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Shark is a seafood commodity that is a good source of minerals and accumulates heavy metals and trace elements through biomagnification, which can pose health risk if taken above the permissible limit. A study was conducted on commonly landed eleven shark species (Scoliodon laticaudus, Rhizopriodon oligolinx, Sphyrna lewini (CR), Carcharhinus macloti, Carcharinus limbatus, Carcharhinus amblyrhynchoides, Carcharhinus sorrah, Carcharinus falciformes(VU), Glaucostegus granulatus, Chiloscyllium arabicum, Loxodon macrorhinus) and analyzed for their heavy metal content, Hazard Index, Total Hazard Quotient, Metal Pollution Index, and also calculated the health risk associated with the consumption. Most of the heavy metals and trace minerals were found to be within the acceptable limit. The Targeted Hazard Quotient (THQ) and the Hazard Index (HI) of all the species except two were less than 1 (HI ≤ 1.0). The Metal Pollution Index (MPI) is showing either no impact or very low contamination. An overall study on hazard identification and health risk characterization in terms of heavy metals shows contamination of some heavy metals in sharks, but there is no potential human health risk associated with consumption.
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Metais Pesados , Tubarões , Poluentes Químicos da Água , Animais , Metais Pesados/análise , Tubarões/metabolismo , Poluentes Químicos da Água/análise , Medição de Risco , Humanos , Oligoelementos/análise , Monitoramento Ambiental , Minerais/análiseRESUMO
Continuing on our antiviral drug discovery research, we intended to diversify our lead anti-HIV-1 inhibitor by non-classical isosteric replacement of amide to 1,2,4-oxadiazoles. The resulting molecules isoxazole-1,2,4-oxadiazole analogs were synthesized using mild bases in ethanol under microwave irradiation. The anti-HIV potential was checked in human CD4+ reporter cell lines, TZM-bl and CEM-GFP, at the highest non-cytotoxic concentration (HNC), demonstrating that 3-((3-(p-tolyl)isoxazol-5-yl)methyl)-1,2,4-oxadiazole and 3-((3-(4-chlorophenyl)isoxazol-5-yl)methyl)-1,2,4-oxadiazole inhibit HIV-1 replication significantly and could be considered as a new lead candidate against HIV-1.
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Fármacos Anti-HIV/farmacologia , HIV-1/efeitos dos fármacos , Isoxazóis/farmacologia , Oxidiazóis/farmacologia , Fármacos Anti-HIV/síntese química , Fármacos Anti-HIV/química , Linhagem Celular , Relação Dose-Resposta a Droga , Humanos , Isoxazóis/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Oxidiazóis/síntese química , Oxidiazóis/química , Relação Estrutura-Atividade , Replicação Viral/efeitos dos fármacosRESUMO
Diabetes is a ubiquitously a metabolic disorder and life-threatening disease. Peroxisome proliferator-activated receptors (PPARs) belong to the class of nuclear receptors which acts as transcription factors to regulate lipid and glucose metabolism. PPAR alpha/gamma dual agonists tend to corroborate the functions of both thiazolidinediones and fibrates and they hold substantial promise for ameliorating the type 2 diabetic treatments and providing potential therapeutic diabetic interventions. New 1,2,4-oxadiazole based trans- acrylic acid derivatives compounds possessing aryl/methylene linker in between pharmacophore head and lipophilic tail for dual PPAR-alpha/gamma agonists are studied. AutoDock Vina used for potential PPAR alpha/gamma dual agonists and 6 compounds 9a, 9g, 9 m, 9n, 9o, and 9r were identified comparable to PPAR gamma agonist Pioglitazone on the basis of their affinity scores and further their in-silico toxicity and in-silico ADME properties. The selected compounds showed better-calculated lipophilicity (iLogP) was found to be 0.92 to 3.19. Compound 9n and 9a were found to be most potent on both PPAR alpha and gamma receptors with EC50 of 0.07 ± 0.0006 µM, 0.06 ± 0.0005 µM and 0.781 ± 0.008 µM, 3.29 µM ± 0.03 respectively as better to pioglitazone having EC50 of 32.38 ± 0.2 and 38.03 ± 0.13 for both receptors. The in-vivo evaluation found to reduce the plasma glucose level and total cholesterol level significantly in diabetic rats compared to pioglitazone at 5 mg/kg/day dose for 7 days of treatment. Thus, trans- acrylic acid derivatives can be further developed as oral therapeutic agents for diabetic interventions as PPAR alpha/gamma dual agonists.
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Diabetes Mellitus Tipo 2/tratamento farmacológico , Oxidiazóis/química , Oxidiazóis/farmacologia , PPAR alfa/agonistas , PPAR gama/agonistas , Animais , Glicemia/análise , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/metabolismo , Desenho de Fármacos , Feminino , Humanos , Hipoglicemiantes/química , Hipoglicemiantes/farmacologia , Hipoglicemiantes/uso terapêutico , Simulação de Acoplamento Molecular , Oxidiazóis/uso terapêutico , PPAR alfa/metabolismo , PPAR gama/metabolismo , Ratos Sprague-DawleyRESUMO
Development of self-nanoemulsifying drug delivery systems (SNEDDS) of docosahexaenoic acid (DHA) is reported with the aim to achieve enhanced dissolution rate. The optimized composition of liquid SNEDDS (L-SNEDDS) formulation was Labrafil M1944 CS, 47% v/v Tween 80, 27% v/v Transcutol P, and 0.1% v/v DHA. L-SNEDDS were solidified using Syloid XDP 3150 as solid porous carrier. The droplet size, polydispersity index, zeta potential, percentage drug loading, and cloud point for L-SNEDDS were found to be 43.51 ± 1.36 nm, 0.186 ± 0.053, -19.20 ± 1.21 mV, 93.23 ± 1.71, and 88.60 ± 2.54 °C, respectively. Similarly, for solid SNEDDS (S-SNEDDS) the above parameters were found to be 57.32 ± 1.87 nm, 0.261 ± 0.043, -16.60 ± 2.18 mV, 91.23 ± 1.88, and 89.50 ± 1.18 °C, respectively. The formulations (L-SNEDDS, S-SNEDDS powder, and S-SNEDDS tablet) showed significant (p<.05) improvement in dissolution rate of drug in 0.1 N HCl (pH 1.2) and phosphate buffer (pH 6.8) as compared to unprocessed DHA. In both the dissolution media, the dissolution rate was found more that 85% in 90 min. Absence of drug precipitation, phase separation, and turbidity during thermodynamic stability studies indicated that the developed SNEDDS were stable. Hence, it was concluded that SNEDDS have offered sufficient stability as well as dissolution rate of DHA.
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Ácidos Docosa-Hexaenoicos/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Nanopartículas/química , Administração Oral , Disponibilidade Biológica , Ácidos Docosa-Hexaenoicos/farmacocinética , Liberação Controlada de Fármacos , Estabilidade de Medicamentos , Emulsões/química , Tamanho da Partícula , Dióxido de Silício/química , Solubilidade , Tensoativos , ComprimidosRESUMO
The development of organic photoluminescent materials, which show promising roles as catalysts, sensors, organic light-emitting diodes, logic gates, etc., is a major demand and challenge for the global scientific community. In this context, a photoclick polymerization method is adopted for the growth of a unique photoluminescent three-dimensional (3D) polymer film, E, as a model system that shows emission tunability over the range 350-650â nm against the excitation range 295-425â nm. The DFT analysis of energy calculations and π-stacking supports the spectroscopic observations for the material exhibiting a broad range of emission owing to newly formed chromophoric units within the film. Full polarization spectroscopic Mueller matrix studies were employed to extract and quantify the molecular orientational order of both the ground (excitation) and excited (emission) state anisotropies through a set of newly defined parameters, namely the fluorescence diattenuation and fluorescence polarizance. The information contained in the recorded fluorescence Mueller matrix of the organic polymer material provided a useful way to control the spectral intensity of emission by using pre- and post-selection of polarization states. The observation was based on the assumption that the longer lifetime of the excited dipolar orientation is attributed to the compactness of the film.
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This work describes a flexible and stretchable battery pack configuration that exhibits highly stable performance under large deformation up to 100% biaxial stretching. Using stress-enduring printable inks and serpentine interconnects, the new screen-printing route offers an attractive solution for converting rigid battery units into a flexible, stretchable energy storage device. Coin-cell lithium ion batteries are thus assembled onto the island regions of a screen-printed, buckling-enabled, polymer-reinforced interconnect "island-bridge" array. Most of the strain on the new energy-storage device is thus accommodated by the stress-enduring serpentine structures, and the array is further reinforced by mechanically strong "backbone" layers. Battery pack arrays are assembled and tested under different deformation levels, demonstrating a highly stable performance (<2.5% change) under all test conditions. A light emitting diode band powered by the battery pack is tested on-body, showing uninterrupted illumination regardless of any degrees of deformation. Moreover, battery-powered devices that are ultrastable under large deformation can be easily fabricated by incorporating different electronics parts such as sensors or integrated circuits on the same platform. Such ability to apply traditionally rigid, bulky lithium ion batteries onto flexible and stretchable printed surfaces holds considerable promise for diverse wearable applications.
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Zn aqueous batteries typically suffer from poor cycle life because water soluble zincate ions are formed during the oxidation of Zn. When Zn is oxidized, most of the Zn2+ ions detach from the current collector and become electrochemically inactive, leaving the battery non-rechargeable. Numerous reports demonstrate the use of Bi2O3 as an electrode additive to enhance electrochemical performance and they attribute this phenomenon to the improvement in electrical conductivity. However, conductivity does not have an effect on the intrinsic solubility of the zincate ion. We conduct a series of characterizations to provide a comprehensive mechanistic role of Bi2O3 in the Zn electrode. We find that upon oxidation, zincate ions are formed but they relax into ZnO on the surface of the bismuth species. This work proposes that the reason for the prolonged cycle life is due to the deposition of ZnO through relaxation and this prevents losing electrochemically active materials. This finding paves the way for further improving the cycle life and understanding the mechanism of the Zn based rechargeable aqueous batteries and possibly other conversion types of rechargeable batteries.
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In this communication, a mild, efficient, and generalized polycondensation route is developed for poly(disulfide)s from commercially available monomers 2,2'-dithiodipyridine and 1,6-hexanedithiol. Using the stoichiometric imbalance between the two monomers, it is possible to produce telechelic poly(disulfide)s of predictable molecular weight with reactive pyridyl disulfide groups at both the terminals of the chain. The two terminal pyridyl disulfide groups can be quantitatively replaced by a functional thiol using selective thiol-disulfide exchange and thus produces functional telechelic poly(disulfide)s, which can be used as a macroinitiator to initiate ring-opening poly-merization of a cyclic lactide monomer generating an ABA-type triblock copolymer with degradable B block.
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Polímeros/química , 2,2'-Dipiridil/análogos & derivados , 2,2'-Dipiridil/química , Dioxanos/química , Dissulfetos/química , Peso Molecular , Polimerização , Polímeros/síntese química , Compostos de Sulfidrila/químicaRESUMO
Back Cover: An efficient polycondensation route for telechelic poly(disulfide)s is developed from two monomers-2,2'-dithiodipyridine and 1,6-hexanedithiol-using stoichiometric imbalance between them. Selective thiol-disulfide exchange of the two terminal pyridyl disulfide groups with functional thiol produces functionalized poly(disulfide)s that can be used as a macro-initiator to initiate ROP of lactide generating a triblock copolymer with degradable middle block. Further details can be found in the article by D. Basak, R. Kumar, and S. Ghosh* on page 1340.
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Polímeros/químicaRESUMO
Background: Healthcare professionals (HCPs) worldwide suffer from stress and poor sleep and the COVID-19 pandemic has further raised these issues. This study sought to determine whether HCPs had reduced stress and increased sleep quality while participating in a heartfulness meditation program. Subjects and Methods: For a 2-month (8 weeks) heartfulness meditation program, we included 41 individuals in a prospective one-group pretest post-test intervention design from February 2023 to April 2023. Scores on the Perceived Stress Scale and Pittsburgh Sleep Quality Index were gathered at baseline and 8 weeks. Forty-one (76%) of the 54 participants completed this study for 8 weeks. Results: Results showed a substantial decline in stress (preintervention mean ± standard deviation [SD] = 20.54 ± 4.46; postintervention mean ± SD = 18.42 ± 6.14; t-value = -1.947 [0.05*]) and improvement in sleep quality (preintervention mean ± SD = 6.63 ± 3.82; postintervention mean ± SD = 5.29 ± 2.44) among HCPs after following this 8-week heartfulness meditation program. In the end, a substantial decrease in perceived stress score and an improvement in the sleep quality index was found. Conclusion: Additionally, practicing heartfulness meditation may aid in developing the traits of empathy, acceptance, and inner serenity. We draw the conclusion that more extensive research is required to fully understand the impact of heartfulness meditation practice.
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Fisetin (FS) is a flavonoid that possesses antioxidant and anti-inflammatory properties against ulcerative colitis. FS shows poor dissolution rate and permeability. An attempt has been made to develop colon-targeted solid self-nanoemulsifying drug delivery systems (S-SNEDDS) of FS. Initially, liquid (L) SNEDDS were prepared by loading FS into isotropic mixture of L-SNEDDS was prepared using Labrafil M 1944 CS, Transcutol P, and Tween 80. These L-SNEDDS were further converted into solid (S) SNEDDS by mixing the isotropic mixture with 1:1:1 ratio of guar gum (GG), xanthan gum (XG) and pectin (PC) [GG:XG:PC (1:1:1)]. Aerosil-200 (A-200) was added to enhance their flow characteristics. Further, they were converted into spheroids by extrusion-spheronization technique. The solid-state characterization of S-SNEDDS was done by SEM, DSC, and PXRD, which revealed that the crystalline form of FS was converted into the amorphous form. In the dissolution study, S-SNEDDS spheroids [GG:XG:PC (1:1:1)] exhibited less than 20% drug release within the first 5 h, followed by rapid release of the drug between the 5th and 10th h, indicating its release at colonic site. The site-specific delivery of FS to colon via FS-S-SNEDDS spheroids was confirmed by conducting pharmacokinetic studies on rats. Wherein, results showed delay in absorption of FS loaded in spheroids up to 5 h and achievement of Cmax at 7h, whereas L-SNEDDS showed rapid absorption of FS. Furthermore, FS-L-SNEDDS and FS-S-SNEDDS spheroids [GG:XG:PC (1:1:1)] increased oral bioavailability of FS by 6.86-fold and 4.44-fold, respectively, as compared to unprocessed FS.
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This study provides the first documentation of three deep conspecific lineages within Panulirus polyphagus in the Indian Ocean, bridging the gap in genetic research. Comparative mitogenomics between lineages (L) at both species and family levels, evolutionary relationships and heterogeneity of sequence divergence within Decapoda, and divergence time estimation were performed. The characterized mitogenomes ranged from 15,685-15,705 bp in size and exhibited a typical pancrustacean pattern. Among the three lineages, L1 predominated the Bay of Bengal, L2 the Arabian Sea, and L2.a, a less common lineage genetically closer to L2, was restricted to the latter region. A minor lineage L1.a, was observed in the Coral Triangle area. All PCGs displayed evidence of purifying selection across species and family levels. The largest genetic distance (K2P) between lineages was 9 %, notably between L1.a and L2.a. The phylogenetic tree subdivided the Achelates into Palinuridae and Scyllaridae, and the topology demonstrated a distinct pattern of lineage diversification within P. polyphagus. AliGROOVE analysis revealed no discernible divergence in Decapoda. The diversification of P. polyphagus appears to have occurred during Miocene, with further diversification in Pliocene. Furthermore, genetic stocks and population connectivity recognized here will provide valuable insight for spatial management planning of this dwindling resource.
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INTRODUCTION: The study was performed to compare dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) with 3-dimensional (3D) pseudocontinuous arterial spin labeling (PCASL) MRI in gliomas with an aim to see whether arterial spin labeling (ASL)-derived cerebral blood flow (CBF) values can be used as an alternative to DCE-MRI for its grading. MATERIALS AND METHODS: Sixty-four patients with glioma (37 male; mean age, 43 years; 38 high grade and 26 low grade) underwent 3D-PCASL and DCE-MRI. The DCE indices (relative cerebral blood volume, rCBV; relative CBF, rCBF; permeability, k and kep; and leakage, ve) and ASL (absolute and rCBF) values were quantified from the tumors. Student independent t test was used to compare ASL and DCE-MRI indices. Pearson correlation was used to see correlation between DCE- and ASL-derived CBF values in tumor and normal parenchyma. RESULTS: On Student t test, neither ASL-derived absolute CBF (P = 0.78) nor rCBF (P = 0.12) values were found to be significantly different in 2 groups, whereas DCE indices except ve were significantly higher in high-grade gliomas. Arterial spin labeling-derived rCBF values weakly correlated with DCE-derived rCBF values, whereas these did not show correlation in normal grey (P = 0.12, r = 0.2) and white (P = 0.26, r = 0.14) matter regions. CONCLUSIONS: Three-dimensional pseudocontinuous arterial spin labeling does not appear to be a reliable technique in the current form and may not be a suitable replacement for DCE in grading of glioma.
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Neoplasias Encefálicas/patologia , Glioma/patologia , Imageamento Tridimensional , Imageamento por Ressonância Magnética/métodos , Marcadores de Spin , Adulto , Circulação Cerebrovascular , Meios de Contraste , Feminino , Humanos , Masculino , Gradação de TumoresRESUMO
INTRODUCTION: Tuberculosis (TB) of the cranio-vertebral junction (CVJ) is a rare condition, accounting for 0.3 % to 1 % of all cases of spinal TB. Early diagnosis and treatment are important in preventing long-term neurological sequelae. Management protocol of this rare site of TB is yet to be conclusively established. This holds particularly true for pediatric age group in which this condition is infrequently encountered. MATERIALS AND METHODS: A total of 29 consecutive pediatric patients presented to the Department of Neurosurgery at Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Lucknow, from January 1997 to October2011 with clinical and/or radiological features suggestive of CVJ TB. A clinical grading system to evaluate the neurological status was developed, and all patients were evaluated using this scoring system. Patients were radiologically evaluated with computed tomography (CT) of CVJ and magnetic resonance imaging (MRI) with gadolinium enhancement. These cases were managed according to their grade and followed up. RESULTS: Out of a total of 29 cases, 18 were females and 11 males. Age range was 4 to 18 years with mean age 9 ± 3.8 years. The follow-up period ranged from 2 months to 7.5 years with mean follow-up of 2.7 years. Eleven cases were of grades 1 and 2, and 18 cases were of higher grade (grades 3 and 4). Predominantly conservative approach was utilized in cases with better clinical status, and grade (grades 1 and 2) and surgical intervention was needed in the more severe grades. All cases had significant improvement at the last follow-up. CONCLUSION: One needs to have a high index of suspicion of CVJ TB if one encounters a case with neck pain, neck restriction, and raised erythrocyte sedimentation rate. CT CVJ and MRI with gadolinium contrast enhancement are the investigations of choice for both establishing a diagnosis and planning the management. For cases with mild neurological deficit, conservative approach would work for majority of cases, and for severe cases, initial conservative approach may be tried, failing which surgical intervention would be needed.
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Articulação Atlantoaxial/patologia , Vértebras Cervicais/patologia , Tuberculose da Coluna Vertebral/diagnóstico , Adolescente , Articulação Atlantoaxial/cirurgia , Vértebras Cervicais/cirurgia , Criança , Pré-Escolar , Gerenciamento Clínico , Feminino , Seguimentos , Gadolínio , Humanos , Aumento da Imagem , Imageamento por Ressonância Magnética , Masculino , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios X , Resultado do Tratamento , Tuberculose da Coluna Vertebral/cirurgia , Tuberculose da Coluna Vertebral/terapiaRESUMO
India is native to many tribal communities: Bharia (Madhya Pradesh), Bihl (Rajasthan), Santhal (Bihar, Jharkhand), Bodo (Assam, West Bengal), and many more. They reside in isolated geographical regions, which poses challenges in reaching out to them. In addition, they still have firm beliefs and taboos regarding menstruation. Knowledge about menstrual health and hygiene is one of the most important aspects of tribal health. Therefore, it is important to synthesize the results of menstrual hygiene data from the Indian tribal population. We have calculated the pooled prevalence of sanitary pad use, dustbin disposal, and hygienic reuse of menstrual materials. Online databases, namely PubMed, Cochrane Central, CINAHL, Pan African Journals, EBSCO, and Google Scholar, were searched. After the removal of duplicates, a quality check, and screening of cross-references, 19 articles were selected for final review. Statistical analysis was done by Revman 5.4 and STATA 17.0. A p-value of <0.05 was considered statistically significant. PRISMA guidelines were followed. The protocol registration number was CRD42022331376. This is a non-funded article. The pooled prevalence of sanitary pad use in Indian tribal females was 2% (95% CI 1 to 3). The pooled prevalence of dustbin disposal of menstrual material was 1% (95% CI: 0.00 to 0.02). The pooled prevalence of hygienic reuse of menstrual materials was 1%. Sanitary menstrual hygiene practices are very less prevalent in Indian tribal females. Awareness programs and tribal health policies need to be accelerated for the promotion of menstrual hygiene. Also, literature on the use, disposal, and storage of menstrual adsorbents is scarce in Indian tribes. Health research in this area needs to be emphasized.
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BACKGROUND: Limited literature was available on the pattern and determinants of mortality among inborn neonates in comparison to the out born ones. The study's goal was to investigate the patterns and risk factors for mortality among hospitalised, on-ventilator inborn and out born neonates. MATERIALS AND METHODS: It was an unmatched, case-control, pilot study conducted between January and December 2020 using information retrieved from the medical records of patients attending the neonatal intensive care unit (NICU) of a tertiary healthcare facility, namely Narayan Medical College & Hospital, situated in eastern India. RESULTS: Congenital pneumonia was the leading cause of death in inborn neonates, with an overall mortality rate of 33.4%. Meanwhile, the overall fatality rate for out born neonates was found to be 43.3%, with birth hypoxia being the most common cause. The only significant attribute affecting mortality in inborn neonates was low arterial blood gas (ABG) pH, whereas in out born neonates they were prematurity, thrombocytopenia, low ABG pO2, and high pCO2. Overall, new-borns with thrombocytopenia, low ABG pO2, and high pCO2 were observed to be at higher risk for mortality compared to others. CONCLUSION: The mortality rate of out born neonates was higher than inborn ones. The attributes affecting mortality were observed to be prematurity, thrombocytopenia, low ABG pH, pO2, and high pCO2.
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Cerebral palsy (CP) is a neurological disorder that affects muscle tone, movement, and motor skills in children. One of the most common symptoms of cerebral palsy is spasticity, which is characterised by involuntary muscle contractions and stiffness. Both botulinum toxin and casting have been used as standalone treatments for spasticity in cerebral palsy, but which is better is still unclear. The aim of the present meta-analysis was to compare the effects on spasticity of serial casting and/or botulinum toxin type A (BoNT-A) in conjunction with or as independent therapies. Studies up to February 2022 were identified in four separate databases. The inclusion criteria were randomised controlled trials (RCTs) that compared different therapies (Botulinum toxin A, or BoNT-A, and casting) and assessed spasticity improvement in children with spastic cerebral palsy who were younger than 18 years old and were published in English. With a 95% confidence interval (CI), the standardised mean difference (SMD) was utilised to calculate treatment effects. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist was followed to undertake the current study. The search for relevant literature in four databases generated 147 results. After the abstract and full-text screening, five publications with a total of 190 cerebral palsy patients were included in this systematic review and meta-analysis. In patients with cerebral palsy, both methods - botulinum toxin and casting- apply globally; our systematic review tries to find out the most effective treatment between the two but does not show any significant difference in these methods. As we know, botulinum toxin is expensive, and the casting method is time-consuming and poorly accepted by patients. There is a need for an excellent study to examine the impact of casting and botulinum toxin type A.
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Acute hemorrhagic edema of infancy (AHEI) is a benign and rare presentation of leukocytoclastic vasculitis that usually affects children between 4 months and 24 months of age. It is characterized by purpuric and ecchymotic lesions that mainly involve the distal extremities, the face, and the ears. It usually follows some viral or bacterial infection. Here, we report a case of a 25-month-old male child who presented with mild grade fever and upper respiratory tract infection symptoms. Subsequently, he developed progressive purpuric and ecchymotic lesions over his body, mainly on his lower limbs and face. Laboratory tests were done, showing elevated C-reactive protein and erythrocyte sedimentation rate with rest of normal results. In view of patients having respiratory symptoms, reverse-transcriptase polymerase chain reaction of a nasopharyngeal swab for coronavirus disease 2019 (COVID-19) was done, which came out to be positive. The baby received supportive care only. He gradually improved and was discharged successfully. AHEI may be a possible after effect of COVID-19 infection.
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Microwave absorbing materials for high-temperature harsh environments are highly desirable for aerodynamically heated parts and engine combustion induced hot spots of aircrafts. This study reports ceramic composites with excellent and stable high-temperature microwave absorption in air, which are made of polymer-derived SiOC reinforced with core-shell nanophase structure of ZrB2/ZrO2. The fabricated ceramic composites have a crystallized t-ZrO2 interface between ZrB2 and SiOC domains. The ceramic composites exhibit stable dielectric properties, which are relatively insensitive to temperature change from room temperature to 900 °C. The return loss exceeds - 10 dB, especially between 28 and 40 GHz, at the elevated temperatures. The stable high-temperature electromagnetic (EM) absorption properties are attributed to the stable dielectric and electrical properties induced by the core-shell nanophase structure of ZrB2/ZrO2. Crystallized t-ZrO2 serve as nanoscale dielectric interfaces between ZrB2 and SiOC, which are favorable for EM wave introduction for enhancing polarization loss and absorption. Existence of t-ZrO2 interface also changes the temperature-dependent DC conductivity of ZrB2/SiOC ceramic composites when compared to that of ZrB2 and SiOC alone. Experimental results from thermomechanical, jet flow, thermal shock, and water vapor tests demonstrate that the developed ceramic composites have high stability in harsh environments, and can be used as high-temperature wide-band microwave absorbing structural materials.