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Biomedical subjects

R J Wilkins

Publications and source records attributed to R J Wilkins.

18 recordsLinked to original sources
PubMed1992

A search for Chlamydia trachomatis in synovial fluids from patients with reactive arthritis using the polymerase chain reaction and antigen detection methods.

A polymerase chain reaction (PCR) technique to detect Chlamydia trachomatis DNA was used to examine synovial specimens from patients with reactive arthritis. We were able to detect C. trachomatis DNA in synovial specimens which had been seeded with intact elementary bodies or chlamydial DNA. However, we were unable to detect chlamydial DNA in unseeded synovial specimens from 10 patients with sexually acquired reactive arthritis, 17 patients with reactive arthritis and 11 control patients with other arthropathies. In addition, using a monoclonal antibody technique, we were unable to detect chlamydial antigen in any of the synovial cell deposits examined. We conclude that C. trachomatis DNA was not present in the joints of these patients at the time of synovial fluid collection, and suggest that either DNA degradation occurred rapidly after viable chlamydiae had entered the joint or that chlamydial DNA was not present at any stage of the reactive response.

Antigens, Bacterial↗
PubMed1992

Measurement of intracellular pH in isolated bovine articular chondrocytes.

Cartilage is an avascular tissue, the cells of which are exposed to reduced extracellular pH. The synthesis of cartilage matrix by chondrocytes is pH-sensitive and therefore control of intracellular pH (pHi) is important. We have measured the pHi of chondrocytes in MOPS-buffered saline (pH 7.4) using the fluorescent dye 2',7'-bis-2-(carboxyethyl)-5(6)-carboxyfluorescein. Mean pHi was 7.10 +/- 0.04 (+/- S.E.M., n = 22), and intracellular buffering power was 30 +/- 4 mmol l-1 (pH unit)-1 when pHi was displaced over the range 7.4-7.8 (n = 13). Recovery from acid load was blocked by 100 microM-ethylisopropylamiloride or by removal of extracellular Na+, indicating that these cells possess the Na(+)-H+ antiporter.

Animals↗
PubMed1992

Expression of alpha-lactalbumin, alpha-S1-casein, and lactoferrin genes is heterogeneous in sheep and cattle mammary tissue.

We used 35S-labeled cRNA probes to localize the sites of alpha-lactalbumin, alpha-S1-casein, and lactoferrin mRNA synthesis in sheep and forcibly weaned cattle mammary tissue. Expression of alpha-lactalbumin was absent in three of four "virgin" glands studied, present in some alveoli of "pregnant" glands but not in others, despite a similar histological appearance. In the early lactating gland, expression was high in those alveoli with few fat globules in their cells and lumen and was absent in alveoli with abundant fat globules. These observations suggest either that alpha-lactalbumin gene expression is linked to the long-term secretory activity of cells and falls once cells are resting or regressing, or that there are cyclical variations in expression, or that in the lactating gland some groups of epithelial cells are synthesizing alpha-lactalbumin and some are synthesizing fat. Expression patterns of alpha-S1-casein were similar to those of alpha-lactalbumin. Lactoferrin, in contrast, was expressed almost exclusively in the "fatty alveoli" of both species. Our results show that dramatic variations in milk gene expression can occur throughout the mammary gland of sheep and cattle and that at no stage of pregnancy, lactation, or involution can the gland be considered metabolically homogeneous.

Animals↗
PubMed1992

Interstitial collagenase gene expression in oral squamous cell carcinoma.

In this study, in situ hybridization techniques were used to determine the location of interstitial collagenase and tissue inhibitor of metalloproteinase (TIMP) gene expression in samples from 11 squamous cell carcinomas of the head and neck (particularly the oral cavity) and from non-neoplastic mucosa of the same region. Ten of the 11 carcinomas examined showed abundant levels of collagenase gene expression in stromal fibroblasts within connective tissues immediately adjacent to tumor masses. Lower levels were detected in basaloid tumor cells located at the periphery of several tumor masses. Interstitial collagenase expression was consistently low in all normal, hyperplastic, and dysplastic epithelial sections. TIMP gene expression was negligible in all tissues examined. These results support the view that stromal interstitial collagenase production may play a key role in assisting invasiveness of squamous cell carcinoma of the head and neck.

Carcinoma, Squamous Cell↗
PubMed1992

Use of computerized interactive morphometry in the diagnosis of mammary adenoma and adenocarcinoma in dogs.

We attempted to define quantitative objective criteria for diagnosis of mammary adenoma and adenocarcinoma in dogs. To that end, correlation between diagnosis made by conventional histologic examination and morphometric descriptors, obtained by computerized histologic analysis, was assessed in biopsy specimens of mammary tissue from 63 dogs. We used 2 interactive computer procedures: one assessed mean nuclear perimeter, mean nuclear area, and circularity factor; and the other evaluated nuclear stratification and cell crowding. A data base was generated with 11 specimens from normal mammary tissue, 17 specimens from mammary adenoma, 18 specimens from low-grade mammary adenocarcinoma, and 15 specimens from mammary adenocarcinoma. The mean values of nuclear perimeter, nuclear area, nuclei per millimeter of basement membrane, and minimal distances from cells to basement membrane gradually increased from normal to high-grade malignancy. Distributions of nuclear areas and of minimal distances from cells to basement membrane were shifted in specimens from malignant tumors. Multivariate analysis confirmed the homogeneity of the diagnostic groups.

Adenocarcinoma↗
PubMed1978

Photosnesitization of DNA by gold.

Au (III) reacts with DNA at pH 5.6 to form a complex which is sensitive to mid-UV radiation. Cyclobutane pyrimidine dimers are produced at some 15 to 30 times the rate that they are in untreated DNA. The mechanism of photosensitization appears to involve energy absorption by Au-urine and Au-cytosine adducts which can then transfer energy to thymine residues. There is no evidence for a "heavy atom" effect which enables metals such as Ag to mix excited states of DNA and to increase the quantum yields of some photoproducts. The use of mid-UV radiation as a probe for investigating the interaction between DNA and drugs such as sodium aurothiomalate is discussed.

Apurinic Acid↗
PubMed1976

Formaldehyde induced DNA-protein crosslinks in Escherichia Coli.

Exposure of Escherichia coli to low doses of formaldehyde induces interstrand cross-links in the cellular DNA, at least 50% of which involve protein "bridges" between the DNA strands. The biological importance of these cross-links is suggested by both the high yield of formation and by the inability of some sensitive repair deficient mutants to completely remove cross-links and bound protein from the DNA during post treatment incubation.

Bacterial Proteins↗
PubMed1976

The use of a technicon SMA 12/60 multichannel biochemical analyzer in veterinary clinical pathology.

This article has described many of the advantages of using a sequential multichannel autoanalyzer to obtain a biochemical profile on animal blood specimens and how this profile can be used in assessing the patients biochemical status. Precautions concerning the collection of blood samples to avoid spurious results have been emphasized. Hemolysis should, in particular, be avoided. Ideally, plasma should be separated from cells shortly after collection and refrigerated. If this is not possible, storage of whole blood under refrigeration (4 degrees C.) is permissible for a short period. In these cases minor changes in blood glucose, total CO2, and calcium may be expected. Also presented are some of the statistical calculations and manipulations that are possible utilizing a data bank containing the data from the SMA 12/60. This information is being used to update much of our knowledge of veterinary clinical pathology.

Alkaline Phosphatase↗
PubMed1975

Treatment of basophilic leukemia in a dog.

Basophilic leukemia in a 6-year-old dog was characterized by marked splenomegaly, anemia, and leukocytosis in which 89% of the circulating leukocytes were basophilis. After an attempt at busulfan therapy, the dog was treated with hydroxyurea and was maintained on this drug for 2 months. After withdrawl of hydroxyurea, the dog remained in remission and was still in remission at the time of writing (8 months later).

Animals↗