A genome-wide association study identifies a novel locus on chromosome 18q12.2 influencing white cell telomere length

Background:

Telomere length is a predictor for a number of common age related diseases and is a heritable trait.

Methods and results:

To identify new loci associated with mean leukocyte telomere length we conducted a genome wide association study of 314 075 single nucleotide polymorphisms (SNPs) and validated the results in a second cohort (n for both cohorts combined  =  2790). We identified two novel associated variants (rs2162440, p = 2.6×10⁻⁶; and rs7235755, p = 5.5×10⁻⁶) on chromosome 18q12.2 in the same region as the VPS34/PIKC3C gene, which has been directly implicated in the pathway controlling telomere length variation in yeast.

Conclusion:

These results provide new insights into the pathways regulating telomere homeostasis in humans.

Allelic variation at the interleukin-1 receptor antagonist gene is associated with early postmenopausal bone loss at the spine

Genetic factors play an important role in determining bone mineral density (BMD) in later life, with the genetic influence mediated through effects on both peak mass and on age- and menopause-related bone loss. At menopause there is an increase in the production and activity of various cytokines and growth factors within the bone microenvironment. The activity of interleukin-1 (IL-1), a powerful stimulant of osteoclastic bone resorption, is increased in estrogen-deficient states with increased production of IL-1 and inhibition of the IL-1 receptor antagonist (IL-1ra). Treatment with IL-1ra blocks the bone loss associated with ovariectomy in animals and the IL-1 receptor antagonist gene (IL-1RN) is therefore a potential candidate gene for the regulation of postmenopausal bone loss. We examined the relationship between annual rates of change in BMD over 5 years and an 86 bp variable number tandem-repeat polymorphism of the IL-1RN gene in 108 early postmenopausal women. All women were within 5 years of a natural menopause at the study's onset, healthy, and not on hormone replacement therapy or other medication known to affect bone metabolism. BMD was measured annually over the 5 year study period at the lumbar spine and femoral neck using dual-energy X-ray absorptiometry. Three alleles were identified (A1 = 4 repeats, A2 = 2 repeats, A3 = 5 repeats), with five genotypes observed: A1A1 (41.7%), A1A2 (45.4%), A2A2 (6.5%), A1A3 (2.8%), and A2A3 (3.7%). For analysis, alleles were collapsed into a biallelic system grouping the A1 and A3 alleles. There was no significant relationship between the IL-1RN genotypes and baseline bone mass at either the spine or hip. IL-1RN genotype was significantly associated with annual rates of change in spinal bone mass (p < 0.05), and this finding remained significant after adjustment for age, weight, and baseline BMD. Carriage of at least one copy of the A2 allele was associated with reduced bone loss at the spine (mean change in BMD +/- SD: -0.81 +/- 1.46%/year) when compared with noncarriage of the A2 allele (mean change -1.38 +/- 1.48%/year), p = 0.05. We therefore conclude that allelic variation at the IL-1RN locus is associated with differential rates of early postmenopausal bone loss at the spine. Further research will be required to clarify the mechanisms underlying these findings and to determine whether this association translates into a significant long-term effect on BMD and fracture in later life.

A higher alkaline dietary load is associated with greater indexes of skeletal muscle mass in women

Conservation of muscle mass is important for fall and fracture prevention but further understanding of the causes of age-related muscle loss is required. This study found a more alkaline diet was positively associated with muscle mass in women suggesting a role for dietary acid-base load in muscle loss.

INTRODUCTION

Conservation of skeletal muscle is important for preventing falls and fractures but age-related loss of muscle mass occurs even in healthy individuals. However, the mild metabolic acidosis associated with an acidogenic dietary acid-base load could influence loss of muscle mass.

METHODS

We investigated the association between fat-free mass (FFM), percentage FFM (FFM%) and fat-free mass index (FFMI, weight/height²), measured using dual-energy X-ray absorptiometry in 2,689 women aged 18-79 years from the TwinsUK Study, and dietary acid-base load. Body composition was calculated according to quartile of potential renal acid load and adjusted for age, physical activity, misreporting and smoking habit (FFM, FFMI also for fat mass) and additionally with percentage protein.

RESULTS

Fat-free mass was positively associated with a more alkalinogenic dietary load (comparing quartile 1 vs 4: FFM 0.79 kg P < 0.001, FFM% 1.06 % <0.001, FFMI 0.24 kg/m² P = 0.002), and with the ratio of fruits and vegetables to potential acidogenic foods.

CONCLUSIONS

We observed a small but significant positive association between a more alkaline diet and muscle mass indexes in healthy women that was independent of age, physical activity and protein intake equating to a scale of effect between a fifth and one half of the observed relationship with 10 years of age. Although protein is important for maintenance of muscle mass, eating fruits and vegetables that supply adequate amounts of potassium and magnesium are also relevant. The results suggest a potential role for diet in the prevention of muscle loss.

The big finger: the second to fourth digit ratio is a predictor of sporting ability in women

BACKGROUND

The second to fourth finger length ratio (2d:4d) is thought to be related to diverse traits including cognitive ability, disease susceptibility, and sexuality.

OBJECTIVE

To examine the relationship between 2d:4d and sports ability in women.

METHODS

Hand radiographs from 607 women (mean age 54 years) were used to estimate 2d:4d. Ranking of sports ability was on a scale (1-5).

RESULTS

The highest achieved level of participation in any sport was significantly negatively associated with 2d:4d (b = -4.93, p = 0.01) as was the relationship between 2d:4d and running level (b = -6.81, p = 0.034). Ability in other sports also showed a negative relationship albeit non-significant.

CONCLUSIONS

These results suggest that a low 2d:4d ratio is related to increased female sports ability. It can be postulated that this ratio may predict potential sports ability. Understanding the mechanisms underpinning this relationship may give important insights into musculoskeletal fitness, health and disease.

Definition and epidemiology of osteoarthritis of the hand: a review

The hand is a common site of peripheral joint involvement in osteoarthritis (OA) and although often underestimated as a cause of disability, the effect on quality of life from limitations in performing activities of daily living such as dressing and feeding may be considerable. Hand OA may also be an important indicator of a systemic tendency to OA which may involve weight bearing joints, notably the hips and knees. (1) The definition of hand OA, particularly for epidemiological studies, has undergone reassessment and revision over the last few years. In this paper we examine the issues relating to this and consider the epidemiology of hand OA.

Low free testosterone levels in rheumatoid arthritis

The androgen status of 25 male patients with rheumatoid arthritis (RA) was assessed and compared with that of age matched controls with osteoarthritis (OA). Significantly reduced levels of serum free testosterone were found in the RA group. Within that group free testosterone was unrelated to all indices of disease activity measured, though it was strongly related to latex positivity. These results support the hypothesis that male sex hormones may have a protective role in RA, though prospective studies would be necessary to determine whether the relation was one of cause or effect.

Defining osteoarthritis of the hand for epidemiological studies: the Chingford Study

OBJECTIVES

To explore the relative merits of clinical and radiological examination in defining hand osteoarthritis (OA) for epidemiological purposes.

METHODS

A total of 976 women aged 45-64 years were selected from the general population and underwent a structured interview, clinical examination of the hand joints and radiography of the hands and knees. The inter-relationship of the clinical and radiological findings was examined, and also the association of each with hand symptoms and the presence of knee OA.

RESULTS

Clinical and radiographic signs of hand OA generally correlated with each other, and each was associated with hand symptoms to a similar degree. When analysed in combination, they were only marginally better at predicting symptoms than when tested individually. However, when they were examined in relation to radiographic features of knee OA, there was a significantly stronger association with radiographic features of hand OA than with clinical features.

CONCLUSIONS

Hand radiology provides a better overall assessment of osteoarthritis than physical examination of the interphalangeal joints or carpo-metacarpal joint; in situations where radiology is not available clinical examination is a viable substitute.

A randomized controlled trial of vitamin D supplementation on preventing postmenopausal bone loss and modifying bone metabolism using identical twin pairs

Vitamin D supplementation, when given with calcium, has been shown to increase bone mineral density (BMD) and reduce the incidence of hip fracture in elderly subjects. Despite its widespread use, the benefits of vitamin D supplementation in younger women and as a single agent are less clear. We performed a randomized co-twin, placebo-controlled, double-blind trial over 2 years to measure the effect of vitamin D3 supplementation on bone density and bone metabolism in young postmenopausal women. Seventy-nine monozygotic (MZ) twin pairs (mean age, 58.7 years; range, 47-70 years) were recruited. For each twin pair, one was randomized to 800 IU cholecalciferol/day for 2 years and the other was randomized to placebo. BMD was measured at the spine and hip and heel ultrasound at baseline, 12, 18, and 24 months. Samples were collected at 0, 3, and 6 months to measure serum calcium, 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), osteocalcin, and urinary deoxypyridinoline (DPD). In total, 64 pairs completed the study. No differences in baseline characteristics were seen between the groups. At 6 months, the treatment group had an increase in serum vitamin D [mean +/- SEM intrapair difference, 14.1+/-2.4 microg/liter (p < 0.001)]. There were no significant differences in other serum measurements or bone markers at 3 months or 6 months. At 24 months, no significant treatment effect was seen on BMD or calcaneal ultrasound change within pairs. Subanalysis of treatment response by vitamin D receptor (VDR) genotype revealed no significant difference in effect on BMD variables with treatment. On the basis of these results, vitamin D supplementation, on its own, cannot be recommended routinely as an osteoporosis prevention for healthy postmenopausal women with normal vitamin D levels under the age of 70 years.

A randomized trial of testosterone therapy in males with rheumatoid arthritis

Thirty-five male patients, aged 34-79 yr, with definite rheumatoid arthritis (RA) were recruited from out-patient clinics and randomized to receive monthly injections of testosterone enanthate 250 mg or placebo as an adjunct therapy for 9 months. Endpoints included disease activity parameters and bone mineral density (BMD). At baseline, there were negative correlations between the ESR and serum testosterone (r = -0.42, P < 0.01) and BMD (hip, r = -0.65, P < 0.01). A total of 29.6% of all patients had at least one vertebral fracture, most having multiple fractures. Back pain, however, was not more prevalent in fracture patients (55% vs 50%). Disease activity was significantly higher in the fracture group (joint score P < 0.05, rheumatoid factor P < 0.01). Thirty patients completed the trial, 15 receiving testosterone and 15 receiving placebo. There were significant rises in serum testosterone, dihydrotestosterone and oestradiol in the treatment group. There was no significant effect of treatment on disease activity overall, five patients receiving testosterone underwent a "flare'. Differences in mean BMD following testosterone or placebo were non-significant (spine: +1.2% vs -1.1%; femur: -0.3% vs +0.3%). There was no suggestion of a positive effect of testosterone on disease activity in men with RA.

Large scale meta-analysis of urinary C-terminal telopeptide, serum cartilage oligomeric protein and matrix metalloprotease degraded type II collagen and their role in prevalence, incidence and progression of osteoarthritis

OBJECTIVE

To evaluate the role of three cartilage-derived biomarkers on osteoarthritis (OA): urinary C-terminal telopeptide (uCTX-II), serum cartilage oligomeric protein (sCOMP), and serum MMP degraded type II collagen (sC2M).

SUBJECTS AND METHODS

Samples from 3582 individuals from the Rotterdam Study, the Genetics osteoArthritis and Progression (GARP), the Chingford Study and the TwinsUK cohort were assayed using enzyme-linked immune sorbent assays. Log10 of concentration levels were correlated with risk of hip, hand and knee OA, hip and knee OA severity and incidence, and progression of knee OA, adjusting for age, gender and body mass index (BMI). Results were meta-analysed to assess overall significance.

RESULTS

After adjusting for covariates, sCOMP was associated with knee OA and hip and knee OA incidence. Furthermore, sC2M was associated with knee OA incidence and progression. After adjustment for multiple tests (Bonferroni P < 0.002) only the association between sCOMP and knee OA remained significant (odds ratio (OR) = 3.26 (95%CI 1.63-10.1) P = 0.0008 for each standard deviation (SD) increase in biomarker levels). Levels of uCTX-II were significantly associated with risk of hand, hip and knee OA, progression and incidence of knee OA. A receiver operating characteristics (ROC) analysis showed a consistent improvement in prediction of knee OA progression from an average area under the curve (AUC) is 0.646 for age, sex and BMI alone to an AUC = 0.668 including uCTX-II for prediction.

CONCLUSIONS

uCTX-II is the most informative biochemical marker for prediction of OA. Both sCOMP and C2M showed some association with OA, thus indicating that they are descriptive of disease activity.

Alcohol-induced metabolomic differences in humans

Alcohol consumption is one of the world's major risk factors for disease development. But underlying mechanisms by which moderate-to-heavy alcohol intake causes damage are poorly understood and biomarkers are sub-optimal. Here, we investigated metabolite concentration differences in relation to alcohol intake in 2090 individuals of the KORA F4 and replicated results in 261 KORA F3 and up to 629 females of the TwinsUK adult bioresource. Using logistic regression analysis adjusted for age, body mass index, smoking, high-density lipoproteins and triglycerides, we identified 40/18 significant metabolites in males/females with P-values <3.8E-04 (Bonferroni corrected) that differed in concentrations between moderate-to-heavy drinkers (MHD) and light drinkers (LD) in the KORA F4 study. We further identified specific profiles of the 10/5 metabolites in males/females that clearly separated LD from MHD in the KORA F4 cohort. For those metabolites, the respective area under the receiver operating characteristic curves were 0.812/0.679, respectively, thus providing moderate-to-high sensitivity and specificity for the discrimination of LD to MHD. A number of alcohol-related metabolites could be replicated in the KORA F3 and TwinsUK studies. Our data suggests that metabolomic profiles based on diacylphosphatidylcholines, lysophosphatidylcholines, ether lipids and sphingolipids form a new class of biomarkers for excess alcohol intake and have potential for future epidemiological and clinical studies.

The effect of moderate alcohol consumption on bone mineral density: a study of female twins

BACKGROUND

Osteoporosis is associated with morbidity and mortality, particularly in postmenopausal women. The effect of moderate alcohol intake on bone mineral density (BMD) and fracture risk remains unclear.

OBJECTIVE

To carry out a twin study to investigate this effect while controlling for genetic effects and other confounding variables.

METHODS

BMD was determined at the hip and lumbar spine in 46 pairs of monozygotic twins discordant for alcohol consumption. Biochemical evidence of altered bone metabolism was sought.

RESULTS

A positive association between alcohol consumption and BMD was shown, in contrast to the negative effect of smoking on BMD. Markers of bone turnover were not associated with alcohol or BMD.

CONCLUSIONS

Moderate alcohol consumption is not harmful to bone health in women and may even be beneficial. Beneficial effects do not appear to be mediated through an action on bone metabolism.

Effects of strontium ranelate on spinal osteoarthritis progression

OBJECTIVE

The aim of this study was to determine whether a 3-year treatment with strontium ranelate could delay the progression of spinal osteoarthritis (OA).

METHODS

This study was a post-hoc analysis of pooled data from the Spinal Osteoporosis Therapeutic Intervention (SOTI) and TReatment Of Peripheral OSteoporosis (TROPOS) trials performed on 1105 women with osteoporosis and concomitant radiological spinal OA at baseline, and for whom lumbar x-rays were available at baseline and over the 3-year treatment period. The presence and severity of osteophytes, disc space narrowing and sclerosis in the lumbar intervertebral spaces was graded according to a validated method, and an overall OA score was calculated for each intervertebral space. Back pain (measured on a five-point Likert scale only in SOTI) and health-related quality of life (SF-36 questionnaire) were assessed at baseline and after 3 years. Patients who suffered an incident or progressive vertebral fracture during the study were excluded from the analysis.

RESULTS

The proportion of patients with worsening overall spinal OA score was reduced by 42% in the strontium ranelate group, compared with placebo (RR, 0.58; 95% CI, 0.42 to 0.79; p = 0.0005). Significantly more patients in the strontium ranelate group experienced an improvement in back pain after 3 years, compared with placebo (p = 0.03), while no significant difference was observed in terms of health-related quality of life between these patient groups.

CONCLUSIONS

The results of this post-hoc analysis suggest that strontium ranelate could reduce the progression of the radiographic features of spinal OA and back pain in women with osteoporosis and prevalent spinal OA.

Neuropathic features of joint pain: a community-based study

OBJECTIVE

Quantitative sensory testing (QST) and questionnaire-based assessments have been used to demonstrate features of neuropathic pain in subjects with musculoskeletal pain. However, their direct relationship has not been investigated in the community. The purpose of this study was to conduct an observational study to describe the characteristics of joint pain and to examine the relationship between QST measures and the PainDETECT Questionnaire (PD-Q).

METHODS

Warm detection, heat pain, and mechanical pain thresholds as well as mechanical pain sensitivity over the sternum were determined and the PD-Q scores were calculated in a cross-sectional study of 462 participants in the Chingford Study. Comparisons were made between subjects with and those without joint pain. Logistic regression modeling was used to describe the association between neuropathic pain features, as determined by the PD-Q score, and each of the QST measures individually, adjusting for age, body mass index, and use of pain-modifying medications.

RESULTS

A total of 66.2% of the subjects reported recent joint pain, with a median average pain severity of 5 of 10. There was increased sensitivity to painful stimuli in the group with pain as compared to the pain-free group, and this persisted after stratification by pain-modifying medication use. While only 6.7% of subjects had possible neuropathic pain features and 1.9% likely neuropathic pain features according to the standard PD-Q thresholds, features of neuropathic pain were common and were present in >50% of those reporting pain of at least moderate severity. Heat pain thresholds and mechanical pain sensitivity were significantly associated with features of neuropathic pain identified using the PD-Q, with an odds ratio (OR) of 0.88 (95% confidence interval [95% CI] 0.79-0.97; P = 0.011) and an OR of 1.24 (95% CI 1.04-1.48; P = 0.018), respectively.

CONCLUSION

QST measures and the PD-Q identified features of neuropathic pain in subjects in this community-based study, with significant overlap between the findings of the two techniques.

The classification and assessment of osteoarthritis

Osteoarthritis is the commonest rheumatic disease, but despite its high prevalence in the elderly, associated disability and public health costs, there is little understanding of the aetiology of the disease. Questions still remain unanswered: 'what do we mean by the term osteoarthritis?; how do we define it?; how do we classify patients with the disease?; how do we differentiate between cases for population studies, and clinically relevant disease the physician wishes to treat?'. This chapter has demonstrated the considerable advances that have been made over the last thirty years in solving these issues, but we are still lacking a universal definition and classification of the disease. Defining and classifying OA is not an easy task, as it is not a single disease, but rather a spectrum of diseases that are the end result of a number of different processes. However, in order to understand the aetiology and natural course of the disease, and to devise appropriate treatment strategies, correct definition of OA at distinct sites is vital. Radiological site-specific definition of the disease is now recognized as the major tool available in defining OA. There is general consensus that the grading of osteophytes and joint space narrowing at the major sites using validated atlases is an important step forward.

Large-scale meta-analysis of interleukin-1 beta and interleukin-1 receptor antagonist polymorphisms on risk of radiographic hip and knee osteoarthritis and severity of knee osteoarthritis

OBJECTIVE

To clarify the role of common genetic variation in the Interleukin-1β (IL1B) and Interleukin-1R antagonist (IL1RN) genes on risk of knee and hip osteoarthritis (OA) and severity of knee OA by means of large-scale meta-analyses.

METHODS

We searched PubMed for articles assessing the role of IL1B and IL1RN polymorphisms/haplotypes on the risk of hip and/or knee OA. Novel data were included from eight unpublished studies. Meta-analyses were performed using fixed- and random-effects models with a total of 3595 hip OA and 5013 knee OA cases, and 6559 and 9132 controls respectively. The role of ILRN haplotypes on radiographic severity of knee OA was tested in 1918 cases with Kellgren-Lawrence (K/L) 1 or 2 compared to 199 cases with K/L 3 or 4.

RESULTS

The meta-analysis of six published studies retrieved from the literature search and eight unpublished studies showed no evidence of association between common genetic variation in the IL1B or IL1RN genes and risk of hip OA or knee OA (P>0.05 for rs16944, rs1143634, rs419598 and haplotype C-G-C (rs1143634, rs16944 and rs419598) previously implicated in risk of hip OA). The C-T-A haplotype formed by rs419598, rs315952 and rs9005, previously implicated in radiographic severity of knee OA, was associated with reduced severity of knee OA (odds ratio (OR)=0.71 95%CI 0.56-0.91; P=0.006, I(2)=74%), and achieved borderline statistical significance in a random-effects model (OR=0.61 95%CI 0.35-1.06 P=0.08).

CONCLUSION

Common genetic variation in the Interleukin-1 region is not associated with prevalence of hip or knee OA but our data suggest that IL1RN might have a role in severity of knee OA.

Assessment of bone in Ehlers Danlos syndrome by ultrasound and densitometry

OBJECTIVE

Ehlers Danlos syndrome (EDS) is an inherited disorder of connective tissue characterised by hyperextensible skin, joint laxity, and easy bruising. There are phenotypic similarities with osteogenesis imperfecta, but in EDS a tendency to fracture or altered bone mass has not previously been considered to be a cardinal feature.

METHOD

This case-control design study investigates whether 23 patients with EDS had differences in fracture rates, bone mass, and calcaneal ultrasound parameters compared with age and sex matched controls.

RESULTS

23 cases of EDS (mean (SD) age 38.5 (15.5)) were compared with 23 controls (mean age 37.8 (14.5)). A significant reduction in bone density measured by dual energy x ray absorptiometry was found at the neck of femur by 0.9 SD, p = 0.05, and lumbar spine by 0.74 SD, p = 0.02. At the calcaneum, broad band ultrasound attenuation and speed of sound were significantly reduced compared with controls by 0.95 SD (p = 0.004) and 0.49 SD (p = 0.004) for broad band ultrasound attenuation and speed of sound respectively. Broad band ultrasound attenuation and speed of sound remained significantly reduced after adjusting for bone mineral density (BMD). After adjusting for functional status (HAQ), age and sex, hypermobility was inversely correlated with broad band ultrasound attenuation and SOS, but not BMD at hip or spine. Previous fracture was 10 times more common in EDS (p < 0.001), with 86.9% of patients reporting a total of 47 low impact fractures, compared with 8.7% of controls.

CONCLUSION

This study has identified a tendency of EDS patients to fracture, have low bone mass and abnormal bone structure. The aetiology is likely to be multifactorial, with an inherited structural element, accentuated by immobility or reduced exercise. This is one of the first clinical studies to suggest ultrasound can detect structural differences in bone, independent of dual energy x ray absorptiometry.

Free and serum testosterone levels in 276 males: a comparative study of rheumatoid arthritis, ankylosing spondylitis and healthy controls

A cross-sectional study of testosterone levels in 276 males was undertaken. Of these 87 were RA patients, 48 males with AS and 141 were healthy controls. Free and serum testosterone levels were significantly lower in the RA males than in either the AS group or the healthy controls (p less than 0.001). This difference was unaffected by age. No differences were seen in testosterone levels between DR1 or DR4 RA patients compared to those without these antigens. No evidence of hyperandrogenicity was seen in the AS group. The finding that males with RA have lower androgen levels than both normal controls and a disease group with inflammatory spondarthritis supports the hypothesis that male sex hormones may be a protective factor against the development of RA.

Oxypurinol as an inhibitor of xanthine oxidase-catalyzed production of superoxide radical

A recent study of the mechanism by which oxypurinol inhibits uric acid generation [T. Spector, W. W. Hall and T. A. Krenitsky, Biochem. Pharmac. 35, 3109(1986)] showed that xanthine is ineffective in impeding the binding of oxypurinol to reduced xanthine oxidase. This study prompted the present hypothesis that, at elevated concentrations of substrates, oxypurinol would be superior to allopurinol as an inhibitor of the xanthine oxidase-catalyzed production of superoxide radical. It was found that the potency of allopurinol was attenuated by elevated concentrations of xanthine and hypoxanthine, whereas the potency of oxypurinol was relatively unaffected. Oxypurinol produced immediate inhibition of superoxide radical production as well as progressive inhibition with time. In contrast, allopurinol, which is also a substrate for xanthine oxidase, produced very little immediate inhibition and caused progressive inhibition only after conversion to oxypurinol. The theoretical advantages of treating ischemic tissues with oxypurinol are discussed.

Polymorphisms of the vitamin D receptor, infant growth, and adult bone mass

Family and twin studies have demonstrated a strong genetic component to the development of peak bone mass. Early fetal and infant environment has also been shown to influence bone mass through an effect on skeletal size and mineral content. We report a retrospective study that has examined whether early infant growth is regulated by genetic factors shown to be associated with bone mass. We have determined the vitamin D receptor (VDR) gene alleles for 66 women (mean age 65.5 years) on whom detailed birth records were available. There was a statistically significant trend (P = 0.04) for VDR genotype against weight at the age of 1 year, with the "tt" homozygote group having 7% higher weight. We conclude that early fetal or infant environment may interact with an individual's underlying genotype to program early skeletal growth, and that this may track through later life to influence adult characteristics. Further prospective studies are required, however, to fully clarify the precise environmental and genetic mechanisms underlying these findings.

The influence of gender on the short and long-term effects of growth hormone replacement on bone metabolism and bone mineral density in hypopituitary adults: a 5-year study

OBJECTIVES

The objectives of this study were to investigate the effects of GH replacement therapy in hypopituitary adults with growth hormone deficiency (GHD) on activation of bone remodelling during dose titration and on BMD over a median of 58 months of continuous therapy.

STUDY DESIGN

Open label study in adult patients with GHD. rhGH was commenced at dose of 0.8 IU subcutaneously daily (0.4 IU if hypertensive or glucose tolerance impaired) with subsequent dose titration based on 2 weekly measurement of serum IGF-I until levels reached the target range (between the median and upper end of the age related reference range). In patients previously commenced on GH using weight based regimens the dose of GH was adjusted during clinical follow-up in order to maintain serum IGF-I in the target range.

PATIENTS

Initial effects of GH on bone remodelling during dose titration were studied in 17 patients (8F). Long-term effects of GH were determined in a separate group of 13 GHD adults (6F) over a median period of 58 months (range 44-72).

MEASUREMENTS

Osteoblastic activity was estimated by measuring serum bone specific alkaline phosphatase (S-BAP). BMD was determined at both lumbar spine (L2-L4) and femoral neck by dual energy X-ray absorptiometry (DEXA).

RESULTS

During dose titration a significant increment in S-BAP was observed by 10 weeks in females but occurred later in males (12-26 weeks). In the long term treatment group there was a significant increment in S-BAP compared to baseline (P = 0.013) after 6 months GH treatment. After long-term GH treatment (median 58 months) S-BAP levels decreased and were no longer statistically significantly different from baseline at the end of the study period. A similar response was observed in male and female patients. There were no significant differences in baseline BMD between male and female patients at either lumbar spine or femoral neck in the long term treatment group. No significant changes were observed in BMD after 6 months GH treatment in either lumbar spine or femoral neck but BMD increased over the remainder of the study at both sites (P = 0.023 and P = 0.03 respectively). When analysed by gender male patients showed a clear positive change in BMD after longer-term replacement in both lumbar spine and femoral neck (P = 0.01 and P = 0.02 respectively) but female patients showed no significant changes. Qualitatively similar results were observed when analysing changes in BMD expressed as Z scores.

CONCLUSION

This study demonstrates an earlier onset of GH activation of bone remodelling as reflected by S-BAP in females compared to males and confirms that long-term GH treatment in hypopituitary adults with GH deficiency increases or preserves BMD both at lumbar spine and femoral neck. However male patients seem to derive the greater benefits in BMD from long-term GH replacement; in females BMD appears simply to be stabilized rather than increased. This constitutes a genuine gender difference in susceptibility given that serum IGF-I was in the upper part of the reference range in all subjects.

Untangling the relationship between diet and visceral fat mass through blood metabolomics and gut microbiome profiling

BACKGROUND/OBJECTIVES

Higher visceral fat mass (VFM) is associated with an increased risk for developing cardio-metabolic diseases. The mechanisms by which an unhealthy diet pattern may influence visceral fat (VF) development has yet to be examined through cutting-edge multi-omic methods. Therefore, our objective was to examine the dietary influences on VFM and identify gut microbiome and metabolite profiles that link food intakes to VFM.

SUBJECTS/METHODS

In 2218 twins with VFM, food intake and metabolomics data available we identified food intakes most strongly associated with VFM in 50% of the sample, then constructed and tested the 'VFM diet score' in the remainder of the sample. Using linear regression (adjusted for covariates, including body mass index and total fat mass), we investigated associations between the VFM diet score, the blood metabolomics profile and the fecal microbiome (n=889), and confirmed these associations with VFM. We replicated top findings in monozygotic (MZ) twins discordant (⩾1 s.d. apart) for VFM, matched for age, sex and the baseline genetic sequence.

RESULTS

Four metabolites were associated with the VFM diet score and VFM: hippurate, alpha-hydroxyisovalerate, bilirubin (Z,Z) and butyrylcarnitine. We replicated associations between VFM and the diet score (beta (s.e.): 0.281 (0.091); P=0.002), butyrylcarnitine (0.199 (0.087); P=0.023) and hippurate (-0.297 (0.095); P=0.002) in VFM-discordant MZ twins. We identified a single species, Eubacterium dolichum to be associated with the VFM diet score (0.042 (0.011), P=8.47 × 10-5), VFM (0.057 (0.019), P=2.73 × 10-3) and hippurate (-0.075 (0.032), P=0.021). Moreover, higher blood hippurate was associated with elevated adipose tissue expression neuroglobin, with roles in cellular oxygen homeostasis (0.016 (0.004), P=9.82x10-6).

CONCLUSIONS

We linked a dietary VFM score and VFM to E. dolichum and four metabolites in the blood. In particular, the relationship between hippurate, a metabolite derived from microbial metabolism of dietary polyphenols, and reduced VFM, the microbiome and increased adipose tissue expression of neuroglobin provides potential mechanistic insight into the influence of diet on VFM.

Endogenous sex steroid levels in women with generalised osteoarthritis

Epidemiologic and clinical observations have suggested a relationship between generalised osteoarthritis (GOA) and hormonal and menopausal factors in women. We explored the hypothesis that postmenopausal women with GOA have altered sex hormone status compared with control women. We studied 112 women (mean age 64) with GOA. Controls were 151 women (mean age 54) from the general population without clinical evidence of hand or knee OA. All women were postmenopausal. Serum was assayed by RIA for testosterone, oestradiol, sex hormone binding globulin (SHBG), and dyhydroepiandrosterone sulphate (DHEAS). Because of the differences in mean ages, the results were compared according to equal age groups divided on the basis of tertiles. SHBG was lower in the GOA group, reaching significance in the middle group 53-61 years (58.0 vs 67.9 nmol/l p less than 0.05). Testosterone was slightly higher in GOA women aged under 53. No consistent differences were seen in the older age group or for the other sex steroids. These preliminary data suggest that middle-aged women with GOA have lower circulating SHBG levels. This implies that higher circulating free oestrogens and androgens are present suggesting a role in the aetiopathogenesis of GOA.