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Biomedical subjects

D Mock

Publications and source records attributed to D Mock.

At least 73 records · Page 4Linked to original sources

Biotin transport through the blood-brain barrier.

The unidirectional influx of biotin across cerebral capillaries, the anatomical locus of the blood-brain barrier, was measured with an in situ rat brain perfusion technique employing [3H]biotin. Biotin was transported across the blood-brain barrier by a saturable system with a one-half saturation concentration of approximately 100 microM. The permeability-surface area products were 10(-4) s-1 with a biotin concentration of 0.02 microM in the perfusate. Probenecid, pantothenic acid, and nonanoic acid but not biocytin or biotin methylester (all 250 microM) inhibited biotin transfer through the blood-brain barrier. The isolated rabbit choroid plexus was unable to concentrate [3H]biotin from medium containing 1 nM [3H]biotin. These observations provide evidence that: biotin is transported through the blood-brain barrier by a saturable transport system that depends on a free carboxylic acid group, and the choroid plexus is probably not involved in the transfer of biotin between blood and cerebrospinal fluid.

Animals↗

Osteosarcoma in irradiated fibrous dysplasia.

A case is described of osteosarcoma arising in a pre-existing fibrous dysplasia fifty years after radiotherapy for facial hirsutism. The patient was treated by surgical excision and chemotherapy and is alive and free of disease five years later.

Aged↗

Atypical facial pain: a retrospective study.

Among the most challenging patients seen for evaluation by a health care practitioner are those suffering from the atypical facial pain syndrome. They have almost inevitably been subjected to extensive treatment which either has had no effect on the symptoms or has aggravated them. This article reports a retrospective study of thirty-four randomly selected cases of atypical facial pain that have been seen by a multidisciplinary pain group.

Adult↗

The effect of DMBA on hamster cheek pouch mucosa in vitro: constant exposure.

Repeated topical application of DMBA to hamster cheek pouch mucosa in vivo has been shown to cause dysplastic changes and ultimately the development of squamous cell carcinomas in the epithelium. A technique has already been reported whereby neonatal hamster pouch mucosa can be maintained in vitro and dysplastic changes have been described in the epithelium after a single exposure to DMBA. By 35 days in organ culture, these changes disappeared and the epithelium regained its normal organotypic morphology. In this study, the tissue was maintained in vitro in medium containing various concentrations of DMBA for up to 49 days. Dysplastic changes were seen in the epithelium of the explants with some histological evidence of malignant behaviour. These changes were observed throughout the experimental period.

9,10-Dimethyl-1,2-benzanthracene↗

The effect of DMBA on hamster cheek pouch mucosa in vitro.

Neonatal hamster cheek pouch mucosa was treated with DMBA for three h either before being explanted or after 7 days in vitro. The epithelium of the treated cultures exhibited dysplasic changes, most marked at 21 to 28 days in vitro. These changes were not seen in the explants maintained for 35 to 49 days in vitro indicating a return to an apparently normal morphology. Examination of the ultrastructure of DMBA treated and untreated explants showed changes consistent with those described in similar tissues in vivo. The epithelium of the carcinogen treated tissue exhibited widened intercellular spaces, tortuous cell membranes, an irregular and discontinuous basal lamina and pseudopodia of the basal cells extending into the underlying mesenchyme. Similar changes have been described in inflamed epithelium, in some other experimental preparations, and in premalignant lesions in vitro, both in animals and man.

9,10-Dimethyl-1,2-benzanthracene↗

The effect of vitamin A on hamster cheek pouch mucosa in organ culture.

Vitamin A was added to the medium of neonatal hamster cheek pouch mucosa maintained in organ culture. The epithelium of the treated explants showed a reduction in keratinization and down-growth into the underlying connective tissue. The cytological and morphological changes in the epithelium were consistent with glandular metaplasia.

Animals↗

Long-term organ culture of hamster cheek pouch mucosa.

Explants of cheek pouch mucosa from 12- to 48-hour-old hamsters have been maintained in organ culture for up to 49 days with excellent preservation of tissue integrity and relationships. The technique uses gelatin sponge matrix in Leighton tubes with Eagle's Minimum Essential Medium (M.E.M.) supplemented with 10% calf serum and antibiotics.

Animals↗

Salivary gland tumors: review of 643 cases.

643 cases of salivary gland tumors constitute two series of histological sections that were studied from hospitals and dental schools in Southeast Scotland and Southern Ontario. The Scottish series represented epithelial tumors of the parotid and intra-oral salivary glands, but the Canadian series also included tumors of the submandibular and sublingual glands. Classification was based on that recommended by the World Health Organisation (Thackray 1972). While direct statiscal comparisons between the two series are not appropriate, the differences between them suggest that malignant tumors are more common in Canada. The Scottish series contains the largest proportion of benign salivary tumors so far reported. In the Scottish series, 88.7% of parotid tumors were benign compared with 51.9% of Canadian series. In the Canadian series from the submandibular glands, 21.2% only were benign. Of the intra-oral salivary tumors, 62.2% from the Scottish series were benign compared with only 34.7% from the Canadian series.

Adenocarcinoma↗