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Biomedical subjects

L Rodríguez

Publications and source records attributed to L Rodríguez.

At least 55 records · Page 3Linked to original sources
PubMed2000

Cloning and characterization of a Candida albicans gene homologous to fructose-1,6-bisphosphatase genes.

By sequencing of the DNA adjacent to the Candida albicans SEC61 gene, an open reading frame encoding a polypeptide of 331 amino acids was found. The predicted protein showed a strong homology with the fructose-1,6-bisphosphatase [FbPase] from other organisms, and conserved regions included the catalytic motif found in all known FbPases. Although the cloned gene did not complement the growth failure of a Saccharomyces cerevisiae fbp1 mutant in media with gluconeogenic carbon sources, it was transcribed in the transformants in a fashion that indicates a partial repression by glucose. A similar control on the transcription of this gene and on FbPase activity was found in wild-type C. albicans, where the cloned gene (CaFBP1) was shown to be localized in a single chromosomal locus in the genome.

Candida albicans↗
PubMed2000

Hepatitis E virus in Cuba.

The hepatitis E virus (HEV) has a global distribution and is known to have caused large waterborne epidemics of icteric hepatitis. The transmission is primarily fecal-oral. Some reports have suggested parenteral transmission of HEV from its association to hepatitis B or hepatitis C infection, or due to the development of hepatitis E after blood transfusion. Though most of the developing countries in Asia and Africa have been shown to be endemic for HEV infection, studies in the Latin American countries have been limited to Mexico, Brazil and Venezuela. We have developed an enzyme immunoassay (EIA) for IgM and IgG antibodies to a recombinant protein containing antigenic epitopes of the ORF3 region of the HEV. This system, as well as a commercial kit that includes ORF2 and ORF3 antigenic epitopes, were used to study the prevalence of anti-HEV antibodies in a sample of Cuban blood donors, acute hepatitis cases and individuals subjected to plasmapheresis. The incidence of anti-HEV IgM was compared with other viral hepatitis markers. Our findings suggest that infections due to HEV are an important viral cause of sporadic hepatitis in Cuba, and that HEV is endemic to this region of the world.

Adult↗
PubMed2000

Characterization of recombinant invertase expressed in methylotrophic yeasts.

We studied, for the first time, characterization of the invertase expressed in the methylotrophic yeasts Hansenula polymorpha and Pichia pastoris in terms of enzyme conformational stability and structural behaviour induced by temperature as a function of pH using enzymic assays, differential scanning calorimetry, fluorescence and CD. The enzyme produced in both hosts was very stable over a broad range of pH values, keeping its enzymic activity and structure above 60 degrees C. Thermal denaturation, as measured by differential scanning calorimetry, was always irreversible. However, the fact that scanning rate had no effect on the calorimetric curves gave us the chance to analyse the data from a thermodynamic point of view. The conformational stabilities were essentially identical under the experimental conditions studied, but stability was always slightly higher in the enzyme expressed in H. polymorpha. This fact indicates that the greater degree of glycosylation of this enzyme form contributed to its increased global stability. Reactivation upon heating at 80 degrees C depends on protein concentration, suggesting that irreversibility could be associated with slow refolding kinetics at high protein concentration.

Calorimetry, Differential Scanning↗
PubMed1999

Biocompatibility in vitro tests of Zinalco.

In this study, cultures of human lymphocytes were exposed for 48 h to aqueous suspensions of Zinalco, with different times of corrosion, to test the biocompatibility of this alloy and support its use in medical implants. The results show that the Zinalco concentrations assessed affect the mitotic index (MI) and some also increase the length of DNA migration measured in the comet assay in a significant manner; none of them showed clastogenic nor aneugenic effects. The authors conclude that Zinalco may be considered as an alternative biomaterial and suggest its use for short-term implants.

Adult↗
PubMed1999

[Prevalence of IgG antibodies against Cytomegalovirus in patients with angiographically demonstrated coronary atherosclerosis].

BACKGROUND: Over the past 25 years the potential role of herpesvirus and particularly Cytomegalovirus as a factor which contribute to atherogenesis, and more recently in restenosis, has been investigated. OBJECTIVES: To determine the rate of Cytomegalovirus seropositivity in patients with angiographically demonstrated Coronary Artery Atherosclerosis. PATIENTS AND METHODS: The subjects were all adult patients undergoing coronary angiography at the Hospital Virgen de la Salud, Toledo between February, 1997 and May, 1998. From each patient, blood was drawn and collected to be assayed. Also we collected the data from sex, age, classic risk factors for coronary artery disease (hypertension, hypercholesterolemia, diabetes and cigarette smoking) and catheterization. Data from 437 patients who underwent cardiac catheterization were collected. There was 349 (82.3%) patients who underwent catheterization because of Ischemic Heart Disease. SEROLOGIC ASSAYS: Serum IgG antibodies to cytomegalovirus were measured quantitatively with EIA, VIDAS, (bioMérieux). As recommended by the manufacturer a titer over 6 was considered positive. RESULTS: There was 115 female and 319 males. Patients were 24-86 years old. Data from catheterization showed that 113 patients (26%) have no lesions on coronaryography and 321 patients (74%) have Coronary Artery Disease (CAD). The rate of Cytomegalovirus-seropositive was 97.1% in patients with lesions and 98.2% in those without lesions. CONCLUSIONS: There is a high rate of antibodies positive for Cytomegalovirus in the population, in patients with Ischemic Heart Disease and with coronary artery disease as in those without lesions in the coronarigraphy. Our conclusion is that if Cytomegalovirus could have any role in the building of proliferating ateheromas and in view of seroepidemiological studies some other factors must be implicated in the development of plaque growth.

Adult↗
PubMed1998

Structural model for family 32 of glycosyl-hydrolase enzymes.

A structural model is presented for family 32 of the glycosyl-hydrolase enzymes based on the beta-propeller fold. The model is derived from the common prediction of two different threading methods, TOPITS and THREADER. In addition, we used a correlated mutation analysis and prediction of active-site residues to corroborate the proposed model. Physical techniques (circular dichroism and differential scanning calorimetry) confirmed two aspects of the prediction, the proposed all-beta fold and the multi-domain structure. The most reliable three-dimensional model was obtained using the structure of neuraminidase (1nscA) as template. The analysis of the position of the active site residues in this model is compatible with the catalytic mechanism proposed by Reddy and Maley (J. Biol. Chem. 271:13953-13958, 1996), which includes three conserved residues, Asp, Glu, and Cys. Based on this analysis, we propose the participation of one more conserved residue (Asp 162) in the catalytic mechanism. The model will facilitate further studies of the physical and biochemical characteristics of family 32 of the glycosyl-hydrolases.

Amino Acid Sequence↗
PubMed1998

Cloning and sequence analysis of the gene encoding invertase (INV1) from the yeast Candida utilis.

The gene INV1 encoding invertase from the yeast Candida utilis has been cloned using a homologous PCR hybridization probe, amplified with two sets of degenerate primers designed considering sequence comparisons between yeast invertases. The cloned gene was sequenced and found to encode a polypeptide of 533 amino acids that contain a 26 amino-acid signal peptide and 12 potential N-glycosylation sites. The nucleotide sequences of the 5' and 3' non-coding regions were found to contain motifs probably involved in initiation, regulation and termination of gene transcription. The amino-acid sequence shows significant identity with other yeast, bacterial and plant beta-fructofuranosidases. The INV1 gene from C. utilis was able to complement functionally the suc2 mutation of S. cerevisiae.

Amino Acid Sequence↗
PubMed1998

Development of an integrative DNA transformation system for the yeast Candida utilis.

We report here the development of an auxotrophic transformation system for the food yeast Candida utilis. To facilitate molecular studies in Candida utilis, we isolated auxotrophic strains for uracil biosynthesis by the combination of NTG-mutagenesis and 5-fluorotic acid (FOA) selection. The ura-mutation could be functionally complemented by the homologous URA3 gene. We used both, LiAc and electroporation methods to direct insertions at the ura3 locus through homologous recombination.

Blotting, Southern↗
PubMed1998

Isolation and sequence analysis of the orotidine-5'-phosphate decarboxylase gene (URA3) of Candida utilis. Comparison with the OMP decarboxylase gene family.

The URA3 gene of Candida utilis encoding orotidine-5'-phosphate decarboxylase enzyme was isolated by complementation in Escherichia coli pyrF mutation. The deduced amino-acid sequence is highly similar to that of the Ura3 proteins from other yeast and fungal species. An extensive analysis of the family of orotidine-5'-phosphate decarboxylase is shown. The URA3 gene of C. utilis was able to complement functionally the ura3 mutation of Saccharomyces cerevisiae.

Amino Acid Sequence↗
PubMed1998

Protective effect of nifedipine against carrageenan-induced inflammation.

Administration of carrageenan (CA; 0.5 mg) to the plantar tissue of rats resulted in reversible inflammatory injury. The edema was monitored by changes in paw volume using a plethysmometer. Simultaneous administration of CA and nifedipine, intraperitoneally, at different doses (10, 20 and 50 mg/kg) prevented the inflammatory action, and the effect was dose- and time-dependent. In order to improve the nifedipine effects, we prepared liposomed nifedipine which, administered intraperitoneally, showed a greater anti-inflammatory action. In the presence of the L-type channel agonist Bay K 8644, the inflammation produced by CA increased and it was counteracted by free or liposomed nifedipine. The significance of these findings with respect to the mechanism of the anti-inflammatory action of nifedipine is discussed.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1998

[The relation of Helicobacter pylori with dysplasia and stomach neoplasms in Costa Rica].

Occurrence of the bacterium Helicobacter pylori was compared for two Costa Rican sites with contrasting levels of gastric cancer incidence, Poás (incidence 15.13%) and Puriscal (83.53%). A sample of 185 adults of similar age and sex proportions was studied in each site, using both H. pylori antiserum tests and gastroscopy to collect two biopsies per case. No clear association between H. pylori and gastric cancer was found.

Adult↗
PubMed1998

[The effect of isoflurane on coronary autoregulation in hypothermia].

OBJECTIVES: To analyze the effect of isoflurane on myocardial metabolism and coronary hemodynamics during the reheating phase after heart surgery. PATIENTS AND METHODS: Sixteen patients (12 women and 4 men), with cardiac output greater than 0.5 undergoing aortic and/or mitral valve surgery, were studied prospectively. A retrograde thermodilution catheter was placed in the heart and a Swan-Ganz catheter was inserted in the pulmonary artery to determine coronary blood flow and pulmonary wedge pressure, respectively, as well as myocardial and systemic parameters. After surgery, and with hemodynamic variables stable and rectal temperature at 34 +/- 0.5 degrees C, 0.4% isoflurane was administered at the end of expiration. Variables were recorded before administering isoflurane and 20 minutes afterwards. RESULTS: Isoflurane administration decreased coronary perfusion pressure, coronary vascular resistance, regional myocardial oxygen consumption and myocardial oxygen output. Increases in coronary oxygen saturation and in large coronary vein saturation were also observed. No patient experienced significant changes in ST segment, enzymes or decreased clearance of lactic acid. CONCLUSIONS: Administering 0.4% isoflurane at the end of expiration effected coronary vasodilation without altering oxygenation or myocardial metabolism. Moreover, no electrocardiographic, enzymatic or metabolic signs of myocardial ischemia were observed.

Adult↗
PubMed1998

Effects of colchicine and colchiceine in a biochemical model of liver injury and fibrosis.

BACKGROUND: The accumulation of collagen is a salient feature of chronic liver injury. The objective of this study was to investigate and compare the therapeutic effectiveness of colchicine and one of its metabolites, colchiceine, to protect rats from developing liver injury and fibrosis. METHODS: To accomplish this, the authors used a procedure developed by others to produce liver injury and fibrosis by chronic administration of CCl4 in rats. The effect of both compounds on collagen metabolism and liver injury was analyzed. RESULTS: Although both compounds prevented increase in collagen synthesis, animals treated with colchicine did not show a reduction in collagen content compared with animals treated with CCl4. On the other hand, the animals treated with colchiceine along with CCl4 showed a 50% reduction in hepatic collagen content as well as an improvement in histological architecture. Both compounds, colchicine and colchiceine, increased the intracellular degradation of collagen in addition to increasing collagenase activity as compared to non-treated rats. However, collagenase activity was lower in animals treated with colchicine and colchiceine than in the fibrotic livers treated with CCl4. The changes in collagen metabolism correlated with changes in parameters of liver injury. CONCLUSIONS: In conclusion, the compound colchiceine may be recommended in the treatment of chronic liver diseases rather than its precursor, colchicine, due to the fact that it showed a lower accumulation of collagen content and has a better anti-fibrogenic effect than does colchicine.

Animals↗
PubMed1998

[Familial cerebral cavernomatosis associated with cutaneous angiomas].

UNLABELLED: OBJECTIVE, PATIENTS AND METHOD: We present a genealogical study of a person with familial cerebral cavernomatosis (CCF) discovered following study of a man who presented with status epilepticus at the age of 35 years. This had also affected another three members of the family consisting of a total of 43 persons, studied over six generations. RESULTS: In the family members studied we did not find cavernomas at other sites but there were dermatological lesions whose relation to cerebral cavernomas (CC) is discussed. CCs are the second commonest type of cerebral vascular malformations. Their major clinical features are epilepsy and cerebral haemorrhage. There are two forms of CC: a sporadic form with single lesions and a familial form with multiple lesions. Although the condition has been recognized since 1854, very little is known about it. Recently a gene causing the familial form has been found on chromasome 7. CONCLUSIONS: We discuss the clinical findings in this family with relation to descriptions in the literature. We emphasize the importance of MR in diagnosis of the condition and for detection of asumptomatic carriers. We consider a possible relationship between these findings and genes which have been mapped, and in view of recent genetic data, the hypothesis of a possible Spanish ancestor with the condition.

Adolescent↗
PubMed1997

Results of 12 years' combined maternal serum alpha-fetoprotein screening and ultrasound fetal monitoring for prenatal detection of fetal malformations in Havana City, Cuba.

Progressively since 1982 and as part of a nationwide programme for the diagnosis and prevention of genetic diseases, maternal serum alpha-fetoprotein (MS-AFP) screening and ultrasound fetal monitoring has been implemented in all pregnant women in Cuba. In Havana City, 328,983 pregnant women underwent MS-AFP screening between 15 and 19 weeks of gestational age. With a cut-off level of > or = 2 multiples of the normal median (MOM), 1767 amniocenteses were carried out to determine the levels of amniotic fluid AFP and 685 malformed fetuses were diagnosed. By ultrasound fetal monitoring, an additional 686 malformed fetuses were detected. As a result of the programme, the birth prevalence of neural tube defects has fallen by 90 per cent.

Amniotic Fluid↗
PubMed1997

Video sequence compression via supervised training on cellular neural networks.

In this paper, a novel approach for video sequence compression using Cellular Neural Networks (CNN's) is presented. CNN's are nets characterized by local interconnections between neurons (usually called cells), and can be modeled as dynamical systems. From among many different types, a CNN model operating in discrete-time (DT-CNN) has been chosen, its parameters being defined so that they are shared among all the cells in the network. The compression process proposed in this work is based on the possibility of replicating a given video sequence as a trajectory generated by the DT-CNN. In order for the CNN to follow a prescribed trajectory, a supervised training algorithm is implemented. Compression is achieved due to the fact that all the information contained in the sequence can be stored into a small number of parameters and initial conditions once training is stopped. Different improvements upon the basic formulation are analyzed and issues such as feasibility and complexity of the compression problem are also addressed. Finally, some examples with real video sequences illustrate the applicability of the method.

Algorithms↗
PubMed1997

Viral isolation from cases of epidemic neuropathy in Cuba.

OBJECTIVE: To investigate the possibility of a viral agent in the central nervous system of patients with epidemic neuropathy. DESIGN: Virus isolation attempts, in cell cultures and suckling mice, from cerebrospinal fluid (CSF) of neuropathy patients and controls undergoing lumbar puncture for unrelated reasons. Serologic studies in patients, contacts, and controls. SETTING: An epidemic of optic and peripheral neuropathy affected more than 50,000 people in Cuba in 1991 through 1993. Illness was associated with dietary limitations and increased physical demands accompanying the shortages of food and fuel experienced in Cuba since 1989. Most patients responded to parenteral vitamin therapy, and the epidemic began to subside when oral vitamin supplementation was begun for the entire Cuban population. RESULTS: Coxsackievirus A9 (five isolates) and a similar, less cytopathic virus (100 isolates) were recovered from 105 (84%) of 125 CSF specimens from neuropathy patients. The strains with light cytopathic effect were antigenically related to Coxsackieviruses A9 and B4 by cross-neutralization and immunoblotting assays. Virus persisted in CSF of some patients for 1 to 12 months. Cerebrospinal fluid from patients and both types of virus from cell culture produced illness, including complete posterior flaccid paralysis, in newborn mice, and virus was reisolated from the mice. Mouse tissues and sural nerve biopsy specimens from patients were stained by immunoperoxidase and colloidal gold techniques using hyperimmune rabbit antisera against the virus with light cytopathic effect. CONCLUSIONS: Coxsackievirus A9 or an antigenically related agent with a light cytopathic effect was present in CSF of 84% of 125 patients with epidemic neuropathy. The role of these agents, probably in combination with nutritional factors, in the pathophysiology of the disease requires further investigation.

Adult↗