Contaminación de la dentina con diferentes técnicas de secado / Contamination of dentin with different drying techniques

El secado es uno de los factores clave para lograr una adhesión micromecánica exitosa en la dentina con los sistemas adhesivos de grabado independiente. El objetivo de este trabajo fue comparar los residuos remanentes luego de cuatro procedimientos diferentes de secado en preparaciones ex vivo en dentina. Se utilizaron cinco terceros molares ex-vivo, en cada uno de los cuales se realizó una preparación dentinaria en piso y paredes con al menos un socavado. Las unidades experimentales fueron almacenadas en solución fisiológica durante 7 días. Las distintas técnicas de secado (G1- G8) se aplicaron, luego de que las preparaciones fueron tratadas con gel de ácido fosfórico al 37% (Blue Gel etch Megadental) durante 15s y lavadas con jeringa y agua a presión durante 15s (Técnica de Grabado Ácido o TGA), de la siguiente manera: algodón común (Condesa) (G1), papel tisú (Achiss) cortado a mano (G2) y con tijera (G3), esponja (Sharpys) (G4), papel tisú (Simplicity) cortado a mano (G5)(AU)

Arundic acid administration protects astrocytes, recovers histological damage and memory deficits induced by neonatal hypoxia ischemia in rats.

INTRODUCTION: Perinatal hypoxia-ischemia (HI) is one of the main causes of mortality and chronic neurological morbidity in infants and children. Astrocytes play a key role in HI progression, becoming reactive in response to the injury, releasing S100 calcium binding protein B (S100B). Since S100B inhibition seems to have neuroprotective effects on central nervous system injury models, here we evaluated the neuroprotective effects of an S100B inhibitor, arundic acid (AA) in a HI model. METHODS: On the 7th postnatal day, animals were submitted to the combination of common carotid artery occlusion and hypoxic atmosphere (8% O2) for 60 min. Three experiments were performed in order to: (1) define AA dose (0.1, 1 or 10 mg/kg, pre-hypoxia i.p. injection), (2) test if repeated AA administrations (10 mg/kg at 3 time points: Pre-hypoxia, 24 h and 48 h after HI) would improve the response and (3) investigate biochemical mechanisms involved in AA protection two days after HI. RESULTS: AA at a dose of 10 mg/kg applied before and after hypoxia, was the only treatment protocol that was able to improve HI-induced memory deficits, to reduce tissue damage, to promote astrocytic survival in the hippocampus and to reduced extracellular release of S100B in the cerebrospinal fluid. CONCLUSION: Overall, AA treatment showed beneficial effects on memory deficits, tissue damage, promoting astrocyte survival likely by reducing S100B release. Protection aided to astrocytes by AA treatment against HI lesion may lead to development of new therapeutic strategies that target these particular cells.

Comparación en la resistencia de unión en la fijación de postes de base orgánica con la utilización de cementos resinosos vs. ionómeros modificados con resina / A comparison of bond strength in cementing organic base posts by using resin cements vs. resin-modified glass ionomer cements

Los postes de base orgánica reforzados con fibras constituyen un recurso terapéutico de gran relevancia para la rehabilitación de dientes tratados endodónticamente. Sin embargo, la metodología para obtener una adecuada fijación a las paredes radiculares todavía es objeto de estudio y discusión. El objetivo de este trabajo fue evaluar la resistencia de unión en la cementación de postes de base orgánica reforzadoscon fibra de vidrio, empleando un cemento resinoso, y compararla con la resistencia de unión de dichos postes utilizando un cemento de ionómero vítreo modificado con resinas como medio de fijación. Se utilizaron 24 premolares inferiores humanos unirradiculares recientemente extraídos. Se realizó el tratamiento endodóntico a todas las piezas dentarias empleando instrumentación mecanizada con un sistema rotatorio y técnica híbrida para la obturación. Posteriormente, se realizaron las maniobras de desobturación y preparación del lecho radicular, y la cementación del poste en cada pieza dentaria. Los especímenes obtenidos se dividieron en 2 grupos según los materiales utilizados para la cementación: 1) Cemento resinoso (Rebilda DC; VOCO Germany) con sistema adhesivo; 2) Cemento de ionómero vítreo modificado con resina (Meron Plus; VOCO Germany). Resultados: La resistencia de unión en la cementación de postes de fibra de vidrio fue significativamente mayor con la utilización de cementos resinosos en comparación con el uso de cemento de ionómero vítreo reforzado con resina (p <0,0001). Conclusión: la utilización de cementos de resina duales como medio de fijación es más recomendable que el uso de cementos de ionômero.

Organic base posts reinforced with fibers constitute a therapeutic resource of great relevance for the rehabilitation of endodontically treatedteeth. However, the methodology for proper attachment to the root walls is still under study and discussion. The aim of this study was toevaluate the bond strength in cementing organic base posts reinforced with fiberglass, using resin cement, and compare it with the bondstrength of these posts using glass ionomer cement modified with resins as fixing means. 24 single-rooted human premolars recentlyextracted were used. Endodontic treatment was performed to all teeth using a mechanized rotary instrumentation and hybrid technique forsealing. Subsequently, we proceeded to unsealing all the teeth, preparing root beds and cementing the posts. The obtained specimens weredivided into 2 groups according to the materials used for cementation: 1) Resin cement (Rebilda DC, VOCO Germany) with adhesivesystem; 2) Glass ionomer cement modified with resin (Meron Plus, VOCO Germany). Results: The bond strength of fiberglass postscementation was significantly higher with the use of resin cements compared with using glass ionomer cement reinforced with resin (p<0.0001). Conclusion: The use of dual resin cements is more recommendable as fixing means than ionomer cements.

Resistencia de unión en la fijación de postes de base orgánica con la utilización de cementos resinosos con y sin sistema adhesivo / Bond strength of organic base posts cementation by using resin cements with and without an adhesive system

En la actualidad, los postes de fibra de vidrio son ampliamente utilizados para la reconstrucción de piezas tratadas enodónticamente con indicación de anclaje intrarradicular. Por lo tanto, el objetivo de este trabajo fue evaluar la resistencia de unión en la cementación de postes de fibra de vidrio con la utilización de cementos resinosos con y sin sistema adhesivo. Se utilizaron 24 premolares inferiores humanosunirradiculares recientemente extraídos. Luego, se procedió a realizar los tratamientos endodónticos a todas las piezas dentarias con el sistema Protaper y a su obturación con técnica híbrida. A continuación, se procedió a la desobturación de todas las piezas y a lacementación de los postes. Las muestras se dividieron en 4 grupos según los materiales utilizados para la cementación: 1) Cemento Rebildacon sistema adhesivo; 2) Cemento Rebilda sin sistema adhesivo; 3) Cemento Paracore con sistema adhesivo; 4) Cemento Paracore sinsistema adhesivo. Resultados: no se observaron diferencias significativas de resistencia entre los tratamientos con y sin sistema adhesivo; ni entre los tratamientos con los cementos Rebilda y Paracore. Tampoco se evidenció interacción entre la utilización o no del sistema adhesivo y el tipo de cemento. Conclusión: todas las combinaciones estudiadas otorgan la misma resistencia de unión de los postes a los tejidosintrarradiculares...

Identification, molecular biotyping and ultrastructural studies of bacterial communities isolated from two damaged frescoes of St Damian's Monastery in Assisi.

AIM: To investigate the composition of the microbial community in biodeterioration of two frescoes in St Damian's Monastery in Assisi. METHODS AND RESULTS: A total of 1292 colonies were isolated from the most deteriorated parts, analysed by microbiological, biomolecular and ultrastructural techniques, and taxonomically classified. Molecular biotyping of Staphylococcus cohnii colonies, one of the most prevalent bacterial species, showed a very restricted genome diversity while Bacillus licheniformis were very homogeneous by RFLP, tDNA-PCR and random-amplified polymorphic DNA. Electron microscopy confirmed heterogeneity of the bacterial population in the different sampling areas. CONCLUSIONS: Several of the identified species are widespread in the soil or saprophytes of human skin. Although unable to demonstrate that they are involved in biodeterioration, they may represent trophic elements contributing to fungi-related chromatic alterations when adequate environmental conditions occur. Deterioration may in part be prevented or controlled by adequate air filtering or conditioning of the room.

Correlation between the immune response elicited in rabbits by env-recombinant avipox vaccines and the inhibition of HIV-1-specific functions.

The fine immunoreactivity of the rabbit humoral response elicited by four env-recombinant avipoxviruses and their ability to stimulate a memory T-cell response and a protective immunity have been studied. The antibody specificity was compared with the serum neutralizing activity and virus-specific T-cell proliferative response. Resistance to challenge by cell-associated HIV-1 was monitored by PCR. Canarypox (CP) and fowlpox (FP) constructs, containing the complete env gene (IS(+)) from the HIV-1(SF2) strain, induced a higher profile of epitope recognition than their counterparts expressing the env gene deleted of the putative immunosuppressive region (IS(-)). Serum neutralizing activity was in agreement with fusion inhibition and lymphoproliferative response in rabbits immunized with CPIS(+), and only partially with FPIS(+). Rabbits failed to be infected, but anti- p55 gag-specific antibodies could be demonstrated by Western blot. This study confirms the ability of these non-replicative live recombinant viruses to elicit a complete immune response, capable of inhibiting specific HIV-1 functions.

Biological and conformational studies on analogues of a synthetic peptide enhancing HIV-1 infection.

We have previously demonstrated that a 23-amino acid peptide derived from the V3 loop of the surface glycoprotein of the HIV-1 strain MN is able to bind CD4 and to enhance HIV-1 infection. Further studies have suggested that the peptide/CD4 interaction induces an increase in both CD4 expression and CD4/gp120 binding affinity. This paper describes the biological and physico-chemical characterization of three analogues of reduced sequence that have been designed in order to identify the minimum active sequence of this peptide corresponding to the MN-HIV- 1 principal neutralizing domain. Biological studies indicate that the entire sequence is required for biological activity and that the sequence 1-18 presents an inhibitory activity. CD and FT-IR absorption data are discussed here in order to identify possible structure-function correlations.

Design, synthesis and CD4 binding studies of a fluorescent analogue of a peptide that enhances HIV-1 infectivity.

We previously demonstrated that a 23-amino-acid peptide derived from the V3 loop of the surface glycoprotein of human immunodeficiency virus (HIV-1) strain MN was able to bind soluble CD4 and to enhance HIV-1 infection. Further studies suggested that the peptide/CD4 interaction induces an increase in both CD4 expression and CD4/gp120 binding affinity. To facilitate identification of the complementary binding site for the peptide on cellular CD4, we designed an analogue carrying a single fluorescein moiety. The synthesis of this modified analogue presented several problems because of the presence of several amino acids in the sequence carrying potentially reactive groups in their side-chains, and the necessity of introducing only one marker per molecule in a position that would not affect biological activity. The side-chain of Lys19 was selected because separate studies demonstrated that its substitution with an uncharged amino acid does not reduce the peptide's biological activity. We compared the merits of various synthetic protocols used to condense the fluorescent marker with the peptide. Biological assays indicated that the presence of the fluorescein moiety did not compromise peptide binding to CD4; furthermore, binding of the labeled analogue was not abolished by trypsin treatment, suggesting that the peptide may interact with both CD4 and additional trypsin-resistant binding sites on the cell surface. Finally, we verified the preservation of HIV infection enhancing ability in the labeled peptide.

Viral phenotype and host-cell susceptibility to HIV-1 infection as risk factors for mother-to-child HIV-1 transmission.

OBJECTIVE: To investigate the role of maternal HIV-1 isolate phenotype and a child's cell susceptibility/resistance to viral infection in mother-to-child HIV-1 transmission. PATIENTS AND METHODS: Forty-nine women were studied at the time of delivery. Primary isolates, obtained by culturing patient peripheral blood mononuclear cells (PBMC) with PBMC from healthy donors, were characterized for tropism and syncytium-inducing capability in monocyte-derived macrophages (MDM), peripheral blood lymphocytes (PBL), and in the MT-2 and MOLT-3 T-cell lines. RESULTS: Seven women transmitted HIV-1 to their children. Primary isolates were obtained from six and 28 transmitting and non-transmitting mothers, respectively. All primary isolates from transmitting mothers and their infants but only 50% of those from non-transmitting mothers replicated in MDM, regardless of their replication capacity in T-cell lines. PBL and MDM cells from six uninfected children were exposed to the corresponding maternal isolates. Polymerase chain reaction analysis of HIV-1 DNA in cells and p24 antigen assay in culture supernatants disclosed that two PBL and five MDM cultures were resistant to viral infection; two other PBL cultures, although HIV-1-infected, were negative for p24 production. Depletion of CD8+ cells only partially restored productive infection in CD4+ cell cultures. Moreover, all six PBL but only one MDM cultures were productively infected by an isolate obtained from a transmitting mother, thus suggesting that MDM resistance to HIV-1 infection is not viral isolate-restricted. CONCLUSIONS: Our findings strongly suggest that mother-to-child HIV-1 transmission is influenced by both monocyte-macrophage tropism of the maternal isolate and susceptibility of the child's target cells, in particular monocyte-macrophages, to HIV-1 infection.

Minimal sequence requirements for synthetic peptides derived from the V3 loop of the human immunodeficiency virus type 1 (HIV-1) to enhance HIV-1 binding to cells and infection.

We previously demonstrated that a 23-mer peptide (DB3) derived from the V3 loop of the surface glycoprotein of HIV-1 MN strain was able to bind to soluble CD4 and enhance HIV-1 infection. The mechanism and structural features required for these biological activities were studied by using shortened DB3 derivatives and DB3 analogs carrying single amino acid substitutions. We found that peptides in which the aromatic amino acid in position 15 or 16 had been replaced by an uncharged hydrophobic residue (DB3-I15 and DB3-I16), analogs in which positively charged amino acids were replaced by corresponding D-enantiomers, and shortened DB3-derivatives lost both enhancing activity and ability to bind to soluble CD4. Other peptide variants in which a positively charged amino acid was replaced by asparagine at positions 3 (DB3-N3), 6 (DB3-N6), and 19 (DB3-N19), respectively, retained both enhancing and binding activities, although with different efficiencies. The CD4 binder peptides DB3 and DB3-N19, but none of the CD4 nonbinder peptides, enhanced CD4 expression on peptide-treated cells as well as gp120 binding to both CD4+ cells and soluble CD4. These findings strongly suggest that the peptide/CD4 interaction induced an increase in both CD4 expression and CD4/gp120 binding affinity, which in turn mediated the enhancement of viral infection. A model of the structural conformation of DB3 peptide required for its biological activities is discussed.

HIV-1 infection of the thymus: evidence for a cytopathic and thymotropic viral variant in vivo.

As thymocyte infection may represent one of the mechanisms responsible for CD4+ T lymphocyte depletion in HIV-1-infected individuals, we studied the occurrence of HIV-1 infection in the thymus in vivo. Thymus (THYPD) and peripheral blood (PBLPD) primary viral isolates were obtained from an HIV-1-infected patient; restriction pattern analysis revealed the presence of a viral variant (THY) in the thymus isolate, from which biological viral clones containing this variant were obtained by limiting dilution infection of Molt-3 cells. The biological phenotype of the viral isolates and THY clones was studied in different cell lines and primary cultures. PBLPD, THYPD, and THY clones could efficiently infect T cell lines; the thymic variant showed a higher cytopathic activity in T cell lines, and a higher replication capacity in both unfractionated and CD4+CD8(+)-enriched primary thymocytes. Sequence analysis of the viral population patterns in vivo confirmed the presence of the THY variant in the thymic compartment, and revealed that the degree of V3 loop heterogeneity was higher in the thymocytes of the patient than in the peripheral blood lymphocytes. In addition to confirming thymocyte infection in vivo, our data also indicate that a differential distribution of viral variants may occur among different body compartments in a single individual; the emergence of cytopathic and tissue-specific variants in the thymus may play a relevant role in the pathogenesis of HIV-1 disease.

Mother-to-child HIV-1 transmission: quantitative assessment of viral burden as a diagnostic tool and prognostic parameter in HIV-1-infected children.

Polymerase chain reaction was performed in 251 infants born to HIV-1-seropositive mothers to diagnose HIV-1 infection. Assay specificity was invariably > 95%, regardless of age at testing, while sensitivity ranged from 15% in neonates (within 48 h of birth) to > 95% in infants over 1 month of age. Evaluation of viral burden in 43 infected infants by means of quantitative DNA-PCR disclosed that the number of HIV-1 proviruses ranged from 5 to 947 per 100,000 peripheral blood mononuclear cells. Clinical follow-up demonstrated that a high viral burden was associated significantly with disease onset.

Replication and tropism of human immunodeficiency virus type 1 as predictors of disease outcome in infants with vertically acquired infection.

In a series of 97 infants born to mothers who were seropositive for human immunodeficiency virus type 1 (HIV-1), 18 were identified as infected within the first 60 days of life on the basis of viral culture and polymerase chain reaction findings. We studied viral burden in vivo by quantitative polymerase chain reaction and the in vitro replication pattern of the HIV-1 infecting strain by culturing patient cells with normal phytohemagglutinin-stimulated peripheral blood mononuclear cells. According to the lag phase before p24 antigen detection and the level of p24 production on peripheral blood mononuclear cells, HIV-1 isolates from these patients were classified as rapid/high (R/H), slow/high (S/H), and slow/low (S/L). The pattern of HIV-1 replication in vitro was significantly associated with the viral burden in vivo; the range of HIV-1 copies per 10(5) peripheral blood mononuclear cells was 10 to 38, 44 to 314, and 360 to 947 in children with isolates of the S/L, S/H, and R/H types, respectively. Viral tropism was assessed by culturing patient cells under end-point dilution conditions with either CD4+ T-lymphocytes or monocyte-derived macrophages. We found that children with S/L isolates harbored mainly monocytotropic variants; all infants with S/H or R/H isolates had T-lymphotropic variants and, in 7 of 11 cases, monocytotropic or amphitropic variants. All children with R/H isolates had HIV-related symptoms by the age of 4 months, and five had acquired immunodeficiency syndrome by the age of 1 year. At 1 year of age, four and no infants with S/H or S/L isolates, respectively, had HIV-1-related symptoms (p < 0.001), and none had acquired immunodeficiency syndrome (p = 0.006).

Pattern of antibody response against the V3 loop in children with vertically acquired immunodeficiency virus type 1 (HIV-1) infection.

The principal neutralizing domain (PND) of HIV-1, located within the third variable region (V3) of the gp120 envelope protein, is related to the humoral and cellular immune response. We studied the V3 PND-specific antibody response in 30 children with vertically acquired HIV-1 infection by determining the antibodies that bound synthetic peptides derived from the PND of the HIV-1MN, HIV-1SF-2, HIV-1SC, HIV-1IIIB, HIV-1RF, HIV-1ELI, and HIV-1Z6 virus strains. At a standard antigen concentration, we found that most sera (90%) reacted against PNDMN peptide, but 73.3% also cross-reacted against multiple PNDs. A search for high-affinity/avidity antibodies was conducted in an antigen-limited assay; at lower peptide concentrations, cross-reactivity was restricted to PNDMN and PNDSC in 12 of 22 broadly reactive sera. Sequence analysis of the V3 region of HIV-1 isolates indicated that patients with high-affinity/avidity antibodies to PNDMN and PNDSC had a PND with an internal 12-amino acid sequence (serotype-specific domain, SSD) that was highly homologous (> 90%) with the MN and SC SSD. Broadly reactive sera with low-affinity/avidity antibodies showed a lower degree of homology with the SSD sequence of all tested viral strains. The role of anti-PND antibodies in vertical transmission was further studied in 49 children born to HIV-1-seropositive mothers. No statistical correlation emerged between V3 antibodies and HIV-1 transmission, but we found that maternal V3 antibodies were lost soon after birth. This finding may be relevant to a new serological approach to the early diagnosis of vertically transmitted HIV-1 infection.

Vertical transmission of HIV-1: lack of detectable virus in peripheral blood cells of infected children at birth.

OBJECTIVE: To evaluate the time-course of HIV-1 detection in peripheral blood mononuclear cells (PBMC) from newborns at risk of vertically acquired infection. DESIGN AND METHOD: Forty-six infants born to HIV-1-infected mothers were enrolled at birth and examined virologically and clinically in the perinatal period and every 30 days for the first 3 months of life. Follow-up was conducted at intervals of 2-3 months. HIV-1 detection in PBMC was performed using virus culture and polymerase chain reaction (PCR) assay. RESULTS: Only one out of 24 newborns tested within 48 h of delivery and two out of 22 infants tested between 3 and 15 days of age were found to be HIV-1-positive by both PCR and virus culture. Further testing performed between 30 and 60 days of life identified an additional eight HIV-1-positive children. Subsequent viral, immunological and clinical follow-up confirmed PCR and virus culture results obtained in 30-60-day-old children. CONCLUSIONS: Infected infants had detectable levels of HIV-1 in their PBMC at 1 month of age. The negative PCR and virus culture findings in PBMC of newborns indicate strongly that HIV-1 cannot be diagnosed at birth in the majority of cases, and suggests that viral transmission could occur during late pregnancy and/or delivery.

Efficacy and duration of action of oral procaterol in asthmatic children after single administration of different dosages.

A double-blind crossover study was performed to evaluate the bronchodilating effect of different single doses of procaterol (less than 0.5 micrograms/kg, 1.5 micrograms/kg, and placebo) orally administered. Sixteen asthmatic children, age 6-12 years, participated in the trial. Pulmonary function, heart rate, blood pressure, and tremor were evaluated at 30, 60, 90, and 120 min and then hourly for 8 hours after administration. All three doses were therapeutically effective. The 1.5 micrograms/kg dose produced a more sustained bronchodilatation effect, but was also associated with an increase in the incidence of tremors. The 0.5 micrograms/kg dosage may, however, be a good starting dose because it assures a reasonable risk/benefit ratio.

[Bronchial hyperreactivity. I. General concepts]. / Iperreattività bronchiale. I. Concetti generali.

Bronchial hyperreactivity is a condition in which the airways show a much greater bronchoconstrictor response to provocative stimuli than normal. Non-specific bronchial hyperreactivity is a feature of asthmatic patients both allergic and non-allergic. It is proposed that bronchial hyperreactivity is due to the fact that the airways are narrower. In addition changes in the mass of muscle, and changes in the contractility of the muscle may contribute to bronchial hyperreactivity. Moreover bronchial hyperreactivity could be due to increased alpha-adrenergic or parasympathetic activity or to decreased beta-adrenergic or non adrenergic inhibitory activity. Bronchial hyperreactivity can be induced by factors such as infection, inflammation or exposure to allergens.