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Biomedical subjects

S L White

Publications and source records attributed to S L White.

119 records · Page 7Linked to original sources

An assessment of the effects of swainsonine on survival of mice injected with B16-F10 melanoma cells.

Systemic administration of swainsonine, an indolizidine alkaloid, inhibits the experimental metastasis of B16-F10 murine melanoma cells. This activity can be attributed primarily to swainsonine-mediated enhancement of host natural killer cell activity. As one next step towards investigating the potential therapeutic utility of this drug, its efficacy in enhancing host survival in the same B16-F10 model system has been assessed. In studies employing intravenously injected tumor cells, pretreatment of mice with swainsonine-containing drinking water provided a reproducible protective effect for the host. This prolongation of survival was substantially enhanced when swainsonine was administered in combination with either of two other immunomodulators, polyinosinic: cytidylic acid (poly-IC) or interleukin-2. In studies in which combinations of these agents were administered after intravenous injection of tumor cells, or after subcutaneous implantation, a greatly reduced effect on host survival was observed. However, when used in combination with cyclophosphamide (to block the effects of suppressor T cells), swainsonine did increase mean survival time. The implications of these results for the use of swainsonine in treatment of metastatic or localized disease, together with its potential mechanism(s) of action, are discussed.

Alkaloids↗

The "Z" osteotomy versus the Kalish osteotomy for the correction of hallux abducto valgus deformities: a retrospective analysis.

A retrospective analysis of hallux abducto valgus surgery performed between 1990 and 1995 where the "Z" osteotomy and Kalish osteotomy were utilized was performed. Objective and subjective data were collected to determine the effectiveness of the Z osteotomy versus the Kalish osteotomy. Twenty cases of hallux abducto valgus where the Z osteotomy was utilized were evaluated on the basis of intermetatarsal angle correction and alleviation of preoperative symptoms. The same evaluation was performed on 21 cases where the Kalish osteotomy was utilized. There did not appear to be an appreciable difference in intermetatarsal angle correction between the two osteotomies; however, the Kalish osteotomy did alleviate preoperative symptoms to a greater degree compared with the Z osteotomy.

Adolescent↗

High-energy bilateral talar neck fractures secondary to motocross injury.

The authors present a case of bilateral Hawkins type II talar neck fractures sustained during a motocross race in a 23 year old man. Due to the complexity of the injuries, open reduction with internal fixation and primary subtalar joint arthrodesis was performed bilaterally. This is one of the few cases of bilateral talar neck fractures reported in the literature in the past 15 years and one of the first utilizing open reduction and internal fixation with concomitant subtalar joint arthrodesis as a primary treatment.

Adult↗

Quantitation of glandular gastric changes in rats given a proton pump inhibitor for 3 months with emphasis on sampling scheme selection.

Proton pump inhibitors and H2-receptor antagonists suppress gastric acid secretion and secondarily induce hypergastrinemia. Sustained hypergastrinemia has a trophic effect on stomach fundic mucosa, including enterochromaffin-like (ECL) cell hypertrophy and hyperplasia. Histomorphometric quantitation of the pharmacologic gastric effects was conducted on 10 male and 10 female rats treated orally with LY307640 sodium, a proton pump inhibitor, at daily doses of 25, 60, 130, or 300 mg/kg for 3 mo. Histologic sections of glandular stomach, stained for chromogranin A, were evaluated by image analysis to determine stomach mucosal thickness, mucosal and nonmucosal (submucosa and muscularis) area, gastric glandular area, ECL cell number/area and cross-sectional area. Total mucosal and nonmucosal tissue volumes per animal were derived from glandular stomach volumetric and area data. Daily oral doses of compound LY307640 sodium caused slight to moderate dose-related mucosal hypertrophy and ECL cell hypertrophy and hyperplasia in all treatment groups as compared with controls. All observed effects were prominent in both sexes but were generally greater in females. The morphometric sampling schemes were explored to optimize the data collection efficiency for future studies. A comparison between the sampling schemes used in this study and alternative schemes was conducted by estimating the probability of detecting a specific percentage of change between the male control and high-dose groups based on Tukey's trend test. The sampling scheme analysis indicated that mucosal thickness and mass had been oversampled. ECL cell density quantitation efficiency would have been increased by sampling the basal mucosa only for short-term studies. The ECL cell size sampling scheme was deemed appropriate for this type of study.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Spatial and time distribution of dairy cattle excreta in an intensive pasture system.

This study determined distribution of feces and urine from 36 lactating dairy cattle (Bos taurus) managed in a rotationally grazed 0.74-ha endophyte-free tall fescue (Festuca arundinacea Schreb.)-white clover (Trifolium repens L.) pasture. Cows were observed for 24 h five times from July 1997 to April 1998, and for 13.5 h in September 1997. During each 24-h observation period, the first grazing period (12 h) used 54% of the paddock and the second grazing period (8 h) used the entire paddock. Times and locations of all defecations and urinations from a subgroup of eight cows, observed while in the pasture, feed area, milking parlor, or in transit were recorded during the observation periods listed above and another time in May 1997. On pasture, all defecations and urinations were surveyed and mapped for all 36 cows. Feces and urine from six observation periods covered an estimated 10% of the paddock area in one year. Within 30 m of the water tank, concentrations of feces and urine from three warm-season observations were significantly greater than concentrations during three cool-season observations. Percentages of defecations and urinations on the pasture, feeding, and milking areas were highly correlated (r > 0.90) with time spent in those areas. Pasture-based systems could reduce manure handling and storage requirements proportional to the time cattle are on pastures. Manure on the pasture was evenly distributed, except around the water tank during warm-weather grazings. Results indicate that pasture-based dairy systems may require smaller, less-expensive manure management systems compared with confinement dairy farms.

Agriculture↗

Minerals in hair, serum, and urine of healthy and anemic black children.

Hair mineral analysis can be used as a reliable screening test for heavy metals, but it is not an established method for defining nutritional and disease states. Wide variation in test results is a major problem in utilizing the technique for clinical purposes. Better reference values are needed, especially for children, as well as information about how hair mineral values correlate with body fluid values. A total of 48 black children were studied. Of these, 20 were normal children, ages 1 to 17; 12 were normal infants, ages 5 weeks to 12 months; 3 were children with iron overload; 7 had iron deficiency anemia; and 6 had thalassemia trait. There were in all 17 boys and 31 girls. The distribution of 15 minerals in hair, serum, and urine samples was determined by energy dispersive X-ray fluorescence. Mineral concentrations from the normal children were compared with concentrations obtained from the children with iron overload, iron deficiency anemia, and thalassemia trait. Statistical analysis revealed no significant differences among any of the groups. Mineral concentrations from the normal infants and children may be useful as reference values. The analysis of hair iron as a valid screening test for body iron status in children is not supported by our data.

Adolescent↗

Promoting healthy diets and active lives to hard-to-reach groups: market research study.

Continued progress over the next decade in reducing premature morbidity and mortality from chronic disease will require that health communication efforts target a significant proportion of the American public that has not been influenced by the health promotion efforts of the 1980s. Focus groups conducted with members of the hard-to-reach American public showed that while being healthy seemed to be important to participants, and they were generally aware of what to do to stay healthy, they had a different operational definition of health than that used in health promotion programs. Participants seemed to believe that better health behaviors would build their resistance to acute illnesses, that is, keep them healthy, but that chronic diseases, such as cancer and diabetes, were due to fate and heredity and beyond their individual control. The focus group results show that participants had not made the link between chronic disease prevention and the importance of diet, exercise, and weight control. Although most of them seemed to express a genuine interest in "doing better," they were not able to supply more than superficial examples of how such changes might be made. Surprisingly, there were more similarities than differences in participants' attitudes and beliefs, with the similarities cutting across boundaries of race-ethnicity, age, and sex. Interest in changing behaviors was only slightly more pronounced among female rather than male, and older rather than younger, participants. However, there was not much evidence from the participants that they were actively seeking health information or trying to reconcile conflicting knowledge and beliefs.

Adult↗

A preliminary pharmacokinetic evaluation of the antimetastatic immunomodulator swainsonine: clinical and toxic implications.

The pharmacokinetics of swainsonine (SW) was investigated in mice after intravenous administration of 3 micrograms/ml. The time course of SW blood levels followed a three-compartment open pharmacokinetic model which consisted of biphasic distribution, and a rapid elimination phase (terminal half-life, 31.6 min). After completion of the distribution, SW was widely distributed to the extravascular space (Vss, 22ml; Vd, 33ml). Free fractions of this substance were indistinguishable from unity, indicating little or no protein binding. The rate-limiting step in the elimination of SW from the body appears to be the slow return from the deep compartment into the central one. Accordingly, SW blood levels may be low and yet significant amounts of this agent may be present in different body organs and tissues. A comparison of SW tissue levels indicates that the highest amounts appeared in the bladder, kidney, and thymus, (3.8 0.5, and 2.2 nmoles/g wet wt) with the lowest levels consistently appearing in the brain (< 0.1 nmoles/g wet wt). Hence, this study suggest that: 1) SW has high affinity for the thymus, which is in part consistent with its previously published immunomodulatory action; 2) SW should be infused for at least 2 1/2 hrs for its concentration to approach a plateau (this is based on the short half-life of SW and its time to steady state); and 3) CNS toxicity may be dose-limiting and not be present at SW levels preventing metastasis.

Animals↗