Biomedical subjects
Publications and source records attributed to C Malan.
[reaction--see text] The synthesis of new phosphonites with a chiral paracyclophane backbone is described. The rhodium complexes derived from the phosphonites bearing biphenoxy and binaphthoxy substituents are highly active and highly selective catalysts for the asymmetric hydrogenation of dehydroamino acids and esters.
PhanePhos-ruthenium-diamine complexes catalyze the asymmetric hydrogenation of a wide range of aromatic, heteroaromatic, and alpha, beta-unsaturated ketones with high activity and excellent enantioselectivity.
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The simultaneous determination of cerebrospinal fluid (CSF) and plasma adenosine deaminase (ADA) activity was evaluated as a diagnostic aid in tuberculous meningitis (TBM). CSF and plasma ADA activity were determined in four groups of patients: (i) a 'no meningitis' group of 174 children investigated for possible meningitis, but found to be uninfected; (ii) an aseptic meningitis group of 40 children; (iii) a bacterial meningitis group of 31 children; and (iv) a TBM group of 27 patients (24 children and 3 adults). CSF ADA alone was determined in a further 23 children with aseptic meningitis, 19 with bacterial meningitis and 13 children and 7 adults with TBM. Both the CSF/plasma ADA ratio and the absolute CSF ADA activity were raised in TBM (mean values 0,24 and 12,61 U/I respectively) and bacterial meningitis (mean values 0,59 and 15,43 U/I respectively), but not in the aseptic meningitis group (mean values 0,06 and 2,00 U/I) or the 'no meningitis' group (mean values 0,04 and 1,51 U/I). Both values will distinguish TBM from aseptic meningitis, but do not appear to hold any marked advantages over conventional CSF criteria in the diagnosis of TBM.
The value of cerebrospinal fluid (CSF) lactate and lactate dehydrogenase (LD) activity in the rapid diagnosis of meningitis was investigated in three groups of patients--a 'no meningitis', an aseptic meningitis and a bacterial meningitis group. The sensitivity achieved in the detection of bacterial meningitis by CSF lactate values of 2.85 mmol/l (93.8%) and 3.9 mmol/l (89.6%) was greater than that reached by conventional chemical investigations using a CSF protein value of 1 g/l (81.5%) or a CSF glucose value of 2.2 mmol/l (68.8%) as the indicator. The sensitivity of an absolute CSF LD value of 40 U/l (86.3%) in the detection of bacterial meningitis was slightly lower than that of a CSF protein value of 1 g/l (87%) and better than the sensitivity of either a CSF/serum LD ratio of 0.1:1.0 (83.9%) or a CSF glucose level of 2.2 mmol/l (76.3%). As with conventional CSF chemistry, both investigations may give normal values in the presence of bacterial meningitis.
The value of cerebrospinal fluid (CSF) lactate and lactate dehydrogenase (LD) values as aids in differentiating tuberculous meningitis (TBM) from aseptic meningitis has been investigated. Using an upper limit of normal for CSF lactate levels of 2,75 mmol/l resulted in detection of 24 out of 26 cases of TBM (a sensitivity of 92%). If, however, a level of 3,85 mmol/l was taken as the upper limit of normal, then 18 out of 26 cases were detected (a sensitivity of 69%). Using 40 U/l as the upper limit of normal for LD levels detected 21 out of 38 cases of TBM (a sensitivity of 55%). Both tests may give normal values in the presence of TBM, but this should not cause specific antituberculosis therapy to be withheld. Neither test appears to hold marked advantages over conventional chemical analysis of CSF in differentiating TBM from aseptic meningitis.
The prognosis of tuberculous meningitis is closely linked to the stage at which treatment is started. At the same time the diagnosis will often have to be made on purely circumstantial evidence. Adenosine deaminase activity in the cerebrospinal fluid was evaluated as a diagnostic aid in 30 cases of tuberculous meningitis. Cerebrospinal fluid adenosine deaminase levels differentiated tuberculous meningitis cases from those with aseptic meningitis being higher than 4 U/l in all and higher than 6 U/l in 90% of cases of tuberculous meningitis, but lower than 6 U/l in aseptic meningitis and less than 4 U/l in normal controls. It could not distinguish bacterial meningitis from tuberculous or aseptic meningitis. In cases of low-cell-count bacterial meningitis, the mean cerebrospinal fluid adenosine deaminase level was significantly lower than in cases of tuberculous meningitis with a similar cell count, but considerable overlap of results in the two groups was still to be found.
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Adenosine deaminase (ADA) estimations were performed on the pleural fluid from 368 effusions. The mean (+/-SD) ADA concentration in tuberculous effusions was 92,11 +/- 37,05 U/l, and these values were found to be highly statistically different from the 23,23 +/- 13,15 U/l in secondary malignant tumours of the pleura, the 34,86 +/- 14,2 U/l in mesotheliomas, and the 23,81 +/- 15,07 U/l in pulmonary embolism. The ADA values of 64,3 +/- 44,95 U/l in lymphoproliferative disorders were less significantly different. No statistical difference could be found between values in the tuberculous group and the ADA levels of 97,57 +/- 82 U/l found in para-infective effusions, but these could be distinguished from each other by microscopic examination of the pleural fluid. The importance of ADA estimations in the diagnosis and differentiation of tuberculous effusions is discussed and the role of microscopy is emphasized.
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One hundred and thirty-one small-for-dates Cape Coloured newborns and their mothers were compared with 81 appropriately grown Cape Coloured newborns and their mothers in order to determine aetiological factors in intra-uterine growth retardation. The mothers of the small-for-dates babies differed from the control mothers in the following respects: their postpartum weight and weight for height were less, their placentas were lighter, their incomes were lower, they smoked more heavily, attended antenatal clinics less frequently, and their social conditions, educational status, dietary intake, weight gain during pregnancy and attitude towards pregnancy were inferior. Their previous babies weighed less than the previous babies of control mothers. The study mothers, however, had higher total serum protein, serum albumin and haematocrit levels, which can probably be explained by a smaller plasma volume expansion. The VDRL test on cord blood was more often positive in study babies, but the mean cord blood IgM level did not differ in study and control babies. It is concluded that socio-economic factors play a major role in the aetiology of small-for-dates babies in the Cape Coloured population. Controlled trials of dietary supplementation seem to be indicated in high-risk mothers in this population group.
Human placental lactogen (HPL) and urinary and serum oestriol levels were studied in patients in whom the contraction stress test was positive. After birth the infants were assessed for growth retardation. Low HPL, serum oestriol and urinary oestrogen levels were found in 66%, 30% and 15% of patients respectively. Gestational ages were known in 148 patients, of whom 72 (49%) had infants whose weights were below the 10th percentile for gestational age. HPL values were low in 81% of mothers who gave birth to growth-retarded infants, but serum and urinary oestriol levels were low in only 43% and 21% respectively. When both a positive stress test and a low HPL value were present, 69% of infants were growth retarded. The incidence of growth retardation rose to 85% when both HPL and serum oestriol levels were abnormal in patients with positive contraction stress tests. In this study estimation of HPL levels was found to be superior to that of oestrogen levels in detecting growth-retarded infants.
Infestation of humans with the parasite Ascaris lumbricoides may induce high total serum IgE levels, but the influence of this immunogenic response on allergic asthma has not been defined. In this study, the specific antiparasitic IgE-mediated response as determined by skin-prick testing was related to the incidence of allergic asthma in Ascaris-infested patients. A limited number--17% of the non-allergic controls and 51% of the allergic asthmatics--had a clinically detectable immunogenic response to the parasite. The predicted incidence of asthma was significantly higher than the observed incidence in the subjects in whom the Ascaris skin test was positive. This was not found in subjects in whom the Ascaris skin test was negative. Inhalation of Ascaris antigen induced asthmatic reactions in 7 of 8 patients who were Ascaris-positive on skin testing, but not in the negative controls. The groups of patients who respond immunogenically to parasite infestation need to be defined, as they may be predisposed to allergic diseases such as asthma.
The relationshop between the concentration of alpha1-fetoprotein (AFP) in cord blood and neonatal jaundice has been examined in 259 neonates. Cord blood AFP varies inversely with gestational age, as does the incidence of severe jaundice. Among babies born at term a higher mean AFP concentration in cord blood was found in the group which subsequently developed marked hyperbilirubinaemia. On average, the full-term babies with a cord blood AFP level above 130 mg/l developed more pronounced jaundice than the rest. We conclude that cord blood AFP concentrations reflect the maturity of the liver in both premature and full-term infants. It is a better criterion than the estimation of gestational period by physical examination of the baby.
Two siblings who were repeatedly admitted to hospital with acute episodes of vomiting, dehydration and coma were found to be suffering from isovaleric acidaemia. This condition is a rare inherited abnormality of leucine metabolism, which is frequently fatal in the early weeks of life and leads to mental retardation in a high proportion of those who survive early attacts. However, both our patients were of normal intelligence. The clinical presentation, biochemical defect, diagnosis and suggested therapies are reviewed.
Plasma growth hormone (HGH) response to insulin-induced hypoglycemia was assessed in a group of normal adult volunteers, with and without prior consumption of ethanol. A significant difference was found in peak HGH concentrations on the two occasions, indicating that prior consumption of ethanol attenuates the normal HGH response to insulin-induced hypoglycemia. It is suggested that ethanol may deplete catecholamine stores in the neurons of the ventromedial nucleus of the hypothalamus and may thereby impair secretion of growth hormone releasing factor. Under certain circumstances this could be of importance in the pathogenesis of alcohol-induced hypoglycemia.
The relationship between urinary excretion of porphyrins, porphyrin precursors and total oestrogens in normal pregnancy was investigated. Significant increases in total oestrogen, delta-aminolaevulinic acid (ALA) and coproporphyrin (COPRO) excretion were noted. However, no close correlation was found between total oestrogen excretion and urinary output of ALA and COPRO. The results suggest that the observed increases in ALA and COPRO excretion during pregnancy may not simply be the result of steroid-mediated induction of hepatic haem biosynthesis, as has been proposed.
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