Differential immune responses in mice infected with the tissue-dwelling nematode Trichinella zimbabwensis.

To improve diagnostic tools, immunotherapies and vaccine development for trichinellosis surveillance and control there is a need to understand the host immune responses induced during infection with Trichinella zimbabwensis, a tissue-dwelling nematode. In this study, we sought to determine immune responses induced in mice during T. zimbabwensis infection. The parasite strain used (Code ISS1209) was derived from a naturally infected crocodile (Crocodylus niloticus) and is the main Trichinella species prevalent in southern Africa. Sixty 6- to 8-week-old female BALB/c mice were randomly assigned to two equal groups: T. zimbabwensis-infected (n= 30) and the non-infected control group (n= 30). Levels of serum tumour necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), interleukin-4 (IL-4) as well as parasite-specific IgM, IgG, IgG1, IgG2a, IgG2b and IgG3 antibody responses were determined using enzyme-linked immunosorbent assay (ELISA). The cytokines and antibodies provided information on T-helper 1 (Th1)- and Th2-type, T-regulatory and antibody responses. Results showed that during the intestinal stage of infection, higher levels of parasite-specific IgM, IgG, IgG1 (P <  0.05) and IL-10 and TNF-α (P <  0.001) were observed in the Trichinella-infected group compared with the non-infected control group. In the parasite establishment and tissue migration phases, levels of IgG1 and IgG3 were elevated (P <  0.001), while those of IgM (P <  0.01) declined on days 21 and 35 post infection (pi) compared to the enteric phase. Our findings show that distinct differences in Th1- and Th2-type and T-regulatory responses are induced during the intestinal, tissue migration and larval establishment stages of T. zimbabwensis infection.

Metabolic and adaptive immune responses induced in mice infected with tissue-dwelling nematode Trichinella zimbabwensis.

Tissue-dwelling helminths are known to induce intestinal and systemic inflammation accompanied with host compensatory mechanisms to counter balance nutritional and metabolic deficiencies. The metabolic and immune responses of the host depend on parasite species and tissues affected by the parasite. This study investigated metabolic and immuno-inflammatory responses of mice infected with tissue-dwelling larvae of Trichinella zimbabwensis and explored the relationship between infection, metabolic parameters and Th1/Th17 immune responses. Sixty (60) female BALB/c mice aged between 6 to 8 weeks old were randomly assigned into T. zimbabwensis-infected and control groups. Levels of Th1 (interferon-γ) and Th17 (interleukin-17) cytokines, insulin and blood glucose were determined as well as measurements of body weight, food and water intake. Results showed that during the enteric phase of infection, insulin and IFN-γ levels were significantly higher in the Trichinella infected group accompanied with a reduction in the trends of food intake and weight loss compared with the control group. During systemic larval migration, trends in food and water intake were significantly altered and this was attributed to compensatory feeding resulting in weight gain, reduced insulin levels and increased IL-17 levels. Larval migration also induced a Th1/Th17 derived inflammatory response. It was concluded that T. zimbabwensis alters metabolic parameters by instigating host compensatory feeding. Furthermore, we showed for the first time that non-encapsulated T. zimbabwensis parasite plays a role in immunomodulating host Th1/Th17 type responses during chronic infection.

Impaction of the stomachs in farmed ostriches (Struthio camelus) in Botswana.

Impaction of the proventriculus, gizzard, and sometimes intestines due to sand was confirmed at postmortem in 25 cases involving ostriches (Struthio camelus). Although there was no age predisposition, impaction was more common in juvenile over 3 mo old. Clinical signs included sternal recumbency, outstretched neck, debility, and inability to stand. Palpation of the impacted stomachs gave a gritty sensation. Depletion of coronary fat was a consistent postmortem finding. The most common material causing impaction was sand. This report highlights impaction as one of the major causes of debility and death in intensively farmed ostriches. High levels of alkaline phosphatase coupled with low levels of plasma glucose, protein, and albumin detected in impacted ostriches may be useful diagnostic antemortem indicators of the syndrome.

Changes in serum levels of vitamin B12, feed intake, liveweight and hematological parameters in cobalt deficient small east African goats.

Thirty short-horned East African goats were divided into two groups (treatments 1 and 2) consisting of fifteen goats each. All the goats were fed on a cobalt deficient diet containing 0.02 mg Co/kg of dry matter for a period of twenty three weeks. Goats in treatment 1 were supplemented with an oral cobalt chloride drench. Cobalt deficiency developed in goats in treatment 2 after ten weeks when their serum vitamin B12 concentration fell below 200-250 pg/ml. Between the third and the twenty-third weeks of the experiment, the mean serum concentration of vitamin B12 was significantly (P < 0.01) higher in cobalt supplemented (289.6 +/- 40.76 pg/ml) than deficient (142.8 +/- 28.27 pg/ml) goats. Total dry matter intake, intake per metabolic body weight and liveweight changes were not significantly (P > 0.05) different between goats in the two treatments. Although packed cell volume, hemoglobin concentration, and erythrocyte count were significantly (P < 0.05) higher in cobalt adequate than deficient goats, these blood parameters were within the normal range for goats. It is suggested that although serum vitamin B12 standard for sheep is applied for goats, the latter species is likely to be more resistant to low dietary cobalt intake than sheep.

Hepato-protective potential of methanol extract of leaf of Ziziphus mucronata (ZMLM) against dimethoate toxicity: biochemical and histological approach.

BACKGROUND: The leaves of Ziziphus mucronata are used locally as food and a health drink; the leaf paste can also be used in the treatment of boils. The root of the plant is usually used in the treatment of a wide range of pains. OBJECTIVE: The study was carried out to evaluate the hepatoprotective potential of the methanol leaf extract of Ziziphus mucronata (ZMLM). METHOD: The extract was prepared by soaking in 70% methanol/water and rotary evaporation. The phenol content of extract was then estimated. Twenty five adult male Sprague dawley rats (aged 21 weeks) were divided into five groups of five rats each and treated as follows; normal control (NC) received distilled water. Dimethoate control (DC) (received 6 mg/kg.bw.day(-1) dimethoate dissolved in distilled water). Experimental Groups (E1) received dimethoate (6mg/kg.bw) + ZMLM (100 mg/kg.bw(-1)); (E2) received dimethoate (6 mg/kg.bw) + ZMLM (200 mg/kg.bw(-1)) and (E3) received dimethoate (6 mg/kg.bw) + ZMLM (300 mg/kg.bw(-1)). In both the cases a normal control and dimethoate control were kept to compare the results. After 90 days, blood was collected and rats were sacrificed to collect the liver tissue for biochemical assays and histological estimations. RESULTS: The results of E1 did not show much change from the normal control group but was significantly different from the dimethoate control group (P≤ 0.05). The preventive effect which was tested in E2 and E3 proved that the extract could almost retain the normal condition in 90 days time. Histological observations also agreed with the results obtained in biochemical parameters. CONCLUSIONS: Ziziphus mucronata methanol leaf extract possesses a preventive effect against dimethoate induced oxidative stress as observed in male albino Sprague Dawley rats.

The entrainment of breathing rhythm to stride frequency in the dik-dik antelope (Rhynchotragus kirki) with observations on the thermoregulatory consequences.

1. Three adult dik-dik antelopes with an average weight of 4.5 kg were used to investigate the rate of oxygen consumption (VO2) during exercise and the entrainment of respiratory rate with stride frequencies at running velocities between 2-11 km/hr. 2. The results of VO2 and the metabolic cost of horizontal locomotion were found to agree with what would be expected of an animal of this size. 3. Respiratory frequencies recorded during the most strenuous exercise were approximately 50% below the value observed when dik-diks are exposed to an ambient temperature (Ta) of 42 degrees C. 4. Respiratory evaporative heat loss was estimated to account for only 4% of the total heat production during exercise. 5. Respiratory frequencies were found to be entrained quite strongly to stride frequencies. The thermoregulatory consequences of this entrainment is discussed.

Metabolism and evaporative heat loss in the dik-dik antelope (Rhynchotragus kirki).

1. Under controlled conditions, the rate of oxygen consumption (VO2) respiratory frequency, evaporative water loss, heat balance, rectal (Trec) and surface temperatures were determined in the dik-dik antelopes at ambient temperatures (Ta) ranging from 1 to 44 degrees C. 2. The thermal neutral zone was found to be between 24 and 35 degrees C. 3. Respiratory frequency ranged between 27 and 630 breaths/min. 4. At a Ta of 44 degrees C, 95% of the heat produced by the dik-dik was lost via respiratory evaporation. Despite an increase in Trec, cutaneous evaporation did not increase. 5. During panting, VO2 increased in accordance with the expected Q10 effect, contrary to earlier findings. 6. Measurements of circadian rhythm [LD 12:12 (7-19) CT26 degrees C] in VO2 showed that the minimum VO2 (0.42 ml O2/g/hr) occurred at midnight while the maximum (0.78 ml O2/g/hr) occurred at midday. The 24 hr mean VO2 was 0.61 ml O2/g/hr. 7. These measurements suggest that in nature, determinants other than light may be responsible for triggering the variations observed in VO2.

Thermoregulation and heat balance in the dik-dik antelope (Rhynchotragus kirki): a field and laboratory study.

Experiments were conducted in the field to study the physiological responses of dik-dik antelope to direct solar radiation and shade. The results were compared to those obtained in the laboratory. The rates of metabolic heat production when the animals were exposed either to the sun or the shade were identical. Dik-dik antelopes lost about 50% more heat evaporatively when exposed to the sun compared to the shade at an ambient temperature (Ta) of 28 degrees C or a Ta of 40 degrees C in a climatic chamber. Heat storage in the laboratory at Ta 40 degrees C or at Ta 28 degrees C in the shade accounted for between 30 and 35% of the total heat production. The corresponding value in the sun was 55%. The net rate of heat gain under the sun was four times greater than under shade at 28 degrees C or in the laboratory at 40 degrees C. Behavioural mechanisms for avoidance of high insolation must constitute important adaptations that the dik-dik uses to avoid dehydration and dependence on drinking water in their natural environment.

The relationship between rate of oxygen consumption, heart rate and thermal conductance of the dik-dik antelope (Rhynchotragus kirkii) at various ambient temperatures.

1. The extent of cardiovascular adjustments to heat and cold were investigated between ambient temperatures of 5 and 45 degrees C by measuring conductance and the rates of oxygen consumption and heart beats. 2. Minimum heart rate was observed at 25 degrees C (114 +/- 9 beats/min). In the heat at 45 degrees C heart rate was observed to increase only slightly (127 +/- 12 beats/min) but in the cold -5 degrees C heart rate nearly doubled that at 25 degrees C. 3. Thermal conductance was on average 0.031 mlO2 (g. hr. degrees C)-1 below 25 degrees C but increased by more than 20 times at 40 degrees C. 4. A positive correlation between heart rate and rate of oxygen consumption was demonstrated below 25 degrees C and the relation may be of practical use.

The design and the role of the nasal passages in temperature regulation in the dik-dik antelope (Rhynchotragus kirkii) with observations on the carotid rete.

Exhaled air temperatures (Tex) and rectal temperatures (Trec) were measured in five dik-dik antelopes under controlled environmental temperatures (Ta) between 15 and 40 degrees C. In addition morphometric analysis of the nasal passages, gross and histological identification of the carotid rete were carried out in an attempt to illustrate a possible brain cooling system in this small ungulate. Below Ta of 30 degrees C, Tex decreased with decreasing Ta leading to the establishment of a temperature gradient of about 20 degrees C between Ta and Trec at a Ta of around 15 degrees C. At Ta of 30 degrees C Tex was approximately half a degree lower than the Trec. Gross and histological studies revealed the presence of carotid rete and profuse vascularisation of the nasal turbinates. Morphometric analysis established a mean volume density of the nasal passages (np) in the splanchnocranium (sp) (VV(np,sp], surface density (SV(np,sp] and harmonic mean width of the nasal passages (W) of 9.5%, 2.15 cm2/cm3 and 1.23 mm, respectively. Combined physiological and anatomical measurements suggest that the dik-dik may possess an efficient brain cooling and water conserving system. The design of the upper respiratory system in these antelopes may help these animals to tolerate the extremes of temperatures and insolation encountered in their habitat.

Thyroid hormones and metabolic rate during induction of Vitamin B12 deficiency in goats.

Vitamin B12 deficiency was induced in 15 small East African goats by feeding cobalt deficient Chloris gayana hay (containing 0.02 mg of Co/kg dry matter) over a 25 week experimental period. Cobalt was supplemented as an oral drench to supply 0.3 g of Co/goat/week to 15 treated goats. At intervals of 3-4 weeks, serum concentrations of Vitamin B12 , total thyroxine (TT4), free tetra-iodothyronine (FT4) and free tri-iodothyronine (FT3) were determined by radioimmunoassay, while the rate of resting metabolism was determined by measuring the goats' rate of oxygen consumption. Serum Vitamin B12 concentration was significantly higher (p<0.01) in cobalt-treated (289.6 +/- 40.76 pg/ml) than in control (142.8 +/- 28.27 pg/ml) goats. The mean serum TT4 concentration was significantly (p<0.01) higher in control (59.0 +/- 1.70 nmol/l) than in cobalt-treated (51.6 +/- 2.45 nmol/l) goats. However, the levels of FT4, FT3 and the rate of resting metabolism were unaffected by the goats' cobalt status. Furthermore, the goats did not lose weight or become anaemic.

The effect of mixing and translocating juvenile ostriches (Struthio camelus) in Botswana on the heterophil to lymphocyte ratio.

The possibility was investigated that translocation of juvenile ostriches from concrete-paved to sandfloored pens and mixing of batches of ostriches after such translocation constitute a stress strong enough to evoke changes in the ratio of heterophils to lymphocytes. Blood smears were obtained from 15 ostriches out of a group of 25 birds 4 and 2 days before and then 2 and 4 days after translocation. The heterophil to lymphocyte ratio changed from 0.27 and 0.37 on days 4 and 2, respectively, before mixing and translocation to 0.53 and 0.84 on days 2 and 4, respectively, after translocation. Mixing and translocating juvenile ostriches appears to constitute stress. This information is important for the onfarm management of juvenile ostriches to enhance their welfare and productivity.

A comparative study of basal metabolism and thermoregulation in a folivorous (Colobus guereza) and an omnivorous (Cercopithecus mitis) primate species.

1. Abdominal temperatures (Tab) and oxygen consumption (VO2) were measured in two males each of colobus and Sykes monkeys. 2. Tab in both species had the same range (36 38.5 C), but there were marked differences in the daily rhythms. 3. Low ambient temperatures (Ta) had little effect on Tab; at Ta = 33.5 35.5 C. however, Tab rose quickly to above 40 C. 4. The thermoneutral zone (TNZ) extended from about 5 to 28 C in both species. 5. In the colobus monkeys the basal metabolic rate (BMR) was considerably lower than in the Sykes monkeys: 85% vs 113% of the value predicted from body mass.

Function of the lower intestine and osmoregulation in the ostrich: preliminary anatomical and physiological observations.

The gross anatomy of the lower intestine of the African ostrich (Struthio camelus) was investigated in four adult birds shot in the wild. The presence of 80 cm long paired caeca, and approximately 10 m of colon between ileum and the cloaca was confirmed. Urine, but not faeces, was found in the coprodeum. Retrograde flow into the colon was not observed. Samples of contents from the lower intestine were secured from these birds and the water content, osmolality and concentrations in the supernatant of short-chain fatty acids (SCFA), acetate, Na, K and Cl and pH were measured. In the caeca and the orad wide part (2-3 m) of the colon an avid production of SCFA takes place since the concentration of SCFA reached around 200 mM in these segments. As judged from a pronounced fall in the concentrations of Na and SCFA along the length of the colon, these ions are absorbed together with water. The water content falls from 92 to 67% (i.e. from 11.5 to 2.0 ml H2O/g dry matter). The mid-gut fermentation of carbohydrate is in agreement with the observation that the birds were feeding exclusively on Euphorbia heterochroma. This succulent plant (water content 87%) apparently makes the birds independent of surface water. Laboratory studies were performed on two captive male chicks. Hyperosmotic NaCl loading was unable to activate the nasal glands to secretion. Their ducts passed directly from the frontal/lacrimal bone to the nasal cavity. Dehydration confirmed a maximal osmolality of the cloacal urine of around 800 mosmol/l, the osmotic urine to plasma ratio being 2.5. Feeding of either a low- or a high-NaCl diet did not affect the transepithelial electrical potential difference of the coprodeal wall. It remained less than 5 mV, lumen negative.

Defects in resting metabolic rates and mitochondrial respiration in Kwashiorkor and dietary obese rats.

Resting metabolic rates have been measured and compared with hepatic mitochondrial respiration in Kwashiorkor and diet-induced obese weaned rats. In Kwashiorkor, resting metabolic rate was 21% lower than the value of controls, while that of the obese rats was 14% higher than in control animals. The resting metabolic rate for Kwashiorkor animals was 50% of the predicted basal metabolic rate (BMR), whereas that of the obese rats was 23% higher than the predicted BMR. The mitochondrial oxygen consumption patterns, using malate plus glutamate or succinate as respiratory substrates, revealed that the resting respiration (state 4) was 23.9% higher in Kwashiorkor and 29.1% higher in obese animals, while the active (state 3) respiration was 34.8% lower in Kwashiorkor and 43.3% lower in obese rats compared to controls. The respiratory control ratios (RCR) were 51.1% and 43.8% in Kwashiorkor and obese rats, respectively, relative to the values in control rats. It is concluded from these studies that Kwashiorkor disease and diet-induced obesity appear to interfere with oxygen utilization at the level of state 3 mitochondrial respiration, which is markedly decreased when compared to the values for control animals.

Design of the mammalian respiratory system. III Scaling maximum aerobic capacity to body mass: wild and domestic mammals.

The purpose of this study was to determine whether the maximal rate of oxygen consumption (Vo2max) is scaled proportionally to Mb1.0, as the diffusing capacity of the lung, or proportionally to Mb0.75, as the standardized resting rate of oxygen consumption (V02std). We measured Vo2max on a variety of mammalian species (14 wild species and 8 domestic or laboratory species ranging in Mb from 7.2 g to 263 kg) using the same 'treadmill' procedure for all animals. For the wild species we found: Vo2max = 1.94.Mb0.79; r=0.995 where Vo2max has the units ml . sec-1 and mb is in kg. There was a great variability in Vo2max among domestic species of the same size, horse and dog having a Vo2max more than 3 times that of a cow and sheep, respectively. Both the variability in Vo2max with body size and among animals of the same size provide powerful tools for investigating the relationship between structure and function at each step in the respiratory system, from the oxygen in environmental air to the oxygen sink in the mitochondria.