Prevalence of Noise Induced Hearing Loss in Indian Air Force Personnel

Background

Noise exposure is an inherent part of duty of the aircrew and maintenance staff in the Indian Air Force (IAF). An audiometric survey of IAF personnel was carried out to analyze the prevalence and severity of noise induced hearing loss (NIHL).

Methods

An audiometric study of 1000 IAF personnel of various trades, age and exposure groups were carried out at an operational base. Age related correction of 5 dB per decade was applied for personnel above SO years of age. Personal factors like smoking, blood group and use of ear defenders were analysed for their effect on the prevalence of NIHL.

Result

The study revealed an overall incidence of NIHL of 22.9 % in the personnel with a higher prevalence among the technical trades (26.18 %) as compared to non technical trades (12.5 %). There was a significant increase in prevalence of hearing loss with duration of exposure with 50.8% of personnel above 30 years of exposure having hearing loss. A higher incidence of hearing loss was observed in personnel of blood group O and smokers whereas use of ear defenders was protective.

Conclusion

The study reveals a significantly increased prevalence of NIHL among the technical trades of the IAF personnel. The deleterious effects of smoking and protective effect of regular use of ear defenders are emphasized.Key Words: Noise induced hearing loss, Smoking, Ear defenders     

The challenge of exploiting ABCG2 in the clinic

ABCG2, or breast cancer resistance protein (BCRP), is an ATP-binding cassette half transporter that has been shown to transport a wide range of substrates including chemotherapeutics, antivirals, antibiotics and flavonoids. Given its wide range of substrates, much work has been dedicated to developing ABCG2 as a clinical target. But where can we intervene clinically and how can we avoid the mistakes made in past clinical trials targeting P-glycoprotein? This review will summarize the normal tissue distribution, cancer tissue expression, substrates and inhibitors of ABCG2, and highlight the challenges presented in exploiting ABCG2 in the clinic. We discuss the possibility of inhibiting ABCG2, so as to increase oral bioavailability or increase drug penetration into sanctuary sites, especially the central nervous system; and at the other end of the spectrum, the possibility of improving ABCG2 function, in the case of gout caused by a single nucleotide polymphism. Together, these aspects of ABCG2/BCRP make the protein a target of continuing interest for oncologists, biologists, and pharmacologists.     

Meeting oxygen needs in Africa: an options analysis from the?Gambia

Objective

To compare oxygen supply options for health facilities in the Gambia and develop a decision-making algorithm for choosing oxygen delivery systems in Africa and the rest of the developing world.

Methods

Oxygen cylinders and concentrators were compared in terms of functionality and cost. Interviews with key informants using locally developed and adapted WHO instruments, operational assessments, cost-modelling and cost measurements were undertaken to determine whether oxygen cylinders or concentrators were the better choice. An algorithm and a software tool to guide the choice of oxygen delivery system were constructed.

Findings

In the Gambia, oxygen concentrators have significant advantages compared to cylinders where power is reliable; in other settings, cylinders are preferable as long as transporting them is feasible. Cylinder costs are greatly influenced by leakage, which is common, whereas concentrator costs are affected by the cost of power far more than by capital costs. Only two of 12 facilities in the Gambia were found suitable for concentrators; at the remaining 10 facilities, cylinders were the better option.

Conclusion

Neither concentrators nor cylinders are well suited to every situation, but a simple options assessment can determine which is better in each setting. Nationally this would result in improved supply and lower costs by comparison with conventional cylinders alone, although ensuring a reliable supply would remain a challenge. The decision algorithm and software tool designed for the Gambia could be applied in other developing countries.     

Association of variant ABCG2 and the pharmacokinetics of epidermal growth factor receptor tyrosine kinase inhibitors in cancer patients

The purpose of the study was to determine if the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), gefitinib and erlotinib, are substrates for the efflux transporter ABCG2, and to investigate the relevance of the ABCG2 421C>A (Q141K) polymorphism to the pharmacokinetics of gefitinib. Gefitinib and erlotinib transport in vitro was studied using HEK293 cells transfected with wild-type ABCG2 or a Q141K clone. Gefitinib pharmacokinetics was determined in 27 cancer patients. was. ABCG2 421C>A and ABCB1 3435C>T genotypes were determined using direct sequencing. Cells expressing wild-type ABCG2 exhibited lower intracellular accumulation of gefitinib and erlotinib at concentrations of 0.1 and 1 microM, and higher efflux at 1 microM than cells lacking ABCG2 (p < 0.05); no significant difference in cellular efflux and accumulation was observed in the variant cell line at lower concentrations nor in the three cell lines at 10 microM. In the presence of the ABCG2 inhibitor fumitremorgin C, cellular accumulation of gefitinib and erlotinib 1 microM was increased in wild-type (p < 0.05), but not in variant or null cells. Gefitinib accumulation during 28 days of treatment (C(ss,min)/C(1,min)) was higher in patients heterozygous at the ABCG2 421C>A locus than those with a wild-type genotype (median, 5.07 vs. 3.60, p = 0.004). No significant associations were observed between the ABCB1 3435C>T genotype and gefitinib pharmacokinetics. In conclusion, gefitinib and erlotinib are ABCG2 substrates, while they inhibit ABCG2 at higher concentrations. A functional variant of ABCG2 is associated with greater gefitinib accumulation at steady-state and may be relevant to toxicity and antitumor activity of EGFR TKIs.     

Exercise-induced changes in the cortical bone of growing mice are bone- and gender-specific

Fracture risk and mechanical competence of bone are functions of bone mass and tissue quality, which in turn are dependent on the bone's mechanical environment. Male mice have a greater response to non-weight-bearing exercise than females, resulting in larger, stronger bones compared with control animals. The aim of this study was to test the hypothesis that short-term weight-bearing running during growth (21 days starting at 8 weeks of age; 30 min/day; 12 m/min; 5 degrees incline; 7 days/week) would similarly have a greater impact on cross-sectional geometry and mechanical competence in the femora and tibiae of male mice versus females. Based on the orientation of the legs during running and the proximity of the tibia to the point of impact, this response was hypothesized to be greatest in the tibia. Exercise-related changes relative to controls were assayed by four-point bending tests, while volumetric bone mineral density and cross-sectional geometry were also assessed. The response to running was bone- and gender-specific, with male tibiae demonstrating the greatest effects. In male tibiae, periosteal perimeter, endocortical perimeter, cortical area, medial-lateral width and bending moment of inertia increased versus control mice suggesting that while growth is occurring in these mice between 8 and 11 weeks of age, exercise accelerated this growth resulting in a greater increase in bone tissue over the 3 weeks of the study. Exercise increased tissue-level strain-to-failure and structural post-yield deformation in the male tibiae, but these post-yield benefits came at the expense of decreased yield deformation, structural and tissue-level yield strength and tissue-level ultimate strength. These results suggest that exercise superimposed upon growth accelerated growth-related increases in tibial cross-sectional dimensions. Exercise also influenced the quality of this forming bone, significantly impacting structural and tissue-level mechanical properties.     

A case of near‐drowning: a case for routine cerebral monitoring

A 6‐week‐old infant presenting with near‐drowning was medically paralysed and ventilated on admission. Status epilepticus was found on cerebral function monitoring, without which the diagnosis would have been missed or delayed for many hours. This case illustrates the value of cerebral function monitoring for patients in intensive care, where clinical signs of seizure activity are frequently masked by paralysis and sedation. Conclusion: Limited availability of electroencephalogram (EEG) and cerebral function monitoring (CFM) in paediatric intensive care may inadvertently delay diagnosis and appropriate treatments and so adversely affect outcomes. We propose that round‐the‐clock cerebral function and/or EEG monitoring should be available in all centres that provide paediatric intensive care.