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Biomedical subjects

R Weiss

Publications and source records attributed to R Weiss.

At least 37 records · Page 2Linked to original sources
PubMed1993

Is CD4 sufficient for HIV entry? Cell surface molecules involved in HIV infection.

HIV-1, HIV-2 and SIV each bind to CD4 as the first step in virus entry. However, alternative receptors may also be used. HIV-1 binds to glycolipids with terminal galactosylceramide residues on neural cells; opsonized virus binds to Fc receptors; HIV-2 can infect certain CD4-negative cells. Further receptors may also play a role in CD4-mediated infection, including cell adhesion molecules and possibly cell surface proteinases. After binding to CD4, immunodeficiency viruses require secondary molecules to effect fusion between the virus envelope and the cell membrane; these accessory requirements differ between HIV-1, HIV-2 and SIV.

Animals↗
PubMed1993

Line scanning system for direct digital chemiluminescence imaging of DNA sequencing blots.

A cryogenically cooled charge-coupled device (CCD) camera equipped with an area CCD array is used in a line scanning system for low-light-level imaging of chemiluminescent DNA sequencing blots. Operating the CCD camera in time-delayed integration (TDI) mode results in continuous data acquisition independent of the length of the CCD array. Scanning is possible with a resolution of 1.4 line pairs/mm at the 50% level of the modulation transfer function. High-sensitivity, low-light-level scanning of chemiluminescent direct-transfer electrophoresis (DTE) DNA sequencing blots is shown. The detection of DNA fragments on the blot involves DNA-DNA hybridization with oligonucleotide-alkaline phosphatase conjugate and 1,2-dioxetane-based chemiluminescence. The width of the scan allows the recording of up to four sequencing reactions (16 lanes) on one scan. The scan speed of 52 cm/h used for the sequencing blots corresponds to a data acquisition rate of 384 pixels/s. The chemiluminescence detection limit on the scanned images is 3.9 x 10(-18) mol of plasmid DNA. A conditional median filter is described to remove spikes caused by cosmic ray events from the CCD images.

Alkaline Phosphatase↗
PubMed1993

[Primary care consultation rates among the middle aged and elderly].

The consultation rate among family physicians has been widely discussed in the literature, but very few studies have been done in Israel. We analyzed the pattern of visits to the family physician of 1,860 patients aged 40 years and older in 3 urban clinics, 2 kibbutzim and 1 rural clinic with a total population of 6,700. The consultation rate rose steadily with age. It was 3.4 per year at age 40-49, and 5.6 at ages 70 and over, with a mean annual rate of 4.6. 77% of the screened population consulted the physician in 1 year and 91.4% in 3 years. Only 9.6% did not visit their physicians in the 3 years. About two-thirds visited the physician 1-4 times a year, and only 2% visited more than 15 times. In urban practices women attended more often than men but there was no significant sex difference in the rural practices. As a result of the greater visit rates of the elderly, they consumed a larger share of medical services. The mean consultation rate in this survey is similar to that in England and in other Western countries. However, it is relatively low in comparison to other studies in Israel. This may be due to the different practice setting and the use of a different sampling frame.

Adult↗
PubMed1993

Transcomplementation of VIF- HIV-1 mutants in CEM cells suggests that VIF affects late steps of the viral life cycle.

The vif gene of HIV-1 has previously been claimed to be essential for the ability of cell-free virus preparations to infect cells. Here we report that the CEM T-cell-line, stably transfected with and expressing vif, supports the replication of vif- HIV-1 viruses to the same extent as wild-type HIV1. Cell entry and early replication stages are the same for vif- and vif+ HIV-1 passaged in CEM, as measured both by a PCR-based cell entry assay and by fusogenic potential. These findings indicate that vif does not affect viral infectivity on CEM cells, but seems to act at a later stage of virus replication/maturation. We also show that the VIF proteins of two different HIV-1 strains can transcomplement different vif- HIV-1 mutants.

Cell Line↗
PubMed1993

Effects of interleukin-1 and interleukin-6 on metallothionein and amyloid precursor protein expression in human neuroblastoma cells. Evidence that interleukin-6 possibly acts via a receptor different from the 80-kDa interleukin-6 receptor.

Since immunohistochemical studies indicated the presence of interleukin-6 in the cortices of patients with Alzheimer's disease, we were interested in the eventual biological effects of this cytokine on neuronal cells. We found that interleukin-6 and interleukin-1 induced metallothionein expression in a human neuronal (SH-SY5Y neuroblastoma) cell line. In contrast to metallothionein, amyloid precursor protein expression was unaffected by both cytokines. When searching in the same cell line for the expression of the classical 80-kDa interleukin-6 binding protein, which is part of the dimeric interleukin-6 receptor, we were unable to detect the respective mRNA. Our findings either indicate that the interleukin-6 receptor in these cells is expressed in extremely low levels or that interleukin-6 may act upon neuronal cells via a different, yet unknown neuronal receptor.

Amyloid beta-Protein Precursor↗
PubMed1993

Enzootic Mycobacterium avium infection in captive Parma wallabies (Macropus parma) with unusual spinal cord manifestations.

Pathological, microbiological and clinical findings in Parma wallabies (Macropus parma) with an enzootic infection caused by Mycobacterium avium are described. Disorders of locomotion resulted from granulomatous myelitis, meningitis and radiculitis in the lumbosacral spinal cord. Lesions found in a number of internal organs suggested protracted systemic infection due to an alimentary or airborne infection with Mycobacterium avium. This organism was isolated and identified by methods that included microbiological examinations, based on microscopy, culture, in-vitro tests, animal inoculation, polymerase chain reaction and cycle sequencing.

Animals↗
PubMed1993

Interscalene block for shoulder arthroscopy: comparison with general anesthesia.

Arthroscopic shoulder surgery can be performed under regional or general anesthesia. The objective of this study was to demonstrate that regional anesthesia has several benefits over general anesthesia for this type of surgery, particularly in the ambulatory patient. Forty patients received general anesthesia and 63 an interscalene block. The regional block was found to be safe and effective, with a high degree of patient acceptance. It provided excellent intraoperative analgesia and muscle relaxation. Postoperatively, regional anesthesia resulted in fewer side effects, fewer hospital admissions, and a shorter hospital stay than did general anesthesia.

Adolescent↗
PubMed1993

Characteristics of registered clinic patients who have not visited their family physician for 3 years.

The objective of this study was to obtain and critically evaluate data on the health characteristics and the need for medical assistance in patients aged 40 years and over, from six urban and rural medical practices in northern Israel, who have not consulted their family physician for at least 3 years. A health questionnaire was completed by means of telephone calls and personal contacts, regarding 139 non-visitors (out of 1847 patients aged 40 and over). The health characteristics and prevalence of medical and social problems were compared to regular clinic attenders. Questionnaires of 101 non-attenders were completed for a response rate of 73% (101/139). The non-attendance rate was 7.5% (139/1847) and there was a low rate of morbidity. The majority (81%) were 40-59 years old and only 16% had had previous illnesses. Only 10% took medications regularly, most of them medical personnel. Twenty-eight of the non-attenders were employees of the regional health care system. Most of these individuals coped with chronic illnesses by consulting the regional hospital's outpatient clinics. Non-attenders could be characterized as less prone to health problems. Most of them seemed remarkably fit and were not suffering unduly as a result of their lack of medical attention.

Adult↗
PubMed1993

The nephritogenic immune response.

An emerging viewpoint states that localization of antibodies, T cells, and macrophages within the kidney occurs through specific receptor-mediated interactions to initiate nephritis. The initial events involve loss of tolerance with activation of autoreactive B cells, autoreactive T cells, or both. Many pathogenic autoantibodies form immune deposits either by binding directly to renal antigens or by complexing with endogenous antigens with affinity for renal antigens. Autoreactive T-cell infiltration requires both the presence of specific antigens and costimulatory factors expressed by cells capable of antigen presentation. It is particularly noteworthy that some of the antigen targets of the nephritogenic immune response involve either cell surface molecules or matrix components with functional properties, raising the possibility that ligation of these components could serve to modulate the local inflammatory response. Furthermore, specific perturbations within endogenous cells, resulting directly from these interactions, probably influence subsequent inflammatory-fibrogenic events. In this review, we focus on recent work relating to the loss of tolerance leading to the emergence of autoreactive B and T lymphocytes; specific autoantibody and T-cell interactions within the kidney; and the active participation of endogenous cells in the initiation of the nephritogenic response.

Animals↗
PubMed1993

Effectiveness, safety, and acceptability of a copper intrauterine device (CU Safe 300) in type I diabetic women.

OBJECTIVE: To evaluate the long-term effectiveness and safety of a copper intrauterine device fulfilling modern standards in type I diabetic women compared with nondiabetic women. RESEARCH DESIGN AND METHODS: Type I diabetic women (n = 59, age 27 +/- 5 yr, duration of diabetes 12 +/- 8 yr, HbA1c 7.0 +/- 1.2%, 78% nulliparous women) were prospectively evaluated at 3, 6, 12, 24, and 36 mo by a gynecological exam and a standardized questionnaire after insertion of the intrauterine device (CU Safe 300, 300 mm2 of copper). A group of nondiabetic women (n = 1150) of comparable age and parity evaluated according to the same study protocol served as a control group. RESULTS: In the diabetic women (1754 cumulative months of use), events leading to termination of the intrauterine device during the 1st yr (691 women-mo) were one accidental pregnancy, one expulsion, one removal for pain, two removals for bleeding, and one removal for planned pregnancy. Events during the 2nd (593 women-mo) and 3rd yr (470 women-mo) were zero and one accidental pregnancy., one and two removals for bleeding, one and one removal for pain, one and one removal for other medical reasons, and two and two removals for planned pregnancy, respectively. No case of pelvic inflammatory disease was diagnosed in the diabetic group, and one case was diagnosed in the nondiabetic group (28,369 mo of cumulative use). Events leading to termination of the intrauterine device per women observed per year and continuation with the intrauterine device after each year of use were comparable in the diabetic and nondiabetic groups for the 1st, 2nd, and 3rd yr. CONCLUSIONS: These results, although preliminary because < 100 diabetic women were studied, indicate that the intrauterine device CU Safe 300 is as effective, safe, and well-tolerated in diabetic as in nondiabetic women. Specific objections to the use of intrauterine devices in type I diabetic women do not seem to be justified for modern, copper-mediated models.

Adolescent↗
PubMed1993

[The use of nonpathogenic leptospira as diagnostic antigens for the diagnosis of leptospira infections in cattle].

The seroprevalence of leptospira antibodies was determined in 4377 bovine sera by microagglutination assay using 11 Leptospira interrogans serovars. In 10% (439 samples) of the sera, a positive reaction was detected. These included 275 sera (62.6%) with reaction to L. grippotyphosa, 159 (36.2%) to L. saxkoebing and 5 (1.1%) sera with reactions to other serovars. Multiple reactions were found in 9.8% of the 439 positive sera, whereby the Sejroe group dominated (65%) within the possible combinations of crossreactions. To determine the suitability of nonpathogenic strains as polyvalent diagnostic antigens, two L. biflexa serovar patoc strains were compared with the above-mentioned 11 L. interrogans serovars in microagglutination testing of 1995 screen sera. The sensitivity of the test was found to be 0.3% and the specificity was 80.3%. Using the two L. patoc strains, all of the 415 positive field sera and 11 positive control sera yielded negative reactions. Based on these results, the use of L. biflexa serovar patoc cannot be recommended as polyvalent antigen in the diagnosis of bovine leptospirosis by microagglutination.

Agglutination Tests↗
PubMed1992

Digital chemiluminescence imaging of DNA sequencing blots using a charge-coupled device camera.

Digital chemiluminescence imaging with a cryogenically cooled charge-coupled device (CCD) camera is used to visualize DNA sequencing fragments covalently bound to a blotting membrane. The detection is based on DNA hybridization with an alkaline phosphatase(AP) labeled oligodeoxyribonucleotide probe and AP triggered chemiluminescence of the substrate 3-(2'-spiro-adamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl- 1,2-dioxetane (AMPPD). The detection using a direct AP-oligonucleotide conjugate is compared to the secondary detection of biotinylated oligonucleotides with respect to their sensitivity and nonspecific binding to the nylon membrane by quantitative imaging. Using the direct oligonucleotide-AP conjugate as a hybridization probe, sub-attomol (0.5 pg of 2.7 kb pUC plasmid DNA) quantities of membrane bound DNA are detectable with 30 min CCD exposures. Detection using the biotinylated probe in combination with streptavidin-AP was found to be background limited by nonspecific binding of streptavidin-AP and the oligo(biotin-11-dUTP) label in equal proportions. In contrast, the nonspecific background of AP-labeled oligonucleotide is indistinguishable from that seen with 5'-32P-label, in that respect making AP an ideal enzymatic label. The effect of hybridization time, probe concentration, and presence of luminescence enhancers on the detection of plasmid DNA were investigated.

Adamantane↗
PubMed1992

[Comparative plasmid profile analysis of Salmonella typhimurium var. Copenhagen strains from a Salmonella outbreak in hospitalized horses].

From April 1990 through June 1991 clinical salmonellosis and asymptomatic faecal excretion of Salmonella spp. were seen in hospitalized horses at two veterinary hospitals. 76 Salmonella strains from hospitalized horses and 18 strains from horses without any clinical contact were characterized by serotyping and plasmid profile analysis. From April 1990 through January 1991 97.8% of the hospitalized horses were infected with strains of S. typhimurium var. Copenhagen, which were closely related according to their similar plasmid patterns. Other strains of S. typhimurium var. Copenhagen and serotype S. enteritidis were isolated not before February 1991. In the same period various plasmid profile types of S. typhimurium var. Copenhagen and strains of S. typhimurium, S. enteritidis and S. lexington were isolated from horses of the control group. Our results suggest that the high incidence of salmonellosis and latent salmonella infection in hospitalized horses was mainly due to the spread of one particular strain of S. typhimurium var. Copenhagen and that this strain was obviously acquired during hospitalisation.

Animals↗