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Biomedical subjects

G F Smith

Publications and source records attributed to G F Smith.

At least 55 records · Page 3Linked to original sources
PubMed1988

Extramammary Paget's disease: an annotated review.

The incidence, clinical features, histogenesis, and treatment of extramammary Paget's disease (EMPD) are reviewed. This unusual skin lesion is associated with an underlying adnexal neoplasm in about 50% of cases. Also, the incidence of distant organ malignancies of EMPD is higher than expected by chance. Even in the absence of a recognizable underlying cancer, EMPD may occasionally produce distant metastases, indicating the malignant potential of this condition. Histochemical, immunohistological, and lectin binding studies demonstrate that the cell of origin of EMPD is the exocrine cell of sweat glands. Although EMPD may arise from eccrine cells, derivation from apocrine cells appears more common. The treatment of the primary lesion, by wide margin excision, is fraught by a high recurrence rate. Chemosurgery may reduce local relapse of EMPD. The value of adjuvant radiation therapy is unestablished. Chemotherapy has induced remission in 2 cases of advanced EMPD and needs testing in clinical trials.

Diagnosis, Differential↗
PubMed1986

Metastatic spread of the PAIII prostatic adenocarcinoma after implantation in the tail of the rat.

The spontaneous metastatic spread of a suspension of PAIII prostatic adenocarcinoma cells from the tail site of implantation was analyzed over a period of 5 weeks in male Lobund-Wistar (LW) rats. Following subcutaneous injection of the PAIII cells, the tumor metastasized through the primary lymphatic drainage. PAIII microfoci were evident in the gluteal and iliac lymph nodes prior to colonization of the lungs. Growth of the primary tumor was evidenced by significant weight differences of the tails of PAIII-bearing and control rats 1 week after tumor implantation. Time-dependent sequential spread of the adenocarcinoma was quantitated. Significant differences were noted between PAIII-bearing and control animals with respect to the gluteal lymph node weights (+2 weeks), iliac lymph node weights (+3 weeks), dry lung weights, and lung colony numbers (+4 weeks) after tumor implantation. During the course of these studies, the whole blood prothrombin, activated partial thromboplastin, and recalcification times for the PAIII-bearing animals were similar to those of the control group. These findings indicate that there were no gross changes in systemic blood coagulation accompanying the metastasis of PAIII cells from the primary tumor. The tumor in LW rats produced a consistent pattern of growth and metastasis that is suitable for quantitation. The PAIII prostatic adenocarcinoma is a sensitive and reproducible system that may be useful to evaluate potential antimetastatic and cytotoxic agents for the treatment of hormone-insensitive prostatic cancer.

Adenocarcinoma↗
PubMed1986

Inhibitory effect of warfarin on the metastasis of the PAIII prostatic adenocarcinoma in the rat.

The PAIII rodent metastatic prostatic adenocarcinoma model was employed to evaluate the effects of dietary warfarin, a prototypic antagonist of thrombin generation on the lymphatic and pulmonary metastases of the tumor from the tail site of subcutaneous transplantation in male Lobund Wistar (LW) rats. In addition, the anticoagulant effects of warfarin were determined in the same animals. Warfarin, administered in the diet at concentrations equivalent to 0.063, 0.125 or 0.250 mg./kg. b.w. for 30 days had no effect on final body weight, gluteal or iliac lymph node weights. Significant (p less than 0.05) dose-dependent extensions of whole blood prothrombin (WBPT), activated partial thromboplastin (WBAPTT) and clotting times (WBCT) over control values were observed with warfarin treatment. Preliminary studies demonstrated that the 0.500 mg./kg. dose produced 50 per cent mortality at +14 days. Warfarin produced significant (p less than 0.05) dose-dependent decreases in the number of PAIII pulmonary metastases as indicated by reductions in dry lung weights and lung colony numbers when compared to untreated tumor-bearing controls. While the therapeutic index of warfarin is a limiting factor in clinical use as an antimetastatic agent, these results suggest that compounds capable of altering hemostatic mechanisms may be potential inhibitors of tumor metastasis. The PAIII prostatic adenocarcinoma model may be a useful system to quantitatively evaluate potential antimetastatic and cytotoxic agents.

Adenocarcinoma↗
PubMed1984

The effects of 1-methyl-5-thiotetrazole in a rat liver vitamin K-dependent carboxylase assay.

1-Methyl-5-thiotetrazole (NMTT), a metabolite of moxalactam (MoxamR), was studied for its potential inhibition of vitamin K-dependent carboxylation. The assay system utilized a detergent solubilized rat liver microsomal preparation. Vitamin K1H2 was artificially produced in situ by the NADH-dependent reduction of exogenous phylloquinone and the resultant carboxylation monitored by 14CO2 incorporation into a soluble peptide substrate. Warfarin, used as a reference inhibitor, gave results expected from the literature - 50% inhibition at a pharmacologically excessive level of 1.0 mM. Carboxylation was unaffected by 1.0 mM NMTT and was marginally (0-14%) diminished by 5.0 mM NMTT. Carboxylation was 25% diminished at 10.0 mM NMTT, a concentration far above that achieved in human testing of moxalactam. When NMTT was pre-incubated with the liver microsomal carboxylase enzyme preparation, 10.0 mM NMTT again caused merely a 25% diminution of carboxylation in the assay. These results do not support a role for NMTT as an inhibition of Vitamin K-dependent carboxylation which would produce pharmacological side effects during moxalactam therapy. During these studies it was found that dramatic consumption of NADH occurs in the presence of liver microsomal preparations (independent of vitamin K and of NMTT) and that NMTT effects on these processes may explain the small carboxylation diminution observed at 10.0 nM NMTT in the carboxylase assay.

Animals↗
PubMed1984

Angiodysplasia of the colon. A review of 17 cases.

From October 1977 through December 1982, 24 patients with lower gastrointestinal tract hemorrhage were diagnosed by visceral angiography as having angiodysplasia of the colon. Seventeen of them underwent surgery for definitive treatment of their hemorrhage. Five patients had lesions on both sides of the colon, and five had coagulation disorders. Three of the 17 patients with lesions isolated to the cecum underwent right hemicolectomy. The rest underwent subtotal colectomy with ileoproctostomy. No patient had recurrent or persistent bleeding. There were three deaths in the subtotal colectomy group (21%); coagulation disorders contributed to two of them. Subtotal colectomy was universally successful in controlling bleeding but had a significant mortality in these elderly patients. Coagulopathy, especially platelet disorders, was a significant risk factor with this diagnosis. A coagulation panel, including platelet function, should be part of the preoperative assessment.

Aged↗
PubMed1984

Use of megadoses of vitamins with minerals in Down syndrome.

To evaluate the effects of megadoses of vitamins with minerals on the cognitive intelligence of children with Down syndrome, a two-group double-blind clinical trial was carried out with 56 school-aged children with Down syndrome. Children were evaluated at baseline, 4 months, and 8 months with a battery of standard psychologic tests, physical examinations, and blood tests. The two groups, which were well-matched is cognitive intelligence and other important subject characteristics at baseline, were not significantly different in intelligence and other test scores at the 4- or 8-month test periods. The particular megadoses of vitamins with minerals used in the study did not produce increased intelligence in the study population.

Adolescent↗
PubMed1981

Superoxide dismutase and glutathione peroxidase abnormalities in erythrocytes and lymphoid cells in Down syndrome.

After validating a superoxide dismutase (SOD) assay, this enzyme was measured together with a large series of cell age sensitive marker enzymes, in the erythrocytes of 24 persons with the 24 persons without Down syndrome. In addition to the expected elevation of SOD-1, significant elevations of erythrocyte glutathione peroxidase (GSHPxase) and phosphofructokinase activities were found in Down syndrome. None of these changes could be accounted for by a decreased mean red cell age. The elevation of GSHPxase was also found in lymphoid cells but does not represent a gene dose effect at this locus. Rather, the elevation of GSHPxase in Down syndrome may represent an adaptive metabolic response to the increased hydrogen peroxide produced by the triplicated SOD-1 gene dose in trisomy 21. Since tissue GSHPxase activity can be manipulated via the enzyme's obligatory selenium co-factor, our data suggest the need to establish blood and tissue levels of selenium in Down syndrome and to correlate selenium, GSHPxase and phenotypic dysfunction in this disorder.

Adult↗