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Biomedical subjects

D Hernández

Publications and source records attributed to D Hernández.

At least 19 recordsLinked to original sources
PubMed2006

Wave-front dynamics in systems with directional anomalous diffusion.

In this paper we study the solutions of a generalized reaction-diffusion system with a bistable reaction term, and considering directional anomalous diffusion. We use the well-known properties of fractional derivatives to model asymmetric anomalous diffusion, and obtain traveling wave solutions that propagate in a direction that depends on the metastability of the front, the fractional exponent and the asymmetry of the diffusion.

Journal Article↗
PubMed2006

Presentation and role of transplantation in adult patients with type 1 primary hyperoxaluria and the I244T AGXT mutation: Single-center experience.

Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder characterized by allelic and clinical heterogeneity. We aim to describe the presentation and full single-center experience of the management of PH1 patients bearing the mutation described in our community (I244T mutation+polymorphism P11L). Since 1983, 12 patients with recurrent renal lithiasis have been diagnosed with PH1 and renal failure in the Canary Islands, Spain. Diagnostic confirmation was based on the presence of oxalosis in undecalcified bone or kidney allograft biopsy, reduced alanine:glyoxylate aminotransferase activity in liver biopsy, and blood DNA analysis. Patients underwent different treatment modalities depending on individual clinical circumstances and therapeutic possibilities at the time of diagnosis: hemodialysis, isolated kidney, simultaneous liver-kidney, or pre-emptive liver transplantation. In all cases, the presentation of advanced renal disease was relatively late (>13 years) and no cases were reported during lactancy or childhood. The eight patients treated with hemodialysis or isolated kidney transplantation showed unfavorable evolution leading to death over a variable period of time. In contrast, the four patients undergoing liver transplantation (three liver+kidney and one pre-emptive liver alone) showed favorable long-term allograft and patient survival (up to 12 years follow-up). In conclusion, in this PH1 population, all bearing the I244T mutation, the development of end-stage renal disease was distinctive during late adolescence or adulthood. Our long-term results support pre-emptive liver transplantation at early stages of renal failure, and kidney-liver transplantation for those with advanced renal disease.

Adolescent↗
PubMed2006

Successful therapeutic use of rituximab in refractory membranous glomerulonephritis.

We present the case of a 57-year-old man with nephrotic syndrome secondary to idiopathic membranous glomerulonephritis unsuccessfully treated with angiotensin-converting enzyme inhibitor (ACEI), angiotensin II receptor antagonist (ARA), prednisone and chlorambucil. After treatment with rituximab, we observed a progressive decrease of proteinuria and normalization of serum albumin. 18 months after treatment, he remained in remission. No adverse reactions to rituximab were noted throughout follow-up.

Antibodies, Monoclonal↗
PubMed2005

The effect of a therapeutic trial of high-dose rabeprazole on symptom response of patients with non-cardiac chest pain: a randomized, double-blind, placebo-controlled, crossover trial.

BACKGROUND: Therapeutic trials with high-dose lansoprazole and omeprazole have been shown to be sensitive clinical tools for diagnosing patients with gastro-oesophageal reflux disease-related non-cardiac chest pain. AIM: To determine the clinical value of a therapeutic trial of high-dose rabeprazole over 7 days in detecting patients with gastro-oesophageal reflux disease-related non-cardiac chest pain. METHODS: Double-blind, randomized, placebo-controlled, crossover study. Patients referred by a cardiologist after a comprehensive cardiac work-up were enrolled into the study. Oesophageal mucosal disease was determined by upper endoscopy and 24-h oesophageal pH monitoring assessed acid exposure. Patients were then randomized to either placebo or rabeprazole 20 mg am and 20 mg pm for 7 days. After a washout period of 1 week, patients crossed over to the other arm of the study for an additional 7 days. Patients completed a daily diary assessing severity and frequency of chest pain throughout the baseline, treatment and wash-out periods. The rabeprazole therapeutic trial was considered as a diagnostic tool, if chest pain scores improved > or =50% from baseline. RESULTS: Of the 35 patients enrolled, 16 (46%) were diagnosed as gastro-oesophageal reflux disease-positive and 19 (54%) as gastro-oesophageal reflux disease-negative. Of the gastro-oesophageal reflux disease-positive patients, 12 of 16 (75%) had a significant symptom improvement on rabeprazole when compared with 3 of 16 (19%) on placebo (P = 0.029). Of the gastro-oesophageal reflux disease-negative group, only two of 19 (11%) improved significantly on the medication and four of 19 (21%) on placebo (P = 0.6599). The calculated sensitivity and specificity of the rabeprazole therapeutic trial was 75% and 90%, respectively. CONCLUSIONS: A rabeprazole therapeutic trial is highly sensitive and specific for diagnosing gastro-oesophageal reflux disease-related non-cardiac chest pain patients.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2005

Updated metaanalysis of steroid withdrawal in renal transplant patients on calcineurin inhibitor and mycophenolate mofetil.

During the 1990s two metaanalysis of randomized clinical trials of steroid withdrawal after renal transplantation showed significant increases in acute rejection episodes and graft failure rates. A recently published metaanalysis of steroid withdrawal in patients on a calcineurin inhibitor and MMF included randomized clinical trials. We have updated this study, searching more publications during the last 2 years. Finally, the same six trials were included, four in patients receiving cyclosporine and two tacrolimus. Risk ratio (RR) for acute rejection was 2.28 [95%CI 1.65-3.16, P < .00001], and pooled risk difference (RD) was 0.08 [0.05-0.11, P < .001], indicating that the proportion of patients with acute rejection episodes after prednisone withdrawal was significantly higher compared with controls. RR for graft failure was 0.73 [0.42-1.28, P = .27], and RD was -0.01 [-0.03-0.01, P = .28], indicating that the proportion of patients with graft failure after withdrawal was not significantly different from that of controls. Total cholesterol was significantly lower after steroid withdrawal (weighted mean difference -0.53 mumol/L [-0.70--0.36, P < .0001]). Renal allograft recipients on triple therapy with a calcineurin inhibitor, MMF, and steroids are at low but significant risk of acute rejection after steroid withdrawal, but do not suffer an increased risk of early graft failure. It is necessary to extend controlled follow-up to confirm graft function stabilization.

Adrenal Cortex Hormones↗
PubMed2005

Antimicrobial activity of lactic acid bacteria isolated from Tenerife cheese: initial characterization of plantaricin TF711, a bacteriocin-like substance produced by Lactobacillus plantarum TF711.

AIMS: The screening and initial characterization of bacteriocins produced by lactic acid bacteria (LAB) from raw Tenerife goats' cheese with possible application as biopreservatives or ripening accelerators for Tenerife cheese. METHODS AND RESULTS: One hundred and eighty LAB of the genera Lactobacillus (95), Leuconostoc (64) and Lactococcus (21) isolated from raw Tenerife goats' cheese were screened for the production of antimicrobial substances. Lactobacillus plantarum TF711, which had the broadest spectrum of antimicrobial activity, was selected for further characterization. The antimicrobial compound was determined as a proteinaceous substance, as it was sensitive to proteases. The bacteriocin-like substance, which we called plantaricin TF711, was active against the Gram-positive bacteria Bacillus cereus, Clostridium sporogenes and Staphylococcus aureus; and against the Enterobacteriaceae Shigella sonnei and Klebsiella pneumoniae. It was stable to heat and to treatment with surfactants and organic solvents. Highest antimicrobial activity was found between pH 1 and 9. Plantaricin TF711 exhibited primary metabolite kinetics, a bacteriostatic mode of action and a molecular mass of c. 2.5 kDa as determined by tricine SDS-PAGE. CONCLUSIONS: Lact. plantarum TF711 produces a low molecular mass bacteriocin-like compound with a wide spectrum of activity and interesting technological properties (thermostability, good pH stability and stability against surfactants and organic solvents). SIGNIFICANCE AND IMPACT OF THE STUDY: Plantaricin TF711 was found to have potential for use as a biopreservative in the food industry.

Anti-Bacterial Agents↗
PubMed2005

[Efficacy and safety of two vitamin supplement regimens on homocysteine levels in hemodialysis patients. Prospective, randomized clinical trial].

UNLABELLED: High levels of homocysteine (tHcy) are frecuent in MHD patients, and recognized as a risk factor for cardiovascular events. Vitamin supplements have been shown to lower serum Hcys, although optimal dose and efficacy is not well defined. Moreover, methylenetetrahydrofolate reductase (MTHFR) gene polymorphism can modulate its prevalence and response to treatment. OBJECTIVE: To evaluate efficacy and safety of two vitamin supplement regimens on Hcys serum levels over a 12 month period. METHODS: We conducted a prospective, randomised, double-blind trial in 60 stable MHD patients (68 +/- 13 years, 48% male, 50% diabetics). Patients were randomly assigned to one of two treatment regimens: 1) daily renal multivitamin containing folate (FA), vitamin B6 and B12 (5 mg, 10 mg and 0.4 mg respectively) (N = 27); and 2) supraphysiological daily doses (15 mg, 100 mg and 1 mg) (N = 33). These regimens were continued throughout the study period. Hcys levels were compared with a control group from the general population (N = 276) matched for age and gender. MEASUREMENTS: demographic and clinical data, serum levels of Hcys, FA, B6, B12 at baseline and after 1, 3, 6 and 12 months of treatment; MTHFR gene polymorphism (PCRRT). RESULTS: At baseline, global prevalence of hyperhomocysteinemia (tHcy > or = 15 micromol/L) was 100% in patients and 22% en controls. Hcys levels were significantly higher in patients versus controls (32.4 +/- 8.9 vs 12.9 +/- 6.8; P < 0.0001). Both regimens were equally effective in reducing Hcys levels. As a whole, Hcys levels were reduced by 23.6% (P < 0.001) after one month of treatment. The highest reduction was observed at the sixth month (28.3%, 32.4 +/- 8.9 vs 22.7 +/- 6.4, P < 0.001) and remained stable thereafter. However, only 12% of patients normalised their plasma levels after 12 months of therapy. The effect of treatment was not influenced by age, gender, diabetes, body weight or time on MHD. Reduction rate of tHcy levels was related to baseline tHcy level (r = 0.500, P < 0.001) and baseline FA levels (r = -0.332, P = 0.009). The MTHFR polimorfism did not significantly modified the effect of the treatment. No side effects were associated with either regimen. CONCLUSIONS: Hyperhomocysteinemia is common in patients with conventional HD schedules and this is not related to vitamin deficiencies. Vitamin supplements significantly reduce Hcys levels in a sustained but suboptimal way. Supraphysiological doses did not improve the results. Further studies are requiered to demonstrate that this effect is associated with an improval in morbidity and mortality.

Aged↗
PubMed2005

[Improved short-term cardiovascular profile after simultaneous pancreas-kidney transplantation].

The prognosis of type 1 diabetes mellitus (T1DM) patients with chronic renal failure (CRF) improves after simultaneous pancreas-kidney (SPK) transplantation. In order to evaluate the changes in cardio-vascular risk (CVR) factors after SKP, we studied nine recipients before and 6 months after SPK. There were five females and four males, with a mean age of 37 +/- 8 years, duration of diabetes of 24 +/- 5 years, three of them before starting dialysis, and six on dialysis (hemodialysis = 5; peritoneal dialysis = 1). Before SPK, all patients received anti-hypertensive therapy (1-4 drugs; mean 2.2 +/- 0.9) and eight received statins. At 6 months after SPK, all patients were under triple immunosuppressive therapy (steroids + tacrolimus + MMF) without statins. They had normal renal function (Plasma Creatinine = 1.2 +/- 0.3 mg/dl) and pancreatic endocrine function (glycemia = 80 +/- 8 mg/dl). HbA1c decreased significantly (8.4 +/- 1.2 vs 4.7 +/- 0.6%; p < 0.007) with a value > 7% in seven patients before SPK and in none 6 months after SKP transplantation (p < 0.001). Although Body Mass Index increased (23 +/- 2 vs 25 +/- 3 kg/m2; p < 0.05), plasma triglycerides decreased (130 +/- 51 vs 88 +/- 33 mg/dl; p < 0.05), and total cholesterol, LDL-cholesterol and HDL-cholesterol were similar. Systolic and diastolic blood pressure (BP) decreased (156 +/- 7 vs 133 +/- 15; p < 0.01 and 96 +/- 7 vs 79 +/- 9; p < 0.007) with only two patients on anti-hypertensive therapy (1 drug). Likewise, before transplantation all patients were hypertensive (six grade 1 and three grade 2) while this was observed in only two at the end of follow-up (both grade 1) (p < 0.001). In conclusion, SPK transplantation with good renal and pancreatic function is associated with a short-term improvement in CVR profile.

Adult↗
PubMed2005

Double-blind, placebo-controlled study of immunotherapy with Parietaria judaica: clinical efficacy and tolerance.

Allergy to Parietaria causes significant morbidity in most Mediterranean areas. The aim of this study is to investigate the efficacy and tolerance of Parietaria depot extract at 25 BU/mL (1.5 microg/mL Par j 1). We performed a multicenter double-blind, placebo-controlled study in rhinitic patients with/without asthma, sensitized to Parietaria. 42 patients followed 20-month immunotherapy. Clinical efficacy was based on symptom and medication scores and the percentage of healthy days (days without symptoms or medication). Severity of asthma/rhinitis scales, visual analogue scale, evaluation of the treatment by doctors and patients, immediate and delayed cutaneous response and quality of life questionnaires were also studied. The active group showed a sustained decrease in symptoms (p = 0.008), medication (p = 0.009) and both (p = 0.001), and an increase in healthy days (p = 0.001) throughout the study, with a threefold increase of healthy days and almost a three time reduction in medication only after one year of treatment. Asthma and rhinitis severity scales also decreased after immunotherapy, and blinded clinical evaluation by physicians confirmed efficacy in 85% and 77% of the active patients. Patient's self-evaluation returned similar results. None of these changes were observed with placebo. Immediate cutaneous response was significantly reduced at the maintenance phase in the active group and remained reduced throughout the study. Late-phase response after intradermal testing also showed a statistical decrease in actively treated patients. Immunotherapy was well tolerated and every systemic reaction reported was mild. In conclusion, immunotherapy with Parietaria 25 BU/mL is an effective and safe treatment for patients with respiratory allergies.

Adolescent↗
PubMed2004

Experience with cyclosporine in the Canary Islands.

Cyclosporine (CsA) is currently the basis of most immunosuppressive protocols after solid organ transplantation. The introduction of Neoral, a new microemulsion formulation of CsA, and more recently a range of adjunctive immunosuppressants have further enhanced short-term efficacy and tolerability of CsA-based immunosuppression. In addition, Neoral C2 monitoring has been shown to have advantages not only in the early posttransplant period, but also for maintenance transplant patients. The major long-term disadvantage associated with CsA is the development of nephrotoxicity and chronic allograft nephropathy (CAN), which is the second major cause of graft failure. Thus, strategies to reduce the risk of CAN include CsA-sparing protocols, use of C2 level monitoring, introduction of non-nephrotoxic adjunctive immunosuppressants, and optimal management of additional risk factors. Other important side effects related to CsA-based immunosuppression include hypertension, diabetes, and hyperlipidemia. Optimal management of these conditions may lead to significant reduction of cardiovascular-related morbidity and mortality following solid organ transplantation.

Atlantic Islands↗