Biomedical subjects

B Alexander

Publications and source records attributed to B Alexander.

214 records · Page 12Linked to original sources

PubMedDate not supplied

The effect of chilli and its pungent ingredient capsaicin on gastrointestinal transit in the rat.

The effect of chilli powder and its pungent ingredient capsaicin on gastrointestinal transit in the rat was studied. Fasted unanaesthetized male Sprague-Dawley rats (n = 144) received by gavage a test meal containing charcoal and cellulose in water or capsaicin solvent plus 51Cr as a radioactive marker. Either 100 or 200 mg of chilli powder (containing 0.13 and 0.26 mg of capsaicin, respectively) or 0.5 or 1 mg of capsaicin were added, the final volume of each meal being 1.5 mL. At 10 and 20 min, animals were killed and the amount of isotope that had left the stomach was measured, together with the distance the charcoal column had travelled along the small intestine. Compared to controls, animals given chilli powder emptied less of their gastric content at 10 and 20 min, an effect partly reproduced by capsaicin. However overall gastric-small intestinal transit was unaffected by chilli powder or capsaicin. Another 12 male Sprague-Dawley rats received, under light ether anaesthesia, on six occasions at 1-2 week intervals, the same six test meals as used in the previous experiment except that charcoal was not used. Total gut transit as measured by the amount of radioactive marker excreted in the stools at 18 and 24 h was unaffected by the use of chilli or capsaicin.

Animals↗

PubMedDate not supplied

Effect of enteral feeding on intestinal epithelial proliferation and fecal bile acid profiles in the rat.

The preservation of colonic mucosal mass requires the presence of feces; thus, colonic hypoplasia develops with enteral feeding. Fermentable soy fiber may maintain fecal bulk and prevent mucosal atrophy. We therefore compared the effects of Enrich (containing soy fiber) with Ensure (fiber-free) on mucosal mass, fecal bile acids, and cell proliferation in the rat. Sprague-Dawley rats (n = 20) were randomized into groups receiving either standard rat food, Enrich, or Ensure. After 4 weeks, rats were weighed and killed at intervals after administration of vincristine sulfate (1 mg/kg intraperitoneally), which was given to induce metaphase arrest within the intestinal crypts and to allow calculation of crypt cell production rate. Fecal free bile acids and neutral steroids were analyzed using gas-liquid chromatography and gas-liquid chromatography mass spectrometry. Nucleic acid concentrations in the small and large intestine and crypt cell production rate in the small bowel were unaffected by diet. In the proximal large bowel, both enteral diets produced a marked reduction in crypt cell production rate to values only 5% to 7.5% of control values (p < .001). In the midcolon of rats fed Ensure, there was a similar reduction, but this hypoplastic effect was completely prevented by Enrich. Without an elevation in the lithocolic acid to deoxycholic acid ratio, secondary bile acid concentrations were increased in rats receiving Enrich (p < .05 to .01) but not in those receiving Ensure. Thus, fermentable soy fiber diets may prevent the midcolonic mucosal hypoplasia induced by enteral feeding.

Animals↗

PubMedDate not supplied

Sedative/hypnotic dependence: patient stabilization, tolerance testing, and withdrawal.

Physical dependence to sedative/hypnotic drugs is not an uncommon clinical problem. The withdrawal syndrome is analogous to alcohol withdrawal, except the duration of the syndrome occurs over a longer period of time with the symptoms being less intense than generally encountered with alcohol. The potential for withdrawal reactions is probably greater for the shorter-acting agents than the longer-acting drugs. Potentially dependent sedative/hypnotic users require stabilization of their symptoms initially, followed by tolerance testing. If tolerant, the patients should be withdrawn using either a long-acting sedative/hypnotic (e.g., diazepam) or phenobarbital. Compared to other benzodiazepines and barbiturates, diazepam appears to be the drug of choice for treating dependent patients. Diazepam is rapidly absorbed and distributed to the brain and therefore useful for stabilization and tolerance testing. It is metabolized on chronic administration to a long-acting metabolite, desmethyldiazepam, which makes the drug ideal for a tapered withdrawal schedule.

Anti-Anxiety Agents↗

PubMedDate not supplied

Blind versus nonblind review: survey of selected medical journals.

The publication of scientific research in medical journals is a lengthy process. Submitted manuscripts are often reviewed by two or more outside reviewers who evaluate each manuscript for publication acceptability. The process of manuscript evaluation by an editor-selected reviewer ("peers" or "referees") is termed "peer review." One issue involving the peer-review process is the use of blind versus nonblind referees. The purpose of this survey was to determine the percentage of a select group of medicine-related journals that blind their reviewers. We surveyed 114 English language journals. Journal editors were sent a survey that asked two questions: (1) are the referees who review your manuscripts blinded to the identity of the authors? and (2) is the editor blinded to the identity of the authors until after the review of the manuscripts is complete? Ninety-six of 114 (84.2 percent) surveys were returned. Ten journals published invited manuscripts only and were excluded from the survey. Only 18.6 percent (16 of 86) of the journals currently blind referees. None of the journals' editors were blind to the identity of the manuscripts' authors.

Medicine↗

PubMedDate not supplied

Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) as a tool for differentiation of P2Y2-receptor-mediated vasorelaxation in guinea pig aorta.

The action of the putative P2Y1-receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) was studied in guinea pig aorta for potential use in the differentiation between P2Y1 and P2Y2 purine receptors. Concentration-effect curves to 2-methylthioadenosine triphosphate (2MeSATP) and uridine triphosphate (UTP), agonists at P2Y1- and P2Y2-receptor sites, respectively, and the common agonist adenosine triphosphate (ATP) were constructed in guinea pig aortic ring preparations with the tone raised by 5 microM of noradrenaline. A ranked order of agonist potency of 2MeSATP > ATP > UTP resulted from the construction of concentration response curves to vasorelaxation of the agonists. Deendothelialization virtually abolished vasorelaxation to UTP but made no significant difference to 2MeSATP-induced responses. PPADS exhibited noncompetitive inhibition at P2Y1-receptor sites by reducing the maximal response to 2MeSATP, although a trend towards a right shift of the concentration-effect curves was observed. In total contrast, PPADS enhanced P2Y2-mediated vasorelaxation to UTP by shifting the concentration-effect curves to the left and increasing maximal responses. Thus, PPADS is a noncompetitive antagonist at P2Y1 receptors but enhances responses, at least to UTP, at P2Y2 receptors in guinea pig aorta via a hitherto unknown mechanism. Thus, PPADS is a potentially useful substance that may be used for differentiation between P2Y1 and P2Y2 receptors in the guinea pig aorta.

Adenosine Triphosphate↗

PubMedDate not supplied

Ecology of phlebotomine sand flies (Diptera: Psychodidae) in a focus of Leishmania (Viannia) braziliensis in northeastern Colombia.

The phlebotomine sand fly fauna of two coffee plantations in a Leishmania-endemic area of Norte de Santander, Colombia was studied. Regular insect collections using a variety of methods were made for three and a half years. Information was obtained on diurnal resting sites, host range and seasonal abundance for 17 species, of which five (Lutzomyia spinicrassa, Lu. serrana, Lu. shannoni, Lu. ovallesi and Lu. gomezi) were far more numerous than the others, anthropophilic and present throughout the year. The behaviour of these and the remaining 12 species is discussed in relation to their potential role in transmission of Leishmania (Viannia) braziliensis in the area.

Adolescent↗

PubMedDate not supplied

Dispersal of phlebotomine sand flies (Diptera: Psychodidae) in a Colombian focus of Leishmania (Viannia) braziliensis.

Dispersal of five species of phlebotomine sand flies was studied in a coffee plantation near Arboledas, Colombia, by mark-release-recapture studies using fluorescent powders. The estimated recapture rate for males of Lutzomyia shannoni marked and released during the day was 28.1%, significantly higher than that for all other species (p < 0.05). Recapture rate of female Lu. shannoni was 9.5%, and no females of the other four species were recovered. This suggests either that Lu. shannoni is a more sedentary species than the others, or that the large trees on which these insects were captured and recaptured function as foci of lekking behaviour in males. The high recapture rates of females of this species may indicate that oviposition occurs in close proximity to the bases of these trees. Although most marked sand flies were recaptured within 200 m of their release point, a single female Lu. gomezi was recovered 960 m away 36 h after release. This suggests that the dispersal capacity of Lutzomyia species may be greater than has been thought, an important consideration in future control programs directed against these insects in Leishmania-endemic areas.

Animals↗

PubMedDate not supplied

An attempt to control Phlebotomine sand flies (Diptera: Psychodidae) by residual spraying with deltamethrin in a Colombian village.

An attempt was made to control phlebotomine sand flies biting indoors in a rural community near Cali, Colombia, using the residual insecticide "K-Othrine" (deltamethrin) sprayed on the inside walls of houses. Twelve houses were divided into matched pairs based on physical characteristics, one house in each pair being left untreated while the inside walls of the other were sprayed with 1% deltamethrin at a concentration of 500 mg a.i./m2. Sand flies were sampled each week using protected human bait and sticky trap collections for four months after spraying. The number of sand flies (Lutzomyia youngi) collected on sticky traps was significantly lower (P = 0.004) in the untreated houses than in the treated ones with which they were matched. This difference was not significant for L. columbiana; the other anthropophilic species were not present in large numbers. The numbers collected on human bait in treated and untreated houses were not significantly different for either species. Activity of the insecticide as determined by contact bioassays remained high throughout the study and failure to control the insects was attributed to two factors: the tendency of sand flies to bite before making contact with the insecticide and the fact that the number of sand flies that entered houses represented a relatively small proportion of the population in the wooded areas surrounding the settlement in the study.

Animals↗

PubMedDate not supplied

Man-biting activity of Anopheles (Nyssorhynchus) albimanus and An. (Kerteszia) neivai (Diptera: Culicidae) in the Pacific lowlands of Colombia.

The daily man-biting activity of Anopheles (Nyssorhynchus) albimanus and An. (Kerteszia) neivai was determined in four ecologically distinct settlements of the Naya River, Department of Valle, Colombia. Differences were found among the settlements with respect to the mosquito species present, intradomiciliary and extradomiciliary biting activity and population densities.

Animals↗

PubMedDate not supplied

Genetic variation among natural and laboratory colony populations of Lutzomyia longipalpis (Lutz & Neiva, 1912)(Diptera: Psychodidae) from Colombia.

Genetic diversity among three field populations of Lutzomyia longipalpis in Colombia was studied using isozyme analysis. Study sites were as much as 598 km apart and included populations separated by the eastern Cordillera of the Andes. Genetic variability among populations, estimated by heterozygosity, was within values typical for insects in general (8.1%). Heterozygosity for field populations were compared with a laboratory colony from Colombia (Melgar colony) and were only slightly lower. These results suggest that establishment and long term maintenance of the Melgar colony has had little effect on the level of isozyme variability it carries. Genetic divergences between populations was evaluated using estimates of genetic distance. Genetic divergence among the three field populations was low (D = 0.021), suggesting they represent local populations within a single species. Genetic distance between field populations and the Melgar colony was also low (D = 0.016), suggesting that this colony population does not depart significantly from natural populations. Finally, comparisons were made between Colombian populations and colonies from Brazil and Costa Rica. Genetic distance values were high between Colombian and both Brazil and Costa Rica colony populations (D = 0.199 and 0.098 respectively) providing additional support for our earlier report that populations from the three countries represent distinct species.

Animals↗

PubMedDate not supplied

Two prospective dosing methods for nortriptyline.

This study compared two prospective pharmacokinetic dosing methods to predict steady-state concentrations of nortriptyline. One method required multiple determinations of the nortriptyline plasma concentration to estimate the drug's steady-state concentration. The second method required a single nortriptyline concentration drawn at a fixed time, preferably 36 hours, following a nortriptyline test dose. The 36-hour nortriptyline plasma concentrations (NTP 36h) were substituted into the straight-line equation of Cssav = 17.2 + 3.74 (NTP 36h), where Cssav is the average steady-state concentration for a 100 mg/day dose of nortriptyline. No differences were noted between the observed steady-state nortriptyline concentration of 121 +/- 19 ng/ml, the 36-hour single-point prediction mean concentration of 121 +/- 21 ng/ml, or the multiple-point prediction mean concentration of 122 +/- 19 ng/ml. Because of the similar findings between the two methods, the clinical advantages and disadvantages of each kinetic approach are discussed to put these prospective dosing protocols into their proper perspective.

Adult↗

PubMedDate not supplied

Subjective symptoms, blood glucose estimation, and blood glucose concentrations in adolescents with diabetes.

Twenty-five adolescent campers with insulin-dependent diabetes mellitus (IDDM) completed a Symptom Rating Checklist and estimated their blood glucose (BG) immediately before having their BG assessed four times daily for 11 days. Consistent relationships between BG and symptoms were not identified when the data were analyzed for the group as a whole. However, when each camper's data were analyzed separately, 23 of the 25 adolescents had at least one significant glycemia-symptom (G-S) correlation. Each camper seemed to have a unique G-S pattern; only one symptom (hungry) was significantly related to BG for more than half of the youngsters studied. Almost all of the significant G-S correlations were indicative of low rather than high BG. However, when asked, few campers were able to accurately identify which symptoms were reliably associated with low or high BG. In this study, different measures of BG estimation error led to different results. The percent of estimates +/- 20% of the actual BG value (55% in this study) was strongly influenced by the actual BG reading because higher BG values have larger accuracy ranges than lower BG concentrations. When estimated BG was simply subtracted from actual BG, under- and overestimates canceled each other out, resulting in an unusually small estimated error (5 mg/dl in this investigation). The absolute difference score ignores the direction of estimation error, but may more accurately reflect patients' average estimation error (68 mg/dl in this study). When actual and estimated BG values were correlated for the group as a whole, the patients appeared to be highly accurate at estimating BG (r = .93, P less than .0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied