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Biomedical subjects

N Papadopoulos

Publications and source records attributed to N Papadopoulos.

At least 91 records · Page 5Linked to original sources
PubMed2001

Spontaneous abortions with increased CD5 positive cells in the placental tissue during the first trimester of gestation.

Most spontaneous abortions occur before 12 weeks' gestation, and most are due to chromosomal errors in the conceptus. Relatively few truly spontaneous abortions take place between 12 and 20 weeks' gestation. Thereafter, between 20 and 30 weeks another type of premature spontaneous termination due to ascending infection becomes prevalent. The number of cells expressing the various lymphocytic markers changes throughout pregnancy. In the present study, we investigated the immunohistochemical expression of mononuclear infiltrations in paraffin-embedded placentas, from fetuses after spontaneous abortion (8th, 10th, and 12th week of gestational age), and those after therapeutic abortion at the same time, using a panel of monoclonal antibodies for the identification of leukocytes (CD45/LCA), B-lymphocytes (CD20/L-26), T-lymphocytes (CD45RO/UCHL1) and CD5 cells. Immunologic factors in human reproductive failure are plausible mechanisms of infertility and spontaneous abortion. Approximately 25% of cases of premature ovarian failure appear to result from an autoimmune etiology. Unfortunately, current therapeutic options for these women are limited to exogenous hormone or gamete substitution. Local inflammation at the sites of endometriosis implants are postulated to mediate the pain and reduce fecundability associated with this clinical syndrome. The recruitment of immune cells, particularly monocytes and T cells, neovascularization around foci of invading peritoneal lesions, and the possible development of antiendometrial autoantibodies support an immunologic basis of this disorder. To date, treatment of pain and infertility associated with endometriosis is primarily surgical, although immune-based adjuvants are theoretical possibilities for the future. Finally, although hypotheses supporting immunologic mechanisms of recurrent pregnancy loss have been popular over the past decade, most clinical investigations in this area do not provide compelling evidence for this position. Reputable specialists in reproductive medicine use experimental immunotherapies judiciously in selected cases of repetitive abortion. For example, the use of anticoagulation therapy can be beneficial in cases with documented antiphospholipid antibodies. At present, however, efficacious immunotherapy protocols for general application have not been established. Despite these caveats, continued strides in our understanding of human reproductive immunology, should yield considerable future progress in this field. We conclude that, 1) maternal cells, probably CD45RO/UCHL1 positive cells, cross the maternofetal barrier and participate in spontaneous (involuntary) abortions, 2) a small proportion of maternal cells (approximately 30%), probably CD5 positive cells, also cross the maternal fetal barrier and cause growth delay and recurrent reproductive failure. The results were statistically significant (p < 0.0001, Student's t-test).

Abortion, Spontaneous↗
PubMed2001

Differential expression of alpha-smooth muscle actin molecule in a subset of bone marrow stromal cells, in b-cell chronic lymphocytic leukemia, autoimmune disorders and normal fetuses.

Lymphocytes are a constituent of normal marrow. Both B and T lymphocytes are derived from bone marrow stem cells. Lymphocytes are found in normal marrow as single cells and in lymphoid aggregates or follicles. Lymphocytes and precursors are particularly prominent in bone marrow from children in which they may account for up to 40% of the bone marrow cells. The development of hematopoetic cells within the bone marrow (BM) occurs in intimate association with cells of the bone marrow microenvironment. This phenotypically diverse population of connective tissue-type cells includes fibroblasts, macrophages, adipocytes and endothelial cells and, collectively, represents the stromal tissue of the bone marrow. The presence of myoid cells in human bone marrow has been observed during hemopoiesis in embryonic life, whereas during adult life, it is strictly related to different pathologic conditions such as metastatic carcinoma, Hodgkin's disease, hairy cell leukemia and chronic myelo-proliferative diseases. Under normal circumstances, lymphoid cells may constitute up to 20% of the population of nucleated cells in the bone marrow. However, there may be an absolute or a relative increase, the latter due to a reduction in hematopoietic tissue, as in some skeletal areas in advancing age, or in hypoplastic conditions. The aim of this study was to examine the presence, distribution and quantitation of cells expressing alpha-smooth muscle actin in the stroma of the BM of patients with nodular type b-cell chronic lymphocytic leukemia (B-CLL), patients with autoimmune disorders and embryos (gestational age 15 to 25 weeks). For this reason, we investigated the presence of myoid cells (MCs) in a series of 20 trephine bone marrow biopsies from adult patients and ten fetal specimens of the spine and femur, using a monoclonal antibody recognizing alpha-smooth muscle actin, a contractile microfilament expressed exclusively by smooth muscle cells, myofibroblasts and related cells. The results of our study showed that: 1. BM stromal myoid cells represent a distinct subpopulation of reticular cells in the bone marrow, undergoing cytoskeletal remodeling in response to various stimuli (fetuses). 2. The appearance of BM stromal myoid cells is not only seen as a characteristic feature in B-CLL, but is also seen, to a lesser degree, in the stroma of bone marrow in patients with autoimmune disorders. 3. Stromal cells with phenotypic smooth muscle features appear in bone marrow during pathological situations in a manner reminiscent of what occurs during normal development.

Actins↗
PubMed2000

10q23.3 loss of heterozygosity is higher in lymph node-positive (pT2-3,N+) versus lymph node-negative (pT2-3,N0) prostate cancer.

Loss of heterozygosity (LOH) in the region of 10q23.3 has been associated with multiple tumors, including glioblastoma multiforme, melanoma, endometrial carcinoma, and prostate carcinoma. The tumor suppressor gene, PTEN/MMAC1, is also located in this region, and, in addition to other tumor types (eg, glioblastoma multiforme, endometrial, and melanoma), PTEN/MMAC1 mutations have been found in prostate cancer cell lines, xenografts, and hormone refractory prostate cancer tissue specimens. The aim of this study was to evaluate LOH at 10q23.3 as a marker of cancer progression in node-positive prostate cancer. Genetic alterations in the region of 10q23.3 were assessed in 23 node-positive (pT2-3, N+) and 44 node-negative prostate (pT2-3, N0) cancers with D10S532, D10S1687, D10S541, and D10S583 flanking polymorphic genetic markers; PTENCA, a genetic marker within PTEN/MMAC1, was also tested. Using DNA from paired normal and microdissected tumor samples, LOH at microsatellite loci was determined after polymerase chain reaction amplification. LOH in at least 1 marker was identified in 14% (6 of 44) of lymph node-negative and 43% (10 of 23) of lymph node-positive prostate cancers (chi-square test, P = .007). This increase in genetic alterations in node-positive prostate cancer suggests that 10q23.3 is a marker for metastatic progression.

Adenocarcinoma↗
PubMed1999

A public database for gene expression in human cancers.

A public database, SAGEmap, was created as a component of the Cancer Genome Anatomy Project to provide a central location for depositing, retrieving, and analyzing human gene expression data. This database uses serial analysis of gene expression to quantify transcript levels in both malignant and normal human tissues. By accessing SAGEmap (http://www.ncbi.nlm.nih.gov/SAGE) the user can compare transcript populations between any of the posted libraries. As an initial demonstration of the database's utility, gene expression in human glioblastomas was compared with that of normal brain white matter. Of the 47,174 unique transcripts expressed in these two tissues, 471 (1.0%) were differentially expressed by more than 5-fold (P<0.001). Classification of these genes revealed functions consistent with the biological properties of glioblastomas, in particular: angiogenesis, transcription, and cell cycle related genes.

Brain↗
PubMed1999

Angiopoietins 3 and 4: diverging gene counterparts in mice and humans.

The angiopoietins have recently joined the members of the vascular endothelial growth factor family as the only known growth factors largely specific for vascular endothelium. The angiopoietins include a naturally occurring agonist, angiopoietin-1, as well as a naturally occurring antagonist, angiopoietin-2, both of which act by means of the Tie2 receptor. We now report our attempts to use homology-based cloning approaches to identify new members of the angiopoietin family. These efforts have led to the identification of two new angiopoietins, angiopoietin-3 in mouse and angiopoietin-4 in human; we have also identified several more distantly related sequences that do not seem to be true angiopoietins, in that they do not bind to the Tie receptors. Although angiopoietin-3 and angiopoietin-4 are strikingly more structurally diverged from each other than are the mouse and human versions of angiopoietin-1 and angiopoietin-2, they appear to represent the mouse and human counterparts of the same gene locus, as revealed in our chromosomal localization studies of all of the angiopoietins in mouse and human. The structural divergence of angiopoietin-3 and angiopoietin-4 appears to underlie diverging functions of these counterparts. Angiopoietin-3 and angiopoietin-4 have very different distributions in their respective species, and angiopoietin-3 appears to act as an antagonist, whereas angiopoietin-4 appears to function as an agonist.

Amino Acid Sequence↗
PubMed1999

Analysis of masked mutations in familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is an autosomal-dominant disease characterized by the development of hundreds of adenomatous polyps of the colorectum. Approximately 80% of FAP patients can be shown to have truncating mutations of the APC gene. To determine the cause of FAP in the other 20% of patients, MAMA (monoallelic mutation analysis) was used to independently examine the status of each of the two APC alleles. Seven of nine patients analyzed were found to have significantly reduced expression from one of their two alleles whereas two patients were found to have full-length expression from both alleles. We conclude that more than 95% of patients with FAP have inactivating mutations in APC and that a combination of MAMA and standard genetic tests will identify APC abnormalities in the vast majority of such patients. That no APC expression from the mutant allele is found in some FAP patients argues strongly against the requirement for dominant negative effects of APC mutations. The results also suggest that there may be at least one additional gene, besides APC, that can give rise to FAP.

Adenomatous Polyposis Coli↗
PubMed1999

Correlation between serum IL-6 and CRP levels and severity of head injury in children.

OBJECTIVE: To examine interleukin-6 (IL-6) and C-reactive protein (CRP) release in children with head injury (HI) and investigate if there is a correlation between the levels of these two proteins and the severity of HI. DESIGN: Prospective clinical investigation. SETTING: Eight-bed paediatric intensive care unit in a university hospital. PATIENTS: Forty-five children were followed up for 4 days after HI and their serum IL-6 and CRP levels were measured. MEASUREMENTS AND RESULTS: Peak serum IL-6 levels occurred 4 h postinjury, decreasing over time. CRP was normal 4 h after injury, then increased reaching peak levels in 48 h. Children with admission Glasgow Coma Scale (GCS) scores of 8 or less had higher IL-6 levels compared to children with GCS scores higher than 8, 4 and 12 h post-injury (p<0.01 and p<0.05, respectively). IL-6 was higher in children with admission PRISM scores of 10 or more than in those with PRISM scores lower than 10 at 4 and 12 h (p<0.05). CRP levels were higher in patients with GCS scores of 8 or less compared to patients with GCS scores higher than 8 at 24, 48 and 72 h (p<0.05, p<0.02 and p<0.02, respectively) . Patients with PRISM scores of 10 or more had higher CRP levels compared to those with PRISM scores lower than 10 at 24, 48 and 72 h (p<0.05). Peak CRP levels correlated well with peak IL-6 levels (r = 0.49, p<0.001). No correlation between IL-6 or CRP levels and mortality or clinical outcome was found. CONCLUSIONS: Serum IL-6 and CRP levels are elevated in children with HI and there is a relation between the severity of HI and the levels of these proteins. There was no correlation between IL-6, CRP and outcomes of the patients.

Adolescent↗
PubMed1999

CACP, encoding a secreted proteoglycan, is mutated in camptodactyly-arthropathy-coxa vara-pericarditis syndrome.

Altered growth and function of synoviocytes, the intimal cells which line joint cavities and tendon sheaths, occur in a number of skeletal diseases. Hyperplasia of synoviocytes is found in both rheumatoid arthritis and osteoarthritis, despite differences in the underlying aetiologies of the two disorders. We have studied the autosomal recessive disorder camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP; MIM 208250) to identify biological pathways that lead to synoviocyte hyperplasia, the principal pathological feature of this syndrome. Using a positional-candidate approach, we identified mutations in a gene (CACP) encoding a secreted proteoglycan as the cause of CACP. The CACP protein, which has previously been identified as both 'megakaryocyte stimulating factor precursor' and 'superficial zone protein', contains domains that have homology to somatomedin B, heparin-binding proteins, mucins and haemopexins. In addition to expression in joint synovium and cartilage, CACP is expressed in non-skeletal tissues including liver and pericardium. The similarity of CACP sequence to that of other protein families and the expression of CACP in non-skeletal tissues suggest it may have diverse biological activities.

Amino Acid Sequence↗
PubMed1999

Phase II trial of escalated dose of tirapazamine combined with cisplatin in advanced malignant melanoma.

A phase II study was undertaken to determine the efficacy of tirapazamine combined with cisplatin in patients with metastatic melanoma between April 1996 and April 1997. Tirapazamine 390 mg/m2, administered i.v. over 2 h, followed in 1 h by cisplatin 75 mg/m2 over 1 h, were used every 21 days to treat chemotherapy-naive patients with metastatic melanoma. Objective tumor measurements were used to assess efficacy of the regimen. NCI common toxicity criteria were used to grade toxicities. Forty-eight patients with metastatic melanoma of cutaneous or mucosal origin, none with symptomatic brain metastasis, were treated. Nine patients had a partial response, with an overall response rate of 20% (95% confidence interval: 9-33%). The median duration of response was 6 months. Grade 3 nausea, vomiting, anorexia, muscle cramps and fatigue occurred in fewer than 10% of patients. Neutropenia and thrombocytopenia were rare. This outpatient single-day administered tirapazamine-cisplatin regimen has definite activity in chemotherapy-naive patients with metastatic melanoma. Further studies in combination with other agents active against this disease are warranted.

Adult↗
PubMed1999

Pilot study of intra-arterial cisplatin and intravenous vinblastine and dacarbazine in patients with melanoma in-transit metastases.

For melanoma, in-transit metastases (ITMs) are a harbinger of systemic disease in over 70% of patients and thus warrant a systemic approach to management. In this study, previously untreated patients with ITMs (n=15) received a systemic regimen of 'CVD' in 21 day cycles (median, three cycles) as follows: dacarbazine 800 mg/m2 intravenously (i.v.) on day 1, vinblastine 1.6 mg/m2 i.v. on days 1-5, and cisplatin (CDDP) 100 mg/m2 by 24 h intra-arterial (i.a.) infusion in 1l of heparinized saline via the iliac or subclavian artery on day 3. There were three clinical complete responses (CRs) in patients with a modest burden of ITMs (< 3 cm in size) and seven partial responses (PRs), yielding a 67% response rate (95% confidence interval, 38-88%). One of the clinical CRs had microscopic residual disease at surgery (a pathological PR). The times to progression (TTP) for the CRs were 5, 21 and 38+ months; the median TTP for the PRs was 4.5 months (range, 2-10 months). Overall median survival was 31 months. Systemic toxicities were similar to those induced by i.v. CVD. However, patients noted more pronounced paraesthesia in the infused extremity. Also, two patients experienced severe CDDP-induced burns, one patient developed brachial plexopathy, and one patient had a haemorrhage in an occult brain metastasis. The high clinical activity of this regimen will have to be confirmed in more patients before a first-pass i.a. advantage can be claimed. Furthermore, the dose, schedule and technique of i.a. CDDP delivery must be further refined before it can be routinely incorporated in regimens as an alternative to isolated regional hyperthermic perfusion, which is technically more difficult and is not readily available in community-based hospitals.

Adult↗
PubMed1998

DNA damage in peripheral blood mononuclear cells correlates with response to biochemotherapy in melanoma.

The combination of cisplatin-based chemotherapy with interleukin-2 (IL-2) and interferon, referred to as biochemotherapy, has shown encouraging results in patients with advanced melanoma. Toxicity is high, however and no objective parameters exist to distinguish between patients who are likely to respond and those who are not. The purpose of this pilot study was to determine whether in vitro cisplatin-induced damage to the glutathione S-transferase-pi (GST-pi) gene in peripheral blood mononuclear cells (PBMCs) before therapy correlated with the histological response in melanoma patients with local-regional metastases who received concurrent biochemotherapy before definitive surgery. Before therapy, PBMCs from 16 patients were exposed to cisplatin at concentrations of 25, 50 or 100 microM for 3 h and the extent of damage to the GST-pi gene was quantitated by polymerase chain reaction (PCR). Patients were subsequently treated on a biochemotherapy regimen consisting of cisplatin 20 mg/m2 intravenously (i.v.) on days 1-4, vinblastine 1.5 mg/m2 i.v. on days 1-4, dacarbazine 800 mg/m2 i.v. on day 1, IL-2 9 MIU/m2 per day i.v. by continuous infusion on days 1-4 (total of 96 h), and interferon alpha2a 5 MU/m2 subcutaneously on days 1-5. The 16 patients were categorized into two groups: major responders (n = 7) and non-major responders (n = 9). Although we observed a wide interpatient variation, a statistically significant correlation existed between the histological response and the degree of DNA damage caused in the PBMCs at all three cisplatin concentrations tested (P = 0.024 for 25 microM; P = 0.036 for 50 microM; P = 0.007 for 100 microM). Our pilot study suggests that determination of in vitro cisplatin-induced DNA damage using a gene-specific PCR assay may be useful in predicting the histological response to biochemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Nitric oxide and neopterin levels and clinical response in stage III melanoma patients receiving concurrent biochemotherapy.

The combination of cisplatin-based chemotherapy with interleukin-2 (IL-2) and interferon-alpha (IFN-alpha), referred to as biochemotherapy, has produced overall response rates of greater than 50% in advanced melanoma patients, with durable complete responses in the range of 5-10%. The mechanism of action of biochemotherapy is unknown. Preclinical work suggests synergistic interactions between the cytotoxic agents, especially cisplatin, and the biological agents in killing melanoma cells. Immune effector cells activated by the components of the biochemotherapy may also be involved, as direct cytotoxic effectors and/or as sources of secondary cytokines, which can induce nitric oxide (NO) production in a wide variety of cell types. In addition, high levels of neopterin, a marker of monocyte/macrophage activation, have been found in patients undergoing immunotherapy or biochemotherapy for melanoma. Based on these data, we hypothesized that the degree of elevation of serum NO metabolic products and neopterin during treatment would correlate with the response to biochemotherapy in melanoma patients. Blood samples were obtained before and during preoperative biochemotherapy with cisplatin, vinblastine, dacarbazine, IL-2 and IFN-alpha in 45 melanoma patients with locoregionally advanced disease. NO was measured as nitrite after enzymatic reduction, using the colorimetric assay of Griess, and neopterin was measured by radioimmunoassay. Our results demonstrate a higher day 5 nitrite level (of borderline statistical significance, P = 0.057) in major responders to the therapy than in those who did not achieve a major response, while there was no difference in the elevation in neopterin level during therapy between major and non-major responders. These results suggest that induction of NO during biochemotherapy may be playing a role in the mechanism of action of this therapy, while the role of monocyte/macrophage activation is still in question.

Adult↗
PubMed1998

Phase II study of neoadjuvant concurrent biochemotherapy in melanoma patients with local-regional metastases.

Our results with concurrent biochemotherapy in patients with stage IV melanoma have been encouraging. Based on these data, we conducted a phase II study to determine the clinical and histological response rate to neoadjuvant concurrent biochemotherapy in patients with local-regional metastases of cutaneous melanoma (stage III). A total of 65 patients with biopsy-proven, measurable and potentially resectable local-regional disease (nodal, satellite/in-transit metastases and/or local recurrence) were treated with cisplatin 20 mg/m2 intravenously (i.v.) on days 1 to 4, vinblastine 1.5 mg/m2 i.v. on days 1 to 4, dacarbazine 800 mg/m2 i.v. on day 1 only, interleukin-2 9 MIU/m2 per day i.v. by 96 h continuous infusion on days 1 to 4, and interferon-alpha 2a 5 MU/m2 subcutaneously on days 1 to 5, repeated every 3 weeks. Patients underwent surgery after two to four courses of biochemotherapy. Those with tumour regression after two preoperative courses received two additional postoperative courses. Of the 64 patients assessable for clinical response, 28 (44%) had a partial response. Of the 62 patients whose response was assessed histologically, four (6.5%) had no evidence of viable tumour in the surgical specimen (pathological complete remission, pCR) and 27 (43.5%) had a partial response, giving an overall response rate of 50%. Tumour burden did not correlate with response, although patients who achieved a pCR had a significantly lower tumour burden (P = 0.02). Our phase II study indicates that neoadjuvant biochemotherapy is an active treatment for melanoma patients with local-regional metastases. However, it is unclear if biochemotherapy is more active than chemotherapy alone; phase III randomized trials are ongoing to answer this question in patients with stage IV disease.

Adolescent↗
PubMed1998

Development of a biochemotherapy regimen with concurrent administration of cisplatin, vinblastine, dacarbazine, interferon alfa, and interleukin-2 for patients with metastatic melanoma.

PURPOSE: To evaluate the antitumor activity and toxicity of concurrent biochemotherapy that uses cisplatin, vinblastine, and docarbazine (DTIC) (CVD) in combination with interferon alfa-2a (IFN-alpha) and interleukin-2 (IL-2) in patients with metastatic melanoma. PATIENTS AND METHODS: Between October 1992 and October 1993, 53 patients with a documented diagnosis of metastatic melanoma with measurable lesions and an Eastern Oncology Cooperative Group (ECOG) performance status of 2 or less were enrolled onto this study. Patients were required to have no clinically significant cardiac dysfunction and to be free from symptomatic brain metastases. The treatment consisted of cisplatin 20 mg/m2 daily for 4 days; vinblastine 1.6 mg/m2 daily for 4 days; and DTIC 800 mg/m2 intravenously (i.v.) day 1 with IL-2 9 x 10(6) IU/m2 i.v. by continuous infusion daily for 4 days and IFN-alpha 5 x 10(6) U/m2 subcutaneously daily for 5 days, repeated at 21-day intervals. Response was assessed after two cycles and patients who responded were continued on treatment for a total of six cycles. RESULTS: Among 53 assessable patients, 11 patients (21%) achieved a complete response (CR) and 23 patients (43%) achieved a partial response (PR), for an overall objective response rate of 64%. The median time to disease progression for all patients was 5 months. The median survival of all patients entered onto the trial was 11.8 months. Among the 11 patients who achieved a CR, five patients (9%) have remained in continuous CR for 50+ to 61+ months. The toxicity of biochemotherapy consisted of severe myelosuppression, significant nausea and vomiting, and moderately severe hypotension that required inpatient hospital care for each 5-day cycle of treatment. There were no treatment-related deaths. CONCLUSION: Concurrent biochemotherapy for patients with advanced melanoma is capable of producing high CR and overall response rates and resulted in durable complete remissions in a small fraction of patients. Toxicity, although severe, was manageable in a routine inpatient hospital environment.

Adult↗
PubMed1997

Angiopoietin-2, a natural antagonist for Tie2 that disrupts in vivo angiogenesis.

Angiogenesis is thought to depend on a precise balance of positive and negative regulation. Angiopoietin-1 (Ang1) is an angiogenic factor that signals through the endothelial cell-specific Tie2 receptor tyrosine kinase. Like vascular endothelial growth factor, Ang1 is essential for normal vascular development in the mouse. An Ang1 relative, termed angiopoietin-2 (Ang2), was identified by homology screening and shown to be a naturally occurring antagonist for Ang1 and Tie2. Transgenic overexpression of Ang2 disrupts blood vessel formation in the mouse embryo. In adult mice and humans, Ang2 is expressed only at sites of vascular remodeling. Natural antagonists for vertebrate receptor tyrosine kinases are atypical; thus, the discovery of a negative regulator acting on Tie2 emphasizes the need for exquisite regulation of this angiogenic receptor system.

Amino Acid Sequence↗
PubMed1997

Molecular basis of HNPCC: mutations of MMR genes.

Hereditary nonpolyposis colorectal cancer (HNPCC) is inherited as a dominant disorder caused by germline defects in one of at least four mismatch repair (MMR) genes. Two of these genes, hMSH2 and hMLH1, account for the vast majority of the germline mutations in HNPCC kindreds, whereas hPMS1 and hPMS2 are mutated in only few families. MMR genes also are susceptible to somatic mutations in sporadic tumors. The mutational spectrum of the MMR genes shows no predominant type of mutation. Furthermore, the mutations are spread throughout the length of the genes, with no significant hot spots. Identification of MMR genes as the cause of HNPCC made presymptomatic diagnosis a reality. However, the presence of multiple genes and the heterogeneity of mutations present challenges to the development of diagnostic tests for this disease.

Adaptor Proteins, Signal Transducing↗