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OBJECTIVES: The purpose of this study was to determine the effects of alendronate on the peri-implant bone in rat maxillae with the aid of micro-computed tomographic, histologic, and biochemical analyses. MATERIALS AND METHODS: Thirty-six male Sprague-Dawley rats were used. After extraction of the maxillary first molars, each rat was given periodic subcutaneous injections of either alendronate (alendronate group) or saline (control group). Customized implants were placed bilaterally 4 weeks after these injections. The rats were sacrificed at either 4, 8, or 12 weeks after implantation (4-, 8-, and 12-week groups, respectively; n = 6 rats per group). Microcomputed tomographic and histologic analyses were conducted for all rats. Biochemical analyses were performed at four time points for the 12-week groups. RESULTS: There were no significant differences between the groups on microcomputed tomographic and histologic analyses. All of the measured biochemical parameters tended to decrease over time, with significant differences among some time points within each group. The serum osteocalcin level was significantly lower in the 12-week alendronate group than in the control group (P < 0.05). CONCLUSIONS: Three approaches were utilized in evaluating the effects of alendronate. It appears serum osteocalcin levels may serve as an adjuvant marker for this purpose, although further studies are required to confirm this.

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Many potential applications of genetically engineered microorganisms in environmental and agricultural biotechnology involve introducing genetic capabilities into nonsterile competitive environments in which they provide no advantage to the host. Field application vectors have been designed for the purpose of creating a temporary niche for the host in such environments. This technique involves the addition to the target environment of a selective substrate readily utilizable by the host microorganism but unavailable to most indigenous species. Thirteen nonionic and anionic detergents, representing a wide range of structural complexities and molecular weights, were screened as potential selective substrates. Competition experiments in soil, using Warburg respirometry, indicated that isolates from six different detergent enrichment cultures were more active on their corresponding detergents than the indigenous microorganisms. Detergents of intermediate structural complexities and molecular weights were most effective for use as selective substrates. A field application vector that utilizes 1.0% Igepal CO-720 (detergent) as the selective substrate and Pseudomonas paucimobilis 1IGP4 as the host was tested for its ability to increase the presence of nonadaptive tetracycline resistance marker genes in soil. In soil amended with the selective substrate, strain 1IGP4 plate counts increased by three orders of magnitude and tetracycline-resistant transformant (pRK293) counts increased from 1.8 x 10/g of soil to 4.3 x 10/g in 2 days. Inoculation in the absence of substrate amendment or amendment with a nonselective substrate did not result in growth of strain 1IGP4. These results demonstrate the effectiveness of field application vectors for increasing the concentration of nonadaptive genes in competitive environments.

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His bundle electrograms were recorded in 12 patients before and after the intravenous administration of 5 mEq of potassium. Antegrade and retrograde refractory periods were determined with the extrastimulus technique. The AH interval was 84 +/- 7 msec before and 89 +/- 7 msec after potassium (P < 0.05). The AH interval at an atrial pacing rate of 140/minute was 129 +/- 13 msec before and 143 +/- 16 msec after potassium (P < 0.02). The effective refractory period of the atrium was 264 +/- 9 msec before and 280 +/- 9 msec after potassium (P < 0.001). Thus small amounts of potassium delay conduction at the atrial and AV nodal level.

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The effects of nitroprusside on His bundle electrograms, when given intravenously for 10 minutes, were studied in 14 patients with heart disease. Recordings were made at varied heart rates using atrial and ventricular pacing. Nitroprusside significantly reduced the AH interval, but it had no effect on the HV interval. Functional and effective refractory periods were measured by the extrastimulus technique. The functional refractory period of the AV node as well as the effective refractory period of the ventriculoatrial conduction system significantly decreased after nitroprusside infusion. This improvement in conduction can probably be explained by the systemic hypotension produced by nitroprusside, which reflexly will increase sympathetic drive to the heart and decrease vagal tone.

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Thirty-seven patients with acute myocardial infarction complicated by atrioventricular or bundle branch block, or a combination of both, has His bundle electrogram studies performed during their stay in the coronary care unit. The acute mortality of the 14 patients with a complicating bundle branch was 50%. Pump failure was the main cause of death. Three patients in this group had a prolonged H-V interval and one patient had a split blundle of His. The presence or absence of a prolonged H-V interval did not affect mortality in this group of patients. The acute mortality of the 16 patients with an inferior wall myocardial infarction was 6%. The H-V interval was normal in all but one of these patients. The atrioventricular block was caused by a proximal block in all cases. The acute mortality of the seven patients with an anterior wall myocardial infarction was 29%. The H-V interval was prolonged in two of seven patients. Pump failure was the acute cause of the deaths. The presence or absence of a prolonged H-V interval did not affect mortality in this group of patients.

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Two days after an acute myocardial infarction, a patient developed pleuropericarditis. A negative lung scan and echocardiographic evidence of pericardial effusion were instrumental in making the diagnosis. Steroid therapy led to a dramatic resolution of the signs and symptoms. Pericardial effusion is usually a late complication of myocardial infarction (Dressler's syndrome), but the increasing use of echocardiography may demonstrate that it occurs early in the course.

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Levels of serum calcium, phosphorus, magnesium, SGOT, CPK, and LDH were measured in 61 patients admitted to a coronary care unit. In 34 the ECG and enzymes confirmed an acute myocardial infarction, whereas the remaining 27 did not have an acute myocardial infarction. The serum phosphorus declined significantly in those with the acute infarction compared to the control group. The fall was most marked in the third and fourth postinfarction day, and by the fifth day had returned to baseline values. The serum calcium and magnesium did not change significantly over the 5 days. Thus the fall in the serum phosphorus serves as a sensitive indicator of acute myocardial infarction.

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There is no information on the effects of coffee on the human conduction system. His bundle electrograms were obtained in 12 patients before and 20 minutes after the ingestion of coffee containing 150 mg caffeine. Antegrade and retrograde refractory periods were obtained with the extrastimulus method. The effective and functional refractory period of the atrioventricular node decreased after coffee ingestion. This improvement in conduction is probably mediated by a release of catecholamines.

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Seven patients with mitral insufficiency and seven patients with aortic insufficiency were studied by right and left heart catheterization. Hemodynamic observations were made during a control period and during the infusion of phentolamine. Significant declines in the pulmonary artery mean pressure, left ventricular end diastolic pressure, peripheral resistance, and arteriovenous oxygen difference were seen in both groups. The cardiac index increased significantly in the two groups. Phentolamine therapy produced favorable hemodynamic effects because of its vasodilating action as well as its positive inotropic effects.

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Hypertension, diabetes mellitus, hypercholesterolemia, and smoking are known coronary risk factors. It has been our impression that premature graying of the hair also predisposes individuals to myocardial infarctions. To test this hypothesis, we evaluated all of the patients under the age of 50 who were admitted to the coronary care unit between 1974 and 1976 with a proven diagnosis of a myocardial infarction. There were 50 patients. Thirty-eight did not have premature graying. Twelve of the male patients (24%) had virtual total graying of the hair which made them appear older than their stated age. The graying in these patients started on the average at 29 years. Five of these patients state that other family members had premature hair graying. The incidence of diabetes, hypertension, and smoking was similar in those with and without premature hair graying. This preliminary study suggests that premature graying of the hair is associated with premature cardiovascular disease. It should probably be regarded as a coronary risk factor and used to identify patients at increased risk.

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The hemodynamic effects of intravenous morphine were documented by right heart catheterization in six patients with an acute uncomplicated transmural myocardial infarction one to three days after the onset of symptoms. Intracardiac pressures, brachial artery pressure, and cardiac output were determined before and 15 minutes after the termination of the morphine infusion. Five milligrams morphine was given intravenously over a 10-minute period. The brachial artery pressure fell from a mean of 78 to a mean of 73 mm Hg (NS). As a result or morphine administration, the average cardiac index decreased from 2.68 to 2.31 liters/min-m2 (P is less than 0.05), and the stroke index decreased from 27 to 22 ml/beat-m2 (P is less than 0.05). Only small changes were observed in the intracardiac pressures.

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A His bundle electrogram was obtained in a 70 year old male with syncopal episodes. A split bundle of His deflection was recorded. After the intravenous administration of phentolamine, a marked shortening of the H-H' interval was observed. This signifies an improvement in conduction at the bundle of His level.

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