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E Rubinstein

Publications and source records attributed to E Rubinstein.

At least 37 records · Page 2Linked to original sources
PubMed2000

Sequence and expression of seven new tetraspans.

The tetraspans are components of large molecular complexes that include also non-tetraspan molecules, in particular integrins. We have identified and sequenced several new members of the tetraspan superfamily, called NET-1 to NET-7 (new EST tetraspan). Sequence analysis of the NET reveals a structure typical for tetraspans, with the presence of four transmembrane domains delimiting two extracellular regions as well as conserved amino acid residues. The NET are differentially expressed in human cell lines.

Amino Acid Sequence↗
PubMed2000

Severely reduced female fertility in CD9-deficient mice.

CD9 is a widely expressed cell surface molecule that belongs to the tetraspanin superfamily of proteins. The tetraspanins CD9, KAI-1/CD82, and CD63 are involved in metastasis suppression, an effect that may be related to their association with beta1 integrins. Knockout mice lacking CD9 were created to evaluate the physiological importance of CD9. CD9-/- females displayed a severe reduction of fertility. Oocytes were ovulated but were not successfully fertilized because sperm did not fuse with the oocytes from CD9-/- females. Thus, CD9 appears to be essential for sperm-egg fusion, a process involving the CD9-associated integrin alpha6beta1.

Animals↗
PubMed2000

CD46 (membrane cofactor protein) associates with multiple beta1 integrins and tetraspans.

The tetraspans associate with a large number of surface molecules, including a subset of beta1 integrins and, indirectly through CD19, with the complement receptor CD21. To further characterize the tetraspan complexes we have raised and selected monoclonal antibodies (mAb) for their ability to immunoprecipitate a molecule associated with CD9. A unique mAb was identified which recognizes the complement regulator CD46 (membrane cofactor protein). CD46 associated in part with several tetranspans and with all beta1 integrins that were tested (CD29/CD49a, CD29/CD49b, CD29/CD49c, CD29/CD49e, CD29/CD49f) but not with beta4 integrins. These data, together with cross-linking experiments showing the existence in living cells of CD46/integrin complexes, suggest that CD46 associates directly with beta1 integrins and indirectly with tetraspans. CD46 also acts as a receptor for measles virus; however, mAb to various integrins and tetraspans did not modify the virus fusion entry step.

Animals↗
PubMed2000

Staphylococcus aureus adherence to thrombin-treated endothelial cells is mediated by fibrinogen but not by platelets.

Recent studies emphasize the role of blood constituents in Staphylococcus aureus (S. aureus) adherence to subendothelial extracellular matrix. In the present study, the adherence of two strains of S. aureus (ATCC 29213 and RN 6390) grown to a postexponential phase to cultured human umbilical vein endothelial cells (EC-304) was examined. Under flow conditions (600 s(-1)), pretreatment of endothelial cells (ECs) with human alpha-thrombin (2 U/mL) significantly (2- to 4-fold) increased bacterial adherence to ECs. Adherence of both S. aureus strains to thrombin-treated ECs was similarly higher in the presence of whole blood, platelet-rich plasma, or platelet-poor plasma when compared with Tris-buffered saline solution (TBS). Platelet inactivation in whole blood by prostaglandin E1 did not reduce the adherence rate. When ATCC 29213 bacteria were suspended in TBS containing increasing concentrations of fibrinogen at near-physiologic ranges (0.25 to 2 mg/mL), a dose-dependent increase in S. aureus adherence to thrombin-activated ECs was observed that reached a maximum level of about 12-fold. Fibronectin used at the above physiologic concentrations (12.5 to 100 microg/mL) enhanced bacterial adherence up to 2-fold. Von Willebrand factor (1 IU/mL) did not support bacterial adherence to ECs, either alone or in combination with fibrinogen. Inhibition of fibrin formation either by the Gly-Pro-Arg-Pro peptide or by hirudin increased bacterial adherence by 50% and 90%, respectively. Blockage of either ICAM-I, alpha5beta1, or alphavbeta3 receptors on ECs by appropriate monoclonal antibodies resulted in substantial inhibition of bacterial adherence (by 42%, 65%, and 72%, respectively). Preincubation of S. aureus with a fibrinogen gamma-chain binding domain peptide led to 65% inhibition of adherence to ECs in the presence of fibrinogen. In contrast, preincubation of bacteria with the Arg-Gly-Asp-Ser peptide failed to affect their adherence. The data suggest that S. aureus adherence to the EC surface was (1) significantly enhanced by thrombin treatment of ECs, (2) not mediated by platelets, and (3) mediated by plasma fibrinogen, which binds to the bacteria via the C-terminus gamma-chain binding domain but not via the Arg-Gly-Asp sequence.

Alprostadil↗
PubMed2000

Trans-epithelial intestinal elimination of moxifloxacin in rabbits.

The intestinal trans-epithelial elimination of moxifloxacin was measured in the jejunum, ileum, caecum and in the bile in a rabbit model. Over a 120 min period following a single parenteral administration of moxifloxacin 15 mg/kg, peak serum concentration was 3.1 (+/- 1.1) mg/L. The elimination constants were: 0.019 (+/- 0. 017) microg/cm(2)/min, 0.011 (+/- 0.014) microg/cm(2)/min and 0.002 (+/- 0.002) microg/cm(2)/min in the jejunum, ileum and caecum, respectively. Per loop, over 120 min, the respective eliminated quantities were: 9.59 (+/- 9.37) microg, 8.26 (+/- 6.74) microg and 1.92 (+/- 1.86) microg. Biliary moxifloxacin concentrations varied between 1.30 and 5.16 mg/L and exceeded serum levels from 45 min onwards. Intestinal concentrations paralleled serum moxifloxacin levels. Altogether, approximately 4.5% of the moxifloxacin dose was eliminated trans-epithelially in the digestive tract over the 120 min experimental period.

Animals↗
PubMed1999

Selective tetraspan-integrin complexes (CD81/alpha4beta1, CD151/alpha3beta1, CD151/alpha6beta1) under conditions disrupting tetraspan interactions.

The tetraspans are molecules with four transmembrane domains which are engaged in multimolecular complexes (the tetraspan web) containing a subset of beta1 integrins (in particular alpha3beta1, alpha4beta1 and alpha6beta1), MHC antigens and several unidentified molecules. The molecules associated with tetraspans are readily detected after immunoprecipitation performed in mild detergents such as Brij 97 or CHAPS. In this study we show that another classical mild detergent, digitonin, dissociated most of these associated molecules, including integrins, from the tetraspans CD9, CD37, CD53, CD63, CD82, Co-029, Talla-1 and NAG-2. In contrast, reciprocal immunoprecipitations from various cell lines demonstrated that two other tetraspans, CD81 and CD151, formed complexes with integrins not disrupted by digitonin. These complexes were CD81/alpha4beta1, CD151/alpha3beta1 and CD151/alpha6beta1. Furthermore, a new anti-CD151 monoclonal antibody (mAb), TS151r, was shown to have a restricted pattern of expression, inversely related to the sum of the levels of expression of alpha6beta1 and alpha3beta1. This mAb was unable to co-precipitate integrins in digitonin, suggesting that its epitope is blocked by the association with integrins. Indeed, the binding of TS151r to the cell surface was quantitatively diminished following alpha3beta1 overexpression. Altogether, these data suggest that, among tetraspans, CD81 interacts directly with the integrin alpha4beta1, and CD151 interacts directly with integrins alpha3beta1 and alpha6beta1. Because all tetraspan-tetraspan associations are disrupted by digitonin, it is likely that the other tetraspans interact indirectly with integrins, through interactions with CD81 or CD151.

Animals↗
PubMed1999

Vancomycin concentration in the vitreous after intravenous and intravitreal administration for postoperative endophthalmitis.

OBJECTIVES: To measure the concentrations of vancomycin in the vitreous of patients with postoperative endophthalmitis after administration of 1 g of vancomycin hydrochloride intravenously and injection of 1 mg of vancomycin hydrochloride into the vitreous, and to determine whether these concentrations are adequate for treatment of gram-positive infections. METHODS: Patients with acute postoperative endophthalmitis were treated with intravenous administration of 1 g of vancomycin hydrochloride followed by vitrectomy and collection of vitreous samples 1 to 5 hours later. Intravitreal vancomycin and ceftazidime were given. Vitreous samples were cultured and their vancomycin concentrations assayed. Minimal inhibitory concentrations of vancomycin for the isolated vitreal pathogens, and serum and vitreous cidal activity were determined. RESULTS: Eighteen patients with acute postoperative endophthalmitis were studied. Fourteen vitreous samples were available after intravenous vancomycin administration, and 4 vitreous samples were available after intravitreal vancomycin administration. After intravenous injection, vitreous vancomycin concentrations ranged from 0.4 to 4.5 microg/mL. Minimal inhibitory concentrations in these samples, obtained from 10 bacterial isolates, were below the therapeutic levels for most causative organisms, including staphylococci. Vitreous cidal activity values were negative at a dilution of 1:2 in 9 of 10 patients examined. After a 1-mg intravitreal injection, vancomycin concentrations in vitreous samples obtained by a second tap from 4 patients 44 to 72 hours later were 182, 138, 58, and 25 microg/mL. In 2 patients in whom measurements were obtained, vitreous cidal activity values were 1:512 and 1:32. CONCLUSION: Vitreous vancomycin concentrations for the treatment of gram-positive endophthalmitis were nontherapeutic after intravenous administration but therapeutic after intravitreal administration.

Anti-Bacterial Agents↗
PubMed1999

Antimicrobial resistance--pharmacological solutions.

The interaction between microbial resistance and antibacterial agents occurs in a direct and an indirect fashion. Directly--through the development of resistance to the agent used, or to agents of the same class--as exemplified by the induction of beta-lactamase by both gram-positive and gram-negative bacteria. It also takes place through the development of resistance to compounds of different classes to the compound used, as exemplified by the loss of Streptococcus pneumoniae susceptibility to penicillin that is accompanied by a parallel loss of sensitivity to erythromycin and to tetracycline. As for the indirect way--microbial resistance may develop through selection of resistant organisms when the patient is treated with antibiotics, when the environment is contaminated with antibiotics (hospital) or when antibacterial agents are used in agriculture and animal husbandry.

Anti-Bacterial Agents↗
PubMed1999

The susceptibility of Streptococcus pneumoniae to levofloxacin and other antibiotics.

The aim of this study was to determine the in-vitro susceptibility of Streptococcus pneumoniae to levofloxacin, ciprofloxacin, sparfloxacin, ofloxacin, amoxycillin, cefepime and cefuroxime. In total, 105 isolates (clinical blood and sputum isolates from 1995-96) were selected from the collection of the Department of Clinical Microbiology of the Chaim Sheba Medical Centre. MICs were determined with an agar dilution method according to NCCLS guidelines. The MIC ranges with the test antibiotics against the pneumococcal isolates were: 0.5 mg/L, levofloxacin; 0.12-0.5 mg/L, sparfloxacin; 0.5-2 mg/L, ciprofloxacin; 0.5-1 mg/L, ofloxacin; < 0.03-2 mg/L, amoxycillin; < 0.03-2 mg/L, cefepime; < 0.03-2 mg/L, cefuroxime. The results indicated that although all isolates were susceptible to all the fluoroquinolone agents except ciprofloxacin, some isolates had reduced susceptibility to amoxycillin, cefepime and cefuroxime. We conclude that all S. pneumoniae isolates tested were susceptible to levofloxacin, ofloxacin and sparfloxacin. However, about 85% were susceptible to amoxycillin and the other beta-lactam antibiotics tested.

Anti-Bacterial Agents↗
PubMed1999

Safety and tolerability of quinupristin/dalfopristin: administration guidelines.

The safety and tolerability of quinupristin/dalfopristin were assessed in both comparative and non-comparative trials (2298 quinupristin/dalfopristin-treated patients). In comparative clinical trials, the most frequent systemic adverse events related to quinupristin/dalfopristin were nausea (4.6%), diarrhoea (2.7%), vomiting (2.7%) and skin rash (2.5%). The comparator group showed similar rates, except that nausea was significantly more common (7.2%; P = 0.01). In non-comparative trials, arthralgia and myalgia were reported most frequently but were reversible upon treatment discontinuation. The renal, inner ear, cardiovascular and central nervous systems were not implicated as significant target organs for toxicity. The most frequent local adverse events related to infusion of quinupristin/dalfopristin were inflammation, pain, oedema, infusion site reaction and thrombophlebitis. Results of laboratory tests while on therapy were comparable for quinupristin/dalfopristin and comparator groups, except that increases in conjugated bilirubin of >5 x the upper limit of normal were reported in 5.5% of quinupristin/dalfopristin recipients; increases in total bilirubin of >5 x the upper limit of normal occurred in 1.5%. Comparator recipients more frequently had increases in alanine aminotransferase and alkaline phosphatase. Quinupristin/dalfopristin inhibits the cytochrome P450 3A4-mediated metabolism of drugs including midazolam, nifedipine, terfenadine and cyclosporin. Therefore, plasma drug monitoring and/or dosage reduction of these agents is prudent. Concomitant administration of drugs that can prolong the electrocardiographic QTc interval should be avoided. Quinupristin/dalfopristin is visually and chemically compatible with commonly used drugs of various classes, but it is not compatible with sodium chloride solution and certain other drugs, including some antimicrobials. Therefore, when prescribing quinupristin/dalfopristin, clinicians should be aware of the potential for peripheral venous intolerance, arthralgias and myalgias, increases in conjugated bilirubin, interactions with drugs metabolized by the cytochrome P450 3A4 isoenzyme and certain physico-chemical incompatibilities. However, multiple studies have shown that the safety and tolerability of quinupristin/dalfopristin are generally favourable, and that it provides clear benefits to ill patients with severe gram-positive infections.

Anti-Bacterial Agents↗
PubMed1998

CD19 is linked to the integrin-associated tetraspans CD9, CD81, and CD82.

The CD19-CD21-CD81 complex regulates signal transduction events critical for B lymphocyte development and humoral immunity. CD81, a molecule with 4 transmembrane domains, member of the tetraspan superfamily, is engaged, together with other tetraspans such as CD9, CD53, CD63, and CD82, in multimolecular complexes containing beta1 integrins and major histocompatibility complex antigens. Here we demonstrate that two other tetraspans, CD82 and the early B cell marker CD9, are coimmunoprecipitated with CD19 from Brij97 lysates of B cell lines. Moreover, CD9 was coprecipitated from lysates of purified CD10(+) early B cells. These associations were confirmed by the cocapping of CD19 with CD9 or CD82. The CD9/CD19 association was disrupted in the presence of digitonin, contrary to the CD81/CD19 association, indicating that CD9 and CD81 interact with CD19 in different ways. The CD9/CD81 association is also disrupted in the presence of digitonin, suggesting that CD9 associates with CD19 only through CD81. To characterize the regions involved in the CD81/CD19 association, two reciprocal CD9/CD81 chimeric molecules were tested for the association with CD19, but none of them could be coprecipitated with CD19 in digitonin, indicating that the domain of CD81 responsible for its association with CD19 is complex. Finally, engagement of CD9 could induce the tyrosine phosphorylation of different proteins, including CD19 itself, suggesting that the CD9/CD19 association is functionally relevant. Thus, a physical and functional link is formed between the CD19-CD21-CD81 complex and the integrin-tetraspan complexes, which is dynamically modulated in the process of B cell differentiation.

Animals↗