Biomedical subjects
Publications and source records attributed to N G Wright.
This paper describes a novel, composite device, based not on optical excitation but on the transfer of holes from Si to the TiO(2)/air or TiO(2)/water interface, for the disinfection and detoxification of fluid streams.
A novel approach to the detection and modelling of preferred orientation is presented, based on the interpretation of two-dimensional powder patterns. A simple graphical construction is introduced to aid interpretation, and the application of this construction to some standard diffraction geometries is discussed. It is also shown in outline how a standard preferred-orientation model can be adapted to describe two-dimensional data.
A natural outbreak of strangles occurred in a group of 19 young experimental ponies. The disease was diagnosed in 11 of them within two days of their arrival at Glasgow University veterinary school and five others developed clinical signs within a further four days, a morbidity rate of 84 per cent. All of the affected ponies had typical signs of strangles including dullness, anorexia, pyrexia, regional lymphadenitis, occasionally with rupture of the lymph node, conjunctivitis and a mucopurulent nasal discharge. Nine of the affected ponies were destroyed during the clinical phase of the disease for post mortem studies. The clinical disease in the remaining animals lasted approximately 21 days although one pony had to be destroyed 10 days after the onset of clinical signs because of the development of septic arthritis. All 16 affected animals exhibited peripheral blood neutrophilia and high plasma fibrinogen levels. beta haemolytic streptococci were isolated by nasopharyngeal swabbing from 18 of the 19 ponies. Streptococcus equi was confirmed only in three animals within the first four days of the outbreak. The majority of the other isolates identified to species were S zooepidemicus. beta haemolytic streptococci were still present in six ponies 40 days after they had clinically recovered and were isolated regularly from three ponies which did not develop clinical strangles but remained in contract with affected animals throughout the study.
The ultrasonographic and histopathological findings in 12 normal and 28 injured superficial digital flexor tendons, with lesions ranging in duration from 2 days to 15 months, were compared. A consistent relationship between the ultrasonographic and histological findings was demonstrated. The echogenicity of lesions, the distinctness of their delineation from the surrounding tissue, and the presence and arrangement of the linear echoes were useful features by which to assess the ultrasonograms. Acute lesions were anechoic, a complex mixture of anechoic and hypoechoic areas, or diffusely hypoechoic. These appearances represented haemorrhage, fibrolysis and early granulation tissue. Fibroplasia and granulation tissue produced well to moderately well defined hypoechoic lesions. Chronic fibrosis was characterised by heterogeneously echogenic areas which were poorly defined from the surrounding tissue and had irregularly-arranged linear echoes on longitudinal images. Intratendinous scar formation resulted in multiple hyperechoic foci. Extensive peritendinous lesions were readily apparent on ultrasonograms, but intertendinous adhesions were more difficult to assess, and produced ill-definition of the borders between the superficial and deep digital flexor tendons.
When beagle dogs were infected with Trypanosoma brucei, a marked reduction in the plasma concentration of atrial natriuretic factor (ANF) occurred in the terminal stage of the disease during weeks 3 and 4. At the same time there was an increase in plasma renin activity (PRA) after infection. Ultrastructural studies of the atria of these dogs demonstrated a reduction in ANF granules. The changes in ANF and PRA occurred in association with severe pancarditis and the development of heart failure. By impairing the ability of the heart and kidneys to regulate blood volume, the alterations in ANF and PRA could be involved in the pathogenesis of heart failure in T. brucei-infected dogs.
The surface features of the upper respiratory tract of 20 clinically normal horses of various ages and types were studied with scanning electron microscopy. In the rostral part of the nasal cavity, there was a wide zone of non-ciliated epithelium whereas, caudally, the surface was well ciliated. This latter type of epithelium extended into the nasopharynx and guttural pouches although scattered areas of non-ciliated microvillous cells were also found.
The surface features of the lower respiratory tract of 20 clinically normal horses of different ages and types were studied with scanning electron microscopy. Parallel light microscopical and transmission electron microscopical studies were also carried out. The ciliary carpet was virtually complete from the trachea to the lobar bronchi. In small bronchi, ciliation was less complete allowing numerous non-ciliated mucous cells to become obvious. The terminal bronchioles, populated mainly by non-ciliated bronchiolar epithelial cells, had an abrupt junction with alveolar ducts. Interalveolar pores were common particularly in older horses.
Membranous nephropathy was induced in four cats by repeated intravenous injections of 120 mg cationic bovine serum albumin (BSA, pI 9.5). All four cats developed diffuse granular deposits of IgG and C3 along the glomerular capillary walls as early as five weeks which persisted until the end of the experiment at 17 weeks. Ultrastructural studies revealed many subepithelial electron dense deposits. Two cats developed severe proteinuria and the nephrotic syndrome characterised by hypoalbuminaemia and oedema. An additional four cats received repeated injections of unmodified native BSA (pI 4.5) and remained basically normal. This is the first report of membranous nephropathy and the nephrotic syndrome in an experimental animal model which, unlike other animal models, is subject to the spontaneously occurring disease.
Three healthy cats were subjected to percutaneous renal biopsy of the left kidney on three occasions at monthly intervals. Three other cats were subjected to three consecutive biopsy attempts on one occasion using the left kidney. Thereafter the six cats were monitored clinically and by means of laboratory analyses of blood and urine until euthanasia four weeks after the last biopsy. Cautious insertion of the biopsy needle in an attempt to avoid over penetration of the kidney resulted in failure to obtain renal tissue on six occasions but in all 12 specimens which did contain renal tissue, glomeruli were present. Major blood vessels were present in two biopsy specimens. At necropsy, radiographic and histological studies demonstrated renal parenchymal and vascular changes in the biopsied kidneys which were similar to but less severe than those produced by a single biopsy attempt. This confirmed that avoidance of damage to major renal vessels is important and suggested that, with care, repeated biopsies need be no more harmful to the kidney than a single biopsy.
Eight 16-week-old dogs were used to induce immune complex glomerulonephritis by daily intravenous injections of 120 mg highly cationized bovine serum albumin (pI9.5). Of four control dogs, two received unmodified native anionic bovine serum albumin (pI 4.5) while the other two received only phosphate buffered saline. The renal glomeruli were examined by light, electron (transmission and scanning) and immunofluorescence microscopy at intervals from five to 11 weeks after the start of the injections. Animals receiving cationic antigen all developed generalised diffuse granular deposits of IgG and C3 along the capillary walls; these were detected as early as five weeks and continued until the termination of the experiment at 11 weeks. Ultrastructural studies revealed many electron dense deposits along the subepithelial regions of the glomerular basement membrane. The experimental disease resembled in many respects naturally occurring membranous nephropathy, the most common form of immune complex glomerulonephritis in dogs.
The surface characteristics of the lower respiratory tract of two groups of cattle were studied with the scanning electron microscope. Group A comprised six one-week-old calves and group B four adult cows. None of the animals had overt respiratory disease or gross morphological evidence of pulmonary lesions. The trachea, bronchi, bronchioles and alveoli of the cranial and the caudal lobes of the right lung were examined. In both groups the luminal surface of the trachea and large bronchi were completely covered by cilia, apparently forming an efficient mucociliary escalator. In the adult animals there were some patchy areas in the trachea and large bronchi devoid of ciliated cells; these were considered abnormal. In the bronchi, non-ciliated cells, mainly mucus-secreting, were not easily identified unless they were discharging secretion. In small bronchi, non-ciliated cells were more evident and easily seen. The bronchioles had many non-ciliated cells and very few ciliated cells capable of forming a complete carpet for a mucociliary escalator. Types 1 and 2 alveolar epithelial cells and alveolar macrophages were identified in both groups. Pores of Kohn were found in the alveolar walls in all animals.
Eighteen dogs were given repeated doses (between 4 and 19) of ampicillin (7 mg per kg intramuscularly on 3 days a week). Fifteen of the dogs developed a subclinical glomerulonephropathy characterized by mesangial hypercellularity. While only 9 of the 18 dogs showed electron-dense deposits in the mesangium, 14 dogs had glomerular deposits of IgG and 11 of these had C3 deposits also.
Nine puppies without maternal antibody to canine adenovirus (CAV) were divided into two groups. The first consisted of six puppies, each of which was given two doses of a commercial inactivated CAV-1 vaccine, 14 days apart. Eight days after administration of the second dose of vaccine, all six puppies, together with the second group, consisting of three unvaccinated controls, were challenged with an aerosol of virulent CAV-2. One dog from each group was killed on the third, fifth and 10th days after challenge and the three additional vaccinates killed at intervening times. All of the dogs developed respiratory signs, mainly coughing and tachypnoea, but the vaccinated dogs made a more rapid recovery. The lungs of both groups were consolidated, the areas affected being more extensive in the controls, and histological examination revealed the main lesion to be a severe necrotising bronchiolitis. Virus was isolated from the respiratory tissues and from throat swabs collected from both groups of dogs. The presence of neutralising antibody in the serum was not, of itself, sufficient to control viral replication and oblate the disease.
Membranous nephropathy was diagnosed in two sibling cats from the same household. Both cases presented with the nephrotic syndrome but 33 months elapsed before the second cat became ill, by which time the first cat had been in full clinical remission for over a year.
Eighteen 16-week-old dogs were inoculated i.v. with a virulent strain of canine adenovirus and the renal glomeruli were examined by light, electron (transmission and scanning) and immunofluorescence microscopy at intervals from 24 h to 7 days after inoculation of virus. From 2 days onwards intranuclear inclusion bodies and cell-associated viral antigen were detected in mesangial, endothelial and circulating mononuclear cells. This was accompanied by swelling and, in some cases, necrosis of these cells with partial or complete occlusion of capillary loops. In 5 dogs examined on days 5-7 after inoculation of virus, granular deposition of IgG, C3 and viral antigen was observed in mesangial areas and electron dense deposits were found in the mesangial matrix.
A scanning electron microscopic study of the distribution of ciliated cells in the tracheobronchial tree of 25 dogs whose ages ranged from four hours to six months was carried out. In newborn puppies, only the dorsal wall of the trachea was completely ciliated while the lateral and ventral walls showed patchy ciliation. This pattern of cilia formation persisted until five days of age when the whole tracheal wall was found to be completely ciliated. The bronchus of newborn puppies was uniformly poorly ciliated but almost complete ciliation was achieved by two days. Likewise, large and small bronchioles of newborn animals had few cilia and, although the number of ciliated cells had increased by two days, complete ciliation was never observed regardless of the age of the dog. No ciliated cells were found in the respiratory bronchioles of any of the 25 dogs.
Eleven healthy cats were subjected to a single, percutaneous renal biopsy with a disposable biopsy needle and thereafter monitored clinically and by means of laboratory analyses of blood and urine until euthanasia at intervals up to two months after biopsy. Biopsy specimens were obtained at each attempt and the specimen length and numbers of glomeruli compared favourably with results from normal dogs biopsied with Franklin-Silverman needles. At necropsy radiographic studies demonstrated renal vascular changes and histological examinations of the biopsied kidneys revealed lesions varying from barely discernible linear scars to extensive haemorrhage and wedge-shaped infarcts. A direct relationship was established between the severe renal lesions in seven cats and biopsy specimens containing medullary tissue and major renal blood vessels.
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