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Biomedical subjects

J Mata

Publications and source records attributed to J Mata.

At least 19 recordsLinked to original sources
PubMed2001

[Importance of impedance audiometry on infant hearing screening test with otoacoustic emissions].

The target of this paper is to evaluate the importance of Impedanciometry in a protocol with transient evoked otoacoustic emissions on high risk infant hearing screening. We used tympanometry and stapedious reflex only when otoacoustic emissions became altered. This method try to decrease the impact in this test caused for middle ear diseases. We realized an Impedanciometry study in all children with abnormal otoacoustic responses and then, we obtained normal otoacoustic responses when tympanometry normalize. In the other hand, the time of test wasn't too large, between 15-20 minutes for child. The analysis of specificity and positive predictive value, of otoacoustic emissions without Impedanciometry was 89% and 45% respectively, however the same values with Impedanciometry was 96% and 75% respectively. In our opinion, high frequency of middle ear diseases in children, and our results, justify the introduction of Impedanciometry in a complete protocol of hearing screening with Otoacoustic Emissions, preventing appearance of false positive caused by these diseases.

Acoustic Impedance Tests↗
PubMed2000

Tea2p is a kinesin-like protein required to generate polarized growth in fission yeast.

Cytoplasmic microtubules are critical for establishing and maintaining cell shape and polarity. Our investigations of kinesin-like proteins (klps) and morphological mutants in the fission yeast Schizosaccharomyces pombe have identified a kinesin-like gene, tea2(+), that is required for cells to generate proper polarized growth. Cells deleted for this gene are often bent during exponential growth and initiate growth from improper sites as they exit stationary phase. They have a reduced cytoplasmic microtubule network and display severe morphological defects in genetic backgrounds that produce long cells. The tip-specific marker, Tea1p, is mislocalized in both tea2-1 and tea2Delta cells, indicating that Tea2p function is necessary for proper localization of Tea1p. Tea2p is localized to the tips of the cell and in a punctate pattern within the cell, often coincident with the ends of cytoplasmic microtubules. These results suggest that this kinesin promotes microtubule growth, possibly through interactions with the microtubule end, and that it is important for establishing and maintaining polarized growth along the long axis of the cell.

Amino Acid Sequence↗
PubMed2000

Tribbles coordinates mitosis and morphogenesis in Drosophila by regulating string/CDC25 proteolysis.

Morphogenesis and cell differentiation in multicellular organisms often require accurate control of cell divisions. We show that a novel cell cycle regulator, tribbles, is critical for this control during Drosophila development. During oogenesis, the level of tribbles affects the number of germ cell divisions as well as oocyte determination. The mesoderm anlage enters mitosis prematurely in tribbles mutant embryos, leading to gastrulation defects. We show that Tribbles acts by specifically inducing degradation of the CDC25 mitotic activators String and Twine via the proteosome pathway. By regulating CDC25, Tribbles serves to coordinate entry into mitosis with morphogenesis and cell fate determination.

Animals↗
PubMed1998

Differential expression and regulation of nucleoside transport systems in rat liver parenchymal and hepatoma cells.

Primary cultures of rat-liver parenchymal cells show carrier-mediated nucleoside uptake by a mechanism that mainly involves concentrative, Na+-dependent transport activity. In contrast, the hepatoma cell line FAO shows high nucleoside transport activity, although it is mostly accounted for by Na+-independent transport processes. This is associated with a low amount of sodium purine nucleoside transporter (SPNT) mRNA. SPNT encodes a purine-preferring transporter expressed in liver parenchymal cells. To analyze whether SPNT expression is modulated during cell proliferation, SPNT mRNA levels were determined in the early phase of liver growth after partial hepatectomy and in synchronized FAO cells that had been induced to proliferate. SPNT mRNA amounts increased as early as 2 hours after partial hepatectomy. FAO cells induced to proliferate after serum refeeding show an increase in SPNT mRNA levels, which is followed by an increase in Na+-dependent nucleoside uptake and occurs before the peak of 3H-thymidine incorporation into DNA. FAO cells also express significant equilibrative nucleoside transport activity, which may be accounted for by the expression of the nitrobenzylthioinosine (NBTI)-sensitive and -insensitive isoforms, rat equilibrative nucleoside transporter 1 (rENT1) and rENT2, respectively. Interestingly, rENT2 mRNA levels follow a similar pattern to that described for SPNT when FAO cells are induced to proliferate, whereas rENT1 appears to be constitutively expressed. Liver parenchymal cells show low and negligible mRNA levels for rENT1 and rENT2 transporters, respectively, although most of the equilibrative transport activity found in hepatocytes is NBTI-resistant. It is concluded that: 1) SPNT expression is regulated both in vivo and in vitro in a way that appears to be dependent on cell cycle progression; 2) SPNT expression may be a feature of differentiated hepatocytes; and 3) equilibrative transporters are differentially regulated, rENT2 expression being cell cycle-dependent. This is consistent with its putative role as a growth factor-induced delayed early response gene.

Animals↗
PubMed1998

Discovering the poles in yeast.

How cells generate and orientate polarized growth is of fundamental importance to understanding cell morphogenesis. The budding yeast Saccharomyces cerevisiae and the distantly related fission yeast Schizosaccharomyces pombe have both been used for genetic analysis of cell morphogenesis. Generation and maintenance of their cell shape require the formation of polarized growth sites and the correct localization of these growth sites on the cell surface with respect to other cellular structures. In this review, the authors discuss and compare the mechanisms used by the two yeasts to achieve polarized growth.

Cell Polarity↗
PubMed1997

tea1 and the microtubular cytoskeleton are important for generating global spatial order within the fission yeast cell.

Fission yeast cells identify and maintain growing regions exactly opposed at the ends of a cylindrical cell. tea1 mutants disrupt this organization, producing bent and T-shaped cells. We have cloned tea1 and shown that tea1 is located at the cell poles. Microtubules are continuously required to transfer tea1 to the cell ends, and tea1 is located at the ends of microtubules growing toward the cell poles. We suggest that tea1 acts as an end marker, directing the growth machinery to the cell poles. tea1 is down-regulated in cells treated with pheromone that grow toward a mating partner and no longer maintain their ends exactly opposed. tea1 may also influence microtubular organization, affecting the maintenance of a single central axis.

Antibody Specificity↗
PubMed1997

Prostate-specific antigen (PSA) and PSA density: racial differences in men without prostate cancer.

BACKGROUND: Many physicians now use serum prostate-specific antigen (PSA) to screen for prostate cancer in asymptomatic men. Whether or not a prostate biopsy should also be performed depends on an accurate definition of what constitutes a normal PSA value. Until recently, studies conducted to establish normal serum PSA values have involved study populations that have included few African-American men. PURPOSE: We sought to compare serum PSA levels and PSA density (i.e., serum PSA level/prostate volume ratio) in African-American and white men without histologic evidence of prostate cancer. METHODS: We reviewed the medical records of 826 consecutive men who underwent one or more prostate biopsies at the Veterans Affairs Medical Center in Shreveport, LA, from January 1993 through December 1995. In this retrospective review, we recorded patient's age, race, serum PSA level, digital rectal examination result, ultrasound-determined prostate volume, indications for biopsy, and biopsy results. Data from a total of 752 consecutive men who were either white or African-American and whose indication for biopsy included a serum PSA of greater than 4.0 ng/mL and/or an abnormal digital rectal examination were analyzed. To examine possible differences in serum PSA level, PSA density, prostate volume, and patient age, the two-sided Student's t test was employed. Multivariate linear regression analysis was used to determine if serum PSA levels were associated with the patient's age, race, or prostate volume in men without prostate cancer. RESULTS: Of the 752 men included in this analysis, 254 had histologic evidence of prostate cancer and 498 did not. Of the 498 men without prostate cancer, 367 (74%) men were white and 131 (26%) were black. There were no racial differences in age or calculated prostate volume. Serum PSA levels and calculated PSA density, however, were significantly (both P < .0001) higher in African-American men that in white men. A multivariate linear regression analysis indicated that race and prostate volume were independent variables associated with serum PSA level. For African-American and white men, serum PSA values of greater than 4 ng/mL were associated with prostate cancer with sensitivities of 89.5% and 81.9%, respectively, and specificities of 38.2% and 52.3%, respectively. CONCLUSION: Among biopsied men without histologic evidence of prostate cancer, African-Americans have a significantly higher PSA level and PSA density than similarly aged white men. IMPLICATIONS: Published criteria for normal PSA level and density have been derived primarily from white men and may not be directly applicable to other populations. Race-specific data are needed to fully optimize PSA as a tumor marker in racial populations that are at high risk for prostate cancer death.

Adult↗
PubMed1995

Macromolecular ionophores. 1. Chiral recognition properties of poly[(1-->6)-2,5-anhydro-D-glucitol] toward racemic amino acid ester.

The chiral recognition property of poly[(1-->6)-2,5-anhydro-3,4-di-O-alkyl-D-glucitol] (1) toward racemic RCH (CO2CH3)NH3+.PF6- (2.HPF6) has been studied using a transport system involving an aqueous source and receiving phases separated by a chloroform phase containing 1. Transport rates for aromatic guests 2a (R = Ph) and 2b (R = CH2Ph) were faster than those for aliphatic guests, 2c (R = CH(CH3)2) and 2d (R = CH2CH(CH3)2), using the polymer substituted with methyl groups (1a). The enantiomeric excess (e.e.) was 10.9% for 2a as a maximum value and decreased in the order of 2a > 2c > 2b = 2d. When the transport of 2a.HPF6 was carried out using the polymers with 3,4-di-O-methyl (1a), ethyl (1b), allyl (1c), and pentyl (1d) groups, the e.e. was 22.0% for 1d as a maximum value and increased in the order of 1a < 1b < 1c < 1d. The formation of a complex between 1a and 2a.HPF6 was confirmed by 1H and 13C NMR spectral measurements.

Amino Acids↗
PubMed1995

Prenatal and presymptomatic diagnosis of the Marfan syndrome using fluorescence PCR and an automated sequencer.

The Marfan syndrome (MFS) is a heritable connective tissue disorder characterized by skeletal, ocular, and cardiovascular abnormalities. Defects in fibrillin, an elastin-associated microfibrillar protein, are now known to cause MFS. Since the discovery of fibrillin as the gene responsible for MFS, requests for prenatal and presymptomatic diagnosis have become common-place. Here we report the use of the polymerase chain reaction (PCR), using fluorescence labelled primers and an automated sequencer, to establish linkage data for 'molecular diagnosis'. The mistaken clinical diagnosis of MFS based on the appearance of a common cardiovascular manifestation, mitral valve prolapse, and a positive family history is also discussed.

Autoanalysis↗
PubMed1995

Fission yeast cell morphogenesis: identification of new genes and analysis of their role during the cell cycle.

To identify new genes involved in the control of cell morphogenesis in the fission yeast Schizosaccharomyces pombe we have visually screened for temperature-sensitive mutants that show defects in cell morphology. We have isolated and characterized 64 mutants defining 19 independent genes, 10 of which have not been previously described. One class of mutants, defining 12 orb genes, become round and show a complete loss of cell polarity. A second class of mutants exhibits branched or bent morphologies. These mutants show defects in either selection of the growth site, defining two tea genes, or in the maintenance of growth direction, defining five ban genes. Immunofluorescence analysis of these morphological mutants shows defects in the organization of the microtubule and actin cytoskeleton. These defects include shortened, bundled, and asymmetrically localized microtubules and enlarged and mislocalized actin patches. Analysis of the mutant phenotypes has allowed us to order the genes into four groups according to their function during the cell cycle: genes required for the maintenance of cell polarity throughout the cell cycle; genes necessary only for the reestablishment of cell polarity after mitosis and not for maintaining cell polarity once it is established; genes essential for the transition from monopolar to bipolar growth and genes that severe as 'polarity markers'.

Actins↗
PubMed1995

Cholesteryl-conjugated phosphorothioate oligodeoxynucleotides modulate CYP2B1 expression in vivo.

5' cholesteryl-conjugated phosphorothioate oligodeoxynucleotides with sequence complementary to the rat CYP2B1 mRNA were evaluated in adult male Sprague-Dawley rats for their pharmacokinetic properties, toxicity, and ability to modulate CYP2B1 expression in vivo. Following intraperitoneal administration of 35S-labelled oligodeoxynucleotides, volume of distribution for the phosphorothioate was 0.33 l/kg while the 5' cholesteryl-conjugate oligodeoxynucleotide was 0.12 l/kg. The elimination half-life was 23.2 and 55.4 hrs for cholesteryl-modified and unmodified oligodeoxynucleotides, respectively. Cholesteryl-conjugate oligodeoxynucleotide toxicity was detected at a dose of 1.0 mg/kg and consisted primarily of midzonal liver cell enlargement and increased total RNA. Hexobarbital sleep times, a measure of CYP2B1 enzyme activity in vivo, increased from 21.9 minutes in saline-treated animals to 29.5 minutes in cholesterol oligodeoxynucleotide-treated animals. A significant decrease in liver microsomal pentoxyresorufin O-dealkylase enzyme activity, a CYP2B1/2 specific assay, was observed but not a change in p-nitrophenol hydroxylase activity, a specific CYP2E1 assay. These data indicate that in vivo modulation of the CYP2B1 gene can be accomplished with synthetic phosphorothioate oligodeoxynucleotides in a sequence-specific manner. Further, cholesteryl conjugation to the 5' end of the oligodeoxynucleotide enhanced potency despite lesser bioavailability.

Animals↗
PubMed1995

Analysis of immunological alterations associated with testicular prostheses.

PURPOSE: Recipients of silicone gel filled testicular prostheses were evaluated for the possible immunological abnormalities of human adjuvant disease. MATERIALS AND METHODS: Medical record audits were performed for 48 recipients of a silicone gel filled testicular prosthesis. Seven patients consented to a detailed health profile questionnaire, physical examination and serological testing. RESULTS: Retrospective chart analyses and physical examinations were unremarkable. Serological results and questionnaire responses varied. One patient with signs and symptoms suggestive of human adjuvant disease underwent prosthesis removal but adjacent tissues had no evidence of silicosis. Long-term followup was poor. CONCLUSIONS: Immunological alterations were present in 71.4% of examined recipients but they may have been coincidental. Careful followup of recipients of a silicone gel filled testicular prosthesis is needed.

Adolescent↗
PubMed1995

[Nutritional value and antinutritional factor content of precooked flours prepared from Canavalia ensiformis].

Precooked flours obtained five Canavalia ensiformis varieties were prepared by dehydration in double drums. On a dry matter basis, significant differences (P < 0.05) among varieties were detected for crude protein content (25 to 30%), starch (36 to 40%) and dietary fiber (13 to 15%). Hemagglutinins were eliminated as result of the high temperature (146 degrees C/4 min) employed during the drying process. Similar results were not obtained for trypsin inhibitors and canavanine considering that small amounts of these compounds remained in the precooked flours prepared from canavalia seeds. A 10% decrease in available lysine was observed. Biological assays yielded Protein Efficiency Ratio (PER) values of 0, 8-1 and Neat Proteic Relation (NPR) values of 2-3-2.6. True digestibility of protein values were improved from 87 to 90%. All cultivars had similar starch digestive utilization coefficient (96%) and starch fraction (4%) resistant to enzymatic hydrolysis in the rat digestive tract.

Animals↗
PubMed1994

Pharmacokinetics of an antisense phosphorothioate oligodeoxynucleotide against rev from human immunodeficiency virus type 1 in the adult male rat following single injections and continuous infusion.

An antisense phosphorothioate oligodeoxynucleotide 27-mer complementary to the rev gene mRNA of the human immunodeficiency virus (HIV-1) was administered to rats through intravenous injections and subcutaneous infusions in order to investigate the disposition of this compound. In addition, nonlethal toxic responses of the rat were evaluated. A biphasic plasma clearance with t1/2 alpha of 20-25 min and t1/2 beta of 27-41 hr was observed. Single doses ranging from 35 to 3257 micrograms were examined, and the plasma concentration and area under the plasma concentration-time curve (AUC) were found to be directly proportional to the dose. Continuous subcutaneous infusion of 50 mg over 28 days was also examined. The oligonucleotide is completely eliminated in the urine over 3 days. Electrophoretic analysis demonstrated that the excreted compound has the same mobility and UV-absorbance profile as the administered compound. Measurement of accumulation and distribution into tissues revealed unique tissue-specific rates and extent of oligonucleotide movement into and out of tissues. Results of the chronic infusion study suggest that uptake into tissue is not saturated, even after 28 days of infusion. Analysis of blood plasma from oligonucleotide-treated animals shows a possible transient elevation in levels of lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), but not alkaline phosphatase (AP), gamma-glutamyltransferase (GT), and bilirubin. The data collectively support the potential utility of phosphorothioate oligonucleotides as therapeutic agents in vivo.

Alanine Transaminase↗