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Biomedical subjects

B J Cohen

Publications and source records attributed to B J Cohen.

At least 19 recordsLinked to original sources
PubMed1992

DecisionNET: database/network support for clinical decision analysts.

DecisionNET is a proposed remote database/wide-area computer network that should cultivate quantitative approaches to medicine by providing rapid access to medical facts, literature citations, decision models, and commentary of specific use to those involved with quantitative clinical decision making. Increasing accessibility to data and providing a forum for exchange of ideas should prove to be a significant asset to clinicians, either as modelers or as clients. Further work will address specific database implementation, development of a query engine, and coordination of the communications infrastructure. DecisionNET provides a unique model for the growth and maintenance of other medical knowledge bases.

Archives↗
PubMed1992

Transient aplastic crisis in patients with sickle cell disease. B19 parvovirus studies during a 7-year period.

OBJECTIVE: To determine (1) the proportion of cases of transient aplastic crisis (TAC) in patients with sickle cell disease due to B19 parvovirus infection in several years, (2) longitudinally, the immune response to B19 parvovirus infection, and (3) whether patients with sickle cell disease experience recurrent or chronic B19 parvovirus infection. DESIGN: Prospective evaluation of patients with sickle cell disease and TAC to find evidence of B19 parvovirus infection and, if present, to document the pattern of serologic response with time. SETTING: Large urban teaching hospital. PATIENTS: Patients younger than 18 years with sickle cell disease who were admitted to the hospital with a diagnosis of TAC or who developed TAC while in the hospital for other reasons. Follow-up serologic studies of B19 parvovirus infection were done in eight patients. MEASUREMENTS/MAIN RESULTS: Serum was tested for B19 parvovirus DNA/viral particles and specific anti-B19 parvovirus IgM and IgG antibodies. B19 parvovirus DNA/viral particles were detected in 11 (21%) of 53 patients with TAC. Specific anti-B19 parvovirus IgM antibodies were detected in 34 (64%) of the 53 patients. Overall, 36 (68%) of 53 patients with TAC had evidence of acute B19 parvovirus infection as shown by the detection of B19 DNA parvovirus and/or specific anti-B19 parvovirus IgM antibodies in acute-phase serum. Follow-up serologic studies in eight patients with acute infection revealed disappearance of B19 parvovirus DNA/viral particles and anti-B19 parvovirus IgM antibodies and persistence of anti-B19 parvovirus IgG antibodies for up to 3 1/2 years after the diagnosis of acute B19 parvovirus infection. No patient had evidence of recurrent or chronic B19 parvovirus infection. CONCLUSIONS: Approximately 70% of cases of TAC in patients with sickle cell disease identified in a 7-year period were caused by acute B19 parvovirus infection. Once detected, anti-B19 parvovirus IgG antibodies remain detectable for several years. There was no evidence of chronic or recurrent B19 parvovirus infection in patients with sickle cell disease.

Adolescent↗
PubMed1992

Haemagglutination by parvovirus B19.

Human parvovirus B19 is a member of the autonomous parvoviridae but in contrast to other members of the genus has not been shown to agglutinate red blood cells. We now report that the virus agglutinates red cells of primate origin, though with plasma-derived virus this activity is masked by the presence of an IgM-like inhibitor. This observation is consistent with the presence on the erythroid precursor target cell of a specific receptor for parvovirus B19.

Animals↗
PubMed1992

cAMP activates the sodium pump in cultured cells of the elasmobranch rectal gland.

The inorganic ion content of rectal gland cells cultured from Squalus acanthias was studied by electron probe analysis in order to determine the effect of stimulation by cAMP. Cell sodium was reduced by 30% (P less than 0.01) at 8 min after exposure to dibutyryl cAMP and theophylline and remained low at 25 and 33 min. Chloride content also fell significantly with stimulation. Although cAMP may activate several transport sites, the results are consistent with a direct effect of stimulation to increase the activity of the sodium pump in shark rectal gland.

Animals↗
PubMed1991

Detection of B19 parvovirus in human fetal tissues by in situ hybridisation.

Evidence of B19 parvovirus infection was sought by in situ hybridisation with biotinylated probes in 65 tissue samples from 32 pregnancies (fetuses, products of conception and/or placentas). Twenty-seven samples were reactive and the results were confirmed by other methods for B19 virus detection in 22 cases. The other methods used were in situ hybridisation with 3H and 35S labelled probes; dot-blot hybridisation with biotin and 32P labelled probes; polymerase chain reaction assay; negative stain and thin section electron microscopy; and radioimmunoassay for B19 antigen. The five false positive results by in situ hybridisation with biotinylated probes were considered to be due to non-specific biotin capture and were more frequent with unfixed samples than with formalin fixed material. It was concluded that while biotinylated probes offered advantages over radioactive probes for detecting B19 DNA by in situ hybridisation, positive findings should be confirmed by other methods.

Biotin↗
PubMed1991

Evaluation of a synthetic-peptide enzyme-linked immunosorbent assay for immunoglobulin M to human parvovirus B19.

A synthetic peptide corresponding to a part of the virus protein 1-virus protein 2 overlapping region of human parvovirus B19 was used in an indirect enzyme-linked immunosorbent assay. Antibodies of the immunoglobulin (Ig) M class were measured in serum samples from patients with erythema infectiosum and controls. In comparison with an IgM assay using native B19 viral antigen, the peptide antigen assay was 92% sensitive and 87% specific. B19 IgM reactivities were seen in a limited number of children with other viral diseases. Specific IgM reactivities to short synthetic viral peptides have previously been reported only with Epstein-Barr virus. Since other sources of viral antigen are limited, the peptide antigen assay may be a useful alternative for the diagnosis of B19-associated disease in human beings.

Amino Acid Sequence↗
PubMed1979

Fetal and placental responses to artificially induced hyperthermia in rats.

Pregnant rats were utilized to study the effect of maternal hyperthermia on fetal development. Eight groups of six to eight rats were exposed to ambient temperatures of 43-44 degrees C at various stages of pregnancy. All rats were killed on day 20 of gestation. Edema, microencephaly and microphthalmia followed heat treatment on day 4, 6, or 8 and skeletal defects occurred on day 10 of gestation. Apparently heat stress of dams after day 14 of gestation had little or no effect on embryos. Most placentas from day 6-10 treatment groups were significantly heavier than control and exhibited extensive thickening and necrosis of decidua basalis. Our results suggest that the rat is a useful model for investigating maternal hyperthermia as a possible cause of human placentophathies and fetal retardation.

Animals↗
PubMed1979

Chronic persistent hepatitis: hepatitis B virus markers and histological follow-up.

Twenty-six untreated patients with chronic persistent hepatitis were followed prospectively for one to 17 years (mean 5.6 years). The patients developed no clinical features of chronic liver disease. Raised serum transaminase levels were usually, but not consistently, the only biochemical abnormality; gamma globulin values were normal. Serum markers of past or present hepatitis B infection were found initially in 14 patients: another two developed markers during their follow-up. Nine patients progressed to a mild or moderate chronic active hepatitis as shown by serial needle liver biopsies but there was no evidence of cirrhosis. This progression was not associated with any clinical or biochemical deterioration. Seven of these patients had presented with insidious symptoms, seven had serum markers of hepatitis B infection, and the four who were HBsAg positive had relatively lower serum HBsAg concentrations than did those patients who continued with chronic persistent hepatitis.

Adult↗
PubMed1978

The IgM antibody responses to the core antigen of hepatitis B virus.

Little is known about the immunoglobulin class of antibodies to HBcAg. In the present study sera containing anti-HBc were fractionated by surcose density-gradient centrifugation, and all serum fractions were tested against HBcAg by immunoelectro-osmophoresis. In addition selected fractions were examined by complement fixation test, immune adherence hemagglutination and immune electron microscopy. Anti-HBc activity in IgG serum fractions was demonstrated by all four techniques used, but HBcAg-specific IgM was detected only by immunoelectro-osmophoresis and by immune electron microscopy. In acute hepatitis B, HBcAg-specific IgM was detected for up to eight weeks after the onset of jaundice. It was also found transiently in two patients who developed chronic hepatitis B without an icteric episode and in one out of thirteen patients with HBsAg-positive chronic liver disease, but in none of eight healthy HBsAg carriers. The results suggested that HBcAg-specific IgM is formed transiently in response to primary HBV infection but is generally undetectable in established HBsAg carriers.

Acute Disease↗
PubMed1978

Laboratory diagnosis of EB virus infection in some cases presenting as hepatitis.

In 1975 and 1976, 7580 serum specimens were tested for HBsAg by the passive haemagglutination test, Hepanosticon. Serum from 38 people gave a positive result after absorption with the absorbent provided, but the presence of HBsAg could not be confirmed by other tests. Tests for current infection with EB virus, namely, the presence of heterophil antibody and EB virus specific IgM, were performed and were positive in 11 of the 38. In six of these the clinical picture was of hepatitis rather than infectious mononucleosis.

Antibodies, Heterophile↗
PubMed1978

Chemical and physical restraint of nonhuman primates.

Numerous publications on primate restraint and anesthesiology have appeared in recent years. This reflects the striking growth of interest in medical primatology and of efforts to improve restraint agents and methods to facilitate humane use of primates in research. For access to earlier literature, readers should consult recent textbooks [12; 29, pp. 469--474], reviews on chemical or physical restraint [3, 4, 16, 27, 30, 37], and other valuable publications on these subjects that have appeared since 1965 [1, 20, 23, 36, 40, 42]. In this brief review we consider publications, principally since 1971, that deal with chemical or physical restraint. We also present previously unpublished data on the clinical use in primates of CI 744 (Telazol), a new dissociative anesthetic that until recently has been available only for investigational use.

Alfaxalone Alfadolone Mixture↗
PubMed1978

Age-associated pathological changes in male rats.

The selection of rats for aging research and the interpretation of experimental results require knowledge of spontaneous age-associated lesions in specific stocks and strains. We have compared selected age-associated pathological changes, as determined by postmortem examination of 113 outbred Crl:CD(SD)BR male retired breeder rats 12--39 months old, with those reported by others in a group of 122 virgin male 12- to 33-month-old F344 rats, an inbred strain from the same commercial source as the outbred rats. Numerous degenerative, inflammatory, and neoplastic lesions occurred in both groups. The wide prevalence and severity of many of the lesions suggest that they could be the source of significant variability in the results of specific aging studies, by their direct and indirect effect(s) on target organs. The prevalence of spontaneous lesions should be defined for each stock or strain intended for use in aging research by postmortem examination of representative groups of animals at various ages. Antemortem diagnostic screening of old rats may also be useful in culling animals bearing lesions that could add to the variability of experimental results, or in selecting for specific lesions that are of research interest themselves.

Aging↗