Publications by authors named "Mohammad-Ali Shafiee"

4 Publications

  • Page 1 of 1

3D simulation of solutes concentration in urinary concentration mechanism in rat renal medulla.

Math Biosci 2019 02 12;308:59-69. Epub 2018 Dec 12.

Division of General Internal Medicine, Department of Medicine, Toronto General Hospital, Toronto, Canada.

In this work, a mathematical model was developed to simulate the urinary concentration mechanism. A 3-D geometry was derived based on the detail physiological pictures of rat kidney. The approximate region of each tubule was obtained from the volume distribution of structures based on Walter Pfaller's monograph and Layton's region-based model. Mass and momentum balances were applied to solve for the change in solutes concentration and osmolality. The osmolality of short and long descending nephrons at the end of the outer medulla was obtained to be 530 mOsmol/kgH2O and 802 mOsmol/kgH2O, respectively, which were in acceptable agreement with experimental data. The fluid osmolality of the short and long ascending nephrons was also compatible with experimental data. The osmolality of CD fluid at the end of the inner medulla was determined to be 1198 mOsmol/kgH2O which was close the experimental data (1216 ± 118). Finally, the impact of the position of each tubule on the fluid osmolality and solutes concentration were obvious in the results; for example, short descending limb a1, which is the closest tubule to the collecting duct, had the highest urea concentration in all tubules. This reflects the important effect of the 3D modeling on the precise analysis of urinary concentration mechanism.
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http://dx.doi.org/10.1016/j.mbs.2018.12.008DOI Listing
February 2019

Blunted Overnight Blood Pressure Dipping in Second Trimester; A Strong Predictor of Gestational Hypertension and Preeclampsia.

Curr Hypertens Rev 2019 ;15(1):70-75

Sarem Fertility and Infertility Research Center (SAFIR), Sarem Women's Hospital, Tehran, Iran.

Background: Preeclampsia is a global burden with 10 million incidences annually and 210 daily deaths worldwide. Diagnosis is mainly based on the features following full presentation.

Objective: This study explored whether early pregnancy circadian changes of ambulatory blood pressure monitoring (ABPM) could predict preeclampsia and hypertension.

Methods: In a prospective study, 294 pregnant women who were referred to Sarem Women's Hospital, Iran were recruited. Systolic, diastolic and mean arterial pressures (MAP) were recorded (diurnally and nocturnally) in each trimester. Dipping was defined as a minimum 10% decrease in blood pressure.

Results: Of the 251 women who completed the study, 25 percent (n=63) experienced blunted MAP dipping during sleep phases in the second trimester. Eighty-nine percent (n=56) experienced hypertensive disorder in the third trimester, one-third of which experienced preeclampsia. Of the women with normal MAP dipping (n=188), 5 percent (n=10) had gestational hypertension and 1 percent (n=2) became preeclamptic. (P<0.0001).

Conclusion: This study clearly demonstrated blunted blood pressure dipping overnight during the second trimester which is a strong predictor of forthcoming pregnancy-induced hypertension and preeclampsia. A scoring system was developed to predict hypertensive disorder and it was significantly correlated with preeclampsia occurrence.
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http://dx.doi.org/10.2174/1573402114666180924143801DOI Listing
August 2019

The Impact of Hemodialysis Frequency and Duration on Blood Pressure Management and Quality of Life in End-Stage Renal Disease Patients.

Healthcare (Basel) 2017 Sep 2;5(3). Epub 2017 Sep 2.

Pars Advanced and Minimally Invasive Manners Research Center, Pars Hospital Department of Nephrology, Iran University of Medical Sciences, Tehran 1449614535, Iran.

Cardiovascular complications are the most prominent causes of morbidity and mortality among chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients undergoing standard hemodialysis (HD) therapy. Cardiovascular disease risk is increased significantly through persistent hypertension and blood pressure (BP) fluctuation, which are the most common complications of CKD. It was hypothesized that an extended approach with lengthier and more frequent dialysis sessions, referred to in this paper as "extended hemodialysis" (EHD), can potentially lower and stabilize blood pressure, and consequently reduce the rate of morbidity and mortality. A greater reduction of volume (salt and water) with higher frequency can improve patient quality of life (QOL). Eleven papers, including clinical trials and systematic reviews were chosen and analyzed. The extracted data was used to evaluate the change in blood pressure levels between standard HD and EHD. Overall, the studies showed that EHD resulted in improved blood pressure management; therefore, we concluded that there will be a decrease in cardiovascular disease risk, stroke, and morbidity and mortality rate. There will be also an improvement in patient QOL due to beneficial effects of the EHD.
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http://dx.doi.org/10.3390/healthcare5030052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618180PMC
September 2017

Dermatologic Manifestations in End-stage Renal Disease.

Iran J Kidney Dis 2015 Sep;9(5):339-53

Division of General Internal Medicine, Toronto General Hospital, University of Toronto, Toronto, Canada.

End-stage renal disease (ESRD) is a rapidly growing global health problem within the past decades due to increased life expectancy, diabetes mellitus, hypertension, and vascular diseases. Since ESRD is not curable definitively, patients suffering from ESRD have a very low quality of life; therefore, symptomatic management is the cornerstone of medical treatment. Uremia affects almost all body organs, such as skin, through different mechanisms including biochemical, vascular, neurologic, immunologic, hematologic, endocrine, and electrolyte and volume balance disturbances. Some of these conditions are associated with significant morbidity, and patients with ESRD commonly present with a spectrum of dermatologic disorders. Each one has its own unique presentation and treatment approaches. In this review article, we discuss the clinical presentation, pathophysiology, and treatment of the most common skin disorders associated with ESRD.
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September 2015