Barry J. O'Neill

Red Cell Indices in Megaloblastosis and Iron Deficiency

Summary The diagnostic value of the red cell indices MCV, MCH and MCHC was assessed in iron deficiency and megaloblastic conditions. The haemoglobin and MCV values taken together provided a reliable distinction between iron deficiency and vitamin B12 or folic acid deficiency. The strong positive correlation observed between MCV and MCH results showed that the MCH is of little value once the MCV is known. A large proportion of iron, vitamin B12 and folic acid deficient patients were found to have normal MCHC results. Among the iron deficient patients the relationship between the haemoglobin level and the red cell indices suggested that the most anaemic patients have the smallest cells with the lowest cellular concentration of haemoglobin. Normal subjects showed an increase in MCV and a decrease in MCHC with increasing age.

Effect of pH changes on the binding of vitamin B12 by intrinsic factor

The binding of vitamin B12 by human gastric juice has been found to be pH dependent. Maximum binding occurs between pH 6·5 and 10. Outside this pH range the vitamin B12-binding ability of human gastric juice decreases and at pH below 2 or above 12·2 this drops sharply to about 10 to 15% of the maximum. Three commercial hog intrinsic factors have been found to give a similar response to pH changes. The pH-dependent binder in human gastric juice has been shown to be intrinsic factor by the addition of intrinsic factor-blocking antibody. About 10% of vitamin B12 bound by human gastric juice is not bound by intrinsic factor and is not pH dependent. The reduction in the vitamin B12-binding capacity of human gastric juice induced by an adverse pH is reversed by neutralization. The physiological and clinical significance of these observations is discussed and their relevance to various procedures in vitro noted.

Studies on the binding of vitamin B12 by human saliva

Summary The vitamin B12 binding capacity of saliva has been studied in 48 normal subjects, 11 patients with chronic myeloid leukaemia and 11 patients with pernicious anaemia. No significant difference in this binding capacity was noted in these subjects. Treatment with intrinsic factor blocking antibody did not reduce the vitamin B12 binding capacity in the 9 samples tested. It was also shown that saliva did not substitute for intrinsic factor in vivo in 2 subjects with pernicious anaemia. Neither did pre‐binding of vitamin B12 to saliva inhibit its normal absorption in 1 control subject. The binding of vitamin B12 by saliva, in vitro, was also shown to be affected by pH changes.

A Modified Method for Assaying Intrinsic Factor Blocking Antibody in Serum

Summary A modified charcoal technique for the detection and titration of intrinsic factor blocking antibody in serum is described. The modifications include pre‐saturation of the test serum with unlabelled vitamin B12, buffering the system and using freshly‐prepared and washed, albumincoated charcoal. This improved technique does not interfere with the titre of the serum intrinsic factor antibody, avoids false positive results, and saves time, effort and reagents.

Folic acid deficiency in Lactobacillus casei.

&NA; The effect of folate starvation on the biochemical constitution and morphology of Lactobacillus casei was studied by growing cultures in different concentrations of folic acid. Folate starvation leads to a marked reduction in the amount of DNA synthesized, a large increase in the average cell length and a striking loss of viability. In addition, extreme folate starvation leads to small reductions in the amount of RNA and protein synthesized. The similarities between folate deprivation in L. casei and in man suggest that the bacterial system may provide a convenient model of the condition in humans.

The anaemia of chronic renal failure

The anaemia accompanying chronic renal failure was studied in 58 patients. Investigations carried out included bleeding studies, bone marrow preparations (including iron and PAS stains), serum iron, TIBC, folk acid and vitamin B 12 levels, 51 Cr red cell survival times, external body scan, estimation of 5-day faecal blood loss, and 58 Fc ferrokinetic studies. The anaemia in these cases was commonly found to be due to multiple factors, in particular haemolysis, bone marrow failure and folic acid deficiency. The need to exclude anaemia due to other causes unrelated to the chronic renal failure was also shown in this series.