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The one-electron reduction product of nitrate, the NO3^2- radical, was reinvestigated because of the contemporary interest in its reactivity in high-level liquid radioactive systems. Indirect observations suggest that the same dianion is produced by the precursor to the solvated electron. The redox potential of the couple NO3^-/NO3^2- was calculated, using several ab initio approaches combined with semiempirical solvation models, to be E° ≈ −1.1 V vs NHE. Using the theoretical prediction to guide the experiment, we find a value of E° = −0.89 V at zero ionic strength. Kinetic and free-energy-relationship arguments are used to question the acid−base equilibria and reaction mode that converts the NO3^2- to the oxidizing NO2 radical. It is proposed that the reaction of the dianion with various general acids is an O^2- (i.e., water or OH^-) transfer to the acid and not proton transfer to NO3^2-. Implications of the highly negative redox potential of the dianion and the existence of the protonated forms to practical systems are discussed.

Two patients exhibiting a highly unusual preleukemic syndrome with marked reticulocytosis, hypochromia, and microcytosis are reported. This red cell phenotype has been investigated by means of HbF, HbA2, and i-antigen activity dosages, immunofluorescence labeling of F cells, reticulocyte survival, globin chain synthesis, and electron microscopy study. The marked reticulocytosis is explained by a delayed disappearance of the reticulum. Serum iron is normal, and a thalassemic syndrome is excluded because of a balanced alpha/non-alpha globin chain synthesis. Electron microscopy studies are consistent with a defect in iron uptake by erythroid cells. All the hematologic data and investigations are similar to those observed for the Belgrade laboratory rat. It is hypothesized that the low expression of HbF and i- Ag associated with microcytosis are related to a prolongation of erythroid maturation as reflected by abnormal reticulocyte survival.

The nature of cells present in the blood, marrow, and spleen of patients with hairy cell leukemia is largely debated. These cells have been tentatively categorized on the basis of either monocytic or lymphocytic markers, and the accumulating data points to the fact that they share some characteristics of both cell types. Although hairy cells are known to lack myeloperoxidase-positive granules, present in normal human monocytes, we investigated the possible presence of other peroxidase activities differing from the granule-bound myeloperoxidase. The study was carried out with several methods based on the incubation of fixed and unfixed cells in the presence of diaminobenzidine and hydrogen peroxide. A peroxidase activity was found in hairy cells, located always in the endoplasmic reticulum but not in the Golgi apparatus or in any granule. By its cytochemical characteristics it appears to be closely related to that of tissue macrophages, activated blood monocytes, and other nonlymphocytic hematopoietic cells. This peroxidase is not found in lymphocytes with B or T phenotypes.

Surface immunoglobulins (sIg) were detected on human lymphocytes by immunoelectron microscopy with peroxidase-conjugated antibodies. Blood, marrow, and thymus cells from normal individuals and patients with lymphoproliferative disorders were examined. Samples were fixed before exposure to specific reagents. Normal lymphocyts with detectable sIg, i.e. B lymphocytes, were characterized by a villous surface; nonlabeled blood lymphocytes and thymocytes were smooth cells. Intermediate cells were also found which in sections appeared moderately villous and labeled, thus identified as B lymphocytes. Further evidence for a relationship between villous surface and sIg was given by the finding of a few lymphocytes with polar concentration of labeled microvilli. In chronic lymphocytic leukemia patients, most cells exhibited a villous surface with parallel variations of the number of microvilli and of anti-immunoglobulin-binding capacity. However, some labeled smooth blastic cells were also observed. On the other hand, abnormal lymphocytes from Sézary's syndrome which could exhibit segments of villous membrane had no detectable sIg. This study confirms that in most cases human B lymphocytes have a characteristic surface appearance and that the detection of sIg in normal lymphocytes correlates with the presence of microvilli.

Morphogenesis of stem nodules in Sesbania rostrata was studied over a period of 6 days after inoculation with an appropriate species of Rhizobium. Nodulation sites were initially slightly raised, circular areas 0.3 to 0.6 mm in diameter and 4 to 5 mm apart in vertical rows along the length of the stem. Each site was underlaid by an adventitious root primordium. A site became susceptible to infection by a specific Rhizobium sp. when the root primordium broke through the epidermis, leaving a fissure. Rhizobia multiplied within this fissure and colonized the exposed intercellular spaces. The infection extended inward as narrow, branched intercellular threads moved into a cortical meristematic zone, where cell division was initiated, and invagination of infection thread branches into adjacent plant cells followed. Rhizobia were released into the plant cells and surrounded immediately by plant membrane. Intracellular rhizobia divided actively, leading to bacteroid-filled cells. Infected areas enlarged and coalesced as the nodule matured.

The nature of cells present in the blood, marrow, and spleen of patients with hairy cell leukemia is largely debated. These cells have been tentatively categorized on the basis of either monocytic or lymphocytic markers, and the accumulating data points to the fact that they share some characteristics of both cell types. Although hairy cells are known to lack myeloperoxidase-positive granules, present in normal human monocytes, we investigated the possible presence of other peroxidase activities differing from the granule-bound myeloperoxidase. The study was carried out with several methods based on the incubation of fixed and unfixed cells in the presence of diaminobenzidine and hydrogen peroxide. A peroxidase activity was found in hairy cells, located always in the endoplasmic reticulum but not in the Golgi apparatus or in any granule. By its cytochemical characteristics it appears to be closely related to that of tissue macrophages, activated blood monocytes, and other nonlymphocytic hematopoietic cells. This peroxidase is not found in lymphocytes with B or T phenotypes.

REFRACTORY ANEMIA (R.A.) is a convenient term to describe those acquired idiopathic chronic disease characterized by a failure of erythropoiesis with or without changes in granulopoiesis and/or thrombopoiesis. Patients with R.A. are noteworthy for the normal or increased cellularify of the bone marrow.1–8All patients with R.A. may be considered as possibly pre- leukemic. Of particular interest is the fact that R.A. erthropoiesis has many striking similarities to that normally seen in the fetus.

In a case of refractory anemia with an excess of myeloblasts in the bone marrow and with thrombocytopenia, examinations of the blood cells under the electron microscope have revealed nucleated cells similar in size to small lymphocytes. Some of these lymphocytelike cells have scanty cytoplasm identical to that of giant platelets present in the blood, which are pathologic in view of their highly developed system of membranes. In the perinuclear space and in short segments of the smooth endoplasmic reticulum, these blood micromegakaryocytes exhibit a peroxidase activity that is identical to that of mature megakaryocytes of normal bone marrow. They also spread over glass like giant platelets. In the past these nucleated cells could well have been confused with atypical lymphocytes, because on stained slides their atypical appearance makes identification difficult.