Cytochrome P450 1B1 expression in rat esophageal tumorigenesis promoted by gastric and duodenal reflux.

Cytochrome P450 1B1 (CYP1B1) mRNA is constitutively expressed in most normal extra-hepatic tissues; however the protein is not detectable in these tissues but is expressed in a wide variety of tumors. CYP1B1 is responsible for the activation of a number of carcinogens present in tobacco smoke and food. A surgical model of rat esophageal tumorigenesis, promoted by gastric or duodenal reflux was used to determine CYP1B1 expression in premalignant esophageal tissue. Immunohistochemistry was performed using a modified amplified fluorescein tyramide protocol. CYP1B1 was not observed in normal esophageal mucosa, submucosa, or muscularis mucosa. Animals exposed to gastric reflux developed mild hyperplasia. Varying degrees of hyperplasia were observed in the duodenal reflux group. All regions of hyperplasia showed moderate or strong CYP1B1 immunoreactivity. Duodenal reflux induced a small number of premalignant changes: immunoreactivity was absent from the epithelium of squamous dysplasia (0/10), Barrett's esophagus (0/7), and majority of dysplastic Barrett's esophagus (1/4). Moderate or strong immunoreactivity was observed in the majority (7/8) of squamous cell carcinomas (SCCs) in situ. Immunoreactivity was also observed in the lamina propria and submucosa in association with inflammation, regardless of the severity of inflammation. The expression of CYP1B1 in hyperplasia, SCCs in situ, or in association with inflammation may increase the production of carcinogenic metabolites, which may promote esophageal tumorigenesis.

Mediastinitis: a life-threatening complication of acute tonsillitis.

Acute tonsillitis is a common condition and usually runs a benign course. However life-threatening complications do still occur, even in this postantibiotic era. Infection can spread downwards into the mediastinum through the anatomic cervical spaces, causing widespread cellulitis, necrosis, abscess formation and sepsis. We present a case of descending mediastinitis in an 18-year-old woman, arising from her first episode of tonsillitis and treated successfully by surgical drainage. We believe that an awareness of this complication, early diagnosis using computed tomography scanning, and prompt, adequate surgical drainage will reduce morbidity and mortality.

The brain decade in debate: IV. Chronobiology.

The present article is the adapted version of an electronic symposium organized by the Brazilian Society of Neuroscience and Behavior (SBNeC) which took place on June 14, 2000. The text is divided into three sections: I. The main issues, II. Chronodrugs, and III. Methods. The first section is dedicated to the perspectives of chronobiology for the next decade, with opinions about the trends of future research being emitted and discussed. The second section deals mostly with drugs acting or potentially acting on the organism's timing systems. In the third section there are considerations about relevant methodological issues concerning data analysis.

The brain decade in debate: IV. Chronobiology

The present article is the adapted version of an electronic symposium organized by the Brazilian Society of Neuroscience and Behavior (SBNeC) which took place on June 14, 2000. The text is divided into three sections: I. The main issues, II. Chronodrugs, and III. Methods. The first section is dedicated to the perspectives of chronobiology for the next decade, with opinions about the trends of future research being emitted and discussed. The second section deals mostly with drugs acting or potentially acting on the organism's timing systems. In the third section there are considerations about relevant methodological issues concerning data analysis

The common marmoset: a new world primate species with limited Mhc class II variability.

The common marmoset (Callithrix jacchus) is a New World primate species that is highly susceptible to fatal infections caused by various strains of bacteria. We present here a first step in the molecular characterization of the common marmoset's Mhc class II genes by nucleotide sequence analysis of the polymorphic exon 2 segments. For this study, genetic material was obtained from animals bred in captivity as well as in the wild. The results demonstrate that the common marmoset has, like other primates, apparently functional Mhc-DR and -DQ regions, but the Mhc-DP region has been inactivated. At the -DR and -DQ loci, only a limited number of lineages were detected. On the basis of the number of alleles found, the -DQA and -B loci appear to be oligomorphic, whereas only a moderate degree of polymorphism was observed for two of three Mhc-DRB loci. The contact residues in the peptide-binding site of the Caja-DRB1*03 lineage members are highly conserved, whereas the -DRB*W16 lineage members show more divergence in that respect. The latter locus encodes five oligomorphic lineages whose members are not observed in any other primate species studied, suggesting rapid evolution, as illustrated by frequent exchange of polymorphic motifs. All common marmosets tested were found to share one monomorphic type of Caja-DRB*W12 allele probably encoded by a separate locus. Common marmosets apparently lack haplotype polymorphism because the number of Caja-DRB loci present per haplotype appears to be constant. Despite this, however, an unexpectedly high number of allelic combinations are observed at the haplotypic level, suggesting that Caja-DRB alleles are exchanged frequently between chromosomes by recombination, promoting an optimal distribution of limited Mhc polymorphisms among individuals of a given population. This peculiar genetic make up, in combination with the limited variability of the major histocompatability complex class II repertoire, may contribute to the common marmoset's susceptibility to particular bacterial infections.

Diurnal variation and distribution of grooming behavior in captive common marmoset families (Callithrix jacchus)

Grooming is an important social activity among primates. In an investigation of its diurnal distribution, all grooming episodes (self-and allo-) were recorded in three families of captive common marmosets (Callithrix jacchus) kept under natural environmental conditions at hourly intervals for periods of 20 min from 05:00 to 18:00 h, for three consecutive days a week for four weeks. The three families were composed of a reproductive pair and their offspring, with 8, 8 and 7 individuals, respectively. No significant variations were detected within families in terms of days or weeks. However, one family did perform more grooming than the others. The frequency of grooming episodes per hour/per family was higher during the period from 08:00-12:00 h, with acrophases narrowly distributed near 10:00 h, (Family 1 = 10:32 ñ 00:33 h; Family 2 = 10:11 ñ 00:13 h; Family 3 = 09:45 ñ 00:14 h) and lower frequencies were observed at the beginning and end of the active period. The differences between families are probably related to the social dynamics of the individual groups and not to their size

[Association of encephalic vascular accidents and Chagas disease]. / Associação entre acidentes vasculares encefálicos e doença de Chagas.

The frequency of strokes was studied in chronic chagasic and years of age, non-chagasic patients, older than 15 coming to necropsy in Uberaba, from 1979 than 1988. The study consisted of paired sex and age matched controls. Two hundred and eight pairs were analysed. Either ischemic or hemorrhagic strokes were found in 41 (19.7%) of the chagasics and in 55 (26.4%) of the non-chagasic, a difference not significant at the level of 5%. Twelve (75%) of the former had infarcts and 4 (25%) had brain hemorrhage; five (31.3%) of the non-chagasics had ischemic strokes and 11 (68.7%) had hemorrhagic strokes. The differences were significant to the level of 5%. The results indicate a high frequency of ischemic strokes in human Chagas' disease and demonstrate a lesser frequency of hemorrhagic stroke in chagasics when compared with non-chagasics.

Circadian variation of methyleugenol anesthesia in albino rats.

In Wistar rats synchronized to a 12-h light/12-h dark cycle (lights on from 08:00 to 20:00 h), the ip injection of methyleugenol (200 mg/kg) at 08:00, 12:00 and 16:00 h significantly increased the sleeping time (time between loss and recovery of righting reflex) when compared to animals anesthetized at 20:00, 24:00 and 04:00 h. These data provide another example of the importance of circadian rhythms in biological systems and their practical relevance to pharmacology.

Circadian variation of methyleugenol anesthesia in albino rats

In Wistar rats synchronized to a 12-h light/12-h dark cycle (lights on from 08:00 to 20:h), the ip injection of methyleugenol (200 mg/Kg) at 08:00, 12:00 and 16:00 h significantly increased the sleeping time (time between loss and recovery of righting reflex) when compared to animals anesthetized at 20:00, 24:00 and 04:00h. These data provide another example of the importance of circadian rhythms in biological systems and their practical relevance to pharmacology

Variations of the ST segment in the rat electrocardiogram.

The characteristics of the electrocardiogram were studied by an oscilloscope method in 30 male albino rats anesthetized with methyleugenol. The results indicated that the measured QT interval remained constant despite the fall in heart rate. The ST segment was present in 50% of the animals, representing approximately 10% of the whole QT interval duration. The use of Bazzet's formula (QTc = k square root of R-R) to correct the measured QT interval for changes in heart rate revealed that 0.17 is a better choice for k in anesthetized adult rats.