Bovine Liver Samples Research Articles

Determination of quinolones and fluoroquinolones, tetracyclines and sulfonamides in bovine, swine and poultry liver using LC-MS/MS

Antibacterials are widely used in veterinary medicine. Residues of these drugs can remain in food of animal origin, including bovine liver. This paper describes a fast and simple analytical method for the determination of quinolones and fluoroquinolones, tetracyclines and sulfonamides in bovine liver samples. Deuterated enrofloxacin, sulfapyridine and demeclocycline were used as internal standards. The homogenised liver samples were extracted with acidified acetonitrile. Steps of non-solid-phase extraction (SPE) clean-up and concentration were used in the presented method. The final extracts were analysed by sensitive and selective detection of all components in a single run using LC-MS/MS. Acceptable recoveries between 66% and 110% were obtained. Good linearity (r2) above 0.96, considering three different days, for all drugs was achieved in concentrations ranging from 0.0 to 2.0 × the maximum residue limit (MRL). Intraday precision with coefficient of variation (CV%) (n = 6) lower than 14.7% and inter-day precision lower than 18.8% in agreement with European Commission Decision 2002/657/EC were obtained in concentrations ranging from 0.5 to 1.5 MRL. Accuracy was between 86% and 110%. Limits of detection and quantitation, as well as decision limit (CCα) and detection capability (CCβ), were also evaluated.

Influence of the target tissue size on the shape of ex vivo microwave ablation zones

Purpose: The aim of this study was to numerically and experimentally characterise the influence of tissues dimensions on the size and shape of microwave-induced ablation zones. Materials and methods: A 2.45 GHz interstitial antenna was introduced into ex vivo bovine liver samples, delivering 60 W for 10 min; then the dimensions of the coagulated area were measured. Ablations were performed both in large samples (termed unrestricted tissue) for characterising the tissue response, and in thin samples, whose dimensions in the plane perpendicular to the antenna were smaller than the short axis of the ablated area obtained in unrestricted samples. In the numerical study the electromagnetic field emitted from the antenna and the corresponding temperature increase were evaluated in both unrestricted and thin tissue samples. Results: When the height of the tissue was smaller than the ablation diameter measured in unrestricted samples, a 7.5% increase in length of the ablated zone was experimentally observed. When both the height and width were lower than the diameter measured in unrestricted samples, an elongation of about 23.4% was experimentally obtained. The numerical study showed that the boundary conditions between the target tissue and the surrounding materials are critical. Conclusions: The ex vivo performances of microwave ablation devices are notably influenced by the shape and dimension of the tissues where the procedure takes place. Accordingly, dedicated interventional protocols should be developed for treatment planning on targets of different shape and size.

Ultrasound assisted-deep eutectic solvent extraction of iron from sheep, bovine and chicken liver samples

A green, novel and effective ultrasound assisted-deep eutectic solvent (DES) extraction (UA-DES-E) procedure was developed for extraction of iron from sheep, bovine and chicken liver samples. The analytical parameters including type and composition DES, volume of DES, ultrasonication time and ratio of sample to DES were optimized by using 50mg of the NIST SRM 1577b bovine liver certified reference material. The limit of detection (LOD) and the limit of quantification (LOQ) were found as 0.026µgmL−1 and 0.085µgmL−1, respectively. The relative standard deviation (RSD) as a result of 7 replicates of 50mg of certified reference material was 1.4%. The accuracy of proposed method was checked by the addition/recovery tests to NIST SRM 1577b bovine liver and a sheep liver. The extraction method was applied to extraction of iron from bovine, sheep and chicken liver samples retail from markets at Kayseri, Turkey with satisfactory results (recoveries higher than 95%).

CT imaging during microwave ablation: analysis of spatial and temporal tissue contraction.

To analyze the spatial distribution and temporal development of liver tissue contraction during high-temperature ablation by using intraprocedural computed tomography (CT) imaging. A total of 46 aluminum fiducial markers were positioned in a 60 × 45 mm grid, in a single plane, around a microwave ablation antenna in each of six ex vivo bovine liver samples. Ablations were performed for 10 min at 100 W. CT data of the liver sample were acquired every 30 s during ablation. Fiducial motion between acquisitions was tracked in postprocessing and used to calculate measures of tissue contraction and contraction rates. The spatial distribution and temporal evolution of contraction were analyzed. Fiducial displacement indicated that the zone measured postablation was 8.2 ± 1.8 mm (∼20%) smaller in the radial direction and 7.1 ± 1.0 mm (∼10%) shorter in the longitudinal direction than the preablation tissue dimension. Therefore, the total ablation volume was reduced from its preablation value by approximately 45%. Very little longitudinal contraction was noted in the distal portion of the ablation zone. Central tissues contracted more than 60%, which was near an estimated limit of ∼70% based on initial water content. More peripheral tissues contracted only 15% in any direction. Contraction rates peaked during the first 60 s of heating with a roughly exponential decay over time. Ablation zones measured posttreatment are significantly smaller than the pretreatment tissue dimensions. Tissue contraction is spatially dependent, with the greatest effect occurring in the central ablation zone. Contraction rate peaks early and decays over time.

Liquid chromatography/tandem mass spectrometry method to determine boldenone in bovine liver tissues.

Boldenone, an androgenic steroid, is forbidden for use in meat production in most countries worldwide. Residues of this drug in food present a potential risk to consumers. A sensitive LC/MS/MS method for analysis of 17β-boldenone using boldenone-d3 as an internal standard was developed. An enzymatic hydrolysis and extraction using ethyl acetate, methanol, and hexane were performed in the sample preparation. Parameters such as decision limit (CCα), detection capability (CCβ), precision, recovery, and ruggedness were evaluated according to the Brazilian Regulation 24/2009 (equivalent to European Union Decision 2002/657/EC) and International Organization for Standardization/International Electrotechnical Commission 17025:2005. CCα and CCβ were determined to be 0.17 and 0.29 μg/kg, respectively. Average recoveries from bovine liver samples fortified with 1, 1.5, and 2 μg/kg were around 100%. A complete statistical analysis was performed on the results obtained, including an estimation of the method uncertainty. The method is considered robust after being subjected to day-to-day analytical variations and has been used as a standard method in Brazil to report boldenone levels in bovine liver.

Spatial characterization of proteolytic enzyme activity in the foregut region of the adult necrophagous fly, Protophormia terraenovae

The spatial distribution of proteolytic enzymes in the adult foregut of Protophormia terraenovae was studied in the context of protein digestion and regurgitation. Based on substrate specificity, pH optima, and use of specific protease inhibitors, all adults tested displayed enzyme activity in the foregut consistent with pepsin, trypsin and chymotrypsin. Chymotrypsin-like and trypsin-like enzyme activity were detected in all gut fluids and tissues tested, with chymotrypsin displaying the highest activity in saliva and salivary gland tissue, whereas maximal trypsin activity was evident in the crop. Pepsin-like activity was only evident in crop fluids and tissues. The activity of all three enzymes was low or undetectable (pepsin) in the fluids and tissue homogenates derived from the esophagus and cardia of any of the adults assayed. Fed adult females displayed higher enzyme activities than fed males, and the activity of all three enzymes were much more prevalent in fed adults than starved. The pH optimum of the trypsin-like enzyme was between pH 7.0 and 8.0; chymotrypsin was near pH 8.0; and maximal pepsin-like activity occurred between pH 1.0 and 2.0. Regurgitate from fed adult females displayed enzyme activity consistent with the proteolytic enzymes detected in crop gut fluids. Enzymes in regurgitate were not derived from food sources based on assays of bovine liver samples. These latter observations suggest that adult flies release fluids from foregut when encountering dry foods, potentially as a means to initiate extra-oral digestion.

Detection of Enrofloxacin Residue in Livers of Livestock Animals Obtained from a Slaughterhouse in Mosul City

Ninety liver samples of poultry, sheep and cattle, 30 each, were obtained from meat retail markets at Mosul city in Iraq, and were analyzed for enrofloxacin residue by using Enzyme Linked Immunosorbent Assay, ELISA [ Schen Zhen Lvshiynan Biotechnology Co., LTD. (china)]. The study revealed that the range and mean of residual enrofloxacin drug concentration in the examined liver samples of poultry, cattle and sheep were (0.01-10.69) (4.290); (0.03-3.61) (1.750); (0.02-1.32) (1.687) mg/ kg respectively. Also the study revealed that 30 (33.31%) of poultry liver samples tested positive, 8 (8.88%) of cattle samples were positive, and 5 (5.55%) of sheep samples were positive for enrofloxacin. 17 (56.66%) of the poultry samples exceeded the maximum residues limits (MRL), as did 8 (26.61%) of cattle samples, and 5(16.6%) of sheep samples. Our results have shown that the maximum mean enrofloxacin concentration was found in poultry livers (4.290) and the minimum mean was in the ovine liver samples (1.687) while bovine livers were (1.750). The difference between the residue of enrofloxacin of poultry liver samples and that of bovine and ovine liver samples was significant at (P<0.05).

Application of high-performance liquid chromatography–UV detection to quantification of clenbuterol in bovine liver samples

A method for the determination of clenbuterol (CLB) concentration in bovine liver by reversed-phase high-performance liquid chromatography (HPLC) with UV detection was developed. The sample was extracted with acetonitrile and isopropanol, followed by HPLC analysis. A reverse-phase column C18 was used, with a UV detector at 214 nm and 0.05 M NaH2PO4 (pH 3.0)/acetonitrile (85:15, v/v) as the mobile phase. The accuracy of the analytical method was estimated by spiking bovine liver samples with three different concentrations of CLB (5.24 ng/g, 20.98 ng/g, and 41.96 ng/g) and recovery of 111.7%, 82.0%, and 84.8%, respectively, was obtained. The precision of the method was estimated by the relative standard deviation, which was < 4.74%. The limit of detection and quantification of CLB were 0.20 ng/g and 0.42 ng/g of liver sample, respectively, and the retention time was 24.82 minutes. The recent discovery of CLB contamination in Mexican food led to the specific inspection of a distribution center for this β-agonist, involving the analysis of a total of 78 bovine liver samples. Of all samples screened, 62% of them had concentrations above the maximum residue limit of 0.6 ng/g set by the United Nations Food and Agricultural Organization for CLB. The analytical method was found to be rapid, sensitive, accurate, repeatable, and reproducible, and could be applied to the measurement of CLB concentration in bovine liver.

광주지역 생식용 소 부산물의 위생관리 실태 조사

A total of 301 samples of bovine liver, spleen and omasum were collected from butchers and restaurants in Gwangju, Korea during 2012 and all samples were subjected to bacteriological examination and antibiotic residues. Also, this study was performed to survey the consciousness for hygiene of livestock workers who are handling bovine by-products in Gwangju. The detection rate of aerobic plate count (APC) was higher in summer than in other seasons in all by-products (P=0.000). The detection rate of E. coli count was lower in the liver than the spleen and omasum (P=0.000). Twenty four of the samples (8.0%) were contaminated with S. aureus while one spleen sample (0.3%) was contaminated with L. monocytogenes and finally 10 (3.3%) of the liver and omasum samples were contaminated with Cl. perfringens. Five of the twenty-four S. aureus isolates harbored enterotoxin gene. However, the cpe gene of Cl. perfingens was not detected among any of the 10 isolates. Antibiotic residues were not detected in the liver samples. The consciousness survey's results showed that most of them (58.8%) were safe.

An FAAS assay utilizing graphene nanosheets-based solid-phase extraction for preconcentration and determination of trace amounts of palladium

A solid-phase extraction procedure is presented for the separation and preconcentration of trace levels of Pd(II) ion by using exfoliated graphene nanosheets (GNs). Experimental parameters such as extraction time, pH, type of eluent, sample volume and temperature were studied in detail. The Pd(II) adsorbed on the GNs was eluted with 1.5 mol L−1 sodium thiosulfite and then determined by flame atomic absorption spectrometry. The effects of potentially interfering ions on the recovery of Pd(II) were also examined. Under optimized conditions, the method provided a preconcentration factor of 100, had a linear range from 5.0 to 100 ng mL−1 of Pd(II), a limit of detection 2.1 ng mL−1, and a relative standard deviation 1.1 % at 20 ng mL−1 of Pd(II). The method was validated by the extraction and determination of Pd(II) in water, tea, lentil and bovine liver samples.

Cadmium and Lead in Grey Wolf Liver Samples: Optimisation of a Microwaveassisted Digestion Method

A microwave-assisted digestion method for the determination of cadmium (Cd) and lead (Pb) by inductively coupled plasma mass spectrometry (ICP-MS) was optimised on certified reference material (CRM) (bovine liver, BCR-185R) and wolf liver samples. Different factors influencing digestion efficiency (temperature, time, composition of the digestion mixture, sample mass) were tested. Validation included linearity (up to 200 μg L(-1) for Cd and Pb), detection (0.003 μg L(-1) for Cd and 0.035 μg L(-1) for Pb), and quantification (0.008 μg L(-1) for Cd and 0.081 μg L(-1) for Pb) limits. Good agreement between measured and certified values was achieved in all conditions, with recoveries ranging from 94 % to 111 % for Cd and from 95 % to 105 % for Pb. The precision of the method, expressed as relative standard deviation, was up to 3 % for Cd and 8 % for Pb. The best digestion parameters (260 °C, 30 min, 1 mL HNO3+4 mL H2O, 0.1 g of CRM) based on accuracy and precision were applied on two wolf liver samples to evaluate the need for the predigestion step (freeze-drying) and appropriate mass of the sample. Freeze-drying improved precision and minimising the tissue mass to 0.1 g reduced the matrix effect. Using these optimised digestion conditions, we determined Cd and Pb in 40 wolf livers collected in Croatia, and their medians (0.055 μg g(-1) and 0.107 μg g(-1), respectively) were in the range of previously reported data for the grey wolf.

Determination of cocaine in postmortem human liver exposed to overdose. Application of an innovative and efficient extraction/clean up procedure and gas chromatography–mass spectrometry analysis

A simple and efficient method was developed for the determination of cocaine in post-mortem samples of human liver via solid–liquid extraction with low temperature partitioning (SLE–LTP) and analysis by gas chromatography coupled to mass spectrometry (GC–MS). The extraction procedure was optimized by evaluating the influence of the following variables: pH of the extract, volume and composition of the extractor solvent, addition of a sorbent material (PSA: primary–secondary amine) and NaCl to clean up and increase the ionic strength of the extract. A bovine liver sample that was free of cocaine was used as a blank for the optimization of the SLE–LTP extraction procedure. The highest recovery was obtained when crushed bovine liver (2g) was treated with 2mL of ultrapure water plus 8mL of acetonitrile at physiological pH (7.4). The results also indicated no need for using PSA and NaCl. The complete analytical procedure was validated for the following figures of merit: selectivity, lower limit of quantification (LLOQ), calibration curve, recovery, precision and accuracy (for within-run and between-run experiments), matrix effect, dilution integrity and stability. The within-run and between-run precision (at four levels) varied from 2.1% to 9.4% and from 4.0% to 17.0%, respectively. A maximum deviation of 11.62% for the within-run and between-run accuracies in relation to the nominal concentrations was observed. Moreover, the LLOQ value for cocaine was 50.0ngg−1 whereas no significant effects were noticed in the assays of dilution integrity and stability. To assess its overall performance, the optimized method was applied to the analysis of eight human liver samples collected from individuals who died due to the abusive consumption of cocaine. Due to the existence of a significant matrix effect, a blank human liver was used to construct a matrix-matched analytical curve. The concentrations of cocaine found in these samples ranged from 333.5 to 5969ngg−1.

Spatial specificity and sensitivity of passive cavitation imaging for monitoring high-intensity focused ultrasound thermal ablation in ex vivo bovine liver

Passive cavitation images (PCIs) generated from scattered acoustic waves are a potential technique for monitoring lesion formation during high-intensity focused ultrasound (HIFU) thermal ablation. HIFU lesion prediction by PCIs was assessed in ex vivo bovine liver samples (N = 14) during 30-s sonications with 1.1-MHz continuous-wave ultrasound (1989 W/cm2 estimated spatial-peak intensity). Treated samples were sectioned, optically scanned, and the HIFU lesions segmented based on tissue discoloration. During each insonation, a 192-element, 7-MHz linear array (L7/Iris 2, Ardent Sound) passively recorded emissions from a plane containing the HIFU propagation axis oriented parallel to the image azimuth direction. PCIs were formed from beamformed A-lines filtered into fundamental, harmonic, ultraharmonic, and inharmonic frequency bands. Lesion prediction was tested using binary classification of local tissue ablation based on thresholded PCIs, with spatial specificity and sensitivity of lesion prediction quantified by the area under receiver operating characteristic curves (AUROC). Tadpole-shaped lesions were best predicted by harmonic emissions (AUROC = 0.76), prefocal lesions were best predicted by harmonic or ultraharmonic emissions (AUROC = 0.86), and cigar-type focal lesions were best predicted by fundamental and harmonic emissions (AUROC = 0.65). These results demonstrate spatial specificity and sensitivity when predicting HIFU lesions with PCIs. [Work supported in part by NIH grants F32HL104916 and R21EB008483.]

Establishing reference ranges for sulfur concentrations in bovine liver and kidney samples

Sulfur toxicosis is a common cause of polioencepha- lomalacia in cattle. Diagnosis requires comprehensive determination of dietary sulfur intake, which may not be possible if feedstuffs are no longer available. The goal of this study was to establish reference ranges for concentrations of sulfur in liver and kidney samples from cattle dying of causes unrelated to sulfur toxicosis. Samples were collected from 71 cattle and assessed for sulfur content using inductive coupled plasma atomic- emission spectroscopy. Cattle demonstrating neurologic signs or gross or histologic lesions of the brain were excluded from the study. Sulfur concentrations were calculated on a wet- and dry-matter basis. Values were examined for Gaussian distribution, and 95% confidence intervals were calculated using the mean for normally distributed values and the median for non-normally distributed values. The 95% confidence interval for liver sulfur was 4,522 to 9,982 ppm dry-matter (1,270 to 2,640 ppm wet-matter). The 95% Cl for kidney sulfur was 5,070 to 19,017 ppm dry-matter (1,187 to 2,918 ppm wet-matter). Correlation assessments suggest that dry- matter liver analysis may be the best defined and most reliable measure of sulfur burden. Additional research is needed to assess concentrations of sulfur present in the liver and kidney of cattle with sulfur toxicosis, the impact of dietary intake on tissue concentrations, and to determine whether postmortem sulfur measurement is a viable method of diagnosing sulfur toxicosis.

Technique for measuring laser radiation intensity in biological tissues

AbstractLaser methods, such as laser-induced fluorescence diagnostics, photodynamic therapy (PDT), and hyperthermia, are finding increasing use in medicine. Irradiation can be performed both with and without contact on the tissue surface. In the case of contact irradiation, especially when laser radiation is introduced into biological tissue through an optical fiber, it is important to know the processes taking place at the irradiation fiber end. These processes affect diffusely reflected radiation which returns to the fiber. By analyzing backscattered radiation, we can evaluate the quality of the radiation procedure and the state of the fiber end. The objectives of this study were to develop a method and device for measuring backscattered radiation power and using this method, to determine the time and temperature ranges realized in PDT and hyperthermia.Light propagation is discussed in bent optical fibers. A technique is proposed for measuring laser radiation intensity in the optical fiber bend. Based on this technique, a system was developed for monitoring the laser radiation dose absorbed in biological tissues. We studied samples of bovine liver, muscle and brain tissues. Experiments were performed using a 675 nm, 100–2200 mW continuous wave semi-conductor laser. Laser radiation was delivered through a silica/polymer optical fiber. Data concerning the temperature and transmitted radiation intensity was acquired.Modeling of the light propagation in a bent optical fiber showed that the sensitivity of the method depends on the position of the photodetectors, but is independent of the loop number of the optical fiber. The results of experiments are presented using different types of biological tissues. We obtained the experimental dependencies of backward and transmitted radiation intensities and the temperature of the tissue surface in the irradiated region on the irradiation time measured with a flat-end fiber. The characteristic ranges of tissue heating caused by irradiation were determined for use in clinical practice.The optical parameters of biological tissues change with increasing temperature. This affects the intensity of transmitting radiation and diffuse radiation entering the fiber. The change in the backscattered radiation intensity greatly depend on the temperature of the irradiated area. The control of the irradiation of biological objects provides an efficient delivery of laser radiation to biological tissues and increases hyperthermia and PDT treatment effect.

Spatial specificity and sensitivity of passive cavitation imaging for monitoring high-intensity focused ultrasound thermal ablation in ex vivo bovine liver.

Passive cavitation images (PCIs) generated from scattered acoustic waves are a potential technique for monitoring lesion formation during high-intensity focused ultrasound (HIFU) thermal ablation. HIFU lesion prediction by PCIs was assessed in ex vivo bovine liver samples (N=14) during 30-s sonications with 1.1-MHz continuous-wave ultrasound (1989 W/cm^2 estimated spatial-peak intensity). Treated samples were sectioned, optically scanned, and the HIFU lesions segmented based on tissue discoloration. During each insonation, a 192-element, 7-MHz linear array (L7/Iris 2, Ardent Sound) passively recorded emissions from a plane containing the HIFU propagation axis oriented parallel to the image azimuth direction. PCIs were formed from beamformed A-lines filtered into fundamental, harmonic, ultraharmonic, and inharmonic frequency bands. Lesion prediction was tested using binary classification of local tissue ablation based on thresholded PCIs, with spatial specificity and sensitivity of lesion prediction quantified by the area under receiver operating characteristic curves (AUROC). Tadpole-shaped lesions were best predicted by harmonic emissions (AUROC=0.76), prefocal lesions were best predicted by harmonic or ultraharmonic emissions (AUROC=0.86), and cigar-type focal lesions were best predicted by fundamental and harmonic emissions (AUROC=0.65). These results demonstrate spatial specificity and sensitivity when predicting HIFU lesions with PCIs.

Generation of uniform lesions in high intensity focused ultrasound ablation

High intensity focused ultrasound (HIFU) is emerging as an effective oncology treatment modality according to the clinical experience in the last decade. The temperature at the focus can reach over 65°C within seconds, denaturing cellular proteins and resulting in coagulative necrosis. HIFU parameters are usually kept the same for each treatment spot in tumor ablation. Because of the thermal diffusion from nearby spots, the lesion size will gradually increase as the HIFU therapy progresses, which leads to insufficient treatment of initial spots and over exposure of later ones. From the viewpoint of the physician, uniform lesions with the least energy exposure and the least energy are preferred in tumor ablation. In this study, an algorithm was developed to determine the number of HIFU pulses delivered to each spot in order to generate uniform lesions that fill the region-of-interest completely. The exposure energies required using different scanning pathways (raster scanning, spiral scanning from the center to the outside, and spiral scanning from the outside to the center), spot spacing (1mm, 2mm, 4mm, and 6mm) and motion time (from 0s to 400s) were compared with each other. It is found that spiral scanning from the outside to the center with spot spacing of 2mm and motion time less than 10s needs the least numbers of pulses or HIFU energy in uniform lesion production with the minimal temperature elevation. In addition, the effects of thermal properties of tissue (i.e., specific heat capacity, convective heat transfer coefficient, and thermal conductivity) on HIFU ablation were investigated in order to determine the HIFU treatment planning for various targets. Uniform lesion production in the transparent gel phantom and ex vivo bovine liver samples using the proposed algorithm proved effective and accord with the simulation for different scanning pathways by an extracorporeal clinical HIFU system. Therefore, dynamically adjusting ultrasound exposure energy can improve the efficacy and safety of HIFU ablation, and the treatment planning depends on the scanning protocol and thermal properties of the target.

Simultaneous determination of eight corticosteroids in bovine tissues using liquid chromatography–tandem mass spectrometry

This paper describes a newly developed method for the simultaneous determination of eight corticosteroid residues in bovine muscle, liver and kidney samples using liquid chromatography–tandem mass spectrometry (LC–MS/MS). The determination of methylprednisone, the main metabolite of methylprednisolone, in bovine tissues using LC–MS/MS is carried out for the first time. The method development demonstrates that the pH is important in optimizing the sample preparation. Tests performed using different solid-phase extraction (SPE) cartridges were enabled to produce conditions for reducing the matrix effects (ion suppression and enhancement) of analysis. Acidic condition and mixed-mode cation exchange SPE columns resulted in the most suitable clean-up for muscle and liver, and also yielded acceptable results for kidney. The enhanced sample clean-up resulted in excellent clear baselines of ion transitions, and therefore, a higher delta electron multiplier voltage (ΔEMV) could be set in the MS/MS detector. The application of 500V of ΔEMV improved the signal responses, however, the noise level did not change, and consequently, the overall sensitivity and analytical limits (limit of detection, limit of quantification) could be enhanced. In the HPLC separation, the recently introduced Kinetex phenyl-hexyl core–shell type column was used that enabled baseline separation for dexamethasone and its β-epimer, betamethasone. Dexamethasone and betamethasone were eluted within 12min and such reduced retention, obtained with core–shell HPLC type column, further enhanced the sensitivity. The method was validated according to the European Union (EU) 2002/657/EC Decision; the studied parameters met the EU standards. The decision limits and limit of detections were calculated in each matrix for all corticosteroids and varied from 0.01 to 13.3μg/kg and from 0.01 to 0.1μg/kg, respectively.

Correction of radiation absorption on biological samples using Rayleigh to Compton scattering ratio

The aim of this work was to develop a method to correct the absorbed radiation (the mass attenuation coefficient curve) in low energy (E<30keV) applied to a biological matrix based on the Rayleigh to Compton scattering ratio and the effective atomic number. For calibration, scattering measurements were performed on standard samples of radiation produced by a gamma-ray source of 241Am (59.54keV) also applied to certified biological samples of milk powder, hay powder and bovine liver (NIST 1557B). In addition, six methods of effective atomic number determination were used as described in literature to determinate the Rayleigh to Compton scattering ratio (R/C), in order to calculate the mass attenuation coefficient. The results obtained by the proposed method were compared with those obtained using the transmission method. The experimental results were in good agreement with transmission values suggesting that the method to correct radiation absorption presented in this paper is adequate for biological samples.

Effect of ethanol injection on cavitation and heating of tissues exposed to high-intensity focused ultrasound

Cavitation activity and temperature rise have been investigated in a tissue-mimicking material and excised bovine liver treated with ethanol and insonated with a 0.825 MHz focused acoustic transducer. The acoustic power was varied from 1.3 to 26.8 W to find the threshold leading to the onset of inertial cavitation. Cavitation events were quantified by three independent techniques: B-mode ultrasound imaging, needle hydrophone measurements and passive cavitation detection. Temperature in or near the focal zone was measured by thermocouples embedded in the samples. The results of this study indicate that the treatment of tissue phantoms and bovine liver samples with ethanol reduces their threshold power for inertial cavitation. This in turn leads to a sudden rise in temperature in ethanol-treated samples at a lower acoustic power than that in untreated ones. The analysis of passive cavitation detection data shows that once the threshold acoustic power is reached, inertial cavitation becomes a major contributor to acoustic scattering in ethanol-treated phantoms and bovine liver samples as compared to control. This study opens up the possibility of improved tumor ablation therapy via a combination of percutaneous ethanol injection and high-intensity focused ultrasound.