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Nathan Goodyear

Transkingdom Control of Microbiota Diurnal Oscillations Promotes Metabolic Homeostasis:... - 0 views

  • in addition to the type of diet being a modulator of microbiota composition, the timing of food intake plays a critical role in shaping intestinal microbial ecology.
  • the microbiota rhythms are influenced by the host clock and perform critical functions in the adaptation of metabolic processes to the diurnal fluctuations in the environment
  • Our study reveals that dysbiosis has a temporal dimension and that static microbiota comparisons might not be fully conclusive unless samples were taken in a controlled manner with respect to this important additional variable
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  • our taxonomic analysis indicates that microbiota oscillations are following rhythmic food intake
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    This is a really nice study.  Altered sleep-wake cycles result in altered food consumption which leads to altered gut microbiota diurnal oscillations.  Gut microbiota have a normal diurnal oscillation.  This altered gut flora then leads to increase insulin resistance, metabolic syndrome, diabetes...
Nathan Goodyear

Diurnal Cortisol Rhythm as a Predictor of Breast Cancer Survival - 0 views

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    Flat and/or abnormal diurnal cortisol patterns found to be associated with earlier mortality in breast cancer.  The flatter cortisol pattern, the earlier the mortality.  Several points here: this highlights the impact of cortisol on the immune system.  Second, this reveals how much of the research has moved to saliva as the gold standard.  This study by the NCI, used salivary cortisol to evaluate the risk of breast cancer survivors.
Nathan Goodyear

Alterations in Diurnal Salivary Cortisol Rhythm in a Population-Based Sample of Cases W... - 0 views

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    low flattened cortisol diurnal salivary pattern and elevated IL-6 found in chronic fatigue patients.  
Nathan Goodyear

Diurnal patterns of salivary cortisol and DHEA in ado... [Stress. 2012] - PubMed - NCBI - 0 views

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    Anorexia nervosa associated with elevated cortisol and DHEA diurnal rhythm.
Nathan Goodyear

STRESS, DIURNAL CORTISOL AND BREAST CANCER SURVIVAL | eCampus CancerPEN - 0 views

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    Stanford University looked at stress, diurnal cortisol pattern and breast cancer survival using...you guessed it, salivary cortisol
Nathan Goodyear

Endocrinology of the Aging Male - 0 views

  • All steps beyond the formation of pregnenolone take place in the smooth endoplasmic reticulum
  • Cytochrome P450 enzyme, CYP11A is located on the inner mitochondrial membrane and catalyses the rate limiting step of pregnenolone synthesis
  • Estrogen and related steroids, thyroid hormone and insulin increase SHBG levels.
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  • SHBG decreases in response to androgens, and in the presence of hypothyroidism, and insulin resistance.
  • Plasma SHBG levels tend to increase with increasing age
  • The apparent metabolic clearance rate of testosterone is decreased in elderly as compared to younger men
  • Testosterone circulates predominantly bound to the plasma proteins SHBG and albumin, with high and low affinity respectively
  • Testosterone is secreted in a pulsatile fashion
  • Current clinical guidelines suggest at least two measurements
  • In adult men, there is a well-documented diurnal variation (particularly in younger subjects) in testosterone levels, which are highest in the early morning and progressively decline throughout the day to a nadir in the evening
  • In older men, the diurnal variation is blunted
  • it is standard practice for samples to be obtained between 0800 and 1100 h.
  • Testosterone and DHEA decline, whereas LH, FSH, and SHBG rise
  • DHT remains constant despite the decline of its precursor testosterone
  • Longitudinal studies show an average annual decline of 1–2% total testosterone levels, with decline in free testosterone more rapid because of increases in SHBG with aging
  • Massachusetts Male Aging Study (MMAS) data show DHEA, DHEAS, and Ae declining at 2–3% per year
  • DHT showed no cross-sectional age trend
  • Androstanediol glucuronide (AAG) declined cross-sectionally with age in the MMAS sample, at 0.6% per year
  • The EMAS data show that, consistent with the longitudinal findings of MMAS (Figure 1), the core hormonal pattern with increasing age is suggestive of incipient primary testicular dysfunction with maintained total testosterone and progressively blunted free testosterone associated with higher LH
    • Nathan Goodyear
       
      This author proves the point in the review of these two studies, that TT may remain constant in aging men, however, FT drops.
  • obesity impairs hypothalamic/pituitary function
  • Androgen deprivation in men with prostate cancer has been associated with increased insulin resistance, worse glycemic control, and a significant increase in risk of incident diabetes
  • Low serum testosterone is associated with the development of metabolic syndrome 116, 117 and type 2 diabetes. 118 SHBG has been inversely correlated with type 2 diabetes
  • Improvement in insulin sensitivity with testosterone treatment has been reported in healthy 121 and diabetic 122 adult men
  • In studies conducted in men with central adiposity, testosterone has been shown to inhibit lipoprotein lipase activity in abdominal adipose tissue leading to decreased triglyceride uptake in central fat depots. 123
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    great review of hormone changes associated with aging in men.
Nathan Goodyear

Reliability of hypothalamic-pituitary-adrena... [Eur J Epidemiol. 2011] - PubMed - NCBI - 0 views

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    Study finds salivary cortisol testing is "reliable" measure of chronic cortisol production.  This study found similarity between diurnal cortisol and dexamethasone suppressed cortisol and adrenal gland volume based on literature review.
Nathan Goodyear

Chemistry and Structural Biology of Androgen Receptor - 0 views

  • Healthy adult men typically produce approximately 3–10 mg of testosterone per day
  • circulating levels ranging from 300 to 700 ng/dL in eugonadal men
  • endogenous testosterone secretion is pulsatile and diurnal
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  • highest concentration occurring at about 8:00 a.m. and the lowest at about 8:00 p.m.
  • Average serum concentrations and diurnal variation in testosterone diminish as men age
  • 40% is sequestered with high affinity to sex hormone-binding globulin (SHBG)
  • almost 60% is bound with low affinity to albumin
  • 2% as free, unbound hormone
  • 5α-DHT has even greater binding affinity to sex hormone-binding globulin than does testosterone
  • 5α-DHT is only about 5% as abundant in the blood as testosterone and is largely derived from peripheral metabolism of testosterone
  • Both 5α-reduction and aromatization are irreversible processes
  • Approximately 90% of an oral dose of testosterone is metabolized before it reaches the systemic circulation
  • there are three modes of action of testosterone. It may directly act through AR in target tissues where 5α-reductase is not expressed, be converted to 5α-DHT (5–10%) by 5α-reductase before binding to AR, or be aromatized to estrogen (0.2%) and act through the estrogen receptor
  • 5α-DHT is a more potent AR ligand than testosterone
  • has 2–10-fold higher potency than testosterone in androgen-responsive tissues
  • estrogen plays a major role in regulating metabolic process,74,75 mood and cognition,76 cardiovascular disease,77,78 sexual function including libido,79 and bone turnover in men
  • Free testosterone is considered the most “biologically active” form
  • testosterone is the major androgen that acts in the “DHT-independent” tissues, such as skeletal muscle, where 5α-reductase is not expressed or is expressed at a very low level
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    good review of androgens and AR.
Nathan Goodyear

ScienceDirect.com - Journal of Chromatography B - Simultaneous determination of salivar... - 0 views

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    LC-MS for salivary testosterone and DHEA validated.  Also, T and DHEA were shown to have specific diurnal rhythms.  Changes in levels were also followed after DHEA therapy.
Nathan Goodyear

Salivary testosterone diurnal variation and psychopathology in adolescent males and fem... - 0 views

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    low testosterone in boys associated with anxiety/depression and attention problems.  Disruptive behavior found in girls with low testosterone.  All determined by salivary testing.
Nathan Goodyear

Diurnal Cortisol Rhythm as a Predictor of Breast Cancer Survival - 0 views

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    In this study, 104 breast cancer patients were evaluated with salivary cortisol.  Those with flat cortisol rhythms had an earlier mortality rate.  Also, NK cells were notably lower in the flat cortisol patients as well.
Nathan Goodyear

Circadian variation in salivary testosterone across age classes in Ache Amerindian male... - 0 views

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    this article looked at normal testosterone rhythm  via saliva.  Normal testosterone peaks in am and is lowest in pm. The normal testosterone rhythm decreases as a man ages.  This is similar results as seen in serum.
Nathan Goodyear

Alterations in diurnal salivary cortisol rhyth... [Psychosom Med. 2008] - PubMed - NCBI - 0 views

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    Individuals with CFS found to have flattened salivary cortisol 4-point pattern and elevated IL-6.
Nathan Goodyear

Diurnal variation of adrenocortical activ... [Neuropsychobiology. 1998] - PubMed - NCBI - 0 views

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    adrenocortical dysfunction found to play a role in CFS
Nathan Goodyear

A prospective study of diurnal cortisol and cognitive function in community-dwelling el... - 0 views

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    High salivary cortisol and decrease metabolism of cortisol (urinary) is associated with increased cognitive decline in the elderly.
Nathan Goodyear

Diurnal Cortisol Dysregulation, Functional Disability, and Depression in Women With Ova... - 0 views

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    with with ovarian cancer, found to have dysregulated cortisol patterns.  Found to be associated with increased rates of depression. Oh, by the way, this study utilized salivary cortisol.
Nathan Goodyear

Vagal Regulation, Cortisol, and Sleep Disruption in Women with Metastatic Breast Cancer - 0 views

  • an association between disrupted nocturnal sleep and flattened diurnal cortisol rhythm in women with metastatic breast cancer
  • They suggest that the stress-buffering effects of sleep may be associated with improved parasympathetic tone and normalized cortisol patterns during the day.
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    women with metastatic breast cancer shown to have more disruption in cortisol pattern and thus dysfunctional sleep.  This has implications on survival.
Nathan Goodyear

Effect of chronic stress associated with unemployment on salivary cortisol: overall cor... - 0 views

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    salivary cortisol used to assess reactions to daily stressors.  
Nathan Goodyear

The Effect of Diurnal Variation on Clinical Measurement of Serum Testosterone and Other... - 0 views

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    Testosterone levels best evaluated in am. This study looked at serum Testosterone levels.
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