Lead Exposure Inhibits Fracture Healing and Is Associated with Increased Chondrogenesis, Delay in Cartilage Mineralization, and a Decrease in Osteoprogenitor Frequency

Lead exposure continues to be a significant public health problem. In addition to acute toxicity, Pb has an extremely long half-life in bone. Individuals with past exposure develop increased blood Pb levels during periods of high bone turnover or resorption. Pb is known to affect osteoblasts, osteoclasts, and chondrocytes and has been associated with osteoporosis. However, its effects on skeletal repair have not been studied. We exposed C57/B6 mice to various concentrations of Pb acetate in their drinking water to achieve environmentally relevant blood Pb levels, measured by atomic absorption. After exposure for 6 weeks, each mouse underwent closed tibia fracture. Radiographs were followed and histologic analysis was performed at 7, 14, and 21 days. In mice exposed to low Pb concentrations, fracture healing was characterized by a delay in bridging cartilage formation, decreased collagen type II and type X expression at 7 days, a 5-fold increase in cartilage formation at day 14 associated with delayed maturation and calcification, and a persistence of cartilage at day 21. Fibrous nonunions at 21 days were prevalent in mice receiving very high Pb exposures. Pb significantly inhibited ex vivo bone nodule formation but had no effect on osteoclasts isolated from Pb-exposed animals. No significant effects on osteoclast number or activity were observed. We conclude that Pb delays fracture healing at environmentally relevant doses and induces fibrous nonunions at higher doses by inhibiting the progression of endochondral ossification

Remodeling of cortical bone allografts mediated by adherent rAAV-RANKL and VEGF gene therapy

Structural allograft healing is limited because of a lack of vascularization and remodeling. To study this we developed a mouse model that recapitulates the clinical aspects of live autograft and processed allograft healing. Gene expression analyses showed that there is a substantial decrease in the genes encoding RANKL and VEGF during allograft healing. Loss-of-function studies showed that both factors are required for autograft healing. To determine whether addition of these signals could stimulate allograft vascularization and remodeling, we developed a new approach in which rAAV can be freeze-dried onto the cortical surface without losing infectivity. We show that combination rAAV-RANKL- and rAAV-VEGF-coated allografts show marked remodeling and vascularization, which leads to a new bone collar around the graft. In conclusion, we find that RANKL and VEGF are necessary and sufficient for efficient autograft remodeling and can be transferred using rAAV to revitalize structural allografts

Helsesøster sine utfordringer i skolehelsetjenesten. En kvalitativ studie av hvilke utfordringer helsesøster møter i arbeidet med barn og unges psykososiale vansker

Bakgrunn: Formålet med studien er å undersøke helsesøster sine utfordringer i møte med barn og unges psykososiale vansker. Hensikten er å bidra med kunnskap og forståelse vedrørende forebyggende arbeid til barn og unge og hvilke forhold som gjør seg gjeldende innafor et sammensatt og komplekst fagområde. Problemstilling: Hvilke utfordringer møter helsesøster i arbeidet med barn og unges psykososiale vansker? Teori: Tidligere forskning rundt psykososial tematikk hos barn og unge, hvor forebygging og psykisk helse er sentrale begreper. Systemteori som innbefatter Bronfenbrenner sin bioøkologiske utviklingsmodell for helhetlig forståelse og tilnærming. Metode: Kvalitativ metode med en hermeneutisk fenomenologisk tilnærming med bruk av. Studiens utvalg er bestående av fire helsesøstre hvor alle er tilknyttet helsøstertjenesten og med flere års erfaring i skolehelsetjenesten. Helsesøstrene ble intervjuet ved bruk av en semistrukturert intervjuguide. Datamaterialet ble systematisk analysert ved anvendelse av Malteruds modifikasjon av Giorgis fenomenologiske analyse. Resultater: Resultatene viser til utfordringer for helsesøster på ulike nivåer. Disse omhandler sammensatte vansker hos barnet hvor vanskene kan bidra til utfordringer knytta til å etablere en trygg relasjon mellom barn og helsesøster. Mangel på ressurser begrenser helsesøster sine muligheter for individuell oppfølging. Videre er samarbeid med skolen en utfordring på grunn av ulik problemforståelse av barna. Helsesøster er i behov av formalisert samarbeid med spesialisthelsetjenesten. Det er videre behov for økt kunnskap hos barn og unge, på skolen og i helsesøsters fagfelt. Konklusjon: Forebygging av psykososiale vansker hos barn og unge er en utfordring med de ressurser helsesøster har tilgjengelig i skolehelsetjenesten. Nøkkelord: Helsesøster, barn og unge, psykososiale vansker, psykisk helse, forebygging, skolehelsetjeneste

Lead Exposure Inhibits Fracture Healing and Is Associated with Increased Chondrogenesis, Delay in Cartilage Mineralization, and a Decrease in Osteoprogenitor Frequency-1

<p><b>Copyright information:</b></p><p>Taken from "Lead Exposure Inhibits Fracture Healing and Is Associated with Increased Chondrogenesis, Delay in Cartilage Mineralization, and a Decrease in Osteoprogenitor Frequency"</p><p>Environmental Health Perspectives 2005;113(6):749-755.</p><p>Published online 14 Mar 2005</p><p>PMCID:PMC1257601.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.</p

Lead Exposure Inhibits Fracture Healing and Is Associated with Increased Chondrogenesis, Delay in Cartilage Mineralization, and a Decrease in Osteoprogenitor Frequency-7

<p><b>Copyright information:</b></p><p>Taken from "Lead Exposure Inhibits Fracture Healing and Is Associated with Increased Chondrogenesis, Delay in Cartilage Mineralization, and a Decrease in Osteoprogenitor Frequency"</p><p>Environmental Health Perspectives 2005;113(6):749-755.</p><p>Published online 14 Mar 2005</p><p>PMCID:PMC1257601.</p><p>This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.</p