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Biomedical subjects

H Ikram

Publications and source records attributed to H Ikram.

At least 163 records · Page 9Linked to original sources
PubMed1983

Hemodynamic, hormonal and electrolyte responses to prenalterol infusion in heart failure.

The hemodynamic, hormonal and electrolyte effects of prenalterol, a synthetic selective beta 1 agonist, were studied in six patients with New York Heart Association functional class II and III heart failure. Prenalterol was infused incrementally at 60, 120 and 240 nmol/min, each rate for 24 hours, producing steady-state plasma prenalterol levels of 52 +/- 3, 121 +/- 6 and 194 +/- 9 nmol/1, respectively (mean +/- SEM). Hemodynamic and hormonal measurements were performed before, during and after prenalterol administration under conditions of constant body posture and a regulated intake of dietary sodium and potassium. Prenalterol induced a statistically significant increase in cardiac index (from 2.6 +/- 0.2 to 3.1 +/- 0.3 1/min/m2), with parallel increases in stroke index (from 28 +/- 2 to 34 +/- 2 ml/beat/m2). Forearm blood flow measurements increased (from 2.9 +/- 0.5 to 4.1 +/- 0.6 ml/min/100 g), while calculated systemic vascular resistance fell, as did pulmonary capillary wedge pressure (from 13.7 +/- 1.6 to 10.5 +/- 1.7 mm Hg). The drug did not alter heart rate, arterial pressure, right heart pressures or the frequency of ventricular premature beats. Prenalterol increased plasma renin activity (from 2.9 +/- 0.8 to 6.6 +/- 1.8 nmol/1/hour), angiotensin II (from 59 +/- 12 to 89 +/- 22 pmol/1), urinary aldosterone excretion (from 41 +/- 10 to 78 +/- 34 nmol/day) and plasma insulin (from 10.6 +/- 2.2 to 19.8 +/- 3.9 mU/1). Circulating catecholamines, cortisol, glucose, glucagon or pancreatic polypeptide did not change. Dose-response studies in five patients showed dose-dependent increments in hemodynamic variables, while hormonal changes plateaued at the second dose level. We conclude that prenalterol infusion augments myocardial contractility, reduces systemic vascular resistance, and stimulates insulin release and the renin-angiotensin-aldosterone system.

Dose-Response Relationship, Drug↗
PubMed1983

Acute haemodynamic, hormonal and electrolyte effects and short-term clinical response to enalapril in heart failure.

To define the short-term haemodynamic, hormonal and electrolyte effects of enalapril in chronic heart failure, we administered it to nine patients. The first dose (5 mg) induced a gradual reduction in plasma angiotensin II, systemic vascular resistance, arterial pressure, heart rate and right heart pressures, the maximum effects occurring within 4-8 h. Angiotensin II levels were still suppressed 24 h after the initial dose, but haemodynamic indices had returned almost to control values by this time. Dose-related increases in cardiac index and plasma renin, and decreases in angiotensin II, systemic vascular resistance and urine aldosterone excretion were seen with 5, 10 and 20 mg enalapril. Cumulative balances for sodium and potassium were positive, plasma potassium increased and plasma antidiuretic hormone fell. After 4-8 weeks of enalapril therapy, clinical status and exercise tolerance improved in the patients who were most severely restricted initially. Enalapril may be useful in the treatment of chronic heart failure.

Aged↗
PubMed1982

Captopril in patients with terminal cardiac failure.

The clinical responses to captopril, an oral converting-enzyme inhibitor, in five patients with resistant heart failure are described. Earlier treatment consisting of digoxin, diuretics and vasodilators had proven inadequate, and each patient was considered end-stage. Captopril therapy resulted in clear-cut improvements in exercise tolerance, a decrease in decubitus and effort dyspnoea, increased energy, a sense of well-being, and enabled all to become ambulatory. Captopril is a major advance in the treatment of patients with severe resistant heart failure.

Aged↗
PubMed1982

Hemodynamic and hormonal responses during captopril therapy for heart failure: acute, chronic and withdrawal studies.

The hemodynamic and hormonal responses to acute and chronic captopril therapy and to its temporary withdrawal were studied in seven patients with congestive heart failure. Maximal hemodynamic and hormonal effects were reached with 25 to 50 mg doses of captopril. Since plasma angiotensin II levels were significantly higher 6 1/2 hours than 1 hour after administration of captopril, the drug should be given not less often than three times daily. No evidence of hormonal "escape" during long-term (mean 4 1/2 months) captopril therapy was observed, and initial hemodynamic responses were well maintained. Cessation of captopril administration resulted in abrupt increases in circulating angiotensin II levels, in arterial pressure, and in both pulse rate and plasma norepinephrine, but no decrease in cardiac function in the short-term was detected.

Aged↗
PubMed1982

Hepatitis B virus vaccine: identification of HBsAg/a and HBsAg/d but not HBsAg/y subtype antigenic determinants on a synthetic immunogenic peptide.

On the basis of theoretical considerations, a peptide (H peptide) was synthesized by Hopp and Woods [Hopp, T. P. & Woods, K. R. (1981) Proc. Natl. Acad. Sci. USA 78, 3824---3828]. This peptide contains a sequence of six amino acids postulated to represent the major epitope, or antibody-combining site, of hepatitis B virus surface antigen (HBsAg). We have used passive hemagglutination inhibition with monospecific antibodies against the a, d, and y subdeterminants of this antigen and against human serum albumin to investigate the antigenic specificities on this peptide, and we have found it to contain the HBsAg/a and HBsAg/d but not HBsAg/y or human serum albumin subdeterminants. When the peptide was conjugated onto human erythrocytes and injected into mice, it induced the formation of anti-HBsAg with and without the use of Freund's adjuvant. If anti-HBsAg/a confers immunity to infection with hepatitis B virus, as is generally thought, these findings may permit the development of a synthetic vaccine lacking all unnecessary antigenic determinants.

Amino Acid Sequence↗
PubMed1982

Haemodynamic and hormonal effects of captopril in primary pulmonary hypertension.

The treatment of primary pulmonary hypertension is unsatisfactory. Since, in animals, experimental pulmonary vasoconstriction may be mediated in part by angiotensin II, we treated five primary pulmonary hypertensive patients with captopril for four days. To ensure accuracy of haemodynamic and hormone data, the patients were studied under conditions of constant body posture, regulated dietary sodium and potassium intake, and unchanged diuretic therapy. Captopril reduced mean pulmonary arterial pressure in parallel with plasma angiotensin II levels. Right ventricular ejection fraction recordings increased considerably in three of four patients. Systemic arterial pressure fell, but there was no change in right atrial pressure, cardiac output, or heart rate. The decline in plasma (and urine) aldosterone levels presumably contributed to the positive cumulative potassium balance and the rise in plasma potassium (mean 0.7 mmol/1). These encouraging results suggest that converting enzyme inhibitors warrant a formal trial with prolonged follow up in the treatment of primary pulmonary hypertension.

Adult↗
PubMed1981

Haemodynamic, hormonal, and electrolyte responses to withdrawal of long-term captopril treatment for heart failure.

To determine whether temporary cessation of captopril therapy compromises cardiac performance, haemodynamic, hormonal, and electrolyte indices were measured for 2 days before, and 4 days after discontinuation of long-term captopril treatment in 5 patients with heart failure. Captopril withdrawal resulted in a four-fold rise in plasma angiotensin II, higher levels of noradrenaline, and a 13.5mmHg increase in mean arterial pressure. Despite there changes, cardiac output at rest and during exercise was well maintained, and right-heart pressures were unaltered. Although plasma aldosterone levels increased three-fold, neither sodium retention nor potassium depletion occurred. Cortisol levels rose in parallel with angiotensin II levels. These results indicate that in the short term cardiac performance is not impaired and electrolyte balance is not adversely affected by the abrupt withdrawal of captopril.

Aged↗
PubMed1981

Haemodynamic, hormonal, and electrolyte responses to captopril in resistant heart failure.

In five patients with resistant heart failure treated with the oral converting-enzyme inhibitor, captopril, standardised and intensive haemodynamic, hormone, and electrolyte monitoring showed significantly raised cardiac output and reduced arterial, pulmonary-wedge, and pulmonary-artery pressures which correlated closely with concomitant alterations in the activity of the renin-angiotensin system. These changes occurred in the absence of a natriuresis or diuresis. Clinical improvement was dramatic and paralleled the objective haemodynamic changes. Hyponatraemia and a rise in plasma-potassium were noted. Captopril is a major advance in the treatment of resistant heart failure, and its beneficial haemodynamic effects relate primarily to a blockade of the renin-angiotensin system, the activity of which is increased by conventional drug therapy.

Aged↗
PubMed1981

Haemodynamic effects of prostacyclin (PGI2) in pulmonary hypertension.

An infusion of prostacyclin (PGI2) in four patients with pulmonary hypertension resulted in a dose-related decrease in the systemic and pulmonary vascular resistance and an increase in cardiac output. No selectivity for the pulmonary vasculature was observed and the drug was not therapeutically beneficial.

Adult↗
PubMed1981

Haemodynamic effects of dobutamine in patients with congestive heart failure receiving captopril.

Treatment with captopril has proved effective in some patients with resistant heart failure. Since cardiac output responses to captopril treatment are generally small, we infused the positive inotropic agent dobutamine in six patients already receiving captopril to determine whether cardiac output could be augmented without concomitantly increasing myocardial oxygen demands. At low infusion rates of dobutamine (2.5 and 5 microgram/kg per min), a substantial rise in cardiac output was observed yet myocardial oxygen uptake remained well below baseline (pre-captopril/dobutamine) levels. At higher rates of infusion (10 and 20 microgram/kg per min) the rise in cardiac output was accompanied by a pronounced increase in myocardial oxygen uptake, and the appearance of chest pain or multifocal ventricular extrasystoles in three patients. These data indicate that captopril treatment combined with low infusion rates of dobutamine can augment cardiac output in the short term, without increasing myocardial oxygen demand.

Aged↗
PubMed1981

Angiotensin II is more potent than potassium in regulating aldosterone in cardiac failure: evidence during captopril therapy.

Potassium and angiotensin II are major regulators of aldosterone secretion. To assess which of these stimuli is the more potent, we measured aldosterone, potassium, and angiotensin II responses to the oral converting enzyme inhibitor captopril in five patients with resistant congestive heart failure during digoxin and furosemide maintenance therapy. In spite of a positive cumulative potassium balance and a clear-cut rise in plasma potassium, aldosterone levels in plasma and urine declined in parallel with levels of angiotensin II. When captopril treatment was later withdrawn in three patients, angiotensin II and aldosterone levels increased in parallel, while plasma potassium remained steady. The results show that under these study conditions, angiotensin II is more potent than potassium in regulating aldosterone in patients with heart failure.

Aged↗
PubMed1981

Cytomegalovirus infections in hemodialysis centers.

This study of 983 patients and 238 staff members of hemodialysis units shows that prevalence of complement fixing antibodies to cytomegalovirus (CMV) is higher in patients than in staff, it is higher in females than in males and increases with age. CMV antibody was more prevalent in black than white staff members but did not vary with socio-economic status or length of time on hemodialysis. Cytomegalovirus antibody response seems normal in patients with antibody to hepatitis B surface antigen and in patients negative for both hepatitis B surface antigen and antibody, but is poor in hepatitis B surface antigen carriers. This may be due to immunological deficiencies in the latter patients.

Adult↗
PubMed1981

The haemodynamic, histopathological and hormonal features of alcoholic cardiac beriberi.

Five cases of cardiac beriberi occurring in chronic alcoholics are described. The clinical diagnosis was based on the presence of biventricular failure, low dietary intake of thiamine and the therapeutic response to oral thiamine. Complicating cardiac disease was excluded by haemodynamic studies, left ventriculography; coronary angiography and endomyocardial biopsy. Haemodynamic measurements including quantitative left ventriculography are reported. They indicate that left ventricular function is depressed despite elevated cardiac output. Biopsy material was studied by light and electron microscopy. No lesion specific to beriberi was detected by either technique although the biopsies were quantitatively abnormal. The histological changes resemble those in early reports based on necropsy material, and consist of vacuolation and intercellular oedema in the early stages with myofibre hypertrophy, fibrosis and cellular infiltration in the chronic cases. The transketolase test and response to intravenous thiamine during catheter studies are valuable diagnostic tests. Plasma renin, angiotensin II and aldosterone levels were lower than in patients with low output heart failure. The incidence of cardiac beriberi appears to be greater than is generally realized.

Adult↗