Biomedical subjects

Lars A Hanson

Publications and source records attributed to Lars A Hanson.

23 records · Page 2Linked to original sources

PubMed2002

The relationship among markers of allergy, asthma, allergic rhinitis, and eczema in Costa Rica.

The association between allergy markers and asthma and allergic rhinitis is stronger in countries with a Western lifestyle than in rural areas of Africa and Asia. We examined the relationship among allergy markers, asthma, rhinitis, and eczema in a case-control study of 198 schoolchildren, 10-13 years of age, living in Costa Rica, a Latin American country. The geometric mean total serum immunoglobulin E (IgE) level in subjects with and without asthma was 465.0 and 143.0 IU/ml, respectively (difference = 322 IU/ml, 95% CI = 141.8-616.1 IU/ml, p < 0.001), and that in subjects with and without allergic rhinitis was 442.5 and 144.3 IU/ml, respectively (difference = 298.2 IU/ml, 95% CI = 125.7-581.0 IU/ml, p < 0.001). After adjusting for age, gender, and skin test reactivity to allergens, we found a linear relationship between serum total IgE level and the log odds ratio (OR) of having asthma. In a multivariate analysis, there was a linear relationship between skin test reactivity to allergens and the log OR of having allergic rhinitis. The OR of having allergic rhinitis was almost three times higher in children who had four positive skin tests than in non-reactors. Skin test reactivity to greater than five aeroallergens was an independent predictor of eczema in a multivariate analysis (OR = 3.1, 95% CI = 1.1-8.4). Although the geometric mean total serum IgE levels of Costa Rican children with either asthma or allergic rhinitis are higher than those of children with asthma or allergic rhinitis in most industrialized countries, the relationship among markers of allergy, asthma, rhinitis, and eczema in Costa Rica is similar to that found in countries with a Western lifestyle and different from that found in rural areas of Asia and Africa.

Allergens↗

PubMed2002

Epidemiological studies of the very high prevalence of asthma and related symptoms among school children in Costa Rica from 1989 to 1998.

The aim of our study was to determine the prevalence of asthma and related respiratory symptoms in school children from Costa Rica during the last 10 years, from 1989 to 1998. Using nationally representative samples of school children from Costa Rica during the last 10 years we have performed three studies. Altogether 9,931 children were investigated. The age groups: study I, 5-17 years (n = 2,682), study II, 6-7 years (n = 2,944), 13-14 years (n = 3,200) and study III, 10 years (n = 1,105). The diagnostic criteria for asthma used in these studies was as follows: study I (1989), diagnosis by a doctor in combination with the presence of four kinds of respiratory symptoms; studies II (1995) and III (1998), history of wheeze in the past 12 months. The two latter were part of the International Study of Asthma and Allergies in Childhood (ISAAC). A very high prevalence of a history of wheezing was found in the three studies (46.8%, 42.9%, and 45.1%) as well as a diagnosis of asthma (23.4%, 27.7% and 27.1%). The physician's diagnosis of asthma reported in the first study (23%) increased from 23.1 in study II to 27.7% in study III (p = 0.004). This increment could be a real increase in asthma prevalence, or be due to a better awareness about asthma. In study II the group of 6-7-year-olds had respiratory symptoms significantly more often than 13-14-year-olds (p < 0.001). Boys more often had a history of wheezing (p = 0.001), wheeze during the previous 12 months (p = 0.01) and an asthma diagnosis at the age of 6-7 years (p = 0.002) than girls, but girls had more respiratory symptoms than boys at the age of 13-14 years (p < 0.005). Wheezing in the past 12 months was more common for those living in urban areas aged 6-7 years (p = 0.04), and there was an increase of wheeze after exercise (p = 0.01). For the 13-14-year-olds the risk of wheezing was higher during the previous 12 months if they lived in temperate areas (<20 degrees C) and at a high altitude (>1,000 m). Living in a rural area and in a warm region (>20 degrees C), increased the risk of dry cough during the previous 12 months in the group of 13-14-year-olds. In conclusion, Costa Rica is located in the tropics with a very high humidity, an enormous variety of flora and fauna and a very high prevalence of mite and cockroach allergens, which provide important risk factors that may explain the high prevalence of asthma and asthma-related symptoms. Further possible factors, such as the change towards a more Western life style, resulting in fewer infections and parasitic diseases in the first years of life and changes in bedding material, may also be unresolved. Increased environmental pollution may add to the very high prevalence of asthma and related respiratory symptoms. The very extensive exposure to mites and cockroaches in bed material and in homes with poor ventilation may be an important factor, but many asthmatic children behave as non atopic, with a viral respiratory infection as a major precipitating factor.

Adolescent↗

PubMed2002

Long term enhancement of the IgG2 antibody response to Haemophilus influenzae type b by breast-feeding.

SUBJECTS: Sets of sera were obtained from 30 children <6 years of age with invasive type b (Hib) infection and their mothers. Duration and mode of breast-feeding were monitored. Titers of IgG1, IgG2, IgA and IgM antibodies against Hib capsular polysaccharide were determined in sera taken during the acute illness and during early and late convalescence. RESULTS: Children 18 months or older with longer durations of exclusive breast-feeding (13 weeks or more; mean, 19.3 weeks) had higher Hib antibody concentrations of the IgG1, IgG2, IgA and IgM isotypes than those with a shorter duration of exclusive breast-feeding (<13 weeks; mean, 5.4 weeks). The difference was greatest for the IgG2 isotype. In regression analyses the association between the duration of exclusive breast-feeding and the anti-Hib IgG2 concentration was significant when breast-feeding, type of Hib infection, maternal Hib antibody titer and age were used as explanatory factors. In the group of 14 children <18 months of age no significant differences were noted. DISCUSSION: This study indicates the presence of a long lasting enhancing effect of breast-feeding on the antibody response to Hib in children, in particular on IgG2 Hib antibody production. This may result from the content in the milk of IFN-gamma and IFN-gamma-producing cells and possibly other factors, which can support IgG2 antibody production.

Age Factors↗

PubMed2002

Aberrations in placental cytokine mRNA related to intrauterine growth retardation.

During normal pregnancy, a predominance of Th2 type cytokines prevails and is considered to protect the fetus. Animal experiments suggest that an increase of Th1 type cytokines may instead have deleterious effects. We have studied with the reverse transcription PCR technique mRNA for IL-1alpha, IL-1beta, IL-6, IL-8, IL-10, transforming growth factor-beta, tumor necrosis factor-alpha, and interferon-gamma in placentas from full-term appropriately grown newborns, newborns with intrauterine growth retardation (IUGR) and newborns who were only small for gestational age. The mRNA for IL-10 was significantly reduced in the IUGR placentas (p < 0.05), whereas the mRNA for IL-8 was significantly higher (p < 0.05) for the IUGR cases compared with the full-term neonates. It might be that reduced IL-10 in the placenta is involved in the pathogenesis of IUGR.

Animals↗

PubMed2002

Breast-feeding, a complex support system for the offspring.

The newborn has an immune system, very limited in size at birth and its postnatal expansion and maturation takes time. In the meantime the transplacental IgG antibodies from the mother play an important role for the protection of the infant. However, these antibodies act in tissues and induce inflammation and are energy-consuming. In contrast, the milk secretory IgA antibodies stop microbes already on the mucosa preventing infection, tissue engagement and energy loss. In addition, the milk contains many protective factors such as lactoferrin and oligosacharides functioning as analogues for microbial receptors preventing mucosal attachment, the initial step of most infections. As a result, breast-feeding significantly reduces the risk of neonatal septicemia, respiratory tract infections, otitis media, diarrhea, urinary tract infections, infection-induced wheezing and necrotizing enterocolitis. Via several mechanisms it seems that human milk can actively stimulate the immune system of the breast-fed infant. This reduces the risk of infections like otitis media, respiratory tract infections, diarrhea and infection-induced wheezing for several years after the termination of breast-feeding. Furthermore, it seems that breast-feeding decreases the risk of attracting celiac disease and allergic diseases. The latter has been much debated, but a recent critical review of published reports gives good support for long-term protection of allergic diseases, especially in high-risk children.

Breast Feeding↗