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Biomedical subjects

R Haslam

Publications and source records attributed to R Haslam.

35 records · Page 2Linked to original sources
PubMed1996

An optimized model for rat liver perfusion studies.

Conditions which influence the viability, integrity, and extraction efficiency of the isolated perfused rat liver were examined to establish optimal conditions for subsequent work in reperfusion injury studies including the choice of buffer, use of oncotic agents, hematocrit, perfusion flow rate, and pressure. Rat livers were perfused with MOPS-buffered Ringer solution with or without erythrocytes. Perfusates were collected and analyzed for blood gases, electrolytes, enzymes, radioactivity in MID studies, and lignocaine in extraction studies. Liver tissue was sampled for histological examinations, and wet:dry weight of the liver was also determined. MOPS-buffered Ringer solution was found to be superior to Krebs bicarbonate buffer, in terms of pH control and buffering capacity, especially during any prolonged period of liver perfusion. A pH of 7. 2 is chosen for perfusion since this is the physiological pH of the portal blood. The presence of albumin was important as an oncotic agent, particularly when erythrocytes were used in the perfusate. Perfusion pressure, resistance, and vascular volume are flow-dependent and the inclusion of erythrocytes in the perfusate substantially altered the flow characteristics for perfusion pressure and resistance but not vascular volume. Lignocaine extraction was relatively flow-independent. Perfusion injury as defined by enzyme release and tissue fine structure was closely related to the supply of O2. The optimal conditions for liver perfusion depend upon an adequate supply of oxygen. This can be achieved by using either erythrocyte-free perfusate at a flow rate greater than 6 ml/min/g liver or a 20% erythrocyte-containing perfusate at 2 ml/min/g.

Animals↗
PubMed1996

An airborne intensive care facility (fixed wing).

A fixed-wing aircraft (Beechcraft KingAir B200 C) fitted as an airborne intensive care facility is described. It completed 2000 missions from 1987-1992 for distances up to 1300 km. Features include: 1. Space for carriage of two stretchers, medical cabin crew of up to five persons and equipment and two-pilot operation if necessary. A third stretcher may be carried in emergencies. 2. Two CARDIOCAP (TM) fixed monitors for ECG, invasive and noninvasive pressures pulse oximetry and end-tidal C02 plus SIEMENS 630(TM)/PROPAQ(TM) compact monitors for the ground transport phase of missions, or the total duration. 3. A medical oxygen reservoir of 4650 litres sufficient for two patients on IPPV with FiO2 = 1.0 for a four-hour trip. The medical suction system is powered from the engine or a vacuum pump. 4. Other medical equipment and drugs in portable packs, for ground transport and resuscitation needs and for replenishment by nursing staff at the parent hospitals. 5. Stretchers compatible with helicopter and road ambulance vehicles used. 6. A stretcher loading device energized from the aircraft, operating through a wide (cargo) door. 7. Provision of 24Ov AC (alternating current) and 28v DC (direct current) electrical energy. 8. Pressurization and climate control. 9. Satisfactory aviation performance for conditions encountered, with single-pilot operation.

Air Ambulances↗
PubMed1995

Thyrotropin-releasing hormone: does two hundred micrograms provide effective stimulation to the preterm fetal pituitary gland compared with four hundred micrograms?

OBJECTIVE: Our purpose was to compare the response of the fetal pituitary-thyroid axis to 200 and 400 micrograms of thyrotropin-releasing hormone administered to the mother immediately before delivery with a control group. STUDY DESIGN: A randomized controlled trial was conducted of 26 women at gestational ages between 24 weeks and 33 weeks 6 days who had received one or more doses of betamethasone who were expected to be delivered within 1 to 4 hours. Women received either 200 or 400 micrograms of thyrotropin-releasing hormone or were in the control group. RESULTS: Thyroid-stimulating hormone determinations on cord blood had a higher mean level in both treatment groups compared with the control group. No differences were seen in cord blood results between the two treatment groups for thyroid-stimulating hormone, thyroxine, triiodothyronine, free thyroxine, free triiodothyronine, and prolactin levels. The only other differences found were in a higher level in total thyroxine and a lower level of free thyroxine in the 400 micrograms thyrotropin-releasing hormone group compared with the 200 micrograms group in the 48-hour blood determinations. CONCLUSION: Both 200 and 400 micrograms of thyrotropin-releasing hormone provided fetal pituitary stimulation, as reflected in fetal thyroid-stimulating hormone levels in cord blood, and both gave significantly higher levels compared with a control group.

Adult↗
PubMed1995

Esophageal body and lower esophageal sphincter function in healthy premature infants.

BACKGROUND & AIMS: Gastroesophageal reflux is a common problem in premature infants. The aim of this study was to use a novel manometric technique to measure esophageal body and lower esophageal sphincter pressures in premature infants. METHODS: Micromanometric feeding assemblies (OD, < or = 2 mm) incorporating 4-9 manometric channels were used in 49 studies of 27 premature neonates. Esophageal body motility was recorded at three sites for 20 minutes after feeding. Twenty attempts (one per minute) were made to stimulate swallowing via facial stimulation (Santmyer reflex). In 32 studies lower esophageal sphincter pressures were recorded (sleeve) for 15 minutes before and after feeding. RESULTS: Peristaltic motor patterns were less common than non-peristaltic motor patterns (26.6% vs. 73.4%; P < 0.0001) that comprised 31.1% synchronous, 34.6% incomplete, and 6.3% retrograde pressure waves. Reflex swallowing was elicited more frequently in neonates older than 34 weeks postconceptional age than in younger infants (33.4% vs. 20.4%; P < 0.05). Mean lower esophageal sphincter pressure was 20.5 +/- 1.7 mm Hg before and 13.7 +/- 1.3 mm Hg after feeding (P < 0.0005). CONCLUSIONS: Premature infants show nonperistaltic esophageal motility that may contribute to poor clearance of refluxed material. In contrast, the lower esophageal sphincter mechanisms seem well developed.

Deglutition↗
PubMed1993

Maturity of children to consent to medical research: the babysitter test.

The age of maturity of children to consent for medical research is under debate, as different authorities regard the capacity of young teenagers as either satisfactory or not to grant consent without parental participation in the process. The present paper contrasts the generally accepted guideline for ethics in paediatric research in Canada with what the same children are allowed and expected to be able to do as babysitters. This comparison reveals deep incongruences in the way the maturity of the same children is appreciated for two different tasks.

Adolescent↗
PubMed1988

Ultrasound diagnosis of nephrocalcinosis in preterm infants.

The incidence of nephrocalcinosis in very low birthweight (less than 1500 g) premature infants was assessed by ultrasound scan and analysis of urine. Three of 36 infants had nephrocalcinosis. All had been receiving long term frusemide for bronchopulmonary dysplasia with simultaneous fluid restriction. Urinary investigations showed no consistent findings in babies with nephrocalcinosis.

Furosemide↗
PubMed1984

Cell hydration in the normally grown, the premature and the low weight for gestational age infant.

Total body water (TBW), extracellular volume (ECV) and intracellular water (ICW) were measured in a cross-sectional study of 107 infants up to four weeks after birth. Three groups of infants were selected for study: (1) mature normally grown infants, (2) mature low weight for gestational age (LWGA) infants and (3) premature normally grown infants. In the normal mature infants there was no significant change in TBW during the first 6 days after birth but there was a small but significant (P less than 0.02) redistribution of extracellular water into the cells by the sixth postnatal day. This suggests that the normal weight loss in infants after birth is due to a relative starvation rather than cell dehydration. In the LWGA infants, TBW levels were higher than normal and ICW significantly increased. This index of cell mass further increased throughout the 14-day period studied (P less than 0.01) and was the highest of all groups studied. It is argued that the changes are due to cytoplasmic growth. Premature babies (mean weight approximately 2000 g and greater than 30 weeks gestation) had higher TBW values than their mature normally grown counterparts. Hyponatraemia was infrequent and no shift of water into cells was detected. All groups of infants revealed loss of ECV over the first two weeks and in premature infants the loss was commensurate with that of TBW.

Body Water↗
PubMed1983

Neonatal water metabolism: an objective postnatal index of intrauterine fetal growth.

The water metabolism of 103 newborn babies was determined over the first 10 postnatal days, by measuring water turnover rates by means of an isotope dilution technique. This technique involves the oral administration of the non-radioactive isotope of water, 2H2O, and the measurement of its urinary excretion by infrared spectrophotometry. The slope of the excretion curve after equilibration with the infant's body water was mathematically expressed as the rate constant. Using multiple obstetric and paediatric criteria, the babies were clinically classified into one of three categories, fully grown ("normal'), borderline or clearly growth retarded. The median values of the rate constants X 10(4) (h-1) for the three groups were 73.3, 85.9 and 100.2 and were highly significantly different from each other (P less than 0.0005) with no overlap of the 97% non-parametric confidence limits of each group. Neonatal water turnover increased with the clinical degree of intrauterine fetal growth retardation and within the limits of this study, this finding was unaffected by gestational age, birth weight or the neonatal environment. The results suggest that neonatal water metabolism is an objective postnatal index of fetal growth retardation.

Body Water↗
PubMed1983

Energy balance and nitrogen balance in growing low birthweight infants fed human milk or formula.

Energy and nitrogen balances were measured in growing low birthweight infants fed either mother's expressed breast milk or a 20 kcal per ounce formula to determine whether or not there were differences between the two dietary groups in (1) the partition of energy among excretion, expenditure, and storage and (2) the relation of energy storage and nitrogen retention to weight gain. There were no significant differences between the human milk fed infants and formula fed infants in gross energy intake, metabolizable energy intake, nitrogen intake, or nitrogen retention. Energy expenditure was significantly lower in the human milk fed infants than in formula fed infants (221 kJ/(kg. day) and 244 kJ/(kg. day), respectively). There was no difference in mean energy storage between the two groups. Although weight gains were similar in both dietary groups, the ratio of energy storage to weight gain was significantly greater in infants fed with human milk (15.3 kJ/g, S.D. 2.0) than in infants fed formula (13.2 kJ/g S.D. 1.8). There was no significant difference between the two groups in the ratio of nitrogen stored to weight gain.

Body Weight↗
PubMed1982

Hydration in the first 24 h of postnatal life in normal infants born vaginally or by caesarean section.

A total of 65 infants, 48 born vaginally and 17 by segment caesarean section, were studied prior to labour for extracellular volume (ECV) (corrected bromide space) and total body water (TBW) (deuterium space) during the first 24 h of postnatal life. The infants were mature and growth retardation excluded. A 'heel stick' blood sample was taken for micro determination of Br and urine for 2H2O concentration. ECV varied from 343 +/- 27 ml/kg at 6 h to 358 +/- 21 ml/kg at 24 h and TBW was 75.5 +/- 3.4% of body weight. Contrary to current opinion, neither TBW nor cell hydration differed in infants born by caesarean section compared with those born vaginally. Such modern methodology to study infant body hydration and the critical assessment of growth and maturity demonstrates that hydration during the first 24 h of life is relatively stable and is not affected by the mode of delivery.

Birth Weight↗
PubMed1976

Metaphyseal chondrodysplasia, neutropenia, and pancreatic insufficiency presenting with respiratory distress in the neonatal period.

Two pairs of brothers suffered respiratory distress in the newborn period because their ribs were abnormally short. The diagnostic radiological features of metaphyseal chondrodysplasia appeared only in the second year. Pancreatic insufficiency and neutropenia were present. One died of overwhelming infection and his brother survived a life-threatening episode of gangrenous proctitis.

Agranulocytosis↗