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Biomedical subjects

J Rubin

Publications and source records attributed to J Rubin.

At least 91 records · Page 5Linked to original sources
PubMed1996

Formation of osteoclast-like cells is suppressed by low frequency, low intensity electric fields.

With use of a solenoid to generate uniform time-varying electric fields, the effect of extremely low frequency electric fields on osteoclast-like cell formation stimulated by 1,25(OH)2D3 was studied in primary murine marrow culture. Recruitment of osteoclast-like cells was assessed by counting multinuclear, tartrate-resistant acid phosphatase positive cells on day 8 of culture. A solenoid was used to impose uniform time-varying electric fields on cells; sham exposures were performed with an identical solenoid with a null net electric field. During the experiments, both solenoids heated interiorly to approximately 1.5 degrees C above ambient incubator temperature. As a result of the heating, cultures in the sham solenoid formed more osteoclast-like cells than those on the incubator shelf (132 +/- 12%). For this reason, cells exposed to the sham solenoid were used for comparison with cultures exposed to the active coil. Marrow cells were plated at 1.4 x 10(6)/cm2 in square chamber dishes and exposed to 60 Hz electric fields at 9.6 muV/cm from days 1 to 8. Field exposure inhibited osteoclast-like cell recruitment by 17 +/- 3% as compared with sham exposure (p < 0.0001). Several variables, including initial cell plating density, addition of prostaglandin E2 to enhance osteoclast-like cell recruitment, and field parameters, were also assessed. In this secondary series, extremely low frequency fields inhibited osteoclast-like cell formation by 24 +/- 4% (p < 0.0001), with their inhibitory effect consistent throughout all variations in protocol. These experiments demonstrate that extremely low intensity, low frequency sinusoidal electric fields suppress the formation of osteoclast-like cells in marrow culture. The in vitro results support in vivo findings that demonstrate that electric fields inhibit the onset of osteopenia and the progression of osteonecrosis; this suggests that extremely low frequency fields may inhibit osteoclast recruitment in vivo.

Animals↗
PubMed1996

Regulation of murine osteoblast macrophage colony-stimulating factor production by 1,25(OH)2D3.

Macrophage colony stimulating factor (MCSF) is important for formation of osteoclasts. We investigated the ability of 1,25(OH)2D3 to regulate osteoblast production of MCSF. Mouse calvarial osteoblasts were cultured for 2 days +/- 1,25(OH)2D3. Since 1, 25(OH)2D3 decreased osteoblast proliferation by 17.6 +/- 1% at 10 nM and 11 +/- 4% at 1 nM, the effect of growth rate on MCSF secretion was examined. Limiting cell proliferation by serum did not affect MCSF production. 1,25(OH)2D3 (1 nM) increased MCSF production (U/10(5) cells) maximally by 68 +/- 33% (n = 3) with an ED50 for 1, 25(OH)2D3 of 5 x 10(-11) M. To investigate effects of 1,25(OH)2D3 on MCSF gene regulation, RT-PCR primers were designed to identify the mRNA coding for the membrane-bound isoform of MCSF. Simultaneous RT-PCR of glyceraldehyde-phosphate dehydrogenase (GAP) allowed semiquantitative assessment of MCSF mRNA between treatment groups expressed as the MCSF/GAP RT-PCR product ratio; both MCSF and GAP (+) primers were labeled with 32P-ATP for phosphorimage quantitation. The membrane-bound MCSF/GAP PCR product ratio was not affected by proliferative rate when growth was limited by [serum]. The MCSF/GAP RT-PCR product ratio was dose dependently increased by 1,25(OH)2D3, maximally at 1 nM at 2.2 +/- 0.2 = fold (n = 10). 1,25 (OH)2D3 also increased the expression of an RT-PCR MCSF/GAP product ratio which represented the secreted isoform of MCSF. The ability of 1,25(OH)2D3 to pretranslationally regulate expression of membrane-bound osteoblast MCSF may be important in osteoblast:osteoclast interactions.

Animals↗
PubMed1996

Uniject as a delivery system for the once-a-month injectable contraceptive Cyclofem in Brazil.

This study assessed the administration of Cyclofem using prefilled Uniject devices. A total of 480 injections were administered divided equally between standard syringes and Uniject. The majority of women (82%) reported that they felt anxious prior to receiving the injection with Uniject. After injection, more than 80% expressed no anxiety about the appearance of Uniject or about the technique of injection. A total of 96.3% of the participants reported slight to no pain with Uniject. In comparison to the standard syringe, 5.6% expressed having had more pain with Uniject. Ninety percent of the service providers reported that Uniject was easy to activate and inject and that it was reassuring for users to know that the syringe and needle had never been used previously. Only two service providers demonstrated difficulties in activating the device. No accidental punctures occurred during the manipulation, and incomplete emptying of the Uniject was not observed. In conclusion, Uniject is a good device for the administration of the injectable contraceptive Cyclofem. It is likely to be appropriate for the delivery of other injectable contraceptives after the necessary stability tests have been performed.

Anxiety↗
PubMed1996

Evaluation of monoclonal antibody-mediated anti-acute myeloid leukemia immunotherapy in a SCID/hu model.

The therapeutic potential of the IgM complement-fixing murine monoclonal antibody (mAb) PM-81 (anti-CD15) against acute myeloid leukemia (AML) was assessed in a SCID/hu leukemia model. Intraperitoneal (i.p.) injection of NB4 leukemia cells resulted in aggressive growth of leukemia cells in the peritoneal cavity of irradiated SCID/CB-17 mice. Flow cytometric analysis of human CD15, 33 and 45 expression, as well as cytologic examination, revealed that leukemia cells disseminated into the peripheral blood and multiple tissues of the mice. The approximately linear relationship between the injected leukemia cells and the subsequent leukemia cell proliferation provided a reliable model for monitoring the therapeutic effects of immunotherapy. Intraperitoneal injection of the mAb PM-81 markedly suppressed leukemia cell growth in this SCID/leukemia model. Most of the untreated mice died within 35-50 days of leukemia cell inoculation. Four weeks after inoculation of NB4 cells, five of nine mAb PM-81 treated mice had no solid tumor growth and six of nine had no detectable peritoneal exudate leukemia cells as determined by flow cytometry. In contrast, 100% of the mice in the untreated or control mAb groups were found to have both solid and peritoneal leukemia growth. In further experiments designed to evaluate the effects of therapy on survival, 50% (4/8) of PM-81 treated mice survived to 150 days, and had no detectable solid or suspension leukemia cells detectable at necropsy. In contrast, the median survival of untreated or negative control antibody-treated mice was 40 days (comparison to PM-81 treated; p = 0.006 and p = 0.03, respectively). The mechanism of leukemia cell suppression is not likely due to complement fixation since we could not demonstrate in vitro any cytotoxicity mediated by SCID mouse plasma. Further study is required to understand the mechanism of the antileukemia effect of PM-81 in this model.

Animals↗
PubMed1996

Diagnosis of closed central slip injuries. A cadaveric analysis of non-invasive tests.

Four non-invasive tests for central slip integrity were analysed using 20 fresh frozen cadaver fingers. A pre-boutonnière deformity was simulated by dividing the central slip. A passively correctable boutonnière was simulated by dividing the central slip, triangular ligament and oblique fibres of the extensor expansion. The test described by Boyes, which evaluates distal interphalangeal joint flexion, was found not to be reliable for the diagnosis of either injury. The test described by Elson, which evaluates distal interphalangeal joint rigidity while actively extending the flexed proximal interphalangeal joint, was the only manoeuvre which was able to discern central slip integrity in both simulated injuries. The central slip tenodesis test and testing resistance of active proximal interphalangeal joint extension should be performed with the proximal interphalangeal joint in flexion to weaken the effectiveness of the lateral bands.

Biomechanical Phenomena↗
PubMed1996

Relation between fat malabsorption and transit abnormalities in human carcinoid diarrhea.

BACKGROUND & AIMS: Fat and complex carbohydrates in the distal bowel activate "brakes" inhibiting upper gut motility. The hypothesis of this study was that rapid transit carcinoid diarrhea in association with steatorrhea results in impairment of gastric emptying. METHODS: Fifteen patients with carcinoid diarrhea without prior gastrointestinal resection or whose small bowel resection was limited to < 100 cm of ileum were studied. Gastrointestinal transit was measured scintigraphically with a standardized meal. Percentage of ingested fat excretion was calculated. RESULTS: Mean length of small bowel resected was 33 cm, and mean 24-hour urine 5-hydroxyindoleacetic acid was 120 mg. Fourteen patients had increased daily stool weights, and 10 had increased stool fat excretion (mean, 13%). Transit was accelerated in the small bowel in 14 and in the colon in all patients. The lag time for gastric emptying was prolonged in 2 patients who had no previous resection. Gastric emptying rate was accelerated in 5, normal in 7, and delayed in 3 patients. CONCLUSIONS: Ileal and colonic brakes do not seem to delay gastric emptying in patients with carcinoid diarrhea associated with rapid transit and mild to moderate steatorrhea.

Aged↗
PubMed1996

1,25(OH)2D3 and cAMP synergistically induce complement 5a receptor messenger RNA.

Complement 5a receptor (C5aR) mediates both acute and chronic participation of monocytes in the immune response. In the human U937 monoblast, C5aR is maximally expressed 4 days after treatment with 1,25(OH)2D3 (or cycloheximide) and prostaglandin E2 combined. The authors asked whether these agents altered expression of C5aR messenger RNA (mRNA). Unstimulated U937 cells expressed neither C5aR mRNA nor C5a binding. Complement 5aR mRNA rose 3 hours after prostaglandin E2 application and fell to basal levels by 12 hours. This early rise in C5aR mRNA did not cause an acute rise in C5a binding, which gradually increased between 1 and 4 days. Neither 1,25(OH)2D3 nor cycloheximide induced expression of C5aR mRNA in the absence of prostaglandin E2 but did enhance prostaglandin E2-stimulated C5aR mRNA expression and C5a binding. The authors observed a late increase in C5aR mRNA at day 3 in treated cells. Inhibition of this late rise in mRNA with 5,6-dichlorobenzimidazole riboside attenuated C5a binding by 65%, indicating its importance in the generation of C5a binding sites. The expression of functional C5aR is, therefore, a complex process involving regulation at transcriptional and posttranscriptional levels.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Enhanced expression of vascular endothelial growth factor in human SaOS-2 osteoblast-like cells and murine osteoblasts induced by insulin-like growth factor I.

Formation of new capillaries, a critical component of tissue growth and repair, is a recognized process in the development, formation, and remodeling of bone. Vascular endothelial growth factor (VEGF), a potent angiogenic factor with specific mitogenic actions on endothelial cells, is produced in a regulated manner by many cell types, including osteoblasts. The aim of the present investigation was to test the hypothesis that insulin-like growth factor I (IGF-I), a known osteogenic factor, modulates VEGF expression in osteoblasts. In human SaOS-2 osteoblast-like cells, 10 nM IGF-I increased the abundance of VEGF messenger RNA (mRNA) by 4-fold above the control value at 2h, and the elevated levels of mRNA returned to near basal by 8 h. IGF-I stimulated VEGF mRNA levels at IGF-I concentrations as low as 1-2 nM. The stability of VEGF mRNA was not increased after IGF-I treatment, and actinomycin D abrogated the enhanced expression of VEGF mRNA by IGF-I, indicating that the action of IGF-I was probably mediated by a transcriptional mechanism. The induction of VEGF mRNA by IGF-I in SaOS-2 cells was associated with an increase in immunoreactive VEGF protein, as detected by immunoblot analysis. IGF-I also increased the expression of VEGF mRNA in primary murine osteoblasts, which confirmed that the actions of IGF-I were not unique to SaOS-2 cells. We conclude that IGF-I enhances osteoblast synthesis of VEGF, which may then act locally on endothelium to stimulate angiogenesis, an essential component of bone growth and remodeling.

Animals↗
PubMed1996

Fecal marker variability in colorectal cancer: calprotectin versus hemoglobin.

BACKGROUND: Blood products like hemoglobin are problematic as markers for colorectal neoplasia because bleeding is intermittent. Levels of calprotectin, a leukocyte-derived protein, are increased in stools from colorectal cancer patients. However, this blood constituent may gain luminal access via interstitial leukocyte migration, which could be a less variable mechanism of entry than bleeding. METHODS: To correlate the levels of and to compare the variability of fecal calprotectin and hemoglobin, quantitative assays were performed independently on multiple serially collected stools from 14 patients with colorectal cancer. Marker level association was estimated with Pearson's correlation coefficient, and variation estimated with an analysis of variance model. RESULTS: Fecal calprotectin and hemoglobin levels were discordant in 55 (50%) of 110 matched aliquots, and marker levels failed to correlate. The estimated between-subject correlation was -0.10 (95% CI, -0.60 to 0.46), and mean within-subject correlation -0.27 (95% CI, -0.73 to 0.34). The between-stool coefficient of variation was less for calprotectin (22%) than for hemoglobin (80%). CONCLUSIONS: In patients with colorectal cancer, the mechanism of luminal calprotectin entry appears to be both different from and less erratic than bleeding.

Aged↗
PubMed1995

Characterization of MCSF-induced proliferation and subsequent osteoclast formation in murine marrow culture.

To clarify events involved in 1,25(OH)2D3-stimulated osteoclast-like cell (OCLC) formation in primary murine marrow culture, we have characterized kinetics of precursor proliferation and fusion and their dependence on macrophage colony-stimulating factor (MCSF). 3H-thymidine nuclear incorporation in tartrate-resistant acid phosphatase positive multinucleated cells (TRAP+ MNCs) was assessed: 3H-thymidine incorporation was greatest when tracer was added during day 4 or 5, with labeled nuclei in 81% (day 4) and 90% (day 5) of the TRAP+ MNCs counted at the end of day 7. The percentage of total nuclei labeled was highest when 3H-thymidine was dosed on day 4 (58%), decreasing to 2% by day 7. Final TRAP+ MNC numbers were depleted by 80% when treated for 24 h with hydroxyurea on either day 3 or 4; this inhibition dropped to 57% and 12% when hydroxyurea was pulsed during days 5 or 6, respectively. The absence of 1,25(OH)2D3 during days 1-4 caused 70% attenuation of TRAP+ MNC formation; however, exposure to 3H-thymidine during day 4 in this experiment resulted in subsequent labeling of 81% of the TRAP+ MNCs formed, indicating that precursor proliferation occurred in the absence of 1,25(OH)2D3. To demonstrate that proliferation required MCSF, cultures were exposed to a monoclonal anti-MCSF antibody during days 3, 4, 5, 6, or 7. Inhibition of TRAP+ MNC formation was 85% when antibody was added during day 3. Antibody treatment after day 5 had little effect on the OCLC number. Fusion of precursors showed steady progression with OCLCs containing 4.8 +/- 0.3 nuclei at the end of day 4, 8.3 +/- 0.5 nuclei after day 5, 12.0 +/- 1.3 after day 6, and 13.7 +/- 1.5 at the end of day 7. This steady accretion of nuclei was unaffected by doses of MCSF antibody which blocked proliferation. In conclusion, we have shown that OCLCs arise from an MCSF-dependent expansion of the precursor pool occurring during days 3 and 4. Fusion of these precursors, which begins as proliferation diminishes, is able to progress in the presence of anti-MCSF antibody. These results should help refine the analysis of factors affecting proliferation and fusion of osteoclasts in murine marrow culture.

Acid Phosphatase↗
PubMed1995

Characterization and functional studies on rat liver fat-storing cell line and freshly isolated hepatocyte coculture system.

We developed and characterized a coculture system composed of a fat-storing cell clone (CFSC-2G) and freshly isolated hepatocytes that can reproduce in vitro some of the physical and functional relationships observed in vivo. Hepatocytes in the coculture are polarized, are smaller in size than hepatocytes plated on plastic, maintain a cuboidal shape, and have a tendency to form cords. Fat-storing cells, which are initially extended, retract and leave spaces that resemble liver sinusoids. Both cell types in the coculture system are functional for at least two weeks as determined by the expression of high levels of liver-specific protein mRNAs as well as by the production and secretion of liver-specific proteins into the culture medium. The hepatocytes maintain relatively high levels of asialoglycoprotein receptor on their cell surface and form functional gap junctional complexes with fat-storing cells. Hence, this coculture system retains a number of differentiated functions of hepatocytes, making it a useful model to study cell-cell interactions in culture and to analyze regulation of hepatocyte functions.

Animals↗
PubMed1994

Differential effect of 4-hydroperoxycyclophosphamide and antimyeloid monoclonal antibodies on T and natural killer cells during bone marrow purging.

Autologous bone marrow (BM) transplantation after high dose therapy is widely used to treat acute leukemia, lymphoma, and selected solid tumors. In studies of BM purging with chemical agents, monoclonal antibodies (MoAbs), or other agents, the emphasis has been on the efficacy of tumor cell removal and sparing of hematopoietic progenitor cells. Two commonly used methods of BM purging for patients with acute myeloid leukemia have been the drug 4-hydroperoxycyclophosphamide (4-HC) and (MoAbs) directed to myeloid antigens such as CD14, CD15, and CD33. Although both methods of BM purging have potent activity against leukemia cells, 4-HC is also quite toxic to normal hematopoietic progenitor cells in the same concentrations that are used to deplete leukemia cells. To further characterize the cellular composition of BM after purging, we examined the effects of MoAbs plus complement and 4-HC on cells of the lymphoid lineage in the BM. 4-HC exerted a concentration-dependent cytotoxicity on clonogenic T lymphocytes, natural killer (NK) cells, and lymphokine (interleukin-2)-activated killer (LAK) cells, whereas the anti-CD14 and anti-CD15 MoAbs had little effect. At a concentration of 4-HC commonly used for BM purging (60 micrograms/mL), there were 4 to 5 logs of T-cell depletion and almost complete elimination of NK- and LAK-cell activity. In contrast, 4-HC at low concentrations (eg, 3 micrograms/mL) spared the majority of lymphoid cells suggesting that low concentration 4-HC combined with MoAb purging may be a desirable alternative to higher concentration 4-HC. These data indicate that purging with antimyeloid MoAbs, but not with 4-HC, spares the function of mature graft lymphocytes. Infusion of viable lymphocytes may be important for the transfer of immune memory against microbial and neoplastic antigens and may hasten immune reconstitution. In addition, mature graft lymphocytes may also be selectively activated and expanded in conjunction with interleukin-2 administration after BM transplantation.

Antibodies, Monoclonal↗
PubMed1994

The management of patients with advanced carcinoid tumors and islet cell carcinomas.

OBJECTIVE: To determine the effectiveness of hepatic artery occlusion alone and with sequenced chemotherapy for patients with hepatic-dominant metastases of islet cell carcinomas and carcinoid tumors. DESIGN: Nonrandomized, observational study with follow-up from 2.5 to 10 years. PATIENTS: 111 ambulatory patients referred to a multidisciplinary tertiary care center who had histologically proven islet cell carcinoma or carcinoid tumor and symptomatic measurable metastatic lesions in the liver or hormonal abnormalities or both. The patients were ambulatory but were having substantial symptoms because of their endocrine syndromes or their tumors. INTERVENTION: All patients had hepatic artery occlusion done surgically or by catheterization and embolization. After this procedure, 71 patients were selected for chemotherapy with alternating two-drug regimens of doxorubicin plus dacarbazine and streptozocin plus fluorouracil. Main outcome measures of response to therapy were rates of tumor regression, rates of improvement in endocrine abnormalities, symptomatic improvement, and duration of favorable response. RESULTS: Objective regressions were observed in 60% of patients treated with occlusion alone and in 80% with chemotherapy added. Regressions were associated with substantial or complete relief from the endocrine syndromes. With occlusion alone, the median duration of regression was 4.0 months and with chemotherapy added, it was 18.0 months. Any comparative inferences about the two treatment regimens must be guarded, because this was not a randomized trial and marked differences occurred in the distribution of prognostic factors between the patient groups. Side effects of arterial occlusion included fever, nausea, pain, and abnormalities in liver function. Side effects of chemotherapy included nausea, vomiting, leukopenia, and alopecia. CONCLUSIONS: Hepatic arterial occlusion can frequently produce major regression of neuroendocrine tumors with relief from the hormonal syndromes. Sequential chemotherapy may improve the rate and duration of the regression.

Adult↗