Growth Retardation Of Chick Embryo Exposed To A Low Dose Of Electromagnetic Waves.

BACKGROUND: The objectives of this study were to explore the effects of low dose of the nonionizing (REW) emitted by a mobile phone on the development of chick embryo. METHODS: one hundred and twenty chick fertilized eggs were equally divided into a control and an exposed group. Sixty fertilized eggs were placed in an egg incubator with a mobile phone (SAR US: 1.10W/kg (head) 0.47 W/kg body) in silent mode having vibration disable mode. Mobile was called for a total of 20 minutes in 24 hours. Twenty embryos each were sacrificed at day 5, 10 and 15, mortality, wet body weight, head to rump length, eye diameter and morphological changes were noted. The control group, 60 eggs were incubated in the same conditions, having removed the phone. RESULTS: No mortality was noted. The experimental group exposed to REW showed subcutaneous haemorrhagic areas and significant growth retardation at day 10 as evidence by smaller eye diameter, wet weight and CR length than the control group. There were no significant growth differences at either day 5 or at day 15. CONCLUSIONS: Electromagnetic waves emitted from mobile phones even though for a very short duration of 20 minutes per day have affected the growth of the chick embryo at day 10 of incubation, Hence exposure of these waves are not 100% safe.

Defining a mutational panel and predicting the prevalence of cystic fibrosis in oman.

OBJECTIVES: Cystic fibrosis transmembrane conductance regulator (CFTR) mutations form distinct mutational panels in different populations and subgroups. The frequency of cystic fibrosis (CF) mutations and prevalence are unknown in Oman. This study aimed to elucidate the mutational panel and prevalence of CF for the North Al Batinah (NAB) region in Oman and to estimate the national prevalence of CF based on the carrier screening of unrelated volunteers. METHODS: The study included retrospective and prospective analyses of CF cases in the NAB region for 1998-2012. Genetic analysis of disease-causing mutations was conducted by screening of the entire coding sequence and exon-intron borders. The obtained mutational panel was used for the carrier screening of 408 alleles of unrelated and unaffected Omani individuals. RESULTS: S549R and F508del were the major mutations, accounting for 89% of mutations in the patient population. Two private mutations, c.1733-1734delTA and c.1175T>G, were identified in the patient cohort. Two carriers, one for F508del and another for S549R, were identified by screening of the volunteer cohort, resulting in a predicted prevalence for Oman of 1 in 8,264. The estimated carrier frequency of CF in Oman was 1 in 94. The carrier frequency in the NAB region was 3.9 times higher. CONCLUSION: The mutational panel for the NAB region and the high proportion of S549R mutations emphasises the need for specific screening for CF in Oman. The different distribution of allele frequencies suggests a spatial clustering of CF in the NAB region.

Learning style preferences of preclinical medical students in oman.

OBJECTIVE: Our study sought to assess the learning preferences of students studying in the preclinical years of the medical degree program at Oman Medical College, Sohar. METHODS: In this descriptive, cross-sectional study, we administered a learning style questionnaire (VARK model) to 140 students to assess their preferred mode of learning, specifically the sensory modality by which they prefer to take in information. RESULTS: Over one third (35%) of the respondents expressed their preference for a single mode of learning, either visual (8%), auditory (9%), read/write (9%), or kinesthetic (9%). The remaining students preferred learning using a combination of either two (14%), three (19%), or four (32%) sensory modalities. CONCLUSION: The results of our study provide us with useful information to develop appropriate learning approaches to reach all types of learners at the college.

Analysis of human DNA-arginine photoadduct modified with peroxynitrite.

The aim of the study is the biochemical characterization of human DNA modified with arginine and peroxynitrite. In the present study, DNA was isolated from human blood cells and its adduct was formed with one of the amino acid, arginine. The DNA-arginine adduct was then modified with peroxynitrite, a reactive nitrogen species. The modified DNA adduct was characterized by ultraviolet (UV) absorption spectroscopy, thermal melting profile, and electrophoresis studies. UV spectroscopic analysis of the photoadduct showed hyperchromicity, indicating the formation of single-strand breaks and photomodification. Thermal denaturation studies of DNA-arginine adduct and peroxynitrite-modified adduct showed a decrease in the temperature (T(m)) value by 4.5°C and an increase in the T(m) of 8°C, respectively. Peroxynitrite modification is evident by an increase in the T(m) value and a change in the migration pattern of native and modified photoadducts on agarose gel electrophoresis. The DNA-arginine and peroxynitrite-modified photoadducts could have important implications in various pathophysiological and immunopathological conditions.

Comparative Difficulties with Non-Scientific General Vocabulary and Scientific/Medical Terminology in English as a Second Language (ESL) Medical Students.

OBJECTIVES: Medical education requires student comprehension of both technical (scientific/medical) and non-technical (general) vocabulary. Our experience with "English as a second language" (ESL) Arab students suggested they often have problems comprehending scientific statements because of weaknesses in their understanding of non-scientific vocabulary. This study aimed to determine whether ESL students have difficulties with general vocabulary that could hinder their understanding of scientific/medical texts. METHODS: A survey containing English text was given to ESL students in the premedical years of an English-medium medical school in an Arabic country. The survey consisted of sample questions from the Medical College Admission Test (USA). Students were instructed to identify all unknown words in the text. RESULTS: ESL students commenced premedical studies with substantial deficiencies in English vocabulary. Students from English-medium secondary schools had a selective deficiency in scientific/medical terminology which disappeared with time. Students from Arabic-medium secondary schools had equal difficulty with general and scientific/medical vocabulary. Deficiencies in both areas diminished with time but remained even after three years of English-medium higher education. CONCLUSION: Typically, when teaching technical subjects to ESL students, attention is focused on subject-unique vocabulary and associated modifiers. This study highlights that ESL students also face difficulties with the general vocabulary used to construct statements employing technical words. Such students would benefit from increases in general vocabulary knowledge.

Laparoscopic surgery recording as an adjunct to conventional modalities of teaching gross anatomy.

OBJECTIVES: In order to increase their effectiveness, methods of teaching morphological sciences need to be revised to incorporate the recent technological advances made in the field of medicine. Teaching human structure with conventional methods of prosections using dissected cadaveric specimen alone quite often fails to prepare students adequately for their clinical training. A learner-oriented method, incorporating three dimensional spatial anatomy and more closely mirroring the clinical setting, is required. METHODS: With these challenges in mind, a 30-minute slow-paced video recording of a cholecystectomy performed laproscopically on a 45 year-old lady was adapted to supplement the conventional teaching of anatomy of the abdomen and pelvis. This study was carried out in October 2010. RESULTS: The subjects of this study were 84 students in a first year preclinical MD course in human structure at the private Oman Medical College. Their feedback was obtained via questionnaire and revealed that the video presentation helped the students to realise the significance of the anatomical details learnt during the human structure course. CONCLUSION: Recordings of laparoscopic surgeries are an effective preclinical anatomy teaching resource in student-centred learning. They also help the students to appreciate the clinical relevance of gross anatomy and enhance their motivation to learn.

Interaction of ritonavir-boosted tipranavir with loperamide does not result in loperamide-associated neurologic side effects in healthy volunteers.

Loperamide (LOP) is a peripherally acting opioid receptor agonist used for the management of chronic diarrhea through the reduction of gut motility. The lack of central opioid effects is partly due to the efflux activity of the multidrug resistance transporter P-glycoprotein (P-gp) at the blood-brain barrier. The protease inhibitors are substrates for P-gp and have the potential to cause increased LOP levels in the brain. Because protease inhibitors, including tipranavir (TPV), are often associated with diarrhea, they are commonly used in combination with LOP. The level of respiratory depression, the level of pupil constriction, the pharmacokinetics, and the safety of LOP alone compared with those of LOP-ritonavir (RTV), LOP-TPV, and LOP-TPV-RTV were evaluated in a randomized, open-label, parallel-group study with 24 healthy human immunodeficiency virus type 1-negative adults. Respiratory depression was assessed by determination of the ventilatory response to carbon dioxide. Tipranavir-containing regimens (LOP-TPV and LOP-TPV-RTV) caused decreases in the area under the concentration-time curve from time zero to infinity for LOP (51% and 63% decreases, respectively) and its metabolite (72% and 77% decreases, respectively), whereas RTV caused increases in the levels of exposure of LOP (121% increase) and its metabolite (44% increase). In vitro and in vivo data suggest that TPV is a substrate for and an inducer of P-gp activity. The respiratory response to LOP in combination with TPV and/or RTV was not different from that to LOP alone. There was no evidence that LOP had opioid effects in the central nervous system, as measured indirectly by CO2 response curves and pupillary response in the presence of TPV and/or RTV.

Innate host defense of the lung: effects of lung-lining fluid pH.

Lung-lining fluid (LLF) is a primary constituent of the pulmonary host defense system. It is distributed continuously throughout the respiratory tract but is heterogeneous regarding its chemistry and physiology between the conducting airways and alveoli. The conducting airways are lined with airway surface liquid (ASL), a mucus gel-aqueous sol complex that interacts functionally with epithelial cilia as the mucociliary escalator. The alveoli are lined with alveolar subphase fluid (AVSF) and pulmonary surfactant. AVSF sterility is maintained in part by the phagocytic activity of resident alveolar macrophages. Normal ASL and AVSF are both more acidic than blood plasma. However, the details of acid-base regulation differ between the two media. Appreciable transepithelial acid-base flux is possible across the airway epithelium, whereas the alveolar epithelium is relatively impermeable to transepithelial acid-base flux. Moreover, one must consider the influence of resident macrophages on AVSF pH. Resident macrophages occupy a sizable fraction of AVSF by volume and are a substantial source of metabolic H+. The buffering capacities of ASL and AVSF probably are largely due to secreted peptides (e.g., ASL mucins and AVSF surfactant proteins). Acid-base exchange between the extracellular hydrophase and intracellular buffering systems of resident macrophages represents an additional buffer pool for AVSF. The pH of ASL and AVSF can be depressed by disease or inflammation. Low pH is predicted to suppress microbe clearance from the airways and alveoli, increase pathogen survival in both regions, and alter mediator release by resident macrophages and recruited leukocytes thereby increasing the propensity for bystander cell injury. Overall, ASL/AVSF pH is expected to be a major determinant of lung host defense responses.

A simplified model for V-ATPase H+ extrusion.

An analytical model of V-type H+-translocating ATPase (V-ATPase) was developed based on an approximation to the mechanochemical model of Grabe et al. (Biophys. J., pp. 2798-2813, vol. 78, 2000). Grabe's work utilizes structural information and physiological assumptions to construct a detailed mechanochemical model of the V-ATPase. Due to the complexity of their model, it does not give a readily usable mathematical expression for the V-ATPase current. Based on their analysis of the structure of the proton pump, we develop a two-compartment model of the V-ATPase, which contains a membrane "half-channel" for proton translocation separated by a hydrophilic strip and a hydrophobic wall from the cytoplasm. Using the Langevin equation to describe proton transport across the membrane, we simplify the model based on their assumptions on the molecular structure of the pump and arrive at a general form of solution to the proton pump flux driven by ATP hydrolysis based on assumptions on the physiological properties of the strip and the wall, as well as the two fluid compartments. In this process of simplification, we explicitly relate V-ATPase structure, stoichiometry, pump efficiency, and ATP hydrolysis energy to the active pump current. The simplified model is used to provide model-generated approximations to measured data from a variety of laboratories. In addition, it provides a very compact characterization of V-ATPase, which can be used as a proton extruder in a variety of different cell membranes, as well as in the membranes of intracellular organelles. Index Terms-Electrophysiology, mechanochemstry, molecular motors, proton extrusion

Pulmonary carbonic anhydrase in vertebrate gas exchange organs.

Carbonic anhydrase (CA) catalyzes the interconversion of CO(2) and HCO(3)(-). Intracellular (extravascular) and intravascular (extracellular) CA has been identified and localized in the lungs of reptiles and mammals. Less information is known, however, on the presence of intravascular CA in the lungs of amphibians and avians. In the present study, perfusion studies were used to compare the catalytic activity of pulmonary intravascular CA in reptiles and mammals. In addition, SDS-resistant CA activity was examined in microsomal fractions prepared from gill/lung tissue from representative animals in each vertebrate class. Finally, the CNO(-) sensitivity of the microsomal CA activity was compared. No SDS-resistant CA activity was found in gill microsomal fractions of several fish species. In contrast, the data suggest that SDS-resistant, intravascular pulmonary CA activity is present in air-breathing vertebrates with vastly differing lung morphologies and that the kinetics of inhibition is remarkably comparable between the vertebrate classes.

Intracellular pH regulation in U937 human monocytes: roles of V-ATPase and Na+/H+ exchange.

The role of plasmalemmal V-type H+ translocating ATPase (V-ATPase) in regulation of intracellular pH (pHi) is unclear in monocytes. This study examined the plasmalemmal V-ATPase and Na+/H+ exchanger (NHE) in U937 human monocytes. The fluorescent probe 2',7'-biscarboxyethyl-5,6-carboxyfluorescein was used to monitor baseline pHi and the kinetics of pHi recovery from cytosolic acid-loads (NH4Cl prepulse). Bafilomycin A1 and 5-(N-ethyl-N-isopropyl)amiloride (EIPA) were used to delineate the activities of the H+-pump and NHE, respectively. Baseline pHi was approximately 7.13 at an extracellular pH (pHo) of 7.4 and fell progressively at lower pHo values. EIPA had no effect on baseline pHi at pHo 7.4, but caused a sustained decrement in pHi at pHo 6.0-7.0. Bafilomycin A1 had biphasic effects on baseline pHi at pHo 6.5-7.4; pHi declined approximately 0.1 units over the course of several minutes and then recovered. At pHo 6.0, bafilomycin A1 caused a sustained decrement in baseline pHi. Recovery from the bafilomycin-induced acidosis at pHo 6.5-7.4 was prevented by EIPA. Similarly, pHi recovery from NH4Cl prepulse acid-loads (pHo 7.4) was sensitive to both EIPA and bafilomycin A1. During this recovery process, Na+/H+ exchange (EIPA-sensitive component of apparent H+ efflux) was the predominant mechanism for H+ extrusion at acid-loaded pHi values < 7.0. At acid-loaded pHi values > or = 7.0, the V-ATPase (bafilomycin-sensitive component) and NHE contributed almost equally to H+ extrusion. The data provide the first evidence that plasmalemmal V-ATPase participates in pHi regulation in U937 cells. The H+-pump and NHE interacted to set baseline pHi and for pHi recovery following cytosolic acid-loading of the monocytes.

Cell alkalosis elevates cytosolic Ca2+ in rabbit resident alveolar macrophages.

Disruption of cellular acid-base status alters the host defence functions of alveolar macrophages (m phi). These pH effects might be mediated by pH-sensitive changes in the signalling pathways of the effector functions of m phi. The present study examined the effects of intracellular pH (pH(i)) on the free cytosolic calcium concentration ([Ca(2+)](i)), an important second messenger for cell functions. [Ca(2+)](i) and pH(i) of rabbit resident alveolar m phi were measured using fluorescent dyes. With extracellular pH (pH(o)) of 7.4, the steady-state pH(i) and [Ca(2+)](i) were approx. 7.14 and 123 nM respectively. Incubation at pH(o) 6.8 caused a sustained cytosolic acidosis, but did not affect [Ca(2+)](i). Likewise, [Ca(2+)](i) was unchanged when m phi at pH(o) 7.4 were acidified using bafilomycin A(1) or sodium propionate. In contrast, [Ca(2+)](i) was markedly sensitive to cytosolic alkalosis. Exposure to NH(4)Cl at pH(o) 7.4 caused transient increases in both pH(i) and [Ca(2+)](i). The Ca(2+) response was mediated by release of intracellular Ca(2+) from thapsigargin-sensitive stores and was potentiated by capacitative entry of extracellular Ca(2+). Incubation at high pH(o) values (>7.4) produced sustained increases in pH(i) and [Ca(2+)](i). The sustained elevation of [Ca(2+)](i) was consistent with pH-sensitive inhibition of plasma-membrane Ca(2+)-ATPase. The response to high pH(o) was unaffected by blockade of L-type or receptor-operated Ca(2+) channels with nifedipine or SKF-96365, and was independent of extracellular Na(+). The findings indicate that pH impacts cytosolic Ca(2+) homoeostasis at multiple levels. The data suggest that cellular acid-base status can influence Ca(2+)-dependent signalling events in resident alveolar m phi, especially during alkaline disruptions of pH(i).

Plasmalemmal H+ extruders in mammalian alveolar macrophages.

The distribution of plasmalemmal V-type H+-pumps (V-ATPase) among mammalian macrophages (mvarphi) is uncertain and, hence, the functional significance of mvarphi plasmalemmal V-ATPase is unclear. This study investigated the role of V-ATPase in the regulation of intracellular pH (pH(i)) by resident alveolar mvarphi from sheep, pigs, dogs and rabbits. The fluorescent probe 2',7'-biscarboxyethyl-5,6-carboxyfluorescein was used to monitor baseline pH(i) and the rate of pH(i) recovery (dpH(i)/dt) from intracellular acid-loads (NH(4)Cl prepulse). Baseline pH(i) was 7.1-7.2. In sheep, pig and dog studies, 10 microM bafilomycin A(1) (a selective V-ATPase inhibitor) caused a rapid fall in baseline pH(i) (0.15-0.20 units); baseline values were unaffected by 0.1 mM amiloride (a Na+ transport inhibitor). V-ATPase activity (bafilomycin-sensitive component of dpH(i)/dt) was solely responsible for pH(i) recovery from intracellular acid-loads at acid-loaded pH(i) values >6.8-6.9. Na+/H+ exchange (amiloride-sensitive component of dpH(i)/dt) was detected only at acid-loaded pH(i) values <6.8. The activity of both H+ extruders increased at lower pH(i) values, albeit the Na+/H+ exchanger was more pH-sensitive than was V-ATPase. In rabbit studies, 10 microM bafilomycin A(1) and 1 mM N-ethylmaleimide (a non-specific H+-pump inhibitor) produced similar falls in baseline mvarphi pH(i), but had significantly larger effects than did the selective V-ATPase inhibitor concanamycin A (