Measurement of regional lung function by tetrapolar electrical impedance plethysmography.

This study demonstrates the clinical feasibility of atraumatically measuring dynamic regional lung function with tetrapolar electrical impedance plethysmography (EIP) in the pediatric age group. A tetrapolar electrode system was used because of its ability to detect local baseline and pulsatile impedance changes, minimal electrode-tissue impedance interference, and uniform current distribution. Studies performed on 4 children 4 to 15 years old with various pulmonary diseases are presented. The information obtained on their regional ventilation and pulsatile perfusion by EIP was found to agree closely with pulmonary ventilation and perfusion scans. In one case, EIP detected pulsatile perfusion abnormalities which were not apparent in the non-pulsatile perfusion scan but were demonstrated by cineangiography. It is concluded that tetrapolar EIP can provide safe, reliable regional information about ventilation and perfusion in diseased lungs, and because of its atraumatic approach, is technically most suitable for use in children.

A longitudinal study of the cultivable subgingival anaerobic bacteria isolated from sheep during the development of broken mouth periodontitis.

In a longitudinal bacteriological study of the cultivable subgingival anaerobic flora isolated from developing broken mouth periodontitis in sheep, samples were taken from five sheep on each of three farms on seven occasions over a period of 2.5 years. Ten different bacterial genera were isolated regularly but with fluctuating frequencies. Bacteroides and Fusobacterium organisms accounted for nearly 70% of the isolates. The Bacteroides and Fusobacterium isolates studied in detail from one farm were identified to species level. The fusobacteria comprised F. nucleatum-like organisms (68.6%). F. necrophorum (29.6%) and F. naviforme (1.8%). The Bacteroides spp. were divided into 11 main groups and included black-pigmented species similar to B. asaccharolyticus and B. gingivalis. On the farm studied in detail, the sheep could be allocated to two groups according to progression of periodontal disease. Most of the B. gingivalis-like isolates were from sheep with actively progressing disease, indicating that this organism may play a role in periodontal destruction in sheep.

Preliminary study of the anaerobic bacteria isolated from subgingival plaque from sheep.

A preliminary study was made to determine the genera of cultivable anaerobic bacteria which could be isolated from subgingival plaque of sheep. Samples were taken from 10 sheep on farms with a known record of broken mouth periodontitis. For assessment of the sampling technique, samples were also taken from freshly exposed tooth roots in killed sheep. The bacteria isolated on several selective and non-selective media were identified to genus level by a combination of Gram reaction, colony morphology and gas chromatographic analysis of volatile and non-volatile fatty acid metabolic end products. At least 10 different genera were isolated and these findings are discussed in relation to the bacteriology of human periodontitis and recent studies of sheep broken mouth periodontitis.

Effect of periodontal disease ("broken mouth") on the distribution of matrix macromolecules in the sheep periodontium.

A topographical, biochemical analysis of the soft connective tissues of sheep periodontia diagnosed clinically as showing periodontitis was carried out and compared with healthy periodontal tissue. Protein content was mapped on a site-to-site basis and compared with the distribution of collagen for both healthy and diseased tissue using amino acid analysis. Diseased tissue was more biochemically homogeneous than corresponding healthy tissue. Protein content per cent was in general greater but collagen content was greatly reduced. Tissue adjacent to radicular cementum appeared to be most markedly affected by the disease process. The apparent selective loss of non-proteinaceous components along with loss of collagen attachment may explain the direction in which periodontal disease is propagated through the tissue.

The effect of periodontal disease on sulphated glycosylaminoglycan distribution in the sheep periodontium.

The glycosylaminoglycan (GAG) distribution in the soft periodontal tissues of the sheep was investigated topographically in healthy tissue and the changes associated with periodontal disease determined and correlated with increasing disease severity. Total sulphated GAG content was determined spectrophotometrically and the proportions of individual GAGS measured after separation by cellulose acetate electrophoresis. In healthy tissue, total sulphated GAG distribution was found to mirror that described previously for collagen, being highest in the gum-pad region and adjacent to alveolar bone. This changed markedly in relation to periodontal disease. Early disease-related changes in GAGs were first detected adjacent to alveolar bone. In severely diseases tissue, an overall increase in sulphated GAG, particularly in the gum-pad region, was present. Increasing disease severity was accompanied by a decrease in dermatan sulphate and a concomitant increase in the proportion of chondroitin-4-sulphate. These changes may be due to the combined effects of chronic inflammation and alterations to the mechanical loading of the tissue owing to loss of attachment.

Dental disease in hill sheep: an abattoir survey.

Heads from 478 aged sheep of a predominantly hill breed population were examined in detail for evidence of dental disease, using both soft and hard tissue measurements around incisor and cheek teeth. Almost 60 per cent of this population (all over 2 1/2 years of age and with a mean age between 7 and 8 years) had either loose or missing teeth. Malalignment of cheek teeth and/or incisors was also common. Pocketing was seen in 87 per cent of the population, and was significantly correlated with tooth looseness. There was also a significant relationship between incisor and specific cheek tooth pocket depths. Whilst local alveolar bone loss was found, it was not a reflection of more general skeletal deterioration. The survey confirms the high incidence of broken mouth in the national flock and shows that wherever incisor problems occur there is a likelihood that cheek tooth disease is also present, a relationship not readily appreciated clinically.

Skeletal and blood biochemical characteristics of sheep during growth and breeding: a comparison of flocks with and without broken mouth.

Two-hundred female Scottish Blackface sheep ranging in age from 3 months to 5 1/2 years were used to investigate the relationships between blood biochemical characteristics, skeletal metabolism and dental health on 5 farms, 3 with broken mouth and 2 with no incidence of the disease. Skeletal growth to 6 months of age was faster in lambs from control flocks than in lambs from affected farms although growth thereafter was slower in the control group. A generally lower protein intake on control farms may account for this reduced growth rate. In general, adult dimensions of bones were attained between 14 and 30 months of age but age of maturation varied between bones; tibial endochondral growth ended after 14 to 21 months while the rib still showed evidence of endochondral growth at 70 months of age. This growth was episodic, being maximal during lactation and possible causes are discussed. There was no significant differences in calcium or phosphorus status between control and affected populations, an inadequate phosphorus intake during pregnancy was common to both groups. Lower serum magnesium concentration in affected than in control sheep was a consistent finding and is discussed.

Functional morphology of the periodontal ligament in the incisor region of the sheep.

The morphology of the periodontal ligament round the sheep incisor tooth is described. Thick, undecalcified sections (100 mum) allow separation of the collagenous fibres into distinct fibre groups and these are compared to similar groups found in other animals. The relationship between the forces applied to the teeth and the distribution of the fibre groups is discussed and it is concluded that there is a functional relationship between the two.

Development of periodontal disease in a single flock of sheep: clinical signs, morphology of subgingival plaque and influence of antimicrobial agents.

The clinical development of broken mouth over a single reproductive year and the effect of two broad spectrum antibacterial agents upon it was followed in 72 Scottish Blackface ewes aged between two and three years. Using a number of dental health indices especially developed for the purpose, the amount of gingivitis, tooth movement, gum recession and pocketing were quantified and graphed for both the whole population and each group in the drug trial. All clinical features except movement fluctuated significantly with time, the fluctuations often being associated with nutritional or other environmental factors. Despite the extended use of large doses of two antimicrobial agents no significant reduction in the amount of clinical gingivitis or pocketing was evident.

Effects in sheep of high dietary levels of vitamin D3 as measured by circulating concentrations of some vitamin D metabolites and skeletal examination.

Housed non-pregnant ewes were given diets supplemented with five, 10, 20, 40 and 80 times the Agricultural Research Council's recommended requirement for vitamin D for 16 weeks. The effects on vitamin D status were assessed by measuring 25-hydroxylated vitamin D metabolites (25-OHD) in plasma at intervals. After 16 weeks, animals on the lowest and two highest vitamin D intakes were killed for histological examination of selected soft tissues and bones. Circulating concentrations of 25-OHD increased with intake and time during the experiment. However the increases were not proportional to intake and only when intakes exceeded 20 times the recommended requirement were concentrations greater than those seen in summer in grazing sheep. There was some evidence for the production of an additional vitamin D metabolite in animals on high vitamin D intakes. No abnormalities were detected in any of the tissues examined histologically.

A laboratory method for studying tooth mobility of the mandibular central incisor of the sheep.

Linguolabially directed loads of 0.01 to 1.0 N were applied to a mandibular central incisor in each of 12 four-year-old ewes with healthy mouths. For each incisor, tooth position was monitored continuously with an ultrasonic displacement transducer. On suddenly applying a load and maintaining it for five minutes, a biphasic pattern of displacement was recorded, a phase of rapid displacement being followed by a more gradual one. A similar biphasic recovery response was seen on suddenly removing the load. These patterns are viscoelastic-like. The group mean displacements showed that for all phases the responses were force-dependent, though not linearly graded. For a given load, the group mean displacements were considerably larger than those reported previously for the teeth of other animals, supporting the impression that the sheep incisor is extremely mobile. These data will provide a baseline for studies on the mobility of the teeth of sheep with inflammatory periodontal disease ('broken mouth').

High incidence of abortions and congenital deformities of unknown aetiology in a beef herd.

In 1980, 16 abortions or stillbirths occurred and 26 deformed calves were born in a beef herd of 115 Friesian cross Hereford cows mated to Charolais bulls. The deformities were principally arthrogryposes with contractures, particularly of the forelimbs, and various skull abnormalities. Following investigation it was considered highly unlikely that hereditary causes, infectious agents or a nutritional deficiency were responsible. The most likely cause was exposure to an unidentified teratogen early in pregnancy.

Rickets associated with vitamin D deficiency in young sheep.

An outbreak of rickets in sheep under a year old (hoggs) appeared clinically as stiffness and rotation of the carpal joints. Histological studies confirmed the diagnosis and biochemical analyses of blood demonstrated a primary vitamin D deficiency.

Sulphur-induced polioencephalomalacia in lambs.

An outbreak of polioencephalomalacia affected 16 of 46 Swaledale lambs and five of 25 Scottish blackface lambs 15 to 32 days after they were introduced to an ad libitum concentrate ration containing 0.43 per cent sulphur. The clinical signs were acute and included depression central blindness and head-pressing, but no hyperaesthesia, nystagmus, dorsiflexion of the neck or opisthotonos were observed. Treatment of the affected lambs with vitamin B1, dexamethasone and antibiotics was associated with a prolonged recovery period, though no further cases were identified after vitamin B1 had been given parenterally to all the lambs at risk.

Pneumonia in sheep associated with dipping in carbolic dips.

Fourteen outbreaks of pneumonia in sheep following dipping in carbolic dips were investigated at seven laboratories. Deaths commonly occurred between one and three days after dipping and fat young sheep of the Suffolk and Border Leicester breeds were most usually involved in outbreaks. The pneumonia was characterised by hyperaemic, oedematous and cyanotic lungs, and the main histological features were hyperaemia, fluid and cellular exudation into alveolar spaces, and widespread epithelialisation of alveolar walls. The microscopic changes differed from pneumonic pasteurellosis and no significant organisms were recovered from any of the lungs. One of 27 Dorset Horn lambs dipped in a batch of dip which had been incriminated in some episodes developed an epithelialising interstitial pneumonia, while two out of three Suffolk lambs dipped in twice the recommended strength of the same batch of dip became ill with severe pneumonia, apparently following skin absorption.