Androgen deficiency is associated with obesity, metabolic syndrome, and type 2 diabetes mellitus in men, but the mechanisms behind these associations remain unclear. In this study, we investigated ...the combined effects of androgen deficiency and high-fat diet (HFD) on body composition and glucose homeostasis in C57BL/6J male mice. Two models of androgen deficiency were used: orchidectomy (ORX) and androgen receptor knockout mice. Both models displayed higher adiposity and serum leptin levels upon HFD, whereas no differences were seen on a regular diet. Fat accumulation in HFD ORX animals was accompanied by increased sedentary behavior and occurred in spite of reduced food intake. HFD ORX mice showed white adipocyte hypertrophy, correlated with decreased mitochondrial content but not function as well as increased lipogenesis and decreased lipolysis suggested by the up-regulation of fatty acid synthase and the down-regulation of hormone-sensitive lipase. Both ORX and androgen receptor knockout exacerbated HFD-induced glucose intolerance by impairing insulin action in liver and skeletal muscle, as evidenced by the increased triglyceride and decreased glycogen content in these tissues. In addition, serum IL-1β levels were elevated, and pancreatic insulin secretion was impaired after ORX. Testosterone but not dihydrotestosterone supplementation restored the castration effects on body composition and glucose homeostasis. We conclude that sex steroid deficiency in combination with HFD exacerbates adiposity, insulin resistance, and β-cell failure in 2 preclinical male mouse models. Our findings stress the importance of a healthy diet in a clinical context of androgen deficiency and may have implications for the prevention of metabolic alterations in hypogonadal men.
Sex hormone-binding globulin (SHBG) is the high-affinity binding protein for androgens and estrogens. According to the free hormone hypothesis, SHBG modulates the bioactivity of sex steroids by ...limiting their diffusion into target tissues. Still, the in vivo physiological role of circulating SHBG remains unclear, especially since mice and rats lack circulating SHBG post-natally. To test the free hormone hypothesis in vivo, we examined total and free sex steroid concentrations and bioactivity on target organs in mice expressing a human SHBG transgene. SHBG increased total androgen and estrogen concentrations via hypothalamic-pituitary feedback regulation and prolonged ligand half-life. Despite markedly raised total sex steroid concentrations, free testosterone was unaffected while sex steroid bioactivity on male and female reproductive organs was attenuated. This occurred via a ligand-dependent, genotype-independent mechanism according to in vitro seminal vesicle organ cultures. These results provide compelling support for the determination of free or bioavailable sex steroid concentrations in medicine, and clarify important comparative differences between translational mouse models and human endocrinology.
We describe the case of an adult female patient with symptomatic familial hypocalciuric hypercalcemia requiring a step-wise therapeutic approach and the eventual need for a total parathyroidectomy ...and thyroidectomy to cure symptoms. Genetic analysis demonstrated a heterozygous R227L inactivating
CASR
gene variant, previously only described in neonatal severe hyperparathyroidism. Post-operative histology showed diffuse hyperplasia of all four parathyroid glands along with the presence of intrathyroidal parathyroid tissue. With regard to clinical management this case suggests that familial hypocalciuric hypercalcemia should be classified as an atypical form of primary hyperparathyroidism rather than a distinct entity.
Parathyroid carcinoma (PC) is an extremely rare malignancy, characterized by slow progression, frequent recurrences and difficult-to-control hypercalcemia which is typically the main contributor to ...the morbidity and mortality of these patients. Patients often undergo repeated surgical resections, whether or not in combination with adjuvant radiation treatment. The role of radiation therapy within the symptomatic treatment of PC currently remains unclear.
We describe a 30-year-old male patient with an inoperable local relapse of PC and secondary symptomatic hypercalcemia, maximally pharmacologically treated. After a local radiation treatment to a total dose of 70 Gray in 35 fractions serum calcium and parathyroid hormone (PTH) levels decreased, accompanied by improvement of the severe gastro-intestinal disturbances.
For patients with inoperable symptomatic PC despite maximal medical treatment who are in a good overall condition, radiation treatment can be considered in well-defined cases to decrease symptoms and improve quality of life.
The IFCC Committee for Standardization of Thyroid Function Tests developed a global harmonization approach for thyroid-stimulating hormone measurements. It is based on a multiassay method comparison ...study with clinical serum samples and target setting with a robust factor analysis method. Here we describe the Phase IV method comparison and reference interval (RI) studies conducted with the objective to recalibrate the participating assays and demonstrate the proof-of-concept.
Fourteen manufacturers measured the harmonization and RI panel; 4 of them quantified the harmonization and first follow-up panel in parallel. All recalibrated their assays to the statistically inferred targets. For validation, we used desirable specifications from the biological variation for the bias and total error (TE). The RI measurements were done with the assays' current calibrators, but data were also reported after transformation to the new calibration status. We estimated the pre- and postrecalibration RIs with a nonparametric bootstrap procedure.
After recalibration, 14 of 15 assays met the bias specification with 95% confidence; 8 assays complied with the TE specification. The CV of the assay means for the harmonization panel was reduced from 9.5% to 4.2%. The RI study showed improved uniformity after recalibration: the ranges (i.e., maximum differences) exhibited by the assay-specific 2.5th, 50th, and 97.5th percentile estimates were reduced from 0.27, 0.89, and 2.13 mIU/L to 0.12, 0.29, and 0.77 mIU/L.
We showed that harmonization increased the agreement of results from the participating immunoassays, and may allow them to adopt a more uniform RI in the future.
Context:
Low testosterone (T) has been associated with incident metabolic syndrome (MetS), but it remains unclear if this association is independent of sex hormone binding globulin (SHBG). Estradiol ...(E2) may also be associated with MetS, but few studies have investigated this.
Objective:
To study the association between baseline sex steroids and the development of incident MetS and to investigate the influence of SHBG, body mass index (BMI) and insulin resistance on this risk.
Methods:
Three thousand three hundred sixty nine community-dwelling men aged 40–79 years were recruited for participation in EMAS. MetS was defined by the updated NCEP ATP III criteria. Testosterone and E2 levels were measured by liquid and gas chromatography/mass spectrometry, respectively. Logistic regression was used to assess the association between sex steroids and incident MetS.
Results:
One thousand six hundred fifty one men without MetS at baseline were identified. During follow-up, 289 men developed incident MetS, while 1362 men did not develop MetS. Men with lower baseline total T levels were at higher risk for developing MetS odds ratio (OR) = 1.72, P < .001), even after adjustment for SHBG (OR = 1.43, P = .001), BMI (OR = 1.44, P < .001) or homeostasis model assessment of insulin resistance (HOMA-IR) (OR = 1.64, P < .001). E2 was not associated with development of MetS (OR = 1.04; P = .56). However, a lower E2/T ratio was associated with a lower risk of incident MetS (OR = 0.38; P < .001), even after adjustment for SHBG (OR = 0.48; P < .001), BMI (OR = 0.60; P = .001) or HOMA-IR (OR = 0.41; P < .001).
Conclusions:
In men, lower T levels, but not E2, are linked with an increased risk of developing MetS, independent of SHBG, BMI or insulin resistance. A lower E2/T ratio may be protective against developing MetS.
The analysis of cytokine profiles helps to clarify functional properties of immune cells, both for research and for clinical diagnosis. The real-time reverse transcription polymerase chain reaction ...(RT-PCR) is becoming widely used to quantify cytokines from cells, body fluids, tissues, or tissue biopsies. Being a very powerful and sensitive method it can be used to quantify mRNA expression levels of cytokines, which are often very low in the tissues under investigation. The method allows for the direct detection of PCR product during the exponential phase of the reaction, combining amplification and detection in one single step. In this review we discuss the principle of real-time RT-PCR, the different methodologies and chemistries available, the assets, and some of the pitfalls. With the TaqMan chemistry and the 7700 Sequence Detection System (Applied Biosystems), validation for a large panel of murine and human cytokines and other factors playing a role in the immune system is discussed in detail. In summary, the real-time RT-PCR technique is very accurate and sensitive, allows a high throughput, and can be performed on very small samples; therefore it is the method of choice for quantification of cytokine profiles in immune cells or inflamed tissues.
The IFCC Committee for Standardization of Thyroid Function Tests intended to standardize free thyroxine (FT
) immunoassays. We developed a Système International d'Unités traceable conventional ...reference measurement procedure (RMP) based on equilibrium dialysis and mass spectrometry. We describe here the latest studies intended to recalibrate against the RMP and supply a proof of concept, which should allow continued standardization efforts.
We used the RMP to target the standardization and reference interval (RI) panels, which were also measured by 13 manufacturers. We validated the suitability of the recalibrated results to meet specifications for bias (3.3%) and total error (8.0%) determined from biological variation. However, because these specifications were stringent, we expanded them to 10% and 13%, respectively. The results for the RI panel were reported as if the assays were recalibrated. We estimated all but 1 RI using parametric statistical procedures and hypothesized that the RI determined by the RMP was suitable for use by the recalibrated assays.
Twelve of 13 recalibrated assays had a bias, meeting the 10% specification with 95% confidence; for 7 assays, this applied even for the 3.3% specification. Only 1 assay met the 13% total error specification. Recalibration reduced the CV of the assay means for the standardization panel from 13% to 5%. The proof-of-concept study confirmed our hypothesis regarding the RI but within constraints.
Recalibration to the RMP significantly reduced the FT
immunoassays' bias, so that the RI determined by the RMP was suitable for common use within a margin of 12.5%.
Objective: Perchlorate is a known competitive inhibitor of the sodium/iodide symporter (NIS). Possible thyroid-related effects of environmental perchlorate have created great health concerns, ...especially in the US, resulting in a debated reference dose (RfD) of 0.0007 mg/kg per day in drinking water recommended by the National Academy of Sciences (NAS). However, the impact of other environmental NIS inhibitors and the role of iodine seem to have received little attention in the whole debate. Methods: We performed a PubMed search for articles published up to February 2006, using the key terms perchlorate, nitrate, thiocyanate, iodine, NIS, RfD, thyroid (alone or in combinations), with particular attention for human studies. In parallel, we critically analysed the January 2005 NAS’ report, entitled ‘Health implications of perchlorate ingestion’. Results: The relative potencies of prevalent environmental NIS inhibitors (nitrate, thiocyanate and perchlorate) to inhibit iodine uptake have been estimated repeatedly with robust results. Our calculations show that nitrate and thiocyanate, acquired through drinking water or food, account for a much larger proportion of iodine uptake inhibition than perchlorate. Furthermore, the iodine uptake inhibitory effects of nitrate and thiocyanate – as defined by their legally accepted maximal contaminant levels in drinking water – exceed the potential effect of the proposed RfD for perchlorate by far. Conclusions: Iodine uptake inhibition and any potential downstream effect by perchlorate are highly dependent on the presence of other environmental NIS inhibitors and iodine intake itself. These potential confounders should therefore be considered in future studies and calculations for risk assessment.
The need for a routinely applicable assay to measure low estradiol levels in adult men, postmenopausal women, and young adolescents was recently discussed in an Endocrine Society position statement. ...Our aim was to develop a sensitive liquid chromatography–tandem mass spectrometry method for estradiol and estrone in human serum without the need for derivatization or extended extraction protocols. After protein precipitation of serum with a mixture of methanol/acetonitrile (85/15) (
v
/
v
) containing isotopic internal standards (17β-estradiol-16,16,17-
d
3
and estrone-2,3,4-
13
C), we quantified estradiol and estrone by two-dimensional liquid chromatography–tandem mass spectrometry with electrospray ionization in the negative mode monitoring 5 × 271.20→145.00 (17β-estradiol) and 269.20→145.00 (estrone). Sensitivity was increased by using fluoride and summation of 5 identical transitions for estradiol. Our method was analytically validated, compared against direct immunoassays using serum of 25 adult men, and clinically tested by measuring samples of 3 men at baseline and after chemical castration, 30 postmenopausal women and 15 patients receiving aromatase inhibitors. Total imprecision was below 20 % for the low quality controls. Limit of quantification was 1.3 ng/L (4.8 pmol/L) for estradiol and 1.2 ng/L (4.4 pmol/L) for estrone. Estradiol in Certified Reference Material BCR-576 was within specified uncertainty limits. No significant ion suppression or interference was observed. Our method showed modest correlation with direct immunoassay for estradiol (
r
2
= 0.64) but no correlation for estrone (
r
2
= 0.12). Patient sample results were within expected ranges. In conclusion, we developed a routinely applicable liquid chromatography–tandem mass spectrometry method for estradiol and estrone measurement which is sensitive enough for use in men, postmenopausal women, and young adolescents.
Figure
Chromatogram of E2 in serum with S/N for one MRM and for the summation of 5 identical MRMs
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