Several extracellular proteins have been reported to be phosphorylated. Previous studies of our l... more Several extracellular proteins have been reported to be phosphorylated. Previous studies of our laboratory indicated that laminin-1 can be phosphorylated by protein kinase A (PKA). Moreover, it has been reported that protein kinase C (PKC), although known to be intracellular, can phosphorylate extracellular proteins in the case of cellular damage and/or platelet activation. In the present study we examined the possibility of laminin-1 serving as a substrate of PKC. Amino acid analysis revealed that laminin-1 is phosphorylated by this enzyme on serine residues. Self assembly, heparin binding, and cell attachment on the phosphorylated molecule were then studied. Phosphorylated laminin-1 showed an increased and more rapid self assembly than the non-phosphorylated molecule. Heparin binding and cell attachment experiments indicated enhanced heparin and cell binding capacity of the phosphorylated molecule in comparison to the non- phosphorylated control. These results indicate that lamini...
International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity, 1999
To examine possible changes of leptin concentrations after the acute administration of glucose or... more To examine possible changes of leptin concentrations after the acute administration of glucose orally (OGTT). Seventy-five grams of glucose were administered per os in one group of obese and normal weight individuals and concentrations of glucose, insulin and leptin were measured at 0, 30, 60, 90 and 120 min. In an age matched control group of individuals with similar BMI water was given and leptin concentrations were measured before and after 30, 60, 90 and 120 min. Twenty-seven obese women aged 34+/-1.57 y with BMI 37.1+/-0.8 kg/m2 and 16 normal weight women, aged 32+/-1.13 y with BMI 23.6+/-0.3 kg/m2 formed the experimental group, while 10 obese and 10 normal weight females with similar age and BMI were used as controls. Weight, height, BMI, body fat, glucose, insulin and leptin at baseline and during OGTT. Variations of the above parameters were calculated from the area under the curve (AUC). Fasting leptin concentrations and AUC were higher in obese than in normal weight women....
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1997
The synthetic laminin pentapeptide tyrosyl-isoleucyl-glycyl-seryl-arginine (YIGSR) binds to a met... more The synthetic laminin pentapeptide tyrosyl-isoleucyl-glycyl-seryl-arginine (YIGSR) binds to a metastasis associated high-affinity laminin receptor. The aim of this study was to investigate if the radiolabeled peptide can be considered as a basis for a potential tumor-imaging radiopharmaceutical. Iodine-131-labeled YIGSR was injected in mice inoculated with Lewis Lung carcinoma, as well as in normal controls. The experimental animals were imaged on a gamma camera 10 hr after peptide administration. The same peptide was also labeled with 125I and administered to tumor-bearing and normal mice. At various time-points after peptide administration, the experimental animals were killed, and the radioactivity in the tumor, lung, liver and spleen was measured. Microscopic autoradiography was performed in histological sections of the same tissues. The tumor and the spleen of tumor-bearing animals were imaged on a gamma camera. No significant blood-pool background was detected. No other organ ...
It has been reported that metastatic melanoma cell lines selectively bind in vitro with the synth... more It has been reported that metastatic melanoma cell lines selectively bind in vitro with the synthetic laminin pentapeptide tyrosyl-isoleucyl-glycyl-seryl-arginine (YIGSR). The aim of this study was to investigate whether the same peptide can bind on melanoma cells in vivo as well. Iodine-125-labeled YIGSR was administered to B16 melanoma-bearing animals. Microscopic autoradiography of tumor and organ sections taken 24 h after peptide administration showed that the peptide did accumulate on the surface of certain tumor cells. The peptide binding cells were frequent in metastatic sites and tumors grown for 24 days and rare in tumors grown for 10 days. A similarly radiolabeled control pentapeptide (peptide DRLKY) did not bind to any tumor cell. It is suggested that the YIGSR binding tumor cells may represent a distinct melanoma cell population with a high metastatic potential.
Biochemistry and molecular biology international, 1995
A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has be... more A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has been detected in human placenta. The protein was extracted from placenta and purified by a combination of ammonium sulfate precipitation, DE-52 anion exchange chromatography, G100 gel exclusion and heparin sepharose affinity chromatography. The molecule was shown to be monomeric after treatment with beta-mercaptoethanol, and had an acidic isoelectric point. The properties of the polypeptide described in this paper (45 kDa, Pi 4-5, monomeric, heparin binding fibroblast growth factor), suggest that it may represent an as yet undescribed growth factor.
Comparative biochemistry and physiology. A, Comparative physiology, 1989
1. The mean pigeon erythrocyte life span was found to be 17-25 days by Cr51-labeled erythrocytes ... more 1. The mean pigeon erythrocyte life span was found to be 17-25 days by Cr51-labeled erythrocytes and 21 +/- 3.4 days by iron kinetics. 2. Total red blood cell volume has been calculated by Cr51-labeled erythrocytes while total plasma volume was determined both by a dye method and iron kinetic data. From these results total blood volume and total body haematocrit were found to be 0.090 +/- 0.002 ml/g body wt and 36 +/- 4.3%, respectively. 3. Venous haematocrit, haemoglobin concentration, erythrocyte count, mean corpuscular haemoglobin concentration, plasma iron and red blood cell iron have also been measured. 4. A significant difference between total body and venous haematocrit and a short mean red blood cell life span, due to ageing and to random destruction of erythrocytes were shown. 5. The above observations are compared with analogous available data for human beings and their physiological significance is discussed.
The purpose of this experimental study was to assess the effects of the immediate postoperative i... more The purpose of this experimental study was to assess the effects of the immediate postoperative intraperitoneal administration of oxaliplatin and 5-FU on the healing of colonic anastomoses in rats. Sixty rats were randomized into 4 groups of 15 rats each and were subjected to colonic anastomoses. To the 1st group, saline solution was administered immediately postoperatively, intraperitoneally. To the 2nd group, 5-FU was administered, to the 3rd group oxaliplatin and to the 4th group 5-FU and oxaliplatin were administered immediately postoperatively, intraperitoneally. After killing the rats on the 8th postoperative day, the anastomoses were examined macroscopically and the anastomotic bursting pressures were measured. The anastomoses were also examined histologically and the hydroxyproline contents were determined. Rupture of the anastomosis was observed in no rats of the 1st group, in 3 rats of the 2nd group, in 4 rats of the 3rd group and in 7 rats of the 4th group (P = 0.016). The bursting pressure (P < 0.001), the hydroxyproline content (P < 0.001) and the concentration of collagen (P < 0.001) and fibroblasts (P < 0.001) were significantly lower in the 2nd, 3rd and 4th group in comparison with the 1st group. The formation of adhesions and the leukocytosis on the anastomoses were significantly higher in the 2nd, 3rd and 4th group than in the 1st group (P < 0.001). The immediate postoperative, intraperitoneal administration of oxaliplatin, 5-FU or the combination of 5-FU and oxaliplatin impairs the healing of colonic anastomoses in rats.
ABSTRACT Background Tissue necrosis is a common complication in operations that use skin flaps fo... more ABSTRACT Background Tissue necrosis is a common complication in operations that use skin flaps for reconstructive surgery. Here we demonstrate the beneficial effect of autologous genetically modified adipose-derived stromal cells (ASCs) in the survival of random-pattern skin flaps. Methods ASCs were isolated from the inguinal fat pad of Wistar rats and genetically modified in order to permanently produce green fluorescent protein (GFP) using the Sleeping Beauty transposon technology. Autologous GFP-producing cells were then injected intradermally into random-pattern skin flaps planned on the dorsal area of rats. Results Injection of ASCs resulted in significant improvement of skin flap survival. Histological analysis showed that the connective tissue was almost intact in skin flaps treated with ASCs in contrast to disorganized tissues from mock-treated skin flaps. GFP ASCs were detected in the endothelium of blood vessels co-expressing the endothelial marker von Willebrand factor, thus suggesting that they promote blood vessel regeneration. Conclusions These findings indicate that transplantation of autologous GFP ASCs improve survival of skin flaps. This methodology suggests that the use of genetically modified ASCs producing, e.g., angiogenic factors may facilitate survival and integration of flaps in plastic surgery.
1. Rat liver microsomal membranes were studied for the presence of protein kinases. Microsomal pr... more 1. Rat liver microsomal membranes were studied for the presence of protein kinases. Microsomal proteins solubilized with Triton X-100 were analyzed by means of ion exchange chromatography. 2. Protein kinase activity was detected in the column fractions using specific assays for cAMP-dependent protein kinase, cGMP-dependent protein kinase, protein kinase C, Ca2+/calmodulin-dependent protein kinase and casein kinases. 3. Fractions with protein kinase activity were further analyzed by SDS-polyacrylamide gel electrophoresis. 4. The results indicate that cAMP-dependent protein kinase type I and II, casein kinases I and II, protein kinase C proenzymes I and II and Ca2+/calmodulin kinase II are associated with the membranes of endoplasmic reticulum (ER).
The purpose of this experimental study was to assess the effects of the immediate postoperative i... more The purpose of this experimental study was to assess the effects of the immediate postoperative intraperitoneal administration of oxaliplatin and 5-FU on the healing of colonic anastomoses in rats. Sixty rats were randomized into 4 groups of 15 rats each and were subjected to colonic anastomoses. To the 1st group, saline solution was administered immediately postoperatively, intraperitoneally. To the 2nd group, 5-FU was administered, to the 3rd group oxaliplatin and to the 4th group 5-FU and oxaliplatin were administered immediately postoperatively, intraperitoneally. After killing the rats on the 8th postoperative day, the anastomoses were examined macroscopically and the anastomotic bursting pressures were measured. The anastomoses were also examined histologically and the hydroxyproline contents were determined. Rupture of the anastomosis was observed in no rats of the 1st group, in 3 rats of the 2nd group, in 4 rats of the 3rd group and in 7 rats of the 4th group (P = 0.016). The bursting pressure (P < 0.001), the hydroxyproline content (P < 0.001) and the concentration of collagen (P < 0.001) and fibroblasts (P < 0.001) were significantly lower in the 2nd, 3rd and 4th group in comparison with the 1st group. The formation of adhesions and the leukocytosis on the anastomoses were significantly higher in the 2nd, 3rd and 4th group than in the 1st group (P < 0.001). The immediate postoperative, intraperitoneal administration of oxaliplatin, 5-FU or the combination of 5-FU and oxaliplatin impairs the healing of colonic anastomoses in rats.
Several extracellular proteins have been reported to be phosphorylated. Previous studies of our l... more Several extracellular proteins have been reported to be phosphorylated. Previous studies of our laboratory indicated that laminin-1 can be phosphorylated by protein kinase A (PKA). Moreover, it has been reported that protein kinase C (PKC), although known to be intracellular, can phosphorylate extracellular proteins in the case of cellular damage and/or platelet activation. In the present study we examined the possibility of laminin-1 serving as a substrate of PKC. Amino acid analysis revealed that laminin-1 is phosphorylated by this enzyme on serine residues. Self assembly, heparin binding, and cell attachment on the phosphorylated molecule were then studied. Phosphorylated laminin-1 showed an increased and more rapid self assembly than the non-phosphorylated molecule. Heparin binding and cell attachment experiments indicated enhanced heparin and cell binding capacity of the phosphorylated molecule in comparison to the non- phosphorylated control. These results indicate that lamini...
International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity, 1999
To examine possible changes of leptin concentrations after the acute administration of glucose or... more To examine possible changes of leptin concentrations after the acute administration of glucose orally (OGTT). Seventy-five grams of glucose were administered per os in one group of obese and normal weight individuals and concentrations of glucose, insulin and leptin were measured at 0, 30, 60, 90 and 120 min. In an age matched control group of individuals with similar BMI water was given and leptin concentrations were measured before and after 30, 60, 90 and 120 min. Twenty-seven obese women aged 34+/-1.57 y with BMI 37.1+/-0.8 kg/m2 and 16 normal weight women, aged 32+/-1.13 y with BMI 23.6+/-0.3 kg/m2 formed the experimental group, while 10 obese and 10 normal weight females with similar age and BMI were used as controls. Weight, height, BMI, body fat, glucose, insulin and leptin at baseline and during OGTT. Variations of the above parameters were calculated from the area under the curve (AUC). Fasting leptin concentrations and AUC were higher in obese than in normal weight women....
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1997
The synthetic laminin pentapeptide tyrosyl-isoleucyl-glycyl-seryl-arginine (YIGSR) binds to a met... more The synthetic laminin pentapeptide tyrosyl-isoleucyl-glycyl-seryl-arginine (YIGSR) binds to a metastasis associated high-affinity laminin receptor. The aim of this study was to investigate if the radiolabeled peptide can be considered as a basis for a potential tumor-imaging radiopharmaceutical. Iodine-131-labeled YIGSR was injected in mice inoculated with Lewis Lung carcinoma, as well as in normal controls. The experimental animals were imaged on a gamma camera 10 hr after peptide administration. The same peptide was also labeled with 125I and administered to tumor-bearing and normal mice. At various time-points after peptide administration, the experimental animals were killed, and the radioactivity in the tumor, lung, liver and spleen was measured. Microscopic autoradiography was performed in histological sections of the same tissues. The tumor and the spleen of tumor-bearing animals were imaged on a gamma camera. No significant blood-pool background was detected. No other organ ...
It has been reported that metastatic melanoma cell lines selectively bind in vitro with the synth... more It has been reported that metastatic melanoma cell lines selectively bind in vitro with the synthetic laminin pentapeptide tyrosyl-isoleucyl-glycyl-seryl-arginine (YIGSR). The aim of this study was to investigate whether the same peptide can bind on melanoma cells in vivo as well. Iodine-125-labeled YIGSR was administered to B16 melanoma-bearing animals. Microscopic autoradiography of tumor and organ sections taken 24 h after peptide administration showed that the peptide did accumulate on the surface of certain tumor cells. The peptide binding cells were frequent in metastatic sites and tumors grown for 24 days and rare in tumors grown for 10 days. A similarly radiolabeled control pentapeptide (peptide DRLKY) did not bind to any tumor cell. It is suggested that the YIGSR binding tumor cells may represent a distinct melanoma cell population with a high metastatic potential.
Biochemistry and molecular biology international, 1995
A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has be... more A heparin binding fibroblast growth factor with a molecular weight of approximately 45 kDa has been detected in human placenta. The protein was extracted from placenta and purified by a combination of ammonium sulfate precipitation, DE-52 anion exchange chromatography, G100 gel exclusion and heparin sepharose affinity chromatography. The molecule was shown to be monomeric after treatment with beta-mercaptoethanol, and had an acidic isoelectric point. The properties of the polypeptide described in this paper (45 kDa, Pi 4-5, monomeric, heparin binding fibroblast growth factor), suggest that it may represent an as yet undescribed growth factor.
Comparative biochemistry and physiology. A, Comparative physiology, 1989
1. The mean pigeon erythrocyte life span was found to be 17-25 days by Cr51-labeled erythrocytes ... more 1. The mean pigeon erythrocyte life span was found to be 17-25 days by Cr51-labeled erythrocytes and 21 +/- 3.4 days by iron kinetics. 2. Total red blood cell volume has been calculated by Cr51-labeled erythrocytes while total plasma volume was determined both by a dye method and iron kinetic data. From these results total blood volume and total body haematocrit were found to be 0.090 +/- 0.002 ml/g body wt and 36 +/- 4.3%, respectively. 3. Venous haematocrit, haemoglobin concentration, erythrocyte count, mean corpuscular haemoglobin concentration, plasma iron and red blood cell iron have also been measured. 4. A significant difference between total body and venous haematocrit and a short mean red blood cell life span, due to ageing and to random destruction of erythrocytes were shown. 5. The above observations are compared with analogous available data for human beings and their physiological significance is discussed.
The purpose of this experimental study was to assess the effects of the immediate postoperative i... more The purpose of this experimental study was to assess the effects of the immediate postoperative intraperitoneal administration of oxaliplatin and 5-FU on the healing of colonic anastomoses in rats. Sixty rats were randomized into 4 groups of 15 rats each and were subjected to colonic anastomoses. To the 1st group, saline solution was administered immediately postoperatively, intraperitoneally. To the 2nd group, 5-FU was administered, to the 3rd group oxaliplatin and to the 4th group 5-FU and oxaliplatin were administered immediately postoperatively, intraperitoneally. After killing the rats on the 8th postoperative day, the anastomoses were examined macroscopically and the anastomotic bursting pressures were measured. The anastomoses were also examined histologically and the hydroxyproline contents were determined. Rupture of the anastomosis was observed in no rats of the 1st group, in 3 rats of the 2nd group, in 4 rats of the 3rd group and in 7 rats of the 4th group (P = 0.016). The bursting pressure (P < 0.001), the hydroxyproline content (P < 0.001) and the concentration of collagen (P < 0.001) and fibroblasts (P < 0.001) were significantly lower in the 2nd, 3rd and 4th group in comparison with the 1st group. The formation of adhesions and the leukocytosis on the anastomoses were significantly higher in the 2nd, 3rd and 4th group than in the 1st group (P < 0.001). The immediate postoperative, intraperitoneal administration of oxaliplatin, 5-FU or the combination of 5-FU and oxaliplatin impairs the healing of colonic anastomoses in rats.
ABSTRACT Background Tissue necrosis is a common complication in operations that use skin flaps fo... more ABSTRACT Background Tissue necrosis is a common complication in operations that use skin flaps for reconstructive surgery. Here we demonstrate the beneficial effect of autologous genetically modified adipose-derived stromal cells (ASCs) in the survival of random-pattern skin flaps. Methods ASCs were isolated from the inguinal fat pad of Wistar rats and genetically modified in order to permanently produce green fluorescent protein (GFP) using the Sleeping Beauty transposon technology. Autologous GFP-producing cells were then injected intradermally into random-pattern skin flaps planned on the dorsal area of rats. Results Injection of ASCs resulted in significant improvement of skin flap survival. Histological analysis showed that the connective tissue was almost intact in skin flaps treated with ASCs in contrast to disorganized tissues from mock-treated skin flaps. GFP ASCs were detected in the endothelium of blood vessels co-expressing the endothelial marker von Willebrand factor, thus suggesting that they promote blood vessel regeneration. Conclusions These findings indicate that transplantation of autologous GFP ASCs improve survival of skin flaps. This methodology suggests that the use of genetically modified ASCs producing, e.g., angiogenic factors may facilitate survival and integration of flaps in plastic surgery.
1. Rat liver microsomal membranes were studied for the presence of protein kinases. Microsomal pr... more 1. Rat liver microsomal membranes were studied for the presence of protein kinases. Microsomal proteins solubilized with Triton X-100 were analyzed by means of ion exchange chromatography. 2. Protein kinase activity was detected in the column fractions using specific assays for cAMP-dependent protein kinase, cGMP-dependent protein kinase, protein kinase C, Ca2+/calmodulin-dependent protein kinase and casein kinases. 3. Fractions with protein kinase activity were further analyzed by SDS-polyacrylamide gel electrophoresis. 4. The results indicate that cAMP-dependent protein kinase type I and II, casein kinases I and II, protein kinase C proenzymes I and II and Ca2+/calmodulin kinase II are associated with the membranes of endoplasmic reticulum (ER).
The purpose of this experimental study was to assess the effects of the immediate postoperative i... more The purpose of this experimental study was to assess the effects of the immediate postoperative intraperitoneal administration of oxaliplatin and 5-FU on the healing of colonic anastomoses in rats. Sixty rats were randomized into 4 groups of 15 rats each and were subjected to colonic anastomoses. To the 1st group, saline solution was administered immediately postoperatively, intraperitoneally. To the 2nd group, 5-FU was administered, to the 3rd group oxaliplatin and to the 4th group 5-FU and oxaliplatin were administered immediately postoperatively, intraperitoneally. After killing the rats on the 8th postoperative day, the anastomoses were examined macroscopically and the anastomotic bursting pressures were measured. The anastomoses were also examined histologically and the hydroxyproline contents were determined. Rupture of the anastomosis was observed in no rats of the 1st group, in 3 rats of the 2nd group, in 4 rats of the 3rd group and in 7 rats of the 4th group (P = 0.016). The bursting pressure (P < 0.001), the hydroxyproline content (P < 0.001) and the concentration of collagen (P < 0.001) and fibroblasts (P < 0.001) were significantly lower in the 2nd, 3rd and 4th group in comparison with the 1st group. The formation of adhesions and the leukocytosis on the anastomoses were significantly higher in the 2nd, 3rd and 4th group than in the 1st group (P < 0.001). The immediate postoperative, intraperitoneal administration of oxaliplatin, 5-FU or the combination of 5-FU and oxaliplatin impairs the healing of colonic anastomoses in rats.
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Papers by G. Koliakos