The use of the CHAID algorithm for determining tourism segmentation: A purposeful outcome.

This paper considers the most suitable market segment(s) from an environmental and local economic development perspective in the specific context of visits to natural environments. More specifically, the paper explores the distinctions and differences between tourists (non-residents) and residents with regard to visit behavior at natural attractions. By using the CHAID algorithm, a decision tree is constructed for means of transportation which serves as a key factor in the segmentation process. However, such a tree for visitors' resident or non-resident status cannot be built as a first explicative variable, unless it is statistically forced. Once it is forced, the tree opens in several sub-segments, for non-residents and residents alike. Finally, it allows understanding of the means of transportation used by visitors according to their geographical origin as well as a set of added independent variables: accommodation establishment, length of stay, season, and other demographic variables (educational level, gender, and age). Also, more importantly, we have obtained segments with no overlap configured according to all the aforementioned variables. This is a very strong result from a methodological point of view and for policy makers in destination settings.

[Polymorphisms in cystathionine beta-synthase and methylenetetrahydrofolate reductase genes as risk factors for cerebral vascular disease]. / Polimorfismos en los genes cistationina beta-sintasa y metilentetrahidrofolato reductasa como factores de riesgo de enfermedad vascular cerebral.

BACKGROUND AND OBJECTIVE: High plasma total homocysteine (tHcy), low dietary intake of folate and other B vitamins, and genetic polymorphisms related to the metabolism of homocysteine may interactively contribute to the risk of cerebral vascular disease (CVD). We explored interrelations between total homocysteine levels and mutations in genes for the two key enzymes in methionine-homocysteine metabolism. PATIENTS AND METHOD: We analyzed two polymorphisms, C677T in the MTHFR gene and 844ins68 in the CBS gene. We assessed their association with fasting homocysteine in 64 patients with CVD, and in 159 controls. RESULTS: No differences in CBS and MTHFR genotype frequencies between cases and controls were found (C677T p = 0.87 and 844ins68 p = 0.63), nor was a particular CBS and MTHFR genotype associated with an elevated risk of CVD. None of the genotypes defined by the CBS and MTHFR variants studied showed an association with elevated fasting homocysteine concentrations (C677T p = 0.07 and 844ins68 p = 0.47). CONCLUSIONS: We did not find any indication that genetic variation in the CBS and MTHFR genes are associated with homocysteine-related risk of CVD, hence needing further investigation. The contributions to total plasma homocysteine levels of the common mutations of genes coding for the enzymes controlling homocysteine metabolism are modest.

Polimorfismos en los genes cistationina â -sintasa y metilentetrahidrofolato reductasa como factores de riesgo de enfermedad vascular cerebral / Polymorphisms in cystathionine â -synthase and methylenetetrahydrofolate reductase genes as risk factors for cerebral vascular disease

FUNDAMENTO Y OBJETIVO: La interacción entre altas concentraciones de homocisteína plasmática, baja ingesta de folato y otras vitaminas B, y la presencia de polimorfismos en genes relacionados con el metabolismo de la homocisteína, puede aumentar el riesgo de padecer una enfermedad cerebrovascular (ECV). Se ha estudiado la interrelación entre la concentración de homocisteína y la presencia de mutaciones en dos genes relacionados con el metabolismo metionina homocisteína. PACIENTES Y MÉTODO: Se han analizado dos polimorfismos, C677T en el gen MTHFR y 844ins68 en el gen CBS, en 64 pacientes con ECV y 159 controles sanos, estableciendo su posible asociación con la homocisteína total. RESULTADOS: No se han encontrado diferencias en las frecuencias enotipificadas de los genes CBS y MTHFR entre casos y controles (C677T, p = 0,87, y 844ins68, p = 0,63). Ningún genotipo estuvo asociado con un mayor riesgo de ECV. Tampoco se pudo establecer su asociación con un aumento de la concentración de homocisteína total (C677T, p = 0,07, y 844ins68, p = 0,47). CONCLUSIONES: No se ha observado ningún indicio de asociación entre las variables genotipificadas en los genes CBS y MTHFR y la concentración de homocisteína que supongan un aumento del riesgo de ECV. La contribución de estas mutaciones al incremento de la concentración de homocisteína es modesto

BACKGROUND AND OBJECTIVE: High plasma total homocysteine (tHcy), low dietary intake of folate and other B vitamins, and genetic polymorphisms related to the metabolism of homocysteine may interactively contribute to the risk of cerebral vascular disease (CVD). We explored interrelations between total homocysteine levels and mutations in genes for the two key enzymes in methionine-homocysteine metabolism. PATIENTS AND METHOD: We analyzed two polymorphisms, C677T in the MTHFR gene and 844ins68 in the CBS gene. We assessed their association with fasting homocysteine in 64 patients with CVD, and in 159 controls. RESULTS: No differences in CBS and MTHFR genotype frequencies between cases and controls were found (C677T p = 0.87 and 844ins68 p = 0.63), nor was a particular CBS and MTHFR genotype associated with an elevated risk of CVD. None of the genotypes defined by the CBS and MTHFR variants studied showed an association with elevated fasting homocysteine concentrations (C677T p = 0.07 and 844ins68 p = 0.47).CONCLUSIONS: We did not find any indication that genetic variation in the CBS and MTHFR genes are associated with homocysteine related risk of CVD, hence needing further investigation. The contributions to total plasma homocysteine levels of the common mutations of genes coding for the enzymes controlling homocysteine metabolism are modest

Prevalencia de bacterias enteropatógenas en Costa Rica / Prevalence of enteropathogenic bacteria in Costa Rica

In a study made of the bacterial etiology of diarrheal cases in Costa Rica, pathogenic strains of E. coli were rarely found but Shigella were found in the same proportion as in the other areas of Latin America. Salmonella occurred frequently in urban centers. Concomitant examination in children of similar age group but without diarrhea suggested that enteropathogenic. E. coli was an important cause of the intestinal symptoms; Shigella prevalence, although it increases with increasing age, loses importance as the cause of symptoms; and in the urban centers Salmonella was important as the cause of symptoms only among children under six months of age(AU)

Salmonelas en la carne de consumo molida / Salmonella en chopped meat for human consumtion

Four hundred and thirty-four samples of chopped meat were examined for Salmonella serotypes; of these, 244 samples came from five rural butcher shops in the Barba Canton, and 190 from five butcher shops in the capital city of San José, in Costa Rica

Micro-organisms of the genus Salmonella were isolated from 40 (9,2 percent) of the samples. More samples from butcher shops in the city (17,9 percent positive) proved to be contaminated than from the rural butcher shops (2,5 percent positive). Possible causes of this differences are discussed

In all, 43 strains were isolated, and 10 serotypes identified, predominant among them being S. anatum and S. derby; the significance of this finding is discussed. Three samples were contaminated with two Salmonella serotypes, and Shigella boydii 5 was isolated from another(AU)

Salmonelas en la carne de consumo molida / Salmonella en chopped meat for human consumtion

Four hundred and thirty-four samples of chopped meat were examined for Salmonella serotypes; of these, 244 samples came from five rural butcher shops in the Barba Canton, and 190 from five butcher shops in the capital city of San José, in Costa Rica

Micro-organisms of the genus Salmonella were isolated from 40 (9,2 percent) of the samples. More samples from butcher shops in the city (17,9 percent positive) proved to be contaminated than from the rural butcher shops (2,5 percent positive). Possible causes of this differences are discussed

In all, 43 strains were isolated, and 10 serotypes identified, predominant among them being S. anatum and S. derby; the significance of this finding is discussed. Three samples were contaminated with two Salmonella serotypes, and Shigella boydii 5 was isolated from another(AU)

Prevalencia de bacterias enteropatógenas en Costa Rica / Prevalence of enteropathogenic bacteria in Costa Rica

In a study made of the bacterial etiology of diarrheal cases in Costa Rica, pathogenic strains of E. coli were rarely found but Shigella were found in the same proportion as in the other areas of Latin America. Salmonella occurred frequently in urban centers. Concomitant examination in children of similar age group but without diarrhea suggested that enteropathogenic. E. coli was an important cause of the intestinal symptoms; Shigella prevalence, although it increases with increasing age, loses importance as the cause of symptoms; and in the urban centers Salmonella was important as the cause of symptoms only among children under six months of age(AU)