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Biomedical subjects

C A Rossi

Publications and source records attributed to C A Rossi.

At least 73 records · Page 4Linked to original sources
PubMed1988

Characterization of attenuated strains of Rift Valley fever virus.

The wild-type ZH501 strain of Rift Valley fever (RVF) virus and two small-plaque strains (T1 and T46) derived from it were characterized by plaque size, pathogenicity for hamsters and ability to replicate in Vero cells. Additionally, a mutagenized, attenuated, large-plaque, vaccine-candidate strain of RVF virus (ZH548-M12) was also studied. Infections with either the ZH501 or T46 strain were uniformly fatal to hamsters. In contrast, nearly all hamsters infected with either the T1 or ZH548-M12 strains survived and were immune to challenge with 10(5) LD50 of the ZH501 strain. Both of these attenuated strains failed to replicate in Vero cells maintained at 41 degrees C, whereas the more virulent strains (ZH501 and T46) replicated at this temperature. The low virulence and ability to induce protection against lethal RVF virus challenge that is associated with the T1 and ZH548-M12 strains make them potential vaccine candidates.

Animals↗
PubMed1988

Aerosol transmission of Hantaan and related viruses to laboratory rats.

Hantaan, Seoul, and Puumala viruses were transmitted to 12-16-week-old female Wistar Rattus norvegicus by inhalation. The rodent infectious dose for each virus by intramuscular inoculation and by inhalation was determined, as was the infectious dose for Vero E-6 cells by direct plaque assay.

Aerosols↗
PubMed1987

Protective effect of endogenous coenzyme Q on both lipid peroxidation and respiratory chain inactivation induced by an adriamycin-iron complex.

Mitochondria from beef heart have been partially depleted of coenzyme Q by pentane extraction. It has been found that lipid peroxidation induced by an adriamycin-iron complex proceeds at a higher rate in this preparation than in coenzyme Q reincorporated mitochondria. Moreover in coenzyme Q depleted mitochondria both NADH and succinate oxidase activities result more affected. These observations indicate that endogenous coenzyme Q can effectively protect mitochondria from membrane lipid oxidative damage induced by adriamycin-iron and can reduce the inactivation of NADH and succinate oxidases.

Animals↗
PubMed1986

Effect of ethanol intake on human erythrocyte membrane fluidity and lipid composition.

Erythrocyte membrane fluidity was evaluated in chronic alcoholic patients without any liver alteration, assuming different daily ethanol amounts, and in normal subjects and related to ghost fatty acid and total lipid composition obtained by high resolution gas chromatography. Erythrocyte membrane fluidity was significantly increased in a dose dependent manner in chronic alcoholic patients respect to normal subjects. This real fluidizing effect of ethanol "in vivo" was attributed mainly to a significant increase in the polyunsaturated fatty acids amount in patient ghosts in comparison with control subjects. On the other hand the cholesterol/phospholipid ratio was not significantly affected by chronic ethanol assumption.

Adult↗
PubMed1985

Interaction of smooth muscle relaxant drugs with calmodulin and cyclic nucleotide phosphodiesterase.

Some smooth muscle relaxant drugs with an unknown mechanism of action have been tested for their interaction with calmodulin and with calmodulin-induced cyclic nucleotide phosphodiesterase (PDE) activity. The affinity of these drugs for calmodulin does not parallel their inhibitory effect on the calmodulin activation of PDE. The lack of parallelism could be due to a binding of the drugs to different sites on calmodulin; furthermore a binding of papaverine, octylonium bromide and felodipine to PDE molecule might also be considered to explain their inhibitory effect on PDE basal activity. The myolytic effect of octylonium bromide and pinaverium bromide may be due to their interaction with calmodulin-dependent systems.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Effect of extrinsic incubation temperature on the ability of Aedes taeniorhynchus and Culex pipiens to transmit Rift Valley fever virus.

Studies were conducted to examine the effects of extrinsic incubation (EI) temperature on the vector competence of Egyptian Culex pipiens and North American Aedes taeniorhynchus for Rift Valley fever (RVF) virus. Following per os exposure, infection rates in Ae. taeniorhynchus remained relatively constant at 55%, 56%, and 59% for mosquitoes held at EI temperatures of 13, 26, and 33 degrees C, respectively. In contrast, significantly fewer Cx. pipiens became infected when held at 13 degrees C (38%), than when held at 26 degrees C (75%) or 33 degrees C (91%). In both species, viral dissemination and transmission occurred earlier in mosquitoes held at high temperatures as compared to those held at low temperatures. Following EI at 26 or 33 degrees C, Cx. pipiens were able to transmit virus as early as 1 day after inoculation with RVF virus. However, 3 days were required before the first transmissions by inoculated Ae. taeniorhynchus. Temperature of EI affected these 2 species differently in their ability to transmit RVF virus. Because of the importance of EI temperature on infection and transmission rates, as well the length of the EI period, the role of EI temperature will need to be evaluated for each virus and vector pair.

Aedes↗
PubMed1984

Enhanced arboviral transmission by mosquitoes that concurrently ingested microfilariae.

Infection, dissemination, and transmission of an arbovirus in mosquitoes are enhanced by concurrent ingestion of microfilariae. Ingestion of Rift Valley fever virus alone infected only 64 percent of female Aedes taeniorhynchus. Of these, only 5 percent of refeeding mosquitoes actually transmitted virus. In contrast, ingestion of the same amount of virus from concurrently microfilaremic (Brugia malayi) gerbils resulted in 88 percent infection and 31 percent transmission. Enhanced transmission of virus may be attributed to increased transit of virus across the midgut wall. Endemic filariasis may promote arbovirus transmission in nature.

Aedes↗
PubMed1984

Effect of some smooth muscle relaxant drugs on calcium-related phenomena.

Some smooth muscle relaxant drugs devoid of anticholinergic action have been tested for their interaction with calmodulin, calmodulin-stimulated cyclic nucleotide phosphodiesterase activity, and uterine membrane binding sites for nitrendipine and adenosine. The myolytic activity of octylonium bromide and pinaverium bromide may be due to their interaction with calmodulin-dependent systems. Trimebutine maleate does not bind either to calmodulin or to nitrendipine and adenosine receptors. Tiropramide has no effect on calmodulin-dependent systems and on Ca2+ channels but it shows a competition for the A2-type adenosine receptors.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

Increased mosquito feeding on Rift Valley fever virus-infected lambs.

Experiments were conducted to determine whether or not mosquitoes exhibited an increase in feeding on Rift Valley fever (RVF) virus-infected lambs as compared to uninfected ones. Overall, when given a choice between a viremic lamb, or its uninfected twin, 65% (1,264/1,943) of the engorged female Culex pipiens obtained blood from the viremic lamb. This excess of feedings on viremic lambs was demonstrated regardless of the age of the lambs, or the time period between inoculation of the lambs and exposure to mosquitoes. With 3-day-old and 6- to 8-week-old lambs, 66% of the mosquitoes obtained blood from the viremic lamb. At 28, 48, and 52 hours after infection, the percentages of mosquitoes feeding on viremic lambs were 72, 68, and 64, respectively. Temperature, as measured by the difference in temperature of the viremic lamb minus that of the control lamb, was positively correlated with mosquito feedings on young lambs (3 days old), but not on older lambs (6 to 8 weeks old). When Cx. pipiens and Aedes taeniorhynchus were simultaneously given the opportunity to feed on 3-week-old lambs, a significantly higher percentage of engorged Cx. pipiens (94/108, 87%) fed on the viremic lamb than did engorged Ae. taeniorhynchus (187/350, 53%). The data generated by this study (e.g., an excess of feedings on the viremic lambs) warrant further study to determine the significance of this observation under field conditions.

Aedes↗
PubMed1983

Purification and properties of two lectins from the latex of the euphorbiaceous plants Hura crepitans L. (sand-box tree) and Euphorbia characias L. (Mediterranean spurge).

1. From the latex of two members of the plant family Euphorbiaceae, Hura crepitans L. (sand-box tree) and Euphorbia characias L. (Mediterranean spurge), two lectins were purified by affinity chromatography on acid-treated Sepharose 6B followed by elution with D-galactose. 2. The lectin from E. characias is a single molecular species with Mr 80 000, made up of two identical subunits with Mr 40 000, and is a glycoprotein containing 11% carbohydrate. 3. The lectin from H. creptians appears as a mixture of three isolectins with Mr 140 000, consisting of four different subunits with Mr values 37 500, 35 500, 31 000, and 29 000. 4. Both lectins have haemagglutinating activity, with no specificity for human blood groups. The haemagglutinating activity is inhibited by D-galactose and by galactose-containing oligosaccharides. 5. The lectin from H. crepitans is mitogenic to human T-, but not to B-, lymphocytes. The latex of E. characias is mitogenic to T- and, to a lesser extent, to B-, lymphocytes, but the purified E. characias lectin has no mitogenic activity. 6. The lectin from H. crepitans, but not that from E. characias, inhibits protein synthesis by a rabbit reticulocyte lysate.

Amino Acids↗
PubMed1982

Isolation of putative benzodiazepine receptors from rat brain membranes by affinity chromatography.

The benzodiazepine receptor from rat brain was solubilised and purified 5200-fold by affinity chromatography. The affinity column contained an immobilized benzodiazepine (delorazepam) and biospecific elution with 6 mM-chlorazepate was achieved. The purified receptor is apparently homogeneous in SDS-polyacrylamide gel electrophoresis. The native protein had a molecular weight of 240,000, and the subunit one of 60,000. The dissociation constant (KD) is 8 nM for [3H]diazepam. A correlation exists between the value of affinity obtained for benzodiazepine derivatives and their known pharmacological effectiveness.

Animals↗
PubMed1980

Mitogenic and haemagglutinating properties of a lectinpurified from Hura crepitans seeds.

A lectin from the seeds of Hura crepitans has been purified to homogeneity by affinity chromatography on acid-treated Sepharose CL-6B, followed by elution with D-galactose. The lectin is a glucosamine-containing glycoprotein with a molecular weight of 120 00, as determined by sucrose density gradient centrifugation, and consists of identical subunits with molecular weights of 30 000. The amino acid composition and total neutral sugar content are given. The Hura lectin agglutinates directly erythrocytes from several species, without specificity for human blood groups. In all cases, with the exception of pig erythrocytes, agglutination was enhanced by neuraminidase. Agglutination was inhibited, in decreasing order of potency, by N-acetyl-D-galactosamine, by D-galactose and galactose-containing oligosaccharides. The lectin has mitogenic activity for purified human T lymphocytes but not for B lymphocytes, and the activity is still evident at a concentration as low as 10 ng/ml. The specific mitogenic activity increases throughout the purification process.

Acetylgalactosamine↗