Hemopoietic effect

Ongoing studies were found in abstract form in the open literature. These studies include the investigation of hemopoietic effects in adult mice at low exposures (Farris et al. 1995), strain differences in metabolism (Grotz and Witz 1995), analysis of benzene metabolites and glutathione in the bone marrow of mice (Henderson et al. 1995), comparison of pulmonary and hepatic microsomal metabolism of benzene in rats (Chaney and Carlson 1995), chromosomal aberrations or DNA repair in exposed humans (Anderson et al. 1995 Hallberg et al. 1995 Mills et al. 1994 Smith et al. 1995), DNA adduct formation (Hedli et al. 

Hemopoietic effects acute hemolytic anemia, accompanied by renal failure, e.g., after inhalation of arsenic hydride or ingestion of soluble copper salts. 

In the years 1929-37 Castle and his colleagues showed that normal gastric juice (intrinsic factor) would potentiate the hemopoietic effect of beef muscle (extrinsic factor). Later they showed that the extrinsic factor in beef muscle was vitamin B12 (Gardner et al., 1949) and that vitamin B12 itself acted like extrinsic factor when small doses were administered orally (Berk et al., 1948b). 

At one time intrinsic factor could be assayed only by its capacity to potentiate the hemopoietic effect of small doses of extrinsic factor (vitamin Bi2) in patients with pernicious anemia in relapse (page 157). The ability of materials to bind vitamin B12 and render it unavailable to organisms used for microbiological assay (page 168) proved to be an... 

To be effective, intrinsic factor must be administered through the alimentary tract. Gastric juice administered intravenously with vitamin Bi2 did not convincingly enhance the hemopoietic effect of the latter (Wallerstein et al., 1953a). 

The hemopoietic effect obtained by Klein and Wilkinson (1934) from intramuscular injections of beef muscle previously incubated with extracts of hog-stomach mucosa is in retrospect probably attributable to the independent action of the vitamin B12 present (Castle, 1953). 

Spies et al. (1953) reported that a boiled mixture of intrinsic factor concentrate from hog mucosa and vitamin Bn had hemopoietic effects in two patients with typical pernicious anemia. But, unfortunately, it had not previously been demonstrated whether or not these patients had failed to respond to similar oral doses of vitamin B12 without intrinsic factor. Glass and Boyd (1953) also described two examples of hemopoietic response to a boiled preparation from hog mucosa containing intrinsic factor and added Bn. 

The hypothesis of Callender and Lajtha is not supported (nor entirely contradicted) by experiments in vivo. Instillation of vitamin Bn into the marrow of one ileum caused maturation of megaloblasts at the site of injection but not in the opposite ileum (Horrigan et al., 1951). Gastric juice injected together with vitamin Bn intravenously did not convincingly enhance its hemopoietic effect (Wallerstein et al., 1953a). 

Intrathecal injections of 40 Mg- were given to study the mechanism of Bi2 binding in serum. The hemopoietic effects did not differ from those commonly produced by intramuscular injections of 40 Mg- (Cox, Ross et al., to be published see also pages 166 and 167 and Figs. 2 and 3). 

To this effect would be added the antianemic effect of the folic acid and citrovorum factor contained in the liver. Folic acid does not increase the absorption of vitamin B12 (page 183). The unlikelihood that it potentiates the hemopoietic effect of the vitamin is considered on page 183. 

Meyer et al. (1950) described responses to the oral administration of a preparation containing 1.67 mg. of folic acid and 25 ng. of vitamin B12 on the assumption that neither agent would have had any significant hemopoietic effect, they concluded that foUc acid acted like the intrinsic factor. Welch and Nichol (1952) demonstrated that folic acid did not enhance the absorption of an, orally administered dose of radioactive vitamin B12, and could therefore not be said to be active like Castle s intrinsic factor. 

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