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Biomedical subjects

L Hernández

Publications and source records attributed to L Hernández.

At least 19 recordsLinked to original sources
PubMed2007

Acrylic bone cements with bismuth salicylate: Behavior in simulated physiological conditions.

In a previous work, we reported the development of acrylic bone cement formulations for application in percutaneous vertebroplasty, by using bismuth salicylate (BS) as the radiopaque agent. Our objective was to obtain high radiopacity along with a therapeutical effect produced by the release of salicylic acid in situ. To follow that study, the setting kinetics and static and dynamical mechanical properties of the BS cements were studied in simulated physiological conditions. Moreover, radiopacity after various times of immersion in saline and the wettability of the cements surfaces were determined. The study finished with the analysis of the biological response. From the results, it can be concluded that physiological conditions did not affect negatively to the cements performance, since all BS-loaded cements fulfilled the ISO standard requirements. Radiopacity of the formulations was maintained over time and cements with BS were found to be biocompatible.

Acrylates↗
PubMed2006

Detection and identification of orthopoxviruses using a generic nested PCR followed by sequencing.

Some orthopoxviruses are considered to be potential biological weapons. After the smallpox eradication campaign ended, routine vaccination was stopped around the world. Consequently, a significant portion of the population is now completely unprotected from infection by variola virus and related orthopoxviruses. Some of the symptoms associated with non-variola infections can be similar to smallpox, causing alert and panic situations. These infections should be considered as real public health concerns, so suitable tools for their differential diagnosis are needed. This study aims to devise a simple and easy-to-perform method that is able to detect and identify any orthopoxvirus that might cause infection in humans. In addition, the similarity of the different genes in the genomes of several species of orthopoxviruses is investigated, and orthopoxvirus-universal primer pairs in the tumour necrosis factor receptor II homologue gene are designed, taking full account of nucleotide similarity. A strategy is devised for their sensitive, rapid and cost-effective detection and identification, based on a nested PCR followed by sequencing. The efficacy of the method is tested with samples sent by the European Network of Imported Viral Diseases as part of two external quality control assays. All human orthopoxviruses assayed were detected and identified.

Animals↗
PubMed2006

Detection and subtyping of dengue 1-4 and yellow fever viruses by means of a multiplex RT-nested-PCR using degenerated primers.

OBJECTIVE: Differential diagnosis of infections that cause similar diseases and may be active simultaneously in the same geographical areas is greatly needed. Dengue and yellow fever viruses (DENV and YFV) are transmitted by the same species of mosquito and both can cause haemorrhagic fever symptoms. These viruses are active mainly in regions where expensive and sophisticated technologies are not available. Our objective was to develop a simple, reliable and easy-to-perform method to detect and identify these viruses. METHODS: We slightly modified a generic RT-PCR able to detect the mentioned viruses and other members of this genus: specific primers for each one of these viruses were designed and included in the nested reaction instead of one of the generic ones. The reaction was optimized and viruses are amplified giving rise to bands of different sizes distinguishable in agarose gels. RESULTS: This test is able to detect and identify the four DENVs and YFV to a high level of sensitivity and specificity and can be used with clinical samples. This simple, reliable and easy-to-perform method able to detect and identify dengue 1-4 and YFV can be used in poor endemic countries.

DNA Primers↗
PubMed2006

Manipulation of the acetylation degree of Azotobacter vinelandii alginate by supplementing the culture medium with 3-(N-morpholino)-propane-sulfonic acid.

AIMS: The aim of this study was to characterize the influence of 3-(N-morpholino)-propane-sulfonic acid (MOPS) on alginate production by Azotobacter vinelandii and its chemical composition (particularly its acetylation degree), as well as on the rheological behaviour of alginate-reconstituted solutions. METHODS AND RESULTS: Cultures were grown in 500-ml flasks containing 90 ml of medium supplemented with MOPS in concentrations ranging from 0 to 13.6 mmol l(-1). The acetylation degree of the alginate was significantly influenced by the MOPS concentration, obtaining an alginate with an acetylation degree of 1.4% when 13.6 mmol l(-1) of MOPS was added to the medium. This value was twice as high as that obtained when no MOPS was used. The higher acetylation of the polymer resulted in higher viscosity of alginate solutions, having a more pronounced pseudoplastic behaviour. CONCLUSIONS: MOPS added to the culture medium determines the acetyl content of the alginate and thus, the physico-chemical properties of the polymer. SIGNIFICANCE AND IMPACT OF THE STUDY: These changes in the functional properties of the polymer can be very valuable in specific applications of alginate in the food and pharmaceutical fields.

Acetylation↗
PubMed2005

Generic RT-nested-PCR for detection of flaviviruses using degenerated primers and internal control followed by sequencing for specific identification.

Flaviviruses are a widespread and numerous group of arboviruses that can cause serious illness in humans. The continuous and slow spread of certain flaviviruses, such as Dengue viruses, and the recent entry and spread of West Nile virus to the American continent, point to the need to control these infections. This control requires the use of suitable techniques for diagnostic and surveillance programmes. A generic RT-nested-PCR that is, theoretically, able to detect each member of the group has been designed. The identification of the detected virus is carried out by sequencing. The introduction of an internal control would reduce the number of false negative results and could be used to quantify the viral load in clinical samples where the method works well.

False Negative Reactions↗
PubMed2005

[Validation of a respiratory polygraphy system in the diagnosis of sleep apnea syndrome].

OBJECTIVE: To validate a cardiorespiratory polygraphy system (BITMED NGP 140) by comparing it to conventional polysomnography in the diagnosis of sleep apnea-hypopnea syndrome. PATIENTS AND METHODS: Polysomnography and cardio-respiratory polygraphy were performed simultaneously on 103 consecutive patients referred because of suspected sleep apnea-hypopnea syndrome. The Bland and Altman method and intraclass correlation coefficients were used to assess agreement between the 2 methods of measurement. Receiver operating characteristic (ROC) curves were used to calculate the yield of cardiorespiratory polygraphy compared to that of conventional polysomnography. RESULTS: Ninety-two valid studies were obtained for 72 men and 20 women (mean [SD] age: 52.4 [12] years). By the Bland and Altman method, the difference between the respiratory event index obtained with the BITMED NGP140 and the apnea-hypopnea index (AHI) obtained by conventional polysomnography was 7.6 (13.2) in the manual analysis (95% confidence interval [CI], 4.9-10.4) and 12 (15.3) (95% CI, 8.8-15.3) in the automatic analysis. For a corrected AHI (AH/total time in bed) mean differences were -2.2 (5.9) and 2.4 (8.2) for manual and automatic analysis. The intraclass correlation coefficients were greater than 0.94. The areas under the ROC curves of the respiratory event index were greater than 0.97 for all cut points. For an AHI of 30 or higher, the best cut-off point determined by manual cardiorespiratory polygraphy analysis was 27 (sensitivity, 98% and specificity, 98%). For the different cut-off points cardiorespiratory polygraphy correctly classified between 92% and 98% of patients in both the manual and automatic analyses. CONCLUSIONS: The BITMED NGP140 had good agreement with conventional polysomnography for the measurement of respiratory events and provided high diagnostic yield.

Adult↗
PubMed2005

Checkpoint kinase 1 (CHK1) protein and mRNA expression is downregulated in aggressive variants of human lymphoid neoplasms.

CHK1: gene encodes for a serine/threonine kinase involved in the regulation of cell cycle progression and DNA damage checkpoints. To determine the role of CHK1 in the pathogenesis of lymphoid neoplasms and its relationship to other DNA damage response genes, we have analyzed the gene status, protein, and mRNA expression in a series of tumors and nonneoplastic lymphoid tissues. CHK1 protein and mRNA expression levels were very low in both reactive tissues and resting lymphoid cells, whereas tumor samples showed a variable pattern of expression related to their proliferative activity. However, seven aggressive tumors showed a dissociate pattern of extremely low or negative protein expression in spite of a high proliferative activity. Four of these tumors were diffuse large B-cell lymphomas (DLCLs) with concordant reduced levels of mRNA, whereas one blastoid mantle cell lymphoma (B-MCL) and two DLCLs had relatively normal levels of mRNA. No gene mutations, deletions, or hypermethylation of the promoter region were detected in any of these cases. In all these tumors ATM, CHK2, and p53 genes were wild type. These findings suggest that CHK1 inactivation in NHLs occurs by loss of protein expression in a subset of aggressive variants alternatively to ATM, CHK2, and p53 alterations.

Blotting, Western↗
PubMed2004

Responses of serum androgen and insulin resistance to metformin and pioglitazone in obese, insulin-resistant women with polycystic ovary syndrome.

Severe insulin resistance is a key abnormality in obese women with polycystic ovary syndrome (PCOS). The purpose of this study was to evaluate whether pioglitazone decreases insulin resistance (IR) and hyperandrogenism to the same extent as metformin in obese women with PCOS who have not received any previous treatment. Fifty-two women with PCOS were randomly allocated to receive either pioglitazone (30 mg/d, n = 25) or metformin (850 mg three times daily, n = 27) and were assessed before and after 6 months. Body weight, body mass index, and waist to hip ratio increased significantly (P </= 0.05) after pioglitazone treatment but not after metformin treatment. Fasting serum insulin concentration (P < 0.001 for both drugs) and the area under the insulin curve during a 2-h oral glucose tolerance test decreased after pioglitazone (P < 0.002) or metformin (P < 0.05) treatment. IR (homeostasis model of assessment-IR index) decreased and insulin sensitivity (elevation of the quantitative insulin sensitivity check index and the fasting glucose to insulin ratio) increased (P </= 0.008) after treatment with either drug. Hirsutism (P < 0.05) and serum concentrations of free testosterone (P < 0.02) and androstenedione (P < 0.01) declined to a similar extent after treatment with the drugs. Treatment with pioglitazone or metformin was associated with the occurrence of pregnancy (n = 5 and n = 3, respectively). These results suggest that pioglitazone is as effective as metformin in improving insulin sensitivity and hyperandrogenism, despite an increase in body weight, body mass index, and the waist to hip ratio associated with pioglitazone.

Adolescent↗
PubMed2004

Nocardia otitidiscaviarum (GAM-5) induces parkinsonian-like alterations in mouse.

Parkinson's disease, a major neurodegenerative disorder in humans whose etiology is unknown, may be associated with some environmental factors. Nocardia otitidiscaviarum (GAM-5) isolated from a patient with an actinomycetoma produced signs similar to Parkinson's disease following iv injection into NMRI mice. NMRI mice were infected intravenously with a non-lethal dose of 5 x 10(6) colony forming units of N. otitidiscaviarum (GAM-5). Fourteen days after bacterial infection, most of the 60 mice injected exhibited parkinsonian features characterized by vertical head tremor, akinesia/bradykinesia, flexed posture and postural instability. There was a peak of nocardial growth in the brain during the first 24 h followed by a decrease, so that by 14 days nocardiae could no longer be cultured. At 24 h after infection, Gram staining showed nocardiae in neurons in the substantia nigra and occasionally in the brain parenchyma in the frontal and parietal cortex. At 21 days post-infection, tyrosine hydroxylase immunolabeling showed a 58% reduction of tyrosine hydroxylase in the substantia nigra, and a 35% reduction of tyrosine hydroxylase in the ventral tegmental region. Dopamine levels were reduced from 110 +/- 32.5 to 58 +/- 16.5 ng/mg protein (47.2% reduction) in brain from infected mice exhibiting impaired movements, whereas serotonin levels were unchanged (191 +/- 44 protein in control and 175 +/- 39 ng/mg protein in injected mice). At later times, intraneuronal inclusion bodies were observed in the substantia nigra. Our observations emphasize the need for further studies of the potential association between Parkinson's disease or parkinsonism-like disease and exposure to various nocardial species.

Animals↗
PubMed2004

Protection against brucellosis in goats, five years after vaccination with reduced-dose Brucella melitensis Rev 1 vaccine.

The protection conferred by the reduced-dose Rev 1 Brucella melitensis vaccine in goats that had been immunized 5 years previously was evaluated. Sixteen goats vaccinated 5 years before with Rev 1 (1 x 10(5) cfu) and 5 non-vaccinated goats were challenged with B. melitensis 16M (4 x 10(5) cfu) using the conjunctival route. After giving birth or aborting, the goats were sacrificed and tissue samples were taken for bacteriological study. The challenge strain was recovered in 12%, of the animals from the vaccinated group, and in (80% of the control group. It is concluded, therefore that the use of reduced-dose Rev 1 protects goats vaccinated in endemic areas for at least 5 years after immunization.

Animals↗
PubMed2004

Drug induced weight gain, an impediment to successful pharmacotherapy: focus on antipsychotics.

The antipsychotic drugs (APDs) are fundamental tools in current psychiatric practice. A new generation of agents, the atypical APDs, represents an important progress in the treatment of psychotic disorders. Unfortunately, some of them induce excessive body weight gain (BWG), obesity, hyperglycemia and dyslipidemia in the following order: clozapine approximately equal to olanzapine > quetiapine > risperidone > ziprasidone = aripiprazole. Appetite stimulation is probably the main mechanism of BWG and this is strongly correlated with the APD affinity for H1 (histaminergic) and alpha1 (adrenergic) receptors. A composed ratio of the APD affinity for diverse neurotransmitters involved in food intake (FI) regulation correlates with BWG as well. Endocrine/metabolic mechanisms, such as the activation of the hypothalamus-pituitary-adrenal axis, changes in insulin sensitivity (by conventional and atypical agents), hyperprolactinemia and gonadal dysfunction (by conventional APDs and risperidone) may also be involved. Importantly, patients with schizophrenia may have a genetically-based predisposition to appetite dysregulation, insulin resistance and endocrine imbalance involving gonadal steroids. Excessive BWG must be prevented or attenuated by proper drug selection, combining or switching agents, nutritional assistance and physical exercise. Amantadine. metformin and reboxetine proved to significantly lessen APD-induced BWG. Notwithstanding this, novel strategies are necessary to treat this side effect in a clinical population particularly prone to poor compliance and under a high risk of negative drug interaction.

Animals↗
PubMed2003

[Protocol to evaluate automatic continuous positive airway pressure. Assessment of the usefulness of the Autoset-T device to determine optimal pressure for treating sleep apnea/hypopnea syndrome].

INTRODUCTION: Given the high prevalence of sleep apnea/hypopnea syndrome (SAHS) and great demand for conventional polysomnography (PSG) and long waiting lists, alternative means for diagnosing SAHS and titrating continuous positive airway pressure (CPAP) are needed. Automatic CPAP may play a role in meeting the last objective, not only for treatment but also for suggesting the optimum CPAP setting. OBJECTIVES: a) To define a protocol to assess the functioning of an automatic CPAP device by means of a mechanical model; b) to determine the behavior of automatically adjusted CPAP during PSG; c) to define the usefulness of automatic CPAP for indicating optimal CPAP pressure for patients with SAHS; d) to evaluate the efficacy of the automatically indicated pressure setting against conventional PSG. METHODS: Four protocols were carried out using the Autoset-T (AT) device. 1. Apneas, hypopneas, flow limitation, snoring and normal flow were simulated in a laboratory using a mechanical model in order to check AT functioning. 2. The behavior of the automatically adjusted CPAP was observed in real time during PSG in 12 patients with severe SAHS. 3. The agreement of CPAP titrated with the AT and with PSG was checked in a group of 39 patients with SAHS. 4. The efficacy of the CPAP pressure recommended by the AT was checked by PSG in a group of 14 patients with SAHS. RESULTS: With the AT, CPAP increased rapidly in response to apneas or snoring in the mechanical model and during conventional PSG; it took only a mean 2.8 3.1 min to rise from a baseline pressure of 4 cm H2O to a near-optimum pressure of 11 1 cm H2O. Once normal flow was reached CPAP slowly decreased, responding with great sensitivity to the slightest abnormality, especially snoring, but not changing in response to certain types of flow limitation. The pressure read visually on the AT was similar to the one recommended by PSG in most of the 39 patients (71%). The PSG performed after one month of using AT-recommended CPAP titration confirmed that the number of apneas, hypopneas (apnea/hypopnea index 6(1) and arousals (8 2) was normal for these SAHS patients. CONCLUSIONS: The AT increases pressure rapidly in the presence of respiratory events and maintains a normal breathing pattern in most patients. Visual reading of the AT pressure allows correct identification of the optimal CPAP setting for SAHS treatment.

Aged↗
PubMed2003

[Unusual molecular changes in two families with Friedreich's ataxia].

Friedreich's ataxia is an autosomal recessive disease generally characterized by the presence of microsatellite expansion in a GAA triplet. The patients inherit a pathologic allele from each one of their parents, that may sometimes show GAA triplet expansions or contractions. Two familial studies of typical Friedreich's ataxia are described. Their molecular study demonstrated marked intergenerational instability and an abnormally long expansion of the GAA triplet in the father in the other one. In the first case, there were expansions of 680/815 repetitions, being characterized by an expansion of 290 repetitions GAA in the father-patient transmission. The second case presented GAA of 1,260/1,095 expansions, while the expanded allele of the father was 1,350 repetitions. These cases illustrate that there can be both expansion as well as contraction of the GAA triplet from alleles of paternal origin in the disease, without any apparent phenotypic changes.

Alleles↗
PubMed2002

Multiple cell cycle regulator alterations in Richter's transformation of chronic lymphocytic leukemia.

To investigate the role of the cell cycle regulators p21(Waf1), p27(Kip1), retinoblastoma (Rb), and cyclin D1 in Richter's transformation of chronic lymphocytic leukemia (CLL), we analyzed 19 CLL and eight Richter's syndrome (RS) tumors, previously characterized for p53 and ARF/INK4a abnormalities. p21(Waf1)immunohistochemical expression was negative in 12 of 15 CLL (80%), whereas it was moderate or strong in three of seven RS (43%). p21(Waf1) gene was in germline configuration in all the tumors analyzed. Four immunohistochemical patterns of p53 and p21(Waf1) expression were observed: (1) p53-/p21- in 10 of 15 CLL (67%), but only in two of six RS (33%); (2) p53+/p21+ in three CLL (20%) and two RS (33%); (3) p53-/p21+ in one RS; and (4) p53++/p21- in two CLL and one RS. Two p53+/p21+ CLL evolved into RS. p53 mutations clustered around the p53++/p21- (two CLL and one RS) and p53-/p21- (one CLL and one RS) tumors. While the majority of CLL displayed strong p27 immunoreactivity, RS tumors were constantly p27-negative. p27(Kip1) gene was in germline configuration in all the tumors analyzed. Most CLL cases were negative for Rb expression. In contrast, all RS exhibited strong Rb expression. Cyclin D1 overexpression was only detected in one CLL evolving into RS and one RS. In conclusion, a p53+/p21- immunohistochemical pattern is shown exclusively by p53-mutated CLL/RS. Additionally, our results suggest a possible implication of moderate/strong p21(Waf1) expression, loss of p27 expression, and cyclin D1 overexpression in the Richter's transformation of CLL.

Adult↗
PubMed2001

Influence of diuretics on the concentration of proteins and other components of pleural transudates in patients with heart failure.

PURPOSE: Diuretic therapy increases the total protein and lactate dehydrogenase concentrations in pleural fluid in patients with transudates due to heart failure, but the effect of diuresis on other substances in pleural fluid constituents is not known. SUBJECTS AND METHODS: Twenty-one patients with transudative pleural effusions due to congestive heart failure were prospectively studied. Repeated diagnostic thoracentesis (mean +/- SD = 3 +/- 1; range, 2 to 6) was performed until the effusions were radiographically unapparent (5 +/- 2 days). Thirty-one patients with congestive heart failure who underwent only a single thoracentesis after diuretic therapy served as controls. We measured the concentrations of various components of pleural effusions in the serum and in the pleural fluid, and determined the serum-pleural fluid gradient (serum concentration minus pleural fluid concentration) and ratio (serum concentration divided by pleural fluid concentration). RESULTS: The pleural concentrations of most components increased significantly (P <0.001) from the initial specimen to the final specimen: total protein, from 23 +/- 7 g/L to 33 +/- 9 g/L; albumin, from 13 +/- 4 g/L to 18 +/- 6 g/L; lactate dehydrogenase, from 177 +/- 62 U/L to 288 +/- 90 U/L; cholesterol, from 31 +/- 16 mg/dL to 52 +/- 22 mg/dL; and cholinesterase, from 1,304 +/- 616 U/L to 1,884 +/- 674 U/L. Expressed as percentage change, the increases in the serum-pleural fluid gradients for albumin (12% +/- 22%) and total protein (11% +/- 12%) were significantly less than the increases in their concentrations in pleural fluid (albumin, 47% +/- 49%; total protein, 48% +/- 40%) or in their pleural fluid/serum ratios (albumin, 27% +/- 29%; total protein, 38% +/- 34%). CONCLUSIONS: The concentrations of the biochemical components commonly measured in pleural fluid increase progressively during diuretic therapy. Calculation of the serum-pleural fluid gradients for protein and albumin may be the most useful way to distinguish transudates from exudates in patients with congestive heart failure who have undergone diuresis.

Aged↗