RESUMO
Pt-Pd core-shell nanoparticles were synthesized using a modified polyol method. A thermal method under refluxing, carrying on the reaction up to 285 °C, has been performed to reduce metallic salts using ethylene glycol as reducer and poly(N-vinyl-2-pyrrolidone) as protective reagent of the formed bimetallic nanoparticles. According to other works, this type of structure has been studied and utilized to successfully increase the catalytic properties of monometallic nanoparticles Pt or Pd. Core-shell bimetallic nanoparticles were structurally characterized using aberration-corrected scanning transmission electron microscopy (Cs-STEM) equipped with a high-angle annular dark field detector, energy-dispersive X-ray spectrometry (EDS), and electron energy-loss spectroscopy (EELS). The high-resolution elemental line scan and mappings were carried out using a combination of STEM-EDS and STEM-EELS. The obtained results show the growth of the Pd shell on the Pt core with polyhedral morphology. The average size of the bimetallic nanoparticles was 13.5 nm and the average size of the core was 8.5 nm; consequently, the thickness of the shell was around 2.5 nm. The growth of the Pd shell on the Pt core is layer by layer, suggesting a Frank-van der Merwe growth mechanism.
RESUMO
SETTING: University hospital and university campus in Lima, Peru. OBJECTIVE: To demonstrate the risk of latent tuberculosis infection (LTBI) in the hospital relative to the community. DESIGN: Prospective cohort study of university students measuring prevalence, boosting, and conversion of tuberculin skin tests (TSTs) among health care students (HCS) and non-health care students (NHCS). RESULTS: Among the HCS relative to NHCS, prevalence of initial positive TST was 20.9% vs. 12.2% (P < 0.001), and conversion rate was 1.1% vs. 0% (P = 0.423) at the 10 mm cut-off and 11.8% vs. 0% at the 6 mm cut-off (P = 0.00005). Multivariate analysis showed that the HCS group had a higher risk of baseline positive TST compared with the NHCS group after controlling for confounding factors (OR 1.7, 95% CI 1.1-2.6). CONCLUSION: HCS are at greater risk than NHCS for having positive baseline TSTs and for TST conversion at the 6 mm cut-off. We conclude that the hospital we studied in Lima, Peru, poses a greater risk than the surrounding community for tuberculosis infection, and greater attention to hospital infection control measures is warranted. A higher rate of skin test boosting among the HCS cohort suggests the possibility of transient, non-progressive LTBI, which merits further study.
Assuntos
Infecção Hospitalar/epidemiologia , Estudantes de Medicina/estatística & dados numéricos , Estudantes de Enfermagem/estatística & dados numéricos , Tuberculose/epidemiologia , Adolescente , Adulto , Feminino , Humanos , Controle de Infecções , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Peru/epidemiologia , Prevalência , Estudos Prospectivos , População Urbana/estatística & dados numéricosRESUMO
OBJECTIVE: To develop a risk assessment algorithm that will increase the identification and treatment of women with cervical infection in rural Haiti. METHODS: Study participants were randomly selected from new patients who accessed services at a women's health clinic in rural Haiti between June 1999 and December 2002. This case-control study included women who tested positive for chlamydia and/or gonorrhoea based on the Gen-Probe PACE 2 laboratory test as cases. Controls were women who tested negative for both of these infections. RESULTS: Women from this area of rural Haiti had a limited level of education and lived in impoverished housing conditions. The sensitivity estimates of Haitian Ministry of Health and WHO algorithms for detecting chlamydia and/or gonorrhoea were generally low (ranging from 16.1% to 68.1%) in this population. Risk scores based on logistic regression models of local risk factors for chlamydia and gonorrhoea were developed and sensitivity estimates were higher for algorithms based on these risk scores (up to 98.8%); however, specificity was compromised. CONCLUSIONS: A risk assessment algorithm to identify women with chlamydia and/or gonorrhoea is more sensitive and less specific than the syndromic management approach advocated by WHO and adapted by the Haitian Ministry of Health. Using a risk assessment tool with high sensitivity based on local risk factors of cervical infection will maximise access to care, improve outcomes, and decrease morbidity in women who have cervical infection in rural Haiti.
Assuntos
Algoritmos , Infecções por Chlamydia/diagnóstico , Gonorreia/diagnóstico , Saúde da População Rural , Adulto , Estudos de Casos e Controles , Infecções por Chlamydia/epidemiologia , Infecções por Chlamydia/terapia , Feminino , Gonorreia/epidemiologia , Gonorreia/terapia , Haiti/epidemiologia , Acessibilidade aos Serviços de Saúde/organização & administração , Humanos , Pobreza , Análise de Regressão , Medição de Risco , Sensibilidade e Especificidade , Resultado do TratamentoRESUMO
SETTING: Lima, Peru. OBJECTIVE: To describe drug resistance profiles of TB isolates from patients at risk for multidrug-resistant tuberculosis (MDR-TB), and to consider the implications of these findings for treatment. DESIGN: Descriptive study of drug susceptibility testing (DST) results for TB isolates from 1680 patients referred for suspicion of MDR-TB between 1996 and 2001. RESULTS: Of 1680 isolates tested, 1144 (68%) were resistant to at least one anti-tuberculosis drug and 926 (55%) were MDR-TB strains. Of 926 MDR isolates, 50 (5%) were resistant to INH and RMP alone, while 367 (40%) were resistant to at least five first-line drugs. We identified 146 unique drug resistance profiles, the most common of which accounted for 11% of drug-resistant isolates. The annual prevalence of isolates with resistance to at least five first-line drugs rose significantly during the study period, from 29% to 37% (P = 0.00086). CONCLUSIONS: This is a group of patients with TB disease among whom the prevalence of a broad spectrum of often highly drug-resistant strains appears to be increasing over time. A single standardized retreatment regimen may be inadequate to cure most patients. Capacity for drug sensitivity testing is essential for development of multiple standardized retreatment or individualized treatment regimens and epidemiological surveillance for planning.
Assuntos
Mycobacterium tuberculosis/efeitos dos fármacos , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Farmacorresistência Bacteriana , Humanos , Isoniazida/farmacologia , Testes de Sensibilidade Microbiana , Peru/epidemiologia , Rifampina/farmacologia , Tuberculose Resistente a Múltiplos Medicamentos/microbiologiaRESUMO
The goals of the current study were to: (1) estimate the prevalence of forced sex among women accessing services at a women's health clinic in rural Haiti; and (2) examine factors associated with forced sex in this population. Based on data from a case-control study of risk factors for sexually transmitted diseases (STDs), a cross-sectional analysis to examine factors associated with forced sex was performed. A number of factors related to gender inequality/socioeconomic vulnerability placed women in rural Haiti at higher risk of forced sex. The strongest factors associated with forced sex in multivariate analyses were: age, length of time in a relationship, occupation of the woman's partner, STD-related symptoms, and factors demonstrating economic vulnerability. The findings suggest that prevention efforts must go beyond provision of information and education to the pursuit of broader initiatives at both local and national levels. At the community level, policy-makers should consider advancing economic opportunities for women who are vulnerable to forced sex. Improving access to community-based income-generating activities may begin to address this problem. However, the viability of these local projects depends largely upon Haiti's 'macro-economic' situation. In order to ensure the success of local initiatives, external humanitarian and development assistance to Haiti should be supported. By broadening the definition of "prevention" interventions, we may begin to address the systemic problems that contribute to the occurrence of forced sex and the increasing incidence of HIV infection throughout the world, such as gender inequality and economic vulnerability. Taking into account factors influencing risk at the local level as well as the macro-level will potentially improve our capacity to reduce the risk of forced sex and the spread of STDs, including HIV infection, for millions of women living in poverty worldwide.
Assuntos
Estupro/estatística & dados numéricos , Serviços de Saúde Rural , População Rural , Adulto , Fatores Etários , Estudos Transversais , Feminino , Haiti/epidemiologia , Humanos , Masculino , Análise Multivariada , Ocupações , Parceiros Sexuais , Infecções Sexualmente Transmissíveis/epidemiologia , Infecções Sexualmente Transmissíveis/prevenção & controle , Fatores SocioeconômicosRESUMO
The goals of the current study are to: (1) estimate the prevalence of sexually transmitted diseases (STDs) among women accessing services at a women's health clinic in rural Haiti; and (2) identify risk factors for STDs in this setting. The design is a case control study, comparing risk factors for women who demonstrated positive laboratory results for chlamydia and/or gonorrhoea to women who tested negative for both of these pathogens. The strongest risk factors for chlamydia and/or gonorrhoea were largely economic variables, with work as a domestic servant increasing the risk by four-fold. Working as a market vendor reduced a woman's risk of having an STD by approximately 45%. Given that economic factors are strongly associated with STD risk in this context, one potential mechanism for reducing the risk of STDs, including HIV, would involve increasing economic opportunities for women in rural Haiti.
Assuntos
População Rural , Infecções Sexualmente Transmissíveis/epidemiologia , Adolescente , Adulto , Fatores Etários , Instituições de Assistência Ambulatorial , Estudos de Casos e Controles , Feminino , Haiti/epidemiologia , Acessibilidade aos Serviços de Saúde , Humanos , Pessoa de Meia-Idade , Análise Multivariada , Ocupações , Prevalência , Fatores de Risco , Parceiros Sexuais , Fatores SocioeconômicosRESUMO
Different from most mammalian species, the optic nerve of the rabbit eye is initially formed inside the retina where myelination of the axons of the ganglion cells starts and vascularization occurs. Astrocytes are confined to these regions. The aforementioned nerve fibers known as medullated nerve fibers form two bundles that may be identified with the naked eye. The blood vessels run on the inner surface of these nerve fiber bundles (epivascularization) and, accordingly, the accompanying astrocytes lie mostly facing the vitreous body from which they are separated only by the inner limiting membrane of the retina. The arrangement of the astrocytes around blood vessels leads to the formation of structures known as glial tufts. Fragments (N = 3) or whole pieces (N = 3) of the medullated nerve fiber region of three-month-old male rabbits (Orictolagus cuniculus) were fixed in glutaraldehyde followed by osmium tetroxide, and their thin sections were examined with a transmission electron microscope. Randomly located discontinuities (up to a few micrometers long) of the basement membrane of the inner limiting membrane of the retina were observed in the glial tufts. As a consequence, a direct contact between the astrocyte plasma membrane and vitreous elements was demonstrated, making possible functional interactions such as macromolecular exchanges between this glial cell type and the components of the vitreous body.
Assuntos
Astrócitos/ultraestrutura , Retina/ultraestrutura , Corpo Vítreo/ultraestrutura , Animais , Astrócitos/fisiologia , Membrana Basal/ultraestrutura , Comunicação Celular , Masculino , Microscopia Eletrônica , Fibras Nervosas/ultraestrutura , Coelhos , Corpo Vítreo/fisiologiaRESUMO
Different from most mammalian species, the optic nerve of the rabbit eye is initially formed inside the retina where myelination of the axons of the ganglion cells starts and vascularization occurs. Astrocytes are confined to these regions. The aforementioned nerve fibers known as medullated nerve fibers form two bundles that may be identified with the naked eye. The blood vessels run on the inner surface of these nerve fiber bundles (epivascularization) and, accordingly, the accompanying astrocytes lie mostly facing the vitreous body from which they are separated only by the inner limiting membrane of the retina. The arrangement of the astrocytes around blood vessels leads to the formation of structures known as glial tufts. Fragments (N = 3) or whole pieces (N = 3) of the medullated nerve fiber region of three-month-old male rabbits (Orictolagus cuniculus) were fixed in glutaraldehyde followed by osmium tetroxide, and their thin sections were examined with a transmission electron microscope. Randomly located discontinuities (up to a few micrometers long) of the basement membrane of the inner limiting membrane of the retina were observed in the glial tufts. As a consequence, a direct contact between the astrocyte plasma membrane and vitreous elements was demonstrated, making possible functional interactions such as macromolecular exchanges between this glial cell type and the components of the vitreous body
Assuntos
Animais , Masculino , Coelhos , Astrócitos , Retina , Corpo Vítreo , Astrócitos , Membrana Basal , Comunicação Celular , Microscopia Eletrônica , Fibras Nervosas , Corpo VítreoRESUMO
A comparative study was carried out in which 66 leprosy patients with ulcers were randomly divided in two groups of 33 patients each: Group A (experimental group) was treated with ketanserin gel (2%) and group B with clioquinol cream and/or Lassar paste during a three month period. At the end of the study, when ulcer sizes in the two groups were compared, the group treated with topical ketanserin showed superior results (p < 0.001 using Kolmogorov-Smirnov's test). We conclude that the drug is useful as coadjuavant treatment for healing ulcers in these patients.
Assuntos
Ketanserina/uso terapêutico , Hanseníase/complicações , Antagonistas da Serotonina/uso terapêutico , Úlcera Cutânea/tratamento farmacológico , Administração Tópica , Adulto , Idoso , Feminino , Humanos , Ketanserina/administração & dosagem , Masculino , Pessoa de Meia-Idade , Antagonistas da Serotonina/administração & dosagem , Resultado do TratamentoRESUMO
A practical method for the radioisotope labeling aimed at the study of the proliferative behavior of astrocytes was described. It consisted in injecting 20 microCi of (3)H-thymidine into the vitreous body and tracing by autoradiography labeled astrocytes located both inside and outside the retina, e.g. optic nerve and neighboring parts of the central nervous system. The paraffin sections were immunostained for glial fibrillary acidic protein (GFAP) previous to autoradiographic processing. The semiquantitative analysis of labeled astrocytes was carried out on autoradiographs of semithin sections of rabbits killed as early as 6 h and as late as 3 months after the single intravitreal injection of (3)H-thymidine. Compared with the technique of labeling astrocytes by systemic administration (single injection or continuous infusion) of (3)H-thymidine into small animals, the method described herein has the following outstanding features: (i) it is much more economical in terms of the amount of labeled precursor used per animal; (ii) the labeling of the astrocytes is obtained as early as 6 h and remains up to 3 months after injection; (iii) the immunolabeling of the astrocytes is compatible with autoradiography; (iv) it is less risky to the experimental animal and to the environment; (v) it can be used in animals much larger than rats or mice.
Assuntos
Astrócitos/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Retina/efeitos dos fármacos , Timidina , Trítio , Corpo Vítreo/efeitos dos fármacos , Animais , Artefatos , Astrócitos/citologia , Astrócitos/metabolismo , Autorradiografia , Axônios/efeitos dos fármacos , Axônios/metabolismo , Axônios/ultraestrutura , Divisão Celular/fisiologia , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Núcleo Celular/ultraestrutura , Proteína Glial Fibrilar Ácida/metabolismo , Imuno-Histoquímica , Masculino , Coelhos , Retina/citologia , Retina/metabolismo , Timidina/farmacocinética , Fatores de Tempo , Trítio/farmacocinética , Corpo Vítreo/metabolismoRESUMO
The purpose of the present investigation was to establish a method for the morphological characterization and location of the several types of astrocytes in the rabbit retina. Whole retinas were incubated with unlabeled antibody to glial fibrillary acidic protein (GFAP) and, afterwards, treated with secondary antibody labeled according to the requirements for the visualization of the antigen-antibody reaction either with the confocal or transmission electron microscope. Specimens treated similarly to the latter were osmium enhanced and analyzed with scanning electron microscopy (SEM). The different immunohistochemical approaches led to the conclusion that the cells selectively visualized with the SEM are astrocytes. The higher resolution and depth of focus of this instrument allowed a better morphological characterization and a more precise location of the astrocytes in the several levels of the inner portion of the rabbit retina. The method described herein, in which pre-embedding immunohistochemistry for GFAP on rabbit retinas was associated with osmium enhancement and examination with SEM, proved to be reliable and efficient for the morphological characterization and location of astrocytes.