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Biomedical subjects

T Duncan

Publications and source records attributed to T Duncan.

At least 19 recordsLinked to original sources
PubMed2004

Laparoscopic palliative surgery for complicated colorectal cancer.

BACKGROUND: The aim of this study was to evaluate the feasibility and outcomes of the laparoscopic approach for the palliation of advanced complicated colorectal cancer (CRC). METHODS: We reviewed 21 laparoscopic palliative procedures for emergent complications of advanced CRC between 1994 and 2002. Intraoperative complications, estimated blood loss, transfusions, operative times, time to first bowel movement, length of hospital stay, and postoperative complications were assessed. RESULTS: Indications for surgery included perforation (n = 10), bleeding (n = 7), and obstruction (n = 4). A proximal diverting procedure was performed in all patients, and a concomitant colon resection was performed in 18 patients (86%). The mean operative time was 181 +/- 22 min. Estimated blood loss was 283 +/- 48 cc, with three patients (14%) requiring transfusions. The average length of hospital stay was 8.6 +/- 2 days, and time to first bowel movement was 61 +/- 9 h. The complication rate and the 30-day mortality rate were 33% and 0%, respectively. CONCLUSION: A laparoscopic approach to address advanced CRC is safe and effective and should be considered part of the surgeon's armamentarium for the palliation of advanced complicated CRC.

Colorectal Neoplasms↗
PubMed2003

Laparoscopic vs open resection for the treatment of diverticular disease.

INTRODUCTION: The aim of this study was to evaluate whether laparoscopic colon resection (LCR) offers any advantages over open colon resection (OCR) in the treatment of diverticular disease. METHODS: Between 1992 and 2002, 95 patients underwent LCR and 80 patients underwent OCR for the treatment of diverticular disease. Demographics, details of operative procedure, outcome, and pathology were compared. RESULTS: Patients in both groups were matched for age, sex, body mass index, history of previous abdominal operations, comorbidities, location of the disease, and presence of complications. LCR resulted in significantly less estimated blood loss and postoperative complications, shorter time to first bowel movement, and shorter length of stay than the OCR. There was no difference in operative time, intraoperative complications, mortality rates between groups. CONCLUSIONS: LCR is a safe and effective approach for the treatment of patients with diverticular disease. It results in less estimated blood loss, shorter time to first bowel movement, less postoperative complications, and shorter length of hospital stay.

Aged↗
PubMed2001

The role of multimedia interactive programs in training for laparoscopic procedures.

BACKGROUND: The application of minimally invasive techniques to the performance of abdominal surgery by general surgeons has been perhaps the greatest advance in the history of general surgery. The safe adoption of many of these procedures, however, has been hampered by significant obstacles, mainly due to the problem of providing adequate training for surgeons. Outside of animal and cadaver labs, most training has been didactic in nature, and adoption rates after completion of these courses are discouraging. Multimedia interactive training has been used in a number of high-tech industries with great success. A >60% improvement in the learning curve after multimedia interactive training, as compared to traditional didactic training, has been reported. Multimedia interactive training programs for surgeons that use content and input from multiple experts in laparoscopic procedures have now been developed. METHODS: Residents from a general surgery residency program who used these programs were asked to rate their effectiveness in increasing their knowledge and comfort level prior to their participation in a real procedure as the primary surgeon or first assistant. A comparison to other traditional training techniques was also made. Eleven residents completed 41 programs designed to teach one of five different laparoscopic procedures-cholecystectomy, fundoplication, appendectomy, colon resection, or hernia repair. RESULTS: On a scale of 1 to 10, with 10 being the highest, the residents reported that the multimedia interactive training programs raised their knowledge level of the procedure from 6.0 to 8.7 (+2.7 point value increase after using the multimedia interactive program). The programs increased their comfort level when actually called on to perform or assist with the procedure from 5.3 to 8.1 (+2.8 point value increase after using the multimedia interactive program). In comparing the value of training methods for learning laparoscopic procedures, the residents rated text, lectures, videos, and animal labs at 4.7, 5.1, 6.0 and 7.3, respectively. By comparison, the residents rated the multimedia interactive training program at 8.8. CONCLUSION: The use of multimedia interactive training programs in addition to current laparoscopic training courses may help to increase the safe adoption of laparoscopic procedures. These programs may be a beneficial adjunct to residency training programs.

Adult↗
PubMed2001

African Americans' views on research and the Tuskegee Syphilis Study.

The participation of African Americans in clinical and public health research is essential. However, for a multitude of reasons, participation is low in many research studies. This article reviews the literature that substantiates barriers to participation and the legacy of past abuses of human subjects through research. The article then reports the results of seven focus groups with 60 African Americans in Los Angeles, Chicago, Washington, DC, and Atlanta during the winter of 1997. In order to improve recruitment and retention in research, the focus group study examined knowledge of and attitudes toward medical research, knowledge of the Tuskegee Syphilis Study, and reactions to the Home Box Office production, Miss Evers' Boys, a fictionalized version of the Tuskegee Study, that premiered in February, 1997. The study found that accurate knowledge about research was limited; lack of understanding and trust of informed consent procedures was problematic; and distrust of researchers posed a substantial barrier to recruitment. Additionally, the study found that, in general, participants believed that research was important, but they clearly distinguished between types of research they would be willing to consider participating in and their motivations for doing so.

Black or African American↗
PubMed2001

New B-type cyclin synthesis is required between meiosis I and II during Xenopus oocyte maturation.

Progression through meiosis requires two waves of maturation promoting factor (MPF) activity corresponding to meiosis I and meiosis II. Frog oocytes contain a pool of inactive "pre-MPF" consisting of cyclin-dependent kinase 1 bound to B-type cyclins, of which we now find three previously unsuspected members, cyclins B3, B4 and B5. Protein synthesis is required to activate pre-MPF, and we show here that this does not require new B-type cyclin synthesis, probably because of a large maternal stockpile of cyclins B2 and B5. This stockpile is degraded after meiosis I and consequently, the activation of MPF for meiosis II requires new cyclin synthesis, principally of cyclins B1 and B4, whose translation is strongly activated after meiosis I. If this wave of new cyclin synthesis is ablated by antisense oligonucleotides, the oocytes degenerate and fail to form a second meiotic spindle. The effects on meiotic progression are even more severe when all new protein synthesis is blocked by cycloheximide added after meiosis I, but can be rescued by injection of indestructible B-type cyclins. B-type cyclins and MPF activity are required to maintain c-mos and MAP kinase activity during meiosis II, and to establish the metaphase arrest at the end of meiotic maturation. We discuss the interdependence of c-mos and MPF, and reveal an important role for translational control of cyclin synthesis between the two meiotic divisions.

Amino Acid Sequence↗
PubMed2000

Identification, expression, and substrate specificity of a mammalian beta-carotene 15,15'-dioxygenase.

We have identified from mouse the first mammalian beta-carotene 15,15'-dioxygenase (beta-CD), a crucial enzyme in development and metabolism that governs the de novo entry of vitamin A from plant-derived precursors. beta-CD is related to the retinal pigment epithelium-expressed protein RPE65 and belongs to a diverse family that includes the plant 9-cis-epoxycarotenoid dioxygenase and bacterial lignostilbene dioxygenases. beta-CD expression in Escherichia coli cells engineered to produce beta-carotene led to the accumulation of all-trans-retinal at the expense of beta-carotene, confirming that beta-CD catalyzed the central cleavage of this vitamin A precursor. Purified recombinant beta-CD protein cleaves beta-carotene in vitro with a V(max) of 36 pmol of retinal/mg of enzyme/min and a K(m) of 6 microm. Non-provitamin A carotenoids were also cleaved, although with much lower activity. By Northern analysis, a 2.4-kilobase (kb) message was observed in liver, kidney, small intestine, and testis, tissues important in retinoid/carotenoid metabolism. This message encoded a 63-kDa cytosolic protein expressed in these tissues. A shorter transcript of 1.8 kb was found in testis and skin. Developmentally, the 2.4-kb mRNA was abundant at embryonic day 7, with lower expression at embryonic days 11, 13, and 15, suggesting a critical role for this enzyme in gastrulation. Identification of beta-CD in an accessible model organism will create new opportunities to study vitamin A metabolism.

Amino Acid Sequence↗
PubMed2000

Molecular characterization and developmental expression of NORPEG, a novel gene induced by retinoic acid.

We have characterized NORPEG, a novel gene from human retinal pigment epithelial cells (ARPE-19), in which its expression is induced by all-trans-retinoic acid. Two transcripts ( approximately 3 and approximately 5 kilobases in size) have been detected for this gene, which is localized to chromosome band 5p13.2-13.3. Placenta and testis showed the highest level of expression among various human tissues tested. Six ankyrin repeats and a long coiled-coil domain are present in the predicted sequence of the NORPEG protein, which contains 980 amino acid residues. This approximately 110-kDa protein was transiently expressed in COS-7 cells as a FLAG fusion protein and immunolocalized to the cytoplasm. Confocal microscopic analysis of the NORPEG protein in ARPE-19 cells showed threadlike projections in the cytoplasm reminiscent of the cytoskeleton. Consistent with this localization, the expressed NORPEG protein showed resistance to solubilization by Triton X-100 and KCl. An ortholog of NORPEG characterized from mouse encoded a protein that showed 91% sequence similarity to the human NORPEG protein. The expression of Norpeg mRNA was detected in mouse embryo at embryonic day 9.5 by in situ hybridization, and the expression appears to be developmentally regulated. In adult mouse, the highest level of expression was detected in the seminiferous tubules of testis.

Amino Acid Sequence↗
PubMed2000

A randomised controlled trial of a community intervention to prevent adolescent tobacco use.

OBJECTIVE: Experimental evaluation of comprehensive community wide programme to prevent adolescent tobacco use. DESIGN: Eight pairs of small Oregon communities (population 1700 to 13 500) were randomly assigned to receive a school based prevention programme or the school based programme plus a community programme. Effects were assessed through five annual surveys (time 1-5) of seventh and ninth grade (ages 12-15 years) students. INTERVENTION: The community programme included: (a) media advocacy, (b) youth anti-tobacco activities, (c) family communications about tobacco use, and (d) reduction of youth access to tobacco. MAIN OUTCOME MEASURE: The prevalence of self reported smoking and smokeless tobacco use in the week before assessment. RESULTS: The community programme had significant effects on the prevalence of weekly cigarette use at times 2 and 5 and the effect approached significance at time 4. An effect on the slope of prevalence across time points was evident only when time 2 data points were eliminated from the analysis. The intervention affected the prevalence of smokeless tobacco among grade 9 boys at time 2. There were also significant effects on the slope of alcohol use among ninth graders and the quadratic slope of marijuana for all students. CONCLUSION: The results suggest that comprehensive community wide interventions can improve on the preventive effect of school based tobacco prevention programmes and that effective tobacco prevention may prevent other substance use.

Adolescent↗
PubMed2000

Plasma vascular endothelial growth factor in acute mountain sickness.

STUDY OBJECTIVES: To investigate the hypothesis that an increase in circulating vascular endothelial growth factor (VEGF) occurs in mountaineers at high altitude, particularly in association with acute mountain sickness (AMS) and/or low hemoglobin oxygen saturation. DESIGN: : Collection of medical histories, AMS scores, plasma samples, and arterial oxygen saturation (SaO(2)) measurements from mountaineers at 1,500 feet (sea level) and at 14,200 feet. SETTING: Mount McKinley ("Denali"), AK. PARTICIPANTS: Sixty-six mountaineers. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Plasma VEGF at 14,200 feet was not increased in any group. In fact, plasma VEGF was significantly lower in subjects who did not develop AMS (53 +/- 7.9 pg/mL; mean +/- SEM; n = 47) compared to control subjects at sea level (98.4 +/- 14.3 pg/mL; n = 7; p = 0.005). Plasma VEGF at 14, 200 feet for subjects with AMS (62 +/- 12 pg/mL; n = 15) did not differ significantly from subjects at 14,200 feet without AMS, or from control subjects at sea level. Of a small number of subjects with paired specimens at sea level and at base camp (n = 5), subjects who exhibited a decrease in plasma VEGF at 14,200 feet were those who did not develop AMS. Neither SaO(2), prior AMS, AMS symptom scores, or acetazolamide use were correlated with plasma VEGF. CONCLUSIONS: Subjects at high altitude who do not develop AMS have lower plasma VEGF levels compared to control subjects at sea level. Plasma VEGF at high altitude is not elevated in association with AMS or hypoxia. Sustained plasma VEGF at altitude may reflect a phenotype more susceptible to AMS.

Adult↗
PubMed2000

The use of water-soluble contrast in evaluating clinically equivocal small bowel obstruction.

This study seeks to determine whether a 6-hour abdominal radiograph after oral Gastrografin is a reliable indicator for nonoperative treatment in patients with a clinically equivocal small bowel obstruction. We collected retrospective data from medical records. Patients who received a Gastrografin transit time (GGTT) study between January 1995 and September 1998 were included in the study. Patients who did not appear to be obvious operative candidates, but had signs of intestinal obstruction, underwent a GGTT study. Serial plain abdominal radiographs were taken. If the contrast was in the colon within 6 hours, then the result was negative. A total of 418 GGTT studies were reviewed. Contrast reached the colon within 6 hours in 283 (68%) patients, and 247 (88%) of these patients were managed nonoperatively. The positive predictive value, negative predictive value, sensitivity, and specificity of Gastrografin reaching the colon within 6 hours were 48, 87, 64, and 78, respectively. False negatives included high-grade partial obstructions that ultimately required surgery. Recent operation preceded the GGTT in 128 (31%) cases. Of these 128 patients, only 17 (14%) received an operation. Although the decision to operate or not should never be based on a GGTT study alone, GGTT studies are of significant help in the clinical management of patients suspected to have a small bowel obstruction. GGTT allows for the judicious selection of the appropriate patient for nonoperative management. GGTT studies are cost effective, safe, and clinically useful when attempting to treat patients conservatively.

Contrast Media↗
PubMed2000

The bill drops here. Concurrent coding reduces billing delays, improves accuracy and saves time and money.

PROBLEM: Salinas Valley wanted to improve its reporting procedures to payors for reimbursement. Delays in reporting referred outpatients and inpatients can significantly impact receipt of reimbursements from payors. SOLUTION: Salinas Valley developed a program of concurrent coding in which every procedure is assigned a reimbursement code that is automatically registered in the patient's B/AR record when the procedure is logged into any of the clinical applications in the healthcare information system. RESULTS: Quicker turnaround on receiving payments from payors, as well as an increased return on investment as the ratio of reimbursement to cost-of-time-spent increases. KEYS TO SUCCESS: Integral to the success of the concurrent coding review program was the openness of the operating system at Salinas Valley.

Abstracting and Indexing↗
PubMed1999

Levels of retinoic acid and retinaldehyde dehydrogenase expression in eyes of the Mitf-vit mouse model of retinal degeneration.

PURPOSE: Several reports have characterized the retinal degeneration observed in the Mitf(vit) mutant mouse. Despite these reports, the factor(s) that may cause or modulate the degeneration still are not well defined; however, it is known that the photoreceptors of Mitf(vit) mice die through an apoptotic mechanism. We reported previously that retinoid metabolism in the RPE of Mitf(vit)++ mice is perturbed. Retinoids regulate genes via the RAR and RXR nuclear receptor pathway that are involved in numerous cellular responses including apoptosis. It is possible that retinoic acid (RA) modulates the retinal degeneration observed in the Mitf(vit) mice. The purpose of this study was to evaluate the levels of RA in whole eyes, as well as its distribution between neural retina and RPE, of the Mitf(vit) mutant mouse model. An additional purpose was to examine the expression of the RA generating enzyme, retinaldehyde dehydrogenase (AHD2), in the eyes of mutant and control mice. METHODS: The distribution of AHD2 in eyes of pre- and postnatal Mitf(vit) and C57BL/6 wild-type mice was determined immunohistochemically. Quantitative and qualitative analyses of RA were performed using reversed-phase high performance liquid chromatography (HPLC). RESULTS: The distribution of AHD2 in ocular tissues was similar between pre- and postnatal Mitf(vit) and C57BL/6 control mice. At postnatal week 10, however, a marked increase in AHD2 immunoreactivity was noted in the central dorsal neural retina of Mitf(vit) mice. No differences in the level of total RA in whole eyes were noted between Mitf(vit) and control mice at early postnatal ages. By 10 weeks of age there was a significant elevation of RA that was localized to the neural retina. CONCLUSIONS: In this study, we show a high level of AHD2 and RA in the neural retina of Mitf(vit) mice relative to control mice. It is possible that this elevation of RAs contributes to the retinal degeneration observed in Mitf(vit) mice either by inducing apoptosis or by enhancing the effect of some other factor(s) involved in the apoptotic pathway.

Aldehyde Oxidoreductases↗
PubMed1999

Laparoscopy for diagnosis and staging of malignancy.

The use of minimally invasive surgery for abdominal pathology, including malignancy, has increased significantly within the past decade. Despite the advances in radiographic imaging, the use of laparoscopy for diagnosing and staging abdominal malignancy has become an important tool in the overall care of these patients. A review of published series for a variety of abdominal malignancies is presented. With the growing experience in this technique, some preliminary conclusions and ongoing issues are discussed.

Abdominal Neoplasms↗
PubMed1999

Expeditious diagnosis of primary prosthetic valve failure.

Primary prosthetic valve failure is a catastrophic complication of prosthetic valves. Expeditious diagnosis of this complication is crucial because survival time is minutes to hours after valvular dysfunction. The only life-saving therapy for primary prosthetic valve failure is immediate surgical intervention for valve replacement. Because primary prosthetic valve failure rarely occurs, most physicians do not have experience with such patients and appropriate diagnosis and management may be delayed. A case is presented of a patient with primary prosthetic valve failure. This case illustrates how rapidly such a patient can deteriorate. This report discusses how recognition of key findings on history, physical examination, and plain chest radiography can lead to a rapid diagnosis.

Adult↗
PubMed1999

Heme-binding by Drosophila retinoid- and fatty acid-binding glycoprotein (RFABG), a member of the proapolipophorin gene family.

We previously have cloned and characterized a retinoid- and fatty acid-binding glycoprotein (RFABG) isolated from the heads of Drosophila melanogaster. The protein is composed of two glycosylated subunits (Mr = >200,000 and 70,000) and is a member of the proapolipophorin gene family. Spectral analysis of purified RFABG revealed an absolute absorbance peak at 405 nm, which is typical for a heme-containing protein. The aim of the present study was to characterize the heme-binding properties of RFABG. Upon saturation of the protein solution with carbon monoxide followed by dithionite reduction, a red shift of the Soret peak to 424 nm and the characteristic alpha- and beta- bands at 567 and 539 nm were observed. Native RFABG contains approximately 0.175 moles of heme (mol/mol) indicating that purified RFABG is primarily the apoprotein. Hemin-agarose affinity chromatography of the native RFABG followed by Western blot analysis showed a single immunoreactive band at 70 kDa, indicating that the heme-binding domain resides in the 70 kDa subunit. Although retinoid and fatty acid also bind to the 70 kDa subunit, no competition was observed when an excess of heme was added to a solution of retinoid or fatty acid bound to RFABG. Heme added to a solution of purified RFABG bound in a saturable manner with an affinity of 3.8 x 10(-7) m.Thus, the current study clearly demonstrates that retinoid- and fatty acid-binding glycoprotein is a novel heme-binding protein, which may be involved in the transport and/or metabolism of heme in Drosophila.

Animals↗
PubMed1998

Identification of a new member of transforming growth factor-beta superfamily in Drosophila: the first invertebrate activin gene.

Activins, a subgroup of the transforming growth factor-beta (TGF-beta) superfamily, have been extensively studied in vertebrates for their roles in growth and development. However, activins are not thought to be expressed in invertebrates. The identification of the first invertebrate activin gene is reported here. A genomic clone representing 102 F region of the Drosophila chromosome 4 is found to encode a putative activin beta. The predicted protein sequence has a multibasic protease site that would generate a mature C-terminal peptide containing 113 amino acids showing > 60% similarity to the vertebrate activin beta B (inhibin beta B) sequences. A TGF-beta family signature as well as all 9 cysteine residues conserved in the vertebrate activins are also present in this mature peptide sequence. Northern blot and RT-PCR analyses indicated that the activin beta gene is expressed in embryo, larva and adult stages of Drosophila.

Amino Acid Sequence↗
PubMed1998

Using geographic information systems to assess spatial patterns of drug use, selection bias and attrition among a sample of injection drug users.

This study sought to assess whether frequency and type of drug use are geographically located within the city of Baltimore independent of neighborhood characteristics. The second goal was to assess geographic factors associated with sample selection and attrition. The sample consisted of 597 inner-city injection drug users who were enrolled in a HIV prevention study. The residential locations were plotted using Geographic Information Systems (GIS) software. Three patterns of drug use in the prior 6 months were examined: daily use of injection heroin, daily use of injection cocaine and any use of crack cocaine. Daily use of cocaine and any use of crack were found to be statistically associated with residing in the western portion of the city and distance from the western district sexually transmitted disease clinic. After adjusting for individual level characteristics and neighborhood level variables, as measured by 1990 census tract data, daily use of cocaine was found to be associated with residing in a more southern area of the city and distance from the western district sexually transmitted disease clinic, and any crack use was found to be associated with residing in a more western area of the city and distance from the western district sexually transmitted disease clinic. Men and younger participants were more likely to reside further away from the study clinic as were individuals who dropped out of the intervention condition. The results of this study suggest that type and frequency of drug use is associated with specific geographic areas, independent of neighborhood characteristics. These results have implications for the location of drug prevention, needle exchange and other HIV prevention activities.

Adult↗