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Biomedical subjects

G Marín

Publications and source records attributed to G Marín.

At least 19 recordsLinked to original sources
PubMed2004

Retinal morphology and electrophysiology of two caprimulgiformes birds: the cave-living and nocturnal oilbird (Steatornis caripensis), and the crepuscularly and nocturnally foraging common pauraque (Nyctidromus albicollis).

Oilbirds (Steatornis caripensis) breed in the total darkness of caves and forage at night on fruits. Common pauraques (Nyctidromus albicollis) are crepuscular and nocturnal foragers on flying insects. We examined if their retinal structure and function can be correlated with their types and periods of activity. Electroretinograms (ERGs) were obtained from anesthetized birds in photopic and scotopic conditions to a wide range of light intensities, following which the retinas were processed for histological analysis. Retinal sensitivity is higher in oilbirds than in common pauraques. Under scotopic conditions with maximum flash luminance, the average (+/- 95% CI) b-wave amplitude of oilbirds is double that of common pauraques (500.4 +/- 49.8 and 245.4 +/- 40.9 microV, respectively) but, under photopic conditions, the results are the reverse (common pauraque: 69.4 +/- 18.1; oilbird: 23.0 +/- 4.4 microV). On the other hand, the retina of both species is highly rod-dominated, but rods are highly more numerous in oilbirds than in common pauraques (rods:cones ratio: 123:1 and 5:1, respectively). In oilbirds, rods are largely thinner and their outer segments are 1.0 microm in diameter and 18.6 microm in length. They are distributed over various levels in the photoreceptor layers, an arrangement known for deep-sea fishes, but so far unknown for birds. In common pauraques, rods are patchily distributed and their outer segments are 4.0 microm in diameter and 53 microm in length. The oilbirds rod thinness allows more rods per area unit, and thus to catch more photons per area unit under darkness, while the low cone number suggests that the species has poor daytime vision, which concurs with the species cavernicolous daytime habits. The lower rod number of common pauraques, compared to oilbirds, appears counterbalanced by their patchiness and longer and thicker outer segments to provide high retinal sensitivity. In addition, common pauraques also have a tapetum. These features, combined with a higher proportion of cones, show that common pauraques are well equipped for crepuscular and nocturnal foraging on flying insects in an open environment.

Activity Cycles↗
PubMed2001

A simple method to microinject solid neural tracers into deep structures of the brain.

We have developed an instrument to perform microinjections of solid neural tracers into deep structures of the brain. The instrument consists of a thin hypodermic needle equipped with a movable internal rod, which is connected to a pressure chamber. When a pressure pulse is applied to the chamber, the rod moves forward and back inside the needle, pushing out a solid load previously packed inside the needle tip. By attaching a microelectrode to the instrument, it is also possible to have electrophysiological control of the injection placement. To test the instrument, we microinjected DiI and rhodamine crystals into selected structures of the visual system of pigeons. The results show small, well-defined injection sites, accurately located in the desired targets, together with well-developed anterogade and retrograde transport, selectively originated from the injection sites. This method extends the usage of solid tracers to most structures in the brain and may, in certain cases, be more advantageous than the conventional method of injecting tracer solutions.

Animals↗
PubMed2001

Factor variability of the Center for Epidemiological Studies Depression Scale (CES-D) among urban Latinos.

Establishing comparable measurement properties across different populations or in different population subgroups is a crucial yet often neglected step in instrument development. Failure to have comparable factor structures across groups makes any comparison between groups suspect. Previous analyses of the measurement structure of the Center for Epidemiologic Studies Depression Scale (CES-D) in diverse racial/ethnic populations have resulted in conflicting results. In the present analysis, data from three studies of urban Latinos (N = 1,403) were analyzed using structural equation modeling techniques to (1) fit the original four-factor solution separately in men and women; (2) evaluate configural and metric invariance between men and women; and (3) evaluate the mediating effects of age and acculturation on the fit of this model to the data. Results indicated that the four-factor model proposed by Radloff provided adequate fit to the data for Latina women when age and acculturation were included in the model. The four-factor model did not fit the data for Latino men; thus tests of configural and metric invariance across these two groups failed. We conclude that the CES-D may not measure the same constructs in Latino men and women and that further evaluation of the use of this measure in diverse populations is needed. Additionally, prior to comparison with other groups in which the four-factor solution is observed, the effects of age and acculturation should be controlled in Latinas.

Adult↗
PubMed1998

Ethnic comparison of attitudes and beliefs about cigarette smoking.

OBJECTIVE: To determine if hypothesized differences in attitudes and beliefs about cigarette smoking between Latino and non-Latino white smokers are independent of years of formal education and number of cigarettes smoked per day. DESIGN: Cross-sectional survey using a random digit dial telephone method. SETTING: San Francisco census tracts with at least 10% Latinos in the 1990 Census. PARTICIPANTS: Three hundred twelve Latinos (198 men and 114 women) and 354 non-Latino whites (186 men and 168 women), 18 to 65 years of age, who were current cigarette smokers participated. MEASUREMENTS AND MAIN RESULTS: Self-reports of cigarette smoking behavior, antecedents to smoking, reasons to quit smoking, and reasons to continue smoking were the measures. Latino smokers were younger (36.6 vs 39.6 years, p < .01), had fewer years of education (11.0 vs 14.3 years, p < .001), and smoked on average fewer cigarettes per day (9.7 vs 20.1, p < .001). Compared with whites, Latino smokers were less likely to report smoking "almost always or often" after 13 of 17 antecedents (each p < .001), and more likely to consider it important to quit for 12 of 15 reasons (each p < .001). In multivariate analyses after adjusting for gender, age, education, income, and number of cigarettes smoked per day, Latino ethnicity was a significant predictor of being less likely to smoke while talking on the telephone (odds ratio [OR] 0.41; 95% confidence interval [CI] 0.26, 0.64), drinking alcoholic beverages (OR 0.66; 95% CI 0.44, 0.99), after eating (OR 0.55; 95% CI 0.37, 0.81), or at a bar (OR 0.62; 95% CI 0.41, 0.94), and a significant predictor of being more likely to smoke at a party (OR 1.72; 95% CI 1.14, 2.60). Latino ethnicity was a significant predictor of considering quitting important because of being criticized by family (OR 1.93; 95% CI 1.26, 2.98), burning clothes (OR 1.57; 95% CI 1.02, 2.42), damaging children's health (OR 1.67; 95% CI 1.08, 2.57), bad breath (OR 2.07; 95% CI 1.40, 3.06), family pressure (OR 1.67; 95% CI 1.10, 2.60), and being a good example to children (OR 1.83; 95% CI 1.21, 2.76). CONCLUSIONS: Differences in attitudes and beliefs about cigarette smoking between Latinos and whites are independent of education and number of cigarettes smoked. We recommend that these ethnic differences be incorporated into smoking cessation interventions for Latino smokers.

Adult↗
PubMed1998

[Low energy transcatheter atrial defibrillation in one patient with refractory atrial fibrillation].

Most cases of atrial fibrillation are converted with antiarrhythmic medications or external electric defibrillation. However, in some refractory patients, an internal transcatheter defibrillation must be attempted. We report a 50 years old male with an atrial fibrillation of one year duration that was refractory to pharmacological treatment and in whom external cardioversion was unsuccessful. After the application of a bifasic shock of 10 joules between a catheter in the right atrium and another one located at the coronary sinus, the patient was converted to sinus rhythm. At two months of follow up, the patient continues in sinus rhythm.

Atrial Fibrillation↗
PubMed1997

Changes across 3 years in self-reported awareness of product warning messages in a Hispanic community.

This study investigated the self-reported awareness of product warning messages among independent random samples of Hispanics in San Francisco surveyed from 1989 through 1992. Messages tested were primarily related to cigarette smoking and the consumption of alcoholic beverages. In general, respondents reported low levels of awareness of product warning messages with the exception of those messages dealing with the consumption of alcohol or cigarettes during pregnancy. Nevertheless, there were increases in awareness across years for the alcohol-related warning messages and for one of the cigarette messages, indicating that continued exposure increases awareness of the message. A notable proportion of the respondents reported being aware of a bogus message implying the presence of socially desirable responses in self-reports of message awareness. Gender, education, age and acculturation level of the respondents also showed effects on reported awareness of specific messages. Continued exposure to product warning messages seems useful in producing health-enhancing behaviors among Hispanics.

Acculturation↗
PubMed1997

Changes in reported awareness of product warning labels and messages in cohorts of California Hispanics and non-Hispanic whites.

A cohort of 777 Hispanics and 234 non-Hispanic Whites were interviewed in San Francisco, California, over the telephone in 1991 and again 1 year later. Overall, both Hispanics and non-Hispanic Whites showed an increase in awareness of a general product warning label for beer and wine containers but a decrease in awareness of a product warning label for cigarettes. High- and low-acculturated Hispanics' awareness of a general product warning label increased for alcoholic beverage containers, although highly acculturated Hispanics were more aware. Both Hispanics and non-Hispanic Whites showed an increase in awareness of specific warning messages. The highly acculturated Hispanics showed more increased awareness of specific message than the less acculturated Hispanics.

Adult↗
PubMed1997

Differential perceptions of drinkers of alcoholic beverages by Mexican-Americans and non-Hispanic whites.

Random samples of 534 Mexican-Americans and 616 non-Hispanic Whites were interviewed over the telephone in San José, California and in San Antonio, Texas. Mexican-Americans tended to favor most frequently negative traits for their perceptions of drinkers than non-Hispanic Whites. Excessive drinkers were perceived most frequently in generally negative fashion by members of both ethnic groups although they were also perceived as happy persons. Highly acculturated Mexican-Americans reported perceptions of drinkers and of excessive drinkers that differed from those held by the less acculturated Mexican-Americans and that resembled those held by the non-Hispanic White respondents.

Adult↗
PubMed1996

Perceptions by Hispanics of channels and sources of health messages regarding cigarette smoking.

OBJECTIVE: To identify the perceptions that two communities of urban Hispanics have of various sources and channels of information regarding cigarette smoking and to compare them with those of non-Hispanic whites. DESIGN: Random samples of subjects of both ethnic groups and of both genders were surveyed by telephone to determine the perceived credibility and motivating power of 13 different channels of information and of 14 different sources of cigarette smoking information. SUBJECTS: 544 Hispanics and 542 non-Hispanic whites from San Francisco, California and Houston, Texas, 18-65 years in age, of both genders. RESULTS: Differences in the proportion of respondents assigning various perceived qualities to sources and channels of information regarding cigarette smoking were found to exist across ethnic groups (Hispanics and non-Hispanic whites); the respondents' gender (particularly among Hispanics); and the acculturation level of the Hispanic respondents. Nevertheless, there was a cluster of channels (printed media and television news) and of sources (physicians, people with cancer, friends, and peers) that were positively evaluated by large proportions of the respondents in both ethnic groups. CONCLUSIONS: Hispanics differ from non-Hispanic whites in their evaluation of various possible sources and channels of information about tobacco control. Culturally appropriate interventions for Hispanics need to be designed so as to use those channels and sources of information that are more positively perceived by Hispanics.

Acculturation↗
PubMed1996

Expectancies for driving under the influence of alcohol among Hispanics and non-Hispanic Whites.

A random sample of 1418 (40.8% male) Hispanics and 501 (46.1% male) non-Hispanic Whites were surveyed about their behavioral expectations for driving under the influence of alcoholic beverages (DUI). Hispanics reported more often than Whites that the effects of DUI would be driving carelessly, being angry at other drivers, feeling nervous, losing the respect of friends, feeling guilty, feeling too tired to drive, and losing their self-respect. There were gender differences among Hispanics but not among Whites. Hispanic abstainers reported the likelihood of the various outcomes more frequently than drinkers although drinking status produced no statistically significant differences among non-Hispanic Whites.

Acculturation↗
PubMed1995

Is serum cotinine a better measure of cigarette smoking than self-report?

OBJECTIVES: To address the question of whether serum cotinine is a better measure of cigarette smoking than self-reported behavior by examining the relation of biochemical, physical examination, and depression assessments to self-reported cigarette consumption and serum cotinine in a population-based sample. METHODS: Serum from 743 Mexican American participants in the Hispanic Health and Nutrition Examination Survey (HHANES) categorized by sex and number of cigarettes smoked per day (0, 1 to 9, 10 to 19, > or = 20) was analyzed for cotinine. HHANES results from hematocrit, hemoglobin, red blood cells (RBCs), white blood cells (WBCs), mean corpuscular volume (MCV), iron, transferrin, lead, erythrocyte protoporphyrin (EPP), vitamin E, vitamin A, cholesterol, body mass index (BMI), pulse rate, systolic and diastolic blood pressure (DBP), Center for Epidemiological Depression Scale (CES-D), and Diagnostic Interview Schedule (DIS) depression diagnosis were compared by category of cigarettes smoked per day and serum cotinine. RESULTS: Among women significant correlations were found between cigarettes per day and cotinine, respectively, and hematocrit (r = 0.148, r = 0.338), hemoglobin (r = 0.152, r = 0.342), WBCs (r = 0.160, r = 0.272), and BMI (r = -0.124, r = -0.164). Among men significant correlations were found between cigarettes per day and cotinine, respectively, and WBCs (r = 0.176, r = 0.296), MCV (r = 0.310, r = 0.264), lead (r = 0.105, r = 0.177), and BMI (r = -0.110, r = -0.192). Cotinine, but not cigarettes per day, was significantly correlated with hemoglobin (r = 0.179) and DBP (r = -0.146) in men and EPP (r = -0.135) and cholesterol (r = 0.105) in women. Mean CES-D score was correlated with cigarettes per day for both men (r = 0.106) and women (r = 0.158) but not with cotinine. CES-D caseness (score > or = 16) and a positive diagnosis of depression by DIS was not related to smoking behavior measures among men. Women smokers compared to nonsmokers had higher levels of depression. Multivariate regression models controlling for sex, age, and education indicated that serum cotinine was a significant predictor of hematocrit, hemoglobin, RBCs, WBCs, lead, and DBP; self-reported cigarettes was significant only for MCV. CONCLUSIONS: Serum cotinine may be a better method of quantifying risks from cigarette use in epidemiological studies.

Adult↗
PubMed1995

A research agenda for health education among underserved populations.

This article summarizes the outcome of health education efforts among populations that, due to their cultural heritage, have received limited services. The literature reviewed shows that programs found to be effective in one population cannot be assumed to be equally effective with a different population. An argument is made for the design of culturally appropriate and group-specific interventions which would properly serve the various underserved populations. Research needs to be conducted to identify appropriate approaches and intervention strategies, as well as the group-specific sociopsychological characteristics (attitudes, norms, values, expectancies) that are related to health-damaging and protective behaviors.

Attitude to Health↗
PubMed1995

The role of gender and acculturation on determining the consumption of alcoholic beverages among Mexican-Americans and Central Americans in the United States.

This study analyzed the responses of 391 Mexican-Americans (44.9% males) and 531 Central Americans (40.2% males) who were between 21 and 65 years of age and resided in San Francisco, California. In general, Mexican-Americans were found to have a lower proportion of abstainers (56.8%) than Central Americans (64.4%). Mexican-Americans reported drinking more often and in greater quantities than Central Americans, and the proportion of "high" drinkers was higher among Mexican-American men and women than among the Central American respondents. Despite this diversity in the topography of alcoholic beverage consumption between Mexican-Americans and Central Americans, the role of gender and acculturation on shaping those variables was fairly consistent across groups. The acculturation level of the respondents was found to significantly affect the proportion of abstainers in both groups. Furthermore, gender was an important determinant of frequency, total number of drinks, and volume of drinking for Mexican-Americans and for Central Americans.

Acculturation↗
PubMed1995

Effectiveness of disseminating culturally appropriate smoking-cessation information: Programa Latino Para Dejar de Fumar.

BACKGROUND: The need for a culturally appropriate smoking-cessation intervention for Latinos is based on data on current patterns of tobacco use, possible targeting by the tobacco industry, and the lack of smoking-cessation interventions that are appropriate to the cultural characteristics of Latino smokers. PURPOSE: Our goal was to evaluate the effectiveness of the Programa Latino Para Dejar de Fumar (PLDF) in disseminating smoking-cessation information in San Francisco's Latino community. METHODS: Annual cross-sectional telephone surveys were conducted from 1986 to 1993 of Latino adults, 18-65 years of age, living in census tracts with at least 10% Latinos. Surveys in 1986 and 1987 formed the base line for comparison of PLDF effects. RESULTS: Awareness of a Hispanic smoking-cessation program (odds ratio [OR] = 1.11; 95% confidence interval [CI] = 1.09-1.14), awareness of PLDF specifically (OR = 1.14; 95% CI = 1.10-1.17), awareness of available printed information to help smokers quit (OR = 1.09; 95% CI = 1.06-1.12), and having a copy of the Guía Para Dejar de Fumar (OR = 1.09; 95% CI = 1.05-1.14) were significantly associated with year of survey. In addition, those same variables were significantly associated with a lower acculturation score (respective ORs = 3.95, and 95% CI = 3.57-4.37; OR = 5.40, and 95% CI = 4.86-6.01; OR = 0.63, and 95% CI = 0.58-0.69; and OR = 4.54, and 95% CI = 3.89-5.30). Women were more likely than men to report awareness of a Hispanic smoking-cessation program (OR = 0.88; 95% CI = 0.81-0.96), awareness of PLDF (OR = 0.84; 95% CI = 0.77-0.92), and awareness of available printed information (OR = 0.78; 95% CI = 0.72-0.85). Cigarette-smoking prevalence decreased from 1986 through 1990, stabilized in 1991, and appeared to increase among all groups in 1993. Prevalence of smoking cessation remained stable overall, but it showed a steady increase among less acculturated respondents. CONCLUSION: We conclude that a culturally appropriate community intervention to promote nonsmoking can be successful at disseminating information about smoking cessation. Latino community norms about smoking are evolving, leading to decreased social acceptability.

Acculturation↗
PubMed1994

Estradiol inhibits growth hormone receptor gene expression in rabbit liver.

We studied the ontogeny of GH receptor mRNA levels and the effect of exogenous estradiol administration on GH receptor mRNA levels in rabbit liver. A solution hybridization-RNase protection assay revealed a predominant 370-base long protected band corresponding to the mRNA encoding the transmembrane GH receptor, and a 241-base long protected band, representing about 9.0%, with the predicted size for the truncated form of the GH receptor. To study the developmental profile of GH receptor expression, we studied 12 female rabbits, at ages 1, 3, 5 and 7 months. Maximal GH receptor mRNA levels were observed in 3-month-old animals and decreased in 7-month-old animals. To investigate the effect of estradiol, 8-week-old immature female rabbits were randomly divided into five groups, and received subcutaneous pellets containing either placebo or estradiol at doses of 0.1, 0.5, 1.5 and 5.0 mg for 3 weeks. Exogenous administration of estradiol, at doses that resulted in physiological circulating levels, induced a reduction in GH receptor expression, measured both by GH binding (36 and 46%), and GH receptor mRNA levels (38 and 87%), in animals receiving pellets containing 1.5 and 5.0 mg of estradiol, respectively. We conclude that estradiol decreases GH receptor expression in rabbit liver. The results of our study suggest that there is an inverse relationship between circulating estrogen concentrations and liver GH receptor expression.

Aging↗