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Biomedical subjects

M Serrano

Publications and source records attributed to M Serrano.

At least 91 records · Page 5Linked to original sources
PubMed1995

Deletion of the p16 and p15 genes in human bladder tumors.

BACKGROUND: Two genes, p16 (also known as CDKN2, INK4A, or MTS1) and p15 (also described as INK4B or MTS2), are found in tandem at chromosome 9p21. These genes are designated as candidate tumor suppressor genes because they encode proteins that function as negative cell cycle regulators. (The encoded polypeptides inactivate specific cyclin-protein kinase complexes that are required for progression through the cell cycle.) Molecular genetic studies have revealed that deletion of the p16 and p15 genes occurs frequently in cancer cell lines and in certain malignant neoplasms. PURPOSE: We evaluated the frequency of p16 and p15 gene alterations in a well-characterized cohort of human transitional cell bladder cancers, and we explored potential associations between alterations in these genes and tumor stage and/or grade. METHODS: Tumor tissue and normal tissue from 110 patients with transitional cell carcinoma of the urinary bladder were examined. The status of the p16 and p15 genes in these tissues was determined by Southern blotting and hybridization with gene-specific probes, by coupled polymerase chain reaction and single-strand conformation polymorphism analysis (PCR-SSCP), and by sequencing DNA fragments produced during PCR. Associations between alterations in the genes and tumor stage and/or grade were evaluated using the two-tailed Fisher's exact test. RESULTS: Homozygous deletion (both alleles lost) of the p16 and the p15 genes was observed in 11 and nine bladder tumors, respectively. Eight of the 11 tumors exhibiting complete loss of the p16 gene also displayed homozygous deletion of the p15 gene. Exclusive loss of either gene was detected in only three tumors. Hemizygous deletion (one allele lost, also referred to as loss of heterozygosity [LOH] of the p16 and/or p15 genes was observed in eight tumors. Rearrangement of the two genes was indicated in three additional tumors. No point mutations were identified in either gene. The overall frequency of alteration in this cohort of bladder tumors was approximately 18% for each gene (in 20 [18.3%, 95% confidence interval (CI) = 11.1%-25.6%] of 109 informative tumors for the p16 gene and in 18 [18%, 95% CI = 10.5%-25.5%] of 100 informative tumors for the p15 gene). A statistically significant association between p16 gene alteration and bladder tumors of low stage (P < .01) and grade (P < .01) was observed; a significant association between p15 gene alteration and tumors of low stage (P < .01) was also detected. CONCLUSIONS: Alteration of the p16 and p15 genes, especially coincident homozygous deletion, appears to be a common event in bladder cancer.

Aged↗
PubMed1995

A p16INK4a-insensitive CDK4 mutant targeted by cytolytic T lymphocytes in a human melanoma.

A mutated cyclin-dependent kinase 4 (CDK4) was identified as a tumor-specific antigen recognized by HLA-A2. 1-restricted autologous cytolytic T lymphocytes (CTLs) in a human melanoma. The mutated CDK4 allele was present in autologous cultured melanoma cells and metastasis tissue, but not in the patient's lymphocytes. The mutation, an arginine-to-cysteine exchange at residue 24, was part of the CDK4 peptide recognized by CTLs and prevented binding of the CDK4 inhibitor p16INK4a, but not of p21 or of p27KIP1. The same mutation was found in one additional melanoma among 28 melanomas analyzed. These results suggest that mutation of CDK4 can create a tumor-specific antigen and can disrupt the cell-cycle regulation exerted by the tumor suppressor p16INK4a.

Amino Acid Sequence↗
PubMed1995

Cloning and characterization of murine p16INK4a and p15INK4b genes.

Progression through the G1 phase of the cell cycle is regulated in part by the D-type cyclin-dependent kinases, cdk4 and cdk6. Genes encoding two specific inhibitors of these kinases, human p16(INK4a/MTS1) and p15(INK4b/MTS2), map to a region of common cytogenetic abnormalities on chromosome 9p21. The murine cognates of these genes were isolated and identified as mouse p16INK4a and p15INK4b based on their homology to their human counterparts and their selective transcriptional induction by SV40T-antigen and TGF-beta, respectively. Both genes map to position C3-C6 on mouse chromosome 4, in a region syntenic with human chromosome 9p. Amplification of polyadenylated mRNA by polymerase chain reactions revealed no expression of mouse p16INK4a in many normal tissues, whereas p15INK4b was expressed ubiquitously. Like human p16INK4a, mouse p16INK4a binds specifically to cdk4 and cdk6 in vitro and inhibits the phosphorylation of the retinoblastoma protein, pRb, by each of these cyclin D-dependent kinases. In mouse MEL erythroleukemia cells, p16INK4a associates preferentially with cdk6 under conditions where cdk4 and cdk6 are coexpressed at equivalent levels. Expression vectors encoding human or mouse p16INK4a caused G1 phase arrest in NIH3T3 fibroblasts, and cyclin D1- and cdk4-dependent pRb kinase activities were inhibited in the p16INK4a-arrested cells.

3T3 Cells↗
PubMed1995

Mutational effects on the p16INK4a tumor suppressor protein.

Several point mutations of p16INK4a were studied by site-specific mutagenesis and functional analysis to assess the effects of these mutations on the function of the protein. These mutations were reported in several malignancies. Three deletional mutants of p16INK4a were also analyzed to reveal the relationship between p16INK4a and p15INK4b and to test the importance of the ankyrin repeats observed in both proteins. We studied the activity of these mutants using the yeast two-hybrid system and an in vitro kinase assay. Our results suggest that point mutations in the conserved ankyrin consensus affect the activity of p16INK4a. However, not all of the point mutations observed in tumors have a detectable effect on the activity. The COOH-terminal region of p16INK4a is not required for the protein to bind and to inhibit CDK4, but the deletion of the 4th ankyrin repeat abolished the activity completely.

Amino Acid Sequence↗
PubMed1995

Association of rat p15INK4B/p16INK4 deletions with monosomy 5 in kidney epithelial cell lines but not primary renal tumors.

Recently the putative tumor suppressor gene p16INK4 was mapped to human chromosome 9p21, which is homologous to rat chromosome 5. Monosomy of rat chromosome 5 occurs with high frequency in rat kidney tumor-derived cell lines (ERC lines). Thus, we studied these lines in order to investigate the involvement of p15INK4B and p16INK4 in the genesis of this tumor type. p15INK4B and p16INK4 were found by Southern blot analysis to be codeleted in five of seven of these lines. This was confirmed by Northern blot analysis with a probe for the rat p15INK4B gene. In normal rat tissues, expression of p15INK4B was abundant in lung (2.5 and 2.0 kilobases), less abundant in testis (2.5, 2.0, 1.1, and 0.9 kilobases), barely detectable in liver (2.0 kilobases), and not detectable in neonatal kidney, adult kidney, brain, heart, or spleen. In the ERC lines, p15INK4B was expressed as a single 2.0-kilobase transcript observed only in those cell lines in which the gene was detected by Southern blot analysis. However, neither p15INK4B nor p16INK4 were deleted in 12 of 12 primary kidney tumors examined, suggesting that deletion of these genes is not directly involved in the process of renal tumor development but may be related to tumor progression or autonomous growth in vitro. A panel of rat kidney epithelial cell lines chemically transformed in vitro (TRKE lines) that had high-frequency monosomy 5 were also examined, but deletion of p15INK4B and p16INK4 was observed in only one of six of the TRKE lines. To our knowledge, this is the first reported investigation of these genes in rodent tumors and cell lines, and its data support the theory that alterations of genes located in the INF region of rat chromosome 5 may play a role in rodent cell transformation.

Animals↗
PubMed1995

[Non-Hodgkin's lymphomas associated with the acquired immunodeficiency syndrome. A multicenter clinical study of 77 cases].

BACKGROUND: The aim of the present was to study the prevalence of non Hodgkin's lymphoma (NHL) in AIDS patients as well as the clinicopathologic characteristics, response to treatment and survival. METHODS: From January 1984 to January 1991, 77 patients with NHL associated with AIDS diagnosed in 9 hospitals in Madrid were retrospectively studied. RESULTS: Ninety-two per cent of the patients were men (mean age 30 years: range: 9-66 years), 62% were intravenous drug abusers and 20 (26%) homosexuals. Pathologic study determined that 62 (80%) patients had high grade NHL (44% small noncleaved), 17% immunoblastic and 20% unclassifiable, and 15 (20%) had intermediate grade (16% diffuse large cell) being all the cases of the B immunophenotype. Sixty-five per cent were in advanced stages and 69% had B symptoms. Extranodal localizations were present in 88%, bone marrow in 29% and CNS in 29%. Six cases had primary CNS lymphomas. 50% of the patients had less than 200 x 10(6)/l CD4 lymphocytes. Forty-seven patients were evaluable for response to chemotherapy: 12 (26%) showed a complete response 27 (57%) a partial response and 8 (17%) did not respond. Opportunistic infections developed in 18%. The estimated survival at 3 years was 14% (median 6 months). On univariate analysis the parameters related to the worst survival were: primary CNS lymphoma, liver involvement, lack of treatment response, LDH > or = 300 UI/l, alkaline phosphatase > or = 500 UI/l and ESR > or = 70 mm. CONCLUSIONS: Non Hodgkin's lymphomas associated with AIDS usually behave in an "aggressive" way with a high frequency of advanced stages, B symptoms, high grade histologic subtypes and extranodal involvement. Response to treatment is poor, bone marrow toxicity frequent and survival short.

Adolescent↗
PubMed1995

Mutations in the p16INK4/MTS1/CDKN2, p15INK4B/MTS2, and p18 genes in primary and metastatic lung cancer.

We examined the genomic status of cyclin-dependent kinase-4 and -6 inhibitors, p16INK4,p15INK4B, and p18, in 40 primary lung cancers and 31 metastatic lung cancers. Alterations of the p16INK4 gene were detected in 6 (2 insertions and 4 homozygous deletions) of 22 metastatic non-small cell lung cancers (NSCLCs; 27%), but none were detected in 25 primary NSCLCs, 15 primary small cell lung cancers (SCLCs), or 9 metastatic SCLCs, indicating that mutation in the p16INK4 gene is a late event in NSCLC carcinogenesis. Although three intragenic mutations of the p15INK4B gene were detected in 25 primary NSCLCs (12%) and five homozygous deletions of the p15INK4B gene were detected in 22 NSCLCs (23%), no genetic alterations of the p15INK4B gene were found in primary and metastatic SCLCs. The p18 gene was wild type in these 71 lung cancers, except 1 metastatic NSCLC which showed loss of heterozygosity. We also examined alterations of these three genes and expression of p16INK4 in 21 human lung cancer cell lines. Alterations of the p16INK4 and p15INK4B genes were detected in 71% of the NSCLC cell lines (n = 14) and 50% of the NSCLC cell lines (n = 14), respectively, but there were none in the 7 SCLC cell lines studied. No p18 mutations were detected in these 21 cell lines. These results indicate that both p16INK4 and p15INK4B gene mutations are associated with tumor progression of a subset of NSCLC, but not of SCLC, and that p15INK4B mutations might also be an early event in the molecular pathogenesis of a subset of NSCLC.

Base Sequence↗
PubMed1995

Inhibition of ras-induced proliferation and cellular transformation by p16INK4.

The cyclin-dependent kinase 4 (CDK4) regulates progression through the G1 phase of the cell cycle. The activity of CDK4 is controlled by the opposing effects of the D-type cyclin, an activating subunit, and p16INK4, an inhibitory subunit. Ectopic expression of p16INK4 blocked entry into S phase of the cell cycle induced by oncogenic Ha-Ras, and this block was relieved by coexpression of a catalytically inactive CDK4 mutant. Expression of p16INK4 suppressed cellular transformation of primary rat embryo fibroblasts by oncogenic Ha-Ras and Myc, but not by Ha-Ras and E1a. Together, these observations provide direct evidence that p16INK4 can inhibit cell growth.

Adenovirus E1A Proteins↗
PubMed1995

Mutations associated with familial melanoma impair p16INK4 function.

Cell division is controlled by a series of positive and negative regulators which act at sequential points throughout the cell cycle. Disturbance of these checks could contribute to cancer by allowing excessive cell proliferation. The point in G1 at which cells irrevocably commit to DNA synthesis is controlled by protein complexes consisting of cyclin-dependent kinases (CDK4 or CDK6) and cyclins (D1, D2 or D3). These complexes are inhibited by low molecular weight proteins, such as p16INK4 (refs 1,2), p15INK4B (ref. 3) and p18 (ref. 4). Deletion or mutation of these CDK-inhibitors could lead to unchecked cell growth, suggesting that members of the p16INK4 family may be tumour suppressor genes. The recent detection of p16INK4 (MTS1) mutations in familial melanoma kindreds, many human tumour cell lines, and primary tumours is consistent with this idea. Previously, we described eight germline p16INK4 substitutions in 18 familial melanoma kindreds. Genetic analyses suggested that five mutations predisposed carriers to melanoma, whereas two missense mutations had no phenotypic effect. We now describe biochemical analyses of the missense germline mutations and a single somatic mutation detected in these families. Only the melanoma-predisposing mutants were impaired in their ability to inhibit the catalytic activity of the cyclin D1/CDK4 and cyclin D1/CDK6 complexes in vitro. Our data provide a biochemical rationale for the hypothesis that carriers of certain p16INK4 mutations are at increased risk of developing melanoma.

Animals↗
PubMed1995

Gastric B-cell mucosa-associated lymphoid tissue (MALT) lymphoma. Clinicopathological study and evaluation of the prognostic factors in 143 patients.

BACKGROUND: Gastric MALT lymphoma can be histologically classified into two groups, low-grade (LG) and high-grade (HG); however, their natural history is poorly understood. We have studied a large retrospective series aiming to confirm whether the histological groups confer different clinical features and behavior and to analyze the prognostic factors in these patients. PATIENTS AND METHODS: A series of 143 gastric B-cell MALT lymphomas is reported. Eighty-four were low-grade lymphomas (LG) and 59 were high-grade lymphomas (HG). Median follow-up was 36 months. The clinical and analytical parameters of the 84 LG patients were compared with those of the 59 HG patients. In the patients who had been operated on, the pathological features (macroscopical patterns, tumor size, involvement of resection margins, degree of parietal invasion and involvement of abdominal lymph nodes and adjacent viscera) of the LG patients were compared with those of the HG patients. The sites of relapses were studied. In the 132 treated and followed-up patients the influence of the treatment and that of clinical, analytical and pathological features on survival were investigated with the Kaplan and Meier and log-rank tests. To identify the factors with independent influence on survival, a Cox model was fitted for the whole series and separately for 53 HG patients. RESULTS: HG group differed from the LG group by a significantly higher frequency of weight loss at presentation, palpable abdominal mass, hepatomegaly, peripheral lymphadenopathy, elevated serum LDH, higher incidence of stage III-IV and tumor/mass patterns in the endoscopy and in the gastrectomy specimen. The tumor was significantly larger in the HG group than in the LG and the deeper invasion of the gastric wall, the higher frequency of infiltration of the abdominal lymph nodes and the visceral extension were also significant in the HG group. Complete remission (CR) was achieved in 91% of the patients of the LG group, but was significantly lower, 70%, in the HG group. Relapses occurred in the stomach and also in non-MALT sites. In 132 treated and followed-up patients, elevated serum LDH, absence of CR, HG group and stage III-IV were associated with a worse survival. In the Cox multivariate model, stage was the only variable influencing survival, although stage was related to the histological grade. In the HG group, stage was also an independent significant risk factor, whereas treatment with surgery, chemotherapy or both was not. In the 103 patients treated with surgery, a worse survival was associated with the involvement of the resection borders, depth of the infiltration of the gastric wall, dissemination to distant abdominal nodes and adjacent organs, but not with the addition of chemotherapy. CONCLUSIONS: Histological classification into LG and HG separates distinctive groups of gastric MALT lymphoma that show striking clinical and prognostic differences. Besides histological grade, stage is the most important prognostic feature.

Aged↗
PubMed1995

Protein-nucleic acid interactions in bacteriophage phi 29 DNA replication.

phi 29 DNA replication starts at both DNA ends by a protein priming mechanism. The formation of the terminal protein-dAMP initiation complex is directed by the second nucleotide from the 3' end of the template. The transition from protein-primed initiation to normal DNA elongation has been proposed to occur by a sliding-back mechanism that is necessary for maintaining the sequences at the phi 29 DNA ends. Structure-function studies have been carried out in the phi 29 DNA polymerase. By site-directed mutagenesis of amino acids conserved among distantly related DNA polymerases we have shown that the N-terminal domain of phi 29 DNA polymerase contains the 3'-5' exonuclease activity and the strand-displacement capacity, whereas the C-terminal domain contains the synthetic activities (protein-primed initiation and DNA polymerization). Viral protein p6 stimulates the initiation of phi 29 DNA replication. The structure of the protein p6-DNA complex has been determined, as well as the main signals at the phi 29 DNA ends recognized by protein p6. The DNA binding domain of protein p6 has been studied. The results indicate that an alpha-helical structure located in the N-terminal region of protein p6 is involved in DNA binding through the minor groove. The phi 29 protein p5 is the single-stranded DNA binding (SSB) protein involved in phi 29 DNA replication, by binding to the displaced single-stranded DNA (ssDNA) in the replication intermediates. In addition, protein p5 is able to unwind duplex DNA. The properties of the phi 29 SSB-ssDNA complex are described. Using the four viral proteins, terminal protein, DNA polymerase, protein p6 and the SSB protein, it was possible to amplify the 19,285-bp phi 29 DNA molecule by a factor of 4000 after 1 h of incubation at 30 degrees C. The infectivity of the in vitro amplified DNA was identical to that of phi 29 DNA obtained from virions.

Bacillus Phages↗
PubMed1995

Pneumonia caused by Listeria monocytogenes.

Pneumonia due to Listeria monocytogenes is extremely uncommon. We report the case of an 87-year-old woman with no underlying immunosuppressive disease who presented with listerial pneumonia. Cutaneous anergy and a decrease in total lymphocyte count in this elderly woman could predispose her to listerial infection.

Adult↗
PubMed1995

Debrisoquine oxidation polymorphism in patients with chronic inflammatory bowel disease.

Polymorphic hydroxylation of debrisoquine (DBQ) is a Mendelian genetic trait related to the risk of suffering some spontaneous disorders. To elucidate whether such a relation exists between this polymorphism and chronic inflammatory bowel disease (CIBD), 67 (39 males) patients with ulcerative colitis (UC), 52 (35 males) patients with Crohn's disease (CD) and 837 healthy controls (391 males) received 10 mg debrisoquine. DBQ and its metabolite, 4-OH-DBQ, were measured in urine to calculate metabolic ratio. Subjects with MR < 12.6 (log 10 MR < 1.1) were extensive metabolizers (EM) of DBQ, whereas those with MR < 12.6 were poor metabolizers (PM). Four UC (5.97%), 1 CD (1.92%) patients and 42 controls (5.03%) were PM of DBQ (nonsignificant difference). When analysing the EM subjects separately, log10 MR were lower in controls (mean = -0.295, SD 0.427, P = 0.0015)) and in Crohn's disease patients (man = -0.281, SD 0.495, P = 0.03) than in ulcerative colitis patients (mean = -0.085, SD = 0.495). There is no relationship between oxidative phenotype of DBQ and the risk for CIBD. Nevertheless, the EM phenotype includes both homo- and heterozygote genotypes for functioning alleles exerting a gene-dose effect that gives a higher oxidative capability to homozygote EMs, reflected in a lower MR value. Genotyping studies are needed to disclose whether heterozygote EMs are over-represented among UC patients and to identify any nonfunctioning allele possibly linked to the risk of developing this disease.

Adult↗
PubMed1995

[The follow-up of transposition of the great arteries corrected by Senning's technic].

INTRODUCTION AND OBJECTIVES: The incidence of late complications after a physiological correction of the patients with transposition of the great arteries (D-TGA) is very significant, due to the alternative operation of the arterial switch. METHODS: We studied 125 patients with D-TGA, treated with Senning surgical correction between december of 1978 and november of 1990. Surgery was performed at a mean age of 11.7 months (from 7 days to 11.2 years), and the postoperative mean follow-up was 7.3 years (from 1.4 to 14.3 years). We analyzed their evolutive clinical condition, ECG, Holter and echocardiogram-Doppler. Four groups were defined: A) Simple, 48.8%. B) Associated with ventricular septal defect, 22.4%. C) With pulmonary stenosis, 15.2%. D) Both anomalies, 13.6%. RESULTS: Sixteen children died (12.8%), 11 of them on the postoperative period. The remaining 5 patients died, at a mean time of 34.3 months after surgery, because they were in cardiac failure. All of patients had enlargement of right ventricle and tricuspid regurgitation was observed in 39 children. There were 3 reoperations. Atrioventricular block was observed in 5.7% of the patients, 33.3% were not in sinus rhythm, 6.6% had atrial flutter-fibrillation, sinus node dysfunction was observed in 24.7%, and five permanent pacemakers were implanted (4.7%). CONCLUSIONS: The later mortality is not high, and the clinical outcome is good, but the frequent rhythm disturbances and enlargement of the right ventricle could let us conclude the hypothesis that anatomical correction is an optimal alternative procedure.

Analysis of Variance↗
PubMed1995

Cost efficient management of educational material.

We retrospectively examined direct and indirect costs of providing a programmed text in Respiratory Pathophysiology using World-Wide Web (WWW) technology as compared to printed paper. The direct costs were $3678 and $3988 respectively. Neither of these costs includes the substantial cost of original development of the educational material. The indirect cost of distributing printed material is $1800. The indirect cost for electronic material is $1430 but this assumes an institutional commitment to a technology infrastructure which will be used for purposes other than just educational material distribution. Given such a commitment, educational material can be managed in a way that provides efficient distribution at less cost than traditional paper distribution. The effectiveness of electronic methods is dependent on usage. A comparison study of use and satisfaction of paper and electronic versions of the material is planned.

Computer Communication Networks↗
PubMed1995

[Genetic predisposition to develop insulin-dependent diabetes mellitus. A population study in Santiago and Temuco, Chile].

Insulin-dependent diabetes mellitus (IDDM) is strongly associated with particular HLA-DQ alpha/beta markers in white population. The heterodimers conformation composed of a DQ alpha chain with an arginine at residue 52 (Arg52) combined to a DQ beta chain lacking an aspartic acid at residue 57 (non Asp57) increase markedly the risk to develop IDDM. To confirm this association, 63 IDDM patients from Santiago de Chile registry, 20 IDDM patients from Temuco registry and 74 unrelated healthy non diabetic control subjects were studied. With polymerase chain reaction (PCR) and sequence specific oligonucleotide probes the individuals were typed for their HLA-DQA1 and DQB1 alleles, their DQA1/DQB1 genotype and heterodimers conformation were compared. In diabetic population both markers Arg52 homocygote and non Asp57 homocygote were markedly increased regard to control subjects (R/R: 0.76 and 0.85 vs 0.33; ND/ND: 0.78 and 0.75 vs 0.50, p < 0.05). A high relative risk (RR) was determined for both homocygote markers in IDDM groups. Arg52 DQ alpha (R)/non Asp57 DQ beta (ND) heterodimers were strongly associated with susceptibility to IDDM. A high RR was observed in patients with four susceptibility DQ heterodimers (RR1: 13.7 in IDDM-Santiago and RR2: 18.6 in IDDM-Temuco, p < 0.00003). The HLA-DQ alpha/beta markers and their risk heterodimers are increased in our diabetic population and could be considered as susceptibility markers to develop IDDM.

Adolescent↗