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Biomedical subjects

L Leiva

Publications and source records attributed to L Leiva.

At least 19 recordsLinked to original sources
PubMed2006

Antibody response to pneumococcal capsular polysaccharide vaccine in Down syndrome patients.

The majority of children with Down syndrome (DS) tend to have frequent bacterial infections including recurrent respiratory infections. Our objective was to evaluate the production of antibodies to pneumococcal polysaccharide antigens after active immunization in DS subjects. IgG antibodies to pneumococcal serotypes (1, 3, 6B, 9V, and 14) were measured before and 6 weeks after immunization with a 23-valent pneumococcal vaccine (Pneumo23, Pasteur-Merrieux) in 6- to 13-year-old DS children (N = 17) and in aged-matched normal controls (N = 30). An adequate response was defined as a 4-fold increase over baseline or a post-immunization level of specific pneumococcal serotype antibody > or = 1.3 microg/mL. After immunization, all DS children had an increase in post-immunization levels against all serotypes analyzed. A 4-fold or more increase was observed in all DS children concerning serotypes 1 and 14, in 90% of subjects for serotypes 3 and 9V, and in 65% for serotype 6B. Regarding this increase, 8 of the 17 DS children had an adequate response to all serotypes analyzed, 8/17 patients to 4 serotypes and 1/17 to 3 serotypes. However, when we compared post-immunization levels between DS children and controls, we observed lower levels in the former group (P < 0.05) for all serotypes except serotype 3. We conclude that pneumococcal polysaccharide immunization could be beneficial for these DS children.

Adolescent↗
PubMed2004

Muscle and skin necrotizing and edema-forming activities of Duvernoy's gland secretion of the xenodontine colubrid snake Philodryas patagoniensis from the north-east of Argentina.

Philodryas patagoniensis is a colubrid snake spread by all South America, but very little is known about the composition and biological activities of its Duvernoy's gland secretion. In order to characterize it, we studied edematogenic, dermonecrotic and myonecrotic activities. For edematogenic activity, solutions containing different amounts of secretion were injected s.c. in the right foot pad of mice, both feet were subsequently cut off and weighed individually. For myonecrotic activity, mice were injected i.m. with solutions containing 40 microg of secretion, and at various time intervals mice were bled to determine serum creatine kinase activity and gastrocnemius muscles were removed for microscopic examination (Hematoxylin-Eosin stain). For dermonecrotic activity, solutions containing different amounts of secretion were injected into the shaved dorsal skin of mice; the necrotic lesion was measured on the inner surface of the skin and trimmed for microscopic examination (Hematoxylin-Eosin stain). Phospholipase A(2) activity was evaluated using a kinetic method. Results showed that P. patagoniensis Duvernoy's gland secretion exhibits a high edematogenic activity and moderate myonecrotic and dermonecrotic activities, while lacking phospholipase A(2) effect. Regarding edema, a 30% increase in the weight was produced by injecting 0.26 microg of Duvernoy's gland secretion. Microscopically, myonecrosis reached its highest intensity 12 h after injection, which was also demonstrated by serum creatine kinase levels. Dermonecrosis was proportional to the amount of secretion injected, with a minimum necrotizing dose of 15.7 microg. Myonecrotic, edematogenic and dermonecrotic activities were inhibited when the secretion was pre-incubated with 1 mM Na(2)EDTA. This suggests that the enzymes responsible for those activities are mostly metalloproeinases. All the studies carried out up to now demonstrate the potential toxicity of P. patagoniensis Duvernoy's gland secretion (which inhabits the north-east region of Argentina) and that the local lesions caused by this colubrid snake are very similar to those found in bothropic accidents. This latter suggests a more careful evaluation of the victims when considering the medical treatment to be adopted.

Analysis of Variance↗
PubMed2001

[Biological, familial and metabolic characteristics of infantile and juvenile obesity].

BACKGROUND: Obesity is the most prevalent nutritional disease in people of less than 20 years old. AIM: To report biological, familial and metabolic characteristics in obese children. PATIENTS AND METHODS: A retrospective review of 187 children seen at obesity clinics and that had a complete metabolic study. RESULTS: Ninety five prepuberal and 92 puberal children, aged 8.7 +/- 2.2 and 12.6 +/- 2.2 years old respectively, were studied. Body mass index was over 4 standard deviations in 48.4% of prepuberal children and in 39.1% of puberal children. Paternal obesity was twice more prevalent (30.2%) than in the general population. The daily caloric intake and basal metabolic rate (BMR) were within the normal range; nevertheless there was a positive caloric balance due to minimal physical activity. The mean daily fat intake was normal (26.4 +/- 8.5 and 25.3 +/- 9.1% of total calories in prepuberal and puberal children respectively). The daily fiber intake was under 70% of recommendation. The total cholesterol was over 200 mg/dl in 26.6 and 23.9% of prepuberal and puberal children. LDL cholesterol was over 130 mg/dl in 27.3 and 26.6% and triacylglycerol was over 150 mg/dl in 16.9 and 25% of prepuberal and puberal children respectively. Basal serum insulin was over 20 uIU/ml in 27.7 and 42.2% of prepuberal and puberal children, respectively. Post glucose serum insulin was over 60 uIU/ml in 40 and 63% of prepuberal and puberal children, respectively. CONCLUSIONS: Infantile and juvenile obesity is a chronic disease with a high incidence of metabolic alterations.

Adolescent↗
PubMed1999

Single and multiple selenium-zinc-iodine deficiencies affect rat thyroid metabolism and ultrastructure.

This study was conducted to evaluate the effects of single and combined deficiencies of Se, Zn and I on thyroid function in rats. Rats were fed amino acid-based diets for 6 wk starting from weaning. The diets contained either low or adequate amounts of these minerals. In addition to the control and control pair-fed groups, seven experimental groups were formed: Se deficient (Se-); I deficient (I-); Zn deficient (Zn-); Se and I deficient (Se-I-); Zn and I deficient (Zn-I-); Se and Zn deficient (Se-Zn); and Se, I and Zn deficient (Se-I-Zn-). Serum triiodothyronine (T3) was significantly lower than in controls in Zn-, Se-Zn- and Se-I- groups. Serum total thyroxine (T4) and free T4 were significantly lower and thyroid-stimulating hormone (TSH) greater in all iodine-deficient groups, regardless of Se or Zn status. Thyroid glutathione peroxidase activity was significantly reduced in Se- and Se-Zn- groups. Nevertheless, in the groups with a concurrent I deficiency, the activity of this enzyme was significantly greater than in controls. Severe alterations of the follicle cellular architecture, including signs compatible with apoptosis, were observed in the Zn- and Se-Zn- groups. These alterations appeared to be less severe when iodine deficiency was simultaneously present. Single and multiple deficiencies of Se, Zn and I have distinct effects on thyroid metabolism and structure.

Animals↗
PubMed1997

[Iodine nutrition in school children of four census areas of Chile].

BACKGROUND: Although endemic goiter is an easily controlled chronic disease, it continues to be a serious global public health problem. AIM: To study iodine nutrition in school age children from different areas of Chile. SUBJECTS AND METHODS: Thyroid gland was palpated in 4181 school age children from Calama, Santiago, Temuco and Punta Arenas. Urinary iodine excretion was measured to 9% of these children and iodine concentration in salt for human consumption obtained in each of these areas was determined. RESULTS: A 9% goiter prevalence in boys and 11% prevalence in girls was detected. The prevalence of goiter Ia was 6.5% and the figure in different geographic areas was similar. Iodine concentration in salt for human consumption was adequate according to Chilean legislation (82.6, 95.7, 96.8 and 93.2 micrograms ugI/g salt in Calama, Santiago, Temuco and Punta Arenas respectively). Urinary iodine excretion in boys and girls was 1695 and 1802 micrograms l/g creatinine in Calama, 680 and 732 in Santiago, 574 and 690 in Temuco, 570 and 528 in Punta Arenas. These values are well above recommendations. CONCLUSIONS: Endemic goiter is no longer a problem in Chile. The importance of a continuous surveillance of iodine nutrition in Chile and the reduction of salt iodine concentration required by Chilean legislation is underscored.

Censuses↗
PubMed1996

[immunization and immune response to pneumococcal vaccination].

The aim of this work was to define antibody levels against four neumococcal serotypes, before and after neumococcal vaccination in patients with respiratory infections. Fifty one patients were studied, 19 children from 1 to 5 years old; children from 6 to 18 years old and 22 adults from 27 to 65 years old. IgG anti-neumococcal, antibodies, against weeks after vaccination. There was a significant increase in antibody titers against all serotypes in subjects older 7 years. In children of less than 6 years, the response to serotype 14 was non significant. The intensity of response differed according to the studied serotype and the percentage of patients that responded to each serotype increased with age. Five patients older than 18 years were identified as non responders to all four serotypes. It is concluded that neumococcal vaccine increases anti-neumococcal antibodies in patients with recurrent infections and allows the identification of patients with specific antibody deficiency syndromes and normal total immunoglobulin levels.

Adolescent↗
PubMed1996

[Bone mass in celiac patients].

Bone mineral content was measured in the whole body, the spine (L2-L4) and hip by Dual Photonic Absorpciometry (densitometer Norland 2600 Gd-153), in seventeen celiac patients, aged 6 to 12 years, with good adherence to the gluten free diet. The diagnosed was made before 30 months of age in 50% of cases. Average treatment duration was 69.8 +/- 36 months. The randomly selected control group was composed of 48 school age children, of the same age and sex of patients. Total bone mass (TBM) and bone mineral density (BMD) were expressed as Z scores on the basis of normal values established by the authors in Chilean children. Celiac patients had lower TBM and BMD of whole body, than controls (-1.11 +/- 0.94 vs 0.00 +/- 0.85 and -0.59 +/- 0.76 vs 0.06 +/- 0.84, respectively) and at the spine (-0.79 +/- 1.04 vs 0.003 +/- 0.92 and -1.49 +/- 0.99 vs 0.06 +/- 0.87 respectively). A lower TBM was founded at the hip (-0.62 +/- 1.28 vs -0.08 +/- 0.82) without differences in BMD. Celiac patients had a lower bone mass than controls despite early diagnosis and good compliance with the gluten-free diet. These differences could not be atributed entirely to the lower height of celiac patients. These results suggest that celiac patients constitute a risk group for development of osteoporosis later in life. This fact should be taken into consideration in the treatment of this condition.

Bone Density↗
PubMed1995

Follicle stimulating hormone-granulosa cell axis involvement in the antifolliculotrophic effect of low dose mifepristone (RU486).

This study was designed to assess the involvement of follicle stimulating hormone (FSH)-granulosa and luteinizing hormone (LH)-theca axes in the antifolliculotrophic effect of mifepristone. Plasma gonadotrophins, including plasma LH bioactivity and pulsatility, oestradiol, testosterone and inhibin concentrations, and follicular growth were monitored in volunteer women treated with placebo or mifepristone in two consecutive cycles. Mifepristone was given either as a single dose of 5 mg (n = 7) when the leading follicle had reached a diameter between 12 and 14 mm, or as a multiple dose of 5 mg/day for 3 days, beginning when the leading follicle had reached a diameter between 14 and 16 mm (n = 5) or between 6 and 11 mm (n = 5). Following the single dose of mifepristone, follicular growth and the accompanying increase in plasma oestradiol were arrested at 12 and 36 h respectively without changes in gonadotrophin or testosterone serum concentrations. The 3 day regimen arrested follicular growth and oestradiol rise and decreased plasma inhibin concentrations when follicles were larger than 12 mm at the onset of treatment. These results indicate that the antifolliculotrophic action of mifepristone is associated with a selective compromise of the FSH-granulosa axis of dominant follicles that have passed a critical stage of growth.

Adult↗
PubMed1995

[Bone mineralization and calcium intake in Chilean school children].

Bone mineralization was evaluated in 36 school age children with calcium intake below 50% of Recommended Dietary Allowances (RDA), and compared with 28 school age children with calcium intake higher than 100% of the RDA. The total group was aged between 86 and 178 months. The calcium intake was evaluated by 24 hours recordatory survey. Height for age and weight for height were evaluated according to WHO tables. Puberal development was evaluated according to Tanner stages. Bone mineral density (BMD) and total bone mass (TBM) of whole body, spine and femoral neck were measured with Norland 2600 densitometer. School age children with intakes below 50% of RDA had lower height for age adequation (97.7 +/- 4.0%), whole body TBM adequation (98.9 +/- 17.9%) and BMD adequation (97.8 +/- 7.9%) than those ingesting more than 100% of the RDA (115.9 +/- 17.4%), (109.7 +/- 18.0%) and (104.7 +/- 11.1%) respectively. In spine, however, there was a clear tendency to be lower, there were no significant differences between both groups. There were no differences in femoral necks BMD adequation, or TBM adequation between both groups. These results show that children with calcium intake below 50% of the recommendation has lower adequation of statural growth and bone mineralization. The role of calcium in the differences found in this study is discussed.

Adolescent↗
PubMed1995

[Bone mineralization in adolescents suffering from postnatal malnutrition].

The bone mineralization of 6 male and 18 female adolescents with a mean age of 12 years and 11 months, who had suffered severe, early, postnatal protein-energy undernutrition, was analyzed. These patients have been followed up at our Institute since their nutritional rehabilitation. Bone mineralization was measured by bone dual isotopic densitometry (Gd 153). These results were compared with those of normal school-age Chilean children of the same age and sex. Weight for height of adolescent who had suffered from undernutrition was similar to the controls, and both were over 100% of the standard. Adequation of height for age was significantly less in those with previous history of undernutrition. Densitometries showed that adolescents with a past history of undernutrition had lower total bone mass in whole body, spine and femoral neck; differences disappeared when expressed per 100 cm of body height. There were no differences in bone mineral density in the different area measurements. It is concluded that the possible alterations that undernutrition produces in bone mineralization probably recover after nutritional rehabilitation, adequate nutritional follow up and health support.

Calcification, Physiologic↗
PubMed1994

Quantitation of soluble HLA class I heterodimers and beta 2-microglobulin in patients with active pulmonary tuberculosis.

Beta 2m serum levels have been shown to be increased in patients with tuberculosis and HIV infection. We determined the stability of beta 2m and of sHLA-I dimers in serum, and then determined the levels of both molecules in 60 non-HIV-infected patients with active pulmonary tuberculosis and in 55 adult controls. The levels of sHLA-I in samples kept at room temperature declined by 8% at 30 minutes, 16% at 60 minutes, and 36% at 120 minutes. Beta 2m levels remained stable at all times tested. Mean sHLA-I levels were 0.99 +/- 0.16 micrograms/ml in controls and 1.34 +/- 0.11 micrograms/ml in patients with tuberculosis (P < 0.0001). Beta 2m levels were 1.23 +/- 0.26 micrograms/ml in controls and 2.26 +/- 0.64 micrograms/ml in patients with tuberculosis (P < 0.0001). All patients with tuberculosis had elevation of sHLA-I and/or beta 2m above 1 standard deviation of normal values. However, there was no correlation between sHLA-I and beta 2m levels in individual samples. Evaluation of sHLA-I holds the promise of further understanding of the biology and genetic regulation of the immune response to mycobacterial infection.

Adolescent↗
PubMed1994

Effects of RU486 on the ovarian response of immature rats to pregnant mare's serum gonadotrophin or diethylstilbestrol.

The purpose of this study was to further investigate the role of progesterone in follicular development induced by pregnant mare serum gonadotrophin (PMSG) or diethylstilbestrol (DES), in pre-pubertal rats, using RU486 to prevent the receptor-mediated actions of progesterone. Intact or hypophysectomized 26-day-old rats received either a single injection of 10 IU PMSG i.p., or 2 mg DES s.c. daily for 3 days, with or without 0.8 mg RU486 s.c. daily for 3 days. Groups of rats were killed 51-96 h after the first injection. RU486 significantly increased the ovarian weight gain, the ovarian and circulating concentrations of progesterone, the concentrations of immunoreactive and bioactive LH and the number of ovulated oocytes in intact rats. RU486 did not affect the ovarian weight increase induced by PMSG or the ovulatory response following PMSG plus human chorionic gonadotrophin (HCG) in rats hypophysectomized 24 h before initiating treatment or in intact rats where ovulation was blocked with chlorpromazine. The ovarian weight gain, the development of antral follicles and the increments in tissue and plasma progesterone concentrations and luteinizing hormone (LH) plasma concentrations elicited by DES in intact rats, were further increased by concomitant treatment with RU486, whereas the ovarian weight increase and antral follicle development induced by DES were completely inhibited by RU486 in hypophysectomized rats. Follicles stimulated to grow by DES plus RU486, but not by DES alone, were capable of ovulating in response to HCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Endemic goiter in three census areas of Chile].

The goal of the present study was to evaluate the current status of endemic goiter in Chile. 3500 students of basic education from public schools in three censor areas of the country were studied: 1000 in Calam (North), 1000 in Temuco (South) and 1500 in Santiago (Center). Socio-economic level was evaluated according to the Graffar scale. Two trained physicians determined body weight, height and size of the goiter through palpation of the thyroid gland (according to W.H.O. classification). Iodine in urine was determined in 20% of the students. Iodine insalt was determined in samples obtained in the three areas. A goiter prevalence of goiter of 11.4% in males and 12% in females was found, with a higher prevalence in females during puberty. A higher prevalence in the medium-low and low socio-economical levels was observed (12.4% and 14.4% respectively). The level of salt iodination was variable in the three areas (1/3 with concentration > than 100 parts per million (ppm), 1/3 between 60-100 ppm and 1/3 with < 60 ppm of iodine content). According to W.H.O. criteria, Chile has presently a low goiter prevalence, but the salt iodine concentration indicate the importance of a permanent surveillance of iodine nutrition.

Adolescent↗
PubMed1994

[Bone mineralization in Chilean children determined by dual photon bone densitometry].

In 198 school age children, aged 6 to 13 years, the bone mineral density (BMD) and total bone mass (TBM) was measured in total body, lumbar spine and hip, using a double beam photon densitometer with a Gd 153 source. An increase with age of BMD and TBM was found in all the analyzed areas. At 12 years of age, TBM and BMD of total body were higher in girls than in boys. BMD of lumbar spine was significantly higher in girls than in boys at ages between 11 to 13 years. BMD of lumbar spine and femoral neck of 9 years old females were 36% and 18% respectively, lower than values of young adult Chilean females. The importance of normal values of bone mineralization for the diagnosis of bone diseases and for the evaluation of programmes directed to solve this problems is emphasized.

Absorptiometry, Photon↗
PubMed1990

The hypothalamic-pituitary-adrenal axis in infantile malnutrition.

We studied the circadian rhythm and the response of the hypothalamic-pituitary-adrenal (HPA) axis to ovine corticotrophin releasing hormone (oCRH) stimulation and dexamethasone suppression in 32 children with grade II-III marasmus. Children were studied prior to and after nutritional rehabilitation. Mean baseline plasma cortisol concentrations were elevated at admission and decreased significantly after nutritional rehabilitation. Mean +/- SEM plasma cortisol response to oCRH increased from a basal of 480 +/- 41 to a peak of 582 +/- 58 nmol/l at the time of admission, and from a basal of 234 +/- 27 to a peak of 532 +/- 41 nmol/l after caloric rehabilitation. Dexamethasone suppression in the malnourished group was associated with a decrease in the mean +/- SEM basal plasma cortisol concentration from 397 +/- 44 to 171 +/- 44 nmol/l. After caloric rehabilitation, basal cortisol levels decreased from 259 +/- 27 to 22 +/- 5 nmol/l following dexamethasone. Our results support the concept that malnutrition is associated with decreased responsiveness to oCRH and incomplete dexamethasone suppression, and that these abnormalities are restored after nutritional rehabilitation.

Child, Preschool↗