Effect of transfusion on hemoglobin variants in preterm infants.

OBJECTIVE: To determine the effect of transfusion on hemoglobin (Hb) variants in very low birth weight infants and to correlate these changes with parameters measured in routine complete blood counts. METHODS: Hb variants were measured by capillary isoelectric focusing on 126 specimens from 25 very low birth weight infants during their hospital course. These results were compared with transfusion frequency, mean corpuscular volume (MCV), and red cell distribution width. RESULTS: Mean initial Hb F level before transfusion was 87.1 +/- 5.1%, and a single 15 ml/kg packed red blood cell transfusion decreased the mean Hb F level to 54.0 +/- 4.7%. With frequent transfusions in the first month of life, there was progressive decline in Hb F content such that Hb F made up < 15% of the total Hb after five transfusions. There was a linear correlation between Hb F content and MCV, with a correlation coefficient (r) of 0.77 and a p value of < 0.0001. In most instances, when the MCV fell below 100 fl, the Hb F content was < 50%; when the MCV fell below 95 fl, the Hb F content was < 25%. There was a nonlinear correlation between Hb F content and red cell distribution width. CONCLUSION: Transfusion in very low birth weight infants results in a rapid transition from Hb F to Hb A predominance. This transition is marked by a reduction in MCV that allows for prediction of the Hb F content.

Rabbit gut permeability in response to histamine chloramines and chemotactic peptide.

Granulocyte-derived chlorinated amines and bacterial formyl peptides are thought to enhance epithelial permeability. In the current study, gut permeability to [51Cr]ethylenediaminetetraacetic acid (EDTA) was monitored in response to luminal formyl-methionyl-leucyl-phenylalanine (fMLP) and histamine monochloramine and dichloramine. Responses were determined in rabbits during states of basal and elevated permeability. Luminal fMLP had minimal effects of gut permeability in control and injured states. Histamine monochloramine or dichloramine enhanced epithelial permeability under basal conditions; this effect was exaggerated by a pre-existing injury. Both histamine monochloramine and dichloramine retained full histamine agonist properties, and a combination of antioxidant and antihistamine therapy was required to block this increase in gut permeability. Whereas histamine chloramines caused a dose-dependent cytotoxicity in rat-cultured enterocytes, marked histological changes to the mucosa were not evident, nor were mucosal glutathione levels depleted. As histamine chloramines retain the histaminergic and oxidizing potential of their precursors, they represent a unique form of inflammatory mediator, although their highly reactive nature precludes in vivo confirmation of their formation.

Potential role of histamine monochloramine in a rabbit model of ileitis.

Histamine chloramines, derived from the chlorination of histamine by granulocyte-derived oxidants, are potential mediators of intestinal injury and dysfunction in states of atopy or inflammation. We assessed the ability of histamine monochloramine to increase epithelial permeability in rabbit distal small intestine and determined whether the conditions for histamine chloramine formation are favorable in a rabbit model of ileitis. Epithelial permeability, quantified by the blood-to-lumen clearance of 51Cr-labeled ethylenediaminetetraacetic acid, was enhanced by luminal perfusion with either histamine or histamine monochloramine (10 microM), although the latter was twice as effective (p less than 0.05). In a rabbit model of ileitis induced by a luminal solution of acetic acid (200 mM) and casein (10 mg/ml) there was a marked increase in epithelial permeability and in the release into the lumen of histamine, myeloperoxidase, 6-keto-prostaglandin F1 alpha and protein. These results suggest that the conditions are favorable for histamine chloramine formation and that histamine and histamine chloramine may impair the integrity of the epithelial barrier.