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Biomedical subjects

T Johnson

Publications and source records attributed to T Johnson.

At least 271 records · Page 15Linked to original sources
PubMed1975

Immunological control of virus-induced tumors in primates.

Cells infected by oncogenic viruses may transform, may develop a latent carrier state, or may be destroyed but understanding of the control of the results of infection is incomplete. Even if cells transform, ultimate development of a tumor may be immunologically controlled. For example, cells of some marmoset species transform after infection with RNA tumor viruses, and animals react to the transformed cells with cell-mediated and humoral immune responses. Both virus specific and cross-reacting cell membrane antigens have been demonstrated. Immune deficiency accelerates tumor growth or causes recurrence of a regressing tumor. In contrast certain simian herpesvirus (Herpesvirus saimiri, HVS and Herpesvirus ateles, HVA), which cause no or minor disease in their natural hosts, induce lymphomas or lymphoblastic leukemias in other primate species. The immune response of the natural host species to HVS is greater than that of animals developing malignancies after experimental infection. HVS and HVA share many properties with Epstein-Barr virus (EBV) of man, including antigens appearing early and late during infection and their related antibody responses but no evidence exists that they induce malignancies in their natural hosts. However, if induction is as infrequent as that with EBV and Burkitt's lymphoma (BL), we have not observed sufficient numbers of squirrel or spider monkeys to have seen a BL-like tumor. Interference with the immune systems of animals carrying HVS or HVA may induce tumor development, and clarify our understanding of the relationships between EBV and BL.

Animals↗
PubMed1975

Routine radioimmunoassay of plasma testosterone, and results for various endocrine disorders.

We describe a modification of published methods for radioimmunoassay of plasma testosterone. This simpler method involves no chromatographic steps, and the necessary reagents, including tritiated testosterone and testosterone anti-serum, are commercially available. A digital computer is used for the calculation. Without difficulty, a technician can complete 100 assays in three working days. Mean testosterone concentrations (plus or minus 2 SD) in the plasmas of 21 normal men and 26 women with a normal menstrual cycle were 684 plus or minus 300 and 45 plus or minus 20 ng/dl, respectively. Within- and between-assay precision (coefficient of variation) were 5.2% (n = 29) and 6.7% (n = 26), respectively. We have assayed more than 1000 samples during the past year. We give data on the concentrations of testosterone in plasma of patients with various endocrine disorders.

Adult↗
PubMed1970

A data processing system for hospital bacteriology.

A system for the automatic capture and retrieval of information contained in routine bacteriology reports is described. The system depends on the preparation of reports on an electric typewriter producing punched paper tape as a byproduct. Periodically the information contained on the tape is analysed by computer. The potential value of the system for the analysis of the results of antibiotic sensitivity testing and for the study of the epidemiology of hospital infections is briefly discussed.

Anti-Bacterial Agents↗
PubMed1969

Haemolytic disease of the newborn caused by anti-Lan antibody.

The first recorded example of anti-Lan associated with haemolytic disease of the newborn is reported. This emphasizes the importance of screening for atypical antibodies early in pregnancy, even though prophylactic use of anti-D immunoglobulin will eventually reduce the incidence of haemolytic disease due to anti-D antibody.

Adult↗
PubMedDate not supplied

Treatment of secondary stent-graft collapse after endovascular stent-grafting for iliac artery pseudoaneurysms.

We report the case of a patient who developed an asymptomatic pseudoaneurysm in the left external iliac artery after transplant nephrectomy. The pseudoaneurysm most probably arose as a suture aneurysm from the external iliac artery after removal of the graft renal artery. Obviously we can not exclude the possibility it was a true aneurysm, although this seems much less likely. The pseudoaneurysm was detected during a routine CT scan and was treated interventionally with a stent-graft. One month later the asymptomatic patient underwent a vascular ultrasound examination including color Doppler, power Doppler, and B-flow as a routine control. An endoleak with collapse of the stent-graft was diagnosed. There was no evidence of stent infection. At a reintervention, the pseudoaneurysm was successfully treated using two uncovered Palmaz stents at the proximal and distal edge of the stent graft. Peri- and post-interventional ultrasound and CT angiography confirmed the exclusion of the aneurysm without an endoleak.

Adult↗
PubMedDate not supplied

Fetal and maternal Doppler flow velocity waveforms in normal sheep pregnancy.

Abnormalities in placental vascular resistance have been shown to have an important association with intrauterine growth retardation in both human and sheep pregnancies. In this study we have assessed impedance to blood flow through the ovine placental circulation by Doppler flow velocity waveform analysis. As gestation advanced from 66 to 136 days, a significant decrease in impedance to flow was observed in both umbilical and maternal placental arteries. The greatest decrease in impedance was observed between 66 and 109 days' gestation in umbilical arteries and between 66 and 80 days' gestation in maternal placental arteries. In these normal pregnancies, no significant correlations could be found between Doppler flow velocity waveform analyses and fetal or placental growth. We conclude that Doppler flow velocity waveform analysis is a valuable and non-invasive method to assess impedance to blood flow through the placental circulation in pregnant sheep.

Animals↗