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Biomedical subjects

B Wold

Publications and source records attributed to B Wold.

At least 19 recordsLinked to original sources
PubMed2001

[Psychological and somatic complaints among adolescents].

BACKGROUND: Health promotion and disease prevention among adolescents should include efforts to reduce the burden of health complaints. In order to develop systematic preventive approaches, epidemiological research is needed. This study focuses on prevalence, gender differences, and intercorrelations among such complaints. MATERIAL AND METHODS: The data were drawn from a nationwide (Norwegian) survey among pupils in compulsory school grades 6, 8, and 10 (age 11, 13, and 15); response rate 79%. RESULTS: Among 15-year-olds, most health complaints were more prevalent among girls than among boys. A principal components analysis revealed a dimension from primarily psychological to primarily somatic complaints. Among 15-year-olds, 18% reported at least one daily psychological complaint and 14% reported at least one daily somatic complaint. Sum-scores for psychological and somatic complaints were constructed, the intercorrelation being 0.56 among 15-year-olds. Girls scored significantly higher than boys on both sum-scores. Among girls there was a marked increase in scores with age (particularly for somatic complaints). INTERPRETATION: The high prevalence of complaints among both genders and the increase with age among girls implies that preventive action is needed. The intercorrelations among complaints indicate common etiological processes.

Adolescent↗
PubMed2001

Oxygen-mediated regulation of skeletal muscle satellite cell proliferation and adipogenesis in culture.

Major problems in stem cell biology revolve around defining the developmental potential of cell populations and understanding how their potential is maintained or progressively restricted. Oxygen (O(2)) is an obvious environmental factor which has received little attention in culturing skeletal muscle progenitor cells. In this work, we examine the effects of O(2) levels on the developmental potential, proliferative capacity, and phenotype of the adult skeletal muscle fiber progenitor population (satellite cells), and cell lines that model multipotential embryonic paraxial mesoderm from which skeletal muscle develops. Both satellite cell proliferation and survival of mature fibers increased in physiologic (6%) O(2) vs. non-physiologic 20% O(2) used in virtually all traditional cell culture. Six percent O(2) conditions also accelerated the up-regulation of multiple MyoD family myogenic regulatory factors (MRFs). An unexpected finding was that fiber-adherent satellite cells could assume a non-myogenic phenotype. By the criteria of molecular markers and gross lipid accumulation, satellite cells were found to assume an adipocyte phenotype, and did so more prominently in 20% O(2) than in physiologic O(2). Selection of the adipogenic fate and execution of adipogenesis by multipotential mesenchymal cell lines was also dramatically higher in traditional 20 vs. 6% O(2), and decreased adipogenesis in physiologic O(2) was associated with significantly less expression of the adipogenic regulator, PPAR gamma. These results suggest that regulatory pathways affected by O(2) are important for satellite cell proliferation, execution of cell fate, and parent muscle survival in culture, and so may play a role in vivo under normal or pathologic conditions.

Adipocytes↗
PubMed2001

Subjective health complaints in adolescence--reliability and validity of survey methods.

This paper studies test-retest reliability and validity of one measure of adolescent health complaints. The test-retest included an eight-item symptom checklist developed for the survey of Health Behaviour in School-aged Children (n=344). Qualitative analysis showed adequate validity for most items. For the total sample, all items were found to have adequate intraclass correlation coefficients (ICC) in the range 0.61-0.75. There were inter-item differences and girls generally received the higher values. Most changes were within one category. Adolescents' understanding of 16 complaints was studied by interviews with 38 adolescents. A few items showed ambiguity in interviews despite adequate test-retest stability.

Adolescent↗
PubMed2001

School-related stress, support, and subjective health complaints among early adolescents: a multilevel approach.

This study investigated the relationship between shared psychosocial school environment and subjective health complaints. A representative sample of 1585 Norwegian grade 8 students (mean age 13.5 years) from 82 schoolclasses completed scales on health complaints, academic stress, the teacher and classmate support scale, decision control, and noise and disturbance in class. Multilevel analysis (MlwiN) revealed that level of health complaints varied across schoolclasses (ICC=5.6%). School class differences in psychosocial environment accounted for 40% of the between-schoolclass variance in health complaints. Tests of cross-level interaction showed a statistically significant interaction between mean schoolclass-level of classmate support and individual level of academic stress. Findings suggest that shared schoolclass contextual factors may have main and stress-moderating effects on adolescent health complaints.

Adaptation, Psychological↗
PubMed2001

Sense of coherence and school-related stress as predictors of subjective health complaints in early adolescence: interactive, indirect or direct relationships?

The role of sense of coherence (SOC) on the relationship between adolescent school-related stress and subjective health complaints was tested with structural equation modelling. As part of the crossnational WHO-survey 'Health behaviour in school-aged children 1997/98' Norwegian representative samples of 1592 grade 6, 1534 grade 8, and 1605 grade 10 students completed measures on SOC, school-related stress and subjective health complaints. A test of nested structural models revealed that both stress-preventive (delta chi2 814. 86, p<0.001), stress-moderating (delta chi2 11.74, p<0.02) and main health-enhancing (delta chi2 1289.1, p < 0.001) effects of SOC were consistent with the data. A model including all these relationships fitted the data well (CFI = 0.91, RMSEA = 0.04). Age-group comparisons revealed that the association between SOC and stress grew weaker with age (p<0.05), whereas the direct association between SOC and health complaints grew stronger (p<0.001). The main effect of SOC accounted for between 39% (11 year olds) and 54% (15 year olds) of the variance in subjective health complaints. Findings indicate that SOC may potentially be a salutogenic factor in adolescents' adaptation to school-related stress, and that relationships between SOC and healthy adaptation, may be evident in younger age-groups than previously anticipated.

Adaptation, Psychological↗
PubMed2001

Subjective health complaints in adolescence. A cross-national comparison of prevalence and dimensionality.

BACKGROUND: The purpose of this work was to study the prevalence and dimensionality of subjective health complaints in a cross-national population of adolescents. METHODS: The analyses were based on data from a WHO cross-national survey, Health Behaviour in School-aged Children (HBSC). The study included a representative sample of 11, 13 and 15-year-old adolescents from Finland, Norway, Poland and Scotland. Data were collected in 1993-1994 and the total sample included 20,324 adolescents. Subjective health complaints were measured by the HBSC Symptom Checklist (HBSC-SCL), including headaches, abdominal pain, backache, feeling low, irritability, nervousness, sleeping difficulties and dizziness. Descriptive analyses, MANOVA and structural equation modelling (EQS) were conducted. RESULTS: Patterns of reporting were consistent for all four countries. A large number of students reported a high level of symptoms. The reporting of most symptoms increased with age. Girls reported significantly more symptoms than boys and the gender differences also increased with age. Structural equation modelling suggests a model of two correlated factors, which can be labelled psychological and somatic. CONCLUSION: The findings of this study indicate that students report a high level of subjective health complaints already at the age of 11 years. The reporting of most symptoms increases with age and more so for girls than for boys. The finding of two dimensions that differ qualitatively, suggests that these dimensions may have different etiologies.

Adolescent↗
PubMed2000

The bHLH regulator pMesogenin1 is required for maturation and segmentation of paraxial mesoderm.

Paraxial mesoderm in vertebrates gives rise to all trunk and limb skeletal muscles, the trunk skeleton, and portions of the trunk dermis and vasculature. We show here that germline deletion of mouse pMesogenin1, a bHLH class gene specifically expressed in developmentally immature unsegmented paraxial mesoderm, causes complete failure of somite formation and segmentation of the body trunk and tail. At the molecular level, the phenotype features dramatic loss of expression within the presomitic mesoderm of Notch/Delta pathway components and oscillating somitic clock genes that are thought to control segmentation and somitogenesis. Subsequent patterning and specification steps for paraxial mesoderm also fail, leading to a complete absence of all trunk paraxial mesoderm derivatives, which include skeletal muscle, vertebrae, and ribs. We infer that pMesogenin1 is an essential upstream regulator of trunk paraxial mesoderm development and segmentation.

Abnormalities, Multiple↗
PubMed2000

Culture in reduced levels of oxygen promotes clonogenic sympathoadrenal differentiation by isolated neural crest stem cells.

Isolated neural crest stem cells (NCSCs) differentiate to autonomic neurons in response to bone morphogenetic protein 2 (BMP2) in clonal cultures, but these neurons do not express sympathoadrenal (SA) lineage markers. Whether this reflects a developmental restriction in NCSCs or simply inappropriate culture conditions was not clear. We tested the growth and differentiation potential of NCSCs at approximately 5% O(2), which more closely approximates physiological oxygen levels. Eighty-three percent of p75(+)P(0-) cells isolated from embryonic day 14.5 sciatic nerve behaved as stem cells under these conditions, suggesting that this is a nearly pure population. Furthermore, addition of BMP2 plus forskolin in decreased oxygen cultures elicited differentiation of thousands of cells expressing tyrosine hydroxylase, dopamine-beta-hydroxylase, and the SA lineage marker SA-1 in nearly all colonies. Such cells also synthesized and released dopamine and norepinephrine. These data demonstrate that isolated mammalian NCSCs uniformly possess SA lineage capacity and further suggest that oxygen levels can influence cell fate. Parallel results indicating that reduced oxygen levels can also promote the survival, proliferation, and catecholaminergic differentiation of CNS stem cells (Studer et al., 2000) suggests that neural stem cells may exhibit a conserved response to reduced oxygen levels.

Animals↗
PubMed2000

Enhanced proliferation, survival, and dopaminergic differentiation of CNS precursors in lowered oxygen.

Standard cell culture systems impose environmental oxygen (O(2)) levels of 20%, whereas actual tissue O(2) levels in both developing and adult brain are an order of magnitude lower. To address whether proliferation and differentiation of CNS precursors in vitro are influenced by the O(2) environment, we analyzed embryonic day 12 rat mesencephalic precursor cells in traditional cultures with 20% O(2) and in lowered O(2) (3 +/- 2%). Proliferation was promoted and apoptosis was reduced when cells were grown in lowered O(2), yielding greater numbers of precursors. The differentiation of precursor cells into neurons with specific neurotransmitter phenotypes was also significantly altered. The percentage of neurons of dopaminergic phenotype increased to 56% in lowered O(2) compared with 18% in 20% O(2). Together, the increases in total cell number and percentage of dopaminergic neurons resulted in a ninefold net increase in dopamine neuron yield. Differential gene expression analysis revealed more abundant messages for FGF8, engrailed-1, and erythropoietin in lowered O(2). Erythropoietin supplementation of 20% O(2) cultures partially mimicked increased dopaminergic differentiation characteristic of CNS precursors cultured in lowered O(2). These data demonstrate increased proliferation, reduced cell death, and enhanced dopamine neuron generation in lowered O(2), making this method an important advance in the ex vivo generation of specific neurons for brain repair.

Animals↗
PubMed2000

The bHLH class protein pMesogenin1 can specify paraxial mesoderm phenotypes.

A new bHLH gene from mouse that we call pMesogenin1 (referring to paraxial mesoderm-specific expression and regulatory capacities) and its candidate ortholog from Xenopus were isolated and studied comparatively. In both organisms the gene is specifically expressed in unsegmented paraxial mesoderm and its immediate progenitors. A striking feature of pMesogenin1 expression is that it terminates abruptly in presumptive somites (somitomeres). Somitomeres rostral to the pMesogenin1 domain strongly upregulate expression of pMesogenin's closest known paralogs, MesP1 and MesP2 (Thylacine1/2 in Xenopus). Subsequently, the most rostral somitomere becomes a new somite and expression of MesP1/2 is sharply downregulated before this transition. Thus, expression patterns of these bHLH genes, together with that of an additional bHLH gene in the mouse, Paraxis, collectively define discrete but highly dynamic prepatterned subdomains of the paraxial mesoderm. In functional assays, we show that pMesogenin1 from either mouse or frog can efficiently drive nonmesodermal cells to assume a phenotype with molecular and cellular characteristics of early paraxial mesoderm. Among genes induced by added pMesogenin1 is Xwnt-8, a signaling factor that induces a similar repertoire of marker genes and a similar cellular phenotype. Additional target genes induced by pMesogenin1 are ESR4/5, regulators known to play a significant role in segmentation of paraxial mesoderm (W. C. Jen et al., 1999, Genes Dev. 13, 1486-1499). pMesogenin1 differs from other known mesoderm-inducing transcription factors because it does not also activate a dorsal (future axial) mesoderm phenotype, suggesting that pMesogenin1 is involved in specifying paraxial mesoderm. In the context of the intact frog embryo, ectopic pMesogenin1 also actively suppressed axial mesoderm markers and disrupted normal formation of notochord. In addition, we found evidence for cross-regulatory interactions between pMesogenin1 and T-box transcription factors, a family of genes normally expressed in a broader pattern and known to induce multiple types of mesoderm. Based on our results and results from prior studies of related bHLH genes, we propose that pMesogenin1 and its closest known relatives, MesP1/2 (in mouse) and Thylacine1/2 (in Xenopus), comprise a bHLH subfamily devoted to formation and segmentation of paraxial mesoderm.

Amino Acid Sequence↗
PubMed1997

Oral hygiene habits of 11-year-old schoolchildren in 22 European countries and Canada in 1993/1994.

This study is part of the Cross-National Survey on Health Behaviour in School-aged Children--a WHO Collaborative Study, which started in 1982. The aim of the study was to describe the oral hygiene habits (toothbrushing and flossing) of 11-year-old schoolchildren in 22 European countries (Austria, Belgium, the Czech Republic, Denmark, Estonia, FInland, France, Germany, Greenland, Hungary, Israel, Latvia, Lithuania, Northern Ireland, Norway, Poland, Russia, Scotland, the Slovak Republic, Spain, Sweden, and Wales) and Canada. The data were collected from standardized anonymous questionnaires in school classrooms during the 1993-1994 school year. At least 1300 school children, representing the whole country, participated in the study in each country. Oral hygiene habits were analyzed according to gender, age, country, school performance, and family economy. The children brushed most favorably in Sweden, Denmark, German, Austria, and Norway (83-73% brushed twice a day). More-than-once-a-day toothbrushing was especially uncommon (from 26 to 33%) among boys in Finland, Lithuania, Russia, Estonia, and Latvia. Toothbrushing frequency differed significantly according to school performance in Canada, the Czech Republic, Scotland, Poland, Northern Ireland, and Wales and between different socio-economic groups in Northern Ireland, Wales, the Czech Republic, Scotland, Poland, and Russia. Use of dental floss was rare. In general, flossing was less frequent among boys than among girls. Daily flossing was most common among Canadian adolescents (25%). In conclusion, there are considerable differences in toothbrushing frequency among children in European countries.

Achievement↗
PubMed1996

Skeletal muscle determination and differentiation: story of a core regulatory network and its context.

Regulation of skeletal muscle determination and differentiation in vertebrates centers on a core regulatory network which is composed of two families of transcription factors, the MyoD group basic helix-loop-helix (bHLH) muscle regulatory factors (MRFs) and the myocyte enhancer factor 2 (MEF2) group of MADS-box regulators. Members of this network interact with each other genetically and physically, and together they cooperate to positively regulate transcription of downstream muscle-specific differentiation genes. During development, the myogenic network can be activated or repressed in response to patterning signals, some of which have recently been identified. Once activated, the powerful myogenic activity of the core network can be modulated and held in check by a remarkably large group of negative regulators that operate on network components by diverse mechanisms. Recent discoveries highlight extensive parallels between myogenesis and peripheral neurogenesis in the structures of their respective regulatory networks and in the interaction of their bHLH networks with other regulatory circuits. Comparisons with Drosophila indicate that these ensembles of interacting molecular circuits have been highly conserved during evolution.

Animals↗
PubMed1996

The pregnant smoker's experience of ante-natal care--results from a qualitative study.

OBJECTIVES: 1) To obtain insight into pregnant smokers' experience of the information received from doctor and midwife at the ante-natal clinic. 2) To develop an understanding of pregnant women's own ideas of how health personnel can help them stop smoking. DESIGN: Qualitative study with strategic sampling. 33 pregnant smokers took part in an in-depth interview in the third trimester. SETTING: Home of patients, or surgeries in Hordaland county, Norway. PARTICIPANTS: Daily smokers during the last three months before conception, and still smoking in the 16th-18th week of pregnancy. RESULTS: Pregnant women lacking motivation to stop smoking seemed to be most satisfied with ante-natal care. The women interviewed saw doctors and midwives as responsible for raising the subject of smoking, and blamed them for disinterest. The findings suggest that pregnant smokers may be classified into four categories ("it could have been worse", "self-delusion", "self-confident", and "rational"), and that intervention should be tailored to meet each woman's perception of control over smoking behaviour.

Adult↗
PubMed1995

[What determines smoking habits in pregnancy? A qualitative study among pregnant smokers].

In this article we present results from a qualitative study among 33 pregnant smokers, who took part in an in-depth interview in the 27th-35th weeks of pregnancy. The aim was to obtain insight into pregnant women's own experience of smoking in pregnancy. The pregnant women interviewed were concerned about their smoking habits. In spite of this, they still expressed positive attitudes towards smoking, and many did not experience pregnancy as a favourable time to stop. The study shows that pregnant women still lack important knowledge about the dangers of smoking. Pregnant smokers' attitudes towards scientific facts, and the role cigarettes play in their everyday lives, are considered to be important variables in determining smoking in pregnancy. The pregnant women experienced that their partner and health-personnel played a minor role in changing smoking behaviour. The reasons the women gave for smoking in pregnancy are discussed in the light of current theories on changing health behaviour. Four key questions are proposed which can be used by doctor and midwife to obtain knowledge of pregnant women's perception of the seriousness of smoking and the associated risks, and of the gains and barriers connected with quitting.

Adult↗
PubMed1995

Comparative analysis of Homo sapiens and Mus musculus cyclin-dependent kinase (CDK) inhibitor genes p16 (MTS1) and p15 (MTS2).

Cyclin-dependent kinase inhibitors are a growing family of molecules that regulate important transitions in the cell cycle. At least one of these molecules, p16, has been implicated in human tumorigenesis while its close homolog, p15, is induced by cell contact and transforming growth factor-beta (TGF-beta). To investigate the evolutionary and functional features of p15 and p16, we have isolated mouse (Mus musculus) homologs of each gene. Comparative analysis of these sequences provides evidence that the genes have similar functions in mouse and human. In addition, the comparison suggests that a gene conversion event is part of the evolution of the human p15 and p16 genes.

Amino Acid Sequence↗
PubMed1995

Disruption of the mouse MRF4 gene identifies multiple waves of myogenesis in the myotome.

MRF4 (herculin/Myf-6) is one of the four member MyoD family of transcription factors identified by their ability to enforce skeletal muscle differentiation upon a wide variety of nonmuscle cell types. In this study the mouse germline MRF4 gene was disrupted by targeted recombination. Animals homozygous for the MRF4bh1 allele, a deletion of the functionally essential bHLH domain, displayed defective axial myogenesis and rib pattern formation, and they died at birth. Differences in somitogenesis between homozygous MRF4bh1 embryos and their wild-type littermates provided evidence for three distinct myogenic regulatory programs (My1-My3) in the somite, which correlate temporally and spatially with three waves of cellular recruitment to the expanding myotome. The first program (My1), marked initially by Myf-5 expression and followed by myogenin, began on schedule in the MRF4bh1/bh1 embryos at day 8 post coitum (E8). A second program (My2) was highly deficient in homozygous mutant MRF4 embryos, and normal expansion of the myotome failed. Moreover, expression of downstream muscle-specific genes, including FGF-6, which is a candidate regulator of inductive interactions, did not occur normally. The onset of MyoD expression around E10.5 in wild-type embryos marks a third myotomal program (My3), the execution of which was somewhat delayed in MRF4 mutant embryos but ultimately led to extensive myogenesis in the trunk. By E15 it appeared to have largely compensated for the defective My2 program in MRF4 mutants. Homozygous MRF4bh1 animals also showed improper rib pattern formation perhaps due to the absence of signals from cells expressing the My2 program. Finally, a later and relatively mild phenotype was detected in intercostal muscles of newborn animals.

Animals↗