The present research intended to examine the relationship between childhood stable peer status and adjustment in midadolescence for both genders, and adjustment in early and middle adulthood for women. One-year stably peer rejected, popular, and average boys and girls were identified by an age 10 and age 11 sociometric classification procedure using positive nominations and rank-ordering. These groups were examined in midadolescence. Findings indicated that stable peer rejection in childhood was associated with negative school adjustment and problems in peer relations in adolescence for both genders, and that many rejected boys were school dropouts. However, rejected children did not associate with deviant peers or show more antisocial behavior than their counterparts. For the adulthood follow-up, cluster analysis using LICUR was applied on rank-ordering data from age 10 and age 13 in order to identify 3-year stably rejected, popular, and average groups of girls. A methodological comparison with a standard sociometric method showed that the applied cluster analysis seems to be a useful additional tool in the arsenal of sociometric classification methods. Furthermore, one seems to arrive at larger stable peer status groups with this method than with other sociometric classification methods. The longitudinal follow-up into adulthood showed that rejected girls were at increased risk for criminal offending and alcohol abuse in young adulthood. Childhood aggressive behavior explained the significant association between peer rejection and criminality. There were no significant differences between the stable peer status clusters in the midadulthood adjustment areas of social relations, health, occupation, and subjective well-being, except that popular girls had achieved more successful vocational careers (which in its turn was explained by their higher academic achievement in childhood). Constraints and implications for future research were discussed.

This dissertation investigated the optimal strategy for the model specification search in the latent growth modeling. Although developing an initial model based on the theory from prior research is favored, sometimes researchers may need to specify the starting model in the absence of theory. In this simulation study, the effectiveness of the start models in searching for the true population model was examined. The four possible start models adopted in this study were: the simplest mean and covariance structure model, the simplest mean and the most complex covariance structure model, the most complex mean and the simplest covariance structure model, and the most complex mean and covariance structure model. Six model selection criteria were used to determine the recovery of the true model: Likelihood ratio test (LRT), DeltaCFI, DeltaRMSEA, DeltaSRMR, DeltaAIC, and DeltaBIC. The results showed that specifying the most complex covariance structure (UN) with the most complex mean structure recovered the true mean trajectory most successfully with the average hit rate above 90% using the DeltaCFI, DeltaBIC, DeltaAIC, and DeltaSRMR. In searching for the true covariance structure, LRT, DeltaCFI, DeltaAIC, and DeltaBIC performed successfully regardless of the searching method with different start models.

This thesis consists of four papers, and has as its central theme the accumulation of welfare problems and social exclusion. We use Swedish data and all analyses are based on individuals of working age. We perform longitudinal analyses to scrutinize the accumulation of disadvantages over the individual life courses as well as to detect the general trends in social exclusion occurrence in Swedish society during the past two decades. In Paper I, in an analysis of social exclusion among immigrants in Sweden, we find that immigrants suffer more often from social exclusion than native Swedes do. We also find that even if the accumulation of welfare problems is more common among immigrants than native Swedes, the connections between welfare disadvantages are stronger among Swedes. Furthermore, a logistic regression analysis revealed that time spent in Sweden decreases the risk of social exclusion among immigrants. However, even though we control for several demographic variables, human capital indicators and socio-economic class, the odds for social exclusion are still greater for immigrants than for native Swedes. Some form of discrimination can therefore not be excluded. Paper II is co-written with Björn Halleröd. This paper involves a longitudinal analysis of the accumulation of closely related welfare disadvantages, showing that the initial deprivation increases over time. Latent growth curve models reveal that a high initial deprivation is related to low socio-economic class and being single. It is also shown that a high initial deprivation decreases the probability of upward class-mobility as well as the probability of deprived singles becoming cohabiting. Moreover, a high initial deprivation increases the risk that couples will experience a household break-up. In Paper III, we perform a longitudinal analysis of social exclusion in Sweden during the period 1979-2003, in which several logistic regression models for panel data are fitted to our data. We find no support that immigrants have been better integrated into Swedish society over time from the perspective of social exclusion risk. Instead, there are weak signs that integration has become worse. We also find weak signs that the higher social exclusion risk that men have relative to women has decreased during the past two decades. Furthermore, comparing with couples without children, the odds for social exclusion among singles with children have increased and the odds for couples with children have decreased during the period 1979-2003. Paper IV utilizes latent class factor models to scrutinize the connections between welfare problems and a set of demographic variables, human capital indicators and socio-economic class. We find that welfare problems do cluster. Our results also support several of the findings in the previous paper. Family type, especially being single or living in a relationship, makes a clear difference in the propensity to accumulate welfare problems. Furthermore, immigrants characterize the factors with a high problem accumulation. Additionally, there is no general difference between the sexes in the problem accumulation itself, but experiences of threat or violence and having sleeping problems seem to be more often related to being a woman, whereas the lack of a close friend is most often related to being a man. To conclude, this thesis reveals several interesting facts concerning the accumulation of welfare problems and social exclusion in Sweden. Considering the implications for policy, the situations of immigrants and single parents need to be underlined. That is, the integration of immigrants should be given more emphasis and measures should be taken to support single parents as well as to promote a discussion on how to make relationships last.

Background Cataract surgery is the most common surgical procedure carried out in the developed world and surgery volumes have increased considerably during the last decades. Various aspects of the surgical procedure, including surgical incision size and intraocular lens materials, have changed substantially, improving the safety and the quality of the outcome. Previous research has primarily focused on the visual function results with a short follow-up time. Long-term population-based studies, exceeding a few years, presenting visual functional results postoperatively, have not been published. Aims To determine the effects of cataract surgery on subjectively experienced visual function and visual acuity in a defined population, and compare the results between sub-groups, on a long-term basis. Methods In this prospective, population-based investigation, all patients with presenile and senile cataract (n=810), operated on during a one-year period (1997-98), at Umeå University Hospital were included. The frequency of cataract surgery at that time, was 5.2 per 1000 population studied. Visual acuity was tested and an eye examination was performed before surgery, 4-8 weeks postoperatively, and five and ten years after surgery. Subjective visual function was assessed using self-administered questionnaires (VF-14) at all occasions. Statistical evaluations comprised analyses of variance, Mann-Whitney U-test, chi-square test, multiple linear regression, a life-table calculation, and Cox’s proportional hazard model. Results Five years after cataract surgery, subjective and objective visual function remained stable in most patients. The most frequent cause of deterioration of visual acuity and decrease in VF-14 scores was agerelated macular degeneration (ARMD). Two thirds of the patients in the cohort were women. They were significantly older than the men and more often operated on both eyes. After adjustment for age and visual acuity, women cataract surgery patients assessed their visual function worse than men both before surgery and 4 months postoperatively. Five years after surgery these differences were no longer significant. At baseline, 13% of the patients were diabetics. At the five-year followup, subjective and objective visual function remained stable in most surviving diabetics, and the longitudinal visual function was not significantly worse compared with the non-diabetics. Ten years after surgery, 28% had received treatment for posterior capsular opacification (PCO). A significantly larger proportion of patients less than 65 years at surgery (37%) compared with those 65 years or older (20%) had been treated. Conclusions Most patients sustain their level of visual acuity and visual function also five and ten years after cataract surgery. Ocular co-morbidity, such as ARMD, is the major cause of longitudinally reduced visual function. Patients suffering from diabetes did not have a significantly worse visual function after five years. A surprisingly large proportion of patients had received treatment for PCO after ten years.

Objective. The overall aim of this thesis was to evaluate the biopsychosocial consequences after stroke and test the validity of the ICF Core Sets for Stroke during one year post-stroke. Material and Methods. Studies I, II and III were based on data from a prospective cohort study with 120 stroke survivors who were recruited at admission to stroke units in western Sweden and were followed-up at six weeks, three months and one year after stroke event. Repeated assessments were done through face-to-face interviews consisting of a battery of questions based on the Stroke ICF Core Set (59 categories of Body Functions, 59 of Activities and Participation and 37 of Environmental Factors) and several questionnaires (EuroQol-5D (EQ-5D), Stroke Impact Scale (SIS), Medical Outcome Study Short Form 36 (SF-36), Self administered Comorbidity Questionnaire (SCQ), information on health care and social services utilization and spouse support). Study IV was based on data from the multi-center cross-sectional validation study of the Stroke ICF Core Set with 757 stroke survivors from China, Germany, Italy and Sweden. Results. Study I: A total of 28 of 59 ICF categories of Body Functions and a total of 41 of 59 categories of Activities and Participation were significant problems for stroke survivors at six weeks and three months. These categories showed a good discriminative ability to distinguish between independent (≤ 2 on modified Ranking Scale (mRS)) and dependent (> 2 on mRS) stroke survivors. Study II: Most stroke survivors felt satisfied with their stroke care and rehabilitation during three months post-stroke. Frequently perceived environmental facilitators could be documented with eleven of 37 ICF categories of Environmental Factors. Only physical geography, such as hills, was a common perceived barrier. Study III: Independent factors of health-related quality of life (HRQoL) varied over time. Almost all variance in HRQoL was explained by categories within Body Functions and within Activities and Participation during the first three months, while at one year only half of the variance could be explained by categories within either Body Functions or Environmental Factors. Problems with personal and energy functions, as well as limited recreational activities, were recurringly associated with poorer HRQoL. Study IV: It was possible to integrate ICF categories of Body Functions and Structures, Activities and Participation into a cross-cultural measurement with good reliability providing summary scores of the overall functioning of stroke survivors. However, the five-point ICF qualifier scale was not consistently applicable. Conclusions. The results of the present thesis showed that the ICF,particularly the ICF Core Set for Stroke, was a valid and practical tool for documenting the multi-faceted biopsychosocial problems and consequences after stroke structured with one common terminology throughout the long chain of care and rehabilitation. The opportunity to integrate ICF categories of Body Functions and Structures, Activities and Participation into a measurement provides new possibilities for monitoring, following-up and comparing overall functioning after stroke. / Syfte. Avhandlingen i sin helhet syftade till att fastställa de mångfaldiga biopsykosociala konsekvenserna under ett års tid efter stroke med hjälp av ICF och att testa validiteten av det nyetablerade Stroke ICF Core Set med avsikt att mäta funktionstillstånd efter stroke. Material och metod. I studie I, II och III ingår data från en ett års prospektiv kohortstudie med 120 personer med stroke som vårdades på strokeenheter i Västsverige och somföljdes upp efter sex veckor, tre månader och efter ett år. Datainsamlingen genomfördes med intervjuer som bestod av ett batteri av frågor grundat påStroke ICF Core Set, EuroQol-5D (EQ-5D), Stroke Impact Scale (SIS), Medical Outcome Study Short Form 36 (SF-36), Self-administered Comorbidity Questionnaire (SCQ), och information om insatser från hälso- och sjukvård, socialtjänst och familj. I studie I analyserades de 59 ICFkategorierna gällande Kroppsfunktioner och de 59 kategorier gällande Aktivitet och Delaktighet deskriptivt vid sex veckor och tre månader efter stroke. Därutöver prövades core sets förmåga att skilja mellan personer som var antingen beroende eller oberoende av hjälp efter stroke. Hur deltagarna uppfattade omgivningsfaktorernas betydelse analyserades deskriptivt utifrån de 37 ICF kategorierna från Omgivningsfaktorer i studie II vid sex veckoroch tre månader liksom skillnaderna mellan deltagarna som var hemma redan vid sex veckor och deltagarna som kom hem senare men inom tre månader. I studie III identifierades faktorerna av generell hälso-relaterad livskvalitet (EQ-5D visuell analog skala) med hänsyn till den biopsykosociala mångfaldigheten av hälsan och huruvida faktorerna ändrades under ett år efter stroke. Till detta användes korrelation- och regressionsanalys och de 155 ICF kategorier gällande Kroppsfunktioner, Aktivitet och Delaktighet samt Omgivningsfaktorer. Den pyskometriska analysen i studie IV baserades på datamaterial från WHO:s internationella multicentertvärsnittsstudie för validering av Stroke ICF Core Sets där 757 personer med stroke från Kina, Tyskland, Italien och Sverige ingår. Möjligheten att integrera 15 ICF kategorier från Brief ICF Core Set for Stroke (6 kroppsfunktioner, 2 strukturer, 7 aktiviteter och delaktighet) med dess 5-stegsbedömningsskala (från 0 till 4, inget, lätt, måttligt, stort och totalt problem) undersöktes både nationsspecifikt men också tvärkulturellt med Raschanalys. Resultat. Studie I. Signifikanta problem kunde dokumenteras med 28 ICF kategorierfrån komponenten Kroppsfunktion och med 41 ICF kategorier frånkomponenten Aktivitet och Delaktighet. Det fanns inga skillnader mellan 6veckor och 3 månader. Kategorierna hade en god förmåga att skilja mellan personer som var antingen oberoende eller beroende av hjälp efter stroke. Personer som var beroende av hjälp hade kontinuerlig mera problem inom området som gällde framförallt förflyttning, personlig vård och urinering men även kommunikation. Studie II. Deltagarna uppfattade elva omgivningsfaktorer som underlättande vid sex veckor och vid tre månader (framförallt familj, vänner och hälso- ochsjukvårdspersonal men också hjälpmedel, medicin och hälso- och sjukvårdsservice) och endast en faktor (fysisk geografi, dvs. backe, grusvägar, etc.) som hindrande. Vid tre månader uppfattades de sistnämnda faktorerna vanligare som hindrande än vid sex veckor. Vården på strokeenheten upplevdes något bättre jämfört med den senare tillkomna servicen från primär- och kommunvård. Studie III. Medan kroppsfunktioner och aktiviteter och delaktighet kunde förklara nästan all varians av självupplevd hälsa under de första tre månaderna (R2=0.80 - 0.93), så kunde bara hälften av variationen förklaras antingen med kroppsfunktioner eller med omgivningsfaktorer (R2=0.51). Problem med fritidsaktiviteter, personlighet, mental uttröttbarhet ochgångförmåga var återkommande problem som var relaterat till sämre självupplevd hälsa under året efter insjuknandet. Studie IV. Efter justeringar som innebar en minskning av bedömningsskalan till mellan två till tre svarsalternativ för vissa kategorier och en borttagning av några kategorier som inte passade in i Raschmodellen visade de resterande ICF kategorierna en bra täckning av personernas funktionstillstånd efter stroke och en god reliabilitet för att mäta funktionstillstånd. I den tvärkulturella analysen fanns det fyra kategorier sominte hade samma betydelse i de olika länderna. Därför utformades nationsspecifika kategorier. Det slutliga tvärkulturella instrumentet omfattar 20 ICF kategorier. Därmed blir det möjligt att integrera olika ICF kategorier till ett instrument och summera bedömningsvärden av de olika kategorierna till ett helhetsvärde för funktionstillstånd som underlättar uppföljning av och jämförelse mellan personer med stroke men även jämförelse mellan olika nationer. Slutsats. Studierna visar att ICF, och särskilt det specifika Stroke ICF Core Set, är ett valid och praktiskt verktyg för att strukturerat kunna dokumentera de mångfaldiga problemen och konsekvenserna efter stroke enhetlig genom hela förloppet av vårdkedjan. Strokesjukvården i Sverige upplevs som välfungerande men en god förbättringspotential finns framförallt i senare skede när primär- och kommunvård ta över ansvaret för personernas vård och rehabilitering. För dokumentation av funktionstillstånd av den typiska äldre patienten med stroke kan de 166 ICF kategorierna reduceras till 92. Faktorer som påverkar hälsorelaterad livskvalitet varierar under tiden efter insjuknandet där kroppsfunktioner och aktiviteter och delaktighet är starkt relaterade under de första tre månaderna. Vid ett år efter insjuknandet har omgivningens betydelse ökat för hälsorelaterad livskvalitet. Tidig hänsyn inte bara till gångförmåga men också till problem med personlighet och temperament, mental uttröttbarhet och återgång till fritidsaktiviteter borde kunna förbättra personernas livskvalitet efter stroke. Att konstruera ett tvärkulturellt instrument i syfte att mäta funktionstillstånd efter stroke genom integrering av ICF kategorier som omfattar kroppsfunktioner, strukturer, och aktiviteter och delaktighet är möjligt. Därmed öppnas nya potentialer för att kunna följa upp och jämföra funktionstillstånd efter stroke inte enbart på individ- och nationell nivå men även på populations- och internationell nivå. Den 5-stegs bedömningsskala (ICF qualifier) är dock inte psykometrisk användbart och fortsatt forskning behövs.

The major aim was to explore perceived daily occupations in mentally disordered offenders (MDO) through occupational performance (OP) and social participation (SP) with descriptive, comparative and longitudinal designs. The 74 consecutively included MDOs were visited onsite for data collection. The following assessments were used: Capability to Perform Daily Occupation, Self-efficacy Scale, Importance scale, Allen Cognitive Level Screen, Interview Schedule for Social Interaction, Manchester Short Assessment of Quality of Life, Psycho/social and Environmental Problems, Global Assessment of Functioning Scale, assessment of Support and Service for Persons with Certain Functional Impairments and Karolinska Scales of Personality. Background factors were assembled from the individual forensic psychiatric investigation. The results indicate that MDOs had contradictive problems in OP, SP and lack of disability awareness. The MDOs and professionals had different appraisals of the MDOs’ OP and SP. Schizophrenic MDOs need substantial support for community dwelling. MDOs with psychopathic personality traits had more problems during upbringing, however, no perceived problems in OP and SP compared to the remaining group. Low Socialization, high Anxiety and psychopathy personality traits partially influenced perceived OP and SP. After one year of forensic psychiatric care, 60 % were still hospitalized and 32 % were community dwelling. Changes after one year of care consisted of higher satisfaction of OP and SP, 1/36 subject valued daily occupations higher and 5/36 subjects reported better social interaction. Although, there are some methodological weaknesses in this thesis (e.g. high attrition rate), the unique results should be taken into consideration. It is concluded that MDOs’ appraisal of their own capability has to be taken seriously in treatment and care. Also long treatment periods, targeting daily occupations from start and providing substantial individual support are necessary for successful transition into community dwelling for MDOs. This thesis contributes to extended knowledge of the MDOs’ daily occupations.

Increasingly, computer and Internet usage play a vital role in connecting individuals to the larger society. Many factors may influence computer ownership and frequency of Internet usage by retired older adults. This thesis applies two theoretical frameworks, Cumulative Inequality theory and Intergenerational Solidarity theory, to explore major factors that may influence retired older adults' computer ownership and their frequency of Internet usage. Special attention will be paid to issues of social inequality: including retirement status (respondent and spouse), availability of an employer-paid pension (respondent and spouse), accumulated wealth, income, educational attainment, and employer-paid health insurance (respondent and spouse). In addition, this thesis will explore issues of intergenerational solidarity, specifically, number of children and number of children living in the household in relation to computer ownership and Internet usage, in particular. This study uses the Wisconsin Longitudinal Study (WLS) data that were collected through phone surveys that were conducted in 2004.

Background: There currently exists a vast amount of literature concerning chronic illness self-management, however the developmental patterns and sustainability of self-management over time remain largely unknown. This paper aims to describe the patterns by which different chronic illness self-management behaviors develop and are maintained over time. Method: Twenty-one individuals newly diagnosed with chronic illnesses (e.g., diabetes, rheumatism, ischemic heart disease, multiple sclerosis, chronic renal disease, inflammatory bowel disease) were repeatedly interviewed over two-and-a-half years. The interviews were conducted in Sweden from 2006 to 2008. A total of 81 narrative interviews were analyzed with an interpretive description approach. Results: The participants’ self-management behaviors could be described in four different developmental patterns: consistent, episodic, on demand, and transitional. The developmental patterns were related to specific self-management behaviors. Most participants took long-term medications in a consistent pattern, whereas exercise was often performed according to an episodic pattern. Participants managed health crises (e.g., angina, pain episodes) according to an on demand pattern and everyday changes due to illness (e.g., adaptation of work and household activities) according to a transitional pattern. All of the participants used more than one self-management pattern. Conclusion: The findings show that self-management does not develop as one uniform pattern. Instead different self-management behaviors are enacted in different patterns. Therefore, it is likely that self-management activities require support strategies tailored to each behavior’s developmental pattern. / Exploring individuals’ conceptions as a way to understand self-management among people living with long term medical conditions

Cadmium and lead accumulate in humans and can have toxic effects. Exposure to cadmium is well known to cause kidney damage. Cadmium binds to metallothioneins, proteins that play a role in cadmium transport. Lead exposure’s main effect is on the central nervous system, but associations with kidney disease have also been found, although it is unknown if the latter is a causal association. The main source of both metals within the non-smoking population is from the diet. This thesis aims to 1) compare the biomarkers lead and cadmium concentration in whole-blood, plasma and urine with regard to their ability to discriminate between individuals with different mean concentrations, and to describe the effect of urinary dilution, 2) estimate the association between end-stage renal disease and blood concentrations of cadmium, lead and mercury, using prospectively collected samples for exposure evaluation, 3) use longitudinal data on kidney function makers to evaluate kidney recovery after a substantial decrease in cadmium exposure, and 4) assess the influence of metallothionein polymorphisms (MT1A rs11076161, MT2A rs10636 and MT2A rs28366003) on cadmium-associated kidney toxicity and recovery due to a reduction in Cd exposure. Repeated sampling of whole-blood, plasma and urine was conducted on 48 occupationally lead-exposed men and 20 individuals under normal environmental lead exposure, for estimation of the day-to-day and between individual-variation. Prospective samples were obtained for 118 cases that later in life developed end-stage renal disease, and 378 matched controls. Erythrocyte cadmium, lead, and mercury concentrations were determined and the risk of developing end-stage renal disease associated with metal concentrations was estimated. For evaluation of kidney recovery after a reduction in cadmium exposure and to test for gene-environment interactions, follow-up data on N-acetyl-β‑d-glucosaminidase, β2‑microglobulin, albumin, and gene polymorphisms were obtained for 412 individuals within the Chinese population and the relation to blood and urinary cadmium was assessed. The concentration of lead in blood was found to be the biomarker with the largest fraction of the total variance attributable to between-individual variation, and was therefore the biomarker with the best ability to discriminate between individuals with different mean concentrations, both for individuals under occupational and normal environmental exposure (91 and 95%, respectively). Adjusting for urinary dilution had a great effect on the fraction of the total variance attributable to between-individual variation among individuals with normal lead exposure but only a minor effect among those who were occupationally exposed. Variance analysis showed that blood concentrations were also the best discriminating biomarker for cadmium. Erythrocyte lead was, in a univariate model, associated with an increased risk of developing end-stage renal disease [odds ratio (OR) = 1.54 for an interquartile range increase, with a 95% confidence interval (CI) = 1.18-2.00], while erythrocyte mercury was negatively associated (OR = 0.75 for an interquartile range increase, with a 95% CI = 0.56-0.99). For erythrocyte cadmium, the OR was 1.15 with a 95% CI of 0.99-1.34. Associations with lead and cadmium were only seen among men. In the study on kidney recovery, the proportion of individuals with albumin level above the 95th percentile decreased between baseline and follow up, but no decrease was found for the tubular markers N-acetyl-β‑d-glucosaminidase and β2-microglobulin. Metallothionein polymorphisms modified cadmium-associated effects on N-acetyl-β‑d-glucosaminidase and β2-microglobulin levels but did not modify cadmium-associated change in any of the kidney function markers between baseline and follow up after a substantial decrease in exposure. Blood concentrations of lead and cadmium are the biomarkers with the best ability to discriminate between individuals with different mean concentrations. Adjustment for urinary dilution has great influence on the fraction of the total variance attributed to between individual variation among urine samples with low lead concentrations, but only a small influence on samples with high lead concentrations. This suggests a difference in excretion. The association between end-stage renal disease and low-level lead exposure, as assessed through prospective erythrocyte samples, gives reason for concern, although further studies are needed to determine causality. A cadmium-associated increase in albumin is reversible after a substantial reduction in exposure, but this is not the case for the observed tubular effects. The tubular kidney effects of cadmium might be modified by the MT1A rs11076161 polymorphism. / För att bedöma exponering för kadmium och bly mäts ofta deras koncentrationer i blod eller urin. Dessa studerades i longitudinella data för 48 blyarbetare och 20 individer med normal miljömässig exponering. Blod- och urinprover togs var annan till var tredje månad. Kadmium- och blykoncentrationer mättes sedan i helblod, plasma och urin. Koncentrationer av bly i blod var den biomarkör som hade den största andelen av den totala variationen som kunde förklaras av skillnader mellan individer, och var därför den biomarkör med den bästa förmågan att särskilja på individer med olika medelkoncentration, både för individer med yrkesexponering och normal miljömässig exponering (91 respektive 95% av variansen berodde på vilken individ blodprovet kom ifrån). Justering för urinens utspädning av bly i urin förbättrar oftast urins användbarhet som biomarkör. För bly stämde detta bara hos dem som inte var blyarbetare. Blodkoncentrationer var också den biomarkör med störst andel av den totala variation som kunde förklaras med skillnader mellan individer för kadmium. Kadmium och bly ackumuleras i njure respektive ben och kan ha toxikologiska effekter. Det är välkänt att höga exponeringsnivåer av kadmium orsakar njurskada och även vid lägre exponeringsnivåer har studier funnit samband med markörer för njurfunktion. Exponering för bly påverkar i första hand det centrala nervsystemet. Studier har dock funnit samband mellan koncentrationer av bly i blod och njurens glomerulära filtrationshastighet. Det är oklart både om dessa associationer, vid låga exponeringsnivåer, är viktiga för hälsan och om de verkligen beror på att kadmium och bly orsakar njurskada. För att studera end-stage renal disease användes prospektiva kohorter där personer lämnat blodprov för forskning: Västerbottens interventionsprogram med prover som tagits vid Västerbottens hälsoundersökningar, MONICA-undersökningar i Norr- och Västerbotten, mammografiundersökningarna i Västerbotten och Malmö kost cancer. Sammanlagt ingick över ett hundra tusen individer i dessa kohorter. Med hjälp av det Svenska njurregistret identifierades sedan 118 personer som senare i livet fått end-stage renal disease. Dessa jämfördes med 378 kontroller. För dessa 496 personer tinades blodprovet (närmare bestämt röda blodkroppar) upp och analyserades för kadmium och bly. För att undersöka njurens förmåga till återhämtning studerades tre områden i Kina varav ett tidigare varit kraftigt kadmiumexponerat. Erytrocytkoncentrationer av bly var, utan att ta hänsyn till några andra variabler, associerat med en ökad risk för att utveckla end-stage renal disease (med oddskvoten 1.54 för en interquartile range ökning av erytrocytbly, med ett 95% konfidensintervall 1.18-2.00). Sambanden kvarstod också efter att ha tagit hänsyn till övriga variabler. För erytrocytkadmium var oddskvoten 1.15 med 95% konfidensintervall 0.99-1.34, och sambandet försvagades när hänsyn togs till andra variabler. Associationerna sågs bland män men inte bland kvinnor. Eftersom kadmium vid höga nivåer orsakar njurskada är det också av intresse att studera om påverkan på njuren går över om exponeringen minskas. Totalt följdes 412 individer upp med mätningar av markörer för njurfunktion och kadmiumkoncentrationer i blod och urin. Första undersökningen gjordes 1998, då man just hade slutat äta kadmiumförorenat ris. En andra undersökning gjordes 2006. Andelen individer med avvikande albuminvärde i urin var lägre vid uppföljningen jämfört med vid baslinjen, men ingen minskning sågs för markörer för tubulär förmåga att återta proteiner. Åttioprocent av kadmium i celler är bundet till proteinet metallotheonin, vilket skyddar mot cellskada, men har också en roll i transporten av kadmium från levern till njurarna. En tidigare studie har visat att njurens känslighet för kadmiumexponering var associerad med genetiska skillnader i detta protein. För att studera genetiska associationer studerades de 412 personerna i den kinesiska studien [då också individernas genotyper av metallotheonin-polymorfierna MT1A rs11076161 (G/A), MT2A rs10636 (G/C) och MT2A rs28366003 (A/G) bestämdes]. Genetiken spelade roll för sambandet mellan förmåga att återta proteiner och kadmium men påverkade inte förändring av njurfunktion efter att man slutat äta kadmiumförorenat ris. Kadmium- och blykoncentrationer i blod är de biomarkörer, av koncentrationer i blod, plasma och urin, med den bästa förmågan att skilja på individer med olika medelkoncentrationer. Justering för urinutspädning påverkade andelen av den totala variationen som kunde förklaras av skillnader mellan individer i stor utsträckning för individer med normal miljömässig exponering men inte bland yrkesexponerade, vilket tyder på en skillnad i hur utsöndringen går till. Associationen mellan end-stage renal disease och låg exponering för bly, uppmätta i prospektiva erytrocytprover, ger orsak till oro, men ytterligare studier behövs för att kunna utvärdera om detta är ett kausalt samband. En kadmiumrelaterad skada av den glomerulära filtrationen är reversibel efter en kraftig reducering i exponering, men detta är inte fallet för tubulär skada. De tubulära njureffekterna av kadmiumexponering kan påverkas av metallotheonin-polymorfier.

Not many children report relationships with friends that are both close and conflictual. There is a paucity of research examining the trajectory of children's relationship closeness and conflict together over time. This is unfortunate because contentious relationships are related to cardiovascular problems, at least in young adults and because the trajectories of these two aspects of children's relationship quality over time is not understood. Therefore, two longitudinal data sets with younger (mean age 7.5 years at Time 1; four data points over 2 years) and older (mean age 9.9 years at Time 1; two data points over 1 year) children were studied. In both cohorts, measures of friendship quality and peer nominations of liking/disliking as well as overt and relational (older cohort) aggression were completed. Children who reported relationships high in both closeness and conflict were generally satisfied with their friendships; they were not more likely to end their friendships than were children who reported different levels of closeness and conflict (younger cohort). Both boys' and girls' relationship closeness increased over time according to growth curve analyses. The relationships of girls who remained in the same friendship, and who therefore provided ratings on the same friend at each time point, tended to increase in closeness at a different rate over time than the relationships of girls who provided ratings on different friends (younger cohort). Children who reported relationships high in closeness and in conflict were not more aggressive over time than were children who reported different levels of relationship closeness and conflict. However, girls' closeness and overt aggression tracked each other (increased) over time (younger cohort). Girls who reported low social support and negative interactions in their friendships increased the most in overt aggression over time (older cohort). Aggressive and nonaggressive children generally reported similar friendship quality (both cohorts), but the friendship closeness of chronically aggressive boys decreased over time (younger cohort). There were negligible friendship quality differences amongst the sociometric groups. The discussion centers on friendship quality changes in children's continuing friendships, the potential dire effects of turbulent friendships and the friendships of aggressive as well as controversial children.