Profile of soluble factors in pleural effusions predict prognosis in mesothelioma.

BACKGROUND: Pleural mesothelioma is a deadly asbestos induced cancer. Less than 10% of mesothelioma patients survive 5 years post diagnosis. However survival can range from a few months to a number of years. Accurate prediction of survival is important for patients to plan for their remaining life, and for clinicians to determine appropriate therapy. One unusual feature of mesothelioma is that patients frequently present with tumor-associated pleural effusions early in the course of the disease. OBJECTIVE: To study whether cells and molecules present in pleural effusions provide prognostic information for mesothelioma. METHODS: We profiled the cellular constituents and concentrations of 40 cytokines, chemokines and cellular factors (collectively "soluble factors") involved in inflammatory and immune signalling pathways in pleural effusion samples from 50 mesothelioma patients.Associations with survival were evaluated by Cox proportional hazards regression methods. Results for the two soluble factors most significantly and independently associated with survival were validated in an independent set of samples (n= 51) using a separate assay system. RESULTS: Survival analysis revealed that IL8, IL2Ra (CD25) and PF4 were independent determinants of a more negative prognosis in mesothelioma patients, independent of other known prognostic factors. Lipocalin2 and IL4 were associated with better prognosis. CONCLUSIONS: This study demonstrates that pleural effusions rich in a range of soluble factors are associated with poor prognosis. These findings will enhance our ability to prognosticate outcomes in mesothelioma patients.

Post-chemotherapy T-cell recovery is a marker of improved survival in patients with advanced thoracic malignancies.

BACKGROUND: There is increasing interest in combining chemotherapy with immunotherapy. However, the effects of chemotherapy on the human immune system are largely unknown. METHODS: Longitudinal changes in peripheral T-cell subsets in 40 patients with malignant mesothelioma (MM) or advanced non-small cell lung cancer (NSCLC) receiving platinum-based chemotherapy were assessed by flow cytometry and evaluated for associations with clinical outcome. RESULTS: Proliferating T cells of all subsets were almost entirely depleted at day 8 following chemotherapy, but rapidly recovered above baseline levels. Regulatory T cells (Treg) were most profoundly depleted at this time point. A greater increase in CD8(+) T-cell proliferation following one treatment cycle was associated with improved overall survival in univariate (hazard ratio (HR)=0.40; P<0.05) and multivariate (HR=0.17; P<0.01) analyses. A greater increase in the ratio of CD8(+) T cell to Treg proliferation was also predictive of better prognosis. CONCLUSION: Chemotherapy potentially provides a favourable environment for the development of anti-tumour immunity through transient Treg depletion and regeneration of the T-cell pool. Change in CD8(+) T-cell proliferation after one cycle of chemotherapy may represent a useful prognostic indicator in patients with MM and NSCLC.

In vitro kinetic properties of the Thr201Met variant of human aromatase gene CYP19A1: functional responses to substrate and product inhibition and enzyme inhibitors.

CONTEXT: The T(201)M variant (rs28757184) within exon 5 of the human aromatase gene CYP19A1, present in up to 20% of some populations, has been reported to reduce prostate cancer progression. OBJECTIVE: We hypothesized that the T(201)M variant would alter the structure of the enzyme and thus would also affect function compared to wild-type human aromatase. DESIGN: HEK293 cells were transiently transfected with CYP19A1 wild-type or T(201)M variant gene transcripts made by site-directed mutagenesis and enzyme activity measured using tritiated androstenedione as the substrate. The effects of differing concentrations of substrate and product (E1 and E2) and four aromatase inhibitors were assessed. RESULTS: At all substrate concentrations tested, the T(201)M variant showed substantially increased activity compared to the wild-type (Vmax: variant, 738 +/- 36 pmol/h . mg; wild-type, 189 +/- 17 pmol/h . mg, P < 0.0001; Km: variant, 64.4 +/- 19.3 nm; wild-type, 46.6 +/- 9.1 nm, P = 0.04). Kinetic analysis showed evidence of substrate inhibition for the wild-type, but no product inhibition was demonstrated for either transcript. Formestane, chrysin, and letrozole had no differential inhibitory effect on the two transcripts, but aminoglutethimide inhibition was substantially reduced in the variant compared to wild-type (IC(50): wild-type, 1.3 +/- 0.2 nm; variant, 45 +/- 14.2 nm, P = 0.002; and Ki: wild-type, 0.7 +/- 0.2 nm; variant, 29.6 +/- 9.7 nm, P = 0.0001). CONCLUSIONS: In addition to loss of function mutations previously described, a new naturally occurring relatively common alteration of enzyme structure at T(201)M increases enzyme activity and reduces the inhibitory effect of aminoglutethimide. These findings identify the T(201)M site, distant from the substrate-binding site and not previously considered to play a role in enzyme activity, as a functionally important area of the enzyme that may play a role in the propensity to disease. Common to other cytochrome P450 enzymes, wild-type aromatase demonstrates substrate but not product inhibition.

The effects of homocysteine and MTHFR genotype on hip bone loss and fracture risk in elderly women.

SUMMARY: Few studies have evaluated the effects of homocysteine and methylenetetrahydrofolate reductase (MTHFR) genotype on age-related bone loss. In our 5-year cohort study with 1,213 women aged 70-85 years, high homocysteine is associated with greater hip bone loss but not fracture risk. The effect of MTHFR genotype on bone density and fracture is weak. INTRODUCTION: Previous studies on the effects of homocysteine and MTHFR genotype on bone mineral density (BMD) and osteoporotic fracture risk have shown inconsistent results. Few studies have evaluated their effects on age-related bone loss. We evaluated the effects of homocysteine and MTHFR genotype variation on hip BMD and fracture risk over 5 years in a cohort of 1,213 community-dwelling women aged 70-85 years. METHODS: Nutritional intake and prevalent fracture status were assessed at baseline, plasma homocysteine was measured at year 1, and hip dual-energy X-ray absorptiometry (DXA) BMD was measured at years 1 and 5. Clinical incident osteoporotic fractures confirmed by radiographic report were collected throughout the study and the MTHFR gene C677T and A1298C polymorphisms genotyped. Data were analyzed using analysis of covariance and Cox proportional hazard regression. RESULTS: The highest tertile of homocysteine was associated with a greater hip BMD loss over 4 years (-2.8%) compared to the middle (-1.6%) and lowest tertiles (-1.2%) (P < 0.001). This effect remained after adjustment for covariates. There was no effect of homocysteine on fracture prevalence or incidence. MTHFR gene variation was only weakly related to one of the bone outcome measures. CONCLUSION: In this study population, high homocysteine is associated with greater hip bone loss but not fracture risk.

Bone structural effects of variation in the TNFRSF1B gene encoding the tumor necrosis factor receptor 2.

UNLABELLED: The 1p36 region of the human genome has been identified as containing a QTL for BMD in multiple studies. We analysed the TNFRSF1B gene from this region, which encodes the TNF receptor 2, in two large population-based cohorts. Our results suggest that variation in TNFRSF1B is associated with BMD. INTRODUCTION: The TNFRSF1B gene, encoding the TNF receptor 2, is a strong positional and functional candidate gene for impaired bone structure through the role that TNF has in bone cells. The aims of this study were to evaluate the role of variations in the TNFRSF1B gene on bone structure and osteoporotic fracture risk in postmenopausal women. METHODS: Six SNPs in TNFRSF1B were analysed in a cohort of 1,190 postmenopausal Australian women, three of which were also genotyped in an independent cohort of 811 UK postmenopausal women. Differences in phenotypic means for genotype groups were examined using one-way ANOVA and ANCOVA. RESULTS: Significant associations were seen for IVS1+5580A>G with BMD and QUS parameters in the Australian population (P = 0.008 - 0.034) and with hip BMD parameters in the UK population (P = 0.005 - 0.029). Significant associations were also observed between IVS1+6528G>A and hip BMD parameters in the UK cohort (P = 0.0002 - 0.003). We then combined the data from the two cohorts and observed significant associations between both IVS1+5580A>G and IVS1+6528G>A and hip BMD parameters (P = 0.002 - 0.033). CONCLUSIONS: Genetic variation in TNFRSF1B plays a role in the determination of bone structure in Caucasian postmenopausal women, possibly through effects on osteoblast and osteoclast differentiation.

A cohort study of the effect of endogenous estrogen on spine fracture risk and bone structure in elderly women and an assessment of its diagnostic usefulness.

The decline in endogenous estrogen concentration after menopause is associated with accelerated bone loss. However, effects in older women remain controversial and the usefulness of estrogen status as a predictor of spine fracture has not been assessed. Therefore, we undertook a prospective cohort study of 1350 women mean age 75 years in order to study the role of endogenous estrogen concentration on the risk of morphometric X-ray absorptiometry (MXA)-defined vertebral deformity and atraumatic clinical spine fracture and the association of endogenous estrogen with bone structure. At 5 years 70 patients (5.2%) had sustained > or = 1 incident spine fracture. The fracture group had significantly lower concentrations of baseline free estradiol index (FEI) median (IQ range) (0.38 (0.22-0.60) vs. 0.49 (0.29-0.84) pmol/nmol, p=0.009). The patients in the lowest tertile of FEI (FEI <0.35) had twice the risk of sustaining a clinical vertebral fracture compared to those subjects in the highest tertile (FEI >0.68) (HR 2.18: 95% CI 1.11-4.28). A low FEI was associated with an increased risk of a vertebral deformity over the 5-year study (OR 1.77: 95% CI 1.02-3.07) for the lowest compared to highest tertile. A low baseline FEI was associated with lower baseline QUS heel bone structure and DXA hip bone structure at 12 months and with deterioration in QUS heel bone structure 5 years later. The effect size of the FEI in predicting spine fracture was similar to the effect size for DXA BMD and heel QUS, probably because of the beneficial effect of the FEI on bone structure. The data suggest that the estrogen effect on reducing spine fracture is at least in part due to an effect on bone structure and its measurement does not significantly improve fracture prediction.

The clinical utility of measured kyphosis as a predictor of the presence of vertebral deformities.

UNLABELLED: Meaured spinal kyphosis, as a predictor of prevalent and incident vertebral deformity, was examined in older women (>70 years) and found to not have sufficient sensitivity or specificity to justify its use as a predictor of present or future vertebral deformity risk. INTRODUCTION: Kyphosis may be attributable to vertebral deformity and was investigated as a clinical tool for predicting the presence and future risk of vertebral deformity. METHODS: Kyphosis was measured in 434 women aged 70 years or older and the kyphosis index (KI) calculated. Prevalent and incident vertebral deformities were assessed by morphometric X-ray absorptiometry (MXA). The predictive value of KI was examined. RESULTS: Severity of kyphosis was categorised by tertile of KI; 65% of anterior thoracic deformities occurred in the 33% of subjects in the highest (most kyphotic) tertile. Using this tertile as a predictor of anterior thoracic deformity, the probability for a positive test rose from 14% for the whole population to 28% and for a negative test the probability fell to 8%. For any spinal deformity the highest tertile of KI increased the probability of a positive test from 34% to 42% and reduced the probability for a negative test to 30%. The incidence of new deformities was 6% over 4 years; a high KI tertile did not increase the probability of any vertebral deformity. CONCLUSIONS: Severe kyphosis does not increase the probability of detection of a prevalent or incident spinal deformity sufficiently to make it a useful method of selecting patients for further evaluation of spinal deformity.

No associations between OPG gene polymorphisms or serum levels and measures of osteoporosis in elderly Australian women.

Bone mass is the single most important risk factor for osteoporotic fractures in the elderly and is mainly influenced by genetic factors accounting for 40-75% of the inter-individual variation. Critical for the bone remodeling process is the balance between the newly discovered members of the tumor necrosis factor ligand and receptor superfamilies, osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaB ligand, which mediate the effects of many upstream regulators of bone metabolism. In the present study, we evaluated the impact of sequence variations in the OPG gene on bone mass, bone-related biochemistry including serum OPG and fracture frequency in elderly Australian women. A total of 1101 women were genotyped for 3 different single nucleotide polymorphisms (SNP) within the OPG gene (G1181C, T950C and A163G). The effects of these SNPs and serum OPG on calcaneal quantitative ultrasound measurements, osteodensitometry of the hip and bone-related biochemistry were examined. We found no significant relationship between sequence variations in the OPG gene or serum OPG and bone mass, bone-related biochemistry or fracture frequency. Our findings confirm some recent publications investigating the same SNPs but diverge from others, indicating that generalization of the relationships found in this type of study must be done with caution and signify the importance of determining associations between polymorphisms and osteoporosis in different ethnic groups.

Klotho gene polymorphisms are associated with osteocalcin levels but not bone density of aged postmenopausal women.

Osteoporosis is known to have a strong genetic basis. It has been proposed that polymorphisms within the KL (klotho) gene have a significant effect on aging, in particular, the osteoblast defect of aging. The association between polymorphisms within this gene and biochemical markers of bone formation and resorption, bone structure, and fracture rates was studied in 1,190 postmenopausal women with a mean age of 75 years. Genotyping of these polymorphic sites was carried out using Matrix-Assisted Laser Desorption Ionization--Time of Flight (MALDI-ToF) mass spectrometry. The G allele of SNP c.1775G>A was associated with a lower osteocalcin level than the A allele (P = 0.004) in a codominant model. SNPs C-387T and IVS1+8262c>t both showed nonsignificant associations with osteocalcin (P values of 0.063 and 0.068, respectively), but a haplotype analysis of 2 of 5 haplotypes of the three SNPs with a frequency greater than 4% revealed a significant association with osteocalcin (P = 0.036). None of the individual polymorphisms or haplotypes analyzed showed any associations with a marker of bone resorption the deoxypyridinoline creatinine ratio, bone structure, or fracture data. Therefore, the G polymorphism within the c.1775G>A SNP site and a haplotype including this are associated with a reduced osteoblast product osteocalcin. These data suggest that variation in the KL gene product affects osteoblast activity independent of osteoclast activity but that this defect does not result in an effect on bone structure in this population, perhaps because of "rescue" by other genetic or environmental factors in this population.

LRP5 gene polymorphisms predict bone mass and incident fractures in elderly Australian women.

Postmenopausal osteoporosis and bone mass are influenced by multiple factors including genetic variation. The importance of LDL receptor-related protein 5 (LRP5) for the regulation of bone mass has recently been established, where loss of function mutations is followed by severe osteoporosis and gain of function is related to increased bone mass. The aim of this study was to evaluate the role of polymorphisms in the LRP5 gene in regulating bone mass and influencing prospective fracture frequency in a well-described, large cohort of normal, ambulatory Australian women. A total of 1301 women were genotyped for seven different single nucleotide polymorphisms (SNPs) within the LRP5 gene of which five were potentially informative. The effects of these gene polymorphisms on calcaneal quantitative ultrasound measurements (QUS), osteodensitometry of the hip and bone-related biochemistry was examined. One SNP located in exon 15 was found to be associated with fracture rate and bone mineral density. Homozygosity for the less frequent allele of c.3357 A > G was associated with significant reduction in bone mass at most femoral sites. The subjects with the GG genotype, compared to the AA/AG genotypes showed a significant reduction in BUA and total hip, femoral neck and trochanter BMD (1.5% P = 0.032; 2.7% P = 0.047; 3.6% P = 0.008; 3.1% P = 0.050, respectively). In the 5-year follow-up period, 227 subjects experienced a total of 290 radiologically confirmed fractures. The incident fracture rate was significantly increased in subjects homozygous for the GG polymorphism (RR of fracture = 1.61, 95% CI [1.06-2.45], P = 0.027). After adjusting for total hip BMD, the fracture rate was still increased (RR = 1.67 [1.02-2.78], P = 0.045), indicating factors other than bone mass are of importance for bone strength. In conclusion, genetic variation in LRP5 seems to be of importance for regulation of bone mass and osteoporotic fractures.

Bone mass effects of a BMP4 gene polymorphism in postmenopausal women.

The pathogenesis of osteoporosis involves both genetic and environmental factors. On the basis of linkage data suggesting gene effects on bone density at chromosome 14q and data locating the BMP4 gene to 14q, we performed a positional candidate study to examine a possible association of BMP4 gene polymorphisms, hip bone density (n = 1012) and fracture rates (n = 1232) in postmenopausal women (mean age 75). On genotype analysis of the three selected single nucleotide polymorphisms (SNP), the 6007C > T polymorphism was associated with total and intertrochanteric hip BMD and BMD was lower in the 32% of subjects homozygous for the C allele. This polymorphism codes for a nonsynonymous amino acid change with the T allele coding for valine, while the C allele codes for alanine. The difference in BMD was 3.1% (TT vs. CC) and 2.3% (CT versus CC) for the total hip (P = 0.023), and 3.7% (TT vs. CC) and 2.8% (CT versus CC) for the intertrochanter site (P = 0.012). Haplotype analysis demonstrated 6 haplotypes of frequency greater than 2%. A major haplotype defined by G-C-T alleles in SNPs -5826G > A, 3564C > T and 6007C > T respectively, showed association with high bone mass. No SNP showed association with fracture rates. We conclude that a polymorphism found in the BMP4 gene, affecting amino acid sequence, is associated with hip bone density in postmenopausal women, presumably via regulation of anabolic effects on the skeleton.

Prediction of incident osteoporotic fractures in elderly women using the free estradiol index.

A decline in postmenopausal estrogen concentration accelerates postmenopausal bone loss. We have examined the predictive power of endogenous estrogen production, DXA hip bone density (BMD), and heel quantitative ultrasound (QUS) on incident clinical fracture in a prospective 3-year population based, randomised controlled trial of calcium supplementation. Baseline blood testing on 1499 women mean (SD) age 75 (3) years for estradiol and sex hormone binding globulin measurements and ankle QUS measurements (Lunar Achilles) was undertaken. Bone density was measured using DXA (Hologic 4500A) at 1 year. Incident clinical fractures were confirmed by X-ray. At 3 years, 10% had sustained more than one incident fracture. The fracture group had significantly lower levels of free estradiol index (FEI) (0.40+/-0.44 versus 0.49+/-0.54 pmol/nmol), hip BMD (0.776+/-0.129 versus 0.815+/-0.124 g/cm(2)) and measures of QUS (BUA 98+/-8 versus 101+/-8 db/Hz, SOS 1504+/-22 versus 1514 +/-26 m/s; stiffness 67+/-11 versus 71+/-11 % mean young adult), respectively, than the non-fracture group. After adjustment for age, weight, use of topical estrogen, calcium supplementation and prevalent fracture, incident fracture was predicted by free estradiol index (HR per SD: 1.43:95%CI: 1.08-1.91, P=0.013). After adjustment for BMD, SOS or stiffness, the free estradiol index no longer predicted fracture. When examined separately, the presence of a vertebral or an appendicular fracture was associated with an 18% lower free estradiol index compared with no fracture. The risk of vertebral fracture increased with decreased free estradiol index (HR per SD reduction: 1.63:95% CI: 0.91-2.92); the risk of appendicular fracture also increased with decreased free estradiol index (HR per SD reduction: 1.45:95% CI: 1.05-2.01) after adjustment for age, weight, use of topical estrogen, calcium supplementation and prevalent fracture. After further adjustment for hip BMD or QUS measures, the effect of free estradiol index was no longer significant for vertebral or appendicular fractures. Therefore, a low free estradiol index increases the probability of having an incident fracture as a result of decreased BMD. These data confirm the importance of postmenopausal estrogen concentration in the pathogenesis of osteoporosis in elderly women.

Effects of endogenous estrogen on renal calcium and phosphate handling in elderly women.

High postmenopausal endogenous estrogen concentrations are an important determinant of preservation of bone mass and reduced fracture in elderly women. Calcium supplementation can also reduce bone loss in these patients, suggesting an interaction between estrogen deficiency and calcium balance. Potential mechanisms of estrogen on calcium transport include direct effects on the bone, the kidney, and the bowel. Previous studies have demonstrated effects of estrogen on renal phosphate handling. We have used a cross-sectional, population-based analysis of biochemical data obtained from ambulant elderly women to determine the association of endogenous estradiol with urine calcium and phosphorus excretion. The subjects were 293 postmenopausal women >70 yr old. Factors associated with renal calcium and phosphate excretion were measured, including the filtered calcium and phosphate load, parathyroid hormone (PTH), estradiol, and sex hormone-binding globulin (SHBG). The free estradiol concentration (FE) was calculated from a previously described formula. A high plasma estradiol concentration (r(2) = 0.023, P = 0.01) and a high FE (r(2) = 0.045, P = 0.001) were associated with reduced renal calcium excretion. The estradiol and FE effect on renal calcium excretion remained significant after adjusting for calcium filtered at the glomerulus and serum PTH. A high FE was associated with a reduced renal phosphate threshold in univariate analysis (r(2) = 0.023, P = 0.010). The effect remained significant after adjustment for serum PTH. The size of the effect of the FE was of the same order of magnitude as the effect of PTH on reducing renal calcium excretion and increasing renal phosphate excretion. These data support in vitro and animal data demonstrating an effect of estradiol on renal calcium and phosphate handling and indicate that, in elderly postmenopausal women, the effect is of a similar magnitude to the well-recognized effects of PTH on these physiologically regulated parameters.

Association of an aromatase TTTA repeat polymorphism with circulating estrogen, bone structure, and biochemistry in older women.

Osteoporosis is a disease that is strongly genetically determined. Aromatase converts androgens to estradiol in postmenopausal women, therefore polymorphisms of the gene for this enzyme may be associated with bone mass and fracture. We investigated the association of the TTTA microsatellite polymorphism in intron 4 of the aromatase (CYP19) gene with bone mineral density (BMD) and fracture in 1,257 women aged 70 yr and greater. The data obtained were stratified based on the presence or absence of a [TTTA]n of 7 (A2), determined from a preliminary analysis of hip dual-energy X-ray absorptiometry BMD, which was present in 27% of the population. The presence of an A2 allele was associated with a higher free estradiol index (0.52 +/- 0.49, P = 0.049) compared with the absence of an A2 allele (0.47 +/- 0.45); higher BMD at all sites of the hip (3.4% total hip, 2.3% femoral neck, 3.6% intertrochanter, 4.1% trochanter) and the lumbar spine (12.7%); higher values for the calcaneal quantitative ultrasound parameters broadband ultrasound (1.3%), speed of sound (0.4%), and stiffness (3.7%); and higher peripheral quantitative computed tomography measures for total (3.4%), trabecular (3.3%), and cortical BMD (3.3%) and the derived stress strain index (SSI) parameters SSI polar (6.4%) and SSI x (6.8%) values. A lower deoxypryridinoline creatinine ratio was observed in subjects with an A2 allele (30.3 +/- 10.4 vs. 27.1 +/- 9.1, P = 0.03). The A2 allele was associated with a lower prevalence of vertebral fracture in subjects who were osteoporotic (odds ratio 0.27, confidence interval 0.09-0.79). Therefore, a common polymorphism of the aromatase gene, perhaps in linkage disequilibrium with a functionally significant CYP19 polymorphism, is associated with bone structure and bone turnover, either by local effects or by effects on circulating bioactive estrogen.

Calcium-sensing receptor gene polymorphism A986S does not predict serum calcium level, bone mineral density, calcaneal ultrasound indices, or fracture rate in a large cohort of elderly women.

Postmenopausal osteoporosis is a complex and heterogeneous disease influenced by multiple factors and related to peak bone mass achieved in early adult life, followed by a subsequent continuous bone loss. Genetic variance and polymorphisms have been shown to be of clinical significance for osteoporotic fragility fractures. Previous studies have related variations in the calcium sensor receptor (CASR) gene to circulating Ca levels and bone mass in young women and adolescent girls. The aim of this study was to investigate the impact of the A986S polymorphism of the CASR gene on calcium homeostasis and bone metabolism in elderly women. We studied the distribution of the A986S polymorphism in a large cohort of 1252 ambulatory Australian women in relation to biochemical markers of bone metabolism, bone mass evaluated by quantitative ultrasound measurements (QUS) and DXA of the hip, prevalent and 36-month incident fracture data. No effect of the polymorphism was found on circulating calcium level, renal Ca excretion, or biochemical markers of bone turnover. Moreover, A986S was not associated with bone mass or prevalent or incident fractures. Power calculations revealed that a difference in circulating calcium levels of 0.05 mmol/l, a difference in DXA bone density of 24 mg, and a 1.6-fold difference in fracture rate could have been detected with a power of 80%. In conclusion, in a large cohort of elderly women the A986S polymorphism of the CASR gene was not found to be significant for calcium homeostasis or bone mass. It is questioned whether the polymorphism has any clinical significance for postmenopausal osteoporosis.

The T869C TGF beta polymorphism is associated with fracture, bone mineral density, and calcaneal quantitative ultrasound in elderly women.

Osteoporosis is a disease that is strongly genetically determined and polymorphisms present in a range of candidate genes may be involved. A number of previous studies have shown an association between the T869C functional polymorphism of the gene for transforming growth factor beta (TGF beta) and bone mineral density (BMD) and fracture, but these studies have been limited to relatively small studies of selected subjects. In a population-based study of 1337 white women over age 70 we examined the TGF beta T869 polymorphism in relation to BMD, calcaneal quantitative ultrasound (QUS), and prevalent and incident fracture. The TGF beta C allele was observed in 50% of the subjects and was associated with reduced hip BMD at all sites (2.8% total hip, 2.4% femoral neck, 2.6% intertrochanter, and 3.4% trochanter) compared to the TGF beta TT genotype. The TGF beta C allele was also associated with a reduction in the QUS parameters BUA, SOS, and stiffness of 0.87%, 0.26%, and 2.4%, respectively, compared to the TGF beta TT genotype. After adjustment for body mass index in an analysis of variance model, the effect of the TGF beta C allele remained significant at the total hip, the femoral neck, and the trochanter, and for the QUS SOS and stiffness parameters. The TGF beta C allele was associated with an increase in osteoporosis [T score < or =-2.5 SD; odds ratio (OR) 2.07; 95% confidence interval (CI) 1.19-3.60] and prevalent fracture (1.37; 95% CI 1.06-1.75). After adjustment for BMD and QUS stiffness, the association of the TGF beta C allele with prevalent fracture was still present (OR 1.40; 95% CI 1.04-1.89), suggesting that the effect of the C allele on fracture was independent of a reduction in BMD and QUS stiffness. Subjects with normal BMD and a TGF beta C allele had an increased risk of incident fracture over 3 years compared to subjects with normal BMD and a TGF beta TT genotype (relative risk 3.95; 95% CI 1.52-10.29). This association was not found in osteopenic or in osteoporotic subjects, indicating a BMD-TGF beta C allele interaction in relation to the association of the TGF beta C allele with fracture risk. These findings are of potential clinical usefulness, as the TGF beta T869C genotype could be used, in conjunction with other genetic and clinical information, to determine an individual's risk of osteoporosis.

Apolipoprotein E4 is associated with reduced calcaneal quantitative ultrasound measurements and bone mineral density in elderly women.

Some studies have reported an association between the apolipoprotein E4 (APOE4) allele and reduced bone density and increased propensity to fracture, but this remains controversial as other studies have not found an association between APOE4 and bone density or fracture. No information is available concerning the effect of the APOE4 allele on quantitative ultrasound (QUS) parameters. We therefore examined this issue in a population-based study of 1332 healthy elderly women, examining the effect of the APOE4 allele on QUS parameters at the calcaneus and comparing this to dual-energy X-ray absorptiometry (DEXA) bone mineral density (BMD) at the hip. In addition, we examined the effect of the APOE4 allele on fracture. Subjects who had at least one APOE4 allele (n = 308) had lower calcaneal QUS parameters and lower hip BMD at the total hip, trochanter, and intertrochanter, but not the femoral neck, compared to subjects without an APOE4 allele (n = 1024) after adjustment for age, body mass index (BMI), and smoking. The decrement in QUS parameters and BMD was approximately 2%. Those subjects having an APOE4 allele were also more likely to fall into a low bone density group, defined by a T score of <1 SD below the young normal range (odds ratio [OR] 1.55, 95% confidence interval [CI] 1.08-2.22). We compared both prevalent and incident nontraumatic fractures over 2 years in the APOE4-present group compared with the APOE4-absent group. There were 354 subjects who entered the study with a history of one or more prevalent fractures, and 104 subjects sustained a nontraumatic fracture during the study. These fractures were not associated with the presence of the APOE4 allele, but a 2% decrement in BMD was unlikely to be associated with a statistically observable increase in fractures in this study. The APOE4 allele was not associated with a difference in any biochemical measures of bone formation or resorption, or in estrogen concentration, nor was it associated with a difference in BMI. Therefore, we conclude that the APOE4 allele is associated with a consistent decrease in both QUS parameters at the calcaneus and BMD at the clinically important hip site, and that this is not associated with differences in biochemical measures of bone formation or resorption.

The effect of estrogen on renal phosphorus handling in the rat.

BACKGROUND/AIMS: Phosphorus reabsorption in the kidney is regulated by parathyroid action on the sodium phosphorus cotransporter (Na-Pi cotransporter). There is some evidence that estrogen may also regulate renal phosphorus handling but it is not known if this is an effect of estrogen on filtered phosphorus load. METHODS: This study examined the effect of estrogen on renal phosphorus handling during infusion with calcium or EDTA. Six month old Sprague Dawley rats were bilaterally oophorectomized (OOX) or underwent a sham operation under ether anaesthesia 6 weeks before undergoing infusion with calcium chloride or EDTA. A second study examined renal phosphorus handling after estrogen replacement in the OOX rat injected with 20 microg estradiol valerate, or vehicle alone, prior to calcium infusion. RESULTS: A comparison of filtered phosphorus load with renal phosphorus excretion indicated that the estrogen replete rat had a higher renal excretion of phosphorus when infused with both calcium (p = 0.004) and EDTA (p = 0.037) at all filtered phosphorus loads. A similar analysis in calcium infused, estrogen replaced, OOX rats indicated an effect of estrogen to increase renal phosphorus excretion (p = 0.007) at all filtered phosphorus loads. OOX resulted in a mild metabolic alkalosis, an effect not reversed by estrogen administration, that was not related to renal phosphorus excretion. OOX decreased renal sodium excretion and uncoupled the relation between renal phosphorus and sodium excretion, an effect reversed by estrogen replacement. CONCLUSION: Ovarian hormone deficiency in the rat results in a decrease in renal phosphorus excretion. This finding is comparable to effects of the menopause and hormone replacement therapy in postmenopausal women.

Regulation of the 1b isoform of the plasma membrane calcium pump by 1,25-dihydroxyvitamin D3 in rat osteoblast-like cells.

The first isogene of the plasma membrane calcium pump (PMCA1) is expressed on the apical plasma membrane of osteoblasts, but its regulation by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] has not been studied in this cell type. We studied 1,25(OH)2D3 effects on PMCA1 function, protein, messenger RNA (mRNA), and isoform expression in osteoblasts. Of seven rat and human immortalized osteoblast-like cell lines studied, PMCA1 mRNA expression was confirmed in all. Only ROS 17/2.8 cells expressed measurable PMCA1 protein by Western analysis. Immunocytochemistry indicated that PMCA1 was expressed predominantly on the plasma membrane of ROS 17/2.8 cells. The 1,25(OH)2D3 but not 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] treatment of confluent ROS 17/2.8 cells resulted in an approximate 3- to 5-fold dose-dependent increase in PMCA1 expression of message and protein as assessed by Western and Northern analysis and vesicular 45Ca uptake of membrane vesicles. 1,25(OH)2D3 had no effect on PMCA1 posttranscriptional splicing. The 1b isoform of PMCA was expressed under all experimental conditions. 1,25(OH)2D3 favored increased expression of the 5.5 kilobases (kb) over the 7.5-kb PMCA1b transcript, with a 2-fold proportional increase in the smaller transcript relative to the larger transcript evident at the highest dose of 1,25(OH)2D3 studied. The resultant proportional increase in the smaller 5.5-kb transcript may increase mRNA stability and account for the increase in PMCA1b protein and function with 1,25(OH)2D3. These data provide evidence for the role of 1,25(OH)2D3 and PMCA1b in the regulation of calcium transport in bone cells.

Calcitriol upregulates expression and activity of the 1b isoform of the plasma membrane calcium pump in immortalized distal kidney tubular cells.

The plasma membrane calcium pump (PMCA) is ubiquitously expressed in calcium transporting epithelia. PMCA is encoded by four distinct genes (PMCA1-4) which can be further posttranscriptionally modified. PMCA1b is the only isoform of PMCA1 expressed in kidney and intestine. Calcitriol upregulates PMCA protein expression and activity and PMCA1 mRNA expression in the intestine. Calcitriol has a similar effect on kidney distal tubule PMCA activity in vivo but the cellular basis for this effect has not been studied. PMCA expression in Madin-Darby bovine kidney (MDBK) cells, a distal kidney tubule cell line, was compared with a proximal tubule (LLC-PK1) and embryonic (HEK 293) kidney cell line. Only MDBK cells express PMCA1b mRNA and PMCA protein. In MDBK cells, calcitriol increased steady state expression of PMCA1b mRNA and protein and upregulated the functional activity of PMCA on calcium transport to a similar degree. Furthermore, calcitriol enhanced PMCA1b mRNA stability. These data are consistent with in vivo localization studies demonstrating the distal kidney tubule localization of PMCA protein. Furthermore, they indicate that calcitriol is an important regulator of PMCA activity in the kidney distal tubule by a pathway that includes translation and posttranscriptional modification of PMCA1b.