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Biomedical subjects

A Martín

Publications and source records attributed to A Martín.

At least 19 recordsLinked to original sources
PubMed2001

Reductive fragmentation of carbohydrate anomeric alkoxy radicals. Synthesis of alditols with potential utility as chiral synthons.

A series of anomeric nitrate esters and N-phthalimido glycosides of carbohydrates in furanose and pyranose forms have been synthesized in order to generate the corresponding alkoxy radicals and study the C1-C2 fragmentation reaction under reductive conditions. This reaction constitutes a two-step method for the transformation of carbohydrates into the corresponding alditols with one less carbon. Using this methodology, interesting four- and five-carbon building blocks for natural products synthesis possessing D-erythritol, D-threitol, D-xylitol, and D-arabinitol stereochemistry have been prepared. The synthesis of 1,2-O-isopropylidene-beta-L-threose (40) and 1-acetamido-2,4,5-tri-O-acetyl-D-arabinitol (50) have also been achieved from 1,2:5,6-di-O-isopropylidene-beta-D-glucofuranose and 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-D-glucopyranose, respectively.

Alcohols↗
PubMed2001

Immunisation with phage-displayed variable region 2 from meningococcal PorA outer membrane protein induces bactericidal antibodies against Neisseria meningitidis.

The immunogenicity and functional activity of antibodies raised in mice against the cyclic disulphide peptide corresponding to the variable region 2 of PorA outer membrane protein from Neisseria meningitidis strain B385 (serosubtype P1.15), displayed on filamentous phage, were evaluated. The epitope, flanked either by cysteine or cysteine and three glycine residues, was expressed as a fusion to PVIII protein from M13. Immunisation of Balb/C mice with either phage generated antibody specific responses. Sera raised against the phage exposing the cyclic peptide through the three-glycine linker recognised the native protein better than those raised against the peptide with no linker. Only the phage displaying the cyclic peptide with linker was capable of inducing antibodies with bactericidal activity. These results indicate the possibility of using phage display for conformational peptide expression for immunisation to elicit functional antibody responses.

Adjuvants, Immunologic↗
PubMed2001

Rhodium/iridium-titanium azaheterometallocubanes.

Treatment of [[Ti(eta5-C5Me5)(mu-NH)]3(mu3-N)] (1) with the diolefin complexes [[MCl(cod)]2] (M = Rh, Ir; cod = 1,5-cyclooctadiene) in toluene afforded the ionic complexes [M-(cod)(mu3-NH)3Ti3(eta5-C5Me5)3(mu3-N)]Cl [M = Rh (2), Ir (3)]. Reaction of complexes 2 and 3 with [Ag(BPh4)] in dichloromethane leads to anion metathesis and formation of the analogous ionic derivatives [M(cod)(mu3-NH)3Ti3-(eta5-C5Me5)3(mu3-N)][BPh4] [M = Rh (4), Ir (5)]. An X-ray crystal structure determination for 5 reveals a cube-type core [IrTi3N4] for the cationic fragment, in which 1 coordinates in a tripodal fashion to the iridium atom. Reaction of the diolefin complexes [[MCl(cod))2] (M = Rh, Ir) and [[RhCl(C2H4)2]2] with the lithium derivative [[Li(mu3-NH)2(mu3-N)-Ti3(eta5-C5Me5)3(mu3-N)]2] x C7H8 (6 C7H8) in toluene gave the neutral cube-type complexes [M(cod)(mu-NH)2(mu3-N)Ti3-(eta5-C5Me5)3(mu3-N)] [M = Rh (7), Ir (8)] and [Rh(C2H4)2(mu3-NH)2(mu3-N)Ti3(eta5-C5Me5)3(mu3-N)] (9), respectively. Density functional theory calculations have been carried out on the ionic and neutral azaheterometallocubane complexes to understand their electronic structures.

Journal Article↗
PubMed2001

Immunogenicity of recombinant class 1 protein from Neisseria meningitidis refolded into phospholipid vesicles and detergent.

The possibility of eliciting bactericidal antibodies against a recombinant class 1 protein (P1) from Neisseria meningitidis, joined to the first 45 amino acids of the neisserial LpdA protein (PM82), was examined. P1 was produced in Escherichia coli as intracellular inclusion bodies, from which it was purified and reconstituted by (a) inclusion into phospholipid vesicles and detergent and (b) refolding in 0.1% SDS. When Balb/c mice were immunised, high titres of subtype-specific bactericidal antibodies against P1 were obtained in both cases. These results suggest that in spite of being a denaturing agent, it is possible to use SDS to reconstitute the P1 protein in a conformation that exposes the immunodominat regions.

Animals↗
PubMed2001

Titanium alkali metal nitrido complexes.

Treatment of [(Ti(eta5-C5Me5)(mu-NH))3(mu3-N)] with alkali metal bis(trimethylsilyl)amido reagents in toluene afforded the complexes [M(mu3-N)(mu3-NH)2[Ti3(mu5-C5Me5)3(mu3-N)]]2 (M = Li (2), Na, (3), K (4)). The molecular structures of 2 and 3 have been determined by X-ray crystallographic studies and show two azaheterometallocubane cores [MTi3N4] linked by metal-nitrogen bonds. Reaction of the lithium derivative 2 with chlorotrimethylsilane or trimethyltin chloride in toluene gave the incomplete cube nitrido complexes [Ti3(eta5-C5Me5)3(mu-NH)2(mu-NMMe3)(mu3-N)] (M = Si (5), Sn (6)). A similar reaction with indium(I) or thallium(I) chlorides yielded cube-type derivatives [M(mu3-N)(mu3-NH)2[Ti(eta5-C5Me5)3(mu3-N)] (M=In (7), Tl (8)).

Journal Article↗
PubMed2001

Isolates from four different HIV type 1 clades circulating in Cuba identified by DNA sequence of the C2-V3 region.

According to the epidemiology of human immunodeficiency virus infection in Cuba, the main sources of infection have been persons coming from foreign countries, mainly from Africa, and individuals who have had sexual contacts with foreigners in Cuba. However, the first Cuban HIV-1 isolates sequenced have been all classified as subtype B. In this note we report the sequence of the gp120 C2/V3 region from 11 HIV-1 isolates from Cuban patients. DNA was isolated either directly from blood PBMC or from primary isolates, PCR amplified and sequenced. Six isolates were classified as subtype B and three of them had the atypical sequences GRGR, GWGR, and TPGR on the tip of the V3 loop. Besides, two other sequences were classified as subtype A, two as subtype H, and one as subtype C. These results confirm that although subtype B seems to be predominant, HIV-1 isolates from various subtypes do circulate in Cuba.

Amino Acid Sequence↗
PubMed2001

Organ donation and family decision-making within the Spanish donation system.

This study analyses the variables associated with the decisions made by families of potential organ donors to give or deny consent for the extraction of organs. Different indicators were recorded in 68 cases of family interview for petition of consent carried out in 13 Spanish hospitals. Those variables showing the strongest relation with family decision (donation/refusal of consent) are knowledge shown by the family about the deceased's wishes with regard to donation (p<0.001), family relationship climate (p<0.01), expression of family's satisfaction level with medical attention received (p<0.01) and number of relatives present at the consent request interview (p<0.01). Logistic regression on family decision with considered variables correctly predicted relatives' final choice in 98.4% of cases. In turn, multivariate exploratory analysis highlights a potential association between the expression of the deceased's wishes and several concurrent variables in the process (satisfaction with personal treatment and medical attention received, emotional reactions in the interviews of notification of death and consent request). It also shows that patterns of reaction and family participation in this process may vary according to the sex of the deceased relative. Results suggest that both educational efforts devoted to promoting a positive attitude toward donation in the general population and the training of health professionals involved in the generation of organs may be key factors in reducing organ shortage.

Bereavement↗
PubMed2001

Performance evaluation of a mesophilic anaerobic fluidized-bed reactor treating wastewater derived from the production of proteins from extracted sunflower flour.

A study of the anaerobic digestion of wastewater derived from the production of protein isolates from extracted sunflower flour was carried out in a laboratory-scale, mesophilic (35 degrees C) fluidized-bed reactor with saponite as bacterial support. Chemical oxygen demand (COD) removal efficiencies in the range of 98.3-80.0% were achieved in the reactor at organic loading rates (OLR) of between 0.6 and 9.3 g COD/I d, hydraulic retention times (HRT) of between 20.0 and 1.1 d and average feed COD concentration of 10.6 g/l. Eighty percent of feed COD could be removed up to OLR of 9.3 g COD/l d. The yield coefficient of methane production was 0.33 l of methane (at STP) per gram of COD removed and was virtually independent of the OLR applied. Because the buffering capacity of the experimental system was maintained at favorable levels with excess total alkalinity present at all loadings, the rate of methanogenesis was not affected by loading. The experimental data indicated that a total alkalinity in the range of 2,000-2,460 mg/l as CaCO3 was sufficient to prevent the pH from dropping to below 7.0 for OLR of up to 9.3 g COD/l d. The volatile fatty acid (VFA) levels and the VFA/alkalinity ratio were lower than the suggested limits for digester failure (0.3-0.4) for OLR and HRT up to 9.3 g COD/l d and 1.1 d, respectively. For a HRT of 0.87 d (OLR of 12.1 g COD/l d) the start of acidification was observed in the reactor.

Fatty Acids↗
PubMed2001

Influence of different natural zeolite concentrations on the anaerobic digestion of piggery waste.

The effect of different natural zeolite concentrations on the anaerobic digestion of piggery waste was studied. Natural zeolite doses in the range 0.2-10 g/l of wastewater were used in batch experiments, which were carried out at temperatures between 27 degrees C and 30 degrees C. Total chemical oxygen demand (COD), total and volatile solids, ammonia and organic nitrogen, pH, total volatile fatty acids (TVFA), alkalinity (Alk) and accumulative methane production were determined during 30 days of digestion. The anaerobic digestion process was favored by the addition of natural zeolite at doses between 2 and 4 g/l and increasingly inhibited at doses beyond 6 g/l. A first-order kinetic model of COD removal was used to determine the apparent kinetic constants of the process. The kinetic constant values increased with the zeolite amount up to a concentration of 4 g/l. The values of the maximum accumulative methane production (Gm) increased until zeolite concentrations of 2-4 g/l. The addition of zeolite reduced the values of the TVFA/ Alk ratio while increasing the pH values, and these facts could contribute to the process failure at zeolite doses of 10 g/l.

Anaerobiosis↗
PubMed2001

Safety and preliminary immunogenicity of the recombinant outer membrane protein P64k of Neisseria meningitidis in human volunteers.

P64k is a meningococcal protein from Neisseria meningitidis that has been obtained by recombinant DNA technology. Recombinant P64k has been extensively characterized by physicochemical and immunological methods. Lately this protein has been found to act as a versatile immunological carrier for weak antigens in mice. In the present work, a Phase I clinical trial was carried out in healthy volunteers who received three inoculations of either placebo or recombinant P64k (20 or 50 microg). No severe adverse events occurred during the trial. Only mild adverse events in ten volunteers were observed. At 1 month after the third dose, 15 out of 18 volunteers (83.3%) who received the recombinant antigen had a P64k-specific antibody titre > or =1:100, as detected by ELISA. A fourth dose, given 9 months after the third one, elicited a potent booster immune response in P64k vaccinees. Accordingly, these P64k formulations were considered safe and immunogenic in healthy human volunteers.

Adult↗
PubMed2001

Long-term follow-up in patients treated with Mini-BEAM as salvage therapy for relapsed or refractory Hodgkin's disease.

Several studies have focused on investigation of the optimal salvage regimen to induce maximum response before autologous stem cell transplantation (ASCT) in patients with relapsed or refractory Hodgkin's disease (HD). However, in most of these studies, the follow-up is relatively short. In the present study, we report on long-term results of 55 consecutive patients with HD who received Mini-BEAM [BCNU (carmustine), etoposide, cytarabine, melphalan] as salvage therapy before ASCT. Eleven patients were refractory to front-line therapy, 17 were partial responders, and 27 patients had relapsed from HD. Twenty-eight patients achieved complete response, and 18 achieved partial response with a median of two cycles of Mini-BEAM, giving a total response rate of 84%. Significant factors predicting poor response (P < 0.05) were: initial treatment with MOPP (mechloroethamine, oncovin, procarbazine, prednisolone), > or = two previous chemotherapy regimens and three disease characteristics at Mini-BEAM treatment: presence of B symptoms, extranodal involvement or low serum albumin. However, only the last two factors retained independent influence on multivariate analysis. In total, 45/55 patients have been transplanted. Median follow-up after Mini-BEAM administration for living patients is 68 months. At the time of reporting, 31 out of 55 patients (56.4%) are still alive, 21 patients (38%) have relapsed, three (5.4%) have developed secondary neoplasias, and five have died of other complications not related to disease progression. The actuarial 7-year overall survival (OS) was 52%, the progression-free survival (PFS) 54% and the event-free survival (EFS) 36%. The response to Mini-BEAM was the most important prognostic factor for predicting the long-term probability of surviving the disease: none of the eight patients who did not respond to Mini-BEAM were alive at 3 years. On multivariate analysis, response to Mini-BEAM and extranodal involvement before Mini-BEAM had a significant influence on OS. Our results show the safety and efficacy of Mini-BEAM before ASCT for refractory or relapsed HD patients.

Adolescent↗
PubMed2001

Evaluation of microbial proteolysis in meat products by capillary electrophoresis.

AIMS: The available methods for evaluating proteolysis in meat products, particularly the contribution of micro-organisms, are expensive, time-consuming and require an unacceptable sample size. To minimize these problems, two capillary electrophoresis-based methods have been developed. METHODS AND RESULTS: Six Gram-positive, catalase-positive cocci, four moulds and three yeasts, isolated from dry-cured ham, were tested on sterile pork slices. Using the Capillary Gel Electrophoresis (CGE) method, changes in sarcoplasmic and myofibrillar proteins due to endogenous and microbial enzymes were detected. The Capillary Zone Electrophoresis (CZE) analysis allowed evaluation of bulk changes by micro-organisms in soluble nitrogen compounds. CONCLUSION: CGE analysis of myofibrillar proteins and CZE determination of soluble nitrogen compounds have proved to be valuable tools for evaluating proteolytic activity of endogenous and microbial origin. SIGNIFICANCE AND IMPACT OF THE STUDY: The CGE and CZE methods developed can be used for a rapid and sensitive analysis of proteolysis in meat products.

Animals↗
PubMed2001

An exploratory multivariate approach to drug consumption patterns in young people based on primary socialization theory.

Drug consumption patterns and their psychosocial conditioning factors are explored on the basis of Primary Socialization Theory (PST), through the application of a questionnaire to a representative sample (N= 650) of the young population (age 15 to 29 years) in the Madrid Region. Cluster analysis identifies five consumption groups. Discriminant analysis, including indicators about subject's integration in primary socialization environments, beliefs about the effects of drugs, indicators of psychosocial wellbeing, and variables related to leisure time, allows 67.45% of correct consumption group prediction. Complex associations between drug use, socialization environments and psychosocial wellbeing are found, calling into question approaches establishing cumulative or unidimensional relationships between posited "risk factors" and drug consumption.

Adolescent↗
PubMed2001

The Spanish National Dose Registry and Spanish radiation passbooks.

The Spanish National Dose Registry (BDN) is the Nuclear Safety Council's (CSN) national database of occupational exposure to radiation. Each month BDN receives records of individual external doses from approved dosimetry services. The dose records include information regarding the occupational activities of exposed workers. The dose information and the statistical analysis prepared by the BDN are a useful tool for effective operational protection of occupationally exposed workers and a support for the CSN in the development and application of the ALARA principle. The Spanish radiation passbook was introduced in 1990 and since then CSN, as regulatory authority, has required that all outside workers entering controlled areas should have radiation passbooks. Nowadays, CSN has implemented improvements in the Spanish radiation passbooks, taking into account previous experience and Directive 96/29/EURATOM.

European Union↗
PubMed2001

Expression of resistance to Blumeria graminis f.sp. tritici in 'Chinese Spring' wheat addition lines containing chromosomes from Hordeum vulgare and H. chilense.

Blumeria graminis f.sp. tritici (syn. Erysiphe graminis f.sp. tritici) causes an important disease of wheat (powdery mildew) to which Hordeum vulgare and H. chilense are resistant. The study of chromosomal addition lines of H. vulgare and H. chilense in wheat showed that they possessed resistance to wheat powdery mildew. This was expressed as a reduction of disease severity but it was not associated with increased macroscopically visible necrosis. The resistance is of broad genetic basis, conferred by gene(s) present on different chromosomes of both H. vulgare and H. chilense. The feasibility of transferring this resistance to wheat is discussed.

Ascomycota↗
PubMed2001

Identification of factors associated with poor peripheral blood progenitor cell mobilization in Hodgkin's disease.

BACKGROUND AND OBJECTIVES: Although the use of drugs which damage stem cells is common in patients with Hodgkin's disease (HD), factors affecting peripheral blood progenitor cell (PBPC) mobilization have not been clearly established in this group of patients. The aim of this study was to identify factors associated with poor PBPC mobilization in patients with HD. DESIGN AND METHODS: In order to address this issue we have evaluated in 54 patients with HD mobilized with G-CSF alone the following factors: sex, age, histologic subtype, B symptoms at diagnosis, status of remission, previous chemotherapy and radiotherapy, interval from diagnosis and last chemotherapy cycle to harvest, and dose of G-CSF. Univariate analysis was performed using Student's t-test, Pearson's correlation and Spearman's correlation. A stepwise regression model was used to determine which of the variables was the most predictive of PBPC mobilization. RESULTS: In univariate analysis poorer PBPC mobilization was observed in patients who had previously received at least two courses of mini-BEAM (p=0.006), a high number of different chemotherapy regimens (p=0.002), a chemotherapy score >30 (p=0.02) and more than 9 months of alkylating agents (p=0.07). We did not find radiotherapy to be a significant factor affecting progenitor cell yield (p=0.59). In the stepwise regression model, only the previous administration of two or more mini-BEAM cycles predicted a poor PBPC yield (p=0.006). INTERPRETATION AND CONCLUSIONS: Previous chemotherapy, principally exposure to a mini-BEAM regimen, seems to be the principal factor affecting collection of PBPC in patients with HD mobilized with G-CSF alone. Since mini-BEAM is an effective salvage regimen in relapsed or refractory HD, collection of PBPC should be planned when there has been no or only minimal exposure to a mini-BEAM regimen.

Adolescent↗
PubMed2001

[A new species of amphipod crustacean of the genus Amphilochus (Crustacea, Amphipoda, Amphilochidae) from Venezuela].

A new species of amphipod Crustacea (Gammaridea, Amphilochidae) of the genus Amphilochus Bate, 1862, is described. The species was collected in Phallusia nigra (Savigny, 1816) at depths between 0 and 2 m, in the pier piles of the Marina El Ancla and Los Manglares gas station in Morrocoy National Park (Falcón State, Venezuela), during the months of June and July 1998. The main differences between A. ascidicola new species and all others species of the genus recorded from the Gulf of Mexico and the Caribbean Sea, are given.

Animals↗