Relationship between intelligence and the size and composition of the corpus callosum.

We investigated the relationship between the morphology of the corpus callosum (CC) and IQ in a healthy sample of individuals in their late teens and early twenties. The relationship between the area of the CC, measured at the midline, and IQ showed regional differences. We observed that a higher estimated performance IQ was associated with smaller area in the posterior regions of the CC, a finding that differs from a positive association previously observed in a somewhat older adult sample. In contrast, higher estimated verbal IQ was associated with decreased fractional anisotropy of the genu, an anterior portion of the CC. Age effects were also observed such that older age was associated with larger CC area. Our results suggest that CC morphology is related to cognitive performance, which may have implications for clinical populations in whom CC morphology is atypical.

Investigations into the production of acetate from ethanol by human blood and bone marrow cells in vitro.

The metabolism of ethanol to acetate and CO2 by suspension cultures of human blood and marrow cells has been investigated. The average rate of metabolism of ethanol by relatively pure preparations of monocytes plus lymphocytes, neutrophils and erythrocytes obtained from normal peripheral blood were, respectively, 12.58, 5.44 and 0.32 nmol/10(7) cells/h, when the concentration of ethanol in the culture was 2.63 mM. Under similar culture conditions, the average rate of metabolism of ethanol by suspension cultures of human marrow cells was 19.0 nmol/10(7) nucleated marrow cells/h. The metabolism of ethanol by nucleated marrow cells was only slightly inhibited by pyrazole and 3-amino-1,2,4-triazole indicating that it was largely independent of pyrazole-sensitive alcohol dehydrogenase and catalase. By contrast, the oxidation of ethanol by isolated rat hepatocytes was markedly inhibited by pyrazole and therefore appeared to be mainly dependent on alcohol dehydrogenase. It is concluded that bone marrow cells have a considerable capacity to metabolize ethanol and that the predominant biochemical pathway involved in this metabolism is different from that involved in rat hepatocytes.

Effects of ethanol on cell volume and protein synthesis in a human lymphoblastoid cell line (Raji).

A human lymphoblastoid cell line (Raji) developed macrocytosis after 5-7 days when cultured in the presence of 100, 250 and 500 mg ethanol/dl. The degree of macrocytosis was least with 100 mg/dl and greatest with 500 mg/dl. The macrocytosis was associated with a proportionate increase in the total protein content per cell, was reversed after culture in the absence of ethanol and was uninfluenced by the supplementation of the culture medium with 50 micrograms folic or folinic acids per millilitre. Ethanol also caused a substantial prolongation of the cell doubling time at concentrations of 250 and 500 mg/dl (but not 100 mg/dl) and this was associated with some increase in the proportion of non-viable cells in the cultures. Furthermore, ethanol increased the incorporation of 3H-leucine into protein per femtolitre of cell volume. It is proposed that the ethanol-induced macrocytosis may have developed as a consequence of the stimulation of the rate of protein synthesis within a normal or prolonged cell cycle.

A new case of congenital dyserythropoietic anaemia, type III: studies of the cell cycle distribution and ultrastructure of erythroblasts and of nucleic acid synthesis in marrow cells.

The clinical and laboratory findings in an asymptomatic 19-year-old Welshman with congenital dyserythropoietic anaemia (CDA) type III are described. The blood film showed macrocytosis and red cell fragmentation and there was biochemical evidence of intravascular haemolysis. The bone marrow showed erythroid hyperplasia, megaloblastic erythropoiesis and several giant multinucleate erythroblasts. Some mononucleate erythroblasts were large and had relative DNA contents of 4-8c and the bi- and multinucleate erythroblasts had total DNA contents of 2-16c. Some of the multinucleate erythroblasts displayed a variety of ultrastructural abnormalities, including marked differences in the appearances of the individual nuclei within the same cell. The marrow cells gave a normal deoxyuridine-suppressed value indicating that the megaloblastic changes were not caused by an impairment of the methylation of deoxyuridylate. The rates of incorporation of 14C-glycine and 14C-adenine into both the DNA and RNA of bone marrow cells were within the normal range. Furthermore, the average rate of elongation of newly-synthesised, 3H-thymidine-labelled daughter DNA strands, assessed by hydroxyapatite chromatography of alkali-denatured DNA was found to be normal. The results suggest that there is no impairment of DNA replication in the majority of the erythroblasts and that the abnormality of erythropoiesis resulted from disturbances during mitosis and the G2 phase.

DNA chain elongation rates in marrow cells from vitamin B12-deficient patients and methotrexate-treated mice.

The DNA synthesized by marrow cells from patients with vitamin B12 deficiency and mice previously given methotrexate (MTX), has been investigated. Suspensions of bone marrow cells were pulse-labelled with [methyl-3H]thymidine or deoxy [5-3H]cytidine for 30 s and the radioactivity in the DNA was chased thereafter in the presence of 10 microM non-radioactive nucleoside for periods up to 60 min. The rates of elongation of new daughter strands were then assessed by hydroxyapatite chromatography of alkali-denatured DNA samples. No significant differences were found between the average rates of elongation of daughter strands from control marrow cells on the one hand and the vitamin B12-deficient or the methotrexate-affected cells on the other. This is to be contrasted with the results of previous studies which have shown a retardation in the rates of movement of replication forks in stimulated, cultured lymphocytes obtained from vitamin B12- or folate-deficient patients.

Metabolism of ethanol by human bone marrow cells.

The ability of human bone marrow cells to metabolise has been studied. After incubation of suspensions of bone marrow cells with [1(-14)C] ethanol (0.1 mg/ml) for 1.5 h, radioactivity was present in the evolved CO(2) and in the cellular lipids. Only a part of the 14CO2 generated was dependent on the presence of contaminating blood cells in the marrow cell suspensions. These findings indicate that one or more cell types in the marrow are capable of oxidising ethanol to acetaldehyde and acetate. Our date raise the interesting possibility that the effects of chronic alcoholism on the bone marrow may not be caused by a direct action of ethanol, but may be related to some intracellular or extracellular changes resulting from the metabolism of ethanol within the marrow cells themselves.