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Biomedical subjects

K L Gardner

Publications and source records attributed to K L Gardner.

15 recordsLinked to original sources
PubMed2006

Restoration of all dystrophin protein interactions by functional domains in trans does not rescue dystrophy.

Rescue of dystrophic skeletal muscle in mdx and utrophin/dystrophin-deficient (dko) mouse models by reintroduction of dystrophin has validated gene therapy as a potential therapeutic approach for Duchenne muscular dystrophy. However, the size of the dystrophin gene exceeds the capacity of adeno-associated viral (AAV) vectors. Dystrophin provides a mechanical link at the muscle membrane by direct binding of its amino-terminal and cysteine-rich domains to actin and a transmembrane protein complex, respectively. It has not been investigated whether restoration of these two tethering functions by two separate dystrophin molecules is sufficient to prevent dystrophic pathologies. We examine the effect of coexpression of the amino-terminal and cysteine-rich domains from separate dystrophin transgenes, Deltacys and Dp71, on the dystrophic phenotype. Expression of individual dystrophin domains from multiple vectors would effectively expand AAV capacity. Although both Deltacys and Dp71 colocalize at the membrane, there is no improvement of dystrophic pathology. The fiber-type and neuromuscular junction abnormalities of dko mice that are ameliorated by the Deltacys transgene are not further improved or disrupted by Dp71. Separate truncated dystrophins, which together restore all protein interactions and scaffolding for signaling molecules, are not sufficient to ameliorate the dystrophic phenotype and therefore dystrophin domains in trans cannot be used to increase the effective cloning capacity for AAV-mediated gene therapy.

Animals↗
PubMed2005

Early life experience alters behavior during social defeat: focus on serotonergic systems.

Early life experience can have prolonged effects on neuroendocrine, autonomic, and behavioral responses to stress. The objective of this study was to investigate the effects of early life experience on behavior during social defeat, as well as on associated functional cellular responses in serotonergic and non-serotonergic neurons within the dorsal raphe nucleus, a structure which plays an important role in modulation of stress-related physiology and behavior. Male Long Evans rat pups were exposed to either normal animal facility rearing or 15 min or 180 min of maternal separation from postnatal days 2-14. As adults, these rats were exposed to a social defeat protocol. Differences in behavior were seen among the early life treatment groups during social defeat; rats exposed to 180 min of maternal separation from postnatal days 2-14 displayed more passive-submissive behaviors and less proactive coping behaviors. Analysis of the distribution of tryptophan hydroxylase and c-Fos-like immunoreactivity in control rats exposed to a novel cage and rats exposed to social defeat revealed that, independent of the early life experience, rats exposed to social defeat showed an increase in the number of c-Fos-like immunoreactive nuclei in serotonergic neurons in the middle and caudal parts of the dorsal dorsal raphe nucleus and caudal part of the ventral dorsal raphe nucleus, regions known to contain serotonergic neurons projecting to central autonomic and emotional motor control systems. This is the first study to show that the dorsomedial part of the mid-rostrocaudal dorsal raphe nucleus is engaged by a naturalistic stressor and supports the hypothesis that early life experience alters behavioral coping strategies during social conflict; furthermore, this study is consistent with the hypothesis that topographically organized subpopulations of serotonergic neurons principally within the mid-rostrocaudal and caudal part of the dorsal dorsal raphe nucleus modulate stress-related physiological and behavioral responses.

Animals↗
PubMed2001

Transgenic mice with cardiac-specific expression of activating transcription factor 3, a stress-inducible gene, have conduction abnormalities and contractile dysfunction.

Activating transcription factor 3 (ATF3) is a member of the CREB/ATF family of transcription factors. Previously, we demonstrated that the expression of the ATF3 gene is induced by many stress signals. In this report, we demonstrate that expression of ATF3 is induced by cardiac ischemia coupled with reperfusion (ischemia-reperfusion) in both cultured cells and an animal model. Transgenic mice expressing ATF3 under the control of the alpha-myosin heavy chain promoter have atrial enlargement, and atrial and ventricular hypertrophy. Microscopic examination showed myocyte degeneration and fibrosis. Functionally, the transgenic heart has reduced contractility and aberrant conduction. Interestingly, expression of sorcin, a gene whose product inhibits the release of calcium from sarcoplasmic reticulum, is increased in these transgenic hearts. Taken together, our results indicate that expression of ATF3, a stress-inducible gene, in the heart leads to altered gene expression and impaired cardiac function.

Activating Transcription Factor 3↗
PubMed1999

Beta 1 integrin- and proteoglycan-mediated stimulation of T lymphoma cell adhesion and mitogen-activated protein kinase signaling by thrombospondin-1 and thrombospondin-1 peptides.

Cell-cell and cell-matrix interactions play important regulatory roles in lymphocyte homeostasis. Thrombospondin-1 (TSP1) is a matricellular protein that differentially promotes the adhesion of resting and activated T cells. In this work, we show that adhesion of Jurkat T cells on substrates coated with TSP1 or TSP1-derived peptides is mediated by beta 1 integrins, CD47, and heparan sulfate proteoglycans. Interactions with TSP1 or TSP1 peptides stimulated CD3-induced Ras activation and tyrosine phosphorylation of several T cell proteins. The signals from TSP1 and its derived peptides differentially synergized with activation of the TCR to induce phosphorylation of linker for activation of T cells (LAT) and extracellular signal-regulated kinase (ERK) 1/2, c-Jun N-terminal kinase, and p38 kinases. The phosphorylation of ERK in the presence of full-length TSP1 was transient and dependent on a beta 1 integrin receptor. Interestingly, peptides derived from the type 1 repeats of TSP1 and a CD47-binding peptide from the carboxyl-terminal domain of TSP1 also stimulated mitogen-activated protein (MAP) kinase phosphorylation. Moreover, the TSP1 heparin-binding peptide synergized with Ab-ligated TCR to transduce signals to the nucleus, detected by activation of AP-1- and Elk-dependent transcription. This TSP1 peptide-dependent activation of AP-1 was inhibited by both heparin and the MAP/ERK kinase inhibitor PD98059, providing a functional link between adhesion molecule interaction and nuclear transactivation events via the MAP kinase pathways. These findings have implications for the role of extracellular TSP1 and TSP1 fragments in the regulation of T cell function during hemostasis, wound repair, and other inflammatory responses.

Amino Acid Sequence↗
PubMed1998

Neuroblastoma screening in the United States: results of the Texas Outreach Program for neuroblastoma screening.

BACKGROUND: Mass screening of infants for neuroblastoma began in Japan after studies suggested that survival rates could be improved by early detection. This study was initiated in 1991 to test the methodology and feasibility of screening for neuroblastoma within the U. S. health care system. METHODS: Infants ages 5-10 months (mean age, 9 months, 25 days) who were born in Texas were screened for neuroblastoma. An enzyme-linked immunoadsorbent assay (ELISA) for homovanillic acid (HVA) and vanillylmandelic acid (VMA) used to quantify the HVA and VMA was performed on urine extracted from specimens dried on filter paper. Infants were recruited to participate in the study by several methods, and the effectiveness of each method was determined by calculating compliance rates. RESULTS: Between February 1991 and June 1994 a total of 14,046 infants were recruited to participate in neuroblastoma screening. Neuroblastoma was detected in 2 children for an incidence rate of 1 in 7023. A total of 291,158 screening kits were distributed to the parents of these infants, resulting in an overall compliance rate of only 4.8%. Compliance rates varied by method of distribution of the test kits: Houston Women, Infants, and Children (WIC) clinic (53%), volunteers (31%), Rio Grande Valley WIC clinics (14.5%), the patient's private physician (9.9%), and by mail (4.7%). CONCLUSIONS: Early detection of neuroblastoma in infants ages 5-10 months was achieved using ELISA. Compliance rates were poor, but clinics with a preventive health focus, such as the WIC clinics, achieved higher compliance rates than did private physicians.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Virilizing adrenal cortical neoplasm arising ectopically in the thorax.

We describe a 44-yr-old woman with a 12-yr history of clinical virilization and serum testosterone levels up to 28.1 nmol/L (normal range, 1-3.3 nmol/L) in whom repeated clinical evaluation and surgical procedures failed to reveal the source of androgen production. At the time the patient was referred to the Clinical Center of the NIH, an intrathoracic mass was seen on upper cuts of an abdominal computer-aided tomography scan, confirmed by computer-aided tomography scan and magnetic resonance imaging of the chest. A 6 x 5 x 3.5-cm mass, attached to the posterior pericardium, was removed by thoracotomy. Pathological examination revealed an adrenal cortical neoplasm of uncertain malignant potential that contained testosterone, 11-deoxycortisol, progesterone, and 17-hydroxyprogesterone. After the operation, the patient's serum testosterone levels decreased to the normal range. Ectopic adrenal cortical rests in the thorax and neoplasms arising from these rests are extremely rare, and we are not aware of a similar case previously reported. In women with virilization, radiological studies of the thorax as well as other reported sites of ectopic adrenal cortex should be performed if radiological studies of the abdomen and pelvis fail to locate the source of the neoplasm.

Adrenal Cortex Neoplasms↗