PubMed Health⌕ Search

Biomedical subjects

R B Heath

Publications and source records attributed to R B Heath.

At least 73 records · Page 4Linked to original sources
PubMed1980

A prospective study of influenza infections during pregnancy.

Serological evidence of infection with influenza A and B viruses was sought during three successive winters. Paired sera from 1595 pregnant women were studied and 79 infections occurred in 77 women (4.8%). A further 77 women who had no serological evidence of recent influenza infection were selected from the study population to serve as a control group. Cases and controls were comparable with respect to age, race, marital status, and number of previous pregnancies. Their offspring had virtually identical mean birth weights, skull circumferences, lengths, and incidences of neonatal jaundice. Although all the infections occurred in either the second or the third trimesters of pregnancy, the cases delivered more babies with congenital abnormalities than did the controls. The possibility was considered that the presence of an abnormal fetus made these women more susceptible to influenza infection. Unexpectedly, the women experiencing influenza infection during pregnancy delivered an excess of male babies, and an excess of females was born to the controls. Although this difference was statistically highly significant (P < 0.01), a biological explanation for the results was not readily apparent and it is suggested that future studies of influenza during pregnancy should particularly look for evidence of an altered sex ratio.

Birth Weight↗
PubMed1979

The pathogenesis of respiratory viral infection.

Sendai virus is used as a model to study the histological response and the mechanism of recovery of mice from infection. Although mice infected intranasally do not appear ill, the ciliated columnar cells of the bronchial epithelium undergoes rapid necrosis followed later by repair. Interferon is produced at an early stage of infection and antibody formation follows later. Cyclophosphamide given to mice infected with Sendai virus abolishes the humoral antibody response but not interferon production; the mice develop pneumonic lesions. They cannot eliminate virus and they die. On the other hand, deprivation of 'T' lymphocytes by thymectomy, irradiation and bone marrow reconstitution renders mice more susceptible to Sendai virus but they do not die. The humoral response is thus apparently helped by 'T' lymphocytes and interferon production is not vital for recovery.

Animals↗
PubMed1979

Changes in pulmonary function after naturally acquired respiratory infection in normal persons.

Changes in pulmonary function due to naturally occurring respiratory tract infection were examinated in 26 normal healthy volunteers during a period of 6 months. Forced expiratory maneuvers in each volunteer were recorded at 2-wk intervals throughout the study and daily during illness. Significant impairment of peak expiratory flow rate, forced vital capacity, forced expiratory volume in one second, and maximal mid-expiratory flow rate at 50% of the vital capacity was observed during infection, whereas changes in the maximal expiratory flow rate at 75% of vital capacity were nonsignificant. From these results, we conclude that large airways are certainly affected during uncomplicated respiratory infections in normal healthy persons and from the changes observed in FVC we suggest that more widespread involvement of the small airways may occur.

Adolescent↗
PubMed1979

The nature of the effector cells of cell-mediated immune responses to Sendai and Kunz virus infections in mice.

The development of virus-specific cell-mediated immune (CMI) responses to Sendai and Kunz virus infections of the respiratory tract of mice is described. In addition a heterotypic cell-mediated immune response develops during each of the virus infections. Cell depletion studies indicate that the effector cells of the virus-specific CMI responses are theta antigen bearing T lymphocytes. Similar studies of the heterotypic responses suggest that 2 cell types are involved, T lymphocytes and NK cells.

Animals↗
PubMed1978

A comparison of complement fixation, indirect immunofluorescence for viral late antigens, and anti-complement immunofluorescence tests for the detection of cytomegalovirus specific serum antibodies.

It was shown that, on average, the titres of the sera obtained by both the anti-complement immunofluorescence (ACIF) and indirect immunofluorescence for viral late antigens (IFA-LA) procedures were approximately eight times higher than those obtained by complement fixation. There was no significant difference between the mean ACIF and IFA-LA titres, but the former method was preferred because it was not affected by non-specific staining. When 406 sera were screened for the presence or absence of antibodies, only five sera (1.2%) gave discordant results with the three tests. None of the tests could detect all of the sera that contained specific antibodies while each test detected over 98% of these sera. Thus, the increased sensitivity of the immunofluorescence procedures did not result in an appreciably increased rate of detection of cytomegalovirus seropositive sera.

Antibodies, Viral↗
PubMed1978

The detection of rubella-specific IgM antibodies by radioimmunoassay.

An indirect solid-phase radioimmunoassay (RIA) has been developed for the detection of immunoglobulin (Ig) class-specific rubella antibodies. A commercial rubella haemagglutinin is dried and fixed on to the wells of flexible microtitre plates and allowed to react with serial dilutions of whole or fractionated human sera. Class-specific rubella antibodies are then detected by determining the specific binding of 125I-labelled anti-human IgG or IgM. The RIA was first evaluated by comparison with the haemagglutination-inhibition (HI) test for the detection of rubella-specific IgM in gel-filtration fractions. RIA was found to be as specific as HI but 10-150 times more sensitive. Rubella-specific IgG antibodies did not interfere in specific IgM determinations by RIA and therefore the latter technique was applied to unfractionated sera. The results obtained indicate that RIA on unfractionated sera is a practical, sensitive and specific technique which could provide a reliable method for the diagnosis of rubella. The rubella-specific IgM titres obtained by RIA were not increased by the removal of IgG by pretreatment of sera with Staphylococcal Protein A.

Antibodies, Viral↗
PubMed1977

Cell-mediated immunity to Sendai virus infection in mice.

The development of a cell-mediated immune response to Sendai virus infection in mice was examined by the use of a 51Cr release assay of cytotoxicity. A low level of "background cytotoxicity" to Sendai virus-infected L cells was found in the spleens of uninfected CBA mice. Spleen cells from Sendai-infected mice showed an elevated level of cytotoxicity against these target cells for a period of 5 weeks, commencing 4 days after infection of the mice. A more transient response was observed in the spleens of mice infected with a serologically distinct virus, the Kunz strain of influenza. This cross-reacting, cell-mediated immune response was intermediate between that observed in unsensitized and Sendai-sensitized spleen cells. The relevance of these cell-mediated immune responses to respiratory tract virus infections is discussed.

Animals↗
PubMed1977

Serum IgM antibody and influenza A infection.

Sucrose density gradient ultracentrifugation followed by haemagglutination inhibition for demonstrating specific influenza IgM was evaluated as a means of confirming recent infection with influenza A viruses. Specific IgM antibodies were found in at least one serum obtained from 83% of patients with proven recent infection with influenza A viruses but in none of the sera from 21 individuals without evidence of infection. Influenza IgM antibodies persisted for up to 112 days after infection. The relative merits of detecting specific IgM and complement fixing antibodies for diagnostic purposes are discussed.

Antibodies, Viral↗
PubMed1976

A comparative study of passive haemagglutination methods for the detection of hepatitis B surface antigen in routine hospital practice.

Two passive haemagglutination methods for detecting HBsAg were compared. In general, the method using turkey erythrocytes was found preferable to the method employing sheep cells since it is more rapid and more sensitive, and less frequently gave rise to false positive reactions with sera from staff, blood donors, and patients not receiving haemodialysis. The turkey cell test gives rise to more false positive screen tests than the sheep cell test when monitoring renal dialysis patients since approximately 10% of the sera of these patients were found to contain turkey cell agglutinins, but this presents no particular difficulty if the recommended absorption procedures are used.

Animals↗
PubMed1975

Studies of the genetic susceptibility of individuals to infection with influenza viruses.

Nearly three and a half thousand sera obtained from various populations were tested serologically to obtain evidence of past infection with influenza A viruses that were prevalent from 1947 to 1972. No significant difference was found between the distributions of the levels of these antibodies of individuals of blood groups A and O, A1 and O, Rh (D+) and Rh (D-) and MM, MN and NN. The significance of these findings is discussed.

ABO Blood-Group System↗
PubMed1975

The pathogenesis of infections of the mouse caused by virulent and avirulent variants of an influenza virus.

A virulent variant of the normally avirulent Kunz strain of influenza virus was obtained by serial passage in mice, and the pathogenesis of the infections caused by the two strains was studied. The virulence of the passaged variant did not appear to result from increased growth in lungs, from acquisition of resistance to non-specific inhibitors or from inadequate immunogenicity, but from its greater ability to replicate in alveolar cells. The apparent adequacy of defence mechanisms to protect against mucosal infection but their failure to protect against infection of alveolar cells in discussed.

Animals↗
PubMed1975

Effect of cyclophosphamide on infections in mice caused by virulent and avirulent strains of influenza virus.

Induced immunosuppression with the drug cyclophosphamide was shown to convert the relatively harmless infection with an avirulent strain of Kunz influenza virus into a fatal pneumonic illness. The drug was also shown to increase the mortality of mice infected with low concentrations of a virulent variant of this strain, but it delayed the time of death of mice that were infected with high concentrations ofthe same variant. The probable roles of immune and inflammatory mechanisms in recovery from primary influenza virus infections are discussed.

Animals↗