Cadmium resisting bacteria in Alexandria Eastern Harbor (Egypt) and optimization of cadmium bioaccumulation by Vibrio harveyi

Cadmium resisting bacteria (CRB) were present in all water and sediments (samples) collected from Alexandria Eastern Harbor, Egypt. The occurrences of CRB in sediments samples were higher than in water samples and reached up to 77.22% of total counts. Five isolates were selected to be the most resistant to cadmium with minimal inhibitory concentration of 60 ppm. The most potent isolate that accumulates a maximum Cd2+ concentration of 23.3 mg Cd2+/ g dry cells was identified as Vibrio harveyi. Medium components affecting metal removal by V. harveyi were explored based on the application of Plackett-Burman design. The growth of V. harveyi in the optimized culture conditions, recorded cadmium biosorption of 1.52 fold increase. Immobilized living cells of V. harveyi on hazelnut shells increased the uptake of cadmium to 49.35 mg Cd2+/g dry cells and removal efficiency up to 84%. Transmission electron microscope study confirmed the accumulation of Cd2+ by V. harveyi cells.Key words: Cadmium resisting bacteria, Vibrio harveyi, bioaccumulation, Plackett-Burman design

Optimization, economization and characterization of cellulase produced by marine Streptomyces ruber

Cellulase is a very important enzyme due to its great industrial applications. Six marine strains of actinomycetes were screened for their carboxymethyl cellulase (CMCase) productivity. Streptomyces ruber was chosen to be the best producing strain. The highest enzyme production (25.6 U/ml) was detected at pH 6 and 40°C after 7 days of incubation. Plackett-Burman design was applied to optimize the different culture conditions affecting enzyme production. Results showed that a high concentration of KH2PO4, and a low concentration of MgSO4 had a significant effect on enzyme production. Rice straw was used as a low cost source of cellulose. It was found that 30 g/l rice straw was the suitable concentration for maximum enzyme production. Partial purification of cellulase enzyme using an anionexchange chromatography resulted in the detection of two different types of CMCases, type I and II, with specific activity of 4239.697 and 846.752 U/mg, respectively. Moreover, estimation of their molecular weight revealed 27.0 kDa for cellulase type I and 24.0 kDa for cellulase type II. It could be concluded that S. ruber is a powerful cellulase producer strain under our tested experimental conditions.Key words: Cellulase production, Streptomyces ruber, Plackett-Burman design, rice straw, enzyme characterization

Development of 137

In this work, 137Cs irradiation facility at the National Institute of Standards (NIS) was developed to enhance the calibration processes. Different thickness lead sheets were used for beam attenuation, to enlarge the 137Cs dose range. Ambient dose equivalent rate, H*(10) was measured using two ionization chambers at a different source-detector distances (SDDs) and a lead sheet thickness. The deviation from the inverse square law for the dose–SDD relationship was obtained. The beam flatness of unattenuated and the lead attenuated beam was measured. The attenuation coefficient for the used lead sheets was obtained and correlated to the broad beam geometry. The room scattering was studied in detail. The uncertainty of the measured doses was calculated. It was found that the inverse square law is verified well at SDD ≥ 2 m. The measured attenuation coefficient for lead attenuators is affected by the broad beam geometry. The contribution of the scattering component of the dose at a certain SDD is the major source of uncertainty since it extracted a value of 1.05%, while the combined uncertainty from all other factors affecting the dose measurements is 1.34%

Corneal collagen cross-linking in patients with keratoconus associated with dry eye

Purpose The aim of this study was to assess the safety and efficacy of corneal collagen cross-linking in keratoconus associated with dry eye. Patients and methods This study included 35 eyes of 29 patients diagnosed as having keratoconus associated with moderate dry eye manifestations (as measured by Schirmer 1 test result of 8-4 mm after 5 min). Moreover, 12 keratoconic eyes were also included in this study without any manifestations of dry eye as a control group (as measured by Schirmer 1 test result of ≥15 mm after 5 min). All eyes were subjected to preoperative and postoperative assessments including uncorrected visual acuity, best-corrected visual acuity, pachymetry, simulated keratometry, and corneal topography. The thinnest corneal thickness was at least 400 μm in all eyes. As mentioned before, the degree of preoperative dry eye was assessed using Schirmer 1 test. Epithelium-on cross-linking technique was used. All data were analyzed and recorded. Results The results of ‘epithelium-on’ collagen cross-linking are variable, but its noninvasive nature makes it potentially useful in cases when epithelium debridement is better to be avoided, such as in patients with dry eyes. In our study, there was a remarkable improvement regarding postoperative uncorrected visual acuity and best-corrected visual acuity (one line or more). There was no statistical significant difference between the results among dry eyes and nondry eyes. Average K readings showed a marked reduction reaching more than 2 D. The mean astigmatism showed unremarkable changes. The main central corneal thickness showed marked corneal thinning with reduction in the corneal thickness of ∼50 μm or more in many eyes. Conclusion This study showed no significant difference in efficacy and safety of corneal collagen cross-linking among eyes with keratoconus either associated with dry eye or not

Assessment of posterior corneal surface changes after photorefractive keratectomy in moderate myopia

Aim The aim of this work was to study the changes that occur in the posterior corneal surface after photorefractive keratectomy (PRK) in moderate myopia using pentacam. Patients and methods This prospective study included 30 myopic eyes of 17 patients with spherical equivalent −2.00–6.00 D who underwent PRK using Visx S4 Excimer Laser. Pentacam examination was carried out for all our eyes at preoperatively, and 1 week and 3 months postoperatively. Pentacam was used to compare preoperative and postoperative measurements of the anterior and posterior corneal curvatures, and asphericity of the posterior corneal surface. Results This study included 30 myopic eyes of 17 patients, seven women and 10 men. Patients’ ages ranged from 28 to 40 years; the mean age was 30.3±3.03 years. No statistically significant changes were found in the posterior horizontal corneal curvature. A statistically significant change in the posterior vertical corneal curvature from 6.1±0.3 to 6.06±0.2 mm 1 week after PRK was found, but it increased after 3 months to 6.2±0.3 mm. No statistically significant changes in the posterior mean corneal curvature were observed either at 1 week or 3 months after PRK. A significant change in the Q-value (asphericity) was found both at 1 week and 3 months postoperatively. Conclusion After PRK, changes in the posterior corneal surface affect mainly the vertical curvature asphericity with forward elevation of the posterior corneal surface

Contrast sensitivity in β-thalassemic patients

Aim of work This work aimed to diagnose any abnormalities in contrast sensitivity and retinal functions in β-thalassemic patients. Patients and methods Thirty patients diagnosed with b-thalassemia were included in this study. Detailed assessment of history and full ophthalmological examination were performed for all our cases. Contrast sensitivity and electroretinogram were performed for all our cases. Results Thirty β-thalassemic patients were included in this study. The mean age of the patients was 37 years; most of our patients were women. The main presenting symptoms were discomfort in night vision. Contrast sensitivity was significantly low in all our cases and electroretinogram showed low scotopic visual sensitivity in 23 cases. Conclusion Ophthalmic follow-up in β-thalassemic patients is mandatory

Fast-neutron spectroscopy studies using induced-proton tracks in PADC track detectors

In this work, a simple and adequate method for fast-neutron spectroscopy is proposed. This method was performed by free-in-air fast-neutron irradiation of CR-39 Nuclear Track Detectors (NTD) using an Am-Be source. Detectors were then chemically etched to remove few layers up to a thickness of 6.25 μm. By using an automatic image analyzer system for studying the registration of the induced-proton tracks in the NTD, the obtained data were analyzed via two tracks shapes. In the first one, the elliptical tracks were eliminated from the calculation and only the circular ones were considered in developing the response function. In the second method all registered tracks were considered and the corresponding response function was obtained. The rate of energy loss of the protons as a function of V[(dE/dX) - V] was calculated using the Monte Carlo simulation. The induced-proton energy was extracted from the corresponding dE/dX in NTD using a computer program based on the Bethe-Bloch function. The energy of the incident particles was up to few hundred MeV/nucleon. The energy of the interacting neutrons was then estimated by means of the extracted induced-proton energies and the scattering angle. It was found that the present resulting energy distribution of the fast-neutron spectrum from the Am-Be source was similar to that given in the literature where an average neutron energy of 4.6MeV was obtained

Development of

In this work, 137Cs irradiation facility at the National Institute of Standards (NIS) was developed to enhance the calibration processes. Different thickness lead sheets were used for beam attenuation, to enlarge the 137Cs dose range. Ambient dose equivalent rate, H*(10) was measured using two ionization chambers at a different source-detector distances (SDDs) and a lead sheet thickness. The deviation from the inverse square law for the dose–SDD relationship was obtained. The beam flatness of unattenuated and the lead attenuated beam was measured. The attenuation coefficient for the used lead sheets was obtained and correlated to the broad beam geometry. The room scattering was studied in detail. The uncertainty of the measured doses was calculated. It was found that the inverse square law is verified well at SDD ≥ 2 m. The measured attenuation coefficient for lead attenuators is affected by the broad beam geometry. The contribution of the scattering component of the dose at a certain SDD is the major source of uncertainty since it extracted a value of 1.05%, while the combined uncertainty from all other factors affecting the dose measurements is 1.34%

The association between Chlamydia trachomatis ln late pregnancy and the development of premature rupture of membranes (PROM)

Background: Premature rupture of membrane (PROM) is considered an important cause of perinatal morbidity and mortality with increased maternal and neonatal risks. The etiology of PROM is known to be multifactorial, however, genital infections such as Chlamydia trachomatis is a possible contributing factor to its occurrence. The aim of this study was to assess the incidence rate of Chlamydia trachomatis infection in pregnancy and its role in the etiology of PROM. Methods: Two groups of patients were included; study and control groups. The study group included twenty full term pregnant women with the diagnosis of recent premature rupture of membranes with a duration of less than twelve hours while the control group included ten normal cases having the same criteria but with intact membranes. All patients were admitted to El Shatby Maternity University Hospital and an informed written consent was taken. Serum samples were collected in red top vacutainer for all women to detect Chlamydia trachomatis Immunoglobulin M (IgM) and Immunoglobulin G (IgG). In addition, endocervical swabbing was performed to detect Chlamydia trachomatis antigen using ELISA technique. Results: The study showed no significant association between PROM and Chlamydia trachomatis infection. However, the prevalence of Chlamydia trachomatis cervicitis in women with PROM was higher as compared to the control group; 45% compared to 20% by chlamydial antigen. Conclusion: The fact that this infection statistically increases the risk of PROM could not be confirmed