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Biomedical subjects

I Arias

Publications and source records attributed to I Arias.

At least 19 recordsLinked to original sources
PubMed2005

Observation of spontaneous self-channeling of light in air below the collapse threshold.

We report the observation of the self-guided propagation of 120 fs, 0.56 mJ infrared radiation in air for distances greater than 1 m. In contrast with the known case of filamentation, in the present experiment the laser power is lower than the collapse threshold. Therefore the counterbalance between Kerr self-focusing and ionization induced defocusing as the stabilizing mechanism is ruled out. Instead, we find evidence of a process in which the transversal beam distribution reshapes into a form similar to a Townes soliton, with the particularity of a very high stability. We include numerical support for this conclusion.

Journal Article↗
PubMed2001

A fast and sensitive method for measuring picomole levels of total free amino acids in very small amounts of biological tissues.

In the present study we describe a simple and fast method to measure the concentration of total free amino acids in very small amounts of biological tissues. The procedure described here is based on the reaction of free amino acids with o-phthaldialdehyde (OPA) in the presence of a reducing agent, beta-mercaptoethanol (MET), to give a complex which can be measured by fluorescence. It is a very rapid process and has the same reliability as the conventional ninhydrin method of Moore and Stein but is about 500 times more sensitive. The sensitivity of the new protocol is such to permit the determination with high reliability of very small amounts of free amino acids at picomole levels, either in a standard amino acid mixture or in biological tissues, without chromatographic separation of the amino acids. It is particularly useful when the amount of the sample is very low, e.g. on a single pituitary or pineal gland of small animals or on single cells, such as oocytes or eggs, as well as single ganglions or axons of marine invertebrates.

Amino Acids↗
PubMed2001

Psychological abuse and posttraumatic stress disorder in battered women: examining the roles of shame and guilt.

Psychological abuse among battered women has been relatively understudied. However, battered women's reports in the existing qualitative and quantitative research suggest that the effects of psychological abuse can be even more damaging than the effects of physical abuse. The current study attempted to clarify the relationship between psychological abuse and posttraumatic stress disorder (PTSD) within a sample of battered women by statistically controlling for the effects of physical abuse. This study also explored the affective experiences of shame and guilt as important variables in the development of PTSD in battered women. This investigation replicated previous work suggesting that battered women are very much at risk for a diagnosis of PTSD and suggests that clinicians and researchers may need to focus on psychological abuse as a predictor of PTSD symptomatology. The current findings encourage attention to shame reactions in battered women and suggest new directions in the study of PTSD for other traumatized populations.

Adult↗
PubMed1999

Translation to Spanish, reproducibility, and cross-cultural adaptation of the Miller-Rahe Recent Life Change Questionnaire in Venezuela.

OBJECTIVE: To translate into Spanish a version of the Miller-Rahe Recent Life Change Questionnaire and to adapt it to Venezuelan cultural values. METHODS: The Spanish version and cross-cultural adaptation of the Miller-Rahe Recent Life Change Questionnaire was done following recently proposed guidelines to preserve semantic, idiomatic, and conceptual equivalence in translations of health assessment instruments. We performed one or more translations into the new language, as well as back-translation, test-retest reliability, and weighting score for the translated instrument. RESULTS: A Spanish version of the Recent Life Change Questionnaire was obtained. Validity of translations was demonstrated with a significant agreement for the nonliteral translations (kappa value = 0.97, P < 0.05). The conceptual equivalence was demonstrated by significant agreement in the back-translations (kappa value = 0.84, P < 0.05). The translated instrument met acceptable levels of reliability, as assessed by Spearman's rank correlation coefficients (> 0.60 for all categories of the questionnaire). The cross-cultural adaptation of the translated instrument required addition and exclusion of items as well as changes of the ranking and scaling of life units in the original questionnaire. CONCLUSION: A valid and reliable Spanish version of the Miller-Rahe Recent Life Change Questionnaire was produced and adapted to Venezuelan cultural values.

Adult↗
PubMed1999

Psychological abuse: implications for adjustment and commitment to leave violent partners.

The contribution of psychological abuse, beyond that of physical abuse, to battered women's psychological adjustment and their intentions to terminate their abusive relationships was examined. Sixty-eight battered women residing in shelters for battered women provided information on their: (1) physical and psychological abuse; (2) psychological symptomatology; (3) strategies for coping with and perceptions of control over partner violence; and (4) intentions to return to their abusive partners. Multiple regression analyses indicated that frequency and severity of physical abuse was not a significant predictor of posttraumatic stress disorder (PTSD) symptomatology nor of women's intentions to terminate their abusive relationships. However, psychological abuse was a significant predictor of both PTSD symptomatology and intentions to permanently leave abusive partners even after controlling for the effects of physical abuse. PTSD symptomatology moderated the relationship between psychological abuse and intentions to terminate the abusive relationships: resolve to leave the abusive partner as a function of level of psychological abuse was significant only among women characterized by low levels of PTSD symptomatology. Greater use of emotion-focused coping strategies, absolutely and relative to problem-focused coping, had direct effects on PTSD symptomatology. However, neither coping nor perceptions of control moderated the effects of psychological abuse on psychological adjustment. The results of the investigation suggested that psychological abuse and ensuing PTSD symptomatology are important variables to assess among physically battered women.

Adaptation, Psychological↗
PubMed1998

Prevalence of traumatic events and peritraumatic predictors of posttraumatic stress symptoms in a nonclinical sample of college students.

This study investigated lifetime prevalence of traumatic events and posttraumatic stress disorder (PTSD) symptoms among 937 college students. Participants rated their lifetime experiences of traumatic events and, in response to their "most stressful" event, completed measures of objective stressor dimensions, PTSD, and peritraumatic reactions. Approximately 67% of respondents reported at least one traumatic event. An estimated 4% of the full sample (12% of traumatized individuals) met PTSD criteria within the past week. After controlling for vulnerability factors and objective characteristics, peritraumatic reactions remained strongly predictive of PTSD symptoms. Results are discussed with respect to immediate reactions to traumatic events as potential precursors of PTSD symptomatology.

Adolescent↗
PubMed1998

Angiotensin-converting enzyme gene polymorphism determines the antiproteinuric and systemic hemodynamic effect of enalapril in patients with proteinuric renal disease. Austrian Study Group of the Effects of Enalapril Treatment in Proteinuric Renal Disease.

Angiotensin-converting enzyme (ACE) inhibitors are known to reduce blood pressure and proteinuria in a variety of different glomerular diseases. Nonetheless, a marked interindividual difference in the efficacy of these agents exists. The activity of the ACE and therefore of the renin-angiotensin-aldosterone system (RAAS) has been shown to be under genetic influence. Patients with a deletion genotype at the intron 16 of the ACE gene have been shown to exhibit higher activity of plasmatic ACE when compared to patients with the insertion genotype. We therefore studied prospectively the hemodynamic and antiproteinuric effect of a 6-month therapy with enalapril in patients with biopsy-proven proteinuric glomerular diseases and the DD (n = 10) and ID/II (n = 26) genotype. Although patients with the DD genotype received a slightly higher dose of enalapril, blood pressure and proteinuria did not change significantly. However, both were significantly reduced in the II/ID group after 10 weeks and 6 months of therapy. Creatinine clearance decreased steadily in DD patients. In II/ID patients, creatinine clearance was reduced significantly after 10 weeks of therapy but increased again thereafter and the value at 6 months was again comparable to the one obtained in the DD patients. We conclude from our study that the ACE genotype influences the blood pressure-lowering and antiproteinuric effect of enalapril in patients with proteinuric glomerular disease.

Adult↗
PubMed1998

[Primary Sjögren syndrome. Study of a population of patients at the Hospital Universitario de Caracas, Venezuela].

Sjögren's syndrome is an autoimmune exocrinopathy of unknown etiology. It is characterized by a chronic inflammatory process that leads to functional impairment and destruction of lachrymal and salivary glands. There is a primary and a secondary form of the disease; the latter accompanies a well defined connective tissue disease. As far as we know, there are no previous reports of primary Sjögren's syndrome in Venezuela. The main purpose of this study was to present the clinical findings and outcome of a population of patients diagnosed and followed in our hospital. A population of fifty-four patients predominantly females (96%) with a mean age of 42 (range 24 to 84) was studied. The presence of articular symptoms was the most common extraglandular manifestation (87%), followed by enlargement of parotideal glands (52%). Parotid enlargement and renal disease were observed with a higher frequency than previously reported in the literature. Recurrent enlargement of parotideal glands has been related to lymphoid malignant transformation in these patients. Our findings seem to suggest that the pattern of clinical expression of primary Sjögren's syndrome may be influenced by the genetic make-up of the population under study, and possibly by local environmental influences. Two of our cases developed pseudolymphoma, a transitional stage between the benign lymphoproliferation of primary Sjögren's syndrome and lymphoma. Furthermore, in this relatively small sample six patients have died during a short follow-up period, suggesting a potentially more aggressive course of the disease in our patients.

Adult↗
PubMed1997

Individual differences in self-appraisals and responses to dating violence scenarios.

Previous research suggests that certain types of self-appraisals may predispose individuals to be more or less tolerant of relationship violence. The current study investigates two such appraisals, self-esteem and self-attributions, as correlates of women's responses to hypothetical episodes of relationship violence by their dating partners. Undergraduate women involved in dating relationships (N = 145) reported global self-esteem, attributions for hypothetical partner aggression, and probable responses to the aggression. Results showed that self-esteem and self-attributions emerged as correlates of intentions to forgive violence, whereas only self-attributions emerged as a correlate of intentions to dissolve the relationship. The association between self-attributions and intentions to exit a violent relationship was fully mediated by intentions to forgive the partner. Because self-appraisals may inform prevention programs for women who may experience relationship violence, clinical implications are discussed.

Adolescent↗
PubMed1996

Angiotensin-converting enzyme polymorphism in patients with terminal renal failure.

An insertion/deletion polymorphism has been described for the gene that encodes the angiotensin-converting enzyme. The deletion allele is associated with higher angiotensin-converting enzyme plasma levels, which ultimately might lead to increased angiotensin II concentrations. Because angiotensin II is a mediator for progressive renal injury, this study determined the frequency of distribution of the angiotensin-converting enzyme insertion/deletion polymorphism in 106 hemodialysis patients and in a group of 95 healthy control patients. There was no difference between the two groups as far as the distribution of the insertion and deletion allele was concerned. Of the total hemodialysis population, 26.4% exhibited the deletion/deletion genotype, as compared with 37.9% of the healthy control population. Also, when patients with terminal renal failure as a result of glomerular disease were analyzed separately, the frequency of the deletion/deletion genotype was identical to that of the control group. Furthermore, the frequency of hypertension, coronary artery disease, left ventricular hypertrophy, and dilated cardiomyopathy, were analyzed according to the angiotensin-converting enzyme genotype, but the deletion allele could not be defined as a risk factor in the study's hemodialysis population. It was therefore concluded that the angiotensin-converting enzyme insertion/deletion polymorphism is not a major risk factor for development of end-stage renal failure. Additionally, in hemodialysis patients, there is no association between the risk for cardiovascular diseases and the angiotensin-converting enzyme genotype.

Adult↗
PubMed1995

Control, coping, and victimization in dating relationships.

This study examined the role of perceived control and coping in mediating the relationship between violent and nonviolent negative relationship events and women's experience of distress. Results based on the responses of 48 victims of dating relationship violence and 74 nonvictims indicated that perceived control was negatively related to distress for victims but not nonvictims. While both victims and nonvictims engaged in both problem- and emotion-focused coping, and different patterns of coping emerged for the two groups, appraisals of control were not related to choice of coping strategies for violent or nonviolent negative relationship events. Psychological distress was not significantly predicted by coping strategies or the interaction of control and coping for either type of event of for either group. These results suggest that control appraisals may be particularly important in reducing distress for victims. However, appraisals of perceived control may place them at increased risk for abuse in the long run, as victims are unlikely to be able to control the violence as it escalates in both severity and frequency over time.

Adaptation, Psychological↗
PubMed1995

Excuses, excuses: accounting for the effects of partner violence on marital satisfaction and stability.

For both theoretical and practical reasons, it is important to understand processes that lead to marital dissatisfaction and dissolution among women who are targets of relationship violence. Because attributional tendencies may often forecast marital behavior and because alcohol use is often seen as providing an excuse for deviant behavior, we examine two potential moderators of the associations between husband violence and wife marital outcomes: wife attributional style and husband problem drinking tendencies. A community sample of married couples (N = 66) completed a comprehensive battery of marital assessments. Results suggested that responsibility attributions moderated the association between husband violence and wives' marital dissatisfaction but exerted a direct effect on wives' disposition toward divorce. Husband problem drinking moderated the impact of husband violence only on wives' disposition toward divorce. As would be expected from an "excuse" model of the associations between violence and marital outcomes, violence had less of an impact on marital satisfaction and divorce ideation when wives attributed responsibility for negative spouse behavior as external to their husbands and when husbands were problem drinkers, respectively.

Adult↗
PubMed1992

Relationships among marital investment, marital satisfaction, and marital commitment in domestically victimized and nonvictimized wives.

The present investigation examined the association between marital investment, marital satisfaction, and commitment to marriage among physically abused women. We applied an investment model and a social learning model to understanding victimized wives' satisfaction and commitment to stay married. Thirty wives who reported physical abuse and 58 nonabused wives completed measures of marital stability, investment in marital problem solving, and dyadic adjustment. Investment in marital problem solving was assessed by having subjects indicate how much energy that they have put into solving 34 common marital problems and whether their efforts were successful or not successful. Consistent with a social learning model but counter to an investment perspective, correlational and multiple regression analyses for each group revealed that failed investment was significantly related to lower, not greater, commitment. Group differences also emerged. Whereas nonabused wives' commitment was related to their dyadic adjustment abused wives' commitment was related to their level of failed investment. Results are consistent with the notion that women may remain in abusive relationships because of psychological entrapment.

Adult↗
PubMed1990

Effects of alcohol, gender, and role of spouses on attributions and evaluations of marital violence scenarios.

The effects of spouses' alcohol consumption, gender, and role in a marital dispute on observers' attributions of responsibility and evaluations of the spouses were examined. A major goal of the investigation was to determine whether the effects of alcohol on attributions and evaluations are gender related or role related. Based on the participation of 115 male and 181 female undergraduate students, the results partly supported the role-related effects of alcohol consumption. Respondents rated both husband and wife more negatively when they were depicted as the perpetrators than as victims. Alcohol consumption did not affect evaluations of the spouses as perpetrators. However, drinking by the husband and wife before their victimization was associated with more negative evaluations than when their victimization was not preceded by drinking. It is argued that alcohol consumption of the victim and not the perpetrator may play a more significant legitimizing role for spousal violence.

Adult↗
PubMed1989

Prevalence and stability of physical aggression between spouses: a longitudinal analysis.

Community couples (N = 272) were assessed in a longitudinal study of early marriage. More women than men reported physically aggressing against their partners at premarriage (44% vs. 31%) and 18 months (36% vs. 27%). At 30 months, men and women did not report significantly different rates of aggression (32% vs. 25%). However, using either the self-report or the partner's report, the prevalence of aggression was higher for women than men at each assessment period. Modal forms of physical aggression for both men and women were pushing, shoving, and slapping. Conditional probability analyses indicated that the likelihood of physically aggressing at 30 months given that one had engaged in such aggression before marriage and at 18 months after marriage was .72 for women and .59 for men. Furthermore, 25-30% of the recipients of physical aggression at all three assessment periods were seriously maritally discordant at 30 months.

Adult↗
PubMed1983

The influence of marital therapy on sexual satisfaction.

The influence of behavioral marital therapy on sexual satisfaction was assessed in 44 consecutive cases for which pre and post data were obtained. There were significant increases in both marital and sexual satisfaction associated with marital therapy. Sexual problems were presented in approximately 40% of the cases, but whether sex was presented as a problem or not generally did not affect therapy outcome. Positive feelings toward spouse or caring for one's spouse improved significantly from pre- to posttherapy.

Adaptation, Psychological↗
PubMed1983

Assessment of perceptual discrepancy: utility of the Primary Communication Inventory.

The Primary Communication Inventory was factor-analyzed in order to validate the subscales of this instrument. These subscales were derived by Navran (20) on the basis of face validity and were labeled verbal and nonverbal communication subscales. The analysis yielded two factors. However, they could not be labeled verbal and nonverbal. Instead, the factors were interpreted as: (a) the individual's perceptions of own communication ability, and (b) the spouse's perceptions of the individual's communication ability. The scoring of the Primary Communication Inventory was revised and used as a measure of perceptual discrepancy between husbands and wives. Interestingly, discrepancy within the marital dyad was greater for the nondistressed participants than for the distressed participants. The results illustrate the potentially adaptive nature of positive perceptual distortion within the marital dyad and the potential utility for future research of calculating perceptual discrepancy scores for each spouse using the Primary Communication Inventory.

Adult↗