Portal-image IMRT verification

The aim of the present work was to develop and utilizing the use of an amorphous silicon electronic portal imaging device [EPID] in IMRT dosimetric verification. Neither pre-irradiation nor extra build-up materials was needed for EPID dosimetry applications. Accurate absolute dosimetry [output] obtained using the EPID up to 250 cGy with mean deviation of 0.39% and 0.62% while the maximum observed deviation was 0.7% and 1.9% at 250 MUs for 6 and IS MV photon energy respectively. Beam-by-beam fluence profiles obtained from portal images were used in air [i.e. without phantom presence] The EPID estimated the relative dose up to 1.5% accuracy. The in-air absolute dose [i.e. number of MUs] of an arbitrary clinical breast [aperture-based] IMRT test fields were extracted, the difference rose to 1.7% in the most severe tested field. One disadvantage of beam-by-beam verification is that the cumulative effect of dose errors from all beams is not quantified, however, it allows the potential origin of dose errors to be isolated more easily. The EPID could estimate the dose at each segment with average accuracy of around 1% for central axis positions and up to 1.7% for off-axis positions in the tested fields. The absolute dose verification plus the fluence map verification of IMRT fields may represent a sufficient procedure to examine the step-and shoot-IMRT treatment. Multi-leaf-collimator [MLC] related QA also tested using EPED. The mean difference between EPID effective penumbra results and both ion chamber and film measurements was 0.06 and 0.01 cm respectively. These results could justify the use of EPID in dosimetric applications including aperture-based IMRT verification, and quality control programs

MLC leaf position and dynalog file accuracy QA procedure using the EPID

A main concern about the IMRT dose validation tool using Monte Carlo [MC] simulation and R and V-system/Dynalog file is the potential inconsistency between the actual leaf-end positions and those recorded by the Dynalog file. The present study investigates a method to validate the accuracy of the Dynalog tiles using amorphous silicon electronic portal imaging device [aSi-EPID] images. A computer program was developed to detect the MLC segmented field edges in EPID images [l024x768 pixels, pixel size: 0.392 mm], Standard reference MLC segmented fields were designed and leaf-end positions were measured accurately. EPID images for these reference MLC fields were recorded and the leaf-end positions were calculated as the locations where the image intensity is 50% of the maximum. Small corrections were made to minimize the effect of scattered photons [background]. Daily EPII] images of the same MLC segmented fields were compared to the original images and to check the accuracy of the Dynalog files. A daily QA tool was developed to check the accuracy of the Dynalog file and MLC leaf end positions as part of the comprehensive IMRT-QA procedure. This ensures the accuracy of the MC based patient-specific IMRT dose verification using the information recorded in the Reeord and Verify system/Dynalog files

Biochemical study on gastrin, secretin and somatostatin homeostasis in end stage renal failure

Chronic renal failure is a complex disease that is associated with enormous biochemical alterations which induce marked multiorgan dysfunctions. Gastrointestinal disorders are diagnosed occasionally while renal failure is not yet recognized. The specific mechanisms underlying these complaints are not yet completely known. Aim: The present study aimed to assess the circulating state of three major biologically active gut hormones i.e. gastrin, secretin and somatostalin. Their responses to standard test meal and to hemodialysis were also determined The present study was conducted on 20 patients with CRFdue to variable kidney diseases. Of them 10 patients receiving conservative treatment only [Conservative group] and the remaining 10 patients undergoing maintenance hemo-dialysis [hemodialysis group] beside the conservative therapy. Also 12 healthy volunteers were similarly investigated. Plasma total gastrin, secretin and somatostatin [S.S] concentrations beside the routine investigations were determined. In conservative uremic group, fasting and one hour postprandial plasma total gastrin, secretin and somatostatin levels were significantly higher than their corresponding normal control levels: Moreover, test meal induced significant increase in these hormones in both CRF and control groups in comparison to their fasting levels. In hemodialysis uremic patients, plasma total gastrin, secretin and somatostatin concentrations before dialysis were significantly higher than their corresponding levels in the normal control and in conservative uremic groups. Hemodialysis caused significant reduction of the circulating gastrin, secretin and somatostatin concentrations when compared with their plasma concentrations before dialysis. However, in hemodialyzed uremics, unlike plasma gastrin and secretin concentrations, plasma SS concentration before dialysis was not significantly different from the fasting level in CRF patients on conservative therapy. Hypersecretinemia and hypersomatostatinemia were concomitant finding with hypergastrinemia in CRF. Disproprotionate synthesis and release of gastrin, secretin and somatostatin can be explained by impairment of the feedback loops and cross regulations in between these hormones. However, being excreted mainly by kidney, impaired excretion of these hormones is also a possible cause of their high circulating concentrations.

Cardiac and ocular manifestations in Egyptian patients with mucopolysaccharidoses

Cardiac and ocular manifestations were evaluated in 21 patients clinically suspected of mucopolysaccharidosis. After electrophoresis analysis of urinary glycoaminoglycans, 3 patients were excluded because their results did not correlate with any known type of mucopolysaccharidosis. Echocardiography revealed abnormal findings in 11 patients [61.1%]. The mitral valve was the most commonly affected valve; 7 patients [38.9%] had thickened mitral valve and 6 had mitral regurge. Corneal opacities were found in 3 patients [16.7%] and progressive increase in intraocular pressure in 1 patient [5.6%], while fundus examination showed early optic atrophy in 1 patient [5.6%] and bilateral papilloedema in 2 patients [11.1%]

Some factors affecting cellulase production and activity by a thermotolerant aspergillus terreus R -4 from filter mud

The growth and cellulase production by the thermotolerant Aspergillus terreus R-4 grown on filter mud [FM] waste, as the sole carbon source, were optimal when the culture medium was composed of [g/I]: FM, 25; casein, 4; KH[2]PO[4], 2; MgSO[4]. 7H[2]O, 0.5; NaCl, 2. The effect of adding various substrates in presence of FM was examined. The supplementation of glucose [5 g/I] to the fermentation medium stimulated maximal cellulase activity, but higher concentrations of glucose repressed production of cellulases. The optimal conditions for CMCase, FPase and cellobiase were at pH 4.8 and 60°C. The cellulolytic enzymes produced by A-terreus R-4 were stable over a wide range of pH values. Enzyme activity was assayed after exposure to elevated temperatures for 15 min and its thermal stability was determined

Production and properties of cellobiases from immobilized cultures of aspergillus terreus R-4

Cultures of Aspergillus terreus R-4 were immobilized using different supports. The highest cellobiase activity [22.4 U/mg protein] was obtained in alginate entrapped cultures. Optimum alginate concentration and size of bead inoculum were 3% and 10 ml beads/50 ml culture, respectively. Addition of wheat bran or corn steep liquor stimulated the biosynthesis of the enzyme. Alginate beads retained 64% of their activity after 4 reuses. Purification of cellobiase [s] from free [FMC] and immobilized [IMC] cultures was fulfilled by ammonium sulphate precipitation followed by gel filtration on Sephadex G-150 and ion exchange chromatography on CM-Sephadex C50. Two cellobiases were obtained CB[im] II[b][MW 54.3-F:D] from immobilized cultures and CB[f]Ia [MW 72.1 KD] from free cultures. CB[imII][b]and CB[fIa]showed optimum temperature of 65 and 60°C and optimum pH values of 5.2 and 4.8, r-espectively. CB[im] II[b]was more thermostable than CB[f]Ia and both enzymes differed in their amino acid composition. Ca[2], Ba[2+], Na[+]and K[+]ions slightly activated or stabilized both cellobiases. CB[im] I[b]was highly activated by Mn[+]2 and strongly inhibited by Hg[2+]and pdraehioromercuribenzoate, while CBI, was only partially inhibited parachloromercurilbenzoate

Cellulase and single cell protein production by aspergillus niger

The potentiality of 4 isolates of Aspergillus niger, to produce cellulolytic enzymes and single cell protein [SCP] has been studied under static culture conditions using 5 different agricultural and agro industrial cellulosic wastes as a carbon source. Isolate No 1 was selected as the most potent for cellulase and SCP production on using beet pulp. Cellulase activities and SCP production of this isolate were found to be influenced by the type and the age of the fungal culture. Best results were maintained after 4 days using the shaked culture. The beet pulp was pretreated in different manners to increase the cellulase and SCP production by the selected isolate. Milling, as a physical treatment, rendered the beet pulp sample more productive for cellulolytic enzymes and SCP. The cellulase and SCP production were also tested using initially adjusted pH as well as buffered media. Maximal CMCase and FPase activities [0.561 and 0.293 unit/ml respectively] and the highest protein yield [35.7%] with maximum conversion efficiency [55.6%] were obtained at pH 6.0 with the phosphate buffer giving better results as compared with the acetate buffer

Influence of some nutritional factors on cellulase and single cell protein production by aspergillus niger from beet pulp

Production of cellulose and single cell protein [SCP] by Aspergillus niger isolate No I grown on beet pulp [BP] waste, as the sole carbon source, were optimal when the culture medium was composed of [g/I]: BP, 25; NaNO[3]2; MgSO[4],. 7H[2]O, 0.57;K[2]HPO[4], 1. Microelements solution in the cultivation medium did not significantly affect the fermentation activities. On the other hand, supplementation of yeast extract [2g/1] to the medium permitted maximal cellulase and SCP production

Optimization of cellulase production by a thermotolerant aspergillus terreus R4 from filter mud

Seven strains of thermotolerant Aspergillus species were screened for cellulolytic activities. Aspergillus terreus R-4 was selected as the most potent cellulase producer on filter mud [FM], as a new substrate, produced as a by-product in cane sugar industry. CMCase, FPase and cellobiase production were optimal when 10% inoculum was used. The optimum fermentation conditions consist of medium composed of [g11]: FM, 25, NH[4]CI, 2, HKH[2]PO[4]; MgSO[4-], 7H[2]O, 0.5; NaCI, 0.5 at pH 7.0 and incubation period for 7 days under shaking conditions

effect of die relief location and luting cements on the seating and retention of full cast crown

The purpose of this investigation was to evaluate and compare experimentally the effect of the die relief location and cement types on the seating and retention of cemented full cast crowns. The results showed that, the difference between post-cementation and pre- cementation measurements are designed as marginal discrepancies. The mean value for the two coats of die spacer applied are consistent with the thickness of 25 muM reported to be most favorable for improving crown seating. An analysis of the groups showed that occlusal surface relief only neither produce significant reduction in mean marginal discrepancies nor increased tensile force required to remove the cemented full cast crown, compared to control group without die relief. Meanwhile, a statistically significant effect for both marginal discrepancies at P <0.001 and values of tensile strength at P = 0.001 was found when the axial wall relief was included. Also, it is shown that glass ionomer cement showed a lower marginal discrepancy [P < 0.001] and a higher retentive value [P = 0.010] in every location of die relief compared to those of zinc phosphate cement

Effect of hybridization on the production of cellulolytic enzymes by aspergillus niger

Two non cellulolytic auxotrophic mutants of Aspergillus niger were crossed together. From 20 obtained prototrophs, the segregants of 4 only could give prototrophs indicating that they were stable heterocaryons or diploids. The 4 prototrophs grew well and produced true cellulolytic activity on avicel as a sole carbon source. Cellulase production by the 4 isolates growing in liquid medium in shaken flask cultures has been investigated. In general A. niger isolates were found to be inducible for the enzymes of the cellulase complex [exoglucanase, endoglucanase, and B-glucosidase], and isolate No I was the most potent mold, and it showed about 3 fold that in B-glucosidase production [8.851 unit/ml] when Na NO[3]was used as a nitrogen source

Psychiatric diagnostic categories in Saudi Arabia

This study involves 324 new cases referred to the Psychiatric Department of king Faisal University, Dammam, Saudi Arabia, over a period of 6 months. Men outnumbered women, which is in contrast to most Western studies. There was a preponderance in the younger age groups. The interaction of cultural factors and the rapid, urbanization of the Saudi society may to some extent explain the pattern

action of glutamate on the spectral absorbance of retina's fish

Perfusion of the isolated retina of the bulti [tilapia nilotica] A with Ringer's solution containing 5 mM glutamate is shown to cause changes in the optical density of the retina. The absorbance spectrum of these changes were recorded every 15 minutes up to 90 minutes after start of perfusion. The results indicate that there were polyphases changes over the spectrum of wavelength ranging from 350 to 650 nm. The maximum increase in optical density was found to be 25 percent at about 420 nm, while the maximum drop was 60 percent at 440-450 nm