Difference In Optical Density Research Articles

Effects of Enamel Matrix Derivative on Bioactive Glass in Rat Calvarium Defects

Tissue engineering-based bone grafting has emerged as a viable alternative to biologic and synthetic grafts. The purpose of this study was to evaluate the effect of enamel matrix derivative (EMD; Emdogain gel, Biora AB, Malmö, Sweden) on bioactive glass in enhancing bone formation in rat calvarium defects. Twenty rats were used in the study. In all animals, 2 standardized critical-sized calvarial defects (5.0 mm diameter) were created surgically. The animals were randomly allocated into 4 groups of 5 animals each. Group AI: one calvarial defect was filled with bioactive glass plus EMD, while the contralateral defect was filled with bioactive glass alone. The healing period was 2 weeks. Groups AII and AIII: the animals were treated in the same manner as in group AI, but the healing periods were 4 and 8 weeks, respectively. Group B: one calvarial defect was filled with EMD only, while the contralateral defect was empty (CSD). The healing period was 8 weeks. New bone formation was evaluated by radiomorphometry and histomorphometry. Results of radiomorphometry showed no significant difference in the mean optical density between bioactive glass with EMD and bioactive glass alone; no defect completely regenerated with bone. The histologic analysis revealed that defects filled with bioactive glass plus EMD in all groups contained slightly more percentage of new bone than those filled with bioactive glass alone; however, the difference was not statistically significant. The highest percentage of new bone formation was present at 8 weeks in the bioactive glass plus EMD group. Bioactive glass particles, used with or without EMD, maintained the volume and contour of the area grafted in CSD. However, they did not lead to a significant difference in bone formation when compared with CSD 8 weeks postoperatively.

Technical Note: Potential errors in optical density measurements due to scanning side in EBT and EBT2 Gafchromic film dosimetry

The purpose of this study is to determine the effect on the measured optical density of scanning on either side of a Gafchromic EBT and EBT2 film using an Epson (Epson Canada Ltd., Toronto, Ontario) 10000XL flat bed scanner.Calibration curves were constructed using EBT2 film scanned in landscape orientation in both reflection and transmission mode on an Epson 10000XL scanner. Calibration curves were also constructed using EBT film. Potential errors due to an optical density difference from scanning the film on either side ("face up" or "face down") were simulated.Scanning the film face up or face down on the scanner bed while keeping the film angular orientation constant affects the measured optical density when scanning in reflection mode. In contrast, no statistically significant effect was seen when scanning in transmission mode. This effect can significantly affect relative and absolute dose measurements. As an application example, the authors demonstrate potential errors of 17.8% by inverting the film scanning side on the gamma index for 3%-3 mm criteria on a head and neck intensity modulated radiotherapy plan, and errors in absolute dose measurements ranging from 10% to 35% between 2 and 5 Gy.Process consistency is the key to obtaining accurate and precise results in Gafchromic film dosimetry. When scanning in reflection mode, care must be taken to place the film consistently on the same side on the scanner bed.

Digital Radiographic Analysis of Optical Density of the Distal Segment of the Trochlear Notch of the Ulna in Labrador Retrievers with Fragmented Coronoid Process

The aim of the study was to find whether there is a difference in the optical density of the subtrochlear region of incisura trochlearis and in the region of processus coronoideus medialis ulnae in elbow joints with fragmented processus coronoideus and in healthy elbow joints of the Labrador retriever breed. We evaluated digital radiographs of elbows (n = 26) with arthroscopically or arthrotomically proven FCP and digital radiographs of healthy elbows (n = 28). A template was made on radiographs in the JiveX program (Visus Technology Transfer) demarcating individual regions of interest (ROI) in which median optical density was measured. For normalisation of median optical density data of individual ROI, median optical density of the caudal ulnar cortex was used. Elbow joints with fragmented processus coronoideus had a lower mean median optical density in the distal part of incisura trochlearis compared to healthy elbow joints. The lowest median optical densities were found in the region of processus coronoideus medialis and in the distal part of the trochlear notch of the ulna in the region of processus coronoideus lateralis. The biggest difference in median optical densities between elbows with FCP and healthy elbows was found in regions distant from the articular surface. In evaluation of the opacity of the trochlear notch of the ulna it is appropriate to assess the whole region of the proximal ulnar metaphysis from the articular surface to the caudal ulnar cortex.

A novel approach for non-invasive measurement of blood haemoglobin

An attempt is made to design a technique for determining total haemoglobin concentration, by wavelength selection and algorithm. A model is based on the difference in optical density induced by the pulsation of the heart beat, by assuming that, the variation of blood vessel size is small during arterial pulsing. A device is constructed with two Light Emitting Diodes (LEDs), and light source of 590 nm and 525 nm wavelength. The selected wavelengths are isosbestic points. Clinical data of patients are collected from pathology laboratory, which is used for determining the correlation between the absorption of light through finger and actual haemoglobin count.

International ring trial to detect anti- Trichinella IgG by ELISA on pig sera

To determine the reproducibility and robustness of an ELISA to detect anti- Trichinella IgG in pig sera which was previously validated at the Community Reference Laboratory for Parasites (CRLP), a ring trial was organized involving European and extra-European reference laboratories for Trichinella. The sensitivity and specificity of the assay determined by the CRLP validation resulted to be 100% and 98.29%, respectively. The assay was reproducible, moreover, based on the receiver-operator characteristic (ROC) curve, the sensitivity and specificity of the assay reached 97.5% and 96.9%, respectively. The analysis of the differences in optical density (OD) between duplicates indicated a high repeatability of the ELISA with about 95% of the differences between −0.16 and 0.17 absorbance units. The accuracy of the test was determined by calculating the area under the ROC curve (AUC). Overall, the ELISA index ( I E) showed a very high accuracy (AUC = 0.9965) and it performed significantly better than the mean of the duplicated ODs (AUC = 0.9387). Of the 21 participating laboratories, nine performed the test without any modification of the original protocol, and 14 with some modifications. Of the laboratories that followed the protocol exactly, three produced false-negatives; whereas of the laboratories that modified the protocol, five produced false-negatives (differences between these two groups of laboratories were not significant, p = 0.18). When comparing these two groups of laboratories, the AUCs were very similar (0.9988 and 0.9955, respectively). Finally, a normal mixed multiple model effect was used to evaluate if the I E obtained was only related to the serum or to other parameters such as the laboratory, dilution of the serum tested and application of the proposed protocol. The variability found in the test results was mainly due to the serum samples. The assay proposed is robust and reproducible and can be used for monitoring the lack of Trichinella infection in domestic pigs.

Comparison of macular pigment optical density (MPOD) between a northern European and a Mediterranean population

Abstract Purpose To investigate the Macular Pigment Optical Density (MPOD) differences between a northern European and a Mediterranean population. Methods MPOD was measured psychophysically using Heterochromatic Flicker Photometry in 71 healthy subjects from northern Europe (18 Dutch and 53 British). 74 healthy age‐matched Cretans (Greece) underwent the same measurements according to the same protocol. None of the subjects was taking any carotenoids supplements. The comparison of MPOD between the two populations was statistically assessed with a Generalized Linear Model of regression. The effect of age and gender was taken into consideration. Results The mean MPOD of the northern Europe population was 0.43 (CI 95% 0.39‐0.47) and the mean age 45 years old (±19). No effect of age (p=0.402) or gender (p=0.074) was revealed into this group. Respectively, for the Mediterranean population the mean MPOD was 0.42 (CI 95% 0.38‐0.45) and the mean age 39 years old (±17);mean MPOD of this group didn’t seem to change with age (p=0.402) or be affected by gender (p=0.511) either. No statistically significant difference in the MPOD between the two populations was revealed from the analysis (p=0.455). No sex or age effect was observed in the total population (p=0.893, p=0.094 respectively). Conclusion The MPOD was compared between two populations with different levels of light exposure and theoretically different diet. Although these factors are believed to affect the levels of MPOD, the latter didn’t seem to differ significantly between the two groups in the present study. Additionally, the MPOD levels weren’t found to change with age in either group or in the total population. Similarly, no sex differences were observed.

하드코팅에 의한 광변색 플라스틱 렌즈의 제조 및 특성

하드코팅에 의해 광변색과 경성의 성질을 갖는 플라스틱 렌즈를 제조하고, 그것들의 광학적 성질과 표면 특성을 평가하였다. 무색 상태의 자외선 스펙트럼과 유색 상태의 가시광선 스펙트럼에서 광변색 효과를 관찰할 수 있었다. 광변색 렌즈의 가시광선 투과율은 무색 상태에서 83.44%(검정)에서 87.15%(청)였으며, 유색 상태에서 71.10%(적)에서 79.98%(황)이었다. 적색 광변색 렌즈는 다른 렌즈에 비해 광학 밀도(<TEX>${\Delta}$</TEX>OD)와 색차(<TEX>${\Delta}$</TEX><TEX>$E^{\ast}_\;{ab}$</TEX>)가 컸다. 하드코팅을 적용한 광변색 렌즈는 부착성, 내온수성, 내약품성 및 표면 현상이 우수하였으며, 또한 경도와 내마모성은 무코팅 렌즈에 비하여 증가하였다. 따라서 이와 같은 코팅 시스템으로 광변색과 하드코팅 성질과 같은 기능성을 안경렌즈에 부여할 수 있었다. In this study, we have prepared plastic lenses with both photochromic and hard properties by hard coating, and evaluated their optical properties and surface characteristics. Photochromic effects could be observed on the UV spectra of the closed forms and the visible spectra of the open forms. Visible light transmittance of photochromic lenses was from 83.44% for graphite(GP) to 85.15% for blue(BL) in colourless state and from 71.10% for red(RE) to 79.98% for yellow(YE) in colour state. Red photochromic lens was higher in optical density(<TEX>${\Delta}$</TEX>OD) and color difference(<TEX>${\Delta}$</TEX><TEX>$E^{\ast}_\;{ab}$</TEX>) than the others. Photochromic lenses applied by hard coating showed good adhesion, hot water resistance, chemical resistance and surface appearance. Also, compared to the uncoated lens, hardness and abrasion resistance were increased. Consequently, this coating system could impart functional properties such as photochromic and hard coating property onto ophthalmic lenses.

SU‐FF‐T‐283: Proton Beam Dosimetry Using Gafchromic EBT Film

Purpose: Gafchromic EBT film characteristics for dose, dose rate, film orientation, air gap, tilt angle, beam energy and temporal stability were investigated in a clinical proton beam dosimetry. Methods and Materials: The EBT film was sandwiched between solid water slabs and irradiated in both parallel and perpendicular arrangements against the beam incident direction. Calibration films were irradiated in the dose range of 20 cGy–1000 cGy at mid spread out Bragg Peak (SOBP) in a reference condition. The optical density changes due to dose, dose rate and proton beam energies were studied. Depth doses measured with EBT film were compared with those obtained with a plane‐parallel ion‐chamber. The responses of the exposed films were measured by a Macbeth TD932 densitometer and a Vidar Dosimetry Pro Advantage™ scanner. Measurements were made at finite time post irradiation for temporal response. Results: There was no noticeable optical density change over dose rates ranging from 32 to 640 cGy min−1. There was an increase in optical density of up to 0.04 units one month after irradiation within the dose range studied. The difference in optical densities between perpendicular and parallel configurations tends to be rather small, within ±0.02 OD units. Air gaps between the film and slabs caused significant perturbation in the depth dose distribution when the film is parallel to the beam axis. By tilting the film plane a few degrees away the beam axis, air gap artifacts was eliminated. Depth dose profiles measured with Gafchromic EBT film agreed with the one measured with an ion chamber although EBT film appears to have an under‐response in the distal end of SOBP. Conclusions: Gafchromic EBT film has unnoticeable dependences of dose rate and proton beam energy. The Gafchromic EBT film could be a useful detector for proton dosimetry measurements with proper precaution and correction.

A procedure to mathematically amend possible thickness disuniformities in gel-layer dosimetry

The continuous development of conformal radiotherapies requires a corresponding improvement of dosimetric techniques. Fricke gel-layer dosimetry, coupled with a suitably developed software, has proven to be a reliable technique for 3D absorbed dose distribution verification. The method is based on the evaluation of the light transmitted by gel-layers due to the fact that th optical density difference between irradiated and non irraddiated dosimeters is proportional to the absorbed dose. Measurement are performed by means of a planar illumination source and a computer-controlled CCD camera. Recently, adoption of gel layers with increased superficial dimensions has evidenced a possible thickness disuniformity of layers, thus introducing a new source of measurement inaccuracy. In this work, a method to mathematically amend this possible source of error is proposed. Dose profiles along the central axis of phantoms irradiated with X-ray therapy and Boron Neutron Capture Therapy fields, obtained with and without the application of the proposed correction procedure, were compared with ionization chamber measurements and Monte Carlo simulations, respectively. The obtained results show a good reliability of the proposed procedure.

Clinical Application of Autofluorescence Densitometry with a Scanning Laser Ophthalmoscope

Fundus autofluorescence (FAF) affects the overlying absorptive retinal pigments within the eye and can potentially be used to assess their density. This study reports a clinical application of FAF in measuring photopigments by scanning laser ophthalmoscopy (SLO). The study group comprised 20 healthy subjects, 4 patients with branch retinal artery occlusion (BRAO), 3 with macular hole, 3 with branch retinal vein occlusion (BRVO), and 4 with resolved central serous chorioretinopathy (CSC). Serial FAF images were taken during exposure to light. The intensity of the FAF was measured at the site of the macular hole or the photocoagulation laser burn in the eyes with BRVO. The autofluorescence optical density difference (fODD) was measured from the FAF images and mapped to elucidate the topographic pattern. The autofluorescence intensity showed little change at the sites of the macular holes or photocoagulation burns during exposure to light. The fODD was smallest at the center of the fovea and gradually increased with the eccentricity within 270 x 270 pixels around the fovea in healthy subjects. The amplitude of the fODD did not change in the area affected with BRAO in comparison to the unaffected area. By contrast, the fODD decreased in the area of resolved serous retinal detachment in the eyes with CSC. In eyes with retinal disease, measuring the autofluorescence intensity using SLO is a feasible method of assessing the changes in the photopigments. Further studies comparing this approach with conventional methods for examining photopigments are needed.

Hepatic injury induced by carbon dioxide pneumoperitoneum in experimental rats

To observe the hepatic injury induced by carbon dioxide pneumoperitoneum in rats and to explore its potential mechanism. Thirty healthy male SD rats were randomly divided into control group (n = 10), 0 h experimental group (n = 10) and 1 h experimental group (n = 10) after sham operation with carbon dioxide pneumoperitoneum. Histological changes in liver tissue were observed with hematoxylin-eosin staining. Liver function was assayed with an automatic biochemical analyzer. Concentration of malonyldialdehyde (MDA) and activity of superoxide dismutase (SOD) were assayed by colorimetry. Activity of adenine nucleotide translocator in liver tissue was detected with the atractyloside-inhibitor stop technique. Expression of hypoxia inducible factor-1 (HIF-1) mRNA in liver tissue was detected with in situ hybridization. Carbon dioxide pneumoperitoneum for 60 min could induce liver injury in rats. Alanine aminotransferase and aspartate aminotransferase were 95.7 +/- 7.8 U/L and 86.8 +/- 6.9 U/L in 0 h experimental group, and 101.4 +/- 9.3 U/L and 106.6 +/- 8.7 U/L in 1 h experimental group. However, no significant difference was found in total billirubin, albumin, and pre-albumin in the three groups. In 0 h experimental group, the concentration of MDA was 9.83 +/- 2.53 micromol/g in liver homogenate and 7.64 +/- 2.19 micromol/g in serum respectively, the activity of SOD was 67.58 +/- 9.75 nu/mg in liver and 64.47 +/- 10.23 nu/mg in serum respectively. In 1 h experimental group, the concentration of MDA was 16.57 +/- 3.45 micromol/g in liver tissue and 12.49 +/- 4.21 micromol/g in serum respectively, the activity of SOD was 54.29 +/- 7.96 nu/mg in liver tissue and 56.31 +/- 9.85 nu/mg in serum, respectively. The activity of ANT in liver tissue was 9.52 +/- 1.56 in control group, 6.37 +/- 1.33 in 0 h experimental group and 7.28 +/- 1.45 (10(-9) mol/min per gram protein) in 1 h experimental group, respectively. The expression of HIF-1 mRNA in liver tissue was not detected in control group, and its optical density difference value was 6.14 +/- 1.03 in 0 h experimental group and 9.51 +/- 1.74 in 1 h experimental group, respectively. Carbon dioxide pneumoperitoneum during the sham operation can induce hepatic injury in rats. The probable mechanisms of liver injury include anoxia, ischemia reperfusion and oxidative stress. Liver injury should be avoided during clinical laparoscopic operation with carbon dioxide pneumoperitoneum.

Validation of an Enzyme-Linked Immunosorbent Assay for Diagnosis of Human Trichinellosis

Trichinellosis is a zoonotic disease caused by the consumption of raw or semiraw meat from different animals harboring Trichinella larvae in their muscles. Since there are no pathognomonic signs, diagnosis can be difficult; for this reason, serology is important. The objective of this study was to validate an enzyme-linked immunosorbent assay (ELISA) using excretory/secretory antigens to detect anti-Trichinella immunoglobulin G antibodies in human sera. A total of 3,505 human serum samples were tested. A receiver-operator characteristic (ROC) curve analysis was performed. The accuracy of the test was determined by calculating the area under the curve, which was equal to 0.999, indicating high accuracy. The coefficient of variation calculated for data from four serum samples in eight working sessions was no higher than 5% for the positive sera or 14% for the negative sera. Moreover, the analysis of the differences in optical density between duplicates indicated a high repeatability for the ELISA. At the ROC optimized cutoff, the sensitivity and specificity of the test were, respectively, 99.2% and 90.6% (specificity of 95.6% when excluding the samples from multiparasitized persons from Tanzania). The validated ELISA showed good performance in terms of sensitivity, repeatability, and reproducibility, whereas the specificity was limited. These results suggest that this test is suitable for detecting anti-Trichinella antibodies in human sera for diagnostic purposes, whereas its use in epidemiological surveys could be questionable.

Effect of 10% formalin on radiographic optical density of bone specimens

The aim of this work was to determine whether the fixation process with 10% formalin modifies the radiographic optical density of bone. Eight rabbit tibiae were placed in separate containers with one of the following fixative solutions: 10% formalin (n = 3), 10% phosphate-buffered formalin (n = 3) or 10% calcium carbonate-buffered formalin (n = 2). Radiographs were obtained at 5 different times: before fixation (time zero), then 1 day, 15 days, 30 days and 90 days following immersion in the fixative solution. Radiographs were scanned and optical density was determined using ImageTool software. There was no significant difference in radiographic optical density among the specimens fixed in 10% formalin (146.60+/-32.44), 10% phosphate-buffered formalin (149.84+/-32.43) and 10% calcium carbonate-buffered formalin (146.61+/-35.92). Regardless of buffering, optical density at time zero was significantly higher than that at 15 days, 30 days and 90 days. However, while optical density at 1 day was significantly higher than that at 30 days and 90 days, it did not differ from that at 15 days. There was also no significant difference in density between 30 days and 90 days (ANOVA, Tukey, at 5% level of significance). The radiographic optical density of specimens stored in 10% formalin diminishes with time, irrespective of buffering, which suggests the occurrence of bone demineralization.

Comparative histomorphometric and tomographic analysis of maxillary sinus floor augmentation in rabbits using autografts and xenografts

Our goal was to evaluate bone neoformation promoted by a bovine xenograft composite (XC) compared with autogenous graft for maxillary sinus augmentation in a rabbit model. The left maxillary sinus of 18 male rabbits was filled with 200 mg of cortical and cancellous autogenous bone and the right sinus was filled with 200 mg of a composite comprised organic and inorganic bovine matrices, pool of bBMPs and collagen. Postoperative implant intervals of 2, 4, and 8 weeks were analyzed. Differences in the bone optical density among the groups and experimental periods were evaluated by computed tomography analysis. The tissue response was evaluated by histomorphometric analysis of the newly formed bone, connective tissue and/or granulation tissue, residual material, and bone marrow. The tomographic analyses showed a maximum optical density in the 4-week period for both groups. Histologically, an inflammatory infiltrate was observed at 2 weeks in the XC group but exclusively around the organic particles of the biomaterial. Regarding to the amount of newly formed bone, no statistical differences (p > 0.05) were observed among the two treatments throughout the implant intervals. However, by the end of the 8 weeks, the quantity of bone marrow was two times greater (p < 0.05) in the control group than in the XC group. In conclusion, the xenograft composite promotes formation of new bone in a similar fashion to autogenous bone and could therefore be considered a biomaterial with potential applications as a bone substitute in maxillary sinus floor augmentation.

Factors associated with variation in Neospora caninum bulk-milk S/P ratios in initially bulk-milk negative testing Dutch dairy herds

We conducted a study on 81 initially bulk-milk ELISA negative dairy herds taken from a random sample of Dutch dairy herds to evaluate variation in bulk-milk S/P ratios and to study reasons for bulk-milk conversion. These herds were repeatedly (3-month intervals) tested between April 2004 and August 2005 and serostatus of all animals had previously been established as negative (N), low-positive (LP) or high-positive (HP). Of these herds, herd- and test-related factors associated with variation in sample over positive (S/P) ratios were analysed using a multivariable linear-mixed model with ‘herd’ as random effect. In addition, changes of animal serostatus in converting herds were described. S/P ratios were calculated as the optical density of the bulk-milk sample minus the optical density of the negative serum control divided by the difference in optical density between the positive and negative serum control. Sixteen bulk-milk conversions in 12 dairy herds were seen with few indications of serological conversion in lactating cattle except for one herd in which recrudescence of infection appeared likely in nine cows. The effect of HP serostatus on bulk-milk S/P ratio was 2–3 times stronger compared with LP serostatus. In addition, bulk-milk S/P-ratio increased when the proportion of HP animals between 1 and 60 days in milk increased and decreased when the average milk-production level of the herd increased. Besides these herd-related factors, the use of different ELISA-testkits between test rounds had a significant effect on the S/P-ratio in bulk-milk samples.

Scattering and image contrast simulation for double wall radiography of pipes

Radiographic image quality, which is quantified by radiographic sensitivity measurements, is significantly influenced by parameters such as scattering, effective attenuation coefficient and image contrast. In the present work, the Monte Carlo method has been utilized to simulate Gamma ray scattering and image contrast for double wall radiography of pipes and some experiments have been designed to determine the radiographic sensitivity and measure the effective attenuation coefficient. Wire type image quality indicators were simulated as artificial defects and the threshold contrast and minimum optical density difference for viewing each wire were investigated. It was found that the maximum allowable source to film distance for double wall exposure and single wall viewing technique was 1.4 times the outside diameter of the pipe and the image contrast and radiographic sensitivity were higher for this technique in comparison with the double wall viewing technique. The double wall exposure and double wall viewing technique is proposed to be used when the minimum source to film distance is higher than 1.4 times the outside diameter.

Tandem dye-sensitized solar cell-powered electrochromic devices for the photovoltaic-powered smart window

Tandem dye-sensitized solar cell (DSSC)-electrochromic (EC) devices were realized using two-faced transparent conducting oxide (TCO). To supply sufficient voltage to drive the EC devices, two series connected, semitransparent DSSCs were fabricated with 7 nm-thick, dye-adsorbed TiO 2 and 4 nm-thick Pt layers. The two series connected, semitransparent DSSCs that were used had an open circuit voltage and short circuit current density of about 1.35 V and 3.96 mA cm −2, respectively, at 1-sun. The tandem DSSC-EC devices showed an optical density difference of 1.2 at 750 nm and reasonable response times of about 60 and 45 s during the coloring and bleaching processes, respectively, indicating that the two series-connected, semitransparent DSSCs could be used as the power sources in the tandem photovoltaic-powered EC devices.

Association of hepatitis E virus (HEV) and postweaning multisystemic wasting syndrome (PMWS) with lesions of hepatitis in pigs

The aim of the study was to determine the presence of swine hepatitis E virus (HEV) RNA and antibodies in postweaning multisystemic wasting syndrome-affected ( n = 114) and non-affected ( n = 46) pigs and the possible association with hepatitis lesions. Forty-four pigs were RT-PCR positive (28.2%); 25 of them were PMWS cases, while 19 were non-PMWS pigs. In both groups, HEV RT-PCR results were associated with hepatitis (OR = 5.61 for PMWS-affected pigs and OR = 5.17 for non-PMWS affected pigs; p = 0.01). No interaction was detected in a logistic regression between PMWS occurrence and HEV infection for the development of hepatitis lesions. Seropositivity to HEV was more likely to occur in pigs with hepatitis (51.9%) compared to pigs without hepatitis (36.1%; p = 0.03). Significant differences in optical densities were notices comparing the lesional stage of pigs ( p = 0.009). While pigs with slight or moderate hepatitis were seropositive, pigs with more severe lesions were seronegative to HEV. These results indicate that swine HEV infection can be a significant contributor to the development of moderate hepatitis in pigs regardless of the PMWS status.

Candida albicans inactivation and cell membrane integrity damage by microwave irradiation

In indicating the microwave irradiation for disinfecting dentures it is necessary to see how this procedure influences Candida albicans integrity and viability. The aim of this study was to evaluate the ability of microwaves to inactivate C. albicans and damage cell membrane integrity. Two 200-ml C. albicans (ATCC 10231) suspensions were obtained. A sterile denture was placed in a beaker containing the Experimental (ES) or the Control suspension (CS). ES was microwaved at 650 W for 6 min. Suspensions were optically counted using methylene blue dye uptake as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550 nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca++ (Cresolftaleine complexone method); DNA (spectrophotometer measurements at 260 nm) and K+ (selective electrode technique). Data were analysed by Student's t- or Wilcoxon z-tests (alpha = 0.05). All ES cells demonstrated cell membrane damage. Viable cells were non-existent in the ES ASD plates. No significant difference in optical density between ES and CS was observed (P=0.272). ES cells released significantly high protein (P<0.001, Bradford; P=0.005, Pyrogallol red), K+ (P<0.001), Ca++ (P=0.012) and DNA (P=0.046) contents. Microwaves inactivated C. albicans and damaged cell membrane integrity.

Development of an enzyme-linked immunosorbent assay for quantification of Salmonella enteritidis-specific antibodies in egg yolk

The present study aims at developing an indirect ELISA to quantify yolk antibodies specific to all surface proteins of the invasive Salmonella Enteritidis (SE), which acquired the 1.8, 14.1, and ~ 50 Kb plasmids. An ELISA checkerboard was used in four different experiments to account for the different parameters included in the preliminary ELISA procedure, and consequently to maximize the difference in Optical Density (OD) values between control positive and negative yolk samples. The first experiment aimed at studying the impact of 5% Bovine Serum Albumin (BSA) dissolved in distilled water as a blocking reagent on a 28 µg/well SE antigen-coated plate, while applying the positive and negative control yolk samples to different concentrations of Phosphate-Buffered Saline (PBS).Conjugate application was maintained constant at a dilution of 1:500 in PBS. The second experiment was similar to the first one, but the positive and negative control yolk samples were diluted in PBS-Tween 20, and the conjugate dilution was changed to 1:1500 in PBS-Tween 20. In the third experiment, the conjugate was diluted at 1:1500 in 5% BSA/PBS-Tween 20 diluent or PBS-Tween 20 diluent with no 5% BSA. The objective of the fourth experiment was to study the impact of four different concentrations of SE-coated antigen levels (28µg/well, 56µg/well, 84µg/well, and 112µg/well), while fixing the blocking step with 5% BSA in distilled water, and the conjugate dilution set at 1:1000 in 5% BSA/PBSTween 20, and fixing the control yolk samples dilution at 1% in PBS-Tween 20. This last experimental procedure allowed the highest difference in mean absorbance OD values of the positive control minus the negative control samples, which was equivalent to 0.381. In addition, the final protocol for this ELISA was applied on individual egg yolk samples of two groups of chicken layers: one challenged in the esophagus at 11 days with 5.4 x 1010 CFU/ml/bird of SE, and the second group was not challenged. The mean OD values of the egg yolk of antibodies specific against SE of the two groups were significantly different (0.8578 versus 0.5250; p<0.05), which indicates the possible application of the developed ELISA for screening SE infection by examining egg yolks produced by commercial layers.