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Biomedical subjects

T R Lappin

Publications and source records attributed to T R Lappin.

At least 73 records · Page 4Linked to original sources
PubMed1984

Controlled trial of artificial surfactant to prevent respiratory distress syndrome.

In a randomised, controlled trial of the effectiveness of artificial surfactant therapy 100 babies of less than 34 weeks' gestation were intubated at birth and received manual ventilation. The 49 babies in the treated group also received 30 mg dipalmitoylphosphatidylcholine and 3 mg high-density lipoprotein in a 5 ml suspension. There were no significant differences in mortality or in the incidence or severity of respiratory distress syndrome between the surfactant-treated and control groups as a whole or between subgroups divided on the basis of sex or pulmonary maturity (as assessed by the lecithin-sphingomyelin ratio). However, there appeared to be a trend towards improved survival in treated babies of 27-29 weeks' gestation.

Clinical Trials as Topic↗
PubMed1984

Iron status of the preterm infant during the first year of life.

The iron status of 49 preterm infants (mean gestational age 33.1 weeks) was assessed serially during the 1st year of life. Haemoglobin concentration, serum ferritin, serum transferrin, serum iron, and transferrin saturation were measured on nine occasions in each infant. In 16 infants of gestational age 28-32 weeks the haemoglobin concentration was significantly lower at 3, 6, and 9 weeks when compared to 33 infants of gestational age 33-36 weeks. For all other measures of iron status there were no significant differences between these gestational age groups. For the entire group of 49 infants the mean haemoglobin concentration reached a nadir of 11.2 g/dl at 9 weeks. Mean serum iron and transferrin saturation reached peaks of 24 mumol/l and 65%, respectively, at 3 weeks. The mean serum ferritin remained over 100 micrograms/l until after 18 weeks. 13 infants (26%) had iron deficiency defined as either serum ferritin less than 10 micrograms/1 (n = 10) or transferrin saturation less than 10% (n = 5) or both (n = 3).

Anemia, Hypochromic↗
PubMed1983

Serum copper and zinc levels in the preterm infant. A longitudinal study of the first year of life.

Serial determinations were carried out on 27 male and 21 female preterm infants (gestational age 28-36 weeks) throughout the first year of life. Serum copper at birth was 0.33 +/- 0.20 micrograms/ml (n equal 8); at 9 weeks, 0.77 +/- 0.19 micrograms/ml (n = 22); at 24 weeks, 1.00 +/- 0.27 micrograms/ml (n = 31), and at 52 weeks 1.21 +/- 0.27 micrograms/ml (n = 40). Serum zinc at birth was 1.03 +/- 0.16 micrograms/ml (n = 9); at 9 weeks, 0.71 +/- 0.11 micrograms/ml (n = 17); at 24 weeks, 1.02 +/- 0.20 micrograms/ml (n = 20), and at 52 weeks, 1.19 +/- 0.34 micrograms/ml (n = 33). The results of this study compare well with values previously reported for infants studied at selected age points.

Copper↗
PubMed1983

The effect of erythropoietin and other factors on DNA synthesis by mouse spleen cells.

The effects of pure and crude human urinary erythropoietin, crude sheep plasma erythropoietin and other growth factors on the incorporation of labeled thymidine were studied using spleen cells from mice previously treated with phenylhydrazine hydrochloride. Erythropoietin at 400 mU/ml caused a 40-80 fold increase in the incorporation of the labeled nucleoside. The slope of the dose-response curve found for pure erythropoietin was not significantly different from that found for a crude urinary erythropoietin preparation or for crude sheep plasma erythropoietin. Colony-stimulating factor, interleukin 2, interleukin 3 and the lectin, concanavalin A were also stimulatory but at concentrations from one hundred to one million times higher than that found for erythropoietin.

Animals↗
PubMed1983

Metabolism of exogenous adenine in a pyruvate kinase-deficient patient.

The metabolism of adenine, administered intravenously and orally, was studied in a patient with red cell pyruvate kinase (PK)-deficiency. Intravenous infusion of 58.5 mumol of adenine per kg containing 6475 Bq of 8-14C adenine caused an initial decrease in red cell ATP level and the gradual return to the pre-infusion level coincided with an increase in radiolabelled ATP. Of the infused adenine, 1.3% had entered the red cell pool after 2 h. The route of administration affected the urinary excretion of adenine and its oxymetabolites; after 6 h, 10.7% of the infused adenine had been excreted, compared with 7.4% after ingestion of a similar dose. In 10 control subjects given 45.1-55.5 mumol/kg, excretion of adenine plus oxymetabolites accounted for 13.5 +/- 2.9% of the ingested dose. Differences were also observed in the urinary purine excretion patterns for the two routes of administration. This study has shown that adenine can be incorporated into ATP in the red cells of a PK-deficient patient.

Adenine↗
PubMed1982

Automated colorimetric determination of alpha-tocopherol.

A rapid and convenient automated procedure for the determination of alpha-tocopherol is described. As little as 0.3 ml of serum or plasma can be used at a sample rate of 20 per hour and carry-over is negligible. Within-batch precision was 4.71% at 5.0 mg alpha-tocopherol per 1, and 3.68% at 20 mg/l, compared with a between-batch precision of 6.98% at 10 mg/l. Using this procedure alpha-tocopherol has been found to be distributed in a log-normal manner and on that basis the range of values for 80 haematologically normal subjects was calculated to be 4.0 to 16.0 mg/l. In pregnancy the alpha-tocopherol was elevated, ranging from 6.7 to 24.0 mg/l. During the first year of life normal infants ranged from 2.0 to 16.0 mg/l which was higher than a small group with various disorders whose values ranged from 1.2 to 8.3 mg/l. The cord blood level was approximately one-fifth of the maternal level.

Adult↗
PubMed1982

The in vitro effect of adenine on pyruvate kinase-deficient red cells.

In pyruvate kinase (PK)-deficient blood with high levels of reticulocytes, the degree of haemolysis after incubation at 37 degrees C for 48 h was halved by the inclusion of adenine in the medium. the decrease in haemolysis was associated with a higher ATP level but was not related to the pH of the incubation mixture. The incorporation of adenine into nucleotides studied over a 3 h period was similar in normal and PK-deficient blood. The observed increase in cellular ATP was equivalent to that shown by radioactive measurements to have been synthesized from added adenine. Inhibition of mitochondrial oxidative phosphorylation in the reticulocytes of the PK-deficient blood by KCN reduced the amount of adenine taken up by the cells by a factor of 3 and altered the pattern of incorporation into the nucleotides. Only 25% of the adenine which entered the blood cells was converted into ATP compared with 85% in the absence of cyanide. Despite the synthesis of small amounts of ATP from labelled adenine, the overall ATP content fell to less than 50% of its original level. It is suggested that incubation with adenine increased the ATP level in the reticulocytes by virtue of mitochondrial oxidative phosphorylation thereby reducing the haemolysis of these cells.

Adenine↗
PubMed1981

Determination of the oxygen dissociation curve and P50 of whole blood. An evaluation of the Hem-O-Scan and instrumentation of laboratory systems.

The Travenol Hem-O-Scan and the Instrumentation Laboratory (IL) system for determination of the oxygen dissociation curve and P50 values have been evaluated. Using the Hem-O-Scan, an oxygen dissociation curve and P50 value may be obtained on 2 microliter of blood in 40 min, though the pH is not measured. In the IL system, approximately 3 ml of blood is required to establish four points on the oxygen dissociation curve in 80 min, and pH data are available. Both systems give reproducible results for P50, giving standard deviations of 0.786 mm Hg for the Hem-O-Scan and 0.949 mm Hg for the IL system, compared with 1.740 mm Hg for the manual system. Good agreement was found between the manual method and Hem-O-Scan (t = 0.363, degrees of freedom = 19, 0.8 greater than P greater than 0.7; r = 0.892, P less than 0.001). There was also satisfactory agreement between the IL system and the Hem-O-Scan (t = 0.370, degrees of freedom = 20, 0.8 greater than P greater than 0.7; r = 0.760, P less than 0.001). P50 values obtained by the manual and by both automated technics agree well with published values.

Adult↗
PubMed1981

Three pyruvate kinase variants with increased affinity for PEP.

Three variants of pyruvate kinase are described which have marked reduction of activity associated with severe non-spherocytic haemolytic anaemia. Each variant shows a reduced K0.5 PEP (the value of the intercept of the abscissa on the Hill plot) and reduced Hill coefficient; FDP activation and ATP inhibition are less than normal and utilization of GDP is increased. The variants are slightly less inhibited by 2,3DPG than controls but require more FDP to relieve this inhibition. Cases 1 and 2 have decreased thermostability but case 3 is normal. The mutant enzymes are further distinguished by their affinity for FDP. Their kinetic and physicochemical properties are compared with other known cases with high affinity for PEP and discussed in terms of a R in equilibrium to T model model for allosteric enzymes.

Adenosine Triphosphate↗
PubMed1979

Intralaboratory quality control of hematology. Comparison of two systems.

Two systems for quality control have been compared, viz., the whole-blood control preparation method and the algorithm method using the geometric moving average XB and a new estimator Y. The system involving whole-blood controls has the advantage of simplicity of operation, but the economic cost of commercial preparations is often high. The algorith system has the advantage that results of all the test samples are used in the calculation; to some extent, this provides a buffer against random variation. The number of count-outs in a given channel is related to the precision of the channel, which in turn is a function of the number of determinations and calculations required for that result. An error of around 1% is introduced into the result each time a calculation is performed. A successful quality control scheme should contain elements of both control preparation and algorithm methods.

Erythrocyte Count↗
PubMed1978

Relation of high-density lipoprotein cholesterol concentration to type of diabetes and its control.

Serum cholesterol and high-density lipoprotein (HDL) cholesterol concentrations were measured in 192 diabetics (94 with juvenile-onset and 98 with maturity-onset diabetes) and 177 non-diabetic controls. Hb A1C, an index of blood sugar control, was also measured in the diabetics. Serum cholesterol concentrations were similar in all the diabetics and controls, but HDL cholesterol concentrations were lower in patients with maturity-onset diabetes than in those with juvenile-onset diabetes and controls. There was no correlation in diabetics between HDL cholesterol and Hb A1C. We conclude that HDL cholesterol concentrations are abnormally low in patients with maturity-onset diabetes but essentially normal in those with juvenile-onset diabetes. They are not related to diabetic control.

Adult↗
PubMed1978

A chemiluminescent effect encountered in the liquid scintillation counting of 32P phosphate.

During the course of a kinetic enzyme study of bisphosphoglyceromutase (EC 2.7.5.4.) a chemiluminescent effect was encountered in the liquid scintillation counting of the beta-emission from 32Pi. A method is described for overcoming the effect, thereby permitting the accurate determination of the radioactive compounds. It is important to check for chemiluminescent effects early in the development of new procedures that involve liquid scintillation counting.

Hydrogen-Ion Concentration↗