Radiosensitivity of human bone marrow granulocyte-macrophage progenitor cells and stromal colony-forming cells: effect of dose rate

Study of the radiation biology of human bone marrow hematopoietic cells has been difficult since unseparated bone marrow cell preparations also contain other nonhematopoietic stromal cells. We tested the clonogenic survival after 0.05 or 2 Gy/min X irradiation using as target cells either fresh human bone marrow or nonadherent hematopoietic cells separated from stromal cells by the method of long-term bone marrow culture (LTBMC). Sequential nonadherent cell populations removed from LTBMC were enriched for hematopoietic progenitors forming granulocyte-macrophage colony-forming unit culture (GM-CFUc) that form colonies at Day 7, termed GM-CFUc7, or Day 14 termed GM-CFUc14. The results demonstrated no effect of dose rate on the D0 or n of fresh marrow GM-CFUc (colonies greater than or equal to 50 cells) after plating in a source of their obligatory growth factor, colony-stimulating factor (CSF) (GM-CFUc7 irradiated at 2 Gy/min, D0 = 1.02 +/- 0.05, n = 1.59 +/- 0.21; at 0.05 Gy/min, D0 = 1.07 +/- 0.03, n = 1.50 +/- 0.04; GM-CFUc14 at 2 Gy/min, D0 = 1.13 +/- 0.03, n = 1.43 +/- 0.03; at 0.05 Gy/min, D0 = 1.16 +/- 0.04, n = 1.34 +/- 0.05). There was a decrease in the radiosensitivity of GM-CFUc7 and GM-CFUc14 derived from nonadherent cells of long-term bone marrow cultures compared to fresh marrow that was observed at both dose rates. In contrast, adherent stromal cells irradiated at low compared to high dose rate showed a significantly greater radioresistance (Day 19 colonies of greater than or equal to 50 cells; at 2 Gy/min, D0 = 0.99 Gy, n = 1.03; at 0.05 Gy/min D0 = 1.46 Gy, n = 2.00). These data provide strong evidence for a difference in the radiosensitivity of human marrow hematopoietic progenitor compared to adherent stromal cells.     

Photoaffinity labeling of the purified skeletal muscle calcium antagonist receptor by a novel benzothiazepine, [3H]azidobutyryl diltiazem

Previous photoaffinity-labeling studies with [3H]azidopine, (+) [3H]PN200-110, and [3H]LU 49888 have demonstrated that 1,4-dihydropyridines (nifedipine-like drugs) and phenylalkylamines (verapamil-like drugs) bind exclusively to the 165-kDa alpha 1 subunit of skeletal muscle calcium channels. However, it has not been conclusively determined whether benzothiazepines (diltiazem-like drugs), which represent the third group of calcium antagonists, also bind to the alpha 1 subunit. Here we report data obtained with a newly developed benzothiazepine photoaffinity probe, [3H]azidobutyryl diltiazem. This drug competes with diltiazem for the benzothiazepine-binding site and, in purified calcium channel preparations, specifically labels the 165-kDa polypeptide which does not change its electrophoretic mobility upon disulfide reduction. These data show that benzothiazepines, just like 1,4-dihydropyridines and phenylalkylamines, bind to the alpha 1 subunit of the skeletal muscle calcium channels.     

Immunologic control of a parasitic arthropod. Identification of a protective antigen from Boophilus microplus

Cattle can be vaccinated against the tick Boophilus microplus by inducing an immunologic reaction against Ag in the tick gut. The uptake of antibody during feeding leads to severe damage to the parasite. One of the responsible tick gut Ag has now been purified and characterized: the Bm86 Ag. It is a membrane-bound glycoprotein present in very low abundance in extracts of partially engorged adult female ticks. It has an apparent m.w. of 89,000, an isoelectric point of 5.1 to 5.6 and an affinity for wheat germ lectin. Microgram amounts of this Ag are able to induce effective protection in cattle against the parasite, as shown by the decreased survival of ticks on vaccinated cattle and a reduction in engorgement weights and egg laying capacity of the survivors. Antisera to the Ag react with the surface of digest cells in the tick gut. As a result of the reaction with antibody, the endocytotic activity of these cells, which is a critical step in bloodmeal digestion in this tick, is strongly and rapidly inhibited. A number of peptides from this Ag, produced by digestion of the reduced and alkylated protein with endoproteinase lys-C, have been sequenced. One peptide has significant amino acid sequence homology with the epidermal growth factor precursor and a second peptide has homology with a putative protective antigen from Plasmodium falciparum.     

固氮酶铁钼辅因子FeMo-co在水与非水体系内重组活力与催化活力的比较研究

 本文提出一种测定FeMo-co催化活力的反应体系,用此反应体系,在测定FeMo-co催化活力的过程中,FeMo-co与变种UW45抽提液的重组活性始终保持不变。讨论了水含量、还原剂对FeMo-co催化活力和重组活力的影响。     

Pathogenesis of wild-type and leaderless foot-and-mouth disease virus in cattle.

Four calves were experimentally infected via aerosol with foot-and-mouth disease virus. Two were infected with a wild-type virus derived from a full-length infectious clone (A12-IC), and two were infected with a clone-derived virus lacking the leader gene (A12-LLV2), with euthanasia and tissue collection at 24 and 72 h postexposure (hpe). Clinical disease was apparent only in the animal given A12-IC and euthanized at 72 hpe. In situ hybridization revealed that the animal infected with A12-IC and euthanized at 24 hpe had abundant viral nucleic acid in the lung, present in clusters of positive cells in the respiratory bronchiolar epithelium and associated subepithelial regions. At 72 hpe in the A12-IC-infected calf, viral nucleic acid in the lung was present in interstitial areas, and in addition, viral nucleic acid was detectable in epithelial tissues around histologically apparent vesicles. In animals infected with A12-LLV2, viral nucleic acid was detectable in the lung at both 24 and 72 hpe, but staining revealed a more localized distribution with less nucleic acid than was found in animals given A12-IC. Therefore, it appears that after aerosol exposure to A12-IC, early replication is in the region of the lung, with subsequent dissemination to distal sites. In comparison, the A12-LLV2 virus is much less widely disseminated in the lung at 24 hpe, with no lesions or virus detectable in secondary sites at 72 hpe. The greatly reduced pathogenicity of A12-LLV2 may make it an excellent candidate for a modified live viral vaccine.     

Transport ofl-lactate by cultured rat brain astrocytes

Several reports indicate that lactate can serve as an energy substrate for the brain. The rate of oxidation of this substrate by cultured rat brain astrocytes was 3-fold higher than the rate with glucose, suggesting that lactate can serve as an energy source for these cells. Since transport into the astrocytes may play an important role in regulating nutrient use by individuals types of brain cells, we investigated the uptake ofl-[U-¹⁴C]lactate by primary cultures of rat brain astrocytes. Measurement of the net uptake suggested two carrier-mediated mechanisms and an Eadie-Hofstee type plot of the data supported this conclusion revealing 2 Km values of 0.49 and 11.38 mM and Vmax values of 16.55 and 173.84 nmol/min/mg protein, respectively. The rate of uptake was temperature dependent and was 3-fold higher at pH 6.2 than at 7.4, but was 50% less at pH 8.2. Although the lactate uptake carrier systems in astrocytes appeared to be labile when incubated in phosphate buffered saline for 20 minutes, the uptake process exhibited an accelerative exchange mechanism. In addition, lactate uptake was altered by several metabolic inhibitors and effectors. Potassium cyanide and -cyano-4-hydroxycinnamate inhibited lactate uptake, but mersalyl had little or no effect. Phenylpyruvate, -ketoisocaproate, and 3-hydroxybutyrate at 5 and 10 mM greatly attenuated the rate of lactate uptake. These results suggest that the availability of lactate as an energy source is regulated in part by a biphasic transport system in primary astrocytes.This data was presented in part at the meeting of the Federation of American Societies for Experimental Biology in May 1989.     

Urinary excretion of bioactive amines and their metabolites in psychiatric patients receiving phenelzine

Phenelzine [2-phenylethylhydrazine] (PLZ), a potent inhibitor of monoamine oxidase (MAO)-A and-B, is used widely in psychiatry. We have studied the effects of PLZ administration on urinary excretion of several bioactive amines and their metabolites in psychiatric patients. Urine samples (24-hour) were collected prior to treatment and again at 2 and 4 weeks of treatment with PLZ (30–90 mg daily in divided doses). Amines and metabolites analyzed included 2-phenylethylamine (PEA), m-and p-tyramine (m-and p-TA), phenylacetic acid (PAA), m-and p-hydroxyphenylacetic acid (m-and p-OH-PAA), tryptamine (T), 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), normetanephrine (NME), 3-methoxy-4-hydroxyphenylglycol (MHPG), 3-methoxytyramine (3-MT), and homovanillic acid (HVA). Levels of PEA, p-TA, 5-HT, and T were elevated during treatment with PLZ, but no significant changes in urinary excretion of the acid metabolites PAA, p-OH-PAA, and 5-HIAA were observed. Urinary levels of the noradrenaline metabolites NME and MHPG were increased and decreased, respectively; a similar pattern was observed with the dopamine metabolites 3-MT and HVA. There was an elevation in levels of m-TA and a decrease in its acid metabolite m-OH-PAA during the treatment with PLZ.     

Structure determination of feline panleukopenia virus empty particles

Various crystal forms of the single-stranded DNA, feline panleukopenia virus (FPV), a parvovirus, have been grown of both full virions and empty particles. The structure of empty particles crystallized in an orthorhombic space group P2₁2₁2₁, with unit cell dimensions a = 380.1 Å, b = 379.3 Å, and c = 350.9 Å, has been determined to 3.3 Å resolution. The data were collected using oscillation photography with synchrotron radiation. The orientations of the empty capsids in the unit cell were determined using a self-rotation function and their positions were obtained with an R-factor search using canine parvovirus (CPV) as a model. Phases were then calculated, based on the CPV model, to 6.0 Å resolution and gradually extended to 3.3 Å resolution by molecular replacement electron density averaging. The resultant electron density was readily interpreted in terms of the known amino acid sequence. The structure is contrasted to that of CPV in terms of host range, neutralization by antibodies, hemagglutination properties, and binding of genomic DNA. © Wiley-Liss, Inc.     

The Evolution of Allomothering Behavior Among Colobine Monkeys: Function and Opportunism in Evolution

The great majority of Old World monkey females are interested in infants, particularly very young ones. Characteristically, females will approach infants cradled by their mothers and subsequently attempt to touch or hold them. For Cercopithecine monkeys, the subfamily that includes the baboons and macaques, caretaking attempts by females other than the mother are ordinarily unsuccessful, at least during the first two or three weeks of life. Mothers are highly possessive of their offspring and will not surrender them to substitute infant-caretakers. In striking contrast, among the other major subfamily of Old World monkeys, the Colobines, mothers readily allow extensive and sometimes prolonged infant carrying and handling by other females (allomothering), even on the first day of life. This paper reviews the traditional functional explanations for these different maternal systems. Stressing opportunism in evolution, the paper suggests that the social and/or genetic benefits alone are not adequate to account for the origins of allomothering behavior among Colobines. Instead, emphasis is given to the kind of ancestral social structure and its environmental context that might allow such a behavioral system to begin. It is hypothesized that, relative to the Cercopithecines, who do not exhibit infant-sharing, the dental morphology and digestive system of the Colobines produced food-acquiring and food-processing advantages that, in effect, reduced intragroup feeding competition and, concomitantly, reduced the importance of status differences between females. Such a social structure could permit the emergence of allomothering behavior since, for all the participants in this activity pattern, there are varying benefits that contribute to individual fitness. [Colobine, allomothering, functions, opportunism, dietary adaptations, social structure]     

Scanning and transmission electron microscopic study of the supraependymal macrophages in the lateral ventricles of the toad brain

Transmission and scanning electron microscopy of the lateral ventricles of the toad brain revealed the presence of supraependymal cells that have the features of macrophages. Based solely on their surface morphology three different cell forms could be identified. The most frequently observed cells are flat and multipolar, and have a smooth or ruffled surface. The second type is spherical with a ruffled surface and occurs either singly, in which case it lacks processes, or in clusters from which processes radiate. The third type has surface blebs and numerous thin, smooth processes. However, when specimens that had been examined in the scanning electron microscope are viewed in the transmission electron microscope, all cells appear to belong to a single cell type. All cells viewed closely resemble macrophages in that they contain nuclei with clumped chromaffin, single cisternae of rough endoplasmic reticulum, numerous dense bodies, and many Golgi complexes. In addition, when horseradish peroxidase (HRP) was perfused into the ventricles, reaction product was found a short time thereafter within cytoplasmic vacuoles, and after a longer period within dense bodies. Because of their ultrastructural resemblance to macrophages and their capacity to ingest HRP, we suggest that these cells function as phagocytes and, as such, act to remove foreign materials from the cerbrospinal fluid.