The South African journal of medical sciences最新文献

An oesophageal carcinoma cell line was karyotyped at passages 8,48,64 and 88. It showed a persistent loss of D group chromosomes and subtelocentric, acrocentric, dicentric and other markers were frequently present. During 80 passages the modal number declined from 60,5 to 54,09. The chromosome pattern of a hepatoma cell line was studied at passages 15/17 and 28. It showed a loss of D and G group chromosomes and the presence of various markers including a D/G fusion.

The concentration of vitamin B12 and its binding proteins was measured in the impala, nyala, wildebeest, zebra, bushpig, warthog, and rhino, all existing in their natural state. Marked differences were found between some species. The variations observed are probably true species differences, unrelated to environmental factors.

Ventilatory response to carbon dioxide was measured by the rebreathing technique in 32 Nigerians and 20 Europeans resident in Lagos. Although the Europeans had larger physical characteristics and lung volumes than Nigerians, the responses to carbon dioxide were similar. The range of ventilatory response was 0,55 to 4,2 and 0,7 to 3,7 1/min/mm Hg for Nigerians and Europeans respectively. These results show that Nigerians are as sensitive to carbon dioxide as their European counterparts.

Despite a wide belief that little information is available on the dimensions of Southern African peoples, data for adult mean stature are presented for no fewer than 123 samples of S.A. Negro (93) and Khoisanoid (30) peoples. Many are published here for the first time. These have made possible a search for signs of the secular trend towards increased adult stature. Two main techniques are the study of longitudinal data (where time-spaced studies on the same population are available) and of age-ranked, cross-sectional data (where the lack of declining stature with age connotes the absence of a secular trens). Most Southern African populations for which data are available show either the absence of the secular trend (previously recognized) or a frankly reversed secular trend (a new concept), in which adults show a decline in mean stature compared with earlier generations. Similar absence or reversal of the secular trend characterizes peoples in Malawi, Kenya, Uganda, Sudan, Senegal, Upper Volta and Ivory Coast, as well as some Asian and South American samples. In the main, developed areas show the secular trend, while less developed areas show an absence or reversal of the trend. To this generalization, the San are a striking exception. All the evidence, first adduced in 1962, points to the usual secular trend as occurring in the San, despite their lowly, undeveloped economic status. Although the data are imperfect, it is possible too, that Xhosa and Moçambique Maravi show evidence of a positive secular trend. "The adult form of mankind is the outcome of growth enhanced, dwarfed, warped, or mutilated by the adventures of life. I am not decrying heredity. But I do insist that new knowledge gained for anthropology through the study of growth brings hope and confidence where formerly was only the grim figure of destiny." (T. Wingate Todd, 1935).

The role of the different cytochromes P-450 in the metabolism of the anaesthetic agent fluroxene, and the mechanism of production of toxic effects seen after pre-treatment of the animals with pehnobarbital prior to anaesthesia, have been investigated. Male rats were anaesthetized with fluroxene, or with 2,2,2-trifluroethyl ethyl ether, or with ethyl vinyl ether in an attempt to ascertain the in vivo toxic effects of the three anaesthetic agents. The resultant hepatic histology is reported. A study of the binding and metabolism of fluroxene by isolated rat hepatic microsomes was also made. We conclude that it is elevated levels of cytochrome P-450 which potentiate the toxicity of fluroxene anaesthesia in phenobarbital treated animals and that cytochrome P-448 does not bind or metabolize fluroxene. The potential toxicity of the fluroxene molecule is considered to reside in the trifluoroethyl moiety, while the vinyl group of fluroxene appears to play a role in the observed liver damage.

The sexual dimorphism in mouse submaxillary glands is well documented. The main difference is seen in the granular convoluted tubules (G.C.T.) which in the adult male are large and in the adult female are small and fewer. Previous studies have shown that amylase is localized histochemically to these G.C.T.'s; that following castration there is a histological reduction in size and number of the G.C.T.'s and a roughly 50 per cent decrease in amylase activity demonstrable biochemically. In the present study 74 male mice aged 60 days were divided in six groups. The animals were fasted overnight. Under general anaesthesia, the submaxillary glands on the left side were removed and frozen in liquid nitrogen for subsequent histochemistry. The animals were then castrated and returned to their cages. At periods of 2, 4, 6, 8, 10 and 12 weeks later, the other submaxillary gland was removed under the same conditions, and the animals were then killed. Fresh frozen cryostat sections of both glands were subjected to the starch substrate film technique for the histochemical demonstration of amylase. Adjacent sections were stained with HE. The 2-week animals showed a slight but define reduction in size and number of G.C.T.'s and a parallel reduction in amylase activity. This was more pronounced by 4 and 6 weeks. In the 4-week animals, however, the changes were not consistent, being more pronounced in some animals than in others. This same phenomenon was observed in the 6-, 8- and 10-week animals, in some of whom there was considerable G.C.T. atrophy in the submaxillaries and in others very much less. In many of the 12-week animals there was very little evidence of G.C.T. atrophy. These findings confirmed other studies which suggested that there may be some regeneration of G.C.T's, possibly as a result of influence of other endocrine glands such as thyroid, adrenal and pituitary.

The ascorbate status and the effect of loading doses of ascorbic acid (1,5 g per day by mouth for 7 days) on the porphyric process were studied in 7 black men with porphyria cutanea tarda symptomatica. It was found that the ascorbate stores were depleted in these patients as judged by serum and leucocyte ascorbate levels. Temporary repletion of the ascorbate stores was effected by the loading doses of ascorbic acid: Serum iron concentrations increased in 6 patients; urinary iron excretion showed small peaks a few days after ascorbic acid therapy commenced; haemoglobin concentration was not affected; excessive amounts of oxalate were excreted in the urine; neither total urinary porphyrin excretion nor the composition of the urinary porphyrins was affected in a way which could be related to ascorbate therapy. Further evidence that ascorbate depletion is not important in the induction of porphyria was found when the ascorbate status of siderotic rats, rendered porphyric by hexachlorobenzene-feeding, was examined. Stores of ascorbate and the oxidative catabolism of ascorbate were not different in the prophyric rats as compared with normal litter mates.