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Biomedical subjects

F Díaz

Publications and source records attributed to F Díaz.

At least 37 records · Page 2Linked to original sources
PubMed2001

Intestinal damage in gastroschisis is independent of the size of the abdominal defect.

The intestinal damage in gastroschisis (GS) has been attributed to a narrow abdominal wall defect (AWD), among other causes, but this causal effect is difficult to prove in humans. The present experimental study was done to ascertain the damaging effect of clinically extrapolable mild and moderate constriction at the AWD on the intestine of fetuses with GS. AWDs of two different sizes were carried out in the fetal rabbit model: small-ring GS (1.5x bowel diameter, SRG) and large-ring GS (3x bowel diameter, LRG); a group of unoperated littermates served as controls. Fetal body weight, intestinal length and weight, bowel diameter and wall thickness, and histology were checked 7 days later. No statistical difference was found in body weight and bowel diameter among the groups. Intestinal length, weight, and wall thickness were significantly different in the GS groups compared to the controls, but no difference was found between the GS groups. Histology did not show venous stasis, ischemic lesions, or differences in the degree of edema between groups SRG and LRG. Mesothelial hyperplasia was seen in both GS groups. The intestinal changes in length, weight, diameter, wall thickness, and histology in GS should thus not be attributed to the diameter of the AWD.

Abdominal Muscles↗
PubMed2001

Effect of the relevance and position of the target stimuli on P300 and reaction time.

The relationships among stimulus relevance and the position of target stimuli in a sequence with the P300 component of event related brain potentials and reaction time were investigated. An auditory oddball series was presented to 42 healthy, young, right-handed female participants. In the series, participants were to ignore the standard stimuli and count the deviants from 1 to 6. When reaching the count of 6, they had to restart their count from 1 again. While counting, half of the sample had to press a key after the deviants, numbers 1, 2 and 3, but not after the numbers 4, 5 and 6. The other half of the sample had to press the key when numbers 4, 5 and 6 rather than when numbers 1, 2, 3 appeared. The P300 amplitude of the more relevant (count and press) stimuli was higher than that of the P300 amplitude of the less relevant (count only) stimuli. This is associated with a greater allocation of cognitive resources to the more relevant stimuli. An interaction was also found between the position of the target stimuli in a sequence and the stimulus relevance, which is attributed to the cognitive preparation. Furthermore, the reaction time tended to increase along the sequence of the more relevant stimuli, due perhaps to an increase in physical fatigue.

Adolescent↗
PubMed2001

Expression of proinflammatory cytokines and their inhibitors during the course of spontaneous bacterial peritonitis.

The aim of this work was the evaluation, in cirrhotic patients with noninfected ascites and with spontaneous bacterial peritonitis (SBP), of serum and ascitic fluid levels of proinflammatory cytokines [interleukin (IL) 1-beta, tumor necrosis factor alpha (TNF-alpha), and IL6] and antiinflammatory compounds [IL10, soluble IL-1 receptor antagonist (sIL-1Ra), soluble receptors of TNF p55 and p75 (sTNFR55 and sTNFR75), and soluble receptor of IL6 (sIL6R)], as well as their relationship with the outcome of the infection in those with SBP. These molecules were assayed by ELISA in noninfected cirrhotic controls (n = 15), patients with SBP (n = 32), and healthy controls (n = 20). Serum levels of IL6 and of the majority of antiinflammatory mediators, sIL1Ra, sTNFR75, and sIL6R, were higher in control cirrhotic patients compared to healthy subjects. SBP was associated with significantly elevated ascitic fluid levels of every one of the proinflammatory cytokines compared to those in cirrhotic controls. Also, serum levels of IL10 and both TNF receptors and ascitic fluid levels of sIL1Ra and sTNFR55 were higher in patients with SBP compared to cirrhotic controls. Ascitic fluid levels of proinflammatory cytokines decreased rapidly after resolution of the infection; however, nonsignificant changes were detected in ascitic fluid concentrations of antiinflammatory molecules. Thus, elevated levels of antiinflammatory compounds both in noninfected cirrhotic patients and in patients with SBP suggest a regulatory control of the inflammatory process by these molecules in liver cirrhosis patients.

Antigens, CD↗
PubMed2001

Serial analysis of serum and ascitic fluid levels of soluble adhesion molecules and chemokines in patients with spontaneous bacterial peritonitis.

The aim of this work was the evaluation of serum and ascitic fluid levels of chemokines (IL-8, growth-regulated oncogene (Gro-alpha), and monocyte chemotactic protein-1 (MCP-1)), and of soluble adhesion molecules (P-selectin, E-selectin, L-selectin, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1)) in patients with spontaneous bacterial peritonitis (SBP). These compounds were serially analysed in serum and ascitic fluid by ELISA in patients with SBP (n = 20), non-infected cirrhotic controls (n = 12), and healthy controls (n = 15). Infected and non-infected cirrhotic patients showed significantly higher serum levels of adhesion molecules. SBP was associated with significantly higher serum and ascitic fluid levels of IL-8, Gro-alpha and ICAM-1 and with ascitic fluid concentrations of MCP-1. Significantly elevated serum levels of both ICAM-1 and VCAM-1 were detected in patient non-survivors after SBP. Thus, higher ascitic fluid levels of chemokines could be implicated in the peritoneal infiltrate in patients with SBP. Prognostic significance can be attributed to serum levels of ICAM-1 and VCAM-1 in these patients.

Ascitic Fluid↗
PubMed2001

Synthesis and hypolipidemic activity of modified side chain alpha-asarone homologues.

A series of homologues of alpha-asarone (1), containing variable size and functionality on the side chain attached to the aromatic ring, has been subjected to a study of structure-activity relationship. For most of the prepared derivatives, either with a carbonyl (8a-8e), a hydroxy group (9a-9e), or with a conjugated double bond (10a-10d), significant effects on serum lipoprotein cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides were displayed. The results showed an enhancement of the hypocholesterolemic activity as the length of the chain is decreased. Theoretical conformational and electrostatic potential analyses of I and olefins 10 suggest unfavorable steric interactions in the bulky superior side-chain homologues as the deactivating biological effect.

Allylbenzene Derivatives↗
PubMed2001

Plasma beta-endorphin levels in obese and non-obese patients with polycystic ovary disease.

The aim of this study was to determine the influence of body weight on circulating plasma levels of beta-endorphin and insulin in women with polycystic ovary disease (PCOD), as well as the correlation between the plasma levels of beta-endorphin and insulin. One-hundred and sixty-seven consecutive subjects with PCOD were recruited, 117 of whom had normal weight (body mass index (BMI) < 25) while 50 were obese (BMI > 25). A venous blood sample was taken and plasma concentrations of beta-endorphin, insulin, gonadotropins, prolactin, progesterone, 17 beta-estradiol, estrone, androgens, dehydroepiandrosterone sulfate and sex hormone-binding globulin (SHBG) were measured. Mean beta-endorphin and insulin plasma levels were significantly higher (p < 0.05) in obese PCOD women than in non-obese ones. Correlation analysis showed a positive association between insulin and beta-endorphin, beta-endorphin and BMI (and weight), insulin and BMI (and weight), and a negative correlation was found between insulin and SHBG. A weak association was found between beta-endorphin and luteinizing hormone (LH) in peripheral plasma. Stratified and linear regression analysis showed that plasma beta-endorphin concentrations correlate more with BMI than with insulinemia.

Adolescent↗
PubMed2001

Ammonia removal in a deep reclaimed wastewater reservoir before agricultural reuse.

An experimental study has been carried out to determine the ammonia removal in a deep reclaimed wastewater reservoir of 50,000 m3. The reservoir is part of the Reuse System of Reclaimed Wastewater of South Tenerife (Spain). The study has been conducted under batch mode operation, in three different periods (winter, spring-summer and winter-spring), with an average storage time of 85 days. Vertical profiles of temperature, dissolved oxygen and pH were determined together with NH3-N, NO2-N and NO3-N concentrations at different points and different depths in the reservoir. Maximum removal efficiency was obtained during the winter periods, in absence of stratification and with good mixing conditions throughout the water column. During these periods, nitrification took place in some extension, favoring the ammonia removal. Average NH3-N concentrations in the reservoir were calculated and apparent first-order rate constants were determined for different stratification conditions. Although ammonia nitrogen could be used as nutrient in the agricultural reuse, its removal from reclaimed wastewater could be useful in order to diminish the chlorine needs for disinfection.

Agriculture↗
PubMed2001

Effect of treatment with different doses of 17-beta-estradiol on insulin receptor substrate-1.

CONTEXT: Ovarian hormones modulate insulin sensitivity, but their exact role remains unclear. OBJECTIVE: We tried to determine whether different doses of 17-beta-estradiol cause changes in the regulation of insulin receptor substrate (IRS-1) levels, and if so, the possible implications in insulin sensitivity. DESIGN: Ovariectomized rats were treated with different doses of 17-beta-estradiol at 6, 11 and 16 days. MAIN OUTCOME MEASURES: Immunoprecipitation and Western blotting for IRS-1 were performed in different tissues. RESULTS: We found that estradiol treatment has an influence on the amount of IRS-1 but that it acts in different ways depending on the tissue studied, on the length of treatment, and on the doses employed. CONCLUSIONS: Our results suggest that low concentrations of 17-beta-estradiol could be responsible for the upregulation of insulin receptor substrate 1, increasing insulin sensitivity in muscle and adipose tissue. However, insulin receptor substrate 1 is downregulated with high concentrations of 17-beta-estradiol, thus these high hormone plasma levels could favour insulin resistance in peripheral tissues. The role of 17-beta-estradiol seems to modulate insulin receptor substrate 1 levels in insulin dependent tissues, but in a different manner in each tissue. These novel findings are important for improving knowledge about the possible risk for insulin resistance in women taking oral contraceptives or receiving hormone replacement therapy at menopause.

Adipose Tissue↗
PubMed2000

Hepatic dysfunction due to parvovirus B19 infection.

Parvovirus B19 has been associated with different diseases. However, hepatic involvement has rarely been reported in adult patients with parvovirus B19 infection. Herein, we report two adult patients with hepatic dysfunction associated with acute parvovirus B19 infection. We believe that hepatic involvement in the setting of parvovirus B19 infection is more common than suspected, and that antibodies against this agent should be routinely measured in patients with hepatic dysfunction of unclear etiology.

Adult↗
PubMed2000

Substance use and sexual risk behavior: understanding their association among four ethnic groups of Latino men who have sex with men.

PURPOSE: To explore the association between substance use in conjunction with sex and unprotected anal sex among Colombian, Dominican, Mexican, and Puerto Rican men who have sex with men (MSM), considering ethnicity, acculturation, and mediating variables. METHODS: A New York City convenience sample of 307 men provided information on past year's sexual behavior, substance use, acculturation, attendance at bars, discos, and parties, self-worth, machismo, and sensation seeking. RESULTS: Alcohol use and drug use were positively associated with unprotected anal sex, particularly with casual partners. Different rates of substance use among the four ethnic groups were found, but were not significant when adjusting for acculturation. Among men who engaged in both unprotected and protected anal sex, substance use was not more common on unprotected occasions than on protected occasions. Attendance at bars, clubs, etc. was not associated with unprotected anal sex. Sensation seeking, self-worth, and machismo were related to substance use and unprotected anal sex. In multivariate analyses, the substance use/unprotected sex association remained when adjusting for ethnicity, acculturation, partner type, attendance at bars, and personality variables. IMPLICATIONS: Substance use and unprotected sex are associated among these Latino MSM. However, there does not appear to be a simple causal relationship between the variables. Several other variables co-vary with these factors but did not statistically explain their association.

Acculturation↗
PubMed2000

Purification and characterization of an adhesin from Pasteurella haemolytica.

We purified an adhesin from Pasteurella. haemolytica by affinity chromatography using glutaraldehyde treated rabbit erythrocytes stroma. The adhesin is a protein of 68 kDa, as determined by SDS-PAGE, and the most abundant amino acids constituting this protein were Gly, Ser, Glx, and Ala, and low concentrations of Cys, Met, and Tyr residues were also found. The N-terminal sequence of the adhesin is ANEVNVYIYKQPYLI. No carbohydrate residues were detected. The adhesin agglutinated rabbit erythrocytes but when the latter were desialylated or pronase treated the agglutinating activity was abolished. The agglutinating activity of the adhesin was inhibited with N-acetyl-D-glucosamine (GlcNAc), and in a lesser degree with N-acetyl-neuraminic acid (NeuAc). GalNAc, N-glycolyl-neuraminic acid, N-deacetylated GlcNAc, or neutral sugars do not modify the activity of the adhesin. The equatorial -OH on C4 and the NH-acetylated group on C2 from GlcNAc, as well as the 4-OH and NH-acetylated group on C5 from NeuAc seem to be responsible for the interaction with the adhesin. The protein is divalent cation-dependent and thermolabile. As for the agglutinating activity, the adhesion of P.haemolytica to tracheal cell-cultures was inhibited by GlcNAc, NeuAc or the purified adhesin, strongly suggesting that the P.haemolytica adhesin plays an important role in infection.

Adhesins, Bacterial↗
PubMed2000

Role of 17beta-estradiol and/or progesterone on insulin sensitivity in the rat: implications during pregnancy.

The mechanism for the development of insulin resistance in normal pregnancy is complex and is associated with serum levels of both progesterone and 17beta-estradiol. However, it remains unclear whether estrogens alone or progestins alone can cause insulin resistance, or whether it is a combination of both which produces this effect. We attempted to determine the role played by progesterone and/or 17beta-estradiol on the phenomena of sensitivity to insulin action that take place during pregnancy in the rat. Ovariectomized rats were treated with different doses of progesterone and/or 17beta-estradiol in order to simulate the plasma levels in normal pregnant rats. A euglycemic/hyperinsulinemic clamp was used to measure insulin sensitivity. At days 6 and 11, vehicle (V)- and progesterone (P)-treated groups were more insulin resistant than 17beta-estradiol (E)- and 17beta-estradiol+progesterone (EP)-treated groups. Nevertheless, at day 16, the V, EP and E groups were more resistant to insulin action than the P group. On the other hand, the V, EP and E groups were more insulin resistant at day 16 than at day 6, whereas the P group was more insulin resistant at day 6 than at day 16. Our results seem to suggest that the absence of female steroid hormones gives rise to a decreased insulin sensitivity. The rise in insulin sensitivity during early pregnancy, when the plasma concentrations of 17beta-estradiol and progesterone are low, could be due to 17beta-estradiol. However, during late pregnancy when the plasma concentrations of 17beta-estradiol and progesterone are high, the role of 17beta-estradiol could be to antagonize the effect of progesterone, diminishing insulin sensitivity.

Analysis of Variance↗
PubMed2000

Frequent use of lubricants for anal sex among men who have sex with men: the HIV prevention potential of a microbicidal gel.

OBJECTIVES: This study assessed frequency of rectal lubricant use, opinions about rectal microbicidal gels, and willingness to participate in acceptability trials of rectal microbicides among Latino men who have sex with men (MSM). METHODS: Latino MSM (N = 307) living in New York City were surveyed from October 1995 through November 1996. Eleven Latino MSM participated in a focus group. RESULTS: Among those having anal sex during the prior year, 93% used lubricants (59% always and 74% in at least 80% of sexual encounters) regardless of condom use. Of the 29 men who practiced anal sed but did not use condoms, 90% used lubricants with similar frequency. Of those using lubricants, 94% used at least 1 teaspoon per occasion. A transparent product, free of smell and taste, was favored. Of the MSM in the sample, 92% said that they would use a lubricant with an anti-HIV microbicidal agent, and 87% expressed interest in participating in an acceptability trial. Product and dispenser preferences also were discussed. CONCLUSIONS: A rectal lubricant with microbicidal properties appears acceptable and desirable to Latino men who have anal sex with other men.

Administration, Rectal↗
PubMed1999

Ageing-related changes in the processing of attended and unattended standard stimuli.

Responses to standard stimuli presented during a dichotic listening task were analysed in 53 healthy subjects from 20 to 86 years of age. The aim was to determine whether N1 and P2 waves showed changes attributable to attention or more general changes underlying the electrophysiological processing of such stimuli under attended and unattended conditions. N1 was larger at midline frontal and central electrodes in middle-aged and in elderly subjects without changes in its topographical distribution. These changes were independent of attention. P2, which was also larger in middle-aged and in elderlies, showed scalp distribution changes depending on the direction of attention. The present results indicate the existence of general ageing-related changes in the processing of attended and unattended standard stimuli which may be related to inhibitory deficits (N1) and to changes in the orientation of electrical sources (P2).

Acoustic Stimulation↗
PubMed1999

Secretion of IFN-gamma by bovine peripheral blood mononuclear cells stimulated with Mycobacterium bovis protein fractions obtained by isoelectric-focusing.

Due to the complexity and variety of biological effects found in Mycobacterium bovis (M. bovis) proteins analyzed solely on a molecular weight (MW) basis, we approached the purification of M. bovis proteins through their isoelectric point (pI). Twenty M. bovis culture filtrate protein extract (CFPE) isoelectric focused (IEF) protein fractions, confined between pI3 and 10, were isolated. The MW of the major proteins isolated in the various fractions correlated with protein already reported 14-, 18-, 20-, 25-, 31-, 38-, 45-, 64-, 67- and 70 kDa by SDS-PAGE. Since several different pI fractions showed proteins of the same MW we tested the ability of all IEF fractions to stimulate interferon-gamma (IFN-gamma) production by peripheral blood mononuclear cells (PBMC) isolated from cattle with well defined M. bovis tuberculosis (TB) infection. In animals with few lesions IFN-gamma inductive IEF fractions were in the acid range. As the number of lesions increased, neutral fractions were also inductive. Some fractions with relatively few proteins induced as much IFN-gamma production as others with abundant proteins. None of the 20 IEF fractions enhanced IFN-gamma production by anergic cells. We conclude that IFN-gamma production in diseased animals is induced mainly by acidic mycobacterial proteins and that the response towards these proteins is enhanced as the disease progresses, what coincides with higher PPD reactivity. However, the IFN-gamma production in anergic status was severely affected. We found that this cytokine production is spontaneous and antigen-independent.

Animals↗
PubMed1999

Phosphorylation protects sperm-specific histones H1 and H2B from proteolysis after fertilization.

At intermediate stages of male pronucleus formation, sperm-derived chromatin is composed of hybrid nucleoprotein particles formed by sperm H1 (SpH1), dimers of sperm H2A-H2B (SpH2A-SpH2B), and a subset of maternal cleavage stage (CS) histone variants. At this stage in vivo, the CS histone variants are poly(ADP-ribosylated), while SpH2B and SpH1 are phosphorylated. We have postulated previously that the final steps of sperm chromatin remodeling involve a cysteine-protease (SpH-protease) that degrades sperm histones in a specific manner, leaving the maternal CS histone variants unaffected. More recently we have reported that the protection of CS histones from degradation is determined by the poly(ADP-ribose) moiety of these proteins. Because of the selectivity displayed by the SpH-protease, the coexistence of a subset of SpH together with CS histone variants at intermediate stages of male pronucleus remodeling remains intriguing. Consequently, we have investigated the phosphorylation state of SpH1 and SpH2B in relation to the possible protection of these proteins from proteolytic degradation. Histones H1 and H2B were purified from sperm, phosphorylated in vitro using the recombinant alpha-subunit of casein kinase 2, and then used as substrates in the standard assay of the SpH-protease. The phosphorylated forms of SpH1 and SpH2B were found to remain unaltered, while the nonphosphorylated forms were degraded. On the basis of this result, we postulate a novel role for the phosphorylation of SpH1 and SpH2B that occurs in vivo after fertilization, namely to protect these histones against degradation at intermediate stages of male chromatin remodeling.

Amino Acid Sequence↗