Journal of the Science of Food and Agriculture, 2020
BACKGROUNDHeat treatment is the most common practice for the microbiological safety of milk; henc... more BACKGROUNDHeat treatment is the most common practice for the microbiological safety of milk; hence, determination of the heat treatment of milk is essential. Also, mislabeling or adulteration of expensive milk samples, like ewe or goat milk, with cow's milk is a growing problem in the dairy market. Thus, the determination of the authenticity of milk samples has crucial importance for both producers and consumers. The aim of this study was to discriminate milk samples using Raman spectroscopy with partial least squares discriminant analysis (PLS‐DA), first with regard to whether the milk was heat‐treated or not, and second with regard to species (cow, goat, ewe, mixture (adulterated)) in both raw and pasteurized milk.RESULTSFirst, discrimination of milk samples as raw or pasteurized was achieved using PLS‐DA. Both in calibration and prediction models, high sensitivity and specificity values were obtained for raw and pasteurized milk samples. Second, the proposed method also discr...
Antibiotics are one of the most widely used types of drugs in pharmaceutics. However, efficiency ... more Antibiotics are one of the most widely used types of drugs in pharmaceutics. However, efficiency of these drugs has decreased recently owing to the threat of antibiotic resistance. One of the important factors causing antibiotic resistance is the excessive use of antibacterials in animals. Therefore, detection of antibiotics in foods of animal origin is crucial. The aim of this study was to develop a novel whole‐cell based bioassay to be used for detection of some antibiotics. Green fluorescent protein (GFP)‐expressing Escherichia coli cells were used as a recognition agent, and antibiotic detection was carried out by pursuing the inhibition rate of fluorescence intensity as a result of the inhibition of viable cells by the time of progress. The performance of bioassay was tested for different antibiotics, and the obtained results showed that the developed method can be used successfully for detection of ampicillin, benzylpenicillin, gentamicin, neomycin, and tetracycline with the l...
Objective: Better understanding of the biodynamics of peri-implant sulcular fluid (PISF) may be a... more Objective: Better understanding of the biodynamics of peri-implant sulcular fluid (PISF) may be an important concern both from a clinical perspective and research standing point. As peri-implant sulcular fluid volume is known to be effected by an array of factors, the aim of the present study was to analyze the potential impact of various peri-implant site-related and dental implant-related factors on PISF volume. Methods: PISF was obtained from a total of 128 implant sites and electronic volume quantification was performed by use of Periotron 8000. These sites were divided into different subgroups based on the presence/ severity of peri-implant inflammation, probing depths (PD), implant features (diameter and length), location of implant (maxilla or mandible) and surgical preference (one-stage or two-stage surgery). Differences between these subgroups were statistically analyzed. Results: PISF volume was higher at sites with peri-implant mucositis (0,190 l) and peri-implantitis (0,...
Increased oxidative stress and hemorheological disturbances may play very important roles in the ... more Increased oxidative stress and hemorheological disturbances may play very important roles in the development of microangiopathies in diabetes mellitus. This study was designed to determine the healing effect of melatonin on hemorheological parameters and diabetic nephropathy in streptozotocin (STZ)-induced diabetic rats. Wistar male rats were divided into four groups as control, untreated-diabetic, melatonin-treated control and melatonin-treated diabetic rats. Diabetes was induced by injecting streptozotocin (45 mg/kg, i.p.). Fourteen weeks after inducement of diabetes, melatonin (10 mg/kg) was administered intraperitoneally for 5 days to the rats. Erythrocyte deformability and aggregation were measured by laser differaction analysis (LORCA). Diabetic nephropathy was assessed by histopathologic evaluation and TUNEL stain in the diabetic kidney. Decreased erythrocyte deformability and increased erythrocyte aggregation indices were determined in the diabetic group. Melatonin treatment...
We recently encountered a 35-year old man who suffered from frequent hypoglycemia. His blood test... more We recently encountered a 35-year old man who suffered from frequent hypoglycemia. His blood test revealed the presence of high and suppressed level of insulin with supressed C-peptide levels, hypothalamic-pituitary axis was normal response in hypoglycemia and negative for anti-insulin antibody. Endocrinological and imaging data eliminated the possibility of insulinoma. His symptoms responded well to the therapy of prednisolone (60 mg/day) and plasmapheresis. We followed up the patient over the subsequent 6 months without remarkable lesions. He has had no further recurrences of hypoglycemia. We believe that the antiinsulin receptor antibody might have induced hypoglycemia in this patient.
In this study, a new, sensitive, and rapid assay was developed to quantitatively measure the prot... more In this study, a new, sensitive, and rapid assay was developed to quantitatively measure the proteolytic enzyme activity using the surface-enhanced Raman scattering (SERS) probe. Two different shapes of gold nanoparticles, gold nanosphere and nanorod particles were produced. SERS label, comprising self-assembled monolayers (SAMs) of Raman reporter molecule (5,5-Dithiobis (2-Nitrobenzoic acid), DTNB), was coated on the surface of the nanoparticles. Two different SERS-based analysis platforms were designed using gold-coated glass slide and polystyrene microtiter plate. The calibration curves were obtained by plotting the intensity of the SERS signal of symmetric NO(2) stretching of DTNB at 1326 cm(-1) vs. the protease concentration. The effects of nanoparticle geometry and assay platform on the protease assay were investigated and the best working combination of the parameters was selected as rod shaped SERS probe and gold-coated glass slide. The correlation between the protease activity and SERS signal was found to be linear within the range of 0.1-2 mU/mL (R(2)=0.979). The limit of detection (LOD) and limit of quantification (LOQ) values of the validated method were found as 0.43 and 1.30 mU/mL, respectively. The intra-day and inter-day precisions of the method, as relative standard deviation (RSD), were determined as 2.5% and 3.6%, respectively. The developed method was successfully applied for quantitative analysis of the commercial enzyme preparate that is used in cheese making process. It was also used for investigation of substrate specificity of protease enzyme towards the casein and bovine serum albumin. The proposed method has a flexibility to try different substrates for the detection of various enzyme activities.
In this study, the utility of Raman spectroscopy (RS) with chemometric methods for quantification... more In this study, the utility of Raman spectroscopy (RS) with chemometric methods for quantification of multiple components in the fermentation process was investigated. Vinegar, the product of a two stage fermentation, was used as a model and glucose and fructose consumption, ethanol production and consumption and acetic acid production were followed using RS and the partial least squares (PLS) method. Calibration of the PLS method was performed using model solutions. The prediction capability of the method was then investigated with both model and real samples. HPLC was used as a reference method. The results from comparing RS-PLS and HPLC with each other showed good correlations were obtained between predicted and actual sample values for glucose (R(2)=0.973), fructose (R(2)=0.988), ethanol (R(2)=0.996) and acetic acid (R(2)=0.983). In conclusion, a combination of RS with chemometric methods can be applied to monitor multiple components of the fermentation process from start to finish with a single measurement in a short time.
Biochemical and Biophysical Research Communications, 1973
The midpoint oxidation-reduction potential of the EPR detectable centre of the molybdenum iron pr... more The midpoint oxidation-reduction potential of the EPR detectable centre of the molybdenum iron protein of Chromatium nitrogenase has been measured. Two centres with identical EPR spectra but different midpoint potentials were detected. The measured midpoint potentials are (1) Em7.5 = −60 mV and (2) Em7.5 = −260 mV. The midpoint potentials were not affected by other components of the nitrogen fixing system.
A new method based on surface-enhanced Raman spectroscopy (SERS) has been developed for sensitive... more A new method based on surface-enhanced Raman spectroscopy (SERS) has been developed for sensitive and rapid detection of melamine. Spherical magnetic-core gold-shell nanoparticles (AuNPs) and rod-shaped gold nanoparticles (nanorods) labeled with a Raman-active compound were used to form a complex with the melamine molecules. 5,5'-Dithiobis(2-nitrobenzoic acid) was used as Raman-active compound because it is readily adsorbed by a gold nanoparticle surface forming a self-assembled monolayer (SAM) and has strong Raman scattering at 1330 cm(-1), because of the symmetric NO(2) stretch. The calibration curve was obtained by plotting Raman band area at 1330 cm(-1) against melamine concentration. A linear relationship was obtained with a high determination coefficient (R(2)=0.997). The method was validated for linearity, sensitivity, precision (intra-day and inter-day repeatability), and recovery. In the model system, the limits of detection (LOD) and quantification (LOQ) were 0.38 and 1.27 mg L(-1), respectively. For melamine-spiked milk samples, LOD and LOQ values were 0.39 mg L(-1) and 1.30 mg L(-1), respectively. Intra and inter-day precision were 3.73 and 4.94 %, respectively. This method was applied to samples of skimmed milk that had been spiked with melamine at different concentrations. The recovery of the method was 95-109 % in the concentration range 2-15 mg L(-1), and average RSD was 1.71 %. Total analysis time was less than 15 min.
Journal of the Science of Food and Agriculture, 2020
BACKGROUNDHeat treatment is the most common practice for the microbiological safety of milk; henc... more BACKGROUNDHeat treatment is the most common practice for the microbiological safety of milk; hence, determination of the heat treatment of milk is essential. Also, mislabeling or adulteration of expensive milk samples, like ewe or goat milk, with cow's milk is a growing problem in the dairy market. Thus, the determination of the authenticity of milk samples has crucial importance for both producers and consumers. The aim of this study was to discriminate milk samples using Raman spectroscopy with partial least squares discriminant analysis (PLS‐DA), first with regard to whether the milk was heat‐treated or not, and second with regard to species (cow, goat, ewe, mixture (adulterated)) in both raw and pasteurized milk.RESULTSFirst, discrimination of milk samples as raw or pasteurized was achieved using PLS‐DA. Both in calibration and prediction models, high sensitivity and specificity values were obtained for raw and pasteurized milk samples. Second, the proposed method also discr...
Antibiotics are one of the most widely used types of drugs in pharmaceutics. However, efficiency ... more Antibiotics are one of the most widely used types of drugs in pharmaceutics. However, efficiency of these drugs has decreased recently owing to the threat of antibiotic resistance. One of the important factors causing antibiotic resistance is the excessive use of antibacterials in animals. Therefore, detection of antibiotics in foods of animal origin is crucial. The aim of this study was to develop a novel whole‐cell based bioassay to be used for detection of some antibiotics. Green fluorescent protein (GFP)‐expressing Escherichia coli cells were used as a recognition agent, and antibiotic detection was carried out by pursuing the inhibition rate of fluorescence intensity as a result of the inhibition of viable cells by the time of progress. The performance of bioassay was tested for different antibiotics, and the obtained results showed that the developed method can be used successfully for detection of ampicillin, benzylpenicillin, gentamicin, neomycin, and tetracycline with the l...
Objective: Better understanding of the biodynamics of peri-implant sulcular fluid (PISF) may be a... more Objective: Better understanding of the biodynamics of peri-implant sulcular fluid (PISF) may be an important concern both from a clinical perspective and research standing point. As peri-implant sulcular fluid volume is known to be effected by an array of factors, the aim of the present study was to analyze the potential impact of various peri-implant site-related and dental implant-related factors on PISF volume. Methods: PISF was obtained from a total of 128 implant sites and electronic volume quantification was performed by use of Periotron 8000. These sites were divided into different subgroups based on the presence/ severity of peri-implant inflammation, probing depths (PD), implant features (diameter and length), location of implant (maxilla or mandible) and surgical preference (one-stage or two-stage surgery). Differences between these subgroups were statistically analyzed. Results: PISF volume was higher at sites with peri-implant mucositis (0,190 l) and peri-implantitis (0,...
Increased oxidative stress and hemorheological disturbances may play very important roles in the ... more Increased oxidative stress and hemorheological disturbances may play very important roles in the development of microangiopathies in diabetes mellitus. This study was designed to determine the healing effect of melatonin on hemorheological parameters and diabetic nephropathy in streptozotocin (STZ)-induced diabetic rats. Wistar male rats were divided into four groups as control, untreated-diabetic, melatonin-treated control and melatonin-treated diabetic rats. Diabetes was induced by injecting streptozotocin (45 mg/kg, i.p.). Fourteen weeks after inducement of diabetes, melatonin (10 mg/kg) was administered intraperitoneally for 5 days to the rats. Erythrocyte deformability and aggregation were measured by laser differaction analysis (LORCA). Diabetic nephropathy was assessed by histopathologic evaluation and TUNEL stain in the diabetic kidney. Decreased erythrocyte deformability and increased erythrocyte aggregation indices were determined in the diabetic group. Melatonin treatment...
We recently encountered a 35-year old man who suffered from frequent hypoglycemia. His blood test... more We recently encountered a 35-year old man who suffered from frequent hypoglycemia. His blood test revealed the presence of high and suppressed level of insulin with supressed C-peptide levels, hypothalamic-pituitary axis was normal response in hypoglycemia and negative for anti-insulin antibody. Endocrinological and imaging data eliminated the possibility of insulinoma. His symptoms responded well to the therapy of prednisolone (60 mg/day) and plasmapheresis. We followed up the patient over the subsequent 6 months without remarkable lesions. He has had no further recurrences of hypoglycemia. We believe that the antiinsulin receptor antibody might have induced hypoglycemia in this patient.
In this study, a new, sensitive, and rapid assay was developed to quantitatively measure the prot... more In this study, a new, sensitive, and rapid assay was developed to quantitatively measure the proteolytic enzyme activity using the surface-enhanced Raman scattering (SERS) probe. Two different shapes of gold nanoparticles, gold nanosphere and nanorod particles were produced. SERS label, comprising self-assembled monolayers (SAMs) of Raman reporter molecule (5,5-Dithiobis (2-Nitrobenzoic acid), DTNB), was coated on the surface of the nanoparticles. Two different SERS-based analysis platforms were designed using gold-coated glass slide and polystyrene microtiter plate. The calibration curves were obtained by plotting the intensity of the SERS signal of symmetric NO(2) stretching of DTNB at 1326 cm(-1) vs. the protease concentration. The effects of nanoparticle geometry and assay platform on the protease assay were investigated and the best working combination of the parameters was selected as rod shaped SERS probe and gold-coated glass slide. The correlation between the protease activity and SERS signal was found to be linear within the range of 0.1-2 mU/mL (R(2)=0.979). The limit of detection (LOD) and limit of quantification (LOQ) values of the validated method were found as 0.43 and 1.30 mU/mL, respectively. The intra-day and inter-day precisions of the method, as relative standard deviation (RSD), were determined as 2.5% and 3.6%, respectively. The developed method was successfully applied for quantitative analysis of the commercial enzyme preparate that is used in cheese making process. It was also used for investigation of substrate specificity of protease enzyme towards the casein and bovine serum albumin. The proposed method has a flexibility to try different substrates for the detection of various enzyme activities.
In this study, the utility of Raman spectroscopy (RS) with chemometric methods for quantification... more In this study, the utility of Raman spectroscopy (RS) with chemometric methods for quantification of multiple components in the fermentation process was investigated. Vinegar, the product of a two stage fermentation, was used as a model and glucose and fructose consumption, ethanol production and consumption and acetic acid production were followed using RS and the partial least squares (PLS) method. Calibration of the PLS method was performed using model solutions. The prediction capability of the method was then investigated with both model and real samples. HPLC was used as a reference method. The results from comparing RS-PLS and HPLC with each other showed good correlations were obtained between predicted and actual sample values for glucose (R(2)=0.973), fructose (R(2)=0.988), ethanol (R(2)=0.996) and acetic acid (R(2)=0.983). In conclusion, a combination of RS with chemometric methods can be applied to monitor multiple components of the fermentation process from start to finish with a single measurement in a short time.
Biochemical and Biophysical Research Communications, 1973
The midpoint oxidation-reduction potential of the EPR detectable centre of the molybdenum iron pr... more The midpoint oxidation-reduction potential of the EPR detectable centre of the molybdenum iron protein of Chromatium nitrogenase has been measured. Two centres with identical EPR spectra but different midpoint potentials were detected. The measured midpoint potentials are (1) Em7.5 = −60 mV and (2) Em7.5 = −260 mV. The midpoint potentials were not affected by other components of the nitrogen fixing system.
A new method based on surface-enhanced Raman spectroscopy (SERS) has been developed for sensitive... more A new method based on surface-enhanced Raman spectroscopy (SERS) has been developed for sensitive and rapid detection of melamine. Spherical magnetic-core gold-shell nanoparticles (AuNPs) and rod-shaped gold nanoparticles (nanorods) labeled with a Raman-active compound were used to form a complex with the melamine molecules. 5,5'-Dithiobis(2-nitrobenzoic acid) was used as Raman-active compound because it is readily adsorbed by a gold nanoparticle surface forming a self-assembled monolayer (SAM) and has strong Raman scattering at 1330 cm(-1), because of the symmetric NO(2) stretch. The calibration curve was obtained by plotting Raman band area at 1330 cm(-1) against melamine concentration. A linear relationship was obtained with a high determination coefficient (R(2)=0.997). The method was validated for linearity, sensitivity, precision (intra-day and inter-day repeatability), and recovery. In the model system, the limits of detection (LOD) and quantification (LOQ) were 0.38 and 1.27 mg L(-1), respectively. For melamine-spiked milk samples, LOD and LOQ values were 0.39 mg L(-1) and 1.30 mg L(-1), respectively. Intra and inter-day precision were 3.73 and 4.94 %, respectively. This method was applied to samples of skimmed milk that had been spiked with melamine at different concentrations. The recovery of the method was 95-109 % in the concentration range 2-15 mg L(-1), and average RSD was 1.71 %. Total analysis time was less than 15 min.
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