Life Sciences Commons^™

Study Of The Relationship Between Insulin Resistance And Osteoporosis In Type 2 Diabetes Mellitus And Diabetic Nephropathy Elderly Patients, Mohamed Zakarya Nooh, Alaa Abdelsalam Dawood, Bassant Samy Hamed Hafez, Moustafa Bakrey Hamed Ata

Mansoura Medical Journal

Background Type 2 diabetes mellitus and diabetic kidney disease play a major role in bone deterioration and increased fracture risk because they influence both insulin sensitivity and bone metabolism. Objective The purpose of this study was to investigate the connection between osteoporosis and insulin resistance in older individuals with type 2 diabetes and diabetic kidney disease (DKD). Methods: A total of 105 participants were enrolled in the study and divided equally into three groups: 35 diabetic patients with albuminuria, 35 diabetic patients without albuminuria, and 35 age- and gender-matched healthy controls. The study was conducted at the Endocrinology & DM …

Evaluation Of Neutrophils To Albumin Ratio (Nar) And C-Reactive Protein To Albumin Ratio (Car) As Markers Of Disease Activity In Patients With Ulcerative Colitis, Doaa Salah Abd-El-Fattah, Mohamed Abd El-Maksoud, Salwa M. Abo El-Khair, Ahmed El-Eraky, Amany Hasson

Mansoura Medical Journal

Background Ulcerative colitis (UC) is considered an extensive disease due to the risks of proximal extension, malignant transformation, disability and impaired life quality. This study aimed to explore the role of Neutrophils to Albumin Ratio (NAR) and C - reactive protein to Albumin Ratio (CAR) in evaluation of disease activity in patients with UC. Methods This cross-sectional study included 227subjects classified into two groups; group (I) included 126patients suffering from ulcerative colitis and group (II) included 101 healthy individuals with normal basic laboratory tests matched for age and sex. Estimating disease activity and severity clinically was according to Truelove criteria. …

Impact Of Admission Hyperglycemia On In-Hospital Arrhythmia In Medical Critical Illness, Ebrahim Elsayed Tawfik, Afaf Abdel Hafez, Tarek El-Sayed Gouda, Rehab Shaheen Bahram Shaheen

Mansoura Medical Journal

Background Admission hyperglycemia is frequently encountered in critically ill patients, even in the absence of pre-existing diabetes. Acute stress hyperglycemia triggers autonomic activation, oxidative stress, and electrophysiological disturbances that may predispose to cardiac arrhythmias. Aim of work The present study aimed to explore the frequency and type of arrhythmic events among critically ill patients with admission hyperglycemia in medical intensive care units (MICU). Methods: A prospective study was conducted on 354 critically ill ICU patients . They were divided into group A with admission hyperglycemia (>180 mg/dL) and group B with admission normoglycemia (≤180 mg/dL). All patients were subjected …

Evaluation Of The Frequency Of Subclinical Peripheral Neuropathy Among Children And Adolescents With Type 1 Diabetes Mellitus Using Nerve Conduction Studies, Hadeer Ashraf Abdulwahab, Ann A. Abdelkader, Nanees Salem, Bothina Hasaneen

Mansoura Medical Journal

Background: The long-term vascular complications of diabetes mellitus (DM) include nephropathy, retinopathy, neuropathy, and macrovascular diseases, so the aim of this study was to evaluate the frequency of subclinical peripheral neuropathy among children and adolescents with Type 1 DM using nerve conduction studies (NCSs) in relation to diabetesrelated clinical and metabolic parameters. Methods: This cross-sectional study was conducted on 50 children and adolescents with T1D. The patients were divided into 2 groups, symptomatic group who had symptoms or signs of diabetic sensorimotor polyneuropathy (DSPN) and asymptomatic group who had no signs or symptoms of polyneuropathy. NCSs were conducted and sensory …

Readmission And Reoperation Following Transurethral Incision Of The Prostate For Benign Prostatic Obstruction: A 20-Year Retrospective Review And Analysis, Amr Wael Yehia, Mohamed Hegazy, Ahmed Refat Elnahas, Ahmed Mohamed Elshal

Mansoura Medical Journal

Introduction: Transurethral Incision of the Prostate (TUIP) is a recognized surgical treatment for benign prostatic obstruction (BPO), particularly in patients with smaller glands. While valued for its minimal invasiveness, it is associated with higher medium-term reoperation rates. This study analyzes a 20-year institutional experience to define the rate, timing, causes, and predictors of readmission and reoperation after TUIP. Methods: A retrospective review of 557 patients who underwent TUIP for BPO was conducted. Data collected included demographics, comorbidities, perioperative details and complications graded by the Clavien-Dindo system. Univariate and multivariate logistic regression analyses identified predictors of readmission and reoperation if present. …

Assessment Of Serum Level Of Il-38 In Patients With Non-Segmental Vitiligo And Its Relation To Disease Severity, Zahraa Jafar Ahmed Altaitoon, Al-Shahat Farag Ahmed Sharaf, Hamdy Fouad A. Marzo, Mohammed Samir Sultan

Mansoura Medical Journal

Background: Vitiligo is a common autoimmune disorder (AID) characterized by extensive loss of melanocytes, causing depigmented skin patches. Interleukin-38 (IL- 38), an anti-inflammatory cytokine, has been linked to several autoimmune conditions, but its involvement in vitiligo hasn’t been confirmed. Aim: To measure serum IL-38 levels in patients with non-segmental vitiligo (NSV) and explores how these levels relate to disease severity and activity. Methods: We conducted a cross-sectional case-control study that included 40 patients with non-segmental vitiligo and 40 healthy individuals matched for age, sex, and BMI. Assessment of disease severity and activity was conducted by using the Vitiligo Area Scoring …

Management Of Seroma After Posterior Lumbar Spine Decompression, Ayman Mohamed Basha, Ahmed Anas Zahra

Mansoura Medical Journal

Background: Postoperative seroma formation represents a significant complication following posterior lumbar spine decompression (PLSD) that can compress neural structures, cause radiculopathy, and serve as potential infection sources. This study evaluated the clinical characteristics and therapeutic approaches for seroma formation after posterior lumbar decompression procedures.

Methods: An observational study was conducted on 140 patients aged 18 years and older who underwent elective PLSD. Patients were systematically evaluated at predetermined intervals using clinical examination and diagnostic imaging when seroma was suspected. Management protocols were stratified according to seroma size, symptom severity, and clinical progression, ranging from conservative compression dressings to percutaneous aspiration …

Role Of 16s Rrna Gene And Activin-A In Detection Of Neonatal Sepsis, Reem Gomaa, Walaa Othman Elshabrawy, Nada Mohsen, Mohamed Mofreh

Mansoura Medical Journal

Objective: A bloodstream infection in a newborn less than 28 days is referred to as neonatal sepsis (NS). A novel quick and sensitive markers are required for the early detection of bacterial infections in neonates with sepsis, even if blood culture is a great way to diagnose sepsis because the results are delayed. This study was done to estimate the value of activin-A and molecular method (16S rRNA gene) by PCR as new methods for diagnosis of neonatal sepsis.

Methods: Fifity neonates came to the Mansoura University Children Hospital (MUCH) divided into two Groups: Group І (Sepsis group) …

Comparative Study Between Cervical Disc Arthroplasty And Anterior Cervical Discectomy And Fusion, Samer Samy, Ayman Mohamed Basha

Mansoura Medical Journal

Background: Cervical disc arthroplasty (CDA) has emerged as an alternative to anterior cervical discectomy and fusion (ACDF), aiming to preserve segmental motion and reduce adjacent segment disease (ASD). However, evidence regarding its superiority remains controversial. This study was designed to relate ACDF and CDA following anterior cervical discectomy with respect to safety, efficacy, and impact on patient lifestyle.

Methods: This retrospective comparative study included 36 patients who underwent anterior cervical discectomy between August 2021 and September 2024. Twenty patients underwent ACDF (Group A), and sixteen patients underwent CDA (Group B). Clinical outcomes were assessed using the Visual Analogue Scale (VAS) …

Epidemiology Of Closed Ruptured Tendoachilles, Hesham Mousad Alsakaan, Wael Mansour Wafa, Mohieb Sayed Ahmed, Ahmed El Sayed Magdy Elhawary

Mansoura Medical Journal

Background: To restore tendon function and avoid long-term impairment, early diagnosis and adequate treatment are crucial. The purpose of this study was to ascertain the incidence pattern of ATR and to pinpoint possible variables related to presentation and management approach.

Aim  identifying potential risk factors either patient or environmental related and to assess the incidence rate of ATR

Patients and Methods: This retrospective cross-sectional study was performed on 87 achilles tendon rupture patients. All the patients were subjected to full medical history taking. Clinical examination was performed including thompson test and Matles test and radiological investigations.

Results: The median age …

Effect Of Adenotonsillectomy On Nocturnal Enuresis In Children With Obstructive Sleeping Apnea, Ramla Dahir Hersi, Hossam El-Sayed Elsisi, Ahmed Abdoo Elzehzahy

Mansoura Medical Journal

Background: Nocturnal enuresis (NE) is the involuntary passage of urine during sleep and is a common condition in the pediatric population. Obstructive sleep apnea (OSA), characterized by recurrent episodes of upper airway obstruction during sleep, has increasingly been identified as a significant contributing factor to NE. Previous studies indicate that children with OSA have a higher prevalence of bedwetting than their healthy counterparts.

Objective: To assess the impact of adenotonsillectomy (AT) on NE in children diagnosed with obstructive sleep apnea.

Methods: This prospective study enrolled 20 pediatric patients presenting with both NE and OSA secondary to severe adenotonsillar hypertrophy. Tonsillar …

Clinico-Epidemiological Profile Of Iron Deficiency Anemia Among Egyptian Primary School Aged Children: A Hospital Based Study, Rabab Fathy Abdelhamid, Noha Essam, Mona Mohamed Taalab

Mansoura Medical Journal

Background: Iron deficiency anemia (IDA) is the most prevalent cause of anemia among Egyptian children and is associated with a range of hematologic and non-hematologic complications, some of which may be irreversible. This study aims to evaluate the clinical profile and identify factors associated with severe IDA in primary school–aged children.

Methods: This cross-sectional study included 420 primary school–aged children diagnosed with IDA who attended the outpatient clinic of Salamoun El-Qumash Family Medicine Centre. Data were collected through face-to-face interviews using a structured questionnaire. All participants underwent a thorough clinical examination and laboratory evaluation, including a complete blood count and …

Effect Of Graft Steatosis On The Early Outcome Of Living Donor Liver Transplantation, Kareem Maher Shams Eldeen Hassan, Ahmed Mahmoud Abdelrafee, Ahmed Mohamed Ibrahim Elsabbagh, Mohamed Abd Elwahab Ali

Mansoura Medical Journal

Background

Hepatic steatosis in donor grafts represents a growing challenge in living donor liver transplantation (LDLT) due to the rising prevalence of metabolic syndrome. The impact of varying degrees of graft steatosis on recipient and donor outcomes remains incompletely defined.

Aim

To evaluate the effect of different degrees of graft steatosis on early postoperative outcomes in both recipients and donors following LDLT.

Methods

This retrospective study analyzed 169 LDLT cases performed at Mansoura University between January 2014 and June 2024. Donors aged 18-45 years with BMI≥5% on liver biopsy were included. Grafts were stratified by steatosis degree:20% (n=4). Primary outcome …

Red Cell Distribution Width As A Prognostic Factor And Its Comparison With Lactate In Patients With Sepsis: An Observational Prospective Cohort Study, Ahmed Taha Gad, Ghada Fathy El-Rahmawy, Naglaa Abd El-Latif El-Negeery, Eiad Ahmed Ramzy

Mansoura Medical Journal

Background: Red blood cell distribution width (RDW) is a straightforward and cost-effective parameter that is utilized in laboratory hematology to differentiate anemias. It is indicative of the grade of heterogeneity in erythrocyte volume. This study purpose examine the correlation among the risk of adverse results in patients with sepsis and RDW, as well as to equivalence the mortality discriminative capacity of RDW and lactate levels.

Methods: This observational prospective cohort study was done on 67 sepstic patients aged ≥ 21 years old, both sexes. Patients were owed into two groups according to RDW levels: Group A (n=35): normal RDW …

Diffusion Weighted Magnetic Resonance Imaging In Rectal Cancer, Ebtehal A. Mohamed, Fatma Mohamed Sherif, Wael Abdulghaffar, Ahmed M Fareed, Gehad A. Saleh

Mansoura Medical Journal

Background: Rectal cancer (RC) is a major cancer burden globally as it is among the tumors that are most frequently diagnosed worldwide and a significant contributor to global cancer mortality yearly. Imaging with diffusion weighting (DWI) and Magnetic resonance imaging (MRI) is the best radiological modality for the local staging and restaging of RC due to its excellent soft-tissue contrast and high spatial resolution.

Aim of the work: This study aims to assess the value of DW-MRI in staging and assessing treatment response in patients with RC who received concurrent chemoradiotherapy.

Methods: Forty-two patients with RC diagnoses …

Hypoalbuminemia As A Predictive Factor For Acute Kidney Injury In Pediatric Patients Running Title: Hypoalbuminemia In Aki Pediatrics, Kareem El-Saeed El-Maasrany, Ayman Hammad, Hosam Zaghloul, Ahmed Elhusseiny

Mansoura Medical Journal

Aim: Hypoalbuminemia is a well-known risk factor for illness and death, but its role as a particular predictor of acute kidney injury (AKI) is still not fully understood. This study intended to evaluate the role of hypoalbuminemia as a predictive factor for AKI outcome among pediatric patients, regarding hospital stay, kidney replacement therapy and mortality rate.

Subjects and Methods: This prospective observational cohort was conducted on 70 children with AKI divided into two groups: group I (35 AKI children combined with hypoalbuminemia) and group II (35 AKI children without hypoalbuminemia). All participants were subjected to full history taking, clinical examination …

The Role Of Adult Appendicitis Score In Reducing The Negative Appendectomy Rate, Mohamed Mahmoud Mansour El Ghzzawy, Magdy Basheer, Mohamed Balata, Amir A. Fikry

Mansoura Medical Journal

Aim: Approximately 15 – 30% of all acute appendectomies are performed based only on clinical suspicion. A negative appendectomy has a 10–12% morbidity rate, which could be detrimental to patients. The current study aimed to evaluate the effectiveness of adult appendicitis score (AAS) in accurate identification of cases with acute appendicitis.

Patients and Methods: This prospective observational study was conducted on 150 patients who presented with manifestations of acute appendicitis admitted to Mansoura Emergency Hospital.  The AAS was calculated, the decision on appendectomy was solely based on the surgeon’s clinical judgment after taking into consideration all the findings of clinical, …

Assessment Of Health-Related Quality Of Life In Pediatric Patients With End Stage Renal Diseases, Nasteho Adan Awil, Ahmed Mahmoud Elrefaey, Abdel-Hady El-Gilany Abdel-Elfattah, Heba Mohamed El-Taher

Mansoura Medical Journal

Background: End-stage renal disease (ESRD) occurs when the glomerular filtration rate falls below 15 mL/min, requiring renal replacement therapy. Despite improved survival, affected children experience significant physical, emotional, and social challenges. Consequently, health-related quality of life (HRQoL) is markedly reduced compared with healthy peers.

Aim: This study aimed to assess health-related quality of life (HRQOL) in pediatric patients with end-stage renal disease (ESRD) and to identify factors associate with the quality of life in pediatric patients with   end stage renal disease (ESRD).

Methods:  All 60 eligible children who were enrolled in the Nephrology Unit at Mansoura University Children's Hospital …

Diagnostic Performance Of Digital Breast Tomosynthesis In The Characterisation Of Breast Lesions: Correlation With Sono-Mammography And Histopathology., Amira Hamed Megahed, Mona Mahmoud Zaky, Maha Mohamed Bilal

Mansoura Medical Journal

Background: Breast lesions range from benign to malignant, with early detection critical for management. Digital mammography is the standard screening tool but may be limited in dense breasts. Ultrasound (US) aids lesion characterisation, while digital breast tomosynthesis (DBT) reduces tissue overlap, enhancing lesion detection.

Objective: To evaluate the diagnostic performance of digital breast tomosynthesis in the characterisation of breast lesions compared with sono-mammography, using histopathology as the reference standard.

Methods: This prospective study included 33 symptomatic female patients with a mean age (45.4 ± 8.2 years) who presented with symptoms such as palpable breast lumps, Mastalgia and nipple discharge between …

Laparoscopic Versus Open Redo Anti-Reflux Surgery, Mohamed Barkok, Mohammed Said, Ahmed Shehta, Abdel-Raouf El-Geidie

Mansoura Medical Journal

Background

Gastroesophageal reflux disease (GERD) is common. Laparoscopic fundoplication became the gold standard for GERD surgery after medical treatment failed. If a previous anti-reflux surgery fails, redo surgery requires a thorough review to determine the cause and a skilled surgical team. Choosing the optimal approach during the redo surgeries, whether open or laparoscopic hasn’t been previously illustrated.

Aim

To compare the outcomes of laparoscopic versus open redo anti-reflux surgeries.

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Patients and methods

This study included 28 patients who underwent redo anti-reflux surgery. The patients were divided according to the approach into laparoscopic (n = 11) and open (n = …

Serum Magnesium Level And Carotid Artery Calcification And Stiffness In Dialysis Patients: Single Center Cross-Sectional Study, Kareem Ahmed Elbosaty, Alaa Abd Elaziz Sabry, Gehad Ahmad Saleh, Nehal Atef Elshabrawy

Mansoura Medical Journal

Introduction Vascular calcification is common among end-stage renal disease (ESRD) patients on regular dialysis, either hemodialysis or peritoneal dialysis. Magnesium is suggested to play a role in inhibiting that process. Recently, Mg started to be considered one of the factors that protect against vascular calcification and consequently decrease CVD mortality rate in CKD patients. Many recent studies support that role although the mechanism of that protective effect is not clear. But it is supposed to be a combination of both passive and active mechanisms. The passive one occurs through interference with calcium phosphate deposition and hydroxyapatite inhibition by phosphate binding. …

Neonatal Intestinal Obstruction: Etiological Spectrum, Surgical Outcomes, And Predictors Of Mortality In A Tertiary Referral Center In Egypt”, Mohamed M. Abdelghany, Kamal Abd El-Elah Ali, Mohamed Said Elsherbiny, Mohamed Attia Shehata

Mansoura Medical Journal

Background: Neonatal intestinal obstruction (NIO) remains a major surgical emergency associated with substantial morbidity and mortality, particularly in low- and middle-income countries. Early identification of neonates at increased risk of adverse outcomes may improve perioperative management and survival. This study aimed to evaluate the etiological spectrum, surgical management, short-term outcomes, and predictors of mortality among neonates undergoing surgery for intestinal obstruction in a tertiary referral hospital in Egypt, with particular emphasis on the prognostic value of perioperative inflammatory markers. Objective: this study aimed to evaluate the causes and early postoperative outcomes among neonates operated for intestinal obstruction in a tertiary …

Ageing With Hiv: Epidemiological Transition, Biological Mechanisms, And The Impact Of Evolving Antiretroviral Therapy, Jude Eteneneng Enoh, Roland Tiagha Akah

Mansoura Medical Journal

The scale up of antiretroviral therapy (ART) has led to the evolution of HIV infection into a chronic condition, leading to a rapid growth in the number of older adults with HIV. This trend involves several biological, medical, and psychological challenges that go beyond conventional HIV treatment. The current mini-review provides a summary of recent data (2014 – 2026) regarding the changing epidemiology of HIV, biological aspects of ageing, and comorbidities and health systems associated with ageing.

Ageing is driven by persistent immune activation, inflammation, immune senescence, and microbial translocation, all of which accelerate biological ageing. These biological factors lead …

Evaluation Of The Role Of Serum Lactate As A Predictor Of Intestinal Ischemia And Exploration In Adhesive Intestinal Obstruction In Pediatrics, Ahmed F. Sanad, Adham Elsaied, Ahmed Shehta, Ahmad Elhattab

Mansoura Medical Journal

Background: Adhesive small bowel obstruction (ASBO) is a common surgical Problem in children. It sometimes occurs when there are adhesions between bowel loops, it can be treated with conservative management through nasogastric tube (NGT) decompression and upper gastrointestinal contrast study or managed with surgical intervention if conservative management fails. Methods: Our study is a prospective cohort one that included 51 patients diagnosed with ASBO. They were divided into two groups based on whether they were managed conservatively (Group A) or underwent exploration (Group B), Group B was further subdivided into 2 groups: Group B1, including explored cases without resection anastomosis …

Influences On Student College-Major Decision And Satisfaction Rate Among Students In The School Of Agriculture, Danielle Shafer

Murray State Theses and Dissertations

The purpose of this study was to determine the factors that influence students to choose agriculture majors and agriculture careers and measure the level of satisfaction with their major based on these influences. There are many factors that influence students to choose a major in college and college-major satisfaction. These influences and satisfaction with major may have an impact on a student’s decision to choose a college career path. Some of the influences mentioned in studies are family, friends, educators, extension programs, clubs, financial, and recruitment efforts. The degree to which each of these influence students may depend on the …

Comparative Finite Element Method-Based Optimisation Of Coir Fibre Laminates: Aluminium Skins Versus Carbon Cloth Skins, Muhamed Swaleh Ahmed, Bernard Wamuti Ikua, Abel Nyakundi Mayaka

Mansoura Engineering Journal

Natural fibre composites offer a sustainable alternative to conventional composite materials. Their mechanical efficiency is influenced by laminate structure and skin material selection. This study presents a comparative finite element analysis and optimisation of coir fibre-reinforced laminates employing either aluminium skins or carbon cloth skins. COMSOL Multiphysics was used to determine their mechanical response. Optimisation was performed using the BOBYQA algorithm to enhance load sharing between the coir core and skin materials. Results indicated that aluminium-skinned laminates achieve superior compressive and flexural performance, achieving a peak compressive strength of 210 MPa and sustaining a flexural load of 0.65 kN at …

Green Hydrogen-Based Decarbonization Approach For Steel Industry With Hybrid Renewable Energy Sources, Raju Kumar Maurya, Dharmbir Prasad, Rudra Pratap Singh

Mansoura Engineering Journal

This work provides a micro-pilot techno-economic and environmental assessment of a green hydrogen-driven decarbonization scenario for low-carbon steel production at the capacity of 1 ton steel produced (i.e., requiring 50 kg of green hydrogen). In this work an integrated renewable energy (RE) scenario for the steel production site at Jamuria, West Bengal, India is planned to utilize solar photovoltaic (PV), wind turbines (WTs), battery storage and a diesel backup generator to meet the hydrogen production load from an electrolyzer using HOMER Pro software. The results show that the proposed micro-pilot system produces excess electricity with respect to the plant's operating …

An Intuitionistic Fuzzy Hypergraph Model Enhanced ‎By Forest-Of-Walks Dynamics For Medical Image ‎Segmentation, Brinthaguru Thangaraj, Karthick Palanisamy

Mansoura Engineering Journal

The process of accurately segmenting Urolithiasis and pulmonary nodules from medical images presents significant difficulties because of three main factors which include nonuniform intensity distribution and the presence of weak object borders and the uncertainty caused by anatomical structure overlaps. The study introduces F-Zinhger as a solution to these problems through its application of the Forest of Walks technology. The method uses superpixels as fundamental elements which form a multi-scale hypergraph that establishes hyperedges through three criteria: intensity similarity, spatial proximity, and Z-intuitionistic fuzzy hesitation to capture complex contextual connections. The system incorporates a random walk-based label propagation system. The …

Recycling Of Plastic Into Fibers Using A Novel Machine Design And Analysis Of Fiber Characteristics, Mahmoud Khamees, Nasser Ayoub, Sabreen Addullah Abdelwahab, M. M. Maghawry

Mansoura Engineering Journal

This study presents a modified extrusion-based recycling system with an improved nozzle design and controlled fiber production capability. The machine was conceptualized and fabricated to efficiently process waste plastic and extrude it into fibers of varying diameters. The study focuses on evaluating how fiber diameter influences critical material properties. Microstructural analysis by scanning electron microscopy (SEM) was conducted to investigate the morphology and fiber diameters, while tensile testing provided insights into mechanical performance, including strength and elongation. Moisture absorption tests were also performed to assess durability and environmental resistance. The results demonstrate clear correlations between fiber diameter and the examined …

Managing Multi-Drug Resistance: An Evolutionary Game Theory And Optimal Control Approach, Shukhrat Nasrulloev

Theses and Dissertations

Multi-drug resistance is an evolutionary process in which treatment eliminates sensitive cells, allowing resistant clones to dominate. This thesis investigates this process using a framework integrating population dynamics, evolutionary game theory, and optimal control theory. We develop a two-population logistic growth model describing competition between drug-sensitive and drug-resistant cells under treatment, construct dose-dependent payoff matrices and replicator dynamics to characterize evolutionary competition, and derive a critical drug level D_crit = (r_S - rR)/(dS - d_R) at which resistant cells gain a fitness advantage. An optimal control problem is formulated via Pontryagin's Maximum Principle to identify schedules …