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A Quintero

Publications and source records attributed to A Quintero.

At least 19 recordsLinked to original sources
PubMed2006

Cyclin D3 expression in primary Ta/T1 bladder cancer.

Cyclin D3 deregulation has recently been reported in bladder cancer but its prognostic significance remains uncertain. A cohort of 159 patients with stage Ta or T1 primary bladder tumours was investigated to determine the significance of cyclin D3 expression in association with other G1-S phase regulators of the cell cycle (p53, p21Waf1, p27kip1, cyclin D1), including tumour proliferation (ki67-MIB1); its association with conventional clinicopathological parameters; and the relationship between cyclin D3 and loss of heterozygosity (LOH) at the 9p21 (p16INK4a locus) chromosome region. The end point of the study was progression-free survival. Cyclin D3, other G1-S phase regulators, and tumour proliferation were investigated by immunohistochemistry and measured by the grid-counting method. To validate the immunohistochemical expression, cyclin D3 was additionally assessed by western blotting in selected cases. LOH at the 9p21 chromosome region (marker D9S171) was assessed in 125 cases using an AB Prism 310 genetic analyser and a set of microsatellite fluorescence-labelled primers. Cyclin D3 overexpression was related to larger tumour size (>5 cm; p < 0.0001) and high tumour proliferation (>10%; p = 0.025). Mean cyclin D3 expression increased with 2004 WHO grading categories in stage Ta (p = 0.035, ANOVA) and stage T1 (p = 0.047, t test) tumours. Cyclin D3 was not related to other clinicopathological parameters, G1-S phase modulators, or 9p21 LOH. Cox's multivariate analysis selected cyclin D3 as an independent predictor of progression-free survival (p = 0.0012, relative risk (RR) = 5.2366) together with tumour size (p = 0.0115, RR = 4.4442) and cyclin D1 (p = 0.0065, RR = 3.3023). Cyclin D3 expression had the highest risk ratio. Our results suggest that expression of cyclin D3 is relevant to the progression-free survival of patients with Ta/T1 bladder carcinomas.

Adult↗
PubMed2006

Ki-67 MIB1 labelling index and the prognosis of primary TaT1 urothelial cell carcinoma of the bladder.

AIMS: To evaluate whether ki-67 labelling index (LI) has independent prognostic value for survival of patients with bladder urothelial tumours graded according to the 2004 World Health Organisation classification. METHODS: Ki-67 LI was evaluated in 164 cases using the grid counting method. Non-invasive (stage Ta) tumours were: papilloma (n = 5), papillary urothelial neoplasia of low malignant potential (PUNLMP; n = 26), and low (LG; n = 34) or high grade (HG; n = 15) papillary urothelial carcinoma. Early invasive (stage T1) tumours were: LG (n = 58) and HG (n = 26) carcinoma. Statistical analysis included Fisher and chi2 tests, and mean comparisons by ANOVA and t test. Univariate and multivariate survival analyses were performed according to the Kaplan-Meier method with log rank test and Cox's proportional hazard method. RESULTS: Mean ki-67 LI increased from papilloma to PUNLMP, LG, and HG in stage Ta (p<0.0001) and from LG to HG in stage T1 (p = 0.013) tumours. High tumour proliferation (>13%) was related to greater tumour size (p = 0.036), recurrence (p = 0.036), progression (p = 0.035), survival (p = 0.054), and high p53 accumulation (p = 0.015). Ki-67 LI and tumour size were independent predictors of disease free survival (DFS), but only ki-67 LI was related to progression free survival (PFS). Cancer specific overall survival (OS) was related to ki-67 LI, tumour size, and p27kip1 downregulation. Ki-67 LI was the main independent predictor of DFS (p = 0.0005), PFS (p = 0.0162), and cancer specific OS (p = 00195). CONCLUSION: Tumour proliferation measured by Ki-67 LI is related to tumour recurrence, stage progression, and is an independent predictor of DFS, PFS, and cancer specific OS in TaT1 bladder urothelial cell carcinoma.

Adult↗
PubMed2004

Prognostic factors in stage T1 grade 3 bladder cancer survival: the role of G1-S modulators (p53, p21Waf1, p27kip1, Cyclin D1, and Cyclin D3) and proliferation index (ki67-MIB1).

OBJECTIVE: To determine the prognostic value of a subset of regulators of the transition from G1-to-S phase of cell cycle in stage T1 grade 3 bladder cancers. METHODS: Fifty-one such cases were investigated to determine the significance on patient's survival of p53, p21Waf1, p27Kip1, Cyclin D1, Cyclin D3, and ki67-MIB1 (proliferation index). The statistical analysis included Kaplan-Meier methodology with Log-rank test and Cox' proportional hazard analysis. RESULTS: Tumor size (p=0.0034), and the labeling index of ki67-MIB1 (p=0.0034), p53 (p=0.0332), p27kip1 (p=0.0059) and Cyclin D1 (p=0.0103) were associated to disease-free survival. Progression-free survival was related to tumor size (p<0.0001), ki67 (p=0.0163), p53 (p=0.0041), p27kip1 (p=0.0161), Cyclin D1 (p<0.0001) and Cyclin D3 (p<0.0001). Patient's overall survival was associated to Cyclin D3 (p<0.0001), p53 (p=0.0017), p21Waf1 (p=0.0142), Cyclin D1 (p<0.0001), ki67-MIB1 (p=0.0450), and tumor size (p=0.0296). Down-regulation of p27kip1 and Cyclin D3 over-expression (disease-free), over-expression of p53, Cyclin D1 and Cyclin D3 (progression-free), and over-expression of Cyclin D3 (overall survival) were independent predictors by Cox's multivariate analysis. Down-regulation of p27kip1 (p<0.001, R.R. 0.997, 95%C.I. 0.995-0.999), and over-expression of Cyclin D1 (p<0.001, R.R. 1.009, 95%C.I. 1.004-1.014) and Cyclin D3 (p=0.005, R.R. 1.013, 95%C.I. 1.004-1.022) were the main independent predictors. CONCLUSION: Down-regulation of p27kip1 and over-expression of Cyclin D1 and Cyclin D3 might be relevant predictors of survival in stage T1 grade 3 bladder cancers, thus selecting a group of patients at higher risk of malignant behavior.

Adjuvants, Immunologic↗
PubMed2003

Hepatoid adenocarcinoma of the urinary bladder.

Hepatoid adenocarcinoma is rare in the urinary bladder with only three well-illustrated previously reported cases. Pathological diagnosis is based on a combination of histological features resembling hepatocellular carcinoma and the positive immunostaining for alpha-fetoprotein. We present the clinicopathological features of four additional cases. The patients were males 66, 85, 61 and 68 years old. Hematuria was the initial symptom in all four patients. Two cases were treated by cystoprostatectomy and the remaining two by transurethral resection of the bladder. On histology, the cases showed a mixture of cells growing in a solid fashion and sheets or anastomosing trabeculae of hepatoid cells merging focally with a secondary glandular pattern of adenocarcinoma. Intracytoplasmic hyaline globules in all and bile production in three of the cases also supported the impression of hepatocytic differentiation. Immunoreactivity for alpha-fetoprotein, low molecular weight cytokeratin, alpha-1-antitrypsin, albumin, epithelial membrane antigen and a striking canalicular pattern when stained against polyclonal carcinoembryonic antigen (CEA), all indicate hepatocellular differentiation. The hepatic nature of the cells was further assessed by detecting the recently incorporated marker hepatocyte paraffin 1, by means of immunohistochemistry and albumin gene mRNA non-isotopic in situ hybridization, both of which had positive signals in all four cases. Three patients died 12, 14 and 19 months after diagnosis. The fourth patient was alive with disease at 26 months of follow-up. In conclusion, hepatoid adenocarcinoma seems to be an aggressive malignant neoplasm that is rare in the bladder whose correct diagnosis may need appropriate immunohistochemical and in situ hybridization means in addition to a complete patient clinical and pathological evaluation. The exact histogenesis and classification of these tumors remains to be established.

Adenocarcinoma↗
PubMed2003

1H,13C 2D NMR and X-ray studies of the products of the reaction between dibenzylidencyclohexanone and 6-amino-1,3-dimethyl uracil.

The reaction of the 6-amino-1,3-dimethyl uracil with the dibenzylidencyclohexanone (1), provided three adducts whose structures result from nucleophilic attack yielding the monoadduct 3 and two isomeric bisadducts (4 and 5) in moderate yields (50-60%). The structures obtained in this study were elucidated with 2D high resolution NMR experiments, variable temperature NMR and X-ray crystallographic studies. In compound 3, the tricyclic skeleton is essentially planar and the cyclohexane ring addopts an envelope conformation. The structures 4 and 5 correspond to two isomeric spiro compounds.

Crystallography, X-Ray↗
PubMed2002

Molecular epidemiology of hepatitis B virus in Afro-Venezuelan populations.

Hepatitis B virus (HBV) infection among Venezuelan populations of African origin was analyzed. These populations exhibited lower HBV prevalence than the one found in the African continent. Sequence analysis of 6 isolates showed that 3 belonged to genotype F, while the 3 others were HBV genotype A. HBV genotype A was more common in the Afro-Venezuelan groups than in the general Venezuelan population. This might reflect the introduction of genotype A during the slavery period. The absence of the African genotype E among these isolates supports the hypothesis of a recent origin for this HBV genotype. HBV genotype F has already been introduced to these relatively isolated communities.

Africa↗
PubMed2002

PGE1 protection against apoptosis induced by D-galactosamine is not related to the modulation of intracellular free radical production in primary culture of rat hepatocytes.

D-galactosamine (D-GalN) toxicity is a useful experimental model of liver failure in human. It has been previously observed that PGE1 treatment reduced necrosis and apoptosis induced by D-GalN in rats. Primary cultured rat hepatocytes were used to evaluate if intracellular oxidative stress was involved during the induction of apoptosis and necrosis by D-GalN (0-40mM). Also, the present study investigated if PGE1 (1 microM) was equally potent reducing both types of cell death. The presence of hypodiploid cells, DNA fragmentation and caspase-3 activation were used as a marker of hepatocyte apoptosis. Necrosis was measured by lactate dehydrogenase (LDH) release. Oxidative stress was evaluated by the intracellular production of hydrogen peroxide (H2O2), the disturbances on the mitochondrial transmembrane potential (MTP), thiobarbituric-reacting substances (TBARS) release and the GSH/GSSG ratio. Data showed that intermediate range of D-GalN concentrations (2.5-10mM) induced apoptosis in association with a moderate oxidative stress. High D-GalN concentration (40 mM) induced a reduction of all parameters associated with apoptosis and enhanced all those related to necrosis and intracellular oxidative stress, including a reduction of GSH/GSSG ratio and MTP in comparison with D-GalN (2.5-10 mM)-treated cells. Although PGE1 reduced apoptosis induced by D-GalN, it was not able to reduce the oxidative stress and cell necrosis induced by the hepatotoxin in spite to its ability to abolish the GSH depletion.

Alprostadil↗
PubMed2001

Hepatitis delta virus genotypes I and III circulate associated with hepatitis B virus genotype F In Venezuela.

The genotypes of hepatitis B (HBV) and delta (HDV) viruses circulating among Venezuelan Amerindian populations, where these viruses are endemic, were determined by sequencing of PCR amplified products from HBsAg positive sera. HDV genotype I (n = 7, 6 from West Amerindians), and III (n = 5, 4 from South Amerindians), were found. Only one HDV genotype I isolate was associated with HBV genotype D, 4 HDV genotype I and 2 HDV genotype III infected individuals were co-infected with HBV genotype F. The failure to detect the South American HDV genotype III in West Amerindians might be related to the outbreak of fulminant hepatitis with high mortality rate occurred between 1979 and 1982, probably affecting more the Amerindians infected with HDV genotype III. These results suggest the circulation of HDV genotype I among Amerindians, probably introduced through European immigrations, and that this HDV genotype is able to replicate in association with HBV genotype F.

Amino Acid Sequence↗
PubMed2001

Lymphoepithelioma-like carcinoma of the urinary bladder: a clinicopathologic study of 13 cases.

Lymphoepithelioma-like carcinoma (LELCA) of the urinary bladder is a rare variant of bladder cancer characterized by a malignant epithelial component densely infiltrated by lymphoid cells. It is characterized by indistinct cytoplasmic borders and a syncytial growth pattern. These neoplasms deserve recognition and attention, chiefly because they may be responsive to chemotherapy. We report on the clinicopathologic features of 13 cases of LELCA recorded since 1981. The chief complaint in all 13 patients was hematuria. Their ages ranged from 58 years to 82 years. All tumors were muscle invasive. A significant lymphocytic reaction was present in all of these tumors. There were three pure LELCA and six predominant LELCA with a concurrent transitional cell carcinoma (TCC). The remainder four cases had a focal LELCA component admixed with TCC. Immunohistochemistry showed LELCA to be reactive against epithelial membrane antigen and several cytokeratins (CKs; AE1/AE3, AE1, AE3, CK7, and CK8). CK20 and CD44v6 stained focally. The lymphocytic component was composed of a mixture of T and B cells intermingled with some dendritic cells and histiocytes. Latent membrane protein 1 (LMP1) immunostaining and in situ hybridization for Epstein-Barr virus were negative in all 13 cases. DNA ploidy of these tumors gave DNA histograms with diploid peaks (n=7) or non-diploid peaks (aneuploid or tetraploid; n=6). All patients with pure and 66% with predominant LELCA were alive, while all patients having focal LELCA died of disease. Our data suggest that pure and predominant LELCA of the bladder appear to be morphologically and clinically different from other bladder (undifferentiated and poorly differentiated conventional TCC) carcinomas and should be recognized as separate clinicopathological variants of TCC with heavy lymphocytic reaction relevant in patient management.

Aged↗
PubMed2000

Specific c-K-ras gene mutations as a tumor-response marker in locally advanced rectal cancer treated with preoperative chemoradiotherapy.

BACKGROUND: Forty percent of patients with colorectal cancer develop mutations in the K-ras gene. OBJECTIVE: Our objective was to evaluate whether the presence of c-K-ras gene mutations is a useful tumor-response marker in patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy. MATERIAL AND METHODS: Thirty seven patients with locally advanced rectal cancer were treated with preoperative chemoradiotherapy. Four to six weeks later, surgery was performed. Specimens were classified according to the UICC-AJC classification. A segment of the tumor was obtained to analyze specific c-K-ras gene mutations. Restriction fragment length polymorphism (RFLP) and single strand confirmation polymorphism (SSCP) techniques were used with a set of probes to detect specific c-K-ras mutations in codons 12, 13, and 61. The 37 patients were divided into Group A (with mutations) and Group B (without mutations). RESULTS: All 37 patients completed the scheduled treatment. Group A consisted of 12 patients, whose tumors were classified and specific c-K-ras mutations were located as follows: eight in codon 12, two in codon 13, and one in codon 61. Group B consisted of 25 patients. The tumors were classified and there were more early-stage tumors in Group A, whereas in Group B there were more advanced-stage tumors (P = .05, respectively). The mean follow-up was 36.2+/-18.3 months. All Group A patients survived, whereas 8 of the 25 patients in Group B died due to progressive metastatic disease. Survival in Group A was 100%, whereas in Group B it was 59% (P = .03). CONCLUSIONS: The presence of specific c-K-ras mutations is an indicator of tumor response in patients with locally advanced rectal cancer treated with preoperative chemoradiotherapy and surgery. Therefore, responding patients may be more amenable to less radical surgical procedures based on c-K-ras mutations.

Adenocarcinoma↗
PubMed2000

Effects of aqueous extract of Casearia sylvestris (Flacourtiaceae) on actions of snake and bee venoms and on activity of phospholipases A2.

The crude aqueous extract from the leaves of Casearia sylvestris, a plant found in Brazilian open pastures, was assayed for its ability to inhibit phospholipase A2 (PLA2) activity and some biological activities of bee and several snake venoms, and of a number of isolated PLA2s. The extract induced partial inhibition of the PLA2 activity of venoms containing class I, II and III PLA2s. When tested against the purified toxins, it showed the highest efficacy against class II PLA2s from viperid venoms, being relatively ineffective against the class I PLA2 pseudexin. In addition, C. sylvestris extract significantly inhibited the myotoxic activity of four Bothrops crude venoms and nine purified myotoxic PLA2s, including Lys-49 and Asp-49 variants. The extract was able to inhibit the anticoagulant activity of several isolated PLA2s, with the exception of pseudexin. Moreover, it partially reduced the edema-inducing activity of B. moojeni and B. jararacussu venoms, as well as of myotoxins MjTX-II and BthTX-I. The extract also prolonged the survival time of mice injected with lethal doses of several snake venoms and neutralized the lethal effect induced by several purified PLA2 myotoxins. It is concluded that C. sylvestris constitutes a rich source of PLA2 inhibitors.

Animals↗
PubMed2000

TNF-alpha dependent production of inducible nitric oxide is involved in PGE(1) protection against acute liver injury.

BACKGROUND: Tumour necrosis factor alpha (TNF-alpha) and nitric oxide modulate damage in several experimental models of liver injury. We have previously shown that protection against D-galactosamine (D-GalN) induced liver injury by prostaglandin E(1) (PGE(1)) was accompanied by an increase in TNF-alpha and nitrite/nitrate in serum. AIMS: The aim of the present study was to evaluate the role of TNF-alpha and nitric oxide during protection by PGE(1) of liver damage induced by D-GalN. METHODS: Liver injury was induced in male Wistar rats by intraperitoneal injection of 1 g/kg of D-GalN. PGE(1) was administered 30 minutes before D-GalN. Inducible nitric oxide synthase (iNOS) was inhibited by methylisothiourea (MT), and TNF-alpha concentration in serum was lowered by administration of anti-TNF-alpha antibodies. Liver injury was evaluated by alanine aminotransferase activity in serum, and histological examination and DNA fragmentation in liver. TNF-alpha and nitrite/nitrate concentrations were determined in serum. Expression of TNF-alpha and iNOS was also assessed in liver sections. RESULTS: PGE(1) decreased liver injury and increased TNF-alpha and nitrite/nitrate concentrations in serum of rats treated with D-GalN. PGE(1) protection was related to enhanced expression of TNF-alpha and iNOS in hepatocytes. Administration of anti-TNF-alpha antibodies or MT blocked the protection by PGE(1) of liver injury induced by D-GalN. CONCLUSIONS: This study suggests that prior administration of PGE(1) to D-GalN treated animals enhanced expression of TNF-alpha and iNOS in hepatocytes, and that this was causally related to protection by PGE(1) against D-GalN induced liver injury.

Alanine Transaminase↗
PubMed1999

INAA of trace elements in colorectal cancer patients.

The concentration of trace elements in samples of both colorectal cancer tumors and normal tissues of a Mexican population were irradiated for 30 s and 4 h and their elemental content were measured by instrumental neutron activation analysis. Ca, Cu, Co, I, Mg, Se, Fe, Zn, Hg, Ba, and Cr were analyzed. Alterations in Co, Fe, I, and Ba were found in tumors with respect to normal tissues.

Adult↗
PubMed1992

Attitudes and knowledge toward bicycle helmet by school age children.

Approximately 600 children under the age of 15 years, die each year in bicycle-related accidents. Over 80% of these deaths involve trauma to the head. Almost one fourth of all significant brain injuries in children are bicycle related. In spite of these significant statistics, bicycle helmet use in Puerto Rico has not received the necessary publicity to increase their use. Pediatricians should encourage helmet use and counsel parents about the important of this device. A case control study of accidents among bicycle riders experiencing a crash demonstrates that safety helmets reduce the risk of head injury by 85% and brain injury by 88%. The recommendation of current safety counseling practices should be incorporated as part of the routine pediatrician visit. Educational campaigns targeted at parents and children focusing on the incidence of consequences of bicycle crashes should be the primary goal for all primary practitioners, since the effectiveness of helmets in preventing head injuries might substantially increase helmet ownership among children. To assess the prevalence of bicycle helmet ownership and the associated factors with this, we surveyed 146 school age children evaluated at the Pediatrics Clinics of the University Hospital Dr. Ramón Ruiz Arnau from January to March 1991. We concluded that only 7.5% of our sample use the helmets.

Accidents, Traffic↗
PubMed1990

Bakers' asthma: prevalence and evaluation of immunotherapy with a wheat flour extract.

One hundred thirty-nine bakers and pastry cooks were included in a prevalence study of IgE-mediated hypersensitivity to wheat flour demonstrated by skin tests, specific IgE to wheat flour (RAST), and inhalation challenge. From the sensitized workers, we selected 30 asthmatic patients. Twenty patients were treated with a standardized wheat flour extract, and ten with a placebo in a double-blind clinical trial. Before and after immunotherapy we performed tests in vivo (skin tests with wheat flour and methacholine tests), and in vitro (total IgE and specific IgE to wheat flour). We found substantial prevalence of wheat flour allergy (25.17% of workers), and a significant decrease (P less than .001) in hyperresponsiveness to methacholine, skin sensitivity (P = .002), and specific IgE (P less than .005) to wheat flour after 20 months of immunotherapy. There was also significant subjective improvement (P less than .001). The placebo group showed no changes in these variables.

Adolescent↗
PubMed1989

Role of glutamine as a direct co-repressor of glutamine synthetase in Rhodobacter capsulatus E1F1.

High performance liquid chromatography (HPLC) has been used to determine the internal levels of amino acids in Rhodobacter capsulatus E1F1 cells, subjected to different treatments and nutritional conditions. Glutamine synthetase activity and enzyme concentration correlated negatively with the level of glutamine, suggesting that glutamine per se acts as a co-repressor in the enzyme synthesis. Moreover, addition of the specific inhibitor L-methionine-D,L-sulfoximine, that produced an increase in enzyme concentration, specifically promoted a depletion of intracellular glutamine.

Enzyme Repression↗
PubMed1988

In vitro translation of tomato bushy stunt virus RNA.

In vitro translation of tomato bushy stunt (TBSV)-RNA in a rabbit reticulocyte system resulted in synthesis of five proteins P 18, P 25, P 34, P 35, and P 40. The P 40 protein was identified as the viral coat protein. Fractionation of TBSV-RNA and subsequent translation provided evidence for the existence of discrete subgenomic RNAs.

Capsid↗