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Biomedical subjects

R S Weinstein

Publications and source records attributed to R S Weinstein.

At least 19 recordsLinked to original sources
PubMed1996

Linkage of decreased bone mass with impaired osteoblastogenesis in a murine model of accelerated senescence.

Bone marrow is the principal site for osteoclastogenesis and osteoblastogenesis; and an increase in the former has been linked with bone loss caused by acute loss of gonadal steroids. We have now used an established murine model of accelerated senescence and osteopenia (SAMP6) to test the hypothesis that reduced osteoblastogenesis is linked with decreased bone mass. At 1 mo of age, the number of osteoblast progenitors in SAMP6 marrow was indistinguishable from controls; however a threefold decrease was found at 3-4 mo of age. Impaired osteoblast formation was temporally associated with decreased bone formation and decreased bone mineral density, as determined by histomorphometric analysis of tetracycline-labeled cancellous bone and dual-energy x-ray absorptiometry, respectively. Osteoclastogenesis determined in ex vivo bone marrow cultures was also decreased in these mice, as was the number of osteoclasts in histologic sections. Moreover, unlike controls, senescence-accelerated mice failed to increase osteoclast development after gonadectomy. The osteoclastogenesis defeat was secondary to impaired osteoblast formation as evidenced by the fact that osteoclastogenesis could be restored by addition of osteoblastic cells from normal mice. These findings provide the first demonstration of a link between low bone mineral density and decreased osteoblastogenesis in the bone marrow and validate the senescence-accelerated mouse as a model of involutional osteopenia.

Aging↗
PubMed1996

Development of an orthotopic SCID mouse-human tumor xenograft model displaying the multidrug-resistant phenotype.

Multiple myeloma is a plasma cell malignancy which is generally incurable in spite of a high initial response to chemotherapy. While animal models of myeloma are known, the recent developments of human xenografts in nude and SCID mice suggests a promising experimental model. The SCID model, in particular, holds promise because these animals readily accept hematopoietic and lymphoid transplantation and do not generally develop graft versus host reaction. We have developed two drug-resistant variants of the human multiple myeloma cell line ARH-77 by in vitro exposure to gradually increasing concentrations of doxorubicin (ARH-D60) or mitoxantrone (ARM-80). When injected into irradiated SCID mice, the ARH-D60 cell line grew in an orthotopic pattern with the development of osteolytic lesions. This is in contrast to the 8226/C1N human myeloma cell line which grows in a disseminated but nonorthotopic manner in the SCID mouse. Both the ARH-D60 and ARM-80 cell lines are resistant to doxorubicin and cross-resistant to mitoxantrone, vinca alkaloids, taxol and m-AMSA while maintaining sensitivity to antimetabolites and alkylating agents. Growth characteristics and cell cycle kinetics, including S-phase, were not altered in the resistant sublines. The ARH-D60 and ARM-80 cell lines both displayed a classic multidrug-resistance (MDR) phenotype which was partially reversed by the addition of verapamil. These two cell lines represent the first MDR human myeloma cell lines which have demonstrated an orthotopic growth pattern in the SCID mouse and thus may be of value in studying the pathophysiology of this disease.

Animals↗
PubMed1996

Comparison of 22-oxacalcitriol and 1,25(OH)2D3 on bone metabolism in young X-linked hypophosphatemic male mice.

Using a mouse model (Hyp) of human hypophosphatemic vitamin D-resistant rickets [X-linked hypophosphatemia (XLH)], we compared the effects of 22-oxa-1,25-dihydroxyvitamin D3 (OCT) and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on restoring defects in mineral and skeletal metabolism. Hyp/Y mice received OCT or 1,25(OH)2D3 at doses of 0.05-0.25 micron.kg-1.day-1 for 4 wk. OCT normalized serum calcium levels, whereas 1,25(OH)2D3 produced hypercalcemia in Hyp/Y. OCT and 1,25(OH)2D3 also normalized serum phosphate levels and increased urinary calcium levels. Additionally, OCT and 1,25(OH)2D3 reduced elevated urinary pyridinoline levels and suppressed urinary adenosine 3',5'-cyclic monophosphate levels to normal. Bone ash content was low in Hyp/Y, and OCT was more effective than 1,25(OH)2D3 in reversing this defect. Histomorphometric analysis of bone turnover, mineralization rate, and osteoid content demonstrated comparable responses with OCT and 1,25(OH)2D3, although the highest dose of 1,25(OH)2D3 resulted in increased osteoid content and delayed mineralization. OCT appears to be more effective and definitely less toxic than 1,25(OH)2D3 in reversing skeletal lesions in Hyp/Y mice and may prove to be the drug of choice in the treatment of childhood XLH.

Animals↗
PubMed1996

Comparative study of alendronate versus etidronate for the treatment of Paget's disease of bone.

Alendronate, an aminobisphosphonate, is much more potent than etidronate, an older bisphosphonate, in inhibiting osteoclast-mediated bone resorption, and unlike etidronate, therapeutic doses of alendronate are not associated with abnormal mineralization. In the present study, we compared the effectiveness, safety, and tolerability of 6 months of daily oral administration of alendronate (40 mg) with those of etidronate (400 mg) in 89 patients with clinically active Paget's disease. The primary efficacy end point was the percent change in serum alkaline phosphatase. Other end points included changes in urinary deoxypyridinoline excretion, pain, functional impairment scores, and radiological osteolysis. Tetracycline-labeled bone biopsies were obtained for histomorphometric analysis from a subset of 43 patients at the 6-month visit. The alendronate-treated group had significantly greater decreases in both serum alkaline phosphatase (79% vs. 44%) and urinary deoxypyridinoline (75% vs. 51%) than the etidronate-treated group (P < 0.001 in both cases). Normalization of serum alkaline phosphatase was much more frequent in alendronate-treated patients (63.4% vs. 17.0%; P < 0.001). Alendronate was well tolerated and had a safety profile similar to that of etidronate. Histomorphometry revealed decreased bone turnover and no qualitative abnormalities, including no direct negative effects on bone mineralization, with alendronate treatment. One patient receiving etidronate developed frank osteomalacia. Alendronate appears to be a highly effective treatment for Paget's disease of bone that offers an important therapeutic advance over etidronate.

Administration, Oral↗
PubMed1995

Panic disorder.

Panic disorder is a chronic illness that affects at least 3 percent of the population. Panic disorder is associated with significant morbidity and an increased risk of suicide. Patients generally present with multiple somatic and psychologic complaints, including heart palpitations, chest pain, tremor, shortness of breath, choking, nausea or abdominal distress, dizziness, derealization, fear of losing control or going crazy, fear of dying, paresthesias, chills or hot flushes, headache, diarrhea, insomnia, chronic fatigue, anxiety and depression. To make the correct diagnosis, these symptoms must be evaluated carefully since they also occur with serious cardiovascular, pulmonary, endocrinologic and neurologic disorders. Many effective treatments are available, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, benzodiazepines such as alprazolam and clonazepam, and psychotherapy.

Antidepressive Agents↗
PubMed1995

Pathology consultation services via the Arizona-International Telemedicine Network.

The Arizona-International Telemedicine Network (AITN) links 4 cities in Arizona and two international sites in China and Mexico, into a telepathology diagnostic network. Established in 1993, the Network provides second opinions on surgical pathology and cytopathology cases. Workstations are 486 PC-based computers. Static images (1024 x 774 x 8 pixels) are grabbed with a variable resolution video camera and sent by 14,400 bit per second modems over ordinary telephone lines. Second opinions are either rendered directly by a general telepathologist or triaged to a specialist. Experience with the first 37 cases indicates a high level of success in providing useful information to referring pathologists over the Network.

Computer Communication Networks↗
PubMed1994

Fractal geometry and vertebral compression fractures.

Cancellous bone in postmenopausal osteoporosis is characterized by widely spaced and disconnected trabeculae. These architectural changes may disproportionately increase bone fragility compared with the decrease in bone mass alone. To determine whether there is an independent architectural contribution to fracture risk, we applied fractal geometry to the cancellous bone in osteoporosis. Fractal objects have recurrent, branching patterns that are quantified by a fractal dimension D, that describes how the object fills space. Photomicrographs of transiliac bone biopsy specimens were digitized, and D was calculated from the negative of the straight portion of the slope of the log of the number of pixels containing boundary points versus the log of the pixel size over a range of pixel sizes. The results were compared with the cancellous bone histomorphometry in 31 individuals, aged 19-80 years, who were healthy before sudden death. D was inversely related to age (r = -0.72, p < 0.0001) and trabecular spacing (r = -0.87; p < 0.0001) and directly related to bone area (r = 0.86, p < 0.0001) and trabecular number (r = 0.83, p < 0.0001). We then examined 12 healthy volunteers and 12 patients with vertebral compression fractures as a result of osteoporosis who were matched for age and cancellous bone area. The patients with fractures had a 7.9% lower mean value for D (1.224 +/- 0.085 SD versus 1.329 +/- 0.125, p < 0.026). Other markers of the cancellous architecture, such as trabecular width, separation, and number, were not different between the matched groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

P-glycoprotein expression in human plasma cell myeloma: correlation with prior chemotherapy.

Multidrug-resistant (MDR) myeloma patients failing chemotherapy may express P-glycoprotein (PGP), which serves as an efflux pump protecting the neoplastic cells. Unknown is whether PGP expression might relate to prior cytotoxic drug exposure. To address this question, we studied 106 consecutive bone marrow samples from 104 myeloma patients with samples studied either before or after therapy and at the time of relapse. We performed an established immunocytochemical assay of PGP using an MDR-1-specific monoclonal antibody and correlated PGP status with prior chemotherapy dosage. Myeloma patients with no prior therapy had a low incidence of PGP expression (6%, 3/47), whereas those receiving chemotherapy had a significantly higher incidence (43%, 21/49) (P < .0001). A substantially higher incidence of PGP expression (50%, 83%, respectively) occurred when the total vincristine dose exceeded 20 mg and when doxorubicin exceeded 340 mg. In the 11 patients who received both high vincristine and doxorubicin dosages (> 20 mg, > 340 mg total dose) there was 100% incidence of PGP expression in the tumor cells. These data provided the basis for a predictive mathematical model from which dose-related PGP expression normograms were generated. Time with myeloma for PGP-negative patients (mean 33 months) had overlapping confidence limits with PGP-positive patients (mean 42 months), suggesting that disease duration was not a significant variable. PGP expression did not correlate with other clinical factors or immunophenotypic factors. Our findings indicate a strong correlation between PGP expression in myeloma and past chemotherapy in myeloma, in particular, related to prior exposure to the natural product agents vincristine and doxorubicin. Additionally, the proportion of PGP-positive plasma cells was significantly higher in the doxorubicin-treated patients than the nondoxorubicin-treated patients (87.7% v 65.17%; P = .013). Combined high vincristine and doxorubicin total dosage appear highly predictive of PGP expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Case report: hypercalcemia in acute myeloblastic leukemia is caused by osteoclast activation.

Hypercalcemia in adult T-cell leukemia has been attributed to increased levels of 1,25-dihydroxyvitamin D (1,25(OH)2D), whereas in other types of leukemia, hypercalcemia has been blamed on direct skeletal invasion by malignant cells, ectopic parathyroid hormone (PTH) production or bone-resorbing cytokines. A 51-year-old man was studied who presented with back pain, circulating myeloblasts, and hypercalcemia. The bone marrow revealed acute myeloblastic leukemia. While the ionized calcium concentration was 8.17 mg/dL (normal, 4.73 to 5.21 mg/dL), the levels of PTH, PTH-related peptide, vitamin D, and thyroxine were normal or subnormal. Bone histomorphometry showed a decreased cortical width with intracortical erosion cavities dissecting into the marrow space. In cancellous bone, the osteoid area, osteoblast perimeter, and tetracycline fluorescence were sparse, whereas the osteoclast perimeter was increased. Persistent marrow fat, the general absence of trabecular narrowing, and the prompt response to calcitonin suggest that the osteoclasts caused the hypercalcemia and lytic lesions, rather than pressure atrophy or osteolysis by leukemic infiltration. Osteoclast activation and subsequent hypercalcemia may have been due to a locally produced cytokine, such as interleukin-1 beta or tumor necrosis factor.

Biopsy↗
PubMed1993

An in vivo model of human multidrug-resistant multiple myeloma in SCID mice.

We have established a reproducible in vivo model of human multiple myeloma in the severe combined immunodeficient (SCID) mouse using both the RPMI 8226 human myeloma cell line and the P-glycoprotein-expressing multidrug-resistant 8226/C1N subline. SCID mice 5 to 8 weeks of age were injected intraperitoneally with either 8226 drug-sensitive or P-glycoprotein-expressing multidrug-resistant myeloma cells (8226/C1N). Tumors were detected within 5 days after injection by the presence of human lambda light chain excretion in the mouse urine. Growth of the tumor was observed primarily in the abdominal cavity with spread to the abdominal organs. The anti-neoplastic agent doxorubicin was effective in treating the drug-sensitive 8226 human-SCID xenografts but had no effect on the multi-drug-resistant 8226/C1N human-SCID xenografts. In the 8226-sensitive xenografts, treatment with doxorubicin resulted in a sharp decline in the concentration of human lambda light chain being excreted in the mouse urine. This correlated with an increased survival of the drug-treated animals. This mouse model offers an in vivo means of evaluating efficacy and toxicity of new therapeutic approaches, including development of chemosensitizers directed against P-glycoprotein in multidrug-resistant myelomas.

Animals↗
PubMed1992

Variable expression of P-glycoprotein in normal, inflamed, and dysplastic areas in ulcerative colitis.

Screening programs for the detection of cancer in ulcerative colitis are inexact and not always successful in finding early, curable cancers. P-glycoprotein is a membrane-based, energy-dependent protein found in varying degrees within normal human tissue. P-glycoprotein is overexpressed in malignant tumors, particularly colorectal cancer, and is known to convey resistance to certain anticancer drugs by acting as a membrane "pump." The purpose of this study was to determine the expression of this protein in inflamed and premalignant colonic epithelium, compare its expression with normal controls, and assess its potential use as a screening tool for high-risk patients with ulcerative colitis. Using immunohistochemical techniques, the colons of 21 patients (10 with dysplasia) with ulcerative colitis were stained with monoclonal antibody C-219 (MAbC219) specific for P-glycoprotein. P-glycoprotein was expressed in 38 percent of normal areas, 71 percent of inflamed areas (P = 0.0156), and 70 percent of dysplastic areas. Comparing the level of expression when progressing from normal to inflamed areas within a given patient, 11 patients (52 percent) showed increased expression, 8 (38 percent) showed equal expression, and only 2 (10 percent) showed decreased expression (P = 0.0225). Comparing expression when progressing from inflamed to dysplastic areas (10 patients), 7 showed equal expression and 3 showed increased expression (P = 0.25). Increasing duration of disease was associated with a significant increase in P-glycoprotein expression, but only in histologically normal areas. Duration of disease had no effect on P-glycoprotein expression in inflamed or dysplastic areas. Similarly, when surgery was performed for elective reasons, there was a significant overexpression of P-glycoprotein, but only in histologically normal areas. Our findings suggest that the increase in P-glycoprotein expression from normal to inflamed and dysplastic areas reflects the premalignant nature of ulcerative colitis and occurs early in the course of the disease. Further research needs to be done to determine its role in cancer surveillance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Intraluminal low-dose rate brachytherapy for malignant endobronchial obstruction.

From October 1985 through October 1989, 87 patients underwent 105 intraluminal brachytherapy treatments for endobronchial or endotracheal malignant tumors. Low-dose rate iridium-192 seeds were used. Of the 60 patients treated for primary lung carcinoma, 52 patients (87%) had previously received full-course external beam radiotherapy to the tumor sites. Ten patients were treated for symptomatic metastatic disease, and one patient had extension of tumor into the trachea from carcinoma of the cervical esophagus. Clinical or bronchoscopic improvement was noted in 42 patients (59%). No significant difference in the response rate was observed between various types of tumor. Patients who were treated with a radiation dose larger than 2500 cGy at a 2 cm radius had a significantly greater response rate (77%) than patients treated with a dose less than 2500 cGy (38%) (p = 0.001). A trend toward better results was apparent in patients who had undergone Nd:YAG laser bronchoscopy in the 2 weeks before brachytherapy. The treatments were well tolerated, and the incidence of serious complications was low and acceptable.

Brachytherapy↗
PubMed1992

Hypercalcemia due to hard water used for home hemodialysis.

We have described two patients from the same rural community in Georgia who had hypercalcemia during home hemodialysis. In the first patient the diagnosis was not considered until after the patient complained of the poor taste of her home tap water and of the white residue it left on her cooking utensils; other causes of hypercalcemia had been ruled out. The diagnosis was confirmed when samples of tap water that had passed through the in-line deionizer showed low to high calcium concentrations. Calcium concentrations were high after the deionizer filters had been in place for some time but within the acceptable guidelines for the type of filters used. The second patient, seen shortly after the first, had also received dialysis with hard water and also had hypercalcemia despite the use of an in-line deionizer. These cases suggest that dialysis-induced hypercalcemia can occur during home hemodialysis despite seemingly adequate pretreatment of the water source.

Aged↗