Biomedical subjects
Publications and source records attributed to J C Shaw.
A patient with multiple keratoacanthomas was successfully treated with oral isotretinoin. The treatment resulted in clearing of existing keratoacanthomas and prevented the development of new lesions. An induction dose of 1.5 mg/kg/day was necessary to initiate the response. This is the third report of successful treatment of multiple keratoacanthomas with isotretinoin.
We have used a sintered glass bead core to simulate the spaces and surfaces of reservoir rock in studies of the bacterial plugging phenomenon that affects waterflood oil recovery operations. The passage of pure or mixed natural populations of bacteria through this solid matrix was initially seen to promote the formation of adherent bacterial microcolonies on available surfaces. Bacteria within these microcolonies produced huge amounts of exopolysaccharides and coalesced to form a confluent plugging biofilm that eventually caused a >99% decrease in core permeability. Aerobic bacteria developed a plugging biofilm on the inlet face of the core, facultative anaerobes plugged throughout the core, and dead bacteria did not effectively plug the narrow (33-mum) spaces of this solid matrix because they neither adhered extensively to surfaces nor produced the extensive exopolysaccharides characteristic of living cells. The presence of particles in the water used in these experiments rapidly decreased the core permeability because they became trapped in the developing biofilm and accelerated the plugging of pore spaces. Once established, cells within the bacterial biofilm could be killed by treatment with a biocide (isothiazalone), but their essentially inert carbohydrate biofilm matrix persisted and continued to plug the pore spaces, whereas treatment with 5% sodium hypochlorite killed the bacteria, dissolved the exopolysaccharide biofilm matrix, and restored permeability to these plugged glass bead cores.
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The measurement of EEG-brain function relationship using measures of EEG amplitude are well known. The application of signal correlation techniques to this problem are less well understood. Selective aspects of EEG signal correlation are described with examples, and their relevance to EEG measurement is discussed.
Porokeratosis plantaris palmaris et disseminata (PPPD) is a rare variant of porokeratosis. We report a second kinship with PPPD that typically appears first on the palms and soles and then gradually progresses to the extremities and trunk. We discuss clinical, histologic, pathogenetic, and therapeutic aspects of PPPD and review the literature concerning the histogenesis of cornoid lamella formation.
A 63-year-old white woman with perioral dermatitis, a sore tongue, and an erythematous dermatosis in the inframammary and perineal regions underwent surgical removal of a pancreatic glucagonoma. The patient's plasma and pooled normal human plasma containing Sigma glucagon were fed to human keratinocyte cultures and increased arachidonic acid levels by 300% and 200%, respectively, when compared to pooled normal human plasma with no added commercial glucagon. These experiments suggest that glucagon may increase inflammatory mediators such as arachidonic acid and its metabolites in the epidermis, causing the skin lesions seen in the glucagonoma syndrome.
Performance on the rod and frame test (RFT) was measured over three separate occasions in three groups of 20 depressive patients and a nonpatient control group. Depressive patients were selected into three groups according to whether they had been prescribed one of three forms of treatment: bilateral electroconvulsive therapy (ECT), nondominant unilateral ECT, or a course of antidepressant drugs. The RFT was administered on three occasions: before treatment, 1 week after completion of treatment, and at 3 months follow-up. The control group received no treatment, but were tested at comparable periods. The RFT was scored as mean absolute error and also as separate frame-dependent, rod-dependent, and constant error components. All depressive groups showed improved error measures post-treatment. The two ECT groups showed less frame dependence post-treatment than the drug group. The group receiving bilateral ECT showed a greater decrease in the mean error of performance than the unilateral group. Right-sided unilateral ECT affected frame dependence in patients who were initially frame independent, rather than in those who were initially frame dependent. The results indicated that the effect of ECT may depend on a patient's initial pretreatment cognitive style.
Continuous sequential urinary arginine vasopressin measurements in 14 preterm, ventilated infants suggest that both osmoreceptor and volume receptor systems are able to stimulate the prolonged secretion of arginine vasopressin from 26 weeks' gestation. The kidney is able to respond to arginine vasopressin stimulation from the first day of life and from 26 weeks' gestation. A maximum urine osmolality not exceeding 550 mOsm/kg was reached which varied with hydration of the infant. Excretion of arginine vasopressin and urine osmolality increased during deterioration of respiratory illness, mask ventilation, bilateral pneumothoraces, and severe intraventricular haemorrhage. The data show that inappropriate arginine vasopressin secretion is common during illness in the first week of life in preterm infants and that strict attention must be paid to water balance during this time.
Serial measurements of plasma sodium, sodium balance, water intake, and urine volume were made for a mean period of 5.9 days in 10 preterm infants of mean gestation 30.5 weeks and mean birthweight 1506 g. In five infants weighed regularly, estimates of insensible water loss averaged 2.6 (range 1.4 to 6.2) ml/kg/hour. High insensible water losses were the cause of hypernatraemia that occurred in two of the 10 infants. Net sodium balance was negative during the study and represented contraction of the extracellular fluid volume associated with weight loss. The negative sodium balance did not seem diminished by increasing sodium intake and there was no evidence that sodium intake need exceed 3 to 4 mmol/kg/day. Hyponatraemia was not due to changes in sodium balance but to water retention associated with inappropriate increases in urinary arginine vasopressin excretion and urine osmolality in 8 of 10 infants. Frequent, accurate measurements of body weight and of plasma sodium are the two most reliable indicators of changes in water balance.
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The EEG synchrony between hemispheres during cognitive activity differs from that during rest. With common reference recording and a visual imagery task it increases in healthy right-handers and neurotic patients, and it decreases in healthy left-handers and schizophrenic patients. It is suggested that this implies a less lateralized brain organization in schizophrenia which may account for the often reported association with left-handedness. When associated with impaired corpus callosum transmission, it may contribute to the disturbed behaviour and thought processes in this condition.
A micromethod is described for the analysis of zinc in plasma or serum by electrothermal atomisation and graphite furnace utilising less than 20 microliters sample volume. The sample matrix introduced an error when aqueous standards were used. Therefore standards were made up in serum which had been treated with Chelex 100 to remove as much zinc as possible. The residual zinc (less than 0.125 mg/l) was determined by flame analysis using the method of additions and each standard assigned a value equal to the sum of the residual zinc and the amount added. Furnace analyses using standards made up in Chelex-treated serum compared favourably with flame analyses over the whole range, and recovery experiments gave 98 +/- 2% of the expected value with 95 +/- 6% recovery of the added zinc. The within-batch coefficient of variation was 2.5%, day-to-day variation 5.6%. The mean concentration of zinc in paired samples of plasma and serum from 50 adults analysed by flame with viscosity-matched aqueous standards were: plasma (mean +/- SD) 0.821 +/- 0.085 mg/l; serum 0.821 +/- 0.07 mg/l. The same samples were analysed in the graphite furnace using serum standards, and the results were: plasma 0.812 +/- 0.082 mg/l; serum 0.815 +/- 0.08 mg/l. In contrast to earlier reports we were unable to demonstrate a significant difference between plasma and serum zinc concentration in the paired samples.
The elements zinc, copper, manganese, molybdenum, selenium and chromium are considered to be essential nutrients in man. It is known that they cross the placenta because they are all present in fetal bodies where they are presumably necessary for normal growth and development. Though deficiency of copper, zinc, selenium and chromium have been reported in man only copper and zinc deficiency have been described in premature infants. Typically, the deficiency develops late (between 3-6 months of age), at a time when the concentration in breastmilk is falling and before a mixed diet has been introduced. This late onset, together with data on body composition, suggests that preterm infants are born with stores--albeit small--of copper and zinc, as they are with iron. The stores may be depleted to a variable extent following birth by dietary insufficiency (particularly total parenteral nutrition), malabsorption and diarrhoea. This leads to severe deficiency in some infants and possibly less severe deficiency in many more, which may pass unrecognised because of difficulties in diagnosis. Dietary provision of a trace element should have two purposes. It should be sufficient to prevent the development of a deficiency state, and to provide enough to enable stores to be formed so that deficiency does not immediately occur if the diet is temporarily inadequate. No case of manganese, molybdenum, selenium or chromium deficiency has yet been described in preterm infants, but no systematic search for deficiency of these elements has yet been undertaken.
The amount of iron in a 1.0 kg preterm infant at birth is sufficient to synthesise only about 18.0 grams of haemoglobin. Since breast milk contains only 40 microgramsFe/100 ml, anaemia will develop in a premature baby fed breast milk unless supplementary iron is given. Preterm infants fed on breast milk are in negative iron balance averaging -0.24 mg/kg X day for at least thirty days after birth, and it can be estimated that they require an intake of about 0.6 mg/kg X day to compensate for obligatory intestinal iron losses. Insensible skin losses, estimated from measurements in adults, are small--of the order of 0.02 micrograms/kg X day, but losses due to venesection may be considerable since each gram of haemoglobin contains 3.4 mg of iron. Absorption of supplementary iron by preterm infants is a linear function of intake, which suggests immature control of iron absorption. Giving blood transfusions seem to diminish iron absorption but may not prevent it altogether. Giving repeated blood transfusions results in high serum ferritin levels similar to those seen in iron overload--however these levels decline spontaneously with age. Preterm infants who are given repeated transfusions do not require iron supplements until the transfusions cease.
Over five weeks 136 out of 246 deliveries were studied. Maternal plasma sodium concentrations were normal at admission. At delivery no significant difference was found between maternal and infant cord plasma sodium concentrations. Twenty-four of the 41 mothers who had received only oral fluids during labour had infants whose cord plasma sodium concentrations were normal. Of the 95 mothers who had been given intravenous fluids, however, only 14 infants with normal plasma sodium concentrations, 31 had a concentrations of 130 mmol (mEq)/1 or less and nine of these had a concentration of 125 mmol/1 or less. There was a highly significant inverse relation between cord plasma sodium concentration and rate of fluid administration, suggesting that hyponatraemia was due to intravenous treatment with predominantly sodium-free solutions. Endogenous antidiuretic activity probably increases during labour, and synthetic oxytocin in large doses has been shown to have an antidiuretic effect. The dose used in this study did not appear to have such an effect. Glucose solutions are often used as a vehicle for oxytocin; 83% of all fluid intake in this study was 5% or 10% glucose in water. Fluid balance in labour should be supervised closely, and oxytocin should be given in a more concentrated solution.
A whole-blood technique was used to measure simultaneously neutrophil migration, uptake, and killing of candida in 27 premature infants of low birth weight (less than 1500 g). Neutrophil migration was consistently reduced, especially in the first two weeks of life. Phagocytosis was also reduced, particularly in the first week of life and in sick patients. Killing was usually normal, except in sick patients. The three functions were not altered when the test was performed in normal adult, rather than autologous, plasma, and the reduced migration and uptake are therefore the result of an intrinsic defect of the cell. The results clarify the previous controversy concerning neutrophil function in premature infants and provide an explanation for their increased susceptibility to infection.
Nitrogen metabolism was studied in three preterm infants (mean gestation 32 wk) by the method of consecutive metabolic balance. The absorption and retention of nitrogen from breast milk was measured, and protein turnover, synthesis, and breakdown were calculated from isotopic plateau of urinary urea and ammonia using an intermittent oral administration of 15N-glycine. Weight gain and nitrogen retention were compared with the weight gain and nitrogen accumulated for a foetus of equivalent gestational age in utero. The average composition of the milk was 289 +/- 19 KJ dl-1 and 1.44 +/- 24 g protein dl-1. The intake of energy was 572 +/- 61 KJ kg-1 day -1 and of nitrogen 447 +/- 99 mg kg-1 day-1. Stool output of nitrogen was 100 +/- 32 mg kg-1 day-1 giving an absorption of 348 +/- 78 mg kg-1 day-1, as urinary excretion was 91 +/- 17 mg kg-1 day-1 retained nitrogen was 256 +/- 71 mg kg-1 day-1, or 56% of intake. The specific weight gain was 15.6 +/- 2.6 g kg-1 day-1 and 53% of this comprised lean tissue (range 34 to 89%). In all but one study the postnatal retention of nitrogen fell far short of calculated in utero accumulation. The results of protein turnover were surprising. In six of the eight studies urinary urea failed to become enriched at all. Protein turnover calculated from the ammonia plateau was 1.94 +/- 0.54 g nitrogen kg-1 day-1, synthesis 10.9 +/- 3.4 g protein kg-1 day-1 and breakdown 9.3 +/- 3.4 g protein kg-1 day-1. It is concluded that the amino acid composition of breast milk may be inappropriate for supporting rates of lean tissue deposition equivalent to in utero accumulation.
The coherence function quantifies the association between pairs of signals as a function of frequency and has been shown to be useful for measuring changes in EEG topography related to cognitive tasks, psychopathology, and other aspects of brain organisation. For a narrow frequency band, its magnitude is analogous to the correlation coefficient between the signals limited by that band, but its value may differ because of the way that smoothing over frequency is achieved. The coherence function is described in physical terms using simple waveforms.