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Biomedical subjects

B May

Publications and source records attributed to B May.

At least 127 records · Page 7Linked to original sources
PubMed1987

Genetic variation between woodchuck populations with high and low prevalence rates of woodchuck hepatitis virus infection.

Woodchuck hepatitis virus (WHV) infection is known to be endemic in areas of the mid-Atlantic states but is apparently absent from populations in New York and much of New England. Blood samples of 40 woodchucks (Marmota monax) from New York and from Delaware were examined by starch gel electrophoresis, and 18 monomorphic and six polymorphic protein-coding genetic systems were identified. Mendelian inheritance of variants of the six polymorphic systems was confirmed in 52 laboratory offspring of the original samples. Average heterozygosity of 0.066 in New York woodchucks and 0.039 in Delaware woodchucks were high values for mammals, although similar to those of other sciurids. Significant heterogeneity between samples from New York and Delaware woodchucks was observed at two loci (peptidase with glycyl leucine-4 and phosphogluconate dehydrogenase), suggesting that these populations were genetically distinct. Whether there are genetically determined differences in response to WHV infection remains to be determined experimentally.

Alleles↗
PubMed1986

Enhanced formation of sulfidopeptide-leukotrienes in ulcerative colitis and Crohn's disease: inhibition by sulfasalazine and 5-aminosalicylic acid.

Release of sulfidopeptide (SP)-leukotrienes (LT) in vitro from normal human colonic mucosa and from mucosal tissue obtained from patients with Crohn's disease (CD) and ulcerative colitis (UC) was investigated. It was found that inflamed mucosal tissue released significantly more SP-LT than normal colonic mucosa both under control conditions and after addition of calcium ionophore A23187. These results indicate the presence of endogenous stimuli as well as an increased responsiveness to an exogenous stimulus of LT formation in the inflamed mucosa. Sulfasalazine (SASP), a drug used in inflammatory bowel diseases, and its active metabolite 5-aminosalicylic acid (5-ASA) were found to inhibit colonic mucosal SP-LT formation, while only 5-ASA inhibited simultaneously synthesis of another arachidonic acid-derived inflammatory mediator, prostaglandin (PG) E2. The results suggest that SP-LT might be important mediators of inflammation in CD and UC.

Aminosalicylic Acids↗
PubMed1986

Sound localization of frequency-modulated sinusoids by Old World monkeys.

Directional hearing acuity, as measured by the minimum audible angle (MAA), was determined in four Old World monkeys, Macaca radiata. The acoustic stimuli were linear changes in frequency (sweeps) for different frequency ranges and sweep rates. The sweeps ranged between 0.5 and 1.3 kHz, at two durations, 100 and 200 ms. In upsweeps which began at 0.5 kHz and were 200 ms in duration, MAA decreased as sweep rate and frequency range increased. These thresholds were compared to MAAs of sweeps which traversed the same range of frequencies but at a different rate, to MAAs of sweeps with identical rates but over different frequency ranges, and to the MAAs of downsweeps. These comparisons indicated that range, and not sweep rate, exerts the greatest effect on the MAA. Interaural phase differences derived from the upper limits of the frequency range are discussed as potential FM localization cues.

Acoustic Stimulation↗
PubMed1986

The role of frequency modulation in the perception of complex stimuli by primates.

Frequency modulation is a common feature of acoustic communication signals, including both human speech and many animal calls. In this study, linear frequency upsweeps were used as simple abstractions of the modulations found in communication signals. Macaque monkeys were trained using positive reinforcement operant conditioning procedures to respond when an ongoing repetitive acoustic signal changed from unmodulated (pure tone) to modulated (sweep). Thresholds for detecting modulation were determined using the psychophysical method of constant stimuli. In the first experiment, it was shown that the monkeys were most sensitive to modulation around a center frequency of 500 Hz. Subsequent experiments were carried out at that frequency, and varied stimulus duration and the frequency relationship between standard and comparison stimuli. The results of these studies indicated that subjects were responding primarily to discrete frequency cues rather than to the presence of modulation. When a premium was placed on attending to modulation by presenting discrete shifts between successive unmodulated stimuli thereby making such shifts an unreliable indicator of the presence of modulation, subjects continued to respond to the presence of the discrete shifts. These results are taken as evidence that the auditory system may deal with frequency modulation near threshold by recoding it as a discrete frequency percept.

Animal Communication↗
PubMed1984

Nonnutritive, thermotactile induction of filial huddling in rat pups.

Norway rat pups, 15 days of age and older, huddle preferentially with members of their own species. This normal filial response can be reassigned, however, by altering the olfactory characteristics of the mother. The present series of experiments was designed to isolate those aspects of maternal stimulation that establish the filial huddling preferences of rat pups. Results of two-choice huddling tests indicated that daily, 4-hr exposures to a perfumed foster dam induced filial preferences for odors associated with maternal care. Similar effects were also achieved with equal amounts of "mere exposure" (familiarization) to odors. Different kinds of odor-experience pairings were evaluated with a within-subject regime of alternating, daily exposures. It was found that preferences induced by maternal contact are stronger than those resulting from familiarization. We rejected the hypothesis that the nursing relationship is a necessary or contributory factor in the establishment of the rat's filial attraction; preferences for odors associated with a nonlactating foster mother were as strong as those derived from maternal contact that included nutritive nursing. Contact interactions with an inanimate, warm, scented tube induced preferences as strong as those induced by maternal care. It was concluded that thermotactile stimulation during mother-young interactions induces olfactory preferences in the weanling rat.

Animals↗
PubMed1984

Patients' perception of dentists' positive and negative attributes.

Earlier studies have shown that dental patients concern themselves with the personality characteristics of their dentists as well as with their professional competence. The present study is part of a wider survey which compared the characteristics of regular and irregular or non-attenders for dental check-ups. In this article patients' characteristics such as sex, age, level of dental anxiety and certain previous dental experiences were related to their perceptions of dentists' positive and negative attributes. The results confirmed previous findings that dentists were seen generally by their patients in a favourable light. Respondents who admitted to higher levels of dental anxiety were more likely to choose more negative attributes and less positive ones than respondents who admitted to lower levels; women, younger subjects and the dentally anxious consistently chose unsympathetic and indifferent as the two top negative characteristics of their dentists.

Adolescent↗
PubMed1984

Some characteristics of regular and irregular attenders for dental check-ups.

Previous surveys of dental care have shown that a substantial proportion of people do not attend dentists regularly. Reasons given for such non-attendance included fear as well as other negative attitudes. Recent studies have attributed fear of dentistry to painful traumatic experiences. The purpose of this study was to compare regular and irregular or non-attenders for dental check-ups on a number of variables, including sex and age, self and family dental anxiety, and previous dental experience. A sample of 531 subjects of both sexes and ranging in age from 16 to 78 years was made available by two large organizations in London and surveyed during office hours. Dental anxiety appeared as a significant factor in non-attendance but there was little support for a simple conditioning hypothesis to explain dental anxiety. Attenders and non-attenders differed markedly in their perception of dentists but there was no difference between the groups as to sex and age.

Adolescent↗
PubMed1983

Theophylline elimination in congestive heart failure.

The elimination of theophylline (clearance, half-life) was investigated in 50 patients with chronic congestive heart failure (grade III/IV) and in 20 controls. The cardiac diagnosis was based on clinical and hemodynamic parameters. Patients with congestion of the liver showed a significant reduction of the theophylline body clearance to 25.7 ml/kg/h +/- 12.1 vs 68.3 ml/kg/h +/- 14.8 in the control group, and a corresponding prolongation of the half-life to 5.7 h +/- 2.5 vs 3.1 h +/- 1.4 in the control group. The main pathogenetic factor is obviously the functioning hepatic tissue, reflected by the galactose elimination capacity (r = 0.666; P less than 0.01; theophylline clearance vs galactose elimination capacity).

Adult↗
PubMed1983

[Histochemical differential diagnosis of intestinal metaplasia of the stomach--new sialic acid stains].

tients with precancerous lesions of the stomach should be followed regularly, since the prognosis of gastric carcinoma is still rather bad. A histochemical method implaying the use of sialic acid is described, which allows differentiation of two forms of intestinal metaplasia of the gastric mucosa, exhibiting possibly different degrees of premalignancy . The two types of metaplastic areas produce, respectively, duodenum-like or colon-like goblet cell mucus. Probably only the latter type is to be classified as a premalignant lesion. This hypothesis is being supported by the fact, that during histochemical work-up of routine biopsy material of gastric mucosa intestinal metaplasia of the colon type was found only in two out of twenty cases of metaplasia.

Biopsy↗