Characterization and Biocompatibility Assessment of Boron Nitride Magnesium Nanocomposites for Orthopedic Applications.

Magnesium (Mg) has been intensively studied as a promising alternative material to inert metallic alloys for orthopedic fixation devices due to its biodegradable nature inside the body and its favorable biocompatibility. However, the low mechanical strength and rapid corrosion of Mg in physiological environments represent the main challenges for the development of Mg-based devices for orthopedic applications. A possible solution to these limitations is the incorporation of a small content of biocompatible nanoparticles into the Mg matrix to increase strength and possibly corrosion resistance of the resulting nanocomposites. In this work, the effect of adding boron nitride (BN) nanoparticles (0.5 and 1.5 vol.%) on the mechanical properties, corrosion behavior, and biocompatibility of Mg-based nanocomposites was investigated. The properties of the nanocomposites fabricated using powder metallurgy methods were assessed using microstructure analyses, microhardness, compression tests, in vitro corrosion, contact angle, and cytotoxicity tests. A significant increase in the microhardness, strength, and corrosion rates of Mg-BN nanocomposites was detected compared with those of pure Mg (0% BN). Crystalline surface post-corrosion byproducts were detected and identified via SEM, EDX, and XRD. Biocompatibility assessments showed that the incorporation of BN nanoparticles had no significant impact on the cytotoxicity of Mg and samples were hydrophilic based on the contact angle results. These results confirm that the addition of BN nanoparticles to the Mg matrix can increase strength and corrosion resistance without influencing cytotoxicity in vitro. Further investigation into the chemical behavior of nanocomposites in physiological environments is needed to determine the potential impact of corrosive byproducts. Surface treatments and formulation methods that would increase the viability of these materials in vivo are also needed.

In Vivo Assessment of High-Strength and Corrosion-Controlled Magnesium-Based Bone Implants.

The biodegradable nature of magnesium in aqueous mediums makes it an attractive material for various biomedical applications when it is not recommended that the material stay permanently in the body. Some of the main challenges that hinder the use of magnesium for bone fracture repair are its limited mechanical strength and fast corrosion rates. To this end, we developed a novel Mg-Zn-Ca-Mn-based alloy and post-fabrication methods that can deliver high-strength and corrosion-controlled implant materials to address these challenges. This study is focused on assessing the in vitro corrosion and in vivo biocompatibility of the developed magnesium-based alloy and post-fabrication processes. The developed heat treatment process resulted in an increase in the microhardness from 71.9 ± 5.4 HV for the as-cast Mg alloy to as high as 98.1 ± 6.5 HV for the heat-treated Mg alloy, and the ceramic coating resulted in a significant reduction in the corrosion rate from 10.37 mm/yr for the uncoated alloy to 0.03 mm/yr after coating. The in vivo assessments showed positive levels of biocompatibility in terms of degradation rates and integration of the implants in a rabbit model. In the rabbit studies, the implants became integrated into the bone defect and showed minimal evidence of an immune response. The results of this study show that it is possible to produce biocompatible Mg-based implants with stronger and more corrosion-controlled properties based on the developed Mg-Zn-Ca-Mn-based alloy and post-fabrication methods.

The Evaluation of Cartilage Regeneration Efficacy of Three-Dimensionally Biofabricated Human-Derived Biomaterials on Knee Osteoarthritis: A Single-Arm, Open Label Study in Egypt.

Full thickness cartilage defects in cases of knee osteoarthritis are challenging in nature and are difficult to treat. The implantation of three-dimensional (3D) biofabricated grafts into the defect site can be a promising biological one-stage solution for such lesions that can avoid different disadvantages of the alternative surgical treatment options. In this study, the short-term clinical outcome of a novel surgical technique that uses a 3D bioprinted micronized adipose tissue (MAT) graft for knee cartilage defects is assessed and the degree of incorporation of such graft types is evaluated via arthroscopic and radiological analyses. Ten patients received 3D bioprinted grafts consisting of MAT with an allogenic hyaline cartilage matrix on a mold of polycaprolactone, with or without adjunct high tibial osteotomy, and they were monitored until 12 months postoperatively. Clinical outcomes were examined with patient-reported scoring instruments that consisted of the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score and the Knee Injury and Osteoarthritis Outcome Score (KOOS). The graft incorporation was assessed using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. At 12 months follow-up, cartilage tissue biopsy samples were taken from patients and underwent histopathological examination. In the results, at final follow-up, the WOMAC and KOOS scores were 22.39 ± 7.7 and 79.16 ± 5.49, respectively. All scores were significantly increased at final follow-up (p < 0.0001). MOCART scores were also improved to a mean of 82.85 ± 11.49, 12 months after operation, and we observed a complete incorporation of the grafts with the surrounding cartilage. Together, this study suggests a novel regeneration technique for the treatment of knee osteoarthritis patients, with less rejection response and better efficacy.

Impact of changing PI-RADS cutoff on prostate cancer detection by MRI cognitive fusion biopsy in biopsy-naïve patients.

BACKGROUND: Multi-parametric magnetic resonance imaging may improve the detection of prostate cancer. The aim of this work is to compare between PI-RADS 3-5 and PI-RADS 4-5 as a threshold for targeted prostatic biopsy. METHODS: This is a prospective clinical study that included 40 biopsy-naïve patients referred for prostate biopsy. Patients underwent prebiopsy multi-parametric (mp-MRI), followed by 12-core transrectal ultrasound-guided systematic biopsy and cognitive MRI/TRUS fusion targeted biopsy from each detected lesion. The primary endpoint was to assess the diagnostic accuracy of the PI-RAD 3-4 versus PI-RADS 4-5 lesion by mpMRI for prostate cancer detection in biopsy-naive men. RESULTS: The overall prostate cancer detection rate and the clinically significant cancer detection rate were 42.5% and 35%, respectively. Targeted biopsies from PI-RADS 3-5 lesions showed a sensitivity of 100%, specificity of 44%, positive predictive value of 51.7%, and negative predictive value of 100%. Restricting targeted biopsies to PI-RADS 4-5 lesions resulted in a decrease in sensitivity and negative predictive value to 73.3% and 86.2%, respectively, while specificity and positive predictive value were increased to 100% for both parameters which was statistically significant (P value < 0.0001 and P value = 0.004, respectively). CONCLUSIONS: Limiting the TBs to PI-RADS 4-5 lesions improves the performance of mp-MRI in the detection of prostate cancer especially aggressive tumors.

Fungal brain abscesses caused by Acremonium species.

Unusual fungal agents that exist environmentally as saprophytes can often lead to opportunistic infections, hyalohyphomycosis is a group of fungal infections caused by fungi characterized by hyaline septate hyphae and can infect both immunocompetent as well as immunocompromised patients, and Acremonium has drawn the attention of clinicians and microbiologists, as a potential pathogen in patients with and without underlying risk factors. It has also been increasingly implicated in systemic fungal diseases. Herein, we describe a case presentation of an immunocompromised patient with fungal brain abscesses due to Acremonium species.

Distal hypospadias repair: Comparative study between snodgrass and transverse preputial onlay flap.

INTRODUCTION: Distal hypospadias repair has several operative strategies such as tubularized incised plate (TIP); Transverse preputial onlay flap (TPOF) and Modified Mathieu Procedure. The aim of our work is to compare between TIP and TPOF techniques in the outcome. MATERIAL AND METHOD: We conducted this comparative study on 66 patients with different types of distal hypospadias divided in two groups A and B for TIP and TPOF respectively. We reported outcome and complications for both TIP and TPOF repair. Our results revealed mean operative time was significantly higher in group B (123.1 ± 6.8 min) than in group A (93.73 ± 3.9 min, P value < 0.001). Postoperative urinary fistula was reported in group A (15.2%) while no fistula in group B (p value = 0.05). The vertical slit appearance of meatus was better in group A (54.5%) than in group B (24.2%, P value 0.023). As regard to hypospadias objective scoring evaluation (HOSE) (Summary Figure) the meatal shape score was higher in group A (1.55 ± 0.51) than in group B (1.24 ± 0.44, p value = 0.0 l), the urinary stream score was significantly higher in group A (1.82 ± 0.39) than in group B (1.97 ± 0.17, p value = 0.04) and the urinary fistula score was significantly higher in group A (3.79 ± 0.60) than in group B (4 ± 0, p value = 0.04). DISCUSSION: Complications are more common after TIP than in TPOF. As regard the meatus shape, the naturally looking vertical slit like meatus was achieved more in the TIP than in TPOF. We advocate further studies with a large number of patients with a long follow up period. CONCLUSION: TPOF is a great option to consider in cases of distal hypospadias because it is an effective technique for primary distal hypospadias repair with a good cosmetic outcome and a low associated complication.

Does the Inverted Kidney Transplantation Technique Promote the Feasibility and Safety of Right Living Donor Nephrectomy?

OBJECTIVE: The aim of this study is to compare the outcomes of right- and left-sided live donor nephrectomies using the inverted kidney transplantation technique for right live donor nephrectomy on transplantation. MATERIAL AND METHODS: A retrospective review was done for the cases of live donor nephrectomy, either as open donor nephrectomy or laparoscopic donor nephrectomy between 2004 and 2019. Inverted kidney transplantation was used with right-sided grafts. The variables of the right- and left-sided live donor nephrectomies were compared. RESULTS: There were 202 live donor nephrectomies including 71 (35.1%) open donor nephrectomies and 131 (64.9%) laparoscopic donor nephrectomies with 4 cases of conversion to open donor nephrectomy. There were 119 (58.9%) right-sided and 83 (41.1%) left-sided live donor nephrectomies with insignificantly different mean operative time (123 and 127 minutes; P=.09), mean warm ischemia time (82.3 and 84.5 seconds; P=.32), and mean blood loss (73 and 78 mL; P=.18), respectively. Inverted kidney transplantation was performed for 86% of grafts from right live donor nephrectomies. Discharge from hospital was on an average of 4.3 days postoperatively. There were only 3 complications (1 in right live donor nephrectomy and 2 in left live donor nephrectomies) with grade 2 according to Clavien-Dindo Classification. Incidence of delayed graft function (P=.09), transplant vein thrombosis (1 case in each group), 1-year graft survival rate (93.2% vs. 94.8%; P=.12), and 1-year serum creatinine levels (1.4 ± 0.3 vs. 1.3 ± 0.2; P=.09) revealed statistically insignificant differences. CONCLUSION: Regardless of the surgical technique, the right live donor nephrectomy seems to be technically as safe as the left live donor nephrectomy for both the donors and the recipients. Using inverted kidney transplantation provided convenient extensions of graft's vessels to full length with no significant increased incidence of vascular thrombosis.

Diagnostic value of salivary gland ultrasonography for secondary Sjögren syndrome in patients with systemic lupus erythematosus.

BACKGROUND: Salivary gland ultrasound (SGUS) is a reliable technique for assessing the salivary glands in patients with primary Sjögren's syndrome (SS); however, the role of SGUS for diagnosis of secondary SS (sSS) in patients with systemic lupus erythematosus (SLE) was not examined. OBJECTIVE: To assess the diagnostic value of SGUS for sSS in patients with SLE, and to investigate the relationship between SGUS findings with clinical and laboratory characteristics of patients with SLE. PATIENTS AND METHODS: This cross-sectional study included 49 patients with SLE. The diagnosis of sSS was confirmed according to the 2016 ACR/EULAR criteria. Salivary gland US was performed for all patients and graded using a validated Hocevar scoring system. A complete clinical and laboratory workup for SLE was assessed. Schirmer's test and the ocular staining were performed. RESULTS: Of the 49 patients with a mean age of 30.2 ± 9.6 years, 98% were female. 19 (38.8%) had sSS. SGUS changes consistent with sSS (≥17) were found in 29 (59.2%) of the patients. Patients with higher SGUS score had more sicca findings as well as positive anti-Ro, anti-La antibodies, and poorer psychological stress (p < 0.05). The SGUS (≥17) showed a sensitivity of 84.2% and a specificity of 56.7% for sSS diagnosis, with an area under the curve of 0.77 (95% CI: 0.63, 0.91). CONCLUSION: We propose salivary gland ultrasound as a non-invasive method in the diagnostic workup for sSS in patients with SLE. Further studies to confirm the diagnostic value of SGUS in a larger sample of patients with sSS will be necessary.

Mental health research in the Arab region in response to the COVID-19 pandemic: a scoping review.

Background: The ongoing pandemic has led to a global surge in coronavirus disease 2019 (COVID-19)-related mental health research. However, most related publications come from Western countries or China, and their findings cannot always be extrapolated to Arab countries. Aims: This study provides a quantitative and qualitative analysis of mental health research pertaining to Arab countries' response to the COVID-19 pandemic. Methods: A scoping review of the World Health Organization (WHO) COVID-19 database for publications on mental health was conducted by authors affiliated with Arab institutions, including articles from inception to 24 October 2020. The included publications were evaluated for their national distribution, international collaboration, publication type, and main research themes. Methodological quality analysis of the included research studies was performed using the original and modified versions of the Newcastle-Ottawa Scale. Results: In total, 102 articles were included in this study, averaging 4.6 articles per Arab country. Most of the articles emerged from the Kingdom of Saudi Arabia, Jordan, and Egypt. A majority of publications demonstrated international collaboration. Most of the publications were original research studies and cross-sectional in design. The predominant research theme was examining the pandemic's mental health effects on the general population and healthcare workers. Only 28.0% of the studies were of high methodological quality, whereas 41.5% were moderate and 30.5% were low in quality. Conclusions: Mental health research in response to the COVID-19 pandemic in the Arab region has quantitative and qualitative shortfalls. Arab institutions need to respond to the pandemic promptly in order to address the delineated research gap and to generate higher-quality research output.

Clinical evaluation of pregnant women with SARS-COV2 pneumonia: a real-life study from Egypt.

BACKGROUND: Knowledge about the outcome of COVID-19 on pregnant women is so important. The published literature on the outcomes of pregnant women with COVID-19 is confusing. The aim of this study was to report our clinical experience about the effect of COVID-19 on pregnant women and to determine whether it was associated with increased mortality or an increase in the need for mechanical ventilation in this special category of patients. METHODS: This was a cohort study from some isolation hospitals of the Ministry of Health and Population, in eleven governorates, Egypt. The clinical data from the first 64 pregnant women with COVID-19 whose care was managed at some of the Egyptian hospitals from 14 March to 14 June 2020 as well as 114 non-pregnant women with COVID-19 was reviewed. RESULTS: The two groups did not show any significant difference regarding the main outcomes of the disease. Two cases in each group needed mechanical ventilation (p 0.617). Three cases (4.7%) died among the pregnant women and two (1.8%) died among the non-pregnant women (p 0.352). CONCLUSIONS: The main clinical outcomes of COVID-19 were not different between pregnant and non-pregnant women with COVID-19. Based on our findings, pregnancy did not exacerbate the course or mortality of COVID-19 pneumonia.

Utility of Lung Ultrasound in Decision-making to Prioritize Hospital Admission for COVID-19 Patients: A Developing Country Perspective.

BACKGROUND AND AIMS: In the midst of this pandemic, planning the prioritization of hospital admissions for patients affected with COVID-19 should be of prime concern, particularly in healthcare settings with limited resources. Thus, in this study, we aimed to develop a novel approach to triage COVID-19 patients and attempt to prioritize their hospital admission using Lung Ultrasonography (LUS). The efficacy of LUS in triaging suspected COVID-19 patients and assessing the severity of COVID-19 pneumonia was evaluated; the findings were then compared with those obtained by chest computed tomography (CT). METHODS: This multicenter, cross-sectional study comprised 243 COVID-19 patients who presented to the emergency department in 3 major university hospitals in Egypt. LUS was performed by an experienced emergency or chest physician, according to the local protocol of each hospital. Demographic, clinical, and laboratory data were then collected from each patient. Each patient was subjected to chest CT scans and LUS. RESULTS: The mean age of the 243 patients was 46.7 ± 10.4 years. Ground-glass opacity, subpleural consolidation, translobar consolidation, and crazy paving were reported in the chest CT scans of 54.3%, 15.2%, 11.1%, and 8.6% of the patients, respectively. B-line artifacts were observed in 81.1% of the patients (confluent pattern, 18.9%). The LUS findings completely coincided with the CT findings (Kappa agreement value, 0.77) in 197 patients (81.1%) and offered a diagnostic sensitivity of 74%, diagnostic specificity of 97.9%, positive predictive value of 90.2%, and negative predictive value of 93.6% for the COVID-19 patients. Following the addition of O2 saturation to the lung imaging findings, the ultrasound method was able to demonstrate 100% sensitivity and specificity in accurately differentiating between severe and non-severe lung diseases. CONCLUSION: LUS with oxygen saturation might prove to be effective in prioritizing the hospital admission of COVID-19 patients, particularly in healthcare settings with limited resources.

Comparison of the CO-RADS and the RSNA chest CT classification system concerning sensitivity and reliability for the diagnosis of COVID-19 pneumonia.

BACKGROUND: The Radiological Society of North America (RSNA) recently published a chest CT classification system and Dutch Association for Radiology has announced Coronavirus disease 2019 (COVID-19) reporting and data system (CO-RADS) to provide guidelines to radiologists who interpret chest CT images of patients with suspected COVID-19 pneumonia. This study aimed to compare CO-RADS and RSNA classification with respect to their sensitivity and reliability for diagnosis of COVID-19 pneumonia. RESULTS: A retrospective study assessed consecutive CT chest imaging of 359 COVID-19-positive patients. Three experienced radiologists who were aware of the final diagnosis of all patients, independently categorized each patient according to CO-RADS and RSNA classification. RT-PCR test performed within one week of chest CT scan was used as a reference standard for calculating sensitivity of each system. Kappa statistics and intraclass correlation coefficient were used to assess reliability of each system. The study group included 359 patients (180 men, 179 women; mean age, 45 ± 16.9 years). Considering combination of CO-RADS 3, 4 and 5 and combination of typical and indeterminate RSNA categories as positive predictors for COVID-19 diagnosis, the overall sensitivity was the same for both classification systems (72.7%). Applying both systems in moderate and severe/critically ill patients resulted in a significant increase in sensitivity (94.7% and 97.8%, respectively). The overall inter-reviewer agreement was excellent for CO-RADS (κ = 0.801), and good for RSNA classification (κ = 0.781). CONCLUSION: CO-RADS and RSNA chest CT classification systems are comparable in diagnosis of COVID-19 pneumonia with similar sensitivity and reliability.

Beneficial effects of (-)-epigallocatechin-3-O-gallate on diabetic peripheral neuropathy in the rat model.

Diabetic neuropathic pain is characterized by spontaneous pain with hyperalgesia and allodynia. We investigated whether (-)-epigallocatechin-3-O-gallate could improve diabetic neuropathic pain development through hypoglycemic, hypolipidemic, antioxidant, and anti-inflammatory effects. Diabetes was induced in rats by streptozotocin (55 mg/kg/once) and treated with (-)-epigallocatechin-3-O-gallate (25 mg/kg/orally/once/daily/5 weeks). Diabetic rats showed an increase in serum levels of glucose, nitric oxide, triglyceride, total cholesterol, and low-density lipoprotein-cholesterol with a decrease in high-density lipoprotein-cholesterol and body weight. Also, there was an elevation in brain malondialdehyde with a marked reduction in brain levels of glutathione, superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase. Furthermore, diabetic rats showed a clear reduction in plasma levels of insulin and an increase in plasma cytokines (interleukin-6 and tumor necrosis factor-α). Moreover, diabetic rats exhibited hyperalgesia as indicated by a hot plate, tail immersion, formalin, and carrageenan-induced edema tests as well as brain histopathological changes (neuron degeneration, gliosis, astrocytosis, congestion and hemorrhage). (-)-Epigallocatechin-3-O-gallate treatment ameliorated alterations in body weight, biochemical parameters, pain sensation, and histopathological changes in brain tissue. (-)-Epigallocatechin-3-O-gallate offers promising hypoglycemic, hypolipidemic, antioxidant and anti-inflammatory effects, which can prevent the development and progression of diabetic neuropathic pain.

A population-based study of the epidemiology and the risk factors for male infertility in Kuwait.

PURPOSE: Infertility has become one of the foremost public health concerns, affecting a large number of couples. This research aimed to study and analyze the epidemiological data of male infertility including demographic characteristics and potential accountable factors. MATERIALS AND METHODS: A population-based study was carried out among male patients of one center. Different factors have been investigated such as family history, smoking, and varicocele. Data were analyzed using the STATA statistical software package. RESULTS: A total of 608 male patients aged between 22 and 56 years were included. Out of them, there were 544 (89.95%) married, 48 (7.9%) married more than once, and 10 (1.6%) divorced. Primary infertility was noted in 478 (78.6%) patients. The most commonly reported sexual disorder was erectile dysfunction 53 (8.7%), while decreased libido was detected in 8 (1.3%) patients. Varicocele was present among 507 (86%) patients. Semen analyses of infertile patients revealed that 43 (8.2%) cases had normal semen tests. In contrast, oligoasthenospermia was the most commonly reported semen abnormality 158 (30.2%). A total of 198 patients underwent assisted reproductive technique. CONCLUSION: This study concluded that primary infertility is the most common type among all infertile male patients who visited our center. The risk factors of male infertility include positive family history, smoking, and varicocele.

"Effect of Zn content and aging temperature on the in-vitro properties of heat-treated and Ca/P ceramic-coated Mg-0.5%Ca-x%Zn alloys".

While potentially strong enough for load-bearing skeletal reconstruction applications, the corrosion (biodegradation) rate of biocompatible Mg-Zn-Ca-based alloys still presents. The present work reports on the use of heat treatment (strengthening and resorption delaying) and micro arc oxidation (MAO) coating (corrosion delaying) processes which were developed to induce desirable corrosion rates which are essential to maintaining the mechanical integrity of Mg-Zn-Ca-based alloys during the bone healing period. Three Mg-x%Zn-0.5%Ca (wt%) alloys with different levels of Zn content (1.2, 1.6 and 5 wt%) were prepared and heat-treated at different age hardening temperatures (100, 150, 200 and 250 °C). In order to further decrease the corrosion rate and improve the bioactivity, samples of the heat-treated Alloy I (Mg-1.2wt%Zn-0.5wt%Ca) at the optimized age-hardening conditions were successfully coated with a biocompatible composite coating without and with HA/ß-TCP nanoparticles by using an MAO process. The microstructure, morphology and the composition of the heat-treated and coated materials were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Hardness and compression tests were conducted, while a corrosion investigation of heat-treated and coated samples was performed using potentiodynamic polarization (PDP) and a mechanical integrity immersion test. The results confirmed that Zn content and age hardening temperature have significant effects on the mechanical and corrosion properties of heat-treated Mg-Zn-Ca-based alloys. Alloy I, which has 1.2 wt% Zn content and was aged at 200 °C, showed the best combination of corrosion (slowest) and mechanical (highest) properties. The MAO (HA/ß-TCP) composite coating significantly improved corrosion resistance compared to the uncoated heat-treated alloy, with only 11.3% reduction in the compressive strength after 8 weeks of immersion.

Engineering Bone-Implant Materials.

This special issue is dedicated to the simulation as well as experimental studies of biomechanical behavior of biomaterials, especially those that are used for bone implant applications [...].

Mini vs standard percutaneous nephrolithotomy for renal stones: a comparative study.

To compare the outcome of mini-percutaneous nephrolithotomy (Mini-PNL) versus standard-PNL for renal stones. Retrospective study was performed between March 2010 and May 2013 for patients treated by Mini-PNL or standard-PNL through 18 and 30 Fr tracts, respectively, using pneumatic lithotripsy. Semirigid ureteroscope (8.5/11.5 Fr) was used for Mini-PNL and 24 Fr nephroscope for standard-PNL. Both groups were compared in stone free rate(SFR), complications and operative time using Student-t, Mann-Whitney, Chi square or Fisher's exact tests as appropriate in addition to logistic regression analysis. P < 0.05 was considered statistically significant. Mini-PNL (378) and standard-PNL (151) were nearly comparable in patients and stones criteria including stone burden (3.77 ± 2.21 vs 3.77 ± 2.43 cm2; respectively). There was no significant difference in number of tracts or supracostal puncture. Mini-PNL had longer operative time (68.6 ± 29.09 vs 60.49 ± 11.38 min; p = 0.434), significantly shorter hospital stay (2.43 ± 1.46 vs 4.29 ± 1.28 days) and significantly higher rate of tubeless PNL (75.1 vs 4.6%). Complications were significantly higher in standard-PNL (7.9 vs 20.5%; p < 0.001). SFR was significantly lower in Mini-PNL (89.9 vs 96%; p = 0.022). This significant difference was found with multiple stones and large stone burden (> 2 cm2), but the SFR was comparable between both groups with single stone or stone burden ≤ 2 cm. Logistic regression analysis confirmed significantly higher complications and SFR with standard-PNL but with significantly shorter operative time. Mini-PNL has significantly lower SFR when compared to standard-PNL (but clinically comparable) with markedly reduced complications and hospital stay. Most of cases can be performed tubeless. The significant difference in SFR was found with multiple stones or large stone burden (> 2 cm2), but not with single stones or stone burden ≤ 2 cm2.

Predicting the Biodegradation of Magnesium Alloy Implants: Modeling, Parameter Identification, and Validation.

Magnesium (Mg) and its alloys can degrade gradually up to complete dissolution in the physiological environment. This property makes these biomaterials appealing for different biomedical applications, such as bone implants. In order to qualify Mg and its alloys for bone implant applications, there is a need to precisely model their degradation (corrosion) behavior in the physiological environment. Therefore, the primary objective develop a model that can be used to predict the corrosion behavior of Mg-based alloys in vitro, while capturing the effect of pitting corrosion. To this end, a customized FORTRAN user material subroutine (or VUMAT) that is compatible with the finite element (FE) solver Abaqus/Explicit (Dassault Systèmes, Waltham, MA, USA) was developed. Using the developed subroutine, a continuum damage mechanism (CDM) FE model was developed to phenomenologically estimate the corrosion rate of a biocompatible Mg⁻Zn⁻Ca alloy. In addition, the mass loss immersion test was conducted to measure mass loss over time by submerging Mg⁻Zn⁻Ca coupons in a glass reactor filled with simulated body fluid (SBF) solution at pH 7.4 and 37 °C. Then, response surface methodology (RSM) was applied to calibrate the corrosion FE model parameters (i.e., Gamma (γ), Psi (ψ), Beta (ß), and kinetic parameter (Ku)). The optimum values for γ, ψ, ß and Ku were found to be 2.74898, 2.60477, 5.1, and 0.1005, respectively. Finally, given the good fit between FE predictions and experimental data, it was concluded that the numerical framework precisely captures the effect of corrosion on the mass loss over time.

Bilateral Single-session vs Staged Mini-percutaneous Nephrolithotomy for Renal Stones: A Comparative Study.

OBJECTIVE: To compare safety and efficacy of bilateral single-session mini-percutaneous nephrolithotomy (BSS-Mini-PNL) vs staged-Mini-PNL. PATIENTS AND METHODS: Adult patients with bilateral renal stones indicated for PNL were managed with BSS-Mini-PNL (45 patients and 90 renal units) and prospectively compared vs staged-Mini-PNL (55 patients and 110 renal units) between July 2014 and December 2017. Mini-PNL was done through 18-Fr tract in prone position under regional anesthesia and fluoroscopy using pneumatic lithotripsy. A semirigid ureteroscope (8.5/11.5 Fr) was used. Mann-Whitney, Student t, chi-square, or Fisher's exact tests were used as appropriate. RESULTS: Both groups were comparable in characteristics of stones and patients. Stone burden was 3.36 ± 1.61 vs 3.38 ± 1.18 cm2 in BSS-Mini-PNL vs staged-Mini-PNL, respectively. Staghorn stones were present in 13.3% vs 8.2% in BSS-Mini-PNL vs staged-Mini-PNL, respectively. There was no significant difference in the number of required tracts (1.34 ± 0.6 vs 1.25 ± 0.51 tract/renal unit) as well as the rate of tubeless Mini-PNL (81.1% vs 85.5%) or stone-free rate (90% vs 92.7%) in BSS-Mini-PNL vs staged-Mini-PNL, respectively. BSS-Mini-PNL had significantly shorter operative time (126.22 ± 37.2 vs 169.63 ± 61.28 minutes), shorter hospital stay (2 [1-8] vs 4 [2-16] days) and higher hemoglobin loss (1.1 [0.1-2.8] vs 0.5 [0.1-2.17] gm/d) than staged-Mini-PNL. The complications profile (17.8% vs 13.6%) and rate of blood transfusion (4.4% vs 3.6%) were comparable in BSS-Mini-PNL vs staged-Mini-PNL, respectively, without significant difference. CONCLUSION: BSS-Mini-PNL is comparable to staged-PNL as regard stone-free rate and complications according to the selection criteria of the present study. However, BSS-Mini-PNL is associated with significant reduction in the cumulative operative time and hospital stay, which are reflected on the overall cost.

Microstructural, mechanical and corrosion characteristics of heat-treated Mg-1.2Zn-0.5Ca (wt%) alloy for use as resorbable bone fixation material.

Mg-Zn-Ca alloys have grabbed most of the recent attention in research attempting to develop an Mg alloy for bone fixation devices due to their superior biocompatibility. However, early resorption and insufficient strength remain the main problems that hinder their use. Heat treatment has previously been thoroughly studied as a post-shaping process, especially after the fabrication of complex parts (e.g. porous structures) by 3D-printing or powder metallurgy. In this work, the effect of heat treatment on Mg-1.2Zn-0.5Ca (wt%) alloy's microstructural, mechanical and corrosion properties was studied. The surface morphology of samples was characterized by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD). Hardness, compression and tensile tests were conducted, while the in vitro corrosion characteristics of the prepared samples were determined using potentiodynamic polarization (PDP) and immersion tests. It was found that increasing the age hardening duration up to 2-5h increased the heat-treated Mg-1.2Zn-0.5Ca alloy's mechanical properties. Further increase in the age hardening duration did not result in further enhancement in mechanical properties. Similarly, heat treatment significantly altered the Mg-1.2Zn-0.5Ca alloy's in vitro corrosion properties. The corrosion rate of the Mg-1.2Zn-0.5Ca alloy after the heat treatment process was reduced to half of that for the as-cast alloy. XRD results showed the formation of biocompatible agglomerations of hydroxyapatite (HA) and magnesium hydroxide (Mg(OH)2) on the corroded surface of the heat-treated Mg-1.2Zn-0.5Ca alloy samples. The performed heat treatment process had a significant effect on both mechanical and corrosion properties of the prepared Mg-1.2Zn-0.5Ca alloy. The age hardening duration which caused the greatest increase in mechanical and the most slowed corrosion rate for Mg-1.2Zn-0.5Ca alloy material was between 2 and 5h.