Therapeutic efficacy of 1alpha,25-dihydroxyvitamin D3 and calcium in osteopenic ovariectomized rats: evidence for a direct anabolic effect of 1alpha,25-dihydroxyvitamin D3 on bone

It is an important question for clinical therapy of osteoporosis with vitamin D metabolites whether these compounds exert their beneficial effects on the skeleton indirectly through an increase in intestinal calcium absorption or whether there is also a major direct component of action on bone. In this study, female 6-month-old Fischer rats were either ovariectomized (OVX) or sham operated. One month before surgery, all rats were placed on a diet containing 0.25% calcium and were kept on this diet throughout the study. Beginning 3 months post-OVX, groups of OVX rats orally received vehicle, a calcium supplement, low dose (0.025 microg/kg x day) or high dose (0.1 microg/kg x day) 1alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3], or combinations of low and high dose 1,25-(OH)2D3 with the calcium supplement. By 3 months postsurgery, pretreatment OVX controls had lost 74% and 37% of tibial and vertebral cancellous bone, respectively. Two-way factorial ANOVA showed that a 3-month treatment of osteopenic OVX rats with 1,25-(OH)2D3 dose dependently increased vertebral and tibial cancellous bone mass (P < 0.001 and P = 0.021, respectively) and trabecular width (P < 0.001). Furthermore, 1,25-(OH)2D3 increased serum calcium (P = 0.028) and urinary calcium excretion (P < 0.001) and reduced serum PTH levels (P < 0.001), osteoclast numbers (P < 0.001), and urinary collagen cross-links excretion (P < 0.001). Calcium supplementation alone was without therapeutic effect, and there was no significant two-way interaction between the individual treatment effects of 1,25-(OH)2D3 and calcium on bone mass. These data indicate that the anabolic effects of 1,25-(OH)2D3 in osteopenic OVX rats are mediated through a direct activity on bone.     

1alpha,25-dihydroxyvitamin D3 actions in LNCaP human prostate cancer cells are androgen-dependent

We and others have recently shown that 1alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] significantly inhibits cell proliferation and increases secretion of prostate-specific antigen (PSA) in LNCaP cells, an androgen-responsive human prostate cancer cell line. The present study was designed to investigate the possible interactions between 1,25-(OH)2D3 and androgens in the regulation of LNCaP cellular function. LNCaP cell growth was dose-dependently inhibited by 1,25-(OH)2D3 (60% inhibition at 10 nM) when cells were cultured in medium supplemented with FBS (FBS medium). 1,25-(OH)2D3-treated cells showed a 5-fold increase in PSA secretion, similar to the increase seen in dihydrotestosterone (DHT)-treated cells. In combination, 1,25-(OH)2D3 and DHT synergistically enhanced PSA secretion 22-fold. This synergistic effect was even greater when cells were cultured in medium supplemented with charcoal-stripped serum (CSS medium), where endogenous steroids are substantially depleted. Under these conditions, 1,25-(OH)2D3 and DHT together stimulated PSA secretion up to 50-fold over the untreated control. Radioligand binding assays and Western blot analyses showed that the androgen receptor (AR) content was increased significantly by 1,25-(OH)2D3 at 48 h. Furthermore, the steady-state mRNA level of AR was up-regulated approximately 2-fold by 1,25-(OH)2D3 at 24 h. When cells were grown in CSS medium, 1,25-(OH)2D3 alone no longer inhibited cell growth or induced PSA secretion. Titration experiments revealed that the addition of DHT at 1 nM to the medium restored the antiproliferative activity of 1,25-(OH)2D3. Conversely, an antiandrogen, Casodex, completely blocked 1,25-(OH)2D3 antiproliferative and PSA stimulation activities when cells were cultured in FBS medium. In conclusion, these results demonstrate that the antiproliferative and PSA induction activities of 1,25-(OH)2D3 in LNCaP cells are dependent upon androgen action and that AR up-regulation by 1,25-(OH)2D3 likely contributes to the synergistic actions of 1,25-(OH)2D3 and DHT in these cells.     

Pharmacokinetics and systemic effect on calcium homeostasis of 1 alpha,24-dihydroxyvitamin D2 in rats. Comparison with 1 alpha,25-dihydroxyvitamin D2, calcitriol, and calcipotriol

The purpose of this study was to compare 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET), hippocampal volumetry (HV), T2 relaxometry, and proton magnetic resonance spectroscopic imaging (1H-MRSI) in the presurgical neuroimaging lateralization of patients with nonlesional, electroencephalogram (EEG)-defined unilateral temporal lobe epilepsy (TLE). Twenty-five patients were prospectively studied, along with age-matched controls. T2 relaxometry examinations were performed in 13 patients. Comparison of FDG-PET, HV, and 1H-MRSI was possible in 23 patients. FDG-PET lateralized 87% of patients, HV 65%, N-acetyl aspartate (NAA)/(choline [Cho] + creatine [Cr]) 61%, and [NAA] 57%. Combined HV and NAA/(Cho + Cr) results lateralized 83% of the patients, a value similar to PET. Of 10 patients with normal magnetic resonance imaging (MRI) scans, 2 were lateralized with HV, 6 with FDG-PET, 4 with NAA/(Cho + Cr), and 3 with [NAA]. T2 relaxometry lateralized no patients without hippocampal atrophy. Bilateral abnormality was present in 29 to 33% of patients with 1H-MRSI measures and 17% with HV. Only hippocampal atrophy correlated with postoperative seizure-free outcome. FDG-PET remains the most sensitive imaging method to correlate with EEG-lateralized TLE. Both FDG-PET and 1H-MRSI can lateralize patients with normal MRI, but only the presence of relative unilateral hippocampal atrophy is predictive of seizure-free outcome. Bilaterally abnormal MRI and 1H-MRSI measures do not preclude good surgical outcome.     

1 alpha,25-Dihydroxyvitamin D3 rapidly increases nuclear calcium levels in rat osteosarcoma cells

A reversed-phase high-performance liquid chromatographic method is described for the measurement of plasma serotonin concentrations. Sample preparation is by a simple solid-phase extraction using C18 columns. An isocratic separation is used with electrochemical detection. The application of the method to the measurement of plasma serotonin concentrations following the administration of fluvoxamine (a serotonin re-uptake inhibitor), maprotiline (a noradrenaline re-uptake inhibitor) and placebo to normal subjects for a seven-day period is reported. Fluvoxamine significantly decreases plasma serotonin over this time period in a linear fashion. No effect on plasma serotonin was seen for maprotiline or placebo. Plasma serotonin concentrations can be used to monitor compliance with fluvoxamine therapy.     

Human keratinocyte line HaCaT metabolizes 1alpha-hydroxyvitamin D3 and vitamin D3 to 1alpha,25-dihydroxyvitamin D3 (calcitriol)

Monoclonal antibodies (MAbs) were generated against epitopes on yeast-like hyphal bodies and hyphae of the entomopathogenic hyphomycete, Nomuraea rileyi. Two MAbs (4C10, 2H4) bind to epitopes common to both hyphal bodies and hyphae, whereas MAb 4E9 binds only to hyphal surfaces. 4C10 and 2H4 appear to be directed towards carbohydrate portions of cell surface mannoproteins, as evidenced by similarities in staining patterns between these MAbs and Concanavalin A on Western blots of N. rileyi cell wall extracts. These MAbs cross-react with antigens on blastospore and hyphal surfaces of two other entomopathogenic fungi, Beauveria bassiana and Paecilomyces farinosus in fluorescence microscopy assays, but do not cross-react with a non-entomopathogenic strain of Candida albicans or with Saccharomyces cerevisiae yeasts. MAb 4C10 also cross-reacts with immunocompetent granular hemocytes from Spodoptera exigua (beet armyworm) and Trichoplusia ni (cabbage looper) larvae and with S. exigua plasmatocytes. Electron microscopy revealed that this MAb binds to a component in cytoplasmic granules in the hemocytes, and that surface labeling may be due to the release of this MAb-positive component upon degranulation. MAb 2H4 does not cross-react with granular hemocytes, but does bind to plasmatocytes and hemocytes that tightly adhere to the substrate in monolayer assays. Additionally, MAb 4C10 specifically labels a basement membrane epitope on S. exigua fat body, suggesting that this antibody binds to mannose residues on extracellular matrix glycoproteins. Cross-reactivity of these N. rileyi MAbs with insect hemocyte and tissue components indicates that fungal surface epitopes can mimic host surface molecules, which could explain why N. rileyi hyphal bodies are not recognized by granulocytes and are able to circulate freely in the hemolymph without binding to basement membranes lining the hemocoel.     

Association of 1 alpha,25-dihydroxyvitamin D3-occupied vitamin D receptors with cellular membrane acceptance sites

We previously reported nongenomic activation of ROS 17/2.8 cells by vitamin D metabolites (1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3], 25-hydroxyvitamin D3, 22-oxa-calcitriol, etc.). The hormone 1 alpha,25-(OH)2D3, or calcitriol, mediated rapid transient changes in intracellular free calcium levels and concomitant stimulation of inositol polyphosphate and diacylglycerol production. These effects resemble the mechanism of cell activation induced by ligands with plasma membrane (PM) receptors. As preliminary studies indicated that PM isolated from ROS 17/2.8 cells lacked specific binding sites for calcitriol alone, we studied the association between calcitriol-occupied vitamin D receptors (VDR) and ROS 17/2.8 cellular membranes. Saturable binding to the PM and the endoplasmic reticulum (ER) of calcitriol-occupied VDR was demonstrated. Binding of the VDR-[3H]calcitriol complex was displaceable by nonradioactive VDR/calcitriol, but not by the unoccupied VDR or by calcitriol alone. ER binding, but not PM binding, was competitively inhibited by a peptide from the VDR sequence recognized by an ER protein, calreticulin, and by an anticalreticulin antibody. The monoclonal antibody (9A7) against the VDR inhibited PM and ER binding of the hormone-occupied VDR. These results were substantiated by studies using baculovirus-expressed human VDR for binding studies with the PM and ER and for immunoblot analysis. We conclude that specific PM and ER sites of association for calcitriol-occupied VDR exist and suggest that these associations could participate in the nongenomic rapid actions of 1 alpha,25-(OH)2D3.     

Regulation of a novel immediate early response gene, IEX-1, in keratinocytes by 1alpha,25-dihydroxyvitamin D3

1alpha,25-Dihydroxyvitamin D3 [1alpha,25(OH)2D3] regulates cellular growth and differentiation. We show that in keratinocytes, 1alpha, 25(OH)2D3 reduces concentrations of the messenger RNA of IEX-1, the product of which blocks Fas- or tumor necrosis factor type alpha-induced apoptosis in various cells. In sub-confluent keratinocyte cultures, the addition of 1alpha,25(OH)2D3, in amounts that induce growth arrest, reduces IEX-1 mRNA concentrations. In confluent cells, 1alpha,25(OH)2D3 initially reduces and then increases IEX-1 mRNA concentrations. IEX-1 protein is localized in the nucleus and perinuclear region of keratinocytes. In sub-confluent cells, 1alpha,25(OH)2D3 translocates IEX-1 protein from the nucleus to the perinuclear region and cytoplasm. Since IEX-1 has recently been shown to regulate cell survival and number, we suggest that IEX-1 may play a role in keratinocyte growth and differentiation and that 1alpha,25(OH)2D3 may reduce keratinocyte growth via a reduction in IEX-1 mRNA and a change in the intracellular distribution of IEX-1 protein.     

Synthesis, stereochemistry, and biological activity of 1alpha,23,25-trihydroxy-24-oxovitamin D3, a major natural metabolite of 1alpha,25-dihydroxyvitamin D3

The C(23) epimers of 1alpha,23,25(OH)3-24-oxovitamin D3, a major natural metabolite of the secosteroid hormone, 1alpha,25(OH)2D3, were chemically synthesized for the first time. The metabolite was synthesized by palladium coupling of the appropriate CD ring analog with an A ring enyne. Various approaches from quinic acid to the A ring precursors were explored, and a new route to the A ring enyne from quinic acid was developed. The C(23) stereochemistry of the natural 1alpha,23,25(OH)3-24-oxovitamin D3 produced in neonatal human keratinocytes was determined to be S on the basis of the 1H NMR and the HPLC data. The biological activity of 1alpha,23(S), 25(OH)3-24-oxovitamin D3 in primary cultures of bovine parathyroid cells was determined by comparing the potency of this metabolite to that of 1alpha,25(OH)2D3 in suppression of parathyroid hormone (PTH) secretion. The results indicate that 1alpha,23(S), 25(OH)3-24-oxovitamin D3 potently suppressed PTH secretion even at concentrations as low as 10(-)12 M and is equipotent with 1alpha, 25(OH)2D3. The high activity of 1alpha,23(S),25(OH)3-24-oxovitamin D3 cannot be explained on the basis of its affinity for the vitamin D receptor as this metabolite was found to be 10 times less effective than radioinert 1alpha,25(OH)2D3 in blocking the uptake and receptor binding of [3H]-1alpha,25(OH)2D3 in intact parathyroid cells. Further studies are required to explain the molecular basis for the activity of 1alpha,23(S),25(OH)3-24-oxovitamin D3 in its ability to suppress PTH secretion. In summary, our present study indicates that the C(23) stereochemistry of the natural 1alpha,23, 25(OH)3-24-oxovitamin D3 is S and this metabolite is equipotent to 1alpha,25(OH)2D3 in suppressing PTH secretion.     

Synthesis and biological activity of 2-methyl-20-epi analogues of 1 alpha,25-dihydroxyvitamin D3

Synthesis and biological evaluation of all eight possible A-ring diastereomers of 2-methyl-20-epi-1,25-dihydroxyvitamin D3 are described. Among the analogues synthesized. 2 alpha-methyl-20-epi-1 alpha,25-dihydroxyvitamin D3 exhibited exceptionally high potency. The double modification of 2-methyl substitution and 20-epimerization yielded analogues with unique activity profiles.     

Analysis of 1alpha,25-dihydroxyvitamin D3 receptor in cell extracts with low protein concentration

Of 1190 patients with carcinoma of the uterine cervix, 15 (1.3%) developed skin metastases. The incidence of skin metastasis was 0.8% in stage I, 1.2% in stage II, 1.2% in stage III, and 4.8% in stage IV. The incidence of skin metastasis seemed to be higher in patients with adenocarcinoma and undifferentiated carcinoma than in patients with squamous cell carcinoma. The interval between the diagnoses of cervical cancer and skin metastasis ranged from 0 to 69 months, with a mean of 16.9 months. The most common sites of skin lesions were the abdominal wall and vulva, followed by the anterior chest wall. Skin lesions presented as nodules in 86.7% (13/15), and 66.7% of the patients had multiple lesions. Skin metastasis was detected as the initial metastatic lesion in 9 patients. However, only 4 patients had neither local recurrence nor other distant metastasis at the time of diagnosis of skin metastasis. The prognosis was grave, but 3 patients survived more than 12 months after the diagnosis of skin metastasis. The main treatment for these patients was extirpation of the skin lesion followed by radiotherapy.     

Differential apoptotic response of human melanoma cells to 1 alpha,25-dihydroxyvitamin D3 and its analogues

Pleiotropic actions of the biologically active form of vitamin D3, 1 alpha,25-dihydroxyvitamin D3 (VD), include antiproliferative effects in both normal human melanocytes and malignant melanoma cell lines. In this study the actions of VD and its low calcemic analogues EB1089 and CB1093, have been examined in two human melanoma cell lines MeWo and WM1341. Both cell lines express similar amounts of vitamin D receptor mRNA and show functional gene regulatory effects in response to VD and its analogues. VD, EB1089 and CB1093 induced apoptosis only in WM1341 cells and not in MeWo cells, even though both cell lines responded well to etoposide, a strong inducer of apoptosis. Additionally, these results were confirmed by analysis of cell morphology. Interestingly in WM1341 cells, CB1093 was found to be more potent in inducing apoptosis than EB1089 and the natural hormone. Moreover, CB1093 appeared to induce apoptosis at a relatively low concentration of 0.1 nM, whereas greater than tenfold higher concentrations of VD and EB1089 were needed to obtain comparable effects. These observations highlight CB1093 as a promising drug for a future treatment against specific types of melanoma.     

Inhibitory effect of 1alpha,25-dihydroxyvitamin D3 on allogeneic lymphocyte stimulation and Langerhans cell maturation

1alpha,25-Dihydroxyvitamin D3 (calcitriol) has been shown to inhibit the proliferation of peripheral blood mononuclear cells induced by allogeneic Langerhans cells in a human mixed epidermal cell lymphocyte reaction. The potent antigen-presenting function of Langerhans cells is gained during culture. We tried to dissect the effect of calcitriol on lymphocyte proliferation and Langerhans cell maturation in a murine mixed epidermal cell lymphocyte reaction using unfractioned epidermal cells as a source for Langerhans cells. First, calcitriol was added upon setup of the mixed epidermal cell lymphocyte reaction using cultured epidermal cells as antigen-presenting cells, and this was found to inhibit the proliferation of lymphocytes in a time- and concentration-dependent manner. When calcitriol was added only during preculture of freshly isolated epidermal cells, the subsequent mixed epidermal cell lymphocyte reaction was also inhibited. In addition, the growth of keratinocytes and the production of granulocyte/macrophage colony-stimulating factor during preculture of epidermal cells was completely inhibited. Supplementation with this growth factor only partially restored the proliferative response of lymphocytes. These results suggest that calcitriol inhibits both the alloantigen-driven stimulation of naive T cell and Langerhans cells maturation. Further experiments with purified Langerhans cells are required to elucidate the mechanism of action of calcitriol on Langerhans cell maturation.     

Synthesis and biological activities of 2 beta-chloro-, 2 beta-fluoro-, and 2 beta-methoxy-1 alpha,25-dihydroxyvitamin D3

Using 1 alpha,2 alpha-oxido-cholesta-5,7-diene-3 beta,25-diol (2) as a starting material, the provitamins of calcitriol with an additional 2 beta-chloro-, 2 beta-fluoro-, and 2 beta-methoxy-substituent (3,4,5) are obtained by transdiaxial opening of the oxirane ring with nucleophiles. An efficient irradiation process is described and used for the synthesis of the 2 beta-substituted calcitriols NS2 (2 beta-Cl), NS6 (2 beta-F), and NS7 (2 beta-OCH3). The affinity of these three vitamin D3 derivatives to the vitamin D receptor (VDR) and was determined. These three A-ring derivatives of 1,25(OH)2D3 were further tested for their proliferation-inhibitory and anti-adipogenic activity and gene regulatoric activity in the vitamin D3-sensitive, murine, mesenchymal cell line C3H10T1/2. The VDR-affinity of the 2 beta-chloro derivative, NS2 (2 beta-Cl), was identical to 1,25(OH)2D3 and its vitamin D binding protein (DBP)-affinity was in the range of 1,25(OH)2D3. NS2 inhibited the proliferation of C3H10T1/2(BMP-4)-cells in the presence of fetal calf serum (FCS) 9 times, and, in the absence of FCS, 111 times lower, as compared with 1,25(OH)2D3. The ID50 dose of adipogenesis-inhibition of NS2 was 13 times higher than the ID50 dose of 1,25(OH)2D3. NS6 (2 beta-F) displayed a slightly higher affinity than 1,25(OH)2D3 to the VDR and DBP-affinity. The proliferation-inhibitory activity in the presence of FCS was 90 times higher, as compared with 1,25(OH)2D3. In the FCS-free proliferation assay NS6 displayed an inhibitory activity in the range of 1,25(OH)2D3. NS6 showed an 5 times higher potency to inhibit (pre)adipocyte-differentiation in C3H10T1/2(BMP-4)-cells than 1,25(OH)2D3. NS7 (2 beta-OCH3) showed the lowest VDR-affinity and the highest DBP-affinity of the tested substances, as compared with 1,25(OH)2D3 (11 times lower and 35 times higher respectively). Its proliferation-inhibitory activity in the FCS-free medium was 9 times and in the FCS-containing assay 67 times lower in comparison with 1,25(OH)2D3. A 1250 times higher NS7-dose was needed to reach the anti-adipogenic potency of 1,25(OH)2D3. All tested substances displayed a similar ability to activate a vitamin D responsive element-regulated reporter gene compared to 1,25(OH)2D3 (NS2 and NS6: 1.3 times higher activity; NS7: 1,4 times lower activity).     

Serum 1alpha,25-dihydroxyvitamin D3 accumulates into the fracture callus during rat femoral fracture healing

1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is thought to be an important systemic factor in the fracture repair process, but the mechanism of action of 1,25(OH)2D3 has not been clearly defined. In this study, the role of 1,25(OH)2D3 in the fracture repair process was analyzed in a rat closed femoral fracture model. The plasma concentration of 1,25(OH)2D3 rapidly decreased on day 3 and continued to decrease to 10 days after fracture. We assessed whether this decrease was based on the accelerated degradation or retardation of the synthesis rate of 1,25(OH)2D3, from 25(OH)D3. After radiolabeled 3H-1,25(OH)2D3 or 3H-25(OH)D3 was injected i.v. into fractured or control (unfractured) rats, the concentrations of 25(OH)D3 and 1,25(OH)2D3 metabolites were measured by HPLC. The plasma concentrations of these radiolabeled metabolites in fractured group were similar to those in control rats early after operation. However, radioactivity in the femurs of fractured rats was higher than that of the control group. Furthermore, the radioactivity was concentrated in the callus of the fractured group analyzed by autoradiography. 1,25(OH)2D3 receptor gene expression was detected early after fracture and, additionally, both in the soft and hard callus on days 7 and 13 after fracture. These results showed that the rapid disappearance of 1,25(OH)2D3 in the early stages after fracture was not due to either increased degradation or decreased synthesis of 1,25(OH)2D3, but rather to increased consumption. Further, these results suggest the possibility that plasma 1,25(OH)2D3 becomes localized in the callus and may regulate cellular events in the process of fracture healing.     

Vitamin D receptor expression, 24-hydroxylase activity, and inhibition of growth by 1alpha,25-dihydroxyvitamin D3 in seven human prostatic carcinoma cell lines

Although prostatic cancer is often viewed as an androgen-dependent malignancy, a number of other hormones including 1alpha, 25-dihydroxyvitamin D3 [1alpha,25(OH)2D3] are now recognized to modulate its growth and differentiated phenotype. Seven different continuous human prostatic carcinoma cell lines were examined for the presence of biologically active receptors for 1alpha,25(OH)2D3. All seven lines were found to contain mRNA for the vitamin D receptor using an RNase protection assay. Six of the seven cell lines were found to have high-affinity saturable binding sites for 1alpha,25(OH)2D3. The seventh line was found to contain vitamin D receptors by sucrose gradient analysis. All seven lines were found to express 24-hydroxylase activity by a HPLC assay that measures the conversion of 25-hydroxyvitamin D3 to 24,25-dihydroxyvitamin D3. 24-Hydroxylase activity was up-regulated in all seven cell lines by preincubation with 1alpha,25(OH)2D3. In the presence of fetal bovine serum, the growth of four of the seven cell lines was inhibited. In the majority of cell lines growth inhibition was related not only to the number of receptors per cell, but also in inverse proportion to the 24-hydroxylase activity of each cell line. The ubiquitous presence of vitamin D receptor and 24-hydroxylase activity in human prostatic carcinoma cells suggests new alternatives for the pharmacological treatment of advanced prostatic cancer and implies that chemoprevention strategies could also make use of this endocrine axis.     

Partial prevention of active Heymann nephritis by 1 alpha, 25 dihydroxyvitamin D3

The hormone 1 alpha, 25 dihydroxyvitamin D3 (1,25(OH)2D3) has potent immunosuppressive effects in vitro. Recent publications also described a protective effect of the hormone in various animal models of immune-mediated diseases. To test its in vivo activity we induced active Heymann nephritis in Lewis rats that were either untreated or treated with 1,25(OH)2D3 or its synthetic 20-epi analogue, KH1060. Treatment with cyclosporine A (CsA) was used as an immunosuppressive control. In this nephrotic model the administration of 1,25(OH)2D3 (0.5 microgram/kg body weight) given on alternate days during the first 13 days after active immunization significantly reduced the proteinuria as measured by weeks 7-9. This reduction was comparable to the reduction observed in rats treated with CsA (20 mg/kg) on alternate days. A second series of experiments with 1,25(OH)2D3 confirmed these findings. The level of autoantibodies was found to be significantly suppressed during the treatment time in the CsA (20 mg/kg) group, whereas the limit of significance (P = 0.06) was reached in the 1,25(OH)2D3 (0.5 microgram/kg) group. The size of the immune deposits also was found to be substantially smaller in the groups that developed less proteinuria. The administration of 1,25(OH)2D3 transiently increased the mean serum calcium concentration with 2.5 mg/dl above the pretreatment values, and the urinary calcium excretion by a factor of 3-5 during the short treatment time. Treatment with the analogue KH1060 did not reduce the proteinuria significantly. Our experiments add evidence to the hypothesis that 1,25(OH)2D3 in pharmacological doses has immunosuppressive potency.     

Serum concentration of calcium, 1,25 vitamin D and parathyroid hormone are not correlated with coronary calcifications. An electron beam computed tomography study

As a consequence of contamination by effluents from local electronics manufacturing facilities, the New Bedford Harbor and estuary in southeastern Massachusetts is among the sites in the United States that are considered the most highly contaminated by polychlorinated biphenyls (PCBs). Since 1993, measures of intrauterine PCB exposure have been obtained for a sample of New Bedford area infants. Among 122 mother-infant pairs, we identified four milk samples with total PCB levels that were significantly higher than the rest, with estimated total PCBs ranging from 1,100 to 2,400 ng/g milk fat compared with an overall mean of 320 ng/g milk fat for the 122 women. The congener profile and history of one case was consistent with past occupational PCB exposures. Otherwise, the source of PCB exposures in these cases was difficult to specify. Environmental exposures including those from fish consumption were likely, whereas residence adjacent to a PCB-contaminated site was considered an unlikely exposure source. In all four cases, the infants were full-term, healthy newborns. Because the developing nervous system is believed to be particularly susceptible to PCBs (for example, prenatal PCB exposures have been associated with prematurity, decrements in birth weight and gestation time, and behavioral and developmental deficits in later infancy and childhood, including decrements in IQ), it is critical to ascertain if breast-feeding is a health risk for the women's infants. Despite the potential for large postnatal PCB exposures via breast milk, there is limited evidence of significant developmental toxicity associated with the transmission of moderate PCB concentrations through breast milk. Breast-feeding is associated with substantial health benefits including better cognitive skills among breast-fed compared with formula-fed infants. We conclude, based on evidence from other studies, that the benefits of breast-feeding probably outweigh any risk from PCB exposures via breast milk among the four New Bedford infants. In this case report, PCB analysis of breast milk and infant cord serum was a research tool. PCB analysis of milk is rarely done clinically, in part because it is difficult to use the results of such analyses to predict health risks. Substantial effort is needed to achieve a better understanding of the clinical and public health significance of PCB exposures, particularly among potentially susceptible groups such as infants and children. Such efforts are critical to improving the clinical and public health management of widespread and ongoing population exposures to PCBs.