Sequential testicular and epididymal damage in Zebu bulls experimentally infected with Trypanosoma vivax.

Six Zebu bulls aged between 31 and 34 months exhibiting good libido were used to study sequential testicular and epididymal damage in Trypanosoma vivax infection. Three bulls were infected with T. vivax, while the other three served as controls. All infected bulls became parasitaemic by day 5 post-infection and developed clinical trypanosomosis with rapidly developing anaemia. Representative bulls, one from each of the infected and control groups, were sacrificed on days 14, 28 and 56 post-infection. Testes and epididymides from these animals were studied histopathologically after processing and staining with haematoxylin and eosin (H and E). Testicular degeneration developed in all the infected bulls characterized by depletion of spermatogenic cells and destruction of interstitial tissue. The most severe testicular degeneration occurred in the bull that was sacrificed 56 days post-infection. Epididymal sperm reserves were 36%, 4% and 0%, respectively, in infected bulls that were sacrificed on days 14, 28 and 56 post-infection. The 0% epididymal sperm reserve may suggest complete cessation of spermatogenesis. It was concluded from this study that T. vivax infection of Zebu bulls could cause severe testicular and epididymal damage that may result in infertility or even sterility of the affected animals at early infection stages not previously thought.

Comparative studies on erythrocyte sialic acid levels in apparently healthy indigenous Nigerian poultry species.

The erythrocyte surface sialic acid levels of 200 apparently healthy indigenous Nigerian poultry species (pigeons, guinea fowls, ducks and chickens, n = 50 for each species) presented for slaughter at a poultry abattoir in Zaria, Nigeria was determined. Other parameters determined were packed cell volume (PCV) and plasma total protein (TP) concentration. The mean erythrocyte surface sialic acid concentration of pigeons, guinea fowls, ducks and chickens were 7.88 +/- 2.51, 14.6 +/- 2.51, 17.6 +/- 2.51 and 14.2 +/- 2.51 mg mg(-1) respectively. There was a statistically significant difference between the mean erythrocyte surface sialic acid concentration of all the species of poultry sampled (P < 0.05). The high erythrocyte surface sialic acid concentration in the indigenous Nigerian poultry species could be responsible for their resistance to infectious diseases, whose aetiologic agents produce neuraminidases. The mean PCV of the pigeons, guinea fowls, ducks and chickens were 46.22 +/- 6.91, 38.24 +/- 6.91, 36.50 +/- 6.91 and 36.46 +/- 6.91% respectively. The difference between the mean PCV values of pigeons on the one hand and guinea fowls, ducks and chickens on the other was statistically significant (P < 0.05). A negative correlation (r = -0.36, P < 0.05) between mean erythrocyte surface sialic acid concentrations and PCV was observed, i.e. the birds with the highest mean PCV values had the lowest levels of erythrocyte surface sialic acid. There was no correlation between TP concentration and either erythrocyte surface sialic acid concentration or PCV values. It is suggested, based on this study, that erythrocyte sialic acid types in these species should be determined, as the results may be vital in selective breeding.

Characterization of a sialidase (neuraminidase) isolated from Clostridium chauvoei (Jakari strain).

A sialidase from Clostridium chauvoei (Jakari strain), an indigenous bacterial strain that causes blackleg in Nigerian cattle and other ruminants was isolated and partially purified by chromatography on DEAE cellulose, hydroxyapatite and phenyl agarose columns. The enzyme migrated as a 65-kDa protein after electrophoresis on sodium dodecyl sulphate polyacrylamide gels. It was optimally active at pH 4.5 and 40 degrees C with an activation energy (Ea) of 13.40 kJ mol(-1). It had Km and Vmax values of 170 microM and 200 micromole h(-1) mg(-1) respectively with fetuin as substrate. When sialyllactose (Neu5Ac2,3 lactose) was used as substrate the Km and Vmax values were 8 microM and 5 micromoles min(-1) mg(-1) respectively. The Clostridium chauvoei sialidase cleaved sialic acids from RBC ghosts of sheep, horse, goat, cattle, pig and mice as well as mouse brain cells, albeit at different rates. The enzyme was activated by Ca2+ and Mg2+ and inhibited by the group-specific reagents diethylpyrocarbonate (DEP) and N-ethylmalemide (NEM). The sialidase inhibitors, 2,3 didehydroneuraminic acid (Neu5Ac2,3en) and paranitrophenyl oxamic acid (pNPO) inhibited the enzyme competitively with Ki values of 40 and 30 microM respectively.

Columbin inhibits cholesterol uptake in bloodstream forms of Trypanosoma brucei-A possible trypanocidal mechanism.

The diterpenoid furanolactone (columbin) from Aristolochia albida inhibited growth of culture forms of Trypanosoma brucei. In vitro analysis of the compound at 5-250 microg/ml showed complete lysis of the parasites within 10-20 minutes post incubation. At 50 microg/ml, columbin killed about 50% of the parasites which initially appeared swollen under phase contrast microscopy. Also the total amount of cholesterol diminished dose-dependently in the presence of 10-100 microg/ml of columbin after a 3-day incubation period. In vivo analysis of the compound in T. brucei-infected mice revealed that 25 mg/kg administered for 3 consecutive days, completely cleared the parasites from the peripheral circulation. However, columbin could not clear parasites in the cerebrospinal fluid.

Haemagglutination inhibition antibodies, rectal temperature and total protein of chickens infected with a local Nigerian isolate of velogenic Newcastle disease virus.

Changes in values of haemagglutination inhibition (HI) antibody titre, rectal temperature (RT) and total protein (TP) were determined for Shaver Brown chickens infected with Newcastle disease virus (NDV) Kudu 113. The infected chickens came down with Newcastle disease by day 3 post infection (PI). The major clinical signs were depression, greenish diarrhoea, paralysis of legs and wings, opisthotonus and torticolis. Mortality and morbidity were 52% and 1000%, respectively. There were haemorrhagic lesions in the wall of the intestine, proventricular mucosa and caecal tonsils. There were necrosis and mononuclear cell infiltration of the liver, kidney and spleen. There was a significant increase in daily mean HI antibody titres from days 3 to 9 PI. Similarly, significant rise in daily mean RTs were noticed in the infected chickens from days 1 to 13 PI. On the other hand, there was a decrease in daily mean TP concentrations of infected chickens, beginning from day 3 PI, and the lowest concentration of 2.60 +/- 0.15 g/dl was obtained by days 7 and 11 PI. The values of HI, RT and TP for the control chickens were relatively constant during the experiment. The correlation coefficient (r) between HI and RT was positive and highly significant (r = 0.725, p<0.001), while the relationship between HI and TP was negative but highly significant (r = -0.712, p<0.001). It was concluded that NDV Kudu 113 induced increases in values of HI and RT, which occurred concurrently with a decrease in TP concentrations of infected chickens.

The inhibition of Clostridium chauvoei (jakari strain) neuraminidase activity by methanolic extracts of the stem barks of Tamarindus indicus and Combretum fragrans.

The inhibition of neuraminidase from Clostridium chauvoei (jakari strain) with partially purified methanolic extracts of some plants used in Ethnopharmacological practice was evaluated. Extracts of two medicinal plants, Tamarindus indicus and Combretum fragrans at 100-1000 microg/ml, both significantly reduced the activity of the enzyme in a dose-dependent fashion (P < 0.001). The estimated IC50 values for Tamarindus indicus and Combretum fragrans were 100 and 150 microg/ml respectively. Initial velocity studies conducted, using fetuin as substrate revealed a non-competitive inhibition with the Vmax significantly altered from 500 micromole min(-1) mg(-1) to 240 micromole min(-1) mg(-1) and 340 micromole min(-1) mg(-1) in the presence of Tamarindus indicus and Combretum fragrans respectively. The KM remained unchanged at 0.42 mM. The computed Index of physiological efficiency was reduced from 1.19min(-1) to 0.57min(-1) and 0.75min(-1) with Tamarindus indicus and Combretum fragrans as inhibitors respectively.

Aetiology and prevalence of canine anaemia in Zaria: a review of 2139 cases observed at the Veterinary Teaching Hospital of the Ahmadu Bello University, Zaria, Nigeria (1990-2003).

An investigation was conducted at the Ahmadu Bello University Veterinary Teaching Hospital (ABUVTH) between January, 1990 and September, 2003 to determine the aetiology and prevalence of canine anaemia in Zaria, Nigeria. Out of the 5278 mongrel dogs presented during the period 1990-2003, 2139 (40.5%) were found to be anaemic, with packed cell volume (PCV) values ranging from 7 to 36%. The clinical signs presented by these dogs include: Pale mucous membranes, weakness, depression, anorexia/inapettence and reduced activity. About 50 dogs (about 1%) with helminths and haemoparasitic infestations had high PCV values (37-40%) without clinical presentation of anaemia or disease. Most of the dogs with anaemia (n = 2016 or 94.2%) had parasitic infestations. About 1580 (about 74%) of the anaemic cases, attributed to parasitic infestations occurred between May and October. A few dogs (n = 55, 2.6%) had anaemia due to poor nutrition, while 68 (3.2%) had anaemia with unknown cause. The public health significance of the parasites reported in this study is discussed.

Pathogenesis and pathology of blackleg in ruminants: the role of toxins and neuraminidase. A short review.

There is no consensus on the pathogenesis of blackleg infection that occurs in ruminants, but toxins and neuraminidase produced by Clostridium chauvoei are believed to play a significant role in the pathogenesis of the disease. This paper provides an update on the role of toxins and neuraminidase in the pathogenesis and pathology of the disease. The use of neuraminidase inhibitors to manage clinical blackleg infections is therefore an alternative therapeutic protocol that should be thoroughly investigated. It is suggested that in vivo clinical trials should be carried out to determine the mechanism of action and clinical efficacy of neuraminidase inhibitors.