Megaloblastic anemias-mechanisms & management

Biphasic modulation of NOS expression, protein and nitrite products by hydroxocobalamin underlies its protective effect in endotoxemic shock: downstream regulation of COX-2, IL-1β, TNF-α, IL-6, and HMGB1 expression

Background. NOS/^•NO inhibitors are potential therapeutics for sepsis, yet they increase clinical mortality. However, there has been no in vivo investigation of the (in vitro) ^•NO scavenger, cobalamin's (Cbl) endogenous effects on NOS/^•NO/inflammatory mediators during the immune response to sepsis. Methods. We used quantitative polymerase chain reaction (qPCR), ELISA, Western blot, and NOS Griess assays, in a C57BL/6 mouse, acute endotoxaemia model. Results. During the immune response, pro-inflammatory phase, parenteral hydroxocobalamin (HOCbl) treatment partially inhibits hepatic, but not lung, iNOS mRNA and promotes lung eNOS mRNA, but attenuates the LPS hepatic rise in eNOS mRNA, whilst paradoxically promoting high iNOS/eNOS protein translation, but relatively moderate ^•NO production. HOCbl/NOS/^•NO regulation is reciprocally associated with lower 4 h expression of TNF-α, IL-1β, COX-2, and lower circulating TNF-α, but not IL-6. In resolution, 24 h after LPS, HOCbl completely abrogates a major late mediator of sepsis mortality, high mobility group box 1 (HMGB1) mRNA, inhibits iNOS mRNA, and attenuates LPS-induced hepatic inhibition of eNOS mRNA, whilst showing increased, but still moderate, NOS activity, relative to LPS only. experiments (LPS+D-Galactosamine) HOCbl afforded significant, dose-dependent protection in mice Conclusions. HOCbl produces a complex, time- and organ-dependent, selective regulation of NOS/^•NO during endotoxaemia, corollary regulation of downstream inflammatory mediators, and increased survival. This merits clinical evaluation.

Folic acid deficiency in sickle cell anaemia

Megaloblastic anaemia responding to folic acid has been reported in a number fo patients with sickle cell anaemia. The incidence of reduced serum and erythrocyte folate levels in such patients remains unclear, however. Serum and erythrocyte folate contents were measured microbiologically in patients with sickle cell anaemia as well as in two control groups with sickle cell trait or normal haemoglobin pattern. Low serum and erythrocyte folate values were significantly more common in 61 sickle-cell patients than in each of the two socio-economically-matched control groups including 61 subjects with Hb AS and 69 blacks with Hb AA. There was no correlation between serum folate and haematocrit or reticulocyte count. The erythrocyte folate, measured before and after removal of reticulocytes, remains a reliable indicator of deficiency of folic acid in sickle-cell patients despite variable degrees of reticulocytes. Folate therapy resulted in higher haematocrits in three of four sickle-cell patients with low serum and low erythrocyte folate values, but in only one of 12 patients with low serum folate and normal erythrocyte folate. These findings are consistent with other observations that folate requirement may be increased in chronic haemolytic disorders and suggest that erythrocyte folate values should be obtained in sickle-cell patients suspected of having folate deficiency.