Biomedical subjects
D Feldman
Publications and source records attributed to D Feldman.
Conventional and molecular cytogenetic identification of a variant klinefelter syndrome patient with a deleted X chromosome.
We report on the case of a 34-year-old patient with the Klinefelter syndrome and an unusual cytogenetic finding of a deletion involving the short arm of the X chromosome. This was confirmed with fluorescent in situ hybridization (FISH) using an X chromosome-specific whole chromosome painting probe. The patient presented with infertility. The only abnormal physical findings were atrophic testes with azoospermia and elevated levels of follicle-stimulating hormone and luteinizing hormone. This case represents a relatively mild manifestation of the Klinefelter syndrome. Previous reported cases were often associated with more severe phenotypes such as variable degrees of mental retardation and facial dysmorphism, hypothesized as due to the failure of X inactivation. The X inactivation center, located on Xq13, is presumably intact in our patient, who had a deletion involving only the short arm. The mild phenotype observed in our patient was found to be consistent with the conventional and molecular cytogenetic findings.
The vitamin D receptor and the syndrome of hereditary 1,25-dihydroxyvitamin D-resistant rickets.
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Induction of androgen receptor by 1alpha,25-dihydroxyvitamin D3 and 9-cis retinoic acid in LNCaP human prostate cancer cells.
We have recently shown that 1alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] inhibits proliferation of LNCaP cells, an androgen-responsive human prostate cancer cell line. Also, 1,25-(OH)2D3 increases androgen receptor (AR) abundance and enhances cellular responses to androgen in these cells. In the current study, we have investigated the mechanism by which 1,25-(OH)2D3 regulates AR gene expression and the involvement of AR in the 1,25-(OH)2D3- and 9-cis retinoic acid (RA)-mediated growth inhibition of LNCaP cells. Northern blot analyses demonstrated that the steady-state messenger RNA (mRNA) level of AR was significantly increased by 1,25-(OH)2D3 in a dose-dependent manner. Time-course experiments revealed that the increase of AR mRNA by 1,25-(OH)2D3 exhibited delayed kinetics. In response to 1,25-(OH)2D3, AR mRNA levels were first detected to rise at 8 h and reached a maximal induction of 10-fold over the untreated control at 48 h; the effect was sustained at 72 h. Furthermore, the induction of AR mRNA by 1,25-(OH)2D3 was completely abolished by incubation of cells with cycloheximide, a protein synthesis inhibitor. 1,25-(OH)2D3 was unable to induce expression of an AR promoter-luciferase reporter. Together, these findings indicate that the stimulatory effect of 1,25-(OH)2D3 on AR gene expression is indirect. Western blot analyses showed an increase of AR protein in 1,25-(OH)2D3-treated cells. This increased expression of AR was followed by 1,25-(OH)2D3-induced inhibition of growth in LNCaP cells. Similar to 1,25-(OH)2D3, 9-cis RA also induced AR mRNA expression, and the effect of both hormones was additive. Moreover, 1,25-(OH)2D3 and 9-cis RA acted synergistically to inhibit LNCaP cell growth. These antiproliferative effects of 1,25-(OH)2D3 and 9-cis RA, alone or in combination, were blocked by the pure AR antagonist, Casodex. In conclusion, our results demonstrate that growth inhibition of LNCaP cells by 1,25-(OH)2D3 and 9-cis RA is mediated by an AR-dependent mechanism and preceded by the induction of AR gene expression. This finding, that differentiating agents such as vitamin D and A derivatives are potent inducers of AR, may have clinical implications in the treatment of prostate cancer.
Liarozole acts synergistically with 1alpha,25-dihydroxyvitamin D3 to inhibit growth of DU 145 human prostate cancer cells by blocking 24-hydroxylase activity.
1Alpha,25-dihydroxyvitamin D3 [1,25-(OH)2D3] inhibits the proliferation of many cancer cells in culture, but not the aggressive human prostate cancer cell line DU 145. We postulated that the 1,25-(OH)2D3-resistant phenotype in DU 145 cells might result from the high levels of expression of 25-hydroxyvitamin D-24-hydroxylase (24-hydroxylase) induced by treatment with 1,25-(OH)2D3. As this P450 enzyme initiates 1,25-(OH)2D3 catabolism, we presumed that a high level of enzyme induction could limit the effectiveness of the 1,25-(OH)2D3 antiproliferative action. To examine this hypothesis we explored combination therapy with liarozole fumarate (R85,246), an imidazole derivative currently in trials for prostate cancer therapy. As imidizole derivatives are known to inhibit P450 enzymes, we postulated that this drug would inhibit 24-hydroxylase activity, increasing the 1,25-(OH)2D3 half-life, thereby enhancing 1,25-(OH)2D3 antiproliferative effects on DU 145 cells. Cell growth was assessed by measurement of viable cells using the MTS assay. When used alone, neither 1,25-(OH)2D3 (1-10 nM) nor liarozole (1-10 microM) inhibited DU 145 cell growth. However, when added together, 1,25-(OH)2D3 (10 nM)/liarozole (1 microM) inhibited growth 65% after 4 days of culture. We used a TLC method to assess 24-hydroxylase activity and demonstrated that liarozole (1-100 microM) inhibited this P450 enzyme in a dose-dependent manner. Moreover, liarozole treatment caused a significant increase in 1,25-(OH)2D3 half-life from 11 to 31 h. In addition, 1,25-(OH)2D3 can cause homologous up-regulation of the vitamin D receptor (VDR), and in the presence of liarozole, this effect was amplified, thus enhancing 1,25-(OH)2D3 activity. Western blot analyses demonstrated that DU 145 cells treated with 1,25-(OH)2D3/liarozole showed greater VDR up-regulation than cells treated with either drug alone. In summary, our data demonstrate that liarozole augments the ability of 1,25-(OH)2D3 to inhibit DU 145 cell growth. The mechanism appears to be due to inhibition of 24-hydroxylase activity, leading to increased 1,25-(OH)2D3 half-life and augmentation of homologous up-regulation of VDR. We raise the possibility that combination therapy using 1,25-(OH)2D3 and liarozole or other inhibitors of 24-hydroxylase, both in nontoxic doses, might serve as an effective treatment for prostate cancer.
Case 33-1997: a 75-year-old man with chest pain, hemoptysis, and a pulmonary lesion.
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Gatekeeping: good or bad, but never indifferent.
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Vitamin D receptor gene polymorphisms: analysis of ligand binding and hormone responsiveness in cultured skin fibroblasts.
Recent reports have suggested that polymorphisms in the gene encoding the vitamin D receptor (VDR) determine a portion of the genetic contribution to bone mineral density (BMD). Individuals homozygous for the allele lacking the Bsm I restriction site in the intron between exons 8 and 9 (BB genotype) have been found to have lower BMD than individuals homozygous for the allele having the Bsm I site (bb genotype). Interestingly, this polymorphism has also been associated with prostate cancer risk. The observed changes in BMD and prostate cancer risk might be due to an alteration in the function or abundance of the VDR leading to differential responsiveness of target cells to the action of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. To test this hypothesis, we cultured dermal fibroblasts from donors with BB, Bb, and bb genotypes and determined the level of VDR expression and the cellular responsiveness to 1,25(OH)2D3 treatment. VDR abundance, affinity for [3H]1,25(OH)2D3, and VDR mRNA levels were not detectably different in BB cells compared to bb cells. Moreover, equal expression of both VDR gene alleles was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) on mRNA from Bb fibroblasts. Fibroblast responsiveness to 1,25(OH)2D3, assessed by induction of 24-hydroxylase mRNA, was similar between BB and bb cell types in dose-response experiments. Although there were individual variations in the parameters we measured, there were no detectable or consistent differences in mean values from our small sample of cultured dermal fibroblasts. In conclusion, we did not detect significant differences in VDR properties or cellular responsiveness to 1,25(OH)2D3 that correlated with VDR genotype. Our findings suggest that these polymorphisms do not affect VDR function, but rather may be a marker for a nearby gene that is responsible for the genotype-associated variation in osteoporosis and prostate cancer risk.
Treatment of early recurrent prostate cancer with 1,25-dihydroxyvitamin D3 (calcitriol)
PURPOSE: Substantial experimental and epidemiological data indicate that 1,25-dihydroxyvitamin D3 (calcitriol) has potent antiproliferative effects on human prostate cancer cells. We performed an open label, nonrandomized pilot trial to determine whether calcitriol therapy is safe and efficacious for early recurrent prostate cancer. Our hypothesis was that calcitriol therapy slows the rate of rise of prostate specific antigen (PSA) compared with the pretreatment rate. MATERIALS AND METHODS: After primary treatment with radiation or surgery recurrence was indicated by rising serum PSA levels documented on at least 3 occasions. Seven subjects completed 6 to 15 months of calcitriol therapy, starting with 0.5 microg. calcitriol daily and slowly increasing to a maximum dose of 2.5 microg. daily depending on individual calciuric and calcemic responses. Each subject served as his own control, comparing the rate of PSA rise before and after calcitriol treatment. RESULTS: As determined by multiple regression analysis, the rate of PSA rise during versus before calcitriol therapy significantly decreased in 6 of 7 patients, while in the remaining man a deceleration in the rate of PSA rise did not reach statistical significance. Overall the decreased rate of PSA rise was statistically significant (p = 0.02 Wilcoxon signed rank test). Dose dependent hypercalciuria limited the maximal calcitriol therapy given (range 1.5 to 2.5 microg. daily). CONCLUSIONS: This pilot study provides preliminary evidence that calcitriol effectively slows the rate of PSA rise in select cases, although dose dependent calciuric side effects limit its clinical usefulness. The development of calcitriol analogues with decreased calcemic side effects is promising, since such analogues may be even more effective for treating prostate cancer.
Pediatric anesthesia and postoperative analgesia.
Children are not "small adults," particularly when it comes to anesthesia and pain management. The psychological and physiologic uniqueness of children must not be forgotten. Cooperation and communication between the anesthesiologist, surgeon, and pediatrician are essential for successful anesthesia and pain management. Pediatric anesthesiologists involved in the perioperative management of infants and children are very much a part of the "continuity of care" concept.
Investigation of acidic fibroblast growth factor delivered through a collagen scaffold for the treatment of full-thickness skin defects in a rabbit model.
In this study the wound healing response of full-thickness skin defects was enhanced through the use of acidic fibroblast growth factor using a collagen scaffold. The objectives of this study were (1) to compare the facilitatory effects of acidic fibroblast growth factor on the cellular response (fibroblast, neutrophil, macrophage, epithelial), tissue response (angiogenesis, collagen) and mechanical properties in a healing wound; and (2) to determine the effect of a collagen scaffold on wound healing when compared with the control. Three 3 x 3 cm full-thickness defects were created on the dorsi of 15 New Zealand White rabbits. Each rabbit had a control (no treatment), collagen scaffold, and collagen scaffold with FGF-1 (100 microg/cm2). All the wounds were covered with a transparent polyurethane dressing. There were three periods of study (1, 2, and 3 weeks) with five rabbits in each period. The volume fraction of the tissue and cells was histomorphometrically determined for each wound. The acidic fibroblast growth factor/collagen system showed promise in enhancing the healing process. Acidic fibroblast growth factor/collagen treatment increased angiogenesis, enhanced epithelialization, and reduced contraction rate over the control. A higher inflammatory response was indicated in the collagen scaffold treated group. Hence acidic fibroblast growth factor delivered through a collagen scaffold shows promise in future clinical applications.
Which primary care physicians treat depression?
The study attempted to determine the proportion of primary care physicians who treat depression and their characteristics. Data were from 677 respondents to a national survey of primary care physicians in Israel. Twenty-two percent always treated depression, 36.6 percent usually did, 28.6 percent sometimes did, and 12.6 percent never did. Logistic regression found that, compared with physicians who sometimes or never treated depression, those who always or usually treated depression treated more medical conditions, regarded themselves as the medical system's first contact for patients with psychosocial problems, had more frequent contact with social workers, and were more likely to have specialized in family medicine.
Lack of correlation between start codon polymorphism of the vitamin D receptor gene and bone mineral density in premenopausal French women: the OFELY study.
Previous studies have demonstrated an association between bone mineral density (BMD) and a start codon polymorphism (SCP) of the vitamin D receptor (VDR) gene in pre- and postmenopausal Caucasian and Japanese women. The SCP can be determined by a restriction fragment length polymorphism defined by the FokI restriction endonuclease. VDR alleles containing the FokI site are denoted by f and alleles lacking the site by F. In this study, the association between BMD and the SCP was examined in a group of 174 premenopausal French women who previously had been studied for a relationship between BMD and the VDR BsmI polymorphism. The SCP genotypes of the French women were FF 40%, Ff 44%, and ff 16% and they were independent of the BsmI genotype. BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine, proximal femur, forearm, and total body. In contrast to previous reports, there was no association of BMD with SCP genotype in this group of Caucasian women at any site. We also measured several biochemical indices of calcium homeostasis and bone turnover. We found no statistically significant associations between SCP genotype and calcium, parathyroid hormone, or vitamin D levels. There was a 33.5% higher level of the skeletal resorption marker N-telopeptides of type I collagen in the women with the ff genotype when compared with women with the FF genotype (p = 0.004). Other bone turnover markers failed to show an association with SCP genotype. In summary, the SCP genotype may not be associated with reduced BMD in all geographical or ethnic populations.
The vitamin D receptor gene start codon polymorphism: a functional analysis of FokI variants.
The vitamin D receptor (VDR) gene contains a start codon polymorphism (SCP) which is three codons upstream of a second start site (ATG). The SCP genotype can be determined with the restriction enzyme FokI, where "f" indicates the presence of the restriction site and the first ATG, while "F" indicates its absence. Recent evidence suggests that the ff genotype is correlated with lower bone mineral density (BMD) in some populations. The SCP results in alternate VDRs that differ structurally, with the F variant (F-VDR) being three amino acids shorter than the f variant (f-VDR). To determine whether there are functional differences between the f-VDR and the F-VDR, we studied the two VDR forms expressed in COS-7 cells. The proteins were distinguishable from one another on Western blots by their different mobilities, confirming the larger size of f-VDR. Ligand binding studies showed no significant differences between the affinities of the two VDR forms for [3H]-1,25-dihydroxyvitamin D3 ([3H]-1,25(OH)2D3) (Kd = 131+/-78 pM, f-VDR; Kd = 237+/-190 pM, F-VDR; p = 0.24); however, a 2-fold difference in affinity can not be discriminated by this method. There were no differences in the abilities of the two receptor forms to bind DNA as determined by electrophoretic mobility shift assays. The ability of the two VDR forms to transactivate target genes was investigated using three different vitamin D responsive luciferase reporter constructs: 24-hydroxylase, osteocalcin, and osteopontin. In these transactivation experiments, 1,25(OH)2D3 dose-response (0.1-10 nM) curves revealed that the ED50 values for transactivation were indistinguishable between the two VDR forms. Additionally, cultured human fibroblasts with FF, Ff, and ff genotypes had similar sensitivity to 1,25(OH)2D3 with respect to the induction of 24-hydroxylase mRNA. In summary, we were unable to detect significant differences in ligand affinity, DNA binding, or transactivation activity between f-VDR and F-VDR forms. We must emphasize, however, that the sensitivity of the methods used limits our ability to detect minor differences in VDR affinity and function. In conclusion, we cannot define a mechanism whereby the SCP in the VDR might contribute to population differences in BMD.
Hereditary 1,25-dihydroxyvitamin D-resistant rickets due to an opal mutation causing premature termination of the vitamin D receptor.
Mutations in the vitamin D receptor (VDR) gene have been shown to cause hereditary vitamin D-resistant rickets (HVDRR). The patient in this study is a young French-Canadian boy with no known consanguinity in his family. The child exhibited the clinical characteristics of HVDRR with early onset rickets, hypocalcemia, secondary hyperparathyroidism, and elevated 1,25-dihydroxyvitamin D (1,25(OH)2D) levels as well as total alopecia. Fibroblasts were cultured from a skin biopsy of the patient and used to assess the VDR. Northern blot analysis showed that a normal size VDR transcript was expressed; however, [3H]1,25(OH)2D3-binding levels were very low and Western blot analysis failed to detect any VDR protein. Total resistance to 1,25(OH)2D3 was demonstrated by the failure of the cultured fibroblasts to induce the transcription of the 25-hydroxyvitamin D-24-hydroxylase gene when treated with high concentrations of 1,25(OH)2D3. Analysis of the DNA sequence revealed a unique C to T base change corresponding to nucleotide 218 of the VDR cDNA. This single base substitution changes the codon for arginine (CGA) to an opal stop codon (TGA), resulting in the truncation of the VDR at amino acid 30. The Arg30stop mutation prematurely terminates translation and deletes 398 amino acids including most of the zinc fingers as well as the entire ligand-binding domain. Restriction fragment length polymorphism analysis of a DdeI restriction site created by the mutation showed that the parents were heterozygous for the mutant allele. In conclusion, the Arg30stop mutation truncates the VDR and leads to a hormone-resistant condition which is the molecular basis of HVDRR in this patient.
Resolution of human parvovirus B19-induced nonimmune hydrops after intrauterine transfusion.
Our objective is to report our experience with cases of prolonged recovery from nonimmune hydrops secondary to human parvovirus B19 infection occurring after intrauterine transfusion. We reviewed cases referred to our unit over a 10 year period for exposure to parvovirus B19 infection. Those cases with serologic evidence of recent infection were identified. The cases requiring intrauterine transfusion were reviewed for demographic details, time of exposure, parvovirus B19 serology, gestational age at detection of nonimmune hydrops, number and results of fetal blood samples, duration from intrauterine transfusion to resolution of hydrops, and neonatal outcome. Of 38 cases identified through serologic evidence of recent parvovirus B19 infection, 35 (92.1%) did not develop hydrops, and these were followed by serial ultrasonography for 8 weeks from the time of exposure. Three cases (7.9%) developed hydrops and required intrauterine transfusion; in two the transfusion was intravascular and in one it was intraperitoneal. The mean duration from intrauterine transfusion to resolution of hydrops was 8 weeks 2 days. Pregnancy outcome in all cases was normal. In cases of nonimmune hydrops secondary to parvovirus B19 infection, resolution of the hydrops after intrauterine transfusion may take up to 12 weeks with a normal pregnancy outcome.
[Characteristics of Israeli primary health care physicians who treat depression].
Primary health care physicians have a pivotal role in treating mental health problems. We determined the proportion of primary care physicians in Israel who treat depression and their characteristics. The study was based on a stratified national random sample of primary care physicians (n677, response rate 78%). From these physicians' reports 22% always treat depression, 36.6% usually, 28.6% sometimes, and 12.6% never. Based on a logistic regression model the physicians who always or usually treated depression were distinguished from the other physicians by their treating more medical conditions on their own, seeing themselves as having more first contact for psychosocial problems, having frequent contact with social workers and specializing in family medicine. Primary health care physicians play a major role in treating depression on their own. This raises new questions about how they treat depression themselves, and under what circumstances they treat or refer to a specialist.
Androgen and vitamin D receptor gene polymorphisms: the long and short of prostate cancer risk.
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