Optimizing magnetic, dielectric, and antimicrobial performance in chitosan-PEG-Fe2O3@NiO nanomagnetic composites

There is a growing interest in eco-friendly and cost-effective organic-inorganic nanocomposites due to their alignment with the principles of "green" chemistry, as well as their biocompatibility and non-toxicity. This study focused on producing Chitosan-PEG-Fe2O3@NiO nanomagnetic composites to improve the stability, dielectric properties, and antimicrobial effectiveness of these nanocomposite materials. The process involved synthesizing Fe2O3@NiO via sol-gel and polymerizing chitosan-PEG. The nanocomposites were characterized by XRD, TEM, FTIR, optical, dielectric, and VSM. Incorporating Fe2O3@NiO significantly improved stability, and the interaction with Fe2O3 during the sol-gel process facilitated the formation of NiFe2O4 with an increase in the crystallinity within the chitosan-PEG matrix. The study examined optical and dielectric properties, highlighting that the 3 NiO-doped chitosan-PEG-Fe2O3 composites had high electrical conductivity (1.8 ∗ 10-3 S/cm) and a significant dielectric constant (106 at low frequencies). As the ratio of NiO NPs within the chitosan-PEG-Fe2O3 increases, the energy band gap of chitosan-PEG-Fe2O3 films decreases up to 3.7 eV. This decrease is owing to the quantum confinement effect. These composites also demonstrated improved antimicrobial activity against E. coli and S. aureus and higher activity in the presence of nanomagnetic particles. The minimum inhibitory concentrations of CS-PEG-Fe2O3/NiO NPs against (Bacillus cereus, M. luteus, S. aureus and (S. enterica, H. pylori, E. coli) were (22-35 mm) and (21-34 mm), respectively.

Exploring nanoarchitectonics and optical properties of PAA-ZnO@BCP wide-band-gap organic semiconductors

This work reports the formation of polyacrylic acid (PAA)-zinc oxide (ZnO)-bromocresol purple (BCP), (PAA-ZnO@ (0.00-0.01) BCP wide-bandgap organic semiconductors deposited onto glass substrates via a sol-gel polymerization process. These semiconductor films were deposited on glass substrates using a spin coating and then dried at 60 °C. The PAA-ZnO film appeared to be of amorphous phase, and films loaded with BCP revealed semicrystalline behavior. The surface of the films exhibited adherence and extended grains. The hydrogen bonds formed between PAA-ZnO and the BCP dye within the PAA-ZnO@BCP films was performed using FTIR-spectroscopy. The prepared nanocomposites demonstrate an indirect band transition which is affected slightly by adding ZnO and BCP dye. Optical parameters such as the absorption coefficient, the refractive index, the dielectric constant, optical conductivity, optical depth, and optical electronegativity of the prepared nanocomposites were studied as functions of incident light energy (wavelength). The PAA carbonyl group n-π* transition and BCP aromatic ring π-π* transitions were detected at about 285 (for all samples) and 432 nm (for BCP loaded samples), respectively. The superior photoluminescence characteristics observed in the BCP/PAA-Zn films excited with a wavelength of 250 nm indicated the successful loading of the BCP dye during the self-aggregation of the PAA-Zn film.

Advancing energy storage and supercapacitor applications through the development of Li+-doped MgTiO3 perovskite nano-ceramics

Perovskite oxide materials, specifically MgTiO3 (MT) and Li-doped MgTiO3 (MTxLi), were synthesized via a sol-gel method and calcination at 800 °C. This study explores the impact of varying Li doping levels (x = 0, 0.01, 0.05, and 0.1) on the crystalline structure and properties of MgTiO3. X-ray diffraction analysis revealed a well-defined rhombohedral MgTiO3 phase. Optical diffuse reflectance measurements provided insights into energy gap values, refractive index, and dielectric constant. Li+ doping enhanced the electrical properties of MgTiO3, with a notable phase transition observed at 50 °C. The study investigated impedance and AC conductivity under varying temperature and frequency conditions (25-120 °C, 4 Hz to 8 MHz). Electrochemical analysis through cyclic voltammetry and electrochemical impedance spectroscopy confirmed highly electrocatalytic properties for MTxLi, particularly when modified onto screen-printed electrodes. This work not only advances the understanding of Li-doped MgTiO3 nanostructures but also highlights their significant potential for direct electrochemical applications, particularly in the realm of energy storage.

Humidity sensing using Zn(1.6 - x)Na0.4CuxTiO4 spinel nanostructures

In this paper, we present a humidity sensing material based on nanostructured Zn(1.6 - x)Na0.4CuxTiO4 spinel to enhance optical and sensitivity performance. Nano-porous of Zn (1.6 - x) Na0.4CuxTiO4 spinel were synthesized using sol gel reactions and calcined at 700 °C. The nanostructures of Zn(1.6 - x)Na0.4CuxTiO4 spinel underwent thorough characterization through multiple techniques. X-ray diffractometry (XRD) coupled with Rietveld refinement using FullProf software, transmission electron microscopy (TEM), Raman Spectroscopy, and optical analysis were employed to assess various aspects of the nanostructures. These techniques were utilized to determine the phase composition, particle size distribution, chemical bonding, and the tunable band gap of the nanostructures. The X-ray diffraction (XRD) analysis of Zn(1.6 - x)Na0.4CuxTiO4 samples revealed well-defined and prominent peaks, indicating a highly crystalline cubic spinel structure. The lattice parameter was decreased from 8.4401 to 8.4212 Å with increasing Cu content from 0 to 1.2 mol%. UV-visible diffuse reflectance spectra were employed to investigate the optical characteristics of copper-doped Zn1.6Na0.4TiO4. The applicability of Cu@NaZT spinel nanostructures in humidity sensors was evaluated at ambient conditions. The fabricated sensor was investigated in a wide span of humidity (11-97%). The examined sensor demonstrates a low hysteresis, excellent repeatability, fast response and recovery. The response and recovery times were estimated to be 20 s and 6 s respectively. The highest sensitivity was achieved at 200 Hz. The proposed sensor can be coupled easily with electronic devices as the humidity-impedance relationship is linear.

Synthesis and characterization of chitosan-corn starch-SiO2/silver eco-nanocomposites: Exploring optoelectronic and antibacterial potential

This work discusses the physicochemical and antimicrobial characteristics of chitosan-corn starch eco-nanocomposites integrated with silica@Ag nano-spheres. These composites were synthesized through sol-gel polymerization and subsequently exposed to simulated body fluid (SBF). The incorporation of Ag into the eco-nanocomposites led to a decrease in diffuse reflectance across the entire wavelength range. The dielectric permittivity exhibited an increase up to 52.1 at a frequency of 100 kHz, while the ac conductivity reached a value of 5.2 ∗ 10-6 (S cm-1) at the same frequency for the sample with the highest Ag content. The study utilized XRD and FTIR techniques to examine the materials before and after in vitro testing and evaluated the antibacterial properties of the eco-nanocomposites against several pathogenic microorganisms, including Staphylococcus haemolyticus, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli, using the agar diffusion method. The eco-nanocomposites demonstrated bioactivity by forming a hydroxy appetite layer on their surfaces and were capable of releasing silver (Ag) at concentrations of 1.3, 1.9, and 2.5 mol%. This study suggests that chitosan-corn starch-SiO2-based doped with Ag eco-nanocomposite has the potential for various applications, including biomedical and environmental fields, where their antibacterial properties can be utilized to combat harmful microorganisms.

Construction and characterization of nano-oval BaTi0.7Fe0.3O3@NiFe2O4 nanocomposites as an effective platform for the determination of H2O2

Talented di-phase ferrite/ferroelectric BaTi₀.₇Fe₀.₃O₃@NiFe₂O₄ (BFT@NFO) in oval nano-morphology was chemically synthesized using controlled sol-gel processes and calcined at 600 °C. The effects of shielding using NiFe₂O₄ (NFO) nanoparticles on the microstructure, phase transition, thermal, and relative permittivity of BaTi₀.₇Fe₀.₃O₃ (BTF) nano-perovskite were systematically explored. X-ray diffraction patterns and Full-Prof software exhibited the forming of the BaTi₂Fe₄O₁₁ hexagonal phase. TEM and SEM images demonstrated that the coating of BaTi0.₇Fe₀.₃O₃ has been successfully controlled with exquisite nano-oval NiFe₂O₄ shapes. The NFO shielding can significantly promote the thermal stability and the relative permittivity of BFT@NFO pero-magnetic nanocomposites and lowers the Curie temperature. Thermogravimetric and optical analysis were used to test the thermal stability and estimate the effective optical parameters. Magnetic studies showed a decrease in saturation magnetization of NiFe₂O₄ NPs compared to their bulk system, which is attributed to surface spin disorder. Herein, characterization and the sensitive electrochemical sensor were constructed for the evaluation of peroxide oxidation detection using the chemically adjusted nano-ovals barium titanate-iron@nickel ferrite nanocomposites. Finally, The BFT@NFO exhibited excellent electrochemical properties which can be ascribed to this compound possessing two electrochemical active components and/or the nano-ovals structure of the particles which can further improve the electrochemistry through the possible oxidation states and the synergistic effect. The result advocates that when the BTF is shielded with NFO nanoparticles the thermal, dielectric, and electrochemical properties of nano-oval BaTi_0.7Fe_0.3O₃@NiFe₂O₄ nanocomposites can be synchronously developed. Thus, the production of ultrasensitive electrochemical nano-systems for the determination of hydrogen peroxide is of extensive significance.

Silencing of tissue factor by antisense deoxyoligonucleotide mitigates thioacetamide-induced liver injury

BACKGROUND

Retinoid receptors (RRs), RAR-α and RXR-α, work as transcription factors that regulate cell growth, differentiation, survival, and death. Hepatic stellate cells (HSCs) store retinoid and release its RRs as lipid droplets upon their activation.

PURPOSE

We test the hypothesis that loss of retinoid receptors RAR-α and RXR-α from HSCs is dependent on tissue factor (TF) during thioacetamide (TAA)-induced liver injury.

METHODS

Liver toxicity markers, TF, fibrin, cleaved caspase-3, and cyclin D1 as well as histopathology were investigated.

RESULTS

Increased TF, fibrin, cleaved caspase-3, and cyclin D1 protein expression is seen in zone of central vein after TAA injection compared with vehicle-treated mice. A strong downregulation of RAR-α and RXR-α is seen in TAA-induced liver injury. In addition, histopathological obliteration and pericentral expression of cleaved caspase 3 and cyclin D1 are observed after TAA injection compared with the normal vehicle-treated mice. No changes have been seen in TAA/TF-sense (SC) in whole parameters compared with TAA-treated animals. TAA/TF-antisense (AS)-treated mice show normal expression of all parameters and normal histopathological features when compared with the control mice. In conclusion, this study declares that the strong downregulation of RAR-α and RXR-α may cause liver injury and particularly activation of HSCs in TAA-induced toxicity. TF-AS treatment not only downregulates TF protein expression but also alleviates loss of liver RAR-α and RXR-α and suppresses the activated apoptosis signals in TAA-induced liver toxicity. Finally, TF and RAR-α/RXR-α are important regulatory molecules in TAA induced acute liver injury.

Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

A stable Sr₄Fe₆O₁₃ was prepared as small crystallites by auto-combustion of a sol-gel in air followed by annealing the later at pertinent temperatures. A green sample, as annealed at elevated temperatures, yields a single Sr₄Fe₆O₁₃ phase of tailored magnetic properties. The structural, morphological, magnetic and electrical properties were investigated by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer, and broadband dielectric spectrometer. Hard magnetic Sr₄Fe₆O₁₃ properties arise with saturation magnetization M_s = 12.4 emu/g, coercivity H_c = 3956.7 Oe and squareness 0.512. Studies made at low temperatures reveals M_s decreasing on increasing temperature from 17.5 emu/g at 85 K down to 12.4 emu/g at 305 K, while H_c rises from 1483 Oe at 85 K to 1944 Oe at 305 K. The ac-conductivity follows the Jonscher relation. The dc-conductivity at high temperatures/low frequencies exhibits a plateau and it depends linearly on a characteristic frequency according to the Barton-Nakajima-Namikawa) relation.

Genetic investigation of 93 families with microphthalmia or posterior microphthalmos

Microphthalmia is a developmental eye defect that is highly variable in severity and in its potential for systemic association. Despite the discovery of many disease genes in microphthalmia, at least 50% of patients remain undiagnosed genetically. Here, we describe a cohort of 147 patients (93 families) from our highly consanguineous population with various forms of microphthalmia (including the distinct entity of posterior microphthalmos) that were investigated using a next-generation sequencing multi-gene panel (i-panel) as well as whole exome sequencing and molecular karyotyping. A potentially causal mutation was identified in the majority of the cohort with microphthalmia (61%) and posterior microphthalmos (82%). The identified mutations (55 point mutations, 15 of which are novel) spanned 24 known disease genes, some of which have not or only very rarely been linked to microphthalmia (PAX6, SLC18A2, DSC3 and CNKSR1). Our study has also identified interesting candidate variants in 2 genes that have not been linked to human diseases (MYO10 and ZNF219), which we present here as novel candidates for microphthalmia. In addition to revealing novel phenotypic aspects of microphthalmia, this study expands its allelic and locus heterogeneity and highlights the need for expanded testing of patients with this condition.

Heterogeneity of Campylobacter species isolated from serial stool specimens of Egyptian children using pulsed field gel electrophoresis

BACKGROUND

The genus Campylobacter spp. is a common cause of human acute bacterial enteritis and travellers' diarrhoea worldwide.

OBJECTIVE

To determine whether multiple serial isolations of Campylobacter spp., when obtained from a single child, represented the same or a different organism.

METHODS

In a birth cohort study conducted in Egypt, numerous children showed serial isolations of Campylobacter spp. Of these, 13 children were selected from different households based on the successive isolation of six or more Campylobacter isolates from stool samples.

RESULTS

Eighty isolates were recovered and identified as either Campylobacter coli (n = 25) or Campylobacter jejuni (n = 55). Pulsed-field gel electrophoresis (PFGE) revealed the presence of 38 unique C. jejuni and 24 C. coli profiles at a similarity level of ≥ 90%. Although no serially-identical isolates were detected in six children, others demonstrated at least one identical couple of isolates; all identified serially between one to six weeks. Two children demonstrated > 80% similar couples of isolates that appeared seven months apart. PFGE could be a useful tool for differentiating reinfection, relapse and convalescent excretion phases.

CONCLUSION

Our data suggest that Campylobacter infection in children is a complex process; children are exposed to multiple species in endemic environments and strains of the same bacterium appear to be shed serially between one to six weeks after the first exposure. Isolates that persisted for longer periods were relatively less similar, as shown from the results of this study.

Enteric viral infections as potential risk factors for intussusception

Introduction:  We aimed to identify potential risk factors for intussusception (ISS) among children presenting to two pediatric hospitals in Egypt. Methodology: In this case-control study,  enrolled children < 3 years old with ISS (confirmed radiologically and/or surgically) were  matched by age and gender to controls admitted with acute non-abdominal surgical illnesses. Stool samples were collected and tested for various enteric bacteria, rotavirus, enteric adenoviruses (EA, 40 and 41) and astroviruses using commercially available ELISA diagnostic kits. Results: From December 2004 to May 2009, 158 cases and 425 matched controls were enrolled. A history of diarrhoea and cough over the preceding four weeks of interview were more common in cases than controls, respectively. Children with mothers who had secondary education and above were 2.2 times more likely to have ISS than those whose mothers had a lower level of education. In spite of the low detection rate of EA infection (regardless of diarrhoea history) and asymptomatic rotavirus infection, they were detected in higher frequencies in cases than controls; however, infection with astrovirus and bacterial pathogens did not appear to be associated with increased risk of ISS. Conclusions: History of diarrhoea and cough over the four weeks preceding the study and maternal education above secondary level were potential risk factors for ISS. EA and asymptomatic rotavirus infection were detected in higher frequencies among cases than controls; however, association with ISS cannot be confirmed. Additional research is needed to confirm these findings and evaluate the pathogenesis which may link such infections with ISS.

Burden of Aeromonas hydrophila-associated diarrhea among children younger than 2 years in rural Egyptian community

INTRODUCTION

Between 2004 and 2007, a birth cohort of Egyptian children was analysed to evaluate the epidemiology of enteric diseases.

METHODOLOGY

A stool sample was collected from the study children every two weeks as well as whenever they experienced diarrhea. Samples were tested for routine bacterial pathogens as well as enteropathogenic viruses and parasites. A secondary goal of the study was to evaluate the burden of less commonly reported pathogens including Aeromonas hydrophila.

RESULTS

Of the 348 study subjects, 79 had A. hydrophila isolated from their stool at some point during the study.  Thirty-six children had exclusively symptomatic (S) infections while 33 had exclusively asymptomatic (AS) infections. However, 10 children had both S and AS infections. Among symptomatic cases, A. hydrophila was the sole pathogen isolated 36% of the time. An important aspect of A. hydrophila associated diarrhea was the high level of resistance to cephalosporins.

CONCLUSION

Although relatively uncommon, A. hydrophila was found to be associated with diarrhea among children living in Egypt and was frequently multi-drug resistant.

Treatment of inflamed pterygia or residual pterygial bed

AIMS

To describe the use of subconjunctival bevacizumab or ranibizumab, an approved antivascular endothelial growth factor for wet macular degeneration, in halting the inflammation of a pterygium or a partially excised pterygium.

METHODS

Case reports.

RESULTS

Prompt regression of conjunctival microvessels in the pterygial bed was documented 1 week after a single subconjunctival injection of ranibizumab (one case) or bevacizumab (two cases). No side-effects were noted over 13 months of follow-up in the first case, 6 months in the second case and 1 month in the third case.

CONCLUSION

Selective blockade of vascular endothelial growth factor was effective in causing regression of conjunctival microvessels in three eyes with inflamed pterygium or residual pterygia.

Isolation of cryptococcus, Candida, Aspergillus, Rhodotorula and nocardia from meningitis patients in egypt

Meningitis occurs throughout Egypt and is largely attributed to bacterial pathogens, but there is little information on fungal etiologies of meningitis. We, therefore, investigated fungal infections among Egyptian patients with acute and subacute meningitis who tested negative for bacterial and viral agents. A total of 1000 cerebrospinal fluid (CSF) samples collected from nine governorates of Egypt during 1998-2002 were initially stained with Gram's, India ink, and lacto-phenol cotton-blue stains, and examined under light microscope to detect fungal elements. All CSF samples were cultured on brain heart infusion, Wickerham and Staib agar media for fungus isolation. CSF with suspected Cryptococcus neoformans infections were also tested by latex agglutination test for antigen detection. Species identification of selected isolates was carried out at the Mycotic Diseases Branch, CDC, Atlanta, Georgia, USA. Fungal agents were detected microscopically and by culture in 17 of 1000 (1.7%) CSF samples tested. Ten of 17 were identified as C. neoformans var grubii (serotype A), 4 as Candida albicans, and one each of Aspergillus candidus, Rhodotorula mucilaginosa (rubra) and Nocardia spp (actinomycetes). Out of the 17 cases with fungal CSF infection, 8 died (Cryptococcus-3, Candida-2, Aspergillus, Rhodotorula and Nocardia) and 2 suffered neurological sequelae. Of the 10 cryptococcal meningitis patients, 4 were HIV positive and one was diagnosed with lymphoma. To our knowledge, this is the first study on isolation of fungi other than Cryptococcus from CSF of Egyptian patients with acute/subacute meningitis. Consideration must now be given to cryptococcosis and candidiasis as potential etiologies of meningitis in Egypt.

Heartworm and Wolbachia: therapeutic implications

A safer, more effective adulticidal treatment and a safe method for reducing microfilaremia and breaking transmission of heartworm disease early in the treatment are needed. The present study evaluated efficacy of ivermectin (IVM) and doxycycline (DOXY) alone or together (with or without melarsomine [MEL]) in dogs with induced adult heartworm infection and assessed the ability of microfilariae from DOXY-treated dogs to develop to L3 in Aedes aegypti mosquitoes and subsequently to become reproductive adults in dogs. Thirty beagles were each infected with 16 adult heartworms by intravenous transplantation. Six weeks later, dogs were ranked by microfilarial count and randomly allocated to 6 groups of 5 dogs each. Beginning on Day 0, Group 1 received IVM (6 mcg/kg) weekly for 36 weeks. Group 2 received DOXY (10 mcg/(kgday)) orally Weeks 1-6, 10-11, 16-17, 22-25, and 28-33. Groups 3 and 5 received IVM and DOXY according to doses and schedules used for Groups 1 and 2. At Week 24, Groups 3 and 4 received an intramuscular injection of MEL (2.5 mg/kg), followed 1 month later by two injections 24h apart. Group 6 was not treated. Blood samples were collected for periodic microfilaria counts and antigen (Ag) testing (and later immunologic evaluation and molecular biology procedures). Radiographic and physical examinations, hematology/clinical chemistry testing, and urinalysis were done before infection, before Day 0, and periodically during the treatment period. At 36 weeks, the dogs were euthanized and necropsied for worm recovery, collection of lung, liver, kidney, and spleen samples for examination by immunohistochemistry and conventional histological methods. All dogs treated with IVM + DOXY (with or without MEL) were amicrofilaremic after Week 9. Microfilarial counts gradually decreased in dogs treated with IVM or DOXY, but most had a few microfilariae at necropsy. Microfilarial counts for dogs treated only with MEL were similar to those for controls. Antigen test scores gradually decreased with IVM + DOXY (with or without MEL) and after MEL. Antigen scores for IVM or DOXY alone were similar to controls throughout the study. Reduction of adult worms was 20.3% for IVM, 8.7% for DOXY, 92.8% for IVM + DOXY + MEL, 100% for MEL, and 78.3% for IVM + DOXY. Mosquitoes that fed on blood from DOXY-treated dogs had L3 normal in appearance but were not infective for dogs. Preliminary observations suggest that administration of DOXY+IVM for several months prior to (or without) MEL will eliminate adult HW with less potential for severe thromboembolism than MEL alone.

Long-term follow-up in Bietti crystalline dystrophy

PURPOSE

To present a long-term follow-up of Bietti crystalline dystrophy.

METHODS

Two brothers are presented including the clinical findings, fluorescein angiography, electrophysiology (electroretinography [ERG], electrooculography [EOG], adaptometry), optical coherence tomography (OCT), and transmission electron microscopy of bulbar conjunctiva and peripheral blood lymphocytes. The clinical findings were documented over a period of 25 years in one brother and 5 years in the other.

RESULTS

The most striking features were deposits in the retina that were formed de novo with old ones replaced by choroidal atrophy in advanced stage of the disease. The light rise (EOG), rod- and cone-driven responses (ERG), and visual fields were affected progressively during the course. These changes of the retinal pigment epithelium and choriocapillaris were observed in the second decade and worsened gradually. OCT demonstrated preferential crystal accumulation in the inner retina. Cytoplasmic lipid crystalline inclusions were found in lymphocytes and conjunctival fibroblasts by transmission electron microscopy.

CONCLUSIONS

Bietti crystalline retinopathy is a progressive retinal disease characterized by retinal crystals gradually replaced by atrophy of the retinal pigment epithelium and gradual constriction of visual fields.

Radiologic findings in infected and noninfected scleral buckles

PURPOSE

To present the radiologic findings in scleral buckle infections and in the early postoperative period after scleral buckling.

METHODS

Retrospective multicenter orbital computed tomography (CT) study of 14 patients and brain magnetic resonance (MR) in one patient with scleral buckle infections, some with the referring diagnosis of endophthalmitis, proliferative vitreoretinopathy, orbital cellulitis, or unilateral headache. The control population consisted of early postoperative prospective CT study of 38 consecutive patients with scleral buckle without clinical infection.

RESULTS

Diffuse scleral thickening and preseptal soft tissue swelling were noted in acute scleral buckle infections. Scleral thickening decreased radiologically following prompt antibiotic therapy in five patients with acute infections. Silicone sponge had low attenuation without infection and high attenuation with infection. In chronically infected scleral buckle, the sclera was thickened around the buckle, with scleral melt under the buckle. MR showed increased signal intensity in the preseptal region in one patient with chronic fungal infection. In the controls, two had thickening of the sclera without soft tissue swelling.

CONCLUSIONS

CT or MR can assist in the early diagnosis and management of scleral buckle infections.

Ultrasonic studies on polystyrene/styrene butadiene rubber polymer blends filled with glass fiber and talc

The compatibility of solid blends: PS/SBR, PS/SBR filled with glass fiber and PS/SBR filled with talc were studied using ultrasonic pulse echo technique. Measurements were carried out at room temperature (298 K) and a frequency of 3 MHz. The ultrasonic velocity for the compressional wave and that for shear wave have been measured to obtain the elastic moduli data by knowing of density. The variation of ultrasonic wave velocities and elastic moduli with weight percent of the blend was found to be linear in PS/SBR blend, indicating some degree of compatibility but the drawback of elastic moduli indicate incompatibility of the system blend, while it deviates from linearity in blends of PS/SBR filled with glass fiber and talc but the increase in elastic moduli indicates that there is an increase in degree of compatibility between PS and SBR due to adding of glass fiber or talc. The ultrasonic absorptions for longitudinal wave in the temperature range from 298 to 423 K in the studied system were measured using ultrasonic pulse echo technique. Typical results showing the temperature dependence of the ultrasonic absorption at frequencies of 1, 2, 3 and 5 MHz are illustrated for all samples of the different compositions. The study of compositional and temperature dependence of the ultrasonic absorption in the present studied blends reveals the same behavior of the compatibility degree of the blends. Density data of the blends confirmed the ultrasonic results. Also the correlation between hardness and elastic moduli for the present blend systems has been studied.

Relationship between intracranial granulomas and cerebrospinal fluid levels of gamma interferon and interleukin-10 in patients with tuberculous meningitis

Cerebrospinal fluid gamma interferon (IFN-gamma) and interleukin-10 levels in 39 patients with tuberculous meningitis were serially measured. Cytokine levels did not predict intracranial granuloma (IG) development, but IFN-gamma levels in the top quartile after 1 month of therapy were highly associated (odds ratio = 18) with detection of an IG by computed tomography scanning.

Anterior ischaemic optic neuropathy after coronary artery bypass graft: the role of anaemia in diabetics

PURPOSE

To ascertain factors associated with anterior ischaemic optic neuropathy (AION) following coronary artery bypass graft (CABG) in a Lebanese population.

METHODS

A retrospective chart review of consecutive CABG performed over a 5-year period (1995-1999) in one medical centre. A comparison of clinical characteristics was carried out between AION cases and subjects free from AION. The variables analysed included history of diabetes as well as preoperative, intraoperative, or postoperative values of haematocrit, blood sugar, oxygen saturation, and arterial blood pressure.

RESULTS

A total of 1,594 persons were included. Three subjects experienced acute visual loss from AION following CABG, all had diabetes mellitus, and two suffered from severe postoperative anaemia. Among diabetics (n=484), the risk of AION was significantly higher in subjects with postoperative haematocrit falling below 22 (28.6%) than the rest (0.21%) (P=0.001). Blood transfusion was given in two subjects with prompt visual recovery.

CONCLUSIONS

Severe anaemia in patients undergoing CABG appears to be a risk factor for AION, especially in diabetics, and needs prompt correction to prevent or reverse the ischaemic ocular events.

Periocular corticosteroids in diabetic papillopathy

PURPOSE

To ascertain the therapeutic effect of periocular corticosteroids in diabetic papillopathy.

METHODS

Prospectively, five consecutive adult-onset diabetic patients with symptomatic diabetic papillopathy underwent visual fields and fluorescein angiography before and after superonasal subtenon injection of corticosteroids.

RESULTS

The median duration of papillopathy was 2.5 weeks by ophthalmoscopy and 3 weeks by fluorescein angiography. The median recovery time of best-spectacle-corrected visual acuity was 2 weeks. Two patients developed sequential diabetic papillopathy, and both reported faster visual recovery and better subjective vision in treated eyes. In these two patients, the final best-spectacle-corrected visual acuity and visual evoked responses were comparable between the two eyes, while automated visual fields were less constricted in treated eyes. Complications included ocular hypertension, mild progression of cataract, and mild ptosis in one patient each.

CONCLUSIONS

Periocular corticosteroids shortened the duration of diabetic papillopathy from a reported median of 5 months to 3 weeks in the present uncontrolled observational study, partly by their angiostatic and antioedema effects at the level of the anterior optic nerve. Intraocular pressure needs to be monitored in eyes receiving periocular corticosteroids.

Virus-induced chalazion

PURPOSE

To investigate a viral etiology in certain chalazia.

METHODS

A prospective study over 7.5 years of all newly presenting chalazia associated with diffuse follicular conjunctivitis but without any other aetiological factors. Patients were investigated for ocular or systemic infections by history, physical exam, slit-lamp exam, and/or histology of conjunctival biopsy (including transmission electron microscopy).

RESULTS

A total of 27 patients developed follicular conjunctivitis without meibomian gland dysfunction, blepharitis, or sexually transmitted diseases. Evidence for a viral aetiology included: recent systemic viral illness (15/27), recent contact with subjects with chalazia or follicular conjunctivitis (5/27), preauricular lymphadenopathy (4/27), viral corneal disease (4/27), or viral particles by ultrastructure (4/4).

CONCLUSIONS

Chalazia may be associated with viral conjunctivitis. Intralesional corticosteroids should be considered with great caution for viral-induced chalazia.

Sapheno-femoral Junction Reflux in Patients with a Normal Saphenous Trunk

OBJECTIVE

To determine the patterns and clinical importance of saphenofemoral junction (SFJ) reflux in patients with chronic venous disease (CVD) and a normal great saphenous vein (GSV) trunk.

METHODS

Fifteen hundred consecutive patients were examined using duplex ultrasound (DU) in three centres. Patients with reflux involving the SFJ and/or its tributaries only were included and its prevalence and patterns were studied. Patients with GSV trunk reflux or in any other veins were excluded. The SFJ diameter was categorised as normal, dilated or varicose. The results of surgery were evaluated by DU in 42 patients 1 year after the procedure.

RESULTS

SFJ area incompetence with a competent GSV trunk occurred in 8.8% of limbs. It was significantly more common in CEAP class 2, 13.6% compared to class 3, 8.2% (p=0.03), class 1, 2.7%, class 4, 4.4% and classes 5 and 6 together, 1.5% (p<0.001 for all). The SFJ had a normal diameter in 21%, dilated in 62% and varicose in 17%. Reflux was seen in 39% of limbs with a normal SFJ diameter, in 85% of those with a dilated SFJ and in all varicose SFJs. Of the 42 operated limbs, 27 had ligation and division of the SFJ and tributary phlebectomies. Fifteen had tributary phlebectomies only, leaving the SFJ intact. At one-year follow-up, SFJ area reflux was found in six limbs (14.3%), involving the SFJ alone in 1, a main tributary in 1 and 4 small tributaries. No reflux was found in the GSV trunk. All but two of the 42 patients were satisfied with the results.

CONCLUSIONS

SFJ reflux with tributary involvement and sparing of the GSV trunk occurs in 8.8% of CVD patients. Such reflux is found in the entire spectrum of CVD, but it is more common in class 2. Local surgery with or without SFJ ligation has very good results at 1 year. DU scanning prior to treatment is important in all patients so that the intact GSV can be spared.

Ocular pathology in congenital heart disease

PURPOSE

To describe the ocular findings in subjects with congenital heart disease (CHD).

METHODS

In a prospective study, the same observer examined 240 consecutive patients with CHD admitted to the medical centre. Two independent geneticists performed identification of syndromes.

RESULTS

The commonest anatomic cardiac anomalies were ventricular or atrial septal defects (62), tetralogy of Fallot (39), pulmonary stenosis (25), and transposition of the great arteries (24). The heart lesions were divided physiologically into volume overload (90), cyanotic (87), and obstructive (63). In all, 105 syndromic subjects included the velocardiofacial syndrome (18), Down's syndrome (17), CHARGE association (6), DiGeorge syndrome (5), Williams syndrome (3), Edwards syndrome (3), Noonan syndrome (3), VACTERL association (2), and Patau syndrome (trisomy 13) (2). The paediatric team recognized 51 patients as syndromic. Two independent geneticists recognized additional 54 patients as syndromic. Positive eye findings were present in 55% (132) and included retinal vascular tortuosity (46), optic disc hypoplasia (30), trichomegaly (15), congenital ptosis (12), strabismus (11), retinal haemorrhages (8), prominent eyes (7), and congenital cataract (6). There was a strong correlation between the retinal vascular tortuosity and both a low haematocrit (P=0.000) and a low arterial oxygen saturation (P=0.002).

CONCLUSIONS

Patients with CHD are at a high risk for ocular pathology and need screening for various ocular abnormalities.

Deep venous reflux and incompetent perforators: significance and implications for therapy

Objectives: To define the significance of perforator and deep vein pathology in patients with chronic venous disease (CVD).

Methods: Consecutive patients with CVD were referred for venous evaluation (group A). Both saphenous veins and all the deep veins including those in the calf area were evaluated. A separate group of patients with deep venous reflux and/or obstruction was identified from our database and analysed separately (group B). The CEAP classification (clinical, aetiological, anatomical and pathological) was used to grade the clinical severity of CVD.

Results: Age, duration of disease and history of thrombosis increased significantly with disease severity ( P <0.02). Reflux in the superficial veins was the most common pathology in group A and it was present in 75% of limbs in group B. The overall contribution of deep venous disease was 26% in group A and it increased significantly with the severity of disease in both groups. Isolated deep vein disease in group A was significantly less compared with group B (8% vs 23%, P<0.0001). Reflux in deep veins of post-thrombotic limbs was significantly longer compared with those with primary disease. The prevalence of incompetent perforator veins was higher in patients with skin damage from both groups. No patient had isolated perforator vein reflux. Reflux was the most common pathology in both groups, while obstruction alone was rare. Other than superficial reflux, which is very common, ipsilateral recurrent deep venous thrombosis (DVT), combined reflux and obstruction, and popliteal vein reflux were the strongest predictors for development of skin damage.

Conclusions: Perforator and deep vein involvement increases significantly with the severity of CVD. Isolated deep vein disease in post-thrombotic limbs is more common than in consecutive venous patients. Reflux is the most common pathology and obstruction alone is rare. In post-thrombotic limbs, the most important predictors for skin damage are ipsilateral recurrent DVT, popliteal vein reflux and a combination of reflux and obstruction.

Rapid diagnosis of typhoid fever by enzyme-linked immunosorbent assay detection of Salmonella serotype typhi antigens in urine

We developed and evaluated an enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies to capture somatic antigen 9 (O9), flagellar antigen d (Hd), and the Vi capsular polysaccharide antigen (Vi) from the urine of persons with and without typhoid fever. Sequential urine samples were collected from 44 patients with blood culture-confirmed typhoid fever and from two control groups. The first control group included patients with brucellosis (n = 12) and those with clinically diagnosed, non-typhoid, acute, febrile illness (n = 27). The second control group was a sample of healthy volunteer laboratory workers (n = 11). When assessed relative to date of fever onset, sensitivity was highest during the first week for all three antigens: Vi was detected in the urine of nine (100%) patients, O9 in 4 (44%) patients, and Hd in 4 (44%) patients. Sequential testing of two urine samples from the same patient improved test sensitivity. Combined testing for Vi with O9 and Hd produced a trend towards increased sensitivity without compromising specificity. The specificity for Vi exceeded 90% when assessed among both febrile and healthy control subjects, but was only 25% when assessed among patients with brucellosis. Detection of urinary Vi antigen with this ELISA shows promise for the diagnosis of typhoid fever, particularly when used within the first week after fever onset. However, positive reactions for Vi antigen in patients with brucellosis must be understood before urinary Vi antigen detection can be developed further as a useful rapid diagnostic test.

Ocular findings in aplastic anemia

OBJECTIVE

To analyze the ocular findings in aplastic anemia.

DESIGN

Eighteen patients with aplastic anemia were examined.

RESULTS

Ocular findings included cotton wool spots (38%), nerve fiber layer or preretinal hemorrhages (67%), vitreous hemorrhages (13%), a picture resembling central retinal vein occlusion (13%) and optic disk edema (6%). Preretinal hemorrhages were the presenting sign of aplastic anemia in 2 patients (13%).

CONCLUSIONS

A blood profile is needed in patients with unexplained retinal hemorrhages. Patients with aplastic anemia need to avoid ocular massage and Valsalva maneuvers to decrease ocular morbidity.

Antimicrobial agent resistance in bacterial isolates from patients with diarrhea and urinary tract infection in the Sudan

Antimicrobial sensitivity tests were performed on four-hundred and ninety-seven bacterial isolates from Sudanese patients with diarrhea or urinary tract infections. Shigella dysenteriae type I and enteropathogenic Escherichia coli showed high resistance rates (percentage of isolates showing antibiotic resistance) against the commonly-used antimicrobial agents: ampicillin, amoxicillin, chloramphenicol, tetracycline, cotrimoxazole, nalidixic acid, sulfonamide, and neomycin, and were completely sensitive to ciprofloxacin. Eighteen resistance patterns against nine antimicrobial agents tested were observed in enteric pathogens. Resistance to ampicillin, amoxicillin, tetracycline, cotrimoxazole, and sulfonamide was the most frequent pattern. The common urinary pathogens, E. coli, Klebsiella pneumoniae, and Proteus mirabilis showed high rates of resistance to ampicillin, amoxicillin, cotrimoxazole, tetracycline, sulfonamide, trimethoprim, streptomycin, and carbenicillin. We recommend that physicians seek updated knowledge of the common antibiotic-sensitivity patterns when starting empirical antibiotic therapy in Sudanese patients with diarrhea or urinary tract infection.

Isolated amyloidosis of anterior uvea and trabecular meshwork

Amyloid deposition in the iris is rare, scanty and associated with systemic disease. We present a case of isolated localized heavy amyloid infiltration of the iris and describe a new hillock-pattern feature visualized using scanning electron microscopy.

Premacular Subhyaloid Hemorrhage Following Laser in situ Keratomileusis

PURPOSE

To report a case of premacular subhyaloid hemorrhage following laser in situ keratomileusis (LASIK).

METHODS

Case report.

RESULTS

The subhyaloid hemorrhage did not resolve over 1 month of observation, necessitating Nd:YAG posterior hyaloidotomy.

CONCLUSION

The LASIK procedure can be associated with postoperative subhyaloid hemorrhage, presumably from rapid release of the microkeratome vacuum pressure.

Lens minibar to facilitate refraction

PURPOSE

To describe a lens minibar that facilitates refraction.

METHODS

Ten lenses of 1-diopter increment were glued to form a hyperopic minibar (range from +1.00 to +5.00) and a myopic minibar (range from -1.00 to -5.00), the size of a credit card.

RESULTS

The lens minibar allowed expedited refraction in children and in consultations that took place outside the clinic.

CONCLUSION

The lens minibar is an inexpensive, small, lightweight tool that facilitates quick refraction.

Ocular sequelae of pneumatic drills

PURPOSE

To determine the ocular sequelae of rock-drilling.

METHODS

Nineteen rock-drillers and 20 age-, sex- and race-matched control subjects underwent ocular examination in a prospective manner.

RESULTS

Subepithelial corneal opacities were found in 12 drillers (63%) and none of the controls; pigmented trabecular meshwork was noted in 13 drillers (68%) and 1 control (5%); low-tension glaucoma was diagnosed in 1 driller (5%); vitreous liquefaction was present in 17 of 17 drillers (100%) examined by a retina specialist and 9 of 20 controls (45%).

CONCLUSIONS

The sequelae of drilling include corneal scars from projectile pieces of drilled stone as well as vibration-induced pigment deposition in the trabecular meshwork and vitreous liquefaction. Wearing of safety glasses is recommended.

Surgically induced scleral necrosis

PURPOSE

To present a group of patients with surgically induced scleral necrosis characterised by conjunctival retraction.

METHODS

Three case reports are presented.

RESULTS

The scleral melt responded to conjunctival covering of the scleral defect.

CONCLUSION

Surgically induced scleral necrosis associated with conjunctival retraction is best managed by covering the exposed sclera either by stretching the retracted conjunctiva in the early post-operative period or by a conjunctival transplant.

Comet-tailed drusen of the retinal pigment epithelium in angioid streaks

PURPOSE

To describe a fundus finding in angioid streaks, namely comet-tailed drusen of the retinal pigment epithelium.

METHODS

A review was carried out of fundus photographs in 110 cases of angioid streaks.

RESULTS

Five patients had comet-tailed drusen and the halo tail was radial and parallel to adjacent angioid streaks.

CONCLUSIONS

Comet-tailed drusen may represent zones of minor stress of the retinal pigment epithelium--Bruch's membrane complex compared with zones of major stress as in angioid streaks.

Ethmoid sinus osteoma presenting as epiphora and orbital cellulitis: case report and literature review

Paranasal sinus osteoma is a slow-growing, benign, encapsulated bony tumor that may be commonly asymptomatic, being detected incidentally in 1% of plain sinus radiographs or in 3% of sinus computerized tomographic scans. In a patient presenting with orbital cellulitis and epiphora, computed tomography disclosed a large osteoma of the ethmoid sinus. Excision of the osteoma allowed recovery of vision, return of extraocular muscle function, and resolution of choroidal folds. Proptosis, diplopia, and visual loss are other frequent presenting signs of paranasal osteomas. Epidemiology, diagnosis, treatment, and pathologic findings in paranasal sinus osteoma are reviewed.

Effect of bromocriptine on uterine contractility in near-term pregnant rats

Treatment of pregnant albino rats at gestation day 9 with the dopamine agonist, bromocriptine, in a dose of 0.7 mg kg-1 day-1, i.p. for 11 days produced a significant increase in the normal uterine contractions both in vitro and in vivo. The increase in frequency (F), amplitude (A) and area under the curve (AUC) in the in vitro experiment amounted to 35, 80 and 58%, respectively; while the increase in F and A in the in vivo experiment was 36 and 25%, respectively, in comparison with the corresponding control group. Addition of oxytocin (5x10(-12)-4x10(-11) m) to the uterus isolated from rats pretreated with bromocriptine resulted in marked uterotonic effect (24, 35 and 49% increase in F; 25, 35 and 46% increase in A and 42, 62 and 122% increase in AUC of contractions). Also, the in vivo experiment showed that an injection of oxytocin at the time of investigation (0.125-1.0 I.U. kg-1, i.v.) into rats pretreated with bromocriptine caused a marked increase in F (33, 40 and 81%) and A (33, 37 and 75%) of uterine contractions compared to the values of bromocriptine-treated animals. These results indicate that bromocriptine should be used with caution during pregnancy. In addition, this must be considered when using oxytocin during delivery of females pretreated with bromocriptine.

Optic disk tubercle

The purpose of this case report was to present a rare case of optic disk tubercle. The optic disk edema resolved on antituberculous therapy with recovery of vision. We concluded that visual loss from an optic disk tubercle can be the presenting sign of tuberculosis.

Determination of pseudoephedrine hydrochloride and carbinoxamine maleate in combination drug formulation by liquid chromatography

An isocratic, reversed-phase liquid chromatographic (LC) method was developed for simultaneous determination of pseudoephedrine hydrochloride (I) and carbinoxamine maleate (II) in a pharmaceutical dosage form. Analysis was conducted on a CN column (10 microns), with a mobile phase consisting of acetonitrile-methanol-phosphate buffer (pH 5.3)-water (140 + 170 + 40 + 100) and at a detection wavelength of 262 nm. The method was validated for linearity, precision, system reproducibility, and accuracy. Recoveries at 80-120% of labeled claim ranged from 97.4 to 100.7% and from 98.5 to 100.2% for I and II, respectively. Results were linear (correlation coefficient, r > 0.9995 for I in the range 250-750 micrograms/mL and r > 0.9999 for II in the range 20-60 micrograms/mL.

Effects of interferon gamma on growth, apoptosis, and MHC class II expression of immature rat intestinal crypt (IEC-6) cells

Intestinal epithelial cells and the mucosal immune cells in close proximity are thought to interact very closely. One well-established mechanism of this intercellular cross-talk is via the production of cytokines such as interferon gamma (IFNgamma). The aim of this study was to analyze the effects of IFNgamma on intestinal crypt epithelial cells. IEC-6 cells were cultured in the presence or absence of IFNgamma to measure its effects on proliferation, cell cycle, apoptosis, and major histocompatibility complex (MHC) class II antigen expression. Even at very low doses (0.01 U/ml), IFNgamma significantly inhibited IEC-6 cell proliferation, as demonstrated by reduced 3H-thymidine uptake, stable cell count, and complete arrest in the quiescent G0/G1 phase of the cell cycle. Incubation with supraphysiological doses of IFNgamma (100-1,000 U/ml) did not induce apoptosis, as assessed by morphology and the TUNEL assay. IFNgamma significantly induced de novo IEC-6 class II antigen expression. Tumor necrosis factor alpha (TNF alpha), which alone had no effect, synergistically enhanced this effect of IFNgamma. MHC class II antigen expression was observed to be independent of cell cycle phase. Our results indicate that IFNgamma alters immature crypt epithelial cell turnover and upregulates MHC class II expression. These alterations may be important in the pathogenesis of immune-mediated bowel disorders.