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J A Vázquez

Publications and source records attributed to J A Vázquez.

At least 19 recordsLinked to original sources
PubMed2006

The notion of hormesis and the dose-response theory: a unified approach.

According to an opinion which is vigorous and insistently defended for approximately one decade, hormesis (the response of a biological entity to an effector, with stimulatory results at low doses and inhibitory results at high doses) radically puts into question the classic theory of dose-response (DR) relationships and demands a profound revision of environmental protection policies. Herein we show that DR theory, with the modifications which we propose, allows the modelling of various kinds of biphasic responses which are phenomenologically similar to hormetic ones and of well-defined origin, as well as responses which have been treated as genuinely hormetic. Our descriptive approach may also represent a useful resource for experimental design, directed towards identifying some of the potentially heterogeneous mechanisms which underlie the hormetic phenomenon. Finally, it also allows to discuss some factors which prevent the use of the notion of hormesis-perhaps useful in a clinical context, under strictly controlled conditions-to make decisions on environmental protection measures.

Clinical Protocols↗
PubMed2006

Proteases production by two Vibrio species on residuals marine media.

A comparative study was carried out on the growth and production of alkaline proteases by two Vibrio species using different marine peptones from fish viscera residues. The bacteria tested, Vibrio anguillarum and Vibrio splendidus, are producers of high levels of proteolytic enzymes which act as factors of virulence in fish cultures, causing high mortality rates. The kinetic assays and subsequent comparison with the parameters obtained from the adjustment to various mathematical models, highlighted the potential interest of the media formulated, for their possible production on an industrial scale, particularly the production of proteases by V. anguillarum growing in rainbow trout and squid peptones.

Alkalies↗
PubMed2006

Preliminary tests on nisin and pediocin production using waste protein sources. Factorial and kinetic studies.

Lactic acid bacteria, the object of current interest as bacteriocin producers, are microorganisms with complex requirements for peptidic sources, making them appropriate indicators for testing the suitability of formulations based on proteinaceous wastes for use as microbiological media. Different peptones obtained from visceral and fish muscle residues promoted growth of lactic acid bacteria when applied individually or in combination. Kinetic parameters and bacteriocin production were similar and, in some cases (pediocin), far superior (>500%) to those obtained with bactopeptones and commercial media specifically recommended for lactic acid bacteria growth. Visceral residues, especially when subjected to a brief process of autohydrolysis at 20 degrees C, were more efficient for bacterial growth than muscle, even when muscle was treated with pepsin.

Animals↗
PubMed2006

[Peritoneal bleeding due to acquired hemophilia during an abdominal sepsis clinical picture].

Bleeding diatheses are frequent alterations during sepsis and surgical-anesthetic aggression. Generally, the bleeding is related with platelet dysfunction, inadequate surgical hemostasis, vitamin K deficit, etc. We present the case of a patient with no background of coagulopathy who, after two surgical interventions, developed abdominal sepsis and peritoneal hematoma after puncture for drainage of abdominal collection, due to an autoimmune origin factor VIII acquired deficit. The hematoma caused a picture of hypovolemic shock that required transfusion of several units of red blood cells, expansion and drug support. Finally, the bleeding was controlled by treatment with immunosuppressants, recombinant activated factor VII (RFVIIa) and polyvalent gammaglobulin. The peritoneal hematoma was drained surgically and the patient evolved towards improvement until being discharged from the intensive therapy unit.

Adult↗
PubMed2006

Sequencing of the porB gene: a step toward a true characterization of Neisseria meningitidis.

Variations in class 2/3 (PorB) proteins form the basis for meningococcal serotyping. Antibodies against these proteins are bactericidal, making serotyping results useful not only for epidemiological surveillance of meningococcal disease but also for identifying potential vaccine components. A total of 20 to 60% of meningococcal B and C isolates from any given population are nontypeable (NT) using a panel of monoclonal antibodies. To analyze the mechanisms responsible for the nonserotypeability characteristic in Neisseria meningitidis, we (i) established the nucleotide sequences of porB gene in 146 meningococcal strains (95 not recognized by the serotyping panel), (ii) identified 18 new allelic variants of the porB gene, (iii) correlated allelic variants with serotypes, (iv) suggest the nontypeability characteristic in those 95 NT strains, and (v) reject the possibility of variation in the levels of PorB expression.

Molecular Sequence Data↗
PubMed2005

Stimulation of bacteriocin production by dialyzed culture media from different lactic acid bacteria.

The cross-effects of dialyzed postincubates (with a cut-off at 1000 Da) on the biomass and bacteriocin production of six strains of lactic acid bacteria were studied, and a predominance of stimulating responses was found, the characteristics of which suggested merely nutritional effects or the presence of precursor fragments of the bacteriocins. Additionally, cluster analysis of the detected responses provides an approach to define groups of highly compatible (potential consortia) or doubtfully compatible strains of lactic acid bacteria. Such a definition, which does not claim taxonomic value, has practical interest, however, in cases (e.g., silage production) in which it is convenient to use mixed inocula including strains able to establish positive interactions.

Anti-Infective Agents↗
PubMed2005

Latex agglutination for bacterial antigens and meningococcus PCR: two useful tools in legal sudden deaths.

Bacterial infections are considered to be a major cause of sudden deaths. The recognition of infections caused by Neisseria meningitidis is an essential duty of medicolegal offices due to the risk of secondary cases. Since other microorganisms, such as Haemophilus influenzae and Streptococcus pneumoniae, are also involved in infectious sudden deaths, the identification of the pathogen responsible for death is essential in order to establish a positive diagnosis while also preventing secondary meningococcal cases. However, because of the unreliability of culture methods used for autopsy specimens and the fragile nature of the microorganisms, other techniques were used. In this study, the detection of specific antigens of N. meningitidis (serogroups A, B, C, Y and W135), H. influenzae type b, S. pneumoniae and Group B Streptococcus was undertaken in 40 samples from sudden death cases in legal procedures with a latex agglutination test. In addition, a meningococcus polymerase chain reaction (PCR) assay (ctrA, crgA and siaD genes) was also used as a corroboration method for positive N. meningitidis agglutinations. Eleven cases of sudden death were confirmed to be due to meningococcus while one case was confirmed to have been caused by H. influenzae type b fulminant epiglottitis. Rapid laboratory diagnosis of meningococcal infection allowed contacts management and notification to the health authorities. From the point of view of the authors, forensic diagnosis of unascertained deaths should include latex agglutination and meningococcus PCR when a fulminant infection by N. meningitidis or H. influenzae is suspected as well as in deaths where the cause is unclear.

Adolescent↗
PubMed2005

Effects of aeration on growth and on production of bacteriocins and other metabolites in cultures of eight strains of lactic acid bacteria.

In general, it is accepted that the production of bacteriocins in lactic acid bacteria cultures implies moderately to highly restrictive conditions regarding the availability of oxygen. However, the situation appears to be more complex, probably owing to the facultative anaerobic character of these microorganisms. By studying the culture of eight strains of lactic acid bacteria carried out in vessels with different loads of medium within an interval that determines linearly the minimum availability of oxygen, the existence of three types of behavior was highlighted: production increases (1) with the availability of oxygen, (2) with the restriction of this availability, and (3) toward both extremes of these conditions, diminishing in intermediate situations. These behaviors affected not only the production of bacteriocins, but also their metabolic character (in the Luedeking and Piret sense), as well as the production of other characteristic metabolites, such as lactic acid, acetic acid, and ethanol.

Bacteriocins↗
PubMed2005

[Role of peritoneal drainage in very low birth weight with enterocolitis].

UNLABELLED: Peritoneal drainage (PD) has been proposed as a temporizing procedure for perforated necrotizing enterocolitis (NEC) in very low birth weight neonates. This operation was designed for patients considered too unstable to undergo laparotomy (LAP). Since the introduction of PD some investigators have suggested that it may serve as a definitive therapy. The aim of our study is to determine the efficacy of PD for the stabilization of patients with complicated NEC and its utility as a definitive surgical treatment. METHODS: We review the clinical records from all the patients treated in our unit because of NEC that required surgical therapy. We analyze the mean blood pressure, cardiac and respiratory rate, inspired oxygen concentration, mean airway pressure, diuresis, and arterial blood gases measured 6 and 12 hours after the initial surgical treatment. We divide patients in two different groups according to the initial surgical procedure, peritoneal drainage (PD) or laparotomy group (LAP). Data is shown as media +/- standard deviation, statistical analyses were performed using analysis of variance (ANOVA) for repeated measures and Mann-Withney test. RESULTS: From January 1997 to January 2001 we treated 13 patients with necrotizing enterocolitis that required surgical treatment. Among this group 6 patients were managed initially with PD and 7 with LAP. The gestational age media was 29.07 +/- 3.81 weeks and the birth weight mean 1199.76 +/- 521 gr., without any significant differences between the two groups DP and LAP. All patients improved haemodynamically and respiratory 6 and 12 hours after the surgical treatment. Nevertheless, the mean blood pressure improved even more in the DP group (p<0.005). The DP group showed an improvement in all parameters 6 hours after the drainage was placed, but this effect wasn't maintained for the next 12 hours onwards. From the 12 hours after PD all patients suffered a steady worsening that required further surgical procedures. The overall mortality was 3 patients (23%), without differences between the two groups. The surgical techniques performed (bowel resection, diversion) were similar for both groups. DISCUSSION: DP allows the stabilization for very critically ill patients with complicated NEC. However, this stabilization is temporary. This improvement lasts for a few hours providing a better status for the definitive surgical treatment for the perforated NEC. In our experience DP could not be considered as a definitive surgical treatment.

Child, Preschool↗
PubMed2004

Peptones from autohydrolysed fish viscera for nisin and pediocin production.

Various peptones obtained from hydrolysed visceral homogenates of four fishery residues showed their suitability for promoting the growth of lactic acid bacteria, micro-organisms with particularly complex requirements regarding peptidic nutrients. The assay of several treatments with two bacterial species, producers of the two main bacteriocins (nisin and pediocin) demostrated that optimum conditions only imply a brief autohydrolysis at natural pH and room temperature, with subsequent steam-flow stabilisation. Later kinetic analysis of the cultures of both bacteria in the best media provided parameters which, for production of both biomass and bacteriocins (the latter behaved in the majority of cases as a mixed metabolite), indicate comparable or superior results to those found in costly commercial media, specifically recommended for culture of lactic acid bacteria.

Animals↗
PubMed2004

Impact of the meningococcal C conjugate vaccine in Spain: an epidemiological and microbiological decision.

The new meningococcal C conjugate vaccine became available in Spain and was included in the infant vaccination schedule in 2000. A catch-up campaign was carried out in children under six years of age. As a consequence, the incidence of meningococcal disease caused by serogroup C has fallen sharply during the last three epidemiological years in Spain. The risk of contracting serogroup C disease in 2002/2003 fell by 58% when compared with the season before the conjugate vaccine was introduced. There was also an important decrease in mortality. Three deaths due to serogroup C occurred in the age groups targeted for vaccination in 2002/2003, compared with 30 deaths in the same age groups in the season before the launch of the vaccine campaign. In the catch-up campaign the vaccine coverage reached values above 92%. For the 2001, 2002 and 2003 routine childhood immunisation programme coverage values ranged from 90% to 95%. During the past three years a total of 111 cases of serogroup C disease have been reported in patients in the vaccine target group. Most of the vaccination failures occurred during the epidemiological year 2002/2003. Eight (53%) vaccine failures occurred in children who had been routinely immunised in infancy, and could be related to a lost of protection with time since vaccination. The isolation of several B:2a:P1.5 strains (ST-11 lineage) is noteworthy. These may have their origin in C:2a:P1.5 strains which, after undergoing genetic recombination at the capsular operon level, express serogroup B. These strains could have relevant epidemic potential.

Adolescent↗
PubMed2003

Survival of lactic acid bacteria in seawater: a factorial study.

A feasibility study of lactic bacteria as potential probiotics in larval cultures of marine fish was performed by investigating the survival of five strains of lactic bacteria in seawater by readily standardized procedures at different temperatures and salinities. These conditions were chosen in such a way that their combinations define a complete first-order factorial design. Depending on the strain and the ambient conditions, the survival adhered to first-order kinetics in some cases, and to the Gompertz equation in others. The half lives (t0.5) calculated from these models were subsequently introduced as responses to the factorial designs, estimating the coefficients of empirical equations that describe the group effect of temperature and salinity on t0.5. Simply additive effects were found in two cases, a negative first-order interaction in another case, while another two required second-order models.

Colony Count, Microbial↗
PubMed2003

Opsonophagocytosis versus complement bactericidal killing as effectors following Neisseria meningitidis group C vaccination.

BACKGROUND: Opsonophagocytosis and complement-mediated Neisseria meningitidis killing after vaccination were investigated. METHODS: Twelve seronegative healthy volunteers received one dose of polysaccharide A/C vaccine and were followed for 3 years. Ex vivo serum killing rates with polymorphonuclear cells (PMN) and/or complement were performed at 0, 1.5, 6, 12, 18, 24, 30 and 36 months. RESULTS: High mean total and median bactericidal antibodies were detected over time in all subjects. Considerable reduction of the initial inoculum was obtained only in the presence of complement, with or without PMN (with significant differences compared to curves without complement) a long time after vaccination. CONCLUSION: PMN did not increase post-vaccination bacterial killing, suggesting that antibody complement-mediated killing, and not opsonophagocytosis, is the main immune effector of the vaccine protection against N. meningitidis.

Blood Bactericidal Activity↗
PubMed2003

Meningococcal disease in catalonia 1 year after mass vaccination campaign with meningococcal group C polysaccharide vaccine.

BACKGROUND: The aim of this study was to investigate the clinical and epidemiological characteristics of meningococcal disease in Catalonia (Spain) after vaccination with the polysaccharide vaccine. PATIENTS AND METHODS: Cases were collected by the Statutory Diseases Reporting System. RESULTS: 176 cases were reported, an overall incidence of 2.9/100,000 persons/year. 60% of cases occurred during winter and spring. The case fatality rate was 6.3%. The highest age incidence was in children under 2 years of age (48/100,000 persons/year). Comparison of the cases detected by the Statutory Diseases Reporting System with those obtained by the Microbiological Reporting System shows that meningococcal disease surveillance in Catalonia was relatively complete (95.7%), with a positive predictive value of 66.3%. 115 cases (65%) were culture-confirmed with a rate of 1.9/100,000 persons/year. 86 (75%) cases were due to Neisseria meningitidis serogroup B and 21 to serogroup C (18%). CONCLUSION: Although infections due to serogroup C have decreased after mass vaccination with the polysaccharide vaccine, it is likely that the number of infections will decrease further with the conjugate meningococcal group C vaccine.

Adolescent↗
PubMed2003

Infections by Neisseria meningitidis serogroup X in Spain.

We describe an atypical presentation of bacteremia caused by N. meningitidis serogroup X. By multilocus sequence typing the isolate was characterized to the sequence type 2139, which is not related with the clonal complex recently isolated in Africa. Since 1984, only six cases of serogroup X N. meningitidis infections have been diagnosed in Spain. Nevertheless, after the application of the conjugated vaccine, attention should be paid to the emergence of infections caused by unusual serogroups of N. meningitidis.

Anti-Bacterial Agents↗
PubMed2003

Substrate inhibition of Pediococcus acidilactici by glucose on a waste medium. Simulations and experimental results.

AIMS: The possibility of substrate inhibition by glucose on biomass and pediocin production was studied in cultures of Pediococcus acidilactici on a residual medium. METHODS AND RESULTS: Calculation of the substrate inhibition coefficient in the context of microbial growth is generally laborious, and very prone to experimental error. However, a simulation combining logistic and Monod kinetics equations demonstrates that quantitative evidence for this type of inhibition, without the possibility of misinterpretation, can be obtained through the comparison of punctual preasymptotic productions as a function of substrate concentration. SIGNIFICANCE AND IMPACT OF THE STUDY: It was concluded that glucose had an inhibitory effect on growth, but not on bacteriocin production.

Bacteriocins↗