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Biomedical subjects

D C Williams

Publications and source records attributed to D C Williams.

At least 163 records · Page 9Linked to original sources
PubMed1981

Insulin synthesis in a clonal cell line of simian virus 40-transformed hamster pancreatic beta cells.

A clonal hamster beta cell line (HIT) was established by simian virus 40 transformation of Syrian hamster pancreatic islet cells. Cytoplasmic insulin was detected in all cells by indirect fluorescent antibody staining, and membrane-bound secretory granules were observed ultrastructurally. Acidified-ethanol extracts of HIT cell cultures contained hamster insulin as determined by radioimmunoassay, radioreceptor assay, and bioassay. One subclone at passage 39 contained 2.6 micrograms of insulin per mg of cell protein. [3H]Leucine-labeled HIT insulin and proinsulin were identical to islet-derived proteins when compared by NaDodSO4/polyacrylamide gel electrophoresis of immunoprecipitates. HIT cell insulin secretion was stimulated by glucose, glucagon, and 3-isobutyl-1-methylxanthine. Insulin secretion at optimal glucose concentration (7.5 mM) was 2.4 milliunits per 10(6) cells per hr. Somatostatin and dexamethasone markedly inhibited HIT insulin secretion. The HIT cell line represents a unique in vitro system for studying beta cell metabolism and insulin biosynthesis.

Animals↗
PubMed1981

Use of inverted intestinal sacs to assess the effect of gastrointestinal insult on carcinogen absorption.

Rats were subjected to various forms of treatment in the manner likely to induce gastrointestinal insult. These and control animals were sacrificed and, using inverted sacs, the rate of absorption of either dimethylnitrosamine and benzo(a)pyrene determined. The gastrointestinal injury resulting from the differing treatments did not significantly affect the absorption of benzo(a)pyrene, whereas that of dimethylnitrosamine was significantly increased after each incubation time, most notably by alcohol pretreatment. The results demonstrate that intestinal damage increases the absorption of some carcinogens.

Animals↗
PubMed1981

The influence of zinc status on the anti-Lewis lung tumour activity of cisplatin and gallium.

Treatment of C57/BL mice with either cisplatin or gallium nitrate inhibited the growth and metastasis of the Lewis lung tumour and these anti-tumour agents also lowered the zinc levels of some tissues. Nutritional zinc deficiency or the deficiency arising from treatment with the chelating agent, penicillamine, also restricted tumour growth. Although the anti-tumour activity of cisplatin was enhanced in zinc-deficient mice, many of these animals died before sacrifice 14 days after tumour inoculation. The results indicate that zinc status could have considerable bearing on the therapeutic index of the mental-containing anti-cancer drugs.

Animals↗
PubMed1981

The endogenous lectin of human platelets is an alpha-granule component.

Platelets from patients with several bleeding disorders (congenital afibrinogenemia, Glanzmann's thrombasthenia, gray platelet syndrome, and Hermansky-Pudlak syndrome) were evaluated for both platelet-bound and platelet-free hemagglutination activities. Thrombin and A23187 activated afibrinogenemic, Hermansky-Pudlak, and thrombasthenic platelets had normal platelet-bound hemagglutination activity. Gray platelets activated by the same agents had deficient platelet-bound hemagglutination activity. In contrast, thrombin-activated afibrinogenemic, gray, and thrombasthenic platelets lacked platelet-free hemagglutination activity. Only thrombin-activated Hermansky-Pudlak platelets had a normal level of platelet-free hemagglutination activity. On the basis of these results and the distinguishing characteristics of the defective platelets, it is concluded that the alpha-granules are the origin of the enhanced hemagglutination activity. Furthermore, it is suggested that the insufficiency of the platelet-bound agglutinin may be the cause of the inability of gray platelets to aggregate normally in response to thrombin.

Blood Coagulation Disorders↗
PubMed1981

Comparison of concentrations of some trace, bulk, and toxic metals in the hair of normal and dyslexic children.

Hair from dyslexic children, analyzed by flameless atomic absorption spectrometry, showed significantly higher concentrations of magnesium and copper than did hair from control subjects. The hair from dyslexic children also contained significantly higher concentrations of aluminum and cadmium than that from control children; the cadmium concentration exceeded the normal acceptable range. There were no significant differences in the case of lead, calcium, selenium, or mercury. Our results indicate that excessive cadmium burden could be implicated in this form of learning disorder.

Adolescent↗
PubMed1981

Combined therapy with ascorbic acid and calcitonin for the relief of bone pain in Paget's disease.

In a short trial, 24 patients with Paget's disease of the bone were treated for 2 weeks with either ascorbic acid and calcitonin in combination, or with calcitonin alone. Pain relief was then assessed subjectively by the patients and classified as nil, some, or a marked reduction in pain. There were 11 patients in the group on combined therapy and 73% of them experienced pain relief, compared with 85% of the 13 patients in the group on calcitonin alone. In the patients who experienced pain relief, however, 62% of those on the ascorbic acid and calcitonin combination claimed a marked relief of pain compared with only 36% of the patients who responded to calcitonin alone. These results indicate that when calcitonin and ascorbic acid are used in combination they may provide an increase in the extent of pain relief, but do not increase the total proportion of patients actually obtaining relief. Urinary hydroxyproline excretion was reduced in the calcitonin treated group, but there was little change in the patients on the combined therapy.

Ascorbic Acid↗
PubMed1980

Plasminogen activator in cultured Lewis lung carcinoma cells measured by chromogenic substrate assay.

A chromogenic substrate assay for the plasminogen activator (PA) activity of Lewis lung carcinoma cells has been developed. The cells were incubated with plasminogen, the activation of which to plasmin was measured by the amidolysis of the chromogenic substrate S-2251. This was routinely performed as a 4h serum-free assay, but a variation lasting 24 h, in medium supplemented with plasminogen-free inhibitor-reduced serum, produced similar results. The assay also detected PA released into the medium. PA activity was proportional to cell density, and the assay was non-toxic to the cells. Assays were performed on cultures derived from primary and metastatic tumours. Host cells were effectively eliminated from such cultures but, because of an initial phase of tumour-cell death, PA assays were not carried out until cultures became established. No consistent difference was detected between PA levels in primary and metastatic cultures. However, these cultures were shown to be atypical of the parent tumour; they grew slowly when reinjected at the primary site, and their metastatic potential was impaired.

Animals↗
PubMed1980

The distinction between the antismoking and nonsmokers' rights movements.

In a recent article Markle and Troyer analyze the cigarette controversy as a status battle between pro and antismoking vested interests. They argue that the purpose of the antismoking movement is to lower the status of smokers, symbolically to label smoking as undesirable, unacceptable, and socially deviant behavior, and, hence, to stigmatize and denigrate smokers as social misfits. In this paper it is argued that it is important to extend the analysis by drawing a distinction between the general antismoking movement and the nonsmokers' rights movement. It is shown that the nonsmokers' right movement in its pure form is devoted solely to the protection of the rights of nonsmokers and does not endorse, and may even oppose, other elements of the general antismoking movement. The essential motivation is not the denigration of smokers but rather is the refusal of nonsmokers to be victimized by the oppressive conditions of the social support system of smoking that gives smokers the implicit right to smoke in shared areas and puts bothered nonsmokers on the defensive.

Advertising↗
PubMed1980

Relationship between X chromosome activation, Barr body frequency and oestrogen receptor status in human breast cancer: a hypothesis.

Current evidence indicates an association between oestrogens, sex chromatin frequency and X chromosome activation in relation to the activity of the enzyme glucose-6-phosphate dehydrogenase. We suggest that a similar association might apply to control the level of oestradiol receptors in breast tumours and present information supporting this hypothesis.

Breast Neoplasms↗