Salah Eldin Kassab - Academia.edu (original) (raw)

Papers by Salah Eldin Kassab

Research paper thumbnail of Measuring sociocultural engagement of health professions education students: a psychometric study

BMC medical education, May 23, 2024

Research paper thumbnail of Role of Renal Nerves in Mediating the Blunted Natriuretic Response to Acute Saline Load in Obese Dogs

American Journal of Hypertension, Mar 1, 1997

We previously reported that the natriuretic from 43.1 { 10.6 to 151.1 { 28.4 mEq /min in the DNX ... more We previously reported that the natriuretic from 43.1 { 10.6 to 151.1 { 28.4 mEq /min in the DNX kidneys. In contrast, U Na V in obese dogs response to an acute sodium load is markedly attenuated in obese dogs. Since obesity is increased from 10.3 { 3.0 to 110.1 { 25.5 mEq /min in the INN kidneys and from 24.4 { 2.7 to 106.1 { associated with enhanced sympathetic nervous activity, the purpose of this study was to test the 20.6 mEq /min in the DNX kidneys. Cumulative sodium excretory response to sodium loading was hypothesis that obese animals have a reduced ability to excrete a sodium load as a result of significantly lower in the obese dogs. In addition, there was no difference in the cumulative U Na V abnormal renal nerve function. To test this hypothesis, we determined the effects of an acute response between the INN (8.4 { 2.2 mEq) and DNX kidneys (9.1 { 2.3 mEq) of obese dogs. sodium load (100 mEq NaCl given as isotonic saline over 60 min) in lean (19.8 { 1.0 kg) and These data indicate that the natriuretic response to an acute saline loading is markedly attenuated obese (25.8 { 1.1 kg) dogs. Two surgically designed hemibladders with indwelling catheters in obese dogs. Furthermore, factors other than renal nerves play a role in this abnormal were used to collect urine from innervated (INN) and denervated (DNX) kidneys of the same dog. response. ᭧ 1997 American Journal of Hypertension, Ltd. Am J Hypertens 1997; 10:315-Arterial pressure averaged 99 { 3 mm Hg in the obese dogs and 90 { 3 mm Hg in the lean dogs. 322 In response to the saline loading in lean dogs, sodium excretion (U Na V) increased from 31.0 { 7.8 KEY WORDS: Obesity, renal sympathetic nervous system, hypertension, dog. to 145.6 { 25.9 mEq /min in the INN kidneys and

Research paper thumbnail of Association of methylenetetrahydrofolate reductase (C677T) polymorphism with hyperuricemia

Nutrition Metabolism and Cardiovascular Diseases, Jul 1, 2007

Background and aimsHomozygosity for the thermolabile variant of 5,10-methylene tetrahydrofolate r... more Background and aimsHomozygosity for the thermolabile variant of 5,10-methylene tetrahydrofolate reductase (C677T) has been suggested to be positively associated with the risk of vascular disease and neural tube defects. In addition, recent studies have suggested that elevated serum uric acid predicts ischemic heart disease, and epidemiological data on ethnic groups have suggested that genetic factors are determinants of serum uric acid levels. In this study, we tested the hypothesis that 5,10-methylenetetrahydrofolate reductase (C677T) polymorphism may be associated with hyperuricemia.

Research paper thumbnail of The Effect Of Access To Electronic Resources On Medical and Dental Students Scores In Summative Assessment: quasi experimental study

Research Square (Research Square), May 19, 2022

Background Access to electronic (E) resources has become an indispensable requirement in medical ... more Background Access to electronic (E) resources has become an indispensable requirement in medical education and practice.

Research paper thumbnail of Differential Expression of Renal Nitric Oxide Synthase Isoforms During Pregnancy in Rats

Hypertension, 1999

Alterations in nitric oxide (NO) production have been suggested to play a role in mediating chang... more Alterations in nitric oxide (NO) production have been suggested to play a role in mediating changes in renal function during normal pregnancy and in pregnancy-induced hypertension. Although NO production is enhanced during normal pregnancy, the mechanisms for the increase are unknown. The purpose of this study was to determine whether the elevation in NO production during pregnancy is associated with increases in renal expression of endothelial (eNOS), inducible (iNOS), and neuronal (nNOS) nitric oxide synthases. To achieve this goal we examined systemic and renal hemodynamics, urinary excretion of nitrate/nitrite, and renal protein expression of the three NOS isoforms in prepregnant rats, pregnant rats at days 6, 13, and 19 of gestation and at day 4 postpartum. Mean arterial pressure decreased by 14% in late pregnancy whereas the glomerular filtration rate and renal plasma flow increased by 21% and 24%, respectively, in mid pregnancy. Excretion of nitrate/nitrite increased throughout pregnancy with a 3.4-fold increase present at day 19 (12.2Ϯ0.7 to 41.1Ϯ1.3 mol/24 h). Renal eNOS protein expression decreased by 39% during pregnancy with the lowest level resulting at day 19 and returning to virgin levels by day 4 post partum. In contrast, renal iNOS and nNOS protein expression increased 31% and 25%, respectively, with highest expression occurring for both at day 13 of pregnancy. These data suggest that the increased NO production and renal hemodynamics associated with pregnancy in rats may be caused by the upregulation of iNOS and nNOS in the kidney. (Hypertension. 1999;33[part II]:435-439.

Research paper thumbnail of Endothelin-A Receptor Antagonism Attenuates the Hypertension and Renal Injury in Dahl Salt-Sensitive Rats

Hypertension, 1998

The aim of this study was to examme the role of endothehn-A (ET,) receptors m mediating the hyper... more The aim of this study was to examme the role of endothehn-A (ET,) receptors m mediating the hypertension and renal qury associated with high salt intake m Dahl salt-sensltlve (DS) rats To achieve this goal, we examined the effects of chronic selective ETA antagonist (A-127722) treatment at a dose of 10 mg/kg/d on arterial pressure, renal function, and morphology m DS and Dahl salt-reslstant (DR) rats placed on a high sodmm (8% NaCl) diet (HSD) for 3 weeks Placement of DS rats (n=l3) on HSD for 3 weeks caused a progressive increase m systolic pressure (from 118 +3 to 1862 15 mm Hg) The mcrease m systohc pressure was slgmficantly attenuated (from 125+4 to 167t 12 mm Hg) m DS rats treated with A-127722 (n= 13) Mean arterial pressure (MAP) measured directly at the end of the study was also slgmficantly lower by 18 mm Hg (P< 02) m the DS rats treated with A-127722 The slope of the chronic pressure-natnuresls curve was shlfted to the right m DS rats and to the left by chronic ETA receptor blockade m DS rats The hypertension m DS rats was associated with marked protemurla (from 4 I+ 1 1 to 74 3t-5 3 mg/24 h/l00 g body weight) that was slgmficantly attenuated (from 5 721 2 to 55 226 5 mg/24 h/100 g body weight) m DS rats treated with A-127722 The percentage of glomeruh dlsplaymg fibrons, hypercellulanty, and hyalmlzatlon was also slgmficantly reduced after treatment with A-127722 m DS rats Arterial pressure, protein excretion, renal hemodynanucs, and morphologc structure were not slgmficandy changed m response to ETA receptor blockade m DR rats placed on HSD These data indicate that endothehn-A receptor actlvatlon may play a role m the exacerbation of hypertension and development of renal injury m DS rats (Hy2lertension. 1998;31[part 2]:397-402.

Research paper thumbnail of Role of nitric oxide in modulating renal function and arterial pressure during chronic aldosterone excess

American Journal of Physiology-regulatory Integrative and Comparative Physiology, 1999

Role of nitric oxide in modulating renal function and arterial pressure during chronic aldosteron... more Role of nitric oxide in modulating renal function and arterial pressure during chronic aldosterone excess. Am. J. Physiol. 276 (Regulatory Integrative Comp. Physiol. 45): R197-R202, 1999.-Chronic aldosterone (Aldo) excess is associated with transient sodium retention, extracellular fluid volume expansion, renal vasodilation, and hypertension. The purpose of this study was to determine the role of nitric oxide (NO) in mediating the renal vasodilation and the escape from the sodium-retaining actions of Aldo. To achieve this goal, we examined the long-term effects of Aldo (15 µg • kg Ϫ1 • min Ϫ1 for 7 days) in conscious, chronically instrumented control dogs (n ϭ 9) and in dogs (n ϭ 12) pretreated with the NO synthesis inhibitor N G-nitro-L-arginine methyl ester (L-NAME; 10 µg•kg Ϫ1 • min Ϫ1). In control dogs, Aldo caused a transient sodium retention (126 Ϯ 6 to 56 Ϯ 2 meq/day) followed by a return of sodium excretion to normal levels. Aldo also increased renal plasma flow by 15% (205 Ϯ 13 to 233 Ϯ 16 ml/min), glomerular filtration rate by 20% (72 Ϯ 3 to 87 Ϯ 5 ml/min), and arterial pressure from 90 Ϯ 3 to 102 Ϯ 3 mmHg. Aldo increased urinary nitrate/nitrite excretion by 60% in the control dogs. Although the sodium-retaining (144 Ϯ 7 to 56 Ϯ 7 meq/day) and arterial pressure (122 Ϯ 6 to 136 Ϯ 5 mmHg) responses to Aldo were the same in dogs pretreated with L-NAME compared with control, the renal hemodynamic response was markedly attenuated. The results of this study suggest that NO plays an important role in mediating the renal vasodilation during chronic Aldo excess.

Research paper thumbnail of Mechanisms of Obesity-Induced Hypertension

Physiology, Dec 1, 1996

Obesity is a major cause of human essential hypertension. Recent studies point toward increased r... more Obesity is a major cause of human essential hypertension. Recent studies point toward increased renal tubular reabsorption and abnormal renal pressure natriuresis in mediating obesity hypertension. The mechanisms for these renal changes appear to be multifactorial, including activation of the sympathetic nervous system and altered intrarenal histology, which compresses the renal medulla.

Research paper thumbnail of Chronic endothelin-induced pressor and renal actions in conscious dogs do not require altered ANG II formation

American Journal of Physiology-regulatory Integrative and Comparative Physiology, Feb 1, 1995

Plasma endothelin levels are elevated approximately two- to threefold in a number of chronic path... more Plasma endothelin levels are elevated approximately two- to threefold in a number of chronic pathophysiological conditions associated with hypertension. Results from recent studies indicate an important interaction between endothelin and the renin-angiotensin system (RAS). The role of the RAS in mediating the increases in arterial pressure produced by long-term pathophysiological elevations in circulating levels of endothelin is unknown. Therefore, the purpose of this study was to chronically increase circulating levels of endothelin within the pathophysiological range and determine the long-term cardiovascular and renal actions of endothelin in control dogs (n = 6) and in dogs pretreated with a converting-enzyme inhibitor (CEI) (n = 6) or CEI + angiotensin II (ANG II) replacement (n = 6). Infusion of endothelin-1 for 8 days at a rate of 2.5 ng.kg-1.min-1 increased plasma endothelin from 7.1 +/- 0.9 to 19.8 +/- 3.3 pg/ml. In control dogs, endothelin increased mean arterial pressure (MAP) by 19% (90 +/- 2 to 107 +/- 3 mmHg) while decreasing renal blood flow (RBF) by 30% and glomerular filtration rate (GFR) by 15-20%. Long-term elevation of circulating endothelin produced similar elevations in MAP in dogs pretreated with CEI (+16%) or CEI + ANG II (+17%). Similar decreases in RBF and GFR also occurred in response to endothelin in all three groups. These results indicate that although long-term increases in circulating endothelin within the pathophysiological range produce significant increases in arterial pressure, this effect does not appear to be mediated by the RAS.

Research paper thumbnail of Decreased sensitivity to renal interstitial hydrostatic pressure in Dahl salt-sensitive rats

Hypertension, Jun 1, 1994

The ability of Dahl salt-sensitive (DS) rats to excrete a sodium load is significantly lower than... more The ability of Dahl salt-sensitive (DS) rats to excrete a sodium load is significantly lower than Dahl salt-resistant (DR) rats. Because renal interstitial hydrostatic pressure (RIHP) is a major mediator of natriuresis in response to a sodium load, we proposed that the renal tubules of DS rats are less responsive to increases in RIHP than those of DR rats. To test this hypothesis, we determined the effect of direct increases in RIHP on renal excretory function in prehypertensive DS and DR rats. RIHP was directly increased by renal interstitial volume expansion via injection of 50 JAL of a 2% albumin and saline solution into the renal interstitium through a chronically implanted renal interstitial catheter. RIHP, mean arterial pressure, glomerular filtration rate, urine flow rate, urinary sodium excretion, and fractional excretions of sodium, potassium, and lithium (an indicator of proximal tubule sodium handling) were measured before and after direct increases in RIHP in DS (n=8) and DR (n=8) rats. Baseline urine flow rate; urinary sodium excretion; fractional excretions of sodium, potassium, and lithium; RIHP; mean arterial pressure; and glomerular filtration rate were not different between DS and DR rats. Renal interstitial volume expansion in DS rats significantly increased RIHP (A4.7±0.8 mm Hg), urine flow rate (A14.5±3.4 jtL/min), urinary sodium excretion

Research paper thumbnail of Role of nitric oxide in modulating the chronic hypertension produced by pathophysiological increases in circulating endothelin

The FASEB Journal, Mar 24, 1994

Research paper thumbnail of Construct validity of a questionnaire for measuring student engagement in problem-based learning tutorials

BMC Medical Education

Background Student engagement is student investment of time and energy in academic and non-academ... more Background Student engagement is student investment of time and energy in academic and non-academic experiences that include learning, teaching, research, governance, and community activities. Although previous studies provided some evidence of measuring student engagement in PBL tutorials, there are no existing quantitative studies in which cognitive, behavioral, and emotional engagement of students in PBL tutorials is measured. Therefore, this study aims to develop and examine the construct validity of a questionnaire for measuring cognitive, behavioral, and emotional engagement of students in PBL tutorials. Methods A 15-item questionnaire was developed guided by a previously published conceptual framework of student engagement. Focus group discussion (n = 12) with medical education experts was then conducted and the questionnaire was piloted with medical students. The questionnaire was then distributed to year 2 and 3 medical students (n = 176) in problem-based tutorial groups at...

Research paper thumbnail of Measuring medical students’ professional competencies in a problem-based curriculum: a reliability study

BMC Medical Education, May 21, 2019

Background: Identification and assessment of professional competencies for medical students is ch... more Background: Identification and assessment of professional competencies for medical students is challenging. We have recently developed an instrument for assessing the essential professional competencies for medical students in Problem-Based Learning (PBL) programs by PBL tutors. This study aims to evaluate the reliability and validity of professional competency scores of medical students using this instrument in PBL tutorials. Methods: Each group of seven to eight students in PBL tutorials (Year 2, n = 46) were assessed independently by two faculty members. Each tutor assessed students in his/her group every five weeks on four occasions. The instrument consists of ten items, which measure three main competency domains: interpersonal, cognitive and professional behavior. Each item is scored using a five-point Likert scale (1 = poor, 5 = exceptional). Reliability of professional competencies scores was calculated using G-theory with raters nested in occasions. Furthermore, criterion-related validity was measured by testing the correlations with students' scores in written examination. Results: The overall generalizability coefficient (G) of the professional competency scores was 0.80. Students' professional competencies scores (universe scores) accounted for 27% of the total variance across all score comparisons. The variance due to occasions accounted for 10%, while the student-occasion interaction was zero. The variance due to raters to occasions represented 8% of the total variance, and the remaining 55% of the variance was due to unexplained sources of error. The highest reliability measured was the interpersonal domain (G = 0.84) and the lowest reliability was the professional behavior domain (G = 0.76). Results from the decision (D) study suggested that an adequate dependability (G = 0.71) can be achieved by using one rater for five occasions. Furthermore, there was a positive correlation between the written examination scores and cognitive competencies scores (r = 0.46, P < 0.01), but not with the other two competency domains (interpersonal and professionalism). Conclusions: This study demonstrates that professional competency assessment scores of medical students in PBL tutorials have an acceptable reliability. Further studies for validating the instrument are required before using it for summative evaluation of students by PBL tutors.

Research paper thumbnail of Generalisability theory analyses of concept mapping assessment scores in a problem-based medical curriculum

Medical Education, 2016

In problem-based learning (PBL), students construct concept maps that integrate different concept... more In problem-based learning (PBL), students construct concept maps that integrate different concepts related to the PBL case and are guided by the learning needs generated in small-group tutorials. Although an instrument to measure students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; concept maps in PBL programmes has been developed, the psychometric properties of this instrument have not yet been assessed. This study evaluated the generalisability of and sources of variance in medical students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; concept map assessment scores in a PBL context. Medical students (Year 4, n = 116) were asked to construct three integrated concept maps in which the content domain of each map was to be focused on a PBL clinical case. Concept maps were independently evaluated by four raters based on five criteria: valid selection of concepts; hierarchical arrangement of concepts; degree of integration; relationship to the context of the problem, and degree of student creativity. Generalisability theory was used to compute the reliability of the concept map scores. The dependability coefficient, which indicates the reliability of scores across the measured facets for making absolute decisions, was 0.814. Students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; concept map scores (universe scores) accounted for the largest proportion of total variance (47%) across all score comparisons. Rater differences accounted for 10% of total variance, and the student × rater interaction accounted for 25% of total variance. The variance attributable to differences in the content domain of the maps was negligible (2%). The remaining 16% of the variance reflected unexplained sources of error. Results from the D study suggested that a dependability level of 0.80 can be achieved by using three raters who each score two concept map domains, or by using five raters who each score only one concept map domain. This study demonstrated that concept mapping assessment scores of medical students in PBL have high reliability. Results suggested that greater improvements in dependability might be made by increasing the number of raters rather than by increasing the number of concept map domains.

Research paper thumbnail of Undergraduate medical education in the Gulf Cooperation Council: A multi-countries study (Part 1)

Research paper thumbnail of Good advice from authors working in under‐represented countries

Research paper thumbnail of Student engagement in health professions education: AMEE Guide No. 152

Research paper thumbnail of Measurement of student engagement in health professions education: a review of literature

BMC Medical Education

Student engagement is a complex multidimensional construct that has attained great interest in he... more Student engagement is a complex multidimensional construct that has attained great interest in health professions education (HPE). Definition and conceptualization of student engagement is an important step that should drive the development of the instruments for its measurement. We have recently proposed a comprehensive framework for student engagement in HPE with a definition of engagement as student investment of time and energy in academic and non-academic experiences that include learning, teaching, research, governance, and community activities. The dimensions of student engagement in this framework included the cognitive, affective, behavioral, agentic, and socio-cultural. Guided by the student engagement framework, this non-systematic review aims to identify, critically appraise, and summarize the existing methods for measuring student engagement in HPE. Extrapolating from higher education literature, we attempted to link the theoretical perspectives of student engagement wi...

Research paper thumbnail of Designing and Piloting a Professionalism Curriculum for Undergraduate Medical Students at the Faculty of Medicine, Suez Canal University

Suez Canal University Medical Journal

Research paper thumbnail of The effect of access to electronic resources during examination on medical and dental students scores in summative assessment: quasi experimental study

BMC Medical Education

Background Access to electronic (E) resources has become an indispensable requirement in medical ... more Background Access to electronic (E) resources has become an indispensable requirement in medical education and practice. Objective Our objective was to assess the effect of E-resources access during examination on end-course-exam scores of medical and dental students. Methods A quasi-experimental study which included two cohorts of medical (n = 106 & 85) and three cohorts of dental students (n = 66, 64 and 69) who took end-course- exams. Each exam was composed of two- parts (Part I and II), that encompassed equal number of questions and duration. Access to E-resources was allowed in part-II only. Items Difficulty Index (DI), Discrimination Index, (DisI), Point Biserial, (PBS) and cognitive level were determined. Results The study included 390 students. The proportion of items at various levels of DI, DisI, and PBS and the average values for item DI, DisI in both parts of each exam were comparable. The average scores in part-II were significantly higher than part-I (P < 0.001, &lt...

Research paper thumbnail of Measuring sociocultural engagement of health professions education students: a psychometric study

BMC medical education, May 23, 2024

Research paper thumbnail of Role of Renal Nerves in Mediating the Blunted Natriuretic Response to Acute Saline Load in Obese Dogs

American Journal of Hypertension, Mar 1, 1997

We previously reported that the natriuretic from 43.1 { 10.6 to 151.1 { 28.4 mEq /min in the DNX ... more We previously reported that the natriuretic from 43.1 { 10.6 to 151.1 { 28.4 mEq /min in the DNX kidneys. In contrast, U Na V in obese dogs response to an acute sodium load is markedly attenuated in obese dogs. Since obesity is increased from 10.3 { 3.0 to 110.1 { 25.5 mEq /min in the INN kidneys and from 24.4 { 2.7 to 106.1 { associated with enhanced sympathetic nervous activity, the purpose of this study was to test the 20.6 mEq /min in the DNX kidneys. Cumulative sodium excretory response to sodium loading was hypothesis that obese animals have a reduced ability to excrete a sodium load as a result of significantly lower in the obese dogs. In addition, there was no difference in the cumulative U Na V abnormal renal nerve function. To test this hypothesis, we determined the effects of an acute response between the INN (8.4 { 2.2 mEq) and DNX kidneys (9.1 { 2.3 mEq) of obese dogs. sodium load (100 mEq NaCl given as isotonic saline over 60 min) in lean (19.8 { 1.0 kg) and These data indicate that the natriuretic response to an acute saline loading is markedly attenuated obese (25.8 { 1.1 kg) dogs. Two surgically designed hemibladders with indwelling catheters in obese dogs. Furthermore, factors other than renal nerves play a role in this abnormal were used to collect urine from innervated (INN) and denervated (DNX) kidneys of the same dog. response. ᭧ 1997 American Journal of Hypertension, Ltd. Am J Hypertens 1997; 10:315-Arterial pressure averaged 99 { 3 mm Hg in the obese dogs and 90 { 3 mm Hg in the lean dogs. 322 In response to the saline loading in lean dogs, sodium excretion (U Na V) increased from 31.0 { 7.8 KEY WORDS: Obesity, renal sympathetic nervous system, hypertension, dog. to 145.6 { 25.9 mEq /min in the INN kidneys and

Research paper thumbnail of Association of methylenetetrahydrofolate reductase (C677T) polymorphism with hyperuricemia

Nutrition Metabolism and Cardiovascular Diseases, Jul 1, 2007

Background and aimsHomozygosity for the thermolabile variant of 5,10-methylene tetrahydrofolate r... more Background and aimsHomozygosity for the thermolabile variant of 5,10-methylene tetrahydrofolate reductase (C677T) has been suggested to be positively associated with the risk of vascular disease and neural tube defects. In addition, recent studies have suggested that elevated serum uric acid predicts ischemic heart disease, and epidemiological data on ethnic groups have suggested that genetic factors are determinants of serum uric acid levels. In this study, we tested the hypothesis that 5,10-methylenetetrahydrofolate reductase (C677T) polymorphism may be associated with hyperuricemia.

Research paper thumbnail of The Effect Of Access To Electronic Resources On Medical and Dental Students Scores In Summative Assessment: quasi experimental study

Research Square (Research Square), May 19, 2022

Background Access to electronic (E) resources has become an indispensable requirement in medical ... more Background Access to electronic (E) resources has become an indispensable requirement in medical education and practice.

Research paper thumbnail of Differential Expression of Renal Nitric Oxide Synthase Isoforms During Pregnancy in Rats

Hypertension, 1999

Alterations in nitric oxide (NO) production have been suggested to play a role in mediating chang... more Alterations in nitric oxide (NO) production have been suggested to play a role in mediating changes in renal function during normal pregnancy and in pregnancy-induced hypertension. Although NO production is enhanced during normal pregnancy, the mechanisms for the increase are unknown. The purpose of this study was to determine whether the elevation in NO production during pregnancy is associated with increases in renal expression of endothelial (eNOS), inducible (iNOS), and neuronal (nNOS) nitric oxide synthases. To achieve this goal we examined systemic and renal hemodynamics, urinary excretion of nitrate/nitrite, and renal protein expression of the three NOS isoforms in prepregnant rats, pregnant rats at days 6, 13, and 19 of gestation and at day 4 postpartum. Mean arterial pressure decreased by 14% in late pregnancy whereas the glomerular filtration rate and renal plasma flow increased by 21% and 24%, respectively, in mid pregnancy. Excretion of nitrate/nitrite increased throughout pregnancy with a 3.4-fold increase present at day 19 (12.2Ϯ0.7 to 41.1Ϯ1.3 mol/24 h). Renal eNOS protein expression decreased by 39% during pregnancy with the lowest level resulting at day 19 and returning to virgin levels by day 4 post partum. In contrast, renal iNOS and nNOS protein expression increased 31% and 25%, respectively, with highest expression occurring for both at day 13 of pregnancy. These data suggest that the increased NO production and renal hemodynamics associated with pregnancy in rats may be caused by the upregulation of iNOS and nNOS in the kidney. (Hypertension. 1999;33[part II]:435-439.

Research paper thumbnail of Endothelin-A Receptor Antagonism Attenuates the Hypertension and Renal Injury in Dahl Salt-Sensitive Rats

Hypertension, 1998

The aim of this study was to examme the role of endothehn-A (ET,) receptors m mediating the hyper... more The aim of this study was to examme the role of endothehn-A (ET,) receptors m mediating the hypertension and renal qury associated with high salt intake m Dahl salt-sensltlve (DS) rats To achieve this goal, we examined the effects of chronic selective ETA antagonist (A-127722) treatment at a dose of 10 mg/kg/d on arterial pressure, renal function, and morphology m DS and Dahl salt-reslstant (DR) rats placed on a high sodmm (8% NaCl) diet (HSD) for 3 weeks Placement of DS rats (n=l3) on HSD for 3 weeks caused a progressive increase m systolic pressure (from 118 +3 to 1862 15 mm Hg) The mcrease m systohc pressure was slgmficantly attenuated (from 125+4 to 167t 12 mm Hg) m DS rats treated with A-127722 (n= 13) Mean arterial pressure (MAP) measured directly at the end of the study was also slgmficantly lower by 18 mm Hg (P< 02) m the DS rats treated with A-127722 The slope of the chronic pressure-natnuresls curve was shlfted to the right m DS rats and to the left by chronic ETA receptor blockade m DS rats The hypertension m DS rats was associated with marked protemurla (from 4 I+ 1 1 to 74 3t-5 3 mg/24 h/l00 g body weight) that was slgmficantly attenuated (from 5 721 2 to 55 226 5 mg/24 h/100 g body weight) m DS rats treated with A-127722 The percentage of glomeruh dlsplaymg fibrons, hypercellulanty, and hyalmlzatlon was also slgmficantly reduced after treatment with A-127722 m DS rats Arterial pressure, protein excretion, renal hemodynanucs, and morphologc structure were not slgmficandy changed m response to ETA receptor blockade m DR rats placed on HSD These data indicate that endothehn-A receptor actlvatlon may play a role m the exacerbation of hypertension and development of renal injury m DS rats (Hy2lertension. 1998;31[part 2]:397-402.

Research paper thumbnail of Role of nitric oxide in modulating renal function and arterial pressure during chronic aldosterone excess

American Journal of Physiology-regulatory Integrative and Comparative Physiology, 1999

Role of nitric oxide in modulating renal function and arterial pressure during chronic aldosteron... more Role of nitric oxide in modulating renal function and arterial pressure during chronic aldosterone excess. Am. J. Physiol. 276 (Regulatory Integrative Comp. Physiol. 45): R197-R202, 1999.-Chronic aldosterone (Aldo) excess is associated with transient sodium retention, extracellular fluid volume expansion, renal vasodilation, and hypertension. The purpose of this study was to determine the role of nitric oxide (NO) in mediating the renal vasodilation and the escape from the sodium-retaining actions of Aldo. To achieve this goal, we examined the long-term effects of Aldo (15 µg • kg Ϫ1 • min Ϫ1 for 7 days) in conscious, chronically instrumented control dogs (n ϭ 9) and in dogs (n ϭ 12) pretreated with the NO synthesis inhibitor N G-nitro-L-arginine methyl ester (L-NAME; 10 µg•kg Ϫ1 • min Ϫ1). In control dogs, Aldo caused a transient sodium retention (126 Ϯ 6 to 56 Ϯ 2 meq/day) followed by a return of sodium excretion to normal levels. Aldo also increased renal plasma flow by 15% (205 Ϯ 13 to 233 Ϯ 16 ml/min), glomerular filtration rate by 20% (72 Ϯ 3 to 87 Ϯ 5 ml/min), and arterial pressure from 90 Ϯ 3 to 102 Ϯ 3 mmHg. Aldo increased urinary nitrate/nitrite excretion by 60% in the control dogs. Although the sodium-retaining (144 Ϯ 7 to 56 Ϯ 7 meq/day) and arterial pressure (122 Ϯ 6 to 136 Ϯ 5 mmHg) responses to Aldo were the same in dogs pretreated with L-NAME compared with control, the renal hemodynamic response was markedly attenuated. The results of this study suggest that NO plays an important role in mediating the renal vasodilation during chronic Aldo excess.

Research paper thumbnail of Mechanisms of Obesity-Induced Hypertension

Physiology, Dec 1, 1996

Obesity is a major cause of human essential hypertension. Recent studies point toward increased r... more Obesity is a major cause of human essential hypertension. Recent studies point toward increased renal tubular reabsorption and abnormal renal pressure natriuresis in mediating obesity hypertension. The mechanisms for these renal changes appear to be multifactorial, including activation of the sympathetic nervous system and altered intrarenal histology, which compresses the renal medulla.

Research paper thumbnail of Chronic endothelin-induced pressor and renal actions in conscious dogs do not require altered ANG II formation

American Journal of Physiology-regulatory Integrative and Comparative Physiology, Feb 1, 1995

Plasma endothelin levels are elevated approximately two- to threefold in a number of chronic path... more Plasma endothelin levels are elevated approximately two- to threefold in a number of chronic pathophysiological conditions associated with hypertension. Results from recent studies indicate an important interaction between endothelin and the renin-angiotensin system (RAS). The role of the RAS in mediating the increases in arterial pressure produced by long-term pathophysiological elevations in circulating levels of endothelin is unknown. Therefore, the purpose of this study was to chronically increase circulating levels of endothelin within the pathophysiological range and determine the long-term cardiovascular and renal actions of endothelin in control dogs (n = 6) and in dogs pretreated with a converting-enzyme inhibitor (CEI) (n = 6) or CEI + angiotensin II (ANG II) replacement (n = 6). Infusion of endothelin-1 for 8 days at a rate of 2.5 ng.kg-1.min-1 increased plasma endothelin from 7.1 +/- 0.9 to 19.8 +/- 3.3 pg/ml. In control dogs, endothelin increased mean arterial pressure (MAP) by 19% (90 +/- 2 to 107 +/- 3 mmHg) while decreasing renal blood flow (RBF) by 30% and glomerular filtration rate (GFR) by 15-20%. Long-term elevation of circulating endothelin produced similar elevations in MAP in dogs pretreated with CEI (+16%) or CEI + ANG II (+17%). Similar decreases in RBF and GFR also occurred in response to endothelin in all three groups. These results indicate that although long-term increases in circulating endothelin within the pathophysiological range produce significant increases in arterial pressure, this effect does not appear to be mediated by the RAS.

Research paper thumbnail of Decreased sensitivity to renal interstitial hydrostatic pressure in Dahl salt-sensitive rats

Hypertension, Jun 1, 1994

The ability of Dahl salt-sensitive (DS) rats to excrete a sodium load is significantly lower than... more The ability of Dahl salt-sensitive (DS) rats to excrete a sodium load is significantly lower than Dahl salt-resistant (DR) rats. Because renal interstitial hydrostatic pressure (RIHP) is a major mediator of natriuresis in response to a sodium load, we proposed that the renal tubules of DS rats are less responsive to increases in RIHP than those of DR rats. To test this hypothesis, we determined the effect of direct increases in RIHP on renal excretory function in prehypertensive DS and DR rats. RIHP was directly increased by renal interstitial volume expansion via injection of 50 JAL of a 2% albumin and saline solution into the renal interstitium through a chronically implanted renal interstitial catheter. RIHP, mean arterial pressure, glomerular filtration rate, urine flow rate, urinary sodium excretion, and fractional excretions of sodium, potassium, and lithium (an indicator of proximal tubule sodium handling) were measured before and after direct increases in RIHP in DS (n=8) and DR (n=8) rats. Baseline urine flow rate; urinary sodium excretion; fractional excretions of sodium, potassium, and lithium; RIHP; mean arterial pressure; and glomerular filtration rate were not different between DS and DR rats. Renal interstitial volume expansion in DS rats significantly increased RIHP (A4.7±0.8 mm Hg), urine flow rate (A14.5±3.4 jtL/min), urinary sodium excretion

Research paper thumbnail of Role of nitric oxide in modulating the chronic hypertension produced by pathophysiological increases in circulating endothelin

The FASEB Journal, Mar 24, 1994

Research paper thumbnail of Construct validity of a questionnaire for measuring student engagement in problem-based learning tutorials

BMC Medical Education

Background Student engagement is student investment of time and energy in academic and non-academ... more Background Student engagement is student investment of time and energy in academic and non-academic experiences that include learning, teaching, research, governance, and community activities. Although previous studies provided some evidence of measuring student engagement in PBL tutorials, there are no existing quantitative studies in which cognitive, behavioral, and emotional engagement of students in PBL tutorials is measured. Therefore, this study aims to develop and examine the construct validity of a questionnaire for measuring cognitive, behavioral, and emotional engagement of students in PBL tutorials. Methods A 15-item questionnaire was developed guided by a previously published conceptual framework of student engagement. Focus group discussion (n = 12) with medical education experts was then conducted and the questionnaire was piloted with medical students. The questionnaire was then distributed to year 2 and 3 medical students (n = 176) in problem-based tutorial groups at...

Research paper thumbnail of Measuring medical students’ professional competencies in a problem-based curriculum: a reliability study

BMC Medical Education, May 21, 2019

Background: Identification and assessment of professional competencies for medical students is ch... more Background: Identification and assessment of professional competencies for medical students is challenging. We have recently developed an instrument for assessing the essential professional competencies for medical students in Problem-Based Learning (PBL) programs by PBL tutors. This study aims to evaluate the reliability and validity of professional competency scores of medical students using this instrument in PBL tutorials. Methods: Each group of seven to eight students in PBL tutorials (Year 2, n = 46) were assessed independently by two faculty members. Each tutor assessed students in his/her group every five weeks on four occasions. The instrument consists of ten items, which measure three main competency domains: interpersonal, cognitive and professional behavior. Each item is scored using a five-point Likert scale (1 = poor, 5 = exceptional). Reliability of professional competencies scores was calculated using G-theory with raters nested in occasions. Furthermore, criterion-related validity was measured by testing the correlations with students' scores in written examination. Results: The overall generalizability coefficient (G) of the professional competency scores was 0.80. Students' professional competencies scores (universe scores) accounted for 27% of the total variance across all score comparisons. The variance due to occasions accounted for 10%, while the student-occasion interaction was zero. The variance due to raters to occasions represented 8% of the total variance, and the remaining 55% of the variance was due to unexplained sources of error. The highest reliability measured was the interpersonal domain (G = 0.84) and the lowest reliability was the professional behavior domain (G = 0.76). Results from the decision (D) study suggested that an adequate dependability (G = 0.71) can be achieved by using one rater for five occasions. Furthermore, there was a positive correlation between the written examination scores and cognitive competencies scores (r = 0.46, P < 0.01), but not with the other two competency domains (interpersonal and professionalism). Conclusions: This study demonstrates that professional competency assessment scores of medical students in PBL tutorials have an acceptable reliability. Further studies for validating the instrument are required before using it for summative evaluation of students by PBL tutors.

Research paper thumbnail of Generalisability theory analyses of concept mapping assessment scores in a problem-based medical curriculum

Medical Education, 2016

In problem-based learning (PBL), students construct concept maps that integrate different concept... more In problem-based learning (PBL), students construct concept maps that integrate different concepts related to the PBL case and are guided by the learning needs generated in small-group tutorials. Although an instrument to measure students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; concept maps in PBL programmes has been developed, the psychometric properties of this instrument have not yet been assessed. This study evaluated the generalisability of and sources of variance in medical students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; concept map assessment scores in a PBL context. Medical students (Year 4, n = 116) were asked to construct three integrated concept maps in which the content domain of each map was to be focused on a PBL clinical case. Concept maps were independently evaluated by four raters based on five criteria: valid selection of concepts; hierarchical arrangement of concepts; degree of integration; relationship to the context of the problem, and degree of student creativity. Generalisability theory was used to compute the reliability of the concept map scores. The dependability coefficient, which indicates the reliability of scores across the measured facets for making absolute decisions, was 0.814. Students&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; concept map scores (universe scores) accounted for the largest proportion of total variance (47%) across all score comparisons. Rater differences accounted for 10% of total variance, and the student × rater interaction accounted for 25% of total variance. The variance attributable to differences in the content domain of the maps was negligible (2%). The remaining 16% of the variance reflected unexplained sources of error. Results from the D study suggested that a dependability level of 0.80 can be achieved by using three raters who each score two concept map domains, or by using five raters who each score only one concept map domain. This study demonstrated that concept mapping assessment scores of medical students in PBL have high reliability. Results suggested that greater improvements in dependability might be made by increasing the number of raters rather than by increasing the number of concept map domains.

Research paper thumbnail of Undergraduate medical education in the Gulf Cooperation Council: A multi-countries study (Part 1)

Research paper thumbnail of Good advice from authors working in under‐represented countries

Research paper thumbnail of Student engagement in health professions education: AMEE Guide No. 152

Research paper thumbnail of Measurement of student engagement in health professions education: a review of literature

BMC Medical Education

Student engagement is a complex multidimensional construct that has attained great interest in he... more Student engagement is a complex multidimensional construct that has attained great interest in health professions education (HPE). Definition and conceptualization of student engagement is an important step that should drive the development of the instruments for its measurement. We have recently proposed a comprehensive framework for student engagement in HPE with a definition of engagement as student investment of time and energy in academic and non-academic experiences that include learning, teaching, research, governance, and community activities. The dimensions of student engagement in this framework included the cognitive, affective, behavioral, agentic, and socio-cultural. Guided by the student engagement framework, this non-systematic review aims to identify, critically appraise, and summarize the existing methods for measuring student engagement in HPE. Extrapolating from higher education literature, we attempted to link the theoretical perspectives of student engagement wi...

Research paper thumbnail of Designing and Piloting a Professionalism Curriculum for Undergraduate Medical Students at the Faculty of Medicine, Suez Canal University

Suez Canal University Medical Journal

Research paper thumbnail of The effect of access to electronic resources during examination on medical and dental students scores in summative assessment: quasi experimental study

BMC Medical Education

Background Access to electronic (E) resources has become an indispensable requirement in medical ... more Background Access to electronic (E) resources has become an indispensable requirement in medical education and practice. Objective Our objective was to assess the effect of E-resources access during examination on end-course-exam scores of medical and dental students. Methods A quasi-experimental study which included two cohorts of medical (n = 106 & 85) and three cohorts of dental students (n = 66, 64 and 69) who took end-course- exams. Each exam was composed of two- parts (Part I and II), that encompassed equal number of questions and duration. Access to E-resources was allowed in part-II only. Items Difficulty Index (DI), Discrimination Index, (DisI), Point Biserial, (PBS) and cognitive level were determined. Results The study included 390 students. The proportion of items at various levels of DI, DisI, and PBS and the average values for item DI, DisI in both parts of each exam were comparable. The average scores in part-II were significantly higher than part-I (P < 0.001, &lt...