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Biomedical subjects

J Karlberg

Publications and source records attributed to J Karlberg.

At least 55 records · Page 3Linked to original sources
PubMed1998

Allergen sensitization of asthmatic and nonasthmatic schoolchildren in Costa Rica.

The prevalence of asthma among schoolchildren in Costa Rica is very high -- at the level of 20-30% -- and the reason is still unknown. A group of children from our previous epidemiologic study was randomly selected in order to establish the relation between asthma symptoms and allergy sensitization to common allergens. Serum samples from children with and without asthma were analyzed for the presence of IgE antibodies to 36 different allergens, for the presence of IgE antibodies to a pool of 10 common allergens, and for total serum IgE. The most prevalent IgE antibodies were those to mite, cockroach, dog, and house-dust allergens with MAST pipettes for the serologic measurements. Positive reactions to house dust, mite, cat, and the two molds (Alternaria and Cladosporium), and food allergens such as egg white, peanut, and shellfish were significantly more prevalent among the asthmatics than the nonasthmatics. Sensitization was equally prevalent at different ages, but the house-dust, mite, cat, dog, cockroach, Alternaria, and egg-white allergens had sensitized boys more often than girls (P < 0.01). The result of the analysis of IgE antibodies to a pool of 10 common allergens by Phadiatop supported the MAST pipette results, showing allergen sensitization in 57.7% of the asthmatic children and 42.3% in the nonasthmatic group. The concentration of IgE was significantly higher among the asthmatic children (372.2 kU/l) than among the nonasthmatic children (249.1 kU/l) (P < 0.00001). Parasitic infestations were not examined in this study, but in most of Costa Rica these have largely been eliminated and could not explain the high total IgE levels. Our data indicate that the very high prevalence of bronchial asthma in Costa Rican schoolchildren can be related to sensitization, especially to airborne indoor allergens such as those of mites, cockroaches, and dogs.

Allergens↗
PubMed1998

Modification of the MTT method for the study of bilirubin cytotoxicity.

BACKGROUND: We propose a modification of the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] method to study the cytotoxicity of bilirubin. The original method involves reading the intensity of a purplish blue color resulting from the conversion of MTT to formazan crystals by the mitochondria of viable cells. We have found that when the method is applied to study the effect of bilirubin on growing cells, precipitation of the yellow bilirubin pigment interferes with the colorimetric reading. METHODS: A human liver cell line was used. The interference of bilirubin deposition on the MTT assay was investigated by comparing the value of optical density of the MTT solution in the presence and absence of bilirubin. The effect of 0.04 mol/L HCL-isopropanol on the bilirubin precipitate was tested by recovering the amount of bilirubin from the wells after the isopropanol treatment. RESULTS: Bilirubin deposition increases MTT reading by 10-24%. Hydrochloride-isopropanol (0.04 mol/L) dissolves MTT formazan only without disturbing the bilirubin precipitates. The bilirubin extracted into the supernatant was less than 5% of the total bilirubin deposited. DISCUSSION: This indirect MTT assay, as developed in this study, could eliminate the interference of bilirubin deposits and serve as a good method for the study of bilirubin cytotoxicity.

2-Propanol↗
PubMed1998

Children born small-for-gestational age: postnatal growth and hormonal status.

It is generally recognized that children born small-for-gestational age (SGA) have a 5-7 times higher risk of short stature than children born at normal size. It has been suggested that the programming of the endocrine axes occurs during critical phases of fetal development and is affected by intrauterine growth retardation. This study was undertaken to characterize the postnatal growth pattern and the final height of children born SGA, as part of a population- based study (n = 3,650), from birth to final height, and to evaluate the hormonal status in another group of prepubertal children born SGA (n = 134) without postnatal catch-up growth. The majority (88%) of 'healthy' full-term singleton SGA infants achieved catch-up growth during the first 2 years of life, and most of the increase in height occurred by 2 months of age. The SGA children who remained short at 2 years of age had a higher risk of short stature later in life. The risk of having a short final height (<-2 SDS) was five times higher for children with a low birth weight and seven times higher for those with a low birth length in comparison with children with a normal birth size. Moreover, about 20% of all children of short stature were born SGA. As a group, children born SGA will have a final height, expressed in SDS, as they had during the prepubertal years. This is in contrast to children, who became short postnatally. During puberty, these short children will have a mean height gain of 0.6 SDS for girls and 0.7 SDS for boys. The mean estimated secretion rate for growth hormone (GH) was lower in the short children born SGA compared with the reference groups born at an appropriate size for gestational age, of either short (p < 0.05) or normal stature (p < 0.001). Moreover, in the youngest children born SGA (2-6 years of age) a different pattern of GH secretion was found, with a high basal GH level, low peak amplitude, and high peak frequency. The majority of the children born SGA had levels of GH-binding protein within the range previously reported for normal children. However, the levels of insulin-like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3) and leptin were significantly reduced compared with the reference values (p < 0.001, p < 0.01 and p < 0.001, respectively). In conclusion, the low spontaneous GH secretion rate and a disturbed GH secretion pattern, together with low serum levels of IGF-I, IGFBP-3 and leptin, might contribute to the reduced postnatal growth in some of the subgroup of children born SGA who remained short during childhood.

Age Factors↗
PubMed1998

High seroprevalence of Helicobacter pylori in active bronchiectasis.

Helicobacter pylori causes chronic inflammation of the gastric mucosa and has been identified in tracheobronchial secretions. Serum IgG against H. pylori was therefore measured prospectively in consecutive subjects with bronchiectasis (n = 100; mean age +/- SD 55.1 +/- 16.7 yr), active pulmonary tuberculosis (n = 87; age, 57.3 +/- 19.1 yr), and healthy volunteers (n = 94; age, 54.6 +/- 7.6 yr). Seropositivity was found in 76.0% of bronchiectatic subjects, which was significantly higher than that of the control (54.3%, p = 0.001) and tuberculous (52.9%, p = 0.0001) groups. Multiple logistic regression, adjusted for age, sex, occupational social class, and number of persons living in the household, showed that H. pylori IgG levels of the bronchiectatic group were still significantly higher than that of the control (p = 0.0014) and tuberculous (p = 0.0154) groups. Multiple regression analysis revealed associations between H. pylori serology and sputum volume (p = 0.03) and age (p = 0.001) in the bronchiectatic patients, but not lung function indices or causes of bronchiectasis. The H. pylori seroprevalence in bronchiectasis was significantly (p = 0.0002) higher in patients who produced more (83.1%) than those who produced less than 5 ml sputum/24 h (58.6%). This is the first report of a high H. pylori seroprevalence in bronchiectasis which appears to be specific. Further studies are indicated to evaluate the possible pathogenic role of H. pylori in bronchiectasis.

Age Factors↗
PubMed1998

Target height as predicted by parental heights in a population-based study.

The corrected midparental height method was introduced by Tanner in 1970 (Tanner method) and is commonly used to estimate target height in children to evaluate the effectiveness of growth-promoting therapies. It has not been established if the equation used to compute target height should be the same for children with short, normal, or tall parents. In this study, we examined the predicted target height values by parental heights in a large population-based study (n = 2402). A simple linear function of midparental height (x) was proposed to estimate target height (y): y = 45.99 + 0.78x (boys), y = 37.85+0.75x (girls), with a 95% predicted interval of about +/-10 cm. The prediction model was similar for boys and girls in SD scores (SDS), and was not affected by assortative mating or difference in parental heights. The model may underestimate the potential stature by about 2 cm for children with midparental height below -2 SDS, or 163 cm. In comparison, the Tanner method may lead to a 6-cm error in underestimating target height for these children. The function would be a better choice than the Tanner method for estimating target height in the clinical evaluation of growth promotion treatments because it is common that short children also have short parents. Children with very short parents will usually be much taller than their parents in adult stature, and we believe that a different function should be developed. The results support the proposed nondominant, non-sex-linked, polygenic inheritance in stature. The estimated heritability values were 0.75-0.78 in cm or 0.55-0.60 in SDS.

Adult↗
PubMed1998

Length and body mass index at birth and target height influences on patterns of postnatal growth in children born small for gestational age.

OBJECTIVE: Previous growth studies on children born small for gestational age (SGA) indicate that birth length, weight, and target height are important predictors for postnatal catch-up growth in SGA. Their influences on different phases of catch-up growth are still not described. The aim of this study was to clarify the influences of target height, length, and nutritional status at birth on different phases of postnatal catch-up growth (infancy, childhood, puberty) in SGA and the long-term consequences. METHODS: Data were obtained from a longitudinal population-based growth study on Swedish children (N = 2815). Primary outcome measurements include heights, the changes in height standard deviation scores (SDS) during various phases of growth and relative risk for adult shortness. RESULTS: The difference in final height in children born SGA was attributable to their difference in target height and the magnitude of catch-up growth during the first 6 months of life, rather than the difference in length or body mass index (BMI) at birth. Length at birth showed negative influence on catch-up growth during infancy (0 to 2 years of age), but no significant influence thereafter. The BMI or weight for length SDS at birth showed no significant influence on catch-up growth during any growth phase. Target height showed positive influence on catch-up growth from the onset of childhood. Neither target height nor length and BMI at birth showed any significant influence on catch-up growth during puberty. The magnitude of catch-up growth during infancy, especially the first 6 months of life, is most critical in decreasing risk at adult shortness. We confirmed that the SGA group had a sevenfold greater risk for adult shortness than the non-SGA group (relative risk = 7.31; 95% confidence interval: 3.96-13.52). However, approximately 40% of children who were below -2 in height SDS at 2 years of age remained short at final height in both SGA and non-SGA groups. The mean height SDS of children born SGA increased by 1.65 from birth to final height, but the length deficit in centimeters at birth (-5.4 cm) persisted into adulthood (-5.9 cm). CONCLUSIONS: BMI at birth is not related to postnatal catch-up growth in infants born SGA, but birth length and target height are important. The genetic influence on catch-up growth appears to start from the onset of childhood. Being born short or becoming short during the first 2 years of life is similar in terms of risk for adult short stature.

Body Height↗
PubMed1998

The effect of platyspondyly and pubertal growth spurt on the stature of patients with beta-thalassaemia major.

OBJECTIVE: To study the effect of the body proportion and pubertal growth spurt on the stature of children with beta-thalassaemia major. METHODS: The height, sitting height, upper to lower segment (U:L) ratio and pubertal development were determined in 71 Chinese children (38 girls and 33 boys) with beta-thalassaemia. The growth patterns of 20 patients with complete growth data between 3 years and final height, were analyzed according to whether they underwent a pubertal growth spurt or not. RESULTS: 27% of the boys and 32% of the girls had a height below the 3rd percentile. About 60% of all the children had a U:L ratio below the 10th percentile for age. Abnormal body proportion was found in patients with or without growth retardation. 34% of the 41 children over the age of 14 years underwent spontaneous puberty. In 28 patients over the age of 16 years, a growth spurt was observed in 46% of the children during spontaneous or induced puberty. The retrospective analysis showed that the height deviation from the mean in adulthood was significantly higher in patients without pubertal growth acceleration than in those with a growth spurt (x = -11.8 cm, s = 7.6 cm vs x = -4.4 cm, s = 4.4 cm; P = 0.02). CONCLUSIONS: An abnormal U:L ratio was commonly observed in patients with beta-thalassaemia major and may be one factor contributing to the short stature of these patients. Abnormal puberty was present in a significant proportion of children and the lack of a pubertal growth spurt was found to be detrimental to adult height.

Adolescent↗
PubMed1998

Hong Kong clinical trials published in Medline between 1987 and 1996.

The aims of this study were to determine the number of randomised clinical trials where the correspondence address included the words 'Hong Kong' for the years of publication between January 1987 and December 1996, and to study their characteristics: year of publication, disease area, sample size, and correspondence address of the department and institute; MEDLINE EXPRESS was used for the search. A total of 5605 publications were identified, of which only 170 (3.0%) were found to be randomised clinical trials. No significant increase in the proportion of randomised clinical trials could be seen during the decade of publication (P>0.05). Approximatley 50% of the trials had a small sample size (fewer than 75 subjects) and most randomised clinical trials were performed in the field of internal medicine, followed by surgery, and obstetrics and gynaecology (total, 69%). The predominant research area was gastrointestinal disease (34%). Despite a relatively high academic output from Hong Kong, the number of randomised clinical trials has not increased much during the decade.

Journal Article↗
PubMed1998

The need for a clinical trials research methodology training programme in Hong Kong.

Training courses in the concepts of clinical trials research methodology that include rules in good clinical practice have not yet been extensively implemented in Hong Kong. This study aims to define the current knowledge of rules in good clinical practice and identify any need for such training programmes. Between May and August 1996, 161 clinical research staff were asked non-randomly to fill in a questionnaire about their knowledge of research methodology and their interest in specific courses. The median number of correctly answered questions (maximum score, 20) was 5 and the mode was 4, which was the expected score if questions had been answered randomly. Only minor differences in score were detected between doctors, research staff, and industry employees. Many researchers were keen, however, to further their knowledge by attending future courses; on average, each person showed an interest in three of the eight proposed courses. The study shows that the knowledge of rules in good clinical practice among clinical research staff in Hong Kong is poor, but there is nevertheless a demand for training programmes.

Journal Article↗
PubMed1998

Evidence-based medical practice: as viewed by a clinical epidemiologist.

Evidence-based medicine shifts the basis for clinical decision making from intuition and unsystematic clinical experience to the examination of evidence resulting from clinical research. Evidence-based medicine is the same as good clinical research. The selection of a proper study design for a specific study objective is the most important cornerstone of good clinical research. Evidence-based medicine places great importance on the design of a study, with optimum evidence being obtained from the randomised, controlled clinical trial. However, various study designs are equally important-if properly used-in the process of searching for solid and important evidence for use in clinical practice. There should be an emphasis on a quality improvement shift in research design from retrospective to prospective, cross-sectional to longitudinal, uncontrolled to controlled, and non-randomised to randomised. The reasons for using suboptimal study designs in clinical research are the lack of formal research training and the pressure to obtain academic output without being motivated. Research design is one of the most important aspects to study and practice, and there are four simple rules: (1) avoid retrospective studies; (2) focus on prospective studies; (3) use controls, randomisation, and blinding; and (4) always discuss the research design with an experienced researcher or statistician before commencing the study.

Journal Article↗
PubMed1997

Spontaneous growth in Chinese patients with Turner's syndrome and influence of karyotype.

The pretreatment mixed cross-sectional and longitudinal height measurements of 203 patients with Turner's syndrome (TS) were analysed. Only one observation was included per year per child and a total of 858 observations formed the basis of the growth study. The mean and SD values were fitted separately by a second-degree polynomial function, giving smoothed growth curves. The spontaneous growth pattern of Chinese girls with TS runs parallel to published Caucasian TS growth curves. The mean final height of Chinese patients with TS was 142 cm compared to 147 cm and 139 cm observed in Northern European and Japanese patients, respectively. Patients with the 46, X, i(Xq) karyotype were found to be significantly shorter, whereas children with the 45, X/46, XY and 46, X, del(Xq) karyotypes were significantly taller among this group of patients. Patients with TS who were disomic for Xp are significantly taller than patients who were monosomic for Xp. Our results suggest that karyotype can have a significant effect on the growth of children with TS.

Adolescent↗
PubMed1997

Linear growth in early treated children with congenital hypothyroidism.

Length/height was studied from birth to 6 years of age in 103 children with congenital hypothyroidism identified by the Norwegian or Swedish screening programs. We used the "infancy-childhood-puberty (ICP) growth model". This model describes normal linear growth during the first 3 years of life by an infancy component with the addition of a childhood component, the latter acting from the second half of the first year. In comparison with reference children, children with hypothyroidism had reduced growth from 6 to 12 months, and increased growth after 12 months of age. Mean onset of the childhood component of growth was delayed from 8.1 months (SD 1.9) to 10.4 months (SD 2.2) in girls, and from 8.9 months (SD 2.0) to 11.0 months (SD 2.1) in boys. Age at onset of the childhood component was correlated with age at start of treatment (r = 0.24), and in children with more severe hypothyroidism (pretreatment serum thyroxine < 40 nmol/l) inversely correlated with the L-thyroxine dose at start of treatment (r = -0.40). Change in height standard deviation score from 1 to 3 years of age was correlated with the serum thyroxine concentration at age 1 year (r = 0.30). The delay in the onset of the childhood component of growth and the association with age at start of treatment and initial L-thyroxine dose indicate that thyroid hormones during the first months of life are essential for normal onset of the childhood component of growth, which otherwise is assumed to be growth hormone-dependent.

Age Factors↗
PubMed1997

Reference values for height, height velocity and weight in Turner's syndrome. Swedish Study Group for GH treatment.

As Northern Europeans are currently the tallest people in the world, specific growth charts for girls with Turner's Syndrome from this area are needed. Based on height and weight measurements from 598 girls with Turner's Syndrome (372 from the Netherlands, 108 from Denmark, 118 from Sweden) not treated with growth-promoting substances and without signs of spontaneous puberty, we constructed growth charts for height-for-age, height-velocity-for-age, weight-for-age, weight-for-height and Body Mass Index for age. Reference tables and regression equations for mean and standard deviation are provided allowing calculation of Standard Deviation Scores. The height and height velocity curves show a low birth length, gradual deviation from the normal percentile curves without pubertal growth spurt, and a prolonged growth until the early 20s. Mean adult height was 146.9 +/- 7.8 cm. Mean weight-for-age was lower than in normal reference children but height-adjusted weight was higher, except in infancy and early childhood. Further studies are required on the factors influencing the weight-height relationship in Turner's Syndrome.

Adolescent↗
PubMed1997

Postnatal growth of children born small for gestational age.

A large, population-based representative study (n = 3656) has shown that the vast majority of healthy, full-term, singleton infants born small for gestational age (SGA) achieve catch-up growth during the first 2 years of life. Indeed, most of the increase in height SDS occurs by 2 months of age. Children born SGA who do not show postnatal catch-up growth and so remain short at 2 years of age, have a higher risk of short stature (< -2 SDS) in later life, with a relative risk at 18 years of age of 5.2 if born light and of 7.1 if born short.

Adolescent↗
PubMed1996

Early age-dependent growth impairment in chronic renal failure. European Study Group for Nutritional Treatment of Chronic Renal Failure in Childhood.

We report early linear growth in 73 children (51 boys, 22 girls) with early onset of chronic renal failure (CRF). The inclusion criteria was onset of CRF before 6 months of age, two or more height measurements during the 1st year of life, follow-up for at least 3 years and continuously impaired renal function with a glomerular filtration rate below 50 ml/min per 1.73 m2 at 1 year or later. Only height measurements taken during conservative treatment or dialysis were included. The data were analysed in terms of the infancy-childhood-puberty growth model. There was an age-dependent growth failure in early life leading to an attained height of -3 standard deviation score (SDS) at 3 years of age. Approximately one-third of the reduction in height occurred during fetal life and one-third during the first postnatal months. Between 0.75 and 1.5 years of age height also decreased by 1 SD as a consequence of a delayed onset of the second, the 'childhood', phase of growth in 36% of the patients and by an 'offset childhood' growth pattern--i.e. a return to the infancy phase pattern after onset of the childhood phase--in 60% of the patients. Growth between 0.25-0.75 and 1.5-5 years of age was generally percentile parallel and thus less likely to be affected in CRF with early disease onset. The glomerular filtration rate was not related to the height gain in early life. We speculate that the growth failure during fetal life and the first postnatal months reflects metabolic and/or nutritional influences and the impaired growth at 0.75-1.5 years of age is related to a partial insensitivity to growth hormone.

Aging↗