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Biomedical subjects

R Calvet

Publications and source records attributed to R Calvet.

15 recordsLinked to original sources
PubMed2001

Sorption of weak organic acids in soils: clofencet, 2,4-D and salicylic acid.

The sorption behaviour of a new wheat hybridising agent (clofencet, 2-4-(chlorophenyl)-3-ethyl-2,5-dihydro-5-oxopyridazine-4-carboxylic acid) was investigated in batch equilibrium experiments and compared to that of two other organic acids (2,4-D and salicylic acid). Sorption coefficients Kd for the three compounds were determined in 18 Cambisols and Ferralsols. Kd values for clofencet were 0.3-9.4 l/kg for Cambisols and 2.1-68 l/kg for Ferralsols. Sorption of clofencet was strongly related statistically to that of salicylic acid. Sorption of clofencet and salicylic acid decreased exponentially with increasing solution pH in Cambisols whereas a bell-shaped curve was obtained for the sorption of salicylic acid in Ferralsols. Sorption of 2,4-D (2,4-dichlorophenoxyacetic acid) was not statistically related to the pH of the different soils. Positively charged oxide surfaces were shown to play a significant role in the sorption of clofencet and salicylic acid. The use of simple correlation and multiple linear regressions suggested that the main sorption mechanisms of clofencet in soils were likely to be ligand exchange on oxide surfaces and, to a lesser extent, cation bridging. Differences in the sorption behaviour of clofencet/salicylic acid and 2,4-D might be attributed to the possibility of the two former compounds forming bidentate complexes with metals.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2001

Accidental dichloromethane fatality: a case report.

A case of accidental dichloromethane poisoning by inhalation is presented. It is of interest that carboxyhemoglobin levels were within the normal range, suggesting that the narcosis and respiratory depression were due to the direct effect of DCM on the central nervous system. The accidental death was attributed to improper ventilation of vapors in the working area.

Adult↗
PubMed2000

Allelic frequencies for the HLA-DQA1, D1S80, HUMTHO1, HUMTPOX, HUMCSF1PO and HUMVWA loci in Cantabria (middle north Spain).

Allele frequencies for six DNA polymorphisms have been studied in a population sample from Cantabria (middle north Spain) using the polymerase chain reaction. The HLA-DQA1 locus was analyzed by the reverse dot-blot technique and the other five by polyacrylamide gel electrophoresis followed by silver staining. Six alleles were found for HLA-DQA1. 15 alleles for D1S80, 6 alleles for HUMTHO1 and HUMCSF1PO, 7 for HUMTPOX and 8 alleles for HUMVWA. The 21 repeat allele in HUMVWA had not previously been reported in a Spanish population. The genotype distributions met Hardy-Weinberg expectations for all the systems and some statistical parameters of forensic interest were calculated. Comparisons with other populations revealed significant differences for HLA-DQA1, HUMVWA and HUMTHO1, with interracial differences being more pronounced than between Spanish populations. The HUMVWA system showed the highest forensic efficiency of the six polymorphisms studied.

Alleles↗
PubMed2000

Hydrocephalus: a fatal late consequence of mumps encephalitis.

Common and usually self-limited diseases may occasionally have fatal consequences. Hydrocephalus is a very rare complication of mumps, with just a few cases reported in the literature. Here we report a fatal case of hydrocephalus presenting 19 years after mumps encephalitis. The long latency period between encephalitis and hydrocephalus-associated symptoms makes this case particularly interesting.

Adult↗
PubMed1997

A review of the collaborative exercises on DNA typing of the Spanish and Portuguese ISFH Working Group. International Society for Forensic Haemogenetics.

Since 1992 the Spanish and Portuguese Working Group (GEP) of the International Society for Forensic Haemogenetics (ISFH) has been organizing collaborative exercises on DNA profiling with the aim of making progress on standardization and discussing technical and statistical problems in DNA analysis. A total of four exercises (GEP-92 to GEP-95) have been carried out until now. A consequence of these exercises was the creation of a quality control programme in Spain and Portugal in 1995 which was carried out simultaneously with the GEP-95 exercise. The number of participating laboratories increased from 10 in the first exercise (GEP-92) to 19 in the last exercise (GEP-95). Despite this increasing number of participating laboratories, results remained satisfactory. In the last exercises, all the laboratories used PCR-based DNA polymorphisms with an increasing number of markers obtaining good results. SLPs were used by only 30% of laboratories in the last two exercises but the results indicated a good level of expertise in most of these laboratories. The reasons for these successful results are the common use of the EDNAP protocol for SLP analysis and commercially available kits or common sequenced allelic ladders for PCR-based DNA polymorphisms.

Blood Stains↗
PubMed1995

PGM1 subtypes in Cantabria (middle N Spain).

A sample of 500 unrelated individuals from Cantabria (middle north Spain) has been studied for red cell Phosphoglucomutase (PGM1) using isoelectric focusing in polyacrylamide. The allele frequencies observed were: PGM1*1 +: 0.643, PGM1*1-: 0.121, PGM1*2 +: 0.195, PGM1*2-: 0.041 and are similar to those reported for other European and Spanish populations. The theoretical exclusion rate in cases of disputed paternity is 30.24%.

Adult↗
PubMed1992

Blood groups of the Cantabrian population (Spain).

The genetic polymorphism of eight red cell antigenic systems was examined in two population samples from Cantabria (north Spain). No significant differences were found between the autochthonous and the resident populations. The results obtained are compared with those for other populations in the north of Spain. The low frequency of the B allele of the AB0 system and the high frequency of the 'cde' haplotype of the Rh system in the Cantabrain and Asturian population suggests that the anthropological characteristics of these two systems, which hitherto have been attributed to the Basques, also apply to the western neighbouring regions.

Blood Group Antigens↗
PubMed1992

An unusual fatal case of accidental asphyxia in a child.

The death of a three-year-old child by asphyctic mechanism is described. The child was accidentally suspended by the neck from a half-opened car window. This report details the form in which the accident occurred. The influence of the type of window and the autopsy findings.

Accidents, Home↗
PubMed1991

HLA phenotype and haplotype frequencies in the Cantabria (middle north Spain) population.

The gene and haplotype frequencies of the HLA-A and -B locus antigens were determined in 502 unrelated individuals from Cantabria (middle North Spain). Our results were compared with those reported for other European and Spanish populations. The haplotypes with significant linkage disequilibrium were also analyzed in various Spanish population samples in order to establish possible relationships with geographic situation and historical events.

Gene Frequency↗
PubMed1990

Opiates depress ACh and ATP release from cholinergic synaptosomes by blocking calcium uptake.

We have studied the effects of opiates on ATP and acetylcholine (ACh) release from cholinergic nerve terminals isolated from the electric organ of Torpedo marmorata. The release of ATP was inhibited by morphine and this action was reversed by naloxone. Morphine, [D-Met2-Pro5]enkephalinamide and [D-Ala2-Leu5]enkephalin also inhibited acetylcholine release. Naloxone prevented these inhibitory effects. The action of enkephalin on ACh release was less effective than that of morphine. The calcium uptake by nerve terminals of Torpedo electric organ was also inhibited by morphine, either under resting or depolarizing conditions, and this effect was reversed by naloxone. Using the quick freeze-fracture method, the structural changes induced by morphine in the presynaptic membrane were also studied. Morphine prevents the rearrangement of intramembrane particles (IMPs) at both freeze-fractured faces of the synaptosomal presynaptic membrane after depolarization. It is concluded that opiates depress the ATP and the ACh releases from cholinergic synaptosomes by inhibiting the calcium uptake by the nerve terminals and the rearrangement of the IMPs after potassium-induced depolarization. Furthermore, ACh release, but not ATP release, seems to be related with the rearrangement of IMPs in the presynaptic membrane.

Acetylcholine↗
PubMed1989

Adsorption of organic chemicals in soils.

This paper presents a review on adsorption of organic chemicals on soils sediments and their constituents. The first part of this review deals with adsorption from gas and liquid phases and gives a discussion on the physical meaning of the shape of adsorption isotherms. Results show that no general rules can be proposed to describe univocally the relation between the shape of isotherms and the nature of adsorbate-adsorbent system. Kinetics of adsorption is discussed through the description of various models. Theoretical developments exist both for the thermodynamics and the kinetics of adsorption, but there is a strong need for experimental results. Possible adsorption mechanisms are ion exchange, interaction with metallic cations, hydrogen bonds, charge transfers, and London-van der Waals dispersion forces/hydrophobic effect. However, direct proofs of a given mechanism are rare. Several factors influence adsorption behavior. Electronic structure of adsorbed molecules, properties of adsorbents, and characteristics of the liquid phase are discussed in relation to adsorption. Such properties as water solubility, organic carbon content of adsorbing materials, and the composition of the liquid phase are particularly important. Evaluation of adsorption can be obtained through either laboratory measurements or use of several correlations. Adsorption measurements must be interpreted, taking into account treatment of adsorbent materials, experimental conditions, and secondary phenomena such as degradations. Correlations between adsorption coefficients and water-octanol partition coefficient or water solubility are numerous. They may be useful tools for prediction purposes. Relations with transport, bioavailability, and degradation are described.

Adsorption↗
PubMed1987

Structural changes at pure cholinergic synaptosomes during the transmitter release induced by A-23187 in Torpedo marmorata. A freeze-fracture study.

Pure cholinergic synaptosomes isolated from the electric organ of Torpedo marmorata were stimulated by calcium ionophore A-23187. The effect of time course of stimulation on the changes in intramembrane particles (IMPs) on presynaptic membranes was studied by quick-freezing and aldehyde-fixation freeze-fracture. We showed that the decrease of small-particle density at the P-face and the increase of large-particle density at the E-face was maximum after 30 sec of A-23187 stimulation. Later, the density of synaptic vesicles decreased. We suggest that the redistribution of IMPs on the presynaptic membrane and acetylcholine (ACh) release from pure cholinergic synaptosomes have a similar time course when triggered by A-23187.

Acetylcholine↗