Biomedical subjects

K A Esievo

Publications and source records attributed to K A Esievo.

At least 19 recordsLinked to original sources

PubMed2000

Effects of Trypanosoma vivax on pregnancy of Yankasa sheep and the results of homidum chloride chemotherapy.

Three groups of pregnant Yankasa ewes, made up of six ewes in each group were assigned at random to first, second and third trimester of pregnancy studies. The ewes were experimentally infected with T. vivax to study the effects of the infection on pregnancy and the results of Novidium Chemotherapy. Three pregnant uninfected ewes served as controls. Fourteen days post infection, the ewes in each trimester study, were paired by weight and assigned to two groups of three ewes each. One group was treated with Novidium while the other group remained untreated. Of the three ewes in each group, one ewe was killed humanely at 21 days post infection and another at the end of the trimester period. In the first trimester, a ewe with partial fetal resorption was observed among the untreated ewes. Fetal death in-utero and expulsion of an autolyzed fetus was observed among the treated ewes. In the second trimester, abortion and almost complete fetal resorption were observed among the untreated ewes. Fetal death in-utero and expulsion of an autolyzed fetus was observed among the treated ewes. In the third trimester, abortions were observed among the untreated ewes. Abortion of a live fetus and a case of dystocia were observed among the treated ewes. Ewes in the second and third trimesters of pregnancy were more susceptible to the infection, with ewes in the third trimester being most susceptible, as measured by the number of abortions and death of ewes. Fetuses from the untreated ewes in the three trimesters of pregnancy were lower in body weights, than the fetuses from the treated ewes. The uninfected control ewes carried the pregnancies to term. Novidium chemotherapy at 14 days post infection was not beneficial in ameliorating the pathogenicity of T. vivax infection on pregnancy in Yankasa ewes. T. vivax infection of only 14 days was enough to cause irreversible pathology in Yankasa fetuses evidenced by death of fetuses in-utero, dystocia and abortions irrespective of Novidium chemotherapy.

Animals↗

PubMed1999

Studies of infectivity and pathogenicity of an isolate of Trypanosoma evansi in Yankasa sheep.

The course of experimental infection and pathogenicity of an isolate of Trypanosoma evansi were investigated using eight infected and six uninfected control Yankasa sheep. The sheep were each infected intravenously via the jugular vein with approximately 2.0 x 10(6) T. evansi parasites. The effects of the parasite on body temperature, packed cell volume (PCV), haemoglobin, erythrocytes, total protein, were monitored three times a week for approximately 9 weeks. Body weights were determined once every week for the duration of the experiment. The results showed that all the infected sheep were positive for the parasite. The prepatent period varied between 3 and 6 days. T. evansi produced parasitaemic waves at an average of 8.3 days interval. Two distinct forms of the disease were produced namely, acute (4-14 days postinfection), and chronic (43-59 days postinfection). Anaemia was a distinct feature of the disease. While the mean rectal temperatures were significantly elevated (P < 0.05), the mean values of the haematological parameters of the infected sheep dropped significantly (P < 0.05) compared to the preinfection levels. Observed clinical signs included pale mucous membrane, epiphora, loss of appetite, emaciation, dullness and rough hair coat together with fluctuating pyrexia which in most cases coincided with rise in parasitaemia. It is suggested that the isolate of T. evansi is pathogenic for Yankasa sheep.

Animals↗

PubMed1998

Effects of acute bovine trypanosomosis (Trypanosoma vivax) on plasma kinetics of intravenously administered lactose.

Four calves infected with Trypanosoma vivax and four uninfected control calves were each injected intravenously with repeated doses of 0.5 g lactose kg-1 body weight, thrice daily at intervals of 4 h. Plasma samples were collected at specified time intervals and analysed for lactose. Pharmacokinetic parameters were calculated from the data. T. vivax infection delayed excretion of lactose from the body, thus leading to significantly (P < 0.001) increased biological half life (t1/2) and a significantly (P < 0.001) reduced elimination rate constant for lactose in the body. The apparent volume of distribution and total clearance of lactose were not affected by the infection. T. vivax infection also appeared to cause accumulation of lactose in the plasma after repeated intravenous administration.

Acute Disease↗

PubMed1996

Effect of acute Trypanosoma vivax infection on cattle erythrocyte glutathione and susceptibility to in vitro peroxidation.

During acute Trypanosoma vivax infection of calves, produced by intravenous inoculation, the mean packed cell volume and red blood cell counts of the infected animals decreased significantly (P < 0.05) between Days 6 and 13 post-infection (pi). The moderately severe normocytic anaemia started to develop during the first wave of parasitaemia which occurred from Day 2 pi and peaked between Days 4 and 5 pi. The mean erythrocyte glutathione (GSH) concentration of the infected calves decreased significantly (P < 0.05) from 58.4 +/- 11.4 mg 100ml-1 red blood cells (RBC) on Day 0 pi to 44.5 +/- 12.8 mg 100ml-1 RBC on Day 5 pi. As the GSH values recovered on Day 6 pi and increased thereafter, another slight decrease (P > 0.05) in GSH concentration occurred on Day 12 pi at the second peak of parasitaemia followed by a significant (P < 0.05) increase to 79.1 +/- 14.6 mg 100ml-1 RBC on Day 13 pi. In the uninfected calves, the mean GSH values ranged from 47.7 +/- 7.0 to 60.8 +/- 6.8 mg 100ml-1 RBC. When washed, erythrocytes of the infected and uninfected calves were separately challenged with hydrogen peroxide. They produced comparable amounts of thiobarbituric acid reactive substances as a measure of by-products of lipid peroxidation. This suggested that the ability of the erythrocytes to prevent peroxidative injury was not reduced, because GSH regeneration was probably enhanced and the antioxidant capacity of the erythrocytes was maintained.

Acute Disease↗

PubMed1995

Studies of experimental infection and cross-immunity between stocks of Cowdria ruminantium in Sokoto red goats.

The course of experimental infection and cross-immunity tests between stocks of Cowdria ruminantium were investigated using eight infected and four uninfected control Sokoto red goats. All eight infected goats reacted to the primary infection. The incubation period varied between 8 and 23 days. During the febrile reaction, the highest rectal temperature recorded was 40 degrees C and the lowest was 39.7 degrees C, compared with a range of 38.6 +/- 0.15 to 38.1 +/- 0.19 in control goats. Following the primary infection, each of the animals was treated with long-acting Tetracycline (Terramycin, Pfizer) at a dose of 20 mg kg-1 body weight to control the resulting temperature reaction. They were reinfected with the homologous stock 3 weeks after treatment to demonstrate whether they had become immune. The homologous challenge did not give any temperature reaction during 3 weeks of monitoring. They were then challenged with the heterologous C. ruminantium stock. This did not result in a febrile reaction during 3 weeks of monitoring. The observed cross-protection indicates antigenic similarity between the two stocks.

Animals↗

PubMed1994

Increased susceptibility of erythrocytes to in vitro peroxidation in acute Trypanosoma brucei infection of mice.

Trypanosoma brucei, Wamba strain, produced an acute infection in mice, and mortality was observed 2 days after the onset of parasitaemia which occurred 3-5 days postinfection. Anaemia was observed in the tail blood of the survivors. When washed erythrocytes from the heart blood were incubated in physiological saline containing 1.5% hydrogen peroxide, the erythrocytes of the infected mice produced significantly greater amounts of by-products of lipid peroxidation (measured as thiobarbituric acid reactive substances) than the erythrocytes of the control mice. This observation suggested that the infected mice may have a reduced ability in the prevention of free radical mediated lipid peroxidation in the erythrocyte membrane. It is concluded that peroxidative injury to the erythrocytes may contribute to the pathogenesis of anaemia in trypanosomosis.

Animals↗

PubMed1994

Biochemical differences (O-acetyl and glycolyl groups) in erythrocyte surface sialic acids of trypanotolerant N'dama and trypanosusceptible Zebu cattle.

Differences in the distribution and concentration of O-acetyl and glycolyl groups in erythrocyte sialic acids of trypanotolerant N'dama and trypanosusceptible Zebu cattle were investigated. Erythrocyte surface sialic acid concentrations were 25.4 +/- 5.5 mg per dl and 5.9 +/- 0.97 mg per dl in N'dama and Zebu animals, respectively. In N'damas, O-acetyl and glycolyl groups were present in concentrations of 16.4 +/- 4.3 mg per dl and 12.8 +/- 2.9 mg per dl, respectively, whereas the corresponding values in Zebus were 2.8 +/- 5.0 mg per dl and 7.6 +/- 1.7 mg per dl, respectively. The differences between N'dama and Zebu cattle in surface sialic acids and in O-acetyl and glycolyl groups were significant (P < 0.01 to < 0.001). N'dama erythrocyte sialic acids had more O-acetyl than glycolyl groups while those of Zebus had less O-acetyl than glycolyl groups. These findings may be relevant to the trypanotolerance of N'dama cattle.

Acetylation↗

PubMed1993

Phospholipase A2 from Trypanosoma congolense: characterization and haematological properties.

Phospholipase A2 was isolated from Trypanosoma congolense and purified to electrophoretic homogeneity. The enzyme appeared to exist in a dimeric form with subunit molecular weights of 16,500 and 18,000. It had a pH optimum of 6.8. Kinetic analysis with different substrates, showed that the enzyme had exceptional specificity for 1,2,dimyristoyl-sn-phosphatidylcholine and 1,2,dioleoyl-sn-phosphatidylcholine with Km values of 1.85 x 10(-3) M and 2.12 x 10(-3) M respectively. The Arrhenius plot was linear with an activation energy of 5.8 kcal mol-1. Inhibition studies with parahydroxy-mercuribenzoate and tributyl-tin-oxide were positive thus implicating a thiol group at the catalytic site of the enzyme. The enzyme was stable to heat treatment and possessed haemolytic and anticoagulating properties.

Animals↗

PubMed1992

Brain Na+ K+ ATPase and cholesterol in acute experimental trypanosomiasis.

Brain Na+ K+ ATPase activity has been found to decrease in experimental trypanosomiasis in rats infected with Trypanosoma congolense. Some physical features that affect membrane fluidity were also observed to be altered. The levels of cholesterol in the brain and free fatty acids in the serum were found to increase in the infected animals. These findings might be relevant to the development of brain lesions.

Animals↗

PubMed1992

Modulation of the calcium pump of the kidney and testes of rats infected with Trypanosoma congolense.

The activity of the CaMgATPase (Ca-pump) of the kidney and testes of Wistar rats infected with Trypanosoma congolense was studied during the course of infection. The activity of the enzyme in both organs was found to decrease with increase in parasitaemia. The transition temperature (Tc) decreased and activation energy (Ea) of the enzyme increased with increase in parasitaemia. The relevance of the Ca-pump in the pathogenesis of trypanosomiasis is discussed.

Animals↗

PubMed1991

In vitro magnesium- and calcium-induced sialidase activity in caprine intestinal mucosa cells.

Sialidase activity identical to 0.0196 mg per ml of liberated sialic acids (2.11 Units) was detected in small intestinal contents of goats. Mg++ and Ca++ induced in vitro detection in mucosa cells of both small and large intestines. Magnesium alone induced sialidase activities identical to 0.0128 mg per ml of liberated sialic acids (1.38 Units) and 0.0166 mg per ml (1.79 Units) in small and large intestinal mucosal cells, respectively. Mg++ and Ca++ together induced higher sialidase activities identical to 0.0191 mg per ml (2.06 Units) and 0.0194 mg per ml (2.09 Units) in small and large intestinal mucosal cells, respectively. The enzyme activity was slightly higher in large than in small intestinal mucosal cells. The results are discussed in relation to control of African animal trypanosomiasis.

Animals↗

PubMed1990

Electrophoresis of bovine erythrocyte sialic acids: existence of additional band in trypanotolerant Ndama cattle.

Mild acid-hydrolysis of erythrocyte surface sialic acids of the trypanotolerant Ndama and the trypanosusceptible White/Fulani Zebu breeds of cattle was performed. The cleaved sialic acids from the two breeds of cattle were simultaneously subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE), along with commercial standard N-acetylneuraminic acid (MW 309.28), blank gel and plasma proteins. The cleaved sialic acids migrated in the globulin fractions, as shown by the plasma protein electrophoresis. While the Ndama and the Zebu erythrocytes had one migrating band each of which coincided with the standard N-acetylneuraminic acid, the Ndama had another trailing band of sialic acid, of an estimated molecular weight of 30 kDa, which may account for the higher erythrocyte sialic acid concentrations of the Ndama. This additional band was absent in the Zebu. All these bands were readily reproducible.

Animals↗

PubMed1987

Erythrocyte sialic acid in human sickle-cell disease.

Membrane-bound erythrocyte surface sialic acid concentrations in sickle-cell human patients (SS) and in control patients with sickle-cell trait (AS) and normal genes (AA) were assayed. The erythrocyte sialic acid concentration was significantly (P less than 0.001) higher in sickle-cell patients than in non-sicklers and although the concentration was higher in AS than AA individuals the difference was not significant (P greater than 0.05). The anaemic state of the SS patients was shown by a significantly (P less than 0.001) lower PCV than in non-sicklers. This finding is discussed in relation to membrane toughness and subsequent membrane loss leading to irreversible sickling of red cells in the deoxygenated state.

Adolescent↗

PubMed1986

Erythrocyte surface sialic acid in Ndama and Zebu cattle.

Erythrocyte surface sialic acid concentrations were measured in the trypano-tolerant Ndama and trypano-susceptible Zebu breeds of cattle. All animals were uninfected and had no records of previous exposure to infection by African pathogenic trypanosomes. Ndama adults had significantly (P less than 0.001) higher erythrocyte surface sialic acid concentrations than Ndama calves. Ndama adults and calves had significantly (P less than 0.001) higher erythrocyte surface sialic acid concentrations than Zebu adults. There were no significant differences between the packed cell volume (PCV), haemoglobin (Hb) concentrations and total leukocyte counts (WBC) of these breeds. The finding of much higher erythrocyte surface sialic acid concentrations (about 7-fold) in the Ndama than in the Zebu is discussed in relation to the induction of anaemia by trypanosome sialidase in both breeds and to how a relative trypano-tolerance may occur in the Ndama.

Animals↗

PubMed1984

Depleted serum haptoglobin in acute bovine trypanosomiasis.

Haemoglobin-binding protein (Haptoglobin, Hp) was assayed in the sera of control and zebu calves with acute T. vivax infection. Hp in control Zebu calves ranged between 123.5 and 236.5 mg dl-1 while Hp in the infected calves was too low to measure or absent. It was suggested that absence of Hp in the infected calves may be as a result of gradual intravascular haemolysis and removal of the Hp-Hb complex by the reticuloendothelial system.

Acute Disease↗

PubMed1983

Leukocyte response in experimental Trypanosoma vivax infection in cattle.

Eight Zebu cattle were infected with Trypanosoma vivax stock Y58, while 8 served as uninfected controls. The infected animals developed early leukopenia due to concomitant lymphopenia and neutropenia. It is suggested that an increase in trypanosomal antigens and neuraminidase in the infected cattle at this time may have an effect on peripheral leukocytes.

Animals↗

PubMed1983

Trypanosoma vivax, stock V953: inhibitory effect of type A influenza virus anti-HAV8 serum on in vitro neuraminidase (sialidase) activity.

Trypanosoma vivax stock V953 lysates were observed to produce neuraminidase (sialidase EC 3.2.1.18) in vitro, which cleaved neuraminic (sialic) acid from the substrate fetuin. The neuraminidase activity was proportional to the number of trypanosomes in the lysates, with 0.44, 0.88, and 1.75 X 10(6) trypanosomes producing 1.4 +/- 0.06, 3.1 +/- 0.1, and 6.7 +/- 0.1 micrograms of sialic acid liberated, respectively. Equal numbers of unlysed and lysed trypanosomes produced approximately the same amount of the enzyme. Trypanosome eluates stored at room temperature appeared to have lost neuraminidase activities within 4 days. An inhibition test for identifying the neuraminidase antigen on influenza viruses was performed in vitro on the T. vivax lysates. The inhibition test, using Type A influenza virus anti-HAV8 serum, showed a highly significant (P less than 0.0001) reduction in neuraminidase activities. The effect of equal amounts of influenza antiserum on serially diluted trypanosome lysates showed that 1 ml of influenza anti-HAV8 serum would inhibit a mean of 6.74 +/- 0.18 micrograms of T. vivax stock V953 neuraminidase activity.

Animals↗

PubMed1982

Variation in erythrocyte surface and free serum sialic acid concentrations during experimental Trypanosoma vivax infection in cattle.

Erythrocyte surface and free serum sialic acid concentrations were determined during experimental Trypanosoma vivax infection in cattle. All infected calves developed mild trypanosomiasis, with significant decreases in mean packed cell volume occurring 15, 16, 20, 22 and 24 days after infection. The anaemia was preceded by significant decreases in mean erythrocyte surface sialic acid concentrations on days 7, 13 and 14, with yet another significant decrease on day 31 after infection. These decreases in erythrocyte surface sialic acid concentrations coincided with the parasitaemic waves. Free serum sialic acid concentration, however, showed an increase, though non-significantly, on day 8, which coincided with both a decrease in erythrocyte surface sialic acid and the initial parasitaemic wave. It is postulated that the early anaemia observed in infected animals may be attributable to the activities of the circulating trypanosomes which produce neuraminidase which, in turn, cleaves off surface sialic acid, thus rendering the erythrocyte more prone to phagocytosis by the recticuloendothelial system.

Animals↗