Biomedical subjects

A Velasco

Publications and source records attributed to A Velasco.

At least 55 records · Page 3Linked to original sources

PubMed1998

Genetic and functional analysis of the styrene catabolic cluster of Pseudomonas sp. strain Y2.

The chromosomal region of Pseudomonas sp. strain Y2 involved in the conversion of styrene to phenylacetate (upper catabolic pathway) has been cloned and sequenced. Four catabolic genes, styABCD, and two regulatory genes, stySR, were identified. This gene cluster when transferred to Escherichia coli W confers to this phenylacetate-degrading host the ability to grow on styrene as the sole carbon and energy source. Genes styABCD are homologous to those encoding the styrene upper catabolic pathway in Pseudomonas fluorescens ST. Northern blot analyses have confirmed that genes styABCD constitute a transcription unit. The transcription start site of the sty operon was mapped 33 nucleotides upstream of the styA translational start codon. The styS and styR genes, which form an independent transcriptional unit, are located upstream of the styABCD operon, and their gene products show high similarity to members of the superfamily of two-component signal transduction systems. The styS gene product is homologous to histidine kinase proteins, whereas the styR gene product exhibits similarity at its N-terminal domain with cluster 1 of receiver modules and at its C terminus with the LuxR/FixJ family 3 of DNA-binding domains. Expression of the catabolic operon decreased significantly in the absence of the stySR genes and was restored when the stySR genes were provided in trans in the presence of styrene, suggesting that the stySR system behaves as a styrene-inducible positive regulator of the styABCD operon. Finally, a gene encoding a phenylacetyl-coenzyme A ligase that catalyzes the first step in the phenylacetate catabolism (styrene lower catabolic pathway) has been identified upstream of the styS gene. This activity was found to be induced in Pseudomonas sp. strain Y2 cells grown on styrene but not present in cells grown on glycerol. These results strongly suggest that the genes responsible for the complete mineralization of styrene are clustered in the chromosome of Pseudomonas sp. strain Y2.

Amino Acid Sequence↗

PubMed1998

IgA nephropathy in psoriasis.

IgA nephropathy (IGAN) was first described by Berger and Hinglais in 1968. It is now the most common glomerular disease worldwide. IGAN has been associated with several diseases. Its association with psoriasis has been rarely described. We report a case of IGAN with crescentic changes, associated with psoriasis vulgaris. We review the literature on the association of IGAN with psoriasis and discuss the likely pathogenetic linkage.

Adult↗

PubMed1998

Nonspecific labeling of myelin with secondary antisera and high concentrations of Triton X-100.

Triton X-100 is used in immunohistochemistry to make tissue permeable, to present certain antigens to antisera, and to prevent certain nonspecific interactions. This detergent is routinely dissolved in buffers at concentrations of 0.01-0.2%. Using high concentrations of Triton X-100 (0.2-2%) and anti-immunoglobulins G (anti-IgGs), labeling of myelin and microglia was detected in fixed brain tissue by indirect fluorescence and avidin-biotin-immunoperoxidase techniques. Differences were found between the species studied (mouse and rat), the type of anti-IgG (anti-mouse, anti-rabbit, anti-sheep, anti-rat, or anti-guinea pig), the detergent concentration, and whether Triton X-100 was included in the incubation media or applied as a pretreatment. Mouse brain displayed strong myelin labeling with all anti-IgGs but rat brain only with anti-rabbit or anti-sheep IgGs. Staining of ramified microglia occurred only in mouse tissue when anti-mouse IgG was used. Nonspecific staining of myelin was also intense in paraffin-embedded tissue and in human brain frozen sections. These results are significant for the prevention of undesirable staining in routine immunolabeling and they also provide a comparatively inexpensive, easy to perform strong labeling of myelin. In addition, the double marker signal (peroxidase and fluorescence) is useful for double labeling studies. (J Histochem Cytochem 46:109-117, 1998)

Animals↗

PubMed1998

Diencephalic and mesencephalic structures related to the optic nerve organization in tench (Tinca tinca L., 1758). A study using fluoro-gold.

The location of several diencephalic and mesencephalic structures in the teleost fish, Tinca tinca, which have not been described previously, was made possible by injecting Fluoro-Gold, as an anterograde and retrograde tracer, into the optic nerve. In the pretectal area, we found the tractus opticus accessorius and the nucleus opticus dorsolateralis. We have made some specifications about the location and nomenclature of the branches belonging to the optic tracts and two nuclei also related to the visual system (the nucleus commissura posterior and the nucleus pretectalis periventricularis pars dorsalis). This study also presents the retinal projections to the optic tectum and the glial cells in the injected optic nerve of the tench. The laminar nucleus and Edinger-Westphal nucleus are also identified and described in relation to the ciliary pathway.

Animals↗

PubMed1997

Protein kinase A activity is required for the budding of constitutive transport vesicles from the trans-Golgi network.

We have examined the role played by protein kinase A (PKA) in vesicle-mediated protein transport from the trans-Golgi network (TGN) to the cell surface. In vivo this transport step was inhibited by inhibitors of PKA catalytic subunits (C-PKA) such as the compound known as H89 and a myristoylated form of the inhibitory peptide sequence contained in the thermostable PKA inhibitor. Inhibition by H89 occurred at an early stage during the transfer of vesicular stomatitis virus G glycoprotein from the TGN to the cell surface. Reversal from this inhibition correlated with a transient increase in the number of free coated vesicles in the Golgi area. Vesicle budding from the TGN was studied in vitro using vesicular stomatitis virus-infected, permeabilized cells. Addition to this assay of C-PKA stimulated vesicle release while it was suppressed by PKA inhibitory peptide, H89, and antibody against C-PKA. Furthermore, vesicle release was decreased when PKA-depleted cytosol was used and restored by addition of C-PKA. These results indicate a regulatory role for PKA activity in the production of constitutive transport vesicles from the TGN.

Animals↗

PubMed1997

Quantitative measurement of protein kinase C immunoreactivity in rod bipolar cells of the goldfish retina.

The intensity of the immunohistochemical reaction (IIR) against the alpha species of protein kinase C (PKC) was quantified in the rod bipolar cells (RBC) of the goldfish retina using of image analysis. Retinae incubated in control Ringer solution showed similar IIR in both the soma and the axon terminal (IIR-ratio approximately 1). Activation of PKC induces the 'transport' of the enzyme to the synaptic terminal of RBC and an increase in the IIR-ratio. In the present report, the effect of retinal neurotransmitters on the IIR-ratio and the time course of PKC transport was studied.

Animals↗

PubMed1997

[The prediction of the degree of metabolic control by minimal technical norms in a diabetes program].

OBJECTIVE: To assess whether scores on the minimum technical norms (MTN) of the diabetes mellitus programme are of use in determining the level of metabolic control achieved. DESIGN: A retrospective study. SETTING: Two teaching health centres in the city of Santander. PATIENTS AND OTHER PARTICIPANTS: 204 patients, the total chosen by the Santander area management for the 1994 annual evaluation of the Diabetes programme. MEASUREMENTS AND RESULTS: The values reached by the variables of the MTN were measured. For a control criterion we took the value of glycosylated haemoglobin HbA1C or over. 52% of patients fulfilled the criteria of good control, 20% acceptable and 28% bad. CONCLUSIONS: Scoring on the MTN has little value in predicting lower values of HbA1C and is no use in assessing the level of metabolic control achieved by the Diabetes programme. The evaluation of the programme should include results indicators.

Community Health Centers↗

PubMed1997

Distribution of S100 immunoreactivity in the retina and optic nerve head of the teleost Tinca tinca L.

The distribution of S100 immunoreactivity within the normal and regenerating retina and optic nerve head of the teleost Tinca tinca L. has been investigated using the avidin-biotin complex (ABC) method and a polyclonal antibody against S100. Astrocytes and Müller cells were labeled with this antibody. This represents the first description of astrocytes localized in the optic nerve head and in the nerve fiber layer of the fish retina displaying a typical bipolar morphology. Horizontal cells in the inner nuclear layer were immunolabeled; we also observed species-specific S100 labeling of horizontal cells of the H1 subtype. No significant changes were seen in the S100 immunoreactive Müller cells, astrocytes, or horizontal cells in the tench retina after optic nerve crushing and during regeneration. These results might help to understand the function of glial cells in the normal and experimentally induced regenerating fish visual system.

Animals↗

PubMed1997

Effects of fluoxetine hydrochloride and fluvoxamine maleate on different preparations of isolated guinea pig and rat organ tissues.

1. Fluoxetine and fluvoxamine reinforced the response to norepinephrine of isolated rat vas deferens incubated in Krebs-Henseleit solution. 2. This reinforcement disappeared when cocaine, 17 beta-estradiol, and propranolol were added to the incubation medium. 3. Fluoxetine and fluvoxamine did not have antimuscarinic effect, but they did have antihistaminic effect, and at high concentrations they inhibited the contraction induced by potassium ion on the isolated rat uterus preparation (IC50 3.99 x 10(-6) and 1.82 x 10(-5) M, respectively).

Acetylcholine↗

PubMed1997

S-100-positive glial cells are involved in the regeneration of the visual pathway of teleosts.

Glial cells in the normal and regenerating visual pathways of Tinca tinca (Cyprinid, Teleost) were studied by labelling with anti-S-100 antibody. In normal fish, S-100-positive bipolar cells were found in the optic nerve, optic tract, and in the diencephalic visual pathways. After crushing the left optic nerve, the distribution and the number of S-100-immunoreactive cells were modified. In the injured nerve, 7 to 15 days after crushing no immunoreactive cell bodies were found in the crushed area, but a greater number of S-100-positive cells were found on both sides of the injured area. Sixty days after crushing, positive cells penetrating the crushed area were observed; the normal pattern was almost restored 200 days after crushing. In the diencephalon, 25 days after crushing, the number of S-100-positive cells increased remarkably and the most intense immunostaining of glial processes was observed 60 days after crushing. The density of S-100-labelled cells decreased after 4 months postcrushing. However, in the optic tectum no changes were observed. The increase of glial cells in the lesioned visual pathway suggests that they could play an important role in axonal regeneration after crushing.

Animals↗

PubMed1997

Effect of 4-aminopyridine and 3,4-diaminopyridine on guinea-pig isolated ileum.

1. 4-Aminopyridine and 3,4-diaminopyridine produced concentration-dependent contraction on guinea-pig isolated ileum incubated in Tyrode solution. The EC30 values were 1.14 x 10(-4) and 1.39 x 10(-4) M, respectively. 2. Calcium channel blockers such as verapamil, diltiazem, nifedipine, flunarizine, and lanthanum chloride antagonized the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 3. Diazoxide and atropine sulphate behaved similarly as antagonists of the contracting effect induced by 4-aminopyridine and 3,4-diaminopyridine in guinea-pig isolated ileum. 4. It is concluded that the aminopyridines exert their effects through the release of acetylcholine from parasympathetic nerve terminals.

4-Aminopyridine↗

PubMed1996

A regulatory role for cAMP-dependent protein kinase in protein traffic along the exocytic route.

The influence of protein kinase A activity on transport of newly synthesized vesicular stomatitis virus G glycoprotein along the exocytic pathway was examined. Transport of vesicular stomatitis virus G glycoprotein to the cell surface was inhibited by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), a selective inhibitor of protein kinase A. This block occurred at the exit of the Golgi complex, whereas transport through the Golgi compartments or from the endoplasmic reticulum to the Golgi was decreased in the presence of H-89. As judged by immunofluorescence endoplasmic reticulum to Golgi transport was accelerated in cells incubated with activators of protein kinase A such as isobutylmethylxanthine (IBMX) or forskolin (FK). Treatment with IBMX and FK also increased transport from the trans-Golgi network to the cell surface. During incubation with IBMX and FK, the organization of the Golgi complex was altered showing intercisternae fusion and miscompartmentalization of resident proteins. These structural changes affected both the kinetics of acquisition of endoglycosidase H resistance and transport activities. These data support a differential regulatory role for protein kinase A in different transport steps along the exocytic pathway. In particular, transport from the trans-Golgi network to the cell surface was dependent on protein kinase A activity. In addition, the results suggest the involvement of this enzyme on the maintenance of the Golgi complex organization.

1-Methyl-3-isobutylxanthine↗

PubMed1996

Protein kinase C localization in the synaptic terminal of rod bipolar cells.

The purpose of the present study was to elucidate the physiological mechanisms that determine the activation of protein kinase C (PKC) in rod bipolar cells (RBC) of mouse and goldfish. The localization of PKC in RBC was examined using immunoreactivity (IR) against the alpha species of the enzyme. After incubating the whole retina or dissociated cells in control or test solutions, PKC-IR was performed on retinal transverse sections or on isolated cells. Cell depolarization induced the transport of the PKC to the synaptic terminal of RBC. The transport of the enzyme was also induced upon incubating dissociated cells in a solution containing phorbol esters. Enzyme transport was inhibited when the isolated retina was incubated in solutions containing GABA or nifedipine. We conclude that calcium and diacylglycerol, which contribute to the activation of PKC in RBC, induce transport of the enzyme to the synaptic terminal where it is presumed to play its functional role.

Animals↗

PubMed1996

Degradation of aggrecan precursors within a specialized subcompartment of the chicken chondrocyte endoplasmic reticulum.

Chicken chondrocytes in culture synthesize aggrecan proteoglycan as a 370 kDa precursor that is glycosylated and secreted into the medium with a half-life of 30 min. In metabolic studies the 370 kDa precursor was shown to render a degradation intermediate of 190 kDa, which appeared with no measurable lag phase; it was dependent on temperature ( > 20 degrees C) and inhibited by certain serine and serine/cysteine protease inhibitors such as leupeptin and PMSF. By contrast, degradation was unaffected by treatment of the cells with brefeldin A or with lysosomotropic agents. Aggrecan precursors were detected by immunofluorescence analysis within a subcompartment of the endoplasmic reticulum (ER), previously characterized as a smooth-membrane-bound subregion [Vertel, Velasco, LaFrance, Walters and Kaczman-Daniel (1989) J. Cell Biol. 109, 1827-1836]. Analysis of the subcellular fractions derived from chondrocytes indicated that the degradation intermediate was concentrated in the ER subcompartment. Degradation was dependent on the Ca2+ concentration and the redox state in the ER. Treatment of the cells with agents or conditions that alter the degradation rate of aggrecan precursors, such as protease inhibitors, decreased temperature or dithiothreitol, also modified the retention of these molecules in the ER subcompartment, as seen by immunofluorescence. These results indicate that a fraction of the 370 kDa aggrecan precursor is targeted to a smooth ER subcompartment where it undergoes degradation.

Aggrecans↗

PubMed1996

Intermediate filament aggregates in mitoses of primary cutaneous neuroendocrine (Merkel cell) carcinoma.

Primary cutaneous neuroendocrine carcinomas express different kinds of intermediate filaments and frequently in a 'paranuclear globular' pattern. We have observed the same pattern not only in interphase but also in mitotic cells, which are very frequent in these tumours. We report a quantitative and morphological study of eight primary cutaneous neuroendocrine carcinomas stained with different antibodies against cytokeratins (CAM 5.2 and anticytokeratin 20), neurofilaments (70 kDa and 200 kDa) and peripherin. We have found a predominance of CAM 5.2 expression in interphase cells and of neurofilament proteins in mitotic cells; 87.02% of the interphase cells were positive with CAM 5.2 whereas only 6.08% were positive for neurofilaments (P < 0.01); 35.41% of the mitotic cells were positive with CAM 5.2, whereas 50% were positive for neurofilaments (P < 0.01). A correlation between a globular pattern of intermediate filament proteins and prognosis has not been found. We describe for the first time the division of neoplastic cells with a globular pattern; the presence of intermediate filament proteins with a globular pattern in all mitotic stages; and the uneven distribution of this formation between the two daughter cells.

Aged↗

PubMed1996

'Scléroedème génito-sus-pubien' of the newborn: a forgotten disease?

A 2-month-old boy with an important hardening of the skin in the pubic and genital regions is presented. He was born prematurely at 31 weeks of gestation, and required a respirator during the first 72 h. The analytical explorations and abdominal ultrasound images were normal. Histological study had not shown significant changes. The patient did not receive any treatment and gradually experienced remission. Because of the location and spontaneous regression in a few months, the picture is very similar to the one described by Degos as 'Scléroedème génito-sus-pubien' of the newborn.

Diagnosis, Differential↗

PubMed1996

Impact of selective financing of drugs on pharmaceutical expenditure control in the province of Valladolid, Spain.

In July 1993, public financing for 1692 drug specialities was stopped in Spain (a drug speciality is a medicine with a defined composition, particular pharmaceutical form and dosage, prepared for immediate use, ready and packaged for dispatching to the public, with uniform name, packaging and labelling which has been granted authorisation by the State Administration and registered in the Pharmaceutical Specialities Register). We designed a study to assess the repercussions of this so-called 'selective financing' on expenditure control. The aims of the study were 2-fold: first, to forecast the consumption of drug specialities that are reimbursable on the Spanish National Health Service, had selective financing not been applied; and, secondly, to estimate the impact of selective financing on drug consumption. For short- and medium-term forecast estimates, time-series analysis was used, and was applied to monthly consumption data. The measures of consumption used were the number of prescriptions per 1000 patients, and cost [in Spanish pesetas (Pta; $US1 = Pta123.9, February 1996)] per 1000 patients. Data were analysed from January 1986 up to the introduction of selective financing. We found that drug specialities excluded by selective financing showed, overall, a negative increase (i.e. the consumption of drugs that were excluded under selective financing decreased). The repercussion forecast, both in terms of prescription numbers and cost, of the 13 excluded drug specialities that had the highest pre-selective financing consumption is decreasing compared with total consumption. The assessment of the repercussions of selective financing up to December 1994 was made by calculating the difference between actual expenditures and forecast expenditures in the absence of selective financing. This repercussion, in prescriptions, was lower than the percentage of the 1692 excluded drug specialities relating to total consumption in 1992. The repercussion in cost, nevertheless, was greater than expected during the first year of selective financing application. This could be attributable to average price containment of drug specialities due to causes other than selective financing itself. The economic impact of selective financing after 1 year of application was reduced because of accommodation phenomena.

Cost Control↗

PubMed1996

Effect of several antidepressant drugs on isolated rat vas deferens in vitro.

Imipramine-N-oxide, quinupramine, clomipramine, doxepin, maprotiline, amineptine, amoxapine, mianserin, minaprine, nomifensine, viloxacine, trazodone and lofepramine effects were studied on rat vas deferens responses to noradrenaline. Tissues were prepared in Krebs-Henseleit solution with and without adding cocaine. 17 beta-estradiol and propranolol for blocking neuronal and extraneuronal noradrenaline reuptake. In normal Krebs-Henseleit solution imipramine-N-oxide, nomifensine, viloxacine and lofepramine increased noradrenaline responses, while clomipramine, trazodone and doxepin behaved as competitive antagonists. When adding cocaine, 17 beta-estradiol and propranolol to the solution there was antagonism but no increase in responses.

Adrenergic alpha-Agonists↗