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Biomedical subjects

N McIntosh

Publications and source records attributed to N McIntosh.

At least 127 records · Page 7Linked to original sources
PubMed1986

Outcome of neonatal intensive care: obstetric implications for a regional service.

Data from 634 newborn babies with birthweights less than or equal to 2000 g admitted to the South West Thames Regional Neonatal Unit in St George's Hospital since its opening in 1980 were analysed. Only 271 (43%) of the pregnancies were booked there; 200 (32%) of the babies were transferred in utero and 162 (26%) after delivery. Weight-specific neonatal survival rates, calculated after exclusion of lethal abnormalities showed that between 1001 and 1500 g, 79 (96%) of the 82 babies transferred in utero survived in 1981-1984, compared with only 57 (79%) of the 72 postnatal transfers (P less than 0.02). Under 1000 g, no such differences were found, possibly because paediatricians transferred only the fitter babies in this weight range. The birth of very-low-birthweight babies of short gestation in units unable to provide immediate resuscitation, adequate stabilization and full neonatal intensive care is a major risk factor for increased neonatal mortality. These findings support the role of regional perinatal centres as service units for antenatal transfer and neonatal intensive care, and as teaching centres.

Birth Weight↗
PubMed1985

Rectal aminophylline in the management of apnoea of prematurity.

Rectal suppositories as an alternative to intravenous aminophylline in the management of recurrent apnoea were studied in 41 preterm infants of mean gestation 28.3 weeks and mean birthweight 1176 g. Therapeutic blood concentrations were obtained two hours after a rectal loading dose of 10 mg/kg, with steady concentrations and maximum reduction in apnoeic episodes (from a mean of 0.5 per hour to 0.09 per hour) within 24 hours on a maintenance dose of 10 mg/kg/day. There was good correlation between the rectal dose and the plasma theophylline concentration. Several infants showed a significant reduction in Pco2 when treated with aminophylline. Side effects were related to the plasma theophylline concentration and were not seen at concentrations less than 14 mg/l.

Aminophylline↗
PubMed1985

Incubator temperature control: effects on the very low birthweight infant.

We studied temperature stability in 22 infants of birthweight less than 1500 g in the first four days of life. Infants were nursed in incubators using either air mode control or skin temperature servo control. Data were collected continuously using a computer linked monitoring system. Skin temperature control resulted in a less stable thermal environment than air mode control. Increased thermal stability in the incubator on air mode control may well be beneficial, particularly to sick, very low birthweight infants.

Feedback↗
PubMed1985

Serial measurement of plasma arginine vasopressin in the newborn.

Plasma arginine vasopressin was measured serially in 11 preterm infants and one asphyxiated, term infant. The samples were taken through umbilical arterial catheters placed at birth for blood gas measurements because ventilatory support was required. Plasma samples of 200 to 300 microliter were taken 4 to 12 hourly for up to 100 hours after birth. Plasma arginine vasopressin was measured by a cytochemical bioassay. A significant correlation between plasma arginine vasopressin and plasma osmolality was found in only two out of six infants. The normal 'resting' concentration was between 0.5 and 2 pg/ml. In five infants, apparent bursts of arginine vasopressin secretion were seen, and in one spontaneously breathing infant with respiratory distress, continuously high concentrations (12 to 25 pg/ml) were recorded over the first 100 hours.

Aging↗
PubMed1984

Specificity of a cytochemical bioassay for arginine-vasopressin and its validation for plasma measurement.

The total Na+/K+ ATP-ase activity of the thick ascending limb of the loop of Henle may be stimulated by arginine-vasopressin (AVP). Lysine-vasopressin (LVP), oxytocin (OT), and arginine-vasotocin (AVT) produce less than 5% of the enzyme activity induced by the same concentration of AVP. Physiological concentrations of a mixture of other hormones with known activity on the kidney (T3, T4, aldosterone, angiotensin II, and OT) did not significantly increase total Na+/K+ ATP-ase activity. Specific AVP antiserum consistently removed greater than 90% of the stimulatory effect of plasma. The concentration of AVP in plasmas from dehydrated subjects was greater than 10 times that of the same subjects hydrated. Intra-assay coefficient of variation was 35% and 52% from 200 microliters and 20 microliters of plasma respectively. The interassay coefficient of variation was 53% and 55% from plasma pools with high and low AVP content.

Animals↗
PubMed1984

Hypercalcaemia in extremely low birthweight infants.

We report 10 cases of hypercalcaemia associated with hypophosphataemia in the first two weeks of life in extremely low birthweight infants (birthweight less than 1000 g). At the time of diagnosis, the infants were fed mainly with expressed breast milk but they had also received intravenous nutrition. After treatment with additional phosphate plasma calcium concentrations returned to normal. There was a high incidence of rickets of prematurity in these infants.

Calcium↗
PubMed1984

Calcium and phosphorus balance in extremely low birthweight infants in the first six weeks of life.

The absorption and retention of calcium and phosphorus in infants of 28 weeks' gestation, or less, who were fed either breast milk or a preterm formula, were determined in 22 balance studies. Breast milk contained significantly lower amounts of calcium and phosphorus than the formula milk. The percentage absorption of calcium was similar in the two groups, but the infants fed breast milk had greater urinary calcium losses and significantly lower calcium retention than the group fed formula milk. The percentage phosphate absorption was also similar in the two groups but because of the higher phosphate intake in the formula milk this group retained a significantly greater amount of phosphate. The extremely low birthweight infants fed on breast milk were phosphorus depleted, with low plasma phosphate concentrations, and seemed to retain as much phosphate as possible. The hypophosphataemia may result in reduced deposition of calcium in bone and explain the calciuria in the breast fed infants. Substrate deficiency may be an important factor in the aetiology of rickets of prematurity and, particularly if breast milk is used, preterm infants may require calcium and phosphate supplements from an early age.

Aging↗
PubMed1984

Plasma amino acids of the mid-trimester human fetus.

The amino acid concentrations in umbilical cord plasma taken at fetoscopy were measured from 12 fetuses between 18 and 29 weeks gestation. Concurrent maternal plasma levels were measured. Fetal plasma showed consistently higher concentrations of plasma amino acids with the ratios varying between 1.1:1 and 3:1 and the difference always reached statistical significance. It is suggested that these results reflect the in vivo situation of the mid-trimester human fetus.

Amino Acids↗
PubMed1983

Intravenous metronidazole in the newborn.

Twenty four neonates at high risk of anaerobic sepsis were treated with intravenous metronidazole, 7.5 mg/kg, 8 hourly, for a mean period of 5 days. The highest observed concentration after the first dose (mean +/- SD) 9.6 +/- 4.0 mg/l (56.1 +/- 23.4 mumol/l) was significantly lower (P less than 0.001) than the highest observed concentration after the final dose (mean +/- SD) 19.3 +/- 8.6 mg/l (112.7 +/- 50.2 mumol/l). The overall metronidazole half life was (mean +/- SD) 23.4 +/- 13.1 hours. The half life after the first dose (mean +/- SD) 21.9 +/- 10.1 hours was not appreciably different from the half life after the final dose (mean +/- SD) 21.6 +/- 12.4 hours. The concentrations of the major metabolite of metronidazole (20396RP) also rose appreciably during treatment. No side effects of metronidazole were noted and its extended half life in neonates suggests that less frequent dosage would be appropriate.

Bacterial Infections↗
PubMed1983

Neurohypophysial peptides in the human fetus: presence in pituitary extracts of immunoreactive arginine-vasotocin.

A specific and sensitive radioimmunoassay was used to demonstrate the presence of arginine-vasotocin (AVT) in human fetal pituitary extracts. The mean pituitary contents of AVT in extracts of 70-101, 102-136 and 137-172 days gestation were 0.32, 0.8 and 8.1 ng/gland respectively. Combined high-pressure liquid chromatography (HPLC) and radioimmunoassay of pooled extracts at these gestational ages confirmed the presence of AVT. Radioimmunoassay of neonatal pituitary extracts (240-280 days) did not conclusively show AVT to be present, as the material assayed did not show parallelism with dilution. However, combined HPLC and radioimmunoassay of pooled extracts at this gestational age did demonstrate the presence of an immunoreactive AVT peak. Radioimmunoassay analysis of this peak indicated that a relatively small amount of AVT (at least 0.5 ng/gland) was present in the human pituitary gland at term.

Arginine Vasopressin↗