Biomedical subjects

A M Yousof

Publications and source records attributed to A M Yousof.

At least 37 records · Page 2Linked to original sources

PubMed1987

Quantitative analysis of cardiac function: comparison of electro-cardiogram dual gated single photon emission tomography, planar radionuclide ventriculogram and contrast ventriculography in the determination of LV volume and ejection fraction.

A dual gated tomography (DGT) program for end systolic and end diastolic acquisition and subsequent processing for calculation of LVEF, end diastolic and end systolic volumes (EDV, ESV) has been evaluated in 20 healthy volunteers (25 years-40 years) and 45 patients (25 years-60 years): 20 with ischaemic heart disease and 25 with valvular heart disease (VHD). All had biplane multigated blood pool (MUGA) studies in the 40 degrees LAO projection using in vivo 99mTc- RBCs, immediately followed by DGT. The results in the patients group were correlated with contrast ventriculography (CV). In the volunteer group, the normal values for LVEF, EDV and ESV measured with DGT were found to be 63% +/- 10%, 91 ml +/- 6 ml and 30 ml +/- 6 ml and r value for the LVEF = 0.91 compared with MUGA. In the IHD group, r values compared with CV were 0.915 and 0.97 for the EDV and ESV and 0.934 for the LVEF. Compared with the MUGA, the r value for LVEF was 0.883. In the VHD group, r values were 0.98 for both the EDV and ESV and 0.948 for the LVEF (P less than 0.002) compared with CV and 0.789 for the LVEF compared with the MUGA. We feel that DGT is an accurate and reproducible technique for LV function measurements.

Adult↗

PubMed1987

Inotropic effects of ionic and nonionic contrast materials in isolated heart preparations.

The inotropic effects of ionic (amidotriazoate) and nonionic (iohexol) contrast material were compared in isolated rat heart preparations. Left atria exposed to amidotriazoate for 10 mins exhibited a dose dependent depression of contractile force approximately twice as large as that brought about by equiosmolar sucrose. When the driving rate was reduced from 60 to 20 beats/min, this specific effect was abolished. The spontaneously beating hearts perfused with amidotriazoate-containing medium had increased resting tension and depressed force of contractions. These effects tended to spontaneously normalize. Upon bolus administration of amidotriazoate the contractile force of perfused hearts was briefly depressed and heart rate, action potential duration and time to peak force decreased. Iohexol did not produce any significant changes in the contractile force. The experiments illustrated direct action of ionic contrast dye on cardiac inotropy probably resulting from an immediate, slowly compensated ionic imbalance, and demonstrated a definite superiority of the nonionic contrast material.

Animals↗

PubMed1986

The natural history of acute rheumatic fever in Kuwait: a prospective six year follow-up report.

One hundred and twenty-six children with the initial attack of acute rheumatic fever were followed up prospectively for 6 years. Sixty-six children maintained regular secondary prophylaxis (regular group) and 60 were irregular (irregular group). Two recurrences developed in the regular group with a recurrence rate of 0.005/patient/year follow-up, and 71 recurrences developed in the irregular group with a recurrence rate of 0.2/patient/year follow-up. These findings demonstrate the effect of secondary prophylaxis in reducing the frequency of recurrences. The prevalence rate of rheumatic heart disease in children who had carditis in the initial attack was 42% in the regular group vs 70% in the irregular group (p less than 0.05). These findings demonstrate the deleterious effect of recurrences in the evolution of rheumatic heart disease. The prevalence rate of rheumatic heart disease in children who maintained regular secondary prophylaxis, was 42% in those children who had carditis in the initial attack and 6% in those who had no carditis (p less than 0.05). These findings demonstrate the prognostic significance of presence or absence of carditis during the initial attack, in the subsequent evolution of rheumatic heart disease. The prevalence rate of rheumatic heart disease in the 66 children who maintained regular prophylaxis was 23%. Comparison of these data with those of similarly designed studies shows that the evolution of rheumatic heart disease following the initial attack of acute rheumatic fever, seems to behave similarly in the tropics and subtropics as it did in temperate climates.

Acute Disease↗

PubMed1986

The concurrent associations of group A streptococcal serotypes in children with acute rheumatic fever or pharyngitis-associated glomerulonephritis and their families in Kuwait.

A group of 146 children with acute rheumatic fever and 256 members from their families, and a group of 125 children with post-streptococcal glomerulonephritis and 199 family members, together with a group of 145 children with non-complicated group A streptococcal pharyngitis were examined over a period of three years. The purpose of the study was to explore the concurrent association and distribution of group A streptococcal serotypes among the three groups. Strains isolated from the children with non-complicated group A streptococcal pharyngitis represented the prevalent strains of group streptococci in the childhood community during the period of study. Rheumatic fever was encountered in a non epidemic situation. As expected, the recovery of group A streptococci was low. The strains however belonged mainly to two patterns, namely type M1 and M non-typable strains. Nephritis was pharyngitis-associated and occured also sporadically throughout the year. Types M12 and 49 accounted for the majority of the isolates. Type M12 accounted for 34.4% of the group A isolates from family members of children with nephritis and was totally absent in family members of children with rheumatic fever (p less than 0.001). The T pattern 8/25/Imp. 19 accounted for 40% of the group A isolates from family members of rheumatic patients compared to 3.3% from family members of nephritis patients (p less than 0.005). Data from this study show that the group A streptococcal serotypes, concurrently isolated from children with acute rheumatic fever and their families are disparately different from those of children with pharyngitis-associated glomerulonephritis and their families in the same population. These findings support the concept of "nephritogenicity" and "rheumatogenicity" and indicated the important role of the biological characteristics of the streptococcal serotypes in the aetiology of acute rheumatic fever and acute poststreptococcal glomerulonephritis.

Acute Disease↗

PubMed1986

Detection of antibodies to muramyl dipeptide, the adjuvant moiety of streptococcal cell wall, in patients with rheumatic fever.

The presence of antibodies to muramyl dipeptide (MDP), an adjuvant structure of streptococcal peptidoglycan, was investigated in patients with acute rheumatic fever (ARF). The detection of these antibodies was done by an enzyme-linked immunosorbent assay with a synthetic multivalent MDP conjugate as an antigen. Sera from 33 of 54 children with ARF had detectable levels of antibodies to MDP at the time of diagnosis. Such antibodies could only be detected in sera from two of 52 healthy children and one of 21 children with acute poststreptococcal glomerulonephritis. The specificity of the antibodies to MDP was demonstrated by inhibition, with free MDP, of binding of the sera to the MDP conjugate. The possible use of these antibodies in the diagnosis of ARF and in screening for safe synthetic muramyl peptides in immunization of humans is discussed.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1986

Asymptomatic severe aortic regurgitation in the young. Hemodynamic and angiographic data in 37 patients with echocardiographic correlation.

The aim of this study was to evaluate from hemodynamic and angiocardiographic (ACG) data the extent of left ventricular (LV) systolic dysfunction in a group of predominantly young (mean age 29 years) asymptomatic patients with severe aortic regurgitation (AR). In addition, echocardiography was performed and these data were correlated with ACG data and the value of these parameters in predicting LV dysfunction was tested. Thirty-seven patients were catheterized and 18 demonstrated LV dysfunction with an ejection fraction (EF) of less than 50%. These patients were classified as group A and the remaining 19 patients with EF greater or equal to 50% formed group B. While there was no difference between the 2 groups with regard to age or regurgitant fraction, the end-diastolic pressure was raised (p less than 0.01) and cardiac index depressed (p less than 0.05) significantly in group A. Of the echocardiographic parameters, the end-systolic diameter (ESD) correlated best with the EF (coefficient of correlation = -0.7 and p less than 0.001). In addition, the ESD was significantly higher in group A (p less than 0.001). When an ESD greater than or equal to 48 mm was used as a predictor of an EF less than 50% (group A) the sensitivity was 89% and the specificity 79%. In conclusion, many young asymptomatic patients with severe AR may have severe LV systolic dysfunction and an ESD greater than or equal to 48 mm is a good predictor of such a subgroup.

Adolescent↗

PubMed1986

Assessment of the severity of aortic stenosis: comparison of gradient and valve area.

Hemodynamic data, including simultaneously measured left ventricular pressure, aortic pressure, and cardiac output, were obtained in 17 patients with isolated valvar aortic stenosis, before and during infusion of dobutamine, isoprenaline, dopamine, and pacing. Infusion of sympathomimetic drugs resulted in a significant increase of both mean and peak systolic aortic valve gradient, cardiac output, heart rate, and systolic aortic valve flow per second. On the other hand, the calculated aortic valve area did not change significantly in spite of variable alterations of all values used for calculating aortic valve area and different causes of hemodynamic changes induced. Aortic valve area is considered a better indicator of the severity of aortic stenosis than is the aortic valve gradient and thus a more suitable indicator for operation.

Adolescent↗

PubMed1985

Tricuspid stenosis and regurgitation in rheumatic heart disease: a prospective cardiac catheterization study in 525 patients.

Cardiac catheterization (CC) was done in 525 symptomatic patients. Tricuspid regurgitation (TR) was graded from right ventricular (RV) angiography (RVA) and compared with RV indicator curves (IC). Tricuspid stenosis (TS) was diagnosed from the mean diastolic gradient (MDG). Organic (O) disease was diagnosed from TS or from thickening of the tricuspid valve (TV) on angiography. TR was found in 137 patients (26%), of whom 46 (33.5%) had additional TS. All of the patients with TS had significant TR. OTR was more frequent (70.4%) and more severe (p less than 0.0001) than functional TR (FTR). There was no difference in pulmonary artery pressure between FTR and OTR except when associated with TS. The TV was explored in 56 patients. A MDG greater than or equal to 2 mm Hg correctly predicted TS in 91% of the patients and right atrial angiography in 100% of the patients. Organic thickening of the TV was predicted in 84%.

Adult↗

PubMed1985

Prospective serological and clinical studies on infants born in Kuwait with an elevated IgM in cord blood.

Little is known about congenital viral and toxoplasmal infections in the developing countries. This study attempts to provide preliminary data on such infections among Arab mothers and infants in Kuwait. Babies born with an elevated IgM in cord blood were selected at birth and then studied prospectively during the first year of life for serological and clinical evidence of viral and toxoplasmal infections. There appeared to be a significant association between the elevation of total cord blood IgM and the selection of cases with cytomegalovirus infection. Demonstration of specific IgM in cord sera was attempted, whenever possible, to provide further evidence of congenital infection and to exclude early postnatal infections. In 18.5% of cases there was an association between serological evidence of infection and certain clinical abnormalities. Apart from cytomegalovirus and rubella virus, no evidence was found for congenital infection by other viruses or toxoplasma in this study.

Congenital Abnormalities↗

PubMed1985

Differences in electrical and mechanical recovery from ischemic heart arrest and cardioplegia.

The course of recovery of heart activity [assessed by heart rate, atrioventricular (AV) conduction time, monophasic action potentials, contractile force, and perfusion rate] from hypothermic ischemic arrest was studied on isolated perfused rat hearts. The effect of control ischemic arrest was compared with various cardioplegic protective formulations based on high K+ content. During control hypothermic ischemia (20 degrees C), the heart activity extinguished only gradually, action potentials were biphasic, AV conduction was extremely prolonged, and contractions were slow and relatively strong. On reperfusion (37 degrees C), the recovery of electrical activity was almost instantaneous and normalized within 2 min, whereas the contractile force remained substantially depressed. In contrast, K+-containing cardioplegic solutions stopped the heart within several cycles. Postarrest recovery was delayed and transitorily associated with severe arrhythmias (AV block, repetitive afterdepolarizations and oscillations during elevated plateau, and ventricular fibrillation). Nevertheless, the action potentials as well as the contractile force virtually normalized in 10-15 min. Procaine-containing cardioplegic solutions were ineffective in preventing the onset of postarrest reperfusion arrhythmias, whereas addition of nifedipine to the K+-containing cardioplegic solutions largely prevented these arrhythmias, and contractile force was further improved by high concentrations of glucose. The data indicate that postarrest electrical and mechanical recovery do not recover in parallel. Furthermore, high concentrations of calcium antagonist and glucose preserve the electrical and mechanical properties of the cardiac muscle during periods of cardiac arrest.

Animals↗

PubMed1984

Recurrences of acute rheumatic fever. A prospective study of 79 episodes.

Fifty-three patients with acute rheumatic fever and 79 recurrences were studied prospectively for six years. All the patients were examined by the same physicians during their initial attack, as well as during recurrences. Of the 27 patients with carditis in the initial attack, all had persistence of cardiac involvement during subsequent recurrences, and some additional involvement developed. Of the 26 patients without carditis in the initial attack, only two patients who initially had pure chorea also had chorea and carditis in recurrences. These data strongly support the concept that if the host escapes carditis in the initial attack, he/she will continue to do so in subsequent recurrences; however, if the heart is involved in the initial attack, recurrences can inflict further cardiac damage. In view of these findings, the current approach to prophylaxis should probably be modified.

Acute Disease↗

PubMed1984

Acute rheumatic fever below the age of five years: a prospective study of the clinical profile.

The clinical profile of acute rheumatic fever below the age of five years was studied prospectively in 53 children seen over a period of seven years. The majority presented with pain in the joints, manifested as arthritis in 81% and arthralgia in 15%. Four per cent presented with congestive heart failure. Carditis developed in 42%, with a high incidence of pericarditis (6%) and congestive heart failure (15%) and a mortality of 2%. The incidence of Erythema marginatum was 2%, while chorea and subcutaneous nodules were not seen. Data from this prospective study, when compared with those of other prospective studies of acute rheumatic fever throughout childhood, clearly show a similar incidence of arthritis and carditis with a slightly more aggressive nature of carditis in children under five years. These findings are in marked contrast to recent reports describing the clinical profile of acute rheumatic fever in this age group.

Acute Disease↗

PubMed1984

Pulmonary function before and sequentially after valve replacement surgery with correlation to preoperative hemodynamic data.

Hemodynamic results after valve replacement surgery are well documented, but there are few follow-up studies on pulmonary function. Pulmonary function and hemodynamic studies were made, preoperatively, in 149 patients with predominant, mitral, aortic or combined mitral and aortic stenosis. A sequential postoperative follow-up of the pulmonary function was performed on 88 patients for as long as 125 wk after valve replacement. All patients had reduced preoperative values for forced vital capacity (FVC), single-breath carbon monoxide diffusing capacity (DLCO), forced expiratory volume in one second, peak expiratory flow rate, and maximal flow after exhalation of 75, 50, and 25% of FVC, and increased total airway resistance, resistance during expiration, and residual volume. The aortic group tended toward more normal values. There was significant correlation between the pulmonary function parameters and the hemodynamic data. In the early postoperative period (10 wk), deterioration of pulmonary function was significant in the aortic group and variable in the mitral and the combined groups; these responses correlated with preoperative hemodynamic and pulmonary function status. Between 10 to 125 wk, all patients showed progressive improvement, especially among those in the mitral group. Patients who died during or soon after mitral valve replacement were found to have significantly lower FVC and DLCO and significantly higher peripheral vascular resistance and cardiothoracic ratio. It is concluded that deterioration in pulmonary function is correlated to severity of cardiac dysfunction, and is reversible late after surgery, except in very advanced cases that have poor prognosis.

Adolescent↗

PubMed1983

Catheter for visualization of patent ductus arteriosus.

We have developed a new catheter for transvenous angiography in patent ductus arteriosus (PDA) that has given excellent results in 31 patients (age range seven months to 17 years). Optimal selective opacification of PDA is due to maintaining the catheter side holes in close proximity to the PDA and to rapid delivery of relatively large volumes of contrast medium into the ampulla of the PDA without the catheter recoiling. The venous route of catheter insertion precludes possible arterial injury.

Cardiac Catheterization↗

PubMed1983

Vascular effects of potassium cardioplegic solutions.

Experiments have been performed on isolated human umbilical and sheep coronary arteries, studying the effects of increasing potassium concentration in steps from 10 to 160 mM. Comparative studies were also done on rat-heart papillary-muscle preparations. The results revealed a dose-dependent increase in smooth muscle tone of the blood vessels. Maximal contraction was reached at 80 mM K+. Papillary-muscle preparations showed a dose-dependent decrease in contractile activity. Complete stoppage of contractile activity was observed at 30 mM K+. The corresponding increase in the vascular smooth muscle tone at 30 mM K+ was 10-25%, showing that vascular smooth muscle cells are less easily affected by increasing K+ than the heart. Further confirmation of the results were obtained by exposing the preparations (papillary muscle and arteries) to a locally-developed depolarizing K+-cardioplegic solution.

Animals↗

PubMed1983

Seroepidemiology of viral and toxoplasmal infections during pregnancy among Arab women of child-bearing age in Kuwait.

Five hundred and seventy three of 606 (94.6%), 583 of 604 (96.5%) and 575 of 595 (96.6%) women were found to have antibody to rubella virus, cytomegalovirus and herpes simplex virus, respectively. The Geometric Mean Titre (GMT) of haemagglutination-inhibition antibody to rubella virus was 60.97, while the GMT of complement-fixation antibody to cytomegalovirus and herpes simplex virus were 28.49 and 25.01, respectively. Furthermore, 301 of 517 (58.2%) women were also found to possess antibody to toxoplasma (GMT = 10.12) as detected by the passive-haemagglutination test. No significant differences in antibody prevalence or GMT could be found among the various nationalities studied except among Bedouins who showed a significantly higher rate and GMT of antibody to rubella virus and for the Mediterranean Arabs who showed significantly higher rate of immunity to and GMT of toxoplasma antibody when compared to other nationalities. Finally, no significant differences in antibody prevalence or GMT could be found among the various age groups.

Adolescent↗

PubMed1982

The antistreptococcal immune responses in children with acute rheumatic fever in Kuwait.

The antistreptococcal immune responses in 130 children with Acute Rheumatic Fever (ARF), seen in Kuwait, over a period of three years, are presented. The ages of children ranged between three to 13 years. One hundred and three presented in initial attacks while 27 presented in recurrences. The geometric mean of antistreptolysin 'O' (ASO) and antihyalurodinase (AH) titres for all patients were 488 Todd Units and 595 units, respectively. In children under the age of eight years, but not above this age, the geometric mean of ASO titres was significantly higher in children with carditis than in those without carditis (P less than 0.01); there was no significant difference in AH titres between the two groups. Analysis of the Geometric Mean Titres (GMT) of both antibodies in relation to other variables is also presented.

Acute Disease↗

PubMed1982

Hemolytic streptococci and streptococcal antibodies in normal schoolchildren in Kuwait.

A total of 1041 asymptomatic "normal" schoolchildren in Kuwait, aged 6-16 years, were investigated over six months from November 1978 through April 1979 for hemolytic streptococcal throat carriage and for streptococcal immune response. A high carrier rate of beta-hemolytic streptococci (47%) with an unusually high prevalence of group C (32%) was found. Group A was isolated in 10%, group B in 2%, and group G in 3% of the children. Comparison of the prevalence of the different serogroups of beta-hemolytic streptococci in our study with that of similar studies reported from temperate, subtropical, and tropical zones showed a high prevalence of groups C and G and a lower prevalence of group A in subtropical and tropical countries in contrast to a high prevalence of group A and lower prevalence of groups C and G in countries with temperate climate. The geometric mean titer of antistreptolysin O in group A carriers in our study was 270 Todd units and significantly higher than that in group C carriers (p less than 0.001), while the geometric mean titer of antihyaluronidase in group A carriers was 240 units and significantly higher than that in groups B, C, and G carriers (p less than 0.0005). The high magnitude of the streptococcal immune response probably reflects a high frequency of streptococcal infections in schoolchildren in Kuwait and possibly indicates a high attack rate of rheumatic fever in the country.

Adolescent↗