Composition and viscosity of interstitial fluid of rabbits.

Open-ended plastic tubes were used as capsules for obtaining interstitial fluid from rabbits. The capsule was a 2.5 cm long plastic tube with an inner diameter of 6 mm. Three small incisions were made in the dorsal mid-line of the anaesthetized rabbit; two capsules were inserted into each incision. A sample of capsular fluid was obtained 6 weeks later by inserting a hypodermic needle through the skin. The volume of fluid obtained from the capsule was sufficient for the analysis of total protein, albumin, albumin:globulin ratio, colloid osmotic pressure and the fluid viscosity. Despite the significantly lower total protein, albumin, globulin and colloid pressure of intracapsular fluid compared with plasma, the intracapsular fluid was found to have a greater viscosity. It is our opinion that the increased viscosity of the intracapsular fluid is due to the presence of a high molecular weight substance other than albumin and globulin, possibly hyaluronan.

Factors which affect blood variables of slaughtered cattle.

Blood was obtained at an abattoir from 4 groups of cattle. The first group was slaughtered in a conventional way, the second and third were subjected to shechita slaughter with or without the application of the captive bolt immediately after the cutting of the throat, and the fourth group of cattle was subjected to a period of recumbency prior to conventional slaughter. Blood samples were analysed for concentrations of catecholamines, cortisol, glucose, lactate and total lipids. The haematocrit and osmolarity was also determined. There were no major differences in the blood variables of cattle subjected to conventional slaughter and those of cattle which had been subjected to a period of recumbency prior to conventional slaughter. Plasma catecholamine concentrations in cattle subjected to shechita slaughter without the application of a stun, were significantly elevated when compared to any of the other groups. It was concluded that postural changes have very little effect on the blood variables, but that the application of a stun after the throat has been cut in shechita slaughter abolishes the increases in blood variables associated with shechita in the absence of stunning.

Effect of a 72 hour fast on physiological stress indicators in feedlot cattle.

Feedlot oxen (n = 15) were herded and subjected to venepuncture on a daily basis for 2 weeks. Plasma glucose, lactate, free fatty acids, total lipids, total protein, cortisol, catecholamines, osmolarity and haematocrit were compared between Days 1 and 14. Plasma glucose concentration and haematocrit decreased significantly while total plasma lipid and free fatty acid concentrations increased significantly over the 14 d. Thereafter, food was withdrawn for 72 h from the experimental group (n = 10) and the same blood variables were compared in the control and the experimental groups. Plasma free fatty acid concentrations rose, while glucose concentrations declined in the experimental group during the fasting period. It is concluded that food deprivation for 72 h in cattle cannot be regarded as a major stressor.

Year performance and final achievement in a physiology course.

The relationship between year performance and final achievement is examined for a second-year physiology course. A positive and significant correlation exists between the year mark and the examination mark with the predictive value of the year mark ranging from 44 to 85 per cent. Virtually all students with a year mark above 55 per cent pass the year. It is suggested that, in the case of failure, only students with a passing year mark should be allowed a supplementary examination and/or that the year mark should still count. In addition, it is clear that a strong case exists for using the year mark as the sole measure of pass or failure.

Heritable testicular hypoplasia in Nguni (Bos indicus) bulls: vascular characteristics and testosterone production.

The biased unilateral occurrence of heritable gonadal hypoplasia was investigated by examining the gross- and microanatomy of the testicular artery and vein, testicular blood flow and testicular testosterone secretion in normal Nguni bulls and in Nguni bulls showing unilateral left, unilateral right and bilateral hypoplasia of the testis. A high incidence of branching of the testicular artery was found ipsilateral to hypoplastic testes. The branching occurs a short distance from the dorsal aorta: one branch proceeds to the testis, the other to the ipsilateral kidney. The association between arterial branching to the kidney and ipsilateral hypoplasia of the testis held for both unilaterally left and unilaterally right hypoplastic bulls. Variations in the anatomy of the testicular vein occurred in both normal and hypoplastic bulls but there was no specific association between the variations and ipsilateral hypoplasia. The lumen diameter of the testicular artery or branch correlated with testis mass. Wall thickness of the artery ipsilateral to hypoplastic testes was not different from that in normal bulls, discounting hyperplasia of the endothelium. Total blood flow to the testis correlated with testis mass. The secretion rate of testosterone from hypoplastic testes was lower than that of normal testes but there was no difference when compared on a unit mass basis.

Effect of surgical restriction of growth of the testicular artery on testis size and histology in bulls.

The growth of the testicular artery was restricted on one side in young bulls and subsequent testicular development was monitored. After the animals had been killed, the testes were studied histologically and compared with testes from hypoplastic bulls. The growth rate of testes from the experimental side was significantly lower than that of testes from the sham-operated side over a period of 578 days. At death, the experimental testes had a mean (+/- SD) mass of 76 (+/- 41) g compared with 220 (+/- 31) g for the control testes. The sham-operated testes accounted for 0.071 (+/- 0.008)% of live body mass compared with 0.025 (+/- 0.014)% for the experimental testes. The seminiferous tubules in the sham-operated testes had a mean diameter (+/- SD) of 211 (+/- 25) microns, whereas those of the artery-restricted testes and hypoplastic testes were significantly smaller (152 (+/- 37) and 145 (+/- 45) microns, respectively). In the artery-restricted and hypoplastic testes, the interstitial tissue accounted for a significantly greater proportion of the testicular tissue than in the sham-operated testes and spermatogenesis was either totally absent or present in only a small proportion of tubules. It is suggested that the artery-restricted testes could be used as a model for testicular hypoplasia.

Necropsies of eight horses infected with Strongylus equinus and Strongylus edentatus.

Ponies (n = 8) approximately 18 months old, were infected with 20,000 to 30,000 infective larvae of Strongylus equinus with less than 10% contamination with Strongylus edentatus larvae and necropsied 7 months post-infection. Lesions were present in the omentum, liver, pancreas, ventral colon, caecum and occasionally in the lungs. There were numerous intraabdominal adhesions and severe multiple granulomatous omentitis. Pancreatic damage, which characterises S. equinus, was exceptionally mild and was manifested mainly by slight periductular infiltration of eosinophils. Granulomas associated with larvae were found in the connective tissue associated with the pancreas. Larvae were recovered from the flanks, the peritoneum, the caecum and the kidney. Larval recovery was low, with a high percentage of the total number of larvae recovered in some of the carcasses being S. edentatus.

Comparative physiological responses to stressors in animals.

1. The species-specific experimental response to stressors (SSERTS) analysis has been applied to a number of species under varied short and long term conditions. 2. The measure provides quantitative data relating to the physiological responses of animals when exposed to stressors and results are presented comparing these for different methods of immobilization, euthanasia, etc. at intra- and inter-species level. 3. It is suggested that the SSERTS measure is of greater value for measuring the responses of animals to stressors than is the measurement of the concentration of single blood variables.

The measurement of psychophysiological reactions of pilots to a stressor in a flight simulator.

Seventeen Boeing 737 pilots were exposed to an acute stressor in a flight simulator: a birdstrike between V1 (velocity of aircraft on take-off run at which crew is committed to take-off regardless of any incidents occurring) and VR (velocity of aircraft at take-off). Certain physiological variables together with state anxiety scores were measured at different stages of the simulated flight. Levels of plasma cortisol, norepinephrine, total protein, total lipid, lactate, and the haematocrit changed significantly across the test conditions. Plasma epinephrine, osmolality and glucose levels did not change significantly across the test conditions. Captains and copilots differed significantly in the profiles obtained for the state anxiety scores. The variables measured in this study demonstrated different profiles in response to the stressor. Conceptual and methodological problems need to be solved before an integrated psychophysiological approach to the reactions of pilots to stressors can be developed.

The response of animals to suxamethonium (succinyldicholine) and succinylmonocholine.

The time which elapses before cessation of breathing, and blood pressure and blood gas changes after the intramuscular administration of suxamethonium, or a mixture of suxamethonium and hexamethonium, is compared in immobilised African elephants (Loxodonta africana) and buffaloes (Syncerus caffer). In addition, the respiratory responses of elephants and other animals to intravenous administration of suxamethonium and succinylmonocholine are reported on, as are the effects of darting animals with succinylmonocholine. The results show that respiration is affected in a similar fashion in all species investigated. However, the characteristic gradual decrease in respiratory rate seen in elephants during culling, using suxamethonium, resembles the effects observed when succinylmonocholine is administered. It is suggested that elephants are killed by this first breakdown product of suxamethonium during culling and/or that unique acetylcholine receptors may be involved.

Evaluation of a simple plasma catecholamine extraction procedure prior to high-performance liquid chromatography and electrochemical detection.

The modified extraction method for catecholamines described in this study is reproducible, simple, rapid, economical and relatively hazard-free. This method is based on the principle that plasma catecholamines are selectively adsorbed on acid-washed alumina at pH 8.6 and then eluted at a pH between 1.0 and 2.0. No statistically significant differences were obtained by using either 0.5 or 1.0 ml of plasma with 0.5 or 1.0 ml of Tris buffer. A 15-min mixing time during the adsorption and desorption steps was found to be practical, but any standardized time up to 1 h can be used. If the washing step was omitted, the catecholamines could not be eluted from the acid-washed alumina. To prevent dilution, the alumina had to be centrifuged and not aspirated to dryness after the washing step. An amount of 50 mg of WA-4 alumina was found to be the most practical in this study. Extracted or unextracted plasma as well as catecholamine standards were stable for four months at -20 degrees C.

Comparative effects of adrenaline and noradrenaline on the synthesis and secretion of soluble protein by isolated hepatocytes.

1. Adrenaline (A) supplementation of the incubation medium of monolayer cultures of hepatocytes at 0.1, 0.2, 0.3, 1 and 10 ng/ml resulted in consistently enhanced levels of secreted and newly synthesised non-secreted proteins; supplementation with 100 and 1000 ng/ml resulted in lower or unchanged levels. These effects were most consistent 6 hr after a medium change. 2. Noradrenaline supplementation of the medium resulted in increased levels of secreted and non-secreted proteins at low concentrations (less than 2.4 ng/ml) at 6 hr after a medium change, but significantly decreased levels of both populations at high concentrations of noradrenaline (NA) (2.4 less than NA less than 1000 ng/ml), at 6-9 hr after a medium change and sustained to 24 hr, the most significant decrease being at 10 ng/ml. 3. All combinations of concentrations of A + NA resulted in non-dose-dependent decreased levels of both the secreted and non-secreted soluble protein fractions. The most significant decreases occurred at concentrations of (1 + 5) and (10 + 10) ng/ml adrenaline + noradrenaline. 4. Medium supplementation with adrenaline, noradrenaline or a combination of the two had no effect on the uptake of [3H]leucine by the cells. 5. The results are discussed in relation to receptor status on the hepatocyte membranes.

Blood constituent responses of animals culled with succinyldicholine and hexamethonium.

Blood constituent responses of elephants and buffaloes culled in the Kruger National Park, using a mixture of succinyldicholine and hexamethonium, were compared to those of animals culled with succinyldicholine only. The results show a decreased physiological response in the animals culled with the mixture, characterised by lower total catecholamine, cortisol and glucose concentrations. Neither a delay of up to 30 min in obtaining blood samples from culled animals, nor a delay of up to 30 min in processing samples obtained immediately after cessation of respiration, gave any significant difference in the blood constituents which were measured.

Blood constituent responses of cattle to herding.

Blood was obtained over a period of 20 minutes by remote controlled procedures from cattle while they were herded. Samples were analysed for catecholamines, cortisol, haematocrit, total lipid, glucose and lactate. The results show that the response to a given stressor is specific and suggest that multiple stressors may not necessarily result in additive effects.

Immediate response to repeated capture and handling of wild impala.

The composition of blood from veld and boma (enclosure)-kept impala, obtained immediately after the animals were manually restrained, was compared to control values. Statistically significant differences existed between the values for hematocrit, lactate, glucose, and osmolarity of veld and boma-kept animals compared to control data. Cortisol values were significantly greater (P less than .05) in boma-kept animals (93 +/- 21 nmol/liter) but not in veld impala (11 +/- 3 nmol/liter). It is suggested that the high cortisol and other values measured in boma-kept impala were due to an anticipatory conditioned response in these animals which occurred prior to them actually being caught. Repeated capture and handling, over a period of several months, of boma-kept impala resulted in statistically insignificant decreases in the mean values of several variables. Although this is indicative of adaptation it is doubtful whether the animals would ever fully adapt to the procedures involved.

Stress in cattle assessed after handling, after transport and after slaughter.

Blood samples were collected from unstressed cattle and from cattle undergoing handling stress, transport stress and slaughter. The blood was analysed for ACTH, cortisol, thyroxine stimulating hormone, tri-iodothyronine (T3) and catecholamine concentrations, and for haematocrit, total plasma protein, plasma lipid, lactate and glucose concentrations. Compared to control values handling significantly increased T3, cortisol, lipid and lactate concentrations. Compared to handling, transport stress was associated with increased catecholamines and lactate concentrations, a decreased cortisol concentration and similar concentrations of T3, lipid and glucose. Compared to transport, slaughter resulted in high catecholamines, lactate and glucose, and low T3, cortisol and lipid levels. It is concluded that the response to stress has two phases, a hypothalamic-adrenal cortex phase which is associated with perceived environmental stress such as noise, and a sympathetic-adrenal-medulla phase which is associated with neurogenic stress such as transport or specifically the massive sympathetic discharge caused by stunning. Combinations of stresses produce a mixed response.

Effects of chemical immobilisation on the blood composition of impala (Aepyceros melampus (Lichtenstein).

The effects of chemical immobilisation on impala (Aepyceros melampus) were investigated. The results indicate that etorphine HCl or Carfentanil should not be used in isolation but that xylazine should be included in the immobilisation "cocktail". The highest dose possible, commensurate with safety, should be used in order to minimise time and distance to recumbency. Body temperature should be monitored and if cooling measures are not effective the animal should be aroused. Either diprenorphine HCl alone or in combination with yohimbine and 4-aminopyridine should be used as antidote/s.