Biomedical subjects
Publications and source records attributed to A A Macdonald.
This year's BVA Congress takes place in Edinburgh, home of the Royal (Dick) School of Veterinary Studies. However, the Scottish capital has been host to more than one veterinary school over the years, as Colin Warwick and Alastair MacDonald explain.
The distribution and relative frequency of endocrine cells in the gastrointestinal tract of the babirusa were studied immunohistochemically using the avidin-biotin-peroxidase complex method. Thirteen types of gut endocrine cells were detected; they were immunoreactive for chromogranin, serotonin, somatostatin, gastrin, bovine pancreatic polypeptide (BPP), glucagon, secretin, cholecystokinin (CCK), methionine-enkephalin-Arg6-Gly7-Leu8 (MENK8), motilin, gastric inhibitory polypeptide (GIP) and peptide tyrosine tyrosine (PYY). Cells that were immunoreactive for chromogranin, serotonin, somatostatin and glucagon were found in all portions of the gastrointestinal tract. MENK8-immunoreactive cells were observed in the stomach and small intestine. Gastrin-immunoreactive cells were detected in the pyloric region and duodenum. PYY-immunoreactive cells were found in the small and large intestine. Cells immunoreactive for motilin, CCK, GIP, and secretin were observed in the proximal small intestine and those immunoreactive for neurotensin were found only in the ileum. Although the distribution pattern of endocrine cells in the gastrointestinal tract of babirusa was similar to those reported for pig, restricted distribution of several endocrine cells, gastrin, BPP, MENK8, motilin, CCK, GIP, secretin and neurotensin and wider distribution of glucagon and PYY were observed in the babirusa. The unexpected presence of MENK8 in all glandular regions of the stomach and PYY in the small intestine was also noted. The distribution of gut endocrine cells might be related to the regulatory characteristics of the babirusa digestive tract.
Stomachs from six adult and one 12-month-old babirusa (Babyrousa babyrussa) were collected from zoological gardens. The babirusa stomach was larger than that of the domestic pig (Sus scrofa), and possessed a large diverticulum ventriculi. Its gastric glands were confined to a small, easily identifiable unit at the end of the corpus ventriculi, and the connections between the different stomach parts were wide and unrestricted, with the exception of the well-defined connection between the diverticulum ventriculi and the fundus ventriculi. Microscopically, the structure of the cardiac, gastric and pyloric glands was similar to that of Sus scrofa. However, the mucusproducing cardiac glands of babirusa occupied a larger area within the stomach (> 70% versus 33%). The pH in the lumen of the cardiac gland area lay between 5.3 and 6.4 and micro-organisms were found here. It was hypothesised that the babirusa is a nonruminant foregut-fermenting frugivore/concentrate selector.
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A description is given of the anatomy of the muscles of the hindlimb of the babirusa (Babyrousa babyrussa L. 1758). Four adult animals, two males and two females were dissected and the results compared with previously published information. Significant differences were found between the accounts and these were analysed within the contexts of material availability and advances in anatomical nomenclature. Comparisons made with published descriptions of the pig (Sus scrofa) showed that the muscular anatomies of the two species are very similar. Those differences which are apparent, despite intraspecies variation in structure, include a thoracic vertebral origin for the M. psoas minor in babirusa but not pig, a smaller gluteal tongue to the M. gluteus medius in the babirusa, a failure of the Mm. gluteus medius to meet on the dorsal midline in the babirusa unlike the case in the pig, the two heads of the M. gluteus accessorius are of unequal size in the babirusa but not in the pig, the vertebral head of the M. obturatorius externus is absent in the babirusa and present in the pig.
The structure of the foramen ovale from 16 species representing 4 carnivore families, the Felidae, Canidae, Ursidae and Hyaenidae, was studied using the scanning electron microscope. The Felidae were represented by 9 domestic cat fetuses (Felis catus), 2 snow leopard neonates (Uncia uncia), an ocelot neonate (Leopardus pardalis), 2 lion neonates (Panthera leo), a panther neonate (Panthera pardus) and 3 tigers (Neofelis tigris), comprising 2 fetuses and a neonate. The Canidae were represented by a golden jackal neonate (Canis aureus), a newborn wolf (Canis lupus), 8 domestic dog fetuses (Canis familiaris), 3 red fox neonates (Vulpes vulpes) and a dhole neonate (Cuon alpinus). The Ursidae were represented by a brown bear neonate (Ursus arctos), a day-old grizzly bear cub (Ursus arctos horribilis), a polar bear neonate (Ursus maritimus), and 2 additional bear fetuses (species unknown). The Hyaenidae were represented by a striped hyaena neonate (Hyaena hyaena). In each species, the foramen ovale, when viewed from the terminal part of the caudal vena cava, had the appearance of a short tunnel. A thin fold of tissue, the developed remains of the embryonic septum primum, extended from the distal end of the caudal vena cava for a variable distance into the lumen of the left atrium and contributed towards the 'tunnel' appearance in all specimens. It constituted a large proportion of the tube, and its distal end was straight-edged. There was fibrous material underlying the endothelium of the flap, the apparent morphology of which suggested that it comprised cardiac muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
The structures of the placenta and the cardiac foramen ovale of the babirusa (Babyrousa babyrussa) were studied by means of light and scanning electron microscopy, with material from eleven fetal and neonatal animals. The babirusa has a diffuse epitheliochorial placenta. The chorion of the term placenta is fusiform in shape, and most of its surface comprises rows of villi interrupted by round, oval or irregularly shaped aerolae. A network of fetal placental capillaries indents the epithelial layer covering the tops and sides of the interareolar villi. The round and oval areolae have slender, irregularly shaped villi. The irregular areolae have undulating surfaces without villi. The umbilical cord contains two arteries, one vein and the urachus. The foramen ovale, when viewed from the terminal part of the caudal vena cava has the appearance of a tunnel; a fold of tissue projects from the caudal edge of the foramen ovale into the lumen of the left atrium. This fold, the distal end of which is straight-edged, constitutes a large proportion of the tube, the remainder being formed by the atrial septum. Comparison of the anatomy of the placenta and heart with those of members of the Suidae and Hippopotamidae indicates that the babirusa has more characters in common with the pigs than with the hippos.
We describe the first reported case in the literature of bacterial endocarditis caused by Enterococcus faecium that was highly resistant to gentamicin. The case is unusual in that it followed a successfully treated Streptococcus sanguis endocarditis. The micro-organism was susceptible only to the glycopeptide antibiotics, vancomycin and teicoplanin and to agents such as pristinamycin and daptomycin which are not routinely available for treatment. It illustrates the therapeutic dilemma posed by serious infections with such micro-organisms and supports previous observations that early heart valve replacement surgery may be necessary to achieve cure of endocarditis due to enterococci which are highly resistant to gentamicin. It further emphasises the importance of screening for high-level aminoglycoside resistance in enterococci in all life threatening enterococcal infections, including endocarditis, septicaemia and meningitis when aminoglycoside-penicillin synergy is required for successful treatment.
Chromosome studies on the Javan warty pig (Sus verrucosus), the Sulawesi warty pig (S. celebensis) and a subspecies of the wild boar, S. scrofa vittatus, have revealed diploid chromosome numbers of 38. The morphology and C-band size of chromosome 10 are different in S. verrucosus and the two other species. Both S. verrucosus and S. celebensis have a Y chromosome that is larger than the Y chromosome of domestic and wild S. scrofa, and is submetacentric rather than metacentric. There are differences between all three species in the G-banding pattern of the long arm of the Y chromosome. The presence of 2n = 38 chromosomes in the Javan warty pig and the Sulawesi warty pig provides new strong evidence that the basic chromosome number in the genus Sus is 38. The differences in karyotype between these pigs (chromosome 10 and the Y chromosome) confirm that they are separate species.
Twenty-six pig fetuses (at 94 days gestational age) were fitted with carotid artery catheters. Eight fetuses were given 1,500 ng of IGF-1 (in 100 microliters) directly into lateral cerebral ventricle; 7 further fetuses received the IGF-1 together with 150 microliters of a potent specific anti-somatostatin serum into a ventricle, 5 other fetuses received the anti-somatostatin serum alone while 6 controls received normal sheep serum. Administration of IGF-1 caused a rapid decrease in circulating growth hormone (pGH) levels but there was no significant change in plasma levels of somatostatin immediately following the IGF-1 administration, suggesting that the decrease in pGH was not mediated by somatostatin secretion. Further evidence that somatostatin was not involved in this effect was provided by the lack of effect of concurrent antisomatostatin serum on the IGF-1-induced decrease in pGH. Thus the high circulating levels of GH in the fetus may result from a lack of feedback of IGF-1, but not through the somatostatin-pituitary axis.
Radioimmunoassayable IGF-I levels were measured in the cerebrospinal fluid and plasma of pig fetuses at 94 days gestational age. Mean plasma IGF-I levels were 128.5 +/- 5.8 micrograms/l while the concentration in the cerebrospinal fluid was 25.8 +/- 4.4 micrograms/l. The effect of intracerebroventricular administration of IGF-I on circulating GH levels was also studied in pig fetuses in utero. Eighteen pig fetuses were fitted with indwelling carotid artery and jugular vein catheters. Nine fetuses were given 1500 ng of pure IGF-I in 100 microliters 0.9% saline by direct injection into a right lateral ventricle. Nine further fetuses (controls) were similarly given 100 microliters of saline without IGF-I. GH levels in the control fetuses were approximately 200 micrograms/l and showed marked fluctuations with episodic intervals of about 40 min. By contrast, in the IGF-I-treated fetuses, GH levels were dramatically lowered by 20 min after IGF administration and remained low throughout the 4-h study. The episodic variations in GH were abolished and levels remained fairly constant at ca. 40 micrograms/l. From these results we surmise that the low levels of IGF-I in the fetus may contribute to their high GH levels. At this stage it is not possible to identify whether the IGF-I inhibition is a direct effect on the pituitary or is mediated by increased somatostatin, decreased GHRH or both.
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The clinical and pathological features of an unusual crippling bone disease in an adult male Pygmy Hog, Sus salvanius, born the smallest in a litter of five and representing the rarest of the known living Suidae, are described. Radiological studies revealed severe spondylosis deformans and focal sharply demarcated radiolucencies in virtually the whole skeleton, but particularly in the bones of the skull, the processes of multiple vertebrae, the ribs, scapulae and parts of the humeri and femora. The clinical chemistry measurements were indicative of pathological lytic processes in the skeleton. The focal bone lesions consisted of caseous necrosis, dystrophic calcification and peripheral fibroblastic demarcation. They contained colonies of filamentous bacteria identified as members of the Order Actinomycetales. Case history evidence suggests that the infection may have resulted from repeated skin trauma inflicted by litter-mates.
1. Blood samples were taken from 30 chronically catheterized pig fetuses in utero. Levels of growth hormone, insulin, cortisol, thyroxine and somatomedin-C/IGF-1 were measured in the plasma of intact fetuses and the plasma of thyroidectomized fetuses at various gestational ages during the latter part of pregnancy. 2. Growth hormone levels were high (mean +/- SEM: 83 +/- 9 ng/ml and remained constant throughout this period. 3. Insulin levels were also constant and ranged between 4 and 14 mU/l. 4. Cortisol levels showed a general increase from 400 nmol/l at 97 days to 1200 nmol/l at term and this increase was not affected by thyroidectomy. 5. IGF-1 levels were lower than in the sows (48.0 +/- 3.0 ng/ml) and did not change throughout this period. 6. Thyroxine levels were also unchanged at about 92 +/- 4 nmol/l. 7. Thyroidectomy resulted in lower (P less than 0.001) thyroxine levels (28 +/- 3 nmol/l) but had no effect on the levels of any other hormone.
The structure of the foramen ovale from six species of Suina was studied using the scanning electron microscope. In each species, the foramen ovale, when viewed from the terminal part of the caudal vena cava had the appearance of a short tunnel. In the domestic pig (Sus scrofa), the wart hog (Phacochoerus aethiopicus) and the bush pig (Potamochoerus porcus) a fold of tissue projected from the caudal edge of the foramen ovale into the lumen of the left atrium. It constituted a large proportion of the tube, and its distal end was generally straight-edged. In some domestic pig hearts small holes were found in the fold, and single threads of tissue arose from its trailing edge. These were not found in specimens from the other pigs or from the collared peccary (Tayassu tajacu), which had a thin unfenestrated tissue fold ending in a straight edge. In both species of hippopotamidae, the hippopotamus (Hippopotamus amphibius) and the pigmy hippopotamus (Choeropsis liberiensis) the fold of tissue was tubular, with strands of tissue extending from the atrial wall to insert on the outer surface of its proximal half. This tube was orientated at an angle of approximately 90 degrees to the caudal vena cava. Its walls were unfenestrated proximally and fenestrated distally, the latter forming a network over the end of the tube. The knotted appearance of the fold after birth suggested that the strands of the network had shortened and coalesced.
The effect of castration and of administration of charcoal-treated porcine follicular fluid (pFF) containing inhibin-like activity on plasma concentration of gonadotropic hormones was studied in neonatal pigs. Plasma follicle-stimulating hormone (FSH) concentration averaged 25.1 +/- 1.5 ng/ml (mean +/- SEM) in 1-wk-old females and gradually declined to 20.2 +/- 0.7 ng/ml 6 wk later. Ovariectomy did not significantly influence plasma FSH concentration. In males, concentration averaged 8.0 +/- 0.7 ng/ml before castration but rose significantly within 2 days after castration. Injection of luteinizing hormone-releasing hormone (LHRH) did not influence plasma FSH concentrations in intact males, but did in females and in 7-wk-old males castrated at 1 wk. Plasma luteinizing hormone (LH) concentrations in 1-wk-old females (2.2 +/- 0.4 ng/ml) gradually declined and were not influenced by castration. Concentrations of plasma LH in 1-wk-old male piglets (2.8 +/- 0.7 ng/ml) were not significantly influenced by castration within 2 days but were significantly higher 6 wk later. LHRH induced a significant rise in plasma LH concentrations in all animals. Injection of pFF resulted in a decline of plasma FSH concentrations in intact and castrated males and in intact females, but did not influence plasma LH concentrations. These data demonstrate a sex-specific difference in the control of plasma FSH, but not in plasma LH concentration in the neonatal pig. Plasma FSH concentrations, but not plasma LH concentrations, are suppressed by testicular hormones in 1-wk-old piglets. Plasma FSH concentrations can be suppressed in both neonatal male and female pigs by injections of pFF.
The circulating levels of growth hormone and thyroxine during the last 2 weeks of gestation, and the effect of thyrotrophin releasing hormone on their secretion, has been examined in 13 chronically catheterised pig foetuses. Porcine growth hormone, measured by homologous radioimmunoassay, in the foetal plasma was found to average 83.5 +/- 10.3 ng/ml, while thyroxine levels were 92.9 +/- 4.1 nmol/l. There was no change in thyroxine or growth hormone levels with gestational age. Injection of 5 micrograms TRH produced a marked increase in plasma growth hormone levels (+194 +/- 51 ng/ml) but no change in thyroxine was observed. Injection of saline and subsequent blood sampling had no effect on the levels of either growth hormone or thyroxine.