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Biomedical subjects

T Duncan

Publications and source records attributed to T Duncan.

At least 37 records · Page 2Linked to original sources
PubMed1998

Causes of recurrence after laparoscopic hernioplasty. A multicenter study.

BACKGROUND: To determine if there are common factors beyond the learning curve that lead to recurrence after laparoscopic hernioplasty, we analyzed failures seen in seven centers specializing in laparoscopic hernia repair. METHOD: We performed a retrospective review of patients who had a laparoscopic hernioplasty (Tapp or Tep) between 1990 and 1996 at centers specializing in laparoscopic repairs (>500 repairs at each center). RESULTS: In all, 7661 patients had 10,053 hernias repaired by the transabdominal preperitoneal or the totally extraperitoneal approach; they were followed for 1 month to 6 years. In patients followed for >/=6 months with a median follow-up of 36 months, 35 repairs failed (0.4%), and all but one of these patients underwent a remedial operation. Twenty-nine had a laparoscopic repair, four had a combined laparoscopic and anterior repair, and one had an anterior repair alone. The cause of failure was determined in all 34 patients. The mechanism of recurrence was inadequate lateral fixation of the mesh in 11 cases, inadequate lateral fixation compounded by too small a mesh in three cases, missed lipoma of the cord in four cases, inadequate fixation of the mesh medially to Cooper's ligament in eight cases (seven of which were associated with too small a mesh), a missed hernia in four cases, and a hernia through a keyhole in the mesh in five cases. As surgeons gained experience, the incidence of recurrence due to missed hernias or too small a mesh decreased. CONCLUSIONS: This large multicenter study demonstrated that the incidence of recurrence after laparoscopic hernioplasty performed by experienced surgeons was extremely low and that some causes could be corrected by experience, whereas others will require changes in technique or equipment.

Hernia, Inguinal↗
PubMed1998

Breaking the cycle of violence among youth living in metropolitan Atlanta: a case history of kids alive and loved.

More teenagers in the United States die from gunshot wounds than from all natural causes of disease combined. Firearm-related mortality accounts for almost half of all deaths among African American teens. Residents of central cities have the highest probability of experiencing violent crimes. This article describes an innovative community-based intervention designed to break the cycle of violence among youth in metropolitan Atlanta. The intervention, Kids Alive and Loved (KAL), emerged from the African American community as one mother's response to the violent death of her 17-year-old son. The authors describe how her response to tragedy gave birth to a culturally appropriate intervention for youth exposed to violence. This article delineates the evolution of KAL, the role of community partners in the design of the intervention, and how diffusion of innovation theory has implications for understanding the KAL approach to breaking the cycle of violence.

Adolescent↗
PubMed1997

Laparoscopy in the evaluation and treatment of patients with AIDS and acute abdominal complaints.

BACKGROUND: The evaluation of AIDS patients with acute abdominal complaints (AAC) is quite difficult, and surgical intervention is associated with a high complication rate. The intent of this study is to evaluate the application of laparoscopy in the diagnosis and treatment of AIDS patients with AAC. METHODS: This is a retrospective analysis of 10 consecutive AIDS patients who presented with AAC. Each had evaluation by a surgical team with subsequent laparoscopic intervention. The charts were reviewed for age, sex, time with AIDS, AIDS comorbidities, evaluation modalities, findings, treatment modalities, and outcome. RESULTS: Laparoscopy resulted in the successful surgical treatment of four patients, diagnosis of medically treatable conditions in four patients, and alteration of the incision site in the remaining two patients. Each patient thus received direct benefit from laparoscopy. Two complications, in the converted patients, and no mortalities were encountered. CONCLUSIONS: Laparoscopy is a safe and effective interventional modality in the diagnosis and treatment of AAC in the AIDS patient.

Abdomen, Acute↗
PubMed1997

Development and evaluation of a sexual decision-making and social skills program: "the choice is yours--preventing HIV/STDs".

A series of interactive videodisc programs designed to reduce HIV/STD risk behaviors was developed and evaluated. Separate programs were developed for each of three race/ethnicities (African American, Hispanic, and Caucasian) at each of two age levels (middle school and high school) using extensive formative procedures. Each program uses scenarios with extensive branching story lines to teach decision-making skills and socially appropriate responses to potentially risky sexual situations. In a randomized experiment with 827 students, significant changes were observed at posttest for the four constructs assessed: (1) belief that sex occurs as a result of decisions (vs. "it just happens"), (2) belief that even a single incident of unprotected sex can result in an STD or pregnancy, (3) intentions and attitudes toward use of condoms, and (4) self-efficacy in remaining abstinent (i.e., avoiding sex). At 30-day follow-up, three of the four measures remained significant.

Adolescent↗
PubMed1997

Pheochromocytoma, chronic renal insufficiency, and hemodialysis: a combination leading to a diagnostic and therapeutic dilemma.

Pheochromocytomas are functioning paragangliomas often presenting with paroxysmal hypertension due to catecholamine secretion. The preferential diagnostic workup includes urine and serum catecholamine measurements. Therapeutic management consists of pharmacologic cardiovascular manipulation and volume expansion with subsequent surgical resection. We have encountered a symptomatic pheochromocytoma in a chronic renal insufficiency patient on hemodialysis. The diagnostic dilemma arose due to the patient's anuric status and the inherent increase in serum catecholamine levels noted in anuric patients. The therapeutic dilemma arose in the proper pharmacologic management and volume expansion in this patient on hemodialysis. The patient underwent successful resection of the pheochromocytoma and has done well. An analysis of our diagnostic and therapeutic processes as well as a review of the literature are presented to assist in the management of this difficult clinical situation.

Adrenal Gland Neoplasms↗
PubMed1996

Molecular characterization and developmental expression of a retinoid- and fatty acid-binding glycoprotein from Drosophila. A putative lipophorin.

A detailed understanding of the mechanism of lipid transport in insects has been hampered by the inability to identify the proapolipophorin gene that encodes apolipophorins I and II, the principal protein components of lipophorin, the lipid transport vehicle. Here we provide the first molecular description of the Drosophila gene encoding a retinoid- and fatty acid-binding glycoprotein (RFABG) and present evidence that it is a member of the proapolipophorin gene family. The gene, localized to the chromosome 4 (102 F region), encodes a 3351-amino acid protein that could serve as the precursor for the approximately 70-kDa and >200-kDa polypeptides associated with RFABG. The N-terminal sequence of the approximately 70-kDa polypeptide and that predicted for the >200-kDa polypeptide showed high sequence similarity to blowfly apolipophorin II and apolipophorin I, respectively. The RFABG precursor contains a signal peptide and exhibits a multidomain mosaic protein structure, which is typical of extracellular proteins. It has structural domains similar to lipid-binding proteins, namely vitellogenins and apolipoprotein B. The protein also contains a domain similar to the D domain of von Willebrand factor and mucin. The gene is expressed in the Drosophila embryo during development in cells that make up the amnioserosa and fat bodies. Immunolocalizations using specific antibodies against RFABG reveal that the protein is initially dispersed through the embryonic amnioserosa sac and latter concentrated at skeletal muscle-epidermis apodemeal contact junctions during larval development. This novel gene may play an important role in the transport of lipids, including retinoids and fatty acids, in insects.

Amino Acid Sequence↗
PubMed1996

A retrospective analysis of laparoscopically assisted ventriculoperitoneal shunts.

BACKGROUND: During the last two years, laparoscopy has been utilized to facilitate the rapid, safe and direct placement of the abdominal component of ventriculoperitoneal shunts. This study was undertaken to review the feasibility, benefits, technique, and clinical application of laparoscopically assisted ventriculoperitoneal (LAVP) shunt placement. METHODS: A retrospective analysis of the records of six patients who underwent LAVP shunt placement was undertaken. The sex, age, technique, indication for surgery, comorbid conditions, complications operative time, results, and mortality were noted. RESULTS: All patients underwent successful shunt placement. This included placement in the face of previous abdominal surgery, including a percutaneous gastrostomy. The one major complication, hemothorax, was not associated with the laparoscopic portion of the procedure. CONCLUSIONS: Using basic laparoscopic skills and nonspecialized equipment, laparoscopic assistance in ventriculoperitoneal shunt placement offers easy, direct placement of the intraabdominal portion of the catheter in most situations and provides definite patient benefits.

Adolescent↗
PubMed1996

The effect of previous lower abdominal surgery on performing the total extraperitoneal approach to laparoscopic herniorrhaphy.

At Georgia Baptist Medical Center in Atlanta, GA, we adopted the total extraperitoneal approach (TEPA) to laparoscopic herniorrhaphies because of the concerns of potential early and late complications associated with entering the abdominal cavity. In our institution, the TEPA has compared favorably with the transabdominal approach, with lower complication and recurrence rates. There has been concern, however, in performing the TEPA in patients with previous lower abdominal surgery. The question has been raised that there is increased risk of complications in these patients. From June 1993 to May 1994, we performed 247 laparoscopic herniorrhaphies in 192 patients using the TEPA. Of these, 55 hernias were repaired in 45 patients with previous lower abdominal surgery. Overall retrospective results showed a slightly higher complication rate (23.1% vs 11.3%) and slightly higher recurrence rate (1.8% vs 0%) in the patients with previous surgery over those without. Although these differences are not statistically significant, it is important to keep these risks in mind when selecting the appropriate hernia repair for each patient.

Adolescent↗
PubMed1994

Increase in retinyl palmitate concentration in eyes and livers and the concentration of interphotoreceptor retinoid-binding protein in eyes of vitiligo mutant mice.

Retinyl esters play an important role in the visual cycle because they are involved in regeneration of 11-cis-retinal for use in rhodopsin formation. In the present study, retinyl ester concentrations were significantly elevated in eyes and livers of mice homozygous for the vitiligo mutation (mivit/mivit). Vitiligo mice demonstrate a slowly progressing retinal degeneration characterized by gradual loss of photoreceptor cells and rhodopsin as well as uneven pigmentation of the retinal pigment epithelium (RPE). Analysis of retinoids by h.p.l.c. indicated that the retinyl palmitate level was increased fivefold in eyes of affected mice at 10 weeks postnatally and was threefold higher at 22 weeks of age. Accumulation of retinyl palmitate occurred in the RPE rather than the neural retina. Furthermore, the concentration of all-trans-retinol was elevated in the RPE of vitiligo mice. Levels of interphotoreceptor retinoid binding protein (IRBP) were increased in vitiligo mice between ages 4 and 14 weeks, but returned to normal by 16 weeks. Increased IRBP levels were not due to increased protein synthesis because IRBP mRNA levels did not differ significantly between control and affected animals. To examine possible systemic involvement in vitiligo mice, retinoids were evaluated in liver and plasma. Mean hepatic total vitamin A levels in affected mice were approximately 1.7 times higher than controls. Analysis of esterified and non-esterified retinoids in liver showed that the concentration of retinyl palmitate was elevated. Plasma retinol levels were normal. This study provides the first evidence of altered systemic retinoid metabolism in vitiligo mice, which occurs, significantly, under normal dietary conditions.

Animals↗
PubMed1994

A glycoprotein binding retinoids and fatty acids is present in Drosophila.

In the search for a possible Drosophila melanogaster homolog of interphotoreceptor retinoid-binding protein (IRBP), a approximately 140-kDa retinoid- and fatty acid-binding glycoprotein found in vertebrates, the 110,000 g supernatant fraction prepared from homogenates of fly heads was analyzed for the presence of proteins capable of binding radiolabeled retinol and palmitic acid. A soluble protein, which binds concanavalin A and has a retention time on size-exclusion high-performance liquid chromatography identical to that of purified bovine IRBP, was identified as binding both ligands. As assessed by fluorescence titration, the protein fraction obtained by concanavalin A-Sepharose affinity chromatography and size-exclusion chromatography of fly head supernatant had apparent dissociation constants of 2.9 x 10(-7) +/- 0.6 M for all-trans retinol, with the number (n) of independent ligand binding sites per protein molecule = 2, and 3.5 x 10(-7) +/- 0.1 M for 16-[9-anthroyloxy] palmitic acid with n = 7. High-performance liquid chromatography of hexane extracts of this protein fraction resolved several peaks with polarity and relative retention times similar, but not identical to all-trans retinol and retinal and their 9-, 11-, and 13-cis isomers. Gas chromatography/mass spectrometry analysis of fatty acid methyl esters prepared following lipid extraction of the protein identified lauric, myristic, palmitic, palmitoleic, and oleic acids as being covalently bound. Laurate, myristate, palmitate, and stearate were noncovalently bound. The apparent molecular mass of the Drosophila protein as assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining of the retinoid- and fatty acid-binding peak obtained by hydrophobic interaction chromatography of the size-exclusion fraction was approximately 70 kDa.

Animals↗
PubMed1994

Light deprivation profoundly affects gene expression of interphotoreceptor retinoid-binding protein in the mouse eye.

Ambient light appears to play a role in regulating gene and protein expression of interphotoreceptor retinoid-binding protein (IRBP), a protein that facilitates the transport of retinoids between the neural retina and pigment epithelium in the visual cycle. Pregnant CD-1 mice were placed in the dark approximately 48 hr before parturition, and the pups were reared for 14 days under these conditions. Control animals were reared on a 12 hr light/12 hr dark cycle. Northern blotting of total RNA isolated from whole mouse eyes at post-natal days 7-14 (P7-P14) showed a marked reduction in IRBP message in the light-deprived animals to 10-20% of levels in control animals. Reprobing of the blots for opsin and S-antigen message showed a significant decrease of about 80-90% in opsin message at 5.1 kb but no change in S-antigen message in the eyes of light-deprived mice. Light microscopic examination of the light-deprived mouse retinas showed no apparent abnormalities in morphological development and immunocytochemistry demonstrated normal distribution and levels of IRBP protein. Immunochemical quantitation of IRBP protein confirmed that there was no reduction in light-deprived as compared to normal mouse eyes. Similarly, when adult mice were light-deprived for 14 days, a marked reduction in IRBP message was also observed with no decrease in the amount of IRBP protein. Thus, light deprivation causes a large decrease in IRBP message in the mouse eye, but IRBP protein is not decreased. The dramatic effect of light deprivation on IRBP mRNA and some opsin mRNAs, but not on S-antigen message and the fact that IRBP protein levels are relatively unaffected, suggest a complex pathway of light regulation of photoreceptor function previously not encountered. This may involve regulatory controls at levels including gene transcription, mRNA stability or protein degradation that may make use of a feedback control mechanism involving light- or dark-dependent signal transduction.

Animals↗
PubMed1994

An institutional review of the management of choledocholithiasis in 1616 patients undergoing laparoscopic cholecystectomy.

At Georgia Baptist Medical Center, 1616 patients underwent laparoscopic cholecystectomy between December 1989 and December 1992; and 103 perioperative endoscopic retrograde cholangiopancreatography (ERCP) procedures were performed, 79 preoperative and 24 postoperative. Endoscopic sphincterotomy with stone extraction was performed in 49 patients (4.7%). Normal ERCP was noted in 46 patients (44%), four patients failed stone extraction preoperatively, and two patients failed extraction postoperatively (5.7%). Four patients had small stones (< 2 mm) managed expectantly without sphincterotomy. Ten laparoscopic common bile duct explorations and eight open common bile duct explorations were performed without retained stones after these procedures. The incidence of detected choledocholithiasis requiring intervention was 4.4 per cent, which is significantly lower than the published incidence of 8 to 15 per cent. It is assumed that a higher percentage of stones may have been detected with liberal or routine use of cholangiography. The clinical significance of these potentially missed stones have not been manifest in our series to date. The authors believe that although improved patient selection may lower the percentage of normal ERCP, this combination of minimally invasive techniques provides a satisfactory approach to choledocholithiasis.

Cholangiography↗
PubMed1993

Interphotoreceptor retinoid binding protein (IRBP) enhances rhodopsin regeneration in the experimentally detached retina.

Results obtained in a previous study showed that, compared with a normal eyecup preparation, the amount of rhodopsin regenerated and the rate at which it was resynthesized after bleaching were reduced by about 50% when the skate retina was detached from its pigment epithelium (RPE) and replaced immediately on the apical surface of the RPE (Sun and Ripps, 1992). In the present study, these observations have been extended to preparations in which the detachment procedure was performed under fluid in order to dilute the IRBP content of the interphotoreceptor matrix. The goal initially was to determine whether lowering the IRBP concentration of the subretinal space affected the regenerative process. Using fundus reflectometry, it was found that allowing fluid to enter the subretinal space exposed by the detachment procedure caused profound deficits in both the rate and amount of rhodopsin that regenerated after bleaching. Results obtained with SDS-PAGE and immunohistochemistry showed that the molecular weight of the IRBP extracted from the skate retina is similar to that of many other vertebrate species, and that antibodies prepared against mammalian IRBP react with epitopes on skate IRBP within the interphotoreceptor matrix. Accordingly, it was investigated whether it is possible to reverse the detachment-induced anomalies in rhodopsin kinetics by introducing ligand-free IRBP purified from bovine retina to the subretinal space. Again using fundus reflectometry, it was found that instilling 5 microM of a 130 microM IRBP solution between the neural retina and the RPE increased significantly the rate of regeneration, and more than doubled the amount of rhodopsin reformed in darkness.

Adaptation, Ocular↗
PubMed1993

Some problems and solutions in the study of change: significant patterns in client resistance.

Latent growth curve methodology was applied to the study of patterns of change in client resistance during parent training therapy. The clinical sample consisted of 68 mothers of children, 52 boys and 16 girls, ages 5 through 12 years, with confirmed conduct problems. Simple linear and linear spline growth models were fit to the three repeated observational measures of maternal resistance during therapy and found inadequate. Instead, a quadratic growth model was used. Pretherapy maternal characteristics of inept discipline and antisocial behavior predicted chronically high levels of resistance. Maternal depressed mood predicted less negative quadratic curvature. No significant predictors of overall change in resistance were detected. Lack of negative curvature of the resistance growth curves predicted child court offenses during a 2-year posttermination follow-up. Results are discussed with reference to the struggle-and-working-through hypothesis of client resistance.

Adult↗
PubMed1993

Parent and teacher ratings in the assessment and prediction of antisocial and delinquent behaviors.

Subjects consisted of a sample of two cohorts of approximately 100 boys each whose behaviors were rated by their parents and teachers. Criterion variables included antisocial behavior, based on parent, child, teacher, and interviewer reports, and delinquency, based on parent and child reports in addition to cumulative arrest data taken from juvenile court records. The data suggest that mothers are focused on the daily, irritating behaviors of their sons. Teachers, on the other hand, appear to focus on a relatively small number of items (e.g., child physically attacks others, associates with deviant peers), and thereby provide ratings that are better predictors of delinquency and arrest. When the mothers' ratings were constrained to include only items that were salient for teachers, their predictive validity coefficients approached the magnitude of the teacher coefficients.

Child↗
PubMed1993

Meralgia paresthetica: a complication of laparoscopic herniorrhaphy.

Laparoscopic herniorrhaphy is a new and presently evolving technique applied to the repair of inguinal defects. Many different authors have described various methods by which this can be achieved. Some of these include the transabdominal preperitoneal approach, the plug technique, the intraperitoneal onlay of mesh, and the extraperitoneal approach. The authors have performed 252 laparoscopic hernia repairs utilizing a form of the transabdominal preperitoneal procedure that is referred to as the "transperitoneal anatomic approach." The development of new procedures or the modification of existing procedures can create new problems or alter the pattern of traditional complications. These problems must be thoroughly evaluated and reported if repetition of these errors is to be avoided. Five cases of meralgia paresthetica are reported that resulted from staple entrapment of the lateral femoral cutaneous nerve during laparoscopic herniorrhaphy. An understanding of the preperitoneal inguinal anatomy and precise placement of staples will allow avoidance of this complication.

Adult↗