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Biomedical subjects

J Holt

Publications and source records attributed to J Holt.

At least 91 records · Page 5Linked to original sources
PubMed1986

Silicon metabolism. I. Some aspects of renal silicon handling in normal man.

Renal silicon handling was investigated in 23 healthy adults using electrothermal atomic absorption techniques. The mean urinary silicon excretion was 33.1 +/- 3.85 mg/day; the mean renal silicon clearance was 88.6 +/- 7.94 ml/min; the mean fractional excretion of silicon was 86.35 +/- 8.1%, and the mean urine silicon concentration was 0.265 micrograms/ml. Using multiple correlation analysis, the urinary silicon was found to be highly significantly correlated with the urine magnesium concentration (p less than 0.001) and also with urinary sodium and urinary osmolality (p less than 0.01). 24-hour urinary silicon excretion was highly significantly correlated with fractional excretion of silicon (p less than 0.001), sodium (p less than 0.001), phosphorus (p less than 0.001), magnesium (p less than 0.001), and osmolar load. In split urine studies in 7 subjects urinary silicon was correlated highly significantly with urinary magnesium in all 7 and with urinary osmolality, urine calcium, and urine creatine concentration in 6 of 7. There was a highly significant correlation between renal silicon clearance and fractional excretion of silicon (p less than 0.0005), with magnesium excretion (p less than 0.01), and with sodium excretion. It is suggested that ion pairing of orthosilicate and magnesium may explain some of these urinary findings.

Adult↗
PubMed1985

Left ventricular function after myocardial infarction: clinical and angiographic correlations.

There is a paucity of information correlating the angiographic findings immediately after myocardial infarction with the clinical status before infarction. Therefore, the coronary anatomy, collateral circulation and quantitative left ventricular function were studied in 39 patients who underwent angiography within 3 weeks of a first transmural myocardial infarction. In all patients, the vessel supplying the infarct was totally occluded at the time of angiography. Patients without angina before infarction (Group I) had fewer coronary obstructions than did patients with a long history of angina before infarction (Group II) (1.5 +/- 0.5 versus 2.5 +/- 0.5, respectively, p less than 0.001) but worse overall and regional left ventricular function. These paradoxical differences between Groups I and II were evident in patients with anterior as well as inferior infarction. Patients in Group I had significantly lower collateral scores than did patients in Group II (0.6 +/- 0.8 versus 1.9 +/- 0.9, respectively, p less than 0.0001) and 13 of 22 patients in Group I had no collateral vessels compared with only 1 of 17 in Group II (p less than 0.001). Partial preservation of anterior wall function in Group II patients with anterior infarction was related both to the presence of collateral vessels and to the more distal obstruction of the left anterior descending coronary artery in these patients as compared with patients with anterior infarction in Group I. In contrast, in patients with inferior wall infarction, no relation could be found between the presence of collateral vessels and regional left ventricular function, although only two patients in this series with inferior infarction did not have collateral vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1984

Patterns of creatine kinase release during acute myocardial infarction after nonsurgical reperfusion: comparison with conventional treatment and correlation with infarct size.

Coronary arteriography and biplane ventriculography were performed in 51 patients during the acute (mean of 6.6 hours after onset of symptoms) and chronic (1 to 3 months after admission) phase of myocardial infarction. Twenty-four patients were treated in a conventional manner. In 27 patients, reperfusion was achieved with intracoronary streptokinase after 24 +/- 20 minutes of infusion. Peak creatine kinase and cumulative creatine kinase release were derived from serial creatine kinase measurements. Ejection fraction and the length of the akinetic or dyskinetic segments were calculated in the chronic phase. The time interval between onset of symptoms and peak creatine kinase was significantly shorter for the streptokinase-treated patients as compared with the conventionally treated patients (13.5 +/- 5.3 versus 22.9 +/- 7.4 hours, p = 0.0001). Significant linear correlations were obtained for both streptokinase-treated and control patients, relating: 1) peak creatine kinase value to both length of the noncontracting segment and ejection fraction in the chronic phase, and 2) cumulative creatine kinase release to both length of the noncontracting segment and ejection fraction in the chronic phase. Patients treated with streptokinase experienced a relatively greater release of enzyme for a given infarct size as compared with those treated in a conventional manner. The difference in enzyme release between the two groups increased as infarct size increased. These observations may be explained by enhanced washout of enzyme from the infarct zone, secondary to reperfusion after intracoronary streptokinase therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗
PubMed1984

Acute coronary hemodynamic response to cigarette smoking in patients with coronary artery disease.

The acute changes in coronary blood flow and coronary resistance that occur in response to cigarette smoking have not been accurately determined. To define the factors that affect this response, coronary sinus blood flow was measured in 16 patients (group I) with coronary artery disease and in 6 patients (group II) without angiographically detectable coronary disease. Seven patients (group IA) had severe (greater than or equal to 75%) proximal left coronary lesions and nine patients (group IB) had significant distal lesions with 50% or less proximal stenoses. Group I had a smaller overall increase (increases 1.6 +/- 5.3%) in coronary sinus blood flow than did group II (increases 7.7 +/- 6.1%) (p less than 0.05). Coronary resistance increased overall (increases 2.7 +/- 5.3%) in group I but decreased (decreases 2.4 +/- 3.4%) in group II (p less than 0.05). Patients in group IA had a highly significant increase in coronary resistance as compared with group IB (increases 7.0 +/- 4.2% versus decreases 0.9 +/- 2.6%) (p less than 0.001). Coronary sinus flow tended to decrease (decreases 1.2 +/- 4.6%) in group IA but to increase (increases 3.8 +/- 5.1%) in group IB (p = 0.06). It is concluded that smoking increases coronary resistance in patients with coronary artery disease. A greater impact is observed in patients with a severe proximal stenosis than in those with a distal stenosis. It is proposed that smoking increases coronary artery tone at the site of the stenosis, limiting the coronary flow response proportionally to the size of the affected vascular bed.

Adult↗
PubMed1984

Implications of precordial ST segment depression during acute inferior myocardial infarction. Arteriographic and ventriculographic correlations during the acute phase.

Thirty two patients presenting with acute transmural inferior wall myocardial infarction underwent cardiac catheterisation and angiography within 12 hours of the onset symptoms. Twelve lead electrocardiograms performed within one hour of catheterisation showed ST segment depression in the anterior precordial leads in addition to inferior wall changes in 17 patients and no ST segment changes in the anterior leads in 15. When the clinical, arteriographic, and ventriculographic variables were compared between the two groups no significant differences were noted with regard to age, sex, risk factors for coronary disease, duration of symptoms before angiography, Killip class, number of inferior leads with ST segment elevation, or initial serum creatine kinase activity. The extent of coronary artery disease as well as the prevalence of severe disease in the left anterior descending artery were similar for both groups. Biplane left ventriculography showed no significant differences between the two groups with regard to global ejection fraction or to the prevalence of posterolateral or anterior segmental wall motion abnormalities.

Coronary Angiography↗
PubMed1984

Aortic collagenase activity as affected by laparotomy, cecal resection, aortic mobilization, and aortotomy in rats.

Recent biochemical evidence that aneurysm formation may be related to higher activated collagenase levels within aneurysmal aortic walls in association with reports of asymptomatic aneurysm rupture after laparotomy has led to speculation that operative trauma unrelated to direct aortic injury may increase the chance of aneurysm rupture by inducing collagenase activation within the aortic wall. The purpose of this study was to determine whether aortic collagenase can be activated by distant operative trauma and the kinetics of activation after injury. Ninety-six rats were divided into four groups: group 1--laparotomy alone; group 2--cecal resection; group 3--aortic mobilization; and group 4--aortotomy and repair. Animals within each group were sacrificed 1,3, and 6 hours and 1,2,3,4, and 5 days after surgery. The abdominal aortas were removed and assayed for collagenase activity by incubation with and digestion of tritium-labeled collagen. Collagenase activity was significantly elevated up to 6 hours after direct aortic injury (p less than 0.05) and decreased to normal levels within 2 days. Laparotomy, colon resection, and aortic mobilization had no significant effect on aortic collagenase activity compared to the controls. These data suggest that collagenase activity is a local phenomenon related to wound healing at the site of initial injury. Operative trauma without direct aortic injury had no effect on aortic collagenase activity.

Animals↗
PubMed1983

Coronary vascular reserve in left ventricular hypertrophy secondary to chronic aortic regurgitation.

Coronary vascular reserve was studied in 11 patients with severe chronic aortic regurgitation (AR). Nineteen patients with the chest pain syndrome and normal findings on cardiac catheterization served as control subjects. Resting coronary sinus flow and contrast-agent-induced hyperemia were measured by continuous thermodilution. Left ventricular (LV) dimensions and mass were obtained echocardiographically. All patients had normal coronary arteries. Resting coronary flow was increased and coronary reserve was decreased in patients with AR compared with the control subjects: 310 +/- 38 versus 121 +/- 13 ml/min and 56 +/- 9 versus 86 +/- 7.5%, respectively. The decrease in coronary vascular reserve correlated with the increase in LV mass (r = -0.86, p = 0.001) and LV wall thickness (r = -0.83, p = 0.002) and with the decrease in LV volume/mass ratio (r = 0.761, p = 0.007). There was no significant correlation between the decrease in coronary vascular reserve and LV volume (r = 0.255), LV peak wall stress (r = 0.292), LV systolic pressure (r = -0.495), aortic or LV diastolic pressure (r = 0.322 and -0.318, respectively), or aortic-LV diastolic gradient, nor with the voltage on the electrocardiogram (limb leads r = -0.60, precordial leads r = -0.118). Thus, coronary vascular reserve is decreased in proportion to the degree of left ventricular hypertrophy in patients with chronic AR. Patients with angina pectoris tended to have a lower coronary vascular reserve than those without angina (median 26 versus 76%, difference not significant). LV wall thickness and not LV volume is the critical component of left ventricular mass related to coronary reserve. No significant correlation between the decrease in coronary vascular reserve and the presence of angina pectoris was demonstrated.

Adult↗
PubMed1983

Determinants of ventricular tachycardia in patients with coronary artery disease and ventricular aneurysm. Clinical, hemodynamic, and angiographic factors.

Many patients with coronary artery disease (CAD) in whom ventricular tachycardia (VT) develops have transmural scars or frank aneurysms. However, only a minority of patients with ventricular aneurysms go on to develop VT. To determine which factors are associated with the development of VT in patients with aneurysms, we retrospectively reviewed the records of 154 patients with CAD and segments of akinesia or dyskinesia, or both, on left ventriculography. Of the 154 patients, 85 had 24-hour Holter monitoring or 48 consecutive hours of continuous electrocardiographic monitoring in an intensive care unit within 6 months of catheterization. VT occurring at least 10 days after myocardial infarction (MI) or in the chronic phase was recorded in 19 patients (Group I); the remaining 66 patients did not have VT (Group II). The clinical, hemodynamic, and angiographic characteristics of these 2 groups showed no significant difference with respect to age, time from first transmural MI to catheterization, congestive heart failure (CHF), ejection fraction, or presence of dyskinesia. Patients with VT had significantly larger aneurysms and a higher prevalence of septal akinesia or dyskinesia. However, stepwise discriminant analysis revealed septal akinesia or dyskinesia to be the only independently significant variable distinguishing the 2 groups. Thus, septal involvement appears to be a major determinant of VT in patients with CAD and ventricular aneurysm.

Adult↗
PubMed1983

Angiographic study of the infarct-related coronary artery in the chronic stage of acute myocardial infarction.

We and others have demonstrated a high prevalence of total coronary occlusion during the acute phase of myocardial infarction (MI). This study reports the angiographic appearance of the infarct-related artery (IRA) in 130 patients with a history of MI, who underwent cardiac catheterization 2 weeks to more than 12 months afterwards. The IRA was the left anterior descending in 47%, the right coronary artery in 50%, and the circumflex in 3% of cases. Total coronary occlusion was found in 80% of patients studied 2 to 4 weeks after MI, and decreased gradually reaching 40% of those studied after 12 months of MI. In those patients with a patent IRA, severe stenosis remained: 99% obstruction at 2 to 4 weeks, decreasing to 85.9% obstruction after 12 months (p less than 0.005). The prevalence of total coronary occlusion (TCO) and the severity of stenosis in those without TCO was similar in those with transmural or nontransmural MI and in those with one-, two- or three-vessel disease. This study suggests that endogenous lysis is probably a slow process, and that severe coronary narrowing persists in those with recanalization.

Adult↗
PubMed1983

Dietary choices and likelihood of abstinence among alcoholic patients in an outpatient clinic.

Animal experimentation and informal clinical observation both suggest a possible relation between diet and drinking. Sixty-four newly sober out-patients at the Elmhurst Alcoholism Treatment Program were interviewed at each clinic visit using the 24-h dietary recall method. Patients were interviewed an average of 3 times each. We analyzed for calories, carbohydrates, sucrose, sugar added to beverages, protein, fats, vitamins and minerals. Patients were grouped according to the number of days they remained sober from their last drink. Those who stayed sober longer chose diets containing twice as much sugar added to beverages and more overall carbohydrates (P less than 0.05). At this time we cannot say whether longer sobriety increased appetite for sugar or whether the choice of sugar influenced the patients' ability to stay sober.

Alcoholism↗
PubMed1983

Effects of chronic tobacco smoking on the coronary circulation.

The effects of chronic smoking on the coronary circulation were studied by evaluating the coronary vascular reserve in 12 chronic smokers (group 1) and 10 nonsmokers (group 2). All patients were referred to cardiac catheterization for evaluation of chest pain and were found to have normal coronary and left ventricular angiograms. Coronary vascular reserve was measured by analyzing the hyperemic response to selective coronary injection of contrast agent. There was no statistically significant difference between groups 1 and 2 with regard to age, baseline electrocardiogram or response to treadmill or thallium-201 exercise tests. The mean coronary reserve (+/- standard deviation) was 74.1 +/- 20.1% in the smokers versus 117.1 +/- 45.1% in the nonsmokers (p less than 0.02). In patients who smoked 1 pack a day or less and in those who smoked more than 1 pack a day, the mean coronary reserve was 89.5 and 64.9%, respectively (p less than 0.05). Additionally, of 20 patients followed up for an average of 20 months, 7 of 10 smokers and 1 of 10 nonsmokers continued to have chest pain (p less than 0.03). The cause for the chest pain has not been established in these patients. These results suggest that coronary vascular reserve is significantly less in chronic smokers than in nonsmokers, and that this decrease is more pronounced in heavy smokers.

Adult↗
PubMed1983

A new technique in quantitative immunohematology: solid-phase kinetic enzyme-linked immunosorbent assay.

A solid-phase kinetic enzyme-linked immunosorbent assay has been developed to measure binding of antibodies to purified or synthetic blood group antigens and tested in the Lewis blood group system. Chemically synthesized Lewis a antigen is used as the target for the binding of serum antibody in this sandwich-type assay. Kinetic, rather than endpoint, determinations are used to calculate the amount of specific antibody. Data are presented showing the assay to be quantitative, sensitive, and specific. It can separately quantitate the amount of IgG or IgM anti-Lewis a present in patient sera. The assay uses commercially available reagents and is semiautomated. Thus, it will be useful for studies in quantitative immunohematology as other blood group antigens become available in purified form.

Antibody Specificity↗