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1.
PLoS One ; 19(7): e0305329, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38985844

RESUMO

The unit commitment (UC) optimization issue is a vital issue in the operation and management of power systems. In recent years, the significant inroads of renewable energy (RE) resources, especially wind power and solar energy generation systems, into power systems have led to a huge increment in levels of uncertainty in power systems. Consequently, solution the UC is being more complicated. In this work, the UC problem solution is addressed using the Artificial Gorilla Troops Optimizer (GTO) for three cases including solving the UC at deterministic state, solving the UC under uncertainties of system and sources with and without RE sources. The uncertainty modelling of the load and RE sources (wind power and solar energy) are made through representing each uncertain variable with a suitable probability density function (PDF) and then the Monte Carlo Simulation (MCS) method is employed to generate a large number of scenarios then a scenario reduction technique known as backward reduction algorithm (BRA) is applied to establish a meaningful overall interpretation of the results. The results show that the overall cost per day is reduced from 0.2181% to 3.7528% at the deterministic state. In addition to that the overall cost reduction per day is 19.23% with integration of the RE resources. According to the results analysis, the main findings from this work are that the GTO is a powerful optimizer in addressing the deterministic UC problem with better cost and faster convergence curve and that RE resources help greatly in running cost saving. Also uncertainty consideration makes the system more reliable and realistic.


Assuntos
Energia Solar , Vento , Incerteza , Método de Monte Carlo , Algoritmos , Energia Renovável , Processos Estocásticos , Modelos Teóricos
2.
Heliyon ; 10(11): e31767, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38841508

RESUMO

This paper proposes a new contribution in the field of optimizing control techniques for wind systems to enhance the quality of the energy produced in the grid. Although the Sliding Mode control technique, whether classical or involving the use of artificial intelligence, has shown interesting results, its main drawback lies in the oscillation phenomenon commonly referred to as "chattering." This phenomenon affects the accuracy and robustness of the system, as well as the parametric variation of the system. In this work, we propose a solution that combines two nonlinear techniques based on the Lyapunov theorem to eliminate the chattering phenomenon. It is a hybrid approach between the Backstepping strategy and the Sliding Mode, aiming to control the active and reactive powers of the doubly fed induction generator (DFIG) connected to the electrical grid by two converters (grid side and machine side). This hybrid technique aims to improve the performance of the wind system in terms of precision errors, stability, as well as active and reactive power. The proposed solution has been validated in the Matlab & Simulink environment to assess the performance and robustness of the proposed model, as well as experimentally validated on a test bench using the DSPACE 1104 card. The obtained results are then compared with other techniques, demonstrating a significant improvement in performance.

3.
Heliyon ; 10(10): e31025, 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38803921

RESUMO

Water is an essential requirement for agricultural productivity. In the agriculture sector, electricity generated by conventional sources contributes to a substantial amount of carbon footprints for pumping water through tube wells. Over the past few decades, a transitional shift towards renewable resources has increased leading to decarbonizing the environment and is considered as a viable solution for electricity production. To assist and provide a road map for this paradigm shift, the proposed study presents a techno-economic and environmental analysis of irrigation systems by carrying comparative analysis of both standalone and grid-connected systems based on four independent sites in a developing country. PV system integrated with grid enabling both energy purchase and sale (PV + G(P+S)), proved to be the most optimal configuration with cost of energy (COE) of $0.056/kWh, $0.059/kWh, $0.061/kWh, and $0.068/kWh while having net present cost (NPC) of $7,908, $20,186, $25,826, and $34,487 for Peshawar, Khyber Agency, Mardan, and Charsadda respectively, over a useful life span of 25 years. Furthermore, sensitivity analysis has been carried out based on uncertain variables such as Grid power purchase (GPP) and average solar radiation (GHI) to check the optimality behavior of the system. Results from environmental analysis revealed that (PV+ G(P+S)) system has a relatively low carbon impact as compared with conventional sources. This configuration also has the ability to prevent excess water extraction by selling any excessive solar PV energy to the grid. This study provides a policy framework insight for the entities for future optimization.

4.
PLoS One ; 19(4): e0300527, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38630760

RESUMO

This study tackles the complex task of integrating wind energy systems into the electric grid, facing challenges such as power oscillations and unreliable energy generation due to fluctuating wind speeds. Focused on wind energy conversion systems, particularly those utilizing double-fed induction generators (DFIGs), the research introduces a novel approach to enhance Direct Power Control (DPC) effectiveness. Traditional DPC, while simple, encounters issues like torque ripples and reduced power quality due to a hysteresis controller. In response, the study proposes an innovative DPC method for DFIGs using artificial neural networks (ANNs). Experimental verification shows ANNs effectively addressing issues with the hysteresis controller and switching table. Additionally, the study addresses wind speed variability by employing an artificial neural network to directly control reactive and active power of DFIG, aiming to minimize challenges with varying wind speeds. Results highlight the effectiveness and reliability of the developed intelligent strategy, outperforming traditional methods by reducing current harmonics and improving dynamic response. This research contributes valuable insights into enhancing the performance and reliability of renewable energy systems, advancing solutions for wind energy integration complexities.


Assuntos
Energia Renovável , Vento , Reprodutibilidade dos Testes , Sistemas Computacionais , Redes Neurais de Computação
5.
Heliyon ; 10(6): e27489, 2024 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-38515729

RESUMO

In a world grappling with escalating energy demand and pressing environmental concerns, microgrids have risen as a promising solution to bolster energy efficiency, alleviate costs, and mitigate carbon emissions. This article delves into the dynamic realm of microgrids, emphasizing their indispensable role in addressing today's energy needs while navigating the hazards of pollution. Microgrid operations are intricately shaped by a web of constraints, categorized into two essential domains: those inherent to the microgrid itself and those dictated by the external environment. These constraints, stemming from component limitations, environmental factors, and grid connections, exert substantial influence over the microgrid's operational capabilities. Of particular significance is the three-tiered control framework, encompassing primary, secondary, and energy management controls. This framework guarantees the microgrid's optimal function, regulating power quality, frequency, and voltage within predefined parameters. Central to these operations is the energy management control, the third tier, which warrants in-depth exploration. This facet unveils the art of fine-tuning parameters within the microgrid's components, seamlessly connecting them with their surroundings to streamline energy flow and safeguard uninterrupted operation. In essence, this article scrutinizes the intricate interplay between microgrid constraints and energy management parameters, illuminating how the nuanced adjustment of these parameters is instrumental in achieving the dual objectives of cost reduction and Carbon Dioxide emission minimization, thereby shaping a more sustainable and eco-conscious energy landscape. This study investigates microgrid dynamics, focusing on the nuanced interplay between constraints and energy management for cost reduction and Carbon Dioxide minimization. We employ a three-tiered control framework-primary, secondary, and energy management controls-to regulate microgrid function, exploring fine-tuned parameter adjustments for optimal performance.

7.
Heliyon ; 10(1): e23711, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38192851

RESUMO

A staircase-shaped quasi-fractal antenna is presented to meet the requirements of compact electronics operating in UWB or E-UWB spectrum. A conventional broadband monopole antenna is converted into UWB antenna utilizing three iterations of fractal patches. The resultant antenna offers wide impedance bandwidth ranges 2.3-17.8 GHz, having a notch band at 6.1-7.2 GHz. Afterwards, a two-port MIMO antenna is created by placing the second element orthogonally with an edge-to-edge distance of 8.5 mm, that is λ/15 where λ corresponds to free space wavelength at the lowest cut-off frequency. Hereafter, a meandered line-shaped stub is inserted to reduce the mutual coupling between closely spaced MIMO elements to less than -25 dB. As the intended application of the proposed work is On-body, Specific Absorption Rate (SAR) analyses are carried out at 2.4, 5.8 and 8 GHz, showing an acceptable range for both 1-g and 10-g averaged tissues standards. Moreover, various parameters of the MIMO antenna are studied, and a comparison is made between simulated and measured results as well as those of the state of the art.

8.
Heliyon ; 10(1): e23712, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38192868

RESUMO

A compact high bandwidth ratio (BDR) super wide band flower slotted micro strip patch antenna (SWB-FSMPA) for super wide band (SWB) applications is presented. The SWB-FSMPA is constructed on a FR-4 substrate having a size of 16 × 22 mm2. The SWB-FSMPA incorporates a 50 Ω tapered micro strip line and a rectangular beveled defected ground structure (RB-DGS). This design enables a simulation bandwidth from 3.78 to 109.86 GHz, allowing for coverage of various wireless applications such as WiMAX (3.3-3.6 GHz), 5G (3.3-3.7 GHz), WLAN (5.15-5.825 GHz), UWB (3.1-10.6 GHz), Ku- (12-18 GHz), K- (18-27 GHz), Ka- (27-40 GHz), V- (40-75 GHz), and W- (75-110 GHz) millimeter wave bands. The SWB-FSMPA antenna exhibits a gain that varies within the range of 3.22-7.23 dBi and a peak efficiency of 93.3 %. The SWB-FSMPA possesses a bandwidth ratio (BR) of 29.1:1, a BDR of 5284 in the frequency domain, a minimal group delay (GD) fluctuation of <0.48 ns, and a linear phase in the time domain, making it well-suited for SWB applications.

9.
Medicine (Baltimore) ; 102(42): e35638, 2023 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-37861504

RESUMO

Successful empirical antibiotic therapy for infected patients with multi drug resistant bacteria (MDR) can be challenging task in various healthcare settings, including neonatal and pediatric intensive care units (NICU and PICU, respectively), unless an up-to-date comprehensive local antibiogram data is available. Thus, this project aimed to investigate the prevalence of MDR among PICU and NICU patients as well as the identification of risk factors associated with recovered MDR bacteria. This was a retrospective study of PICU and NICU patients admitted with bacterial infection of MDR organisms between October 2020 and May 2021. Frequency distribution, Chi-square test were applied to verify the significance differences among subgroups and to identify risk factor associated with each group. About 36.4% of recruited patients were neonates, while the remaining percentage (63.6%) were pediatric. The most predominant site of infection among these patients were revealed as urinary tract (35%), followed by bloodstream (20.0%), wound/skin (12.9%) and respiratory system (11.4%). Methicillin-resistant Staphylococcus aureus (MRSA) was identified as the most common microbe across these sites of infections (30.7%), followed by Escherichia coli (25.0%), Klebsiella pneumoniae (22.9%) and Serratia (10.0%). High mortality rate was significantly associated with patients who were on mechanical ventilators (28.9%, OR 5.5; 95% CI), followed by patients had invasive operation (27.5%, OR, 8.04; 95% CI) and those who required a total parental nutrition (TPN) since almost one-half of these cases have (46.2%) died. In addition, mortality rate was relatively higher among patients infected with species of Serratia (28.6%) and Enterobacter (20.0%). These data highlighted that MRSA was the main MDR bacteria isolated from PICU and NICU followed by gram-negative bacteria, which were associated with high mortality rate. Therefore, infection control measures and continuous monitoring of emerging MDR bacteria should be applied to limit the bacterial infections in NICU and PICU patients.


Assuntos
Infecções Bacterianas , Staphylococcus aureus Resistente à Meticilina , Recém-Nascido , Criança , Humanos , Estudos Retrospectivos , Prevalência , Arábia Saudita/epidemiologia , Bactérias , Unidades de Terapia Intensiva Pediátrica , Infecções Bacterianas/tratamento farmacológico , Infecções Bacterianas/epidemiologia , Fatores de Risco , Antibacterianos/uso terapêutico , Unidades de Terapia Intensiva Neonatal
10.
Sensors (Basel) ; 23(20)2023 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-37896543

RESUMO

A pattern reconfigurable antenna, composed of eight elements, is proposed for energy harvesting applications. Pattern reconfigurable antennas are a promising technique for harvesting from different wireless sources. The radiation pattern of the proposed antenna can be steered electronically using an RF switch matrix, covering an angle range from 0 to 360 degrees with a step size of 45 degrees. The proposed antenna primarily consists of an eight-dipole configuration that shares the same excitation. Each dipole is excited using a balun comprising a quarter-wavelength grounded stub and a quarter-wavelength open-circuit stub. The proposed antenna operates in the frequency range of 4.17 to 4.5 GHz, with an impedance bandwidth of 7.6%. By switching between the different switches, the antenna can be steered with a narrower rotational angle. In addition, the antenna can work in an omnidirectional mode when all switches are in the ON state simultaneously. The results demonstrate a good agreement between the numerical and experimental findings for the reflection coefficient and radiation characteristics of the proposed reconfigurable antenna.

11.
Sensors (Basel) ; 23(20)2023 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-37896656

RESUMO

This article presents a quad-element MIMO antenna designed for multiband operation. The prototype of the design is fabricated and utilizes a vector network analyzer (VNA-AV3672D) to measure the S-parameters. The proposed antenna is capable of operating across three broad frequency bands: 3-15.5 GHz, encompassing the C band (4-8 GHz), X band (8-12.4 GHz), and a significant portion of the Ku band (12.4-15.5 GHz). Additionally, it covers two mm-wave bands, specifically 26.4-34.3 GHz and 36.1-48.9 GHz, which corresponds to 86% of the Ka-band (27-40 GHz). To enhance its performance, the design incorporates a partial ground plane and a top patch featuring a dual-sided reverse 3-stage stair and a straight stick symmetrically placed at the bottom. The introduction of a defected ground structure (DGS) on the ground plane serves to provide a wideband response. The DGS on the ground plane plays a crucial role in improving the electromagnetic interaction between the grounding surface and the top patch, contributing to the wideband characteristics of the antenna. The dimensions of the proposed MIMO antenna are 31.7 mm × 31.7 mm × 1.6 mm. Furthermore, the article delves into the assessment of various performance metrics related to antenna diversity, such as ECC, DG, TARC, MEG, CCL, and channel capacity, with corresponding values of 0.11, 8.87 dB, -6.6 dB, ±3 dB, 0.32 bits/sec/Hz, and 18.44 bits/sec/Hz, respectively. Additionally, the equivalent circuit analysis of the MIMO system is explored in the article. It's worth noting that the measured results exhibit a strong level of agreement with the simulated results, indicating the reliability of the proposed design. The MIMO antenna's ability to exhibit multiband response, good diversity performance, and consistent channel capacity across various frequency bands renders it highly suitable for integration into multi-band wireless devices. The developed MIMO system should be applicable on n77/n78/n79 5G NR (3.3-5 GHz); WLAN (4.9-5.725 GHz); Wi-Fi (5.15-5.85 GHz); LTE5537.5 (5.15-5.925 GHz); WiMAX (5.25-5.85 GHz); WLAN (5.725-5.875 GHz); long-distance radio telecommunication (4-8 GHz; C-band); satellite, radar, space communications and terrestrial broadband (8-12 GHz; X-band); and various satellite communications (27-40 GHz; Ka-band).

12.
PLoS Negl Trop Dis ; 17(6): e0011426, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37339146

RESUMO

BACKGROUND: Schistosomiasis is one of the most prevalent helminthic infections worldwide. Praziquantel (PZQ) resistance poses a possible danger to the disease's ability to be controlled. Little is known about the role of Ziziphus spina-christi leaf extract (ZLE) in the treatment of hepatic schistosomiasis. However, no study has explored ZLE's anti-angiogenic and anti-proliferative activity as a possible mechanism for reducing hepatic injury in this context. Therefore, this study aimed to evaluate the therapeutic potential of ZLE as an anti-angiogenic, and anti-proliferative agent in hamsters infected with S. mansoni. METHODS: Fifty hamsters were used and divided into 5 groups (10 hamsters each); noninfected untreated (controls), noninfected treated with ZLE, infected untreated, infected treated with PZQ- and infected treated with ZLE. Anti-angiogenic and anti-fibrotic effects of the drugs were assessed pathologically through the immunohistochemical expression of VEGF, Ki-67, and TGF ß1 in liver sections. Some oxidative stress parameters were measured in hepatic homogenates (NO, GSH, GST, and SOD), and serum liver enzymes were also assessed. RESULTS: A significant decrease in worm burden, granuloma size, granuloma area, and numbers in the ZLE- and PZQ-treated groups compared to the infected untreated group, and the decrease in granulomas number and tissue egg load was significantly lower in PZQ treated group compared to ZLE treated group (p<0.05). ZLE exhibited significant anti-angiogenic and anti-fibrotic effects on granulomas, illustrated by significantly lower expression of VEGF and TGF-ß1 than infected untreated and PZQ-treated groups. ZLE exhibits antiproliferative activity evidenced by a significant reduction of positive Ki-67 hepatocytes percentage compared to the infected untreated group. Moreover, ZLE exhibits potent antioxidant effects evidenced by a significantly lowered NO and conservation of hepatic GSH, GST, and SOD in hepatic homogenates compared to infected untreated and PZQ-treated groups (p<0.05). CONCLUSION: Our results point to ZLE as a promising hepatoprotective therapeutic tool in the treatment of schistosome hepatic fibrosis as it has anti-angiogenic, anti-proliferative, anti-fibrotic, and antioxidant effects in hamsters infected with S. mansoni, providing scientific support for its use in conventional medicine.


Assuntos
Anti-Helmínticos , Esquistossomose mansoni , Esquistossomose , Ziziphus , Animais , Cricetinae , Esquistossomose mansoni/tratamento farmacológico , Antioxidantes , Antígeno Ki-67 , Fator A de Crescimento do Endotélio Vascular/farmacologia , Fator A de Crescimento do Endotélio Vascular/uso terapêutico , Fígado , Esquistossomose/tratamento farmacológico , Praziquantel/uso terapêutico , Praziquantel/farmacologia , Extratos Vegetais/uso terapêutico , Extratos Vegetais/farmacologia , Granuloma , Superóxido Dismutase , Schistosoma mansoni , Anti-Helmínticos/uso terapêutico
13.
Cardiovasc Intervent Radiol ; 46(4): 512-518, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36826492

RESUMO

PURPOSE: To describe the feasibility and technique of percutaneous image-guided combined treatment of bone cyst (BC) using cryoablation and bone graft substitute injection. MATERIALS AND METHODS: Between July 2019 and January 2022, six consecutive patients (ages between 16 and 33 years) with symptomatic BC in pelvic and lower extremity bones underwent percutaneous image-guided combined treatment using cryoablation and bone graft substitute. To induce bone mineralization as early as possible, the cyst cavity was filled with bone graft substitute. Technical success of the procedure was evaluated, and clinical success was defined as satisfactory clinical symptom relief using visual analogue scale (VAS). Radiologic success was defined as early BC remineralization on radiographic studies. Detailed demographic data with lesion location, size, time to and degree of BC mineralization, complications, clinical outcomes, and radiological follow-up were retrospectively assessed. RESULTS: Technical success was 100% achieved in all patients. BC mineralization was observed in all patients, with a median time to reach 80% mineralization at 6 months, with one patient reaching 80% at 5 months and another reaching 100% at 3 months. A significant drop in VAS was observed in all patients, reflecting significant pain relief. There were no major complications. The median follow-up period was 31.5 months, with a minimum follow-up of 5 months and a maximum follow-up of 3 years. CONCLUSION: Percutaneous image-guided combined treatment with cryoablation and bone graft substitute for symptomatic BC is technically feasible and was safe in this limited series.


Assuntos
Cistos Ósseos , Criocirurgia , Humanos , Adolescente , Adulto Jovem , Adulto , Resultado do Tratamento , Estudos Retrospectivos , Criocirurgia/métodos , Estudos de Viabilidade
15.
Cureus ; 14(12): e32630, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36654626

RESUMO

Background Bariatric surgery is one of the most effective interventions for morbid obesity. Despite its benefits, unwanted consequences such as dumping syndrome (DS) have been reported following the procedure. This study aims to estimate the prevalence of DS and identify the factors associated with it in Saudi Arabia. Methodology This cross-sectional study collected data from patients who underwent bariatric surgery at King Fahad General Hospital, Jeddah, Saudi Arabia, in 2019-2020. A validated questionnaire was used to collect the data. The questionnaire included demographic items such as age and sex and items relating to DS such as nausea, vomiting, and palpitations. A modified version of the Sigstad diagnostic scoring system was used to confirm the diagnosis. Results Of the 240 investigated cases, two-thirds (67.5%) were females. The most reported symptoms were nausea (37.9%), vomiting (36.7%), desire to lie down (25.5%), restlessness (25.5%), and abdominal fullness (23.7%). Based on the modified Sigstad diagnostic scoring system, 75 (31.4%) patients met the criteria for DS. The bivariate analysis showed the prevalence was significantly higher in females (36.4%), those with university qualifications (40.3%), and those with high monthly income (62.5%) (p<0.05). Also, dietary behaviors in terms of frequency, size of meals, and drinking liquids with meals were significantly associated with the prevalence of DS, where the lowest prevalence was recorded among those who ate more than one small meal (10.9%), while the highest prevalence was found in those who ate more than one large meal (81.8%); also, the prevalence was significantly higher in patients who drank liquids with meals (40.8%) than those who drank liquids between meals (26.8%) (p<0.05). Conclusion In this single institutional study, we report a 31.4% prevalence of DS among our cohort. The predictors of the syndrome include gender, education level, monthly income, eating more than one large meal per day, and drinking liquids with meals. In the future, these predictors will be explained to patients before and after bariatric surgery to reduce the prevalence of such inconvenient syndromes.

16.
J Food Drug Anal ; 29(1): 39-45, 2021 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35696227

RESUMO

Ranitidine is a medication that has been used to alleviate heartburn and other disorders for over 40 years. Following reports of N-nitrosodimethylamine (NDMA) contamination in ranitidine products, there have been many recalls and registration suspensions. Here, we revise the literature information confirming ranitidine association with NDMA. Then, we highlight the documented mechanisms for NDMA release from ranitidine. In addition, the stability issue for this medicine is discussed. After that, we review and discuss the results of the United States Food and Drug Administration and the Australian Therapeutic Goods Administration laboratory testing of ranitidine products and the detected NDMA levels. Finally, the case of NDMA generation in Angiotensin II Receptor Blockers (ARBs) and ranitidine were compared in an attempt to address the circumstances leading to the current contamination.


Assuntos
Dimetilnitrosamina , Ranitidina , Antagonistas de Receptores de Angiotensina , Inibidores da Enzima Conversora de Angiotensina , Austrália , Preparações Farmacêuticas , Estados Unidos
17.
Cureus ; 13(11): e19965, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34984125

RESUMO

Seizure is a common neurological problem in the emergency department. First-time seizure needs careful evaluation to exclude the underlying structural brain lesions. Neuroimaging studies, including magnetic resonance imaging and computed tomography scan, are strongly recommended for all adult patients with first-time seizures. We report the case of a 35-year-old woman who was brought to the emergency department because of the first-time loss of consciousness episode. She developed bilateral jerky movements in both her upper and lower limbs. It was associated with frothy secretions from the mouth and cyanosis. The episode lasted for two minutes and terminated spontaneously. The patient was tired after gaining consciousness. The past medical history of the patient was remarkable for anxiety, depression, and polycystic ovarian syndrome. She has undergone multiple cognitive behavioral therapy sessions, but she did not take any psychiatric medications. Neurological examination did not reveal any focal neurological deficit. The patient underwent a computed tomography scan to exclude any space-occupying lesion. The unenhanced scan demonstrated bilateral symmetrical calcification of the basal ganglia. No calcification was noted in the cerebellum or the cerebral cortex. Otherwise, no intracranial pathology was seen. Such findings conferred the diagnosis of Fahr disease. The patient was discharged on carbamazepine to prevent further seizure episodes. After six months of follow-up, the patient did not experience further convulsion episodes. Fahr disease is a rare disorder with a wide spectrum of manifestations. Despite its rarity, physicians should keep this condition as a possible differential diagnosis when they encounter an adult patient with a first-time seizure, particularly in a patient with a history of neuropsychiatric disorders.

18.
J Pharm Biomed Anal ; 191: 113582, 2020 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-32889348

RESUMO

N-nitrosodimethylamine (NDMA) is a carcinogenic contaminant that was accidentally discovered in drugs, such as valsartan and ranitidine, and more recently in metformin. Liquid chromatography tandem mass spectrometry (LC-MS/MS) is the method typically used for the analysis of NDMA in ranitidine. It seems that using gas chromatography (GC) for NDMA analysis is problematic as ranitidine is sensitive to high temperatures. In the present study, we assessed the usefulness of solid-phase microextraction (SPME) as a method of extraction and introduction into the GC. When using headspace (HS) and liquid injection modes in GC for NDMA analysis in ranitidine, higher NDMA levels were detected compared to using LC-MS/MS. Interestingly, using HS-SPME-GC-MS was advantageous because we could avoid the high temperature utilized in the liquid injection and HS modes. Moreover, the results obtained using HS-SPME-GC-MS provided a good match with those achieved using LC-MS/MS. The feasibility of using HS-SPME-GC-MS to successfully analyze NDMA in ranitidine opens new opportunities for the analysis of this contaminant in pharmaceuticals, specifically those that are heat-labile.


Assuntos
Dimetilnitrosamina , Microextração em Fase Sólida , Cromatografia Líquida , Cromatografia Gasosa-Espectrometria de Massas , Ranitidina , Espectrometria de Massas em Tandem
19.
Clin Exp Hepatol ; 6(2): 137-141, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32728631

RESUMO

AIM OF THE STUDY: Interleukin-6 (IL-6) can play a role in hepatic regeneration through many mechanisms, one of which is the induction of synthesis of matrix metalloproteinases (MMPs). The aim of the study is to focus on the significance and role of MMPs in the regenerative process to reveal the correlation between IL-6 and MMPs in rats following partial hepatectomy. MATERIAL AND METHODS: Following hemi-hepatectomy, eighty male rats were divided into a control group and a group treated with IL-6 35 µg/100 gm body weight according to a lethality study. The blood samples were drawn from all animal groups for MMP-9 serum level assessment. For the quantitative determination of MMP-9 an enzyme-linked immunosorbent assay (ELISA) was used (Cytoimmune Science Inc., MD) through the quantitative sandwich immunosorbent assay technique. A monoclonal antibody for MMP-9 was pre-coated onto microplate standards. After washing away the unbound substances, an enzyme-linked polyclonal antibody specific for cytokine was added to the wells and color developed in proportion to the amount of total cytokine (pro and/or active) bound in the initial step. The color development was stopped and the intensity of the color was measured. RESULTS: The liver regeneration rate (%) was significantly higher in the group of rats treated with IL-6 (median value was 49.55% vs. 33.20%), p < 0.001. The MMPs' serum level was significantly higher in the group of rats with resection and treatment (median value was 8.01). CONCLUSIONS: These results give evidence for the vital role of MMPs in the process of hepatic regeneration, the level of which, in turn, has a close relationship with the level of IL-6. MMPs have diverse effects in promoting angiogenesis, remodeling of extracellular matrix and endothelial cell proliferation.

20.
Int J Surg Case Rep ; 66: 165-168, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31862659

RESUMO

BACKGROUND: Angiodysplasia is the second most common vascular abnormality of the GI tract after diverticulosis and is the second principal cause of lower GI bleeding over 60 years. CASE REPORT: A 68-year-old male patient presented to our institute in the outpatient clinic with pallor of gradual onset and progressive course since 6 months. Detailed history revealed hematochezia, sometimes melena. Physical examination revealed signs of iron deficiency anemia which was confirmed by laboratory results and hemoccult positive stool. The patient refused the colonoscopy. A bdominal CT with contrast was then performed which revealed an evidence of abnormal subtle mural contrast flocculation within the small bowel loop with luminal extravasations of contrast at small segment of distal ileum few centimeters from ileocaecal valve with mildly dilated and early filling of its drained vein, this abnormal contrast extravasations and flocculation increased through dynamic study. In addition, evidence of contrast mural flocculation within the left lateral wall of distal few centimeters of rectum was also observed. This abnormal mural contrast flocculation within the wall of solitary segment terminal ileum and distal rectum suggest the evidence of venous ectasia or angiodysplasia. Surgical resection was done with end to end anastomosis of the small intestine without any complication in the postoperative progress. CONCLUSION: This case also emphasizes the critical significance of a mutual multidisciplinary approach to occult gastrointestinal bleeding. The management of angiodysplasia is considered as multidisciplinary team work that would consist of expertise from different departments as in endoscopy, angiography, and gastrointestinal surgery.

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