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Biomedical subjects

M Vera

Publications and source records attributed to M Vera.

At least 37 records · Page 2Linked to original sources

Increased plasma adrenomedullin levels in hemodialysis patients with sustained hypotension.

BACKGROUND: Sustained hypotension in end-stage renal disease patients is characterized, despite an overactivation of the sympathetic and renin-angiotensin systems, by decreased vascular resistance and a blunted vascular response to pressor stimuli. An increased production of one or more vasodilator substances might play a role in the reduced vascular resistance and response to pressor stimuli in these patients. We evaluated the possible role of an increased production of nitric oxide and/or adrenomedullin (ADM) in the pathophysiology of chronic hypotension in hemodialysis (HD) patients. METHODS: Three groups of hypotensive (N = 9), normotensive (N = 10), and hypertensive (N = 9) HD patients were included in the study. Plasma renin activity (PRA) and plasma levels of catecholamines, ADM, nitrite/nitrate (an estimator of nitric oxide production), tumor necrosis factor (TNF), and interleukin-1beta (IL-1beta) were measured. Plasma volume and left ventricular ejection fraction (LVEF) were also evaluated. RESULTS: Plasma levels of nitrite/nitrate and ADM were elevated in HD patients with respect to the reference values in normal subjects. Plasma ADM levels, but not nitrite/nitrate levels, were higher in hypotensive (368.1 +/- 25.4 pg/mL) than normotensive (225 +/- 9.9 pg/mL) and hypertensive HD patients (278.2 +/- 15.5 pg/mL, P < 0.01). When considering hypotensive and normotensive patients together, the mean blood pressure inversely correlated with time on HD (r = -0. 53, P < 0.05) and plasma ADM levels (r = -0.78, P < 0.01). CONCLUSIONS: Plasma ADM and nitrite/nitrate levels are increased in HD patients, but only ADM levels were higher in hypotensive than in normotensive and hypertensive HD patients. The higher plasma levels of this peptide in hypotensive patients and its inverse correlation with mean arterial pressure suggest that ADM may be involved in the pathophysiology of chronic hypotension in HD patients.

Adrenomedullin↗

Serum cystatin C as a new marker for noninvasive estimation of glomerular filtration rate and as a marker for early renal impairment.

Cystatin C is a nonglycosylated basic protein produced at a constant rate by all investigated nucleated cells. It is freely filtered by the renal glomeruli and primarily catabolized in the tubuli (not secreted or reabsorbed as an intact molecule). Because serum cystatin C concentration is independent of age, sex, and muscle mass, it has been postulated to be an improved marker of glomerular filtration rate (GFR) compared with serum creatinine level. We compared serum cystatin C level with other markers of GFR, such as serum creatinine level and creatinine clearance, and analyzed their variations based on iothalamate labeled with iodine 125 ((125)I-iothalamate) clearance ((125)I-ICl), used as the gold standard for GFR. The concentrations of the two different markers of GFR in patients with impaired renal function were classified according to (125)I-ICl. Twenty individuals with normal renal function ((125)I-ICl, 128 +/- 23 mL/min/1.73 m(2)) were used as the control group. Serum cystatin C level showed a greater sensitivity (93.4%) than serum creatinine level (86.8%). Also, serum cystatin C showed the greatest proportion of increased values in patients with impaired renal function (100%) compared with serum creatinine level (92.15%). Serum cystatin C levels started to increase to greater than normal values when GFR was 88 mL/min/1.73 m(2), whereas serum creatinine level began to increase when GFR was 75 mL/min/1.73 m(2). These data suggest that measurement of serum cystatin C may be useful to estimate GFR, especially to detect mild reductions in GFR, and therefore may be important in the detection of early renal insufficiency in a variety of renal diseases for which early treatment is critical.

Biomarkers↗

Effect of methyl tertiary butyl ether concentrations on exhaust emissions from gasoline used in the metropolitan area of Mexico City.

In this work, the primary objective was to assess the impact of oxygenated fuel on the exhaust emissions from an important fraction of vehicles in the Metropolitan Area of Mexico City (MAMC). The results aim to provide information on the actual effect of MTBE on a fleet that represents more than 60% of the in-use vehicles in the MAMC. Ten vehicles were tested with a low-octane base gasoline, and 10 more with a regular-grade unleaded base gasoline. Three MTBE concentrations, 5, 10, and 15 vol %, were tested following the U.S. Federal Test Procedure (FTP). CO, total HC, and NOx from the exhaust gases were quantitatively evaluated and also characterized for FTP speciated organic emissions. From this data, the O3-forming potential of the fuels was calculated. Results show that for the fleet using low-octane gasoline, the addition of 10% MTBE substantially reduced CO emissions, but total HC concentration in the exhaust showed a modest decrease. For the regular gasoline, the 10% MTBE blend seemed to be the best choice, but there was not a significant decrease in emissions. The specific reactivity of each fuel, expressed in grams of O3 per gram of nonmethane organic gases, increased with MTBE concentration in both cases. This result is important to consider, especially for a region like Mexico City, which has high atmospheric O3 concentrations.

Air Pollutants↗

Characterization of monoclonal antibodies against apolipoproteins A-I and A-II. Epitope expression in LpA-I and LpA-I:A-II particles.

Two monoclonal antibodies (MAbs) against apolipoprotein A-I (apo A-I), 6B9 and FF9B10, and one MAb against apolipoprotein A-II (apo A-II), 3F5, were characterized. To establish the epitope of apo A-I recognized by these antibodies, different experimental approaches were performed. First, competition between MAbs and the related epitopes on the same antigen was performed using double-determinant tests with previously characterized MAbs. Second, competition of different synthetic peptides of apo A-I in solution with apo A-I immobilized to solid phase was carried out. The MAbs against apo A-I (6B9 and FF9B10) appear to recognize discontinuous epitopes located in the amino-terminal region of the apo A-I. In competition experiments MAb 3F5 did not recognize central- or carboxy-terminal peptides of apo A-II. Furthermore, apo A-II was stronger recognized when it was included in HDL or LpA-I:A-II than in its purified form. So the epitope for 3F5 is better expressed in the lipoprotein structure. Finally, to establish the epitopes expression in different antigens in solution, competition of purified apo A-I, apo A-II, LpA-I, and LpA-I:A-II particles or HDL3, with apo A-I or HDL immobilized to solid phase, was carried out. The results showed that both MAbs against apo A-I reacted with poor affinity against free apo A-I, with high and similar affinities against Lp A-I and Lp A-I:A-II lipoparticles and with the highest affinity against HDL3. The MAb 3F5 against apo A-II recognized only LpA-I:A-II and not LpA-I lipoparticles.

Animals↗

Prevalence of DSM-IV disorders in children and adolescents with asthma versus diabetes.

OBJECTIVE: To evaluate the relationships between asthma and type and incidence of psychiatric problems in a pediatric population. METHODS: A series of 93 children and adolescents with asthma presenting during a 1-year period to a pediatric pneumology and allergy service was studied. Their psychopathological problems were compared with those of 93 children with insulin-dependent diabetes mellitus (IDDM). Various questionnaires were completed by the patients: the Child Depression Inventory (CDI), the State-Trait Anxiety Inventory for Children (STAIC), and the Coopersmith Self-Esteem Inventory (SEI). Their parents were administered the Child Behavior Checklist (CBCL). The patients were examined using the revised Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS-R). RESULTS: There were more symptoms in the asthma group than in the IDDM group, as indicated by total CBCL scores, internalization and externalization CBCL subscores, and the STAIC scores. Asthma was often associated with Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) psychiatric disorders. We found 30 anxiety disorders, 5 affective disorders, and 6 disruptive behaviour disorders. Asthmatic children did not seem to be more depressed than the IDDM group, and their self-esteem, overall, was good. However, the asthma subgroup presenting with psychiatric disorders had poorer self-esteem and social competence. Adolescents did not seem to suffer more psychiatric disturbances than did younger patients. Girls did not suffer more psychiatric disturbances than did boys. CONCLUSION: Asthma appears to be associated both with higher overall incidence of psychiatric problems than in IDDM and with particular categories of psychiatric problems. In particular, the problems include anxiety disorders, internalizing symptoms, and disruptive behaviours.

Adolescent↗

[Sociodemographic profile of a group of sex workers in Puerto Rico].

This research explored the sociodemographic characteristics, the health perceptions and the distinctive aspects of the sexual work of a group of women sexual workers (n = 311). The study interest was generating data relative to the use of injectable drugs, the prevalence of sexually transmitted diseases (STD), the prevalence of HIV and the risk behaviors of this population group. A remarkable characteristic of the group of women studied was their history of pregnancies at and early age. A high proportion of illness apparently related to the presence of sexually transmitted diseases and limited health care was observed.

Adolescent↗

[Factors related to initiation, type and length of breast feeding among participants and non-participants in prenatal breast feeding education at a local hospital].

The objective of this study was to determine the factors associated to initiation, type and duration of breastfeeding among participants and non-participants in prenatal breastfeeding classes at a local hospital (n = 153). Pre-experimental study design was used. The participants of the study were selected by simple systematic random sampling. Median age of participants was 28 years and 85% were married at the moment of the interview. 88.9% began to breast feed at some time and of these 32% breastfed for six months. Average number of school years completed by participants was 15.1 with a standard deviation of 1.9 years. The inferential results reflected statistical association between participation in prenatal breastfeeding classes and the initiation, type and duration of breastfeeding. Multiple regression results indicate a positive relationship between duration of breastfeeding and participation in breastfeeding support groups, after controlling for all factors of the conceptual model. The results of this study give support for hospital and community initiatives for increasing the incidence of breastfeeding and for extending the duration of breastfeeding. It is further recommended that continued education courses be offered to health professionals on breastfeeding techniques.

Adolescent↗

Help seeking for mental health care among poor Puerto Ricans: problem recognition, service use, and type of provider.

OBJECTIVES: This study examines the effects of health, predisposing, and enabling factors on recognition of a mental health problem, use of formal mental health care, and contact with a specialized mental health provider. METHODS: Interviews were conducted with a probability sample of 3,435 adults. The variables examined include measures of mental health; social and demographic factors; and enabling factors relevant to the help-seeking process. RESULTS: Subjective and objective measures of mental health were associated with the recognition of a mental health problem. The objective assessment of definite need for services was relevant for the use of formal services. However, the subjects' perception of poor mental health was strongly related to receiving care from a mental health specialist. Although interaction with social networks is associated with use of formal services, low economic strain is related to receiving care from the specialty sector. CONCLUSIONS: The results support the importance of using multiple measures of mental health problems. The finding that individuals' perceived economic strain increases the likelihood of receiving specialized care suggests that studies of economic barriers to the use of mental health services might benefit from the adoption of measures that assess perceived economic circumstances.

Adolescent↗

Social networks and patterns of use among the poor with mental health problems in Puerto Rico.

OBJECTIVES: This study uses the recently developed Network-Episode Model (NEM) to examine the nature and correlates of utilization among Puerto Ricans reporting mental health problems. The NEM highlights two issues: (1) examining the patterns or combinations of lay and formal use that individuals employ and (2) reformulating how the availability and content of social networks influences patterns of care. METHODS: Using data from the 1989 Mental Health Care Utilization Among Puerto Ricans Study (probability sample of 1,777 individuals living in low-income areas of the island), the authors focus on the patterns and correlates of use for 365 Puerto Ricans reporting service use for mental health problems in the previous year. RESULTS: A combination of clustering and multinomial logit techniques indicates that there are six unique care patterns. Two patterns include the use of mental health providers and are associated with different contingencies. CONCLUSIONS: In general, patterns of use are shaped by age, education, gender, and illness severity. Larger, more supportive networks decrease the use of patterns of care that include formal health care providers, and decrease direct entry into the mental health sector. These results are in line with NEM's predictions for lower class populations and help clarify inconsistencies in previous research on social networks. The implications of this perspective for health services research and treatment are discussed.

Adolescent↗

The association between Crohn disease and the myelodysplastic syndromes. Report of 3 cases and review of the literature.

We report 3 patients who developed Crohn disease and myelodysplastic syndrome concurrently and review 9 previously reported cases of this association. Demographic and clinical features, treatment, and outcome are presented from previous reports and our own 3 cases. Of the 12 patients, 8 were men, and the mean age was 68.8 years (range, 28-83 yr). The geographic origin was heterogeneous. Pancytopenia was found in 5 patients, anemia in 5, and bicytopenia in 2. The classification types of myelodysplastic syndrome were variable. The marrow karyotype was reported in 10 patients: it was abnormal in 5, with chromosome 20 abnormalities in 3. Crohn disease and myelodysplasia were diagnosed simultaneously in 5 patients, whereas Crohn disease antedated myelodysplasia in 4 patients (interval, 8 mo-30 yr) and myelodysplasia antedated Crohn disease in 3 patients (interval, 2 mo-4 yr). Signs and symptoms of Crohn disease improved in most patients upon specific medical treatment. However, the outcome of myelodysplastic syndrome was not favorable in 10 of 11 patients in whom it was reported, with 4 deaths due to myelodysplasia-related complications. Notably, the activity of myelodysplasia in 1 of our own patients paralleled the clinical activity of Crohn disease, and hematologic abnormalities of the myelodysplasia resolved upon successful treatment of the Crohn disease, thus strengthening the hypothesis of a pathogenetic link between the disorders. The possibility of myelodysplastic syndrome should be considered in patients with Crohn disease over the age of 50 years who have peripheral blood cytopenias. Likewise, a diagnosis of Crohn disease should be considered in patients with myelodysplastic syndrome who develop gastrointestinal symptoms such as chronic and/or bloody diarrhea. In patients with such an association, the possibility of improvement of the myelodysplasia upon successful therapy of Crohn disease should not be ruled out.

Aged↗

Mental health utilization in women with symptoms of depression.

This paper examines the help-seeking process of mental health services in women with high depressive symptoms. The data are based on an island wide probabilistic sample (n = 1,062) of 18- to 64-year-old women living in low socioeconomic areas in Puerto Rico. Symptoms of depression were measured by the Center for Epidemiological Studies Depression Scale (CES-D). Results show that one out of three women living in poor residential areas report high depressive symptoms. Of these women with high depressive symptoms, only 12% seek help from a mental health specialist and 14.5% from a general health care provider to deal with their emotional problems. Some factors related to the use of mental health services are: presence of an occupational disability, head of household status, having private insurance, and having a regular source of care. These data suggest that women underutilize mental health services and overutilize physical health services to deal with their emotional problems. The lack of recognition of emotional problems by these women may explain the low utilization of mental health services.

Adolescent↗

[Women abandoned by Social and Health Agencies. Challenge in the prevention of HIV/AIDS].

The present study examined the role of an intervention directed to link a group of sexual workers with social and health services. The subjects receptivity to use these services was measured by the degree of acceptance that the selected agencies provided to the participants of this study. The present investigation included two groups of subjects consisting of sexual workers and other women that were at high risk of prostitution because of their social circumstances. The sample consisted of 92 women residents of either the San Juan area of other towns from the eastern part of Puerto Rico. The method of focal group and a agencies directory was utilized during the intervention. In addition, the attempt to establish a helpful relationship between the subject and the agency was also incorporated to the investigation. The present findings showed the presence of a considerable social distance between the agencies and the subjects studies. The use of the studied intervention failed to be an efficient strategy. The authors recommend to explore different and new intervention modalities that elicit significant social change. Moreover, these interventions should innovate the current treatments aimed at the social problems related to sexual work.

Acquired Immunodeficiency Syndrome↗

Teen perspectives on HIV and the relevance of Hawaii's health providers.

Based on focus group interviews with adolescents from an urban Honolulu community, the present article describes how these adolescents view HIV, HIV-prevention and the role of health care providers in addressing HIV-related needs. Although medical providers are known to be knowledgeable experts in a variety of health care areas, other research points to an underutilization of this potential. While knowledgeable about HIV, many of the youth in this study continue to engage in risky behavior. Few perceive they have others they can meaningfully talk to about their HIV and other health concerns. Even when probed for, almost none of these teens saw health care providers as pertinent to HIV or their health beyond the traditional illness/prescription role. Suggestions for ways to get more involved in the prevention of HIV and, more generally, positive health development in teens are discussed.

Adolescent↗