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Biomedical subjects

D Duke

Publications and source records attributed to D Duke.

At least 19 recordsLinked to original sources
PubMed2006

Bertolotti's syndrome. A cause of back pain in young people.

Bertolotti's syndrome is characterised by anomalous enlargement of the transverse process(es) of the most caudal lumbar vertebra which may articulate or fuse with the sacrum or ilium and cause isolated L4/5 disc disease. We analysed the elective MR scans of the lumbosacral spine of 769 consecutive patients with low back pain taken between July 2003 and November 2004. Of these 568 showed disc degeneration. Bertolotti's syndrome was present in 35 patients with a mean age of 32.7 years (15 to 60). This was a younger age than that of patients with multiple disc degeneration, single-level disease and isolated disc degeneration at the L4/5 level (p </= 0.05). The overall incidence of Bertolotti's syndrome in our study was 4.6% (35 of 769). It was present in 11.4% (20 patients) of the under-30 age group. Our findings suggest that Bertolotti's syndrome must form part of a list of differential diagnoses in the investigation of low back pain in young people.

Adolescent↗
PubMed2005

Imaging patients with "post-cholecystectomy syndrome": an algorithmic approach.

AIM: To assess the role of ultrasound (US), magnetic resonance cholangiopancreatography (MRCP) and liver function tests (LFTs) in the evaluation of selected patients presenting with late post-cholecystectomy syndrome (PCS) who were referred for endoscopic retrograde cholangiopancreatography (ERCP). MATERIALS AND METHODS: In a retrospective study a final group of 42 patients with PCS referred for diagnostic ERCP underwent MRCP and abdominal US. ERCP and MRCP images were assessed for bile duct diameters and the presence of strictures and stones. A common bile duct (CBD) diameter of < 10mm was considered normal, whereas > or = 10mm was considered abnormal on US. Findings were correlated to LFTs with contingency table results performed for single techniques and combination of methods. RESULTS: In total 14 stones and one stricture were seen. US had a high negative predictive value (86.4%). MRCP had a sensitivity of 100% and specificity of 88.0%. ERCP is the most accurate test but failed in 11 patients, five of whom had a stone. The accuracy of US and LFTs increases to 93.8% if test results agree in either negative or positive outcome. CONCLUSION: US and LFTs are first-line tests in PCS. If the CBD on US is > or = 10mm, but no cause is identified, MRCP should be performed. If US and LFTs are normal then MRCP is not necessary. The availability of LFTs raises the diagnostic value of imaging.

Adult↗
PubMed1999

Treatment of benign and atypical nevi with the normal-mode ruby laser and the Q-switched ruby laser: clinical improvement but failure to completely eliminate nevomelanocytes.

OBJECTIVE: To evaluate the effect of normal-mode and Q-switched ruby laser light (694 nm) on nevomelanocytes of benign, atypical, and congenital nevi. DESIGN: Half of the lesion of each of 31 nevi was treated with either the Q-switched ruby laser or the normal-mode ruby laser or both; the other half of the lesion was covered with aluminum foil and was not treated. SETTING: A university-affiliated, hospital-based laser center. PATIENTS: Sixteen patients with a total of 31 melanocytic nevi were enrolled in the study. INTERVENTIONS: All nevi were evaluated by at least 2 dermatologists to assess the degree of clinical atypia. Photographs were taken before and immediately after treatment and at each follow-up visit. The digital imaging system was used to evaluate the number of melanocytes in a measured length of basement membrane zone. MAIN OUTCOME MEASURE: Three individual readings (number of melanocytes per unit length) were taken on both the control and treated halves and then compared to quantitate treatment effect. All analyses used averages from 3 measurements. A Student paired t test was used to compare the treated and untreated sides. RESULTS: Sixteen (52%) of the nevi showed a clinically visible decrease in pigment on the treatment side at the 4-week follow-up visit. CONCLUSION: No lesions had complete histologic removal of all nevomelanocytes. Therefore, 1 or 2 laser treatments are not sufficient to cause complete removal of a lesion either clinically or histologically.

Adolescent↗
PubMed1999

The Virginia generalist initiative: lessons learned in a statewide consortium.

In response to Virginia's need for an increased supply of generalist physicians, the state's three medical schools--Eastern Virginia Medical School, Virginia Commonwealth University School of Medicine, and the University of Virginia School of Medicine--have formed a partnership with key governmental stakeholders in the Virginia Generalist Initiative funded by The Robert Wood Johnson Foundation's Generalist Physician Initiative. These state-supported medical schools historically have functioned independently, with little cooperative effort. This paper describes the consortium, its activities, its successes, and its unmet objectives, and uses a series of cases in point to illustrate relevant lessons learned. Some of these lessons are that (1) stakeholders must be involved from the beginning of planning to identify mutual goals and establish consortium protocols; (2) all partners must share a philosophical commitment to the consortium's mission, as well as the time and resources needed; (3) an atmosphere that enables risk-taking behavior must be created; (4) stakeholders must be willing to revise goals and sustain an environment conductive to change; and (5) trust is essential and must be vigilantly maintained. The paper concludes that the Virginia Generalist Initiative has dramatically altered the goals, objectives and programs of the three schools and has succeeded in aligning the schools' strategic objectives with the state's priorities.

Databases as Topic↗
PubMed1998

Comparative clinical trial of 2 carbon dioxide resurfacing lasers with varying pulse durations. 100 microseconds vs 1 millisecond.

OBJECTIVES: To compare the clinical and histological effects of 2 carbon dioxide lasers with different pulse durations and to evaluate the effect of carbon dioxide laser pulse duration on postprocedure erythema, wound healing, and efficacy of wrinkle treatment. DESIGN: Prospective, randomized, comparative clinical trial. SETTING: A university-affiliated hospital-based laser center. PATIENTS: Thirty-five patients with facial wrinkles were enrolled in the study. Treatment sites included 15 perioral, 14 periorbital areas, and 6 full face. INTERVENTION: A 2-sided comparison was performed. One side of the study site was treated with the TruPulse laser (Tissue Technologies, Palomar Medical Products Inc, Lexington, Mass). The other side of the study site was treated with the UltraPulse 5000 laser (Coherent Medical Inc, Palo Alto, Calif). The 2 sides were treated to equivalent tissue effects rather than maintaining the number of passes. MAIN OUTCOME MEASURES: Photographs of the treatment areas at baseline, week 1, week 2, month 2, and month 6 were evaluated by a 5-member panel for degree of erythema, amount of edema, and percentage of wrinkle improvement. Silicon skin casts for profilometry measurements before and after the treatment were compared. To evaluate skin shrinkage, surface area before and after treatment of square tattoos on both cheeks of the full-face patients were computed using a digital imaging system. Histological sections before and after the procedure were analyzed. RESULTS: At week 1, 75% of the patients had more erythema on the UltraPulse than TruPulse sides. The difference in erythema (TruPulse less than UltraPulse) between the 2 treatment sides was clinically mild yet statistically significant for weeks 1 (P = .05) and 2 (P = .05). Although observed results favored the UltraPulse over the TruPulse, the difference in efficacy between the 2 lasers did not reach statistical significance. CONCLUSIONS: Compared with the longer pulse-duration carbon dioxide laser, the shorter pulse-duration carbon dioxide laser, used with higher energy and more passes, caused slightly less erythema while maintaining efficacy. The longer pulse-duration laser required lower energy and fewer number of passes to achieve an equivalent depth of ablation, level of residual thermal damage, and degree of efficacy. The shorter TruPulse allows for more superficial tissue damage per pass and therefore is best suited for situations requiring superficial or more controlled ablation. The longer UltraPulse achieves a desirable depth of tissue damage with fewer passes. The data did not support the long-term presence of tissue collagen shrinkage in the treated areas.

Adult↗
PubMed1998

Pre-surgical CT/FEA for craniofacial distraction: I. Methodology, development, and validation of the cranial finite element model.

Recently, surgeons have begun to treat serious congenital craniofacial deformities including craniosynostoses with mechanical devices that gradually distract the skull. As a prospective means of treatment planning for such complex deformities, FE models derived from routine preoperative CT scans (CT/FEA) would provide ideal patient specific engineering analyses. The purpose of this study was to assess the dimensional and predictive accuracy of the CT/FEA process through the development of a 3D model of a dry human calvarium subjected to two-point distraction ex vivo. Comparative skull measurements revealed that CT/FEA construction error did not exceed 1% for transcranial dimensions, and the thickness error did not exceed 8.66% or 0.31 mm. CT/FEA strain predictions for the central region of the skull, between the distraction posts, were not statistically different from homologous gage values at P < 0.05. Peripherally, however, the strain fields were less well behaved and the FE predictions showed only general qualitative agreement with gage recordings.

Biomechanical Phenomena↗
PubMed1998

Presurgical finite element analysis from routine computed tomography studies for craniofacial distraction: II. An engineering prediction model for gradual correction of asymmetric skull deformities.

Finite element analysis from routine computed tomography studies (CT/FEA) allows clinicians to predict the mechanical and anatomic consequences of specific distraction systems before human application. A realistic three-dimensional CT/FEA engineering model of an actual plagiocephalic infant with unicoronal synostosis was developed using 4215 parabolic triangular shell elements and intracranial pressure conditions ranging from 10 to 20 mmHg. The completed finite element analysis model was used to predict the anatomic outcome of multiaxial distraction delivered by hypothetical patterns of rod and node distraction units. The predictions for the various patterns of distraction units were also compared quantitatively with respect to force, stress, strain, and intracranial volume. Best anatomic corrections were achieved with bilateral patterns of distraction units that simultaneously elongated the ipsilateral cranium and shortened the contralateral cranium. Greatest strain levels were experienced within the osteotomy callus, greatest stress levels at the appliance anchorage sites, and the greatest rod force at the ipsilateral lower coronal position.

Biomechanical Phenomena↗
PubMed1998

Care before and after laser skin resurfacing. A survey and review of the literature.

BACKGROUND: The extent of the wound healing period and the final outcome of cutaneous laser resurfacing are influenced not only by the treatment protocol and type of laser used but also on care of the skin before and after the procedure. OBJECTIVE: This project was conducted to determine the pre- and postresurfacing care protocols currently in practice and to research the literature in an effort to clarify which interventions can accelerate wound healing and improve efficacy of the treatment. METHODS: Three hundred thirty-nine questionnaires were mailed to all dermatology and plastic surgery members of the American Society for Laser Medicine and Surgery (ASLMS). Questionnaires were completed anonymously to decrease respondent bias. Statistical analysis included calculation of percentages and means of the data. RESULTS: Survey results are discussed and compared with data from the literature for the following interventions: tretinoin cream, glycolic acid cream, hydroquinone, oral prophylactic antibiotics, oral prophylactic antivirals, hydrogel dressings, semiocclusive ointments, topical antibiotics, topical corticosteroids, oral corticosteroids, and dilute acetic acid soaks. CONCLUSIONS: Many options are appropriate, based on data from past studies, for pre- and postresurfacing skin care. Approximately 73% of the results of the survey correlate with information from the literature. Past studies do provide information to help us select interventions that can improve wound healing and the final cosmetic outcome. Further studies involving resurfacing patients may clarify some of the more complex wound care issues, such as oral prophylactic antibiotics, hydroquinone, and topical vitamins C and E.

Data Collection↗
PubMed1997

Long-term results after CO2 laser skin resurfacing: a comparison of scanned and pulsed systems.

BACKGROUND: New laser technology permits the use of high-energy pulsed and continuous-wave carbon dioxide (CO2) lasers with flashscanners to treat rhytides. OBJECTIVE: We compared the efficacy and side effects of the two leading CO2 lasers used in skin resurfacing. METHODS: A total of 28 patients with facial rhytides were treated with either the UltraPulse or SilkTouch laser systems; in five additional patients, contralateral cosmetic units were treated with one system or the other in a direct comparison of the lasers. RESULTS: We compared photographs taken before and after treatment, and a lessening of facial wrinkling was noted in all subjects. In some subjects improvement was confirmed by optical profilometry methods. Biopsy specimens in representative patients showed that immediate thermal damage was limited to 180 microns. Long-term postoperative specimens showed changes in the papillary dermis consistent with new collagen deposition and reduction of pretreatment solar elastosis. Posttreatment facial erythema was noted in half the patients for up to 2 months; transient hyperpigmentation was observed in one third of the treated areas. CONCLUSION: Although the SilkTouch system produced more immediate thermal damage, there were no significant differences in efficacy or adverse effects between the lasers. Our results suggest that both laser systems, used with appropriate settings, are capable of safely smoothing the skin surface.

Adult↗
PubMed1996

Laser treatment of tattoos in darkly pigmented patients: efficacy and side effects.

BACKGROUND: Many modalities for the treatment of tattoos and pigmented lesions produce a greater risk of complications in Fitzpatrick types V and VI skin because of an increased incidence of adverse pigmentary changes and keloidal scarring. In fair-skinned persons Q-switched lasers have proved effective in removing pigmented lesions and tattoos without scarring. OBJECTIVE: This study was conducted to determine the efficacy and effects of Q-switched lasers on a small series of darkly pigmented patients with tattoos. METHODS: Four patients of Ethiopian origin with facial and neck tribal tattoos were treated with both the Q-switched ruby and Nd:YAG lasers. One black woman with a multicolored tattoo on the mid chest was treated with the Q-switched ruby laser. RESULTS: Clearing of all lesions was seen. The treatments did not result in scarring or permanent pigment changes other than the ones intended. CONCLUSION: Our results indicate that in darkly pigmented patients, Q-switched laser treatment of tattoos can be performed successfully. The longer wavelength Q-switched Nd:YAG laser is recommended when removing tattoos in darker complected persons. A test treatment is advised before treatment of large skin areas.

Adult↗
PubMed1996

Multiple retiform hemangioendotheliomas. A low-grade angiosarcoma.

We present the case of a 30-year-old woman who over a 10-year period has developed multiple well-differentiated angiosarcomas involving the trunk and extremities. The clinical and histologic features are characteristic of retiform hemangioendothelioma (RH), a distinctive form of low-grade angiosarcoma. This case is unique in that multiple lesions developed in different anatomic sites. We discuss the clinical and histologic characteristics, diagnosis, and prognosis of RH.

Adult↗
PubMed1995

Cost-effectiveness of captopril therapy after myocardial infarction.

OBJECTIVES: This study sought to assess the cost-effectiveness of captopril therapy for survivors of myocardial infarction. BACKGROUND: The recent randomized, controlled Survival and Ventricular Enlargement (SAVE) trial showed that captopril therapy improves survival in survivors of myocardial infarction with an ejection fraction < or = 40%. The present ancillary study was designed to determine how the costs required to achieve this increase in survival compared with those of other medical interventions. METHODS: We developed a decision-analytic model to assess the cost-effectiveness of captopril therapy in 50- to 80-year old survivors of myocardial infarction with an ejection fraction < or = 40%. Data on costs, utilities (health-related quality of life weights) and 4-year survival were obtained directly from the SAVE trial, and long-term survival was estimated using a Markov model. In one set of analyses, we assumed that the survival benefit associated with captopril therapy would persist beyond 4 years (persistent-benefit analyses), whereas in another set we assumed that captopril therapy incurred costs but no survival benefit beyond 4 years (limited-benefit analyses). RESULTS: In the limited-benefit analyses, the incremental cost-effectiveness of captopril therapy ranged from $3,600/quality-adjusted life-year for 80-year old patients to $60,800/quality-adjusted life-year for 50-year old patients. In the persistent-benefit analyses, incremental cost-effectiveness ratios ranged from $3,700 to $10,400/quality-adjusted life-year, depending on age. The outcome was generally not sensitive to changes in estimates of variables when they were varied individually over wide ranges. In a "worst-case" analysis, incremental cost-effectiveness ratios for captopril therapy remained favorable ($8,700 to $29,200/quality-adjusted life-year) for 60- to 80-year old patients but were higher ($217,600/quality-adjusted life-year) for 50-year old patients. CONCLUSIONS: We conclude that the cost-effectiveness of captopril therapy for 50- to 80-year old survivors of myocardial infarction with a low ejection fraction compares favorably with other interventions for survivors of myocardial infarction.

Aged↗
PubMed1994

Uterine rupture during pregnancy in a patient with a history of hysteroscopic metroplasty.

BACKGROUND: Uterine septa may be responsible for spontaneous abortion. Hysteroscopic metroplasty may improve pregnancy outcome. CASE: A patient with a history of hysteroscopic resection of a uterine septum presented in preterm labor. This was her second pregnancy following the procedure; the first resulted in a term vaginal delivery. This second pregnancy ended with a preterm cesarean delivery. A 3.5 x 3.5-cm fundal rupture was discovered during the cesarean. The metroplasty had been performed with the KTP laser under direct laparoscopic visualization. No surgical complications had occurred. CONCLUSIONS: Uterine rupture during a pregnancy may occur following hysteroscopic metroplasty, even when no complications occur at surgery and even if a normal pregnancy outcome follows the procedure. Physicians providing care for patients who have had hysteroscopic metroplasty should be aware of the potential for uterine rupture during pregnancy.

Adult↗
PubMed1993

Familial cutaneous melanoma and two-mutational-event modeling.

BACKGROUND: According to the Knudson two-mutational-event theory, two mutations at a genetic locus may be required for the development of some cancers. Persons who have inherited a defect in one chromosome and therefore require only one more mutation for cancer development are at a higher risk of manifesting cancer at a younger age than persons without an inherited mutation, who need two acquired "hits." This difference allows one to distinguish familial and sporadic types of the same malignancy by evaluating age of disease onset. METHODS: To study the role of inheritance in the etiology of familial cutaneous melanoma, characteristics of patients with familial versus nonfamilial melanoma were analyzed according to the Knudson two-mutational-event model. RESULTS: The familial versus nonfamilial graphs, based on age of diagnosis, did not support this model. However, there was a statistically significant earlier age of diagnosis for patients with familial melanoma. Melanoma thickness was less (i.e., earlier cancer at possibly younger age) for patients with a positive versus a negative family history. Conversely, linear regression, after adjusting for tumor thickness, showed that patients with hereditary melanoma still manifested earlier ages of diagnosis of melanoma compared with sporadic patients. CONCLUSIONS: Genetic patterns other than the two-step model, additional family-related factors, patient-physician sensitization due to a family history, or a combination of these factors might explain this age difference. More complex multistep modeling of the data may be helpful in better characterizing the genetic patterns of cutaneous melanoma.

Age Factors↗
PubMed1991

Direct gene transfer and expression into rat heart in vivo.

We found previously that genes injected into skeletal muscle can be taken up by myofibers and expressed. In the present study we found that myocardial cells can also express a variety of reporter genes injected into myocardium as efficiently as skeletal myofibers, while the cells of several other tissues cannot. The inability of tissues other than striated muscle to express injected DNA is not due to technical difficulties of injection because injected DNA was detected in these other tissues by PCR analysis. These results suggest that skeletal and cardiac muscle cells have unique features such as T tubules that may play a critical role in DNA uptake. Expression in cardiac muscle was stable for only two weeks, possibly because of an immune response against the transfected cells. The ability to directly transfer genes into myocardial cells raises the possibility of gene therapy for both acquired and genetic heart diseases.

Animals↗
PubMed1991

Standardized isolation of protoplasts.

Isolation of leaf mesophyll protoplasts from tobacco (Nicotiana tabacum) is facilitated using a specially designed digestion chamber. The chamber's airtight seals and various ports reduce the complexity, time and contamination risks which may be associated with standard isolations. The polished glass viewing window allows continuous monitoring of protoplast release, thus facilitating more precise determinations of the optimal digestion time. In concert with a simplified centrifugation step, the protoplast isolation procedure is greatly standardized.

Cell Separation↗