The investigators sought evidence-based criteria for identifying late-onset hypogonadism in men between the ages of 40 and 79 years on the basis of the association between symptoms and a low ...testosterone level. The data suggest that late-onset hypogonadism can be defined by the presence of at least three sexual symptoms with a total testosterone level of less than 11 nmol per liter and a free testosterone level of less than 220 pmol per liter.
The data suggest that late-onset hypogonadism can be defined by the presence of at least three sexual symptoms with a total testosterone level of less than 11 nmol per liter and a free testosterone level of less than 220 pmol per liter.
The clinical importance of an age-related reduction in the testosterone level
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remains controversial.
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Because of the uncertainty regarding the nature of testosterone deficiency in aging men,
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recent guidelines have suggested that so-called late-onset hypogonadism be regarded as a clinical and biochemical state with advancing age, characterized by particular symptoms and a low level of serum testosterone.
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However, few data on hypogonadism in aging men are available
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because of the lack of evidence regarding the exact criteria for identifying testosterone deficiency in older men who do not have pathological hypogonadism.
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Although a familiar array . . .
Context: The cause of declining testosterone (T) in aging men and their relationships with risk factors are unclear.
Objective: The objective of the study was to investigate the relationships between ...lifestyle and health with reproductive hormones in aging men.
Design: This was a baseline cross-sectional survey on 3200 community-dwelling men aged 40–79 yr from a prospective cohort study in eight European countries.
Results: Four predictors were associated with distinct modes of altered function: 1) age: lower free T (FT; −3.12 pmol/liter·yr, P < 0.001) with raised LH, suggesting impaired testicular function; 2) obesity: lower total T (TT; −2.32 nmol/liter) and FT (−17.60 pmol/liter) for body mass index (BMI; ≥ 25 to < 30 kg/m2) and lower TT (−5.09 nmol/liter) and FT (−53.72 pmol/liter) for BMI 30 kg/m2 or greater (P < 0.001–0.01, referent: BMI < 25 kg/m2) with unchanged/decreased LH, indicating hypothalamus/pituitary dysfunction; 3) comorbidity: lower TT (−0.80 nmol/liter, P < 0.01) with unchanged LH in younger men but higher LH in older men; and 4) smoking: higher SHBG (5.96 nmol/liter, P < 0.001) and LH (0.77 U/liter, P < 0.01) with increased TT (1.31 nmol/liter, P < 0.001) but not FT, compatible with a resetting of T-LH-negative feedback due to elevated SHBG.
Conclusions: Complex multiple alterations in the hypothalamic-pituitary-testicular axis function exist in aging men against a background of progressive age-related testicular impairment. These changes are differentially linked to specific risk factors. Some risk factors operate independently of but others interact with age, in contributing to the T decline. These potentially modifiable risk factors suggest possible preventative measures to maintain T during aging in men.
SARS-CoV-2 is associated with broad tissue tropism, a characteristic often determined by the availability of entry receptors on host cells. Here, we show that TMEM106B, a lysosomal transmembrane ...protein, can serve as an alternative receptor for SARS-CoV-2 entry into angiotensin-converting enzyme 2 (ACE2)-negative cells. Spike substitution E484D increased TMEM106B binding, thereby enhancing TMEM106B-mediated entry. TMEM106B-specific monoclonal antibodies blocked SARS-CoV-2 infection, demonstrating a role of TMEM106B in viral entry. Using X-ray crystallography, cryogenic electron microscopy (cryo-EM), and hydrogen-deuterium exchange mass spectrometry (HDX-MS), we show that the luminal domain (LD) of TMEM106B engages the receptor-binding motif of SARS-CoV-2 spike. Finally, we show that TMEM106B promotes spike-mediated syncytium formation, suggesting a role of TMEM106B in viral fusion. Together, our findings identify an ACE2-independent SARS-CoV-2 infection mechanism that involves cooperative interactions with the receptors heparan sulfate and TMEM106B.
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•TMEM106B directly engages the receptor-binding domain of SARS-CoV-2 spike•Substitution E484D increases TMEM106B binding, enhancing TMEM106B-mediated entry•TMEM106B-specific antibodies neutralize SARS-CoV-2 infection•TMEM106B promotes spike-mediated syncytium formation
The lysosomal transmembrane protein TMEM106B can serve as an alternative receptor for SARS-CoV-2 entry into ACE2-negative cells. Spike substitution E484D improves spike binding to TMEM106B, enhancing TMEM106B-mediated SARS-CoV-2 infection.
Context:
Late-onset hypogonadism (LOH) has been defined as a syndrome in middle-aged and elderly men reporting symptoms in the presence of low testosterone (T).
Objective:
The objective of the study ...was to seek objective biochemical and end-organ evidence of androgen deficiency in men classified as having LOH according to our previously published criteria.
Design, Setting, and Participants:
The design of the study included cross-sectional data from the European Male Aging Study on 2966 community-dwelling men aged 40–79 years in eight European countries.
Main Outcome Measure(s):
Waist circumference, body mass index, muscle mass, estimated heel bone mineral density (eBMD), hemoglobin, insulin sensitivity, physical activity, metabolic syndrome, insulin resistance index, and cardiovascular disease were measured.
Results:
Sixty-three men (2.1%) were classified as having LOH: 36 moderate and 27 severe. They were older and more obese than eugonadal men and had, in proportion to the graded T deficiency, lower muscle mass, eBMD, and hemoglobin, with poorer general health. Both moderate and severe LOH was associated with lower hemoglobin, mid-upper arm circumference, eBMD, physical function (measured by the Short Form-36 questionnaire), slower gait speed and poorer general health. Only men with severe LOH showed significant associations with larger waist circumference (β= 1.93cm; 0.04–3.81), insulin resistance (β= 2.81; 1.39–4.23), and the metabolic syndrome (odds ratio 9.94; 2.73–36.22) after adjustments for confounders. Men with low testosterone only (irrespective of symptoms) showed lesser magnitudes of association with the same end points.
Conclusions:
LOH is associated with multiple end-organ deficits compatible with androgen deficiency. These data support the existence of a syndrome of LOH in only a minority of aging men, especially those with T below 8 nmol/liter.
erectile dysfunction is associated with mortality, whereas the association between low testosterone (T) and higher mortality remains controversial. Sexual dysfunction and low T often coexist, but the ...relative importance of sexual symptoms versus low T in predicting mortality is not known. We studied the interrelationships between sex steroids and sexual symptoms with all-cause mortality in a large prospective cohort of European men.
survival status was assessed in 1,788 community-dwelling men, aged 40-79, who participated in the European Male Ageing Study (EMAS). Sexual symptoms were evaluated via a validated questionnaire (EMAS-SFQ). Sex steroids were measured by mass spectrometry. Cox proportional hazard models were used to study the association between hormones, sexual symptoms and mortality.
about 420 (25.3%) men died during a mean follow-up of 12.6 ± 3.1 years. Total T levels were similar in both groups, but free T was lower in those who died. Men with three sexual symptoms (erectile dysfunction, reduced morning erections and lower libido) had a higher mortality risk compared with men with none of these symptoms (adjusted hazard ratio (HR) and 95% confidence intervals: 1.75 (1.28-2.40, P = 0.001)). Particularly, erectile dysfunction and poor morning erections, but not lower libido, were associated with increased mortality (HR 1.40 (1.13-1.74, P = 0.002), 1.28 (1.04-1.59, P = 0.023) and 1.12 (0.90-1.39, P = 0.312), respectively). Further adjusting for total T, free T or oestradiol did not influence the observed risk.
sexual symptoms, in particular erectile dysfunction, predict all-cause mortality independently of sex steroids and can be an early warning sign of a poor health status.
Context:
During aging, total testosterone (TT) declines and SHBG increases, resulting in a greater decrease in calculated free T (cFT). Currently, guidelines suggest using TT to diagnose androgen ...deficiency and to reserve cFT only for men with borderline TT.
Objective:
Our objective was to investigate if either low cFT or low TT is more strongly associated with androgen-related clinical endpoints.
Methods:
A total of 3334 community-dwelling men, aged 40—79 years, were included in this study. Differences in clinical variables between the referent group of men with both normal TT (≥10.5 nmol/liter) and normal cFT (≥220 pmol/liter) with those who had normal TT/low cFT, low TT/normal cFT, and low TT/low cFT were assessed by regression models adjusted for age, center, body mass index, and comorbidities.
Results:
A total of 2641 men had normal TT (18.4 ± 5.5 mean ± SD nmol/liter)/normal cFT (326 ± 74 pmol/liter), 277 men had normal TT (14.2 ± 3.7)/low cFT (194 ± 23), 96 men had low TT (9.6 ± 0.7)/normal cFT (247 ± 20), and 320 men had low TT (7.8 ± 2.5)/low cFT (160 ± 55). Men with normal TT/low cFT were older and in poorer health. They had higher SHBG and LH and reported more sexual and physical symptoms, whereas hemoglobin and bone ultrasound parameters were lower compared to the referent group. Men with low TT/normal cFT were younger and more obese. They had lower SHBG, but LH was normal, whereas features of androgen deficiency were lacking.
Conclusions:
Low cFT, even in the presence of normal TT, is associated with androgen deficiency-related symptoms. Normal cFT, despite low TT, is not associated with cognate symptoms; therefore, cFT levels should be assessed in men with suspected hypogonadal symptoms.
We studied if low free testosterone (T) or low total T is more strongly associated with androgen-related clinical endpoints. We showed that low free T is associated with hypogonadal signs and symptoms even if total T is normal.
Testosterone concentrations in men are associated with cardiovascular morbidity, osteoporosis, and mortality and are affected by age, smoking, and obesity. Because of serum testosterone's high ...heritability, we performed a meta-analysis of genome-wide association data in 8,938 men from seven cohorts and followed up the genome-wide significant findings in one in silico (n = 871) and two de novo replication cohorts (n = 4,620) to identify genetic loci significantly associated with serum testosterone concentration in men. All these loci were also associated with low serum testosterone concentration defined as <300 ng/dl. Two single-nucleotide polymorphisms at the sex hormone-binding globulin (SHBG) locus (17p13-p12) were identified as independently associated with serum testosterone concentration (rs12150660, p = 1.2×10(-41) and rs6258, p = 2.3×10(-22)). Subjects with ≥ 3 risk alleles of these variants had 6.5-fold higher risk of having low serum testosterone than subjects with no risk allele. The rs5934505 polymorphism near FAM9B on the X chromosome was also associated with testosterone concentrations (p = 5.6×10(-16)). The rs6258 polymorphism in exon 4 of SHBG affected SHBG's affinity for binding testosterone and the measured free testosterone fraction (p<0.01). Genetic variants in the SHBG locus and on the X chromosome are associated with a substantial variation in testosterone concentrations and increased risk of low testosterone. rs6258 is the first reported SHBG polymorphism, which affects testosterone binding to SHBG and the free testosterone fraction and could therefore influence the calculation of free testosterone using law-of-mass-action equation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To characterize the incidence of clinically diagnosed Paget's disease of bone in the UK during 1999-2015 and to determine variations in the incidence of disease by age, sex, geography and level of ...deprivation.
Incident cases of Paget's disease occurring between 1999 and 2015 were identified from primary care records. Overall crude incidence and incidence stratified by age and sex was calculated each year from 1999 to 2015. Direct age- and sex-standardized incidence was also calculated. We used Poisson regression to look at variations in incidence by deprivation and UK region.
A total of 3592 incident cases of Paget's disease were identified between 1999 and 2015. Incidence increased with age and at all ages was greater in men than women. In women and men, respectively, crude incidence increased from 0.037 and 0.074/10 000 population per year among those 45-49 years of age to 3.7 and 6.3/10 000 population per year among those ≥85 years. The overall standardized incidence decreased from 0.75/10 000 person-years in 1999 to 0.20/10 000 person-years in 2015. After adjustment for age and sex, incidence was >30% higher in the most- compared with least-deprived quintile of deprivation. There was evidence of geographic variation, with the highest incidence in the North West of England, which persisted after adjustment for age, sex and level of deprivation.
The incidence of clinically diagnosed Paget's disease has continued to decrease since 1999. The reason for the decline in incidence remains unknown, although the rapidity of change points to an alteration in one or more environmental determinants.
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.
Serum estradiol (E2) and estrone (E1) levels exhibit substantial heritability.
To investigate the genetic regulation of serum E2 and E1 in men.
Genome-wide association study in 11,097 men of European ...origin from nine epidemiological cohorts.
Genetic determinants of serum E2 and E1 levels.
Variants in/near CYP19A1 demonstrated the strongest evidence for association with E2, resolving to three independent signals. Two additional independent signals were found on the X chromosome; FAMily with sequence similarity 9, member B (FAM9B), rs5934505 (P = 3.4 × 10-8) and Xq27.3, rs5951794 (P = 3.1 × 10-10). E1 signals were found in CYP19A1 (rs2899472, P = 5.5 × 10-23), in Tripartite motif containing 4 (TRIM4; rs17277546, P = 5.8 × 10-14), and CYP11B1/B2 (rs10093796, P = 1.2 × 10-8). E2 signals in CYP19A1 and FAM9B were associated with bone mineral density (BMD). Mendelian randomization analysis suggested a causal effect of serum E2 on BMD in men. A 1 pg/mL genetically increased E2 was associated with a 0.048 standard deviation increase in lumbar spine BMD (P = 2.8 × 10-12). In men and women combined, CYP19A1 alleles associated with higher E2 levels were associated with lower degrees of insulin resistance.
Our findings confirm that CYP19A1 is an important genetic regulator of E2 and E1 levels and strengthen the causal importance of E2 for bone health in men. We also report two independent loci on the X-chromosome for E2, and one locus each in TRIM4 and CYP11B1/B2, for E1.
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