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Biomedical subjects

D Atkins

Publications and source records attributed to D Atkins.

At least 19 recordsLinked to original sources
PubMed1992

Vitamin content of camel milk.

The content of vitamin C, vitamin B2 and fat-soluble vitamins E and A in camel milk was studied. The milk samples were collected from 20 individual camels (Camelus dromedarius) in two different occasions. The study showed that camel milk contains considerably less vitamin A and B2 than cow milk while the content of vitamin E was about the same level. The level of vitamin C was in average three times higher than that of cow milk.

Animals↗
PubMed1991

Syncope and orthostatic hypotension.

PURPOSE: The purpose of this study was to determine the postural blood pressure response over time, the prevalence of orthostatic hypotension in patients with syncope, and the relationship of orthostatic hypotension to recurrence of symptoms. PATIENTS AND METHODS: We prospectively evaluated 223 patients with syncope in a standardized manner. Orthostatic responses were measured in a standardized fashion at 0, 1, 2, 3, 5, and 10 minutes or until symptoms occurred. Follow-up was obtained at 3-month intervals. Causes of syncope were assigned by predetermined criteria. RESULTS: Orthostatic hypotension (20 mm Hg or greater systolic blood pressure decline) was found in 69 patients (31%). The median time to reach minimal standing systolic blood pressure was 1 minute for all subjects. In patients with orthostatic hypotension (20 mm Hg or greater), mean time to reach minimum blood pressure was 2.4 minutes. The vast majority of patients with significant orthostatic hypotension had this finding within 2 minutes of standing. Orthostatic hypotension was common in patients for whom other probable causes of syncope were assigned. The recurrence of syncope was not related to the degree of orthostatic hypotension; however, the recurrence of dizziness and syncope as end-points was lower in patients with 20 mm Hg or greater systolic blood pressure reductions as compared with patients with lesser degrees of orthostatic blood pressure declines. CONCLUSION: Orthostatic hypotension is common in patients with syncope and is detected in the vast majority of patients by 2 minutes. Although symptom recurrence on follow-up was lower in patients with more severe orthostatic hypotension, the clinical significance of this finding needs to be further defined by future studies.

Adolescent↗
PubMed1991

The tobacco mosaic virus 30K movement protein in transgenic tobacco plants is localized to plasmodesmata.

Transgenic tobacco plants expressing a gene encoding the tobacco mosaic virus (TMV) movement protein (30K) were studied using immunocytochemical techniques. The movement protein was shown to be localized within or on most of the plasmodesmata observed in the transformed plant. These results are consistent with the idea that the movement protein interacts with the plasmodesmata to facilitate the cell-to-cell spread of TMV.

Capsid Proteins↗
PubMed1991

Expression of the tobacco mosaic virus movement protein using a baculovirus expression vector.

A cDNA clone of the tobacco mosaic virus 30K movement protein (MP) gene was constructed and introduced into an Autographa californica nuclear polyhedrosis baculovirus expression vector. Infection of Spodoptera frugiperda cells with the vector resulted in the synthesis of low levels of MP, which was detected by anti-MP serum as two closely related species of Mr approximately 34K and a third species of 32K. The authenticity of the recombinant MP was confirmed by comparison of the protein, on the basis of migration during SDS-PAGE, with authentic MP from several sources. It appeared that the recombinant MP was not modified by N-linked glycosylation, but was phosphorylated. The recombinant MP was produced in both a phosphorylated and an unphosphorylated state and the former species was shown to comigrate with plant-expressed MP during SDS-PAGE.

Animals↗
PubMed1977

Rat osteogenic sarcoma cells:effects of some prostaglandins, their metabolites and analogues on cyclic AMP production.

Cyclic AMP production by freshly isolated cells, from a 32P-induced transplantable rat osteogenic sarcoma, was stimulated by PGE1, PGE2 and to a less extent by PGF2alpha and PGA2. In the case of PGE2, the cyclic AMP content of cells was maximal within 5 min. The 13,14-dihydroderivatives of PGE1, PGE2 and PGF2alpha had approximately 40% of the activity of the parent prostaglandin whilst, in every case, the metabolites (15-keto and 13,14-dihydro-15-keto) had very little activity. Two prostaglandin endoperoxide analogues (U44069 and U46619) had only 10% of the activity of an equimolar dose of PGE2. The data presented in this paper demonstrates similarities between the responses of these cells and cells derived from bony tissue in terms of the ability of prostaglandins to stimulate bone resorption in tissue culture.

Animals↗
PubMed1977

Secretion of prostaglandins as bone-resorbing agents by renal cortical carcinoma in culture.

Fragments of human renal carcinoma tissue have been co-cultured with mouse calvaria. In 9/13 cases significant bone resorption occurred whilst in no case did control kidney cause significant resorption. When bone resorption did occur, it could be reduced by inclusion of indomethacin in the culture medium. In some cases when theophylline was included in culture medium to prevent cyclic AMP breakdown, there was enhancement of tumour-induced bone resorption. Control studies without tumour showed that none of the experimental treatments had a direct effect on bone. Radioimmunoassay of prostaglandin E (PGE) levels in pooled culture media showed that tumour fragments produced appreciable amounts of PGE, and that this production was lowered by indomethacin and increased by theophylline. It is concluded that the bone resorption induced by these tumours is due to a prostaglandin, and that prostaglandin production may be controlled by changes in cyclic AMP metabolism.

Animals↗
PubMed1977

Radiation induced osteogenic sarcoma in the rat as a model of hormone-responsive differentiated cancer.

An osteogenic sarcoma was induced in an inbred strain of the Sprague Dawley rat using seven serial injections of 32P-orthophosphate. The tumor was maintained by transplantation over a 3-year period in the same inbred strain. During this time it retained its bone-like differentiation. Tumor membranes and freshly isolated tumor cells also retained responsiveness to parathyroid hormone and to prostaglandins of adenylate cyclase and cyclic nucleotide formation respectively. The potencies of these agents and their analogues and metabolites were found to be proportional to their efficacies as bone resorbing agents. Thus, the tumor was shown to be a model for the study of hormone-responsiveness for tumor growth and differentiation, and also of the effects of agonists which act on bone-like cells.

Adenylyl Cyclases↗