Merits and Demerits of Sickle Cell Trait Donor Blood in Tropical Transfusion Medicine: Are There Any Indications for Specific Use of Blood Donated by Carriers of Sickle Cell Trait?

Haemoglobin-S mutation confers anti-malarial resistance and survival advantage in the tropics. Consequently, a significant and indispensable proportion of tropical blood donors carry sickle cell trait (SCT), which is associated with both merits (advantages) and demerits (disadvantages) in the practice of tropical transfusion medicine. Majority of the literature regarding SCT in blood transfusion highlighted its demerits with little or no reference to its merits, which constitute potentially beneficial qualities and useful applications of SCT blood in tropical transfusion medicine. Hence, the aim of this review is to present an updated, balanced, and comprehensive but concise and critical overview of the literature (using search-terms relevant to SCT in transfusion medicine) for both merits and demerits of SCT donor blood vis-à-vis its potential applications and implications in technical and clinical practice of transfusion medicine in the tropics. The review is presented in a sequential ‘stage-by-stage’ order from pre-donation procedures to blood donation, processing, storage and transfusion. The review explored the potential adverse effects of pre-donation medications on SCT donor, highlighted SCT-associated technical challenges in blood collection, processing and storage, and elucidated the clinical demerits and implications of SCT blood in sickle cell disease, perinatal, and neonatal transfusions. Moreover, the review expounded the merits of SCT blood vis-à-vis the probability of its low risks for transfusion transmitted malaria and HIV infections, and its potential applications in the evolving concept of ‘therapeutically rational transfusion of SCT red cells’ in managing severe and/or drug resistant malaria, and possibly haemophilia. In conclusion, the review underscored the need for tropical transfusionists and clinicians to innovate ways of ameliorating or circumventing the demerits and implications of SCT blood, and at the same time explore the feasibility and safety of its potential merits and applications vis-à-vis the practice of blood transfusion in low resource settings in tropical Africa, and by implication in other regions of the world where SCT is prevalent

The role of infections in the pathogenesis of bleeding among patients with haemophilia-A: A primer for haemophilia caregivers in the tropics

Haemophiliacs are often transfusion-dependent, and are at risk of HIV and non-HIV immunosuppression, making them vulnerable to transfusion-transmissible infections (TTIs) and non-TTIs, many of which can cause infection-associated bleeding (IAB) even in non-haemophilic individuals. Haemophiliacs are particularly susceptible to IAB due to vicious interaction between pre-existing ‘inherited’ FVIII deficiency and infection-induced ‘acquired’ pro-haemorrhagic abnormalities. IAB in haemophiliacs manifests as undue musculoskeletal and/or mucocutaneous haemorrhages. It is thus important for haemophilia caregivers in general (and in the tropics in particular) to have thorough understanding of IAB. Clinico-pathological perspectives of IAB in haemophilia are fragmented, and not comprehensively appraised in previous literature. This review presents updated, comprehensive but concise overview of pathogenesis, trigger mechanisms, clinical implications, therapy and prevention of IAB in haemophiliacs as accrued from literature. Methodology: Online databases such as PubMed, Medline, Google Scholar and others were interrogated using the search terms; ‘haemophilia-A’, ‘viral, bacterial and parasitic infections’, ‘bleeding’, ‘mucocutaneous’, ‘thrombocytopenia’, ‘ecchymosis’, ‘purpura’, ‘haematuria’, ‘melena’, ‘haematemesis’, and ‘haemoptysis’ in various combinations. Results: Pathogenesis of IAB in haemophilia include mucosal ulcerations, acquired coagulopathy, and/or portal hypertension. As long as the causative infections are untreated, IAB is often persistent or recurrent, predisposing patients to absenteeism from school/work, iron deficiency, excessive exposure to blood products, high risk of acquiring additional TTIs and increased risk of developing inhibitors to FVIII. Haemophilia caregivers should investigate stool, urine, sputum, blood and/or radiographs of all cases of persistent or recurrent bleeding, especially if bleeding is unabated by blood products transfusion alone, and more-so in patients presenting with constitutional and/or systemic indicators of infections such as pyrexia, asthenia, dysuria, cough, diarrhoea, jaundice, or history of passage of worms in the stool. Transfusion of blood products alone would not suffice for IAB, and transfusions of FVIII containing products without concurrent anti-infection chemotherapy may even promote the development of inhibitors since active infections and inflammations are important risk factors for inhibitor development in haemophiliacs. Conclusion: It is therapeutically essential to combine transfusion therapy with anti-infective chemotherapy in order to achieve prompt and sustained stoppage of IAB. Haemophilia caregivers should also counsel patients on hygiene, barrier protection against vectors, and vaccination protocols

EFFECT OF EXPERIMENTAL VARIABLES ON TRIBOLOGICAL PROPERTIES OF MARTENSITIC STAINLESS STEEL

Wear by slurry abrasion occurs during transport of abrasive slurries encountered in industrial and specially mining applications, extruders, and in slurry pumps. Steel piping systems are widely used in mining to convey the mineral, ore and tailing slurries to the processing plant, as well as to recycle the debris medium back to the mining area. Hardfacing by welding is one of the economic methods to improve wear resistance of engineering components. The present work reports slurry abrasion behaviour of hardfaced martensitic stainless steel under a wide range of experimental condition. The slurry abrasion experiments were performed using slurry abrasion test apparatus using silica sand as the abrasive medium. The effect of test parameter such as sliding distance, normal load and slurry concentration of abrasive medium on slurry abrasion behaviors of martensitic stainless steel was investigated. The slurry abrasion volume loss exhibited increasing trend with increasing sliding distance, normal load and slurry concentration, although the magnitude of increase was different in each case. The results of the investigation suggest and slurry concentration had relatively stronger effect as compared to that of normal load.. The morphological studies of the worn surfaces revealed characteristic differences in the wear pattern under different test conditions

Synthesis of Gamma-Alumina from Kankara Kaolin as Potential Zeolite Active Matrix

Commercial fluid catalytic cracking catalysts are manufactured using zeolites dispersed on an amorphous matrix, which is mostly alumina. Alumina is widely used as catalyst support in many heterogeneous catalytic processes owing to its high surface area, superior chemical activity and low cost. In compounded zeolite catalyst it serves as the active matrix which aids the conversion of the bulkiest molecules in the feed owing to its larger pore size than zeolite. Large specific surface area gamma-alumina (γ-Al2O3) was synthesized by hydrothermal method using Kankara kaolin as starting material. Thermal treatment of ammonium alum prepared from the filtrate of the dealuminated metakaolin was employed to obtain the alumina. Crystalline aluminum sulfate with 39 wt% Al2O3 was obtained at calcination temperature of 800°C with 3 h soaking. Gamma-alumina was produced at 850°C with 3 h soaking time, having specific surface area of 166 m2/g. The weight percent of Al2O3 content in the synthesized and commercial gamma-alumina were 85% and 89% respectively as obtained from the XRF analysis. Good comparison was also observed in the diffractogram of the synthesized and commercial gamma-alumina from the XRD analysis. The Scanning Electron Microscopy (SEM) image showed the platy hexagonal shape of the gamma-alumina.Keywords: Gamma-alumina, zeolite, kaoli

Preparation of High Grade Silica from Rice Husk for Zeolite Synthesis

Silica powder with approximately 96% purity was extracted from rice husk (RH) and used as a silica source for the synthesis of zeolite Y by hydrothermal process. The effect of synthesis parameters such as pH, temperature of burning the rice husk, acid leaching prior to formation of rice husk ash (RHA) on the properties of final product were studied. The acid-leached rice husk calcined at 650 °C for 6 h produced rough powder of rice husk silica, light brown in colour. The silica purity of the rice husk ash (RHA) calcined at 400, 450 and 5000C were 95.6wt%, 96.1wt% and 95.89 wt% respectively. The X-Ray Diffraction (XRD) pattern of the silica obtained show that the silica was amorphous with traces of crystalline phase. The amorphous nature of the RHA and the relatively high purity of silica content in it make it a suitable source of silica for zeolite synthesis.Keywords: Silica; RHA; Zeolite; Synthesis; Hydrothermal; Temperatur

Haemoglobin phenotypes and the risk of asymptomatic malaria parasitemia among blood donors in northwest Nigeria: clinical implications in the practice of tropical transfusion medicine

Background: In malaria-endemic populations, sickle cell trait (SCT) protects against both severe and non-severe malaria, but inconsistencies exist about protective effect of SCT on asymptomatic malarial parasitemia (AMP). Surprisingly, the effect of Hb-phenotypes on AMP has not been explored among blood donors in Nigeria or other malaria-endemic countries, where risks of AMP and transfusion transmitted malaria (TTM) are high. The objective of this study is to determine risk of AMP with respect to donor Hb-phenotypes (SCT versus HbAA), and elucidate clinical implications of AMP with respect to risk of TTM vis-à-vis the practice of transfusion medicine in Nigeria, and by implication other malaria-endemic tropical countries.Methodology: Analysis of 100 blood donors with AMP (cases) and 100 donors without AMP (controls) was performed. Frequencies of SCT and HbAA (determined by Hb electrophoresis) among cases and controls were compared by X2 -test. Risks of AMP (detected by microscopy) with respect to Hb-phenotypes were expressed as Odds ratios (OR) by case-control logistic regression.Results: In comparison with blood donor without AMP (controls), donors with AMP had lower frequencies of SCT (12% vs 28%, p<0.05) with corresponding higher frequencies of HbAA (88% vs 72%, p<0.05). HbAA is associated with high risk of AMP (OR=2.91, 95%CI: 2.10-3.48, p=0.021), while SCT is associated low risk of AMP (OR=0.49, 95%CI: 0.27-0.73, p=0.032).Conclusion: This finding shows that donor SCT is a surreptitious mitigator of the risk of AMP and TTM in the tropics. Therefore, patients who are selectively transfused with HbAA blood (e. g. neonates and sickle cell disease patients) could be at greater risks of TTM, and such patients need closer post transfusion monitoring. The risk of TTM calls for diligent post transfusion haemovigilance in Nigeria and other malaria endemic tropical countries in Africa Keywords: blood donors, sickle cell trait, asymptomatic malaria parasitemia, transfusion transmitted malari

High performance supercapacitor based on laser induced graphene for wearable devices

To ensure maximum comfort for the wearer, electronic components that include energy harvesters need to be mechanically conformable. In this context, we demonstrate a versatile, cost-effective and efficient method for fabricating graphene supercapacitor electrodes using Laser Induced Graphene (LIG). A CO2 laser beam instantly transforms the irradiated polyethersulfone polymer (PES) into a highly porous carbon structure. The LIG method was used to deposit graphene layers on graphite sheets to produce the supercapacitor electrodes. Graphene formation and morphology were examined and confirmed using several techniques including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) spectroscopy, Raman Spectroscopy and Fourier transform infrared spectroscopy (FTIR). Moreover, the electrochemical characterization was performed in different electrolytes (NaOH and KOH). At 5 mV s-1, the LIG electrode achieved 165 mF cm-2 and 250 mF cm-2 in NaOH and KOH electrolytes, respectively. Consequently, we show that a wearable symmetric supercapacitor device with LIG electrodes achieved 98.5 mF cm-2 at 5 mV s-1 in KOH electrolyte. The device demonstrated an energy density of 11.3 μWh.cm-2 with power density of 0.33 mWcm-2 at 0.5 mA cm-2. The retention of capacitance was 75% after 2000 cycles, with outstanding performance for the comparable graphene-based electrodes. These results further validate the use of LIG for developing flexible energy harvesters for wearable applications

Development and evaluation of a self-nanoemulsifying drug delivery system for sinapic acid with improved antiviral efficacy against SARS-CoV-2

This study aimed to develop a self-nanoemulsifying drug delivery system (SNE) for sinapic acid (SA) to improve its solubility and antiviral activity. Optimal components for the SA-SNE formulation were selected, including Labrafil as the oil, Cremophor EL as the surfactant, and Transcutol as the co-surfactant. The formulation was optimized using surface response design, and the optimized SA-SNE formulation exhibited a small globule size of 83.6 nm, high solubility up to 127.1 ± 3.3, and a 100% transmittance. In vitro release studies demonstrated rapid and high SA release from the formulation. Pharmacokinetic analysis showed improved bioavailability by 2.43 times, and the optimized SA-SNE formulation exhibited potent antiviral activity against SARS-CoV-2. The developed SA-SNE formulation can enhance SA’s therapeutic efficacy by improving its solubility, bioavailability, and antiviral activity. Further in silico, modeling, and Gaussian accelerated molecular dynamics (GaMD)-based studies revealed that SA could interact with and inhibit the viral main protease (Mpro). This research contributes to developing effective drug delivery systems for poorly soluble drugs like SA, opening new possibilities for their application via nebulization in SARS-CoV-2 therapy

Effect of concurrent resistance training on lower body strength, leg kick swimming, and sport-specific performance in competitive swimmers

The present study investigated the effect of 9 weeks of combined resistance training (aquatic and dry land resistance) on maximum lower body strength, leg kick, and swimming performance in competitive swimmers. Twenty-two male national competitive swimmers were randomly as-signed into two groups: experimental group (EG: age = 16.2 ± 0.3 years) or control group (CG: age = 16.3 ± 0.3 years). The EG performed a combined resistance training while the CG group com-pleted their usual training. One repetition maximum (1RM) back squat, 30 m leg kick, and swimming performance (100 m front crawl, start and turn) were evaluated in pre and post test. The findings showed a significant increase in 1RM back squat (d = 1.90; 14.94 ± 1.32%) after 9 weeks of combined resistance training. In addition, ours results revealed a significant improvement in 30 m leg kick swimming (d = 2.11; 5.84 ± 0.16%) and in all swimming, start and turn performances (d = 1.83 to 2.77; 2.69 ± 0.18% to 15.14 ± 1.06%) in EG. All dependent variables remained unchanged in the CG. To sum up, 9 weeks of combined resistance training can improve the maximum lower body strength and leg kick swimming performance. These improvements can be the essential factors that subsequently positively affected swimming, start and turn performances. Combined resistance training is an effective training that can be incorporated by coaches and swimmers into their programs to improve strength, leg kick swimming, and, subsequently, swimming performance in competitive swimmersThis research received no external funding. The authors thank all the subjects who participated in this studyinfo:eu-repo/semantics/publishedVersio