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Biomedical subjects

J A Cameron

Publications and source records attributed to J A Cameron.

87 records · Page 5Linked to original sources
PubMed1969

Immunochemistry of the cell walls of Listeria monocytogenes.

The antigenic specificity of Listeria monocytogenes types I, II, III, IVa, and IVb was studied by immunochemical techniques. Immunologically active carbohydrates of the various types were extracted from cell walls and were chemically analyzed. Types I and II contained predominantly glucosamine and rhamnose; type III, galactose, rhamnose, and glucosamine; and types IVa and IVb, glucose and galactose. Quantitative precipitin inhibition tests with purified monosaccharides indicated that the major antigenic determinant of types I and II is rhamnose. Precipitin reactions could not be detected with type III carbohydrate and homologous or heterologous antisera. The major determinants of types IVa and IVb were found to be galactose and glucose, respectively. As much as 87% inhibition of the quantitative precipitin test for types I and II was obtained with rhamnose, 72% for type IVa with galactose, and 72% for type IVb with glucose. The immunochemical basis for the antigenic specificity of L. monocytogenes types I, II, IVa, and IVb was further confirmed by using agar gel diffusion. Cross-reactions among the various type-specific carbohydrates and heterologous antisera were also studied. Type II carbohydrate was found to contain galactose and react with type IVa antisera. This reaction could be blocked by galactose. Type I carbohydrate did not contain galactose nor did it react with antiserum prepared from type IVa cells. Therefore, the somatic antigens of type I and type II L. monocytogenes, previously thought to be identical, appeared to differ. The dominant immuno-specific group in the cross-reaction between type IVb carbohydrate and type IVa antisera was found to be galactose. Type IVa absorbed antisera did not produce a significant cross-reaction with type IVb carbohydrate. The results obtained from this investigation indicate a lesser degree of antigenic relationship between type IVa and type IVb L. monocytogenes than was previously believed to exist.

Alanine↗
PubMed1967

Thiobarbiturate-reacting materials in microorganisms.

The amount of thiobarbiturate-reacting material in 51 strains of bacteria and three yeasts was determined. Reactive material was found to be present in all of the gram-negative bacteria examined. It was assumed that the reactive material in this case was primarily 2-keto-3-deoxyoctonate (KDO), an eight-carbon sugar acid which is usually associated with the cell wall lipolysaccharide of members of the Salmonella-Escherichia group. Very little reactive material could be detected in the gram-positive species and yeasts that were examined. When expressed as per cent dry weight, the gram-negative bacteria exhibited about eight times more reactive material than the gram-positive species. It is suggested that the small amount of reactive material detected in gram-positive cells and yeasts is due to compounds other than KDO.

Bacteria↗
PubMedDate not supplied

Good visual result following early penetrating keratoplasty for Peters' anomaly.

Visual results following penetrating keratoplasty for congenital corneal opacities have been generally disappointing, prompting many ophthalmologists to recommend no surgery for congenital, monocular corneal opacities. A 14-day-old boy had a penetrating keratoplasty performed for unilateral Peters' anomaly and microcornea. Visual acuity 49 months after surgery was 20/40 and peripheral fusion was present. Early surgery with early suture removal, amblyopia therapy, frequent clinical examinations, and motivated, well-informed parents were important factors in obtaining a good visual result.

Amblyopia↗
PubMedDate not supplied

Excimer laser phototherapeutic keratectomy for shield ulcers and corneal plaques in vernal keratoconjunctivitis.

BACKGROUND: Shield-shaped corneal ulcers and corneal plaques in vernal keratoconjunctivitis are associated with delayed epithelial healing, as well as the risks of infectious keratitis and sterile stromal ulceration. Significant visual impairment due to scarring and irregular astigmatism may result from central corneal lesions. METHODS: Three eyes with central corneal lesions resulting from vernal keratoconjunctivitis were treated by excimer laser after active vernal keratoconjunctivitis was controlled and inflammatory plaque overlying the shield ulcers was removed. RESULTS: All three eyes showed rapid reepithelialization within 1 week. Spectacle-corrected visual acuity of 20/30 or better was obtained in each eye. CONCLUSIONS: In selected patients, excimer laser phototherapeutic keratectomy may be a useful adjunct in the treatment of shield-shaped corneal ulcers and plaques in vernal keratoconjunctivitis.

Adolescent↗
PubMedDate not supplied

Phototherapeutic keratectomy for climatic droplet keratopathy, KKESH Excimer Laser Study Group. King Khaled Eye Specialist Hospital.

BACKGROUND: Phototherapeutic keratectomy (PTK) is an effective treatment for many superficial corneal disorders. The efficacy of PTK for the treatment of climatic droplet keratopathy (CDK) has not been reported. METHODS: We report the results of excimer laser (Summit Technology, Inc, Waltham, Mass) PTK on 75 eyes (67 patients) with "smooth" climatic droplet keratopathy (55 eyes) and "irregular" climatic droplet keratopathy (20 eyes) in whom more than 6 months of follow up are available. RESULTS: PTK was successful in reducing corneal opacification in both smooth (98%) climatic droplet keratopathy and irregular (80%) climatic droplet keratopathy. Achievement of a clear or mildly hazy cornea following PTK was more likely to occur with smooth (80%) climatic droplet keratopathy than irregular (25%) climatic droplet keratopathy (P = 0.01). Eyes with smooth climatic droplet keratopathy were more likely to obtain more than one line of improved uncorrected (56% vs. 25%) or spectacle-corrected visual acuity (61.8% vs. 21.2%) than those with irregular climatic droplet keratopathy (P = 0.03 and 0.005, respectively). Delayed re-epithelialization (longer than 14 days) was more common in irregular CDK (21%) than in smooth CDK (9%), as was the incidence of secondary microbial keratitis (10.0% vs. 1.8%). CONCLUSIONS: PTK is effective in reducing superficial corneal opacification in CDK, although serious complications may occur, especially in advanced irregular CDK.

Aged↗
PubMedDate not supplied

[The role of the myoblasts and connective tissue in the regeneration of the limbs in amphibians].

A possibility of tissue metaplasia (transformation of one cell type into another) during limb regeneration in lower vertebrates has been a matter of vivid arguments over the last decades. These discussions are rather irreconcilable in character mainly due to the lack of reliable cell markers which permit to follow all the stages of cell transformation during metaplasia. The final conclusions can be made only if any artifacts of cell labelling are excluded. Latest findings obtained using nuclear and cytoplasmic markers are presented which suggest that many data interpreted previously as a convincing proof of metaplasia may be a consequence of the involvement of nondifferentiated cells in regeneration. Molecular biological approaches are believed to be most promising for the solution of disputable problems of tissue metaplasia. However, recent findings about actin gene hypomethylation are insufficient for any final conclusions about the possibility of metaplasia during limb regeneration. The answer to many unsolved questions of developmental biology can be made only when combined use is made of modern methods of cell and molecular biology.

Amphibians↗