A method for evaluating antianginal drugs in experimental animals: assessment of myocardial ischemia by myocardial pH

This paper describes a method by which antianginal drugs can be evaluated in the dog heart in situ. Myocardial pH was measured continuously by a micro glass pH electrode inserted in the left ventricular endocardial layers of the dog anesthetized with pentobarbital. Occlusion of the left anterior descending coronary artery (LAD) decreased myocardial pH, and release of the LAD restored the pH. The myocardial acidosis induced by ischemia was metabolic in nature and accompanied by a decrease in the levels of adenosine triphosphate and creatine phosphate and an increase in the levels of lactate in the myocardium. Drugs were injected intravenously 30 min after incomplete (partial) occlusion ot the LAD, lasting until 60 min after drug injection. Propranolol, atenolol, and sotalol markedly attenuated the myocardial pH that had been decreased by LAD occlusion. Nitroglycerin, diltiazem, and nicorandil also attenuated the pH, but these drugs were less active in attenuating myocardial acidosis. Dipyridamole, nifedipine, and beta-2 adrenoceptor antagonists were least active in this regard. It is concluded that myocardial pH can be used as an indicator of myocardial regional ischemia and utilized for evaluation of antianginal drugs.     

Additive effect of theophylline on the cardiac response to isoproterenol

To ascertain the effect of theophylline on the cardiac chronotropic response to beta-adrenergic stimulation, isoproterenol dose-response curves in healthy young subjects were compared during saline and theophylline maintenance infusions. Each study was repeated 1 to 3 weeks later to evaluate reproducibility. Neither the dose of isoproterenol required to raise the heart rate by 25 bpm (2.32 +/- 0.81 vs. 1.55 +/- 0.46 micrograms on day 1 and 1.28 +/- 0.22 vs. 1.27 +/- 0.25 micrograms on day 2) nor the slopes of the dose-response curves were affected by theophylline. Higher heart rates were observed after isoproterenol bolus dosing during theophylline than during saline infusion because of additive chronotropic effects of theophylline and isoproterenol. Since theophylline does not interact in a synergistic fashion with isoproterenol, phosphodiesterase inhibition appears to be an unlikely mechanism of the chronotropic effect of methylxanthines at therapeutic concentrations.     

The reaction of skin to primers used in the "single-step" bonding systems

A large number of direct bonding systems have been introduced for use by dentists and dental hygienists. Although these agents are used for direct bonding of brackets to enamel, contact with skin, oral mucosa, and gingiva is not uncommon. These products have wide clinical use, but their biocompatibility characteristics have not been extensively investigated. The present study was undertaken to determine the effects of the primer component of Mono-Lok (Rocky Mountain) and the primer component of Control (Lancer Pacific) on skin. Three adult Macaca mulatta monkeys were used in the study. The skin on their backs was shaved and the primer component of Control, primer component of Mono-Lok, and saline solution were applied at different sites every 3 days for up to four applications. The skin was examined clinically and, 5 days after the last application, a biopsy was performed for histologic evaluation. The skin in contact with the primer component of Mono-Lok exhibited pronounced inflammatory changes and was characterized by swelling, vesiculation, and ulceration. Histologic observations confirmed these findings by showing a marked inflammatory cellular response characterized by eosinophils. In contrast to these findings, the skin in contact with the primer component of Control or saline solution exhibited normal architecture. Histologic observations supported this appearance and showed minimal inflammatory cell infiltration. These results show that there are differences in the biocompatibility of direct bonding systems and that further studies are needed to clarify their long-term effects on patients and dental personnel.     

Is the driver drunk? Oculomotor sobriety testing

Recently a new test involving observation of ocular pursuit movements, end-point nystagmus and angle of lateral deviation at which nystagmoid movements begin has been used by law enforcement agencies to determine the blood alcohol level of suspected drunk drivers. When properly administered and scored, this test can correctly identify approximately 80% of drivers with alcohol levels of 0.10% or greater. The test is more accurate than the traditional coordination or mental computation tests previously used, but questions may be raised about the use of the test with suspects who have ocular problems such as high refractive errors, chronic nystagmus, etc.     

A comparison of Nd:YAG laser damage thresholds for PMMA and silicone intraocular lenses

Power density producing damage at a probability of 0.5 (ie, damage threshold, DT-50) was determined for PMMA (with/without UV absorber) and Silicone intraocular lenses. Scattered light from a collinear diagnostic He:Ne beam was one of four damage monitors deployed to enhance the sensitivity of the system. In order of increasing laser resistance the following results were obtained: injection molded PMMA (1.9/GW/cm2) Silicone (2.63 GW/cm2) Lathe-cut PMMA (4.47 GW/cm2), Lathe-cut PMMA with UV absorber (8.32 GW/cm2), Cast-molded PMMA (12.30 GW/cm2). An analysis of variance revealed interclass differences significant at the .01 level. Cast-molded PMMA was the most laser-resistant IOL material.     

Colonic diverticular disease. Its spectrum in a community hospital

A retrospective study of 239 patients who were hospitalized for diverticular disease is reported. Two thirds of patients had simple diverticulosis, and the remainder had gastrointestinal bleeding, evidence of microabscess, or more serious complications. The prevalence of bleeding on the left side in this series differs from the prevalence of right-sided bleeding noted in the literature, and this difference is unexplained. Only three patients in this series died (overall mortality, 1.2%); all had other associated life-threatening diseases.     

Various problems in the diagnosis and treatment of the broncho-obstructive syndrome

Clinico-x-ray-laboratory investigation, bronchoscopy were performed, respiratory function and ECG were studied in 212 patients with different forms of chronic bronchitis. Six groups of patients were defined with relation to the presence or absence of obstruction, its nature (permanent, transient), prevalence (small, medium and large bronchi), genesis of disease (inflammatory, allergic). The characteristics of the groups and their clinico-x-ray, functional and immunological features were presented. Treatment including methods of climatotherapy, exercise therapy, pharmacological agents (antibacterial, broncholithic and antihistaminic), physiotherapy and administered with relation to the defined groups, proved to be effective. The improvement of bronchial permeability was noted in 49.5% (ranging from 40.0 to 68.7% in different groups).