Biomedical subjects
Publications and source records attributed to G B Rees.
Nineteen pigs in a 500 sow herd died from anthrax over a period of 95 days. This paper describes some of the problems encountered and how they were dealt with, including the risks to public health, the disposal of slurry and the cleansing and disinfection of the premises after the herd was slaughtered.
A case of amphetamine abuse in late pregnancy is reported. The presenting features of convulsions, confusion, agitation with hypertension and proteinuria led to a diagnosis of eclampsia for which a caesarean section was performed. Investigations and differential diagnosis of convulsions in late pregnancy are reviewed. A general urinary drug screen gives results after 24 hr whereas, if amphetamine abuse is suspected, this can be confirmed within three hr if a specific test for urinary amphetamines is performed. The sympathomimetic effects of a single dose of amphetamine are contrasted with the depression of the sympathetic nervous system which occurs after long-term use. Implications for anaesthesia are discussed.
Respiratory frequency, tidal volume, minute ventilation, oxygen consumption, carbon dioxide production, and end-tidal carbon dioxide tension were measured longitudinally during pregnancy and post partum in 20 normal subjects with a computer-assisted mass spectrometer. Resting tidal volume, minute ventilation, oxygen consumption, and carbon dioxide production increased during pregnancy. End-tidal carbon dioxide tension fell progressively during pregnancy. Respiratory exchange ratio was 0.9 at 36 to 39 weeks' gestation and 0.8 at 5-13 weeks post partum. Respiratory frequency did not change during pregnancy. The increase in minute ventilation is in excess of the increase of carbon dioxide production and the resultant fall in end-tidal carbon dioxide tension reflects a fall in systemic arterial blood carbon dioxide tension. The greater respiratory exchange ratio during late pregnancy as compared with post partum also reflects this hyperventilation during pregnancy. Fourteen subjects with pregnancy-induced hypertension studied cross-sectionally failed to show any difference in the respiratory variables measured when compared with normotensive subjects at a similar length of gestation.
Peripheral blood lymphocytes taken from healthy women planning a pregnancy and then at various intervals up to the 16th week of pregnancy were assayed for natural killer (NK) cell activity against K562 target cells both in a 51Cr-release assay and in a single cell cytotoxicity assay. Results indicated a depression in NK activity from the earliest stages of pregnancy. The target binding capacity of the effector cells remained unimpaired up to 16 weeks, but a significant reduction in the post-binding lytic potential was observed, which parallelled the drop in cytotoxicity as assayed by the 51Cr-release method. The ability of individual effector cells to recycle and kill multiple targets remained essentially unimpaired. Analysis of lymphocyte subpopulations using the monoclonal antibodies anti-Leu-7 and anti-Leu-11b, which recognize NK cell-associated antigens, showed a significant reduction in the proportion of the mature, lytically active Leu-7-11+ cells capable of both binding and lysing K562 target cells. The suggestion that the depression in cytotoxicity may be associated with the reduction in the Leu-7-11+ subpopulation is supported by the high correlation levels observed between the proportion of Leu-7-11+ cells and target cell lysis.
Peripheral blood lymphocytes (nylon wool non-adherent) from healthy pregnant women and normal non-pregnant females were tested for natural killer (NK) cell-mediated cytotoxicity against K562 target cells both by 51Cr-release assay and single-cell cytotoxicity assay in agarose. The results indicated depression of NK cytotoxicity in pregnancy due to a decrease in the proportion of target-binding lymphocytes as well as a reduction in the lytic capacity of target-bound cells. The ability of active pregnancy-associated NK lymphocytes to recycle appeared to be unimpaired. Analysis of lymphocyte populations with monoclonal antibodies recognizing NK cell-associated antigens showed that the number of Leu-11+ lymphocytes was reduced in pregnancy. Enumeration of Leu-7+ cells and correlation of NK cell subpopulation data with cytotoxicity assay data suggest that pregnancy is associated with a reduction in the number of mature NK cells and probably also an inhibition of post-binding lytic activity.