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Biomedical subjects

K F Adams

Publications and source records attributed to K F Adams.

At least 55 records · Page 3Linked to original sources
PubMed1991

Influence of calcium administration on the short-term hemodynamic and anti-ischemic effects of nifedipine.

This prospective study investigated whether pretreatment with intravenously administered calcium would influence the effect of nifedipine on rest hemodynamics and treadmill performance in patients with ischemic heart disease. Seventeen patients were studied after undergoing a qualifying treadmill exercise test that revealed ST segment depression indicative of ischemic heart disease. Study subjects performed three additional treadmill tests as part of the protocol. One treadmill test was obtained from each patient to provide baseline measurements without a preceding intravenous infusion and in the absence of all antianginal drugs including nifedipine; two additional exercise tests were preceded by an infusion and 10 mg of bite-and-swallow nifedipine. The infusions, administered in a randomized, double-blind, crossover fashion, consisted of either 10 ml of 10% calcium chloride (13.6 mEq) in 50 ml of 5% dextrose in water or 5% dextrose in water alone. Rest systolic blood pressure (134 +/- 4.6 mm Hg) was unchanged after placebo infusion (135 +/- 4.6 mm Hg) but decreased to 124 +/- 4.1 mm Hg (p less than 0.01) 25 min after nifedipine administration. Rest systolic blood pressure increased after calcium infusion (from 139 +/- 4.3 to 148 +/- 4.8 mm Hg, p less than 0.01) and then decreased significantly 25 min after nifedipine administration to 135 +/- 4.2 mm Hg (p less than 0.01). Despite a decrease at the time of peak nifedipine effect after either infusion, systolic blood pressure was significantly lower after administration of nifedipine alone than after administration of calcium and nifedipine (124 +/- 4.1 vs. 135 +/- 4.2 mm Hg, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1991

Effects of 4 percent and 6 percent carboxyhemoglobin on arrhythmia production in patients with coronary artery disease.

In this study, we assessed the effects of exposure to 4 percent and 6 percent carboxyhemoglobin on ventricular arrhythmias in 41 subjects (nonsmokers) with documented coronary artery disease. We used a randomized, double-blind, crossover design. On day 1, a training session with no exposure, the baseline carboxyhemoglobin level was measured, and a supine bicycle exercise test was done. On days 2 through 4, subjects were exposed to room air, 100 parts per million (ppm)2 carbon monoxide (target, 4 percent blood carboxyhemoglobin), or 200 ppm carbon monoxide (target, 6 percent blood carboxyhemoglobin), and they then did a supine bicycle exercise test. Radionuclide ventriculography was performed at rest and during exercise. Ambulatory electrocardiogram recordings were made during the four consecutive days to determine the frequency of premature ventricular contractions at various intervals. The frequency of single premature ventricular contractions per hour during exercise was significantly greater on the 6 percent carboxyhemoglobin day than on the room air day (167.72 +/- 37.99 for 6 percent carboxyhemoglobin compared with 127.32 +/- 28.22 for room air, p = 0.03). The frequency of multiple premature ventricular contractions per hour was also significantly greater during exercise on the 6 percent carboxyhemoglobin day compared with the room air day (9.59 +/- 3.70 for the 6 percent carboxyhemoglobin day compared with 3.18 +/- 1.67 for the room air day, p = 0.02). Patients who developed increased arrhythmias during exercise on the 6 percent carboxyhemoglobin day were significantly older than those who had no increased arrhythmia, and, in addition, exercised longer and had a higher peak workload during exercise. No effect of carbon monoxide exposure was seen on the 4 percent carboxyhemoglobin day.

Aged↗
PubMed1990

Production of arrhythmias by elevated carboxyhemoglobin in patients with coronary artery disease.

OBJECTIVE: To assess the effects of exposure to 4% and 6% carboxyhemoglobin on ventricular arrhythmias in patients with coronary artery disease. DESIGN: Randomized, double-blind, crossover design. SETTING: Exercise laboratory with an environmentally controlled exposure. PATIENTS: Forty-one nonsmokers with documented coronary artery disease. INTERVENTION: On day 1, a training session with no exposure, the baseline carboxyhemoglobin level was measured, and a supine bicycle exercise test was done. On days 2 to 4, patients were exposed to room air, 100 ppm carbon monoxide (target, 4% carboxyhemoglobin) or 200 ppm carbon monoxide (target, 6% carboxyhemoglobin), and they then did supine bicycle exercise with radionuclide ventriculography. Ambulatory electrocardiogram recordings were made during the 4 consecutive days to determine the frequency of ventricular premature depolarization (VPD) at various intervals. MEASUREMENTS AND MAIN RESULTS: The frequency of single VPD/h was significantly greater on the 6% carboxyhemoglobin day than on the room air day during the exercise period (167.72 +/- 37.99 for 6% carboxyhemoglobin compared with 127.32 +/- 28.22 for room air, P = 0.03). During exercise, the frequency of multiple VPD/h was greater on the 6% carboxyhemoglobin day compared with room air (9.59 +/- 3.70 on the 6% carboxyhemoglobin compared with 3.18 +/- 1.67 on room air, P = 0.02). Patients who developed increased single VPD during exercise on the 6% carboxyhemoglobin day were significantly older than those who had no increased arrhythmia, whereas patients who developed complex arrhythmias were also older and, in addition, exercised longer and had a higher peak workload during exercise. CONCLUSION: The number and complexity of ventricular arrhythmias increases significantly during exercise after carbon monoxide exposure producing 6% carboxyhemoglobin compared with room air but not after exposure producing 4% carboxyhemoglobin.

Age Factors↗
PubMed1990

Comparison of coronary angiography and early oral dipyridamole thallium-201 scintigraphy in patients receiving thrombolytic therapy for acute myocardial infarction.

We evaluated 50 consecutive patients who received thrombolytic therapy for acute myocardial infarction using thallium-201 single photon emission computed tomography in combination with oral dipyridamole (300 mg) to assess the frequency of residual myocardial ischemia. Thallium studies were performed early after myocardial infarction at a mean of 4.6 days (range 3 to 11) in 50 patients. The time from the onset of chest pain to the administration of thrombolytic therapy was 2.6 hours (range 0.5 to 5.5). Q wave myocardial infarction was evident in 46 patients; four patients had a non-Q wave infarction (anterior infarction in 31 patients and inferior infarction in 19 patients). The serum mean peak creatinine kinase was 1503 IU/L (range 127 to 6500). Coronary angiography was performed in all patients at a mean of 3.1 days (range 2 to 10) and revealed the infarct-related vessel to be patent in 36 patients (72%). The ejection fraction was 48% (range 26% to 67%). After dipyridamole administration, 13 patients (26%) developed angina that was easily reversed with the administration of intravenous aminophylline. Systolic blood pressure decreased from 122 to 115 mm Hg (p less than 0.05) and the heart rate increased from 76 to 85 beats/min (p less than 0.05). None of the patients had significant hypotension, arrhythmias, or evidence of infarct extension. Perfusion abnormalities were present on the initial thallium images in 48 patients. Redistribution suggestive of ischemia was present in 36 patients (72%). Ischemia confined to the vascular distribution of the infarct vessel was evident in 22 patients. Seven patients had ischemia in the infarct zone as well as in a remote myocardial segment. Thus 29 patients (58%) had ischemia in the distribution of the infarct vessel. Ischemia in the infarct zone was evident in 19 of 36 patients (53%) with open infarct vessels and in 10 of 14 patients (71%) with occluded infarct vessels. In conclusion, thallium-201 single photon emission computed tomography using oral dipyridamole was safely performed in patients with recent myocardial infarctions who receive thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Endorphins and pain perception in silent myocardial ischemia.

Evidence suggests that endogenous opioids, particularly the beta-endorphins and met-enkephalins, are closely involved in stress-induced analgesia and nociceptive pain control. Numerous investigations have been conducted to evaluate the role of opioids in silent vs symptomatic myocardial disease. There is good evidence to suggest that patients with asymptomatic ischemia have defective pain perception compared with those with angina; however, the precise role of the endorphin and enkephalin systems in this phenomenon remains to be elucidated. Possible sources for disparate study results include variation in patient populations, insensitive or improperly timed assay techniques, and differences in amount of ischemia.

Angina Pectoris↗
PubMed1988

Acute elevation of blood carboxyhemoglobin to 6% impairs exercise performance and aggravates symptoms in patients with ischemic heart disease.

Acute exposure to carbon monoxide has the potential to impair exercise capacity in patients with ischemic heart disease. The effect of sufficient inhalation of this compound to gradually produce a level of 6% carboxyhemoglobin was studied in 30 nonsmoking patients with obstructive coronary artery disease and evidence of exercise-induced ischemia. After an initial training session, subjects were exposed to air or carbon monoxide on successive days in a randomized double-blind crossover fashion. Cardiac function and exercise capacity were assessed during symptom-limited supine radionuclide ventriculography. On the carbon monoxide day, mean postexposure carboxyhemoglobin was 5.9 +/- 0.1% compared with 1.6 +/- 0.1% (p less than 0.01) after air exposure. The mean duration of exercise was significantly longer after air compared with carbon monoxide exposure (626 +/- 50 s for air versus 585 +/- 49 s for carbon monoxide, p less than 0.05). Actuarial methods suggested that subjects were likely to experience angina earlier during exercise on the day of carbon monoxide exposure (p less than 0.05). Both the level (62 +/- 2.4 versus 60 +/- 2.4%, p = 0.05) and change in left ventricular ejection fraction at submaximal exercise (1.6 +/- 1.6 versus -1.2 +/- 1.6%, p = 0.05) were greater on the air exposure day compared with the carbon monoxide day. The peak exercise left ventricular ejection fraction was not different for the two exposures (57 +/- 2.5% for both). These results demonstrate earlier onset of ventricular dysfunction, angina and poorer exercise performance in patients with ischemic heart disease after acute carbon monoxide exposure sufficient to increase blood carboxyhemoglobin to 6%.

Aged↗
PubMed1987

Endorphins are related to pain perception in coronary artery disease.

Plasma beta-endorphin levels were measured by radioimmunoassay before and after exercise in 25 patients with coronary artery disease. Eighteen patients were men and 7 were women; age range was 36 to 75 years (mean 60). All patients had angina pectoris, a positive treadmill test response or positive exercise radionuclide findings. The mean preexercise plasma endorphin level was 4.9 +/- 3.0 pmol/liter (range 0.7 to 13.5). The mean postexercise plasma endorphin level of 6.6 +/- 4.6 mol/liter (range 0 to 19.5) was significantly higher (p less than 0.05). A significant positive correlation was seen between postexercise endorphin levels and time to onset of angina (r = 0.4, p = 0.03). There were negative correlations between postexercise endorphin levels and occurrence (r = -0.4, p = 0.04) and duration of angina (r = -0.4, p = 0.05). No association was found for maximal heart rate-blood pressure product, workload, time to ST-segment depression or stress ejection fraction. A positive correlation was found between rest left ventricular ejection fraction and postexercise endorphin levels (r = 0.5, p = 0.02). In conclusion, in patients with exercise-induced myocardial ischemia, plasma beta-endorphin levels are increased after exercise; postexercise endorphin levels are related to timing and occurrence (presence or absence) of angina; and endorphins may alter the perception of pain caused by myocardial ischemia.

Adult↗
PubMed1987

Evolution of regional left ventricular wall motion abnormalities in acute Q and non-Q wave myocardial infarction.

The evolution of segmental wall motion in Q and non-Q wave acute myocardial infarction was studied in detail in 15 patients without known prior ischemic events. Serial two-dimensional echocardiographic studies were performed beginning early after the onset of chest pain and continuing until 10 to 14 days after admission. An area of apparent infarction was identified on each initial study based on later correlation of ECG and echocardiographic findings. Wall motion of infarct-and noninfarct-related areas was graded in a semiquantitative fashion based on the scoring of a visual analysis. Sequential image data demonstrated significant spontaneous improvement in wall motion of the infarct area in non-Q but not in Q wave events. Patients with non-Q wave infarction and improvement in regional function were at high risk for recurrent infarction within 6 months. Improvement in wall motion inside or outside the area of infarction in Q wave events was related to future risk. We concluded that in patients with initial acute myocardial infarction, failure to develop Q waves correlated with return of function in the apparent area of infarction. Improvement in regional wall motion after the initial study suggested risk for future ischemic events in both ECG types of myocardial infarction. Serial echocardiographic imaging may be a means to identify patients at risk for infarct extension in both non-Q and Q wave events.

Echocardiography↗
PubMed1987

The influence of age and gender on left ventricular response to supine exercise in asymptomatic normal subjects.

The performance of normal subjects during radionuclide ventriculography has been related to age, but the combined effects of age and sex on exercise ventricular function are not well described. We studied 55 normal volunteers, 27 men (age = 30 +/- 10 years) and 28 women (age = 33 +/- 14 years), free of chest pain syndromes, during supine rest/exercise radionuclide ventriculography performed to fatigue. Resting left ventricular ejection fraction did not differ between male and female subjects (64 +/- 5.4 vs 64 +/- 6.1; p = NS). Both the peak left ventricular ejection fraction (78 +/- 4.4 vs 72 +/- 9.2; p less than 0.001) and the change in ejection fraction with exercise (14 +/- 4.0 vs 7.9 +/- 7.0; p less than 0.001) were significantly greater in men compared to respective values in women. Regression analysis showed that sex (r = 0.51; p less than 0.001) but not age (r = -0.18; p = 0.19) was a significant predictor of change in ejection fraction with exercise. Data on left ventricular volume response to exercise, available in 43 subjects, revealed that men had a greater percentage of decline in end-systolic volume with exercise than women (-47 +/- 15 vs -24 +/- 26; p less than 0.001). It is concluded that sex exerts a significant influence on normal left ventricular response to fatigue-limited supine exercise and that the gender difference is mediated, in part, by left ventricular end-systolic volume response to exercise.

Adolescent↗
PubMed1984

Intranasal interferon-alpha 2 for prevention of natural rhinovirus colds.

The prophylactic activity of intranasal human interferon-alpha 2 (HuIFN-alpha 2) against natural rhinovirus colds was determined in a randomized, double-blind, placebo-controlled trial. A total of 304 working adults self-administered sprays of HuIFN-alpha 2 (10(7) IU/day) or a placebo once daily. During 22 days of treatment, 13 (8.5%) placebo recipients but no HuIFN-alpha 2 recipients had respiratory illnesses documented secondary to rhinovirus infection (P = 0.0002). The occurrence of illness with symptoms of tracheobronchitis was lower in HuIFN-alpha 2 recipients (one eposide) than in placebo recipients (eight episodes, P = 0.04). In contrast, the frequency of nasal symptoms and the overall rate of respiratory illness were significantly higher in HuIFN-alpha 2 recipients during weeks 2 and 3 of treatment. Symptoms (obstruction, discomfort, blood-tinged nasal mucus) or signs (punctate bleeding sites, erosions, superficial ulcerations) of nasal irritation occurred in 40 HuIFN-alpha 2 recipients during week 3 (P less than 0.0001 versus placebo recipients). Although the results of the current study were partially confounded by the nasal side effects of prolonged administration, they showed that intranasal HuIFN-alpha 2 was efficacious in preventing rhinovirus colds under natural conditions.

Administration, Intranasal↗
PubMed1982

Antitussive effect of guaifenesin in young adults with natural colds. Objective and subjective assessment.

The efficacy of guaifenesin in reducing cough frequency in young adults with acute respiratory disease was evaluated by both an objective cough counting system and a questionnaire. A guaifenesin cough preparation and the syrup vehicle were administered in a double-blind manner. Coughs were recorded on tape over a 24-hour baseline evaluation period and a 36-hour treatment period for 42 patients. A pronounced diurnal variation in cough frequency was observed. The evaluation of efficacy was based upon comparisons between equivalent six-hour time periods of successive days. No antitussive effect of guaifenesin was demonstrated. The questionnaire was administered to 65 patients, including the 42 whose coughs were recorded. Of 26 patients with productive cough receiving guaifenesin, 25 (96 percent) reported a decrease in sputum thickness compared to 13 (54 percent) of 24 patients receiving the vehicle (p = 0.01, Fisher exact test). Twenty-three of 26 (88 percent) patients receiving guaifenesin also reported reduction in sputum quantity compared to 15 of 24 (62.5 percent) receiving the vehicle (p = 0.07, Fisher exact test). The diurnal variation in cough frequency measured by the tape recording was not apparent from the subjective cough frequency estimates obtained by the questionnaire.

Adolescent↗
PubMed1981

Comparative toxicity of amantadine hydrochloride and rimantadine hydrochloride in healthy adults.

The relative toxicities of amantadine and rimantadine were compared in a double-blind, placebo-controlled study involving healthy adults. In separate studies, drugs were administered at a dosage of 200 mg/day (52 volunteers) or 300 mg/day (196 volunteers) for 4.5 days. Both drugs were well tolerated at the lower dosage. At 300 mg/day amantadine recipients had a greater frequency and severity of central nervous system (nervousness, lightheadedness, difficulty concentrating) and sleep (insomnia, fatigue) complaints compared with rimantadine or placebo recipients. Amantadine recipients also performed less well on an objective test measuring sustained attention and problem-solving ability. Both amantadine and rimantadine recipients reported adverse gastrointestinal symptoms more often than placebo recipients. Because of better tolerance at higher dosage, rimantadine offers more promise than amantadine for treatment of influenza A virus infections.

Adamantane↗
PubMed1979

The effect of copper on erythrocyte deformability: a possible mechanism of hemolysis in acute copper intoxication.

Although the development of hemolytic anemia as a complication of acute copper intoxication is well documented, the precise mechanism by which copper produces accelerated erythrocyte destruction is unknown. Normal erythrocyte survival depends in part on the ability of the cell to deform and pass through narrow areas of microcirculation in the liver and especially in the spleen. In the present study, it is demonstrated that toxic concentrations of copper rapidly and markedly reduce erythrocyte deformability. This reduction in cell deformability is associated with a marked increase in membrane permeability and osmotic fragility of copper-treated cells. Further, the decrease in deformability occurs despite normal levels of cell ATP and the apparent absence of oxidative damage to the cell. These observations indicate that copper-mediated changes in the erythrocyte membrane may be responsible for reducing the flexibility of the cell. The loss of deformability could act to reduce erythrocyte survival and thus explain the hemolysis associated with copper intoxication in vivo.

Anemia, Hemolytic↗
PubMed1977

Acceptibility and antigenicity of influenza A/Victoria/75 virus vaccines in adults of different ages.

Influenza A/Victoria/75 virus vaccines were tested for acceptability and antigenicity in adults of different ages. Whole-virus vaccines prepared by Merck Sharp and Dohme (West Point, Pa.) and Merrell-National Laboratories (Cincinnati, Ohio) and subunit vaccines prepared by Parke, Davis and Company (Detroit, Mich.) and Wyeth Laboratories (Philadelphia, Pa.) were given intramuscularly in concentrations of 800, 400, or 200 chick cell-agglutinating units per dose. Systemic and local side effects of all vaccine preparations were negligible. In volunteers with low or absent (less than or equal to 10) titers of hemagglutination-inhibiting antibody before vaccination, titers of greater than or equal to 40 were attained after vaccination in 43%-67%, 40%-58%, and 20%-38% of volunteers receiving the 800, 400, and 200 chick cell-agglutinating unit preparations, respectively.

Adolescent↗
PubMedDate not supplied

Lack of effect of low levels of carboxyhemoglobin on cardiovascular function in patients with ischemic heart disease.

We studied 30 patients 38-75 yr of age who had ischemic heart disease to assess the effect of acute elevation of carboxyhemoglobin (COHb) concentration. Patients were nonsmokers with ischemia defined by exercise-induced ST depression (ST decreases)--25/30, angina--23/30, or abnormal ejection fraction (EF) response--18/30. After an initial familiarization and exercise session patients were exposed to air (carboxyhemoglobin [COHb] = 1.5 +/- 0.05%) and to carbon monoxide (CO) (100 ppm-COHb-average = 3.8 +/- 0.1%) on successive days in a double blind, randomized fashion. There was no significant difference in time to onset of angina (air = 312 sec, CO = 306 sec), maximal exercise time (air = 711 sec, CO = 702 sec), maximal ST decreases (1.5 mm for both), or time to significant ST decreases (air = 474 sec, CO = 475 sec). Double product at ST decreases and maximal double products were similar for both conditions. Resting ejection fraction was slightly but nonsignificantly higher after CO exposure (air = 53.9%, CO = 55.2%). Maximal ejection fraction was similar for both conditions (air = 57.4%, CO = 57.1%). Change in ejection fraction was slightly lower for CO exposure (air = 3.5%, CO = 2%), p = .049. In conclusion, there is no clinically significant effect of 3.8% COHb (representing a 2.2% increase from resting values) on the cardiovascular system in this study.

Administration, Inhalation↗
PubMedDate not supplied

Effects of low-level carbon monoxide exposure on resting and exercise-induced ventricular arrhythmias in patients with coronary artery disease and no baseline ectopy.

The effects of acute elevation of carboxyhemoglobin (COHb) concentrations on resting and exercise-induced ventricular arrhythmias were evaluated in 10 patients who had ischemic heart disease and in whom no ectopy during baseline monitoring was noted. After an initial training session, patients were exposed to air, 100 ppm carbon monoxide (CO), or 200 ppm CO on successive days in a randomized, double-blind, cross-over fashion. After exposure to 100 and 200 ppm CO, venous COHb levels averaged 4% and 6%, respectively. Symptom-limited supine exercise was performed after exposure. Eight of the 10 patients had evidence of exercise-induced ischemia--either angina, 1.0 mm ST depression, or abnormal ejection fraction response--during 1 or more exposure days. Ambulatory electrocardiograms were obtained on each day and analyzed for arrhythmia frequency and severity. On air and CO exposure days, each patient had only 0-1 ventricular premature beat/h in the 2 h prior to exposure, during the exposure period, during the subsequent exercise test, and in the 5 h following exercise. In conclusion, low-level CO exposure is not arrhythmogenic in patients with coronary artery disease and no ventricular ectopy at baseline.

Aged↗