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R A Weiss

Publications and source records attributed to R A Weiss.

At least 181 records · Page 10Linked to original sources
PubMed1993

Human saphenous vein in vitro model for studying the action of sclerosing solutions.

BACKGROUND: Previous studies detailing the clinical and histologic effects of sclerosing solutions in rabbit ear and other animal vein models have provided information comparing the effects of various concentrations of hypertonic saline with and without dextrose (Sclerodex), polidocanol, scleremo (chromated glycerin), and sodium tetradecyl sulfate. OBJECTIVE: To observe short-term histologic changes of sclerosing solutions in vitro in large diameter human vein. METHODS: Human saphenous vein segments were obtained following cardiac bypass procedures. Several types of sclerosing solutions, including 23.4% hypertonic saline, 1% polidocanol, and 3% sodium tetradecyl sulfate, were allowed continuous contact with the vessel wall for 10 minutes. Test vein segments were immediately fixed and observed for histologic changes compared with normal saline controls. RESULTS: Endothelium was rapidly destroyed by all tested sclerosing solutions. Vessel wall necrosis occurred quickly with the extent determined by the sclerosing solution. Destructive potential of 3% sodium tetradecyl sulfate greatly exceeded that of 23.4% hypertonic saline or 1% polidocanol, in agreement with previous animal studies. CONCLUSION: Direct toxic effects of sclerosing agents may be compared in a constant, reproducible environment with this in vitro model.

Endothelium, Vascular↗
PubMed1993

Mutation of amino acids within the gibbon ape leukemia virus (GALV) receptor differentially affects feline leukemia virus subgroup B, simian sarcoma-associated virus, and GALV infections.

The three type C retroviruses, gibbon ape leukemia virus (GALV), simian sarcoma-associated virus (SSAV), and feline leukemia virus subgroup B (FeLV-B), infect human cells by interacting with the same cell surface receptor, GLVR1. Using LacZ retroviral pseudotypes and murine cells transfected with mutant GLVR1 expression vectors, we show that the same 9-amino-acid region of human GLVR1 is critical for infection by the three viruses. Rat cells were not susceptible to infection by LacZ (FeLV-B) pseudotypes because of a block at the receptor level. We found multiple amino acid differences from human GLVR1 in the 9-amino-acid critical region of rat GLVR1. Expression of a human-rat chimeric GLVR1 in murine cells demonstrated that rat GLVR1 could function as a receptor for GALV and SSAV but not for FeLV-B. Substitution of human GLVR1 amino acids in the critical region of rat GLVR1 identified three amino acids as responsible for resistance to FeLV-B infection; two of these affect SSAV infection, but none affects GALV infection.

Amino Acid Sequence↗
PubMed1993

A single amino acid substitution in the V1 loop of human immunodeficiency virus type 1 gp120 alters cellular tropism.

Specific point mutations which affect viral tropism have been identified in both the V3 loop and in the CD4-binding region of the human immunodeficiency virus type 1 surface glycoprotein gp120. Here we report that a single point mutation in the first variable region (V1) of human immunodeficiency virus type 1 strain JRCSF is responsible for a change in viral tropism.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Mask Performance Rating Table for specific military tasks.

The Performance Rating Table (PRT) is introduced as a means to separate mask-wearer performance by causative factors. The PRT shows which mask factors require design attention and how the mask affects different users.

Adaptation, Physiological↗
PubMed1993

Evaluation of the venous system by Doppler ultrasound and photoplethysmography or light reflection rheography before sclerotherapy.

Transmission of high pressure, from deep to superficial venous system of the leg, often causes varicosis of superficial veins. High-pressure transmission frequently occurs through reverse flow or leakage through malfunctioning valves. Therefore, the goal of varicose or telangiectatic vein treatment to stop the leak or reflux at its origin by eliminating vein segments with faulty valves. Noninvasive diagnostic tests such as Doppler ultrasound allow reflux sites to be identified and targeted before treatment. Doppler ultrasound permits assessment of competence of the sapheno-femoral junctions and lesser saphenous-popliteal vein junctions bilaterally and detection of points of reflux through suspected incompetent perforating veins in the thigh, calf, and ankle. Photoplethysmography (PPG), or light reflection rheography (LRR), offers a simple, reproducible technique for physiologic evaluation of the effectiveness of the calf muscle pump and quantification of the degree of venous insufficiency as well as differentiation between superficial and deep venous insufficiency. A combination of Doppler ultrasound and PPG/LRR readily identifies those patients who may derive a medical benefit from treatment of a physiologically abnormal venous system. The presence of reflux by Doppler is indicative of a venous problem that is more than cosmetic. Treatment may consist of sclerotherapy alone or a combination of surgical ligation of an incompetent sapheno-femoral junction followed by sclerotherapy.

Evaluation Studies as Topic↗
PubMed1992

Retroviral pseudotypes produced by rescue of a Moloney murine leukemia virus vector by C-type, but not D-type, retroviruses.

Human HOS cells containing a Moloney murine leukemia virus (Mo-MLV) recombinant genome were infected by a panel of retroviruses. The C-type viruses simian sarcoma associated virus, feline leukemia virus subgroup B, and the feline endogenous virus RD114 were able to form pseudotypes with the Mo-MLV genome, which transferred a selectable marker gene to target cells; however, Human T cell leukemia virus-1 and the D-type viruses Mason-Pfizer monkey virus and simian retrovirus-1 failed to rescue the Mo-MLV vector. Further characterization of the RD114 pseudotype demonstrated that it retained the receptor specificity of RD114 and will therefore prove useful in receptor characterization.

Animals↗
PubMed1992

CPF-DD is an inhibitor of infection by human immunodeficiency virus and other enveloped viruses in vitro.

The initial step in the infection cycle of human immunodeficiency virus type 1 (HIV-1) involves binding of its surface glycoprotein gp 120 to the T lymphocyte CD4 antigen. CPF-DD is a low molecular weight inhibitor of HIV infectivity that inhibits gp 120 binding to CD4 in vitro (Finberg et al., Science 249, 287-291, 1990). We find, however, that the actions of CPF-DD are not limited to its ability to interfere with gp 120-CD4 binding; its predominant action is to remove the viral envelope from the underlying core. Subsequently the virions disintegrate. Most enveloped viruses tested were inhibited by CPF-DD, but the infectivity of noneneloped viruses was unaffected or only slightly reduced.

Animals↗
PubMed1992

Amino acid residues of the human immunodeficiency virus type I gp120 critical for the binding of rat and human neutralizing antibodies that block the gp120-sCD4 interaction.

We have characterized the discontinuous epitopes recognized by two rat and three human neutralizing monoclonal antibodies (mAb) by examining the effect of single amino acid changes in conserved residues of gp120 on mAb recognition. A human mAb derived from an infected individual, 448D, and two rat mAbs, 39.13g and 39.3b, respectively, derived by immunization with native recombinant gp120, recognize similar epitopes. Recognition of the envelope glycoproteins by these mAbs was affected by changes in gp120 amino acid residues 88, 113, 117, 257, 368, or 370. The gp120 amino acids 257, 368, and 370 have previously been reported to be important for CD4 binding, which is consistent with the ability of these mAbs to block the gp120-CD4 interaction. Residues 88, 113, and 117 are not thought to be important for CD4 binding, suggesting that the antibody epitopes overlap, but are distinct from, the CD4 binding region. We also found that some alterations in gp120 residues 88, 117, 368, or 421 reduced the ability of polyclonal sera from HIV-1-infected individuals to inhibit the interaction of the mutant gp120 glycoproteins with soluble CD4. Thus, changes in the HIV-1 gp120 glycoprotein that minimally affect the receptor binding may allow escape from neutralizing antibodies directed against the CD4 binding region.

Amino Acids↗
PubMed1992

Variations in practice among urologists and nephrologists treating children with vesicoureteral reflux.

To analyze the current management recommendations among physicians treating children with vesicoureteral reflux, the American Urological Association Reflux Practice Guidelines Panel surveyed 100 pediatric urologists, 100 general urologists and 100 pediatric nephrologists by questionnaire, and received a 60% response. In the evaluation of a 4-year-old girl with bilateral grade 2 reflux general urologists were more likely than the other 2 groups to recommend cystoscopy and urethral dilation. At followup nuclear cystography was recommended by 76% of pediatric urologists, 48% of general urologists and 71% of pediatric nephrologists, while the latter 2 groups were less likely to recommend any subsequent upper tract evaluation. Pediatric urologists were significantly more likely to recommend antireflux surgery if the child had 1 breakthrough febrile urinary tract infection, poor compliance with medical management or persistent reflux at age 11 years. In a 6-year-old girl with unilateral grade 4 reflux and detrusor instability 44% of pediatric urologists recommended antimicrobial prophylaxis and anticholinergic therapy compared to 12% of general urologists and 6% of pediatric nephrologists. Antireflux surgery was recommended by 29% of pediatric urologists, 60% of general urologists and 59% of pediatric nephrologists. In older girls with persistent grade 2 or 3 reflux pediatric urologists were much more likely to recommend antireflux surgery. In contrast, they were less likely to recommend surgery in young girls and boys with newly diagnosed grade 4 reflux. These data demonstrate significant differences in therapeutic recommendations among pediatric urologists, general urologists and pediatric nephrologists, and suggest the need for outcomes research to determine the optimal management of children with vesicoureteral reflux.

Child↗
PubMed1992

Respirator performance rating table for mask design.

The ultimate goal for respirator mask designers is computer-aided design. Mask design, however, is a very complex operation, with many different interrelationships. Current knowledge does not allow significant incorporation of physiological information into mask design. Rather, physiological information is usually gathered during mask evaluation, after the design process has been completed. The Performance Rating Table (PRT) is a beginning step to formulating physiological knowledge in a way that can be useful for design. The PRT organizes physiological knowledge to assign performance data to various mask and level of work causes. Best estimates of tabled values were obtained from the literature.

Body Temperature Regulation↗
PubMed1992

Respirator performance rating tables for nontemperate environments.

Respirator performance rating tables have been constructed for hot, humid (29 degrees C, 95% RH); hot, dry (49 degrees C, 30% RH); and cold, dry (-32 degrees C, 70% RH) conditions. These tables convey expected wearer performance percentages compared to unmasked workers for various mask elements and work rates. The hot, humid condition was found to be the most severe overall. Many table entries approach 100%, thus leading to difficulties in correcting mask deficiencies.

Equipment Design↗
PubMed1992

Conserved structural features in the interaction between retroviral surface and transmembrane glycoproteins?

Among the retroviruses, the surface (SU) and transmembrane (TM) glycoproteins of lentiviruses are linked exclusively by noncovalent bonds. For some C-type retroviruses, however, a small proportion of the SU proteins has been shown to be linked to their TM proteins by a disulfide bond, with the remainder being noncovalently associated. A region near the carboxyl terminus of the HIV-1 SU glycoprotein has been implicated in contacting the TM glycoprotein. Computer modelling indicates that this region of divergent lentivirus and oncovirus SU glycoproteins forms a structurally conserved "pocket" which could accommodate a "knob"-like protrusion formed by an immunodominant region in the TM protein containing the CxxxxxC (lentiviruses) or CxxxxxxCC (C- and D-type viruses) motif. An anti-idiotypic monoclonal antibody, raised against a monoclonal antibody reacting with a sequence in the "pocket" of HIV-1 gp120, was found to bind to synthetic peptides close to the CxxxxxC motif. It is suggested that part of the SU-TM linkage mechanism for the lentiviruses and oncoviruses is a 'knob and socket' structure and that the interaction between SU and TM proteins is similar in one region for lentiviruses and C-type as well as D-type viruses. The conserved knob and socket linkage may be relevant to a mechanism for viral-cell membrane fusion that is broadly common to all of these retroviruses.

Amino Acid Sequence↗
PubMed1992

Investigations into the mechanism by which sulfated polysaccharides inhibit HIV infection in vitro.

Sulfated polysaccharides have been shown to inhibit human immunodeficiency virus (HIV) infection in vitro. Dextrin sulfate, fucoidan, and dextran sulfate fail to neutralize virions directly, but interact with target cells to inhibit virus entry. Ionic interactions of sulfated polyanions with oppositely charged cell surface components, including CD4, have been assumed to be the inhibitory mechanism. It is shown that the sulfated polysaccharides inhibit infection of both CD4+ and CD4- cell lines by HIV and also that they inhibit HTLV-1 and, to a lesser extent, the simian retrovirus, MPMV, which use receptors other than CD4. One binding site for radiolabeled fucoidan on the surface of human T cells is an 18 kD protein, but its significance is not yet clear.

Antiviral Agents↗
PubMed1992

Monoclonal antibodies to the C4 region of human immunodeficiency virus type 1 gp120: use in topological analysis of a CD4 binding site.

We have raised antisera and monoclonal antibodies (MAbs) to the C4 region of HIV-1 gp120, using an antigen chimaera of poliovirus as immunogen. These MAbs and sera, together with MAbs to the same region raised by other methods, fall into three groups defined by their abilities to bind to recombinant gp120 and/or the immunogenic peptide. In some cases, the amino acids recognized by the MAbs have been identified by pep-scan and by solution phase peptide inhibition of binding to recombinant gp120. Our results indicate that the amino acids WQEVGKAMYA are exposed on the surface of recombinant gp120. Antibodies to these amino acids on recombinant gp120 compete for soluble CD4 binding in vitro, but only weakly neutralize HIV.

Amino Acid Sequence↗
PubMed1992

Development of HIV-1 group-specific neutralizing antibodies after seroconversion.

OBJECTIVE: To study the induction of group-specific (gs) neutralizing antibodies to HIV-1 after seroconversion. DESIGN AND METHODS: Serum samples taken sequentially from seven Dutch homosexual men and four British haemophiliacs (anonymous sample, therefore sex not known) before and after seroconversion were tested for neutralizing antibodies effective against five diverse HIV-1 strains. Strains of HIV-1 tested included isolates from the United States, Europe and Africa. RESULTS: The gs neutralizing antibody response varied between individuals. Only five of the 11 individuals studied produced detectable neutralizing antibodies to laboratory-adapted HIV-1 strains (for example, IIIB) within 32 weeks of seroconversion. Most individuals initially produced antibodies effective against US/European isolates; the response then generally broadened to include the more diverse strains, i.e., African. CONCLUSIONS: These results suggest that the gs neutralizing target for HIV-1 is poorly immunogenic in vivo and is probably not highly conserved among diverse HIV-1 strains.

HIV Antibodies↗
PubMed1992

Physicians' negative perception of sclerotherapy for venous disorders: review of a 7-year experience with modern sclerotherapy.

Sclerotherapy is the injection of a sclerosing substance directly into a varicosity or telangiectasia to cause damage, fibrosis, and eventual obliteration of the vessel. Although sclerotherapy has been shown to be effective with a low incidence of side effects, many physicians in the United States are unaware of the technique or view it in a negative way. To better define the extent of physician unfamiliarity or prejudice toward sclerotherapy, we surveyed a local medical community of gynecologists by anonymous written questionnaire. The results indicated that 82% of the responding physicians believed that their knowledge of sclerotherapy was insufficient to advise their patients, leaving patients to learn about sclerotherapy from mass media sources. Sclerotherapy was perceived as only slightly effective therapy for varicose veins and was thought to have a relatively high incidence of side effects. With recent improvements in the technique, our collaborative experience with 3000 patients receiving 50,000 injections over the past 5 years has shown that sclerotherapy is a safe procedure achieving outstanding cosmetic results with concomitant symptomatic relief of painful varicosities and telangiectases. Sclerotherapy, as practiced today, offers an effective, simple, and less costly alternative to surgical stripping for most varicose and telangiectatic veins. The survey data demonstrate the need to educate the American medical community about the technique and merits of modern sclerotherapy so that patients may be properly guided by their physicians to the best sources of care for their aching and unsightly leg veins.

Adolescent↗