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Biomedical subjects

C Félix

Publications and source records attributed to C Félix.

11 recordsLinked to original sources
PubMed2006

Matrix effects on the optical response of silver nanoclusters.

We report absorption spectra for Ag(7), Ag(9), and Ag(11) in an argon matrix grown at a temperature of 28 K and compare them with previous spectra of the same species measured in matrices of argon grown at lower temperatures as well as in neon matrices. We discuss the discrepancies in the light of the matrix crystallinity and show that this leads to an understanding of the influence of the matrix on the optical response of small clusters.

Journal Article↗
PubMed2001

Ag8 fluorescence in argon.

The fluorescence of Ag8 in an argon matrix and in argon droplets is reported. This is the first unambiguous assignment of the fluorescence of a metal cluster larger than the tetramer, indicating that the excited state lifetime is longer than previously thought. It is discussed as a possible result of a matrix cage effect. The excitation spectrum is compared with two-photon-ionization measurements of Ag8 in helium droplets and to known absorption data. The agreement is excellent. We propose that the excited states relax rapidly through vibrational coupling to a long-lived state, from which the fluorescence occurs.

Journal Article↗
PubMed1992

Effect of social class and nutrient intake on height and plasma insulin-like growth factor in Andean Equadorian children.

The purpose of this study was to assess the validity of insulin-like growth factor (IGFI) determination as an index of nutritional status and growth in Equadorian schoolboys. Plasma IGFI was measured in 144 healthy boys, 9 years old, who were classified by their social class in four groups: 1 (n = 29); 2 (n = 49); 3 (n = 28); 4 (n = 8). Children in groups 1 and 2, of the lower socio-economic class, had significantly reduced caloric and protein intakes compared to children in groups 3 and 4 (P less than 0.01). Mean heights were significantly lower in groups 1 and 2 (P less than 0.001 and less than 0.05, respectively). The mean plasma IGFI in group 1 was 561 +/- 64 mU/ml and significantly lower than that in groups 2-4 (872 +/- 75, 986 +/- 94, and 1238 +/- 190 mU/ml in groups 2, 3 and 4, respectively) (P less than 0.01). The effect of caloric and nitrogen supplementation was studied in 36 children taken from groups 1 and 2 combined, and divided into three subgroups; they were given (1) an animal protein supplement of 18 g/day with 860 kcal/day (n = 12), (2) a vegetable protein supplement of 17.8 g/day based on a traditional Andean food with 862 kcal/day (n = 12), and (3) a placebo (n = 12). The IGFI levels increased significantly after 7 and 14 days in both subgroups 1 and 2. These results demonstrate that plasma IGFI reflects the nutritional status and responds to a short-term diet supplementation. It may provide a reliable means of assessing the effect of nutritional programs intended to improve the growth of children in underdeveloped countries.

Body Height↗
PubMed1991

Increased frequency of HLA-DR3 and complotype SC01 in Mexican mestizo patients with amoebic abscess of the liver.

Our preliminary study (31 patients) of HLA frequencies and amoebic abscess of the liver (AAL) in Mexican mestizos was extended to include 110 patients with this condition. The previously found increase in HLA-B16 was not confirmed, but the frequency of HLA-DR3 was again found significantly increased in patients with AAL when compared to the normal, ethnically matched control population, both in its isolated (35.5% vs 12.7%) and in the HLA-A2, DR3 haplotypic version (20.9% vs 4.5%). Moreover, seven of the 17 HLA specificities that were found to be individually different at P (yet not at PC) level in patients with AAL when compared to the control population, were actually HLA-DR3 containing haplotypes. HLA-DR3 may thus encode a risk factor(s) for AAL, at least in the Mexican mestizo population. Furthermore a significant increase in the complotype SC01 and its haplotypic version SC01, DR4 were identified in 45 non selected patients with AAL when compared to normal controls (31.1% vs 6.7% and 17.8% vs 0% respectively). Even though a relationship between allelic forms of complement components and their function has not been fully established, this complotype could represent a risk factor as well, since complement appears to play a role in host defence against amoebic invasion. Finally, no extended haplotype preference was found in these AAL patients.

Adult↗
PubMed1991

Prenatal diet, nutrient intake and pregnancy outcome in urban Ecuadorian primiparas.

A nutritional survey was conducted in an urban public maternity hospital, Hospital Gineco-Obstétrico Isidro Ayora (HGOIA), located in Quito, Ecuador. Seventy-four primiparas in the third trimester of pregnancy were recruited to assess the influence of sociedemographic factors on food patterns and nutrient intake, and the interrelationship between prenatal nutrient intake, maternal weight gain and pregnancy outcome. Results of the regression analysis indicated that maternal education was the factor most strongly associated with nutrient intake, followed by monthly per capita income. Maternal nutrient intake was next analyzed and compared with the WHO (1974, 1985) and NRC (1980) recommended daily allowances. Results also indicated the average daily intake of energy, protein, phosphorus, vitamins C and A, thiamine, riboflavin, and niacin met or exceeded the recommended daily allowances. Dietary calcium and iron intake, however, were below recommendations. Sodium and fat intake were both relatively high. Higher dietary fat intake was associated with increased birth weight, while lower protein intake was associated with increased risk of delivering a low-birth weight baby. Maternal weight gain during the third trimester predicted baby birth weight and height but not head circumference.

Feeding Behavior↗
PubMed1991

Vascular prostacyclin production in Andean women with pregnancy-induced hypertension.

Although prostacyclin (PGI2) production in the umbilical artery is known to be reduced in pregnancy-induced hypertension (PIH), little information is available about its production in maternal vascular tissues. We measured 6-keto-prostaglandin F 1 alpha generation in the umbilical and omentum arteries of 24 Andean women divided into three groups: 1) 8 normal pregnant women, 2) 8 cases with clinical evidence of severe PIH, and 3) 8 normotensive non-pregnant women. The normal pregnant group (232 +/- 172 pg mg-1 2h-1) and the non-pregnant control group (237 +/- 146 pg mg-1 2h-1) showed similar PGI2 production in the omentum arteries, whereas the PIH group showed lower PGI2 generation (P less than 0.05) than the normal patients both in the umbilical (697 +/- 377 vs 1528 +/- 291 pg mg-1 2h-1) and omentum (132 +/- 73 vs 232 +/- 172 pg mg-1 2h-1) arteries. PGI2 production was 6.8 times lower in the omentum arteries than in the umbilical arteries. The data confirm and extend the view of the occurrence of reduced PGI2 production in the maternal-fetal vascular tissues of women with severe PIH.

Arteries↗
PubMed1990

[HLA antigens, complement types, and amebic liver abscess in Mexican mestizos].

The association between parasitic diseases, and antigens of the major histocompatibility complex in man (HLA) has been poorly studied. The only study of the association between the HLA system and amebic abscess of the liver was performed by our group, and revealed a significant increase in HLA-BI6 and HLA-DR3 in patients with amebic abscess of the liver. The present study covered a larger number of patients and controls (110 of each) and it confirmed the association with HLA-DR3, it failed to confirm the association with HLA-BI6.

Adult↗