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Biomedical subjects

A Valdes

Publications and source records attributed to A Valdes.

10 recordsLinked to original sources
PubMed2006

Hepatitis B virus genotypes and G1896A precore mutation in 486 Spanish patients with acute and chronic HBV infection.

This study aims to determine the prevalence of hepatitis B virus (HBV) genotypes (A-F) and their association with the G1896A precore mutation in 486 patients positive for HBV surface antigen. Genotypes were determined by RFLP and precore mutation by real-time PCR. Genotypes D (48.1%) and A (39.5%) were the most common, followed by F (4.1%) and B, C and E (<1%). The A to D ratio (A:D) was 1.4 in HBeAg+ chronic hepatitis B (CHB), 0.6 in HBeAg- CHB and 1.4 in HBeAg- inactive carriers. Distribution of these genotypes was different between HBeAg+ CHB and HBeAg- CHB (P = 0.02), and between HBeAg- CHB and HBeAg- inactive carriers (P = 0.009). Genotype A was the most prevalent in HBeAg+ CHB with elevated alanine aminotransferase (ALT) (68.6%) and genotype D in HBeAg+ CHB with fluctuating ALT (60.7%). There was a difference in genotype prevalence between chronic and acute infection (P = 0.03). The precore mutant correlated with high levels of HBV-DNA in genotype d HBeAg- CHB. Genotype D is not as highly prevalent in Spanish patients as would be expected in a Mediterranean area. The unequal prevalence of genotypes between acute and chronic infection suggests that genotype A is associated with a higher tendency to cause chronic infection.

Adolescent↗
PubMed2005

Changes in different regions of hepatitis B virus gene in hepatitis B 'e' antigen-negative patients with chronic hepatitis B: the effect of long-term lamivudine therapy.

BACKGROUND: Lamivudine therapy for chronic hepatitis B has been associated with changes in different regions of the hepatitis B virus nucleotide sequence. AIM: To study changes in the sequences of polymerase and precore/core promoter regions of hepatitis B virus, before and during 5 years of therapy with lamivudine. METHODS: Eighty consecutive samples were taken from 10 chronic hepatitis B 'e' antigen-negative patients. RESULTS: Nine patients carried hepatitis B virus precore mutations during the study. Before therapy, wild type was replaced by A1896 in two (20%) cases. During treatment, A1896 reverted transitory to wild type in five cases (50%) and in one case wild type was replaced by A1896. The continuous detection of precore mutations during therapy was associated with a lower response rate. YMDD mutations were observed in nine cases and both, L180M and M204V/I mutations were simultaneously detected in six cases. About 75% of the patients with M204V mutations were responders and none with M204I or mixed pattern sustained response. CONCLUSION: Hepatitis B 'e' antigen-negative patients exhibit changes in the precore regions both spontaneously and under lamivudine therapy, the transitory reversion to wild type being most frequently witnessed. Patients carrying M204V mutations are more likely to respond to therapy. If, in further studies, these results are confirmed some patients with YMDD mutations could benefit from prolonging the duration of lamivudine therapy.

Adult↗
PubMed2001

Quantitative detection of hepatitis B virus DNA in serum by a new rapid real-time fluorescence PCR assay.

A sensitive and accurate HBV DNA quantification assay is essential for monitoring hepatitis B virus (HBV) replication. This study evaluated a real-time PCR method performed in the LightCycler analyser for quantitative HBV DNA assay. HBV DNA results with this method were compared with those obtained using a branched-chain DNA (bDNA) solution hybridization assay. Real-time PCR was performed using two adjacent fluorescently labelled probes and primers corresponding to the HBV core gene. The same standard employed in the bDNA assay was used for calibration. Serum samples came from 193 HBV surface antigen (HBsAg)-positive patients (34 HBV e antigen (HBeAg)-positive and 93 with antibody to HBeAg (anti-HBe)), and 66 asymptomatic HBV carriers. In addition, we analysed serum samples from 8 anti-HBe-positive patients who had been receiving lamivudine treatment for more than three years. A linear standard curve was seen in the range from 10(3) to 10(8) copies/mL. In the reproducibility analysis, intra-assay coefficient of variation (CVs) at two known HBV DNA concentrations were 4% and 2% and interassay CVs were 6% and 4%. The median of serum HBV DNA by real-time PCR was 9.2 x 10(8) copies/mL in HBeAg-positive patients with persistently elevated alanine aminotransferase (ALT) levels, 1.3 x 10(7) copies/mL in anti-HBe-positive cases with persistently elevated ALT levels, 3.7 x 10(4) copies/mL in anti-HBe-positive patients with fluctuating ALT levels and 10(4) copies/mL in asymptomatic HBV carriers. The differences in HBV DNA levels among the various groups studied were statistically significant (P < 0.05). The cut-off between chronic hepatitis patients and asymptomatic carriers was found to be at a serum HBV DNA concentration of 5 x 10(4) copies/mL. Of the 109 serum samples with a viral load < 7.5 x 10(5) (negative by bDNA assay) 44 (40%) were positive by real-time PCR: 24 (56%) chronic hepatitis and 20 (33%) asymptomatic carriers. There was a positive association between HBV DNA levels determined by real-time PCR and ALT levels (P < 0.05), which was not observed with the bDNA assay for HBV DNA quantification. At 12 months of lamivudine treatment, 6 patients (75%) showed HBV DNA levels < 5 x 10(4) copies/mL (range < 10(3)-2 x 10(3)), significantly lower than at baseline. At 36 months, 2 of 8 (25%) showed HBV DNA levels persistently lower than 5 x 10(4) copies/mL (1.7 x 10(3), 6 x 10(3)). The LightCycler quantitative real-time PCR is a practical, sensitive, reproducible single-tube assay with a wide dynamic range of detection. The assay is automatic except for DNA extraction and the running time is only 70 min. The LightCycler real-time PCR is useful for identifying different states of HBV infection and for evaluating the efficacy of viral therapy.

DNA, Viral↗
PubMed1997

Use of glucagon for acute intravenous diltiazem toxicity.

Intravenous diltiazem has become a preferred medication for treating supraventricular tachyarrhythmias in hospitalized patients. We present a case of inadvertent acute overdosage, its clinical effects, and successful treatment using intravenous glucagon.

Acute Disease↗
PubMed1985

Inhibition of thromboxane synthesis ameliorates the progressive kidney disease of rats with subtotal renal ablation.

Ablation of greater than 70% of renal mass in the rat results in hypertension, proteinuria, and glomerular sclerosis of the remnant kidney. Rats with a remnant kidney have increased excretion of thromboxane in the urine when compared with normal rats. Chronic oral administration of OKY 1581, an inhibitor of thromboxane synthesis, in rats with a remnant kidney increases renal blood flow and glomerular filtration rate (GFR), decreases protein and thromboxane excretion in the urine, lowers blood pressure and cardiac index, and improves renal histology. The degree of hypertrophy of the remnant kidney was unaffected by administration of OKY 1581. Calculated values for single nephron plasma flow and GFR were significantly greater in rats with remnant kidneys given OKY 1581 than in rats given saline. Acute i.v. administration of OKY 1581 increased renal plasma flow and GFR in rats with a remnant kidney but not in normal rats or rats with a remnant kidney previously treated with acetylsalicyclic acid. OKY 1581 markedly inhibited platelet aggregation. We suggest that in this model of renal disease platelet aggregation and intraglomerular thrombosis play a key role in the development of glomerulosclerosis. Inhibition of platelet aggregation prevents development of glomerulosclerosis, hypertension, and cardiac hypertrophy. We suggest that hyperperfusion and hyperfiltration per se occurring in remnant glomeruli are not directly responsible for the development of glomerulosclerosis.

Acrylates↗
PubMed1985

Plasma vasopressin response to osmotic and hemodynamic stimuli in heart failure.

Arginine vasopressin (AVP) regulation was studied in 42 patients with severe heart failure (CHF) and 10 patients without CHF during cardiac catheterization. Plasma AVP levels were elevated in CHF compared with non-CHF patients (2.98 +/- 2.48 vs. 1.01 +/- 0.44 pg/ml, P less than 0.01). In non-CHF patients, osmotic loading with angiographic contrast caused increases in plasma osmolality (283 +/- 4 to 290 +/- 5 mosmol/l, P less than 0.05) and AVP (1.01 +/- 0.44 to 1.79 +/- 0.20 pg/ml, P less than 0.001). In 10 CHF patients, similar osmotic loading produced an increase in plasma osmolality (275 +/- 13 to 288 +/- 17 mosmol/l, P less than 0.05) and an exaggerated rise in plasma AVP (3.61 +/- 3.17 to 16.30 +/- 12.17 pg/ml, P less than 0.001). The increase in plasma AVP per unit increase in osmolality was greater (P less than 0.01) in the CHF patients (1.36 +/- 1.25 pg . mosmol-1 . 1(-1)) than in non-CHF patients (0.18 +/- 0.17). To determine whether improved cardiac performance would lower AVP levels, 18 CHF patients received the experimental agent MDL 17,043, with improved cardiac index (1.9 +/- 0.4 to 3.3 +/- 0.7 1 . min-1 . m-2, P less than 0.001). Plasma AVP levels did not change significantly (1.99 +/- 0.74 to 2.81 +/- 2.06 pg/ml), but significant inverse correlations were found between changes in plasma AVP and changes in mean (r = -0.53) and systolic (r = -0.65) arterial pressure after MDL 17,043 infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗