Characterization of two vasoactive peptides isolated from the plasma of the snake Crotalus durissus terrificus.

Incubation of plasma from the snake Crotalus durissus terrificus (CDTP) with trypsin generated two hypotensive peptides. The primary structure of the peptides was established for two sequences as: (Ser-Ile-Pro-Gln-Ala-Pro-Thr-Ser-Asn-Leu-Ile-Glu-Ala-Thr-Lys) and (Lys-Pro-Asp-Ala-Asn-Gln-Val-Leu-Ile-Gln-Val-Ile-Gly-Val). These peptides display homology with fragments of albumin from Trimeresurus flavoviridis. Bolus intra-arterial injection of the purified or the synthetic peptide produced a strong and sustained vasopressor response in the anaesthetized snake (CDT) and rats (Wistar); this hypotensive effect was also potentiated by captopril-an angiotensin-converting (0.1 mg/kg) enzyme inhibitor.

Effects of three vasoactive peptides isolated from the plasma of the snake Bothrops jararaca.

Incubation of plasma from the snake Bothrops jararaca (BJP) with trypsin generated two hypotensive peptides. The primary structure of the peptides was established for three sequences as: Asn-Pro-Phe-Val-Asp-Ala (fraction 13), Ser-Lys-Pro-Asn-Met-Ser-Asp-Glu-Ser-Leu-Ala-Val-Ala-Ile (fraction 14), Asn-Pro-Phe- Val-Asp-Ala (fraction 15). These peptides display homology with fragments of albumin from Trimeresurus flavoviridis. A bolus intra-arterial injection of the purified or the synthetic peptide produced a strong and sustained vasopressor response in the anaesthetized snake B. jararaca and Wistar rats; this hypotensive effect was also potentiated by captopril, an angiotensin-converting enzyme inhibitor (0.1 mg/kg). The natural concentrations of these peptides in plasma need to be determined and could play a physiological role in snake blood pressure regulation.

Effects of an individually ventilated cage system on the airway integrity of rats (Rattus norvegicus) in a laboratory in Brazil.

The ventilation method used in the management of laboratory rats is important in maintaining their health. Rats kept under general diluting ventilation (GDV) are exposed to high levels of pollutants present in the environment (dust, airborne bacteria, etc.) or those pollutants produced by animal metabolism and excretion inside the boxes (e.g. ammonia and carbon dioxide). These pollutants may contribute to respiratory pathologies. An alternative experimental ventilation system for laboratory animal housing using intracage ventilation technology (individually ventilated cage system, IVC) was developed. In this system, ammonia levels decreased and rats exhibited better reproductive performance and a lower incidence of pneumonia than rats maintained under GDV. Using two different levels of air speed (0.03-0.26 m/s: IVC(1); 0.27-0.80 m/s: IVC(2)), the effects of IVC were compared with GDV (control) in Wistar rats in terms of respiratory mucus properties, on the nasal epithelium (as measured by quantitative morphometry) and on the lungs (as determined by the cellular composition obtained by bronchoalveolar lavage). Mucus of the respiratory system was evaluated using the following techniques: rheology (viscoelasticity) by microrheometer, in vitro mucociliary transportability (frog palate) and contact angle (an indicator of adhesivity). Also, membrane transepithelial potential difference was measured as a biomarker of airway integrity. After bedding was changed, ammonia concentrations inside the cages on day 3 were significantly higher for GDV than for IVC(1) and IVC(2). The potential-difference values for IVC(1), IVC(2) and GDV in the epiglottis and in the trachea also showed differences. Although some significant differences were observed across the three groups in counts of some cell types, the intragroup results were highly variable among individuals and inconsistent between sexes. No significant differences in the other parameters were found across groups. These results establish that rats maintained under GDV in relatively unregulated conditions are exposed to factors that can lead to deleterious effects on the ciliated epithelium of the airways, and that these effects can be prevented by the use of IVC.

Variaçäo na composiçäo do leite de coelha / Variation in the composition of rabbit's milk (oryctolagus cuniculus)

Foi estudada a variaçäo da composiçäo do leite de coelhas reprodutoras Branco Nova Zelândia. Os resultados demonstraram que o teor de proteína do leite näo sofreu variaçäo significativa do 5. ao 15. dia de lactaçäo (11,2 g/100ml de leite) e do 16. dia ao 50. dia (12,4 g/100ml). Os teores de gorduras totais, sódio e potássio foram respectivamente, 13,2 g/100ml, 47,5 mEq/I e 46,6 mEq/I até o 7. dia de lactaçäo; 10,8 g/100ml, 50,8 mEq/I e 50,3 mEq/I entre o 8. e o 30. dia; 14,9 g/100ml, 82,3 mEq/I e 23,6 mEq/I entre o 31. e 62. dia, sendo o 2. e 3. períodos, assim como o 1. e 3., significativamente diferentes. As médias de gorduras totais e de minerais durante todo período de lactaçäo foram: 12,0% de gorduras toatis, 60,2 mEq/I de sódio, 40,2 mEq/I de potássio, 343,6 mEq/I de cálcio, 0,52 mEq/I de zinco, 0,056 mEq/I de cobre e 21,3 mEq/I de magnésio