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J Seoane

Publications and source records attributed to J Seoane.

At least 19 recordsLinked to original sources
PubMed2000

OAZ uses distinct DNA- and protein-binding zinc fingers in separate BMP-Smad and Olf signaling pathways.

We have identified the 30-zinc finger protein OAZ as a DNA-binding factor that associates with Smads in response to BMP2, forming a complex that transcriptionally activates the homeobox regulator of Xenopus mesoderm and neural development, Xvent-2. OAZ contains a BMP signaling module formed by two clusters of fingers that bind Smads and the Xvent-2 BMP response element, respectively. Previously implicated as a transcriptional partner of Olf-1/EBF in olfactory epithelium and lymphocyte development in the rat, OAZ fulfills this role through clusters of fingers that are separate from the BMP signaling module. The mutually exclusive use of OAZ by the BMP-Smad and Olf pathways illustrates the dual role of a multi-zinc finger protein in signal transduction during development.

Amino Acid Sequence↗
PubMed1999

Glucokinase overexpression restores glucose utilization and storage in cultured hepatocytes from male Zucker diabetic fatty rats.

Zucker diabetic fatty rats develop type 2 diabetes concomitantly with peripheral insulin resistance. Hepatocytes from these rats and their control lean counterparts have been cultured, and a number of key parameters of glucose metabolism have been determined. Glucokinase activity was 4.5-fold lower in hepatocytes from diabetic rats than in hepatocytes from healthy ones. In contrast, hexokinase activity was about 2-fold higher in hepatocytes from diabetic animals than in healthy ones. Glucose-6-phosphatase activity was not significantly different. Despite the altered ratios of glucokinase to hexokinase activity, intracellular glucose 6-phosphate concentrations were similar in the two types of cells when they where incubated with 1-25 mM glucose. However, glycogen levels and glycogen synthase activity ratio were lower in hepatocytes from diabetic animals. Total pyruvate kinase activity and its activity ratio as well as fructose 2,6-bisphosphate concentration and lactate production were also lower in cells from diabetic animals. All of these data indicate that glucose metabolism is clearly impaired in hepatocytes from Zucker diabetic fatty rats. Glucokinase overexpression using adenovirus restored glucose metabolism in diabetic hepatocytes. In glucokinase-overexpressing cells, glucose 6-phosphate levels increased. Moreover, glycogen deposition was greatly enhanced due to the activation of glycogen synthase. Pyruvate kinase was also activated, and fructose-2,6-bisphosphate concentration and lactate production were increased in glucokinase-overexpressing diabetic hepatocytes. Overexpression of hexokinase I did not increase glycogen deposition. In conclusion, hepatocytes from Zucker diabetic fatty rats showed depressed glycogen and glycolytic metabolism, but glucokinase overexpression improved their glucose utilization and storage.

Animals↗
PubMed1999

Flow cytometric DNA ploidy analysis of oral cancer comparison with histologic grading.

It has been reported that DNA content analysis provides prognostic information eliminating the subjective component involved in routine microscopic decision making. In an attempt to establish a relationship between pathological findings and flow cytometric analysis, 36 formalin-fixed, paraffin-embedded tumour tissue samples were prepared according to Hedley's method and analysed by means of an Epics Profile II flow cytometer. DNA aneuploidy was observed in 15 tumours (41%). A statistically significant correlation was identified between DNA index and mitoses, cellular response and degree of differentiation, but not the ploidy status. It was not possible to identify a significant association of sex, age, and site of the tumour to DNA index. We found a strong correlation between histologic malignancy and DNA index; an increase in DNA index as malignancy score increases was noted. It was concluded that DNA index shows a good correlation with the histologic features of oral cancer, being a complement of differentiation and histologic grading analysis. The use of DNA analysis as a complement to pathological studies would help to diminish the subjective component of assessment of head and neck cancers. Ploidy status was not statistically associated with the differentiation of tumours.

Adult↗
PubMed1999

Ultrastructural and immunocytochemical evidences of core-particle formation in the methylotrophic Pichia pastoris yeast when expressing HCV structural proteins (core-E1).

Particulate antigens of the Hepatitis C virus (HCV) are reported for the first time by transmission electron microscopy in Pichia pastoris. The yeast was cloned to express the first 339 NH2-terminal amino acids of the HCV polyprotein (C-E1.339 polypeptide). The C-E1.339 polypeptide covers the putative 191 aa of the core protein (aa 1-191) and 148 aa of the E1 envelope antigen (aa 192-339). Virus-like particles (VLP) with diameters ranging from 20 nm to 30 nm were specifically observed in those cells expressing the HCV polyprotein. The VLP appeared along the membrane of the endoplasmic reticulum, but were fundamentally localized in vacuoles, either free or inside autophagic bodies. Clustered particles, chains of particles, high-density reticular structures, and crystalloid bodies were also detected, the last one being an orderly arrangement of particles with 20 nm diameters. The crystal-associated particles are well differentiated from the intracellular VLP because of their uniform size and shape. We argue that membrane components are retained in the architecture of the VLP, conferring to this particle certain heterogeneity. Both kinds of particles, the VLP formed after treatment with NP-40 and the crystal-associated particles, were core protein-positives. Whether they reflect mature HCV nucleocapsid or intermediary states in the viral nucleocapsid morphogenesis remains unknown. We conclude that, like mammalian cell lines, the P. pastoris yeast could be an appropriate host for the analysis of HCV polyprotein processing and, eventually, virus assembly.

Gene Expression↗
PubMed1999

Myc downregulation by transforming growth factor beta required for activation of the p15(Ink4b) G(1) arrest pathway.

The antimitogenic action of transforming growth factor beta (TGF-beta) in epithelial cells involves cyclin-dependent kinase (cdk) inhibitory gene responses and downregulation of c-Myc expression. Although the cdk inhibitory responses are sufficient for G(1) arrest, enforced expression of c-Myc prevents G(1) arrest by TGF-beta. We investigated the basis of this antagonism by using Mv1Lu lung epithelial cell lines that conditionally express levels of human c-Myc. We show that c-Myc prevents induction of the cdk4 inhibitor p15(Ink4b) and the subsequent inhibition of G(1) cdks by TGF-beta. We assessed the significance of this effect by analyzing the oligomeric state of cdk4 in these cells. In proliferating cells, endogenous cdk4 is distributed among three populations: an abundant high-molecular-mass (>400-kDa) pool of latent cdk4 that serves as a source of cdk4 for cyclin D, a low-abundance pool containing active cyclin D-cdk4 complexes, and an inactive population of monomeric cdk4. Cell stimulation with TGF-beta converts the latent and active cdk4 pools into inactive cdk4, an effect that is specifically mimicked by overexpression of p15 but not by other forms of G(1) arrest. This process of TGF-beta-induced cdk4 inactivation is completely blocked by expression of c-Myc, even though the latent and active cdk4 complexes from c-Myc-expressing cells remain sensitive to dissociation by p15 in vitro. c-Myc causes a small increase in cyclin D levels, but this effect contributes little to the loss of TGF-beta responses in these cells. The evidence suggests that c-Myc interferes with TGF-beta activation of the p15 G(1) arrest pathway. TGF-beta must therefore downregulate c-Myc in order to activate this pathway.

Amino Acid Sequence↗
PubMed1998

Flow cytometric analysis of nuclear DNA content in oral leukoplakia.

DNA ploidy has been studied in 31 paraffin-embedded specimens of oral leukoplakia and in 10 specimens of oral leukoplakia that have undergone malignant transformation after a 5-year observation period. Three out of 31 specimens (9.7%) showed an aneuploid DNA pattern, with DNA indices of 1.17, 1.28 and 1.32. It was not possible to establish a statistically significant difference of DNA ploidy related to the presence or absence of dysplasia. One out of the 10 oral leukoplakias that underwent malignant transformations had a multiploid pattern with DNA indices of 1.44 and 2.37. In this study the DNA index has not proved to be of value in the identification of dysplastic leukoplakia among the non-dysplastic ones.

Aneuploidy↗
PubMed1998

[Prospective 3-month study of intravascular catheter complications in HIV-infected patients: relation between phlebitis and infection].

BACKGROUND: The aim of this study was to evaluate the etiology of phlebitis (chemical or infectious) and the prevalence of infections related to intravascular catheters (IRIC) in patients with HIV infection admitted to a 22-bed Infectious Disease Unit with a high rate of HIV infection. MATERIAL AND METHODS: A 3-month prospective study from November 1, 1994 to January 31, 1995 was carried out following a formula for data collection of all the intravenous catheters used during that time period. Cultures of the catheters withdrawn on Wednesdays and those with signs of phlebitis were performed. RESULTS: One hundred fifty-two intravenous catheters in 71 patients with HIV infection with a mean age of 37 years (range: 21-73) and mean hospital stay of 10.2 days were reported. During the study period 42 phlebitis were produced, of which 37 catheters (7 central and 30 peripheral) were processed. Of the 37 phlebitis processed, 29 (78.9%) were considered to be of physiochemical origin. Of the 21 catheters withdrawn Wednesday, 18 were processed, 8 with phlogotic signs, 2 with IRCI, equivalent to 1.9 IRCI/100 days of catheterization. During the study period no local or severe systemic infections related to the catheter were reported. Staphylococcus epidermidis was the organism involved in all the cases of IRCI. CONCLUSIONS: Despite the high number of immunosuppressed patients in related to HIV infection, a greater incidence of IRCI was not found in these patients. The most frequent cause of phlebitis by catheter was of chemical origin.

Adult↗
PubMed1997

Metabolic impact of adenovirus-mediated overexpression of the glucose-6-phosphatase catalytic subunit in hepatocytes.

Glucose-6-phosphatase (G6Pase) catalyzes the hydrolysis of glucose 6-phosphate (Glu-6-P) to free glucose and, as the last step in gluconeogenesis and glycogenolysis in liver, is thought to play an important role in glucose homeostasis. G6Pase activity appears to be conferred by a set of proteins localized to the endoplasmic reticulum, including a glucose-6-phosphate translocase, a G6Pase phosphohydrolase or catalytic subunit, and glucose and inorganic phosphate transporters in the endoplasmic reticulum membrane. In the current study, we used a recombinant adenovirus containing the cDNA encoding the G6Pase catalytic subunit (AdCMV-G6Pase) to evaluate the metabolic impact of overexpression of the enzyme in primary hepatocytes. We found that AdCMV-G6Pase-treated liver cells contain significantly less glycogen and Glu-6-P, but unchanged UDP-glucose levels, relative to control cells. Further, the glycogen synthase activity state was closely correlated with Glu-6-P levels over a wide range of glucose concentrations in both G6Pase-overexpressing and control cells. The reduction in glycogen synthesis in AdCMV-G6Pase-treated hepatocytes is therefore not a function of decreased substrate availability but rather occurs because of the regulatory effects of Glu-6-P on glycogen synthase activity. We also found that AdCMV-G6Pase-treated-cells had significantly lower rates of lactate production and [3-3H]glucose usage, coupled with enhanced rates of gluconeogenesis and Glu-6-P hydrolysis. We conclude that overexpression of the G6Pase catalytic subunit alone is sufficient to activate flux through the G6Pase system in liver cells. Further, hepatocytes treated with AdCMV-G6Pase exhibit a metabolic profile resembling that of liver cells from patients or animals with non-insulin-dependent diabetes mellitus, suggesting that dysregulation of the catalytic subunit of G6Pase could contribute to the etiology of the disease.

Adenoviridae↗
PubMed1997

[Photochemotherapy in the treatment of oral erosive lichen planus. Letter].

Photochemotherapy with 8-methoxypsoralenes and PUVA has been found to be effective in the treatment of superficial skin inflammations, such as lichen planus. However, there is little bibliography on the treatment of oral lichen planus with PUVA. A case of oral erosive lichen planus was treated with oral psoralenes (0.6 mg/kg body weight) two hours before ultraviolet exposure. Twenty sessions were held, three weekly, for a total cumulative dose of 35.9 J/cm2. After treatment concluded, clinical symptoms and erosive lesions disappeared. PUVA therapy may be useful for severe forms of erosive oral lichen planus that do not respond to conventional treatment.

Drug Therapy↗
PubMed1997

Assessment of dental students' ability to recognise precancerous lesions and conditions.

The role of dentists in both primary (promoting a healthier lifestyle) and secondary (early diagnosis) prevention of oral cancer is undeniable, and becomes particularly important as oral cancer is thought to be preceded by premalignant lesions or conditions in about one half of the cases. In these situations, there is the possibility for an early diagnosis which will definitively influence the survival rate. Thus, it is an undergraduate educational objective related to secondary prevention of oral cancer to increase the efficacy of screening of precancerous lesions/conditions. A questionnaire with 38 clinical cases including 16 benign lesions, 9 malignant lesions and 13 precancerous lesions or conditions was applied voluntarily to 3rd, 4th and 5th year University of Santiago de Compostela dental students on April 1996. The participation rate was 90% of the 3rd-year students, 60% in 4th-year class, and 50% of the 5th-year group. The agreement in the diagnosis with a panel of experts reached 81.45% for 5th-year students. Students of 3rd- and 4th-year scored lower percentages, probably due to the rarity of some of the conditions in our area. 5th-year students scored significantly higher values than 3rd- and 4th-year students.

Clinical Competence↗