Doxorubicin affects the cardiac muscarinic system in the rat.

During the study on the mechanism of doxorubicin-induced cardiotoxicity, we observed that a long incubation (4 hr) with doxorubicin reduced the maximal negative inotropic effects of a muscarinic receptor agonist, carbachol. The mechanism responsible for this doxorubicin-induced reduction of the efficacy of carbachol was examined in isolated guinea pig hearts. In isolated left atrial muscle preparations, 1 hr incubation with 100 microM doxorubicin caused a parallel right-ward shift of the concentration-response curves for carbachol, but a longer (4 hr) incubation with this agent (30, 100 or 200 microM), caused a significant reduction of the magnitude of the negative inotropic effect of carbachol in addition to the concentration-dependent parallel right-ward shift. The 4-hr incubation with these concentrations of doxorubicin also reduced the maximal negative inotropic effect of an adenosine A1 receptor agonist, R-phenylisopropyl adenosine (R-PIA), without affecting the potency of this agonist. Doxorubicin (1 to 100 microM) reduced [3H]quinuclidinyl benzilate (QNB) binding in a concentration dependent manner, but failed to alter [3HIR-PIA binding. The decrease in the magnitude of the maximal negative inotropic effect by doxorubicin was caused by changes in the muscarinic system at steps common to the transduction of muscarinic and adenosine A1 receptor mechanisms.     

Effects of perineural capsaicin treatment on compound action potentials of superior laryngeal nerve afferents in sevoflurane-anesthetized dogs

Effects of perineural capsaicin (CAPS) treatment on compound action potentials of the superior laryngeal nerve (SLN) afferents were studied in 6 sevoflurane-anesthetized dogs. Perineural CAPS (100 microg/ml) to the bilateral SLNs reduced (P<0.01) the peak and integral amplitudes of the C-wave of the compound action potential. By contrast, the perineural CAPS had no effect on the A-wave component (P>0.05). Removal of the perineural CAPS recovered the C-wave to pretreatment level. The perineural CAPS treatment selectively blocks C-wave compound action potentials of the SLN afferents, providing a useful tool for studies of laryngeal C-fibers in respiratory physiology.     

Telomere length and telomerase activity in canine mammary gland tumors

OBJECTIVE: To measure telomere length and telomerase activity in naturally occurring canine mammary gland tumors. SAMPLE POPULATION: 27 mammary gland tumor specimens obtained during resection or necropsy and 12 mammary gland tissue specimens obtained from healthy (control) dogs. PROCEDURE: Telomere length in tissue specimens was measured by use of restriction endonuclease digestion and Southern blot analysis. Telomerase activity was measured by use of a telomeric repeat amplification protocol assay. RESULTS: Telomere length in mammary gland tumors ranged from 11.0 to 21.6 kilobase pairs (kbp; mean +/- SEM, 14.5+/-0.5 kbp) but did not differ among tumor types. Telomeres in mammary gland tumors were slightly shorter than in normal tissue specimens, but telomere length could not be directly compared between groups, because mean age of dogs was significantly different between groups. Age was negatively correlated with telomere length in control dogs but was not significantly correlated with length in affected dogs. Telomerase activity was detected in 26 of 27 mammary gland tumors and in 4 of 12 normal tissue specimens. However, telomerase activity and telomere length were not correlated in tumor specimens. CONCLUSIONS AND CLINICAL RELEVANCE: Telomere length is maintained in canine mammary gland tumors regardless of the age of the affected dog. Measurement of telomere length may be a useful tool for monitoring the in vivo effects of telomerase inhibitors in dogs with tumors.     

Comparison of behavioral effects of morphine and fentanyl in dogs and cats

Behavioral effects induced by intravenous administration of morphine at 0.3, 0.6, 1.2, and 2.4 μg/kg and fentanyl at 5, 10, 20, and 40 μg/kg were evaluated in dogs and cats. In dogs, fentanyl and morphine depressed activity and level of consciousness in a dose- dependant manner. In cats, higher doses of fentanyl stimulated activity temporarily, but excitement, so-called "opioid mania," was not observed. Morphine induced distinctive behavioral changes characterized by sitting with fixed staring, and "opioid mania" was not observed in cats.     

Two new variants of the Rhodococcus equi virulence plasmid, 90 kb type III and type IV, recovered from a foal in Japan

Calves were vaccinated orally, subcutaneously or intraperitoneally with a smooth, plasmid-cured strain of Salmonella enterica serovar typhimurium, strain 81. Oral vaccination was not effective, as only 1/5 calves survived challenge with virulent S. typhimurium. Strain 81 was attenuated for calves, as only a slight rise in rectal temperatures was detected after vaccination. The organism was excreted by some calves in the faeces, but no signs of diarrhoea were observed after vaccination. After parenteral vaccination, strain 81 was able to reach the intestines, gastric associated lymphoid tissues and other internal lymphoid tissues and remained viable for up to 14 days in the bovine host. After oral challenge with a virulent strain, 9/10 vaccinated calves survived challenge as opposed to 4/10 control calves (p<0.5). Diarrhoea was present in all calves of the control groups, but in only 4/10 of the vaccinated calves. The clinical reactions of the vaccinated calves were milder than in the control calves, as the rises in rectal temperatures were lower, diarrhoea was less severe, and the challenge strain was present in fewer organs from vaccinated calves than control calves. This study showed that parenterally administered Salmonella vaccines can induce both mucosal and systemic immunity, and it is postulated that this capability of strain 81 is related to its colonisation of lymphoid tissues and other systemic and intestinal tissues. This study confirmed that plasmid-cured strains were attenuated in the bovine host and conferred significant protection after parenteral vaccination, but not oral vaccination.     

Stress analysis of wood

Summary For the preparation of specimens for testing the stress distribution with the photoelastic method, various techniques are applicable. In this paper the so-called glass-transition temperature method is tested on a specimen imitating the layered structure of wood. The observations made on this specimen are compared with those obtained from a specimen with isotropic properties.

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Zusammenfassung Für die Herstellung von Modellen zur Untersuchung der Spannungsverteilung mit spannungsoptischen Verfahren gibt es verschiedene Techniken. In dieser Mitteilung wird das sogenannte Glas-Übergangstemperatur-Verfahren an einem Modell, das den Schichtaufbau des Holzes nachahmt, geprüft. Die Beobachtungen, die an diesem Modell gemacht wurden, werden mit jenen verglichen, die sich an einem Modell mit isotropen Eigenschaften ergaben.

     

Tetracycline-resistance genes of Clostridium perfringens, Clostridium septicum and Clostridium sordellii isolated from cattle affected with malignant edema

The minimal inhibitory concentrations (MICs) of 10 antimicrobial agents against a total of 33 isolates of Clostridium perfringens, Clostridium septicum and Clostridium sordellii from cattle affected with malignant edema in Japan was determined. The low MIC activities of benzylpenicillin confirm the place of benzylpenicillin as the antibiotics of choice for treatment of malignant edema. Five (22%) of 23 C. septicum strains, five (71%) of seven C. perfringens strains and all strains of C. sordellii showed resistance to oxytetracycline. These oxytetracycline-resistant strains carried tetracycline-resistance genes [tetA(P), tetA408(P), tetB(P) and tetM]. The sequences of the tetracycline-resistance genes of some C. septicum strains were completely or nearly completely identical to those of strains belonging to other clostridiual species. This is the first report of resistance of C. septicum to tetracycline.     

Skin and coat traits in sheep in Brazil and their relation with heat tolerance

The objective of this study was to evaluate and compare physical parameters in groups of sheep with different phenotypic characteristics in the Centre-west region of Brazil. Five groups of sheep, with nine animals per group, were selected, three groups of Santa Inês animals with different coat colours (white, brown and black), one group with crossbred animals (Santa Inês × Bergamasca) and one group with animals of the Bergamasca breed. The following traits were evaluated: coat thickness, number and length of hair, pigmentation level in the coat and the skin as well as the percentage area of sweats glands in the skin tissue, carried out by histological analysis. The number of hairs and the area of sweats glands were not significantly different between the evaluated groups. The Bergamasca breed showed low pigmentation of the skin and long hairs. The levels of pigmentation of the hair and of the skin were highly correlated. Between the Santa Inês groups, the group with white hair showed the better parameters for heat adaptation, while the brown hair group showed the lower heat adaptation when compared with another hair breed groups.     

Cytotoxicity for porcine islet cells by complement of six animal species

Complement-mediated cytotoxicity for porcine islet cells (PICs) was evaluated using sera of six animal species. Then soluble complement receptor type-1 (sCR1) as an anti-complement agent was added to those sera, and the changes in 50% hemolytic unit of complement serum (CH50) and cytotoxic effect of those sera on PICs were examined. All the sera except for that of pig showed cytotoxicity. However, the extent of toxicity was considerably different between species. In the rat and human serum, sCR1 significantly reduced CH50 and cytotoxicity, however in the dog serum, sCR1 had no suppressive effects. These results may suggest that complement contribute to humoral cytotoxicity for PICs as a main factor, and the compatibility of complement with PICs differs between animal species.