The effect of dexamethasone and promethazine in combination with buparvaquone in the management of East Coast fever.

The effects of dexamethasone and promethazine on the amelioration of pulmonary oedema in East Coast fever were investigated. The clinical effects of these drugs were further investigated when used in conjunction with the antitheilerial drug, buparvaquone. In the first experiment, 15 crossbred (Friesian x Zebu) steers were divided into four groups. With the exception of the animals in group IV, that served as a control group all the others were infected with Theileria parva sporozoites. On the second day of the febrile reaction, the steers in groups I and II were treated with dexamethasone (0.1 mg/kg) and promethazine (1 mg/kg), respectively. Group III steers served as the infected untreated controls. On the fifth day of the febrile reaction the animals in groups I, II and III were infused intravenously with tattoo ink suspension and 1 h later sacrificed for post-mortem examination and tissue sampling. The clinical picture indicated that both drugs significantly mitigated dyspnoea and the post mortem examination revealed a significant reduction in morphological changes. Tattoo ink particle count reflected a significant (P< 0.01) reduction in vascular leakage in the treated animals, with promethazine being significantly (P < 0.05) more effective than dexamethasone in this respect. In the second experiment, 18 steers were infected with T. parva sporozoites, and then were randomly allotted into three groups each of which contained six animals. After the onset of ECF clinical signs, the animals in the first two groups were treated with buparvaquone in combination with either dexamethasone (group I) or promethazine (group II), and the third group was treated with buparvaquone alone. The results indicated that all the animals in groups I, II and III recovered well and no significant differences were observed in clinical disposition between the groups. Two months later, serum samples were collected from the refractory animals and demonstrated the presence of antibodies against T. parva. When the animals were subsequently artificially challenged with T. parva, none of them succumbed to clinical disease. The same T. parva stabilate stock was used in both experiments and it proved to be infective in a separate batch of steers.

Incidence of gross reproductive abnormalities in small east African zebu cattle.

Reproductive organs from mature Small East African zebu (SEAZ) heifers and cows slaughtered at the Morogoro abattoir were collected twice a month and evaluated over a period of 12 months. Out of the 402 animals from which reproductive organs were taken, 54% were pregnant, 24% were actively cycling and 22% were non-cycling. Various gross abnormalities were observed in the reproductive organs of about 16% of the cattle, and the major reproductive abnormality in both total and the non-cycling animals was various degrees of fibrous adhesion between the ovary and the infundibulum and mesosalpinx. It is concluded that, contrary to common belief, a majority of the female SEAZ cattle that are slaughtered are fertile.

Dichapetalum spp toxicity in cattle at a farm in Tanzania.

An investigation was carried out to establish the cause of mortalities during the dry season in cattle at a state livestock replacement farm at Kibaha in the Coast Region of Tanzania. Studies included a thorough review of the farm records, interviews with the farm staff, screening for parasites through examination of blood and lymph node smears, clinical examination of sick animals, and a survey of the grazing lands as well as postmortem examinations of the dead cattle. Circumstances incriminated plant poisoning as the cause of the deaths. A systematic survey of the pastures indicated a preponderance of Dichapetalum spp poisonous plants in areas in which most of the affected cattle had been grazing. Leaves of these plants were collected, dried, powdered and fed or drenched to 6 goats and 24 wistar rats. Lesions in animals that died resembled those seen in dead cows--pulmonary congestion and edema, froth in the airways, hemorrhagic gastroenteritis, and variable quantities of serous effusions into serous cavities. Although Dichapetalum spp occur especially in coastal regions, previous cases of poisoning by this plant in Tanzania have not been published. This report documents a systematic toxicological trial to verify the poisonous potency of this plant.

Antinutritional effects of Crotalaria ochroleuca (marejea) in animal feed supplements.

Antinutritional effects of Crotalaria ochroleuca (marejea) in animal feed supplements were studied in rats fed marejea supplemented rations. Six rations supplemented with 10, 30 or 50% marejea seed or leaf meals were tested for toxic effects compared with 1 control ration. Thirty-five mature rats whose mean weight was 55.8 g were randomly assigned to the 7 rations. The daily performance was observed. After 35 d of the feeding, the rats were killed and a postmortem examination was performed to assess the condition of the internal organs. Mean daily gains were 0.15 and 0.93 g, total gains were 5.20 and 32.55 g, and the final weights were 163.42 and 188.75 g for the rats on marejea seed and marejea leaf meals, respectively. Growth performance deteriorated with increasing levels of seed and leaf supplementation. Rats on 10% marejea leaf meal had normal growth performance. Postmortem examination showed that internal organs of animals on 30 or 50% marejea seed and 50% marejea leaf meals were severely damaged. Rats on 10% marejea leaf meal had normal internal organs. It appears that supplementation with marejea leaf meal at low levels could bring about good results but more experiments are required for verification of the precise levels and forms of supplementation.

Enzyme changes in remodelling epithelial cells: a histochemical study of the rat jejunum in vivo during and following exposure to deoxycholic acid.

Loops of rat jejunum were exposed in vivo to different concentrations of deoxycholic acid (DOC; 0, 2.5, 5, 10 and 20 mM). Following a 30 min exposure period, DOC was washed out of the loops and the intestines were allowed to recover for 15 or 150 min. Frozen tissue for enzyme histochemistry was collected during exposure and following the recovery periods. As shown previously, exposure to DOC caused a dose-dependent loss of epithelial cells at the villous tips and denudation of the lamina propria. Flattened epithelial cells bordering the denuded areas were, however, responsible for a rapid restoration of epithelial continuity, which was completed within 15 min. In the present study, these flattened cells showed normal reactivity for non-specific esterase and succinate dehydrogenase. In contrast, following a prolonged recovery period (150 min), a subpopulation of enterocytes at the villous tips that otherwise appeared normal showed decreased reactivity for brush border enzymes and non-specific esterase, and a positive reaction for mucin. A shutdown in the synthesis of cytoplasmic enzymes and redistribution of cell surface enzymes could be responsible for these late occurring enzyme changes, that were consistently observed after 150 min of recovery from DOC at 20 mM. Alternatively, retention of goblet cells and/or a modification in enzyme synthesis may explain the presence of mucin that was demonstrated in the epithelial cells which had low enzyme reactivity.

Alterations of ultrastructure and of cytoplasmic filaments in remodelling rat jejunal epithelial cells during recovery from deoxycholate.

Structural features associated with reversibility of lesions induced by deoxycholic acid (DOC) were studied by electron microscopy and immunofluorescence techniques. Tied jejunal loops were incubated in vivo with 2.5-20 mmol/l DOC in isotonic solution. Immediately after this treatment, or after a recovery period of 15 or 150 minutes following washout of the bile acid, the loops were excised and processed. DOC produced epithelial lesions whose severity and reversibility were concentration-dependent. Ultrastructural features associated with the reversibility of the lesions were particularly apparent in specimens exposed to 10-20 mmol/l DOC. These features included cell flattening with the formation of thin, veil-like structures into the eroded area by cells at the edges of the erosions. Immunofluorescence studies showed a redistribution of actin and cytokeratin filaments to the margins and leading edges of the flattened cells. It is suggested that cell flattening and migration are responsible for the rapid morphological recovery of the injured epithelium. Actin and cytokeratin appear to be instrumental in the remodelling and migration.

Peyer's patches in experimental Salmonella dublin infection in calves. Microvascular and epithelial changes contributing to atrophy of lymphoid follicles.

Six calves were infected per os with Salmonella dublin and killed nine hours to seven days later. Early changes included occlusion of capillaries with a hyaline material, particularly in the ileal Peyer's patch (PP). Central areas of the follicles contained hemorrhages and edema. In later stages the follicle-associated epithelium (FAE) of both the jejunal and ileal PP was fused with the adjacent epithelium and the follicles were collapsed. As judged from 5'nucleotidase histochemistry, follicles were depleted of lymphocytes whereas reticular cells were retained. Carbonic anhydrase (CA) histochemistry showed a decreased reaction in the ileal FAE and a reduced amount of CA reactive material in the follicles of the ileal PP, indicating loss of FAE differentiation and function. Hyaline material and fibrinous thrombi were seen occluding the blood capillaries and the lymphatics, respectively. The villi were atrophied and covered with thick fibrin deposits. Using antifibrinogen antibodies, immunoperoxidase stained fibrin in the lymphatics and the lumenal deposits but not the hyaline material in the capillaries. Reaction for CA indicated that this hyaline material originated from erythrocytes. Factors contributing to the follicle atrophy may include anoxia due to stasis in the microcirculation with the formation of erythrocyte thrombi, and reduced lymphopoiesis due to a decrease in the stimulating factors provided by the FAE.

Morphological and functional recovery following exposure to deoxycholic acid. A study in the rat small intestine in vivo.

Whereas many studies deal with teh deleterious effects of unconjugated deoxycholic acid on epithelial morphology, few are concerned with the reversibility of these effects, the subject of the present study. Tied jejunal loops in the rat were incubated for 30 minutes with deoxycholic acid (2.5-20 mmol/litre) in isotonic solution. Immediately after this treatment, or after a subsequent recovery period of 15 or 150 minutes following wash out of the bile acid, the loops were excised, fixed and examined by light microscopy and scanning electron microscopy. Deoxycholic acid produced epithelial lesions whose severity and reversibility depended on the concentration applied. However, even the severely affected epithelium obtained by treatment at 10-20 mmol/litre was reverted to normal within 150 minutes, and a substantial normalisation was observed already after 15 minutes. An exception to this rapid restoration of epithelial morphology and integrity was noted in villi which had suffered necrosis of lamina propria. The revertion of epithelial pathology was paralleled with a normalisation of glucose absorption, of the potassium ion and protein content of the loop fluid, and of the paracellular epithelial permeability as measured with 3-H-poly-ethylenglycol. Morphometry showed that deoxycholic acid caused villous atrophy without affectin the crypt length. The extent and reversibility of this atrophy depended on dose and recovery time as above. It is suggested that the remarkably fast morphological restitution proceeds mainly by process involving cellular remodelling and migration.

The toxicity of Burttia prunoides in rats and goats.

Studies of the toxicity of the leaves and seeds of the plant Burttia prunoides from Singida district of Tanzania were conducted in rats and goats. One group of rats was drenched with a decoction of powdered seeds or leaves while the other group was fed rations containing different proportions of powdered seeds or leaves. The goats were drenched with aqueous suspensions of powdered seeds or leaves. All animals were observed for behavioral changes and clinical signs. Leaves were not toxic to the rats or the goats. In rats the seeds induced a severe acute central nervous system (CNS) disorder and death and also a subacute syndrome characterized by emaciation and milder CNS signs. In goats the seeds induced a severe CNS disorder where unlike the rats the animals did recover. Postmortem findings in the rats included hemorrhage and inflammation of the glandular stomach and edema and congestion of the lungs, brain and mucosa of the gastrointestinal tract. The kidneys were congested and showed complete nephrosis of the proximal tubular epithelium. Livers were congested and had focal areas of necrosis. The findings in this study resemble those obtained in calves and sheep using the same plant.