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Biomedical subjects

D A Spandidos

Publications and source records attributed to D A Spandidos.

At least 19 recordsLinked to original sources
PubMed2006

Mutational analysis of the cell cycle inhibitor Kip1/p27 in childhood leukemia.

BACKGROUND: Cyclin-dependent kinases (CDKs) and cyclins, their regulatory subunits, govern cell-cycle progression in eukaryotic cells. Kip1/p27 is the main cyclin-dependent kinase inhibitor, which arrests cell division inhibiting G1-S transition. Kip1/p27 seems to play a critical role in the pathogenesis of several human malignancies and its lower expression has been shown to correlate with a poor prognosis in adult solid tumors. METHODS: Bone marrow blasts from 49 children with leukemia, 37 acute lymphoblastic leukemia (ALL), and 12 acute myeloid leukemia (AML) were studied. Exon 3 of Kip1/p27 was amplified using the polymerase chain reaction technique (PCR). Single strand conformational polymorphism and heterodouplex analysis were performed to detect DNA sequence with altered conformations and were subsequently sequenced to document mutations. RESULTS: Mutations in Kip1/p27 gene were detected in 2 out of 3 T-ALL, 6 out of 12 AML patients, and only 1 out of 34 B lineage ALL cases. Although the patient groups are small, a highly significant relation of the mutation status with the type of leukemia (P = 0.0037) and the risk group according to treatment protocols (P = 0.00021) was estimated. A statistically significant difference in the white blood count was observed (P = 0.019) between the mutated and non-mutated patient groups although no statistically significant association of the mutation status with the hemoglobin and platelets values, karyotype, age, sex, disease progression, and outcome was determined. CONCLUSIONS: Based upon these results, the Kip1/p27 mutations should be considered for further prospective testing as an additional parameter for risk stratification and treatment of childhood leukemia.

Acute Disease↗
PubMed2005

Preferential loss of 5S and 28S rDNA genes in human adipose tissue during ageing.

Loss of genomic rDNA has been associated with cellular and organismal ageing. The rDNA locus in humans comprises multiple copies of the 5.8S, 28S and 18S genes. Aim of the present study was to test the effect of aging on the copy number of the three rDNA genes individually in post-mitotic human tissue. We utilized real time polymerase chain reaction relative quantification to measure the copy number of 5.8S, 28S and 18S rDNA genes individually. We obtained adipose tissue from 120 male individuals aged from 9 to 94 years. The available data of each subject corresponding to the time of tissue sampling included: age, height, weight and calculated body mass index. Each rDNA gene was directly tested with Pearson correlation against age and body mass index. We found a significant negative correlation of the gene copy of 5.8S (P < 0.001) and 28S (P < 0.003) with age. Interestingly 18S gene copy displayed a different pattern with no statistically significant correlation with age. Conversely, we observed a significant negative correlation of the 18S gene copy with body mass index (P = 0.004) and a marginally non-significant negative correlation of the 5.8S (P = 0.097) gene copy with body mass index. In summary our results indicate that the rDNA recombination events in humans can be differentially targeted and regulated in response to ageing and/or fat accumulation. The proposed model generates possible implications regarding the effects of each rDNA gene loss in cell function as well as the mechanism of recombination targeting.

Adipose Tissue↗
PubMed2005

Distribution of HIV/AIDS protective SDF1, CCR5 and CCR2 gene variants within Cretan population.

An interesting finding in the epidemiology of human immunodeficiency virus (HIV) infection is that certain mutations in genes coding for chemokine receptors and their ligands may confer resistance to HIV-1 infection and/or AIDS progression. The mutations most frequently studied are the CCR5-delta32, CCR2-64I and SDF1-3'A. We examined the frequency of the above polymorphisms within the Cretan population, evaluating their contribution to a protective genetic background against HIV infection and progression. Two hundred blood samples were recruited at random among prospective blood donors from Crete. Genotyping was initially performed by polymerase chain reaction (PCR) analysis. CCR2 and SDF-1 PCR-amplified genomic regions were further subjected to restriction fragment length polymorphism (RFLP) analysis for genotype determination. The CCR5-delta32 allele frequency among our study group was 3.25%, although no respective homozygous samples were detected. The screening for the CCR2-64I polymorphism yielded 39 heterozygous (19.5%) and 4 homozygous (2%) subjects, revealing a CCR2-64I allele frequency of 11.75%. Among our 200 PCR-RFLP analysed samples, 73 (36.5%) were found heterozygous and 23 (11.5%) homozygous for the SDF1-3'A mutant variant. The allele frequency of the above polymorphism reached 29.75%. The frequency of the CCR5-delta32 allele among our study population seems to be remarkably lower compared to previously reported frequencies in other Caucasian groups. However, the SDF1-3'A allele frequency shows significantly higher distribution profiles within our study group compared to those observed in other Caucasian-European populations. The indicated difference could be attributed to the increased homogeneity of our population, which is well balanced and dispersed over a small geographical area. Since this polymorphism is related with delayed progression from HIV infection to AIDS, it could be used for prognostic genotyping in HIV infected Cretan individuals.

Acquired Immunodeficiency Syndrome↗
PubMed2005

Detection of point mutations at codon 12 of KI-ras in ophthalmic pterygia.

AIMS: Ophthalmic pterygium is a potentially vision-threatening lesion of unknown etiology, related to an exposure to solar light. Mutations to the ras genes are frequently observed in lesions related to an exposure to solar light. The present study aims at screening pterygia for mutations at codons 12 and 13 of the ras genes. METHODS: In all, 50 pterygia were examined, together with respective blood samples and specimens of normal conjunctiva. A PCR reaction was performed to amplify sequences containing codons 12 and 13 of Ki-ras, H-ras, and N-ras. An RFLP analysis was then performed to detect point mutations at codon 12. The mutational status at codons 12 and 13 was further explored with sequencing of PCR products. RESULTS: RFLP analysis revealed Ki-ras mutations at codon 12 in five (10%) of pterygia, whereas H-ras or N-ras mutations were not observed. Sequencing confirmed Ki-ras mutations at codon 12 and revealed absence of mutations at codon 13. The presence of Ki-ras mutations was significantly correlated with postoperative recurrence (P=0.02) and young age (P=0.04). Mutations were not observed in specimens of blood or normal conjunctiva for any of the genes examined. CONCLUSIONS: The absence of N-ras mutations is in agreement with previous reports concerning mucosal lesions. The detection of Ki-ras mutations and the association with postoperative recurrence implies a possible role of Ki-ras in the clinical profile of pterygium. The mechanism of Ki-ras mutations is unclear and could be independent of the action of UV light.

Adult↗
PubMed2004

Association between schizophrenia and DRD3 or HTR2 receptor gene variants.

Schizophrenia is a severe and common psychiatric disorder afflicting 1% of the world population. A role of many neurotransmitter receptors in schizophrenia was suggested by an association with several polymorphisms located in their coding regions. In this study we examined the contribution of the T-102C and A-206G transitions in the 5-HTR2a and DRD3 receptor genes respectively to genetic susceptibility and phenotypic expression of schizophrenia disorder within the Greek population. We determined by PCR and RFLP analysis the genotype for the above polymorphisms in 114 schizophrenic hospitalized individuals and 192 control samples. In contrast to previous reports from large European multicentre studies, which indicate significant correlation between schizophrenia and C-102 allele of the T-102C polymorphism, in this study we observed a statistically significant overall association between the disorder and allele T-102 (P<0.0001, odds ratio (OR)=2.11, 95% CI=1.48-3.02). We also found a highly significant excess of the T-102/C-102 and C-102/C-102 genotypes in the normal group (P<0.001). Comparison of the patients with the controls for the DRD3 polymorphism (A-206G transition) showed marginally nonsignificant differences in the genotypic (P=0.054) and no significance in the allelic (P=0.163) frequencies. However, the A-206/A-206 genotype seems to positively contribute to the disorder appearance, when compared to A-206/G-206 as genotype base line risk (P=0.016, OR=1.88, 95% CI=1.09-3.26). In conclusion, from genetic association analysis of this schizophrenic population, a significant association is clearly determined between the HTR2 genetic polymorphism and the presence of schizophrenic disorder, manifested as increased risk of schizophrenia for carriers of the T-102 allele.

Adult↗
PubMed2004

Simple electrostatic interaction mechanisms in the service of HIV-1 pathogenesis.

The main cell population affected by the human immunodeficiency virus-1 (HIV-1) infection belongs to the CD4+ T-lymphocyte family. Recent convincing evidence indicates that the majority of the cells that die due to HIV-1 are not actually infected by the virus. Instead, these cells are being led to programmed cell death after the activation of apoptotic mechanisms by the virus or its components. We propose here from accumulated evidence that the virus appears to deregulate the physiological function of these cells during the process of antigen presentation. Ionic interactions between the variable V3 domain of the HIV-1 coat glycoprotein gp120 and the amino terminal of the chemokine receptor CCR5 play a prominent role in this process, and we speculate that nature has evolved simple electrostatic interaction mechanisms which, coupled to specific recognition systems on the cell surface, can initiate and modulate certain cellular events without the need for specific molecular structures. HIV-1 utilizes such a mechanism to ensure activation of the target host cell.

Amino Acid Sequence↗
PubMed2003

Human herpes viruses in non-melanoma skin cancers.

We examined the possible involvement of human herpes viruses in sporadic non-melanoma skin cancer of Greek patients. Polymerase chain reaction (PCR) based detection assays were utilized for the detection of viral cytomegalovirus (CMV), herpes simplex virus (HSV) and Epstein-Barr virus (EBV) genomes in 24 squamous cell carcinomas (SCC), five Bowen's disease, 72 basal cell carcinomas (BCC) specimens and eight premalignant lesions. Forty-two of 109 (38.5%) skin lesions were found positive for CMV DNA. The highest incidence was 6/8 (75%) observed in specimens with premalignant lesions. The incidence was 37.5% (27/72) in BCC, 33% (8/24) in SCC and 20% (1/5) in extragenital Bowen's disease. All samples were negative for HSV-1/2 and EBV DNA as assessed by our PCR based assay. The CMV infection showed no statistically significant correlation with the histological type, age, site of lesion or sex. Our results give a strong indication of the possible involvement of CMV in non-melanoma skin cancer development.

Adult↗
PubMed2003

Absence of mutations in the VHL gene but frequent loss of heterozygosity at 3p25-26 in non-small cell lung carcinomas.

In this study we have examined 79 primary non-small cell lung tumours for the presence of mutations of the VHL gene as well as for allelic imbalance at the gene surrounding loci. While allelic imbalance was found in 83% of specimens, frequently affecting the whole 3p25-p26 region, no mutations were detected in the VHL coding region. The fractional regional loss (FRL) was significantly higher in squamous cell carcinomas (0.746) than adenocarcinomas (0.493) (Wilcoxon P=0.002). This is the first investigation of the VHL gene mutational status in primary lung tumours. Our results indicate that mutation is not a common means of VHL inactivation in NSCLC.

Adenocarcinoma↗
PubMed2003

Mutational analysis of CDKN2A genes in patients with squamous cell carcinoma of the skin.

BACKGROUND: Nonmelanoma skin cancers [squamous cell carcinomas (SCC) and basal cell carcinomas (BCC)] are the most common neoplasias of the Caucasian population. OBJECTIVES: The purpose of our study was to determine the involvement of CDKN2A genes in the development of sporadic nonmelanoma skin cancer in Greek patients. PATIENTS AND METHODS: Allelic imbalance analysis was performed in 22 SCC and five Bowen's disease specimens. Mutational analysis was performed on exons 1alpha, 1beta and 2 of the CDKN2A locus in 22 SCC, five Bowen's disease and 39 BCC specimens. Exon 1alpha was additionally screened in 28 BCC specimens to complete the mutational analysis of a previous study. RESULTS: Overall, 52% (14 of 27) of the SCC and Bowen's disease specimens exhibited loss of heterozygosity (LOH) in at least one microsatellite marker, whereas, only two of 27 (7%) exhibited microsatellite instability. LOH in 9p appears to be equally involved in both BCC and SCC tumours. Exons 1alpha, 1beta and 2 of the CDKN2A locus were screened for mutations. A Val28Gly substitution in exon 1alpha and a CCC-->TTT (Ala57Val and Arg58Ter) substitution in exon 2, resulting in a change in the amino acid sequence, are reported for the first time in two SCCs, the latter being indicative of a combination of an ultraviolet (UV) radiation-induced mutation and a point mutation. A previously described polymorphism of CDKN2A, the gene for p16INK4a, Ala148Thr, was also detected in an allelic frequency of 3.72%. No mutation was found in any of the five Bowen's disease specimens, or in exon 1beta of CDKN2A, also the gene for p14ARF. CONCLUSIONS: Mutations and the high incidence of 9p LOH detected in our SCC samples imply that inactivation of CDKN2A genes, via allelic loss and/or mutation (probably UV-induced) may play a significant role in nonmelanoma skin cancer development, particularly in the more aggressive SCC type.

Adult↗
PubMed2002

Association of p53 codon 72 polymorphism with advanced lung cancer: the Arg allele is preferentially retained in tumours arising in Arg/Pro germline heterozygotes.

The association of p53 codon 72 polymorphism with cancer has been investigated by several scientific groups with controversial results. In the present study, we examined the genotypic frequency of this polymorphism in 54 patients with advanced lung cancer and 99 normal controls from the geographical region of Greece. Sputum and bronchial washing samples from each patient were assayed for the presence of human papillomavirus. Codon 72 heterozygous (Arg/Pro) patients were also analysed for loss of heterozygosity at the TP53 locus, in order to determine the lost p53 allele (Arg or Pro). p53 Arg/Arg genotype was significantly increased in lung cancer patients compared to normal controls (50% vs 24.2%, P<0.002). Human papillomavirus was detected only in two patients (3.7%). Loss of heterozygosity at the TP53 locus was found in 14 out of 27 Arg/Pro patients (51.85%). The Pro allele was lost in 11 cases (78.6%), while the Arg allele was lost in three (21.4%). Our results suggest that p53 codon 72 Arg homozygosity is associated with advanced lung cancer, and that the Arg allele is preferentially retained in patients heterozygous for this polymorphism. On the other hand, human papillomavirus infection does not seem to play an important role in lung carcinogenesis.

Aged↗
PubMed2002

Detection of herpes simplex virus in pseudoexfoliation syndrome and exfoliation glaucoma.

PURPOSE: The pathogenesis of pseudoexfoliation syndrome (PEX) remains unknown. An infection, possibly viral, is one of the proposed pathogenetic mechanisms. This study examines the presence of herpes simplex virus (HSV) and varicella-zoster virus (VZV) in iris and anterior capsule specimens of PEX and non-PEX patients. METHODS: Iris and anterior capsule specimens were obtained from 64 patients with PEX (study group, SG) and 61 patients without PEX (control group, CG). The presence of HSV and VZV DNA was evaluated with a polymerase chain reaction (PCR). RESULTS: Herpes simplex virus type I was detected significantly more often in iris specimens from the SG (13.79%), compared to those from the CG (1.75%). Varicella-zoster virus DNA was not detected in any of the examined specimens. CONCLUSION: Results imply a possible relationship between HSV type I and PEX, although no aetiological role of HSV infection in PEX pathogenesis can be established. Results also advocate against any association between VZV and PEX.

Aged↗
PubMed2002

The transcobalamin codon 259 polymorphism influences the risk of human spontaneous abortion.

BACKGROUND: The remethylation cycle of methionine is folate and vitamin B(12) (cobalamin) dependent and appears to be crucial for embryonic development, probably through effects on synthesis of DNA, proteins and polyamines. Transcobalamin (TC) transports vitamin B(12) to the tissues. The objective of the present investigation was to explore the putative association between the major TC genetic polymorphism (Pro259Arg) and human spontaneous abortion. METHODS: The prevalence of the TC Pro259Arg polymorphism was determined in DNA samples from embryos that had been spontaneously aborted between the 6th and 20th week after conception, and adult controls using solid-phase minisequencing technique. RESULTS: The 259-Pro allele was significantly less frequent in the spontaneous abortion group than in the control group (42.2 and 57.0% respectively; P = 0.005), while the frequency of 259-Arg was significantly increased. There was a lower prevalence of 259-Pro homozygotes in the spontaneous abortion group compared with the control group (9.1 and 32.2% respectively; P < 0.001). CONCLUSIONS: The 259-Pro allele seems to have beneficial influences during embryogenesis, conceivably through its positive effect on vitamin B(12) intracellular bioavailability. Our results warrant additional investigations addressing the question if vitamin B(12) supplementation in addition to folic acid supplementation may prevent spontaneous abortion in women planning a pregnancy.

Abortion, Spontaneous↗
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

In vivo detection of human papilloma virus-induced lesions of anogenital area after application of acetic acid: a novel and accurate approach to a trivial method.

Human papilloma virus infection is increasing at an alarming rate. The ability of the virus to establish a subclinical infection and its association with malignancy of the lower genital tract make the statistics even more worrisome. Topical application of acetic acid solution provokes temporal alterations of the light-scattering properties of human papilloma virus-induced lesions of anogenital area. For the in vivo study of the phenomenon, an imaging system has been employed, which performs time-lapse imaging and enables the calculation and display of the kinetics of the provoked alterations in any point within the examined area. Confirmation of diagnosis has been established with conventional histology and polymerase chain reaction. It has been shown that the method provides early detection and staging of skin alteration or transformation due to human papilloma virus infection and enables mapping of the infected area.

Acetates↗
PubMed2001

Prevalence of hepatitis B and C markers in high-risk hospitalised patients in Crete: a five-year observational study.

BACKGROUND: So far the prevalence of viral hepatitis infection in hospitalized patients has not been extensively studied. Therefore we conducted the present five-year observational study to evaluate the prevalence of HBV and HCV infection in high-risk hospitalized patients of Crete, the largest Greek island, Due to the homogeneous population, epidemiological studies can be accurately done. METHODS: The study was carried out in two out of four District General Hospitals, and in the University Hospital of the island. Markers for HBV and HCV were studied and statistically evaluated according to age, sex and geographical area, in a well-defined hospitalized population. RESULTS: The total prevalence of HBsAg and anti-HCV in the three prefectures during the five-year study is 2.66% and 4.75% respectively. Overall the relative risks were higher in males than females for each hepatitis marker (p < 0.001). Higher prevalence of HBcAb was found in the 41-60 years age group for both sexes (males 36.17%, females 27.38%). Peak HBsAg prevalence was found in the age group of 21-40 and 41-60 years for males (5.4%) and females (3.09%) respectively. Anti-HCV prevalence increases with age reaching the highest prevalence in the age group of 41-60 years for males (7.19%) and in the 61-90 years age group for females (7.16%). For both sexes significant differences between the three locations were identified. For HBsAg a higher prevalence in Heraklion (3.96%) compared to Chania (2.30%, males: p < 0.0001, females: p < 0.05) and Rethymnon (1.45%, males: p < 0.01, females: p < 0.0001) was detected. For HCV a significantly higher prevalence in Heraklion (6.54%) compared to Chania (2.39%, males: p < 0.001, females: p < 0.001) but not in Rethymnon (5.15%, NS). A lower prevalence rate of HBcAb in Heraklion compared to Chania (20.07% versus 23.05%, males: p < 0.001, females: p < 0.001) was found. CONCLUSIONS: These results were possibly overestimated, but nevertheless reflect the situation of the general population within the island as shown by our previous publications in other study groups. Moreover they contribute to the mapping of viral hepatitis prevalence in a geographical area of Southern Europe and may be helpful in planning public health interventional strategies.

Adult↗
PubMed2001

Dys-regulation of effector CD4+ T cell function by the V3 domain of the HIV-1 gp120 during antigen presentation.

It was recently demonstrated that the semiconserved domain of the V3 region of the HIV-1 surface glycoprotein gp120 can induce an activation-apoptosis phenomenon to memory CD4+ cells from healthy individuals. Studying the effects of V3 on the interaction of antigen presentation between monocyte-derived macrophages and resting memory CD4+ T cells, we observed that V3 affects both cell populations. Macrophages exposed to composite liposomes containing V3 on the surface and tetanus toxoid (TT) as the recall antigen entrapped in the aqueous phase (lipoV3/TT liposomes) were able to activate CD4+ T cells during primary stimulation, but not after restimulation nine days later. Unstimulated macrophages or macrophages exposed to soluble TT responded to second stimuli, lipoV3/TT liposomes, and soluble TT in activating CD4+ T cells. Soluble TT-activated CD4+ T cells could be restimulated by soluble TT but not by lipoV3/TT liposomes, whereas lipoV3/TT liposome-activated CD4+ T cells became unresponsive to a second stimulus. These results show that resting memory CD4+ cells activated by macrophages presenting the recall antigen together with V3 become unresponsive to restimulation.

Amino Acid Sequence↗
PubMed2001

V3 induces in human normal cell populations an accelerated macrophage-mediated proliferation--apoptosis phenomenon of effector T cells when they respond to their cognate antigen.

The semi-conserved domain of V3 of HIV-1 was synthesised in a lipopeptide form to be presented on the surface of liposome particles. Composite liposomes were constructed with entrapped tetanus toxoid as a recall antigen (lipo-V3/TT liposomes) to study the influence of V3 on effector T cells of human normal peripheral lymphocyte populations. We demonstrated that lipo-V3/TT liposomes induce a V3-specific response characterised by an early, enhanced proliferation of effector CD4+ T cells, followed by a sharp apoptosis. The phenomenon required the presence of monocyte-derived macrophages and CD4+ T cells, but it was qualitatively and quantitatively distinct from the normal soluble antigen-mediated antigen presenting cell: T cell interaction. Presence of the beta-chemokine RANTES in the culture medium inhibited the phenomenon, suggesting that V3 plays a costimulatory role that involves the chemokine receptor CCR5 pathway during the process of antigen presentation to T cells. This observation may be very important if it occurs also in HIV-1 infection, as it may explain the selective and progressive depletion of non-infected effector CD4+ T cells.

Antigens, CD19↗