Tertiary conformational transition constant of guinea pig haemoglobin determined from the reaction of 5,5′-dithiobis (2-nitrobenzoate) with CysF9[93]β and CysH3[125]β

We have determined Kequ, the equilibrium constant for the reaction of 5,5′-dithiobis(2-nitrobenzoate) — DTNB — with the CysF9*93+β and CysH3*125+β sulphydryl groups of various derivatives of guinea pig haemoglobin at 25oC. In the pH range 5.6 to 9, Kequ decreases almost 50-fold: from a mean of 3.45 ± 0.2 to a mean of 0.073 ± 0.01. Quantitative analyses of the pH dependence profiles of Kequ enable the determination of Krt, the equilibrium constant for the rt tertiary conformational transition of haemoglobin. The t isomer population is 53.9 (± 2)%. In the r conformation the pKas of the amino acid residues whose ionisations are coupled to the reaction of DTNB with the sulphydryl groups are 5.74 ± 0.02 — for a combination of HisNA2*2+β and HisH21*143+β) — and 7.74 ± 0.2 for ValNA1*1+β); in the t conformation they are 5.88 ± 0.05 and 8.23 ± 0.1, respectively.Keywords --- guinea pig haemoglobin; sulphydryl groups; 5,5′-dithiobis(2-nitrobenzoate); equilibrium constants; tertiary conformational transition

Isothermal, kinetics and thermodynamics studies of the biosorption of Pb (II) ion from aqueous solution using the scale of croaker fish (Genyonemus lineatus)

Biosorbent prepared from the scale of croaker fish (Genyonemus lineatus) has been used for the removal of Pb(II) ion from aqueous solution in a batch system. The effects of some important parameters such as pH, initial metal concentration, temperature and biosorbent dosage on biosorption capacity were investigated. Equilibrium time for the biosorption process is 20 and 30 min at lower and higher concentrations, respectively. The process at 28 °C is in agreement with a pseudo-second-order kinetics model. The equilibrium data obeyed the Langmuir adsorption isotherm with a maximum monolayer adsorption capacity of 14.58 mg g−1. The study showed that the sorption process depends on biomass dosage, temperature, pH and initial metal ion concentration. The calculated thermodynamics parameters (ΔGo, ΔHo and ΔSo) indicated that the biosorption of the metal ion onto fish scale is feasible, spontaneous and exothermic in nature

Perturbation of spectra properties of 3,4-diphenyl thiophene by polar and non polar solvents

The UV/visible spectra of 3,4-diphenyl thiophene were obtained in various solvents (both polar and non polar). The wave number of transition energies, corresponding molar absorp-tivities and oscillation frequency were determined. Three bands were obtained in solvents such as cyclohexane, propan-2-ol, methanol and ether. Two bands are obtained in n-hexane and 1,2-dichloroethane, while 1,4-dioxane give a single band. Transitions are assigned to these bands according to their shift due to the effect of solvents

Anticarcinogenic effect of alpha-lipoic acid and <i>Jatropha gossypifolia</i> leaves against cypermethrin-induced genotoxicity in rats

Background: Cypermethrin (Cyp), a synthetic pyrethroid developed for agricultural and public health applications, has become harmful to the environment and mammalian life owing to indiscriminate use. Aim: This study aimed to investigate the protective effect of the methanolic extract of Jatropha gossypifolia leaves against Cyp-induced genotoxicity in rats using alpha-lipoic acid (α-LA) as standard drug. Method: Fifty-six male Wistar rats, assigned to eight groups of seven animals each, were treated orally for 28 days as follows - Group 1: only corn oil (Control); Group 2: 20 mg/kg body weight (b.wt) of Cyp; Groups 3, 4 and 5: Cyp + 50 mg/kg b.wt of J. gossypifolia, Cyp + 100 mg/kg b.wt of J. gossypifolia and Cyp + 50 mg/kg b.wt of α-LA, respectively; Groups 6, 7 and 8: J. gossypifolia (50 mg/kg b.wt), J. gossypifolia (100 mg/kg b.wt) and α-LA (50 mg/kg b.wt), respectively. The P53 was assayed for using the plasma, while the micronucleus assay was carried out on the bone marrow. Results: Results showed that exposure to Cyp significantly increased the number of micronucleated polychromatic erythrocytes (86.70%) as well as p53 concentration in both the liver and plasma (200.00% and 125.53%) compared to the control. Co-administration with methanolic extract of J. gossypifolia leaves significantly reversed these alterations in a dose-dependent manner. Conclusion: The methanolic extract of J. gossypifolia leaves has the potential to ameliorate Cyp-induced genotoxicity in rats, and also, the toxicological evaluations of the plant extract and α-LA showed that it is relatively safe for use at the doses investigated

Multitasking, but for what benefit? The dilemma facing Nigerian university students regarding part-time working.

Students working part-time while studying for a full-time university degree are commonplace in many Western countries. This paper however, examines the historically uncommon part-time working activities and career aspirations among Nigerian university students. In particular, how working is perceived to contribute to developing employability skills, and whether it is influenced by their self-efficacy. Survey data from 324 questionnaires was collected from a federal university, although the data analysis used a mixed-method. The findings indicate that despite low levels of part-time working generally among students, older, more experienced, higher level and female students, place a premium on the skills that part-time work can develop. Moreover, self-efficacy and being female, is a significant predictor in understanding part-time work and career aspirations. This study offers originality by focusing on students’ part-time work, the value working provides, and its link with career aspirations, within a relatively unexplored context of Nigeria

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Design and methods for a quasi-experimental pilot study to evaluate the impact of dual active ingredient insecticide-treated nets on malaria burden in five regions in sub-Saharan Africa

Background Vector control tools have contributed significantly to a reduction in malaria burden since 2000, primarily through insecticidal-treated bed nets (ITNs) and indoor residual spraying. In the face of increasing insecticide resistance in key malaria vector species, global progress in malaria control has stalled. Innovative tools, such as dual active ingredient (dual-AI) ITNs that are effective at killing insecticide-resistant mosquitoes have recently been introduced. However, large-scale uptake has been slow for several reasons, including higher costs and limited evidence on their incremental effectiveness and cost-effectiveness. The present report describes the design of several observational studies aimed to determine the effectiveness and cost-effectiveness of dual-AI ITNs, compared to standard pyrethroid-only ITNs, at reducing malaria transmission across a variety of transmission settings. Methods Observational pilot studies are ongoing in Burkina Faso, Mozambique, Nigeria, and Rwanda, leveraging dual-AI ITN rollouts nested within the 2019 and 2020 mass distribution campaigns in each country. Enhanced surveillance occurring in select study districts include annual cross-sectional surveys during peak transmission seasons, monthly entomological surveillance, passive case detection using routine health facility surveillance systems, and studies on human behaviour and ITN use patterns. Data will compare changes in malaria transmission and disease burden in districts receiving dual-AI ITNs to similar districts receiving standard pyrethroid-only ITNs over three years. The costs of net distribution will be calculated using the provider perspective including financial and economic costs, and a cost-effectiveness analysis will assess incremental cost-effectiveness ratios for Interceptor® G2, Royal Guard®, and piperonyl butoxide ITNs in comparison to standard pyrethroid-only ITNs, based on incidence rate ratios calculated from routine data. Conclusions Evidence of the effectiveness and cost-effectiveness of the dual-AI ITNs from these pilot studies will complement evidence from two contemporary cluster randomized control trials, one in Benin and one in Tanzania, to provide key information to malaria control programmes, policymakers, and donors to help guide decision-making and planning for local malaria control and elimination strategies. Understanding the breadth of contexts where these dual-AI ITNs are most effective and collecting robust information on factors influencing comparative effectiveness could improve uptake and availability and help maximize their impact

An overview of transmission theory and techniques of large-scale antenna systems for 5G wireless communications

To meet the future demand for huge traffic volume of wireless data service, the research on the fifth generation (5G) mobile communication systems has been undertaken in recent years. It is expected that the spectral and energy efficiencies in 5G mobile communication systems should be ten-fold higher than the ones in the fourth generation (4G) mobile communication systems. Therefore, it is important to further exploit the potential of spatial multiplexing of multiple antennas. In the last twenty years, multiple-input multiple-output (MIMO) antenna techniques have been considered as the key techniques to increase the capacity of wireless communication systems. When a large-scale antenna array (which is also called massive MIMO) is equipped in a base-station, or a large number of distributed antennas (which is also called large-scale distributed MIMO) are deployed, the spectral and energy efficiencies can be further improved by using spatial domain multiple access. This paper provides an overview of massive MIMO and large-scale distributed MIMO systems, including spectral efficiency analysis, channel state information (CSI) acquisition, wireless transmission technology, and resource allocation