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J Weinstein

Publications and source records attributed to J Weinstein.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cell cycle-regulated expression, phosphorylation, and degradation of p55Cdc. A mammalian homolog of CDC20/Fizzy/slp1.

p55Cdc is a mammalian protein that shows high homology to the cell cycle proteins Cdc20p of Saccharomyces cerevisiae and the product of the Drosophila fizzy (fzy) gene, both of which contain WD repeats and are thought to be required for the metaphase-anaphase transition. The fzy mutants exhibit a metaphase arrest phenotype, which is accompanied by stabilization of cyclins A and B, leading to the hypothesis that fzy function is required for cell cycle-regulated ubiquitin-mediated proteolysis. p55Cdc expression was initiated at the G1/S transition and steady state levels of p55Cdc were highest at M and lowest in G1. Inhibition of the 26 S proteasome prevented both mitotic exit and loss of p55Cdc at the M/G1 transition, suggesting that p55Cdc degradation was mediated by the cell cycle-regulated proteolytic pathway. Immune complexes of p55Cdc obtained at different cell cycle stages showed a variety of proteins with dramatic differences observed in the pattern of associated proteins during the transition from G2 to M. Immunolocalization of p55Cdc demonstrated dynamic changes in p55Cdc localization as the cells transit mitosis. p55Cdc appears to act as a regulatory protein interacting with several other proteins, perhaps via its seven WD repeats, at multiple points in the cell cycle.

Carrier Proteins↗
PubMed1996

Cost-effectiveness of lumbar discectomy.

Cost-effectiveness analysis is useful when attempting to determine whether the benefits of an intervention are worth is costs. It can help clinicians to consider more explicitly all potential costs and outcomes of a given treatment, and it can assist policy makers in determining how best to allocate limited health-care resources to maximize the health of a population. This article describes the research methods used to estimate cost-effectiveness, and then examines existing reports on the cost-effectiveness of lumbar disc surgery. Results of previously published studies were inconsistent, indicating that estimates of discectomy's cost-effectiveness are highly dependent on how one measures and values the improvement in quality of life resulting from the procedure. If only long-term outcomes are considered, the procedure appears no more effective than continued medical treatment. But discectomy seems effective when its short-term benefits are considered. In either case, costs for the procedure are moderate. The authors conclude that for carefully selected patients with herniated lumbar discs, short-term quality of life is improved substantially with surgical versus medical treatment. When this benefit is considered, discectomy appears to be a cost-effective intervention, although this conclusion applies only to carefully selected patients with clearly defined indications for surgery. For patients without these indications and for patients in whom the immediate relief of sciatica is less important, discectomy's cost-effectiveness will be less favorable.

Cost of Illness↗
PubMed1996

A point mutation causes mistargeting of Golgi GlcNAc-TV in the Lec4A Chinese hamster ovary glycosylation mutant.

The Lec4A and Lec4 Chinese hamster ovary glycosylation mutants lack N-linked glycans with GlcNAcbeta(1,6)Manalpha(1,6) branches that are initiated by the transferase termed GlcNAc-TV. Detergent extracts of Lec4 cells have no detectable GlcNAc-TV activity, but Lec4A extracts have activity equivalent to that of parental Chinese hamster ovary cells. This discrepancy occurs because Lec4A GlcNAc-TV activity co-localizes with membranes of the endoplasmic reticulum (ER) instead of with Golgi membranes (Chaney, W., Sundaram, S., Friedman, N., and Stanley, P. (1989) J. Cell. Biol. 109, 2089-2096). cDNAs from the coding region of the GlcNAc-TV gene have now been isolated from each mutant line. Lec4 GlcNAc-TV cDNA was found to possess two insertions, the first of which shifts the open reading frame and codes for a truncated transferase missing 585 amino acids from the catalytic domain. By contrast, Lec4A GlcNAc-TV cDNA possesses a single point mutation from T to G, which results in a change from Leu to Arg at position 188. When transfected into Lec4 cells, both cDNAs gave the appropriate phenotype; Lec4 cDNA was unable to restore GlcNAc-TV activity, whereas Lec4A cDNA converted Lec4 cells to the Lec4A phenotype, with an active GlcNAc-TV mislocalized to ER membranes. Moreover, Lec4A cDNA cured of its mutation restored a functional, Golgi-localized GlcNAc-TV to Lec4 cells. The results demonstrate that a single change in the 740 amino acids of GlcNAc-TV serves to functionally inactivate the transferase in an intact cell by causing it to localize to the ER instead of the Golgi compartment. The mislocalized transferase retains full enzyme activity, showing that it is well folded and stable and suggesting that the L188R mutation either prevents association with exit complexes from the ER or causes retrograde transport from a Golgi compartment.

Amino Acid Sequence↗
PubMed1996

Over-expression of p55Cdc inhibits granulocyte differentiation and accelerates apoptosis in myeloid cells.

p55Cdc is a protein identified in cycling mammalian cells. It is highly expressed in proliferating but not in differentiated or growth-arrested cells. Structurally, p55Cdc is similar to the Cdc4 and Cdc20 proteins, which have been proposed to regulate DNA synthesis and mitosis in Saccharomyces cerevisiae. To define the role of p55Cdc during myelopoiesis, we studied the expression and regulation of this protein in response to the hematopoietic growth factors, granulocyte-macrophage colony stimulating factor (GM-CSF) and granulocyte-colony stimulating factor (G-CSF). We analysed the time course of expression of p55Cdc in response to GM-CSF and G-CSF stimulation in the murine factor-dependent myeloid leukemic cell line, 32Dc13, and demonstrated differential regulation of p55Cdc in response to these two growth factors. Over-expression of p55Cdc resulted in acceleration of apoptosis in growth factor- and serum-free conditions, although no difference was observed in the rate of cell proliferation. Decreases in p55Cdc protein levels correlated with cells undergoing apoptosis. p55Cdc over-expression also inhibited granulocyte differentiation of 32Dc13 cells treated with G-CSF. Our studies suggest that p55Cdc regulation is critical for normal cell cycle control during myeloid cell proliferation and differentiation.

Animals↗
PubMed1996

Post-translational modifications of recombinant P-selectin glycoprotein ligand-1 required for binding to P- and E-selectin.

P-selectin glycoprotein ligand-1 (PSGL-1) is a mucin-like ligand for P- and E-selectin on human leukocytes. PSGL-1 requires sialylated, fucosylated O-linked glycans and tyrosine sulfate to bind P-selectin. Less is known about the determinants that PSGL-1 requires to bind E-selectin. To further define the modifications required for PSGL-1 to bind P- and E-selectin, we transfected Chinese hamster ovary (CHO) cells with cDNAs for PSGL-1 and specific glycosyltransferases. CHO cells synthesize only core 1 O-linked glycans (Galbeta1-3GalNAcalpha1-Se r/Thr); they lack core 2 O-linked glycans (Galbeta1-3(Galbeta1-4GlcNAcbeta1-6)GalNAcalpha1 -Ser/Thr) because they do not express the core 2 beta1 6-N-acetylglucosaminyltransferase (C2GnT). CHO cells also lack alpha1 3 fucosyltransferase activity. PSGL-1 expressed on transfected CHO cells bound P- and E-selectin only when it was co-expressed with both C2GnT and an alpha1 3 fucosyltransferase (Fuc-TIII, Fuc-TIV, or Fuc-TVII). Chromatography of beta-eliminated O-linked glycans from PSGL-1 co-expressed with C2GnT confirmed synthesis of core 2 structures. Tyrosine residues on PSGL-1 expressed in CHO cells were shown to be sulfated. Phenylalanine replacement of three tyrosines within a consensus sequence for tyrosine sulfation abolished binding to P-selectin but not to E-selectin. These results demonstrate that PSGL-1 requires core 2 O-linked glycans that are sialylated and fucosylated to bind P- and E-selectin. PSGL-1 also requires tyrosine sulfate to bind P-selectin but not E-selectin.

Animals↗
PubMed1996

Dipyridamole mediated enhanced antiproliferative activity of 10-ethyl-10-deazaaminopterin (10-EDAM) against human lung cancer cell lines.

10-ethyl-10-deazaaminopterin (10-EDAM) is a rationally designed derivative of the antifolate, methotrexate (MTX). In a number of tumor models these design features have resulted in an improved spectrum of antiproliferative activity as compared with the parent compound. Using an MTT growth assay, we compared in vitro antiproliferative activity of 10-EDAM with MTX in eight lung cancer cell lines. Growth was inhibited in all lines tested by clinically achievable concentrations of 10-EDAM (0.1-1,000 nM). 10-EDAM was more cytotoxic than MTX at the same concentrations in all eight lung cancer cell lines. In an effort to enhance the antiproliferative effect, we evaluated the addition of dipyridamole (DPM), an inhibitor of nucleoside transport, to 10-EDAM (0.1-10 microns). DPM decreased the concentration of 10-EDAM required to cause 50% growth inhibition (IC50) in all eight cell lines tested. This suppression was statistically significant by 2-sided sign test (P = .0078). By contrast, the IC50 of MTX was decreased in only two of the eight cell lines when DPM was added (0.1-10 microM). In defined thymidine depleted media, cell kill by the combination of 10-EDAM and DPM was no greater than 10-EDAM alone, consistent with the possibility that DPM exerts some of its effect by inhibition of extrinsic nucleoside salvage. In consideration of the published activity of 10-EDAM in lung cancer and the modest clinical toxicity of DPM based biochemical modulation, we conclude the current in vitro data provide justification for clinical evaluation of this combination in patients with lung cancer.

Aminopterin↗
PubMed1995

Inhibition of human immunodeficiency virus type-1 integrase by curcumin.

Curcumin (diferuloylmethane) is the yellow pigment in turmeric (Curcuma longa L.) that is widely used as a spice, food coloring (curry) and preservative. Curcumin exhibits a variety of pharmacological effects including antitumor, anti-inflammatory, and anti-infectious activities and is currently in clinical trials for AIDS patients. The effects of curcumin have been determined on purified human immunodeficiency virus type 1 (HIV-1) integrase. Curcumin has an inhibitory concentration50 (IC50) for strand transfer of 40 microM. Inhibition of an integrase deletion mutant containing only amino acids 50-212 suggests that curcumin interacts with the integrase catalytic core. Two structural analogs, methyl cinnamate and chlorogenic acid, were inactive. Energy minimization studies suggest that the anti-integrase activity of curcumin could be due to an intramolecular stacking of two phenyl rings that brings the hydroxyl groups into close proximity. The present data suggest that HIV-1 integrase inhibition may contribute to the antiviral activity of curcumin. These observations suggest new strategies for antiviral drug development that could be based upon curcumin as a lead compound for the development of inhibitors of HIV-1 integrase.

Antiviral Agents↗
PubMed1995

Loads in the spinal structures during lifting: development of a three-dimensional comprehensive biomechanical model.

Epidemiological studies have shown that loads imposed on the human spine during daily living play a significant role in the onset of low back pain. The loads applied to the lumbar spine are shared by a number of structures: muscles; posterior elements, including facets and ligaments; and the disc of a ligamentous motion segment. In vivo, it is not practical to determine forces in these structures using experimental techniques. Biomechanical models, based on an optimization technique of electromyographic activities of the trunk muscles, have been proposed to predict forces in the load transmitting structures. The mathematical models reported in the literature are based on information collected from a wide variety of sources, of which the subject that takes part in the experiment is only one. The present study describes techniques developed in our laboratory to collect from the subjects themselves all the data needed for the formulation of a biomechanical model. The results demonstrated that back lifting with 0 N (no load), 90 N, and 180 N in the hands created maximum external flexion moments respectively of 109.6 Nm, 137.9 Nm, and 161.7 Nm, at the L3-4 disc level. The corresponding external axial compression forces on the disc were 469.5 N, 511.8 N, and 601.5 N. The predicted disc compression varied from 3.4 to 5.0 times the body weight. In comparison to the static lifting mode, the dynamic lifting task caused an increase in the disc compression force ranging from 15.8% to 39.4% depending on the load being lifted (e.g., 3256 N for the dynamic mode vs. 2516 N for the static mode when the subject lifted 90 N). The salient features of the entire protocol developed by the authors and the need for further improvements are also presented.

Adult↗
PubMed1995

Generation of a drug resistance profile by quantitation of mdr-1/P-glycoprotein in the cell lines of the National Cancer Institute Anticancer Drug Screen.

Identifying new chemotherapeutic agents and characterizing mechanisms of resistance may improve cancer treatment. The Anticancer Drug Screen of the National Cancer Institute uses 60 cell lines to identify new agents. Expression of mdr-1/P-glycoprotein was measured by quantitative PCR. Expression was detected in 39 cell lines; the highest levels were in renal and colon carcinomas. Expression was also detected in all melanomas and central nervous system tumors, but in only one ovarian carcinoma and one leukemia cell line. Using a modified version of the COMPARE program, a high correlation was found between expression of mdr-1 and cellular resistance to a large number of compounds. Evidence that these compounds are P-glycoprotein substrates includes: (a) enhancement of cytotoxicity by verapamil; (b) demonstration of cross-resistance in a multidrug-resistant cell line, (c) ability to antagonize P-glycoprotein, increasing vinblastine accumulation by decreasing efflux; and (d) inhibition of photoaffinity labeling by azidopine. Identification of many heretofore unrecognized compounds as substrates indicates that P-glycoprotein has a broader substrate specificity than previously recognized. This study confirms the validity of this novel approach and provides the basis for similar studies examining a diverse group of gene products, including other resistance mechanisms, putative drug targets, and genes involved in the cell cycle and apoptosis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

A novel mammalian protein, p55CDC, present in dividing cells is associated with protein kinase activity and has homology to the Saccharomyces cerevisiae cell division cycle proteins Cdc20 and Cdc4.

A novel protein, p55CDC, has been identified in cycling mammalian cells. This transcript is readily detectable in all exponentially growing cell lines but disappears when cells are chemically induced to fall out of the cell cycle and differentiate. The p55CDC protein appears to be essential for cell division, since transfection of antisense p55CDC cDNA into CHO cells resulted in isolation of only those cells which exhibited a compensatory increase in p55CDC transcripts in the sense orientation. Immunoprecipitation of p55CDC yielded protein complexes with kinase activity which fluctuated during the cell cycle. Since p55CDC does not have the conserved protein kinase domains, this activity must be due to one or more of the associated proteins in the immune complex. The highest levels of protein kinase activity were seen with alpha-casein and myelin basic protein as substrates and demonstrated a pattern of activity distinct from that described for the known cyclin-dependent cell division kinases. The p55CDC protein was also phosphorylated in dividing cells. The amino acid sequence of p55CDC contains seven repeats homologous to the beta subunit of G proteins, and the highest degree of homology in these repeats was found with the Saccharomyces cerevisiae Cdc20 and Cdc4 proteins, which have been proposed to be involved in the formation of a functional bipolar mitotic spindle in yeast cells. The G beta repeat has been postulated to mediate protein-protein interactions and, in p55CDC, may modulate its association with a unique cell cycle protein kinase. These findings suggest that p55CDC is a component of the mammalian cell cycle mechanism.

Amino Acid Sequence↗
PubMed1993

Isolation, characterization, and expression of a cDNA encoding N-acetylglucosaminyltransferase V.

A cDNA clone for the complete coding sequence for alpha-1,3(6)-mannosylglycoprotein beta-1,6-N-acetylglucosaminyltransferase V (GlcNAc-T V, EC 2.4.1.155) was isolated and expressed in COS-7 cells. Degenerate oligonucleotide primers for polymerase chain reaction were synthesized based on the amino acid sequence of three tryptic peptides isolated from affinity-purified GlcNAc-T V. Polymerase chain reaction amplimers were isolated from rat and mouse mRNA. A cDNA-encoding full-length enzyme was isolated from a rat 1 cell (EJ-ras-transformed) library and sequenced. Transient expression of this clone in COS-7 cells, followed by enzymatic activity assays, demonstrated that this cDNA sequence encodes GlcNAc-T V. Northern analysis of rat kidney mRNA revealed a single band corresponding to a length of about 7 kilobases. Sequence analysis of the cDNA clone demonstrated an open reading frame that encoded a type II membrane protein of 740 amino acids.

Amino Acid Sequence↗
PubMed1992

Job$ '92.

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Administrative Personnel↗