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Biomedical subjects

S M Wagner

Publications and source records attributed to S M Wagner.

15 recordsLinked to original sources
PubMed1997

Predicting rodent carcinogenicity from mutagenic potency measured in the Ames Salmonella assay.

Many in vitro tests have been developed to identify chemicals that can damage cellular DNA or cause mutations, and secondarily to identify potential carcinogens. The test receiving by far the most use and attention has been the Salmonella (SAL) mutagenesis test developed by Ames and colleagues [(1973): Proc Natl Acad Sci USA 70:2281-2285; (1975): Mutat Res 31:347-364], because of its initial promise of high qualitative (YES/NO) predictivity for cancer in rodents and, by extension, in humans. In addition to the initial reports of high qualitative predictivity, there was also an early report by Meselson and Russell [in Hiatt HH et al (1977): "Origins of Human Cancer, Book C: Human Risk Assessment," pp 1473-1481] of a quantitative relationship between mutagenic potency measured in SAL and carcinogenic potency measured in rodents, for a small number of chemicals. However, other reports using larger numbers of chemicals have found only very weak correlations. The primary purpose of this study was to determine whether mutagenic potency, as measured in a number of different ways, could be used to improve predictivity of carcinogenicity, either qualitatively or quantitatively. To this end, eight measures of SAL mutagenic potency were used. This study firmly establishes that the predictive relationship between mutagenic potency in SAL and rodent carcinogenicity is, at best, weak. When predicting qualitative carcinogenicity, only qualitative mutagenicity is useful; none of the quantitative measures of potency considered improves the carcinogenicity prediction. In fact, when qualitative mutagenicity is forced out of the model, the quantitative measures are still not predictive of carcinogenicity. When predicting quantitative carcinogenicity, several possible methods were considered for summarizing potency over all experiments; however, in all cases, the relationship between mutagenic potency predictors and quantitative carcinogenicity is very weak.

Animals↗
PubMed1995

Phenotypic modulation of gonococcal lipooligosaccharide in acidic and alkaline culture.

Neisseria gonorrhoeae infects a diverse array of niches in its human host, which expose the organism to dramatic variations in pH. We examined growth and lipooligosaccharide expression of two gonococcal strains in liquid and solid cultures under acidic, neutral, and alkaline conditions. Growth rates in broth were similar under the three conditions, and the pH remained fairly constant throughout the growth cycle. Altered lipooligosaccharide expression at the different pHs was noted in both plate- and broth-grown organisms.

Bacterial Proteins↗
PubMed1989

Intraoperative endoscopic localization of jejunal angiodysplasia as a source of massive rectal bleeding.

Gastrointestinal bleeding from an unknown source presents a difficult diagnostic problem. Despite the number of diagnostic tests available, there are occasions when gastrointestinal bleeding requires operative intervention without preoperative localization of the bleeding site. This situation was encountered in the case described, in which a preoperative bleeding scan could only suggest that the small bowel in the left upper quadrant was the source of the bleeding. Intraoperative small-bowel endoscopy was important in confirming the diagnosis.

Endoscopy↗
PubMed1989

Pancreatography after recovery from massive pancreatic necrosis.

Massive retroperitoneal necrosis may follow life-threatening acute pancreatitis. At delayed operation, the surgeon may not be able to delineate dead pancreas from dead adipose tissue. The question arises: has "gloved hand" debridement resulted in pancreatectomy? The histologists report only "necrotic debris, of uncertain origin." To obtain objective data, pancreatography was performed in 13 patients, 10 weeks to 23 months after onset of massive pancreatic necrosis. Each patient had required delayed laparotomy for debridement and external drainage at some earlier stage of their illness. Pancreatography was correlated with the clinical assessment of diabetes and steatorrhea. Except in specific cases involving internal fistulae, pancreatography has not been previously reported in such patients. The results demonstrate that the main pancreatic duct usually maintained its normal length and configuration. Necrosis or stricture of the main duct, if it occurred, was more likely to be followed by diabetes. Steatorrhea was clinically detected in a single patient only. The necrotic tissue, up to several kilograms in wet weight, is largely dead adipose tissue. The pancreas, especially its head, is resistant to necrosis, much more resistant than is the retroperitoneal fat.

Acute Disease↗
PubMed1989

Giving credit where money is due. How to get a charge out of patients.

It took a while, but hospitals are finally catching on to what major retailers discovered more than 30 years ago: Americans love to charge. When presented with a bill for socks at Bloomingdale's or lunch at Lutece, they pull out the plastic. Now, many can do roughly the same thing when presented with a hospital bill for treatment of a herniated disk. To shore up financial reserves, reduce bad debt, and increase cash flow, hospitals are turning to revolving consumer credit plans to help patients pay the self-pay portions of their hospital bills. Consumers like it because it gives them an affordable monthly payment over a long term, a good credit report reference, and a means to satisfy the self-pay obligation in a dignified, responsible way. And it seems to be working. A study of a 43-hospital chain that used a revolving charge plan for patients for a 23-month period showed that finance charges to patients more than covered the cost of the program; bad debts for receivables financed were cut to 29 percent, a 44.2 percent reduction; and consumers accepted the program because it was familiar, legal, binding, and, most important, affordable.

Accounting↗
PubMed1985

Odynophagia in patients with malignant disorders.

The differential diagnosis of odynophagia in patients with malignant disorders usually includes esophagitis due to herpes, Candida, or gastroesophageal reflux. Two cases and a review of the literature are presented that illustrate that leukemic infiltration of the esophagus and necrosis of the esophageal mucosa following chemotherapy should be considered in addition to the more commonly recognized causes. Esophagoscopy with biopsy and brushing for fungal stains is essential for the correct diagnosis since the various causes for odynophagia may be clinically and radiographically indistinguishable.

Aged↗
PubMed1978

Effects of caffeine and coffee on fluid transport in the small intestine.

Although caffeine is known to stimulate small intestinal water secretion in man, no available studies have examined the effect of coffee on small intestinal fluid transport. We have studied the effect of both coffee and caffeine on jejunal sodium and water transport by the triple lumen intestinal perfusion technique. Both caffeine and coffee solutions had equivalent caffeine concentrations, approximating the caffeine concentration in one cup of coffee. Control and coffee perfusion resulted in net absorption of 0.9 +/- 0.2 and 1.1 +/- 0.3 ml per min per 30 cm, respectively, whereas caffeine perfusion resulted in net water secretion of 2.4 +/- 0.4 ml per min per 30 cm (P less than 0.02). Net sodium absorption was observed with control and coffee solutions with a mean absorption of 190 +/- 32 and 184 +/- 40 muEq per min per 30 cm, respectively. Net sodium secretion of 334 +/- 25 muEq er min per 30 cm was observed during caffeine perfusion (P less than 0.02). We conclude that coffee perfusion has no significant effect on sodium and water transport in the jejunum in spite of the marked secretory effects of caffeine solutions. The results of this study yield further support to the suggestion that the effects of caffeine may not be similar to the effects of caffeine-containing compounds such as coffee.

Adult↗
PubMed1975

Enhancement of filterability of sickle cells by cyanate: an effect independent of oxygen saturation.

Filterability and morphology of cyanate-treated sickle cells were compared to those of untreated cells at equal oxygen saturations to determine whether carbamylation inhibited sickling by an effect other than by its alteration of the oxygen dissociation curve. Morphology of treated and untreated cells was not significantly different at all levels of oxygen saturation examined. Filterability, on the other hand, was improved significantly by carbamylation. This latter finding indicates that carbamylation enhances deformability of sickle cells by a mechanism(s) in addition to its effect on red cell oxygen saturation. This mechanism(s) may account for the clinical benefit of cyanate therapy with doses which do not significantly affect the oxygen dissociation curve.

Adenosine Triphosphate↗