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Biomedical subjects

A Johnson

Publications and source records attributed to A Johnson.

At least 487 records · Page 27Linked to original sources
PubMed1988

Psychosocial implications of recurrent genital herpes simplex virus infection.

Fifty seven patients experiencing first attacks of genital herpes simplex virus infection (HSVI) were compared with 50 patients who were concerned about frequently recurring attacks despite routine counselling and reassurance. Using the general health questionnaire this latter group was found to be more psychologically distressed and more socially naive than the first attack group, as measured by socioeconomic class and the lie score of the Eysenck personality questionnaire; otherwise the two groups were similar. Patients presenting to clinics with frequently recurring genital HSVI may therefore be especially psychologically distressed, socially naive, and disadvantaged. Managing these patients needs to include understanding these problems as well as giving advice and using antiviral agents.

Adolescent↗
PubMed1988

PMA-induced pulmonary edema: mechanisms of the vasoactive response.

We investigated the effect of phorbol myristate acetate (PMA) in isolated guinea pig lungs perfused with phosphate-buffered Ringer solution. Pulmonary arterial pressure (Ppa), pulmonary capillary pressure (Ppc), and change in lung weight were recorded at 0, 10, 25, 40, and 70 min. The capillary filtration coefficient (Kf), an index of vascular permeability, was measured at 10 and 70 min. The perfusion of PMA (0.5 x 10(-7) M) increased Ppa, Ppc, and lung weight at 70 min. The ratio of arterial-to-venous vascular resistance (Ra/Rv) decreased and the Kf did not change with PMA. The perfusion of the lung with 4 alpha-phorbol didecanoate (inactive toward the protein kinase C analogue of PMA) did not affect the lung. The inhibition of TxA2 synthase with dazoxiben inhibited the response to PMA. The inhibition of the 5-lipoxygenase with U-60257 and the SRS-A receptor antagonist FPL 55712 also prevented the response to PMA. The addition of superoxide dismutase (SOD), catalase, or SOD plus catalase (the enzymes that remove O.2 H2O2, and OH., respectively) did not prevent the PMA effect or the release of TxA2; however, dimethylthiourea (DMTU), a scavenger of OH., did prevent the response to PMA. The data indicate that PMA causes a neutrophil-independent increase in lung weight due to increases in Ppc mediated by TxA2 and SRS-A. The protective effect of DMTU may be due to the inhibition of TxA2 generation.

Animals↗
PubMed1988

Inflammatory events after fibrin microembolization. Alterations in alveolar macrophage and neutrophil function.

We performed bronchoalveolar lavage (BAL) 0.5 to 24 h after thrombin-induced pulmonary microembolization in spontaneously breathing sheep to examine the inflammatory events that occur after pulmonary intravascular coagulation. Neutrophil alveolitis was evident as early as 0.5 h after microembolization and was maximal at 4 h (4.9 +/- 1.5% neutrophils of total BAL cells at baseline versus 26.2 +/- 2.8% at 4 h post-thrombin). Neutrophils obtained both at baseline (isolated from peripheral blood) and at 0.5 to 24 h after thrombin (isolated from BAL) did not demonstrate significant basal production of superoxide anion (O2-) and produced similar amounts of O2- upon challenge with phorbol myristate acetate (PMA) 200 micrograms/ml. The basal O2- production by alveolar macrophages was also not increased. However, alveolar macrophages recovered after fibrin microembolization produced greater amounts of O2- (29.1 +/- 6.3 nm O2-/10(6) cells at 0.5 h) after challenge with PMA compared with alveolar macrophages recovered prior to embolization (10.6 +/- 1.6 nm O2-/10(6) cells baseline), suggesting that thrombin-induced microembolization primes alveolar macrophages and enhances their O2- generation. Neutrophil chemotactic activity was detected in BAL fluid at 0.5 h post-microembolization and reached a peak level at 2 h. Alveolar macrophages were a source of the chemotactic activity since conditioned medium obtained from 2-h post-thrombin macrophages induced neutrophil chemotaxis, whereas baseline cells did not. The addition of the thrombin to macrophages did not result in the generation of chemotactic activity from baseline macrophages, indicating that macrophages were activated during the process of intravascular coagulation rather than by thrombin per se. Post-thrombin BAL fluid also stimulated O2- generation from sheep neutrophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1988

Umbilical arterial systolic/diastolic values in normal twin gestation.

Linear regression analysis was used to describe the relationship of umbilical arterial systolic/diastolic values to gestational age in 65 twin gestations. This relationship (y = 6.18 - 0.11x) was then compared with a previously described regression for singleton pregnancies using a multiple regression model. This comparison revealed that the relationship between the systolic/diastolic ratio and gestational age is the same in singleton and twin gestations.

Diastole↗
PubMed1987

A simple method for preparing prometaphase chromosomes from amniotic fluid cell cultures.

A simple method for preparing prometaphase chromosomes from amniotic fluid cell cultures is described. The technique is based upon several key steps including: (1) reduced colcemid concentration, (2) reduced exposure to trypsin-EDTA, and (3) maintaining cells in single suspension by adjusting cell concentration appropriately. Chromosomes with banding resolution up to 800 bands per haploid set can be routinely produced. The described methodology is particularly useful in defining and establishing the clinical significance of subtle structural aberrations.

Amniotic Fluid↗
PubMed1987

Partial amino acid sequence analysis of rabbit MHC class II molecules isolated from two-dimensional polyacrylamide gels.

Partial N-terminal amino acid sequence analyses were performed on rabbit MHC class II molecules eluted from 2-D electrophoretic gels. Rabbit spleen cells were biosynthetically labelled with 3H-phenylalanine, 3H-tyrosine and 35S-methionine and class II molecules were immunoprecipitated with a monoclonal antibody, 2C4. The immunoprecipitates were electrophoresed on 2-D gels and as many as 15 spots were observed. Individual spots corresponding to alpha and beta chains were eluted from unfixed gels following visualization of the spots by autoradiography of 35S-Met labelled polypeptides. Ten eluted polypeptides were subjected to amino acid sequence analysis to locate Phe and Tyr residues. Comparison of these partial sequences with sequences of human class II molecules indicated that each of six beta chains and three of four alpha chains were homologous to human DQ molecules; one of the alpha chains appeared homologous to DR alpha or DP alpha. The assignment of alpha or beta chain to the polypeptides was confirmed by radiosequence of molecules labelled with 35S-Cys residues. Thus, by a relatively simple procedure, individual MHC class II polypeptides in spleen cell lysates have been separated from each other and partial amino acid sequences have been obtained.

Amino Acid Sequence↗
PubMed1987

The effects of immunoglobulin isotype and antibody affinity on complement-mediated inhibition of immune precipitation and solubilization.

We have studied complement-mediated prevention of precipitation (PIP) and solubilization of immune complexes (IC) formed with DNP19-BSA and murine monoclonal antibodies (MCAs) of different isotypes and affinities. PIP was effective for IC formed with IgG1 and IgM antibodies, but not for IgA MCA. For IgG1 MCAs, affinity appeared to exert a minor effect on PIP, and IC formed in antibody excess or at equivalence were retained in solution more readily than those formed in antigen excess. For IgM MCAs affinity and antigen-antibody ratio did not affect PIP. As PIP did not occur in Mg-EGTA, it was concluded that PIP was entirely classical pathway dependent. Solubilization of IC containing IgG1 MCAs occurred more rapidly and to a greater extent with low affinity antibodies and an inverse relationship between affinity and the extent of solubilization was observed. Complexes formed with IgG1 MCAs were solubilized relatively poorly when formed in antigen excess. In contrast, affinity and antigen-antibody ratio did not influence the rate and extent of solubilization of IC containing IgM MCAs. IC formed with IgG2b were solubilized rapidly whereas those formed with IgG2a or IgA were solubilized poorly. The relative contributions of the classical and the alternative pathways to solubilization varied with each antibody and the effect of antigen-antibody ratio on these relative contributions was inconsistent.

Antibodies, Monoclonal↗
PubMed1987

Detection of cytomegalovirus by 24-well plate centrifugation assay using a monoclonal antibody to an early nuclear antigen and by conventional cell culture.

During a 12-month period, two methods for detection of cytomegalovirus (CMV) in 1624 clinical specimens were compared: (1) centrifugal inoculation of MRC-5 cells on coverslips in 24-well plates and staining with a monoclonal antibody to CMV early nuclear antigen after incubation for 40 h (EA assay), and (2) conventional tube cell culture. CMV was identified in 183 (11.3%) specimens from 113 different patients. The EA assay was positive for CMV in 144/183 specimens (79%), and CMV was detected by recognition of specific cytopathic effect (CPE) in conventional cell culture in 143/183 (78%). Both methods yielded CMV in 56% of the specimens (104/183). CMV was detected by EA assay alone in 22% (40/183) and only by CPE in 21% (39/183) of the positive specimens. When all specimen types were considered, there was no significant difference in the detection of CMV between the two methods. However, bronchoalveolar lavage (BAL) fluids yielded CMV more frequently by EA assay than by CPE (58 compared to 48 of 574, p = 0.0178), and CMV was detected in blood specimens more often by CPE than by EA assay (20 compared to one of 149, p less than 0.0001). In addition to CMV, other viruses were recovered by conventional tube cell culture, including herpes simplex virus (HSV) type 1 from 17 BAL fluids (two of which were positive for CMV by EA assay) and one liver biopsy and adenovirus serotype 4 from four separate urine specimens and three gastrointestinal tract biopsies from one patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗