Biomedical subjects

I Brodsky

Publications and source records attributed to I Brodsky.

At least 37 records · Page 2Linked to original sources

PubMed1997

ATP modification of serotonin-induced contraction of the rat pulmonary artery.

Serotonin (5HT) and ATP are simultaneously released from activated platelets at the site of vascular injury and are hypothesized to play a significant role in hemostasis. Our laboratory investigated the modulation of vascular contraction of arterial ring segments by 5HT plus ATP as a model of the potential regulation of localized vascular tone by platelet releasates in regions of arterial damage. This study expands our focus on how these two vasoactive components, released from platelet dense granules, regulate vascular tone. 5HT- and 5HT analog-induced vasoconstrictions were measured in the presence or absence of ATP and ATP analogs with intact or deendothelialized rat pulmonary arterial ring segments suspended in organ baths. The possible presence of 5HT2 and 5HT1A receptor types in the rat pulmonary artery was demonstrated by vasoconstrictions induced by 5HT and (+)-8-hydroxy-2-(di-N-propylamino) tetralin hydrobromide (DPAT). The DPAT response was only 30%-50% of that induced by comparable concentrations of 5HT. The 5HT-induced contraction was inhibited by the 5HT2 antagonist, ketanserin. ATP equally relaxed 5HT and DPAT contracted tissue while the P2X agonist, alphabeta-methylene ATP, increased the contracted state of DPAT-treated arteries to a significantly greater extent than observed with 5HT. The P2y agonist, 3'-O-(4-benzoyl)benzoyl ATP (BzATP), the P2X agonist betagamma-methylene ATP, and ATP all relaxed 5HT-induced contractions to similar levels under a number of physiological conditions. The final level of 5HT-induced tissue contraction was the same whether ATP was added prior to, after, or simultaneously with 5HT. ATP and the phosphodiesterase inhibitor, theophylline, inhibited 5HT-induced vasoconstriction in an additive fashion. The ATP effects were endothelium dependent, while the inhibition by theophylline was not. The distribution of 5HT and ATP receptor types, as indicated by these and numerous other studies, appears to vary within different regions of the cardiovascular system. Extracellular ATP can synergistically enhance or inhibit 5HT-contracted blood vessels differentially at localized regions, which would significantly impact on localized vascular tone, and this in turn may modulate hemostasis and thrombosis.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1997

Cytokine-mediated erythroid maturation in megakaryoblastic human cell line HU-3.

HU-3 is a bipotential cell line derived from the bone marrow of a patient with megakaryoblastic leukemia. Continuously proliferating cells evolved from cultures supplemented with nutrient medium containing human serum and granulocyte-macrophage (GM) colony-stimulating factor (CSF). Growth and viability of the HU-3 cell line was strictly dependent on the presence of GM-CSF, interleukin-3, or thrombopoietin (Tpo). Independent of the cytokine, the cells constitutively expressed a well-defined megakaryocyte phenotype, with 70-95% of the cells positive for CD4, CD34, and platelet glycoproteins Ib, IIb, and IIIa. Fewer than 10% of the cells had detectable erythroid glycophorin A. Erythropoiesis was induced in HU-3 parental cells and five clones harvested from culture medium containing GM-CSF by replacement of the growth-promoting cytokine with stem cell factor (SCF) and erythropoietin (Epo). During the first week of induction, the proliferating cells slowly acquired erythroid markers. Concomitant with a maturational growth arrest during the second week, there was a rapid accumulation of gamma and beta globin chains and benzidine reactive hemoglobin, as well as a distinct erythroid morphology. The culture declined after 12 days because of the transient effect of SCF in maintaining viability. Parental and cloned cells cultured for 7 days in Tpo-supplemented medium responded to the synergistic growth effect of SCF and Epo but were markedly suppressed in their yield of hemoglobinized cells. Recycling of the cells in GM-CSF for 4 days did not reverse the suppressive effect of Tpo. These results suggest a role for Tpo in the lineage commitment of erythromegakaryocytic progenitors by suppressing the erythroid potential. With its constitutive megakaryocyte phenotype and inducible erythroid potential, the self-renewing bipotential HU-3 cell line may represent one of the earliest stages in megakaryocytopoiesis before irreversible lineage commitment. The suppressive effect of Tpo on the erythroid potential of cloned HU-3 cells enhances the value of this cell line for deciphering the molecular and cellular events during lineage commitment of progenitor cells.

Cell Division↗

PubMed1996

High incidence of potential p53 inactivation in poor outcome childhood acute lymphoblastic leukemia at diagnosis.

Previous studies have indicated that p53 gene mutations were an uncommon event in acute lymphoblastic leukemia (ALL) in children. In one series of 330 patients, p53 mutations were seen in fewer than 3%. We analyzed bone marrow mononuclear cells derived from 10 children with ALL at diagnosis who subsequently failed to achieve a complete remission or who developed relapse within 6 months of attaining complete remission for p53 gene mutations and mdm-2 overexpression. We found that three children had p53 gene mutations, and four overexpressed mdm-2. Also, experiments comparing relative levels of mdm-2 RNA and protein in these patients demonstrated that mdm-2 overexpression can occur at the transcriptional and posttranscriptional level in primary leukemic cells. Although we were unable to link Waf-1 RNA expression with p53 status in childhood ALL, our data show potential p53 inactivation by multiple mechanisms in a large percentage of these patients and demonstrate that these alterations can be detected at diagnosis. Inactivation of the p53 pathway may, therefore, be important in children with ALL who fail to respond to treatment and may be useful for the early identification of children requiring alternative therapies.

Adolescent↗

PubMed1996

Directly probing rapid membrane protein dynamics with an atomic force microscope: a study of light-induced conformational alterations in bacteriorhodopsin.

This paper demonstrates that an atomic force microscope can be used to directly monitor rapid membrane protein dynamics. For this demonstration the membrane-bound proton pump, bacteriorhodopsin, has been investigated. It has been unequivocally shown that the light-induced dynamic alterations that have been observed do not arise from external artifacts such as heating of the sample by the incident light, but that these changes can be directly linked to the light-induced protein conformational alterations in this membrane. In essence, it has been shown that the light energy absorbed by bacteriorhodopsin is converted not only to chemical energy but also to mechanical energy. In summary a new ultrasensitive tool is described for monitoring the molecular dynamics of materials with wide applicability to fundamental and applied science.

Bacteriorhodopsins↗

PubMed1996

Unrelated donor bone marrow transplantation without T cell depletion using a chemotherapy only condition regimen. Low incidence of failed engraftment and severe acute GVHD.

Twenty-five patients with hematologic malignancies were treated with busulfan (16 mg/kg) and cyclophosphamide (50 mg/kg x 3 days) as conditioning for bone marrow transplantation using marrow from serologically matched, DR locus genotypically identical unrelated donors. Previous studies of BuCy2 as conditioning for UD-BMT have reported a graft failure rate of up to 21% suggesting it may be insufficiently immunosuppressive in this setting. We elected not to use BuCy4 as it may have a higher incidence of extramedullary toxicity. In addition the patients received GM-CSF (500 mg/m2) from day 0, cyclosporine and short-course methotrexate (15 mg/m2 x 1, then 10 mg/m2 x 3) as GVHD prophylaxis and prophylactic ganciclovir at engraftment if either they or their donor were CMV antibody positive. The median age of the 25 patients was 41 years and the most common diagnosis was CML (76%). Seven patients were considered poor risk and eight males were recipients of marrow from female donors. Sixteen patients survive at a median of 435 days from transplant. The actuarial overall and disease-free survivals at 1 year in this group of older patients were 62 +/- 20% and 57 +/- 20% and 100-day survival was 70%. The engraftment rate was 100%; there have been no instances of secondary graft failure. Fifteen patients (60%) developed grade II-IV GVHD and 12 of 16 (75%) developed some chronic GVHD but only half of these were extensive. The performance status of survivors is good (median of 90); seven of 12 eligible patients are back at work. This study demonstrates that UD-BMT can be successfully performed in very closely HLA-matched older patients using a chemotherapy-only protocol and that low rates of severe acute GVHD can be achieved without T cell depletion.

Actuarial Analysis↗

PubMed1996

Hepatic dysfunction following busulfan and cyclophosphamide myeloablation: a retrospective, multicenter analysis.

Veno-occlusive disease continues to be a significant cause of morbidity and early mortality following bone marrow transplantation. This study retrospectively analyzes the incidence and risk factors for severe VOD in 350 patients treated with 4 days of busulfan (total 16 mg/kg) and 2 days of cyclophosphamide (120 mg/kg) at four marrow transplant centers. Using the criteria defined by McDonald et al (Hepatology 1984; 4: 116-122), 93/350 (27%) developed VOD (11% mild, 5% moderate and 11% severe). Multivariate analysis revealed the following risk factors to be significantly associated with severe VOD: pretransplant transaminase and alkaline phosphatase elevation, ciprofloxacin antibiotic prophylaxis, use of estrogen/progestins or vancomycin during the peritransplant period and methotrexate for GVHD prophylaxis. Mild to moderate grades of VOD were not associated with significantly increased mortality but mortality was higher in patients with severe VOD (31%, P = 0.0013). These data suggest that risk factors for VOD may depend on the preparative regimen used and suggest that use of these risk factors may identify a subgroup of patients that can be targetted for studies of prevention of VOD.

Adolescent↗

PubMed1995

Extracellular ATP inhibits agonist-induced mobilization of internal calcium in human platelets.

Our previous studies have demonstrated that platelets possess ATP purinergic receptors in addition to the ADP, P2T, receptor. Occupancy of the P2 receptor by ATP inhibited agonist-induced platelet aggregation. This study demonstrated that the mechanism of inhibition may involve ATP inhibition of agonist-induced mobilization of internal calcium. Within the cardiovascular system, the ATP inhibition of calcium mobilization is unique to platelets. All other cell types in the cardiovascular system, where calcium mobilization is affected by extracellular ATP, responded with an increased mobilization as opposed to inhibition. The platelet inhibitory response to ATP was enhanced by the addition of an ATP generating system, creatine phosphate/phosphocreatine kinase. ATP and ATP analogues were found to inhibit calcium mobilization with a rank order of alpha beta-methylene ATP, beta gamma-methylene ATP approximately ATP > benzoyl ATP > 2 methylthio ATP which is a characteristic of P2x-like receptors. The inhibitory effect of ATP could be abrogated by prolonged treatment of platelets with the P2x desensitizing agent, alpha beta-methylene ATP. Also, UTP and CTP were approximately as effective inhibitors as ATP while GTP was not. ATP competition with ADP for the P2T receptor was excluded in studies with platelets derived from an aspirin-treated individual which were essentially insensitive to ADP. The agonist-induced calcium mobilization and inhibition by ATP occurred with the thromboxane A2 mimetic, U46619, collagen and thrombin; however, the kinetics of mobilization varied somewhat with the different agonists. The responses to extracellular ATP were independent of extracellular Ca2+, where 1 mM calcium or 0.3 mM EGTA was added to the reaction mixture. The inhibition of calcium mobilization coupled to inhibition of platelet aggregation by extracellular ATP may serve an important physiologic role. ATP, released from activated platelets at localized sites of vascular injury, may help to limit the size of the platelet plug-clot that, if left unregulated, could occlude the injured blood vessel.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1995

The role of water in retinal complexation to bacterio-opsin.

A system is described that allows for the delineation of the factors that effect the complexation of retinal to the apoprotein of bacteriorhodopsin. This complexation is investigated in various states of hydration, in H2O and D2O, at a variety of pH levels, with mutant membranes and labeled retinals. The complexation reaction was also investigated using absorption spectroscopy and vibrational spectra using difference Fourier transform infrared spectroscopy. The results demonstrate the crucial role of water in controlling the protein conformations that lead to protein/ligand binding reactions and begin to shed new light on the protein control of a reaction that normally cannot take place in an aqueous medium.

Bacteriorhodopsins↗

PubMed1995

Translocation 11;14 in newly diagnosed chronic myelogenous leukemia.

In patients with chronic myelogenous leukemia (CML), the Philadelphia chromosome may be associated with a number of other cytogenetic lesions. However, t(11;14)(q13;q32), found mainly in B-cell lymphoproliferative disorders, has not been previously reported in Ph-positive CML. We describe a patient with hematologically typical chronic phase CML in whom both cytogenetic lesions were found at diagnosis.

Adult↗

PubMed1995

Extramedullary toxicity of a conditioning regimen containing busulphan, cyclophosphamide and etoposide in 84 patients undergoing autologous and allogenic bone marrow transplantation.

Relapse is still a common problem after bone marrow transplant (BMT) and teh value of adding etoposide to standard conditioning agents is being tested. The aim of the study was to assess the extramedullary toxicity which resulted from adding etoposide to busulphan 16 mg/kg and cyclophoshamide 120 mg/kg (BuCY2). Eighty four patients received etoposide 40 mg/kg in addition to BuCY2 as conditioning for autologous and allogeneic BMT for leukemia and lymphoma. The Bearman system of grading extramedullary toxicity was used along with a system of grading skin toxicity that we devised. There were seven acute toxic deaths (8%) and in total 15 patients experienced life-threatening or fatal toxicity. The major finding was a striking increase in pulmonary toxicity with six deaths (five alveolar hemorrhage and one pulmonary embolus). Five of seven of the patients with severe pulmonary toxicity had been given irradiation to the lung fields (P < 0.001). Thirty nine per cent of patients had veno-occlusive disease of the liver but the case fatality rate was low (1 of 33). Dermatologic toxicity was experienced by 82% of patients and was symptomatically troublesome but rapidly reversible. The addition of etoposide to BuCY2 increases non-hematological toxicity. This regimen is associated with severe pulmonary toxicity in patients with a history of prior chest irradiation. A high incidence of skin toxicity was seen; a system for describing this toxicity is proposed.

Adolescent↗

PubMed1994

Decreased protein catabolism after exercise in subjects with IDDM.

We examined whether the increased rates of protein catabolism (proteolysis and leucine oxidation) associated with moderate insulinopenia in subjects with IDDM would be accentuated by prior bicycle exercise (53% VO2max for 82 min). Insulin infusions maintained plasma glucose concentrations on one study day in "tight" control (TC: 6 mmol/l) and on a separate day in "loose" control (LC: 12 mmol/l). Elevations in serum ketone body, plasma NEFA, and whole-blood branched-chain amino acid concentrations on the loose control day during the basal period persisted throughout the post-exercise recovery period. Amino acid kinetics were estimated during a primed, constant infusion of L-[1-13C]leucine from plasma dilution of alpha-[1-13C]KIC and expired air 13CO2 enrichments. Loose control was associated with increased rates of whole-body leucine oxidation (LC 25 +/- 7 vs TC 21 +/- 8 mumol.kg-1.h-1) and protein degradation (LC 127 +/- 12 vs TC 118 +/- 18 mumol.kg-1.h-1) (both p < 0.05). During the 2-h post exercise recovery period, there were significant decreases in rates of leucine oxidation (LC 21 +/- 7, TC 16 +/- 7) and protein degradation (LC 112 +/- 13, TC 107 +/- 11), compared to the basal period (both p < 0.05, basal vs recovery). Rates of whole-body protein synthesis were unchanged by prior exercise. In conclusion, moderate insulinopenia is associated with significantly higher rates of protein degradation and leucine oxidation in the basal state. Following exercise, net protein catabolism is diminished due to reduced rates of protein degradation in the presence of maintained rates of protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Detection of bcrabl fusion mRNA in samples of whole, unfractionated blood.

Using a new strategy, capture-RT-PCR, bcrabl fusion mRNA sequences were specifically and sensitively detected in samples of whole blood from leukemia patients with the Philadelphia chromosome. Sample processing required only mixing blood with the chaotropic salt, GuSCN, and mRNA was captured during a short incubation of prepared blood with an affinity membrane. Immobilized mRNA sequences were amplified without elution. No radioisotopes or Southern transfer were needed.

Blood Specimen Collection↗

PubMed1994

A controlled clinical trial with a specifically configured RNA drug, poly(I).poly(C12U), in chronic fatigue syndrome.

Chronic fatigue syndrome (CFS) is a physically debilitating illness associated with immunologic abnormalities, viral reactivation, and impairment of cognition. In a randomized, multicenter, placebo-controlled, double-blind study of 92 patients meeting the CFS case definition of the Centers for Disease Control and Prevention, the response of several laboratory and clinical variables to an antiviral and immunomodulatory drug, poly(I).poly(C12U), was determined. Measures of clinical response included Karnofsky performance score, a cognition scale derived from a self-administered instrument assessing symptomatology (SCL-90-R), an activities of daily living scale, and exercise treadmill performance. After 24 weeks, patients receiving poly(I).poly(C12U) had higher scores for both global performance and perceived cognition than did patients receiving placebo. In particular, patients given poly(I).poly(C12U) had increased Karnofsky performance scores (P < .03), exhibited a greater ability to do work during exercise treadmill testing (P = .01), displayed an enhanced capacity to perform the activities of daily living (P < .04), had a reduced cognitive deficit (P = .05), and required less use of other medications (P < .05).

Activities of Daily Living↗

PubMed1993

Occupancy of P2 purinoceptors with unique properties modulates the function of human platelets.

This report demonstrates that platelets possess P2 purinoceptors with unique properties that distinguish them from the ADP (P2T) receptor. Extracellular ATP, and its poorly hydrolyzable analogues, inhibit collagen- and U46619 (a thromboxane mimetic)-induced platelet aggregations. Adenosine deaminase was without effect on ATP action while reversing the inhibitory effect of adenosine. A unique aspect of the P2 receptor is the sensitivity to UTP and CTP and insensitivity to GTP. The rank order of inhibition by beta gamma-methylene ATP, alpha beta-methylene ATP > ATP indicates that a P2x-like receptor is present on the platelet membrane. This conclusion is further supported by the nearly complete desensitization to ATP by pre-exposure of platelets to alpha beta-methylene-ATP. However, unlike previously described P2x purinoceptors, the inhibition of platelet aggregation by extracellular ATP appears to result, at least in part, from the ATP-induced increase of intracellular cyclic AMP levels apparently coupled through a Gs protein. The combined addition of iloprost (0.14 to 1.39 nM) and ATP (18 microM) or ATP (20-40 microM) and the phosphodiesterase inhibitor theophylline (0.5 to 1 mM) synergistically inhibited platelet aggregation implying a common interactive site with adenylate cyclase. This is further substantiated by the ability of the adenylate cyclase inhibitor, 2',5'-dideoxyadenosine, to abrogate the inhibitory effects of ATP. The protein kinase A (PKA) inhibitor H1004 blocks ATP inhibition of platelet aggregation while the protein kinase C inhibitor H7 did not. This implies that the generation of cyclic AMP, with the subsequent activation of PKA and phosphorylation of selected proteins is required, in part, for the action of ATP.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1993

Expression of HERV-K proviruses in human leukocytes.

HERV-K is a 50-copy, human endogenous, class 1 retroviral element that contains some polycistrons with gag, pol, and env open reading frames. Although expression of HERV-K proviruses has been shown in cultured human cell lines, expression of these elements has not been shown in human blood leukocytes. Using both reverse transcriptase-polymerase chain reaction and ribonuclease protection techniques, we show HERV-K pol gene expression in human blood leukocytes. Expression in blood leukocytes from 7 normal individuals was from a variety of different HERV-K proviruses, while restricted expression was observed in blood cells of 5 leukemia patients and 3 polycythemia vera patients. Evidence is presented suggesting that the restricted expression in leukemia blood cells is a result of gene regulation, not gene amplification.

Adult↗

PubMed1993

Bronchiolitis obliterans after bone marrow transplantation: the effect of preconditioning.

While half of all patients receiving bone marrow transplantation (BMT) for malignancies and related diseases may achieve prolonged disease-free survival, 2-10% of patients undergoing allogeneic transplantation develop bronchiolitis obliterans (BrOb). We have hypothesized that total body irradiation (TBI) which has been used for pretreatment may influence the subsequent development of BrOb in patients undergoing allogeneic BMT. Since 1976, we have treated 104 patients undergoing allogeneic BMT with non-TBI preconditioning. Of 60 patients that survived and were evaluable for chronic graft versus host disease (GVHD) 26 developed chronic GVHD (43%). Four of 104 patients (3.9%) developed BrOb by clinical and/or pathologic findings. Four of 4 patients (100%) with BrOb had chronic GVHD. Two of these 4 patients (50%) were alive at the end of 2 years. These data demonstrate that chronic GVHD is a risk factor for BrOb in patients receiving non-TBI preconditioning regimens. The similar incidence of BrOb in this population compared to other studies using TBI suggest that the preconditioning regimen is not a factor in the development of BrOb. Further study is needed to confirm these findings. Allogeneic bone marrow transplantation (BMT) has revolutionized the therapeutic approach toward acute and chronic leukemias, aplastic anemia and rare immunodeficiency disorders. Half of all patients that undergo BMT achieve long-term disease-free survival but a similar number develop significant complications [1].(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Outcome of patients requiring medical ICU admission following bone marrow transplantation.

Despite encouraging results seen following bone marrow transplantation (BMT), it has been observed that once these patients become critically ill and require medical intensive care unit (MICU) admission, the chances of survival are poor. We hypothesized that while mechanical ventilation would be an important predictor for death in the MICU, those patients not requiring mechanical ventilation could be successfully discharged from the MICU. The records of 36 patients with 43 admissions to the MICU following BMT were analyzed. Of these admissions, 33 (76.7 percent) patients had allogeneic and 10 (23.3 percent) had autologous transplants, respectively. Overall, 14 (32.6 percent) of the admissions resulted in a satisfactory discharge from the MICU. There was no significant difference in the survival rates between those patients undergoing allogeneic or autologous transplantations, 11 (33.3 percent) vs 3 (30.0 percent), respectively. Twenty-seven (62.8 percent) of the admissions resulted in mechanical ventilation and were performed in 20 (66.7 percent) patients with allogeneic BMTs and 7 (70.0 percent) patients with autologous BMTs, which was not significantly different. The survival rate for those requiring mechanical ventilation was significantly less than for those not mechanically ventilated during their MICU stay, 1 (3.7 percent) vs 13 (81.3 percent), respectively (p < 0.001). Those patients who did not survive their MICU stay had a significantly higher mean APACHE II score of 21.2 +/- 4.7 than the survivors' score of 15.8 +/- 3.8 (p < 0.001). The average length of stay for the survivors was 4.4 + 3.0 days, which was significantly less than the 17.8 +/- 24.0 days for those patients not surviving (p < 0.001). These data indicate that admission to the MICU may result in a beneficial outcome for critically ill patients with BMTs, but for those requiring mechanical ventilation due to respiratory failure, the chances of survival are poor. This information may be useful for providing patients with BMTs and their families with realistic estimates of prognosis prior to transfer to the MICU and mechanical ventilation.

Adult↗

PubMed1993

The detection of post-therapy residual minimal disease in leukemias characterized by specific chromosomal anomalies.

Chromosomal and Southern Blot analyses have been used to diagnose Leukemias characterized by non-random chromosomal rearrangements. They have also been used to monitor disease progression during and after chemotherapy. These methodologies are often not adequate to detect RMD after ablative therapy and Bone Marrow Transplantation (BMT). Molecular quantitative Polymerase Chain Reaction (PCR) techniques have been developed to detect low levels of leukemic cells in patients with diseases characterised by fusion transcripts. 95% of Chronic Myelocytic (CML) and 15-25% of Acute Lymphoblastic Leukemia (ALL) patients are Ph1 producing a fusion transcript between the abl proto-oncogene and the bcr gene. Acute Promyelocytic Leukemia (APL) with break points in the (RAR) gene and the zyl gene also produces a fusion transcript. The significance of PCR for 1) detecting RMD after therapy, 2) correlating low levels of leukemic cells over time with therapeutic response and long term remission and 3) assessing the effect of RMD during remission by sequential analyses is discussed.

Adult↗