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Biomedical subjects

C A Wardrop

Publications and source records attributed to C A Wardrop.

At least 37 records · Page 2Linked to original sources
PubMed1989

Myelodysplastic syndrome with trisomy 8 in an adolescent with Fanconi anaemia and selective IgA deficiency.

We describe a patient with growth failure and multiple congenital anomalies characteristic of Fanconi anaemia, but without the classical feature of progressive bone marrow hypoplasia. Following treatment with growth hormone for a period of 8 years, he presented with myelodysplastic syndrome and a karyotypically abnormal clone in the bone marrow (47,XY,+8). The diagnosis of Fanconi anaemia was supported by the induction of abnormally high levels of characteristic chromosome aberrations in peripheral lymphocytes following exposure in vitro to the bifunctional alkylating agent mitomycin C. Immune function studies also identified a selective IgA deficiency. The relative importance of interacting constitutional and exogenous factors involved in the development of preleukaemia in this patient is discussed.

Adolescent↗
PubMed1988

Definitive estimate of rate of hemoglobin switching: measurement of percent hemoglobin F in neonatal reticulocytes.

The transition from fetal to adult erythropoiesis starts at 32-36 wk postconception. The rate of this switchover has been controversial. Studies of globin chain synthesis by reticulocytes in vitro have indicated gradual switching with a time for 50% reduction in fetal Hb synthesis ("half-time") of more than 6 wk. This may not accurately reflect fetal/adult Hb synthetic balance in vivo. By contrast, histochemical studies and also indirect mathematical analysis of postnatal changes in circulating fetal Hb and adult Hb may imply abrupt patterns of switching with half-times of less than 1 wk. We have resolved this discrepancy by direct measurement of the changing proportions of fetal and adult Hb in reticulocytes prepared by flourescence activated cell sorting from 10 full-term cord and 45 preterm postnatal blood samples. This method overcomes problems both of extrapolation from in vitro measurements and of mathematical analysis. We find a gradual transition from fetal Hb to adult Hb synthesis. The half-time is approximately 16-18 wk. Values of fetal Hb in reticulocytes were on average higher than predicted from in vitro synthesis studies. We find considerable individual variation. Infants differ in their switching behaviour, many showing prolonged dependence on fetal Hb.

Age Factors↗
PubMed1987

Lessons from the anemia of prematurity.

In our view, three main lessons stem from consideration of the refractory early anemia of prematurity (REAP). These are: (1) Hemoglobin concentration is not enough to describe the anemia. (2) The REAP may be clinically very severe but is often easily missed. It interacts with and worsens other causes of anemia in preterm infants, such as blood losses. Its pathogenesis is multifactorial, but it is generally interrelated with short gestation and its other complications. (3) Prevention, prophylaxis, and if necessary, adequate management are very important.

Anemia, Neonatal↗
PubMed1986

Determination of red-cell mass in assessment and management of anaemia in babies needing blood transfusion.

A new method for the rapid determination of red-blood-cell mass (RCM) in infants needing blood transfusion is described. RCM is estimated from the fall in the baby's fetal haemoglobin level resulting from transfusion of a known mass of adult-haemoglobin-containing red cells. In severe blood loss and refractory anaemias in preterm infants, in addition to the red-cell deficit, the plasma volume is low, leading to a falsely high haematocrit of about 0.30, which conceals a deficiency of 50-70% in circulating red cells. Red-cell transfusion in such infants based on haematocrit often fails to restore RCM to normal, leading to repeated transfusions. The frequency of transfusions may be reduced by giving enough red cells fully to correct the deficiency based on RCM estimation.

Adult↗
PubMed1985

The flow of blood cell suspensions through 3 microns and 5 microns Nuclepore membranes: a comparison of kinetic analysis with scanning electron microscopic examinations.

This study was designed to investigate the effect of red and white cells on the flow of dilute suspensions of blood cells through 3 microns and 5 microns Nuclepore membrane filters. The rate of flow of blood cell suspensions through 3 microns or 5 microns membranes declines continually due to occlusion of pores by slow cells. The cells which occlude 3 microns pores exceed the number of white cells about seven-fold. Electron microscopic examination of a used membrane confirms that these slow cells are not white cells but are red cells which are visibly damaged. With 5 microns membranes, the number of slow cells is entirely consistent with them being white cells. Again, electron microscopic examination confirms that 5 microns pores are occluded by white cells. With both types of membrane, the same kinetic analysis is valid and yields information about the behaviour of red cells during the filtration procedure.

Blood Cells↗
PubMed1985

New insulating material in maintenance of body temperature.

Flectalon, web of aluminised polyvinylchloride fibres, has been formulated to minimise radiant heat losses and to provide conventional insulation. Critical temperature determinations were used to assess the insulating efficacy of this and other swaddling materials in infants. The critical temperature for a baby 2 to 10 days old was 31 degrees C when naked and 23 degrees C when wrapped in a Silver Swaddler or a sheet and two blankets. The use of a quilt made with Thinsulate or Hollofil with a mass per unit area of 160 to 180 g/m2 reduced the critical temperature to 19.5 degrees C, while Flectalon of comparable weight reduced the critical temperature to 13.8 degrees C: Flectalon is thus an efficient insulator. The risk of overheating was studied by monitoring swaddled babies, rectal temperatures at various ambient temperatures. Some forms of swaddling caused increases in rectal temperatures at "normal' hospital temperatures, implying risks from warmer environments and assessments of swaddling materials should, therefore, include medical evaluation of efficiency and safety. Flectalon merits assessment in other groups at risk from hypothermia.

Aluminum↗
PubMed1984

Evaluation of the contribution of red and white cells to the flow of suspensions of washed blood cells through 3 micron Nuclepore membranes.

This study was designed to investigate a method of analysis which can quantitate the contribution of white cells to the flow of washed suspensions of blood cells. Such an analysis would obviate the need to remove white cells when studying the filterability of normal and abnormal red cells. The flow of suspensions of washed blood cells through a 3 micron Nuclepore membrane declines continually due to the occlusion of pores and the degree of pore occlusion is reduced significantly by the removal of the 'buffy coat' during the preparation of the suspension. These findings are in complete agreement with many other reports. However, a detailed kinetic analysis of the results suggests strongly that the white cell population makes a small contribution to the degree of pore occlusion which is caused largely by approximately 1% of the total red cell population. Despite the phenomenon and extent of pore occlusion, a kinetic analysis of the complete non-linear flow profile allows a measure of the deformability of red cells from filtration studies of washed but unfractionated blood cells.

Blood Flow Velocity↗
PubMed1981

Acute depression of serum folate in surgical patients during preoperative infusion of ethanol-free parenteral nutrition.

Total parenteral nutrition for 48 h with Aminoplex solutions and a calorie source led to statistically similar, severe depression of the serum folate concentration (by 63-77%) irrespective of whether the calorie source contained ethanol, sorbitol, lipid or glucose. Folate levels were also depressed following infusion of other ethanol-free regimens (Freamine and glucose, 59%; Vamin and glucose, 44%). Least depression (31%0 followed use of Aminosol and glucose, a regimen based on casein hydrolysate. It seems important, therefore, to give prophylactic folate to all patients receiving parenteral nutrition, regardless of whether the calorie source is ethanol.

Ethanol↗
PubMed1981

Aminoacid infusion induced depression of serum folate after cholecystectomy.

Aminoacid solutions were given to cholecystectomy patients for a period of 48 h starting 24 h after the operation. Infusion of the aminoacid component of parenteral nutrition regimens, without calorie source, frequently led to an acute fall in the serum folate concentration. The degree of depression varied with different commercial aminoacid solutions. (Aminoplex 14 = c.60%, Vamin = 30%, Aminosol = c.0%). The folate depression by Vamin infusion was unaffected by supplementation with L-methione but was alleviated by the addition of glycine. As a consequence of surgical operation itself, folate values fell by 37% during the 24 h following cholecystectomy. This seems likely to increase the risk of haematological toxicity (i.e. acute leukopenia and thrombocytopenia) in patients given folate-free parenteral nutrition after a surgical operation.

Amino Acids↗
PubMed1979

Effects of stopping smoking for 48 hours on oxygen availability from the blood: a study on pregnant women.

The effects of stopping smoking for 48 hours on factors governing the availability of oxygen from the blood--that is, carboxyhaemoglobin (COHb), haemoglobin-oxygen (HbO2) affinity, and haemoglobin concentration--were measured in women in the last trimester of pregnancy. Three groups were studied: smokers, smokers who stopped smoking for 48 hours, and non-smokers. The 22 smokers had higher initial COHb values and greater HbO2 affinity than the 10 non-smokers, but their total haemoglobin concentrations were also higher, so that their oxygen availability was not significantly reduced. In the 11 smokers who stopped the reduction in COHb and decrease in HbO2 affinity led to a significant increase of 8% in "available oxygen" in 48 hours. Since even small improvements in oxygen delivery to the tissues may confer critical benefit to the fetus, particularly during labour or when exposed to general anaesthesia, smoking should be discouraged for 48 hours before elective deliveries. The same consideration might reasonably be applied to patients undergoing general anaesthesia for all elective operations.

Carboxyhemoglobin↗
PubMed1978

Oxygen availability from the blood and the effect of phosphate replacement on erythrocyte 2,3-diphosphoglycerate and haemoglobin-oxygen affinity in diabetic ketoacidosis.

Eleven patients with diabetic ketoacidosis were given intravenous phosphate in doses (mean 118 mmol; range 83--320 mmol) adequate to maintain normal plasma phosphate, in addition to a standard treatment regime. Prevention of hypophosphataemia stimulated recovery of the initially low red-cell 2,3-diphosphoglycerate concentrations (10.6 +/- 5.8 (SD) mumol/g Hb) after twenty-four hours. In ten control patients (initial concentration 8.1 +/- 4.4 mumol/g Hb) treated without phosphate replacement, significantly lower red-cell 2,3-diphosphoglycerate concentrations were found between 2 and 6 days after admission (forty-eight hour value for control patients 14.6 +/- 1.6 and for phosphate-treated patients 18.9 +/- 4.1 mumol/g Hb; p less than 0.01). However, no effect on in vivo p 50 or on the availability of oxygen from the blood resulted from the higher 2,3-diphosphoglycerate levels. Maintenance of normal plasma phosphate levels by intravenous phosphate is, therefore, not indicated to improve tissue oxygenation in diabetic ketoacidosis.

Adolescent↗
PubMed1978

Nonphysiological anaemia of prematurity.

Clinical and haematological findings at the nadir of the refractory, early anaemia of prematurity were compared in a study of 95 preterm infants. 53% of 30 babies less than 32 weeks' gestational age at birth had abnormal clinical features resulting from anaemia at its nadir, with a combination of tachycardia, tachypnoea, dyspnoea and feeding difficulties, diminished activity, and pallor. The expression 'available oxygen', derived from the Hb concentration and Hb-O2 affinity, correlated more closely with clinical features of anaemia that did the Hb concentration alone. A formula is presented that predicts the 'available oxygen', provided the Hb concentration and post-conceptual age are known; this avoids the need for direct measurement of Hb-O2 affinity. Clinical anaemia is common in preterm infants with Hb concentrations of up to 10.5 g/dl, consequent on the high O2 affinity of fetal Hb. This is the first description of any common clinical consequence of high Hb-O2 affinity.

Age Factors↗
PubMed1978

Simple and versatile method for measuring oxygen consumption in infants.

A simple, rapid, and accurate method for measuring oxygen consumption in infants is described. Expired gas is entrained in a stream of air drawn through a gently applied face mask. Oxygen consumption is derived from (1) gas flow rate, measured with a flowmeter, and (2) the fall in oxygen concentration of the gas mixture, measured with a paramagnetic analyser. A measurement can be made at the bedside within 2 minutes without disturbing the infant. In 17 mature 2-day-old neonates mean oxygen consumption was 6.52 ml/kg per min, SD 0.90, similar to that previously reported using less simple methods,

Evaluation Studies as Topic↗