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Clostridium scindens: a human gut microbe with a high potential to convert glucocortico... - 0 views

  • During the enterohepatic circulation (EC), bile salts are synthesized in the liver, concentrated in the gallbladder, and function in the lumen of the small intestine to absorb dietary lipids and limit microbial growth at the site of nutrient uptake
  • Bile acid 7α/β-dehydroxylating bacteria are organisms capable of converting primary bile acids made by the host to harmful secondary bile acids, deoxycholic acid, and lithocholic acid
  • These bacteria normally comprise a small proportion of the gut microbiota (∼103–104/g wet weight) and consist of species within the genus Clostridium
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  • C. scindens and a small number of species belonging to the genus Clostridium are responsible for significant alterations in the human bile acid pool composition through bile acid 7α/β dehydroxylation
  • bile acids play an important role in maintaining intestinal barrier function as antimicrobial agents in the small bowel (37, 38) and inducers of antimicrobial peptides
  • Perturbations in the biliary bile acid pool composition can be indicative of hepatogastrointestinal diseases such as fat malabsorption (40), gallstones (3), gastrointestinal cancers (41), and possibly type II diabetes
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    Gut microbiota appears to be source of androgen production that originates from the gut.  Who would have thought that the Gut as an androgen producing endocrine gland.
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Bacteria in the Intestine, Helpful Residents or Enemies from Within? - 0 views

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    To be read
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IN THIS ISSUE - The Journal of Immunology - 0 views

  • t has been suggested that increased permeability of intestinal epithelial tight junctions (TJ) in these diseases is mediated by proinflammatory cytokines including IL-1β,
  • Al-Sadi et al. (p. 5653 ) hypothesized that myosin light chain kinase (MLCK), which is known to be important for intestinal TJ permeability, could mediate IL-1β-induced disruption of the epithelial barrier
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    Heavy article on immune system activation
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The Intestinal Microbiota Affect Central Levels of Brain-Derived Neurotropic Factor and... - 0 views

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    Gut and Brain linked together
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Hypercalcemia of malignancy and new treatment options - 0 views

  • Hypercalcemia of malignancy occurs as the result of direct bone metastasis and via humoral mechanisms such as parathyroid hormone-related protein (PTHrP) or 1,25-dihydroxyvitamin D mediated pathways
  • ectopic secretion of parathyroid hormone (PTH) has been implicated
  • Hypercalcemia due to osteolytic bone lesions is common in multiple myeloma, leukemia, and breast cancer
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  • Humoral hypercalcemia is predominant in squamous cell, renal cell and ovarian cancers, and lymphomas are associated with 1,25-dihydroxyvitamin D mediated hypercalcemia
  • 20% of cases of hypercalcemia of malignancy and is frequently encountered in multiple myeloma, metastatic breast cancer, and to a lesser extent in leukemia and lymphoma
  • Physiologic bone turnover requires the complementary activity of osteoblasts – mesenchymal stem cell-derived bone-forming cells – and bone-resorbing cells of monocyte and macrophage lineage known as osteoclasts
  • In local osteolytic hypercalcemia, the RANKL/RANK interaction results in excessive osteoclast activation leading to enhanced bone resorption and thus hypercalcemia
  • In addition, osteoclast activation is also mediated by malignancy secreted cytokines, including interleukin-1, initially termed “osteoclast stimulating factor”
  • Macrophage inflammation protein 1-alpha (MIP 1-alpha)
  • hypercalcemia is through extra-renal 1,25-dihydroxyvitamin D (calcitriol) production
  • 1% of cases
  • increased production of 1,25-dihydroxyvitamin D occurs nearly exclusively in Hodgkin and non-Hodgkin lymphoma with case reports of the same in ovarian dysgerminoma
  • 1-α-hydroxylase in the kidney, a process regulated by PTH
  • in 1,25-dihydroxyvitamin D induced hypercalcemia, malignant cells likely recruit and induce adjacent macrophages to express 1-α-hydroxylase, converting endogenous calcidiol into calcitriol.31 Calcitriol then binds to receptors in the intestine leading to heightened enteric calcium reabsorption with resultant hypercalcemia
  • this mechanism of disease is best conceptualized as an absorptive form of hypercalcemia
  • Ectopic production of PTH by malignant cells has been described in a handful of cases involving cancer of the ovary and lung, as well as neuroendocrine tumors and sarcoma
  • primary hyperparathyroidism and malignancy comprising nearly 90% of cases of hypercalcemia
  • an initial panel consisting of PTH, PTHrP, phosphorus, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D should be obtained
  • Lymphoma, a hypercalcemia due to 1,25-dihydroxyvitamin D mediated pathways, is implied by elevations in 1,25-dihydroxyvitamin D without concomitant elevations in 25-hydroxyvitamin D. In such cases, PTH is low and PTHrP undetectable
  • Treatment of hypercalcemia of malignancy is aimed at lowering the serum calcium concentration by targeting the underlying disease, specifically by inhibiting bone resorption, increasing urinary calcium excretion, and to a lesser extent by decreasing intestinal calcium absorption
  • mildly symptomatic disease
  • marked symptoms
  • hydration with isotonic fluid (if admitted), avoidance of thiazide diuretics, and a low-calcium diet
  • denosumab
  • Denosumab is an RANKL antibody that inhibits osteoclast maturation, activation, and function
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    hypercalcemia in cancer and treatments.
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Appendicitis: Causes, Symptoms and Treatment | Health Blog - 0 views

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    What Is Appendicitis? How to diagnose Appendicitis? Where is Appendix pain located In this article, we hope you can find all of your answers related to Appendicitis. We covered everything about Appendicitis. We discussed types, causes, symptoms, tests, and treatment of Appendicitis.
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    Appendicitis is an inflammation of the appendix, which is a small tube of intestinal tissue that projects from the large intestine. While the appendix does not seem to have a particular function, one theory suggests that it acts as a storehouse of good bacteria and boosts immunity after diarrheal illness. However, some experts believe the appendix is just a purposeless remnant from our evolutionary past. One thing we're sure of is that we can live without it, without any apparent consequences.
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The river blindness drug Ivermectin and related macrocyclic lactones inhibit WNT-TCF pa... - 0 views

  • WNT signaling
  • early colon cancers commonly display loss of function of the tumor suppressor Adenomatous polyposis coli (APC), a key component of the β-CATENIN destruction complex
  • Other cancers also show an active canonical WNT pathway; these include carcinomas of the lung, stomach, cervix, endometrium, and lung as well as melanomas and gliomas
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  • In normal embryogenesis and homeostasis, the canonical WNT pathway is activated by secreted WNT ligands produced in highly controlled context-dependent manners and in precise amounts. WNT activity is transduced in the cytoplasm, inactivates the APC destruction complex, and results in the translocation of activate β-CATENIN to the nucleus, where it cooperates with DNA-binding TCF/LEF factors to regulate WNT-TCF targets and the ensuing genomic response
  • beyond the loss of activity of the APC destruction complex, for instance throughAPC mutation, phosphorylation of β-CATENIN at C-terminal sites is required for the full activation of WNT-TCF signaling and the ensuing WNT-TCF responses in cancer.
  • The WNT-TCF response blockade that we describe for low doses of Ivermectin suggests an action independent to the deregulation of chloride channels
  • involve the repression of the levels of C-terminally phosphorylated β-CATENIN forms and of CYCLIN D1, a critical target that is an oncogene and positive cell cycle regulator.
  • the Avermectin single-molecule derivative Selamectin, a drug widely used in veterinarian medicine (Nolan & Lok, 2012), is ten times more potent acting in the nanomolar range
  • Ivermectin also diminished the protein levels of CYCLIN D1, a direct TCF target and oncogene, in both HT29 and H358 tumor cells
  • Activated Caspase3 was used as a marker of apoptosis by immunohistochemistry 48 h after drug treatment. Selamectin and Ivermectin induced up to a sevenfold increase in the number of activated Caspase3+ cells in two primary (CC14 and CC36) and two cell line (DLD1 and Ls174T) colon cancer cell types (Fig​(Fig2C).2C). All changes were significative
  • The strong downregulation of the expression of the intestinal stem cell genesASCL2 andLGR5 (van der Flieret al, 2009; Scheperset al, 2012; Zhuet al, 2012b) by Ivermectin and Selamectin (Fig​(Fig2D)2D) raised the possibility that these drugs could affect WNT-TCF-dependent colon cancer stem cell behavior
  • Pre-established H358 tumors responded to Ivermectin showing a ˜ 50% repression of growth
  • Ivermectin hasin vivo efficacy against human colon cancer xenografts sensitive to TCF inhibition with no discernable side effects
  • Ivermectin (Campbellet al, 1983), an off-patent drug approved for human use, and related macrocyclic lactones, have WNT-TCF pathway response blocking and anti-cancer activities
  • these drugs block WNT-TCF pathway responses, likely acting at the level of β-CATENIN/TCF function, affecting β-CATENIN phosphorylation status.
  • anti-WNT-TCF activities of Ivermectin and Selamectin
  • Ivermectin has a well-known anti-parasitic activity mediated via the deregulation of chloride channels, leading to paralysis and death (Hibbs & Gouaux, 2011; Lynagh & Lynch, 2012). The same mode of action has been suggested to underlie the toxicity of Ivermectin for liquid tumor cells and the potentiation or sensitization effect of Avermectin B1 on classical chemotherapeutics
  • the specificity of the blockade of WNT-TCF responses we document, at low micromolar doses for Ivermectin and low nanomolar doses for Selamectin, indicate that the blockade of WNT-TCF responses and chloride channel deregulation are distinct modes of action
  • What is key then is to find a dose and a context where the use of Ivermectin has beneficial effects in patients, paralleling our results with xenografts in mice.
  • Cell toxicity appears at doses greater (> 10 μM for 12 h or longer or > 5 μM for 48 h or longer for Ivermectin) than those required to block TCF responses and induce apoptosis.
  • Our data point to a repression of WNT-β-CATENIN/TCF transcriptional responses by Ivermectin, Selamectin and related macrocylic lactones.
  • (i) The ability of Avermectin B1 to inhibit the activation of WNT-TCF reporter activity by N-terminal mutant (APC-insensitive) β-CATENIN as detected in our screen
  • (ii) The ability of Avermectin B1, Ivermectin, Doramectin, Moxidectin and Selamectin to parallel the modulation of WNT-TCF targets by dnTCF
  • (iii) The finding that the specific WNT-TCF response blockade by low doses of Ivermectin and Selamectin is reversed by constitutively active TCF
  • (iv) The repression of key C-terminal phospho-isoforms of β-CATENIN resulting in the repression of the TCF target and positive cell cycle regulator CYCLIN D1 by Ivermectin and Selamectin
  • (v) The specific inhibition ofin-vivo-TCF-dependent, but notin-vivo-TCF-independent cancer cells by Ivermectin in xenografts.
  • These results together with the reduction of the expression of the colon cancer stem cell markersASCL2 andLGR5 (e.g., Hirschet al, 2013; Ziskinet al, 2013) raise the possibility of an inhibitory effect of Ivermectin, Selamectin and related macrocyclic lactones on TCF-dependent cancer stem cells.
  • the capacity of cancer cells to form 3D spheroids in culture, as well as the growth of these, is also WNT-TCF-dependent (Kanwaret al, 2010) and they were also affected by Ivermectin treatment
  • If Ivermectin is specific, it should only block TCF-dependent tumor growth. Indeed, the sensitivity and insensitivity of DLD1 and CC14 xenografts to Ivermectin treatment, respectively, together with the desensitization to Ivermectin actionin vivo by constitutively active TCF provide evidence of the specificity of this drug to block an activated WNT-TCF pathway in human cancer.
  • Ivermectin has a good safety profile since onlyin-vivo-dnTCF-sensitive cancer xenografts are responsive to Ivermectin treatment, and we have not detected side effects in Ivermectin-treated mice at the doses used
  • previous work has shown that side effects from systemic treatments with clinically relevant doses in humans are rare (Yang, 2012), that birth defects were not observed after exposure of pregnant mothers (Pacquéet al, 1990) and that this drug does not cross the blood–brain barrier (Kokozet al, 1999). Similarly, only dogs with mutantABCB1 (MDR1) alleles leading to a broken blood–brain barrier show Ivermectin neurotoxicity (Mealeyet al, 2001; Orzechowskiet al, 2012)
  • Indications may include treatment for incurable β-CATENIN/TCF-dependent advanced and metastatic human tumors of the lung, colon, endometrium, and other organs.
  • Ivermectin, Selamectin, or related macrocyclic lactones could also serve as topical agents for WNT-TCF-dependent skin lesions and tumors such as basal cell carcinomas
  • they might also be useful as routine prophylactic agents, for instance against nascent TCF-dependent intestinal tumors in patients with familial polyposis and against nascent sporadic colon tumors in the general aging population
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    Ivermectin, a common anti-parasitic, found to inhibit WTF-TCF pathway and decrease c-terminal phosophorylaiton of Beta-CATENIN all resulting in increased aptosis and inhibition of cancer growth in colon cancer cell lines and lung cancer cell lines.
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Cancers | Free Full-Text | A Second WNT for Old Drugs: Drug Repositioning against WNT-D... - 0 views

  • To date nearly half of known human tumors show a dysregulation of the WNT signaling pathway
  • It should be also noted that the WNT pathway is not exclusively employed during development or overactivated in cancer. In adults many healthy tissues rely on it for renewal and homeostasis maintenance, most notably the intestine, haematopoietic system, hair, bones and skin. Therefore one might expect adverse reactions in all these organ systems, which has indeed been observed for many WNT-targeting compounds upon attempts to push them into the clinics
  • The intestine seems to be the most vulnerable in this regard
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  • Ivermectin inhibits proliferation of human colon cancer and lung cancer cells both in vitro and in vivo
  • The anti-proliferative action, affecting both the bulk tumor cells and CSCs, was linked in this study to inhibition of WNT signaling
  • the anti-WNT IC50 of ivermectin is 5–10 times (~1–2 µM vs. 10 µM) lower than that of its toxic effect against chloride channels
  • oral bioavailability of the drug, as for other antiparasitic drugs discussed in this section, is very low
  • Toxicity studies in vivo have also demonstrated a wide therapeutic index for ivermectin
  • Its anti-proliferative activity has been demonstrated in a wide array of cancer cell lines representative of WNT-dependent cancers: non-small lung carcinoma [96], multiple myeloma [97], hepatoma [98], adrenocortical carcinoma [99], ovarian cancer [100] and glioblastoma
  • Niclosamide inhibits the canonical WNT pathway
  • In addition to inhibiting the canonical WNT pathway, niclosamide may mediate its anticancer activities through several other signaling pathways such as NOTCH [107], MTOR [108], NF-κB [97] and STAT3 [96]
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    review article highlights older medications that have anti-Wnt pathway effects in cancer.  Roughly, 50% of cancer involve upregulated Wnt pathway activity. Other drugs of note: metformin
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How is the Immune System Suppressed by Cancer - 1 views

  • nitric oxide (NO) released by tumor cells
  • Excellent work by Prof de Groot of Essen, indicated by adding exogenous xanthine oxidase ( XO) in hepatoma cells, hydrogen peroxide was produced to destroy the hepatoma cells
  • NO from eNOS in cancer cells can travel through membranes and over long distances in the body
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  • NO also is co linked to VEGF which in turn increases the antiapoptotic gene bcl-2
  • The other important influence of NO is in its inhibition of the proapoptoic caspases cascade. This in turn protects the cells from intracellular preprogrammed death.
  • nitric oxide in immune suppression in relation to oxygen radicals is its inhibitory effect on the binding of leukocytes (PMN) at the endothelial surface
  • Inhibition of inducible Nitric Oxide Synthase (iNOS)
  • NO from the tumor cells actually suppresses the iNOS, and in addition it reduces oxygen radicals to stop the formation of peroxynitrite in these cells. But NO is not the only inhibitor of iNOS in cancer.
  • Spermine and spermidine, from the rate limiting enzyme for DNA synthases, ODC, also inhibit iNOS
  • tolerance in the immune system that decreases the immune response to antigens on the tumors
  • Freund’s adjuvant
  • increase in kinases in these cells which phosphorylate serine, and tyrosine
  • responsible for activation of many growth factors and enzymes
  • phosphorylated amino acids suppress iNOS activity
  • Hexokinase II
  • Prostaglandin E2, released from tumor cells is also an inhibitor of iNOS, as well as suppressing the immune system
  • Th-1 subset of T-cells. These cells are responsible for anti-viral and anti-cancer activities, via their cytokine production including Interleukin-2, (IL-2), and Interleukin-12 which stimulates T-killer cell replication and further activation and release of tumor fighting cytokines.
    • Nathan Goodyear
       
      Th1 cells stimulate NK and other tumor fighting macrophages via IL-2 and IL-12; In contrast, Th2, which is stimulated in allergies and parasitic infections, produce IL-4 and IL-10.  IL-4 and IL-10 inhibit TH-1 activation and the histamine released from mast cell degranulation upregulates T suppressor cells to further immune suppression.
  • Th-2 subset of lymphocytes, on the other hand are activated in allergies and parasitic infections to release Interleukin-4 and Interleukin-10
  • These have respectively inhibitory effects on iNOS and lymphocyte Th-1 activation
  • Mast cells contain histamine which when released increases the T suppressor cells, to lower the immune system and also acts directly on many tumor Histamine receptors to stimulate tumor growth
  • Tumor cells release IL-10, and this is thought to be one of the important areas of Th-1 suppression in cancer patients
  • IL-10 is also increased in cancer causing viral diseases such as HIV, HBV, HCV, and EBV
  • IL-10 is also a central regulator of cyclooxygenase-2 expression and prostaglandin production in tumor cells stimulating their angiogenesis and NO production
  • nitric oxide in tumor cells even prevents the activation of caspases responsible for apoptosis
    • Nathan Goodyear
       
      NO produced by cancer cells inhibits proapoptotic pathways such as the caspases.
  • early stages of carcinogenesis, which we call tumor promotion, one needs a strong immune system, and fewer oxygen radicals to prevent mutations but still enough to destroy the tumor cells should they develop
  • later stages of cancer development, the oxygen radicals are decreased around the tumors and in the tumor cells themselves, and the entire cancer fighting Th-1 cell replication and movement are suppressed. The results are a decrease in direct toxicity and apoptosis, which is prevented by NO, a suppression of the macrophage and leukocyte toxicity and finally, a suppression of the T-cell induced tumor toxicity
  • cGMP is increased by NO
  • NO in cancer is its ability to increase platelet-tumor cell aggregates, which enhances metastases
  • the greater the malignancies and the greater the metastatic potential of these tumors
  • The greater the NO production in many types of tumors,
  • gynecological
  • elevated lactic acid which neutralizes the toxicity and activity of Lymphocyte immune response and mobility
  • The lactic acid is also feeding fungi around tumors and that leads to elevated histamine which increases T-suppressor cells.  Histamine alone stimulates many tumor cells.
    • Nathan Goodyear
       
      The warburg effect in cancer cells results in the increase in local lactic acid production which suppresses lymphocyte activity and toxicity as well as stimulates histamine production with further stimulates tumor cell growth.
  • T-regulatory cells (formerly,T suppressor cells) down regulate the activity of Natural killer cells
  • last but not least, the Lactic acid from tumor cells and acidic diets shifts the lymphocyte activity to reduce its efficacy against cancer cells and pathogens in addition to altering the bacteria of the intestinal tract.
  • intestinal tract bacteria in cancer cells release sterols that suppress the immune system and down regulate anticancer activity from lymphocytes.
  • In addition to the lactic acid, adenosine is also released from tumors. Through IL-10, adenosine and other molecules secreted by regulatory T cells, the CD8+ cells can be inactivated to an anergic state
  • Adenosine up regulates the PD1 receptor in T-1 Lymphocytes and inhibits their activity
  • Adenosine is a purine nucleoside found within the interstitial fluid of solid tumors at concentrations that are able to inhibit cell-mediated immune responses to tumor cells
  • Adenosine appears to up-regulate the PD1 receptor in T-1 Lymphocytes and inhibits the immune system further
  • Mast cells with their release of histamine lower the immune system and also stimulate tumor growth and activate the metalloproteinases involved in angiogenesis and metastases
  • COX 2 inhibitors or all trans-retinoic acid
  • Cimetidine, an antihistamine has been actually shown to increase in apoptosis in MDSC via a separate mechanism than the antihistamine effect
    • Nathan Goodyear
       
      cimetidine is an H2 blocker
  • interleukin-8 (IL-8), a chemokine related to invasion and angiogenesis
  • In vitro analyses revealed a striking induction of IL-8 expression in CAFs and LFs by tumor necrosis factor-alpha (TNF-alpha)
  • these data raise the possibility that the majority of CAFs in CLM originate from resident LFs. TNF-alpha-induced up-regulation of IL-8 via nuclear factor-kappaB in CAFs is an inflammatory pathway, potentially permissive for cancer invasion that may represent a novel therapeutic target
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    Great review of the immunosuppression in cancer driven by the likes of NO.
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Gut barrier function and systemic endotoxemia after laparotomy or laparoscopic resectio... - 0 views

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    Surgery increases systemic endotoxin levels via increase in intestinal permeability.
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Ascorbate in pharmacologic concentrations selectively generates ascorbate radical and h... - 0 views

  • Proposed mechanism
  • The data show that pharmacologic ascorbate concentrations produced Asc•− selectively in extracellular fluid compared with blood and that H2O2 formation occurred when Asc•− concentrations were >100 nM in extracellular fluid.
  • These data validate the hypothesis that ascorbate is a prodrug for selective delivery of reactive species to the extravascular space
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  • pharmacologic ascorbate as a prooxidant drug for therapeutic use.
  • Recently we reported that pharmacologic ascorbic acid concentrations produced H2O2 concentrations of ≥25 μM, causing cancer cell death in vitro
  • We found that H2O2 concentrations generated in vivo were those that caused cancer cell death in vitro
  • When ascorbate was given parenterally, Asc•−, the product of a loss of one electron from ascorbate, was detected preferentially in extracellular fluid compared with blood
  • Asc•− generation in extracellular fluid depended on the ascorbate dose and the resulting concentrations
  • With i.v. administration of ascorbate, Asc•− concentrations were as much as 12-fold greater in extracellular fluid compared to blood and approached 250 nM
  • In blood, such Asc•− concentrations were never produced and were always <50 nM
  • These data are all consistent with the hypothesis that pharmacologic ascorbate concentrations in vivo serve as a prodrug for selective delivery of H2O2 to the extracellular space
  • After oral ingestion, control of intracellular and extracellular ascorbate concentrations is mediated by three mechanisms: intestinal absorption, tissue transport, and renal reabsorption
  • intestinal absorption, or bioavailability, declines at doses >200 mg
    • Nathan Goodyear
       
      significant limitation of gut absorption of vitamin C--at 200 mg po.
  • corresponding to plasma concentrations of ≈60 μM
    • Nathan Goodyear
       
      equates to 0.06 mM.  Max blood levels found with po AA dosing has been 0.22 mM
  • at approximately this concentration, the ascorbate tissue transporter SVCT2 approaches Vmax, and tissues appear to be saturated
    • Nathan Goodyear
       
      SVCT2 Rc in gut reach max binding.
  • also at ≈60 μM, renal reabsorption approaches saturation, and excess ascorbate is excreted in urine
  • Parenteral administration bypasses tight control
  • When tight control is bypassed, H2O2 forms in the extracellular space
  • in vivo validation of ascorbate as a prodrug for selective H2O2 formation
  • Temporarily bypassing tight control with parenteral administration of ascorbate allows H2O2 to form in discrete time periods only, decreasing likelihood of harm, and provides a pharmacologic basis for therapeutic use of i.v. ascorbate
  • H2O2 formation results in selective cytotoxicity
  • Tumor cells are killed with exposure to H2O2 for ≤30 min
  • In vitro, killing is mediated by H2O2 rather than Asc•−
  • In addition to cancer treatment, another potential therapeutic use is for treatment of infections. H2O2 concentrations of 25–50 μM are bacteriostatic
  • virally infected cells may also be candidates
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    follow up invivo study to previous study from 2005.  Here, the authors prove their hypothesis that ascorbate is a prodrug for delivery of H2O2.
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Plasma lipoproteins: composition, structure and biochemistry - 0 views

  • triacylglycerols
  • The most abundant lipid constituents are triacylglycerols, free cholesterol, cholesterol esters and phospholipids (phosphatidylcholine and sphingomyelin especially ), though fat-soluble vitamins and anti-oxidants are also transported in this way
  • the lipoprotein aggregates should be described in terms of the different protein components or apoproteins (or 'apolipoproteins'
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  • Density is determined largely by the relative concentrations of triacylglycerols and proteins and by the diameters of the broadly spherical particles
  • these classes can be further refined by improved separation procedures, and intermediate-density lipoproteins (IDL) and subdivisions of the HDL (e.g. HDL1, HDL2, HDL3 and so forth
  • the main groups are classified as chylomicrons (CM), very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL) and high-density lipoproteins (HDL), based on the relative densities of the aggregates on ultracentrifugation
  • the various lipid components should not be considered as absolute, as they are in a state of constant flux
  • Apo A1 is the main protein component of HDL
  • Apo A2 is the second most important HDL apolipoprotein
  • Lipoproteins are spherical (VLDL, LDL, HDL) to discoidal (nascent HDL) in shape with a core of non-polar lipids, triacylglycerols and cholesterol esters, and a surface monolayer, ~20Å thick, consisting of apoproteins, phospholipids and non-esterified cholesterol, which serves to present a hydrophobic face to the aqueous phase
  • The lipoproteins can be categorised simplistically according to their two main metabolic functions. The principal role of the chylomicrons and VLDL is to transport triacylglycerols ‘forward’ as a source of fatty acids from the intestines or liver to the peripheral tissues. In contrast, the HDL remove excess cholesterol from peripheral tissues and deliver it to the liver for excretion in bile in the form of bile acids (‘reverse cholesterol transport’). While these functions are considered separately here for convenience, it should be recognised that the processes are highly complex and inter-related, and they involve transfer of apoproteins, enzymes and lipid constituents among the heterogeneous mix of all the lipoprotein fractions.
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    Awesome review of apolipoproteins, their function, and their metabolism.
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Testosterone: a metabolic hormone in health and disease - 0 views

  • E2 and the inflammatory adipocytokines tumour necrosis factor α (TNFα) and interleukin 6 (IL6) inhibit hypothalamic production of GNRH and subsequent release of LH and FSH from the pituitary
  • Leptin, an adipose-derived hormone with a well-known role in regulation of body weight and food intake, also induces LH release under normal conditions via stimulation of hypothalamic GNRH neurons
  • In human obesity, whereby adipocytes are producing elevated amounts of leptin, the hypothalamic–pituitary axis becomes leptin resistant
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  • there is evidence from animal studies that leptin resistance, inflammation and oestrogens inhibit neuronal release of kisspeptin
  • Beyond hypothalamic action, leptin also directly inhibits the stimulatory action of gonadotrophins on the Leydig cells of the testis to decrease testosterone production; therefore, elevated leptin levels in obesity may further diminish androgen status
  • Prostate cancer patients with pre-existing T2DM show a further deterioration of insulin resistance and worsening of diabetic control following ADT
  • ADT for the treatment of prostatic carcinoma in some large epidemiological studies has been shown to be associated with an increased risk of developing MetS and T2DM
  • Non-diabetic men undergoing androgen ablation show increased occurrence of new-onset diabetes and demonstrate elevated insulin levels and worsening glycaemic control
  • increasing insulin resistance assessed by glucose tolerence test and hypoglycemic clamp was shown to be associated with a decrease in Leydig cell testosterone secretion in men
  • The response to testosterone replacement of insulin sensitivity is in part dependent on the androgen receptor (AR)
  • Low levels of testosterone have been associated with an atherogenic lipoprotein profile, characterised by high LDL and triglyceride levels
  • a positive correlation between serum testosterone and HDL has been reported in both healthy and diabetic men
  • up to 70% of the body's insulin sensitivity is accounted for by muscle
  • Testosterone deficiency is associated with a decrease in lean body mass
  • relative muscle mass is inversely associated with insulin resistance and pre-diabetes
  • GLUT4 and IRS1 were up-regulated in cultured adipocytes and skeletal muscle cells following testosterone treatment at low dose and short-time incubations
  • local conversion of testosterone to DHT and activation of AR may be important for glucose uptake
  • inverse correlation between testosterone levels and adverse mitochondrial function
  • orchidectomy of male Wistar rats and associated testosterone deficiency induced increased absorption of glucose from the intestine
  • (Kelley & Mandarino 2000). Frederiksen et al. (2012a) recently demonstrated that testosterone may influence components of metabolic flexibility as 6 months of transdermal testosterone treatment in aging men with low–normal bioavailable testosterone levels increased lipid oxidation and decreased glucose oxidation during the fasting state.
  • Decreased lipid oxidation coupled with diet-induced chronic FA elevation is linked to increased accumulation of myocellular lipid, in particular diacylglycerol and/or ceramide in myocytes
  • In the Chang human adult liver cell line, insulin receptor mRNA expression was significantly increased following exposure to testosterone
  • Testosterone deprivation via castration of male rats led to decreased expression of Glut4 in liver tissue, as well as adipose and muscle
  • oestrogen was found to increase the expression of insulin receptors in insulin-resistant HepG2 human liver cell line
  • FFA decrease hepatic insulin binding and extraction, increase hepatic gluconeogenesis and increase hepatic insulin resistance.
  • Only one, albeit large-scale, population-based cross-sectional study reports an association between low serum testosterone concentrations and hepatic steatosis in men (Völzke et al. 2010)
  • This suggests that testosterone may confer some of its beneficial effects on hepatic lipid metabolism via conversion to E2 and subsequent activation of ERα.
  • hypogonadal men exhibiting a reduced lean body mass and an increased fat mass, abdominal or central obesity
  • visceral adipose tissue was inversely correlated with bioavailable testosterone
  • there was no change in visceral fat mass in aged men with low testosterone levels following 6 months of transdermal TRT, yet subcutaneous fat mass was significantly reduced in both the thigh and the abdominal areas when analysed by MRI (Frederiksen et al. 2012b)
  • ADT of prostate cancer patients increased both visceral and subcutaneous abdominal fat in a 12-month prospective observational study (Hamilton et al. 2011)
  • Catecholamines are the major lipolysis regulating hormones in man and regulate adipocyte lipolysis through activation of adenylate cyclase to produce cAMP
  • deficiency of androgen action decreases lipolysis and is primarily responsible for the induction of obesity (Yanase et al. 2008)
  • may be some regional differences in the action of testosterone on subcutaneous and visceral adipose function
  • proinflammatory adipocytokines IL1, IL6 and TNFα are increased in obesity with a downstream effect that stimulates liver production of CRP
  • observational evidence suggests that IL1β, IL6, TNFα and CRP are inversely associated with serum testosterone levels in patients
  • TRT has been reported to significantly reduce these proinflammatory mediators
  • This suggests a role for AR in the metabolic actions of testosterone on fat accumulation and adipose tissue inflammatory response
  • testosterone treatment may have beneficial effects on preventing the pathogenesis of obesity by inhibiting adipogenesis, decreasing triglyceride uptake and storage, increasing lipolysis, influencing lipoprotein content and function and may directly reduce fat mass and increase muscle mass
  • Early interventional studies suggest that TRT in hypogonadal men with T2DM and/or MetS has beneficial effects on lipids, adiposity and parameters of insulin sensitivity and glucose control
  • Evidence that whole-body insulin sensitivity is reduced in testosterone deficiency and increases with testosterone replacement supports a key role of this hormone in glucose and lipid metabolism
  • Impaired insulin sensitivity in these three tissues is characterised by defects in insulin-stimulated glucose transport activity, in particular into skeletal muscle, impaired insulin-mediated inhibition of hepatic glucose production and stimulation of glycogen synthesis in liver, and a reduced ability of insulin to inhibit lipolysis in adipose tissue
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    Great review of the Hypogonadal-obesity-adipocytokine hypothesis.
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Understanding lipoproteins as transporters of cholesterol and other lipids - 0 views

  • the density of each lipoprotein is clearly in a constant state of flux
  • Two lipoprotein fractions are primarily involved in transport of lipid to peripheral tissues, very low density lipoproteins (VLDL) from the liver and chylomicrons from the intestinal tract
  • As lipid is removed from these two fractions, the density of each fraction increases, thereby transforming VLDL into intermediate-density lipoprotein (IDL) and ultimately LDL, and chylomicrons into chylomicron remnants
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  • LDL-cholesterol has been described, and overly simplified, as “bad cholesterol” and HDL-cholesterol as “good cholesterol.”
  • Two primary subfractions of HDL have been classified as the higher-density HDL3, and the less dense, more lipid-filled HDL2
  • HDL, is primarily involved in returning lipid, largely cholesterol, to the liver in a process called reverse cholesterol transport
  • Recent investigations are also suggesting that smaller, denser lipoproteins are associated with increased risk of atherosclerotic development
  • lipoproteins as transporters of lipid
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    Brief, but good review of lipoproteins and apoliproteins.
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Beta Glucan: Health Benefits in Obesity and Metabolic Syndrome - 0 views

  • beta glucan (β-glucan), which is a dietary fiber readily found in oat and barley bran
  • Among cereals, the highest content (g per 100 g dry weight) of β-glucan has been reported for barley: 2–20 g (65% is water-soluble fraction) and for oats: 3–8 g (82% is water-soluble fraction). Other cereals also contain β-glucan but in much lower amounts: sorghum 1.1–6.2 g, rye 1.3–2.7 g, maize 0.8–1.7 g, triticale 0.3–1.2 g, wheat 0.5–1.0 g, durum wheat 0.5-0.6 g, and rice 0.13 g
  • Other sources of β-glucan include some types of seaweed [17] and various species of mushrooms such as Reishi, Shiitake, and Maitake [18].
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  • Distinction between soluble and insoluble dietary fibers is based on the solubility characteristics of dietary fiber in hot aqueous buffer solutions
  • Insoluble fibers primarily consist of cellulose and some hemicelluloses, resistant starch, and chitin while soluble fibers include pectins, β-glucans, galactomannan gums, mucilages, and some hemicelluloses
  • insoluble fibers increase fecal bulk and the excretion of bile acids and decrease intestinal transit time
  • Soluble fibers increase total transit time by delaying gastric emptying and also slow glucose absorption
  • only soluble viscous fibers delay gastric emptying time and slow glucose absorption while nonviscous soluble fibers primarily act as a substrate for microbial fermentation in the colon
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    good review on Beta glucan.
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The Gut Microbiota and Type 1 Diabetes - 0 views

  • A study by Bosi and colleagues suggested that the increased gut permeability preceded the clinical onset of T1D
  • gut permeability may be an important player in the development of T1D but, as yet, the findings in human studies have shown association but causation will be more difficult to prove.
  • Early childhood (≤ 3 month) introduction to cereals [10, 11] and cow's milk [48] were shown to promote beta cell autoimmunity
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  • These findings suggest that prebiotics and probiotics could be potential therapeutic tools to improve gut integrity in various intestinal inflammatory and autoimmune diseases including T1D
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    another great review article of gut dysbiosis, altered gut permeability and type I diabetes.
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Prolonged antibiotic treatment induces a diabetogenic intestinal microbiome that accele... - 0 views

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    Only abstract available here.  Animal study finds that gut bacteria induce diabetes and early antibiotic exposure accelerated this autoimmune activity.  This study also used VSL#3 to attempt to treat but no effect was evident.  
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Gut Endotoxin Leading to a Decline IN Gonadal function (GELDING) - a novel theory for t... - 0 views

  • GELDING theory (Gut Endotoxin Leading to a Decline IN Gonadal function)
  • trans-mucosal passage of bacterial lipopolysaccharide (LPS) from the gut lumen into the circulation is a key inflammatory trigger underlying male hypogonadism
  • Obesity and a high fat/high calorie diet are both reported to result in changes to gut bacteria and intestinal wall permeability, leading to the passage of bacterial endotoxin (lipopolysaccharide- LPS) from within the gut lumen into the circulation (metabolic endotoxaemia), where it initiates systemic inflammation.
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  • Endotoxin is known to reduce testosterone production by the testis, both by direct inhibition of Leydig cell steroidogenic pathways and indirectly by reducing pituitary LH drive, thereby also leading to a decline in sperm production.
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    Ever heard of the GELDING theory?  This involves the link between LPS endotoxin from the gut and low Testosterone in obese men.
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Cell Host and Microbe - Microbiota Regulate Intestinal Absorption and Metabolism of Fat... - 0 views

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    You are what you eat...you are what your gut eats.  Confirmation of the influence of the GI microbiota on calorie utilization.   We shouldn't be surprised by this: what do we do to cattle?  we give them antibiotics which increases their weight and time to market.  What are we doing to ourselves?
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