Search PubMed⌕ Search

Biomedical subjects

R Curtis

Publications and source records attributed to R Curtis.

At least 109 records · Page 6Linked to original sources
PubMed1987

An early-onset retinal dystrophy with dominant inheritance in the Abyssinian cat. Clinical and pathological findings.

The clinical and pathological features of an early-onset autosomal dominant photoreceptor degeneration in the Abyssinian cat are described. Ophthalmoscopic evidence of retinal disease at 8-12 weeks of age was always preceded by marked dilatation of the pupils, impairment of the pupillary light reflex, and nystagmus. The electroretinogram was unrecordable in all but one of the affected individuals examined. Abnormal photoreceptor development was observed by both light and electron microscopy in retinas of a 22-day-old kitten; in this individual, no outer segment material was detected, and inner segments showed impaired development which was more severe towards the posterior pole. In a 40-day-old kitten, the inner segments were relatively well-formed, whereas the outer segments, though present, showed marked disorganization and degenerative change. The retinas of older individuals showed more advanced photoreceptor degeneration, with thinning of the neural retina. This early-onset retinopathy, which may be classified as a rod-cone dysplasia, is distinct from the hereditary retinal dystrophy (progressive retinal atrophy) previously described in this breed. The gene symbol Rdy has been adopted.

Animals↗
PubMed1986

The interaction of Schwann cells with CNS axons in regions containing normal astrocytes.

On occasions retinal axons can be myelinated by Schwann cells. In the present experiments cultured autologous Schwann cells were injected into the optic disc of adult cats and the extent of Schwann cell myelination determined. Little if any Schwann cell myelination of retinal ganglion cell axons developed. Schwann cells were also injected into lesions in the cerebral cortex induced by ethidium bromide. In this site some Schwann cell remyelination was detected, but it was restricted to areas next to regions of malacia induced by the injection procedure. It was concluded that astrocyte responses, limit Schwann cell myelination and remyelination in normal tissue by excluding Schwann cells from the CNS compartment, and induce changes in chronically demyelinated and amyelinated axons which may affect myelination.

Animals↗
PubMed1986

Retinal function in rats and guinea-pigs reared on diets low in essential fatty acids and supplemented with linoleic or linolenic acids.

Rats were reared into a third generation on diets deficient in essential fatty acids supplemented with linoleic acid (18:2 n-6) or linolenic acid (18:3 n-3) with the object of depleting the retina of n-6 or n-3 fatty acids. In the rats fed 18:2 n-6 the percentage by weight of 22:6 n-3 in retinal fatty acids fell from 22.5 to 8.5% in first-generation animals but then remained unchanged in second and third generations. There was no difference in b-wave amplitudes of the electroretinogram between the rats fed 18:2 n-6 and those fed 18:3 n-3. In guinea-pigs fed purified diets low in 18:3 n-3 the percentage by weight of 22:6 n-3 in retinas fell from 8 to less than 0.5% by the third generation. However, there were no statistical differences in the b-wave amplitudes between these animals and those reared on a commercial diet. It is concluded that if n-3 fatty acids are involved in retinal function their role is too subtle to be detected by standard electroretinographic techniques.

Aging↗
PubMed1984

Comparison of canine oropharyngeal malignancy in various geographical locations.

The variation in prevalence of neoplasms over time and location has been of value in identifying environmental carcinogens. Studies on the relative frequency of the different histological types of canine oropharyngeal malignant neoplasm have shown that squamous cell carcinoma of the tonsil occurs four times more commonly in south east England, and twice as frequently in the United States of America as in Melbourne, Australia. The prevalence of tonsillar squamous cell carcinoma in London in 1950 was 15 times greater than that currently experienced in Melbourne and four times greater than that now found in other areas of south east England.

Animals↗
PubMed1984

Multiple primary breast and thyroid cancer.

The occurrence of breast and thyroid multiple primary cancers was evaluated using data from the Connecticut Tumor Registry. The study population consisted of 1618 women with primary thyroid cancer and 39,194 women with primary breast cancer diagnosed between 1935 and 1978. Thirty-four thyroid cancer patients subsequently developed breast cancer and 24 breast cancer patients later had thyroid cancer. A significantly elevated risk of thyroid cancer following breast cancer (SIR = 1.68) and breast cancer following thyroid cancer (SIR = 1.89) was demonstrated. The finding was even more notable when compared with the risks obtained for other sites. The elevated risk was particularly evident in women under 40 years of age at time of diagnosis of the first cancer. Analysis by histologic type revealed that the highest risk of second primary breast cancer was found among patients with follicular or mixed papillary-follicular thyroid cancer. Women under age 40 with follicular carcinoma had a 10-fold risk of developing breast cancer (4 observed, 0.4 expected). An enhanced risk of second primary tumours was evident for the entire period after treatment of the first primary, although it was highest within one year after diagnosis of the first primary. This may be due to the close medical surveillance of cancer patients which would increase early diagnosis of second tumours. Our findings suggest that breast and thyroid cancer may share common aetiologic features.

Adult↗
PubMed1983

The 'blue eye' phenomenon.

Diffuse clouding of the cornea ('corneal oedema', 'blue eye') of sudden onset and usually transient duration and with accompanying anterior uveitis, may be attributable to natural infection with canine adenovirus type 1 (CA-1) or to vaccination with live modified virus. It is now recognised that kerato-uveitis is a manifestation of type III hypersensitivity in which immune complex formation resulting from the release of virus, especially from infected corneal endothelial cells, brings about corneal endothelial damage and hence corneal oedema. A proportion of cases fail to resolve. At least one breed, the Afghan hound, appears to be particularly susceptible. The incidence of ocular lesions resulting from vaccination has stimulated the development of new vaccines incorporating canine adenovirus type 2 (CAV-2), a serotype which has been shown not be cause endogenous ocular disease.

Adenoviridae Infections↗
PubMed1983

Clinical and pathological observations concerning the aetiology of primary lens luxation in the dog.

A series of 123 consecutive referred cases of lens dislocation in the dog were classified as primary (100), secondary (21) and congenital (two). Cases designated as primary lens luxation comprised only the terrier breeds or crossbreds and collectively appeared to represent a single clinical entity characterised by age of onset (mean four to five years), essential bilaterality and the apparent absence of antecedent ocular disease. Elevated intraocular pressures were encountered in many eyes exhibiting subluxation. However, in three Tibetan terriers, on which tonometry was performed on a daily basis for approximately one year during the period of subluxation and before the development of luxation, there was no evidence of abnormal intraocular pressure change, suggesting that ocular hypertension in primary lens luxation is a secondary and not a primary development. All but one of nine affected eyes representing three terrier breeds showed abnormalities of the suspensory apparatus of the lens (zonule) which resembled those reported previously in Tibetan terriers bred for the condition.

Animals↗
PubMed1983

Aetiopathological aspects of inherited lens dislocation in the Tibetan Terrier.

Four litters of Tibetan Terriers were bred in order to study the ocular pathology of primary lens luxation, which in this breed is due to an autosomal recessive gene. Scanning and transmission electron microscopy were carried out on ocular tissues of 5 dogs from 2 homozygous litters killed at various ages up to the time of onset of clinical subluxation. All eyes showed zonular abnormality, in particular a bizarre arrangement of fibrillar material associated with the ciliary processes and relating to the system of zonular fibres inserting posteriorly at the lens equator. A further litter, the result of an affected X carrier mating and killed at 20 months of age, included 2 affected and 2 unaffected dogs. The pathological changes noted in affected eyes are reconciled with the clinical signs observed in 4 homozygous dogs developing lens luxation.

Animals↗
PubMed1983

A field trial, of preshipment vaccination, with intranasal infectious bovine rhinotracheitis-parainfluenza-3 vaccines.

A total of 849 calves, 278 controls, 335 vaccinated intranasally with IBR-PI3/TS and 236 vaccinated intranasally with IBR-PI3/PTC were studied in a field trial of preimmunization. All calves were vaccinated in Saskatchewan at least three weeks prior to shipment to feedlots. Four hundred and twenty six calves were not sold within eight weeks of vaccination; however, seven of these died within four weeks of vaccination. Treatment rates varied from 1.0% to 5.2%. There was no significant effect of vaccination on treatment rates. Similarly, there was no significant effect of vaccination in the 74 calves sold to feedlots in Saskatchewan. Three hundred and forty nine calves were sold to feedlots in Ontario. Two of these died from fibrinous pneumonia. Treatment rates varied from 1.7% to 33.3% in different feedlots, but there was no significant effect of vaccination on treatment rates. Therefore, preimmunization is unlikely to significantly reduce the overall treatment rate in calves entering feedlots.

Animals↗
PubMed1983

High efficiency membrane oxygenator.

An adult membrane oxygenator of new design has been described which possesses excellent operating characteristics. The preliminary safety and efficacy of the device was demonstrated by in vitro performance testing and by the minimal blood trauma and absence of significant time dependent change during 6 hr ex vivo perfusions. These encouraging results are the basis for proceeding with clinical studies.

Animals↗
PubMed1983

The suspensory apparatus of the canine lens.

The suspensory apparatus of the canine lens was studied in gross specimens stained with periodic acid and Schiff's reagent, and by transmission and scanning electron microscopy. Two distinct groupings of zonular fibres were discernible: those passing along the crests of the ciliary processes and inserting at the lens anterior to the equator, and those arising from the walls of the ciliary processes and inserting posteriorly at the lens. In addition, zonular fibres were found to arise from single plicae and from processes of intermediate size located between the main ciliary processes. The vitreous body was firmly attached to the pars plana, over which zonular fibres passed in a meridional direction, and also to the lens capsule adjacent to the posterior zonular insertions. The mode of insertion of the zonular fibres at the lens and over the unpigmented ciliary epithelium is described. Zonular fibrils averaged approximately 13 nm in diameter, with a periodicity of 17 nm and were morphologically similar to those of other species.

Animals↗