Biomedical subjects

Catarina Pereira

Publications and source records attributed to Catarina Pereira.

3 recordsLinked to original sources

PubMed2006

Dehydrogenation of ribitol with Gluconobacter oxydans: production and stability of L-ribulose.

l-Ribulose is an important chiral lead molecule used for the synthesis of, among others, l-ribose, a high-value rare sugar used in the preparation of antiviral drugs. These drugs--nucleoside-analogues--gain importance in the treatment of severe viral diseases, like those caused by the HIV or hepatitis virus. In this study, factors that may have an impact on l-ribulose production with Gluconobacter oxydans and on the stability of l-ribulose were investigated. A bioconversion-type process, using washed resting cells, was chosen to produce l-ribulose from ribitol. In this process, the cell production and bioconversion phase were separated. The former was first optimized and a maximum cell mass of 1.5 g CDWL(-1) could be produced. For the bioconversion phase, the aeration level of the system proved to be one of the most critical factors; a maximal production rate of 15.7 g L(-1)h(-1) or 5.9 g(g CDW)(-1)h(-1) of l-ribulose could be reached. Furthermore, resting cells were found capable of completely converting ribitol solutions of up to 300 g L(-1) within 30 h, although the kinetics indicated a rather low affinity of the dehydrogenase enzymes for the substrate.

Acetobacter↗

PubMed2005

Application of cluster analysis in prevention of coronary heart disease.

INTRODUCTION: Coronary heart disease is one of the principal causes of death and morbidity in the western world, and particularly in Portugal. OBJECTIVES: This study's aim was to investigate coronary disease risk factors, differentiating lifestyles and behavioral habits which are associated with onset of the disease. METHODS: The experimental population was divided into two groups: an experimental group (n=30)--male subjects, aged 40-75 years, who suffered a first coronary event in the previous 20 days; and a control group (n=30)--male subjects, aged 40-75 years, who presented no coronary problems. Individuals with a clinical history of any other chronic disease were excluded from the sample. Data were obtained through questionnaires. Data analysis consisted of both traditional statistical analysis (Student's t test) and cluster analysis. The latter technique enables behavioral patterns that will or will not induce coronary heart disease to be distinguished. RESULTS: The Student's t test revealed significant differences (p < or = 0.05) between the experimental and control groups for the following variables: nutrition and dietary habits, smoking, stress and psychosocial factors, hereditary factors and total risk factors. The risk level of all these factors was higher in the experimental group. Cluster analysis applied to 19 variables enabled three behavioral patterns to be identified that may induce the disease, characterized by high risk indices in specific variables, and one behavioral pattern that tends to prevent development of coronary heart disease, which is characterized by low levels of risk factors. CONCLUSIONS: Coronary heart disease appears to be related to lifestyle and habits. Analysis of the three high-risk behavioral patterns enabled priority areas to be established for preventive measures against coronary heart disease. These are: stress, irritability and depression, smoking, sedentary lifestyle and nutrition (excessive consumption of salt, sugar and alcohol).

Adult↗

PubMed2005

Thermoregulation and aging.

Worldwide climate changes, bringing long-lasting higher and lower extremes of temperature, are leading to an increased mortality rate in elderly people due to cardiocirculatory dysfunction. The ability of young adults to make physiological adjustments when exposed to low or high temperatures decreases with age. The purpose of this literature review is to assess the dysfunctions occurring in the elderly as a result of their reduced responsiveness to thermal stress. Physiological responses to cold environment induce a reversible plasma water shift from the intravascular to the interstitial and intracellular level due to peripheral vasoconstriction. This phenomenon occurs on exposure to cold water or air and even during facial cooling by a cold wind. Above-normal temperatures induce a reduction in intravascular water due to sweating. Older people are less able to cope with the increased viscosity of blood and are thus more liable to suffer a cardiocirculatory accident.

Adaptation, Physiological↗