The Covid-19 and online learning process in Bangladesh

This study investigates the augmentation of students' engagement in the online learning process using Zoom platform. To engage students more in the online classes we have conducted a survey on four universities students in the four dimensions. To investigate effective online class, we have gone through descriptive statistics followed by principal component analysis (PCA) and factor regression model to identify predicted factors that engage students more in the Zoom online classes. The results of PCA confirmed that questions answer session, instructor asks question to them, break during the class, topic related examples, experience sharing scope, case studies, using Google classroom, screen share, screen annotation, video contents share, class recording, raise hand and reactions to topics can enhance students engagement in the Zoom online classes. The regression results validate all four dimensions have significant influence on effective zoom online class that enhance students learning process. Thus, findings of this study recommend educating course instructors for ensuring all the applications of online learning process while conducting online classes. We strongly believe this course of action will engage students in the online class to enhance learning activities using Zoom platform in Bangladesh.

Biological Efficacy of Compounds from Stingless Honey and Sting Honey against Two Pathogenic Bacteria: An In Vitro and In Silico Study

Honey inhibits bacterial growth due to the high sugar concentration, hydrogen peroxide generation, and proteinaceous compounds present in it. In this study, the antibacterial activity of stingless and sting honey against foodborne pathogenic bacteria isolated from spoiled milk samples was examined. The isolated bacterial strains were confirmed as Bacillus cereus and Listeriamonocytogenes through morphological, biochemical, and 16 s RNA analysis. Physiochemical characterizations of the honey samples revealed that both of the honey samples had an acidic pH, low water content, moderate reducing sugar content, and higher proline content. Through the disc diffusion method, the antibacterial activities of the samples were assayed and better results were observed for the 50 mg/disc honey. Both stingless and sting honey showed the most positive efficacy against Bacillus cereus. Therefore, an in silico study was conducted against this bacterium with some common compounds of honey. From several retrieved constituents of stingless and sting honey, 2,4-dihydroxy-2,5-dimethyl 3(2H)-furan-3-one (furan) and 4H-pyran-4-one,2,3-dihydro of both samples and beta.-D-glucopyranose from the stingless revealed high ligand-protein binding efficiencies for the target protein (6d5z, hemolysin II). The root-mean-square deviation, solvent-accessible surface area, the radius of gyration, root-mean-square fluctuations, and hydrogen bonds were used to ensure the binding stability of the docked complexes in the atomistic simulation and confirmed their stability. The combined effort of wet and dry lab-based work support, to some extent, that the antimicrobial properties of honey have great potential for application in medicine as well as in the food industries.

Diseases association with the polymorphic major histocompatibility complex class I related chain a: MICA gene

The Major Histocompatibility Complex class I chain-related molecule A (MICA) genes encode a highly polymorphic glycoprotein among the cell surface antigens that trigger an immune response after allograft transplantation. It is encoded by the MICA gene, a member of the glycosylated MIC genes. Discovered in 1994, the MICA gene is located within the MHC class I region. Moreover, its biological function is achieved through the interaction with the NKG2D receptor. Unlike the classical HLA molecules, MICA protein is not associated with β2- microglobulin nor binds peptides. MICA gene expression may result in a cytotoxic response and IFN-γ secretion through the up-regulation by heat shock proteins in response to infection (Human Cytomegalovirus HCMV), mediated by NKG2D-expressing cells. Anti-MICA antibodies were identified as significant risk factors for antibody mediated rejection after being detected in sera of patients with graft rejection. In addition, soluble MICA proteins (sMICA) has been detected in the serum of transplant recipients with cancers. Furthermore, the association of MICA polymorphisms with infectious diseases, various autoimmune diseases, cancer, and allograft rejection or graft-versus-host disease (GVHD) has been studied. Moreover, numerous advanced disease studies centered on MICA polymorphism are independent of HLA association. In this review, we discussed the up-to-date data about MICA and the association of MICA polymorphism with infections, autoimmune diseases, graft-versus-host disease, and cancer.

Role of oxidative stress in angiogenesis and the therapeutic potential of antioxidants in breast cancer

The escalation of cancer cases globally, especially breast cancer, is of concern. Angiogenesis is hallmark of cancer pathogenesis and plays an important role in cancer progression and metastasis. Pro-angiogenic agents, secreted by tumor cells, form new blood vessels, and produce reactive oxygen species (ROS). ROS promote angiogenesis via two major pathways: namely Vascular Endothelial Growth Factor (VEGF) dependent and non-VEGF dependent pathways. As a consequence of unbalanced ROS overproduction and low antioxidants levels, oxidative stress occurs and promotes angiogenesis in breast cancer tissues. Thus, the potential use of antioxidants as a preventive therapy in breast cancer. Preclinical studies depict that vitamins A and E may counter oxidative stress resulting in reduction of metastasis and viability of breast cancer. Furthermore, clinical studies demonstrate a decline in breast cancer risk in postmenopausal women upon the consumption of antioxidants. Herein, we discuss various pro-angiogenic agents that may play an important role in breast cancer angiogenesis. Moreover, the contribution of oxidative stress in inducing the angiogenic process is extensively reviewed here. Furthermore, the findings of pre-clinical and clinical studies on the use of antioxidants, namely vitamins A and E, in breast cancer are deliberated upon, along with the role of angiogenesis in cancer therapy.

Multiresidue Gas Chromatographic Method for Determining Synthetic Pyrethroid Pesticides in Agricultural Products: Collaborative Study

Fourteen laboratories from 6 countries and regions participated in an international collaborative study to evaluate a multiresidue gas chromatographic (GC) method for determining 8 synthetic pyrethroid pesticides in grains, fruits, and vegetables. The study design was based on Youden’s matched-pairs principle for collaborative tests of analytical methods. Each laboratory analyzed 12 collaborative samples of wheat, oranges, and tomatoes as blind samples. Wheat samples were extracted with acetonitrile–water (2 + 1), while orange and tomato samples were extracted with acetone. Residues were partitioned into hexane, evaporated to dryness with a rotary evaporator, and then dissolved in hexane. The hexane extract was partitioned with acetonitrile and cleaned up on a 5% water-deactivated Florisil column with 6% ethyl ether in hexane as eluant. Residue concentrations were determined by GC with electron capture detection with split-less injection by comparison with single-point calibration standards. The appropriate standard concentration was determined by screening sample extracts before analysis. The multiresidue method was tested over the concentration range of 0.0951.909 mg/kg depending on the 8 different of pesticides and agricultural products analyzed in the collaborative study. Statistical analysis of data from 13 laboratories showed weighted average recoveries for 8 pyrethroids in wheat, oranges, and tomatoes at 0.105–1.909,0.095–1.909, and 0.105–0.954 mg/kg, respectively, ranging from 91.8 to 100.2%, from 88.1 to 100.6%, and from 88.2 to 101.5%, respectively. Reproducibility relative standard deviation values ranged from 6.46 to 17.74%, from 5.94 to 18.13%, and from 5.59 to 10.48%, respectively. Repeatability relative standard deviation values ranged from 6.34 to 10.84%, from 5.19 to 11.72%, and from 3.20 to 8.09%, respectively. The multiresidue GC method for determining synthetic pyrethroid pesticides in agricultural products has been adopted first action by AOAC INTERNATIONAL.

Azimuthal Anisotropy of Heavy-Flavor Decay Electrons in p-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

Angular correlations between heavy-flavor decay electrons and charged particles at midrapidity (|η|<0.8) are measured in p-Pb collisions at sqrt[s_{NN}]=5.02  TeV. The analysis is carried out for the 0%-20% (high) and 60%-100% (low) multiplicity ranges. The jet contribution in the correlation distribution from high-multiplicity events is removed by subtracting the distribution from low-multiplicity events. An azimuthal modulation remains after removing the jet contribution, similar to previous observations in two-particle angular correlation measurements for light-flavor hadrons. A Fourier decomposition of the modulation results in a positive second-order coefficient (v_{2}) for heavy-flavor decay electrons in the transverse momentum interval 1.5<p_{T}<4  GeV/c in high-multiplicity events, with a significance larger than 5σ. The results are compared with those of charged particles at midrapidity and those of inclusive muons at forward rapidity. The v_{2} measurement of open heavy-flavor particles at midrapidity in small collision systems could provide crucial information to help interpret the anisotropies observed in such systems.

Protein C Deficiency Causing Recurrent Myocardial Infarction in a Young Male

Protein C is one of the most important factors that prevent blood from clotting. Protein C deficiency usually leads to venous thrombosis. We intend to report a male of 38 years admitted in coronary care unit of Dhaka Medical College Hospital, who suffered recurrent episodes of myocardial infarction, whose traditional risk factors were well controlled. Ultimately he was diagnosed with protein C deficiency, which is not commonly implicated in arterial thrombosis. Protein C deficiency can rarely cause severe life threatening arterial thrombosis, like myocardial infarction. Many more cases are reported in recent literature. It can happen sporadically. A high degree of suspicion should be maintained if traditional risk factors are absent in instances of arterial thrombosis, to look for protein C deficiency.

D-Meson Azimuthal Anisotropy in Midcentral Pb-Pb Collisions at sqrt[s]_{NN}=5.02 TeV

The azimuthal anisotropy coefficient v_{2} of prompt D^{0}, D^{+}, D^{*+}, and D_{s}^{+} mesons was measured in midcentral (30%-50% centrality class) Pb-Pb collisions at a center-of-mass energy per nucleon pair sqrt[s_{NN}]=5.02  TeV, with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decays at midrapidity, |y|<0.8, in the transverse momentum interval 1<p_{T}<24  GeV/c. The measured D-meson v_{2} has similar values as that of charged pions. The D_{s}^{+} v_{2}, measured for the first time, is found to be compatible with that of nonstrange D mesons. The measurements are compared with theoretical calculations of charm-quark transport in a hydrodynamically expanding medium and have the potential to constrain medium parameters.

J/ψ Elliptic Flow in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

We report a precise measurement of the J/ψ elliptic flow in Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV with the ALICE detector at the LHC. The J/ψ mesons are reconstructed at midrapidity (|y|<0.9) in the dielectron decay channel and at forward rapidity (2.5<y<4.0) in the dimuon channel, both down to zero transverse momentum. At forward rapidity, the elliptic flow v_{2} of the J/ψ is studied as a function of the transverse momentum and centrality. A positive v_{2} is observed in the transverse momentum range 2<p_{T}<8  GeV/c in the three centrality classes studied and confirms with higher statistics our earlier results at sqrt[s_{NN}]=2.76  TeV in semicentral collisions. At midrapidity, the J/ψ  v_{2} is investigated as a function of the transverse momentum in semicentral collisions and found to be in agreement with the measurements at forward rapidity. These results are compared to transport model calculations. The comparison supports the idea that at low p_{T} the elliptic flow of the J/ψ originates from the thermalization of charm quarks in the deconfined medium but suggests that additional mechanisms might be missing in the models.

Anomalous Evolution of the Near-Side Jet Peak Shape in Pb-Pb Collisions at sqrt[s_{NN}]=2.76 TeV

The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a p_{T} region inaccessible by direct jet identification. In these measurements pseudorapidity (Δη) and azimuthal (Δφ) differences are used to extract the shape of the near-side peak formed by particles associated with a higher p_{T} trigger particle (1<p_{T,trig}<8  GeV/c). A combined fit of the near-side peak and long-range correlations is applied to the data allowing the extraction of the centrality evolution of the peak shape in Pb-Pb collisions at sqrt[s_{NN}]=2.76  TeV. A significant broadening of the peak in the Δη direction at low p_{T} is found from peripheral to central collisions, which vanishes above 4  GeV/c, while in the Δφ direction the peak is almost independent of centrality. For the 10% most central collisions and 1<p_{T,assoc}<2  GeV/c, 1<p_{T,trig}<3  GeV/c a novel feature is observed: a depletion develops around the center of the peak. The results are compared to pp collisions at the same center of mass energy and ampt model simulations. The comparison to the investigated models suggests that the broadening and the development of the depletion is connected to the strength of radial and longitudinal flow.

Flow Dominance and Factorization of Transverse Momentum Correlations in Pb-Pb Collisions at the LHC

We present the first measurement of the two-particle transverse momentum differential correlation function, P_{2}≡⟨Δp_{T}Δp_{T}⟩/⟨p_{T}⟩^{2}, in Pb-Pb collisions at sqrt[s_{NN}]=2.76  TeV. Results for P_{2} are reported as a function of the relative pseudorapidity (Δη) and azimuthal angle (Δφ) between two particles for different collision centralities. The Δϕ dependence is found to be largely independent of Δη for |Δη|≥0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around Δφ=π (i.e., on the away side), which is not observed in number correlations in the same centrality range, and thus provides an indication of the dominance of triangular flow in this collision centrality. Fourier decompositions of P_{2}, studied as a function of the collision centrality, show that correlations at |Δη|≥0.9 can be well reproduced by a flow ansatz based on the notion that measured transverse momentum correlations are strictly determined by the collective motion of the system.

Correlated Event-by-Event Fluctuations of Flow Harmonics in Pb-Pb Collisions at sqrt[s_{NN}]=2.76 TeV

We report the measurements of correlations between event-by-event fluctuations of amplitudes of anisotropic flow harmonics in nucleus-nucleus collisions, obtained for the first time using a new analysis method based on multiparticle cumulants in mixed harmonics. This novel method is robust against systematic biases originating from nonflow effects and by construction any dependence on symmetry planes is eliminated. We demonstrate that correlations of flow harmonics exhibit a better sensitivity to medium properties than the individual flow harmonics. The new measurements are performed in Pb-Pb collisions at the center-of-mass energy per nucleon pair of sqrt[s_{NN}]=2.76  TeV by the ALICE experiment at the Large Hadron Collider. The centrality dependence of correlation between event-by-event fluctuations of the elliptic v_{2} and quadrangular v_{4} flow harmonics, as well as of anticorrelation between v_{2} and triangular v_{3} flow harmonics are presented. The results cover two different regimes of the initial state configurations: geometry dominated (in midcentral collisions) and fluctuation dominated (in the most central collisions). Comparisons are made to predictions from Monte Carlo Glauber, viscous hydrodynamics, ampt, and hijing models. Together with the existing measurements of the individual flow harmonics the presented results provide further constraints on the initial conditions and the transport properties of the system produced in heavy-ion collisions.

Centrality Dependence of the Charged-Particle Multiplicity Density at Midrapidity in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

The pseudorapidity density of charged particles, dN_{ch}/dη, at midrapidity in Pb-Pb collisions has been measured at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02  TeV. For the 5% most central collisions, we measure a value of 1943±54. The rise in dN_{ch}/dη as a function of sqrt[s_{NN}] is steeper than that observed in proton-proton collisions and follows the trend established by measurements at lower energy. The increase of dN_{ch}/dη as a function of the average number of participant nucleons, ⟨N_{part}⟩, calculated in a Glauber model, is compared with the previous measurement at sqrt[s_{NN}]=2.76  TeV. A constant factor of about 1.2 describes the increase in dN_{ch}/dη from sqrt[s_{NN}]=2.76 to 5.02 TeV for all centrality classes, within the measured range of 0%-80% centrality. The results are also compared to models based on different mechanisms for particle production in nuclear collisions.

Measurement of an Excess in the Yield of J/ψ at Very Low p_{T} in Pb-Pb Collisions at sqrt[s]_{NN}=2.76 TeV

We report on the first measurement of an excess in the yield of J/ψ at very low transverse momentum (p_{T}<0.3  GeV/c) in peripheral hadronic Pb-Pb collisions at sqrt[s_{NN}]=2.76  TeV, performed by ALICE at the CERN LHC. Remarkably, the measured nuclear modification factor of J/ψ in the rapidity range 2.5<y<4 reaches about 7 (2) in the p_{T} range 0-0.3  GeV/c in the 70%-90% (50%-70%) centrality class. The J/ψ production cross section associated with the observed excess is obtained under the hypothesis that coherent photoproduction of J/ψ is the underlying physics mechanism. If confirmed, the observation of J/ψ coherent photoproduction in Pb-Pb collisions at impact parameters smaller than twice the nuclear radius opens new theoretical and experimental challenges and opportunities. In particular, coherent photoproduction accompanying hadronic collisions may provide insight into the dynamics of photoproduction and nuclear reactions, as well as become a novel probe of the quark-gluon plasma.

Anisotropic Flow of Charged Particles in Pb-Pb Collisions at √[s{NN}]=5.02 TeV

We report the first results of elliptic (v_{2}), triangular (v_{3}), and quadrangular (v_{4}) flow of charged particles in Pb-Pb collisions at a center-of-mass energy per nucleon pair of sqrt[s_{NN}]=5.02  TeV with the ALICE detector at the CERN Large Hadron Collider. The measurements are performed in the central pseudorapidity region |η|<0.8 and for the transverse momentum range 0.2<p_{T}<5  GeV/c. The anisotropic flow is measured using two-particle correlations with a pseudorapidity gap greater than one unit and with the multiparticle cumulant method. Compared to results from Pb-Pb collisions at sqrt[s_{NN}]=2.76  TeV, the anisotropic flow coefficients v_{2}, v_{3}, and v_{4} are found to increase by (3.0±0.6)%, (4.3±1.4)%, and (10.2±3.8)%, respectively, in the centrality range 0%-50%. This increase can be attributed mostly to an increase of the average transverse momentum between the two energies. The measurements are found to be compatible with hydrodynamic model calculations. This comparison provides a unique opportunity to test the validity of the hydrodynamic picture and the power to further discriminate between various possibilities for the temperature dependence of shear viscosity to entropy density ratio of the produced matter in heavy-ion collisions at the highest energies.

Intraoperative and delayed wound approximation in closure of skin defects in different areas

OBJECTIVE

Wound approximation device is an interesting reconstructive option but not well popularised. In this study we present a simple device that can be used for immediate or delayed closure of large dermal wounds in different anatomical areas.

METHOD

Patients with acute and chronic wounds were recruited and underwent immediate intra-operative wound approximation and/or delayed wound approximation, with a home-made wound approximation device.

RESULTS

Approximation time in the immediate closure group ranged from 20-140 minutes. Satisfactory scars were obtained in 19 patients (76%) and adherent scars developed in 6 patients. Delayed wound approximation was used successfully in closure of 9 defects.

CONCLUSION

This simple dermal wound approximation device can be used intraoperatively to successfully close large difficult wounds, located on the trunk and thigh, with minimal complications. The device can also be used to approximate delayed wounds located in regions where closure is particularly problematic, like the lower leg, foot, and scalp. Some modifications of the device are needed to improve its safety and efficacy. Wound tension is detrimental to adequate wound healing and tensile strength, another basic principle that should not be overlooked to avoid wound dehiscence. Wound approximation is adding to reconstructive options, not replacing them, and they must always be considered.

Measurement of pion, kaon and proton production in proton-proton collisions at [Formula: see text] TeV

The measurement of primary [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] production at mid-rapidity ([Formula: see text] 0.5) in proton-proton collisions at [Formula: see text][Formula: see text] 7 TeV performed with a large ion collider experiment at the large hadron collider (LHC) is reported. Particle identification is performed using the specific ionisation energy-loss and time-of-flight information, the ring-imaging Cherenkov technique and the kink-topology identification of weak decays of charged kaons. Transverse momentum spectra are measured from 0.1 up to 3 GeV/[Formula: see text] for pions, from 0.2 up to 6 GeV/[Formula: see text] for kaons and from 0.3 up to 6 GeV/[Formula: see text] for protons. The measured spectra and particle ratios are compared with quantum chromodynamics-inspired models, tuned to reproduce also the earlier measurements performed at the LHC. Furthermore, the integrated particle yields and ratios as well as the average transverse momenta are compared with results at lower collision energies.

Endothelin receptor A-specific stimulation of glomerular inflammation and injury in a streptozotocin-induced rat model of diabetes

AIMS/HYPOTHESIS

Activation of endothelin receptor-A (ET(A)) increases glomerular permeability to albumin (P(alb)) and elevates pro-inflammatory markers in hyperglycaemic rats.

METHODS

Male Sprague-Dawley rats were given streptozotocin (n = 32) or saline (sham; n = 32). Half of the animals in each group received the ET(A)-selective antagonist, ABT-627 (atrasentan; orally), beginning immediately after hyperglycaemia was confirmed. Glomeruli were isolated by sieving techniques and P(alb) determined from the change in glomerular volume induced by oncotic gradients of albumin. Glomerular nephrin levels were assessed by immunofluorescence, whereas urinary nephrin was measured by immunoassay.

RESULTS

At 3 and 6 weeks after streptozotocin injection, proteinuria was significantly increased compared with sham controls and significantly reduced by ABT-627 treatment. P(alb) was also increased at 3 and 6 weeks post-streptozotocin. ABT-627 had no effect on P(alb) or protein excretion in sham control rats. In glomeruli isolated from hyperglycaemic rats, incubation with BQ-123, a selective ET(A) antagonist, reduced P(alb), whereas BQ-788, a selective endothelin receptor-B antagonist had no effect (n = 6 rats per group, 5-8 glomeruli per rat). Glomerular and plasma content of soluble intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 were significantly increased 6 weeks after streptozotocin (ELISA). ABT-627 attenuated these increases. After 6 weeks of hyperglycaemia, glomerular nephrin content was decreased with a concurrent increase in urinary nephrin excretion. ABT-627 prevented glomerular nephrin loss in hyperglycaemic rats (n = 5-8 rats per group; eight groups).

CONCLUSIONS/INTERPRETATION

These observations support the hypothesis that endothelin-1, via the ET(A) receptor, directly increases P(alb), possibly via nephrin loss, as well as early inflammation in the hyperglycaemic rat.

Resistance to low-dose aspirin therapy among patients with acute coronary syndrome in relation to associated risk factors

BACKGROUND

A substantial proportion of patients have recurrence of vascular events despite daily intake of low-dose aspirin therapy. Therefore, different patients may require different aspirin dosages to achieve complete inhibition of platelet function.

OBJECTIVE

The aim of this work was to measure the response to low-dose aspirin therapy (150 mg/day) among patients with unstable angina or non-ST-segment elevation myocardial infarction and to find out whether titrating aspirin dosage to 300 mg/day, would provide a better therapeutic response in the resistant cases. Moreover, we also aimed to study any association between aspirin non-responsiveness and atherothrombotic risk factors.

METHODS

The antiplatelet effect of 150 mg/day aspirin was studied prospectively in 50 consecutive patients with unstable angina or non-ST-segment elevation myocardial infarction. Platelet aggregation was measured using optical platelet aggregometry and serum thromboxane B(2) level. Aspirin resistance was defined as collagen (1 μg/mL) and adenosine diphosphate (ADP) (5 μmol/L)-induced platelet aggregation of ≥ 40% when compared with control values. Twenty healthy age- and sex-matched individuals were taken as a control group. All patients were subjected to complete medical history (risk factors, medications), thorough clinical examination, ECG, coronary angiography and laboratory investigations including: complete haemogram, coagulation, kidney, liver and lipid profiles, fasting blood glucose and glycated haemoglobin (HbA(1C) ).

RESULTS

Eleven of 50 patients (22%) were found to be aspirin resistant. A highly significant difference was found between the mean values of ADP, collagen-induced platelet aggregation percentage and thromboxane B(2) level after aspirin 150 mg/day when compared with the corresponding mean values after aspirin 300 mg/day among the resistant patients (66 ± 7.01%, 62 ± 4.34% and 620 ± 64.58 pg/mL, respectively, vs. 26.87 ± 2.85%, 16.5 ± 3.8% and 77 ± 11.3 pg/mL) indicating enhanced response to aspirin after escalating the dose. The presence of atherothrombotic risk factors (hypertension, smoking, family history of ischaemic heart disease and previous MI) were not statistically different between aspirin-resistant and aspirin-sensitive patients. However, there was a highly significant difference between the aspirin sensitive and the resistant patients regarding the other risk factors (diabetes mellitus and dyslipidaemia) (P < 0.01).

CONCLUSION

There is inter-individual variability in response to the antiplatelet effect of standard doses of aspirin (150, 300 mg/day). The response to aspirin 300 mg/day is enhanced in resistant patients when compared to 150 mg/day. There was a significant association between aspirin resistance and atherothrombotic risk factors (diabetes, hyperlipidaemia and obesity).

Nanoparticle doped organic-inorganic hybrid photorefractives

The gain characteristics of liquid crystal photorefractive cells doped with ferroelectric nanoparticles has been measured. The liquid crystal two beam coupling gain is found to reverse in sign and increase in magnitude through the addition of ferroelectric BaTiO(3) nanoparticles, yielding gain coefficients up to 1100 cm(-3) in the Bragg regime. We attribute the novel effects of gain reversal and magnitude increase to interactions between the ferroelectric particles' spontaneous polarization and the local liquid crystal flexopolarization.

Stimulated photorefractive backscatter leading to six-wave mixing and phase conjugation in iron-doped lithium niobate

The generation of multiple waves during near-oblique incidence of a 532 nm weakly focused beam on photorefractive iron-doped lithium niobate in a typical reflection geometry configuration is studied. It is shown that these waves are produced through two-wave coupling (self-diffraction) and four-wave mixing (parametric diffraction). One of these waves, the stimulated photorefractive backscatter produced from parametric diffraction, contains the self-phase conjugate. The dynamics of six-wave mixing and its dependence on crystal parameters, angle of incidence, and pump power are analyzed. What we believe to be a novel order analysis of the interaction equations provides further insight into experimental observations in the steady state. The quality of the backscatter is evaluated through image restoration, interference experiments, and visibility measurement. Reduction of two-wave coupling may significantly improve the quality of the self-phase conjugate.

Major improvements of the photorefractive and photovoltaic properties in potassium niobate

Optical and electrical measurements have been made on a new codoped potassium niobate crystal (KNbO3:Fe,Ag) that yields a significant enhancement of the photorefractive and photovoltaic effects when compared with the published results for singly doped potassium niobate crystals. The codoped Ag impurity enters the K site, rather than the typical Nb site, thus changing the local field in the lattice. It is believed that Fe perturbed by the Ag in the K site is responsible for an enhancement of the linear absorption and photocurrent, as well as a probable increase in the effective trap density. An enhanced trap density is likely the cause of the increased photorefractive counterpropagating two-beam coupling efficiency.

A clinico-radiological study of the contralateral ear in acquired unilateral cholesteatoma

OBJECTIVE

Clinico-audiological and CT scan assessments of the contralateral ear in patients with unilateral cholesteatoma can be a good predictive method for the fate of these ears.

MATERIAL AND METHODS

Fifty patients with unilateral cholesteatoma and 25 control subjects with bilateral normal ears were subjected to otomicroscopical and audiological assessment. Axial and coronal computed tomography (CT) for the mastoid bone at 1 mm slice thickness was done for all ears. A simplified method was used to find out the surface area (SA) of the air cells at each individual section and semi-automatically calculate the total volume of the matstoid air cells.

RESULTS

Otomicroscopically, 72% of the contralateral ears showed signs of retraction pockets, granulation tissues and other signs of chronicity. Audiologically 20% of the control ears showed moderate to severe conductive hearing loss while 10% showed mixed hearing loss. As regards mastoid pneumatization, the mean air cell volumes were 6.1, 12.68 and 29.92 CC in cholesteatomatous, contralateral and control ears respectively. This indicates a highly significant difference in the mean air cell volume between the control ears and the other two groups.

CONCLUSION

It can be concluded that continuous follow up of the contralateral ear in cholesteatomatous ears is mandatory to detect subtle pathological changes and manage them early. Volumetry of contralateral ear using the applied simple method can lead to a reduction in major surgery and can affect the choice of the surgical approach.

Contra-directional two-beam coupling by use of a single input beam in an iron-doped lithium niobate multimode fiber

Experimental results are presented for 1,800 contra-directional two-beam coupling (TBC) measurements in a single crystal fiber of LiNbO8:Fe using a single incident beam and its Fresnel reflection off the back surface of the fiber. To our knowledge, this is the first time that volume gratings have been written in a fiber using this beam coupling geometry. At small f-numbers, the TBC efficiency has been predicted to decrease in bulk LiNbO3:Fe due to the erasure of the weak gratings by the dark conductivity. We present experimental results validating the published theory and show experimentally that confinement of the interfering beams in a fiber geometry overcomes this limitation.

Chemomorphic analysis of malathion in skin layers of the rat: implications for the use of dermatopharmacokinetic tape stripping in exposure assessment to pesticides

The dermatopharmacokinetic (DPK) method of dermal tape stripping may prove to be a valuable addition to risk assessment protocols for toxic substances as it has been for the assessment of bioequivalence and bioavailability of topical dermatologic drugs. The measurement of drug penetration into stratum corneum (SC) with respect to time is thought to be comparable with drug distribution in underlying tissues. To examine this possibility, the dermal penetration and absorption characteristics of [(14)C]malathion in the Sprague-Dawley rat was examined by three analytical techniques. [(14)C]Malathion was applied in different vehicles for 30-min and 1-h periods of exposure. Penetration into the SC was assessed by tape stripping followed by instant electronic autoradiography (IEA). Also, the (14)C activity retained in three successive 16 microm sections of the skin application site was determined by IEA and malathion was identified by Fourier transform infrared microscopy (FTIR microscopy). Absorbed [(14)C]malathion was measured in selected tissues, organs, and the residual carcass by liquid scintillation counting (LSC). Penetration into the SC followed a linear trend. The capacity of the SC reservoir for malathion amounted to approximately 1% of the dermal dose, while approximately 6% of the dose was absorbed. Results from this study support the view that LSC remains the method of choice to efficiently and reliably quantify absorption of a radiolabeled test substance. IEA offers the ability of the user to visualize the extent and profile of dermal absorption. When IEA is combined with FTIR microscopy, an effectual tool for studying the penetration of chemicals into layers of the skin emerges. The combined use of the three analytical techniques can be used to test the validity of the DPK method in hazard evaluation and exposure assessment of the organophosphorus insecticides.

Synthesis and antiviral evaluation of n-glycosides derived from 6-amino-3-aryl-2-methyl-4-(3h)-quinazolinones

Reaction of monosaccharides (D-glucose. D-galactose, D-xylose or L-arabinose) with 6-amino-3-aryl-2-methyl-4-(3H) quinazolinones (1a-c) in boiling methanol yielded the corresponding N-glycopyranosides 3a-c, 4a-c, 5a,b and 6a,b. The N-glycopyranosides 3a-c, 4a-c, 5a,b and 6a,b were acetylated with acetic anhydride and pyridine to give the corresponding acetate derivatives 7a-c, 8a-c, 9a,b and 10a,b. The structures of all these glycosides were assessed by elemental analysis, IR, NMR and mass spectra. Some of these products were tested for anti-cancer and anti-AIDS activity.

Socioclinical profile of children with asthma in Al-Majmaah Health Province

OBJECTIVE

Although asthma in children constitutes a major health problem, there is a dearth of literature on different aspects of asthma in rapidly developing countries. This cross-sectional research aims to study the socioclinical profile of asthmatic children and the impact of asthma symptoms on their life style.

METHODS

The sample of this study, drawn from pediatric clinics of a general hospital and primary health care centers during a period of six months, comprised of children under 13 years of age who met the operational diagnostic criteria for asthma. The data collected from multiple sources on a semistructured questionnaire was analyzed by using different statistical tests.

RESULTS

The results showed that male children represented 69% of the sample and children under one year of age manifested significantly severe degree of asthma. The frequency of asthma symptoms decreased in most of the studied children with increasing age. Further, they have insignificant family history of asthma (48.5%) but a significant smoking at home in severely affected children (59%). Moreover, most of them (88%) were mainly characterized by a combination of asthmatic symptoms of variable severity that adversely affected their sleep pattern and significantly resulted in school absences and increased days stay in hospital.

CONCLUSION

The revealed socioclinical profile of studied children with asthma has adverse impact on certain components of their life style, which shows the need for re-activating relevant treatment modalities including health education and changing certain habits like parental smoking at home, which adversely affects asthma.

Monitoring Wadi El Raiyan lakes of the egyptian desert for inorganic pollutants by ion-selective electrodes, ion chromatography, and inductively coupled plasma spectroscopy

Wadi El Raiyan is a great depression located southwest of Cairo in the western desert of Egypt, one of the most arid regions of the world. In 1973, Wadi El Raiyan was connected with the agricultural wastewater drainage system of the El Faiyum province to provide a reservoir for the wastewater that exceeded the capacity of Lake Qarun north of the province. Pollutants from agricultural waste including pesticides and fertilizers as well as other effluents of industrial activities and runoffs certainly will pass into the biotic elements of the ecosystem. This report presents the status of inorganic pollutants including anions, cations, and trace metals in the two lakes and the surrounding springs of Wadi El Raiyan using ion chromatography, ion-selective electrodes, and inductively coupled plasma emission spectroscopy. The report also includes the levels of selected metals in the vegetation community of the area. The result of this investigation revealed a great improvement in water quality of the Wadi El Raiyan lakes compared to 1988 report by Saleh et al. Mercury was not detected in any of the samples and the level of lead was significantly reduced. Cadmium levels were much higher than those seen earlier. The higher level of cadmium might be used as an indicator to track the contamination of water by human waste. Concentrations of common anions were not significantly different from those reported earlier. However, an increase in the level of cyanide was observed. Levels of heavy metals in vegetation around the lakes were also found to be lower than previously reported.

Backbone dipoles generate positive potentials in all proteins: origins and implications of the effect

Asymmetry in packing the peptide amide dipole results in larger positive than negative regions in proteins of all folding motifs. The average side chain potential in 305 proteins is 109 +/- 30 mV (2. 5 +/- 0.7 kcal/mol/e). Because the backbone has zero net charge, the non-zero potential is unexpected. The larger oxygen at the negative and smaller proton at the positive end of the amide dipole yield positive potentials because: 1) at allowed phi and psi angles residues come off the backbone into the positive end of their own amide dipole, avoiding the large oxygen; and 2) amide dipoles with their carbonyl oxygen surface exposed and amine proton buried make the protein interior more positive. Twice as many amides have their oxygens exposed than their amine protons. The distribution of acidic and basic residues shows the importance of the bias toward positive backbone potentials. Thirty percent of the Asp, Glu, Lys, and Arg are buried. Sixty percent of buried residues are acids, only 40% bases. The positive backbone potential stabilizes ionization of 20% of the acids by >3 pH units (-4.1 kcal/mol). Only 6.5% of the bases are equivalently stabilized by negative regions. The backbone stabilizes bound anions such as phosphates and rarely stabilizes bound cations.

Impact of health education program on knowledge about AIDS and HIV transmission in students of secondary schools in Buraidah city, Saudi Arabia: an exploratory study

BACKGROUND

Accurate information about acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) is important for their prevention.

OBJECTIVES

This study is intended to assess knowledge on AIDS in students of secondary schools in Buraidah City and to measure the effect of a health education program on their knowledge about AIDS in general, modes of HIV transmission and the degree of their misperception about the transmission of the disease through casual contact.

METHODOLOGY

A well-designed health education program using personal communication and visual media techniques was conducted for 483 secondary school students in Buraidah secondary schools during the year 1997. Pre- and post-tests were done to examine their knowledge about AIDS.

RESULTS AND RECOMMENDATIONS

The results of this study pointed out that a health education program on AIDS for students of secondary schools greatly and significantly improved their scores on general knowledge on AIDS views on its transmission and misperception of AIDS (p < 0.01). Continuous in-ice programs for secondary students are recommended.

Analysis of metal pollutants in the Houston Ship Channel by inductively coupled plasma/mass spectrometry

Trace metal pollutants in the surface water of the Houston Ship Channel were determined using inductively coupled plasma/mass spectrometry (ICP/MS). Metal concentrations varied according to sampling sites. Barium, cobalt, chromium, molybdenum, silver, beryllium, antimony, lead, and mercury concentrations were relatively similar throughout the channel averaging 83.25, 0.55, 6. 31, 6.66, 0.02, 0.017, 3.61, 0.68, and 0.055 microg/L, respectively. Titanium, manganese, copper, zinc, nickel, and selenium concentrations were found to be higher at stations closer to the Galveston Bay (as the water is turning from relatively fresh water to sea water) with concentration ranges of 102.5-351.7, 0.3-25, 0. 3-25, 30-280, 16-77, 6.2-26.5, and 0.0-6.2 microg/L, respectively. Aluminum was found to be much higher at the Buffalo Bayou station (341 microg/L) followed by the San Jacinto station (104 microg/L) with an average of 42 microg/L in the other two stations. Vanadium was found to be unusually high at the Washburn Tunnel station (116 microg/L) and at much lower concentrations in the other three stations, averaging 6.5 microg/L. Iron was also higher at the Buffalo Bayou station (143 microg/L) but was absent at the Lynchburg Ferries station. Arsenic was not found at the Lynchburg and San Jacinto stations. However, arsenic had similar concentrations of 1. 983 and 1.835 microg/L at Buffalo Bayou and Washburn Tunnel, respectively. Cadmium was higher at the Lynchburg Ferries station (3. 3 microg/L) and ranged from 0.3 to 0.96 microg/L in the other locations. Thallium was not found in any of the stations.

Efficacy of single-dose intramuscular Ceftriaxone for treatment of acute otitis media in children

Full text is available as a scanned copy of the original print version.

Penetration of household insecticides through different types of textile fabrics

Six different types of fabrics were compared for their ability to protect against human exposure to three different commercial household aerosol insecticides. Fabrics used in this investigation were, 100% cotton, cotton-polyester thermal underwear, cotton-polyester blend (twill), 100% acrylic, 100% wool and artificial silk (rayon). The household insecticides were, Black Flag (Ant and Roach Killer), Raid (Ant and Roach Killer) and Hot Shot (Wasp and Hornet Killer) containing propoxur, permethrin/pyrethrins and chlorpyrifos/allethrins as their active ingredients respectively. A fluorescent tracer, 4-methyl-7-diethyl amino coumarin was mixed with the aerosol (or equivalent aliquot) and sprayed onto cloth squares fitted on Whatman paper patches. The percentage of penetration through the cloth was quantified by the intensity of the fluorescence spectrum of each patch extract and the amount of the tracer recovered was calculated. The extract was concentrated to 1/10th of the volume to measure the content of each of the insecticides by supercritical fluid chromatography (SFC) using electron capture (ECD) and diode array detectors. Scanning electron microscope (SEM) images of the fabrics showed the geometry of the yarn. The results obtained from the fluorescence spectra, SFC and SEM showed that cotton-polyester (twill), cotton, wool and cotton thermal underwear were the least penetrable materials for the aerosols. On the other hand, acrylic and artificial silk (rayon) were the most penetrable cloth types.

Determination of the distribution of malathion in rats following various routes of administration by whole-body electronic autoradiography

The distribution of [14C]-malathion, an organophosphorus pesticide, in rats after intravenous, oral and dermal administration was carried out using electronic autoradiography of whole body sections of treated animals. The study indicated that a major difference in the disposition of [14C]-malathion occurred following various routes of administration to rats. Following intravenous administration, the liver and kidney accumulated extremely high levels of the chemical. After oral administration, [14C]-malathion absorption from the stomach was slow and its excretion followed mostly the fecal route. Dermal application of [14C]-malathion may represent a high risk for exposure to the organophosphorus pesticide where the entire skin, not only the site of application, may act as reservoir for the compound.

Use of biplane transesophageal echocardiography as the only imaging technique for percutaneous balloon mitral commissurotomy

Percutaneous balloon mitral commissurotomy with the Inoue technique was attempted in 9 patients with rheumatic mitral stenosis under the sole guidance of biplane transesophageal echocardiography and was completed in 8 patients. This preliminary experience points to the feasibility and relative safety of performing percutaneous balloon mitral commissurotomy under the sole guidance of biplane transesophageal echocardiography.

Regional distribution of lead in human milk from Egypt

Bioaccumulation of lead during chronic exposure and its mobilization and secretion with mother's milk constitute a serious health hazard to the newly born children. Lead levels in human breast milk of 120 Egyptian women representing 20 different governorates throughout Egypt were determined using a graphite furnace Atomic Absorption spectrometer. According to the daily permissible intake (DPI) value established by the WHO of 5.0 micrograms/kg/d in mother's milk, the mean values of lead were around the permissible level in most of the Egyptian governorates. However, lead levels in mother's milk from Alexandria, Assiut and Cairo were significantly higher than the permissible value. Higher lead levels in mother's milk from these governorates may be attributed to heavy automobile traffic using leaded gasoline in addition to the use of lead water pipelines in these areas.

Pattern of pediatric upper gastrointestinal disease: a teaching hospital experience

During the period 1983-1993, 166 pediatric patients(91 females and 75 males) were subjected to upper gastrointestinal endoscopy. Epigastric pain or heart burn and vomiting were the indications in 115 (69%) patients. Gastritis. duodenitis, and esophagitis were diagnosed in 63 (38%), and duodenal ulcer in seven (4.2%) patients. Bleeding sites were identified in 10 out of 21 (47.6%) patients with a history of hematemesis. Helicobacter pylori was identified in 12 (48%) of 25 patients with chronic gastritis. Endoscopic removal of foreign bodies (FB) was required in nine patients. Endoscopic small bowel biopsy provided sufficient material to con-firm the diagnosis in seven out of 13 patients with chronic diarrhea. Endoscopic findings were normal in 78 (47%) patients. The procedure was safe and well tolerated.

Binding of aluminum to human serum transferrin, human serum albumin and rat serum proteins

Human serum transferrin (HSTF), human serum albumin (HSA) and rat serum were compared for their interaction with AlCl3, in a Tris-HCl buffer solutions (pH 7.4). The AlCl3 was tested in series of concentrations in the range of 50 microM up to 500 microM. HSTF, HSA and their 1:1 mixture and rat serum were incubated at 37 degrees C with series of AlCl3 concentrations. The protein profile of the incubated solutions were compared to control using SDS-PAGE and FPLC tests. The results indicated that HSTF was more specifically responsive to AlCl3 showing a characteristic increase in its UV absorption, peak and area dimensions. Simultaneously, HSA was less affected, but it showed a significant shift with an increase in molecular weight accompanied with a change in its profile. The respective bands of transferrin and albumin in rat serum behaved similarly. The SDS-PAGE and FPLC data coincided and confirmed the preferential affinity of HSTF to bind with Al3+. These results support the suggestion of using HSTF for monitoring levels of Al3+ in human blood samples of exposed population. The importance of further developing such a biomarker is the increased demand for early detection of the hazardous levels of Al3+ in relation to its long term neurotoxic adverse effects.

Gamma aminobutyric acid radioreceptor-assay a possible biomarker for human exposure to certain agrochemicals

Cyclodiene insecticides, hexachlorocyclohexanes, pyrethroids, bicyclophosphates, the bicycloorthocarboxylate insecticides and some of their metabolites and environmental degradation products are central nervous system toxicants with high specific binding affinity to the chloride channel of the gamma-aminobutyric acid (GABA)A receptor-ionophore sites. [35S] tertiary-butylbicyclophosphorothionate (TBPS) with specific activity higher than 60 Ci/mmole has a high binding affinity to the same sites and is now commercially available and can be used to label the GABAA receptor for the development of a radioreceptor assay technique. The GABA receptor was prepared by ultra centrifugation and dialysis of brain homogenates of either cow, goat, rat or catfish. The receptor was then labeled with [35S] TBPS and the assay was conducted by measuring the displacement of radioactivity following incubation with samples containing the analytes. A radioreceptor assay protocol was developed to measure the amount of the alpha-endosulfan in blood samples. The assay was extremely sensitive, and can detect 0.2 nM of endosulfan at a level equivalent to 0.08 ppb or 8 x 10(-11) gm of endosulfan in each ml of the blood samples.

Aluminum interaction with human brain tau protein phosphorylation by various kinases

Phosphorylation is an indispensable process for energy and signal transduction in biological systems. AlCl3 at 10 nM to 10 microM range activated in-vitro [gamma-32P]ATP phosphorylation of the brain (tau) tau protein in both normal human or E. coli expressed tau forms; in the presence of the kinases P34, PKP, and PKC. However, higher concentrations of ALCl3 inhibited the tau phosphorylation with P34, PKP, and PKC to a maximum at 1 mM level. AlCl3 at 100 microM to 500 microM range induced non-enzymatic phosphorylation of tau with gamma-ATP, gamma-GTP, and alpha-GTP. AlCl3 activated histone phosphorylation by P34 in a similar pattern. The hyperphosphorylation of tau by Al3+ was accompanied by molecular shift and mobility retardation in SDS-PAGE. This may demonstrate the mechanism of the longterm neurological effect of Al3+ in human brain leading to the formation of the neurofibrillary tangles related to Alzheimer's disease.

Malathion disposition in dermally and orally treated rats and its impact on the blood serum acetylcholine esterase and protein profile

14C-methoxy-malathion with either pure or 50% E.C. formulated malathion were applied orally or dermally at one tenth of their LD50 to two batches of male albino rats. More than 90% of 14C was released with urine after 24 hours. The rest of 14C was detected in the feces, blood, intestines, liver and kidney in a descending order. No significant 14C was detected in other organs. Comparing the oral pure and formulated malathion treatments, there was no significant variation in the rate of disposition or excretion of 14C-malathion. However, the dermal treatment revealed that the 14C-formulated malathion was released faster than the pure one in urine in the first 24 hours; while the 14C-pure malathion showed relatively higher levels in the feces and blood in the first 24 hours. In a third batch of male albino rats, the effect of the same level of dermal treatment by either pure or 50% E.C. formulated malathion on serum acetylcholine-esterase (A. Ch. E.) activity and serum protein profile was studied. The serum A. Ch. E. activity was found to be inhibited to 40% activity after 6 to 24 hours for both treatments. However, after 96 hours the serum of the pure malathion treated rats showed full recovery of A.Ch.E. activity, while the formulated malathion treated showed only 60% activity. The SDS-PAGE analysis showed a differentiation in the serum protein bands of the 48 hours exposed rats to formulated malathion which was confirmed by the scanned gel profile. The FPLC integrated chromatograms proved an initiation of a new protein band accompanied with rearrangement of the albumin and pre-albumin bands. Thus it can be concluded that, the impact on the blood serum protein profile and A. Ch. E. activity can be used as reliable criteria to detect acute toxicity of malathion and other choline-esterase inhibitors in exposed field workers. Further research is needed to elucidate the specificity and sensitivity of such criteria as biomarkers for human exposure.

Identification and quantitative determination of chlorinated pesticides

Identification and Quantitative determination of complex mixtures of chlorinated hydrocarbon pesticides and their metabolites usually require highly expensive analytical instruments and highly trained personnel. The present work describes a simplified procedure for analysis of these mixtures involving a combination of marker dye TLC and capillary column GLC.

Mutagenic and carcinogenic effects of pesticides

A discussion of the mutagenic and carcinogenic effects of various classes of commonly used pesticides. Classes discussed include halogenated hydrocarbons organophosphorus insecticides, and certain herbicides and fungicides. Halogenated hydrocarbons were found generally hazardous, causing sterility and displaying marginal or definite carcinogenic activity. Several organophosphorus insecticides have been shown to be mutagens; some have been shown to be carcinogens. Both the herbicide impurity tetrachlorodibenzodioxin, TCDD, and maleic hydrazide have been shown to be carcinogenic in mice and rats. The role of DNA as a critical target for carcinogenic activity is also discussed.

Toxaphene, a complex mixture of polychloroterpenes and a major insecticide, is mutagenic

Toxaphene, the most widely used chlorinated insecticide, is mutagenic in the Salmonella test without requiring liver homogenate for activity. This insecticide is a complex mixture (more than 177 polychloroterpenes) with carcinogenic activity in rodents. Some but not all of the mutagenic components are easily separated from the insecticidal ingredients.

Polychlorobornane components of toxaphene: structure-toxicity relations and metabolic reductive dechlorination

2,2,5-endo,6-exo,8,9,10-Heptachlorobornane and four derivatives of this heptachlorobornane, with an additional chlorine atom at position 3-exo,8,9, or 10, account for a major portion of the acute toxicity of toxaphene and for up to 23 percent of toxaphene composition as analyzed by open tubular column gas-liquid chromatography with an electron capture detector. Both in several organisms and model environmental systems and on photolysis, this heptachlorobornane undergoes facile reductive dechlorination at the geminal-dichloro group and sometimes dehydrochlorination.