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Biomedical subjects

A Valenzuela

Publications and source records attributed to A Valenzuela.

At least 55 records · Page 3Linked to original sources
PubMed1996

Increasing DNA extraction yield from saliva stains with a modified Chelex method.

Recovery, preservation and analysis of body fluid stains is an important aspect of forensic science. PCR-based typing of DNA extracted from recovered stains is often a crucial method to identify a perpetrator or exclude an innocent suspect. This paper reports an improved method of extracting genomic DNA from saliva stains deposited on human skin in simulated bite mark situations. Results of organic (phenol-chloroform) extraction and Chelex extraction were compared to a modified Chelex method developed by the authors. Modifications include pre-extraction preparation with proteinase K and incubations at 56 degrees C and 100 degrees C plus microconcentration of the solution. Quantification results using the classical Chelex extraction method showed that 31.9 +/- 4.22% of the deposited DNA was recovered, but using the modified Chelex extraction method DNA recovery was increased to 47.7 +/- 6.90%. The quantity and quality of extracted DNA was shown to be adequate for PCR-based typing at two STR loci.

Bites and Stings↗
PubMed1996

Probing HLA-B7 conformational shifts induced by peptide-binding groove mutations and bound peptide with anti-HLA monoclonal antibodies.

To determine the influence of peptide-binding groove residues and MHC-bound peptide on HLA-B7 conformation, we investigated the binding sites of nine locus- or allele-specific mAbs using a panel of 82 HLA-B7 variants. The functional mAb epitopes encircle the HLA-B7 peptide-binding groove. Three mAbs are affected by mutations at solvent-accessible peptide-binding groove mutations. Mutations in peptide-binding groove residues 45, 63, and 150 affect multiple nonoverlapping mAb epitopes, probably by interaction with other MHC residues or bound peptide. However, 18 of 24 peptide-binding groove mutations do not affect mAb binding, indicating that the conformation of solvent-accessible HLA-B7 structures is largely dissociated from changes in the peptide-binding groove. To test whether bound peptides alter HLA-B7 conformation, we loaded HLA-B7 heavy chains on acid-stripped cells with beta2-microglobulin and 20 individual synthetic peptides. Two of eight mAbs are sensitive to HLA-B7-bound peptides. A likely interpretation of these data is that the conformational flexibility of HLA-B7 is due to peptide-induced conformational shifts in MHC side chains, rather than major shifts in the MHC main chain. These results suggest that HLA-B7 conformation is largely maintained in the context of different bound peptides and different peptide-binding grooves.

Antibodies, Monoclonal↗
PubMed1996

Cytoprotective and antioxidant effects of boldine on tert-butyl hydroperoxide-induced damage to isolated hepatocytes.

Boldine, an aporphine alkaloid, was recently shown by us to exhibit potent antioxidant properties. We report here that boldine concentration-dependently inhibited the peroxidative (accumulation of thiobarbituric acid reactive substances) and lytic damage (trypan blue exclusion and lactate dehydrogenase leakage) to isolated rat hepatocytes induced by tert-butyl hydroperoxide (TBOOH). Boldine (200 micromol/L) fully cytoprotected and completely prevented the peroxidation induced by TBOOH at concentrations equal to or lower than 0.87 mmol/L. However, at a peroxide concentration of 0.91 mmol/L, although boldine completely inhibited lipid peroxidation it largely failed to afford cytoprotection against TBOOH. TBOOH alone (0.83 mmol/L) caused an early (within 60 s) sudden decline of reduced glutathione (by 50%) and an equivalent increase in the levels of oxidized glutathione. Neither of these effects was prevented by the simultaneous addition of a cytoprotective and antioxidant concentration of boldine (200 micromol/L). The delayed addition of boldine to the suspension (after 10 or 20 min), while effectively blocking any further increase in thiobarbituric acid reactive substances, totally failed to prevent the peroxide-induced loss in cell viability. Conversely, preincubation of the hepatocytes with boldine for 150 min (at which time no boldine could be detected in either intra- or extracellular spaces) prevented lipid peroxidation and was as effective in protecting the cells against the damage caused by the subsequent addition of TBOOH as the simultaneous addition of boldine and TBOOH to hepatocytes preincubated for 150 min under control conditions.

Animals↗
PubMed1996

Association of the shared epitope with radiological severity of rheumatoid arthritis.

OBJECTIVE: To investigate the association between radiological severity of rheumatoid arthritis (RA) and the presence of the shared epitope. METHODS: Ninety unrelated adult Spanish patients with RA with a disease duration of at least 3 years, selected according to the American College of Rheumatology criteria, were radiologically assessed (shoulders, elbows, wrists, hands, hips, knees, and feet) and classified as having severe or nonsevere RA. DNA oligotyping was used to determine DR specificities and to detect DR4 and DR1 alleles. RESULTS: Forty-one patients (45.5%) had severe RA. Sixty-six patients (73.3%) carried the shared epitope and 18 (20%) had double expression of the shared epitope. Thirty-seven (90%) of the 41 patients with severe RA expressed the shared epitope. Logistic regression analysis showed that both single and double expression of the shared epitope were strongly related to the radiological severity of RA (odds ratio = 6.3 and 9.4, respectively). CONCLUSION: Our results show that radiological severity of RA is highly associated to the shared epitope.

Adult↗
PubMed1995

New seizure frequency QTL and the complex genetics of epilepsy in EL mice.

EL/Suz (EL) mice experience recurrent seizures that are similar to common partial complex epilepsy in humans. In the mice, seizures occur naturally at 90-100 days of age, but can be induced in younger mice and analyzed as a semi-quantitative trait after gentle rhythmic stimulation. A previous genetic mapping study of EL backcrosses to the strains ABP/LeJ or DBA/2J showed two quantitative trait loci (QTL) with large effects on seizure frequency (El1, Chr 9; El2, Chr 2) and implied the existence of other QTL with lesser effects. To further the understanding of EL-derived seizure alleles, we examined intercross progeny of EL and the strains ABP/LeJ and DDY/Jcl, and also a backcross of (EL x DDY)F1 hybrids to DDY. A new large-effect seizure frequency QTL was found (El5, Chr 14), a more minor QTL confirmed (El3, Chr 10), and two additional QTL proposed (El4, Chr 9; El6, Chr 11). The serotonin receptor gene, Htr2a, maps near and is a candidate for El5, and linkages of other serotonin receptor genes to seizure frequency QTL are noted. In addition, a strong gender effect was revealed, and epistasis was found between Chr 9 and Chr 14 markers. Despite this progress, however, our results revealed a more complex determinism of epilepsy in EL mice than previously described. In particular, no single El locus or pair was essential for frequent seizures, as QTL with large effects, such as El5, El2, and El1, were highly dependent on genetic context. Our studies highlight the importance of gene interaction in some complex mammalian traits defined by natural variation.

Animals↗
PubMed1995

Chromosome mapping of Rfv3, a host resistance gene to Friend murine retrovirus.

Inoculation of adult mice with Friend virus complex usually induces rapid viremia and erythroleukemia, resulting in death in 1 to 3 months. In certain mouse strains, a single host gene, Rfv3, controls the ability to mount a virus-specific neutralizing antibody response which results in elimination of viremia. In this study, microsatellite markers were used to localize the Rfv3 gene to a 20-centimorgan region of mouse chromosome 15 unlinked to immunoglobulin loci, T-cell receptor loci, or the major histocompatibility complex. Potential candidate genes for Rfv3 are several genes expressed in cells of the immune system and previously mapped to the same region, including a T-cell antigen gene, Ly6, and three cytokine receptor genes, IL2rb, IL3rb1, and IL3rb2.

Animals↗
PubMed1995

Relationship of blood rheology to lipoprotein profile during normal pregnancies and those with intrauterine growth retardation.

AIMS: The effects on fetal growth of hyperlipidaemia in pregnancy are not well understood at present. In this study the different lipid fractions in normal pregnancies and pregnancies complicated by intrauterine growth retardation (IUGR) were determined and related to changes in plasma and serum viscosity. METHODS: Two groups of pregnant women were studied. Group 1 consisted of 35 healthy pregnant women aged between 21 and 38 years with no previous pathology and a normal pregnancy to term. Group 1 patients were studied at four periods defined at the start of the study: (1) < or = 17 weeks; (2) 18-24 weeks; (3) 25-32 weeks, (4) > or = 33 weeks. Group 2 consisted of 24 pregnant women aged between 16 and 34 years with ultrasound diagnosed IUGR confirmed after birth. Plasma lipids and plasma and serum viscosity were measured. RESULTS: Plasma triglycerides, low density lipoprotein cholesterol, and total cholesterol increased progressively throughout pregnancy, with significantly higher values after week 25. Apolipoprotein A (ApoA) and triglyceride concentrations were significantly lower in the IUGR group than in the normal group. The HDL/ApoA ratio was greater in the IUGR group than in the control group, as was the ApoB/ApoA ratio. There were no differences in the other lipids. Plasma and serum viscosity was higher in the IUGR group than in the normal group. CONCLUSIONS: Haemorheological modifications in the IUGR group are partly secondary to changes in high density lipoprotein metabolism and the competitive inhibition of fibrinolysis by ApoB, which is increased in pregnancies with IUGR. Changes in ApoA, and more specifically in the ApoB/ApoA ratio, could be good markers for the early detection of IUGR.

Adolescent↗
PubMed1994

Lipoproteins and apolipoproteins in pericardial fluid: new postmortem markers for coronary atherosclerosis.

Determinations of lipoproteins (HDL-cholesterol and LDL-cholesterol) and various apolipoproteins (Apo A-I, Lp(a) and Apo B-100) were performed in postmortem pericardial fluid. Studies were carried out on 77 cadavers: 41 adult subjects with a morphological and biochemical diagnosis of intermediate or fresh myocardial infarction and 36 adults with no previous history of myocardial infarction. HDL and LDL were determined by enzymatic methods. Both apolipoproteins (A-I and B-100) were quantified by radio-immunoassay methods and Lp(a) was measured by enzyme immunoassay. Cases with severe atherosclerosis of coronary arteries showed higher levels of Apo B in pericardial fluid compared to cases without atherosclerosis. A significant increase of Apo B was found in cases with a positive diagnosis of myocardial infarction. Due to the high level of Apo B in pericardial fluid, a decrease in the LDL/Apo B ratio, along with a pronounced increase in the Apo B/Apo A ratio, was detected. The determination of Apo B in pericardial fluid can be a useful parameter to be included in biochemical analysis for the postmortem diagnosis of myocardial infarction related to coronary atherosclerosis.

Apolipoproteins A↗
PubMed1994

Anti-inflammatory and antipyretic effects of boldine.

Boldine, an antioxidant alkaloid isolated from Peumus boldus, exhibits a dose-dependent anti-inflammatory activity in the carrageenan-induced guinea pig paw edema test with an oral ED50 of 34 mg/kg. Boldine also reduces bacterial pyrogen-induced hyperthermia in rabbits to an extent which varied between 51% and 98% at a dose of 60 mg/kg p.o. In vitro studies carried out in rat aortal rings revealed that boldine is an effective inhibitor of prostaglandin biosynthesis, promoting 53% inhibition at 75 microM. The latter in vitro effect may be mechanistically linked to the anti-inflammatory and antipyretic effects of boldine exerted in vivo.

Animals↗
PubMed1994

Lymphocyte subpopulations in patients with primary fibromyalgia.

OBJECTIVE: Fibromyalgia (FM) is a clinical entity of unknown etiology frequently diagnosed in rheumatology. The potential involvement of the immune system in its pathogenesis has been suggested. Studies of abnormal T cell subpopulations often have been inconclusive. We attempted to clear this point by comparing lymphocyte subpopulations, including some of the newer activation markers, in patients with FM and healthy controls. METHODS: Sixty-five patients with FM and 56 healthy controls were studied. Flow cytometry was used as a quantification technique to measure lymphocyte subpopulations, CD3 (T cells), CD19 (B cells), CD16 (natural killer cells), CD4 (T helper/inducer cells), CD8 (T cytotoxic/suppressor cell), CD25 (interleukin 2 receptor), CD69 (activation inducer molecule marker), CD71 (transferrin receptor) and CD54 (ICAM-1); CD4/CD8 ratios were also estimated. RESULTS: The number of T cells expressing activation markers CD69 and CD25 was decreased in patients with FM; the other subpopulations were similar in patients and controls. CONCLUSION: Our results suggest a defect in T cell activation in patients with FM.

Adolescent↗
PubMed1994

[Variability of measured energy expenditure in patients with acute pancreatitis: is it possible to obtain a reliable pathology factor for these cases?].

Energy expenditure was measured in 55 patients with acute pancreatitis, during variable periods ranging from 1 to 5 weeks and it was compared with estimated energy expenditure according to Harris Benedict equations. Patients with severe pancreatitis had similar measured and measured/estimated energy expenditure rations, compared to those with mild pancreatitis (1678 +/- 349.6 kcal/day and 1.1 +/- 0.19 vs 1632 +/- 383 kcal/day and 1.06 +/- 0.19). There was a high dispersion of measured/estimated rations (0.67 - 1.7) that precluded the calculation of a reliable energy expenditure correction factor for this disease. It is concluded that energy expenditure must be measured and not estimated, when planning an adequate nutritional support in patients with acute pancreatitis.

Acute Disease↗
PubMed1994

Biochemical bases of the pharmacological action of the flavonoid silymarin and of its structural isomer silibinin.

The flavonoid silymarin and one its structural components, silibinin, have been well characterized as hepato-protective substances. However, little is known about the biochemical mechanisms of action of these substances. This review deals with recent investigations to elucidate the molecular action of the flavonoid. Three levels of action have been proposed for silymarin in experimental animals: a) as an antioxidant, by scavenging prooxidant free radicals and by increasing the intracellular concentration of the tripeptide glutathione; b) regulatory action of the cellular membrane permeability and increase of its stability against xenobiotic injury; c) at the nuclear expression, by increasing the synthesis of ribosomal RNA by stimulating DNA polymerase I and by exerting a steroid-like regulatory action on DNA transcription. The specific hepatoprotective action of silibinin against the toxicity of ethanol, phenylhydrazine and acetaminophen is also discussed. It is suggested that the biochemical effects observed for the flavonoid in experimental models may settle the basis for understanding the pharmacological action of silymarin and silibinin.

Animals↗
PubMed1994

[Technological innovation applicable to marine oils rich in n-3 fatty acids to allow their nutritional and pharmacological use: a challenge for the present decade].

The important physiological properties described for marine oils rich in n-3 polyunsaturated fatty acids have give rise to increasing efforts to develop procedures for obtaining, preserve and concentrate these oils aiming its nutritional and pharmacological use. The fish meal industry provides high quantities of fish oil, however this oil being not suitable for human consumption must be subjected to different refining procedures to allow its use for feeding purposes. This review describes the current research about the employment of different procedures to incorporate n-3 polyunsaturated fatty acid to our feeding. The feasibility for the application of chemical methods and stereospecific enzyme-transesterification procedures for obtaining oil concentrates, and the use of natural substances for stabilizing the oil against oxidation are discussed. The possibility that some birds such as the chicken, feeding a diet rich in n-3 polyunsaturated fatty acids, as a healthy, safe and suitable vehicle to provide these fatty acid for human nutrition is also discussed.

Adult↗
PubMed1993

Determination of boldine in plasma by high-performance liquid chromatography.

A sensitive method for the determination of boldine in blood plasma is described. The procedure involves a direct pH-buffered chloroform extraction of boldine from blood plasma, followed by its assay under isocratic conditions by HPLC with UV detection. The extraction recovery is excellent, and sensitivity and precision of the method are very high, when applied to plasma samples containing pharmacologically relevant concentrations of boldine.

Animals↗
PubMed1993

Paraoxonase activity in human pericardial fluid: its relationship to coronary artery disease.

Pericardial fluid paraoxonase activity was compared with 3 biochemical markers of atherosclerosis (HDL, LDL/HDL ratio and Apolipoprotein A-I) and a significant association was found. When the paraoxonase activity in pericardial fluid samples was separated into 2 groups according to the degree of coronary atherosclerosis (slight and severe), most of the cases showing low levels of paraoxonase activity also showed severe coronary atherosclerosis. In addition, paraoxonase activity in pericardial fluid was found to be statistically correlated with HDL levels, which agrees with the results reported in serum.

Apolipoprotein A-I↗
PubMed1993

Characterization of paraoxonase activity in pericardial fluid: usefulness as a marker of coronary disease.

In this study, the presence of paraoxonase activity in pericardial fluid was demonstrated. A comparison of some properties, such as optimum pH, stability versus pH, heat inactivation, effect of inhibitors, isoelectric point and kinetic parameters (Km and Vmax), between plasma and pericardial fluid paraoxonase was made. The properties studied were practically identical. The enzyme activity in pericardial fluid was tested as a marker in the postmortem diagnosis of myocardial infarction. The paraoxonase activity in the myocardial infarction group (47 cases) was lower than in the control group (40 cases), but the difference was not significant.

Aryldialkylphosphatase↗