XRD and ATR-FTIR techniques for integrity assessment of gamma radiation sterilized cortical bone pretreated by antioxidants.

Terminal sterilization of bone allograft by gamma radiation is required to reduce the risk of infection. Free radical scavengers could be utilized to minimize the deteriorating effects of gamma radiation on bone allograft mechanical properties. The objective of this research is to assess the changes in structural and chemical composition induced by hydroxytyrosol (HT) and alpha lipoic acid (ALA) free radical scavengers in gamma sterilized cortical bone. Bovine femurs specimens were soaked in different concentrations of HT and ALA for 7 and 3 days respectively before irradiation with 35 KGy gamma radiation. The attenuated total reflection-Fourier transform infrared spectroscopy and the X-ray diffraction techniques were utilized to analyze the changes in chemical composition induced by irradiation in the presence of free radical scavengers. A significant increase in the proportion of amide I and amide II to phosphate was noticed in the irradiated group, while in the pretreated groups with ALA and HT this effect was minimized. In addition, gamma radiation reduced the mature to immature cross links while ALA and HT alleviated this reduction. No significant changes were noticed in the mineral crystallinity or crystal size. Bone chemical structure has been changed due to gamma irradiation and these changes are mainly relevant to amide I, amide II proportions and collagen crosslinks. The deteriorating effects of gamma sterilization dose (35 kGy) on chemical structure of bone allograft can be alleviated by using (HT) and (ALA) free radical scavengers before irradiation.

Biomechanical properties enhancement of gamma radiation-sterilized cortical bone using antioxidants.

Gamma radiation sterilization is the method used by the majority of tissue banks to reduce disease transmission from infected donors to recipients through bone allografts. However, many studies have reported that gamma radiation impairs the structural and mechanical properties of bone via formation of free radicals, the effect of which could be reduced using free radical scavengers. The aim of this study is to examine the radioprotective role of hydroxytyrosol (HT) and alpha lipoic acid (ALA) on the mechanical properties of gamma-sterilized cortical bone of bovine femur, using three-point bending and microhardness tests. Specimens of bovine femurs were soaked in ALA and HT for 3 and 7 days, respectively, before being exposed to 35-kGy gamma radiation. In unirradiated samples, both HT and ALA pre-treatment improved the cortical bone bending plastic properties (maximum bending stress, maximum bending strain, and toughness) without affecting microhardness. Irradiation resulted in a drastic reduction of the plastic properties and an increased microhardness. ALA treatment before irradiation alleviated the aforementioned reductions in maximum bending stress, maximum bending strain, and toughness. In addition, under ALA treatment, the microhardness was not increased after irradiation. For HT treatment, similar effects were found. In conclusion, the results indicate that HT and ALA can be used before irradiation to enhance the mechanical properties of gamma-sterilized bone allografts.

The diagnostic capability of x-ray scattering parameters for the characterization of breast cancer.

PURPOSE: The evaluation of the diagnostic capability of easy to measure x-ray scattering profile characterization parameters for the detection of breast cancer in excised samples. The selected parameters are the full width at half maximum (FWHM) and area under the x-ray scattering profile of breast tissue in addition to the ratio of scattering intensities (I2/I1%) at 1.6 nm(-1) to that at 1.1 nm(-1) (corresponding to scattering from soft and adipose tissues, respectively). METHODS: A histopathologist is asked to classify 36 excised breast tissue samples into healthy or malignant. A conventional x-ray diffractometer is used to acquire the scattering profiles of the investigated samples. The values of three profile characterization parameters are calculated and the diagnostic capability of each is evaluated by determining the optimal cutoffs of scatter diagrams, calculating the diagnostic indices, and plotting the receiver operating characteristic (ROC) curves. RESULTS: At the calculated optimal cutoff for each of the examined parameters, the sensitivity ranged from 78% (for area under curve) up to 94% (for FWHM), the specificity ranged from 94% [for I2/I1% and area under curve] up to 100% (for FWHM), and the diagnostic accuracy ranged from 86% (for area under curve) up to 97% (for FWHM). The area under the ROC curves is greater than 0.95 for all of the investigated parameters, reflecting a highly accurate diagnostic performance. CONCLUSIONS: The discussed tests offered a means to quantitatively evaluate the performance of the suggested breast tissue x-ray scattering characterization parameters. The performance results are promising, indicating that the evaluated parameters would be considered a tool for fast, on spot probing of breast cancer in excised tissue samples.

Electrical behavior of stored erythrocytes after exposure to gamma radiation and the role of alpha-lipoic acid as radioprotector.

The effects of gamma rays (25, 50 and 100 Gy) on stored erythrocytes were studied by measuring their dielectric properties and observing their morphology under scanning electron microscopy. Alpha lipoic acid (a potent natural antioxidant) was introduced prior to irradiation for radioprotection. It can be concluded that the dose level of 25 Gy can be considered a safe sterile dose; however, irradiation doses of 50 and 100 Gy should be applied with the addition of alpha-acid to preserve the cell viability.

Biophysical characterization of beta-thalassemic red blood cells.

Thalassemia is the world's most common hereditary disease; therefore, more interest has been devoted for the development of the screening procedure of this disease. In beta-thalassemia major, the subject of the current study, impaired biosynthesis of beta-globin leads to accumulation of unpaired alpha-globin chain. The objective of the present study, was to examine many of the biophysical properties of beta-thalassemia major red blood cells (RBCs) and to study the possibility of use of any of them as a preliminary screening tool for beta-thalassemia. The percentage of normal hemolysis, osmotic fragility test, turbidity test, rheological properties, and dielectric properties, were studied in 20 regularly blood transfused thalassemia major patients who were under chelation therapy and their status were compared with those of 10 healthy subjects. There was an increase in the percentage of hemolysis for beta-thalassemia by 114.6% compared to the normal RBCs. The fragility curve for beta-thalassemia RBCs showed a shift toward lower NaCl concentration compared to the normal curve. The average osmotic fragility (H(50): the NaCl concentration producing 50% homolysis) for beta-thalassemia was found to be 3.21 +/- 0.67 g/l, whereas for normal RBCs it was 5.5 +/- 0.31 g/l. The turbidity curve of the beta-thalassemic RBCs showed a shift toward higher detergent concentration of the normal curve, with higher value for the average membrane solubilization (S(50)). The viscosity value of whole blood beta-thalassemia was found to be 3.916 +/- 0.56 cp whereas for normal blood was 2.516 +/- 0.36 cp. The relative permittivity, dielectric loss, and AC conductivity of RBCs decreased significantly compared to normal samples. This could be attributed to the loss of the insulating properties of the membrane and loss of its surface charge of thalassemic RBCs. As can be noticed, several factors showed clear difference between thalassemic and normal blood samples. Some of these parameters could be measured immediately after sample withdrawal and require short time to perform the measurements. This offers the advantages of being effective, low cost, and fast techniques, therefore, we suggest that these techniques could be applied for beta-thalassemia major screening purposes.

Enhanced detection of hepatocellular carcinoma.

BACKGROUND: Tumor markers in the early detection of tumors are promising tools that could improve the control and treatment of tumors. While alpha-fetoprotein (AFP) is a commonly used tumor marker in the detection of hepatocellular carcinoma (HCC), its sensitivity and specificity are insufficient to detect HCC in all patient samples. METHODS: We compared AFP with serum levels of vascular endothelial growth factors (VEGF and VEGF-A), insulin-like growth factor-2 (IGF-II), and the activity of the lysosomal enzyme alpha-L-fucosidase (AFU) in the sensitivity of detection of HCC and cirrhosis in Egyptian patients. RESULTS: The sensitivity of tumor detection using AFP was 68.2%. This level of detection was increased to 88.6% when AFP was evaluated in conjunction with AFU. The combined use of AFP and VEGF increased the sensitivity of detection to 95.5% in patients with HCC. The combination of the three markers yielded 100% detection sensitivity. VEGF-A showed a low specificity (20%), and IGF-II showed extremely low sensitivity (4.5%). CONCLUSIONS: We suggest that AFU or VEGF or both be measured with AFP to improve the detection sensitivity of HCC.

A new ESR dosimeter based on bioglass material.

Bioglass (Bio-G) samples were irradiated with 60Co gamma-rays to study radicals for dosimetric materials with electron spin resonance (ESR). The ESR spectrum of Bio-G is characterized by two main signals. The first signal at g approximately = 4.3 corresponds to Fe3+ impurities and the second signal at g approximately = 2.0130 with line-width 10.85 G is ascribed as a hole center. The gamma-ray dose response and thermal stability were studied to establish the suitability of bioglass as an ESR dosimeter. A radical formation efficiency, G-value, of 0.53 +/- 0.11 was obtained. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 255 +/- 46 days and 0.71 eV, respectively.

Characterization of cirrhosis and hepatocellular carcinoma using low-angle x-ray scattering signatures of serum.

The diagnosis of hepatocellular carcinoma (HCC) usually occurs at late stages in the disease when there are few effective treatment options. The measurement of the concentration of tumour markers in the serum of patients is a complementary tool frequently used for the interpretation of diagnostic imaging results. It is also used as a prognostic tool for the detection of cancer. Unfortunately, the sensitivity of tumour markers is still low and many times it yields normal results for cirrhotic and HCC patients. In the current work, the detection possibility of the structural changes in serum proteins accompanying cirrhosis and HCC is investigated using a low-angle x-ray scattering (LAXS) technique. The results show that there are significant differences in the LAXS profiles of cirrhosis and HCC lyophilized serum samples compared to normal. The changes in shape, total counts and position of the first scattering peak at 4.8 degrees, which was previously reported to be sensitive to the structural changes in protein, showed the most characteristic deviations from normal serum. The present results are promising and would offer a potentially helpful complementary tool for monitoring cirrhosis and HCC.