Skip to main content

Home/ Dr. Goodyear/ Group items matching "mechanisms" in title, tags, annotations or url

Group items matching
in title, tags, annotations or url

Sort By: Relevance | Date Filter: All | Bookmarks | Topics Simple Middle
Nathan Goodyear

Lowered testosterone in male obesity: Mechanisms, morbidity and management Tang Fui MN, Dupuis P, Grossmann M - Asian J Androl - 0 views

  • The number of overweight people is expected to increase from 937 million in 2005 to 1.35 billion in 2030
  • Similarly the number of obese people is projected to increase from 396 million in 2005 to 573 million in 2030
  • By 2030, China alone is predicted to have more overweight men and women than the traditional market economies combined
  • ...37 more annotations...
  • diacylglycerol O-acyltransferase 2 (DGAT2), mechanistically implicated in this differential storage, [10] is regulated by dihydrotestosterone, [11] suggesting a potential role for androgens to influence the genetic predisposition to either the MHO or MONW phenotype.
  • bariatric surgery achieves 10%-30% long-term weight loss in controlled studies
  • The fact that obese men have lower testosterone compared to lean men has been recognized for more than 30 years
  • Reductions in testosterone levels correlate with the severity of obesity and men
  • epidemiological data suggest that the single most powerful predictor of low testosterone is obesity, and that obesity is a major contributor of the age-associated decline in testosterone levels.
  • healthy ageing by itself is uncommonly associated with marked reductions in testosterone levels
  • obesity blunts this LH rise, obesity leads to hypothalamic-pituitary suppression irrespective of age which cannot be compensated for by physiological mechanisms
  • Reductions in total testosterone levels are largely a consequence of reductions in sex hormone binding globulin (SHBG) due to obesity-associated hyperinsulinemia
  • although controversial, measurement of free testosterone levels may provide a more accurate assessment of androgen status than the (usually preferred) measurement of total testosterone in situations where SHBG levels are outside the reference range
  • SHBG increases with age
  • marked obesity however is associated with an unequivocal reduction of free testosterone levels, where LH and follicle stimulating hormone (FSH) levels are usually low or inappropriately normal, suggesting that the dominant suppression occurs at the hypothalamic-pituitary level
  • adipose tissue, especially when in the inflamed, insulin-resistant state, expresses aromatase which converts testosterone to estradiol (E 2 ). Adipose E 2 in turn may feedback negatively to decrease pituitary gonadotropin secretion
  • diabetic obesity is associated with decreases in circulatory E 2
  • In addition to E 2 , increased visceral fat also releases increased amounts of pro-inflammatory cytokines, insulin and leptin; all of which may inhibit the activity of the HPT axis at multiple levels
  • In the prospective Massachusetts Male Aging Study (MMAS), moving from a non-obese to an obese state resulted in a decline of testosterone levels
  • weight loss, whether by diet or surgery, increases testosterone levels proportional to the amount of weight lost
  • fat is androgen-responsive
  • low testosterone may augment the effects of a hypercaloric diet
  • In human male ex vivo adipose tissue, testosterone decreased adipocyte differentiation by 50%.
  • Testosterone enhances catecholamine-induced lipolysis in vitro and reduces lipoprotein lipase activity and triglyceride uptake in human abdominal adipose tissue in vivo
  • in men with prostate cancer receiving 12 months of androgen deprivation therapy, fat mass increased by 3.4 kg and abdominal VAT by 22%, with the majority of these changes established within 6 months
  • severe sex steroid deficiency can increase fat mass rapidly
  • bidirectional relationship between testosterone and obesity
  • increasing body fat suppresses the HPT axis by multiple mechanisms [30] via increased secretion of pro-inflammatory cytokines, insulin resistance and diabetes; [19],[44] while on the other hand low testosterone promotes further accumulation of total and visceral fat mass, thereby exacerbating the gonadotropin inhibition
  • androgens may play a more significant role in VAT than SAT
  • men undergoing androgen depletion for prostate cancer show more marked increases in visceral compared to subcutaneous fat following treatment
    • Nathan Goodyear
       
      Interesting: low T increases VAT, yet T therapy does not reduce VAT, yet T therapy reduces SAT.
  • irisin, derived from muscle, induces brown fat-like properties in rodent white fat
  • androgens can act via the PPARg-pathway [37] which is implicated in the differentiation of precursor fat cells to the energy-consuming phenotype
  • low testosterone may compound the effect of increasing fat mass by making it more difficult for obese men to lose weight via exercise
  • pro-inflammatory cytokines released by adipose tissue may contribute to loss of muscle mass and function, leading to inactivity and further weight gain in a vicious cycle
  • Sarcopenic obesity, a phenotype recapitulated in men receiving ADT for prostate cancer, [55] may not only be associated with functional limitations, but also aggravate the metabolic risks of obesity;
  • observational evidence associating higher endogenous testosterone with reduced loss of muscle mass and crude measures of muscle function in men losing weight
  • genuine reactivation of the HPT axis in obese men requires more substantial weight-loss
  • A number of intervention studies have confirmed that both diet- and surgically-induced weight losses are associated with increased testosterone, with the rise in testosterone generally proportional to the amount of weight lost
  • men, regardless of obesity level, can benefit from the effect of weight loss.
  • inconsistent effect of testosterone on VAT
  •  
    to be read
Nathan Goodyear

Intratumoral androgen biosynthesis in prostate cancer pathogenesis and response to therapy - 0 views

  • Additional studies have similarly found that prostate tissue levels of DHT in PCa patients treated with ADT therapy before prostatectomy declined by only ∼75% versus declines of ∼95% in serum levels
  • In a recent study in healthy men, treatment for 1 month with a GnRH antagonist to suppress testicular androgen synthesis caused a 94% decline in serum testosterone, but only a 70–80% decline in prostate tissue testosterone and DHT
  • progression to CRPC was associated with increased intratumoral accumulation or synthesis of testosterone.
  • ...9 more annotations...
  • the intraprostatic synthesis of testosterone from adrenal-derived precursors likely accounts for the relatively high testosterone levels in prostate after ADT
  • In addition, AR activity in these cells is likely further enhanced by multiple mechanisms that sensitize AR to low levels of androgens
  • higher affinity ligand DHT (approximately eightfold higher affinity
  • type 2 5α-reductase (SRD5A2) being the major enzyme in prostate
  • reduce DHT to 5α-androstane-3α,17β-diol (3α-androstanediol; Ji et al. 2003, Rizner et al. 2003), which is then glucuronidated to form 3α-androstanediol glucuronide by the enzymes UDP glycosyltransferase 2, B15 (UGT2B15) or UGT2B17
  • DHT in prostate is inactivated by the enzyme AKR1C2, which is also termed 3α-hydroxysteroid dehydrogenase type 3 (3α-HSD type 3
    • Nathan Goodyear
       
      The metabolite 3-alpha androstanediol is NOT inactive as this author states.  This DHT metabolite actually can stimulate  ER alpha receptors in the prostate.
  • AKR1C1, is also expressed in prostate. However, in contrast to AKR1C2, it converts DHT primarily to 5α-androstane-3β,17β-diol (3β-androstanediol; Steckelbroeck et al. 2004), which is a potential endogenous ligand for the estrogen receptor β
  • Significantly, intraprostatic testosterone levels were not substantially reduced relative to controls with normal serum androgen levels, although DHT levels were reduced to 18% of controls
  • testosterone levels in many of the CRPC samples were actually increased relative to control tissues (Montgomery et al. 2008). While DHT levels were less markedly increased, this may have reflected DHT catabolism
  •  
    This article discusses the failure of androgen deprivation therapy and prostate cancer.  This failure is quite common.  The authors point to alpha-DHT as the primary mechanism through AR stimulation.  However, we know that DHT metabolites also stimulate estrogen receptors.
Nathan Goodyear

The Androgen 5α-Dihydrotestosterone and Its Metabolite 5α-Androstan-3β, 17β-Diol Inhibit the Hypothalamo-Pituitary-Adrenal Response to Stress by Acting through Estrogen Receptor β-Expressing Neurons in the Hypothalamus - 0 views

  • Sex steroid hormones are primarily responsible for sex difference in adult HPA function; androgens inhibit whereas estrogens enhance HPA axis activation after a stressor
  • the PVN contains relatively high levels of AR (Bingaman et al., 1994; Zhou et al., 1994) and ERβ (Alves et al., 1998; Hrabovszky et al., 1998; Somponpun and Sladek, 2003) but is essentially devoid of ERα
  • the nonaromatizable androgen DHT and the nonselective ER ligand E2 influence HPA reactivity by acting on neurons within or surrounding the PVN
  • ...9 more annotations...
  • inhibitory action of DHT is detectable at both the level of hormone secretion as well as PVN c-fos mRNA expression
  • the inhibition can be mimicked by the DHT metabolite 3β-diol and by the subtype selective ERβ agonist DPN
  • E2 acts to enhance HPA reactivity
  • the ability of the ER antagonist tamoxifen, but not the AR antagonist flutamide, to block the inhibitory actions of DHT, speaks to the intracellular mechanism by which this inhibitory signal might be transduced.
    • Nathan Goodyear
       
      that is because the interaction with the DHT metabolite is not with the AR, but with the ER-beta.
  • the DHT metabolite 3β-diol and the ERβ-subtype-selective agonist DPN suppressed ACTH, corticosterone, and c-fos mRNA responses to restraint stress in a manner similar to DHT
  • metabolism of DHT to 3β-diol and subsequent binding to ERβ can be inhibitory to HPA reactivity, and this is one possible mechanism for the action of DHT.
  • Our data also suggest that E2 enhances the reactivity of the HPA axis to stress by acting on or near neurons of the PVN
  • the actions of E2 appear to be through an ERα-dependent mechanism
  • these studies suggest that ERβ, within the male hypothalamus, acts to inhibit the HPA axis and that the inhibitory effects of DHT may be, at least in part, via its intracellular conversion to 3β-diol and subsequent binding to ERβ
  •  
    DHT metabolites: particularly 3beta-androstanediol inhibit HPA axis through ER-beta.
Nathan Goodyear

Potential Mechanisms of Estrogen Quinone Carcinogenesis - 0 views

  • 4-hydroxyestrone/estradiol was found to be carcinogenic in the male Syrian golden hamster kidney tumor model, whereas, 2-hydroxylated metabolites were without activity
  • 4-hydroxyestradiol induced uterine tumors in 66% of CD-1 mice; whereas, mice treated with 2-hydroxyestradiol or 17β-estradiol had much lower uterine tumor incidence
  • DNA adducts of catechol estrogen quinones have been detected in the mammary glands of ACI rats treated with 4-hydroxyestradiol or it’s quinone
  •  
    great read on the proposed mechanisms of how estrogen metabolites produce quinone intermediates that are carcinogenic.
wheelchairindia9

Recliner Wheelchair - 0 views

  •  
    Reclining Back Wheelchair( bed cum wheelchair ) which are suitable for indoor as well as outdoor purposes. These wheel chairs are manufactured using high quality material to ensure high strength and durability. Wheelchairs are available in foldable frames and are capable for maximum weight. Reclining wheelchairs are available in standard folding frames with extended head supports and seat widths up to 24" wide. The recline mechanism is attendant operated with levers much like a bicycle brake lever. The levers operate hydraulic (pump) mechanisms for a smooth adjustment. Using this Recliner Wheelchair mechanism, the chair back can easily and frequently be positioned to any angle. Reclining Wheelchair 609 GC: Reclining Wheelchair 609 GC is one of the multipurpose chairs which boast of features like reclining, inbuilt commode, customized armrest and footrest and foldable nature of the chair. Reclining Wheelchair 609 GC Features: The wheelchair can be folded within very easily within seconds, making it easier during travels and outings. The backrest of the chair can be easily reclined, giving the user the freedom to relax by not moving up from the chair. The footrest can be inclined and adjusted so as to make the user comfortable during reclining or otherwise. A well paded thigh support is an add-on to the footrest. The front and rear wheels of the chair are designed and placed in such a way so as to support the reclining of the user, making it a very safe and friendly wheelchair. The inbuilt commode has its seat just underneath the main seat of the chair; it can be used by just removing the main seat. The Wheelchair can also be folded from between by just removing the commode and the chair's seat. This Wheelchair's functionality gives the user total freedom. Easy to fold and unfold within seconds. Reclining Wheelchair 609 GC Measurements: Frame Style : Foldable Frame Material : MS Chrome Plated open position wheel to wheel width in : 26" (inch
Nathan Goodyear

Insulin resistance and Alzheimer's disease. [BMB Rep. 2009] - PubMed result - 0 views

  • there are dual mechanisms of brain insulin resistance leading to AD-type neurodegeneration: one mediated by endogenous, CNS factors; and the other, peripheral insulin resistance with excess cytotoxic ceramide production.
  •  
    Insulin resistance has dual mechanism of contribution to Alzheimer's disease
Nathan Goodyear

Mechanisms of Leptin Action and Leptin Resistance - Annual Review of Physiology, 70(1):537 - 0 views

  • The failure of elevated leptin levels to suppress feeding and mediate weight loss in common forms of obesity defines a state of so-called leptin resistance.
  •  
    mechanisms of Leptin action and Leptin Resistance
Nathan Goodyear

MECHANISMS OF ASCORBATE-INDUCED CYTOTOXICITY IN PANCREATIC CANCER - 0 views

  •  
    Good discussion of the mechanism of action of IV vitamin C in cancer therapy.
Nathan Goodyear

Stuck at the bench: Potential natural neuroprotective compounds for concussion - 0 views

  • Long-chain polyunsaturated fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are highly enriched in neuronal synaptosomal plasma membranes and vesicles
  • The predominant CNS polyunsaturated fatty acid is DHA
  • effective supplementation and/or increased ingestion of dietary sources rich in EPA and DHA, such as cold-water fish species and fish oil, may help improve a multitude of neuronal functions, including long-term potentiation and cognition.
  • ...45 more annotations...
  • multiple preclinical studies have suggested that DHA and/or EPA supplementation may have potential benefit through a multitude of diverse, but complementary mechanisms
  • pre-injury dietary supplementation with fish oil effectively reduces post-traumatic elevations in protein oxidation
  • The benefits of pre-traumatic DHA supplementation have not only been independently confirmed,[150] but DHA supplementation has been shown to significantly reduce the number of swollen, disconnected and injured axons when administered following traumatic brain injury.
  • DHA has provided neuroprotection in experimental models of both focal and diffuse traumatic brain injury
  • potential mechanisms of neuroprotection, in addition to DHA and EPA's well-established anti-oxidant and anti-inflammatory properties
  • Despite abundant laboratory evidence supporting its neuroprotective effects in experimental models, the role of dietary DHA and/or EPA supplementation in human neurological diseases remains uncertain
  • Several population-based, observational studies have suggested that increased dietary fish and/or omega-3 polyunsaturated fatty acid consumption may reduce risk for ischemic stroke in several populations
  • Randomized control trials have also demonstrated significant reductions in ischemic stroke recurrence,[217] relative risk for ischemic stroke,[2] and reduced incidence of both symptomatic vasospasm and mortality following subarachnoid hemorrhage
  • Clinical trials in Alzheimer's disease have also been largely ineffective
  • The clinical evidence thus far appears equivocal
  • curcumin has gained much attention from Western researchers for its potential therapeutic benefits in large part due to its potent anti-oxidant[128,194,236] and anti-inflammatory properties
  • Curcumin is highly lipophilic and crosses the blood-brain barrier enabling it to exert a multitude of different established neuroprotective effects
  • in the context of TBI, a series of preclinical studies have suggested that pre-traumatic and post-traumatic curcumin supplementation may bolster the brain's resilience to injury and serve as a valuable therapeutic option
  • Curcumin may confer significant neuroprotection because of its ability to act on multiple deleterious post-traumatic, molecular cascades
  • studies demonstrated that both pre- and post-traumatic curcumin administration resulted in a significant reduction of neuroinflammation via inhibition of the pro-inflammatory molecules interleukin 1β and nuclear factor kappa B (NFκB)
  • no human studies have been conducted with respect to the effects of curcumin administration on the treatment of TBI, subarachnoid or intracranial hemorrhage, epilepsy or stroke
  • studies have demonstrated that resveratrol treatment reduces brain edema and lesion volume, as well as improves neurobehavioral functional performance following TBI
  • green tea consumption or supplementation with its derivatives may bolster cognitive function acutely and may slow cognitive decline
  • At least one population based study, though, did demonstrate that increased green tea consumption was associated with a reduced risk for Parkinson's disease independent of total caffeine intake
  • a randomized, placebo-controlled trial demonstrated that administration of green tea extract and L-theanine, over 16 weeks of treatment, improved indices of memory and brain theta wave activity on electroencephalography, suggesting greater cognitive alertness
  • Other animal studies have also demonstrated that theanine, another important component of green tea extract, exerts a multitude of neuroprotective benefits in experimental models of ischemic stroke,[63,97] Alzheimer's disease,[109] and Parkinson's disease
  • Theanine, like EGCG, contains multiple mechanisms of neuroprotective action including protection from excitotoxic injury[97] and inhibition of inflammation
  • potent anti-oxidant EGCG which is capable of crossing the blood-nerve and blood-brain barrier,
  • Epigallocatechin-3-gallate also displays neuroprotective properties
  • More recent research has suggested that vitamin D supplementation and the prevention of vitamin D deficiency may serve valuable roles in the treatment of TBI and may represents an important and necessary neuroprotective adjuvant for post-TBI progesterone therapy
  • Progesterone is one of the few agents to demonstrate significant reductions in mortality following TBI in human patients in preliminary trials
  • in vitro and in vivo studies have suggested that vitamin D supplementation with progesterone administration may significantly enhance neuroprotection
  • Vitamin D deficiency may increase inflammatory damage and behavioral impairment following experimental injury and attenuate the protective effects of post-traumatic progesterone treatment.[37]
  • emerging evidence has suggested that daily intravenous administration of vitamin E following TBI significantly decreases mortality and improves patient outcomes
  • high dose vitamin C administration following injury stabilized or reduced peri-lesional edema and infarction in the majority of patients receiving post-injury treatment
  • it has been speculated that combined vitamin C and E therapy may potentiate CNS anti-oxidation and act synergistically with regards to neuroprotection
  • one prospective human study has found that combined intake of vitamin C and E displays significant treatment interaction and reduces the risk of stroke
  • Pycnogenol has demonstrated the ability to slow or reduce the pathological processes associated with Alzheimer's disease
  • Pcynogenol administration, in a clinical study of elderly patients, led to improved cognition and reductions in markers of lipid peroxidase
  • One other point of consideration is that in neurodegenerative disease states like Alzheimer's disease and Parkinson's disease, where there are high levels of reactive oxygen species generation, vitamin E can tend to become oxidized itself. For maximal effectiveness and to maintain its anti-oxidant capacity, vitamin E must be given in conjunction with other anti-oxidants like vitamin C or flavonoids
  • These various factors might account for the null effects of alpha-tocopherol supplementation in patients with MCI and Alzheimer's disease
  • preliminary results obtained in a pediatric population have suggested that post-traumatic oral creatine administration (0.4 g/kg) given within four hours of traumatic brain injury and then daily thereafter, may improve both acute and long-term outcomes
  • Acutely, post-traumatic creatine administration seemed to reduce duration of post-traumatic amnesia, length of time spent in the intensive care unit, and duration of intubation
  • At three and six months post-injury, subjects in the creatine treatment group demonstrated improvement on indices of self care, communication abilities, locomotion, sociability, personality or behavior and cognitive function when compared to untreated controls
  • patients in the creatine-treatment group were less likely to experience headaches, dizziness and fatigue over six months of follow-up
  • CNS creatine is derived from both its local biosynthesis from the essential amino acids methionine, glycine and arginine
  • Studies of patients with CNS creatine deficiency and/or murine models with genetic ablation of creatine kinase have consistently demonstrated significant neurological impairment in the absence of proper creatine, phosphocreatine, or creatine kinase function; thus highlighting its functional importance
  • chronic dosing may partially reverse neurological impairments in human CNS creatine deficiency syndromes
  • Several studies have suggested that creatine supplementation may also reduce oxidative DNA damage and brain glutamate levels in Huntington disease patients
  • Another study highlighted that creatine supplementation marginally improved indices of mood and reduced the need for increased dopaminergic therapy in patients with Parkinson's disease
  •  
    great review of natural therapies in the treatment of concussions
Nathan Goodyear

International Journal of Impotence Research - Mechanisms of action of PDE5 inhibition in erectile dysfunction - 0 views

  • Nitric oxide (NO) is produced from oxygen and L-arginine under the control of nitric oxide synthase (NOS)
  • Cyclic GMP is the intracellular trigger for penile erection
  • PDE5 is the predominant phosphodiesterase in the corpus cavernosum
  •  
    Nice review of the mechanism of action of PDE5 inhibitors and ED.
Nathan Goodyear

Molecular mechanisms of mistletoe plant extract-induced apoptosis in acute lymphoblastic leukemia in vivo and in vitro - ScienceDirect - 0 views

  •  
    Mistletoe induces apoptosis of lymphoblastic leukemic cells in in vivo study. Other studies have pointed to the increase NK activity as the primary mechanism
Nathan Goodyear

Rare Occurrence of 3 "H": Hypercalcemia, Hemolytic Anemia and Hodgkin's Lymphoma - 0 views

  • administered zoledronic acid (4 mg). Prednisolone (1 mg/kg/day) was started and simultaneously, she was administered first cycle of ABVD (Adriamycin: 25 mg/m2, Bleomycin: 10 U/m2, Vinblastine: 6 mg/m2 and Dacarbazine: 375 mg/m2), which led to normalisation of serum calcium levels over 4 days and improvement in her hemoglobin levels
  • Etiology of anemia in Hodgkin’s lymphoma is multifactorial. Anemia of chronic disease, decreased red cell survival, infiltration of bone marrow by tumor and marrow suppression by chemotherapy/radiotherapy are the common mechanisms
  • Our case had only a transient response to steroids and chemotherapy. Therefore, she was treated with Rituximab which brought hemolysis under control
  • ...7 more annotations...
  • Mechanism of hypercalcemia in HL has long been suggested to involve extra-renal activation of 1α-hydroxylase leading to production of 1, 25(OD)2 Vitamin D3 or Calcitriol, an active metabolite of Vitamin D, which leads to increased re-absorption of calcium and phosphate from intestine, increased osteoclast activation and bone resorption as well as increased phosphate re-absorption in renal tubules
  • Hypercalcemia of malignancy involves three mechanisms: 1. Humoral hypercalcemia mediated by PTHrP—seen in solid tumors like breast cancer and adult T cell leukemia/lymphoma (ATLL), 2. Direct osteoclast mediated bone resorption due to bony metastasis—seen in solid tumors and multiple myeloma, 3. Calcitriol mediated hypercalcemia—seen in Hodgkin’s and non-Hodgkin’s lymphoma as well as granulomatous disorders like tuberculosis, sarcoidosis, leprosy and disseminated Candidiasis
  • Hypercalcemia in HL is rare and its incidence has been reported as 0.9, 1.6 and 5.4 % in different series
  • The source of 1α-hydroxylase in HL has been postulated as monocytes and macrophages infiltrating the tumor akin to tuberculosis or sarcoidosis and is stimulated by IFN-γ secreted by T-lymphocytes
  • Like sarcoidosis, patients with HL exhibit increased sensitivity to Vitamin D supplements and sunlight, which have been found to precipitate hypercalcemia in these patients
  • Classical biochemical profile in Calcitriol mediated hypercalcemia include: an elevated calcium, normal/slightly elevated phosphate, normal 25(OH) Vitamin D, suppressed PTHrP and PTH, elevated Calcitriol and a normal/increased tubular reabsorption of phosphate
  • not been associated with a poorer prognosis and tends to subside after treatment of the underlying disease
  •  
    great read on hypercalcemia in hodgkin's lymphoma.
Nathan Goodyear

Anticancer mechanisms of cannabinoids - 0 views

  • modulating key cell signalling pathways involved in the control of cancer cell proliferation and survival
  • cannabinoids inhibit angiogenesis and decrease metastasis in various tumour types in laboratory animals
  • Cannabis sativa L. (marijuana)
  • ...41 more annotations...
  • of the approximately 108 cannabinoids produced by C. sativa, Δ9-tetrahydrocannabinol (thc) is the most relevant because of its high potency and abundance in plant preparations
  • Tetrahydrocannabinol exerts a wide variety of biologic effects by mimicking endogenous substances—the endocannabinoids anandamide3 and 2-arachidonoylglycerol4,5—that engage specific cell-surface cannabinoid receptors
  • the cb2 receptor was initially described to be present in the immune system6, but was more recently shown to also be expressed in cells from other origins
  • transient receptor potential cation channel subfamily V, member 1
  • orphan G protein–coupled receptor 55
  • Most of the effects produced by cannabinoids in the nervous system and in non-neural tissues rely on cb1 receptor activation
  • two major cannabinoid-specific receptors—cb1 and cb2
  • cardiovascular tone, energy metabolism, immunity, and reproduction
  • cannabinoids are well known to exert palliative effects in cancer patients
  • best-established use is the inhibition of chemotherapy-induced nausea and vomiting
  • thc and other cannabinoids exhibit antitumour effects in a wide array of animal models of cancer
  • cannabinoid receptors and their endogenous ligands are both generally upregulated in tumour tissue compared with non-tumour tissue
  • cb2 promotes her2 (human epidermal growth factor receptor 2) pro-oncogenic signalling in breast cancer
  • pharmacologic activation of cannabinoid receptors decreases tumour growth
  • endocannabinoid signalling can also have a tumour-suppressive role
  • pharmacologic stimulation of cb receptors is, in most cases, antitumourigenic. Nonetheless, a few reports have proposed a tumour-promoting effect of cannabinoids
  • most prevalent effect is the induction of cancer cell death by apoptosis and the inhibition of cancer cell proliferation
  • impair tumour angiogenesis and block invasion and metastasis
  • thc and other cannabinoids induce the apoptotic death of glioma cells by cb1- and cb2-dependent stimulation
  • Autophagy is primarily a cytoprotective mechanism, although its activation can also lead to cell death
  • autophagy is important for cannabinoid antineoplastic activity
  • autophagy is upstream of apoptosis in the mechanism of cannabinoid-induced cell death
  • the effect of cannabinoids in hormone- dependent tumours might rely, at least in part, on the ability to interfere with the activation of growth factor receptors
  • glioma cells), pharmacologic blockade of either cb1 or cb2 prevents cannabinoid-induced cell death with similar efficacy
  • other types of cancer cells (pancreatic48, breast24, or hepatic43 carcinoma cells, for example), antagonists of cb2 but not of cb1 inhibit cannabinoid antitumour actions
  • thc promotes cancer cell death in a cb1- or cb2-dependent manner (or both) at lower concentrations
  • cannabidiol (cbd), a phytocannabinoid with a low affinity for cannabinoid receptors15, and other marijuana-derived cannabinoids57 have also been proposed to promote the apoptotic death of cancer cells acting independently of the cb1 and cb2 receptors
  • In cancer cells, cannabinoids block the activation of the vascular endothelial growth factor (vegf) pathway, an inducer of angiogenesi
  • In vascular endothelial cells, cannabinoid receptor activation inhibits proliferation and migration, and induces apoptosis
  • cb1 or cb2 receptor agonists (or both) reduce the formation of distant tumour masses in animal models of both induced and spontaneous metastasis, and inhibit adhesion, migration, and invasiveness of glioma64, breast65,66, lung67,68, and cervical68 cancer cells in culture
  • the ceramide/p8–regulated pathway plays a general role in the antitumour activity of cannabinoids targeting cb1 and cb2
  • cbd, by acting independently of the cb1 and cb2 receptors, produces a remarkable anti-tumour effect—including reduction of invasiveness and metastasis
  • cannabinoids can also enhance immune system–mediated tumour surveillance in some contexts
  • ability of thc to reduce inflammation75,76, an effect that might prevent certain types of cancer
  • recent observations suggest that the combined administration of cannabinoids with other anticancer drugs acts synergistically to reduce tumour growth
  • combined administration of gemcitabine (the benchmark agent for the treatment of pancreatic cancer) and various cannabinoid agonists synergistically reduced the viability of pancreatic cancer cells
  • Other reports indicated that anandamide and HU-210 might also enhance the anticancer activity of paclitaxel89 and 5-fluorouracil90 respectively
  • Combined administration of thc and cbd enhances the anticancer activity of thc and reduces the dose of thc needed to induce its tumour growth-inhibiting activity
  • Preclinical animal models have yielded data indicating that systemic (oral or intraperitoneal) administration of cannabinoids effectively decreases tumour growth
  • Combinations of cannabinoids with classical chemotherapeutic drugs such as the alkylating agent temozolomide (the benchmark agent for the management of glioblastoma80,84) have been shown to produce a strong anticancer action in animal models
  • pharmacologic inhibition of egfr, erk83, or akt enhances the cell-death-promoting action of thc in glioma cultures (unpublished observations by the authors), which suggests that targeting egfr and the akt and erk pathways could enhance the antitumour effect of cannabinoids
  •  
    Good review of the anticancer effects of cananbinoids.
Nathan Goodyear

Ketogenic diets as an adjuvant cancer therapy: History and potential mechanism - 1 views

  •  
    review of science and mechanisms of ketogenic diet and cancer.
Nathan Goodyear

Multiple Myeloma Tumor Cells are Selectively Killed by Pharmacologically-dosed Ascorbic Acid - EBioMedicine - 0 views

  • Recent reports indicate that a certain ROS concentration is required for high-dose vitamin C to induce cytotoxicity in cancer cells.
  • The generation of ascorbyl- and H2O2 radicals by PAA increases ROS stress in cancer cells
  • In this study, we report that PAA is efficacious in killing MM cells in vitro and in vivo models, which generated levels of 20–40 mM ascorbate and 500 nM ascorbyl radicals after intraperitoneal administration of 4 g ascorbate per kilogram of body weight (Chen et al., 2008Chen et al., 2008), in xenograft MM mice
  • ...33 more annotations...
  • These data suggest that PAA may show a therapeutic advantage to blood cancers vs solid tumors because of the communication between tumor cells and blood plasma
  • These results strongly suggest that the mechanism of PAA killing of MM cells is indeed iron-dependent
  • These results suggest that PAA administration in SMM may be able to prevent progression to symtomatic MM
  • A recent study by Yun and colleagues demonstrated that vitamin C selectively kills KRAS and BRAF mutant colorectal cancer cells by targeting GAPDH, but spares normal cells
  • RAS family genes show the most frequent mutations in MM. KRAS, NRAS and BRAF are mutated in 22%, 20% and 7% of MM samples
  • the disease stage rather than the mutation of RAS and/or BRAF is the major predictive factor for PAA sensitivity in MM treatment
  • Other molecular mechanisms including ATP depletion and ATM-AMPK signaling have been reported to explain PAA-induced cell death
  • our pilot study also suggested that PAA could overcome drug resistance to bortezomib in MM cells
  • Our findings complement reported studies and further address the mechanism of action using clinical samples in which we observed that PAA killed tumor cells with high iron content, suggesting that iron might be the initiator of PAA cytotoxicity
  • combination of PAA with standard therapeutic drugs, such as melphalan, may significantly reduce the dose of melphalan needed
  • Combined treatment of reduced dose melphalan with PAA achieved a significantly longer progression-free survival than the same dose of melphalan alone.
  • These data also suggest that the bone marrow suppression induced by high-dose melphalan can be ameliorated by the combination of PAA with lower dose of melphalan because of the lack of toxicity of PAA on normal cells with low iron content.
  • if creatinine clearance is <30 mL/min, high dose ascorbic acid should be not administrated.
  • In MM preclinical and clinical studies, ascorbate was used as an adjunct drug and showed controversial results (Harvey et al., 2009, Perrone et al., 2009, Held et al., 2013, Sharma et al., 2012, Nakano et al., 2011, Takahashi, 2010, Sharma et al., 2009, Qazilbash et al., 2008). However, none of these tests used pharmacological doses of ascorbate and intravenous administration
  • Multiple myeloma (MM) is a plasma cell neoplasm.
  • Cameron and Pauling reported that high doses of vitamin C increased survival of patients with cancer
  • pharmacologically dosed ascorbic acid (PAA) 50–100 g (Chen et al., 2008, Padayatty et al., 2004, Hoffer et al., 2008, Padayatty et al., 2006, Welsh et al., 2013), administered intravenously, has potent anti-cancer activity and its role as anti-cancer therapy is being studied at the University of Iowa and in other centers
  • In the presence of catalytic metal ions like iron, PAA administered intravenously exerts pro-oxidant effects leading to the formation of highly reactive oxygen species (ROS), resulting in cell death
  • the labile iron pool (LIP) is significantly elevated in MM cells
  • The survival of CD138+ cells in vitro was significantly decreased following PAA treatment in all 9 MM
  • In contrast, no significant change of cell viability was observed in CD138− BM cells from the same patients
  • The same effect of PAA was also observed in the SMM patients
  • no response to PAA was detected in CD138+ cells from the 2 MGUS patients
  • the combination of melphalan plus PAA showed greater tumor burden reduction than each drug alone, suggesting a synergistic activity between these two drugs
  • Both catalase and NAC protect cells from oxidative damage
  • cells pretreated with NAC and catalase became resistant to PAA even at high doses
  • adding deferoxamine (DFO), an iron chelator, to OCI-MY5 cells before PAA treatment was also sufficient to prevent PAA-induced cellular death
  • iron is essential for PAA to achieve its anti-cancer activity
  • PAA induced early necrosis (Fig. 3Fig. 3A, 60 min) followed by late apoptosis
  • results further indicated that PAA induced mitochondria-mediated apoptosis
  • PAA by reacting with LIP and generating ROS induces mitochondria-mediated apoptosis in which AIF1 cleavage is important for cell death.
  • ROS and H2O2 are well known factors mediating PAA-induced cancer cell death
  • PAA was sensitive to all 9 MMs and 2 SMMs
  •  
    animal study finds high-dose, pharmacologic vitamin C found to kill multiple myeloma cells via pro-oxidant effect found in similar studies in dealing with different cancers.
Nathan Goodyear

Growth Inhibition of Ovarian Tumor-Initiating Cells by Niclosamide | Molecular Cancer Therapeutics - 0 views

  • Ovarian cancer is the most lethal gynecologic malignancy and the fifth-most cause of overall cancer death of women in developed countries
  • An increasingly accepted cancer stem cell hypothesis regards tumors as caricatures of normal organs, possessing a hierarchy of cell types, at various stages of aberrant differentiation, descended from precursor tumor-initiating cells (TIC) cells that are highly resistant to conventional cytotoxics
  • Significant changes of gene expression in 2,928 genes were identified after niclosamide treatment for different time periods
  • ...14 more annotations...
  • uncoupling of mitochondrial oxidative phosphorylation is believed to be its anti-helminthic mechanism of action
  • we hypothesized that niclosamides antagonistic effects on OTICs could, in part, be due to its disruption of metabolism
  • niclosamide represses metabolic enzymes responsible for bioenergetics, biosynthesis, and redox regulation specifically in OTICs, presumably leading to mitochondrial intrinsic apoptosis pathways, loss of tumor stemness, and growth inhibition
  • niclosamide treatment resulted in a more than 20% increase in reactive oxygen species (ROS) in cultured OTICs
  • niclosamide, which has proved to be safe and effective for the past 2 decades against numerous parasites, inhibited OTIC growth both in vitro and in vivo
  • Our results showed that genes participating in protein complexes of oxidative phosphorylation were downregulated
  • Niclosamide is believed to inhibit mitochondrial oxidative phosphorylation
  • Niclosamide was reported to inactivate NF-κB, causing mitochondrial damage and the generation of ROS, leading to apoptosis of leukemic stem cells
  • niclosamide were identified in a screen for mTOR-signaling inhibitors
  • mTOR was reported to maintain stemness properties of HSCs by inhibiting mitochondrial biogenesis and ROS levels (39), implying that mTOR inhibitors (such as niclosamide) may interfere with mitochondria and various metabolic pathways in TICs via disruption of antioxidant responses
  • We observed Wnt hyperactivity in OTICs, in agreement with previous hypotheses of Wnt inhibitor effectiveness as an ovarian cancer therapy
  • niclosamide has now been independently identified in screens for Wnt inhibitors
  • downregulation of the Wnt/β-catenin target oncogenes survivin and c-Myc
  • ovarian carcinogenesis, the cell-to-cell signaling pathway Notch (8), were also suppressed by niclosamide (data not shown). These results agree with another recent niclosamide study in leukemia (49), and it has been widely hypothesized that disruption of Notch signaling may represent a highly effective therapy for ovarian and other solid tumors, via its essentiality to maintaining TIC stemness
  •  
    Niclosamide, common anti-parasitic medication, inhibits cellular metabolism and increases ROS; both of which provide powerful anti-proliferative, anti-cancer treatment mechanism in TICs. Powerful target therapy for cancer stem cells. Also shown to inhibit Wnt stimulated oncogenes survivin and c-Myc, disrupts Notch signaling, inactivates NF-kappaBeta, and inhibits mTOR-signaling.  This has been found in in vitro and in vivo studies.
Nathan Goodyear

Antineoplastic Mechanisms of Niclosamide in Acute Myelogenous Leukemia Stem Cells: Inactivation of the NF-κB Pathway and Generation of Reactive Oxygen Species | Cancer Research - 0 views

  • Here, we report on niclosamide as an antileukemic agent with two independent antineoplastic mechanisms: NF-κB pathway inactivation and ROS generation
  • In this report, we validated the inhibitory action of niclosamide against tumor necrosis factor (TNF)–induced NF-κB activation in AML cells and identified its mechanism, together with generation of reactive oxygen species (ROS), as being responsible for induced apoptosis of AML cells
  • NF-κB plays a critical role in inflammation, antiapoptotic responses, and carcinogenesis
  • ...8 more annotations...
  • pharmacologic inhibition of NF-κB was effective in killing AML cells
  • High NF-κB expression is found in primitive human AML blast cells
  • niclosamide inhibited the TNF-induced NF-κB reporter activity in a dose- and time-dependent manner
  • niclosamide inhibiting TNF-induced IKK phosphorylation (Fig. 2A), niclosamide may exert its inhibitory effect at the TAK1 step
  • Pretreatment with niclosamide completely blocked the time- and dose-dependent TNFα-induced alteration of the NF-κB–DNA complex
  • niclosamide inhibited constitutively active NF-κB binding to DNA in U266 cells
  • niclosamide completely abolished the TNFα-induced phosphorylation of IKKα/β and IκBα
  • Accordingly, the TNFα-induced degradation of IκBα was abrogated by niclosamide
  •  
    Old anti-parasitic medication, niclosamide, found to have anti-leukemic acitivty through inactivation of NF-kappaB and increase in ROS production in in Vitro and in Vivo study.
Nathan Goodyear

Pharmacological Ascorbate Radiosensitizes Pancreatic Cancer - 0 views

  • Previous studies from our laboratory have demonstrated that pharmacological ascorbate is cytotoxic to pancreatic cancer cells while normal cells are resistant
  • Ascorbate-induced cytotoxicity is mediated by the formation of H2O2 during the oxidation of ascorbate
  • the combination of IR + ascorbate increased the concentration of intracellular H2O2
  • ...17 more annotations...
  • Under steady-state conditions, intracellular GSH is maintained at millimolar concentrations, which keeps cells in a reduced environment and serves as the principal intracellular redox buffer when cells are subjected to an oxidative stressor including H2O2 (26). Glutathione peroxidase (GPx) activity catalyzes the reduction of H2O2 to water with the conversion of GSH to glutathione disulfide (GSSG). Under steady-state conditions, GSSG is recycled back to GSH by glutathione disulfide reductase using reducing equivalents from NADPH. However, under conditions of increased H2O2 flux, this recycling mechanism may become overwhelmed leading to a depletion of intracellular GSH (27, 28).
  • ascorbate radiosensitization can create an overwhelming oxidative stress to pancreatic cancer cells resulting in oxidation/depletion of the GSH intracellular redox buffer, resulting in cell death.
  • Treatment with the combination of ascorbate + IR significantly delayed tumor growth compared to controls or ascorbate alone
  • Ascorbate + IR also significantly increased overall survival compared to controls, IR alone or ascorbate alone
  • 54% of mice treated with the combination of IR + ascorbate had no measurable tumors
  • Glutathione is a measurable marker indicative of the oxidation state of the thiol redox buffer in cells. In severe systemic oxidative stress, the GSSG/2GSH couple may become oxidized, i.e. the concentration of GSH decreases and GSSG may increase because the capacity to recycle GSSG to GSH becomes rate-limiting
  • This suggests that the very high levels of pharmacological ascorbate in these experiments may have a pro-oxidant toward red blood cells as seen by a decrease in the capacity of the intracellular redox buffer
  • These data support the hypothesis that ascorbate radiosensitization does not cause an increase in oxidative damage from lipid-derived aldehydes to other organs.
  • Our current study demonstrates the potential for pharmacological ascorbate as a radiosensitizer in the treatment of pancreatic cancer.
  • pharmacological ascorbate enhances IR-induced cell killing and DNA fragmentation leading to induction of apoptosis in HL60 leukemia cells
  • pharmacological ascorbate significantly decreases clonogenic survival and inhibits the growth of all pancreatic cancer cell lines as a single agent, as well as sensitizes cancer cells to IR
  • Hurst et al. demonstrated that pharmacological ascorbate combined with IR leads to increased numbers of double-strand DNA breaks and cell cycle arrest when compared to either treatment alone
  • pharmacological ascorbate could serve as a “pro-drug” for the delivery of H2O2 to tumors
  • the double-strand breaks induced by H2O2 were more slowly repaired
  • The combination of ascorbate and IR provide two distinct mechanisms of action: ascorbate-induced toxicity due to extracellular production of H2O2 that then diffuses into cells and causes damage to DNA, protein, and lipids; and radiation-induced toxicity as a result of ROS-induced damage to DNA. In addition, redox metal metals like Fe2+ may play an important role in ascorbate-induced cytotoxicity. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of H2O2; labile iron can also react with H2O2. Recently our group has demonstrated that pharmacological ascorbate and IR increase the labile iron in tumor homogenates from this murine model of pancreatic cancer
  • we demonstrated that ascorbate or IR alone decreased tumor growth, but the combination treatment further inhibited tumor growth, indicating that pharmacological ascorbate is an effective radiosensitizer in vivo
  • data suggest that pharmacological ascorbate may protect the gut locally by decreasing IR-induced damage to the crypt cells, and systemically, by ameliorating increases in TNF-α
  •  
    IV vitamin C effective as radiosensitizer in pancreatic cancer.
Nathan Goodyear

Promising role for Gc-MAF in cancer immunotherapy: from bench to bedside - 0 views

  • MAF precursor activity has also been lost or reduced after Gc-globulin treatment in some cancer cell lines
  • This appears to result from the deglycosylated ɑ-N-acetylgalactosaminidase (nagalase) secreted from cancerous cells
  • Nagalase has been detected in many cancer patients, but not in healthy individuals
  • ...31 more annotations...
  • Studies have shown that the production of nagalase has a mutual relationship with Gc-MAF level and immunosuppression
  • It has been demonstrated that serum levels of nagalase are good prognosticators of some types of cancer
  • The nagalase level in serum correlates with tumor burden and it has been shown that Gc-MAF therapy progresses, nagalase activity decreases
  • It has been shown that Gc-MAF can inhibit the angiogenesis induced by pro-inflammatory prostaglandin E1
  • The effect of Gc-MAF on chemotaxis or activation of tumoricidal macrophages is likely the main mechanism against angiogenesis.
  • Administration of Gc-MAF stimulates immune-cell progenitors for extensive mitogenesis, activates macrophages and produces antibodies. “This indicates that Gc-MAF is a powerful adjuvant for immunization.”
  • Cancer cell lines do not develop into tumor genes in mouse models after Gc-MAF-primed immunization (29-31) and the effect of Gc-MAF has been approved for macrophage stimulation for angiogenesis, proliferation, migration and metastatic inhibition on tumors induced by MCF-7 human breast cancer cell line
  • The protocol included: "a high dose of second-generation Gc-MAF (0.5 ml) administered twice a week intramuscularly for a total of 21 injections.”
  • Yamamoto et al. showed that the administration of Gc-MAF to 16 patients with prostate cancer led to improvements in all patients without recurrence
  • Inui et al. reported that a 74-year-old man diagnosed with prostate cancer with multiple bone metastases was in complete remission nine months after initiation of GcMAF therapy simultaneously with hyper T/NK cell, high-dose vitamin C and alpha lipoic acid therapy
  • It has also been approved for non-neoplastic diseases such as autism (41), multiple sclerosis (42, 43), chronic fatigue syndrome (CFS) (40), juvenile osteoporosis (44) and systemic lupus erythematous (45).
  • Gc-MAF has been verified for use in colon, thyroid (38), lung (39), liver, thymus (36), pancreatic (40), bladder and ovarian cancer and tongue squamous carcinoma
  • Prostate, breast, colon, liver, stomach, lung (including mesothelioma), kidney, bladder, uterus, ovarian, head/neck and brain cancers, fibrosarcomas and melanomas are the types of cancer tested thus far
  • weekly administration of 100 ng Gc-MAF to cancer at different stages and types showed curative effects at different follow-up times
  • this treatment has been suggested for non-anemic patients
  • Studies have shown that weekly administration of 100 ng Gc-MAF to cancer patients had curative effects on a variety of cancers
  • Because the half-life of the activated macrophages is approximately one week, it must be administered weekly
  • In vivo weekly intramuscular administration of Gc-MAF (100 ng) for 16-22 weeks was used to treat patients with breast cancer
  • individuals harboring different VDR genotypes had different responses to Gc-MAF and that some genotypes were more responsive than others
  • Administration of Gc-MAF for cancer patients exclusively activates macrophages as an important cell in adaptive immunity
  • Gc-MAF supports humoral immunity by producing, developing and releasing large quantities of antibodies against cancer. Clinical evidence from a human model of breast cancer patients supports this hypothesis
  • There is also evidence that confirms the tumoricidal role of Gc-MAF via Fc-receptor mediation
  • It is likely that the best therapeutic responses will be observed when the nutritional and inflammatory aspects are taken together with stimulation of the immune system
  • it should be noted that no harmful side effects of Gc-MAF treatment have been reported, even when it was successfully administered to autistic children
  • The natural activation mechanism of macrophages by Gc-MAF is so natural and it should not have any side effects on humans or animal models even in cell culture
  • Besides the Gc-MAF efficacy on macrophage activity, it can be a potential anti-angiogenic agent (28) and an inhibitor of the migration of cancerous cells in the absence of macrophages (47).
  • Activating or modifying natural killer cells, dendritic cells, DC, CTL, INF and IL-2 have all been recommended for cancer immunotherapy
  • It has been reported that nagalase cannot deglycosylate Gc-MAF as it has specificity for Gc globulin alone
  • inflammation-derived macrophage activation with the participation of B and T lymphocytes is the main mechanism
  • macrophages highly-activated by the addition of Gc-MAF can show tumoricidal activity
  • Previous clinical investigations have confirmed the efficacy of Gc-MAF. In addition to activating existing macrophages, Gc-MAF is a potent mitogenic factor that can stimulate the myeloid progenitor cells to increase systemic macrophage cell counts by 40-fold in four days
  •  
    great review on Gc-MAF in cancer.  An increase in nagalase blocks Gc-protein to Gc-MAF activity leaving the host immune system compromised.
Nathan Goodyear

Hyperbaric Oxygen Therapy Can Improve Post Concussion Syndrome Years after Mild Traumatic Brain Injury - Randomized Prospective Trial - 0 views

  • The changes in SPECT images after treatment indicate that HBOT led to reactivation of neuronal activity in stunned areas that seemed normal under CT and MRI imaging. While SPECT imaging has a limited spatial resolution (compared, for example, to fMRI), the changes in activity were sufficiently robust to be clearly detected by the SPECT images.
  • HBOT might initiate a cellular and vascular repair mechanism and improve cerebral vascular flow
  • HBOT induces regeneration of axonal white matter [61], [62], [63], [64], has positive effect upon the myelinization and maturation of injured neural fibers [65], and can stimulate axonal growth and increase the ability of neurons to function and communicate with each other
  • ...6 more annotations...
  • HBOT was found to have a role in initiation and/or facilitation of angiogenesis and cell proliferation processes needed for axonal regeneration [67].
  • The observed reactivation of neuronal activity in the stunned areas found here, along with similar results in post-stroke patients
  • At the cellular level, HBOT can improve cellular metabolism, reduce apoptosis, alleviate oxidative stress and increase levels of neurotrophins and nitric oxide through enhancement of mitochondrial function (in both neurons and glial cells)
  • HBOT may promote the neurogenesis of endogenous neural stem cells
  • With regard to secondary injury mechanisms in mTBI, HBOT can initiate vascular repair mechanism and improve cerebral vascular flow [58], [59], [68], [69], promote blood brain barrier integrity and reduce inflammatory reactions [28] as well as brain edema
  • It might be possible that HBOT enables the metabolic change simply by supplying the missing energy/oxygen needed for those regeneration processes.
  •  
    Hbot therapy, according to study, induces neuroplasticity and improves brain function in post concussion syndrome and those with mTBI.  The important point about this study was that the study was done years after the injury; what if the therapy was employed immediately after...
‹ Previous 21 - 40 of 570 Next › Last »
Showing 20 items per page