An improved protocol for pulsed-field gel electrophoresis typing of Clostridium difficile

Pulsed-field gel electrophoresis (PFGE) is the 'gold standard' technique for bacterial typing and has proved to be discriminatory and reproducible for typing Clostridium difficile. Nevertheless, a high proportion of strains are non-typable by this technique due to the degradation of the DNA during the process. The introduction of several modifications in the PFGE standard procedure increased typability from 40% (90 isolates) to 100% (220 isolates) while maintaining the high degree of discrimination and reproducibility of the technique.

Experimental study on the origin of optical waveguide losses by means of Rayleigh backscattering measurement

Scattering is often considered as the main cause of the huge attenuation difference between optical fibers and integrated optical waveguides. In order to evaluate the magnitude of scattering in those waveguides, an optical low coherence reflectometry experiment has been conducted, showing that the amount of backscattered light is not enough to explain that difference in losses.

Double-blind, placebo-controlled study of immunotherapy with Parietaria judaica: clinical efficacy and tolerance

Allergy to Parietaria causes significant morbidity in most Mediterranean areas. The aim of this study is to investigate the efficacy and tolerance of Parietaria depot extract at 25 BU/mL (1.5 microg/mL Par j 1). We performed a multicenter double-blind, placebo-controlled study in rhinitic patients with/without asthma, sensitized to Parietaria. 42 patients followed 20-month immunotherapy. Clinical efficacy was based on symptom and medication scores and the percentage of healthy days (days without symptoms or medication). Severity of asthma/rhinitis scales, visual analogue scale, evaluation of the treatment by doctors and patients, immediate and delayed cutaneous response and quality of life questionnaires were also studied. The active group showed a sustained decrease in symptoms (p = 0.008), medication (p = 0.009) and both (p = 0.001), and an increase in healthy days (p = 0.001) throughout the study, with a threefold increase of healthy days and almost a three time reduction in medication only after one year of treatment. Asthma and rhinitis severity scales also decreased after immunotherapy, and blinded clinical evaluation by physicians confirmed efficacy in 85% and 77% of the active patients. Patient's self-evaluation returned similar results. None of these changes were observed with placebo. Immediate cutaneous response was significantly reduced at the maintenance phase in the active group and remained reduced throughout the study. Late-phase response after intradermal testing also showed a statistical decrease in actively treated patients. Immunotherapy was well tolerated and every systemic reaction reported was mild. In conclusion, immunotherapy with Parietaria 25 BU/mL is an effective and safe treatment for patients with respiratory allergies.

Stomata open at night in pole-sized and mature ponderosa pine: implications for O3 exposure metrics

Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) is widely distributed in the western USA. We report the lack of stomatal closure at night in early summer for ponderosa pine at two of three sites investigated. Trees at a third site with lower nitrogen dioxide and nitric acid exposure, but greater drought stress, had slightly open stomata at night in early summer but closed stomata at night for the rest of the summer. The three sites had similar background ozone exposure during the summer of measurement (2001). Nighttime stomatal conductance (gs) ranged from one tenth to one fifth that of maximum daytime values. In general, pole-sized trees (< 40 years old) had greater nighttime gs than mature trees (> 250 years old). In late summer, nighttime gs was low (< 3.0 mmol H2O m(-2) s(-1)) for both tree size classes at all sites. Measurable nighttime gs has also been reported in other conifers, but the values we observed were higher. In June, nighttime ozone (O3) uptake accounted for 9, 5 and 3% of the total daily O3 uptake of pole-sized trees from west to east across the San Bernardino Mountains. In late summer, O3 uptake at night was < 2% of diel uptake at all sites. Nocturnal O3 uptake may contribute to greater oxidant injury development, especially in pole-sized trees in early summer.

An ICI 182,780-sensitive, membrane-related estrogen receptor contributes to estrogenic neuroprotective actions against amyloid-beta toxicity

Although estrogen (E2)-related neuroprotection has been repeatedly demonstrated in different models, the involvement of non-classical estrogen receptors (ERs) in this activity remains unclear. Using SN56 murine cholinergic cell line from the basal forebrain, we present evidence indicating that an ER associated with the plasma membrane participates in estrogen-dependent reduction of neuronal death induced by amyloid-beta peptide (Abeta) toxicity. Exposure to either E2 or estradiol-horseradish peroxidase (E-HRP) for 15 min significantly reduced Abeta-induced cell death. This effect was decreased by the ER antagonist ICI 182,780 as well as by MC-20 antibody directed to a region neighboring the ligand-binding domain of ERa. Using MC-20 antibody in unpermeabilized SN56 cells, we detected a protein at the plasma membrane region. The binding of impermeant forms of E2, E-HRP, and E-BSA-FITC to specific sites of SN56 plasma membrane was blocked by pre-incubation with E2, ICI 182,780, and MC-20 antibody in a concentration-dependent manner. Thus, a membrane-related ER that shares some structural homologies with ERalpha may participate in estrogen-mediated neuroprotection.

RAPD method useful for distinguishing Leishmania species: design of specific primers for L. braziliensis

The technique of Random Amplification Polymorphic DNA allows fragments of the genome to be amplified by means of polymerase chain reaction (PCR) without previous knowledge of their sequences. The protozoa of the genus Leishmania present great genetic variability, making it difficult to characterize the different species. A method is developed with a single 10-mers long primer, which allows the species L. braziliensis, L. mexicana, L. infantum, L. tropica, L. chagasi, L. amazonensis and L. major to be differentiated. These products amplified by RAPD have also facilitated the design of some primers that amplify L. braziliensis DNA exclusively.

Estradiol prevents amyloid-beta peptide-induced cell death in a cholinergic cell line via modulation of a classical estrogen receptor

The pathology of Alzheimer's disease includes amyloid-beta peptide aggregation that contributes to degeneration of cholinergic neurons. Even though the underlying molecular mechanisms remain unclear, recent in vitro evidence supports a protective role for estrogens against several neurotoxic agents. Here we report that, in a murine cholinergic cell line (SN56), the massive cell death induced by 1-40 fragment of amyloid-beta peptide was prevented by 17beta-estradiol through a mechanism that may involve estrogen receptor activation. The protective effect of estradiol was observed in a dose-dependent manner, and was completely blocked by the pure antiestrogen ICI 182,780. In contrast, the inactive isomer 17alpha-estradiol consistently showed weaker neuroprotection than the native hormone that was unaffected by ICI 182,780 treatment. In addition, equivalent concentrations of 17beta-estradiol enhanced luciferase activity in cells transfected with a luciferase reporter gene driven by tandem estrogen response elements. Estrogen-induced luciferase activity was blocked by ICI 182,780, indicating estrogen receptor-dependent transcriptional activity. We also observed by reverse transcription-polymerase chain reaction, Western blot and immunocytochemistry that increasing concentrations of 17beta-estradiol enhanced the expression of estrogen receptor alpha mRNA and protein during amyloid-beta-induced toxicity. Under these conditions, it was found by confocal microscopy that the localization of estrogen receptor alpha in the absence of hormone was mainly extranuclear. However, the receptor was consistently observed also at the nuclear region after estrogen exposure. Overall, these data suggest that estrogen may exert neuroprotective effects against amyloid-beta-induced toxicity by activation of estrogen receptor-mediated pathways. In addition, intracellular estrogen receptors are up-regulated by their cognate hormone even during exposure to neurotoxic agents.

Blockade of CRF(1) or V(1b) receptors reverses stress-induced suppression of neurogenesis in a mouse model of depression

Repeated exposure to stress is known to induce structural remodelling and reduction of neurogenesis in the dentate gyrus. Corticotrophin-releasing factor (CRF) and vasopressin (AVP) are key regulators of the stress response via activation of CRF(1) and V(1b) receptors, respectively. The blockade of these receptors has been proposed as an innovative approach for the treatment of affective disorders. The present study aimed at determining whether the CRF(1) receptor antagonist SSR125543A, the V(1b) receptor antagonist SSR149415, and the clinically effective antidepressant fluoxetine may influence newborn cell proliferation and differentiation in the dentate gyrus of mice subjected to the chronic mild stress (CMS) procedure, a model of depression with predictive validity. Repeated administration of SSR125543A (30 mg/kg i.p.), SSR149415 (30 mg/kg i.p.), and fluoxetine (10 mg/kg i.p.) for 28 days, starting 3 weeks after the beginning of the stress procedure, significantly reversed the reduction of cell proliferation produced by CMS, an effect which was paralleled by a marked improvement of the physical state of the coat of stressed mice. Moreover, mice subjected to stress exhibited a 53% reduction of granule cell neurogenesis 30 days after the end of the 7-week stress period, an effect which was prevented by all drug treatments. Collectively, these results point to an important role of CRF and AVP in the regulation of dentate neurogenesis, and suggest that CRF(1) and V(1b) receptor antagonists may affect plasticity changes in the hippocampal formation, as do clinically effective antidepressants.

A European survey of diagnostic methods and testing protocols for Clostridium difficile

OBJECTIVE

To conduct a survey of the methods used in clinical microbiology laboratories in Europe to diagnose infection with Clostridium difficile.

METHODS

A questionnaire was devised and sent to a co-ordinating member of the Study Group in each of eight European countries. This co-ordinator was in charge of forwarding the questionnaire to hospital laboratories arbitrarily selected. The number of laboratories in each country was determined on the basis of one laboratory for 10,000 beds of hospitalization. This questionnaire covered different aspects pertaining to Clostridium difficile associated to diarrhea (CDAD) diagnosis such as circumstances of request, criteria used for undertaking C. difficile investigations, methods used for the diagnosis, etc.

RESULTS

A total of 212 questionnaires were completed and submitted for analysis: 87.7% of laboratories reported routinely performing C. difficile diagnostic tests. Methods used included toxin detection (93%), culture (55%), and glutamate dehydrogenase (GDH) detection (5.9%). Among the laboratories detecting toxins, different enzyme immunoassays (EIA) and cytotoxicity assays were used in 79% and 17.3% of cases, respectively. Among the different strategies reported, 4.8% were considered suboptimal for the diagnosis of C. difficile infections, but marked discrepancies could be observed between countries. The overall incidence (median) of CDAD was estimated at 1.1 for 1,000 patient admissions.

CONCLUSION

The results of this study suggest marked discrepancies between laboratories and also between countries regarding the criteria by which C. difficile is investigated for, and the methods and the strategies that are used for the diagnosis of C. difficile. These discrepancies could be explained by the lack of clear guidelines for C. difficile diagnosis in each country, and by the importance that physicians attach to C. difficile. Precise guidelines for C. difficile diagnosis would be the first step to make possible accurate comparison of the incidence and the epidemiology of CDAD from one hospital to another or from one country to another.

Developmental expression of neurotensin in thyrotropes and gonadotropes of male and female rats

Besides its potential roles as a central neuromodulator or a hypothalamic neurohormone, neurotensin (NT) may also have endocrine function in the anterior pituitary of mammals. We previously found that NT immunoreactivity is present in the secretory granules of gonadotropes and thyrotropes in both male and female rats, where its levels of expression are under the control of sex steroids. In this work, using immunocytochemistry and in situ hybridization, we have studied the postnatal development of NT-like immunoreactivity (NTir) and the mRNA encoding NT (mRNA-NT) in specific anterior pituitary cells of both male and female rats. NT expression starts after birth and displays an identical pattern in both sexes until sexual maturity, with mRNA-NT being detected from day 2 of postnatal life in thyrotropes localized in the central portion of the anterior lobe. This pattern of expression develops progressively throughout the 2nd and 3rd weeks in both sexes. By the beginning of the 3rd week, mRNA-NT can also be detected in gonadotropes localized in the periphery of the gland coinciding with a rise in serum estradiol concentrations in both sexes, and by day 21, mRNA-NT is extensively present in both the periphery and the central region. NTir is observed from days 5-6 in thyrotropes predominantly localized in the central portion of the anterior lobe, and by day 21, NTir is also detected in gonadotropes localized in the periphery of the gland. This pattern remains similar in both sexes until the time of puberty, when female rats start displaying plastic changes in NT expression according to the stage of the estrous cycle. These findings indicate that NT expression in the rat anterior pituitary is cell specific, and develops from birth to adulthood under the control of sex steroid hormones. In addition, preliminary data showing the presence of NT receptors in rat pituitary cells support the hypothesis of a paracrine or an autocrine role for this peptide within the pituitary.

Olerance of a cluster schedule with a house dust mite extract quantified in mass units: multicentre study

The standardisation of allergenic extracts in micrograms of the major allergen has encouraged the search for new treatment schedules, with the purpose of shortening the number of visits and doses required to reach the maintenance dose without eliciting a greater risk of adverse reactions for the patients. With this objective, a prospective multicentre pharmacovigilance study was designed that included 200 patient with allergic rhinoconjunctivitis and/or allergic asthma sensitised to mites (Dermatophagoides pteronyssinu and/or farinae). The dose increment period was carried out using a cluster schedule, where the optimal dose wa reached after 4 visits, administering two doses in each visit. The duration of the study was 5 months and a total o 1902 doses were administered. At the end of the trial, 31 adverse reactions in 23 patients were recorded. Six of these were systemic (0.3% of t administered doses) recorded in 6 patients (3% of the sample). One was an immediate reaction (grade 1) and delayed (4 mild and 1 moderate). Two were asthmatic exacerbations, 2 cutaneous reactions, 1 rhinitis and 1 an unspecific symptom (not IgE-mediated). Two appeared upon administration of the first vial and the remaining 4 after administration of the third cluster. Therefore, the schedule tested presents an adequate tolerance profile, suggesting savings (compared to th conventional schedule of 13 doses per patient) of 1800 visits and 1000 treatment doses in the whole study.

Tolerance and effects on skin reactivity to latex of sublingual rush immunotherapy with a latex extract

BACKGROUND

Specific immunotherapy could be a therapeutic tool for the increasing problem of sensitisation to Natural Rubber Latex (NRL).

OBJECTIVE

To investigate the tolerability of SLIT for Latex and its effects on skin reactivity.

METHODS

Twenty-six patients (mean age 35.5 years) with an average history of 7.5 years of cutaneous symptoms plus respiratory symptoms (23/26) due to NRL were studied. All underwent rush sublingual therapy (4 days) with a standardized NRL extract followed by a 9-week maintenance treatment. Local and systemic adverse reactions were monitored throughout the treatment. Skin reactivity to NRL extract was evaluated before, during and at the end of the treatment by latex glove-use test, rubbing test and skin prick test.

RESULTS

All patients reached the maintenance dose. Out of 1044 administered doses, 257 (24.6%) produced adverse reactions from which 21.4% were local. Only 10.1% of cases required treatment, mainly with antihistamines alone (5.8%), with 2-agonists alone (0.8%) or associated to antihistamines and/or corticosteroids (2.7%). One patient was precautionary treated twice with adrenaline but completed the treatment without further problems. The glove-use test improved significantly after 5 days and 10 weeks of treatment (p = 0.003, p = 0.0004 respectively), whereas the rubbing test improved significantly only after 10 weeks of treatment. Doctor's assessments confirmed the results obtained with the glove-use test (p = 0.003 after 5 days, and p = 0.004 after 10 weeks) but not those obtained with the rubbing test. No change was detected for SPTs.

CONCLUSION

SLIT for NRL allergy is able to modify skin reactivity to NRL in days as assessed with methods reproducing HCWs normal exposure to the allergen. Tolerance of SLIT is better than tolerance reported for injective therapy with NRL, but the build up phase should be administered under medical surveillance until sufficient experience has been accumulated. The long-term effect of the treatment deserves further investigation.

IgE reactivity to profilin in Platanus acerifolia pollen-sensitized subjects with plant-derived food allergy

BACKGROUND

The presence of profilin-specific IgE antibodies is a cause of cross-reactivity between botanically-unrelated allergen sources. Recently, the association between Platanus acerifolia pollinosis and plant-derived food allergy has been described. The aim of this study was to ascertain whether the P. acerifolia profilin is involved in such cross-reactivity.

METHODS

Twenty-three patients suffering from Platanus acerifolia pollinosis and plant-derived food allergy were evaluated in an allergy department. Specific IgE levels to P. acerifolia pollen, P. acerifolia profilin and food extracts were measured. Molecular masses of IgE-binding proteins were calculated by Western blotting and cross-reactivity studies among P. acerifolia profilin and different food extracts were evaluated by Enzyme AllergoSorbent Test (EAST)-inhibition assays. Also, EAST-inhibition assays with the two known P. acerifolia allergens, Pla a 1 and Pla a 2, were performed.

RESULTS

Surprisingly, a high IgE-binding prevalence (90%) of P. acerifolia profilin was found. EAST-inhibition showed high inhibition values when Platanus acerifolia pollen extract was used as free phase and plant-derived food extracts as solid phase, whereas the other way round showed low inhibition values. IgE reactivity to profilin was studied using a pool of patient sera, by EAST-inhibition assays with hazelnut, apple peel, peanut, chickpea and peanut extracts as solid phase and no inhibition was obtained when P. acerifolia profilin was used as inhibitor phase. The same results were obtained when purified Pla a 1 and Pla a 2 were also used as inhibitor phase.

CONCLUSIONS

The clinical association observed between Platanus acerifolia pollen and plant-derived food could be explained by the in vitro IgE cross-reactivity detected by EAST-inhibition. However, it appears that neither P. acerifolia profilin nor the two major allergens described (Pla a 1 and Pla a 2) can explain such a strong cross-reactivity.

Experimental and interventional dietary study in humans on the role of HDL fatty acid composition in PGI2 release and Cox-2 expression by VSMC

BACKGROUND

High-density lipoproteins (HDLs) induce prostacyclin (PGI2) release in vascular smooth muscle cells (VSMCs) by up-regulation of cyclooxygenase-2 (Cox-2). Our goal was to analyze the role of human HDL lipid moiety on Cox-2-dependent PGI2 synthesis in human VSMCs and to assess the impact that the intake of diets with different fatty acid composition exert on HDL-induced PGI2 release.

MATERIALS AND METHODS

Human VSMCs were treated with HDL or fatty acids in the presence or absence of different cell signalling inhibitors and PGI2 (by enzyme immunoassay) and Cox-2 protein levels (by Western blot) were analyzed. High-density lipoproteins were obtained from a plasma pool or from plasma of 12 volunteers subjected to a longitudinal dietary interventional study of three consecutive diets periods enriched in monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids n-6 (PUFA n-6) or n-3 (PUFA n-3).

RESULTS

High-density lipoprotein delipidation attenuated the effect of HDL on both PGI2 synthesis and Cox-2 up-regulation, while arachidonic acid (AA) but not other fatty acids mimicked the effects of HDL. Arachidonic acid induced PGI2 synthesis and Cox-2 expression through similar mechanisms to those activated by HDL [pertussis toxin-sensitive G proteins, p42/44 mitogen-activated protein kinase (MAPK), p38MAPK, and c-Jun N-terminal kinase-1 (JNK-1) pathways]. Finally, we observed that HDL from the PUFA n-3 dietary period induced lower PGI2 release than that from the PUFA n-6 period (64% vs. 100%).

CONCLUSIONS

Our results suggest that lipid moiety modulates HDL-induced PGI2 release/Cox-2 up-regulation in human VSMCs, and that changes in fatty acids as accomplished with the diet can modulate vascular PGI2 homeostasis.

Lettuce anaphylaxis: identification of a lipid transfer protein as the major allergen

BACKGROUND

Allergy to plant-derived foods is associated with birch pollinosis in central and northern Europe. Symptoms elicited are usually limited to the oropharyngeal system. By contrast, in the Mediterranean area, allergy to the same foods manifests more frequently with systemic reactions caused by nonspecific lipid transfer proteins (nsLTP), independently of an associated pollinosis.

OBJECTIVE

We sought to investigate the pattern of immunoglobulin E (IgE) binding protein bands implicated in lettuce allergy, in particular the presence of an nsLTP.

METHODS

Consecutive lettuce allergic patients were selected. Determination of serum-specific IgE, immunoblot, and inhibition experiments were performed in order to study the pattern of IgE binding proteins and the potential cross-reactivity to pollens. Inhibition studies with recombinant allergens were conducted to identify the lettuce allergens. The major allergen was subjected to N-terminal amino acid sequencing.

RESULTS

Fourteen patients were diagnosed as being allergic to lettuce. All were sensitized to Platanus pollen. Ten of them showed specific IgE to a lettuce protein of 9-kDa. The IgE binding to this protein was completely inhibited by the cherry-LTP and peach extract. The N-terminal sequence of the 9-kDa protein showed a high degree of amino acid sequence identity to other nsLTPs. A clear partial cross-reactivity was observed between lettuce-LTP and Platanus-pollen extract.

CONCLUSIONS

An LTP has been demonstrated to be a major allergen in patients suffering from lettuce allergy.

Apolipoprotein E genotype is not associated with cardiovascular disease in heterozygous subjects with familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is a genetic disorder characterized by high low-density lipoprotein cholesterol levels and premature cardiovascular disease (CVD). There are important differences in the presence of CVD among heterozygous subjects with FH. Some of this variability can be explained by genetic factors, and the apolipoprotein (apo) E genotype has been proposed as a useful marker.

METHODS

We analyzed the apo E genotype in 706 non-related subjects who were heterozygous for FH from Spain. CVD was present in 198 subjects (28%), 132 men (41%) and 66 women (17%).

RESULTS

Apo E allele frequencies for the epsilon 3, epsilon 4, and epsilon 2 alleles were 0.89, 0.09, and 0.02 respectively. Age, body mass index, smoking status, high blood pressure, diabetes mellitus, presence of tendon xanthomas, total cholesterol level, triglyceride levels, high-density lipoprotein cholesterol level, low-density lipoprotein cholesterol level, and Lp(a) did not differ among genotypes. The incidence of CVD and the age of onset of CVD did not differ among genotypes either. In the multivariant analysis, apo E genotype did not contribute significantly to CVD.

CONCLUSIONS

Heterozygous men with FH have a very high risk of coronary disease in a Mediterranean country, and the apo E genotype in this large group of adults with FH is not associated either with CVD or lipid values, in contrast with the established effect in the general population.

Effect of treatment with the selective oestrogen receptor modulator LY117018-HCl on pituitary sensitivity to GnRH and subsequent ovulation

The effects of LY117018-HCl (LY; a benzothiophene similar to raloxifene) were examined on various reproductive parameters in female rats. Four-day cyclic rats were treated (10:00 h on dioestrus) with LY (0.01, 0.1, 0.5, 1, 2, 4 or 16 mg kg(-1) p.o.) and assessed for ovulation at oestrus. LY inhibited ovulation at doses as low as 0.5 mg kg(-1), and ovulation did not occur at doses of 4 and 16 mg kg(-1). LY (16 mg kg(-1)) reduced wet uterine mass and LH concentrations at the time of the expected ovulatory surge. Ovulation induced by hCG in pentobarbital-treated rats was not altered by LY treatment, indicating normal ovarian sensitivity to gonadotrophins. LY, however, completely blocked the effects of oestradiol (under either negative or positive feedback modes) on LH secretion in ovariectomized rats. GnRH secretion into hypophyseal portal blood during pro-oestrus was not affected by treatment with LY, whereas the concentrations of serum LH remained reduced. Finally, treatment with LY markedly reduced pituitary sensitivity to GnRH during pro-oestrus, as it completely blocked GnRH-induced LH secretion. These results demonstrate that LY inhibits oestradiol action in the uterus and prevents ovulation in normal cyclic rats. LY-induced inhibition of ovulation is not caused by an alteration of the ovarian response to gonadotrophins or an impairment of GnRH secretion at the hypothalamus, but by a reduction in the sensitivity of gonadotrophs to the stimulatory effects of GnRH during pro-oestrus.

Development of a rapid polymerase chain reaction-ELISA assay using polystyrene beads for the detection of Toxoplasma gondii DNA

AIMS

To develop a rapid colourimetric assay for the detection of Toxoplasma gondii DNA using polystyrene beads as solid support.

METHODS AND RESULTS

A nested-polymerase chain reaction (PCR)-ELISA assay for the detection of T. gondii DNA was standardized by optimizing the hybridization time and probe concentration. Its detection threshold was then determined and compared with Southern blotting hybridization. These were found to be equivalent, but the PCR-ELISA-beads test is easier to perform and the turnaround time is much shorter than with Southern blot.

CONCLUSIONS

The PCR-ELISA-beads assay is a valuable tool for the detection of T. gondii DNA.

SIGNIFICANCE AND THE IMPACT OF THE STUDY

Our results demonstrate that this PCR-ELISA assay, using polystyrene beads, can be used as a routine diagnostic test for the detection of T. gondii in clinical laboratories.