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Biomedical subjects

G Quintero

Publications and source records attributed to G Quintero.

At least 19 recordsLinked to original sources
PubMed2003

Nitric oxide disrupts VE-cadherin complex in murine microvascular endothelial cells.

Vascular endothelial cadherin (VE-cadherin), which is localized at adherent junctions, is involved in the control of vascular permeability. A growing body of evidence indicates that NO modulates the movement of fluid and proteins out of the vasculature. In this paper, we investigated whether NO can disrupt the VE-cadherin complex. We found that treatment with two NO donors (SIN-1 and SNAP) markedly reduced the amount of VE-cadherin in a murine microvascular endothelial cell line (H5V) as demonstrated by immunoprecipitation analysis, cellular ELISA, and Northern blot analysis. Beta- and gamma-catenins were also found to be affected by the two NO donors. Moreover, the disruption of the complex, induced by NO donors, correlated with increases in vascular permeability using both in vivo and in vitro models. These results clearly demonstrate a role for NO in vascular permeability.

Animals↗
PubMed2001

Albumin-derived advanced glycation end-products trigger the disruption of the vascular endothelial cadherin complex in cultured human and murine endothelial cells.

Endothelial cell (EC) junctions regulate in large part the integrity and barrier function of the vascular endothelium. Advanced glycation end-products (AGEs), the irreversibly formed reactive derivatives of non-enzymic glucose-protein condensation reactions, are strongly implicated in endothelial dysfunction that distinguishes diabetes- and aging-associated vascular complications. The aim of the present study was to determine whether AGEs affect EC lateral junction proteins, with particular regard to the vascular endothelial cadherin (VE-cadherin) complex. Our results indicate that AGE-modified BSA (AGE-BSA), a prototype of advanced glycated proteins, disrupts the VE-cadherin complex when administered to ECs. AGE-BSA, but not unmodified BSA, was found to induce decreases in the levels of VE-cadherin, beta-catenin and gamma-catenin in the complex and in total cell extracts, as well as a marked reduction in the amount of VE-cadherin present at the cell surface. In contrast, the level of platelet endothelial cell adhesion molecule-1 (PECAM-1), which is located at lateral junctions, was not altered. Supplementation of the cellular antioxidative defences abolished these effects. Finally, the loss of components of the VE-cadherin complex was correlated with increases in vascular permeability and in EC migration. These findings suggest that some of the AGE-induced biological effects on the endothelium could be mediated, at least in part, by the weakening of intercellular contacts caused by decreases in the amount of VE-cadherin present.

Acetylcysteine↗
PubMed2001

Analgesic and anti-inflammatory effects of Mangifera indica L. extract (Vimang).

Vimang is an aqueous extract of Mangifera indica used in Cuba to improve the quality of life in patients suffering from elevated stress. To assess its possible analgesic and antiinflammatory effects, the results of a standard extract evaluation are presented. Analgesia was determined using acetic acid-induced abdominal constriction and formalin-induced licking. Antiinflammatory effects were evaluated using carrageenan- and formalin-induced oedema. Vimang (50-1000 mg/kg, p.o.) exhibited a potent and dose-dependent antinociceptive effect against acetic acid test in mice. The mean potency (DE(50)) was 54.5 mg/kg and the maximal inhibition attained was 94.4%. Vimang (20-1000 mg/kg, p.o.) dose-dependently inhibited the second phase of formalin-induced pain but not the first phase. The DE(50) of the second phase was 8.4 mg/kg and the maximal inhibition was 99.5%, being more potent than indomethacin at doses of 20 mg/kg. Vimang (20-1000 mg/kg, p.o.) significantly inhibited oedema formation (p < 0.01 or p < 0.05) of both carrageenan- and formalin-induced oedema in rat, guinea-pigs and mice (maximal inhibitions: 39.5, 45.0 and 48.6, respectively). The inhibitions were similar to those produced by indomethacin and sodium naproxen, p.o. The different polyphenols found in Vimang could account for the antinociceptive and antiinflammatory actions reported here for the first time for M. indica bark aqueous extract.

Acetic Acid↗
PubMed2000

"The lizard in the green bottle": "aging out" of problem drinking among Navajo men.

The Navajo exhibit a number of indicators suggesting the extent of significant problems associated with drinking and alcohol abuse. Measures of alcohol-related mortality and morbidity provide stark testimony regarding the shape and magnitude of problem drinking among the Navajo. While these measures highlight patterns of drinking that often result in social, physical, and psychological pathology, there are other, less noted patterns of Navajo drinking. This paper describes a salient, if often overlooked, pattern of Native American drinking by examining the aging out phenomenon among Navajo men. Using narratives collected from former problem drinkers, this paper describes the factors and motivations associated with this sometimes dramatic change in drinking behavior. Several themes emerge from these narratives that help explain the aging out process. These themes include health concerns, religious involvement, living a traditional Navajo way of life, and the responsibilities and life changes associated with child rearing. This paper not only provides detail on a category of drinker and drinking phenomena that is largely ignored in accounts of Native American drinking, but also illustrates some of the values and meanings attached to drinking cessation and highlights the relation between changes in drinking behavior and stages in life course among Navajo men.

Adult↗
PubMed1999

Risk factors for conduct disorder among Navajo Indian men and women.

OBJECTIVES: To describe the risk factors for conduct disorder before age 15 among Navajo Indians. METHODS: The study was based on a survey of a stratified random sample of adult Navajo Indians between the ages of 21 and 65 living on and adjacent to two different areas of the Navajo Reservation. There were 531 male and 203 female respondents. The average age (SD) of the men was 38.7 (10.5) years and of the women 35.5 (9.0) years. Conduct disorder was diagnosed retrospectively using the Diagnostic Interview Schedule first developed for the Epidemiological Catchment Area study. The responses were combined into a continuous scale. RESULTS: Significant risk factors for increased scores on the conduct disorder scale were: histories of physical and sexual abuse in childhood; abusive maternal drinking; a small number of households per camp; younger age; and being male rather than female. Measures of social status and religion in which subjects were raised were not significant. CONCLUSIONS: Many of the risk factors that are associated with conduct disorder in other populations are also risk factors in the Navajo population. There is suggestive evidence that some of these risk factors have become more common since World War II, raising the possibility that conduct disorder has become more prevalent, as is thought to be the case nationwide.

Adolescent↗
PubMed1999

Alcohol dependence and conduct disorder among Navajo Indians.

OBJECTIVE: The purpose of this study is to examine the association between conduct disorder before age 15 and subsequent alcohol dependence, and to describe the lifetime prevalence of alcohol dependence among Navajo Indian women and men. METHOD: This was a case-control design which included both men (n = 735) and women (n = 351) and in which the Diagnostic Interview Schedule was used for the diagnosis of the lifetime history of alcohol dependence and conduct disorder. Alcohol dependent cases were selected from inpatient and outpatient treatment programs (204 men, 148 women). Whenever possible, controls were matched for age, sex and community of residence and were randomly selected and interviewed until a nonalcohol dependent individual was found. Among the men, there were 374 alcohol dependent controls and 157 nonalcohol dependent controls. Among the women, the figures were 60 and 143, respectively. When combined, the controls comprise samples of the adult male and female populations from which estimates of lifetime prevalence of alcohol dependence, and of the amount of alcohol dependence in the population attributable to conduct disorder, may be inferred. RESULTS: Conduct disorder is a risk factor for alcohol dependence among both men and women. Lifetime prevalence of alcohol dependence in this population is high (70.4% for men and 29.6% for women), but the amount of alcohol dependence in the population attributable to conduct disorder is low. On the other hand, among the alcohol dependent, those with conduct disorder had the most severe alcohol- and nonalcohol-related problems. CONCLUSIONS: The potential limitations of the study are those common to case-control designs, especially biased recall by cases. There are also potential sampling biases among the controls. It is shown that none of the potential biases invalidate the findings, which support the hypothesis that in this population conduct disorder is a risk for alcohol dependence. The implications for primary prevention of alcohol dependence are discussed.

Adolescent↗
PubMed1998

Immunogenicity of four Plasmodium falciparum preerythrocytic antigens in Aotus lemurinus monkeys.

Aotus lemurinus monkeys were immunized with pools of either lipid-tailed peptides injected in PBS or peptides in Montanide ISA-51, all derived from four Plasmodium falciparum pre-erythrocytic antigens, namely, LSA1, LSA3, SALSA, and STARP. These formulations were well tolerated. Their immunogenicity was demonstrated by the induction of both B- and T-cell responses to most of the peptides studied (of the 12, 10 induced antibody production, 9 induced T-cell proliferative responses, and all 12 induced gamma interferon secretion). Immune responses proved to be long lasting, since some were still detectable 210 days after immunization. Of particular importance is the fact that B- and T-cell responses elicited in this way by synthetic peptides were specific for native parasite proteins on P. falciparum sporozoites and liver stage parasites.

Amino Acid Sequence↗
PubMed1997

Treatment of 3rd molar-induced periodontal defects with guided tissue regeneration.

Recent reports provide evidence of increased attachment levels when using guided tissue regeneration (GTR) techniques for the treatment of periodontal defects. Periodontal defects frequently occur at the distal aspect of mandibular 2nd molars which are next to mesioangular impacted 3rd molars that have oral communication. The purpose of this study was to determine whether the use of GTR can enhance probing attachment levels (PALs) following extraction of mesioangular impacted third molars. 12 patients with bilateral soft tissue impacted mandibular 3rd molars entered this split mouth study. After extractions, the previously exposed distal root surface of the 2nd molars were debrided. The defects on the randomly selected experimental sites were covered with expanded polytetraflouro-ethylene (e-PTFE) membrane and the tissue was replaced to cover the membrane. Membranes were removed after 6 weeks. Control sites were treated identically except no membrane was placed. GI, P1I, PD, PAL and BOP records were obtained at 0, 3 and 6 months. The use of barrier material did not provide statistically-significant differences in PAL when comparing experimental versus control sites. Nevertheless, PAL gain was consistently greater at 3 and 6 months when GTR techniques were used in sites with deep impactions.

Adult↗
PubMed1997

Smoking experimentation and initiation among adolescent girls: qualitative and quantitative findings.

OBJECTIVE: To use qualitative and quantitative findings to describe patterns of smoking experimentation and initiation among adolescent girls. DESIGN: Ethnographic in-person interviews, focus groups, telephone interviews, and a survey questionnaire were used over a one-year period. The paper reports on cross-sectional data drawn from a three-year longitudinal study. SUBJECTS AND SETTING: 205 girls participated in the survey and interviews during year 3 of the study. Girls were drawn from two urban high schools in Tucson, Arizona (USA), and were in grades 10 and 11 (mean ages 16 and 17, respectively) during year 3. RESULTS: Overall, 30% (n = 61) of informants reported that they currently smoked, 7% (n = 15) were ex-smokers, and 63% (n = 129) were "non-smokers". The most frequently cited reasons for smoking were stress reduction and relaxation. Several stress-inducing situations, including family environment, social relations with classmates, and schoolwork, are discussed. The notion of peer pressure is re-examined in the light of teenagers' experience that there is little overt pressure to initiate smoking. Consonant with notions of adolescent autonomy, the theme of independence in smoking initiation and continuation permeated girls' narratives about their smoking behaviour. Girls projected the image that they could control their cigarettes rather than have their cigarettes control them. CONCLUSIONS: Smoking prevention and cessation programmes need to address and counter the smoking/relaxation association, which was identified as an important reason for smoking among adolescent girls. Questions typically used in surveys to measure smoking behaviour do not adequately define the smoking experience as described by teenagers.

Adolescent↗
PubMed1994

Bone grafting and guided bone regeneration for immediate dental implants in humans.

This study evaluated bone regeneration and osseointegration of hydroxyapatite (HA) coated and titanium plasma sprayed (TPS) implants placed in sockets immediately after extraction in 36 adults, mean age 55.2 years (range 26 to 81 years). Twelve TPS and 10 HA-coated implants in 20 patients were grafted with demineralized freeze-dried bone allograft (DFDBA), covered with a barrier material, and the facial flap coronally positioned to attain primary closure (experimental). The remaining 11 TPS and 10 HA-coated implants were placed similarly, except that no DFDBA was used (control). Osseous structures were measured at the initial placement and 6-month re-entry surgeries. At the 6-month re-entry, all implants placed were clinically osseointegrated. Bone resorption at the most coronal socket crest was -1.53 mm for the grafted group and -1.59 mm for the control group. Crestal bone apposition of 1.39 mm was noted at the most apical socket crest (ASC) for the grafted group, whereas crestal resorption of -0.11 mm was noted in the ungrafted control group (P < 0.02). Bone fill from the base of the deepest osseous defect was 5.68 mm for the grafted group and 3.18 mm for the control group (P < 0.04). Complete resolution of osseous defects occurred at 15 of 22 sites in the grafted group and at 9 of 21 sites in the control group. Clinical exposure of the barrier material and a subsequent inflammatory response at 27 of 43 sites, requires removal of the material prior to the 6-month re-entry and was associated with significantly more bone loss at the ASC sites (P < 0.01). There was no significant difference for any of the parameters when comparing the TPS with the HA-coated implants.

Adult↗
PubMed1994

Combined dental implant and guided tissue regeneration therapy in humans.

This study evaluated wound healing and osseointegration of dental implants placed in immediate postextraction sockets in humans. Ten healthy adults had one or more teeth extracted and replaced with ITI dental implants, which were centered in the residual socket and covered with a polytetrafluoroethylene membrane and a flap to attain primary closure. Measurements were made to document the relationship of bone to implant at the time of implant placement and at the 6-month reentry. All implants were clinically osseointegrated at the 6-month reentry procedure; narrow bony defects showed complete bone fill, while wide defects showed partial bone fill. There was less bone regeneration in areas of thin cortical bone or preexisting dehiscences and in implant sites with early membrane exposure. Implants placed in immediate postextraction sockets demonstrated successful osseointegration with irregular bone-healing patterns, which were related to variations in existing bony anatomy and socket location.

Alveolar Bone Loss↗
PubMed1993

Displacement chromatography on cyclodextrin silicas. IV. Separation of the enantiomers of ibuprofen.

A displacement chromatographic method has been developed for the preparative separation of the enantiomers of ibuprofen using a beta-cyclodextrin silica stationary phase. The retention behavior of ibuprofen was studied in detail: the log k' vs. polar organic modifier concentration, the log k' vs. pH, the log k' vs. buffer concentration and the log k' vs. 1/T relationships; also, the alpha vs. polar organic modifier concentration, the alpha vs. pH, the alpha vs. buffer concentration and the log alpha vs. 1/T relationships have been determined in order to find the carrier solution composition which results in maximum chiral selectivity and sufficient, but not excessive solute retention (1 < k' < 30). 4-tert.-Butylcyclohexanol, a structurally similar but more retained compound than ibuprofen, was selected as displacer for the separation. Even with an alpha value as small as 1.08, good preparative chiral separations were observed both in the displacement mode and in the overloaded elution mode, up to a sample load of 0.5 mg.

Acetonitriles↗
PubMed1993

Interpretation of linear and computed tomograms in the assessment of implant recipient sites.

Tomography is a radiographic process that produces cross-sectional images of bony structures within the body. The purpose of this study was to evaluate the accuracy of diagnostic measurements made by dental implant team members from linear tomograms of human cadaver mandibles. Five partially edentulous cadaver mandibles were radiographed using linear tomography (LT) and computer-assisted tomography (CT). From the tomograms, each of four team members traced the perceived outer circumference of the mandible and the inferior alveolar canal. Tomogram tracings were compared to each other and to the equivalent CT cross-sectional image to determine the precision of the measurements. One mandible was sectioned to verify the accuracy of the CT images. Repeated measures analysis of variance of the measurements made from the LT and CT scans showed significant statistical differences between team members. Multiple cross-sectional views facilitated identification of the inferior alveolar canal in the majority of CT scans, whereas image blurring inherent to LT resulted in the inability of team members to identify the canal in 14% to 50% of the images. Volume averaging within the CT slice aperture was found capable of producing a magnification error of short dense objects. CT and LT must both be interpreted cautiously because of innate technique objects. CT and LT must both be interpreted cautiously because of innate technique pecularities that can lead to measurement errors. The wide variation in interpretation of the linear tomograms and frequent inability to identify the inferior alveolar canal made this technique less valuable than the reformatted CT when planning dental surgical procedures.

Analysis of Variance↗
PubMed1993

A comparison of polylactic acid granules and decalcified freeze-dried bone allograft in human periodontal osseous defects.

The purpose of this study was to compare the effectiveness of polylactic acid (PLA) granules as an alloplastic grafting material to that of decalcified freeze-dried bone allograft (DFDBA) and a flap procedure for debridement without graft (FPD) when treating periodontal intrabony defects. Ten patients presenting with advanced adult periodontitis, including at least 3 similar periodontal osseous defects (2- and 3-walled), comprised the study group. After completion of a hygienic phase of treatment, measurements were made with calibrated periodontal probes and stents to determine soft tissue recession, probing pocket depths, and probing attachment levels. Each defect was surgically exposed and hard tissue measurements were obtained. Defects were treated with one of the 3 methods above chosen randomly prior to the surgical appointment. Six months postsurgery, soft tissue measurements were repeated and all sites were surgically reentered to obtain hard tissue measurements. All surgical sites healed without clinical complication. The initial pocket depths and initial depth of osseous defects were compared between the groups using ANOVA and no significant differences were found. A mean osseous defect fill of 0.4 mm (11.2%) occurred with the flap procedure for debridement, 3.0 mm (65%) with DFDBA, and 0.1 mm (2.2%) with PLA. Mean crestal bone loss was 1.30 mm for FPD, 0.60 mm for DFDBA, and 1.55 mm for PLA. No statistically significant differences were found in soft tissue recession between groups or in the osseous defect measurement between PLA and FPD. A statistically significant improvement (P < 0.001) was found in the fill of the osseous defects when using DFDBA compared to the initial defect depth and to the other 2 groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Small versus large particles of demineralized freeze-dried bone allografts in human intrabony periodontal defects.

Various particle sizes of demineralized freeze-dried bone allograft (DFDBA) are currently used to treat patients with periodontal osseous defects. However, the effect of particle size on the healing of human intrabony periodontal defects is unknown since there have been no direct clinical comparisons. The purpose of this study was to compare the bony defect resolution obtained using two different particle size ranges of DFDBA. Cortical bone from a single donor was processed and ground to final particle sizes of 250 mu to 500 mu or 850 mu to 1,000 mu using an analytic mill. Paired interproximal intrabony periodontal defects in 11 patients were grafted with DFDBA. Soft and hard tissue measurements were made using an electronic constant-force probe at the initial and reentry surgeries. Treated sites in 10 patients were reevaluated by reentry approximately 6 months postoperatively. Mean bony defect fill was 1.66 mm for the large particle group and 1.32 mm for the small particle group. There was no statistically significant difference in bony fill between defects grafted with the different particle sizes of DFDBA when used in humans.

Adult↗
PubMed1990

Displacement chromatography on cyclodextrin-silicas. III. Enantiomer separations.

The feasibility of preparative enantiomer separations by displacement chromatography on analytical-scale beta-cyclodextrin-silica columns, operated in the reversed-phase mode, was demonstrated using the enantiomers of mephobarbital, hexobarbital, dansylleucine, dansylvaline and dansylphenylalanine as model solutes. The method development scheme (which relies on the determination of the elution-mode retention behavior and the adsorption isotherms of the solutes and the candidate displacers) described in Parts I and II can be used to select the appropriate displacers and the conditions leading to a successful displacement chromatographic separation. The importance of the displacer (both type and concentration) to the success of the displacement chromatographic separation is demonstrated.

Amino Acids↗
PubMed1989

Displacement chromatography on cyclodextrin-silicas. I. Separation of positional and geometrical isomers in the reversed-phase mode.

The retention behaviour of several charged and uncharged solutes on beta-cyclodextrin-silica was studied as a function of the methanol concentration, ionic strength and pH of the eluent in order to develop efficient displacement chromatographic separations for positional and geometric isomers. These retention curves were used to predict the eluent (carrier solvent) compositions that result in solute retentions in excess of k' = 10. The adsorption isotherms of several cationic detergents were determined in these carrier solutions and were found to be convex. The adsorption isotherms of several positional isomers used as test solutes were also determined in these carrier solutions. The adsorption isotherms permitted the development of efficient displacement chromatographic separations for the isomers tested. Column loadings as high as 58 mg were achieved on a regular 4.6 mm I.D. analytical-scale cyclodextrin silica columns.

Chromatography, Liquid↗