Carotid body chemosensory function in prolonged normobaric hyperoxia in the cat

The effects of normobaric hyperoxia on carotid body chemosensory function in the cat were studied. The hypothesis was that carotid body chemosensory function would be affected by chronic exposure to 100% O2 at sea level. It was based on the assumptions that carotid body tissue is exposed to high PO2 because of its high blood flow and that its O2 chemosensing mechanism is sensitive to O2 radical-induced reactions. Twelve cats were exposed to 100% O2 for 60-67 h, and 10 control cats were maintained in room air at sea level. They were anesthetized with pentobarbital sodium (Nembutal), and chemosensory afferents from a cut carotid sinus nerve were isolated and identified. The responses of single or a few clearly identifiable chemoreceptor afferents to isocapnic hypoxia and hypercapnia during hyperoxia and to the bolus injections of cyanide, nicotine, and dopamine were studied. We found that chronic hyperoxia severely blunted or eliminated the O2-sensitive response of the carotid chemoreceptors while augmenting the hypercapnic response. The response to cyanide but not to nicotine and dopamine were attenuated. Thus the hypoxic and hypercapnic responses that normally interact were separable. The lack of the cyanide response was consistent with the lack of the hypoxic response, suggesting a possible shared mechanism of carotid chemoreceptor response. Qualitatively normal responses to dopamine and nicotine indicated that the respective receptors were relatively intact after chronic exposure to hyperoxia and that the sensory nerves themselves were not affected by the prolonged O2 exposure.     

The armadillo: a model for the neuropathy of leprosy and potentially other neurodegenerative diseases

Leprosy (also known as Hansen’s disease) is an infectious peripheral neurological disorder caused by Mycobacterium leprae that even today leaves millions of individuals worldwide with life-long disabilities. The specific mechanisms by which this bacterium induces nerve injury remain largely unknown, mainly owing to ethical and practical limitations in obtaining affected human nerve samples. In addition to humans, nine-banded armadillos (Dasypus novemcinctus) are the only other natural host of M. leprae, and they develop a systemically disseminated disease with extensive neurological involvement. M. leprae is an obligate intracellular parasite that cannot be cultivated in vitro. Because of the heavy burdens of bacilli they harbor, nine-banded armadillos have become the organism of choice for propagating large quantities of M. leprae, and they are now advancing as models of leprosy pathogenesis and nerve damage. Although armadillos are exotic laboratory animals, the recently completed whole genome sequence for this animal is enabling researchers to undertake more sophisticated molecular studies and to develop armadillo-specific reagents. These advances will facilitate the use of armadillos in piloting new therapies and diagnostic regimens, and will provide new insights into the oldest known infectious neurodegenerative disorder.     

Cloning and characterization of RNF6, a novel RING finger gene mapping to 13q12.

Myeloproliferative disorders frequently show deletions or rearrangements of the long arm of chromosome 13. We report here the cloning of RNF6, a new gene that maps close to the chromosome 13 breakpoint in a case of myelofibrosis with a t(4;13)(q26;q12). RNF6 is predicted to encode a 685-amino-acid protein with a coiled-coil domain and a RING-H2 finger at the amino and carboxy terminis, respectively. In addition, we have identified a novel motif, Lys-X-X-Leu/Ile-X-X-Leu/Ile (KIL motif), that is located shortly upstream of a subset of RING-H2 proteins, including RNF6. Drosophila g1, rat Neurodap1, and mouse Praja1. FISH and physical mapping indicated that RNF6 is located at 13q12.2 close to marker D13S1121, and it is oriented from telomere to centromere. RNF6 is not disrupted by the t(4;13).     

Detection and distribution of scorpion (Heterometrus bengalensis) venom in rabbit tissues by enzyme-linked immunosorbent assay (ELISA).

ELISA was carried out to detect distribution of scorpion venom in experimental animal tissues. The venom content of different tissues was in the order, liver greater than kidney greater than spleen greater than lung greater than heart greater than diaphragm greater than brain. Tissue distribution of venom antigen in the envenomental subject by ELISA will provide a better approach for serotherapy.     

Investigations on Graphene-Based Ultra-Wideband (UWB) Microstrip Patch Antennas for Terahertz (THz) Applications

Plasmonics - An investigation on graphene-based hexagonal microstrip patch antenna has been carried out in this article. The hexagonal-shaped radiators have been designed and modified by...