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Biomedical subjects

S Ergün

Publications and source records attributed to S Ergün.

At least 37 records · Page 2Linked to original sources
PubMed1998

Human lymphocytes produce urocortin, but not corticotropin-releasing hormone.

Hypothalamic corticotropin-releasing hormone (CRH) is the principal regulator of the hypothalamus-pituitary-adrenal axis in mammals. In addition, immunoreactive CRH is also present at peripheral sites, where it is thought to act as a proinflammatory peptide. However, the source of peripheral CRH has remained obscure. Human lymphocytes were shown to produce immunoreactive CRH, yet the data on CRH mRNA expression in these cells are equivocal. More recently, Vaughan et al. discovered a new member of the CRH family, termed urocortin. Urocortin was shown to act through the same receptors as CRH. The current study was designed to investigate both mRNA and protein expression of CRH and urocortin in human lymphocytes. Using a commercial CRH(1-41) radioimmunoassay, we demonstrate that normal human lymphocytes and Jurkat T lymphoma cells produce significant amounts of immunoreactive peptide. However, no CRH mRNA was detectable by RT-PCR in these cells. In contrast, a band of the correct size and sequence was amplified with urocortin-specific primers. Immunocytochemical analysis of human lymphocytes using antibodies that could distinguish between CRH and urocortin revealed significant expression of urocortin but not of CRH, consistent with our RT-PCR data. We conclude that human lymphocytes produce urocortin, but not CRH.

Cells, Cultured↗
PubMed1997

Vascular endothelial growth factor and its receptors in normal human testicular tissue.

Expression of vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), and its receptors Flt-1 and KDR (Flk-1 in mouse) and their localization in the human testis were analyzed by means of reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry. VEGF mRNA was detected in the human testicular tissue and in fragments of seminiferous tubules by means of RT-PCR, while fragments of blood vessels isolated from testes were negative. Western blotting procedure using a specific VEGF antibody, revealed two protein bands corresponding to 24 and 49 kDa in the extracts prepared from the whole testis and in the seminiferous tubules while no such bands were found in isolated fragments of human testicular blood vessels. Also immunohistochemically, human testicular blood vessels show no VEGF immunoreactivity, while Leydig cells and Sertoli cells were positive. The mRNA of the VEGF receptor Flt-1 was found to be expressed in human testicular tissue, in isolated fragments of testicular blood vessels and in seminiferous tubules as determined by RT-PCR procedure. In accordance with these results, the Flt-1 protein was immunohistochemically localized in Leydig, Sertoli and perivascular cells. Endothelial cells of certain segments of human testicular microvasculature also stained positive for Flt-1. Expression of VEGF receptor, KDR, could be demonstrated in human testicular tissue, in isolated seminiferous tubules and in isolated fragments of human testicular blood vessels by means of RT-PCR. Immunohistochemically, the KDR protein was localized in endothelial cells and perivascular cells of capillaries within the lamina propria of seminiferous tubules. Leydig cells and Sertoli cells show KDR immunoreactivity, too. Thus we demonstrate the presence of both types of VEGF receptors Flt-1 and KDR on Leydig as well as on Sertoli cells which are normal non-endothelial cells, suggesting hitherto unrecognized and novel functions for such receptors. The results obtained permit us to suggest VEGF as a paracrine mitogenic and angiogenic factor, responsible for modulating the capillarization of the human testicular tissue and maintaining the functions of testicular microvasculature. VEGF may also influence the permeability of capillaries passing through the groups of Leydig cells and those localized within the lamina propria of human seminiferous tubules. The differences in the expression pattern of the VEGF receptors in the human testicular tissue probably reflect different VEGF effects in different compartments of human testis.

Blotting, Western↗
PubMed1997

Vascular endothelial growth factor, a possible paracrine growth factor in human acute myeloid leukemia.

Vascular endothelial growth factor (VEGF) is a multifunctional cytokine involved in angiogenesis, inflammation, and wound healing. It is secreted by a variety of tumor cell lines, including hematopoietic lines. Therefore, we investigated expression of VEGF and its receptors on fresh leukemic blasts. VEGF-specific transcripts were detected by polymerase chain reaction (PCR) in 20 of 28 patients with de novo acute myeloid leukemia (AML) and in 3 of 5 patients with secondary AML. Using immunocytochemistry, we found VEGF protein in 2 leukemic cell lines and in 8 AML patients, in concordance with PCR results. Supernatants of fresh leukemic cells from 24 AML patients contained significantly more VEGF than supernatants from bone marrow cells of 9 normal donors or of CD34-enriched cells from 3 normal volunteer donors as determined by an enzyme-linked immunosorbent assay. VEGF possesses two high-affinity receptors, KDR and FLT1. Using a sensitive nested PCR assay, we detected expression of FLT1 in 10 of 20 patients with de novo AML and 3 of 5 patients with secondary AML. KDR was expressed in 4 of 22 patients with de novo AML and 1 of 4 with secondary AML. To study possible paracrine growth stimulation of AML blasts, endothelial cells from human umbilical cords were incubated with increasing concentrations of VEGF. A dose-dependent increase of granulocyte-macrophage colony-stimulating factor secretion from endothelial cells was identified.

Acute Disease↗
PubMed1997

Estrogen and progesterone receptors and estrogen receptor-related antigen (ER-D5) in human epididymis.

Estrogen receptor mRNA expression was detected in the head and tail parts of the human epididymis by means of reverse transcription polymerase chain reaction (RT-PCR). Immunocytochemical labelling showed that ciliate and nonciliate cells from the epithelium of the efferent ductules possessed strong to moderate nuclear staining for estrogen and progesterone receptors. The epididymal duct was negative for both antigens. Vascular endothelial cells also showed estrogen receptor, but no progesterone receptor immunolabelling in all regions of the organ. Immunoreactivity for the estrogen receptor-related antigen (ER-D5) was seen in the cytoplasm of ciliated and nonciliated epithelial cells from the efferent ductules, in the basal cells of some epididymal duct profiles as well as in myofibroblasts of the lamina propria, endothelial cells and smooth muscle cells of the vessel walls. The results obtained suggest that the epithelial cells of the efferent ductules of the human epididymis may be main target structures of estrogens and progestins.

Electrophoresis, Agar Gel↗
PubMed1997

Angioarchitecture of the human spermatic cord.

Human spermatic cords were investigated by means of cast preparations, light-microscopic examination and computer-aided 3-dimensional reconstructions from serial sections of paraffin-embedded material. After leaving the testis, the testicular veins formed two principal groups co-existing side by side. Numerous veno-venous anastomoses could be observed within each individual group, whereas only a few mutual intergroup anastomoses were found. The testicular artery ran within one group but showed no close topographical relationship to the other group. Light microscopy of the serial sections revealed that the group of veins with no close topographical relationship to the testicular artery ran at a distance of several centimeters embedded within fatty tissue. With the help of computer-aided 3-dimensional reconstructions, a spatial picture of the vascular organization was obtained. These results allowed the following classification of the veins of the pampiniform plexus. Group-I veins formed a tight plexus around the testicular artery by means of veno-venous anastomoses. Group-II veins formed veno-venous anastomoses between each other and ran over at a sizeable distance embedded in fatty tissue but showed no close topographical relationship to the testicular artery. Group-III vessels formed veno-venous anastomoses between group-I and group-II. Group IV veins formed arterio-venous anastomoses with the testicular artery. Based on the differences in wall structure and diameter, a subclassification in group-I and group-II was undertaken. This organization of the veins of the human pampiniform plexus should further the understanding of physiological processes, such as the transfer of hormones and other substances from the veins to the testicular artery and vice versa. It should also facilitate the tracing of the veins during antegrade sclerosing.

Adult↗
PubMed1997

Expression of FLT4 and its ligand VEGF-C in acute myeloid leukemia.

FLT4 represents a recently cloned member of class III receptor tyrosine kinases which include receptors for the angiogenic growth factor VEGF, namely FLT1 and KDR. The ligand of FLT4 has been identified as VEGF-C which shares sequence homology with VEGF and P1GF. In the adult FLT4 shows a restricted expression pattern that is limited to lymphatic endothelia and endothelia of some high endothelial venules (HEV). FLT4 has also been detected in some tumor cell lines including the hematopoietic line HEL. We therefore investigated expression of FLT4 and its ligand VEGF-C in fresh samples from patients with AML. Using a sensitive PCR method we detected FLT4 m-RNA in 15 of 41 patients with de novo AML at diagnosis or relapse and in three of 12 patients with secondary AML. FLT4 expression was confirmed by immunocytochemistry in a subgroup of the studied patient population. FLT4 was also found in leukemic cell line U937, but not TF-1 and KG1a. VEGF-C expression was found in leukemic samples of four of seven FLT4-positive and four of six FLT4-negative patients. U937 cells also produced VEGF-C m-RNA. Interestingly, FLT4 expression was not detected in bone marrow samples of 15 normal volunteer donors or in CD34-positive cells from three additional donors. Possible autocrine and paracrine growth stimulation of leukemic blasts by VEGF-C is currently being investigated in our laboratory.

Acute Disease↗
PubMed1997

[Antegrade scrotal phlebography of the v. spermatica in left-sided testicular varicocele--are retrograde phlebographic classifications suitable for typing?].

PURPOSE: The study was conducted to clarify whether the use of classifications in base of retrograde phlebography would be sufficiently suitable for typifying the findings of antegrade phlebography examinations of the internal spermatic vein with regard to antegrade sclerotherapy. SUBJECTS AND METHODS: In course of antegrade sclerotherapy in 236 patients with previously untreated idiopathic left-sided varicocele, phlebography via scrotal approach was performed. The results were compared with the relevant findings of the pre-existing classifications of the retrograde exams. RESULTS: Comparison with the classifications of Bähren and Braedel showed distinct discrepancies. In 28.8% (Bähren) respectively 36.4% (Braedel) of our findings, typification was unsuccessful. Correspondence was found with the Riedl-classification. Collateral vessels however, are not sufficiently differentiated. CONCLUSION: Retrograde classifications proved insufficient in typifying the findings of antegrade phlebography of the internal spermatic vein. A more subtle classification is required. This has been worked out and presented.

Contrast Media↗
PubMed1997

Region-specific expression of the androgen receptor in the human epididymis.

The expression of the androgen receptor in the human epididymis was analysed by ribonuclease protection, in-situ hybridization and immunohistochemistry. Androgen receptor mRNA and protein could be detected throughout the entire organ, albeit in different quantities, in the caput, corpus and cauda regions, respectively. Also positive, though only weakly, was the ductus deferens, while the efferent ducts were devoid of specific signals. In-situ transcript hybridization and immunocytochemistry localized androgen receptor mRNA and protein primarily to the epithelium of the epididymal duct. In the ductal epithelial cells androgen receptor immunoreactivity showed a distinct nuclear distribution. While peritubular cells occasionally displayed weak signals, interstitial cells as well as blood vessels were consistently negative throughout the entire organ. The observed pattern of androgen receptor expression in the human epididymis supports the notion that the structure and function of the epididymis is differentially controlled by androgens in a region-specific manner, whereas it would not seem compatible with a direct role for androgens in the regulation of epididymal blood flow.

Aged↗
PubMed1997

Localization of endothelin-1 and endothelin-receptors A and B in human epididymis.

Expression of mRNA of endothelin-1 (ET-1) and its receptors, endothelin receptor A (ET-A) and endothelin receptor B (ET-B), in human epididymis was assessed by reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemistry was performed on longitudinal sections through whole normal human epididymides. ET-1 mRNA was detected in caput, corpus and cauda epididymidis. Immunohistochemically, ET-1 was localized mainly in ciliated cells of efferent ducts and in some principal cells of epididymal duct. Larger arteries, but not epididymal microvasculature, contained ET-1 immunoreactivity. ET-A and ET-B mRNAs were detected in caput, corpus and cauda epididymidis. In efferent ducts, ET-A immunoreactivity was localized in ciliated cells. In the proximal region of the epididymal duct, ET-A immunostaining was localized mainly in basal cells whereas the distal region was devoid of ET-A immunoreactivity. Throughout the epididymis, blood vessels stained positive for ET-B. Furthermore, ET-B immunoreactivity was found in ciliated cells of efferent ducts and in basal cells of the distal epididymal duct. The fact that ciliated cells of efferent ducts contain ET-1 and both types of receptors indicates that ET-1 acts as an autocrine factor in these cells. ET-1 produced by efferent ducts and epididymal duct may control epididymal blood flow in a paracrine manner via ET-B receptors in epididymal blood vessels.

Endothelin-1↗
PubMed1996

Sertoli cell lines established from H-2Kb-tsA58 transgenic mice differentially regulate the expression of cell-specific genes.

Sertoli cell lines have been established from H-2K(b)-tsA58 transgenic mice carrying an inducible temperature-sensitive SV40 T antigen in their germline. All cell lines tested for expression of Sertoli cell products by reverse transcription-polymerase chain reaction were shown to express mRNAs for alpha-inhibin, Steel factor, SGP-2, and transferrin as well as for androgen receptor and the orphan nuclear receptor SF-1. Selected cell lines were shown by immunocytochemistry to express the established Sertoli cell-specific pattern of cytoskeletal markers. The FSH receptor gene was also expressed, though downregulated by comparison with in vivo levels of expression. In some lines low expression of the luteinizing hormone receptor gene could also be detected. The gene for the transcription factor GATA-1, which is expressed specifically in Sertoli cells, was expressed only in a subset of the cell lines. Quantitative analysis of SGP-2 transcript levels by ribonuclease protection assays showed an increase at the nonpermissive temperature, whereas using a similar assay, Steel factor mRNA was shown to be expressed in amounts comparable to the in vivo situation only in two cell lines during permanent growth. In summary, cell lines that exhibit distinct Sertoli cell characteristics have been established, which may resemble different stages of phenotypic development.

Animals↗