Management of newly diagnosed glioblastoma multiforme: current state of the art and emerging therapeutic approaches

Glioblastoma multiforme represent > 50% of primary gliomas and have five year survival rates of ~ 5%. Maximal safe surgical resection followed by radiotherapy with concurrent and adjuvant temozolomide remains the standard treatment since published by Stupp et al. (in N Engl J Med 352:987-996, 2005), with additional benefit for patients with MGMT-methylated tumors. We review the current treatment landscape and ongoing efforts to improve these outcomes. An extensive literature search of Pubmed and Google Scholar involving the search terms "glioblastoma," "glioblastoma multiforme," or "GBM" for papers published to July 2021 was conducted and papers evaluated for relevance. As well as current data that informs clinical practice, we review ongoing clinical research in both newly diagnosed and recurrent settings that provides hope for a breakthrough. The Stupp protocol remains standard of care in 2021. Addition of tumor treating fields improved mOS modestly, with benefit seen in MGMT-methylated and unmethylated cohorts and also improved time to cognitive decline but has not been widely adopted. The addition of lomustine to temozolomide, in MGMT-methylated patients, also showed a mOS benefit but further investigation is required. Other promising therapeutic strategies including anti-angiogenic therapy, targeted therapy, and immunotherapy have yet to show a survival advantage. Improvements in the multidisciplinary management, surgical techniques and equipment, early palliative care, carrier support, and psychological support may be responsible for improving survival over time. Despite promising preclinical rationale, immunotherapy and targeted therapy are struggling to impact survival. A number of ongoing clinical trials provide hope for a breakthrough.

Risk factors for multi-joint disease in patients with glucocorticoid-induced osteonecrosis

This study investigated risk factors for osteonecrosis involving multiple joints (MJON) among glucocorticoid-treated patients. The best predictor of MJON was cumulative oral glucocorticoid dose. Risk of MJON was 12-fold higher in patients who had a second risk factor for osteonecrosis. Further research is needed into strategies for prevention of MJON.

INTRODUCTION

Osteonecrosis (ON) is a debilitating musculoskeletal condition in which bone cell death can lead to mechanical failure. When multiple joints are affected, pain and disability are compounded. Glucocorticoid treatment is one of the most common predisposing factors for ON. This study investigated risk factors for ON involving multiple joints (MJON) among glucocorticoid-treated patients.

METHODS

Fifty-five adults with glucocorticoid-induced ON were prospectively enrolled. MJON was defined as ON in ≥ three joints. Route, dose, duration, and timing of glucocorticoid treatment were assessed.

RESULTS

Mean age of enrolled subjects was 44 years, 58% were women. Half had underlying conditions associated with increased ON risk: systemic lupus erythematosus (29%), acute lymphoblastic leukemia (11%), HIV (9%), and alcohol use (4%). Mean daily oral dose of glucocorticoids was 29 mg. Average cumulative oral dose was 30 g over 5 years. The best predictor of MJON was cumulative oral glucocorticoid dose. For each increase of 1,000 mg, risk of MJON increased by 3.2% (95% CI 1.03, 1.67). Glucocorticoid exposure in the first 6 months of therapy, peak dose (oral or IV), and mean daily dose did not independently increase risk of MJON. The risk of MJON was 12-fold in patients who had a second risk factor (95% CI 3.2, 44.4).

CONCLUSIONS

Among patients with glucocorticoid-induced ON, cumulative oral dose was the best predictor of multi-joint disease; initial doses of IV and oral glucocorticoids did not independently increase risk. Further research is needed to better define optimal strategies for prevention and treatment of MJON.

Diabetic ketoacidosis and mortality in COVID-19 infection

Aim

- Patients with diabetes have increased morbidity and mortality from COVID-19. Case reports describe patients with simultaneous COVID-19 and diabetic acidosis (DKA), however there is limited data on the prevalence, predictors and outcomes of DKA in these patients.

Methods

- Patients with COVID-19 were identified from the electronic medical record. DKA was defined by standardized criteria. Proportional hazard regression models were used to determine risk factors for, and mortality from DKA in COVID-19.

Results

- Of 2366 patients admitted for COVID-19, 157 (6.6%) patients developed DKA, 94% of whom had antecedent type 2 diabetes, 0.6% had antecedent type 1 diabetes, and 5.7% patients had no prior diagnosis of diabetes. Patients with DKA had increased hospital length of stay and in-patient mortality. Higher HbA1c predicted increased risk of incident DKA (HR 1.47 per 1% increase, 95% CI 1.40–1.54). Risk factors for mortality included older age (HR 1.07 per 5 years, 95% CI 1.06–1.08) and need for pressors (HR 2.33, 95% CI 1.82–2.98). Glucocorticoid use was protective in patients with and without DKA.

Conclusion

- The combination of DKA and COVID-19 is associated with greater mortality, driven by older age and COVID-19 severity.

Low volumetric bone density is a risk factor for early complications after spine fusion surgery

This study aims to investigate lumbar spine (LS) volumetric bone density (vBMD) as a risk factor for complications (pseudoarthrosis, instrumentation failure, adjacent fractures), re-operation, and time to complication after fusion.

INTRODUCTION

Lumbar spine (LS) fusion surgery is increasingly performed worldwide. Complications after fusion result in significant morbidity and healthcare costs. Multiple factors, including osteoporosis, have been suggested to contribute to risk of complications and re-operation. However, most studies have used DXA, which is subject to artifact in patients with spine pathology, and none have investigated the relationship between BMD and timing of post-operative complications. This study aims to investigate LS volumetric bone density (vBMD) as a risk factor for complications (pseudoarthrosis, instrumentation failure, adjacent fractures), re-operation, and time to complication after fusion.

METHODS

We evaluated a cohort of 359 patients who had initial LS fusion surgery at our institution, had pre-operative LS CTs and post-operative imaging available for review. Demographic factors, smoking status, vBMD, and details of surgical procedure were related to likelihood and timing of post-operative complications.

RESULTS

Mean age was 60 ± 14 years, vBMD 122 ± 37 g/cm³. Median follow-up was 11 months. Skeletal complications occurred in 47 patients (13%); 34 patients (10%) required re-operation. Low vBMD (directly measured and estimated using HU) and smoking were associated with increased risk of skeletal complications. Each increase in baseline vBMD of 10 g/cm³ decreased the complication hazard and increased the complication-free duration in time-to-event analysis (hazard ratio 0.91, 95% CI 0.83-0.98, p < 0.02).

CONCLUSIONS

Low vBMD was a significant risk factor for early post-operative complications in patients undergoing LS fusion. Prospective studies are needed to confirm these findings and to elucidate the optimal timing for follow-up and strategies for prevention of post-operative complications in this population.

Correction to: Differences in bone quality and strength between Asian and Caucasian young men

The second name of the ninth author, X.E. Guo, was incorrectly coded as part of his surname. The publisher apologises for the inconvenience caused.

Frailty in Postmenopausal African American and Hispanic HIV-Infected Women

Studies suggest frailty occurs earlier in HIV-infected individuals, but data in postmenopausal HIV-infected women are lacking. We assessed the prevalence of frailty and association with anthropometric measures in HIV-infected and uninfected postmenopausal women. Fried's frailty phenotype was measured in HIV-infected and uninfected Hispanic and African American postmenopausal women participating in a study of bone metabolism; fat and lean mass were measured by whole body dual energy x-ray absorptiometry (DXA). Multivariable logistic regression evaluated frailty risk factors. The study was conducted at Columbia University Medical Center between 2002 and 2007. The participants were 61 HIV-infected and 27 uninfected Hispanic and African American postmenopausal women. The study compared prevalence and predictors of frailty in HIV-infected and uninfected postmenopausal women. Prevalence of frailty tended to be higher among HIV-infected than uninfected controls (11.5% vs 0% p=0.07). Surprisingly, among HIV-infected women, total body fat, not lean mass, was associated with frailty in multivariate analysis. Higher prevalence of frailty in African American and Hispanic HIV-infected postmenopausal women (11.5%) was similar to the 11% prevalence reported in minority women who were 10 years older in the general population. Our data suggest that frailty occurs earlier in HIV-infected postmenopausal women, but larger longitudinal studies are necessary to confirm whether musculoskeletal aging is accelerated by HIV infection.

Differences in bone quality and strength between Asian and Caucasian young men

This is a cross-sectional study to assess differences in bone quality in young Asian and Caucasian (n = 30/group) men between 25 and 35 years. We found that Asians had smaller bones, thicker and denser cortices, and more plate-like trabeculae, but stiffness did not differ between groups.

INTRODUCTION

We conducted a cross-sectional study to assess differences in bone quality in young Asian and Caucasian (n = 30/group) men between 25 and 35 years.

METHODS

We measured bone mineral density (BMD) at the spine, total hip (TH), femoral neck (FN), and forearm by dual energy X-ray absorptiometry (DXA), and bone geometry, density, microarchitecture, and mechanical competence at the radius and tibia by high-resolution peripheral quantitative computed tomography (HR-pQCT) with application of individual trabecula segmentation (ITS) and trabecular and whole bone finite element analysis (FEA). We measured load-to-strength ratio to account for differences in bone size and height, respectively. We used Wilcoxon rank sum and generalized linear models adjusted for height, weight, and their interaction for comparisons.

RESULTS

Asians were 3.9 % shorter and weighed 6.5 % less than Caucasians. In adjusted models: by DXA, there were no significant race-based differences in areal BMD; by HR-pQCT, at the radius, Asians had smaller total and trabecular area (p = 0.003 for both), and denser (p = 0.01) and thicker (p = 0.04) cortices at the radius; by ITS, at the radius Asians, had more plate-like than rod-like trabeculae (PR ratio p = 0.01), greater plate trabecular surface (p = 0.009) and longer rod length (p = 0.002). There were no significant race-based differences in FEA or the load-to-strength ratio.

CONCLUSIONS

Asians had smaller bones, thicker and denser cortices, and more plate-like trabeculae, but biomechanical estimates of bone strength did not differ between groups. Studies are needed to determine whether these differences persist later in life.

In vivo assessment of bone structure and estimated bone strength by first- and second-generation HR-pQCT

Bone strength is dependent on bone density and microstructure. High-resolution peripheral quantitative computed tomography (HR-pQCT) can measure microstructure but is somewhat limited due to its resolution. We compared a new HR-pQCT scanner to existing technology and found very good agreement for most parameters. This study will be important when interpreting results from different devices.

INTRODUCTION

Recently, a second-generation HR-pQCT scanner (XCT2) has been developed with a higher nominal isotropic resolution (61 μm) compared to the first-generation device (XCT1, 82 μm). It is unclear how in vivo measurements from these two devices compare. In this study, we obtained and analyzed in vivo XCT1 and XCT2 measurements of bone microarchitecture and estimated strength.

METHODS

We scanned 51 adults (16 men and 35 women, age 44.8 ± 16.0) on both XCT2 and XCT1 on the same day. We first compared XCT1 and XCT2 measurements obtained using their respective standard patient protocols. In XCT1, microarchitecture parameters were derived, while XCT2 measurements were directly measured. We also compared XCT2-D with XCT1 by finding the overlapping regions of interest and using the standard patient protocol for XCT1.

RESULTS

We obtained excellent agreement between XCT1 and XCT2 for most of the volumetric bone mineral density (vBMD), trabecular and cortical measurements (All R (2) > 0.820) except for cortical porosity at the radius (R (2) = 0.638), trabecular number (R (2) = 0.694, 0.787) and trabecular thickness (R (2) = 0.569, 0.527) at both radius and tibia, respectively. XCT1 and XCT2-D measurements also had excellent agreement for most of the measurements (all R (2) > 0.870) except trabecular number (R (2) = 0.524, 0.706), trabecular thickness (R (2) = 0.758, 0.734) at both radius and tibia, respectively, and trabecular separation (R (2) = 0.656) at the radius.

CONCLUSION

While some caution should be exercised for parameters that are more dependent on image resolution, results from our study indicate that second-generation scans can be compared to more widely available first-generation data and may be beneficial for multicenter and longitudinal studies using both scanner generations.

Low vitamin D levels have become less common in primary hyperparathyroidism

We compared temporal trends in serum 25-hydroxyvitamin D and parathyroid hormone (PTH) in two primary hyperparathyroidism (PHPT) cohorts recruited 20 years apart. The prevalence of 25-hydroxyvitamin D levels <20 and <30 ng/mL declined by 30-50 %, respectively, and was accompanied by lower PTH. In the older cohort, higher PTH may be due to lower 25-hydroxyvitamin D.

INTRODUCTION

Vitamin D deficiency may exacerbate PHPT. Whether there have been temporal trends in 25-hydroxyvitamin D (25OHD) levels in PHPT is unclear. The prevalence of low vitamin D levels (25OHD <20 and <30 ng/mL) and associated biochemical and bone mineral density (BMD) profiles were assessed in two PHPT cohorts recruited over 20 years apart.

METHODS

This is a cross-sectional comparison of serum 25OHD levels, calciotropic hormones, and BMD between two PHPT cohorts recruited at the same hospital: the "old" (N = 103) and "new" (N = 100) cohorts were enrolled between 1984 and 1991 and between 2010 and 2014, respectively.

RESULTS

Mean 25OHD levels were 26 % higher in the new cohort (23 ± 10 vs. 29 ± 10 ng/mL, p < 0.0001). Levels of 25OHD <20 and <30 ng/mL declined from 46 and 82 %, respectively, to 19 and 54 % (both p < 0.0001). Supplemental vitamin D use was common in the new (64 %) but not the old cohort (0 %). The new cohort demonstrated 33 % lower serum PTH levels (p < 0.0001). Neither serum nor urine calcium differed. BMD was higher in the new cohort at all skeletal sites (all p < 0.001).

CONCLUSION

With the rise in vitamin D supplementation over the last two decades, low 25OHD levels are no longer common in PHPT patients in the New York area. Those with 25OHD <20 and <30 ng/mL have declined by over 50 and 30 %, respectively. The lower mean PTH levels in the new cohort are most likely accounted for by higher vitamin D intake. Whether improved vitamin D status also underlies the relatively higher BMD in the more vitamin D replete cohort of PHPT patients is unknown.

Investigating the filled gel model in Cheddar cheese through use of Sephadex beads

Cheese can be modeled as a filled gel whereby milkfat globules are dispersed in a casein gel network. We determined the filler effects using Sephadex beads (GE Healthcare Life Sciences, Pittsburgh, PA) as a model filler particle. Ideally, such a model could be used to test novel filler particles to replace milkfat in low-fat cheese. Low-filler (6% particles), reduced-filler (16%), and full-filler (33%) cheeses were produced using either Sephadex beads of varying sizes (20 to 150 μm diameter) or milkfat. Small- and large-strain rheological tests were run on each treatment at 8, 12, and 18 wk after cheese manufacturing. Differences in rheological properties were caused primarily by the main effects of filler volume and type (milkfat vs. Sephadex), whereas filler size had no obvious effect. All treatments showed a decrease in deformability and an increase in firmness as filler volume increased above 25%, although the beads exhibited a greater reinforcing effect and greater energy recovery than milkfat.

A trabecular plate-like phenotype is overrepresented in Chinese-American versus Caucasian women

This study used extreme phenotype selection to define two trabecular bone phenotypes in a cohort of Chinese-American and Caucasian women. A trabecular plate-predominant phenotype is more common in Chinese-Americans while the rod-predominant phenotype is more typical of Caucasians. The robustness of these phenotypic associations with respect to lifestyle factors suggests that this trait may have a genetic basis and that these phenotypes can be utilized in future genetic studies.

INTRODUCTION

Compared to Caucasians, Chinese-Americans have more plate-like trabecular bone when measured by individual trabecula segmentation (ITS). These findings suggest a phenotypic difference between the races, which may be amenable to genetic analysis. We sought to identify a single ITS plate trait to pursue in genetic studies by conducting an extreme phenotype selection strategy to numerically define two distinct phenotypes-plate-like and rod-like-and determine whether the selected phenotypic associations were independent of lifestyle factors in order to conduct future genetic studies.

METHODS

A previously described cohort of 146 Chinese-American and Caucasian women with high-resolution peripheral quantitative computed tomography imaging and ITS analyses were studied with logistic regression and receiver operator characteristic analyses.

RESULTS

The tibial plate-to-rod (TPR) ratio was the best ITS discriminator of race. Using extreme phenotypic selection, two TPR ratio phenotypes were defined numerically: plate-like as a TPR ratio value in the highest quartile (≥1.336) and rod-like as a TPR ratio value in the lowest quartile (≤0.621). Women with a plate-like phenotype were 25.7 times more likely (95 % CI 7.3-90.1) to be Chinese-American than women with rod-like morphology. After controlling for constitutional and lifestyle covariates, women in the highest vs. lowest TPR ratio quartile were 85.0 times more likely (95 % CI 12.7-568.0) to be Chinese-American.

CONCLUSION

Using extreme phenotype selection, we defined a plate- and rod-like trabecular bone phenotype for the TPR ratio trait. The former phenotype is more common in Chinese-American women, while the latter is more typical of Caucasian women. The robustness of these phenotypic associations after controlling for differences in constitution and lifestyle suggest that the TPR ratio may have a genetic basis and that the extreme phenotypes defined in this analysis can be utilized for future studies.

Effects of rosiglitazone vs metformin on circulating osteoclast and osteogenic precursor cells in postmenopausal women with type 2 diabetes mellitus

CONTEXT

Thiazolidinediones are associated with increased fractures in type 2 diabetes mellitus (T2D). One explanation is that activation of peroxisome proliferator-activated receptor-γ expression alters bone remodeling cells.

OBJECTIVE

To investigate whether osteoclast and osteogenic precursor cells are altered by rosiglitazone (RSG) treatment in T2D as compared to metformin (MET) treatment.

DESIGN

A randomized controlled trial of RSG or MET for 52 weeks, followed by 24 weeks of MET.

SETTING

Data were generated at a tertiary care center.

PATIENTS

Seventy-three T2D postmenopausal women participated.

MAIN OUTCOME MEASURES

Peripheral blood mononuclear cells were isolated and cultured with receptor activator of nuclear factor κB ligand and stained for tartrate-resistant acid phosphatase to measure circulating osteoclast precursors. Peripheral blood mononuclear cells were also characterized for osteogenic, endothelial, and calcification markers by flow cytometry with the ligands osteocalcin (OCN), CD34, and CD 146.

RESULTS

Tartrate-resistant acid phosphatase-positive cells increased between weeks 0 and 52 (RSG, 2.9 ± 2 to 14.0 ± 3 U/L, P = .001; MET, 3.3 ± 2 to 16.7 ± 2 U/L, P = .001), increasing further in the RSG group after changing to MET (to 26.5 ± 5 U/L, P = .05 vs wk 52). With RSG, OCN+ cells with CD34 but without CD146 fell from weeks 0 to 52 (20.1 ± 1% to 15.5 ± 2%; P = .03), remaining stable through week 76. The OCN+ cells lacking both CD34 and CD146 increased from weeks 0 to 52 (67.3 ± 2 to 74.4 ± 2%; P = .02), but returned to baseline after switching to MET.

CONCLUSION

In postmenopausal women with T2D, circulating osteoclast precursor cells increase with both RSG and MET, and increase further when switching from RSG to MET. Subpopulations of cells that may be involved in the osteogenic lineage pathway are also altered with RSG. Further work is necessary to elucidate how these changes may relate to fracture risk.

Microbiology of Cheddar cheese made with different fat contents using a Lactococcus lactis single-strain starter

Flavor development in low-fat Cheddar cheese is typified by delayed or muted evolution of desirable flavor and aroma, and a propensity to acquire undesirable meaty-brothy or burnt-brothy off-flavor notes early in ripening. The biochemical basis for these flavor deficiencies is unclear, but flavor production in bacterial-ripened cheese is known to rely on microorganisms and enzymes present in the cheese matrix. Lipid removal fundamentally alters cheese composition, which can modify the cheese microenvironment in ways that may affect growth and enzymatic activity of starter or nonstarter lactic acid bacteria (NSLAB). Additionally, manufacture of low-fat cheeses often involves changes to processing protocols that may substantially alter cheese redox potential, salt-in-moisture content, acid content, water activity, or pH. However, the consequences of these changes on microbial ecology and metabolism remain obscure. The objective of this study was to investigate the influence of fat content on population dynamics of starter bacteria and NSLAB over 9 mo of aging. Duplicate vats of full fat, 50% reduced-fat, and low-fat (containing <6% fat) Cheddar cheeses were manufactured at 3 different locations with a single-strain Lactococcus lactis starter culture using standardized procedures. Cheeses were ripened at 8°C and sampled periodically for microbiological attributes. Microbiological counts indicated that initial populations of nonstarter bacteria were much lower in full-fat compared with low-fat cheeses made at all 3 sites, and starter viability also declined at a more rapid rate during ripening in full-fat compared with 50% reduced-fat and low-fat cheeses. Denaturing gradient gel electrophoresis of cheese bacteria showed that the NSLAB fraction of all cheeses was dominated by Lactobacillus curvatus, but a few other species of bacteria were sporadically detected. Thus, changes in fat level were correlated with populations of different bacteria, but did not appear to alter the predominant types of bacteria in the cheese.

Fortification of cheese with vitamin D3 using dairy protein emulsions as delivery systems

Vitamin D is an essential vitamin that is synthesized when the body is exposed to sunlight or after the consumption of fortified foods and supplements. The purpose of this research was to increase the retention of vitamin D(3) in Cheddar cheese by incorporating it as part of an oil-in-water emulsion using a milk protein emulsifier to obtain a fortification level of 280 IU/serving. Four oil-in-water vitamin D emulsions were made using sodium caseinate, calcium caseinate, nonfat dry milk (NDM), or whey protein. These emulsions were used to fortify milk, and the retention of vitamin D(3) in cheese curd in a model cheesemaking system was calculated. A nonemulsified vitamin D(3) oil was used as a control to fortify milk. Significantly more vitamin D(3) was retained in the curd when using the emulsified vitamin D(3) than the nonemulsified vitamin D(3) oil (control). No significant differences were observed in the retention of vitamin D(3) when emulsions were formulated with different emulsifiers. Mean vitamin D(3) retention in the model system cheese curd was 96% when the emulsions were added to either whole or skim milk compared with using the nonemulsified oil, which gave mean retentions of only 71% and 64% when added to whole and skim milk, respectively. A similar improvement in retention was achieved when cheese was made from whole and reduced-fat milk using standard manufacturing procedures on a small scale. When sufficient vitamin D(3) was added to produce cheese containing a target level of approximately 280 IU per 28-g serving, retention was greater when the vitamin D(3) was emulsified with NDM than when using nonemulsified vitamin D(3) oil. Only 58±3% of the nonemulsified vitamin D(3) oil was retained in full-fat Cheddar cheese, whereas 78±8% and 74±1% were retained when using the vitamin D(3) emulsion in full-fat and reduced-fat Cheddar cheese, respectively.

Endothelial function in mild primary hyperparathyroidism

BACKGROUND

It is not known if endothelial dysfunction, an important early event in the pathogenesis of atherosclerosis, is present in mild primary hyperparathyroidism (PHPT) and if so, whether it improves following parathyroidectomy.

DESIGN

We measured flow-mediated vasodilation (FMD), which estimates endothelial function by ultrasound imaging, in patients prior to and 6 and 12 months after parathyroidectomy.

RESULTS

Forty-five patients with mild PHPT [80% female, 61 ± 1 (mean ± SE) years, serum calcium 2·65 ± 0·03 mm (10·6 ± 0·1 mg/dl), PTH 10·5 ± 0·7 pm (99 ± 7 pg/ml), 25-hydroxyvitamin D (25OHD) 70·3 ± 3·7 nm (28·2 ± 1·5 ng/ml)] were studied. Baseline FMD was normal (4·63 ± 0·51%; reference mean: 4·4 ± 0·1%) and was not associated with serum calcium, PTH or 25OHD levels. In the group as a whole, FMD did not change after surgery (6 months: 4·38 ± 0·83%, P = 0·72; 12 months: 5·07 ± 0·74%, P = 0·49). However, in those with abnormal baseline FMD (<2·2%; n = 15), FMD increased by 350%, normalizing by 6 months after surgery (baseline: 0·81± 0·19%; 6 months: 3·18 ± 0·79%, P = 0·02 vs baseline; 12months: 3·68 ± 1·22%, P = 0·04 vs baseline). Baseline calcium, PTH and 25OHD levels did not differ between those with abnormal vs normal FMD, nor did these indices predict postoperative change in FMD.

CONCLUSIONS

FMD is generally normal in patients with mild PHPT and is unchanged 1 year after parathyroidectomy. Although FMD may normalize after surgery in patients with baseline abnormalities, data do not support using endothelial dysfunction as an indicator for parathyroidectomy.

Volumetric bone mineral density at the spine and hip in Chinese American and White women

This study evaluated racial differences in bone size and volumetric density at the spine and hip in pre- and postmenopausal Chinese American and White women. Compared with White women, Chinese American women have greater cortical volumetric bone density (vBMD) at the hip, congruent with the results at the peripheral skeleton.

INTRODUCTION

Chinese American women have lower rates of fracture than White women despite lower areal bone density. At the forearm and tibia, however, Chinese American women have higher cortical vBMD as well as greater trabecular and cortical thickness, but smaller bone area as measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) compared with White women. Since HR-pQCT data are obtained at peripheral sites, it is unclear whether these differences are relevant to the clinically important lumbar spine and hip. This study assesses racial differences in bone size and vBMD at the spine and hip in Chinese American and White women.

METHODS

QCT of the spine and hip was measured to assess racial differences in bone size, structure, and vBMD in pre- (n = 83) and postmenopausal (n = 50) Chinese American and White women. Data were adjusted for weight, height, physical activity, total calcium intake, parathyroid hormone, and 25-hydroxyvitamin D levels.

RESULTS

Among premenopausal women, lumbar spine trabecular vBMD was 5.8% greater in Chinese American versus White women (p = 0.01). At the hip, cortical vBMD was 3% greater at the femoral neck (p = 0.05) and 3.6% greater at the total hip (p = 0.01) in premenopausal Chinese American compared with White women. Among postmenopausal women, there was no difference in lumbar spine trabecular vBMD. Cortical vBMD was 4% greater at the total hip (p = 0.02) and tended to be greater at the femoral neck (p = 0.058) in Chinese American versus White women.

CONCLUSIONS

Consistent with earlier findings in the peripheral skeleton, cortical vBMD is greater at the hip in Chinese American versus White women.

Survival of microencapsulated probiotic Lactobacillus paracasei LBC-1e during manufacture of Mozzarella cheese and simulated gastric digestion

An erythromycin-resistant strain of probiotic Lactobacillus paracasei ssp. paracasei LBC-1 (LBC-1e) was added to part-skim Mozzarella cheese in alginate-microencapsulated or free form at a level of 10(8) and 10(7)cfu/g, respectively. Survival of LBC-1e and total lactic acid bacteria (LAB) was investigated through the pasta filata process of cheese making (in which the cheese curd was heated to 55 °C and stretched in 70 °C-hot brine), followed by storage at 4 °C for 6 wk and simulated gastric and intestinal digestion. This included incubation in 0.1 M and 0.01 M HCl, 0.9 M H(3)PO(4), and a simulated intestinal juice consisting of pancreatin and bile salts in a pH 7.4 phosphate buffer. Some reductions were observed in both free and encapsulated LBC-1e during heating and stretching, with encapsulated LBC-1e surviving slightly better. Changes in total LAB losses during heating and stretching did not reach statistical significance. During storage, a decrease was observed in total LAB, but no statistically significant decrease was observed in LBC-1e. Survival during gastric digestion in HCl was dependent on the extent of neutralization of HCl by the cheese, with more survival in the weaker acid, in which pH increased to 4.4 after cheese addition. The alginate microcapsules did not provide any protection against the HCl. It is interesting that survival of the encapsulated LBC-1e was greater during incubation in H(3)PO(4) than in the HCl gastric juices. Proper selection of simulated gastric digestion media is important for predicting the delivery of probiotic bacteria into the human intestinal tract. Neither free nor encapsulated LBC-1e was affected by incubation in the pancreatin-bile solution. Based on the level of probiotic bacteria in cheese needed to provide a health benefit and its survival during simulated gastric digestion, as determined in this study, it should theoretically be possible to lower the amount that needs to be ingested in cheese by up to a factor of 10(3) compared with other fermented dairy foods or when consumed as supplements.

Effect of parathyroidectomy on subclinical cardiovascular disease in mild primary hyperparathyroidism

OBJECTIVE

We recently demonstrated that mild primary hyperparathyroidism (PHPT) is associated with increased carotid intima-media thickness (IMT) and stiffness, and increased aortic valve calcification. It is unclear whether parathyroidectomy (PTX) improves these abnormalities. The purpose of this study was to determine whether cardiovascular abnormalities in PHPT improve with PTX.

DESIGN

Forty-four patients with PHPT were studied using carotid ultrasound and transthoracic echocardiography before and after PTX. Carotid IMT, carotid plaque and stiffness, left ventricular mass index (LVMI), myocardial and valvular calcification, and diastolic function were measured before, 1- and 2-year post-PTX.

RESULTS

Two years after PTX, increased carotid stiffness tended to decline to the normal range (17%, P=0.056) while elevated carotid IMT did not improve. Carotid plaque number and thickness, LVMI and cardiac calcifications did not change after PTX, while some measures of diastolic function (isovolumic relaxation time (IVRT) and tissue Doppler peak early diastolic velocity) worsened within the normal range. Indices did improve in patients with cardiovascular abnormalities at baseline. Increased carotid stiffness improved by 28% (P=0.004), a decline likely to be of clinical significance. More limited improvements also occurred in elevated IMT (3%, P=0.017) and abnormal IVRT (13%, P<0.05), a measure of diastolic dysfunction.

CONCLUSIONS

In mild PHPT, PTX led to modest changes in some cardiovascular indices. Improvements were mainly evident in those with preexisting cardiovascular abnormalities, particularly elevated carotid stiffness. These findings are reassuring with regard to current international guidelines that do not include cardiovascular disease as a criterion for PTX.

Reduced fracture risk with early corticosteroid withdrawal after kidney transplant

Corticosteroid use after kidney transplantation results in severe bone loss and high fracture risk. Although corticosteroid withdrawal in the early posttransplant period has been associated with bone mass preservation, there are no published data regarding corticosteroid withdrawal and risk of fracture. We hypothesized lower fracture incidence in patients discharged from the hospital without than with corticosteroids after transplantation. From the United States Renal Data System (USRDS), 77, 430 patients were identified who received their first kidney transplant from 2000 to 2006. Fracture incidence leading to hospitalization was determined from 2000 to 2007; discharge immunosuppression was determined from United Networks for Organ Sharing forms. Time-to-event analyses were used to evaluate fracture risk. Median (interquartile range) follow-up was 1448 (808-2061) days. There were 2395 fractures during follow-up; fracture incidence rates were 0.008 and 0.0058 per patient-year for recipients discharged with and without corticosteroid, respectively. Corticosteroid withdrawal was associated with a 31% fracture risk reduction (HR 0.69; 95% CI 0.59-0.81). Fractures associated with hospitalization are significantly lower with regimens that withdraw corticosteroid. As this study likely underestimates overall fracture incidence, prospective studies are needed to determine differences in overall fracture risk in patients managed with and without corticosteroids after kidney transplantation.

Premenopausal women with idiopathic low-trauma fractures and/or low bone mineral density

INTRODUCTION

In men, idiopathic osteoporosis (IOP) is often associated with low serum insulin-like growth factor (IGF-1) and reduced bone formation. The characteristics of premenopausal women with IOP are not well defined. We aimed to define the clinical, reproductive, and biochemical characteristics of premenopausal women with unexplained osteoporosis.

METHODS

This is a cross-sectional study of 64 women with unexplained osteoporosis, 45 with fragility fractures, 19 with low bone mineral density (BMD; Z-score less than or equal to -2.0) and 40 normal controls. The following are the main outcome measures: clinical and anthropometric characteristics, reproductive history, BMD, gonadal and calciotropic hormones, IGF-1, and bone turnover markers (BTMs).

RESULTS

Subjects had lower BMI and BMD than controls, but serum and urinary calcium, serum estradiol, vitamin D metabolites, IGF-1, and most BTMs were similar. Serum parathyroid hormone (PTH) and the resorption marker, tartrate-resistant acid phosphatase (TRAP5b), were significantly higher in both groups of subjects than controls and directly associated in all groups. Serum IGF-1 and all BTMs were directly associated in controls, but the association was not significant after controlling for age. There was no relationship between serum IGF-1 and BTMs in subjects. There were few differences between women with fractures and low BMD.

CONCLUSIONS

Higher serum TRAP5b and PTH suggest that increased bone turnover, possibly related to subclinical secondary hyperparathyroidism could contribute to the pathogenesis of IOP. The absence of differences between women with fractures and those with very low BMD indicates that this distinction may not be clinically useful to categorize young women with osteoporosis.

Survival of Listeria monocytogenes introduced as a post-aging contaminant during storage of low-salt Cheddar cheese at 4, 10, and 21°C

Traditional aged Cheddar cheese does not support Listeria monocytogenes growth and, in fact, gradual inactivation of the organism occurs during storage due to intrinsic characteristics of Cheddar cheese, such as presence of starter cultures, salt content, and acidity. However, consuming high-salt (sodium) levels is a health concern and the dairy industry is responding by creating reduced-salt cheeses. The microbiological stability of low-salt cheese has not been well documented. This study examined the survival of L. monocytogenes in low-salt compared with regular-salt Cheddar cheese at 2 pH levels stored at 4, 10, and 21°C. Cheddar cheeses were formulated at 0.7% and 1.8% NaCl (wt/wt) with both low and high pH and aged for 10 wk, resulting in 4 treatments: 0.7% NaCl and pH 5.1 (low salt and low pH); 0.7% NaCl and pH 5.5 (low salt and high pH); 1.8% NaCl and pH 5.8 (standard salt and high pH); and 1.8% NaCl and pH 5.3 (standard salt and low pH). Each treatment was comminuted and inoculated with a 5-strain cocktail of L. monocytogenes at a target level of 3.5 log cfu/g, then divided and incubated at 4, 10, and 21°C. Survival or growth of L. monocytogenes was monitored for up to 90, 90, and 30 d, respectively. Listeria monocytogenes decreased by 0.14 to 1.48 log cfu/g in all treatments. At the end of incubation at a given temperature, no significant difference existed in L. monocytogenes survival between the low and standard salt treatments at either low or high pH. Listeria monocytogenes counts decreased gradually regardless of a continuous increase in pH (end pH of 5.3 to 6.9) of low-salt treatments at all study temperatures. This study demonstrated that post-aging inoculation of L. monocytogenes into low-salt (0.7%, wt/wt) Cheddar cheeses at an initial pH of 5.1 to 5.5 does not support growth at 4, 10, and 21°C up to 90, 90, and 30 d, respectively. As none of the treatments demonstrated more than a 1.5 log reduction in L. monocytogenes counts, the need for good sanitation practices to prevent post-manufacturing cross contamination remains.

Reduced fracture risk with early corticosteroid withdrawal after kidney transplant

Corticosteroid use after kidney transplantation results in severe bone loss and high fracture risk. Although corticosteroid withdrawal in the early posttransplant period has been associated with bone mass preservation, there are no published data regarding corticosteroid withdrawal and risk of fracture. We hypothesized lower fracture incidence in patients discharged from the hospital without than with corticosteroids after transplantation. From the United States Renal Data System (USRDS), 77, 430 patients were identified who received their first kidney transplant from 2000 to 2006. Fracture incidence leading to hospitalization was determined from 2000 to 2007; discharge immunosuppression was determined from United Networks for Organ Sharing forms. Time-to-event analyses were used to evaluate fracture risk. Median (interquartile range) follow-up was 1448 (808-2061) days. There were 2395 fractures during follow-up; fracture incidence rates were 0.008 and 0.0058 per patient-year for recipients discharged with and without corticosteroid, respectively. Corticosteroid withdrawal was associated with a 31% fracture risk reduction (HR 0.69; 95% CI 0.59-0.81). Fractures associated with hospitalization are significantly lower with regimens that withdraw corticosteroid. As this study likely underestimates overall fracture incidence, prospective studies are needed to determine differences in overall fracture risk in patients managed with and without corticosteroids after kidney transplantation.

Fortification of Cheddar cheese with vitamin D does not alter cheese flavor perception

Currently, dietary guidelines for vitamin D consumption are under review, considering new information that >50% of the US population is vitamin D deficient, and may lead to a recommendation of a higher dietary intake of this vitamin. Vitamin D fortification of cheese aims to improve the current availability of fortified dairy foods beyond liquid milk. However, cheese is susceptible to undesirable flavor changes during long-term cheese ripening, and cheese bacteria and enzymes may degrade added vitamins. To test the retention of vitamin D(3) in Cheddar cheese curd, cheese milk was fortified initially during manufacture at a level of 150 IU/serving, using commercial sources that contained vitamin D(3) in powder, oil, or emulsion form, with and without homogenization of the fortified milk. When fortification was done directly to the cheese milk, we found that more than 80% vitamin D(3) was retained in cheese curd, irrespective of homogenization or form of fortification. Further, Cheddar cheese was fortified with the emulsion form of vitamin D(3) directly in cheese milk at 200 and 400 IU/serving to test stability and flavor changes. Vitamin D(3) fortified in this manner was stable for up to 9 mo in Cheddar cheese. Consumer acceptance and descriptive analysis of flavor profiles of cheese were also conducted and showed that vitamin D(3) fortified cheeses were equally liked by consumers, and cheese taste and flavor remained unaltered with vitamin D(3) addition even after aging for 9 mo.

Effects of HIV infection and antiretroviral therapy with ritonavir on induction of osteoclast-like cells in postmenopausal women

SUMMARY

Ritonavir (RTV) is a commonly used antiretroviral associated with bone loss. We show that peripheral blood mononuclear cells (PBMCs) from human immunodeficiency virus (HIV)-positive women on RTV are more likely to differentiate into osteoclast-like cells when cultured with their own sera than PBMCs and sera from HIV- women or HIV+ on other antiretrovirals.

INTRODUCTION

RTV increases differentiation of human adherent PBMCs to functional osteoclasts in vitro, and antiretroviral regimens containing RTV have been associated with low bone mineral density (BMD) and bone loss.

METHODS

BMD, proresorptive cytokines, bone turnover markers (BTMs), and induction of osteoclast-like cells from adherent PBMCs incubated either with macrophage colony-stimulating factor (MCSF) and receptor activator of nuclear factor κB ligand (RANKL) or with autologous serum were compared in 51 HIV- and 68 HIV+ postmenopausal women.

RESULTS

BMD was lower, and serum proresorptive cytokines and BTMs were higher in HIV+ versus HIV- women. Differentiation of osteoclast-like cells from adherent PBMCs exposed to either MCSF/RANKL or autologous serum was greater in HIV+ women. Induction of osteoclast-like cells was greater from PBMCs exposed to autologous sera from HIV+ women on RTV-containing versus other regimens (172 ± 14% versus 110 ± 10%, p < 0.001). Serum-based induction of osteoclast-like cells from adherent PBMCs correlated with certain BTMs but not BMD.

CONCLUSIONS

HIV infection and antiretroviral therapy are associated with higher BTMs and increased differentiation of osteoclast-like cells from adherent PBMCs, especially in women on regimens containing RTV. HIV+ postmenopausal women receiving RTV may be at greater risk for bone loss.

Vitamin D deficiency in HIV-infected postmenopausal Hispanic and African-American women

We evaluated vitamin D status in HIV+ and HIV- postmenopausal African-American (AA) and Hispanic women. Most women (74-78%) had insufficient 25-hydroxyvitamin D (25OHD) levels, regardless of HIV status. 25OHD was lower in AA women and women lacking supplement use, providing support for screening and supplementation. Among HIV+ women, 25OHD was associated with current CD4 but not type of antiretroviral therapy.

INTRODUCTION

To evaluate vitamin D status and factors associated with vitamin D deficiency and insufficiency in HIV-infected (HIV+) postmenopausal minority women.

METHODS

In this cross-sectional study, 89 HIV+ and 95 HIV- postmenopausal women (33% AA and 67% Hispanic) underwent assessment of 25OHD, 1,25-dihydroxyvitamin D, parathyroid hormone, markers of bone turnover and bone mineral density by dual energy X-ray absorptiometry.

RESULTS

The prevalence of low 25OHD did not differ by HIV status; the majority of both HIV+ and HIV- women (74-78%) had insufficient levels (<30 ng/ml). Regardless of HIV status, 25OHD was significantly lower in AA subjects, and higher in subjects who used both calcium and multivitamins. In HIV+ women on antiretroviral therapy (ART), 25OHD was directly associated with current CD4 count (r=0.32; p<0.01) independent of age, ethnicity, BMI, or history of AIDS-defining illness. No association was observed between 1,25(OH)(2)D and CD4 count or between serum 25OHD, 1,25(OH)(2)D or PTH and type of ART.

CONCLUSIONS

In postmenopausal minority women, vitamin D deficiency was highly prevalent and associated with AA race and lack of supplement use, as well as lower current CD4 cell count. These results provide support for screening and repletion of vitamin D in HIV+ patients.

Impact of fat reduction on flavor and flavor chemistry of Cheddar cheeses

A current industry goal is to produce a 75 to 80% fat-reduced Cheddar cheese that is tasty and appealing to consumers. Despite previous studies on reduced-fat cheese, information is critically lacking in understanding the flavor and flavor chemistry of reduced-fat and nonfat Cheddar cheeses and how it differs from its full-fat counterpart. The objective of this study was to document and compare flavor development in cheeses with different fat contents so as to quantitatively characterize how flavor and flavor development in Cheddar cheese are altered with fat reduction. Cheddar cheeses with 50% reduced-fat cheese (RFC) and low-fat cheese containing 6% fat (LFC) along with 2 full-fat cheeses (FFC) were manufactured in duplicate. Cheeses were ripened at 8°C and samples were taken following 2 wk and 3, 6, and 9 mo for sensory and instrumental volatile analyses. A trained sensory panel (n=10 panelists) documented flavor attributes of cheeses. Volatile compounds were extracted by solid-phase microextraction or solvent-assisted flavor evaporation followed by separation and identification using gas chromatography-mass spectrometry and gas chromatography-olfactometry. Selected compounds were quantified using external standard curves. Sensory properties of cheeses were distinct initially but more differences were documented as cheeses aged. By 9 mo, LFC and RFC displayed distinct burnt/rosy flavors that were not present in FFC. Sulfur flavor was also lower in LFC compared with other cheeses. Forty aroma-active compounds were characterized in the cheeses by headspace or solvent extraction followed by gas chromatography-olfactometry. Compounds were largely not distinct between the cheeses at each time point, but concentration differences were evident. Higher concentrations of furanones (furaneol, homofuraneol, sotolon), phenylethanal, 1-octen-3-one, and free fatty acids, and lower concentrations of lactones were present in LFC compared with FFC after 9 mo of ripening. These results confirm that flavor differences documented between full-fat and reduced-fat cheeses are not due solely to differences in matrix and flavor release but also to distinct differences in ripening biochemistry, which leads to an imbalance of many flavor-contributing compounds.

Parathyroid hormone stimulates circulating osteogenic cells in hypoparathyroidism

CONTEXT

The osteoanabolic properties of PTH may be due to increases in the number and maturity of circulating osteogenic cells. Hypoparathyroidism is a useful clinical model because this hypothesis can be tested by administering PTH.

OBJECTIVE

The objective of the study was to characterize circulating osteogenic cells in hypoparathyroid subjects during 12 months of PTH (1-84) administration.

DESIGN

Osteogenic cells were characterized using flow cytometry and antibodies against osteocalcin, an osteoblast-specific protein product, and stem cell markers CD34 and CD146. Changes in bone formation from biochemical markers and quadruple-labeled transiliac crest bone biopsies (0 and 3 month time points) were correlated with measurements of circulating osteogenic cells.

SETTING

The study was conducted at a clinical research center.

PATIENTS

Nineteen control and 19 hypoparathyroid patients were included in the study.

INTERVENTION

Intervention included the administration of PTH (1-84).

RESULTS

Osteocalcin-positive cells were lower in hypoparathyroid subjects than controls (0.7 ± 0.1 vs. 2.0 ± 0.1%; P < 0.0001), with greater coexpression of the early cell markers CD34 and CD146 among the osteocalcin-positive cells in the hypoparathyroid subjects (11.0 ± 1.0 vs. 5.6 ± 0.7%; P < 0.001). With PTH (1-84) administration, the number of osteogenic cells increased 3-fold (P < 0.0001), whereas the coexpression of the early cell markers CD34 and CD146 decreased. Increases in osteogenic cells correlated with circulating and histomorphometric indices of osteoblast function: N-terminal propeptide of type I procollagen (R(2) = 0.4, P ≤ 0.001), bone-specific alkaline phosphatase (R(2) = 0.3, P < 0.001), osteocalcin (R(2) = 0.4, P < 0.001), mineralized perimeter (R(2) = 0.5, P < 0.001), mineral apposition rate (R(2) = 0.4, P = 0.003), and bone formation rate (R(2) = 0.5, P < 0.001).

CONCLUSIONS

It is likely that PTH stimulates bone formation by stimulating osteoblast development and maturation. Correlations between circulating osteogenic cells and histomorphometric indices of bone formation establish that osteoblast activity is being identified by this methodology.

Rheological properties and microstructure of Cheddar cheese made with different fat contents

Reduced- and low-fat cheeses are desired based on composition but often fall short on overall quality. One of the major problems with fat reduction in cheese is the development of a firm texture that does not break down during mastication, unlike that observed in full-fat cheeses. The objective of this investigation was to determine how the amount of fat affects the structure of Cheddar cheese from initial formation (2 wk) through 24 wk of aging. Cheeses were made with target fat contents of 3 to 33% (wt/wt) and moisture to protein ratios of 1.5:1. This allowed for comparisons based on relative amounts of fat and protein gel phases. Cheese microstructure was determined by confocal scanning laser microscopy combined with quantitative image analysis. Rheological analysis was used to determine changes in mechanical properties. Increasing fat content caused an increase in size of fat globules and a higher percentage of nonspherical globules. However, no changes in fat globules were observed with aging. Cheese rigidity (storage modulus) increased with fat content at 10°C, but differences attributable to fat were not apparent at 25°C. This was attributable to the storage modulus of fat approaching that of the protein gel; therefore, the amount of fat or gel phase did not have an effect on the cheese storage modulus. The rigidity of cheese decreased with storage and, because changes in the fat phase were not detected, it appeared to be attributable to changes in the gel network. It appeared that the diminished textural quality in low-fat Cheddar cheese is attributed to changes in the breakdown pattern during chewing, as altered by fat disrupting the cheese network.

Therapy of hypoparathyroidism with intact parathyroid hormone

Hypoparathyroidism, a disorder characterized by low parathyroid hormone (PTH), is generally treated with oral calcium and vitamin D supplementation. We investigated the effects of PTH(1-84) treatment in 30 hypoparathyroid subjects for 24 months. PTH(1-84) treatment in hypoparathyroidism significantly reduced supplemental calcium and 1,25-dihydroxyvitamin D requirements without generally altering serum and urinary calcium levels.

INTRODUCTION

Hypoparathyroidism, a disorder characterized by low PTH, is associated with hypocalcemia, hypercalciuria, and increased bone mineral density (BMD). Conventional therapy with calcium and 1,25-dihydroxyvitamin D can maintain the serum calcium concentration, but doses are high, and control is variable. We investigated the effects of human PTH(1-84) treatment in hypoparathyroidism.

METHODS

Thirty subjects with hypoparathyroidism were treated in an open-label study of PTH(1-84) 100 µg every other day by subcutaneous injection for 24 months, with monitoring of calcium and vitamin D supplementation requirements, serum and 24 h urinary calcium excretion, and BMD by dual energy X-ray absorptiometry.

RESULTS

Requirements for supplemental calcium decreased significantly (3,030±2,325 to 1,661±1,267 mg/day (mean±SD); p<0.05), as did requirements for supplemental 1,25-dihydroxyvitamin D (0.68±0.5 to 0.40±0.5 µg/day; p<0.05). Serum calcium levels and 24 h urinary calcium excretion were mostly unchanged at 24 months. BMD increased at the lumbar spine by 2.9±4% from baseline (p<0.05), while femoral neck BMD remained unchanged and distal one third radial BMD decreased by 2.4±4% (p<0.05).

CONCLUSION

PTH(1-84) treatment in hypoparathyroidism significantly reduces supplemental calcium and 1,25-dihydroxyvitamin D requirements without generally altering serum and urinary calcium levels.

Cardiac structure and diastolic function in mild primary hyperparathyroidism

CONTEXT

Data on the presence, extent, and reversibility of cardiovascular disease in primary hyperparathyroidism (PHPT) are conflicting.

OBJECTIVE

To evaluate the heart in PHPT, we assessed cardiac structure and diastolic function in patients with mild PHPT compared with age- and sex-matched controls.

DESIGN

This was a case-control study.

SETTINGS

The study was conducted in a university hospital Metabolic Bone Diseases Unit.

PARTICIPANTS

Fifty-four men and women with PHPT and 76 controls without PHPT participated in the study.

OUTCOME MEASURES

We measured left ventricular mass index (LVMI), the presence of mitral annular calcification, the ratio of early to late diastolic mitral inflow velocities (E/A), and early diastolic velocity of the lateral mitral annulus using Doppler tissue imaging (tissue Doppler e').

RESULTS

Patients had mild disease with mean (+/-sd) serum calcium 10.5 +/- 0.5 mg/dl and PTH 96 +/- 45 pg/ml. LVMI and diastolic function were normal in PHPT. There was no difference in LVMI (98 +/- 23 vs. 96 +/- 24 g/m(2), P = 0.69) or the frequency of mitral annular calcification between PHPT cases and controls. Diastolic function variables (E/A and tissue Doppler e') were higher (better) in cases compared with controls, although both were within the reference range. PHPT patients with low E/A had higher serum PTH (121 +/- 36 vs. 89 +/- 46 pg/ml, P = 0.03) and calcium (10.8 +/- 0.4 vs. 10.5 +/- 0.5 mg/dl, P = 0.05) than those with normal values. Finally, we found LVMI to be inversely associated with serum 25-hydroxyvitamin D in PHPT (r = -0.29, P < 0.05). All findings persisted after adjustment for group differences in cardiovascular risk factors.

CONCLUSIONS

Patients with biochemically mild PHPT do not have evidence of increased left ventricular mass, diastolic dysfunction, or increased valvular calcifications. However, the data support an association between low vitamin D levels and the development of left ventricular hypertrophy in this disorder. Finally, the increased serum calcium and PTH levels in those with diastolic dysfunction suggest that disease severity may determine the presence of cardiac manifestations in PHPT.

Assessment of trabecular and cortical architecture and mechanical competence of bone by high-resolution peripheral computed tomography: comparison with transiliac bone biopsy

We compared microarchitecture and mechanical competence parameters measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite-element analysis of radius and tibia to those measured by histomorphometry, micro-CT, and finite-element analysis of transiliac bone biopsies. Correlations were weak to moderate between parameters measured on biopsies and scans.

INTRODUCTION

HR-pQCT is a new imaging technique that assesses trabecular and cortical bone microarchitecture of the radius and tibia in vivo. The purpose of this study was to determine the extent to which microarchitectural variables measured by HR-pQCT reflect those measured by the "gold standard," transiliac bone biopsy.

METHODS

HR-pQCT scans (Xtreme CT, Scanco Medical AG) and iliac crest bone biopsies were performed in 54 subjects (aged 39 +/- 10 years). Biopsies were analyzed by 2D quantitative histomorphometry and 3D microcomputed tomography (microCT). Apparent Young's modulus, an estimate of mechanical competence or strength, was determined by micro-finite-element analysis (microFE) of biopsy microCT and HR-pQCT images.

RESULTS

The strongest correlations observed were between trabecular parameters (bone volume fraction, number, separation) measured by microCT of biopsies and HR-pQCT of the radius (R 0.365-0.522; P < 0.01). Cortical width of biopsies correlated with cortical thickness by HR-pQCT, but only at the tibia (R = 0.360, P < 0.01). Apparent Young's modulus calculated by microFE of biopsies correlated with that calculated for both radius (R = 0.442; P < 0.001) and tibia (R = 0.380; P < 0.001) HR-pQCT scans.

CONCLUSIONS

The associations between peripheral (HR-pQCT) and axial (transiliac biopsy) measures of microarchitecture and estimated mechanical competence are significant but modest.

The effect of aging on low-fat, reduced-fat, and full-fat Cheddar cheese texture

This study investigated the effects of aging and fat content on the texture of Cheddar cheese, both mechanical and sensory aspects, over a 9-mo aging period. Cheeses of 6, 16, and 33% fat were tested at 0.5, 3, 6, and 9 mo of aging. Cheeses were evaluated by a trained sensory panel using an established texture lexicon as well as instrumental methods, which were used to probe cheese structure. Sensory analysis showed that low-fat cheeses were differentiated from full-fat cheeses by being more springy and firm and this difference widened as the cheeses aged. In addition, full-fat cheeses broke down more during chewing than the lower fat cheeses and the degree of breakdown increased with aging. Mechanical properties were divided by magnitude of deformation during the test and separated into 3 ranges: the linear viscoelastic region, the nonlinear region, and fracture point. These regions represent a stress/strain response from low to high magnitude, respectively. Strong relationships between sensory terms and rheological properties determined in the linear (maximum compliance) and nonlinear (critical stress and strain and a nonlinear shape factor) regions were revealed. Some correlations were seen with fracture values, but these were not as high as terms related to the nonlinear region of the cheeses. The correlations pointed to strain-weakening behavior being the critical mechanical property. This was associated with higher fat content cheeses breaking down more as strain increased up to fracture. Increased strain weakening associated with an increase in fat content was attributed to fat producing weak points in the protein network, which became initiation sites for fracture within the structure. This suggests that fat replacers need to serve this functional role.

Influence of brine concentration and temperature on composition, microstructure, and yield of feta cheese

The protein matrix of cheese undergoes changes immediately following cheesemaking in response to salting and cooling. Normally, such changes are limited by the amount of water entrapped in the cheese at the time of block formation but for brined cheeses such as feta cheese brine acts as a reservoir of additional water. Our objective was to determine the extent to which the protein matrix of cheese expands or contracts as a function of salt concentration and temperature, and whether such changes are reversible. Blocks of feta cheese made with overnight fermentation at 20 and 31 degrees C yielded cheese of pH 4.92 and pH 4.83 with 50.8 and 48.9 g/100 g of moisture, respectively. These cheeses were then cut into 100-g pieces and placed in plastic bags containing 100 g of whey brine solutions of 6.5, 8.0, and 9.5% salt, and stored at 3, 6, 10, and 22 degrees C for 10 d. After brining, cheese and whey were reweighed, whey volume measured, and cheese salt, moisture, and pH determined. A second set of cheeses were similarly placed in brine (n = 9) and stored for 10 d at 3 degrees C, followed by 10 d at 22 degrees C, followed by 10 d at 3 degrees C, or the complementary treatments starting at 22 degrees C. Cheese weight and whey volume (n = 3) were measured at 10, 20, and 30 d of brining. Cheese structure was examined using laser scanning confocal microscopy. Brining temperature had the greatest influence on cheese composition (except for salt content), cheese weight, and cheese volume. Salt-in-moisture content of the cheeses approached expected levels based on brine concentration and ratio of brine to cheese (i.e., 4.6, 5.7 and 6.7%). Brining at 3 degrees C increased cheese moisture, especially for cheese with an initial pH of 4.92, producing cheese with moisture up to 58 g/100 g. Cheese weight increased after brining at 3, 6, or 10 degrees C. Cold storage also prevented further fermentation and the pH remained constant, whereas at 22 degrees C the pH dropped as low as pH 4.1. At 3 degrees C, the cheese matrix expanded (20 to 30%), whereas at 22 degrees C there was a contraction and a 13 to 18 g/100 g loss in weight. Expansion of the protein matrix at 3 degrees C was reversed by changing to 22 degrees C. However, contraction of the protein matrix was not reversed by changing to 3 degrees C, and the cheese volume remained less than what it was initially.

Carotid vascular abnormalities in primary hyperparathyroidism

CONTEXT

Data on the presence, extent, and reversibility of cardiovascular disease in primary hyperparathyroidism (PHPT) are conflicting.

OBJECTIVE

This study evaluated carotid structure and function in PHPT patients compared with population-based controls.

DESIGN

This is a case-control study.

SETTING

The study was conducted in a university hospital metabolic bone disease unit.

PARTICIPANTS

Forty-nine men and women with PHPT and 991 controls without PHPT were studied.

OUTCOME MEASURES

We measured carotid intima-media thickness (IMT), carotid plaque presence and thickness, and carotid stiffness, strain, and distensibility.

RESULTS

IMT, carotid plaque thickness, carotid stiffness, and distensibility were abnormal in PHPT patients, and IMT was higher in patients than controls (0.959 vs. 0.907 mm, P < 0.0001). In PHPT, PTH levels, but not calcium concentration, predicted carotid stiffness (P = 0.04), strain (P = 0.06), and distensibility (P = 0.07). Patients with increased carotid stiffness had significantly higher PTH levels than did those with normal stiffness (141 +/- 48 vs. 94.9 +/- 44 pg/ml, P = 0.002), and odds of abnormal stiffness increased 1.91 (confidence interval = 1.09-3.35; P = 0.024) for every 10 pg/ml increase in PTH, adjusted for age, creatinine, and albumin-corrected calcium.

CONCLUSIONS

Mild PHPT is associated with subclinical carotid vascular manifestations. IMT, a predictor of cardiovascular outcomes, is increased. Measures of carotid stiffness are associated with extent of PTH elevation, suggesting that those with more severe PHPT may have impaired vascular compliance and that PTH, rather than calcium, is the mediator.

Vitamin D insufficiency prior to bariatric surgery: risk factors and a pilot treatment study

OBJECTIVE

To assess vitamin D status and the influences of race, sun exposure and dietary vitamin D intake on vitamin D levels, and to evaluate two vitamin D repletion regimens in extremely obese patients awaiting bariatric surgery.

METHODS

A cross-sectional analysis of dietary vitamin D, sun exposure, PTH [intact (iPTH) and PTH(1-84)] and 25-hydroxyvitamin D (25OHD; differentiated 25OHD2 and 25OHD3) in 56 obese [body mass index (BMI) > 35 kg/m(2)] men and women (age 20-64 years). In a pilot clinical trial, 27 subjects with 25OHD levels < 62 nmol/l were randomized to receive ergocalciferol or cholecalciferol for 8 weeks.

RESULTS

Serum 25OHD was low (mean 45 +/- 22 nmol/l) and was inversely associated with BMI (r = -0.36, P < 0.01). Each BMI increase of 1 kg/m(2) was associated with a 1.3 nmol/l decrease in 25OHD (P < 0.01). BMI, sun exposure, African American race and PTH predicted 40% of the variance in 25OHD (P < 0.0001). Serum 25OHD significantly increased at 4 and 8 weeks in both treatment groups (P < 0.001), whereas PTH(1-84) declined significantly in subjects treated with cholecalciferol (P < 0.007) and tended to decrease following ergocalciferol (P < 0.09).

CONCLUSIONS

In severely obese individuals, those who are African American, have higher BMI and limited sunlight exposure are at greatest risk for vitamin D insufficiency. These demographic factors can help to identify at-risk patients who require vitamin D repletion prior to bariatric surgery. Commonly prescribed doses of ergocalciferol and cholecalciferol are effective in raising 25OHD. Further investigation is needed to evaluate whether these regimens have differential effects on PTH, and to determine the optimal regimen for vitamin D repletion in the extremely obese patient.

The decline in hip bone density after gastric bypass surgery is associated with extent of weight loss

CONTEXT

Bariatric surgery is common and may be associated with deleterious effects on the skeleton.

OBJECTIVE

Our objective was to assess bone metabolism and bone mineral density (BMD) after Roux-en-Y gastric bypass.

DESIGN AND SETTING

We conducted a 1-yr prospective longitudinal study at a university hospital bariatric surgery practice and metabolic bone disease unit.

PARTICIPANTS

Participants included 23 obese (mean body mass index 47 kg/m(2)) men and women, aged 20-64 yr.

MAIN OUTCOME MEASURES

Serum PTH, 25-hydroxyvitamin D, osteocalcin, and urinary N-telopeptide, and BMD were assessed.

RESULTS

Patients lost 45 +/- 2 kg 1 yr postoperatively (P < 0.01). PTH increased early (3 months, 43-50 pg/ml; P < 0.001) and urinary calcium dropped (161-92 mg/24 h; P < 0.01), despite doubling of calcium intake (1318-2488 mg/d; P < 0.001). Serum 25-hydroxyvitamin D concentrations were unchanged (23-26 ng/ml), although vitamin D intake increased by 260% (658 IU/d at baseline to 1698 IU/d at 12 months; P < 0.05). Markers of bone remodeling rose (P < 0.01 for both urinary N-telopeptide and osteocalcin), whereas BMD decreased at the femoral neck (9.2%, P < 0.005) and at the total hip (8.0%, P < 0.005). These declines were strongly associated with the extent of weight loss (femoral neck: r = 0.90, P < 0.0001; and total hip: r = 0.65, P = 0.02). Lumbar spine and distal radius sites did not change.

CONCLUSIONS

After Roux-en-Y gastric bypass, there was evidence of calcium and vitamin D malabsorption. Bone turnover increased, and hip bone density rapidly declined. The decline in hip BMD was strongly associated with weight loss itself. Vigilance for nutritional deficiencies and bone loss in patients both before and after bariatric surgery is crucial.

Osteonectin/SPARC polymorphisms in Caucasian men with idiopathic osteoporosis

Animal models suggest a role for osteonectin/SPARC in determination of bone mass. We found haplotypes consisting of three single nucleotide polymorphisms (SNPs) in the 3' untranslated region (UTR) of the osteonectin gene are associated with bone density in Caucasian men with idiopathic osteoporosis.

INTRODUCTION

Osteonectin is a matricellular protein regulating matrix assembly, osteoblast differentiation, and survival. Animal studies indicate that osteonectin is essential for normal bone mass. The 3' UTR is a regulatory region controlling mRNA stability, trafficking, and translation, and we determined whether osteonectin 3' UTR haplotypes could be associated with bone mass and/or idiopathic osteoporosis.

METHODS

Single strand conformation polymorphism and allele-specific PCR analysis were used to assess alleles at osteonectin cDNA bases 1046, 1599, and 1970, using genomic DNA from middle-aged Caucasian men with idiopathic, low turnover osteoporosis (n = 56) and matched controls (n = 59). Bone density was measured by DXA at spine, hip and radius. Allele and haplotype frequencies were analyzed by Chi square analysis and Fisher's exact test.

RESULTS

Five common osteonectin 3' UTR haplotypes were identified. The frequency of one haplotype (1046C-1599C-1970T) was higher in controls compared with patients, and this haplotype was also associated with higher bone densities at multiple sites in patients. In contrast, a second haplotype (1046C-1599G-1970T) was associated with lower bone densities in patients at multiple sites.

CONCLUSIONS

Osteonectin regulates skeletal remodeling and bone mass in animals, and haplotypes in the 3' UTR of this gene are associated with bone density in Caucasian men with idiopathic osteoporosis.

Bone health in young women with epilepsy after one year of antiepileptic drug monotherapy

OBJECTIVE

Antiepileptic drugs (AEDs) may have adverse effects on bone mineral density (BMD) and metabolism. We previously reported biochemical evidence of increased bone turnover in premenopausal women with epilepsy on phenytoin monotherapy compared with those on carbamazepine, lamotrigine, and valproate. We therefore hypothesized that rates of bone loss would be higher in young women treated with phenytoin.

METHODS

Ninety-three premenopausal women with epilepsy receiving a single AED (carbamazepine, lamotrigine, phenytoin, or valproate) participated. Subjects completed nutritional and physical activity questionnaires. Biochemical indices of bone and mineral metabolism and BMD of the proximal femur and lumbar spine were measured at baseline and 1 year.

RESULTS

Participants reported high calcium intake (>1,000 mg/day) and were physically active. Significant loss (2.6%) was seen at the femoral neck in the phenytoin group. BMD remained stable in the other AED groups. Bone turnover markers and calciotropic hormones were unchanged after 1 year in all groups except for a significant decline in urine N-telopeptide in the phenytoin group. In women receiving phenytoin, lower serum 25-hydroxyvitamin D concentrations were associated with higher parathyroid hormone, bone alkaline phosphatase, and urine N-telopeptide levels, a biochemical pattern consistent with secondary hyperparathyroidism and increased remodeling.

CONCLUSION

In this study, young women treated with phenytoin had significant femoral neck bone loss over 1 year. In contrast, those treated with carbamazepine, lamotrigine, and valproate did not have detectable adverse effects on bone turnover or bone mineral density. These results raise concerns about the long-term effects of phenytoin monotherapy on bone in young women with epilepsy.

Sex differences in visceral adipose tissue post-bariatric surgery compared to matched non-surgical controls

OBJECTIVE AND METHODS: Given the profound weight loss after gastric banding and bypass we compared fat compartmentalization by whole body magnetic resonance imaging in women and men after these procedures to two groups of non-surgical controls who were either matched for age, weight and height or were of lower body mass index (BMI). RESULT: In women post-surgery (n=17; BMI 31.7 kg/m(2)) there was lower visceral adipose tissue (VAT) (1.4 vs 2.5 kg; P<0.01) compared with matched controls (n=59; BMI 32.1 kg/m(2)). In contrast, VAT (5.3 vs 5.4 kg) was nearly identical in men post-surgery (n=10; BMI 34.1 kg/m(2)) compared with matched controls (n=10; BMI 32.1 kg/m(2)) even though the degree of weight reduction was not significantly different from women (27.4 vs 32.6%). Furthermore, VAT when adjusted for total adipose tissue (TAT) was 43% less in women post-surgery (1.2 vs 2.1 kg; P=0.03) than in controls with lower BMI (25.1 kg/m(2)). After adjustment for TAT, subcutaneous adipose tissue in women post-surgery was significantly greater than matched controls (35.1 vs 34.2 kg; P=0.03). There was a significant negative correlation of VAT and the degree of weight loss in women (r=-0.57; P=0.018) but this relationship was not significant in men (r=-0.39; P=0.27). Skeletal muscle was lower in both sexes compared with matched controls (women, 21.8 vs 23.1 kg; men, 32.5 vs 35.5 kg). CONCLUSION: Prospective studies are necessary to confirm if there is a sexual dimorphism in the effects of bariatric surgery on body composition.

Normocalcemic primary hyperparathyroidism: further characterization of a new clinical phenotype

CONTEXT

Patients with elevated PTH and consistently normal serum calcium levels, in whom secondary causes of hyperparathyroidism have been excluded, may represent the earliest presentation of primary hyperparathyroidism (PHPT).

OBJECTIVE

The objective of the study was to characterize patients with normocalcemic PHPT referred to a bone disease unit.

DESIGN

This was a longitudinal cohort study.

SETTING

Ambulatory patients were referred to the metabolic bone disease unit.

PATIENTS

The study population included 37 patients [aged 58 yr, range 32-78; 95% female; serum calcium, 9.4 +/- 0.1 (sem) mg/dl (2.3 +/- 0.02 mmol/liter), reference range, 8.5-10.4 (2.1-2.6 mmol/liter); PTH, 93 +/- 5 pg/ml].

INTERVENTIONS

Interventions included yearly (median 3 yr; range 1-8 yr) physical examination, biochemical indices, and bone mineral density (BMD).

MAIN OUTCOME MEASURES

We measured the development of features of PHPT.

RESULTS

Evaluation for classical features of PHPT revealed a history of kidney stones in five (14%), fragility fractures in four (11%), and osteoporosis in 57% [spine (34%), hip (38%), and/or distal one third radius (28%)]. BMD did not show preferential bone loss at the distal one third radius (T scores: spine, -2.00 +/- 0.25; hip, -1.84 +/- 0.18; one third radius, -1.74 +/- 0.22). Further signs of PHPT developed in 40% (seven hypercalcemia; one kidney stone; one fracture; two marked hypercalciuria; six had >10% BMD loss at one or more site(s) including four patients developing World Health Organization criteria for osteoporosis). Seven patients (three hypercalcemic, four persistently normocalcemic) underwent successful parathyroidectomy.

CONCLUSIONS

Patients seen in a referral center with normocalcemic hyperparathyroidism have more substantial skeletal involvement than is typical in PHPT and develop more features and complications over time. These patients may represent the earliest form of symptomatic, rather than asymptomatic, PHPT.

Determinants of bone mineral density in Chinese-American women

SUMMARY

Few data are available regarding bone mineral density (BMD) and its determinants among Chinese Americans. We identified determinants of BMD among 359 Chinese-American women in order to identify risk factors for low BMD in this burgeoning population. BMD in Chinese-American women is influenced by a number of factors, including immigration.

INTRODUCTION

Osteoporosis and low BMD are common among Chinese women, including Chinese Americans, who are a growing population at risk for osteoporosis in the US. Few data are available regarding BMD and its determinants among Chinese-American women.

METHODS

In this study, we examined predictors of BMD in 359 ambulatory Chinese-American women, ages 20-90, using stepwise multiple regression analysis. Variables in the model included age, weight, height, menarche age, years since menopause, immigration age, years in US, percentage of life in US, number of pregnancies, oral contraceptive use, family history of osteoporosis, family history of hip fracture, daily calcium intake, exercise, time outdoors, alcohol consumption and tobacco use.

RESULTS

Among premenopausal women, weight was the strongest predictor of BMD, accounting for 10.5% of the variance at the lumbar spine (LS), 15.2% at the total hip (TH) and 16.6% at the femoral neck (FN). Time outdoors was also a positive predictor of BMD (1.4% at LS, 2.8% at TH and 1.6% at FN), while family history of osteoporosis (1.4% at TH) and age (3.7% at FN) were negative predictors. Among postmenopausal women, greater BMD at the LS and TH was associated with greater weight and earlier immigration age. Weight accounted for 16.4% of the variance at the LS and 19.8% at the TH; immigration age accounted for 3.1% of the variance at the LS and 4.1% at the TH. At the FN, years since menopause and weight were predictors of BMD, accounting for 14.4% and 8.7% of the variance, respectively. While older age at immigration had a negative effect on BMD, years in and proportion of life in the United States were not significant predictors of BMD.

CONCLUSIONS

Bone mineral density in Chinese-American women is influenced by a number of biological and lifestyle factors, including immigration. The results of this study provide new insights into risk factors for low bone density as they relate to environmental determinants in the growing population of Chinese-American women.

Influence of calcium, pH, and moisture on protein matrix structure and functionality in direct-acidified nonfat Mozzarella cheese

Influence of calcium, moisture, and pH on structure and functionality of direct-acid, nonfat Mozzarella cheese was studied. Acetic acid and citric acid were used to acidify milk to pH 5.8 and 5.3 with the aim of producing cheeses with 70 and 66% moisture, and 0.6 and 0.3% calcium levels. Cheeses containing 0.3% calcium were softer and more adhesive than cheeses containing 0.6% calcium, and flowed further when heated. Cheeses with the same calcium content (0.6%), the same moisture content, but set at different pH values (pH 5.3 and 5.8), exhibited no significant differences in melting or firmness. Increasing cheese moisture content from 66 to 70% produced a softer cheese but did not increase meltability. Such differences in functionality corresponded with differences in structure and arrangement of proteins in the cheese protein matrix. Microstructure of cheese with 0.6% calcium had an increase in protein folds and serum pockets compared with the 0.3% calcium cheeses that had a more homogeneous structure. Protein matrix in the low-calcium cheese appeared less dense indicating the proteins were more hydrated. In the 0.6% calcium cheeses, the proteins appeared more aggregated and had larger spaces between protein aggregates. Thus, between pH 5.3 and 5.8, calcium controls cheese functionality, and pH has only an indirect affect related to its influence on the calcium in cheese.