High postmortem concentrations of hypoxanthine and urate in the vitreous humor of infants are not confined to cases of sudden infant death syndrome.

OBJECTIVE: High concentrations of hypoxanthine and urate have been found in the blood of rats who died suddenly during induced respiratory alkalosis as well as in cases of sudden death in malignant hyperthermia-susceptible pigs challenged with halothane. The origin of these metabolites is the excessive hydrolysis of adenine nucleotides, which is associated with the production of free radicals. We wished to establish whether high levels of these compounds were also to be found in sudden infant death syndrome (SIDS) victims, compared with other causes of death. DESIGN: Vitreous humor samples were analysed for hypoxanthine and urate by high-performance liquid chromatography. SETTING: Forensic Laboratories, Salt River, Cape Town. PARTICIPANTS: Vitreous humor samples were collected from 91 infants presented for postmortem examination. MAIN OUTCOME AND RESULTS: From autopsy reports, cause of death was classified as: (i) SIDS (N = 50); (ii) acute sudden death (N = 5); and (iii) all other causes of death (N = 36). There were no differences in the hypoxanthine or urate levels of groups (i) and (iii) over the first 5 days of the postmortem period. Group (ii) levels were lower than those of both (i) and (iii). CONCLUSION: Adenine nucleotide hydrolysis is not only a feature of SIDS, and possibly results from antemortem hypoxia in most deaths. The lower concentrations found in cases of acute sudden death probably resulted only from postmortem hydrolysis of the nucleotides.

Parathyroid hormone, ionised calcium, and potentially interacting variables in plasma of an Old World primate.

Bone turnover and calcium homeostasis in man can only be modelled validly in Old World nonhuman primates. In order to interpret the models it is necessary to establish endocrine and biochemical parameters of bone mineral metabolism. This report is probably the first description of acute phase parathyroid responses to manipulations of blood ionised calcium, and of reference values for potentially interacting variables, in vervet monkeys. Plasma parathyroid hormone concentrations were measured in vervets under defined conditions, and ranges reported as normal for other nonhuman primates and man are summarised.

William Jolly--father of medical science in South Africa.

William Jolly graduated in medicine at Edinburgh University in 1906 and became research assistant to Sir Edward Sharpey Schafer. He also mastered various techniques in electrophysiology under Einthoven, graduating D.Sc. in 1911. In 1911 he was appointed first Professor of Physiology and in 1918 first Dean of the Faculty of Medicine at the University of Cape Town. He conducted and stimulated research there and in recognition thereof was awarded an Honorary LI.D. by Edinburgh University and a special allowance from the University of Cape Town. He was President of the Royal Society of South Africa, a trustee of the South African Museum and a member of the National Research Council and Board.

Transient response of the calcium homeostatic system: effect of calcitonin.

With the use of an intravenous step load of calcium, a rapid (less than 30 min) process that helps regulate plasma calcium has been identified in pigs. The process appears to be calcitonin dependent, may not involve simple equilibration, and varies inversely with age, as it is virtually absent in old sheep compared with its intensity in young sheep. Based on these findings and a general model of calcium homeostasis, five classes of regulatory processes are proposed. Grade I (half time, t1/2, congruent to 15 min) is a transient and saturable response present only in young individuals and is calcitonin dependent. Grade II (1/2 congruent to 60-90 min) is parathyroid hormone and possibly calcitonin dependent. Grade III (t1/2 = 3-4 h) is parathyroid hormone dependent and probably renal in nature. Grade IV (t1/2, several hours) is vitamin D dependent and intestinal in nature. Grade V (t1/2, hours or days) is parathyroid hormone and calcitonin dependent and skeletal in nature.

Failure of bone phosphorus levels to indicate dietary intake of phosphorus by sheep.

Fifteen actively growing lambs were divided into 3 groups and fed diets similar in all respects except for their calcium (Ca) and phosphorus (P) levels. The diets (Group 1; 1,47% Ca, 0,36% P: Group 2; 0,85% Ca, 0,47% P: Group 3; 0,37% Ca, 0,64% P) were fed to the animals for 98 days, when rib biopsy specimens were removed and analysed for Ca and P (Group 1; 21,20% Ca, 10,49% P: Group 2; 19,54% Ca, 9,42% P: Group 3; 19,10% Ca, 9,24% P). Although there were no differences (P greater than 0,01) in the bone analyses between the groups, there was a tendency for bone calcium levels to follow dietary calcium levels. Bone phosphorus levels, again, followed bone calcium levels and were opposite to dietary phosphorus levels. This work re-emphasizes the dominance of calcium over phosphorus in bone formation. Implications of these findings are discussed in the light of the use of bone phosphorus analyses to estimate the phosphorus intake and status of grazing sheep.

A report on the safety of an intravenous compound calcium solution and the levels of plasma total and ionized calcium following injection.

An intravenous compound 5% calcium solution was subjected to three trials in S.A. Mutton Merino X Merino ewes to establish its safety and also to resultant levels of blood total and particularly ionized calcium. In the first trial, 10 animals each received 20 ml of the compound but the administration time progressively decreased from 90 seconds in the first to only 15 seconds in the last ewe. Plasma total calcium levels more than doubled in all the animals and, except for transient disorientation in the last ewe, nothing untoward was noted. In the second trial 4 ewes again received 20 ml of the compound while in the third trial 5 ewes received the compound at the rate of 0,5 ml/kg. In both trials the administration time was about 30 seconds. Plasma total and ionized calcium levels more than doubled initially and, while there was a steady and parallel decline in both, they were still more than 60% higher than pre-injection levels after as long as 2 hours.

Studies on feline babesiosis. 4. Chemical pathology; macroscopic and microscopic post mortem findings.

Chemopathological changes were monitored in 20 experimentally infected and 70 clinical cases of feline babesiosis. Total serum proteins remained unchanged but there was a definite increase in gamma globulin and decrease in alpha and beta globulins. In most cases liver function was essentially normal although function tests occasionally indicated hepatic dysfunction. Renal function was unaffected. Venous blood pH remained normal throughout. Post mortem findings on the experimental cats included bile stasis and hepatic necrosis in some; marked internal icterus was only seen in 2 cases.

Studies of feline babesiosis 3. Haematological findings.

Haematological changes were monitored in 20 experimentally infected and 70 clinical cases of feline babesiosis. There was a rapid drop in the haematocrit, haemoglobin and erythrocyte count. Experimental animals were most anaemic about 3 weeks after infection. Variations were encountered. There were no definite trends in the erythrocyte indices although the erythrocytes were often macrocytic and hypochromic. No significant changes were found in total leukocyte counts.

Studies on feline babesiosis. 2. Clinical observations.

Clinical observations were made on 20 experimentally infected and 70 clinical cases of feline babesiosis. The experimental cats showed a remarkable ability to adapt to the disease. Lethargy, anorexia and anaemia were recorded in both groups. Icterus was only occasionally seen. Elevated body temperature was not a feature of the disease. All untreated animals eventually died. Blood smears revealed increased polychromatophils, Howell-Jolly bodies, nucleated erythrocytes and anisocytosis indicative of a regenerative anaemia. Erythrophagocytosis by monocytic type leucocytes was also observed.

The use of faecal analyses to estimate the phosphorus intake by grazing sheep. I. The use of pool instead of individual samples.

Analyses of rectal faeces of sheep for phosphorus, calcium and magnesium may be useful to indicate the mineral status of the herbage being consumed. A number of sheep should be used for each pasture, but this would entail a large number of individual analyses. In this experiment it was shown that a pool analysis of faeces did not differ significantly (P less than 0.01) from the arithmetic mean of the individual samples (20). In 13 replications this was true for phosphorus, calcium and magnesium, whether the sheep were non-pregnant, non-lactating, pregnant, or lactating. From the results it was estimated that 3 faecal pellets from at least 30 sheep should be used to make the pool. Blood was also taken on 11 occasions for pool and individual (20) analyses. No significant difference was found for plasma inorganic phosphate, magnesium and total protein, but on 3 occasions there was a significant difference (P less than 0,01) for plasma calcium.

The use of faecal analyses to estimate the phosphorus intake by grazing sheep. II. The repeatibility of the technique and the influence of varying the phosphorus intake.

Fifty sheep received a pelleted ration containing between 0,31 and 0,38% phosphorus. Pooled faecal samples, composed of 3 faecal pellets from 30 randomly selected sheep, were taken on 15 occasions during 23 days. The faecal phosphorus levels of the 15 pooled samples were remarkably constant with a mean of 0,94% and a coefficient of variation of 6,38%. However, when the animals the faecal phosphorus levels above and below the limits set in the repeatabilty trial. There was also a rise in faecal phosphorus when the total food intake was halved. The faecal samples were also analysed for calcium and magnesium.

The relationship between total and ionized calcium in the blood sheep when calcium levels are altered.

In a series of eight experiments attempts were made to change the levels of calcium in the blood of sheep by intravenous infusions of calcium, EDTA and thyrocalcitonin or changing the acid-base balance by various means. When total calcium levels changed these changes were mirrored closely by changes in the physiologically important ionized calcium fraction (r = 0.839). It is concluded that the total calcium determinations remain valuable indicators of changes in the physiological level of calcium in the blood.

The effect of different dietary levels of Ca and P on the plasma Ca, inorganic P and Mg as well as the ash, Ca, P and Mg content of cervical vertebrae and total body of sheep.

Six 14 month old rams were divided equally into three groups and received either a high Ca (1,102% Ca : 0,192% P : 0,128% Mg), control (0,322% Ca : 0,311=P : 0,128% Mg) or high P (0,127% Ca : 1,043% P: 0,130% Mg) diet in pellected form for 150 days. 2. Dry mass and ash % of the third cervical vertebra decreased as Ca intake decreased while fat % increased. There was a highly significant negative correlation (= -0,992) between bone ash% and bone fat %. Bone P and Mg showed no particular trends. 3. Total body Ca and P as well as % body Ca and P all decreased with a decrease in dietary Ca and increase in dietary P intake. Body Mg showed no particular trend. 4. The results suggest that while plasma values may be useful in assessing the P intake of sheep on natural pastures, bone and total body P may not be.

Aspects of forced exercise and the therapy thereof in sheep.

Sixteen Merino sheep were subjected to forced exercise after which half were treated with sodium bicarbonate, vitamin B complex, antibiotics and a glucocorticoid. Cardiac rate, rectal temperature and blood were taken from all the animals before, immediately after and again two and five hours after exercise. Exercise resulted in increased cardiac cardiac rate, rectal temperature, plasma levels of glucose, lactate, lactate dehydrogenase, creatine kinase, potassium, and decreased levels of blood pH, buffer base, bicarbonate, base excess and CO2. Compared with the controls, the therapy increased plasma glucose and blood pH, buffer base, bicarbonate and base excess, while there was a significant decrease in plasma potassium. This latter effect may be important in the therapy of capture myopathy in wild animals as hyperkalaemia may be one of the causes of death in the syndrome.

A review of the influence of nutrition upon the oestrous cycle and early pregnancy in the mare.

Attention is drawn to the beneficial effect of improved nutrition during winter and early spring on the ovarian activity of mares. Furthermore, the necessity of an adequate plane of nutrition during early pregnancy to prevent embryonic resorption is stressed.