RESUMEN
There is an increased interest in exploring the potential of new Lactococcus lactis strains isolated from different natural ecosystems for the production of aroma compounds. Thus, the objective of this study was to screen the aroma generation of Lactococcus lactis strains isolated from different sources by an electronic nose and sensory evaluation for their potential use in starter cheese cultures. Twenty-three strains of Lactococcus lactis were isolated from dairy sources such as artisanal raw-milk cheeses, nondairy sources, and commercial starter cultures (industrial). All the strains were assessed for their ability to produce aromas by an electronic nose and sensory analysis after their incubation in milk. Some phenotypic characteristics of technological importance such as lactose fermentation, proteolytic activity, and citrate utilization were also evaluated. Lactococcus lactis strains showed clear phenotypic differences related to their isolation source. Strains isolated from raw-milk dairy products or commercial starter cultures presented faster lactose fermentation and proteolytic activity than those presented by strains isolated from nondairy sources. Additionally, strains isolated from dairy and nondairy sources presented better citrate utilization than strains isolated from commercial dairy starters. On the other hand, there was not a clear relationship between the source of isolation and the ability of lactococci strains to produce aroma. Principal components analysis of electronic nose data revealed 4 distinctive groups based on aroma profiles. Additionally, odor intensity scores (yogurt-like and Fresco cheese-like) for these 4 groups revealed the nature of their differences. In general, strains from dairy products presented intense yogurt-like and Fresco cheese-like aromas, with the latter being the most intense for one specific strain. On the other hand, the majority of wild strains from nondairy sources presented a stronger yogurt-like aroma, whereas industrial strains presented low intensity for both aroma descriptors. Additionally, an aroma potentiation effect was observed when mixtures of 2 lactococci strains isolated from different sources acted together.
Asunto(s)
Queso/microbiología , Lactococcus lactis/metabolismo , Odorantes/análisis , Adulto , Animales , Bovinos , Femenino , Tecnología de Alimentos , Humanos , Lactococcus lactis/clasificación , Lactococcus lactis/aislamiento & purificación , MasculinoRESUMEN
OBJECTIVE: To establish the frequency of compliance to pharmacological therapy, and to identify non-compliance factors, in relation to metabolic control on patients with type-II diabetes mellitus. MATERIAL AND METHODS: A comparative cross-sectional study was conducted between 1997 and 1998, among 150 type-II diabetic patients, at the Family Medicine Unit No. 33, of the Mexican Institute of Social Security, in Chihuahua, Mexico. Compliance to drug therapy was measured by counting tablets at home. Metabolic control was measured through glycosilated hemoglobin. A questionnaire was given to collect data on factors related to compliance. Statistical analysis consisted of descriptive statistics, Student's t and odds ratios. RESULTS: Pharmacological therapy compliance was 54.2%. Factors associated with non-compliance were elementary schooling and lack of information about the disease. CONCLUSIONS: Pharmacological therapy compliance was low. Factors related to non-compliance can be modified through education.
Asunto(s)
Diabetes Mellitus Tipo 2/tratamiento farmacológico , Hipoglucemiantes/uso terapéutico , Cooperación del Paciente/estadística & datos numéricos , Anciano , Estudios Transversales , Femenino , Hemoglobina Glucada , Hemoglobinuria/diagnóstico , Humanos , Masculino , Persona de Mediana EdadRESUMEN
OBJECTIVE: To identify risk factors associated with tuberculin reactivity in healthcare workers (HCWs). DESIGN: Cross-sectional survey of tuberculin reactivity (2 TU of purified protein derivative (PPD) RT23, using the Mantoux two-step test). SETTING: Two general hospitals located in a region with a high prevalence of tuberculosis and high bacille Calmette-Guerin (BCG) coverage. PARTICIPANTS: Volunteer sample of HCWs. RESULTS: 605 HCWs were recruited: 71.2% female; mean age, 36.4 (standard deviation [SD], 8.2) years; 48.9% nurses, 10.4% physicians, 26.8% administrative personnel; mean time of employment, 10.9 (SD, 6.7) years. PPD reactivity (> or =10 mm) was found in 390 (64.5%). Multivariate analysis revealed an association of tuberculin reactivity with occupational exposure in the hospital: participation in autopsies (odds ratio [OR], 9.3; 95% confidence interval [CI95], 2.1-40.5; P=.003.), more than 1 year of employment (OR, 2.4; CI95, 1.1-5.0; P=.02), work in the emergency or radiology departments (OR, 2.0; CI95, 1.03-3.81; P=.04), being physicians or nurses (OR, 1.5; CI95, 1.04-2.11; P=.03), age (OR, 1.04; CI95, 1.02-1.07 per year of age; P<.001), and BCG scar (OR, 2.1; CI95, 1.2-3.4; P=.005). CONCLUSIONS: Although the studied population has a high baseline prevalence of tuberculosis infection and high coverage of BCG vaccination, nosocomial risk factors associated with PPD reactivity were identified as professional risks; strict early preventive measures must be implemented accordingly.
Asunto(s)
Infección Hospitalaria/epidemiología , Exposición Profesional/análisis , Personal de Hospital/estadística & datos numéricos , Prueba de Tuberculina , Tuberculosis/diagnóstico , Tuberculosis/epidemiología , Adulto , Estudios Transversales , Femenino , Hospitales Generales/estadística & datos numéricos , Humanos , Modelos Logísticos , Masculino , México/epidemiología , Análisis Multivariante , Exposición Profesional/estadística & datos numéricos , Prevalencia , Factores de Riesgo , Población Urbana , Recursos HumanosRESUMEN
The rap mutation in Escherichia coli prevents the growth of bacteriophage lambda. Phage mutations that overcome rap inhibition (bar) have been mapped to loci in the pL operon. We cloned and sequenced three mutations in two of these loci: barIa to the left arm of the lambda attachment site (attP) and barII in the ssb (ea10) gene. The mutations represent single base-pair changes within nearly identical 16-base-pair DNA segments. Each mutation disrupts a sequence of dyad symmetry within the segment. Plasmids carrying a bar+ sequence downstream to an active promoter are lethal to rap, but not rap+, bacteria. The bar sequences isolated from the lambda bar mutants are not lethal. We synthesized a minimal lambda barIa+ sequence, 5'-TATATTGATATTTATATCATT, and cloned it downstream to an inducible promoter. When transcribed, this sequence is sufficient to kill a rap strain.