Effects of temperature on norepinephrine-induced sinus acceleration and overdrive suppression in the isolated dog atrium

Using an isolated, blood-perfused atrium preparation, the effects of temperature on SA nodal pacemaker activity were investigated in 9 preparations. The PP interval decreased as temperature was raised. Regular sinus rhythm and atrial contraction were maintained above approximately 26 degrees C. Below 26 degrees C, sinus depolarization still showed a regular rate, although atrial contractions had ceased. At about 24 degrees C, atrial rhythm became irregular. Below 20 degrees C, atrial depolarization disappeared. Chronotropic responses to norepinephrine were suppressed at decreased temperatures, not only with respect to maximum PP shortening but also to the threshold dose for inducing sinus acceleration. Overdrive suppression was not influenced significantly by decreasing temperature. These results indicate that a temperature decrease causes suppression of SA nodal pacemaker activity, although the SA node continues to function regularly until about 25 degrees C.     

Comparison of polymerase chain reaction and culture methods for detection of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in subgingival plaque samples

In a formerly drug-dependent patient of 35 years of age suffering from an advanced HIV infection there was a development within a period of a few months of rapid weight loss amounting to 12 kg, persistent subfebrile temperatures and progressive dyspnoea on exercise. The histological pattern obtained via bronchoscopy revealed not only pneumocystis carinii pneumonia, which had already been suspected clinically, but also a not very differentiated adenocarcinoma of the lung with lymphangiosis carcinomatosa. The patient died three months after tis diagnosis was established, which had been followed by the usual pneumocystosis therapy and palliative treatment with glucocorticoids.     

Canine testicular tumors: epidemiologic features of 410 dogs

Histologically confirmed testicular tumors were diagnosed in 410 dogs from 12 North American veterinary university hospitals and clinics. Three tumor-cell types, Sertoli cell tumor, interstitial cell tumor and seminoma, were about equally represented. Several breeds were identified with high risk for different testicular tumor-cell types. Cytogenetic and immunogenetic studies of these dog families could offer leads applicable to familial testicular cancer in man. The multiplicity of breeds within the series suggests that, as in man, other factors, in addition to hereditary, play a role in etiology. Cryptorchid dogs appear to have a 13.6 times higher risk of testicular tumor than normal dogs. Additionally, male dogs with an inguinal hernia have an increased risk (4.7) of testis tumors. There were no detectable excesses of other urogenital anomalies or urogenital tumors among the series. The Shetland Sheepdog is suggested as an appropriate model for research into the mechanisms responsible for testicular maldescent and tumorigenesis.     

Acute bacterial endocarditis: a silent source of sepsis in the burn patient

In the past six years, 35 patients with thermal injuries have died with a diagnosis of endocarditis. The cause of death in 21 of the 22 patients with acute bacterial endocarditis (ABE) was directly related to complications arising from the ongoing sepsis. In only three cases was the diagnosis considered pre-mortem. The endocarditis was located in the right heart in 18, left heart in 9, and both sides in 8 cases. Associated venous thrombi were present in 14 instances, and 10 of these were septic thrombi. Staphylococcus was the primary organism in the blood in 17 of 22 patients with ABE. Clinically audible murmurs were present in only two patients. In no instance was ABE superimposed upon previously existing valvular disease. ABE can serve as a silent source of sepsis in the burn patient. The diagnosis should be suspected with persistantly positive blood cultures, especially for Staphylococcus aureus, in any burn patient in whom no other foci of sepsis can be identified. Vigorous methods of diagnosis and specific treatment are recommended.