The South African journal of medical sciences最新文献

The isolation of an ovine herpesvirus from a cell culture of an adenomatous sheep lung is reported, confirming previous observations of a possible association of a herpesvirus with this tumour. Some growth properties and morphological characteristics of the virus are described, as well as serological data supporting a possible relationship between tumour and virus. Attempts to produce jaagsiekte by intratracheal injection of virus into lambs were unsuccessful, suggesting that a second factor may be involved inthe oncogenic process possibly similar to that proposed for the well-known EBV-Burkitt's lymphoma system.

Patterns of response to carbon dioxide (CO2) inhalation in 12 Nigerian asthmatic patients before and after salbutamol aerosol inhalation are described. Ventilatory response to CO2 inhalation follows three patterns, viz,(1) an increase; (2) a decrease; (3) no change in response. While most of our subjects showed substantial improvement in forced expiratory volume in one second (FEV1) following bronchodialator therapy, there was no corresponding change in ventilatory response to CO2. On the whole. the mean values of the slope of response to CO2 inhalation of the asthmatics before and after bronchodilator were not significantly different from values obtained in normal patients in our laboratory.

To aid elucidation of the chemical composition of the antigonadotrophic substances produced by the epiphysis cerebri, 100 bovine pineal bodies were incubated in Krebs-Ringer buffer and the incubate treated to give an ethyl acetate and an aqueous extract. Using thin layer chromatography on fluorescent silica gel plates, 5 indoles were identified and 6 unknown substances isolated from the pineal incubate and from both extracts. The presence of peptides was detected in the incubate and in the aqueous extract. The antigonadotrophic activity of the incubate and of the two extracts was examined using a continuous flow in vitro system with the production of luteinizing hormone (LH) from bovine adenohypophysial tissue as the final parameter. All three fractions were found to result in a somewhat similar production of LH. To distinguish between the antigonadotrophic activity attributable to the indole and the indole/protein components of the pineal secretion, 90 bovine pineal bodies were homogenized and the homogenate incubated in the continuous flow in vitro system in the presence or absence of trypsin and trypsin-inhibitor. Results were inconclusive regarding the role played by the indole and indole/protein fractions in the antigonadotrophic activity of the pineal body.

The transient decrease in coronary conductance and flow that is seen when the atria contract has been studied in 6 anaesthetized, open-chest dogs in heart block, paced via epicardial pacemaker leads. Left circumflex and anterior descending coronary flows were recorded via Doppler ultrasonic flow probes; aortic and left ventricular pressures and electrocardiogram were recorded simultaneously. The transient conductance and flow decrease in diastole were found from linear regression to be consistent with the left ventricular pressure rise caused by atrial contraction, in the case of the anterior descending coronary artery, which also showed no decrease in peak systolic conductance or flow when atria and ventricles contracted simultaneously. Circumflex conductance and flow were decreased by an atrial contraction to an extent greater than could be accounted for by the rise in left ventricular diastolic pressure. Peak circumflex flow and conductance were also decreased in systole, by 12 per cent, when atrial and ventricular contractions were exactly synchronous so that the atria could not discharge into the ventricles. The systolic effect and the excessive diastolic effect are ascribed to compression of atrial branches of the circumflex artery. This artrial compression mechanism accounted for 37-75 per cent of the effect of an atrial contraction on conductance in diastole. Values from 5 dogs of systolic and diastolic conductance changes due to atrial compression were linearly related. Calculation of atrial flow by applying this percentage to the transient flow decrease indicated that 17 per cent of circumflex diastolic flow was atrial, and that this percentage stayed constant throughout diastole.

The beta-alanyl and L-histidyl analogues of puromycin were synthesized chemically and tested for their ability to release [3H] N-acetylphenylalanine from its tRNA carrier in the rat liver and E. Coli ribosomal systems. Both analogues were found to be inactive in releasing [3H] N-acetylphenylalanine. Reasons for the inactivity of these compounds are discussed in relation to the structure of the puromycin molecule and the requirements for puromycin-like activity.

IgG, IgA and IgM levels were measured in the serum of 73 patients with hepatitis-B antigen-positive (virus-B) acute hepatitis and 48 patients with hepatitis-B antigen-negative (virus-A) hepatitis. The mean serum IgM level on admission was significantly higher in virus-A than in virus-B hepatitis (p less than 0,01), and remained so for 2-3 weeks. However, the overlap between the individual figures in the two forms of the disease was so great as to make the estimation of little diagnostic value. The mean serum IgG and IgA levels at the time of admission were not significantly different in the patients with and without hepatitis-B anti-genaemia.

Six in vitro trials were conducted using bovine tissues to study the effects of addition of cerebrospinal fluid (C.S.F.) to the incubation medium on the secretion of luteinizing hormone (LH) from adenohypophysial tissue, both in the presence and absence of hypothalami. Additionally, a study was made of the effect of including pineal bodies on the secretion of LH in both medium alone and in medium + C.S.F. No marked or consistent effect on LH secretion was observed when the C.S.F. concentration ranged between 5 per cent and 40 per cent, when the tissues were incubated in C.S.F. alone, nor when pineal bodies were added to the culture system. These results do not support the concept that the C.S.F. contains substantial amounts of substances which enhance secretion of LH from the anterior pituitary.