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Biomedical subjects

S Buckley

Publications and source records attributed to S Buckley.

At least 19 recordsLinked to original sources
PubMed2001

Do lung remodeling, repair, and regeneration recapitulate respiratory ontogeny?

Herein we posit that modeling of the lungs during morphogenesis, repair, and regeneration is tightly coordinated by conserved stimulatory and inhibitory signaling mechanisms, including specific transcriptional factors, cytokines, peptide growth factors, proteases, and matrix elements. This evolutionary-developmental (evo-devo) functional conservation has been extended to morphogenesis of the respiratory tracheae in Drosophila. Fifty or more genes direct fruit fly tracheal organogenesis. Among them, hedgehog, patched, smoothened, cubitus interruptus, branchless, breathless, sprouty, decapentaplegic, and mad are functionally conserved between flies, mice, and humans. For example, fibroblast growth factor (FGF) signaling is essential, not only for fly trachea and mouse bronchial branching morphogenesis, but also for postnatal modeling and repair of alveoli. Likewise, sprouty family genes act as inducible negative regulators of FGF signaling, which in part may determine interbranch length during bronchial development. Alveolar epithelial survival, migration, and proliferation during remodeling after hyperoxic injury also require FGF signaling. In addition, FGF signaling appears to regulate a small (< 5%) population of putative alveolar stem/ progenitor cells that express telomerase and are relatively resistant to hyperoxic apoptosis. We speculate that genes in evo-devo functionally conserved signaling pathways such as FGF-FGF receptor-Sprouty may provide novel therapeutic targets to augment lung repair and induce lung regeneration.

Adult↗
PubMed2001

Nongenomic estrogen action in human lung myofibroblasts.

Recent studies have suggested that the antiproliferative effects of E2 may be mediated through a nongenomic action. Herein, we asked whether nongenomic estrogen action regulates phosphorylation of Raf1 and ERK1/2 mitogen-activated protein (MAP) kinase in lung myofibroblasts. We demonstrated that lung myofibroblasts, incubated in the presence of E2, showed a rapid phosphorylation on serine-259 of Raf1 and tyrosine-204 of ERK1/2 MAP kinase at 15 min, by approximately 3- and 5-fold, respectively. This phosphorylation was followed by dephosphorylation between 30 and 60 min. Western blot analysis showed that E2 regulates tyrosine phosphorylation of four main cytoplasmic proteins in lung myofibroblasts, of 42, 44, 70 and 100 kDa. Furthermore, our results indicated that E2 inhibits cell proliferation (BrdU index) in lung myofibroblasts by approximately 30% (P < 0.01). These data provide evidence that nongenomic action of E2, regulates both serine and tyrosine phosphorylation of cytoplasmic proteins in lung myofibroblasts, including Raf1 and ERK1/2 MAP kinase, which may regulate proliferation in lung myofibroblasts.

Binding Sites↗
PubMed2001

Migration and gelatinases in cultured fetal, adult, and hyperoxic alveolar epithelial cells.

Alveolar epithelial cell (AEC) migration mediated by matrix metalloproteinases (MMPs) is required for lung development and repair after injury such as hyperoxia. Of specific interest in lung remodeling are the gelatinases, which are upregulated in AEC after hyperoxia. We correlated migration and gelatinase production in AEC cultured from fetal, adult, and hyperoxic rats. Fetal AEC (19-20 days) had higher MMP-2 and MMP-9 gelatinase expression than adult AEC, with fivefold higher MMP-9 activity, and were migratory through gelatin, responding to epidermal growth factor, keratinocyte growth factor, and fibroblast growth factor-10. MMP-2 and MMP-9 expression and migratory activity could be detected from the time of plating. In contrast, adult AEC migrated and expressed MMP-2 and MMP-9 proteins only after 48 h of culture. AEC from hyperoxic rats were significantly more migratory through gelatin than control adult AEC, with significantly higher MMP-9 activity. Inhibition of MMPs with doxycycline reduced the migration of AEC from hyperoxic rats to the level of control adult AEC. Fibronectin-cultured "hyperoxic" AEC acquired a temporary capacity for migration similar to the A549 lung cancer cell line, which is both highly migratory and invasive and is derived from the AEC type 2 lineage. These data suggest that MMP activity is associated with a migratory phenotype in fetal, hyperoxic, and transformed AEC in vitro, and we speculate that MMPs may play a key mechanistic role in AEC migration in vivo during lung development and repair.

Aging↗
PubMed2001

Counting and cardinal understanding in children with Down syndrome and typically developing children.

This study compares the procedural counting ability (independently and with parental support) and conceptual understanding of cardinality of a group of children with Down syndrome and a group of typically developing children, matched for non-verbal mental age. Participants were 23 children with Down syndrome (chronological age range: 3.5-7 years; mental age range: 2.5-4 years) and 20 typically developing children (chronological age range: 2-4 years; mental age range: 2.5-4 years), and their main caregiver. The children were asked to count sets of toys (assessing procedural counting skills) and to give sets of toys (assessing understanding of cardinality), with set sizes between 2 and 18 items. The counting task was performed in two conditions, with and without parental support. The children were also asked to say the count word sequence aloud, to assess sequence production independent from object counting. The typically developing children produced significantly more number words altogether, longer standard number sequences and could count larger sets than the children with Down syndrome. Support from an adult improved performance on the count task significantly for both groups of children, and there was no significant difference between the groups in the degree of improvement, i.e. the zone of proximal development. No significant differences were found between the frequency of children (approximately one third) in each group who used counting to solve the give task, indicating an understanding of cardinality.

Child↗
PubMed2000

Comparison of four echocardiographic techniques for measuring left ventricular ejection fraction.

Accurate quantitative measurement of left ventricular (LV) ejection fraction (EF) by 2-dimensional echocardiography is limited by subjective visual endocardial border detection. Both harmonic and precision contrast microbubbles provide better delineation of endocardial borders than fundamental imaging. The aim of this study was to correlate 2-dimensional echocardiographic quantification of LVEF measured by 4 currently available techniques with radionuclide angiography. A total of 50 patients who underwent radionuclide (EF) measurement (47 of 50 had technically difficult echocardiograms by fundamental imaging) underwent echocardiography by 4 methods: fundamental alone, fundamental with contrast, harmonic alone, and harmonic with contrast. Three echocardiologists measured the biplane 2-dimensional echocardiographic LVEF independently and were blinded to radionuclide angiography. The correlation of echocardiographic EF with radionuclide EF improved incrementally with each method. However, contrast with harmonic imaging provided the closest correlation (r = 0.95, 0.96, and 0.95 as assessed by the 3 independent analysts.

Adult↗
PubMed2000

Conversion of cephapirin to deacetylcephapirin in milk and tissues of treated animals.

Cephapirin is one of six beta-lactam antibiotics approved for use in the treatment of food-producing animals in the United States. When used for treatment of mastitis by intramammary infusion, it is partially converted to a microbiologically active metabolite identified as deacetylcephapirin (DACEP). The degradation was followed in four cows with naturally acquired mastitis which were treated with cephapirin. DACEP persisted longer than the parent compound in the milk. When a calf was treated with cephapirin by intramuscular injection, the compound was almost completely converted to DACEP in tissues. The deacetyl form must be considered in the determination of residues in treated animals.

Animals↗
PubMed2000

Telomerase in alveolar epithelial development and repair.

Telomerase expression and activity were examined in the developing lung and in the adult lung during repair after injury. Both whole lung tissue and primary cultures of type 2 alveolar epithelial cells (AEC2) isolated from fetal and adult rodents were analyzed for 1) telomerase expression by immunohistochemistry and 2) telomerase activity with a telomerase repeat amplification protocol. We found that telomerase was expressed in a temporally regulated manner in fetal lung through the late stages of gestation, with peak expression just before birth. Expression persisted for a brief period in neonates, then decreased to nearly undetectable levels by postnatal day 9. Telomerase expression and activity were reinduced in normally quiescent adult lung by in vivo treatment with hyperoxia. In populations of AEC2 isolated from both developing and repairing lungs, telomerase expression and activity showed a strong correlation with the proliferation marker proliferating cell nuclear antigen. It has been suggested that telomerase expression and activity are hallmarks of stem or progenitor cells. Our observations suggest that a telomerase-positive subpopulation is present within the general AEC2 population. Telomerase may act as a marker for the proliferative status of this subpopulation.

Age Factors↗
PubMed2000

Bioactive transforming growth factor-beta in the lungs of extremely low birthweight neonates predicts the need for home oxygen supplementation.

Transforming growth factor-beta (TGF-beta) is a peptide implicated in tissue injury and repair but its role in the premature human lung remains unclear. In the present study, we used a TGF-beta responsive-promoter-luciferase construct in mink lung epithelial cells to quantify levels of biologically active TGF-beta (BA-TGF-beta) in the endotracheal aspirate (ETA) fluid from 16 extremely low birthweight neonates [6 M/10 F, mean GA 26 weeks (range 23-30), mean BW 774 g (range 555-1,075)]. ETA fluid was obtained on day 1 and then every 4 days up to 32 days. BA-TGF-beta levels were low (92 +/- 19 pg/ml) in the first 24 h of life and then increased 5- to 10-fold with peak BA-TGF-beta levels (400 +/- 50 pg/ml) on day 20-25. BA-TGF-beta levels were higher in male than female infants (p = 0.0056). Prenatal steroids decreased significantly the amount of BA-TGF-beta recovered. High initial levels of BA-TGF-beta persisted over time and were predictive of the need for oxygen therapy at home. We conclude that abundant BA- TGF-beta is present in the lungs of preterm infants and speculate that it may be involved in inflammatory and repair processes encountered in acute and chronic lung disease.

Bronchoalveolar Lavage Fluid↗
PubMed2000

Cytokine response during hyperoxia: sequential production of pulmonary tumor necrosis factor and interleukin-6 in neonatal rats.

BACKGROUND: Exposure of newborn animals to high concentrations of oxygen leads to diffuse alveolar damage similar to that seen in bronchopulmonary dysplasia in human infants. Therefore, neonatal rats are a suitable practical model of hyperoxic lung damage in human infants. OBJECTIVE: To determine the involvement of tumor necrosis factor-alpha and interleukin-6 in lung injury in neonatal rats exposed to 100% O2 concentration. METHODS: A randomized controlled study was designed in which litters of term Sprague-Dawley rat pups were assigned to experimental or control groups. The pups in the experimental group were placed in 100% O2 from birth for 9 days, while the control pups were placed in room air. Twelve to 15 pups from each group were sacrificed on day 1, 3, 6, 9 and 13 after birth for bronchoalveolar lavage collection and lung histologic study. The bronchoalveolar lavage fluid was assayed for TNF alpha and IL-6. RESULTS: Newborn rats exposed to 100% O2 for the first 9 days of life showed severe pulmonary edema and hypercellularity on days 1 and 3, which then improved to nearly complete resolution on days 6 and 9. Pulmonary TNF alpha was produced early on O2 exposure (day 3) and pulmonary IL-6 later (days 6 and 9). CONCLUSIONS: Hyperoxia induces sequential production of pulmonary TNF alpha and IL-6, which corresponds to the severity of the pathological findings and the known inflammatory and anti-inflammatory role of these cytokines.

Animals↗
PubMed1999

Prophylactic administration of immune lymphokine derived from T cells of Salmonella enteritidis-immune pigs. Protection against Salmonella choleraesuis organ invasion and cecal colonization in weaned pigs.

Experiments involving 132 weaned piglets were conducted to evaluate the efficacy of a Salmonella enteritidis-immune lymphokine (PILK) derived from the T cells of Salmonella enteritidis (SE)-immunized pigs to protect weaned piglets from Salmonella choleraesuis (SC) infection. Fourteen-to-seventeen day-old piglets were weaned and randomly placed into 1 of 5 groups: (1) noninfected controls, (2) PILK 3X noninfected, (3) SC infected controls, (4) PILK 1X SC infected, and (5) PILK 3X SC infected. PILK was given orally either one time (PILK 1X) or three times (PILK 3X) over 14 days. One hour after the first PILK administration on day 0, piglets were orally challenged with 10(7) cfu of SC. Weights were recorded on day 0, day 7, and day 14. On day 14, pigs in groups 3, 4, and 5 were sacrificed and organs and lymph tissue were cultured for the presence of SC. Three replicates of this experiment were pooled and anlayzed. A significant reduction in the number of pigs positive for SC in the liver, lung, and spleen was found in group 5 (PILK 3X) when compared to group 3 (inf. cont. p < 0.001[). The number of SC positive cecal contents was dramatically reduced in group 5 group when compared to group 3, with the PILK 3X group showing 13% positive pigs versus 55.2% in the infected controls (p < 0.05). Weight gain over the 14 day study in the infected PILK 3X group (group 5) was found to be comparable to the gain observed in the group 1 (noninfected controls). The pigs receiving PILK 3X (group 2) with no SC challenge gained significantly more weight than all other groups, including the noninfected controls (group 1 p < 0.05[). The results of these experiments indicate that PILK protects against SC infection in weaned pigs while enhancing performance in the presence of an SC infection.

Animals↗
PubMed1999

Prospective determination of distal colon findings in average-risk patients with proximal colon cancer.

BACKGROUND: Recent guidelines indicate that colonoscopy and sigmoidoscopy are both acceptable options for screening average-risk patients for colorectal cancer. Retrospective studies have found that a majority of patients with cancer proximal to the splenic flexure have a normal screening flexible sigmoidoscopy. METHODS: This was a multicenter, prospective description of colonoscopic findings and family history in consecutive patients with proximal colon cancer. RESULTS: Among 116 prospectively identified average-risk patients with cancer proximal to the splenic flexure, 40 (34.5%) had neoplasia distal to the splenic flexure. The prevalence of patients with adenomas greater than or equal to 1 cm, with only one tubular adenoma less than 1 cm, and with only hyperplastic polyps were 16.4%, 8.6%, and 6.9%, respectively. CONCLUSIONS: Most average-risk patients with cancer proximal to the splenic flexure will have a normal screening flexible sigmoidoscopy. These patients have an unexpectedly high prevalence of large distal adenomas, but the prevalence of both single small tubular adenomas and hyperplastic polyps alone is similar to that expected during screening of the general population. Clinicians and payers should continue to seek methods to improve the cost-effectiveness and availability of screening colonoscopy in average-risk persons.

Adenocarcinoma↗
PubMed1999

Trauma on rural roads: the role of a peripheral hospital.

Road accident trauma is a leading cause of death and serious morbidity among healthy young adults in the developed world. The Irish Republic has the third worst road safety record in the EU. In studying the unique demographics of rural road accidents, our aim was to provide information essential to the future development of trauma care in Ireland. Our figures highlight the inadequacies of data received by the National Roads Authority, illustrate the resource impact of road trauma on a peripheral hospital, and demonstrate the need for similar studies in the rationalisation of trauma care as we approach the next millennium.

Accidents, Traffic↗
PubMed1999

Spatial-specific TGF-beta1 adenoviral expression determines morphogenetic phenotypes in embryonic mouse lung.

The precise spatial-temporal role that expression and activation of transforming growth factor (TGF)-beta plays in mammalian organ morphogenesis remains incompletely understood. Using replication deficient adenoviral vectors containing engineered TGF-beta1 cDNAs, we studied the spatial effects of locally over-expressing either latent or mutated, constitutively active TGF-beta1 protein during embryonic mouse lung branching morphogenesis in culture. Transfer of exogenous genes into lung epithelium was achieved by intra-tracheal micro-injection of recombinant adenovirus, while submerging lungs in virus resulted in gene transfer into the pleura and subjacent mesenchymal cells, as revealed by cytochemical staining for beta-galactosidase. Only lungs transfected with active, but not latent TGF-beta1 gene, showed elevated levels of active TGF-beta. Epithelial over-expression of active, but not latent TGF-beta1, via intra-tracheal micro-injection inhibited lung branching morphogenesis by 36 %. In contrast, lungs submerged with either active or latent TGF-beta1 recombinant virus did not demonstrate an inhibitory effect upon branching. Pulmonary gene regulation was assayed by competitive polymerase chain reaction coupled with reverse transcription. Direct respiratory tract micro-injection of adenovirus over-expressing active TGF-beta1 resulted in a dose-dependent inhibition of epithelial surfactant protein (SP)-C and SP-B mRNA levels by up to 76 % and 70 %, respectively, while in contrast, fibronectin and matrix Gla protein (MGP) mRNA levels remained stable. However, lungs that had been submerged in adenovirus expressing active TGF-beta1 demonstrated a concentration-dependent induction of both fibronectin and MGP mRNA levels up to 4.3- and 4.7-fold respectively in the presence of 1 x 10(11) pfu/ml active TGF-beta1 virus. On the other hand, lungs treated with adenovirus expressing latent TGF-beta1 either by micro-injection or submerging failed to demonstrate any regulatory effect either upon epithelial or mesenchymal gene expression. We conclude that adenovector-mediated over-expression of activated TGF-beta1 in specific spatial compartments results respectively in either inhibition of branching morphogenesis and epithelium-specific gene expression, or in induction of matrix gene expression without affecting morphogenesis or epithelium-specific gene expression, depending on the route of administration. Also, the lack of effect of latent TGF-beta1 over-expression strongly suggests that TGF-beta activation per se provides an important locus of fine regulation of the spatial effects of TGF-beta signaling during embryonic lung branching morphogenesis.

Adenoviridae↗
PubMed1999

Muscle oxygenation trends during constant work rate cycle exercise in men and women.

PURPOSE: To examine the relationship between muscle oxygenation and arteriovenous oxygen difference [(a - v)O2diff)] at four constant rate workloads in healthy men and women and to compare these responses between the genders. METHODS: Nineteen men and 14 women consented to perform an incremental test to identify the lactic acidosis threshold (LAT) and maximal aerobic power (VO2max) and an intermittent constant work rate test at an oxygen uptake corresponding to 40% LAT, 80% LAT, 25% LAT-VO2max, and 50% LAT-VO2max. Each exercise interval was 5 min long followed by 2 min of recovery. Cardiac output was measured by CO2 rebreathing at each workload from which (a - v)O2diff was computed. Tissue absorbency was measured from the vastus lateralis in both the test sessions using near infrared spectroscopy (NIRS). Muscle oxygenation during constant work rate exercise and recovery was expressed as a percentage (%Mox) of the maximum range observed during incremental exercise and recovery. RESULTS: A systematic decrease was observed in %Mox with increasing intensity, followed by a proportional increase during recovery from each exercise bout. Significant inverse relationships were observed between %Mox and (a - v)O2diff in men (r = -0.34) and women (r = -0.31) across the four intensities. Mean %Mox was significantly higher (P < 0.05) in women compared with men, suggesting lesser deoxygenation at the same relative exercise intensity. CONCLUSIONS: %Mox was not an accurate predictor of mixed (a - v)O2diff during exercise because of the low common variance between these two variables, and it is unclear whether the gender difference in %Mox is a true physiological phenomenon or whether it is an artifact of the NIRS technique.

Acidosis, Lactic↗
PubMed1999

Abrogation of cyclin D1 expression predisposes lung cancer cells to serum deprivation-induced apoptosis.

Cyclin D1 antisense (D1AS)-transfected lung epithelial cell lines were serum deprived and then analyzed for three hallmarks of apoptosis: appearance of single-strand DNA breaks, alteration of apoptosis-related protein expression, and induction of chromatin condensation. Single-strand DNA breaks appeared at significant levels 24 h after serum deprivation, whereas induction of chromatin condensation was observed after 72 h. The antioxidants dimethyl sulfoxide, ascorbate, and glutathione, as well as insulin-like growth factor-I, inhibited induction of DNA damage in this assay. Additionally, proliferating cell nuclear antigen expression is completely suppressed in the D1AS cells, indicating a mechanism to explain the reduced capacity for DNA repair. Increased expression of cyclin D1, which is a common lesion in lung cancer, may thus prevent induction of apoptosis in an oxidizing and growth factor-poor environment. Reducing cyclin D1 expression in lung cancer cells by expression of D1AS RNA disrupted these protective pathways.

Antioxidants↗