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Biomedical subjects

D Pennington

Publications and source records attributed to D Pennington.

12 recordsLinked to original sources
PubMed2003

Phobic anxiety in 11 nations. Part I: Dimensional constancy of the five-factor model.

The Fear Survey Schedule-III (FSS-III) was administered to a total of 5491 students in Australia, East Germany, Great Britain, Greece, Guatemala, Hungary, Italy, Japan, Spain, Sweden, and Venezuela, and submitted to the multiple group method of confirmatory analysis (MGM) in order to determine the cross-national dimensional constancy of the five-factor model of self-assessed fears originally established in Dutch, British, and Canadian samples. The model comprises fears of bodily injury-illness-death, agoraphobic fears, social fears, fears of sexual and aggressive scenes, and harmless animals fears. Close correspondence between the factors was demonstrated across national samples. In each country, the corresponding scales were internally consistent, were intercorrelated at magnitudes comparable to those yielded in the original samples, and yielded (in 93% of the total number of 55 comparisons) sex differences in line with the usual finding (higher scores for females). In each country, the relatively largest sex differences were obtained on harmless animals fears. The organization of self-assessed fears is sufficiently similar across nations to warrant the use of the same weight matrix (scoring key) for the FSS-III in the different countries and to make cross-national comparisons feasible. This opens the way to further studies that attempt to predict (on an a priori basis) cross-national variations in fear levels with dimensions of national cultures.

Adolescent↗
PubMed2002

Dysregulation of transforming growth factor beta signaling in scleroderma: overexpression of endoglin in cutaneous scleroderma fibroblasts.

OBJECTIVE: As an initial approach to understanding the basis of the systemic sclerosis (SSc; scleroderma) phenotype, we sought to identify genes in the transforming growth factor beta (TGF beta) signaling pathway that are up-regulated in lesional SSc fibroblasts relative to their normal counterparts. METHODS: We used gene chip, differential display, fluorescence-activated cell sorter, and overexpression analyses to assess the potential role of TGF beta signaling components in fibrosis. Fibroblasts were obtained by punch biopsy from patients with diffuse cutaneous SSc of 2-14 months' duration (mean 8 months) and from age- and sex-matched healthy control subjects. RESULTS: Unexpectedly, we found that fibroblasts from SSc patients showed elevated expression of the endothelial cell-enriched TGF beta receptor endoglin. Endoglin is a member of the nonsignaling high-affinity TGF beta receptor type III family. The expression of endoglin increased with progression of disease. Transfection of endoglin in fibroblasts suppressed the TGF beta-mediated induction of connective tissue growth factor promoter activity. CONCLUSION: SSc is characterized by overproduction of matrix; that is, genes that are targets of TGF beta signaling in normal fibroblasts. Our findings suggest that lesional SSc fibroblasts may overexpress endoglin as a negative feedback mechanism in an attempt to block further induction of profibrotic genes by TGF beta.

Antigens, CD↗
PubMed2001

Experimental measurements of deep directional columnar heating by laser-generated relativistic electrons at near-solid density.

In our experiments, we irradiated solid CH targets with a 400 J, 5 ps, 3 x 10(19) W/cm(2) laser, and we used x-ray imaging and spectroscopic diagnostics to monitor the keV x-ray emission from thin Al or Au tracer layers buried within the targets. The experiments were designed to quantify the spatial distribution of the thermal electron temperature and density as a function of buried layer depth; these data provide insights into the behavior of relativistic electron currents which flow within the solid target and are directly and indirectly responsible for the heating. We measured approximately 200-350 eV temperatures and near-solid densities at depths ranging from 5 to 100 microm beneath the target surface. Time-resolved x-ray spectra from Al tracers indicate that the tracers emit thermal x rays and cool slowly compared to the time scale of the laser pulse. Most intriguingly, we consistently observe annular x-ray images in all buried tracer-layer experiments, and these data show that the temperature distribution is columnar, with enhanced heating along the edges of the column. The ring diameters are much greater than the laser focal spot diameter and do not vary significantly with the depth of the tracer layer for depths greater than 30 microm. The local temperatures are 200-350 eV for all tracer depths. We discuss recent simulations of the evolution of electron currents deep within solid targets irradiated by ultra-high-intensity lasers, and we discuss how modeling and analytical results suggest that the annular patterns we observe may be related to locally strong growth of the Weibel instability. We also suggest avenues for future research in order to further illuminate the complex physics of relativistic electron transport and energy deposition inside ultra-high-intensity laser-irradiated solid targets.

Journal Article↗
PubMed2000

Autocrine overexpression of CTGF maintains fibrosis: RDA analysis of fibrosis genes in systemic sclerosis.

We have used representational difference analysis (RDA) to identify up-regulated genes in skin fibroblasts from fibrotic lesions obtained from patients with systemic sclerosis (scleroderma). RDA of cDNA libraries derived from fibroblasts from involved and uninvolved skin detected several differentially expressed genes. One such gene consistently up-regulated in scleroderma cells coded for human connective tissue growth factor (CTGF). Other studies described here show that the CTGF protein is readily detected in cultures of systemic sclerosis fibroblasts but was not detected in comparable normal cells. High levels of CTGF are also evident in biological fluids from patients with systemic sclerosis. TGFbeta stimulates CTGF production in both normal and systemic sclerosis fibroblasts with the latter found to be higher producers. Moreover, an analysis of constitutive and TGFbeta-induced CTGF gene activation showed altered and elevated transcriptional responses in systemic sclerosis cells compared with controls. CTGF stimulated a two- to threefold increase in proalpha1(I) collagen and fibronectin synthesis by both dermal and lung fibroblasts in culture and promoted significant matrix remodeling of fibroblast-populated three-dimensional collagen lattices. A direct relation between the overexpression of CTGF and elevated collagen synthesis was suggested by the observation that transfection of a CMV-CTGF cDNA construct and protein expression in fibroblasts increased the transcription of a Col 1alpha2 promoter-reporter construct to levels seen in systemic sclerosis fibroblasts. Using Col 1alpha2 promoter deletion constructs the CTGF responsive element was localized to the first 379 bp upstream of the transcriptional start site. These data indicate that there is an overexpression of CTGF in the systemic sclerosis cells, probably due to increased gene transcription, and suggest that the dysregulation of CTGF production is an important factor in fibroblast activation and the excessive deposition of collagen in systemic sclerosis.

3T3 Cells↗
PubMed2000

Use of the vascular closure staple clip applier for microvascular anastomosis in free-flap surgery.

We report our initial experience using the vascular closure staple clip applier (a nonpenetrating titanium clip applied in an interrupted, everting fashion) for microvascular anastomosis in free-flap surgery. In total, 153 anastomoses were performed in 87 free flaps (174 potential anastomoses) using the vascular closure stapler between October of 1997 and June of 1999. In 66 flaps, both the arterial and venous anastomosis were performed with the clip applier, whereas in 21 flaps only the venous anastomosis was performed using the clips. A total of 146 anastomoses were performed in an end-to-end fashion, and seven were performed end-to-side. Of the 87 flaps there were 53 TRAM flaps, seven bilateral TRAM, five latissimus dorsi, four gastrocnemius, three rectus abdominis, two radial forearm fibula, and four Rubens fat-pad flaps. Seventy flaps were used for breast reconstruction, seven flaps for lower limb reconstruction, four flaps for head and neck reconstruction, and six flaps for chest wall/trunk reconstruction. There were no postoperative anastomotic complications of bleeding, thrombosis, or need for revision (100 percent patency rate), with a significantly reduced time for completion of anastomoses. The clip applier is a safe, reliable method for performing microvascular anastomoses, allowing reduced operating time and possible cost savings in free-flap surgery.

Anastomosis, Surgical↗
PubMed1999

Osseointegration of preformed polymethylmethacrylate craniofacial prostheses coated with bone marrow-impregnated poly (DL-lactic-co-glycolic acid) foam.

Osseointegration of bone marrow-PLGA-coated, preformed polymethylmethacrylate cranioplasties offers the possibility of reducing: operative time, periimplant seroma and infection, metallic fixation, and periprosthetic resorption following surgical skull remodeling. These alloplastic materials are FDA-approved but previously have not been used together to promote cranioplasty incorporation. The objective of this study was to determine whether the use of PLGA foam coating improves host osseointegration of preformed, textured, polymethylmethacrylate prosthetic cranioplasties. A critical-sized cranial defect was created in two groups of 10 and one group of three rabbits. The defect was filled with either a textured, preformed polymethylmethacrylate disc or a textured, preformed polymethylmethacrylate disc coated with poly (DL-lactic-co-glycolic acid). Both implants were immersed in autologous bone marrow for 20 minutes before implantation. Half of each group of 10 were killed at 3 weeks, and the remainder at 6 weeks. A third group of three rabbits with excised periosteum was evaluated at 6 weeks. Histologic analysis of the discs determined relative amounts of cancellous bone formation adjacent to the prostheses. Woven trabecular bone was present at each host bone to implant perimeter interface at 3 weeks, with fine fibrous capsular formation around the implants. Thicker, lamellar trabeculae were present at 6 weeks with an increased fibrous layer surrounding both types of implants. Bone formed on the superficial and deep implant surfaces in a noncontiguous fashion. Two of five measures showed that total bone formation was significantly greater in the PLGA-coated implants. Polymethylmethacrylate discs coated with bone marrow-impregnated PLGA foam demonstrate increased bone formation at 3 and 6 weeks as compared with non-coated preformed polymethylmethacrylate discs. Only implants with preserved periosteum showed bone formation away from the host-implant interface (centrally) on the superficial surface at 6 weeks.

Animals↗
PubMed1997

Competency-based learning in traumatology.

BACKGROUND: A multidisciplinary, competency-based trauma teaching program was introduced for final year medical students (n = 67) at Royal Prince Alfred Hospital (RPAH) in 1994 to complement the surgical clerkship. METHODS: The method involved small groups rotating through a series of teaching stations each structured to address a predetermined competency. Four 3-hour sessions were held on the subject areas of resuscitation, plastic, orthopedic, and neurotrauma. Performance in the trauma section of a summative Objective Structured Clinical Examination (OSCE), 6 months after the teaching, was compared with that of a control group (n = 127) from other campuses where trauma was taught by a series of discipline-based lectures. Three trauma OSCE stations were designed to test psychomotor skills while five addressed aspects of the cognitive domain. Checklists were used to ensure standardization of scoring in a range of questions asked for skills tested at each station. RESULTS: The marks of the RPAH students (mean 78% +/- SD 9%) were significantly higher (P < 0.0005) than the controls (mean 70% +/- SD 9%) in the 8 trauma questions. There was no significant difference (P = 0.8) in marks obtained by the study group (mean 61% +/- SD 8%) and controls (mean 63% +/- SD 7%) in 22 questions sampling a wide spectrum of nontrauma subject areas. The study group performed significantly better in one of the three skills stations and three of the five problem-solving stations when compared with the control group. CONCLUSION: The innovation has the potential to fulfill a need for an integrated trauma program in the undergraduate core curriculum.

Australia↗
PubMed1996

Sensory recovery following free TRAM flap breast reconstruction.

The free TRAM flap is now commonly used in breast reconstruction after mastectomy. A number of our patients reported anecdotally return of some sensation in their reconstructed breasts, despite being told beforehand that this was unlikely. This study measured return of sensation in a series of 21 patients, by studying both patients' subjective reporting of sensory return using a standardised questionnaire and objective evaluation of sensation with standard clinical tests. These included temperature and pain threshold and the use of the Semmes-Weinstein method. The study demonstrates that measurable sensory recovery occurred in 16 of our 21 patients (76%). 18 of the 21 patients (86%) reported a subjective feeling of sensation in the reconstructed breast and 7 (33%) claimed it felt the same as their normal contralateral breast. Sensory recovery usually commences about 6 months postoperatively and progressively improves over time. These findings demonstrate that the free tissue transfer method does not necessarily lead to an insensate reconstruction, as might be supposed.

Adult↗
PubMed1995

Subjective assessment of allergy relief following group hypnosis and self-hypnosis: a preliminary study.

Self-hypnosis was taught to 34 self-identified allergy patients who attended two training classes. They practiced on their own and were questioned two months later. Seventy-six percent of the subjects reported they felt an improvement in their symptoms; 86% of those who were medicated decreased their medicines. Practice was clearly related to reported improvement. "Feeling hypnotized" was not related to improvement.

Adolescent↗
PubMed1975

Acute post-traumatic coarctation of the abdominal aorta.

An unusual case of coarctation of the abdominal aorta following trauma in reported. The resultant supratenal aortic constriction was associated with severe hypertension and elevated plasma renin concentration. Gradual aortic dilation at the suture site was accompanied by remission of hypertension and return of plasma renin concentration to normal. Correlation of laboratory and hemodynamic changes resulting from this unusual case of abdominal coarctation is discussed.

Adult↗