NMR studies in solution of poly-L-proline

The isomerization of poly-L -proline in different solvents has been studied by NMR spectroscopy. Different resonance signals for the CH_α protons have been obtained for the two different helical conformations of thus compound, namely form I and form II.     

Inhibition of MEL cells' capacity to undergo erythroid differentiation by chemicals added during induction

Erythroid differentiation of murine erythroleukemia (MEL) cells, as induced by dimethyl sulfoxide, can be suppressed by chemicals at very low concentrations, not affecting cell viability and proliferation, if present in the culture medium between 18 and 24 h after addition of the inducer. The effect is apparent on the progeny of the treated cells and is determined, between day 3 and 5 following DMSO induction, as percent value of cells expressing the erythroid phenotype. Cultures showing decreased values are no longer terminal and a large number of clones, incapable of expressing the erythroid phenotype, can be isolated from them. In contrast, induced cultures are terminal if the added chemicals do not decrease the expression of the erythroid phenotype. Incorporation of thymidine into induced cultures reveals that maximal sensitivity of MEL cells to chemicals coincides with DNA duplication. In all affected cells, the inhibition to undergo erythroid differentiation is transmitted from one cell generation to the next.     

Kidney and lung injury in irradiated rats protected from acute death by partial-body shielding

Ninety-six CD-1 male rats were exposed to gamma-ray doses (0-25 Gy) in increments of 5 Gy. One femur, the surgically exteriorized GI tract, and the oral cavity were shielded during irradiation to protect against acute mortality from injury to the hematopoietic system, small intestine, and oral cavity. In addition, the thoraxes of half of the animals from each dose group were shielded. At approximately monthly intervals from 2 to 10 months after irradiation the hematocrit, plasma urea nitrogen (PUN), and 51Cr-EDTA clearance were measured. During the study 20 thorax-shielded and 19 thorax-irradiated animals died. All rats whose thoraxes received 25 Gy irradiation and three out of seven rats whose thoraxes received 20 Gy died 1 to 3 months postirradiation with massive pleural fluid accumulation. Shielding the thoraxes prevented this mode of death at these doses. Kidney injury was judged to be the primary cause of death of all thorax-shielded animals and 15- and 20-Gy thorax-irradiated animals. Animals with kidney damage had elevated PUN and reduced 51Cr-EDTA clearance and hematocrits. The relative merits of each of these end points in assessing radiation-induced kidney injury after total-body exposure are discussed.     

MORBILLIVIRUS INFECTION IN BOTTLENOSE DOLPHINS: EVIDENCE FOR RECURRENT EPIZOOTICS IN THE WESTERN ATLANTIC AND GULF OF MEXICO

Morbillivirus infection is widespread among odontocetes of the western Atlantic and Gulf of Mexico. Serologic evidence of infection in bottlenose dolphins, Tursiops truncatus , was first detected during an epizootic along the mid-Atlantic coast in 1987. Here, we report recurrent epizootics in the coastal dolphin population since at least the early 1980s based on serological surveys and regional stranding frequencies. The first observed epizootic of this series occurred in the Indian and Banana Rivers in 1982 and was followed by others on the mid-Atlantic coast in 1987–1988 and in the Gulf of Mexico between 1992 and 1994. This temporal pattern of infection is likely facilitated by the population size and its fragmentation into relatively discrete coastal communities. Introduction of morbillivirus into a community with a sufficient number of naive hosts may precipitate an epizootic, depending on the potential for transmission within the group. Propagation of an epizootic along the coast is probably determined by frequency of contact between adjacent communities and seasonal migrations.
Morbillivirus antibodies were also detected in serum from offshore bottlenose dolphins. The sero-prevalence in the latter may be higher than in coastal dolphins because of their close association with enzootically infected pilot whales ( Globicephala spp.). Occasional contact between offshore and coastal dolphins may provide an epizootiologic link between pilot whales and coastal dolphin communities.     

Postconflict social interactions among barbary macaques (Macaca sylvanus)

We investigated the occurrence of postconflict social interactions in a group of Barbary macaques (Macaca sylvanus)that live in a large enclosure. We collected data during the mating and the nonmating seasons and analyzed them via two methods. Separate analyses for the two seasons yielded very similar results. Reconciliation and redirection occurred. But we found no evidence for consolation and postconflict kin-oriented affiliation. The consistency of these findings with those on other species of Macacaindicates that reconciliation and redirection are typical postconflict social interactions of macaque victims.     

Effects of recombinant human gamma interferon on intracellular survival of Bordetella pertussis in human phagocytic cells

Abstract Several studies have demonstrated that Bordetella pertussis has the ability to enter and survive intracellularly within human polymorphonuclear leukocytes (PMNL) and human monocytes/macrophages. The effects of human recombinant gamma interferon (IFN-γ) on the survival of B. pertussis in PMNL and human monocytes, and on the oxidative burst activity of PMNL and human monocytes in response to B. pertussis were assessed in this study. IFN-γ partially increased intracellular killing of phagocytosed B. pertussis in human monocytes, as determined by an orange acridine-crystal violet assay. In contrast, IFN-γ did not enhance intracellular killing of B. pertussis in PMNL. No significant increase of superoxide production was noted in human monocytes in response to B. pertussis when stimulated with various concentrations of IFN-γ. The partial increase of B. pertussis killing by IFN-γ within monocytes, together with poor production of superoxide may explain how B. pertussis can survive within human phagocytic cells, and thus cause a more prolonged course of the disease.     

Effect of beta-N-oxalylamino-l-alanine on cerebellar cGMP level in vivo

Beta-N-oxalylamino-l-alanine (BOAA), a non-protein amino acid present in the seeds of Lathyrus Sativus (LS), is one of several neuroactive glutamate analogs reported to stimulate excitatory receptors and, in high concentrations, cause neuronal degeneration. In the present study, the in vivo acute effects of synthetic BOAA and LS seed extract were investigated on rat cerebellar cyclic GMP following intraperitoneal (10–100 mg/kg) or oral (100 mg/kg) administration of subconvulsive doses of toxin. Furthermore, the BOAA content in LS seeds and in the cerebellum of injected rats was determined by high performance liquid chromatograph analysis. A dose- and time-dependent increase of cerebellar cyclic guanosine monophosphate (cGMP) level was observed after intraperitoneal administration of synthetic BOAA or LS extract. The neurotoxin evoked a maximum stimulation 90 min after injection within the dose range of 50–75 mg/kg, elevating cGMP from basal levels of 5.3±0.5 pmol/mg protein to 15±1.3 pmol/mg protein. Similarly, the oral intake of LS-extracted neurotoxin resulted in the elevation of cGMP content. Kynurenic acid (300 mg/kg i.p.), a non specific excitatory amino acid antagonist, was effective in blocking LS BOAA-elicited cGMP enhancement. The data suggest that in the cerebellum acute administration of low concentrations of BOAA exert in vivo activation of glutamate receptors involved in the regulation of cGMP level.     

Unstable telocentric chromosome produced after centric misdivision of a 21q/21q translocated element

Summary An unstable telocentric chromosome was found in an individual with Down's syndrome and an unusual chromosomal mosaic, 46,XX, t(21q21q)+,21-/46,XX,21p-/45,XX,21-. As the 21q/21q chromosome was of paternal origin, based on the characteristics of its centromeric heterochromatin and on the characteristics of both 21 chromosomes of the father, it was concluded that its formation involved centric breakage and loss of centromeric material. The cell line with the 21p- chromosome may have originated from the translocation by an asymmetric misdivision of the reduced centromeric material. Of the two telocentrics produced by this fracture, one, possessing the smaller amount of centromeric apparatus, would be immediately lost; the other would be retained, but complete activity of its centromere would not be restored. It would therefore be unstable and might be lost.     

Two different populations of primitive erythroid cells in the ehick embryo.

Antibodies prepared against the two hemoglobins of the adult chick cross react with the two minor hemoglobins and do not react with the two major hemoglobins isolated from lysates of primitive erythroid cells of the 4-day-old embryo. The different immunological reactivities of the two primitive hemoglobin pairs have permitted us to discriminate, in smears of primitive erythroid cells, two populations on the basis of their hemoglobin contents.