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Home/ Dr. Goodyear/ Contents contributed and discussions participated by Nathan Goodyear

Contents contributed and discussions participated by Nathan Goodyear

Nathan Goodyear

Selenium in soil and endemic diseases in China. - PubMed - NCBI - 0 views

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    Selenium deficiencies, selenosis, lead to disease.
Nathan Goodyear

The antioxidant role of selenium and seleno-compounds. - PubMed - NCBI - 0 views

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    Selenium (Se) deficiency is associated with increased oxidative stress.  Selenium is a cofactor necessary for glutathione perioxidase.  Selenium reduced 8-OHdG, promoted cell growth inhibition and cell death pointing to significant Cancer implications.
Nathan Goodyear

Cellular and Molecular Basis of Deiodinase-Regulated Thyroid Hormone Signaling - 0 views

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    Anything and everything one would want to know regarding thyroid hormone signaling.  Doctors, especially endocrinologists, need to read this.  T4 is not or is ever inside target cells.  The enzymes, deiodinase types 1, 2, and 3, are what control the thyroid hormone at the cellular levels.  Deiodinase-2 is what generates T3 in the cytosol of the cell.  In contrast, deiodinase-3 is what generates rT3 which is inactive.  High Fat diet increases deiodinase-3.
Nathan Goodyear

Plant-derived 3,3′-Diindolylmethane Is a Strong Androgen Antagonist in Human ... - 0 views

  • Inhibition of Endogenous PSA Expression by DIM
  • DIM strongly inhibited DHT induction of androgen-responsive genes by more than 50%
  • antiandrogenic activity of DIM
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  • DIM suppresses DHT-induced cell growth and PSA expression and exhibits no AR agonist activity
  • DIM has a strong affinity for both the mutant AR inLNCaP cells and for recombinant wild-type human AR
  • nuclear translocation and foci formation of DHT-bound AR are inhibited by DIM
  • Our investigation, leads to the conclusion that DIM is a strong, pure androgen antagonist.
  • The down-regulation of PSA by DIM
  • PSA has been reported to promote the proliferation, migration, and metastasis of prostate cancer cells through several mechanisms, including cleavage of insulin-like growth factor-binding protein-3 and degradation of extracellular matrix proteins fibronectin and laminin
  • PSA expression is regulated by the AR and is thought to function as a growth factor in LNCaP cells
  • down-regulation of PSA expression may be important in the antiproliferative effects of DIM in LNCaP cells
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    DIM, from cruciferous veggies often used to aid estrogen metabolism, is found to decrease PSA transcription and function as an androgen receptor antagonist in prostate cancer cell lines.
Nathan Goodyear

http://press.endocrine.org/doi/pdf/10.1210/jc.2014-2585 - 0 views

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    Cross sectional study finds that 1/3 of men with type II diabetes have low T via serum.  Low T correlated with higher IMT and hs-CRP.
Nathan Goodyear

Association of androgen-deprivation therapy with excess cardiac-specific mortality in m... - 0 views

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    Androgen Deprivation Therapy, ADT,  is associated with increased cardiovascular mortality in men with pre-existing CVD.  This has also been shown to be the case with IR, Diabetes, weight gain...What man 40+ with prostate cancer doesn't have some degree of CVD??
Nathan Goodyear

Androgen Therapy in Women: A Reappraisal: An Endocrine Society Clinical Practice Guidel... - 0 views

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    A recommendation that I agree with: Very little data available for Testosterone in women requires significant restraint and recommendation to limit use of Testosterone in women.
Nathan Goodyear

Glucagon Stimulation Testing in Assessing for Adult Growth Hormone Deficiency: Current ... - 0 views

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    the Glucagon Stim test is a useful alternative to the ITT for HGH deficiency evaluation.
Nathan Goodyear

Diagnosing Growth Hormone Deficiency in Adults - 0 views

  • it is clear that serum IGF-1 and or IGFBP-3 can be normal in patients with undisputed GHD
  • Various investigators have reported normal IGF-1 values in 37–70% of GH deficient adults
  • The co-administration of arginine and GHRH (the combined test) is a powerful stimulus for GH production and has gained increasing acceptance as a useful method of diagnosing GHD [34]. This test has been advocated as a suitable alternative to ITT
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  • The glucagon stimulation test (GST) is a reliable, safe alternative to the ITT in the diagnosis of GHD
  • An intravenous infusion of arginine (0.5 g/kg body weight) together with an intravenous bolus of GHRH (1 mcg/kg body weight) is administered [30]. Serum samples for GH are then obtained every 15–30 minutes for two hours.
  • Obesity, particularly marked obesity, is associated with blunted GH secretion in response to provocative stimuli
  • It has also been suggested that that even mildly increased BMI (25–30 kg/m2) can result in diminished stimulated GH production in 13% of healthy subjects
  • Corneli et al. have defined BMI-specific cut-off points for diagnosing adult-onset GHD using GHRH + arginine—11.5 ng/mL for those with BMI < 25 kg/m2, 8.0 ng/mL for BMI 25–30 kg/m2, 4.2 ng/mL for those with BMI > 30 kg/m2
  • GH levels are higher during the luteal phase in comparison with the follicular phase of the cycle
  • Oral, in contrast to transdermal oestrogen, lowers IGF-1 levels and is associated with increased GH levels
  • Adequate pituitary replacement with thyroxine and hydrocortisone are needed for optimal GH production
  • one cannot rely on a low IGF-1 to diagnose GHD in women taking oral oestrogen preparations.
  • Numerous GH secretagogues are available with the insulin tolerance test being the gold standard and the glucagon stimulation test or the GHRH + arginine as acceptable alternatives
  • ain et al. found the GST to be at least as good as the ITT in provoking GH secretion
  • the GST is safe, with almost no contraindications, it causes nausea and sometimes vomiting in 15–20% of subjects
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    Nice, more recent analysis, of HGH testing.
Nathan Goodyear

Which Patients Do Not Require a GH Stimulation Test for the Diagnosis of Adult GH Defic... - 0 views

  • Four studies have reported that the probability of GHD (peak GH criteria ranging from < 2.3 to < 5 μg/liter) in patients with three to four PHDs ranges from 91% to 100%
  • 95% accuracy by the presence of either three or more PHDs or a serum IGF-I concentration less than 84 μg/lite
  • adult GHD could be predicted with 95% accuracy by the presence of either three or four PHDs or a serum IGF-I concentration less than 84 μg/liter
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  • Hypopituitary adults with GHD have been reported to have normal serum IGF-I levels in 37–70% of patients in various studies (5, 9, 18, 21, 22). This is owing in part to the fact that multiple factors regulate serum IGF-I concentrations including nutritional status; hepatic and renal function; and circulating concentrations of thyroid hormone, androgens, and estrogens
  • changes in concentrations of IGF-binding proteins (IGFBPs) influence the total concentration of IGF-I in plasma
  • Among patients with an IGF-I sd score above −1 in the present study, 46% had a peak GH less than 2.5 μg/liter and 67% had a peak GH less than 5 μg/liter.
  • In summary, adult GHD can be predicted with 95% accuracy by the presence of either three or four PHDs or a serum IGF-I concentration less than 84 μg/liter
  • We propose that adult patients with three or four PHDs (three or four of the following deficiencies: TSH, ACTH, gonadotropins [LH and/or FSH], and AVP [central diabetes insipidus]) do not require a GH stimulation test to make the diagnosis of adult GHD
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    Insulin Tolerance Test is the gold standard for HGH diagnosis, but this an unpopular test do to long list of side effects.  This study finds a 95% accuracy for IGF-1 less than 84 with 3 or more coexisting pituitary hormone deficiencies.
Nathan Goodyear

Sensitivity and specificity of six tests for the diagnosis of adult... - PubMed - NCBI - 0 views

  • ARG plus GHRH test, high sensitivity (96 and 95%, respectively) and specificity (92 and 91%, respectively) for GH deficiency were achieved
  • The greatest diagnostic accuracy occurred with the ITT and the ARG plus GHRH test
  • 95% specificity could be achieved with the ARG plus L-DOPA and ARG tests only with very low peak GH cut-points (0.25 and 0.21 microg/liter, respectively) and not at all with the L-DOPA test
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  • Although serum IGF-I levels provided less diagnostic discrimination than all five GH stimulation tests, a value below 77.2 microg/liter was 95% specific for GH deficiency
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    study evaluated 6 tests for HGH deficiency diagnosis.  Ninety-five percent specificity found with ARG + l-DOPA and ARG alone.  However, the authors found a 95% specificity with IGF-1 < 77.  Although, IGF-1 is false negative in up to 65% of those with HGH deficiency.
Nathan Goodyear

https://www.endocrine.org/~/media/endosociety/Files/Publications/Clinical%20Practice%20... - 0 views

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    Current recommendations on HGH origin, evaluation, and therapy.
Nathan Goodyear

Testosterone Substitution Normalizes Elevated Serum Leptin Levels in Hypogonadal Men: T... - 0 views

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    Men with low T and elevated Leptin, have Leptin normalized with Testosterone therapy.  In obese men, Leptin is inversely associated with Testosterone.  This points to more cause/effect relationship with low T, elevated Leptin, and obesity in men.
Nathan Goodyear

Pituitary-adrenocortical function in abdominal obesity of males: ev... - PubMed - NCBI - 0 views

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    Obesity associated with decreased adrenal 21alpha-hydroxylase activity.  The result is decreased cortisol production in obese individuals.  
Nathan Goodyear

Reduced testosterone and adrenal C19 steroid levels in obese men. - PubMed - NCBI - 0 views

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    Decreased adrenal steroid production occurred in men with obesity.  Estrone positively correlated.
Nathan Goodyear

Inhibition of sex hormone-binding globulin production in the human ... - PubMed - NCBI - 0 views

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    Insulin and Prolactin inhibit liver SHBG production.  Testosterone, Estradiol and T4 stimulate SHBG in in vitro study.
Nathan Goodyear

The activity of satellite cells and myonuclei following 8 weeks of ... - PubMed - NCBI - 0 views

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    Though, studies have shown that resistance training increases Testosterone production, this study finds that artificial suppression of Testosterone reduced myogenic response to 8 weeks of resistance training.
Nathan Goodyear

Hypogonadal symptoms in young men are associated with a serum total... - PubMed - NCBI - 0 views

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    Study looked at the threshold of symptoms of hypogonadism in men < 40 based on serum Testosterone levels.  The study found the prominent symptom was fatigue and the cut off Total Testosterone level was < 400 ng/dl.
Nathan Goodyear

http://www.diabetologia-journal.org/files/Narendran.pdf - 0 views

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    Exercise is not just for calories out.  Exercise increases growth hormone, IGF-1, glucagon-like peptide 1, IL-6, and IL-1ra.  The effect is to GH increases beta islet cell mass and protects beta cell lines against IL-1beta, Interferon-gamma and TNF-alhpa induced apoptosis.  IL-6 increased production increases GLP-1 and IL-1ra which counters IL-1beta.  Interleukin-1beta induces islet cell apoptosis and thus IL-1ra counters this pro-inflammatory signal.
Nathan Goodyear

Sex Hormone-Binding Globulin and the Free Androgen Index Are Related to Cardiovascular ... - 0 views

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    The opposite effect strikes again: elevated free androgen index is associated with CV risk in perimenopause women across 5 ethnic groups.  Low SHBG was associated with increased CVD.
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