Victoria Valles

Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Tlalpam, Mexico City, Mexico

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Publications (17)44.93 Total impact

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    ABSTRACT: There is a need to assess whether human immunodeficiency virus (HIV)-infected patients are more likely than noninfected individuals to have any of the specific lipoprotein combination profiles identified as the best predictors of future cardiovascular disease in the general population. One hundred five infected patients, randomly selected from a Mexican HIV clinic, and 105 age- and gender-matched noninfected community volunteers, were enrolled to study the prevalence of each of three highly atherogenic lipoprotein phenotypes [high apolipoprotein (Apo)B/ApoA-I ratio, hypertriglyceridemia with high ApoB and hypoalphalipoproteinemia with high ApoB], and the relationship between time of exposure to antiretroviral therapy (ART) drug class and lipid changes. The highly atherogenic lipoprotein phenotypes were similarly frequent in both groups. There was a nonsignificant increased risk of dyslipidemia with longer exposure to any of the ART drug classes, although this hazard seems to be greater in patients with central fat accumulation. No evidence of increased risk for certain highly atherogenic lipoprotein phenotypes in HIV-infected patients was found. More than one pathogenic mechanism for ART-associated dyslipidemia is postulated.
    No preview · Article · Feb 2008 · Archives of Medical Research
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    ABSTRACT: We assessed myocardial perfusion (blinded interpretation of a single-photon emission computed tomography) and known risk factors for atherosclerosis in 105 randomly selected human immunodeficiency virus (HIV)-infected patients in a clinic in Mexico City and in a community sample of 105 age and gender-matched infection-free subjects. An abnormal scan was obtained in 4.8% of the infected and in 7.6% of the non-infected subjects. Severity of scintigraphic abnormalities was similar in both groups. In these Mexican HIV-infected patients, despite a long time of infection and of exposure to combined antiretroviral therapy and to other classical risk factors for atherosclerosis, there was no evidence of increased risk for abnormal myocardial perfusion. Dissimilar magnitude in the hazard of coronary heart disease may occur among infected populations with different frequencies of traditional predisposing factors for cardiovascular illness.
    No preview · Article · Nov 2007 · International journal of cardiology
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    ABSTRACT: Hypoxic stimulation of the carotid body receptors (CBR) results in a rapid hyperglycemia with an increase in brain glucose retention. Previous work indicates that neurohypophysectomy inhibits this hyperglycemic response. Here, we show that systemic arginine vasopressin (AVP) induced a transient, but significant, increase in blood glucose levels and increased brain glucose retention, a response similar to that observed after CBR stimulation. Comparable results were obtained after intracerebral infusion of AVP. Systemic AVP-induced changes were maintained in hypophysectomized rats but were not observed after adrenalectomy. Glycemic changes after CBR stimulation were inhibited by pharmacological blockage of AVP V1a receptors with a V1a-selective receptor antagonist ([beta-Mercapto-beta,beta-cyclopentamethylenepropionyl1,O-me-Tyr2, Arg8]-vasopressin). Importantly, local application of micro-doses of this antagonist to the liver was sufficient to abolish the hyperglycemic response after CBR stimulation. These results suggest that AVP is a mediator of the hyperglycemic reflex and cerebral glucose retention following CBR stimulation. We propose that hepatic activation of AVP V1a receptors is essential for this hyperglycemic response.
    Preview · Article · Jul 2006 · Journal of Applied Physiology
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    ABSTRACT: We assessed the impact of the NCEP–III recommendations in a population–based, nation–wide Mexican survey. Information was obtained from 15,607 subjects aged 20 to 69 years. In this report, only samples obtained after a 9 to 12 hours fast are included (2,201 cases). A cardiovascular risk equivalent was found in 10.5% and > 2 risk factors were present in 41.7% of the population. In 10% of cases, the LDL–C concentration was high enough to be an indication for a lipid–lowering drug (> 160 mg/dL), independent of the presence of risk factors. A quarter of the population was eligible for some form of treatment (lifestyle modifications in 15.9%, drug therapy in an additional 11.7%). Among cases with > 2 risk factors, a small percentage (1.8%) were identified as having a 10 year–risk > 20% and 86.3% were considered as having alO year–risk < 10%. The majority of the metabolic syndrome cases (84%) were identified as low–risk subjects. As a result, only 17.6% of them qualified for drug–based LDL–C lowering. Our data helps to estimate of the magnitude of the burden imposed on the Mexican health system, of lowering LDL–C for cardiovascular prevention. If we apply our results to the 2,000 Mexican population census more than 5.8 million cases nationwide may require LDL lowering drug therapy following the NCEP–III criteria.
    Full-text · Article · Feb 2005 · Revista de investigacion clinica; organo del Hospital de Enfermedades de la Nutricion
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    ABSTRACT: We assessed the impact of the NCEP-III recommendations in a population-based, nation-wide Mexican survey. Information was obtained from 15,607 subjects aged 20 to 69 years. In this report, only samples obtained after a 9 to 12 hours fast are included (2,201 cases). A cardiovascular risk equivalent was found in 10.5% and > or = 2 risk factors were present in 41.7% of the population. In 10% of cases, the LDL-C concentration was high enough to be an indication for a lipid-lowering drug (> 160 mg/dL), independent of the presence of risk factors. A quarter of the population was eligible for some form of treatment (lifestyle modifications in 15.9%, drug therapy in an additional 11.7%). Among cases with > or = 2 risk factors, a small percentage (1.8%) were identified as having a 10 year-risk > 20% and 86.3% were considered as having a 10 year-risk < 10%. The majority of the metabolic syndrome cases (84%) were identified as low-risk subjects. As a result, only 17.6% of them qualified for drug-based LDL-C lowering. Our data helps to estimate of the magnitude of the burden imposed on the Mexican health system, of lowering LDL-C for cardiovascular prevention. If we apply our results to the 2,000 Mexican population census more than 5.8 million cases nationwide may require LDL lowering drug therapy following the NCEP-III criteria.
    Full-text · Article · Jan 2005 · Revista de investigacion clinica; organo del Hospital de Enfermedades de la Nutricion
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    ABSTRACT: Several risk factors for the development of coronary atherosclerosis (CA) have been identified. These included hyperlipidemia, hypertension, smoking and diabetes mellitus. As well as elevated plasma homocysteine (tHcys) levels, is considered an independent risk factor for CA in some American and Europeans studies, but its association are scare in Latin-American population. We therefore conducted a case-control study to explore this issue in Mexican population. Eighty eight patients with scintigraphic evidence of CAD or history of myocardial infarction compared with a control group of 96 individuals were analyzed. tHcys were measured in all subject's serum samples. Conventional risk factors were also analyzed. A high prevalence of hyperhomocystinemia with no significant difference between the 2 groups was found. The mean concentration of tHcys was 13.9 micromol/L (SD +/- 6.9) in the CA group; and 14.8 micromol/L (SD +/- 7.3) in the control group. We did not obtain a statistical difference on tHcys concentration between patients with and without others risk factors, like diabetes mellitus, hyperlipidemia, hypertension, smoking and obesity. Ours results shown a high prevalence of hyperhomocystinemia (> 12 micromol/L) in Mexican people. However these high levels were not associated with evidence of CA. More studies in our population are warranted to clarify the possible influence of homocysteine on coronary atherosclerosis.
    No preview · Article · Sep 2004 · Revista de investigacion clinica; organo del Hospital de Enfermedades de la Nutricion
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    ABSTRACT: Our objective was to describe the prevalence of the metabolic syndrome using World Health Organization (WHO) and National Cholesterol Education Program (NCEP-III) definitions in a population-based survey. We performed an analysis of data from a Mexican nationwide, population-based study. The population was composed of 2,158 men and women aged 20-69 years sampled after a 9-12 h fasting period. Prevalence of the metabolic syndrome as defined by the NCEP-III definition and WHO criteria was estimated and case characteristics were assessed. Age-adjusted prevalence was 13.61% for WHO criteria and 26.6% for the NCEP-III definition. Prevalence was 9.2 and 21.4%, respectively, in subjects without diabetes. Thirty five percent of affected cases were <40 years of age. In addition to criteria used for diagnosis, ca. 90% were either overweight or obese. In cases detected using WHO criteria, antihypertensive treatment or blood pressure reading >140/90 was found in 61.8%. The proportion of subjects who qualified for hypolipemiant treatment was lower: lifestyle modifications were needed in 42.1% and drug therapy was required in 18.9%. The same trends were found for cases detected using the NCEP definition. Prevalence of the metabolic syndrome in Mexico is high. A large proportion of affected cases qualify for preventive actions for complications of the metabolic syndrome (i.e., weight loss, antihypertensive or hypolipemiant treatment). These results provide data for planning therapeutic programs for Mexican patients with the metabolic syndrome.
    No preview · Article · Feb 2004 · Archives of Medical Research
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    ABSTRACT: It is well established that the carotid body receptors (CBR), at the bifurcation of the carotid artery, inform the brain of changes in the concentration of CO(2) and O(2) in arterial blood. More recent work suggests that these receptors are also extremely sensitive to blood glucose levels suggesting that they may play an important role as sensors of blood components important for brain energy metabolism. Much less is known about changes in brain glucose metabolism in response to CBR activation. Here we show that 2-8 min after local injection of sodium cyanide (NaCN) into the CBR or after electrical stimulation of the carotid sinus nerve in dogs and rats, brain glucose uptake increased fourfold. Cerebrospinal fluids (CSF) transferred from dogs, 2-8 min after CBR stimulation, into the cisterna magna of non-stimulated dogs or rats induced a similar increase in brain glucose uptake. CSF from stimulated dogs was also active when injected intravenously in anesthetized or awake rats. The activity was destroyed when the stimulated CSF was heated to 100 degrees C or treated with trypsin. We conclude that a peptide important for brain glucose regulation appears in the CSF shortly after CBR stimulation.
    Full-text · Article · Jan 2004 · Brain Research
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    Full-text · Article · Jun 2003 · Journal of Human Hypertension
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    Full-text · Article · Jun 2003 · Diabetes Care
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    ABSTRACT: Glucose homeostasis, a fundamental process for life, is controlled at multiple levels. Glucose sensitive receptors in the brain, portal vein, liver, pancreas and carotid bodies (Álvarez-Buylla and Roces de Álvarez-Buylla, 1994) provide afferent information to central nervous system (CNS) about the glucose concentration in different regions of the body. In the CNS, this input is integrated by the hypothalamus and the nucleus of the tractus solitarius (NTS) (Adachi et al., 1995). Additionally, there is evidence that carotid body receptors (CBR) are also sensitive to changes in blood glucose concentration (Álvarez- Buylla and Roces de Álvarez-Buylla, 1994; López-Barneo et al., 2001) and afferent impulses from these receptors induce a reflex response on glucose levels: 1) by enhancing glucose production by the liver, and 2 by promoting glucose retention by the brain. Carotid bodies play an important role in the insulin-induced counterregulatory response to mild hypoglycemia (Koyama et al., 2000). The efferent pathway for these reflexes is not fully understood, but previous experiments identify the neurohypophysis and adrenal glands as necessary for the hyperglycemic reflex initiated by NaCN stimulation, and suggest that the effects of these two glands on CBR hyperglycemic reflex are humoral (Álvarez-Buylla et al., 1997). This is supported by the finding that the neurohypophyseal hormone arginine-vasopressin (AVP) has a modulatory role on glucose metabolism during stress, and that an increase of vasopressin plasma levels is observed after perfusion of the carotid sinus with deoxygenated blood, a method similar to NaCN stimulation (Share and Levy, 1966). In addition, hypophysectomy leads to adrenal cortical atrophy and hypoglycemia (Wurtman et al., 1968). We have previously hypothesized that pituitary AVP may be involved in the hyperglycemic reflex initiated by CBR stimulation. In this paper we extend the study to the role of glucose in regulating AVP at the level of NTS (Yarkov et al., 2001), and suggest that this peptide may facilitate hyperglycemic reflexes elicited by CBR stimulation. We show that AVP can directly trigger a hyperglycemic reflex similar to that obtained after CBR stimulation. We suggest that AVP may interact with vasopressin receptors located in the NTS, liver, adrenal cells and pancreas to stimulate the secretion of epinephrine (E) and glucagon.
    No preview · Article · Feb 2003 · Advances in Experimental Medicine and Biology
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    ABSTRACT: To investigate the prevalence and characteristics of patients with type 2 diabetes diagnosed before the age of 40 years (early-onset disease) in a nationwide, population-based study. Using a multistage sampling procedure, we enrolled a representative sample of Mexican urban adults aged 20 to 69 years. Weight, height, blood pressure, and plasma levels of glucose, insulin, and other metabolic parameters were measured in all subjects. We identified 993 subjects with type 2 diabetes, including 143 subjects aged 20 to 39 years (14% of those with diabetes). Subjects with early-onset diabetes had a greater prevalence of obesity and higher plasma insulin and lipid levels than did age-matched controls, and a greater prevalence of high-density lipoprotein cholesterol levels <35 mg/dL and severe hypertriglyceridemia than did older subjects with diabetes. Those (n = 32) with a normal body mass index (20 to 25 kg/m(2)) tended to have insulin deficiency as the main abnormality, whereas the "metabolic syndrome" characterized the remaining 111 subjects with early-onset diabetes. Most patients with early-onset type 2 diabetes in Mexico are obese or overweight, suggesting that obesity treatment and prevention programs may be effective in reducing the prevalence of this disease.
    No preview · Article · Dec 2002 · The American Journal of Medicine
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    ABSTRACT: To describe the characteristics of mixed hyperlipidemia cases, using data derived from the Encuesta Nacional de Enfermedades Crónicas (Mexican National Survey of Chronic Diseases, ENEC). The ENEC was conducted in 1993, in 417 Mexican cities. Blood measurements of lipids, glucose, and insulin were obtained from 2206 cases. Differences between dyslipidemia patients and non cases were obtained using analysis of variance or the chi-squared test. Mixed hyperlipidemia was diagnosed in 282 subjects (12.8%). Cases were 42.7+/-12.6 years old. Fifty six percent were males and 46.4% had HDL cholesterol levels < 0.9 mmol/l. Other cardiovascular risk factors were also present. The prevalence of mixed hyperlipidemia was high even among young adults. A logistic regression model showed that obesity, age, male gender, residence in some regions of Mexico, diabetes, arterial hypertension, and fasting insulin levels >21 mU/ml, were factors associated with mixed hyperlipidemia. Mixed hyperlipidemia is a very common condition in Mexican adults. It is more common in males older than 30 years, with additional cardiovascular risk factors. Study findings suggest that the metabolic syndrome plays a role in the pathogenesis of this disorder.
    No preview · Article · Nov 2002 · Salud publica de Mexico
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    ABSTRACT: The apolipoprotein (apo) B and A-I distribution found in a survey performed in 417 Mexican cities is described. Information was obtained from 15,607 subjects aged 20 to 69 years. In this report, only samples obtained after a 9- to 12-hour fast were included (1,674 cases, 652 men and 1,022 women). The population is representative of the Mexican urban adults. Mean lipid concentrations were: cholesterol,182.7 mg/dL; triglycerides, 213 mg/dL; high-density lipoprotein (HDL) cholesterol, 38.3 mg/dL; and low-density lipoprotein (LDL) cholesterol, 116 mg/dL. The mean concentration of apo B was 77.8 +/- 25.9 mg/dL and 71 +/- 22.8 in men and women, respectively. A continuous increase of apo B was observed as subjects got older. A tendency to decrease after age 60 was observed in men, but not in women. The body mass index (BMI) is a major determinant for the apo B concentrations. The 90th percentile of the apo B concentration identifies a similar proportion of abnormal subjects than the LDL cholesterol concentration of 160 mg/dL. The 120 mg/dL concentration, upper normal limit level used in other populations, identified as abnormal only 3.8% of the cases. Regardless of the lipid abnormality, an apo B above the 90th percentile was associated with higher levels of glucose, cholesterol, triglycerides, and non-HDL cholesterol, despite a similar age and BMI. The overall mean concentration of apo A-I was 122.3 +/- 31 mg/dL and 129 +/- 34 in men and women, respectively. In conclusion, our data show that the apo B and apo A-I concentrations in Mexican urban adults are lower compared with the levels reported in other ethnic groups. Previously used reference ranges are not useful in the population report herein. These observations strengthen the need for obtaining data in population-based studies worldwide.
    No preview · Article · Jun 2002 · Metabolism
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    ABSTRACT: Objective. To describe the characteristics of mixed hyper- lipidemia cases, using data derived from the Encuesta Na- cional de Enfermedades Crónicas (Mexican National Survey of Chronic Diseases, ENEC). Material and Methods. The ENEC was conducted in 1993, in 417 Mexican cities. Blood measurements of lipids, glucose, and insulin were obtained from 2206 cases. Differences between dyslipidemia patients and non cases were obtained using analysis of variance or the chi-squared test. Results. Mixed hyperlipidemia was diagnosed in 282 subjects (12.8%). Cases were 42.7±12.6 years old. Fifty six percent were males and 46.4% had HDL cholesterol levels < 0.9 mmol/l. Other cardiovascular risk factors were also present. The prevalence of mixed hyper- lipidemia was high even among young adults. A logistic regression model showed that obesity, age, male gender, re- sidence in some regions of Mexico, diabetes, arterial hyper- tension, and fasting insulin levels >21 mU/ml, were factors associated with mixed hyperlipidemia. Conclusions. Mixed hyperlipidemia is a very common condition in Mexican adul- ts. It is more common in males older than 30 years, with additional cardiovascular risk factors. Study findings suggest that the metabolic syndrome plays a role in the pathogene-
    Full-text · Article · Jan 2002 · Salud publica de Mexico
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    ABSTRACT: The prevalence of lipid abnormalities revealed in a survey done in 417 Mexican cities is described. Information was obtained on 15,607 subjects, aged 20 to 69 years. In this report, only samples obtained after a 9- to 12-h fast were included (2,256 cases: 953 men and 1,303 women). The population is representative of Mexican urban adults. Mean lipid concentrations were: cholesterol, 4.80 mmol/l; triglycerides, 2.39 mmol/l; HDL cholesterol, 1.00 mmol/l; and LDL cholesterol, 3.06 mmol/l. The most prevalent abnormality was HDL cholesterol below 0.9 mmol/l (46.2% for men and 28.7% for women). Hypertriglyceridemia (>2.26 mmol/l) was the second most prevalent abnormality (24.3%). Severe hypertriglyceridemia (>11.2 mmol/l) was observed in 0.42% of the population. Increased LDL cholesterol (> or =4.21 mmol/l) was observed in 11.2% of the sample. Half of the hypertriglyceridemic subjects had a mixed dyslipidemia or low HDL cholesterol. More than 50% of the low HDL cholesterol cases were not related to hypertriglyceridemia. Insulin resistance was found in 59% of them. In conclusion, the prevalence of hypoalphalipoproteinemia and other forms of dyslipidemia in Mexican adults is very high and it is among the highest previously reported worldwide.
    Full-text · Article · Sep 2001 · The Journal of Lipid Research
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    ABSTRACT: Results from a population-based survey O ur objective was to evaluate the di-agnostic proficiency of the World Health Organization (WHO) and the National Cholesterol Education Pro-gram (NCEP)-III definitions (1,2) for the metabolic syndrome in a Mexican nation-wide, population-based survey. Details of the sampling procedures have been pre-viously described (3). The population was composed of 2,158 men and women aged 20 – 69 years sampled after a 9-to 12-h fasting period. For the WHO criteria, in-sulin resistance was diagnosed if a non-diabetic case had fasting insulin concen-trations 126 pmol/l (21 U/ml) (75th percentile in Mexican adults). The age-adjusted prevalence was 13.61% for the WHO criteria (n 268) and 26.6% for the NCEP-III definition (n 574). After excluding patients with diabetes, the prev-alence was 9.2 and 21.4%, respectively. The agreement between the definitions was assessed in 1,969 subjects; 189 cases were eliminated due to the lack of a urine sample. The number of abnormal cases was lower using the WHO criteria. Only 237 of the 545 subjects (43.4%) who fulfilled the NCEP criteria were diagnosed as af-fected using the WHO definition. Just 16 of 253 cases (6.3%) detected by the WHO definition did not fulfill the NCEP defini-tion. The agreement between the criteria was moderate (0.507). On the other hand, the subjects diagnosed using the WHO recommendations had a worse profile than the cases detected by the NCEP-III definition only—they had a higher BMI and higher non-HDL choles-terol, triglyceride, and glucose concentra-tions. The demonstration of insulin resistance among the nondiabetic popu-lation caused the lack of agreement in 202 of the 242 cases that fulfilled the NCEP definition but failed the WHO criteria. Other reasons for disparity were the higher thresholds used by the WHO cri-teria; these differences explained the lack of agreement in 66 of the 152 cases with diabetes. In conclusion, the prevalence of the metabolic syndrome is influenced by the selection of the diagnostic criteria. The WHO criteria identified a lower number of cases than the NCEP-III definition. These differences were explained mainly by the inclusion of abnormally high insu-lin concentrations as a diagnostic crite-rion. However, the presence of insulin resistance may help to identify patients more severely affected (4).
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