Changes in mRNA gene expression during growth in the femoral head of the young rat.

The rate of physeal growth slows as an animal matures with changes in mRNA gene expression due to the altered cellular activity. To measure the change in gene expression during the juvenile growth period, the femoral head, enclosing the proximal femoral physis, primary spongiosa, and articular cartilage, was collected from both femora of 16 female Sprague-Dawley rats between 4 and 10 weeks of age. One femur of each rat had had a mid-diaphyseal femoral fracture at 4 weeks of age.

Altered expression of mitochondrial genes in response to fracture in old rats.

Background: Old rats require more time for bone to bridge a fracture gap than young rats. To explore possible mitochondrial dysfunction in this delay, we measured levels of mRNA derived from mitochondrial genes in healing fractures of young, adult, and old rats.

Methods: Diaphyseal femoral fractures were induced in female rats at 6, 26, and 52 weeks of age (young, adult, and old rats, respectively).

Genes with greater up-regulation in the fracture callus of older rats with delayed healing.

The rate of bone formation to bridge a fracture gap slows with age. To explore potential pathogenic mechanisms and possible negative-feedback responses by the skeleton to this reduced rate of healing, mRNA transcripts up-regulated more and/or longer were studied in older rats with delayed healing. Female rats at 6 (young), 26 (adult), and 52 (old) weeks of age received unilateral diaphyseal femoral fractures with intramedullary rod stabilization.

Evidence for overgrowth after midfemoral fracture via increased RNA for mitosis.

Middiaphyseal femoral fractures in children and young rats stimulate linear femoral growth, a phenomenon commonly attributed to increased vascularity. To test for changes in mRNA expression of genes related to blood vessels, nerve fibers, cartilage, bone, and cell metabolism, we measured mRNA gene expression for all known rat genes in the physis at various times after diaphyseal fracture. Female Sprague-Dawley rats, 4 weeks of age at surgery, were subjected to a unilateral, simple, transverse, middiaphyseal femoral fracture stabilized with an intramedullary rod.

Young, adult, and old rats have similar changes in mRNA expression of many skeletal genes after fracture despite delayed healing with age.

Genes active in fracture healing are not well understood. Because age slows skeletal repair, the change in gene expression between animals of differing ages may illuminate novel pathways important to this healing response. To explore this, 6-, 26-, and 52-week-old female Sprague-Dawley rats were subjected to mid-diaphyseal femoral fracture with intramedullary fixation.

Gene expression during fracture healing in rats comparing intramedullary fixation to plate fixation by DNA microarray.

Objective: This study was designed to compare mRNA gene expression in healing diaphyseal femoral fractures between those injuries treated with intramedullary nails and those treated with internal plate fixation.

Design: RNA gene expression was measured at 1 day, 3 days, and 1, 2, 4, and 6 weeks after surgery in the fracture callus of rats randomized to femoral shaft fracture with intramedullary nail fixation, rigid plate fixation, or sham fracture.

Setting: AAALAC-accredited vivarium of an independent academic medical center.

Altered mRNA expression of genes related to nerve cell activity in the fracture callus of older rats: A randomized, controlled, microarray study.

Background: The time required for radiographic union following femoral fracture increases with age in both humans and rats for unknown reasons. Since abnormalities in fracture innervation will slow skeletal healing, we explored whether abnormal mRNA expression of genes related to nerve cell activity in the older rats was associated with the slowing of skeletal repair.

Methods: Simple, transverse, mid-shaft, femoral fractures with intramedullary rod fixation were induced in anaesthetized female Sprague-Dawley rats at 6, 26, and 52 weeks of age.

Comparison of mRNA gene expression by RT-PCR and DNA microarray.

Few studies have compared the quantification of mRNA by DNA microarray to the results obtained by reverse transcription PCR (RT-PCR). In this study, mRNA was collected from the healing femoral fracture callus of adult and juvenile rats at various times after fracture. Ten samples were measured by both methods for 26 genes.

The genomic response of the mouse kidney to low-phosphate diet is altered in X-linked hypophosphatemia.

The mechanism for the renal adaptation to low-phosphate diets is not well understood. Whether the Hyp mutation of the Phex gene blocks this adaptation is also not clear. To gain further insight into this, 5-wk-old normal and Hyp mice were fed a control (1.

Evaluation of a cleanser for petroleum-contaminated skin.

Background: Extremity injuries contaminated with petroleum products pose clinical dilemmas. This project was designed to evaluate the efficacy of a dioctyl sulfosuccinate (DS) solution for cleansing petroleum-contaminated skin.

Methods: One hundred Sprague-Dawley rats were subjected to a contamination protocol followed by a cleansing procedure.

The effect of age on gene expression in adult and juvenile rats following femoral fracture.

Objective: To compare mRNA gene expression during fracture healing in young and adult rats.

Design: Gene expression was measured at zero, 1, 2, 4, 6, 8 and 10 weeks after fracture (6 rats/age/time point) in rats at 6 and 26 weeks of age at surgery.

Setting: AAALAC-accredited vivarium of an independent academic medical center.

Gene expression in older rats with delayed union of femoral fractures.

Background: Fracture-healing slows with age. While six-week-old rats regain normal bone biomechanics at four weeks after a fracture, one-year-old rats require more than twenty-six weeks. The objective of this study was to examine the possible role of altered mRNA gene expression in this delayed union.

Na/P(i) cotransporter ( Npt2) gene disruption increases duodenal calcium absorption and expression of epithelial calcium channels 1 and 2.

Mice homozygous for the disrupted type-II Na/P(i) cotransporter gene ( Npt2(-/-)) exhibit hypophosphataemia, increased serum concentration of 1,25-dihydroxyvitamin D (1,25-(OH)(2)D) and calcium (Ca) and elevated urinary Ca excretion. To determine whether the hypercalcaemia and hypercalciuria are secondary to 1,25-(OH)(2)D-stimulated intestinal Ca absorption, we examined the effect of Npt2 gene disruption on serum Ca and urinary Ca excretion after an overnight fast, and on duodenal Ca absorption. We also compared the duodenal expression of the epithelial Ca channels, ECaC1 and ECaC2, and calbindinD(9K) mRNAs, relative to that of beta-actin mRNA, in Npt2(+/+) and Npt2(-/-) mice.