Citations

Abstract We report here the first association between vitamin D–resistant rickets, alopecia, and type 1 diabetes in a child with compound heterozygous mutations in the VDR gene. Transfection studies suggest dissociated effects of VDR gene mutations on the regulation of genes involved in vitamin D metabolism and dendritic cell maturation. Introduction: Whereas vitamin D may play a role in the immune tolerance process, no patient has been reported to associate hereditary vitamin D–resistant rickets (HVDRR) and an autoimmune disease, and no attempt has been made to delineate the outcome of mutations of the vitamin D receptor (VDR) on the transcription of genes controlling immune tolerance. Materials and Methods: The VDR gene was analyzed in a child with vitamin D–resistant rickets, total alopecia, and early childhood–onset type 1 diabetes. Patient's fibroblasts and COS-7 cells transfected with wildtype or mutant VDRs were studied for ligand-binding capacity, transactivation activity using two gene promoters [CYP-24, a classical 1,25(OH)2D3-responsive gene, and relB, a critical NF-κB component for regulation of dendritic cell differentiation], VDR-RXR heterodimers association to CYP 24 VDREs by gel mobility shift assays, and co-activator binding by Glutathione-S-transferase pull-down assays. Results: Two novel compound heterozygous mutations (L263R and R391S) were identified in the VDR ligand-binding domain in this child. Both mutations significantly impaired VDR ligand-binding capacity but had dissociated effects on CYP-24 and RelB promoter responses to vitamin D. CYP 24 response binding to SRC-1 and RXR-heterodimer binding to CYP24 VDREs were abolished in L263R mutants but normal or partially altered in R391S mutants. In the opposite, RelB responses to vitamin D were close to normal in L263R mutants but abolished in R391S mutants. Conclusions: We report the first clinical association between HVDRR, total alopecia, and early childhood–onset type 1 diabetes. Mutations in the VDR ligand-binding domain may hamper the 1,25(OH)2D3–mediated relB responses, an effect that depends on the site of the VDR mutation and cannot be anticipated from VDR ligand-binding ability or CYP-24 response. Based on these results, we propose to survey the immune function in patients with HVDRR, including those with moderate features of rickets.

The amount of thrombin active in vivo in the intravascular space (blood and endothelial surface), both basally and in experimental intravascular coagulation, is measured by way of the accessibility of thrombin to intravascular hirudin. Blood samples from pigs given intravenous 125I-labeled hirudin contain 125I-labeled hirudin-thrombin complex in concentrations indicative of a basal thrombin concentration in vivo of 0.5 nmol/liter. Intravenous infusion of Salmonella endotoxin elicits an increase in the circulating concentration of hirudin-thrombin complex that begins within 15 min and is 20-30 times basal after 4 hr. Induction of mild intravascular coagulation is evidenced by a modest reduction in plasma fibrinogen concentrations. It is concluded that there is a basal pool of hirudin-accessible thrombin in the intravascular space that, were it free in the plasma phase, would be sufficient in principle to sustain intravascular coagulation.

Type 2 diabetes is characterized by an ∼60% loss of β-cell mass, a marked defect in postprandial insulin secretion, and a failure to suppress postprandial glucagon concentrations. It is possible that postprandial hyperglucagonemia in type 2 diabetes is due to impaired postprandial insulin secretion. To address this, we studied eight adult Goettingen minipigs before and after an ∼60% reduction in β-cell mass induced by alloxan. Pigs were studied fasting and after ingestion of a mixed meal. Insulin and glucagon secretion were determined by deconvolution of blood hormone concentrations measured at 1-min intervals. The relationship between insulin and glucagon release was analyzed using cross-correlation and forward versus reverse cross–approximate entropy. We report that glucagon and insulin were secreted in ∼4-min pulses. Prealloxan, postprandial insulin secretion drove an ∼20% suppression of glucagon concentrations (P < 0.01), through inhibition of glucagon pulse mass. The alloxan-induced ∼60% deficit in β-cell mass lead to an ∼70% deficit in postprandial insulin secretion and loss of the postprandial insulin-driven suppression of glucagon secretion. We conclude that postprandial hyperglucagonemia in type 2 diabetes is likely due to loss of intraislet postprandial suppression of glucagon secretion by insulin.

Abstract ERα acts either through classical (ERE-mediated) or nonclassical (non-ERE) pathways. The generation of mice carrying a mutation that eliminates classical ERα signaling presents a unique opportunity to study the relative roles of these pathways in bone. This study defines the skeletal phenotype and responses to ovariectomy and estrogen replacement in these mice. Introduction: Estrogen receptor α (ERα) can act either through classical estrogen response elements (EREs) or through non-ERE (nonclassical) pathways. To unravel these in bone, we crossed mice heterozygous for a knock-in mutation abolishing ERE binding (nonclassical ERα knock-in [NERKI]) with heterozygote ERα knockout mice and studied the resulting female ERα+/+, ERα+/NERKI, and ERα−/NERKI mice. The only ERα present in ERα−/NERKI mice is incapable of activating EREs but can signal through nonclassical pathways, whereas ERα+/NERKI mice may have a less drastic alteration in the balance between classical and nonclassical estrogen signaling pathways. Materials and Methods: BMD was measured using DXA and pQCT at 3 months of age (n = 46–48/genotype). The mice were randomly assigned to sham surgery, ovariectomy, ovariectomy + estradiol (0.25 μg/day), or ovariectomy + estradiol (1.0 μg/day; n = 10–12/group) and restudied 60 days later. Results and Conclusions: At 3 months of age, both the ERα+/NERKI and ERα−/NERKI mice had deficits in cortical, but not in trabecular, bone. Remarkably, changes in cortical bone after ovariectomy and estrogen replacement in ERα−/NERKI mice were the opposite of those in ERα+/+ mice. Relative to sham mice, ovariectomized ERα−/NERKI mice gained more bone (not less, as in ERα+/+ mice), and estrogen suppressed this increase (whereas augmenting it in ERα+/+ mice). Estrogen also had opposite effects on bone formation and resorption parameters on endocortical surfaces in ERα−/NERKI versus ERα+/+ mice. Collectively, these data show that alteration of the balance between classical and nonclassical ERα signaling pathways leads to deficits in cortical bone and also represent the first demonstration, in any tissue, that complete loss of classical ERE signaling can lead to paradoxical responses to estrogen. Our findings strongly support the hypothesis that there exists a balance between classical and nonclassical ERα signaling pathways, which, when altered, can result in a markedly aberrant response to estrogen.

Abstract The relationship between BMD and fracture risk was estimated in a meta-analysis of data from 12 cohort studies of ∼39,000 men and women. Low hip BMD was an important predictor of fracture risk. The prediction of hip fracture with hip BMD also depended on age and z score. Introduction: The aim of this study was to quantify the relationship between BMD and fracture risk and examine the effect of age, sex, time since measurement, and initial BMD value. Materials and Methods: We studied 9891 men and 29,082 women from 12 cohorts comprising EVOS/EPOS, EPIDOS, OFELY, CaMos, Rochester, Sheffield, Rotterdam, Kuopio, DOES, Hiroshima, and 2 cohorts from Gothenburg. Cohorts were followed for up to 16.3 years and a total of 168,366 person-years. The effect of BMD on fracture risk was examined using a Poisson model in each cohort and each sex separately. Results of the different studies were then merged using weighted coefficients. Results: BMD measurement at the femoral neck with DXA was a strong predictor of hip fractures both in men and women with a similar predictive ability. At the age of 65 years, risk ratio increased by 2.94 (95% CI = 2.02-4.27) in men and by 2.88 (95% CI = 2.31-3.59) in women for each SD decrease in BMD. However, the effect was dependent on age, with a significantly higher gradient of risk at age 50 years than at age 80 years. Although the gradient of hip fracture risk decreased with age, the absolute risk still rose markedly with age. For any fracture and for any osteoporotic fracture, the gradient of risk was lower than for hip fractures. At the age of 65 years, the risk of osteoporotic fractures increased in men by 1.41 per SD decrease in BMD (95% CI = 1.33-1.51) and in women by 1.38 per SD (95% CI = 1.28-1.48). In contrast with hip fracture risk, the gradient of risk increased with age. For the prediction of any osteoporotic fracture (and any fracture), there was a higher gradient of risk the lower the BMD. At a z score of -4 SD, the risk gradient was 2.10 per SD (95% CI = 1.63-2.71) and at a z score of -1 SD, the risk was 1.73 per SD (95% CI = 1.59-1.89) in men and women combined. A similar but less pronounced and nonsignificant effect was observed for hip fractures. Data for ultrasound and peripheral measurements were available from three cohorts. The predictive ability of these devices was somewhat less than that of DXA measurements at the femoral neck by age, sex, and BMD value. Conclusions: We conclude that BMD is a risk factor for fracture of substantial importance and is similar in both sexes. Its validation on an international basis permits its use in case finding strategies. Its use should, however, take account of the variations in predictive value with age and BMD.

ABSTRACT Fosmidomycin is effective against malaria, but it needs to be given for ≥4 days when used alone. We conducted a study of 50 children with Plasmodium falciparum malaria to evaluate the safety and efficacy of consecutively shortened regimens of artesunate-fosmidomycin (1 to 2 mg/kg of body weight and 30 mg/kg of body weight, respectively; doses given every 12 hours). All dosing regimens were well tolerated. Artesunate-fosmidomycin acted rapidly, resulting in consolidated geometric mean parasite and fever clearance times of 24 h and 15 h, respectively. Treatment regimens of ≥2 days led to cure ratios of 100% by day 14 (39/39; 95% confidence interval [95% CI], 91% to 100%). Most importantly, the 3-day regimen achieved 100% cure on day 28 (10/10; 95% CI, 69% to 100%). Treatment with artesunate-fosmidomycin was associated with transient grade I or II neutropenia (absolute neutrophil counts of 750 to 1,200/μl and 400 to 749/μl, respectively) in six or two patients, respectively. Artesunate-fosmidomycin demonstrates the feasibility and potential value of short-course artemisinin-based combination chemotherapy with rapidly eliminated combination partners.

Currently no definitive biomarker of Alzheimer's disease (AD) is available, and this impedes both clinical diagnosis in humans and drug discovery in transgenic animal models. Proton magnetic resonance spectroscopy ( 1 H MRS) provides a noninvasive way to investigate in vivo neurochemical abnormalities. Each observable metabolite can potentially provide information about unique in vivo pathological processes at the molecular or cellular level. In this study, the age-dependent 1 H MRS profile of transgenic AD mice was compared to that of wild-type mice. Twenty-seven APP-PS1 mice (which coexpress mutated human presenilin 1 and amyloid-β precursor protein) and 30 wild-type mice age 66-904 days were examined, some repeatedly. A reduction in the levels of N -acetylaspartate and glutamate, compared with total creatine levels, was found in APP-PS1 mice with advancing age. The most striking finding was a dramatic increase in the concentration of myo -inositol with age in APP-PS1 mice, which was not observed in wild-type mice. The age-dependent neurochemical changes observed in APP-PS1 mice agree with results obtained from in vivo human MRS studies. Among the different transgenic mouse models of AD that have been studied with 1 H MRS, APP-PS1 mice seem to best match the neurochemical profile exhibited in human AD. 1 H MRS could serve as a sensitive in vivo surrogate indicator of therapeutic efficacy in trials of agents designed to reduce neurotoxicity due to microglial activation. Because of its noninvasive and repeatable nature, MRS in transgenic models of AD could substantially accelerate drug discovery for this disease.

Abstract OBJECTIVE The aim of our study was to analyze patterns of care and to identify prognostic factors in patients at least 18 years of age who received radiotherapy for malignant pineal parenchymal tumors. METHODS In a multicenter, retrospective study, we analyzed data for 37 previously published cases and 64 patients treated at the participating institutions. RESULTS A total of 56 patients received postoperative radiotherapy, and 45 patients received primary radiotherapy. Chemotherapy was administered to 34 patients. The median follow-up period was 38 months, and median overall survival was 100 months. The variables that significantly influenced overall survival were the extent of disease (localized versus disseminated; P = 0.0002), differentiation (pineal parenchymal tumor of intermediate differentiation versus pineoblastoma; P = 0.001), and residual disease (≥50% versus <50% reduction in size; P < 0.0001). In a multivariate analysis, the parameters turned out to be independent risk factors. The median survival in patients with local or spinal failure was 15 months. Local control was better in older patients (≥32 yr versus <32 yr; P = 0.02). Spinal control was more successful in patients with pineal parenchymal tumors of intermediate differentiation than it was in patients with pineoblastomas (P = 0.03). Nine of 45 treatment failures occurred later than 5 years after treatment. CONCLUSION Stage, histological characteristics, and response are independent risk factors in adults with malignant pineal parenchymal tumors. Late relapses are common.

SUMMARY The effects of nutrients on the mucosal immune system are poorly understood. The aim of this work was to study the cellular mucosal immune response to intrajejunal perfusion of an elemental diet (ED) or a control (C) electrolyte solution by measuring jejunal secretion of soluble CD4 (sCD4) and sCD8. sCD4 and sCD8 are markers of helper/inducer and suppressor/cytotoxic regulatory functions of T cells, respectively. A four lumen tube with a proximal occluding balloon at the angle of Treitz was used for jejunal perfusion in seven healthy volunteers (mean age 23 years). The length of the test segment was 40 cm. The jejunum was successively perfused with C for 80 min and then with ED containing 21.3g/l of free amino acids and 104.2g/l of oligosaccharides for 100 min. Jejunal fluid and serum concentrations of sCD4 and sCD8 were measured and their jejunal outputs calculated. When compared with C perfusion, jejunal perfusion with the ED resulted in a significant increase of sCD8 but not sCD4 jejunal secretion rates. sCD8 jejunal values increased early after ED perfusion and stayed at roughly the same level during the perfusion. Serum concentrations of sCD4 and sCD8 were not modified during ED perfusion. These data support the hypothesis that ED suppresses the immunologic tone of the gut, which could explain its beneficial effect in the management of intestinal inflammatory disease.