Optimal Trajectories for Propellant-Free Rendezvous Missions

The paper provides a new approach to utilizing space environmental forces in time- and energy-optimal, propellant-less spacecraft rendezvous missions. Considering the nonlinear form of the relative dynamic equations, rendezvous missions are posed as optimal control problems subject to input saturation. We conduct a direct optimal control approach to obtain optimal trajectories and control inputs. Initially, we consider the differential drag only and conduct a comprehensive analysis of the effect of altitude on the required control input and achieved cost function. Lorentz forces are then utilized with the differential drag, reducing the time required for time-optimal missions. For energy-optimal missions with combined differential drag and Lorentz forces, a weighting matrix in the cost function is introduced to adjust the relative contributions of these forces

Oxidative Stress in Hemodialysis Pediatric Patients

BACKGROUND: Oxidative stress may play a role in complications of hemodialysis patients as atherosclerosis, thrombosis, and inflammation. AIM: The aim of the study was to evaluate the oxidative stress in hemodialysis pediatric patients through measurement of oxidative stress enzymes as paraoxanase activity (PON), arylesterase activity (ASA), superoxide dismutase (SOD) and also non-enzymatic antioxidant vitamins as vitamins A, C and E levels. METHODS: The study included 50 hemodialysis pediatric patients with mean age 11.4 ± 5.4 years and 30 normal children of matched sex and age as a control group. Assessment of oxidative stresses was done using ELIZA technique. RESULTS: SOD, ASA, and vitamin C were significantly lower among hemodialysis patients in comparison to control group (p = 0.004, 0.004, > 0.001 respectively). CONCLUSION: The study concluded that oxidative stress was common finding in hemodialysis pediatric patients which may play a role in complications encountered among these patients

Fetuin-A and Ghrelin Levels in Children with End Stage Renal Disease and the Effect of a Single Hemodialysis Session on Them

BACKGROUND: Fetuin-A and ghrelin have been implicated in cardiovascular diseases and mortality among end stage renal disease patients. The exact mechanisms have not been fully elucidated. There is robust data supporting an association between ghrelin and various cardiovascular conditions, and some common processes such as inflammation, oxidative stress, and endoplasmic reticulum stress have been implicated.AIM: This study was conducted to assay serum fetuin-A and ghrelin in chronic renal failure pediatric patients and to study changes in their level that may occur after a single hemodialysis.MATERIAL AND METHODS: Forty nine pediatric patients suffering from ESRD on maintenance hemodialysis (HD), 20 patients with chronic renal failure (CRF) not on dialysis and 35 healthy subjects as control group were included. The mean age of the study population was 10.58 ± 3.94, 10.62 ± 3.24 and 10.61 ± 3.97 years respectively. Serum fetuin-A and plasma acyl ghrelin levels were measured by using ELISA method.RESULTS: The present study revealed that predialysis serum fetuin-A level was significantly increased in pediatric HD patients compared with the normal population, while ghrelin levels were significantly reduced. Furthermore, serum levels of fetuin-A decreased significantly after a single HD session.CONCLUSION: Our study concluded that fetuin-A and acyl ghrelin may play a role in inflammatory process among HD pediatric patients which may account for cardiovascular insults and mortality but their use as biochemical markers among ESRD pediatric patients have limitations due to wide fluctuations

Soil Contamination With Heavy Metals and Its Effect on Growth, Yield and Physiological Responses of Vegetable Crop Plants (Turnip and Lettuce)

The present study was conducted to investigate the impact of irrigation with industrial wastewater on soil and plant. For these purpose turnip and lettuce plants were cultivated in soil irrigated with wastewater then heavy metals content of the soil, plant growth, yield and the subsequent changes in biochemical constituents of plant were examined. Irrigation with wastewater was found to load the soil with heavy metals (Pb, Co, Ni and Cd) that were not detected in soil before irrigation. The magnitude of Cd in soils after irrigation with industrial wastewater exceeds the maximum allowable limit (3 mg Kg-1). Both turnip and lettuce exhibited significant decreases in leaf area, fresh weight and dry weight of shoots and roots as well as all the measured yield components in response to wastewater irrigation. The magnitude of decrease was positively correlated with the amounts of heavy metals detected in the soil and the inhibitory effect on turnip was much more pronounced than in lettuce. Furthermore, heavy metals accumulation in soil resulted in an oxidative damage to turnip and lettuce as indicated by the significant increase in lipid peroxidation and H2O2 levels in both plants comparing to control values. The significant increases in putrescine in lettuce and turnip shoots and roots and spermidine in lettuce roots as well as total phenolics and flavonoids in plants cultivated in soil enriched with heavy metals are believed to be defense mechanisms in turnip and lettuce plants to counteract the oxidative stress resulted from heavy metals contamination generated from irrigation with wastewater

Visfatin versus Flow-Mediated Dilatation as a Marker of Endothelial Dysfunction in Pediatric Renal Transplant Recipients

BACKGROUND: Renal transplantation (RTx) is the treatment of choice for paediatric end-stage renal disease (ESRD). A major cause of morbidity and mortality after RTx is cardiovascular disease. Independent predictors of cardiovascular events were shown to constitute an endothelial dysfunction (ED). This study aims to evaluate Visfatin serum level in comparison to brachial artery flow-mediated dilatation (FMD) as a marker of endothelial dysfunction in paediatric RTx recipients.METHODS: Visfatin serum level has been evaluated in 30 patients on regular hemodialysis (HD), 36 patients post-RTx and 30 controls as a measure for ED, and has been compared to brachial artery FMD.RESULTS: Visfatin level in transplant recipients was significantly lower than the hemodialysis group as well as FMD was better in transplant recipients. In spite of marked improvement of FMD and marked reduction of visfatin in post-RTx no direct statistical correlation was found between serum Visfatin level and flow-mediated dilatation.CONCLUSION: Pediatric RTx recipients show lower serum Visfatin level and better FMD than those on regular hemodialysis, reflecting less endothelial dysfunction (ED) and less cardiovascular risk. FMD in kidney transplant recipients tends to be less than normal subjects while visfatin level of the same group is similar to controls. Pediatric RTx appears to have a positive impact on the growth development of children with ESRD

Prevalence and Anti-Microbial Susceptibility of Hospital Acquired Infections in Two Pediatric Intensive Care Units in Egypt

BACKGROUND: Hospital-acquired (nosocomial) infection is a common serious health problem worldwide, especially in pediatric intensive care units and is associated with high mortality and morbidity, prolonged hospital stays and high cost.AIM: To determine the types of organisms involved in hospital-acquired an infection in two pediatric intensive care units during the one-year study and its anti-microbial susceptibility.MATERIAL AND METHODS: This study was carried out in the pediatric intensive care units (PICU) of Ain Shams & Cairo Universities, where 86 pediatric patients were recruited. Their age ranged from 1 month to 156 months with mean 20.7 ± 25.8 months. Male to female ratio was 37:29. Four samples were collected from each child for culture and sensitivity: blood, endotracheal aspirate, urine and skin swab.RESULTS: The most common microorganism was staphylococcus while Gram-negative bacteria were the commonest group. Amikacin and imipenem are the most sensitive antibiotics. Risk estimate for different risk factors among studied patients revealed no significance.CONCLUSION: Staphylococcus was the commonest micro-organism while Gram-negative infections were the commonest group among PICU with a predominance of Acinetobacter and Klebsiella. Respiratory infections were the most common, followed by blood-borne infection. Risk factors for mortality were not significant

Evaluation of Rezum therapy as a minimally invasive modality for management of Benign Prostatic Hyperplasia: A prospective observational study

Objective: To evaluate safety and efficacy of Rezum therapy as a minimally invasive modality for management of benign prostatic hyperplasia in patients with prostate volume 80cc. Methods: Between June 2020 and February 2023, A total of 98 patients diagnosed with BPH and managed by Rezum were included in this study. Patients were divided based on their prostate volume of either less than 80 cc or greater than 80 cc. We evaluated several parameters related to their condition, including prostate volume, post-voiding residual (PVR) before and after surgery, number of treatments received, maximum urine flow rate (Qmax) before and after surgery and mean follow- up periods. Results: The mean age was 68 years (SD 11.2). The median prostatic volume was 62 cc (IQR 41, 17). A maximum of 9 treatments were administered. Six months was determined to be the average post-operative follow-up period (IQR: 3.5-7.2). The mean preoperative total PSA was 2.7 (IQR 1, 2), preoperative mean PVR was 79.8 cm3, preoperative mean Qmax was 8.2 ml/s (IQR 4.7-10.5), and median post-operative days until catheter removal was four days (IQR 3,1). Post-operative PVR was 24.7 cm3 (IQR 18.2, 29.4) and the mean post-operative Qmax was 18.3 ml/s (SD 6.3). Qmax levels significantly increased, by an average of 8.2 ml/s (SD 7.13) (p < 0.001). Similarly, a decrease of average PVR of 97.28 cm3 (SD 95.85) (p < 0.001) was detected, which is a substantial reduction. Between prostates less 80cc and those over 80cc, there were no appreciable differences in Qmax or PVR (p-values: 0.435 and 0.431, respectively). Conclusions: From our study, we conclude that Rezum water vapor thermal therapy, as a minimally invasive modality, is an effective and safe surgical option for management of benign prostatic hyperplasia of men with moderate to severe lower urinary tract symptoms (LUTS). This procedure has been shown to be effective in patients with varying larger prostate volumes

A multidisciplinary approach to sphincter pharyngoplasty for correction of velopharyngeal dysfunction following repair of cleft palate

Background: Management of severe velopharyngeal dysfunction is best performed by a multispecialty team. This team could include a speech-language pathologist, otolaryngologist, prosthodontist, and a plastic surgeon. The most commonly performed surgical procedures in complicated cases with scarred soft palate are sphincter pharyngoplasty and pharyngeal flaps. In this study, a multidisciplinary approach was applied for proper assessment and surgical intervention using sphincter pharyngoplasty for velopharyngeal insufficiency after cleft palate repair. Methods: Twenty patients underwent sphincter pharyngoplasty. Preoperative diagnosis was performed using auditory perceptual assessment, nasoendoscopy assessment, nasometry, and videofluoroscopy. Results: There were statistically significant differences between the preoperative and postoperative assessments. Bleeding occurred in two patients. Obstructive sleep apnea occurred in three patients and was resolved spontaneously within three months, and one patient experienced slight wound dehiscence. Conclusion: Velopharyngeal dysfunction after cleft palate repair is best treated by a multidisciplinary team through speech therapy together with sphincter pharyngoplasty