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Biomedical subjects

G Sourvinos

Publications and source records attributed to G Sourvinos.

At least 19 recordsLinked to original sources
PubMed2006

Lamivudine monotherapy in HBeAg-negative chronic hepatitis B: prediction of response-breakthrough and long-term clinical outcome.

BACKGROUND: Factors that predict response and breakthrough phenomenon to lamivudine monotherapy in patients with HBeAg-negative chronic hepatitis B have not been well defined. AIM: To determine pre-treatment and on treatment variables that predict initial response and breakthrough in patients with HBeAg-negative chronic hepatitis B receiving long-term lamivudine. METHODS: Seventy-nine patients, with chronic HBeAg-negative hepatitis B, who received lamivudine for a median of 31 months were included in the study. RESULTS: Initial virologic and biochemical response was observed in 73 (92%) and 70 (89%) patients, respectively, while 34 (47%) and 15 (21%) patients developed virological and biochemical breakthrough, respectively. High levels of necroinflammation in liver biopsy were associated with a higher probability of initial virological and biochemical response. Patients with pre-treatment serum hepatitis B virus DNA concentrations of more than 10(6) copies/mL were three times more likely to develop virologic breakthrough. Two patients died, one with baseline cirrhosis because of liver failure during biochemical breakthrough while the second death was liver and treatment unrelated. CONCLUSIONS: In HBeAg-negative chronic hepatitis B, initial response to lamivudine therapy is associated with necroinflammation, while baseline serum hepatitis B virus DNA exceeding 10(6) copies/mL is a strong predictor for breakthrough because of drug-resistant mutations. Severe complications are uncommon and are associated with biochemical breakthrough and pre-existing cirrhosis.

Adolescent↗
PubMed2003

Microsatellite DNA instability and loss of heterozygosity in bronchial asthma.

Genetic alterations, such as loss of heterozygosity (LOH) or microsatellite instability (MI), have been reported in both malignant and benign disorders. In order to identify loci of deoxyribonucleic acid (DNA) mutation in asthma, MI and LOH were studied in sputum cells. DNA was extracted from cells in the sputum and blood cells of 22 patients with moderate asthma. Cells were analysed for MI and LOH using 18 polymorphic markers on chromosome 5q, 6p, 11q, 14q. Microsatellite analysis was also performed in six healthy subjects. None of the healthy individuals exhibited any genetic alteration. Genetic alterations were found in 16 of 22 asthmatic patients (73%). In total, 12 (54.5%) patients exhibited LOH only, one (4.5%) MI only, while three showed both MI and LOH. The highest incidence of LOH and MI was found on chromosome 14q. Mean immunoglobulin E and blood eosinophil levels were significantly higher in asthmatics with three or more genetic alterations. A high incidence of genetic alterations in the deoxyribonucleic acid of the sputum cells was found in asthmatic patients. Further studies are needed to identify the role of loss of heterozygosity and microsatellite instability in the investigation of genetic susceptibility of asthma and thus, in its pathogenesis.

Adult↗
PubMed2002

Normal ras genes: their onco-suppressor and pro-apoptotic functions (review).

The ras family of oncogenes has been extensively studied for its implication in several types of human malignancies. Activation of ras genes involves mutations that alter the catalytic activity of the protein enhancing the downstream signals mostly towards cell proliferation and malignant transformation. Ras genes are also involved in induction of senescence or apoptosis, suggesting activation of alternative pathways that may be anti-oncogenic. Early experiments showed that transfection of wild-type ras in transformed cells reversed the oncogenic phenotype suggesting that wild-type ras has onco-suppressive properties. Indeed, expression of wild-type ras genes in several human malignancies is associated with good prognosis. In tumors carrying mutant ras genes the levels of expression of the wild-type allele never exceeded the mutant counterpart, indicating that the wild-type protein suppresses the effect of the mutant one. Recent development of the Kras2 deficient mice provided the tool to study the role of wild-type ras genes in tumorigenesis.

Animals↗
PubMed2001

p53 Codon 72 polymorphism is linked to the development and not the progression of benign and malignant laryngeal tumours.

The p53 codon 72 polymorphism, resulting in either an arginine or a proline residue has been proposed to affect the susceptibility of p53 protein to human papilloma virus (HPV) E6-mediated degradation in vitro. However, there are controversial results from several clinical studies in various human tumours. The purpose of our study was to investigate the significance of this p53 genotype with respect to the risk of neoplasia development in Greek patients with benign and malignant laryngeal tumours. Furthermore, we searched for an association between p53 alleles and the presence of HPV in the same series of samples. We found a significant statistical association in the distribution of p53 genotypes between laryngeal lesions and normal samples (P<0.001). Allelic analysis of the patients with both benign and malignant tumours revealed a striking over-representation of the homozygous p53Arg allele compared to normal population (P<0.0003). HPV was detected in only 3 laryngeal samples (1 benign and 2 malignant tumours). This is the first study correlating the p53 codon 72 polymorphism in laryngeal tumours. Our results provide evidence that this p53 polymorphism may be implicated at the early stages of the disease and concerns predisposition to premalignant laryngeal lesions rather than to progression from benign tumour toward malignancy. Moreover, we demonstrate that the p53Arg homozygous genotype affects the predisposition for laryngeal tumours while the heterozygous status does not. The low incidence of HPV infection suggests that it is not a major oncogenic factor in the development of laryngeal tumours but may have synergistic action with specific genotypes of p53 gene.

Carcinoma, Squamous Cell↗
PubMed2001

Detection of herpes simplex virus and human papilloma virus in ophthalmic pterygium.

PURPOSE: To evaluate the presence of herpes simplex virus (HSV) and human papilloma virus (HPV) in pterygia and phenotypically normal conjunctiva and the possible relation between viral presence and clinical information. METHODS: Fifty pterygia and respective conjunctival specimens were obtained. A personal and family history was recorded for each patient. HSV and HPV detection and typing were accomplished by polymerase chain reaction amplification of viral sequences. Results were statistically analyzed. RESULTS: HSV (type 1) was detected in 11 (22%), HPV (type 18) in 12 (24%), and both HSV-1 and HPV-18 in 3 (6%) of pterygia. No conjunctival specimen displayed HSV, whereas HPV was detected in four (8%). Postoperative recurrence and history of conjunctivitis were significantly more common in patients with simultaneous detection of HSV and HPV. CONCLUSION: The fact that HSV was not detected in conjunctival specimens implies a more specific correlation with pterygium, as compared with HPV. The detection of potentially oncogenic viruses, such as HSV and HPV, supports the concept that pterygium can be considered a neoplastic condition. The correlation of postoperative recurrence and a history of conjunctivitis with the simultaneous detection of HPV and HSV, implies a possible viral cooperation affecting the clinical profile of pterygium.

Adult↗
PubMed2001

Genetic detection of bladder cancer by microsatellite analysis of p16, RB1 and p53 tumor suppressor genes.

PURPOSE: We investigated the incidence of genetic alterations in urine specimens from patients with bladder cancer. MATERIALS AND METHODS: A total of 28 cytological urine specimens were assessed for microsatellite alternations, and 15 microsatellite markers were located on p53, RB1 and p16 regions. In 15 patients DNA from tumor specimens was also available. RESULTS: Loss of heterozygosity was detected in 26 of 28 patients (93%) in at least 1 microsatellite marker. Allelic losses were found in 18 patients (64%) for the p16 locus, in 8 (29%) for the RB1 locus and in 17 (61%) for the p53 region. In contrast, no microsatellite alterations were found in the normal group without evidence of bladder cancer. In 11 cases genetic alterations in the cytological urine specimens were not detectable in the corresponding tumor specimen, suggesting heterogeneity of bladder cancer. CONCLUSIONS: The detection of loss of heterozygosity in cytological urine specimens may be a prognostic indicator of early detection of bladder cancer. Our results suggest that microsatellite analysis of urine specimens represents a novel, potentially useful, noninvasive clinical tool to detect bladder cancer.

Aged↗
PubMed2001

Extended genetic alterations in a patient with pulmonary sarcoidosis, a benign disease.

BACKGROUND: Genetic alterations at the microsatellite level have been detected in various human malignant tissues, but have also been found in chronically inflamed tissues. Sarcoidosis is a benign disease of unknown etiology characterized by chronic inflammation, which may be associated with an increased incidence of developing malignancy. METHODS: We examined the microsatellite alterations in a sputum cytological specimen of a patient with sarcoidosis. The DNA electrophoretic pattern of sputum was compared with that of the peripheral blood. Thirty-two microsatellite markers located at chromosomes 2p, 3p, 8p, 9p, 9q, 17p, 17q were used to reveal genetic alterations. RESULTS: Loss of heterozygosity (LOH) was detected in eleven markers in loci 2p, 9p, 9q and 17q. LOH was observed in all four markers spanning the chromosomal arm 17q11.2-q21, suggesting a potential chromosomal deletion. CONCLUSION: The observation of LOH in all four markers spanning the chromosomal arm 17q11.2-q21 may suggest a potential for malignancy development in this patient, or may be linked to the aetiopathogenesis of sarcoidosis. Further microsatellite fine mapping and clinical follow up of this patient are needed to clarify this.

Adult↗
PubMed2000

Human papillomavirus infection of non-melanoma skin cancers in immunocompetent hosts.

Human papilloma viruses (HPVs) consist of more than 70 different types and are known to be associated with numerous malignant tumors, including carcinomas of the mucosal and cutaneous epithelium. Non-melanoma skin carcinoma (NMSC) is the most frequently occurring malignancy worldwide in the Caucasian population. Most studies examining the involvement of papillomaviruses in the development of cutaneous carcinomas have been performed on lesions from patients with epidermodysplasia verruciformis or from immunosuppressed patients. Our specimens were obtained from 108 immunocompetent patients with benign and malignant skin lesions, and HPVs were detected in 27%. HPV 8 and HPV 18 were the most frequent types (62 and 48%, respectively). Our results suggest that HPVs, particularly the oncogenic potential of certain types such as HPV 8, 18, and 5 could contribute to the development of NMSCs.

Basal Cell Carcinoma↗
PubMed2000

RNA polymerase III transcription factor TFIIIC2 is overexpressed in ovarian tumors.

Most transformed cells display abnormally high levels of RNA polymerase (pol) III transcripts. Although the full significance of this is unclear, it may be fundamental because healthy cells use two key tumor suppressors to restrain pol III activity. We present the first evidence that a pol III transcription factor is overexpressed in tumors. This factor, TFIIIC2, is a histone acetyltransferase that is required for synthesis of most pol III products, including tRNA and 5S rRNA. TFIIIC2 is a complex of five polypeptides, and mRNAs encoding each of these subunits are overexpressed in human ovarian carcinomas; this may explain the elevated TFIIIC2 activity that is found consistently in the tumors. Deregulation in these cancers is unlikely to be a secondary response to rapid proliferation, because there is little or no change in TFIIIC2 mRNA levels when actively cycling cells are compared with growth-arrested cells in culture. Using purified factors, we show that raising the level of TFIIIC2 is sufficient to stimulate pol III transcription in ovarian cell extracts. The data suggest that overexpression of TFIIIC2 contributes to the abnormal abundance of pol III transcripts in ovarian tumors.

Acetyltransferases↗
PubMed2000

Allelic loss at the BRCA1, BRCA2 and TP53 loci in human sporadic breast carcinoma.

Abnormalities in several genes are known to confer susceptibility to breast cancer. In the present study, we investigated the incidence of allelic imbalance at the BRCA1, BRCA2 and TP53 loci, in 82 sporadic breast carcinomas using a bank of highly polymorphic microsatellite markers located at the BRCA1, BRCA2 and TP53 regions. Genetic alterations were observed in 58/82 (71%) cases in at least one microsatellite marker, at one of the three regions. Twenty-seven out of 82 (33%) cases exhibited loss of heterozygosity (LOH) at BRCA1 locus while in 20/82 (34%) cases LOH was observed for the BRCA2 region. Allelic deletions were detected in 28/82 (34%) cases for the TP53 locus. Our results suggest that allelic deletion at the above genetic loci play an important role to the development of sporadic breast tumours.

BRCA2 Protein↗
PubMed2000

High frequency of loss of heterozygosity on chromosome region 9p21-p22 but lack of p16INK4a/p19ARF mutations in greek patients with basal cell carcinoma of the skin.

Basal cell carcinoma of the skin is the most common neoplasia in humans. Previous studies have shown the existence of allelic imbalance (loss of heterozygosity and microsatellite instability) in BCC on several human chromosomes. Chromosome region 9p21-p22 harbors the CDKN2a/p16INK4a, p19ARF, and p15INK4b tumor suppressor genes. To determine the contribution of these genes to the development of basal cell carcinomas we looked for evidence of allelic imbalance in 67 sporadic basal cell carcinoma specimens from Greek patients and screened 28 of them presenting loss of heterozygosity at 9p21-p22 for germline mutations in p16INK4a and p19ARF genes. Chromosome regions 17q21 and 17p13 were also screened for allelic imbalance in all the 67 basal cell carcinoma specimens. Overall, 69% (46 of 67) of the specimens displayed loss of heterozygosity in at least one microsatellite marker, whereas only six of the 67 (9%) exhibited microsatellite instability. For the 9p21-p22 locus the overall frequency of loss of heterozygosity reached 55% (37 of 67) and is the highest reported. The overall frequency of loss of heterozygosity for the 17q21 locus is 34% (22 of 64) and for the 17p13 locus is 11% (seven of 65). Two of the 28 loss of heterozygosity positive cases were heterozygous for a previously described polymorphism, Ala148Thr, in exon 2 of the CDKN2a gene. This is the first demonstration of polymorphism in the CDKN2a gene in human basal cell carcinomas. No sequence variation in exon 1beta of the p19ARF gene was found. Our results provide evidence of a significantly high occurrence of loss of heterozygosity for the 9p21-p22 locus; however, lack of p16INK4a/p19ARF mutation suggests that these genes seem not to be implicated by mutational inactivation in the development of basal cell carcinoma. Other(s), yet unidentified, tumor suppressor gene(s) located in this locus may be related to this specific type of skin cancer.

Adult↗
PubMed2000

Allelic loss in chromosomal region 1q21-23 in breast cancer is associated with peritumoral angiolymphatic invasion and extensive intraductal component.

AIMS: Breast cancer is the most frequent cancer in the female population and the involvement of chromosomal alterations is often implicated in the development of cancer. The aim of our study was to assess loss of heterozygosity (LOH) in chromosome 1 in relation to clinical and pathological parameters. METHODS: Tumours, corresponding normal tissues and peripheral blood samples from 50 women with operable breast cancer, were analysed by polymerase chain reaction (PCR) at 16 polymorphic DNA markers, on both the long and short arm of chromosome 1. RESULTS: There was a significant correlation between chromosomal region 1q21-23 and the presence of extensive intraductal component (EIC) and peritumoral angiolymphatic (PALI) invasion, both independent markers of local recurrence. CONCLUSIONS: Allelic loss in region 1q21-23 may be a valuable prognostic biological marker for the detection of local relapse in breast cancer, in combination with other histological and clinical parameters.

Alleles↗
PubMed2000

Analysis of eight polymorphic human genetic markers in a well-defined Greek population.

The use of DNA in forensic science has become a basic tool for person identification or parentage testing. The use of polymorphic markers permits the formation of a unique profile for each individual. The knowledge of allele frequencies in a given population allows the scientist to estimate the probability of a particular allele combination. For this task, allele databanks are essential. In this report, the authors estimate the frequencies of eight polymorphic markers (namely, HumFES, HumF13A1, HumTHO1, HumVWA, HumFABP2, HumLIPOL, D1S80, and D17S5) in a randomly selected sample from Crete, Greece. The allele profile of all markers, with the exception of D17S5 and HumFABP2, concurs with previous reports and international data.

Alleles↗
PubMed2000

Frequent genetic alterations at the microsatellite level in cytologic sputum samples of patients with idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology associated with DNA damage and malignancy. Bronchogenic carcinoma is the cause of death in 10% to 13% of IPF patients. Microsatellite instability (MSI) and loss of heterozygosity (LOH) are frequently detected in cancers. If these genetic alterations could be observed in IPF, they might explain the higher relative risk of lung cancer in this disease. We investigated the incidence of MSI and LOH in sputum cytologic specimens from 26 IPF patients and 26 healthy, matched subjects, using 10 highly polymorphic microsatellite markers. The electrophoretic pattern of each specimen was compared with that of corresponding peripheral blood. Thirteen (50%) patients showed genetic alterations, consisting either of MSI or LOH. Five (19%) patients exhibited MSI and 10 (39%) exhibited LOH in at least one microsatellite marker. Three (12%) patients showed LOH in more than one marker. None of the healthy subjects exhibited genetic alterations in the studied markers. No correlation was found between the detected genetic alterations and age, disease duration, blood gases, or spirometric parameters of the patients. Our findings suggest that the genetic alterations that we studied are frequent in IPF, are apparently unrelated to the severity of the disease, and may be related to tumorigenesis.

Aged↗
PubMed2000

Mechanisms of retrovirus-induced oncogenesis.

Retroviruses are implicated in a series of human and animal tumours such as leukaemias, mammary tumours or skin cancer. The mechanism that they use to induce tumour formation varies. Insertional mutagenesis is a common mechanism in rodent, feline and avian retroviruses, where the retrovirus integrates into the host genome and affects the transcription of the neighbouring genes. Cloning of these affected genes led to identification of a series of oncogenes that play a significant role in the induction of human neoplasms. Retrovirus insertion also serves as a model to identify collaborating oncogenes. Human retroviruses use different, more complex mechanisms contributing to oncogenesis. Studies of the propagation and induction mechanisms used by retroviruses have given insight to the understanding of oncogenesis.

Animals↗
PubMed1999

Overexpression of the Tpl-2/Cot oncogene in human breast cancer.

Tpl-2/Cot proto-oncogene encodes a serine threonine kinase and was initially cloned as a provirus insertion site in MoMuLV-induced T cell lymphomas in rats. Tpl-2 locus was also shown to be affected by provirus insertion in MMTV-induced mammary carcinomas in mice. The involvement of Tpl-2 in 35 human breast paired tumour specimens versus their corresponding adjacent normal tissue was evaluated. Tpl-2 was found overexpressed in 14 of the 35 breast tumours tested using a semi-quantitative RT - PCR method. Gene amplification was detected in eight out of the 14 specimens overexpressing Tpl-2, suggesting the increased number of copies of Tpl-2 gene as a possible mechanism for Tpl-2 overexpression. Significant association was found between the overexpression of Tpl-2 and stage I of the tumours, indicating that this molecular alteration may be an early event in the development of the disease. Furthermore, overexpression of Tpl-2 was associated with positive progesterone receptor status of the samples. This is the first report on the Tpl-2 oncogene linked to human breast tumours suggesting that it may be a key molecule for the study of human breast cancer.

Adult↗
PubMed1999

Detection of microsatellite instability in sporadic cardiac myxomas.

OBJECTIVE: Microsatellite instability (MIN) is an early event in DNA repair-deficient associated diseases and reflects an elevated mutation rate in the genome of neoplastic cells. Sporadic cardiac myxomas are the most common primary heart tumours and their aetiopathology remains obscure. This study investigates the incidence of MIN in sporadic cardiac myxomas as a possible genetic mechanism of tumour pathogenesis. METHODS: Eleven surgically excised sporadic cardiac myxomas were assessed for MI using twenty-two highly polymorphic microsatellite markers, located on a wide range of chromosomal arms. DNA was extracted from myxoma tissue specimens as well as the respective normal tissue and subjected to polymerase chain reaction. RESULTS: The microsatellite analysis revealed that seven myxoma specimens (64%) exhibited MIN in at least one marker. One tumour specimen exhibited evidence of MIN in four microsatellite markers, while the most frequently affected marker was D17S855 (27%), located on chromosome 17q. DISCUSSION: We have detected a considerable incidence of MIN in sporadic cardiac myxomas indicating that decreased fidelity in DNA replication and repair is common in these tumours. To the best of our knowledge this is the first report describing MIN in sporadic cardiac myxomas, as a possible pathogenetic mechanism of these rare neoplasms.

Adult↗