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Biomedical subjects

V Alvarez

Publications and source records attributed to V Alvarez.

At least 19 recordsLinked to original sources
PubMed2006

LRRK2 mutations are a common cause of Parkinson's disease in Spain.

Pathogenic mutations in the leucine-rich repeat kinase 2 gene (LRRK2; PARK8) have been implicated in autosomal dominant, late-onset parkinsonism. The LRRK2 6055G > A (G2019S) mutation is the most common reported to date, and has been observed in a number of different European populations. So far, only the LRRK2 4321C > G (R1441G) mutation has been identified in the Spanish population. Herein we have assessed the frequency of G2019S in a referral-based series of 225 patients with Parkinson's disease (PD) from the region of Asturias, Northern Spain. The mutant allele was identified in five (2.7%) of the sporadic late-onset patients and was not present in control subjects. All carriers displayed genetic profiles consistent with the same haplotype, as previously reported for Lrrk2 G2019S-positive subjects. None of these patients presented with a family history of parkinsonism at the time of diagnosis. Thus, approximately 5% of sporadic patients with PD from the North of Spain have either Lrrk2 G2019S or R1441G substitutions.

Aged↗
PubMed2006

A new de novo Notch3 mutation causing CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is one of the most common hereditary forms of stroke, and migraine with aura, mood disorders, or dementia, are also frequently found in these patients. Missense mutations in the Notch3 gene that create or destroy cysteine residues, have been found in most cases with a family history of the disease, although a few sporadic cases harbouring Notch3 mutations have also been described. Here, we describe a 44-year-old patient with clinical features of CADASIL who was a carrier of a new Notch3 mutation: cys128-->gly. Both parents were alive and healthy, and negative for the mutation. This case illustrates the interest of analysing the Notch3 gene in cases with clinical features of CADASIL, even in the absence of a family history of the disease.

Adult↗
PubMed2005

PCR detection of colostrum-associated Maedi-Visna virus (MVV) infection and relationship with ELISA-antibody status in lambs.

A recent large-scale experimental study showed that bottle-feeding ovine colostrum from seropositive ewes results in high MVV-seroconversion in lambs. In contrast, relatively few lambs that naturally suckled colostrum from seropositive dams seroconverted as a result of it. Furthermore, lambs fed uninfected bovine colostrum readily seroconverted when mixed with ovine-colostrum lambs indicating that horizontal MVV transmission between lambs was efficient. MVV-infection was further investigated in the same samples using two PCR tests targeting sequences in the long-terminal repeats (LTR) and POL MVV genes. PCR-tests confirmed previous serological findings. However, the LTR-PCR was more sensitive and allowed detecting infection earlier than the other tests, including 5-8% of new-born lambs from seropositive dams, providing more evidence that prenatal MVV-infection may be more important than considered. The degree of agreement between PCR and antibody tests in individual samples was low up to 6 months of age and moderate at 10 months-old. Nine percent of lambs were always PCR-negative but seroconverted and 19% of lambs were PCR-positive at least once and did not seroconvert. However, seroconversion was associated with increasing number of times lambs were PCR-positive and ovine colostrum-fed lambs were more frequently PCR-positive than other lambs. The significance of these findings in terms of MVV-infection, epidemiology and control is discussed.

Aging↗
PubMed2005

Horizontal Maedi-Visna virus (MVV) infection in adult dairy-sheep raised under varying MVV-infection pressures investigated by ELISA and PCR.

A three year long experimental study was carried out to investigate horizontal MVV-infection by PCR and ELISA, in 191 one year-old latxa dairy-sheep raised in two separate groups under low and high MVV-infection pressure, respectively. Sheep originated from a previous MVV-transmission study in lambs and seroprevalence among one year-old sheep in both groups was 15% approximately. The high infection-pressure group (H-group) consisted of 147 replacement ewes that joined a milk-producing, housed dairy-flock with 42-66% MVV-seroprevalence and the low infection-pressure group (L-group) were castrated males raised in a separate shed. In contrast to results obtained when infection was investigated in lambs, the overall degree of agreement between ELISA and PCR results was very good and there was some indication that it increased further as sheep became older. MVV-prevalence did not change in the L-group and increased to 57% in three year-old sheep in the H-group (p<0.001). Random effects logistic regression confirmed seroconversion was significantly higher in the H-group compared to the L-group and was highest during the year after the sheep were introduced in the dairy flock and did not increase with age as in previous studies using less sensitive antibody assays. The evidence that horizontal transmission can be very low in spite of prolonged close contact between infected and non-infected sheep is valuable for MVV-control purposes. Furthermore it highlights the need to investigate virus excretion dynamics in infected animals and animal to animal transmission to improve our overall understanding of horizontal MVV transmission in MVV endemic populations.

Aging↗
PubMed2005

The Pro279Leu variant in the transcription factor MEF2A is associated with myocardial infarction.

BACKGROUND: A myocyte enhancer factor 2A (MEF2A) mutation that segregated with coronary artery disease/myocardial infarction (CAD/MI) in a large family has recently been described. Missense mutations in sporadic coronary artery disease patients were also reported. These data suggest that mutations in exons 7 and 11 of MEF2A cause CAD/MI, though the association was refuted by another study. OBJECTIVE: To analyse the genetic variation of exons 7 and 11 in a large cohort of Spanish CAD/MI patients and controls. METHODS AND RESULTS: A rare polymorphism, P279L, was detected both in patients and controls. Carriers of the 279Leu allele had a threefold risk of suffering CAD/MI compared with controls (p = 0.009; odds ratio = 3.06 (95% confidence interval, 1.17 to 8.06)). In the controls the allele was found only in those under 50 years of age. Exon 11 showed a high degree of heterogeneity caused by a polyglutamine (CAG)n polymorphism, but no significant differences in genotype or allelic frequencies were found. CONCLUSIONS: The 279Leu allele appears to be a genetic risk factor for CAD/MI in the population studied. This effect could be the result of a reduced transcriptional activity on MEF2A with 279Leu.

Alleles↗
PubMed2005

[Pharmacogenetics of angiotensin system in non diabetic nephropathy].

BACKGROUND: Genetic variability could contribute to the response to pharmacological treatment in patients with nephropathy. In albuminuric diabetic patients the renoprotective effect of angiotensin I-converting enzyme (ACE) inhibition should be lower among homozygotes for the deletion allele (DD) compared to II-homozygotes. METHODS: A total of 71 non-diabetic chronic nephropathy patients were treated with losartan (n = 37) or amlodipine (n = 34). Blood pressure and proteinuria were determined before and after the treatment, and changes in the mean values were statistically compared. Patients were genotyped for the ACE-I/D, angiotensin I receptor type 1 (AGTR1)-1166 A/C, and angiotensinogen (AGT)-M235T polymorphims, and the reduction of blood pressure and proteinuria between the different genotypes were compared. RESULTS: The reduction in systolic or diastolic blood pressure was not found to be different between the ACE-I/D or AGT-M/T genotypes in patients treated with losartan or amlodipine. In patients treated with losartan, we found a significantly higher reduction of diastolic blood pressure in AGTR1-AA patients compared to AC patients (p = 0,0024). We did not find differences in proteinuria-reduction between the different genotypes in patients treated with losartan or amlodipine. CONCLUSIONS: Our data show that the effects of losartan and amlodipine on the absolute mean reduction of blood pressure and proteinuria in non-diabetic nephropathy patients are similar between the different ACE or AGT genotypes. Although based on a small number of patients, the AGTR1-AA genotype was associated with a significantly higher reduction in diastolic blood pressure among losartan-treated patients. Additional studies are necessary to refute or confirm this association.

Adult↗
PubMed2004

Relative contribution of colostrum from Maedi-Visna virus (MVV) infected ewes to MVV-seroprevalence in lambs.

Maedi-visna virus (MVV) seroprevalence associated with consumption of colostrum from seropositive ewes was investigated in 276 housed lambs from birth to 300 days-old. At birth, lambs were allocated to five experimental groups according to the maternal MVV-serological status, source and mode of feeding colostrum (bovine or ovine and bottle fed or suckled from the dam) and type of horizontal MVV-exposure (raised with the dam or separately with other lambs). The risk of being seropositive at 300 days-old was associated with feeding ovine colostrum from seropositive ewes and increased with intake of bottle-fed ovine colostrum and was higher in lambs separated from their dams and raised with other experimental lambs compared to lambs raised with their dams. Approximately 75-87% of ELISA-positive results in lambs that had ovine colostrum was attributable to colostrum itself. However, approximately only 16% of naturally raised and 29-61% of bottle-fed ovine colostrum lambs were ELISA-positive as a result feeding ovine colostrum. These results confirm that ovine colostrum from seropositive ewes can be a major source of MVV but its overall contribution to seroprevalence in natural conditions is relatively low, and shows that horizontal MVV transmission can be an important source of infection in new-born lambs.

Aging↗
PubMed2004

The reference change value: a proposal to interpret laboratory reports in serial testing based on biological variation.

BACKGROUND: A proposal to calculate and use the reference change value (RCV) as an objective guide for interpreting the numerical results obtained in clinical laboratory serial testing is introduced in this study. METHODS: A database showing the results of a compilation of 191 publications on biological variation and including information on a number of analytes provided the standardized criterion based on biology for calculating the RCVs. RESULTS: For each of the 261 analytes included in the study, the RCV was determined using Harris's formula, replacing analytical imprecision with the desirable specification of analytical quality based on half the within-subject biological variation at 95% probability levels. The result is a guide for a common criterion to identify clinically significant changes in serial results. CONCLUSIONS: The RCV concept is an approach that can be offered by laboratories to assess changes in serial results. The RCV data in this study are presented as a point of departure for a widely applicable objective guide to interpret changes in serial results.

Algorithms↗
PubMed2003

Differential effect of fetal, neonatal and treatment variables on neurodevelopment in infants with congenital hypothyroidism.

OBJECTIVES: To identify the influence of fetal, neonatal and treatment variables on neurodevelopment in children with congenital hypothyroidism. METHODS: A multiple regression analysis was performed in the neurodevelopmental scores of 26 children with CH who were assessed at 3, 6, 12 and 18 months for postural control, fine eye-hand coordination and language. The independent variables were: duration of fetal hypothyroidism, initial biochemical severity, days at starting treatment, initial dose, and efficiency of treatment. RESULTS: Postural control was predicted by duration of fetal hypothyroidism and language by the biochemical severity of the disease at birth. Fine eye-hand coordination was not predicted by any variable. CONCLUSION: This pattern of influences suggests that fetal and neonatal hypothyroidism have different effects on brain maturation sites during the first 2 years of life and that some subtle neurocognitive deficits are probably unavoidable.

Child Development↗
PubMed2003

Influence of anticalcineurinic therapy in plasma homocysteine levels of renal transplant recipients: a prospective study.

Hyperhomocysteinemia is an independent factor for cardiovascular disease. Renal function and folate level are important determinants of total plasma homocysteine levels. The influence of anticalcineurin drugs on homocysteine levels is controversial. The aims of the study were: (1) to analyze changes in homocysteine levels after the first year of 73 renal transplants and (2) to determine the influence of immunosuppressive anticalcineurin drug therapy on fasting homocysteine concentrations. We examined homocysteine, serum creatinine, folate, and vitamin B12 concentrations immediately after transplant, at 6 months, and after 12 months from renal transplant. Also, MTHFRC677T polymorphism was investigated. Tacrolimus was administered in 28 patients and cyclosporine in 45. Homocysteine levels decreased from 28.41+/-13.71 micromol/L to 18.59+/-8.31 micromol/L after 6 months and to 17.13+/-7.06 micromol/L after 1 year. No relationship was found between homocysteine and folate levels. When anticalcineurin drugs were considered, the homocysteine levels in patients treated with tacrolimus was lower than that in patients treated with cyclosporine at month 6 after transplant (16+/-7.4 micromol/L vs 20.1+/-8.5 micromol/L, P=.03) and after 1 year (15+/-7.6 micromol/L vs 18.4+/-6.4 micromol/L, P=.04). Serum creatinine levels followed the same evolution: they were lower in patients treated with tacrolimus at 6 months (1.35+/-0.36 mg/dL vs 1.57+/-0.45 mg/dL, P=.03) and to a lesser extent at 1 year after renal transplant (1.38+/-0.35 mg/dL vs 1.54+/-0.45 mg/dL, P=.09). The homocysteine value closely related with serum creatinine in both groups. In conclusion, 1 year posttransplant, the homocysteine level was lower among patients treated with tacrolimus, the cohort that also showed the lower serum creatinine concentrations.

Adult↗
PubMed2003

[Influence of different pharmacological agents in the ex vivo proliferation of mesothelial cells obtained from the peritoneal effluent of patients treated with peritoneal dialysis].

UNLABELLED: Mesothelial cells (MC) are the first peritoneal membrane barrier in contact with dialysate. The aim of this study was to analyze the in vitro capacity of different pharmacological agents to modify the ex vivo proliferation of MC obtained from the peritoneal effluent of patients treated with peritoneal dialysis (PD). MATERIAL AND METHODS: Thirty cultures of MC taken from nocturnal peritoneal effluent were performed. After identification, MC are subcultured in 24 multi-well plates, adding the different exogenous agents. Proliferative capacity and cell morphology were estimated on day 16th of culture. The agents evaluated were insulin, IGF-1, tamoxifen, labetalol, carvedilol, enalapril and losartan. RESULTS: Insulin shows a dose-dependent effect on MC growth, with a limit that is stimulated by the addition of fetal bovine serum (FBS). Concentrations higher than 100 micrograms/ml, are not associated with further growth, even with cell damage. In contrast, the wide range of IGF-1 dose used did not affect to MC proliferation. Tamoxifen causes negative effects on MC growth just a very high doses, not resembling doses in clinical practice. Labetalol does not modify MC proliferation used under therapeutic calculated range. However, concentrations higher than 40 micrograms/ml showed a negative influence on growth, behaving as lethal doses that over 100 micrograms/ml. The addition of FBS attenuates this effect. These effects were very similar to that caused by carvedilol addition. Enalapril and losartan act as antiproliferative agents for MC. This effect is potentiated with angiotensin II, reaching lethal concentrations increasing the dose. In conclusion, mesothelial cell growth ex vivo taken from nocturnal peritoneal effluent on PD patients is an useful tool to explore the effects of any pharmacological agent on the biology of the cell of the peritoneum. The agents used had any influence in the proliferation capacity of mesothelial cells.

Ascitic Fluid↗
PubMed2003

[Relative frequency of Boophilus microplus (Acari: Ixodidae) in bovines (Bos taurus and B. indicus) in 8 ecological zones of Costa Rica].

The research on the relative abundancy of Boophilus microplus took place in ten farms, distributed in eight ecological zones (EZ) and two rainfall systems of Costa Rica. Monthly visits were made to pick up ticks larger than 4 mm from the right side of the animals. The total number of ticks was increased by two and divided between the total of sampled bovines per farm. Farm visits were adjusted to animals bath to allow the recovery of the tick population. B. microplus was detected in all sampled farms throughout the year. Media comparison statistic analyses were made and no differences were found among EZ, farms and seasons. On the contrary, there were important statistical differences between rainfall systems. The rainfall system 1, that included rain seasonality, showed larger tick infestations (p = 0.03). An isothermal and low variability regarding relative humidity situations were present in some of the areas included in this research. Bath intensity was lower to other past studies. Even though no differences were found between production systems, it is important to emphasize that bath intensity was higher in european cattle farms, in comparison to others of the same EZ, but of crossbred. A tick manual removable system was recommended in dual-purpose and specialized dairy farms with no more than 30-35 animals, as an alternative feasible system that significantly reduced acaricide use.

Animals↗
PubMed2003

[Relative abundance of Amblyomma spp. (Acari: Ixodidae) in bovines (Bos taurus and B. indicus) from Costa Rica].

The research describe the big amount of ticks of the Amblyomma genus, found on bovines through monthly samplings carried out in ten farms in eight ecological zones (EZ) of Costa Rica. Ticks larger than 4 mm were picked up from the right side of the animals during the visit. The study compiled meteorological information for some farms located in the experiment, showing that the most fluctuant variable is rainfall. The most important Amblyomma species found was A. cajennense. Amblyomma nymphs were found only from January to May, which coincides with the lower humidity season in the rain seasonality area; as for it is expected only one generation per year. In the lab work Amblyomma nymphs are kept to measure the moulting season and the surviving time under controlled conditions, but no major differences were found between both sexes. The surviving periods show that it is not possible to do a grazing land handling, in order to control this genus species. Adults of the genus Amblyomma are present through all the year, not showing any specific preference for a season. The research divided the investigation areas in rain seasonability and not-seasonality systems. The highest amount of Amblyomma is found given in the rain seasonality system or of pacific influence. A. maculatum is present only in the EZ of Tropical Humid Forest transition to pre-mountainous. Likewise, Ixodes boliviensis is found in the EZ of low mountainous Very Humid Forest.

Animals↗