Publications by authors named "Mehdi Aarabi"

11 Publications

  • Page 1 of 1

Modelling COVID-19 transmission in a hemodialysis centre using simulation generated contacts matrices.

PLoS One 2021 19;16(11):e0259970. Epub 2021 Nov 19.

LIAM (Laboratory for Industrial and Applied Mathematics), York University, Toronto, Ontario, Canada.

The COVID-19 pandemic has been particularly threatening to patients with end-stage kidney disease (ESKD) on intermittent hemodialysis and their care providers. Hemodialysis patients who receive life-sustaining medical therapy in healthcare settings, face unique challenges as they need to be at a dialysis unit three or more times a week, where they are confined to specific settings and tended to by dialysis nurses and staff with physical interaction and in close proximity. Despite the importance and critical situation of the dialysis units, modelling studies of the SARS-CoV-2 spread in these settings are very limited. In this paper, we have used a combination of discrete event and agent-based simulation models, to study the operations of a typical large dialysis unit and generate contact matrices to examine outbreak scenarios. We present the details of the contact matrix generation process and demonstrate how the simulation calculates a micro-scale contact matrix comprising the number and duration of contacts at a micro-scale time step. We have used the contacts matrix in an agent-based model to predict disease transmission under different scenarios. The results show that micro-simulation can be used to estimate contact matrices, which can be used effectively for disease modelling in dialysis and similar settings.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0259970PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8604317PMC
November 2021

Assessment of Bone Mineral Density in Patients Undergoing Hemodialysis; An Iranian Population-Based Study.

Arch Iran Med 2021 08 1;24(8):599-606. Epub 2021 Aug 1.

Bone Joint and Related Tissues Research Center, Akhtar Orthopedic Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.

Background: End-stage renal disease (ESRD) is a condition in which bone turnover and metabolism is impaired; thus, osteoporosis and low bone density are subsequently inevitable. We aimed to determine bone mineral density (BMD) and biochemical markers, and associated factors in hemodialysis (HD) patients.

Methods: Patients aged 30-70 years undergoing HD between 2015 to 2019 were enrolled in this cross-sectional study. BMD measured by dual energy x-ray absorptiometry (DEXA) and biochemical laboratory tests were assessed in 200 patients undergoing HD. Statistical analysis was based on test, Pearson, regression and Mann-Whitney tests using SPSS 16.

Results: Two hundred patients were investigated. Sixty percent of the patients were female. Mean ± SD of participants' age was 58.6 (±11.63) years and mean ± SD for duration of HD was 45.69 (± 43.76) months. Osteoporosis was found in 48% (n=96) and low bone density in 36% (n=76) of our patients. General osteoporosis was more frequent in those undergoing HD for more than 3 years, although not significantly (=0.093, odds ratio [OR]=0.37). However, regional osteoporosis in hip and femoral neck, but not spine vertebrae, were significantly higher after three years of HD (=0.036, OR=0.27; =0.042, OR=0.27; and =0.344, OR=0.56, respectively). Increased body mass index (BMI) correlated negatively with osteoporosis (=0.050).

Conclusion: With increasing age and duration of HD, BMD decreases. Higher BMI was associated with higher bone mass density. Bone density assessment seems to be necessary in patients undergoing HD.
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http://dx.doi.org/10.34172/aim.2021.85DOI Listing
August 2021

Are individual analyses of multiple short urine collections throughout the 24 hours superior to a standard 24-hour urine collection in precipitation risk assessment of healthy subjects?

Nephrology (Carlton) 2021 Mar 25;26(3):234-238. Epub 2021 Jan 25.

Division of General Internal Medicine, Department of Medicine, Toronto General Hospital and Li Ka Shing Knowledge Institute of St. Michael's Hospital and Division of Nephrology, University of Toronto (MLH), Toronto, Ontario, Canada.

Purpose: The commonly used 24-hour collection technique has been the mainstay of diagnosis for supersaturation but has some certain limitations. Hence, superiority of multiple short urine collections as a new alternative in precipitation risk assessment was assessed compared to the standard 24-hour urine collection among healthy subjects.

Materials And Methods: Individual urine samples of 26 healthy subjects were acquired every 2 to 3 hours throughout the 24 hours. Urine samples were obtained and the time and volume of each sample were recorded. Urinary constituents involved in precipitation including, sodium-potassium, chloride, calcium, phosphate, citrate, magnesium, urea, creatinine and pH were measured. A simulated 24-hour collection was recalculated by the totalling of all shorter urine collections volume and urinary constituents excretions throughout the day.

Results: Urine pH, urine creatinine and precipitation rate had a significantly lower values in 24-hours urine collection compared to one individual value of multiple urine collections by -0.769 (P < .0001), -7.305 (P < .0001), and - 12.838 (P < .0001), respectively. However, calcium (2.697, P < .0001), citrate (3.54, P < .0001), total phosphate (19.961, P < .0001) and total creatinine (9.579, P < .0001) had statistically significantly higher values in the 24-hours urine collection compared to individual value of multiple urine collections.

Conclusion: Based on the results, individual analysis of multiple shorter urine collections throughout the day improves the ability of identifying supersaturation points, precipitation risk zones and may potentially improve risk assessment compared to the 24-hour urine collection method.
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http://dx.doi.org/10.1111/nep.13842DOI Listing
March 2021

Triceps-sparing Posterior Approach for Supracondylar Humeral Fracture in Children.

Arch Bone Jt Surg 2019 Sep;7(5):416-421

5 Azar Hospital, Bone, Joint, Connective Tissue Research Center, Gorgan, Iran.

Background: The most common pediatric elbow fracture is supracondylar humeral fracture which accounts for 60% of elbow fractures in children. The aim of this study was to evaluate the results of open reduction and internal fixation of type III supracondylar humeral fractures using a Triceps sparing posterior approach.

Methods: In total, 98 patients were evaluated from June 2007 to 2014.

Results: According to the results, the mean age of the patients was 6.4 years. The ratios of males to females and the right to left hand were 2.06 and 2.26, respectively. Totally, 82% of fractures happened in the dominant hand which was right. The patients underwent surgery within approximately 50.16 hours after injury. Anatomic reduction and internal fixation were performed under direct vision with no need for image intensifier. The mean time of follow-up was 14.3 months, and all fractures healed clinically and radiologically. Moreover, the maximum lack of an extension was 15° and the obtained mean was 3.5°. Additionally, the mean final Bauman angle difference with healthy elbow was determined at 2.4°. The rate of complications was 19.3%, including pin tract infections (7%), pin loosening (3%), heterotopic ossification (4%), and wound dehiscence (1%). Furthermore, there were 4 cases (4%) of anterior interosseous nerve palsy, two of which happened before surgery, and the other two following the surgery. All of these complications were resolved within 3 to 10 weeks spontaneously.

Conclusion: This approach helped preserve the extensor mechanism and ulnar nerve intact to have an acceptable skin scar esthetically along with satisfactory postoperative function.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6802550PMC
September 2019

Impact of Prolonged Fasting on the Risk of Calcium Phosphate Precipitation in the Urine: Calcium Phosphate Lithogenesis during Prolonged Fasting in a Healthy Cohort.

J Urol 2018 07 2;200(1):141-146. Epub 2018 Mar 2.

Division of General Internal Medicine, Department of Medicine, Toronto General Hospital and Li Ka Shing Knowledge Institute of St. Michael's Hospital and Division of Nephrology, University of Toronto (MLH), Toronto, Ontario, Canada.

Purpose: Intermittent fasting and curtailing water intake for extended periods were likely common in Paleolithic times. Today it occurs for religious and dietary reasons. This restriction in intake should cause a decrease in the urine flow rate while raising the concentration of certain substances in urine to the point of precipitation. In this study we measured the risk of CaHPO precipitation following 18 hours of food and water deprivation.

Materials And Methods: Urine samples were periodically collected from 15 healthy subjects who fasted and abstained from drinking any liquid for 18 hours. The urine constituents Ca, HPO and pH involved in CaHPO formation were measured at various times throughout the fasting day. A comparison was made with control data, which consisted of diurnal urine collections taken throughout a separate nonfasting day prior to the fasting day.

Results: The mean ± SEM urine flow rate decreased significantly from 0.93 ± 0.1 ml per minute in the control group to 0.37 ± 0.05 ml per minute in the fasting group (p <0.05). Mean Na and Ca excretion rates decreased significantly from 127 ± 12 to 54 ± 13 μmol per minute and from 3.2 ± 0.4 to 0.80 ± 0.21, respectively. Mean urinary Na and Ca concentrations also decreased from 161 ± 11.6 to 122 ± 16.0 mmol/l and from 3.7 ± 0.5 to 2.0 ± 0.55, respectively. Urinary pH and the concentration of phosphate, citrate and magnesium were not significantly affected.

Conclusions: Although the steady decrease in the urine flow rate was statistically significant during 18 hours of food and water deprivation, there was no evidence that the calculated risk of CaHPO precipitation in the healthy subjects had increased.
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http://dx.doi.org/10.1016/j.juro.2018.02.3092DOI Listing
July 2018

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

Results and complications of a surgical technique for correction of coxa vara in children with osteopenic bones.

J Pediatr Orthop 2008 Dec;28(8):799-805

Shriners Hospital for Children, McGill University, Montreal, Quebec, Canada.

Background: Surgical correction of coxa vara in children with osteopenic bone diseases could be very challenging. In this study, we describe a modified surgical technique for the correction of coxa vara in children with bone fragility. We also report the results and complications of this technique in 16 children (21 coxa vara) with osteopenic bone diseases.

Methods: Charts, clinic notes, and radiology images of 16 patients (21 hips) who had a proximal femoral osteotomy for the treatment of coxa vara in osteogenesis imperfecta (18 hips) and fibrous dysplasia (3 hips) in our institution between 1996 and 2005 were reviewed. The modified surgery involved an intertrochanteric osteotomy and the use of Kirshner wires and intramedullary rods. Neck-shaft angle, Hilgenreiner-epiphyseal angle, and head-shaft angle were assessed at preoperative, postoperative, and final follow-up.

Results: The average age at surgery was 8.3 years (range, 3.3-15.8 years). The average correction of the neck-shaft angle was from 84.6 to 114.4 degrees, and for the Hilgenreiner-epiphyseal angle, it was from 67.7 to 42 degrees at final follow-up. All osteotomies were healed at 3 months postoperatively. The mean follow-up was 4.29 years (range, 1.70-8.12 years). The average improvement in abduction and external rotation of the hips was 14 and 15 degrees, respectively. There were no cases of infection and 2 cases (12%) of implant-related complications. One patient with fibrous dysplasia needed replacement of the intramedullary rod and additional distal femoral osteotomy 1 week postsurgery. In another patient, the intramedullary rod had migrated proximally, which was corrected 5 months postsurgery by advancing the rod distally.

Conclusion: Results suggest that this surgical technique provides satisfactory correction of coxa vara in children with osteopenic bone diseases.

Clinical Relevance: The described surgical technique used to correct coxa vara is reproducible and safe and has few complications. Furthermore, the size of the implants used allows surgery to be performed in very young children.
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http://dx.doi.org/10.1097/BPO.0b013e31818e19b7DOI Listing
December 2008

Radial head dislocation and subluxation in osteogenesis imperfecta.

J Bone Joint Surg Am 2007 Dec;89(12):2694-704

Pediatric Orthopaedics Clinical Fell, McGill University, 1529 Cedar Avenue, Montreal, QC H3G 1AG, Canada.

Background: Upper limb deformity in children with osteogenesis imperfecta may substantially impair function. The aims of this retrospective work were to study the prevalence of radial head malalignment (dislocation or subluxation) in different types of osteogenesis imperfecta and to identify factors linked to it.

Methods: We assessed 489 upper limbs from 254 patients (with a mean age of 9.6 years and including 130 female patients) who had various types of osteogenesis imperfecta. Radiographs representing a single time-point for each patient were assessed for the presence and direction of radial head malalignment and associated abnormalities (dysplasia of the capitellum or of the radial head or neck, calcification of the interosseous membrane, or radioulnar synostosis). Deformations of the humerus, radius, and ulna were assessed with regard to location, direction, and magnitude. The forearm range of motion in pronation and supination and the hand grip force were measured in a subset of patients.

Results: We observed radial head dislocation or subluxation in forty-four and thirty-nine upper extremities, respectively. The frequency of radial head malalignment was significantly higher in type-V osteogenesis imperfecta (86%) than in the other types (0% to 29%) (p < 0.001). Dysplasia of the humeral capitellum, radial head, or radial neck was associated with malalignment in all types of osteogenesis imperfecta, with the exception of capitellum dysplasia in type V. Malalignment in type V was associated with calcification of the interosseous membrane, an abnormality that was specific for type V. In the other osteogenesis imperfecta types, malalignment was commonly linked with radial and ulnar deformation and was associated with decreased forearm range of motion in supination and pronation and a lower grip force.

Conclusions: Radial head malalignment is common in osteogenesis imperfecta, especially in type V. Malalignment is associated with bowing characteristics and impaired function of the upper limb. These findings may provide support for surgical correction of radial and ulnar bowing in selected patients with osteogenesis imperfecta.
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http://dx.doi.org/10.2106/JBJS.F.01287DOI Listing
December 2007

High prevalence of coxa vara in patients with severe osteogenesis imperfecta.

J Pediatr Orthop 2006 Jan-Feb;26(1):24-8

Shriners Hospital for Children, Division of Orthopaedics, McGill University, Montréal, Québec, Canada.

The purpose of this study was to determine the incidence and clinical presentation of coxa vara in 283 patients with osteogenesis imperfecta (OI). The charts and X-rays of 150 girls and 133 boys with OI were reviewed. The patients were classified according to the Sillence classification modified by Glorieux: 94 type I, 90 type IV, 67 type III, 18 type V, 10 type VI, and 4 type VII. The mean age was 9.4 years (range 0.3-23.3). Twenty-nine patients (10.2%) had coxa vara (23 left and 20 right). Fifty-five percent of them were type III, 24% type IV, 13.8% type VI, and 3.4% each of types V and VII. The incidence of coxa vara was 6% in type V, 8% in type IV, 24% in type III, 25% in type VII, and 40% in type VI (P < 0.001 for difference between types I, III, and IV). The mean neck-shaft angle was 99 degrees (range 80-110 degrees), the average head-shaft angle was 104 degrees (range 90-120 degrees), and the mean Hilgenreiner-epiphyseal angle was 68 degrees (range 40-90 degrees). Twenty-five patients (36 hips) had previous femoral rodding before diagnosis and seven hips (all type III) had no history of rodding. Abduction and internal rotation of the hip joints were restricted in all patients with this deformity. All children with coxa vara had a Trendelenburg gait. In conclusion, coxa vara in OI is not rare, especially in severe forms of the disease. Regular clinical and radiologic follow-up is indicated in children with previous femoral rodding and in severely affected children, particularly those with OI type III.
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http://dx.doi.org/10.1097/01.bpo.0000189007.55174.7cDOI Listing
February 2006

Functional analysis of upper limb deformities in osteogenesis imperfecta.

J Pediatr Orthop 2004 Nov-Dec;24(6):689-94

Department of Orthopedic Surgery, Japan Self-Defense Force Sapporo General Hospital, Sapporo, Hokkaido, Japan.

The charts and radiographs of 159 children with osteogenesis imperfecta (OI) were retrospectively reviewed to measure the severity of upper limb deformities and to evaluate the functional outcome using the Pediatric Evaluation of Disability Inventory (PEDI). The patients were classified according to the Sillence classification modified by Glorieux: 51 type 1, 33 type 3, 54 type 4, and 21 5ype 5. Fifty-nine patients (37.1%) had deformities of their upper limbs. Children with type 3 OI had the highest incidence and the most severe deformities. The humerus was the most commonly involved bone, followed by the ulna and radius. Upper limb deformities were classified into four groups according to the severity of the maximum deformity angle. The mean self-care scores of PEDI were significantly low only in the group with severe deformities, but mobility scores were dramatically decreased in both the moderate and severe deformity groups. Therefore, upper limb deformities in children with OI do not represent only a cosmetic problem, but may also significantly impair functional activities of daily living.
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http://dx.doi.org/10.1097/00004694-200411000-00017DOI Listing
June 2005

Total hip arthroplasty in a patient with neurofibromatosis type I and recurrent spontaneous hip dislocation.

Can J Surg 2004 Jun;47(3):219-20

Service d'orthopédie et traumatologie infantile, Hôpital des enfants malades, Paris, France.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3211826PMC
June 2004
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