Search

Erythrocyte fractions of varying density were isolated by discontinuous density gradient centrifugation of washed erythrocytes of five subjects (three adults and two cord bloods). Free and total carnitine concentrations were determined in each gradient fraction to compare the carnitine content of less dense with more dense erythrocytes. Erythrocyte, leukocyte, and reticulocyte counts and hemoglobin were measured on all fractions of each gradient. The density gradient studies showed that the highest proportion of reticulocytes were associated with the least dense gradient fractions of all five subjects. Linear regression analyses revealed significant positive correlations (r = 0.94 to 0.99, P less than 0.02 to P less than 0.001) between the number of reticulocytes per fraction and the total or free carnitine concentrations per fraction for all subjects. No correlation was found between free or total carnitine and hemoglobin, number of erythrocytes, or number of leukocytes per fraction. It appears that erythrocyte carnitine is localized in circulating reticulocytes which have mitochondria and carnitine-dependent fatty acid metabolism.

A previously unrecognized hypochromic anemia associated with marked normoblastemia during the newborn period is reported. One male and two female siblings and a first cousin had a hypochromic anemia and marked normoblastemia (300 to 900 normoblast index per 100 white blood cells) at birth. Globin chain synthesis studies on peripheral blood of the proband at birth indicated the presence of alpha-thalassemia trait with possible reduced gamma chain synthesis. Studies of globin chain synthesis on the father, two older affected siblings of the proband, and the proband at 1.5 years of age revealed alpha-thalassemia trait. The data suggest this complex alpha-thalassemia-like condition as a new syndrome associated with marked neonatal normoblastemia.

The interaction of bis-(N-maleimidomethyl) ether with oxyhemoglobin results in covalent linkages of both maleimide groups, converting them to succinyl derivatives of beta93 Cys and beta97 His at their sulfhydryl and imidazolyl side chains, respectively. The resultant hemoglobin is stable, and reveals a left-shifted oxyhemoglobin equilibrium curve in which cooperativity is abolished. This reagent readily traverses the red cell membrane and prevents the sickling reaction upon deoxygenation. It appears to affect none of the activities of the red cell enzymes adversely, nor does it appear to affect the red cell membrane. Since there are several defined effects on the stereochemical status of the molecule conferred by interaction with bis-(N-maleimidomethyl) ether, the precise mechanism of the anitsickling effect remains to be elucidated. A more subtle perturberant will be required to specify a precise antisickling effect. By use of bis-(N-maleimidomethyl) ether a precise locus on the beta chain of human hemoglobin S can be perturbed to produce the desired effect.

Pulmonary alveolar macrophages (PAM) obtained from healthy human cigarette smokers generated greater pressure in filtration through small cylindrical pores than PAM from nonsmoking controls. A well standardized hamster smoking model was employed to study the structural basis for the impaired PAM filtration accompanying cigarette smoke exposure. Hamsters also demonstrated increased PAM filtration pressure through cylindrical pores less than half a cell diameter in size after inhalation of cigarette smoke, but not after exposure to vapor phase smoke that had been strained through a particle filter. Cigarette smoker PAM were equally filterable as control through larger diameter channels, and showed comparable improvements in filterability with cytochalasin B treatment. Altered PAM filtration was associated with the formation of characteristic cytoplasmic smoker inclusions, an increase in cell size, and loss of redundant, ruffled surface membrane. The study of smoker and control PAM separated into different sizes on the basis of variations in cell density suggested that discrepancies in cell size were insufficient to explain the filtration disparity. A loss of availability of surface membrane for deformation appeared to be the most important factor responsible for the impaired filtration.

Rabbit PAM deformability was evaluated by positive-pressure filtration through Nucleopore membranes of well-specified pore diameter. The PAM filtration method was standardized and was influenced by apparatus variations (pore size, flow rate, cell concentration), environment (temperature, pH, divalent cations, protein concentration), and differences in PAM cell volume. The influence of phagocyte function on filtration deformability was evaluated by exposing PAMs to pharmacologic and physiologic agents with somewhat exclusive influences on phagocyte physiology. Agents that interact with microfilament contractile protein (N-ethylmaleimide, cytochalasin B) altered deformability profoundly, but no effect was observed with agents interacting with microtubules (vinblastine, colchicine). Agents that cause general PAM activation (phorbol myristate acetate) or stimulate chemotaxis (F-Met-Leu-Phe) increased deformability. On the contrary, PAM deformability was not changed by phagocytosis of Staphylococcus aureus or latex beads. Pharmacologic agents that alter PAM adhesion (aspirin, indomethacin, physiologic dose hydrocortisone) or inhibit glycolysis (2-deoxyglucose) had no influence on filtration deformability. Filtration PAM deformability reflects passive whole cell rigidity, which appears to be determined by the state of polymerization of the actin-myosin microfilament complex.