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Biomedical subjects

G J Knight

Publications and source records attributed to G J Knight.

99 records · Page 6Linked to original sources
PubMed1966

The measurement of sodium concentration in human red blood cells.

Experiments are described which indicate that iodinated human serum albumin underestimates the amount of extracellular sodium trapped in the packed layer of red blood cells, when cells and plasma are separated by centrifugation. Sucrose-(14)C also underestimates the amount of trapped extracellular sodium, but the difference between the percentages of sucrose-(14)C and extracellular sodium trapped is constant and independent of mean relative centrifugal force. It is concluded that human red blood cell sodium concentration can be measured with accuracy (a) if trapped plasma sodium is estimated with radioisotopes of sodium and a correction made for entry of sodium into the cells, providing cells and plasma can be separated rapidly; (b) by the use of sucrose as a standard plasma marker to derive the amount of trapped plasma sodium; (c) by washing the cells with sodium-free solutions. Reported values for red blood cell sodium concentration in healthy adults are critically reviewed.

Animals↗
PubMed1966

The entry of sodium into human red blood cells in vivo.

The kinetics of sodium, movement into human red blood cells has been studied in vivo with (24)Na. When human serum albumin(-131)I is used to measure the percentage of plasma trapped in the packed red blood cells after centrifugation, approximately 30 % of red blood cell sodium is found to equilibrate immediately with plasma. It is concluded that this immediately exchangeable compartment of red blood cell sodium is an experimental artefact, associated with the use of labeled albumin for measuring plasma trapping. This immediately exchangeable fraction disappears when sucrose-(14)C is used to measure plasma trapping. The experimental results were examined by compartmental analysis, using an analogue computer. The results obtained, when plasma trapping was measured with sucrose-(14)C could be simulated by the use of models containing two compartments, arranged in series or in parallel. The errors of the techniques used and the possible physical basis for the results are discussed.

Carbon Isotopes↗
PubMedDate not supplied

Evaluation of preschool children with Down's syndrome in Cape Town using the Griffiths Scale of Mental Development.

Fifty-five preschool children with Down's syndrome were assessed using the Griffiths Scale of Mental Development. They were all the children with Down's syndrome living in Cape Town who spoke English or Afrikaans as their home language. There was a significant decrease in developmental quotient with increasing age and the hearing and speech subscore was lower than the other subscores. No significant associations were found between maternal age, sex, social class or race of the child and development. There was a negative association between developmental quotient and the number of siblings. The additional stimulation of a playgroup or preschool centre was associated with improved developmental functioning when compared to the children cared for at home during the day.

Child Development↗