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Biomedical subjects

A Avendaño

Publications and source records attributed to A Avendaño.

At least 19 recordsLinked to original sources
PubMed1998

The introduction of routine Haemophilus influenzae type b conjugate vaccine in Chile: a framework for evaluating new vaccines in newly industrializing countries.

OBJECTIVE: To determine the burden of Haemophilus influenzae type b (Hib) disease, the safety and immunogenicity of Hib conjugate vaccine, the practicality of combining Hib conjugate and diphtheria-tetanus-pertussis vaccines and the effectiveness of routine vaccination. STUDY DESIGNS: A series of studies were carried out involving infants and children in Santiago, Chile. The study designs included retrospective surveillance, cost-benefit analysis, randomized placebo-controlled trials of safety and immunogenicity and a Phase IV postlicensure evaluation of vaccine effectiveness. RESULTS: The studies included in this stepwise process showed that Hib invasive disease was a significant public health problem with a substantial economic burden; that combining Hib conjugate and diphtheria-tetanus-pertussis vaccines was practical, safe and elicited a strong immunologic response; and that the combined formulation afforded a high level of protection against invasive Hib disease (90% effectiveness). CONCLUSIONS: In July, 1996, Chile became only the third newly industrializing country to introduce routine Hib conjugate vaccination. New vaccines, such as Hib conjugates, will be more expensive than existing ones. The stepwise process used in Chile may serve as an example for the evaluation of new vaccines in nonindustrialized countries.

Child, Preschool↗
PubMed1997

GDH3 encodes a glutamate dehydrogenase isozyme, a previously unrecognized route for glutamate biosynthesis in Saccharomyces cerevisiae.

It has been considered that the yeast Saccharomyces cerevisiae, like many other microorganisms, synthesizes glutamate through the action of NADP+-glutamate dehydrogenase (NADP+-GDH), encoded by GDH1, or through the combined action of glutamine synthetase and glutamate synthase (GOGAT), encoded by GLN1 and GLT1, respectively. A double mutant of S. cerevisiae lacking NADP+-GDH and GOGAT activities was constructed. This strain was able to grow on ammonium as the sole nitrogen source and thus to synthesize glutamate through an alternative pathway. A computer search for similarities between the GDH1 nucleotide sequence and the complete yeast genome was carried out. In addition to identifying its cognate sequence at chromosome XIV, the search found that GDH1 showed high identity with a previously recognized open reading frame (GDH3) of chromosome I. Triple mutants impaired in GDH1, GLT1, and GDH3 were obtained. These were strict glutamate auxotrophs. Our results indicate that GDH3 plays a significant physiological role, providing glutamate when GDH1 and GLT1 are impaired. This is the first example of a microorganism possessing three pathways for glutamate biosynthesis.

Ammonium Sulfate↗
PubMed1995

Early and late mortality of patients undergoing aortic valve replacement after previous coronary artery bypass graft surgery.

BACKGROUND: In a small number of patients who undergo coronary artery bypass graft surgery (CABG), a hemodynamically significant aortic valve lesion requiring aortic valve replacement (AVR) develops as they grow older. In a limited number of studies in small patient groups, high mortality has been shown in patients undergoing AVR after CABG. We undertook this study to determine the mortality risk factors for patients who undergo AVR after CABG procedures. METHODS AND RESULTS: The outcome of 104 patients treated at our institution between January 1983 and December 1993 was retrospectively reviewed. The initial surgery was CABG in all patients. The patient population included 86 men (83%) and 18 women (17%); their mean age was 67 years. Overall, 70% of patients had congestive heart failure, and 96% had multivessel coronary artery disease. The diagnosis was aortic stenosis in 68% of patients, aortic insufficiency in 16%, and combined aortic stenosis and aortic insufficiency in 16%. Postoperative complications included worsening congestive heart failure (35%), perioperative myocardial infarction (13%), and bleeding (28%). The early mortality was 14%, and the late mortality was 17% (mean follow-up, 35 months). The risk factors for early mortality were number of diseased vessels (P = .028), renal failure (0.000), and prior myocardial infarction (P = .028). A perioperative predictor of early mortality was cardiopulmonary bypass time (P = .000). The risk factors for late mortality included preoperative diabetes mellitus (P = .007), postoperative acute respiratory distress syndrome (P = .011), and ventricular arrhythmias (P = .0001). The survival at 1, 5, and 10 years was 96%, 75%, and 49%, respectively. CONCLUSIONS: Risk factors were identified for early and late mortality in patients undergoing AVR after previous CABG. Although early morbidity and mortality were high, the longterm outcome of the survivors was favorable.

Aged↗
PubMed1995

Attenuated live cholera vaccine strain CVD 103-HgR elicits significantly higher serum vibriocidal antibody titers in persons of blood group O.

Persons of blood group O are at increased risk of developing cholera gravis. In a randomized, placebo-controlled, double-blind safety-immunogenicity trial of live oral cholera vaccine CVD 103-HgR in 5- to 9-year-old Chilean children, vibriocidal antibody seroconversion (74% overall) did not differ by blood group. However, the reciprocal geometric mean titer (GMT) in blood group O vaccines (GMT = 486) was higher than that in non-O vaccines (GMT = 179) (P < 0.02).

ABO Blood-Group System↗
PubMed1994

Comparison of Hemochron and HemoTec activated coagulation time target values during percutaneous transluminal coronary angioplasty.

OBJECTIVES: The aim of this study was to determine whether activated coagulation time measurements from Hemochron and HemoTec machines can be used interchangeably and whether similar activated coagulation time target ranges for adequate anticoagulation can be applied to both machines. BACKGROUND: Adequate anticoagulation is necessary for the safe performance of intravascular interventions such as percutaneous transluminal coronary angioplasty. In current practice, anticoagulation status is frequently assessed by way of the activated coagulation time with one of two commercially available systems, HemoTec and Hemochron. Each one employs a different technique to determine the time of clot formation; however, the same target activated coagulation time values for adequate anticoagulation have been used interchangeably in published studies. METHODS: A total of 311 paired samples were compared in 113 high risk patients undergoing angioplasty enrolled in a randomized trial of a platelet glycoprotein IIb/IIIa receptor antibody. Simultaneous activated coagulation time measurements were obtained before and after administration of heparin, and the difference between the values of both machines was calculated. The relation between the Hemochron and HemoTec values was determined by using linear regression analysis. All activated coagulation time measurements were classified as either therapeutic or subtherapeutic using an arbitrary activated coagulation time target of 300 s. RESULTS: There was a correlation between values from the two machines (r = 0.86), but the Hemochron values were consistently higher than the HemoTec values by a mean value +/- SD of 28 +/- 29%, with wide individual variation. After heparin administration, there was a significant (p < 0.0001) difference between the number of measurements classified as therapeutic by HemoTec (53%) and by Hemochron (94%). CONCLUSIONS: HemoTec and Hemochron activated coagulation time measurements cannot be used interchangeably. Appropriate target activated coagulation time ranges to determine adequate anticoagulation during coronary angioplasty need to be established for both machines; the target range for one machine should not be extrapolated to the other.

Angioplasty, Balloon, Coronary↗
PubMed1993

Optimizing surgical backup for multiple simultaneous percutaneous transluminal coronary angioplasty procedures.

At busy interventional centers, it may be difficult to coordinate surgical backup for multiple simultaneous PTCA procedures. We sought to determine the actual risk of two simultaneous cases requiring surgery, and to identify a group in which multiple simultaneous PTCA procedures could be performed at low risk. We prospectively applied the ACC/AHA A/B/C lesion classification system and an empiric low/medium/high risk classification (based on patients' overall clinical picture) to 1,128 PTCA procedures over a 9 month period; 22 of these patients (1.9%) went directly from the catheterization laboratory to emergency CABG. The incidence of emergency CABG by groups was A-low 1/166, A-medium 1/71, A-high 0/22, B-low 1/116, B-medium 10/481, B-high 2/52, C-low 2/47, C-medium 3/88, and C-high 2/85. The patients were divided into two groups: minimal risk (A + B-low: 3/375 or 0.8%) and increased risk (B-med/high + C: 19/753 or 2.5%). The difference between the groups was significant using chi square with an alpha < 0.05. The risk of two cases requiring surgery at the same time was calculated as a function of the number of simultaneous PTCA procedures performed. Six or fewer minimal risk PTCA, one increased risk plus up to three minimal risk, and a maximum of two increased risk cases were found to have a risk of < 0.001. We conclude that it is possible to identify a group of patients with minimal risk, in whom multiple simultaneous procedures can be performed with a negligible probability of two cases requiring surgery at the same time.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1993

[Tolerance and immunogenicity of an oral dose of CVD 103-HgR, a live attenuated Vibrio cholerae 01 strain: a double-blind study of Chilean adults].

CVD 103-HgR is an attenuated, AB+, live, recombinant vaccine strain, developed by deletion of the toxA gen in a virulent Vibrio cholerae 01, Inada classical strain (569B). In phase II studies conducted to date, CVD 103-HgR has been well tolerated and immunogenic in volunteers from both industrialized countries and cholera-endemic areas. In this study of safety, immunogenicity and excretion, 81 Chilean adults were randomly allocated to receive, in a double blind fashion, a single oral dose of 5 x 10(9) FU of CVD 103-HgR or placebo, (5 x 10(9) heat-killed E. Coli K12 organisms), in 100 ml of buffered water. Side effects were assessed by daily visits to the participants. Immunogenicity, (vibriocidal seroconversion), was investigated in blood drawn before and on days 8 and 28 after immunization, while stool cultures to assess excretion of the vaccine strain were performed on specimens obtained on days 1 and 7. None of the participants, (40 vaccinees and 41 placebo recipients), experienced untoward effects during 30 minutes of close surveillance after ingestion of the preparation; upon follow up, neither adverse events were more frequently reported by the vaccinees. 34/40 vaccinees, and 2/41 participants receiving placebo had a significant raise, (> = fourfold), in their vibriocidal titers; (85 vs 2%, p < 0.001). The peak postimmunization geometric mean titer, (222), was ten fold higher than the baseline vibriocidal titer. The vaccine strain was recovered in stool cultures from 8 participants, one of them excreted the strain in both specimens. We conclude that CVD-103-HgR is safe and immunogenic in Chilean adults.

Administration, Oral↗
PubMed1991

Association between Rh and plasma iron binding (transferrin).

In order to establish the mechanism involved in the maintenance of the Rh polymorphism and fetomaternal compatibility relationships, we examined a sample of children from the North Area of Santiago (Chile), with respect to their growth and development patterns since 1973. This sample had shown large sib-sib segregation distortions for the Rh system. Metric variables, such as plasma protein fractions and iron, academic performance at the end of the last secondary grade and adult stature, were studied in relation to genetic markers, viz., sex, ABO, Xg, MN, Rh, haptoglobins, phosphoglucomutase, and esterase D, by means of unbalanced one way analyses of variance. Highly significant results were found for Rh phenotypes and total iron binding capacity (TIBC, transferrin). However, plasma iron did not differ significantly among Ph phenotypes. Children with the C (Rh) specificity had higher values of TIBC than non-C or c individuals (P less than 0.00001). Evolutionary considerations regarding iron transport and erythroblastosis, relationships between Rh and the transferrin receptor at the plasma membrane, and the location of the Blym-I oncogene (that shares common sequences with transferrins) close to Rh in chromosome 1 are discussed. Less significant results were found between phosphoglucomutase and stature, gamma globulin level and sex, and academic performance (history) and sex.

Analysis of Variance↗
PubMed1991

[Ultrasonic detection of fetal vernix in amniotic fluid as and index to fetal maturity].

The relationship between ultrasonographic detection of fetal vernix and visual assessment of amniotic fluid (AF) and fetal pulmonary maturity evaluated by the "shake test" was studied in 73 high-risk patients undergoing amniocentesis for obstetrical indications. The AF was classified as type I, type II, and type III, depending on the subjective amount of vernix detected. Ultrasound predicted correctly 7 out of 11 cases of type I AF (64%), 14 out of 22 cases of type II AF (64%), and 38 out of 40 cases of type III AF (95%). When ultrasonography detected type I AF the "shake test" was negative in all cases, whereas if type II or type III were found, the "shake test" was positive in 40% and 86%, respectively. Our results suggest that sonographic detection of type I AF is associated with immaturity, thus amniocentesis should be avoided in such cases. Conversely, if a type III AF is detected a mature fetus is found in almost 90% of the cases. The observation of AF detecting fetal vernix during third trimester sonography is a simple manoeuver that can help to avoid the use of amniocentesis, an invasive procedure associated with some serious fetal and maternal complications.

Amniotic Fluid↗
PubMed1991

[Concentrations of serum lipids in children with Down's syndrome].

The level of blood lipids in children with Down's syndrome was determined with the purpose of establishing possible differences in total cholesterol, triglyceride and HDL-cholesterol levels with those of healthy children. LDL-cholesterol fraction was calculated. Blood samples were obtained from 66 healthy children (controls) and 72 patients who suffered from clinically diagnosed Down's syndrome. All the children were grouped according to age. The variables of body weight, height, and blood lipids gave a distribution of values that allows one to distinguish the group of children with Down's syndrome from the normal group. The values obtained for triglycerides, total cholesterol, and LDL-cholesterol ranged higher, with a constant deficit of HDL-cholesterol in all age groups. The lipid pattern encountered in the Down's syndrome patient suggests the existence of unknown, possibly genetically determined mechanisms, that provoke a disorder in lipid metabolism.

Adolescent↗
PubMed1990

[Age of menarche and genetic blood markers].

In 160 girls from low and middle socio-economic class of Santiago we correlated the age at menarque with genetic markers such as ABO blood group, Rh, MN, Xg, haptoglobins, Esterase D and Phosphoglucomutase. No significant association of these markers and age at menarque was found.

Adolescent↗
PubMed1982

A large phenotypic sib-sib discordance for the Rh blood system. A possible new feto-maternal compatibility system.

A large sib-sib phenotypic discordance for the Rh system has been found in a longitudinal follow-up study on growth and development. Sibs born no more than 3 years later than their respective indexes show a significant tendency to have a different phenotype from that of their indexes. The hypothesis that distortion is due to eggs or fetal loss finds support in the existence of increased time intervals between indexes' and sibs' births in those cases in which the losses were suspected. Two groups of index families made according to the presence or absence of the cde haplotype in their genotype show important differences in segregation and reproductive patterns. The observed distortions cannot be explained by the differences in known antigenic Rh specificities. The existence of a new feto-maternal compatibility system would better fit these facts and would also allow the reinterpretation of several distortions associated with Rh described in the literature that have never been satisfactorily explained.

Birth Intervals↗
PubMedDate not supplied

[Parental socialization styles and psychosocial development in 16 to 19 year old adolescents].

To study relationships between perceptions that 16 to 19 year old adolescents have about socialization styles and disciplinary methods used by their parents, with their view of the world, interpersonal relations, moral development, use of psychotropic substances and maladjusted behaviours, 241 adolescents--123 males--which belong to a follow up study on growth and development from northern metropolitan Santiago, Chile, were asked to answer a questionary of psychosocial development, previously elaborated by two of the authors (GS and CA). The most used socialization styles by these fathers and mothers were the negative power one (39.2% and 38.5%) and the inductive one (23.8% and 30.0%), while permissive styles occurred at much lower frequency (1.5% and 1.1%). Coincidence among parents in socialization styles was found in 47.7% and disagreement in 19.2% of cases. The inductive style and coincidence in it's use by both parents, were frequently associated to idealistic world views, autonomous and conventional moral development, satisfactory interpersonal relationships and low frequency of psychotropic consumption, and maladjusted behaviours while negative power based styles by both parents and disagreement of styles among them were rather related to realistic or negative world view, preconventional moral development, higher frequency of relational problems, psychotropic consumption and maladjusted behaviours.

Adolescent↗
PubMedDate not supplied

[School achievement and neurologic examination: a 7-years' correlation study].

Neurological examination and school performance were analyzed in 146 children from a longitudinal follow up on growth and development at northern metropolitan Santiago, Chile. Their reading and writing abilities and their performance on neuro-maturational tests at the third elementary grade, were compared with academic achievements seven years later and highly significant correspondence was found among these terms. Reading comprehension and simple arithmetic problem solving abilities were the most affected aspects in children that exhibited multiple subtle neurological abnormal signs. Writing and design abilities were also involved up to a certain degree. Intellectual endowment was a determinant factor in this relationship since children above average. I.Q. showed less neurological involvement and better academic qualifications and vice versa. Subjects with many subnormal neuro-maturational signs had relative under-ratings at school examinations, whichsoever their mental level was. Thirty percent of the initial 208 study case were missed in the 7 year time span: Most of them were unable to read and write properly at third elementary school grade, showed evidence of several minor neurological failures and abandoned school in the mean time. By contrast, 96% of the index group could be reexamined. This bias implies that between early learning plus neurological status, at age 9 years and the later academic performance should have been an extremely positive interrelationship for the whole series.

Achievement↗
PubMedDate not supplied

[Growth related to menarche in women of middle and low socioeconomic status].

Growth after menarche is described in 149 six to twenty year old girls from a growth and development follow-up study in a northern suburb of Santiago. Mean height at menarche and final adult height were obtained. The mean post-menarche growth was 6.40 +/- 2.70 cm. There was a large dispersion in post-menarche growth; three of them grew more than 15 cm and one 22 cm. We conclude that prediction of post-menarche growth is uncertain.

Adolescent↗
PubMedDate not supplied

[Growth of girls and boys at puberty].

Growth at puberty varies according to age and individual maturity. Changes in height and weight of girls (aged 10 to 16 years) and boys (aged 11 to 17 years) which participate in a follow-up study at northern metropolitan Santiago, Chile, are described. Sexual maturity seems more determinant than chronological age on weight and height at puberty. For instance height of the whole sample of boys from 12 to 15.5 years of age ranged from 141 to 164 cm in contrast to 147 to 160 for those of the same age range but in the third stage of public hair development (Tanner). Sexual maturity should be taken into account for appropriate growth evaluation at puberty.

Adolescent↗
PubMedDate not supplied

[Widal reaction and phenotypes in children with typhoid fever (preliminary study)].

Recognition of genetic heterogeneity in typhoid fever patients might allow studies on the behaviour of definite cohorts regarding this infection, which would be important for clinical and epidemiological purposes. Under the hypothesis that agglutinins response (Widal test) is a suitable phenotype for this objective, associations between results of this response at admission (positive and negative) and clinical and hematological variables were explored in 91 children with bacteriologically confirmed typhoid fever, admitted to a metropolitan hospital at Santiago, Chile, during 1981-82 period. Association between gender and negative Widal test was found in males when this test was performed during the third week of disease (OR = 10, p = 0.52) as well as a tendency of females to express figures below the mean for total WBC count in patients older than 10 years (OR = 2.43, p = 0.019) and for neutrophils (%) in younger than this age when the Widal test was negative in the latter (OR = 10, p = 0.016). These preliminary findings suggest that Widal test and gender might interact for determining the presumptive heterogeneity in this children group.

Age Factors↗