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Biomedical subjects

D B Jones

Publications and source records attributed to D B Jones.

At least 37 records · Page 2Linked to original sources
PubMed2003

Fixed precision sequential sampling plans for the greenbug and bird cherry-oat aphid (Homoptera: Aphididae) in winter wheat.

The numbers of greenbugs, Schizaphis graminum (Rondani), and bird cherry-oat aphids, Rhopalosiphum padi L., per wheat tiller (stem) were estimated in 189 production winter wheat (Triticum aestivum L.) fields located throughout Oklahoma. Taylor's power law regressions were calculated from these data and used to construct fixed precision sequential sampling schemes for each species. An evaluation data set was constructed from 240 samples taken during three growing seasons from winter wheat fields at four locations in Oklahoma. Wheat cultivar and growth stage were recorded for each field on the day of sampling. Taylor's power law parameters for evaluation fields differed significantly for both species among growing seasons, locations, and plant growth stages. Median precision achieved using the fixed precision sequential sampling schemes for each species departed <20% from expected precision over the range population intensity in the evaluation data. For the 10% of samples with greatest deviation between observed and expected precision, observed precision was 13.8-81.8% greater than that expected precision depending on aphid species and population intensity. For the greenbug, the distribution of the percentage deviation between observed and expected precision was positively skewed, so that the sampling scheme tended to over-predict precision. For the bird cherry-oat aphid, the distribution was more symmetric. Even though precision observed using the sampling schemes frequently varied from expected precision, because of the inevitable consequence of sampling error and environmental variation, the sampling schemes yielded median observed precision levels close to expected precision levels over a broad range of population intensity.

Agriculture↗
PubMed2002

Surgeon workload and motion efficiency with robot and human laparoscopic camera control.

BACKGROUND: Surgeons are now being assisted by robotic systems in a wide range of laparoscopic procedures. Some reports have suggested that robot-assisted camera control (RACC) may be superior to a human driver in terms of quality of view and directional precision, as well as long-term cost savings. Therefore, we setout to investigate the impact of RACC of surgeon motion efficiency. METHODS: Twenty pigs were randomized to undergo a standardized laparoscopic Nissen fundoplication with either a human or RACC system, the AESOP 2000. All procedures were performed by the same surgical fellow. Time was recorded for dissection and suture phases. Inertial motion sensors were used to monitor both the surgeon's hands and the camera. Digitized data were analyzed to produce summary measures related to overall motion. RESULTS: The operative times were slightly longer with RACC (mean 80.2 +/- 20.6 vs 73.1 +/- 15.4 min, not significant). With regard to operative times and surgeon motion measures, the only statistically significant differences were for setup and breakdown times, which contributed <15% to the total time for the procedure. CONCLUSION: In terms of impact on surgeon motion efficiency and operative time under normal surgical conditions, RACC is essentially the same as an expert human driver. However, careful planning and structuring of the surgical suite may yield some small gains in operative time.

Animals↗
PubMed2002

Lichtenstein inguinal herniorrhaphy using sutures versus tacks.

The Lichtenstein hernia repair has become a popular technique for most inguinal hernias performed in the United States. One attempt to improve on this technique includes the use of a tacker instead of suturing the mesh. This study compared the feasibility and time saving for placement of mesh for open inguinal hernias with a tacker versus polypropylene suture.Thirty-four patients were prospectively randomized to undergo open hernia repair using either running 2-0 polypropylene suture or a tacker device that contained spiral titanium tacks. Patients were examined after 1 week and followed for a mean of 8 months (range 1-26 months) to record postoperative complications and technical failure rate. Mesh placement times were significantly shorter in the tacker group (9.0+/-3.5 min) than the suture group (30.9+/-9.9 min). No technical complications or recurrences were found in the follow-up period in either group.Securing mesh with the tacker is safe, and repair appears durable at short-term follow-up. Using the tacker on open inguinal hernia repairs shortens the time for mesh placement compared to suture fixation. Decreased operative time may reduce overall cost.

Adolescent↗
PubMed2002

The effect of hepatic inflow occlusion on laparoscopic radiofrequency ablation using simulated tumors.

BACKGROUND: The purpose of this study was to determine the effect of hepatic inflow occlusion (the Pringle maneuver) on laparoscopic radiofrequency (RF) ablation. METHODS: Using a previously validated agarose tissue-mimic model, 1-cm simulated hepatic tumors (three per animal) were laparoscopically ablated in five pigs with normal perfusion and then in five pigs with hepatic artery and portal vein occlusion. Energy was applied until tissue temperature reached 100 degrees C (warm-up) and thereafter for eight min. Specimens were examined immediately after treatment. RESULTS: Vascular occlusion was successful in all cases per color-flow Doppler ultrasound. Pringle time was 11.4 +/- 1.6 min. Warm-up time (2.7 +/- 1.4 vs 20.2 +/- 14.0 min) was significantly faster in the Pringle group. Ablation diameter (34.8 +/- 2.9 vs 24.7 +/- 3.1 mm), proportion of round/ovoid lesions (93% vs 20%), ablation symmetry (100% vs 40%), and margin distance (5.1 +/- 3.0 vs 1.1 +/- 1.2 mm) were significantly better for the Pringle group than the No Pringle group, respectively. CONCLUSION: Using a Pringle maneuver during laparoscopic RF ablation significantly enhances ablation geometry and results in larger margins.

Animals↗
PubMed2002

Upper gastrointestinal endoscopic ultrasound and its impact on patient management: 1990-2000.

BACKGROUND: Endoscopic ultrasound (EUS) is a relatively new method used in the investigation and staging of upper gastrointestinal tract (UGIT) disease. AIMS: To review practice and outcomes of EUS in an Australian university teaching hospital. METHODS: The first part of the study was a retrospective review of indications, safety, referral patterns and technical difficulties of all EUS procedures performed at Concord Hospital, New South Wales, Australia, over a 10-year period from 1990 to 2000. The second part of the study examined the impact of EUS on the management of 225 consecutive cases, as determined by a questionnaire completed by each of the referring doctors. RESULTS: A total of 537 EUS examinations was performed over the 10-year period. Indications for EUS included: (i) assessment of oesophageal lesions (241), (ii) assessment of gastric lesions (184) and (iii) assessment of pancreaticobiliary (112) disease. Cancer staging was performed in 46.7% of oesophageal and 31.4% of gastric cases. Sedation was achieved using intravenous midazolam (5.3+/-1.3 mg; mean +/- SD) and 52% of cases required additional intravenous pethidine (48.5+/-10.0 mg; mean +/- SD). Technical difficulties were encountered in 11% of cases and these were mainly related to nontraversable luminal stricturing. Of the 537 referrals, 48.2% were from within Central Sydney Area Health Services, and the remainder were from other Sydney hospitals, New South Wales regional centres and interstate. Of 225 questionnaires sent to referring doctors, 146 questionnaires were completed and returned for analysis. EUS aided staging of malignant disease, and confirmed or established a diagnosis in 86% of cases. The diagnostic accuracy of EUS was 76% when confirmed histologically. EUS avoided further diagnostic investigations in the majority of cases and in 25% of cases surgery was avoided. Fine-needle aspiration biopsy (FNAB) during EUS would have been useful in 30% of cases. Overall, clinical decision-making and management were changed in one-third of cases. CONCLUSIONS: Endoscopic ultrasound is an accurate, safe and useful imaging method in UGIT disease. The increasing demand for EUS and EUS-guided FNAB suggests an expanding future for EUS in Australia.

Adolescent↗
PubMed2001

Comparison of video trainer and virtual reality training systems on acquisition of laparoscopic skills.

Training on a video trainer or computer-based minimally invasive surgery trainer leads to improved benchtop laparoscopic skill. Recently, improved operative performance from practice on a video trainer was reported. The purpose of this study was three fold: (a) to compare psychomotor skill improvement after training on a virtual reality (VR) system with that after training on a video-trainer, (VT) (b) to evaluate whether skills learned on the one training system are transferable to the other, and (c) to evaluate whether VR or VT training improves operative performance. For the study, 50 junior surgery residents completed baseline skill testing on both the VR and VT systems. These subjects then were randomized to either a VR or VT structured training group. After practice, the subjects were tested again on their VR and VT skills. To assess the effect of practice on operative performance, all second-year residents (n = 19) were evaluated on their operative performance during a laparoscopic cholecystectomy before and after skill training. Data are expressed as percentage of improvement in mean score/time. Analysis was performed by Student's paired t-test. The VR training group showed improvement of 54% on the VR posttest, as compared with 55% improvement by the VT group. The VR training group improved more on the VT posttest tasks (36%) than the VT training group improved on the VR posttest tasks (17%) (p <0.05). Operative performance improved only in the VR training group (p <0.05). Psychomotor skills improve after training on both VR and VT, and skills may be transferable. Furthermore, training on a minimally invasive surgery trainer, virtual reality system may improve operative performance during laparoscopic cholecystectomy.

Animals↗
PubMed2001

Accuracy and effectiveness of laparoscopic vs open hepatic radiofrequency ablation.

BACKGROUND: The purpose of this study was to compare the accuracy (in terms of ultrasound-guided probe placement) and the effectiveness (in terms of pathologic tumor-free margin) of laparoscopic vs open radiofrequency (RF) ablation. METHODS: Using a previously validated tissue-mimic model, 1-cm simulated hepatic tumors were ablated in 10 pigs randomized to open or laparoscopic techniques. Energy was applied until tissue temperature reached 100 degrees C (warm-up) and thereafter for 8 min. A pathologist blinded to technique examined all specimens immediately after treatment. Analysis was by Fisher's exact test and the Mann-Whitney U test; p < 0.05 was considered significant. RESULTS: Off-center distance (3.5 +/- 1.6 vs 4.2 +/- 1.4 mm), size (24.7 +/- 3.1 vs 25.6 +/- 3.8 mm), symmetry (40% vs 73%), margin positivity (33% vs 9%), and margin distance (1.1 +/- 1.2 vs 2.2 +/- 1.6 mm) were not significantly different between laparoscopic (n = 15) and open (n = 11) ablations, respectively. The proportion of round/ovoid lesions (20% vs 64%) was lower (p = 0.043), and warm-up time (20.2 +/- 14.0 vs 10.7 +/- 7.5) was longer (p = 0.049) for the laparoscopic than for the open groups, respectively. CONCLUSION: Accurate probe placement can be achieved using laparoscopic and open RF ablation techniques. The physiologic effects of laparoscopy may alter ablation shape and warm-up time. Additional studies are needed to establish effective ways of achieving complete tumor destruction.

Animals↗
PubMed2001

Microsphaeropsis olivacea keratitis and consecutive endophthalmitis.

PURPOSE: To report a case of fungal keratitis with consecutive endophthalmitis caused by Microsphaeropsis olivacea. METHODS: Case report. RESULTS: A 51-year-old man developed fungal keratitis and consecutive endophthalmitis after sustaining a penetrating injury to the right eye. Cultures of the aqueous humor yielded M. olivacea. Infection resolved after intraocular fungal debridement, intravitreous amphotericin B, and aggressive topical natamycin and oral fluconazole. Persistent, low-grade smoldering corneal and intraocular inflammation required topical corticosteroid therapy. CONCLUSION: M. olivacea is an exceedingly rare ocular pathogen. The intraocular portion of the infection responded quickly to intravitreal antifungal treatment; however, the course was prolonged by smoldering corneal inflammation. Prompt recognition of intraocular spread and aggressive treatment may be beneficial in fungal infections caused by unusual organisms with uncertain virulence.

Antifungal Agents↗
PubMed2001

Laparoscopic skills training.

BACKGROUND: The purpose of this study was to quantify the learning curve of a previously validated laparoscopic skills curriculum. METHODS: Second-year medical students (MS2, n = 11) and second (PGY2, n = 11) and third (PGY3, n = 6) year surgery residents were enrolled into a curriculum using five video-trainer tasks. All subjects underwent baseline testing, training (30 minutes per day for 10 days), and final testing. Scores were based on completion time. The relationship between task completion time and the number of practice repetitions was examined. Improvement (the difference in baseline and final performance) amongst groups was compared by one-way analysis of variance using the baseline score as a covariate; P <0.05 indicated significance. RESULTS: Baseline scores were not significantly different. Final scores were significantly better for MS2s versus PGY3s. Adjusted-improvement was significantly larger for the MS2s compared with PGY2s and PGY3s, and for PGY2s compared with PGY3s. The mean number of repetitions corresponding to a predicted 90th percentile score was 32. CONCLUSION: Inexperienced subjects benefit the most from skills training. For maximal benefit, we recommend that each task be practiced for at least 30 to 35 repetitions.

Adult↗
PubMed2001

Improving operative performance using a laparoscopic hernia simulator.

BACKGROUND: Traditionally, the acquisition of surgical skill has occurred entirely in the operating room. To meet the expanding challenges of cost containment and patient safety, novel methods of surgical training utilizing ex-vivo workstations are being developed. The purpose of our study was to evaluate the impact of a laparoscopic training curriculum on surgical residents' operative performance. METHODS: Twenty-one surgery residents completed baseline laparoscopic total extraperitoneal (TEP) hernia repairs. Operative performance was evaluated using a validated global assessment tool. Each resident was then randomized to a control group or a trained group. A CD ROM, video, and simulator were used for training. At the end of the study, each resident's operative performance was again evaluated. RESULTS: Improvement was significantly greater in the trained group in five of the eight individual global assessment areas as well as the composite score (P <0.05). Questionnaire data suggested that training resulted in improved understanding of the TEP hernia repair (P = 0.01) and an increased willingness to offer the operation to patients with nonrecurrent unilateral hernias (P = 0.02). CONCLUSIONS: A multimodality laparoscopic TEP hernia curriculum improves residents' knowledge of the TEP hernia repair and comfort in performing the procedure, and may also improve actual operative performance.

Clinical Competence↗
PubMed2001

Surgical aspects and future developments of laparoscopy.

Laparoscopy has revolutionized surgery and in the process influenced the practice of anesthesiology. This article reviews several minimal access procedures that have been accepted into practice, are gaining acceptance, or remain investigational. Absolute contraindications to laparoscopy have been emphasized. As the threshold for primary care physicians to refer sicker and sicker patients for surgery decreases, it is crucial for the anesthesiologist to understand physiologic stresses of pneumoperitoneum and the nuances of laparoscopic surgery. The anesthesiologist also can be recruited to adjust insufflation pressures, tweak images on monitors, rotate and position the patient, or pass balloons and bougies. With patient and surgeon expectation of no pain or nausea and early discharge, anesthetic choices become vital for the ultimate success of the procedure.

Adrenalectomy↗
PubMed2001

Tryptase-positive mast cells accompany lymphocytic as well as lymphoplasmacytic lymphoma infiltrates in bone marrow trephine biopsies.

AIMS: To investigate the specificity of increased bone marrow mast cell numbers in lymphoplasmacytic lymphoma (LPL) and to evaluate the relationship between mast cell number and the immunoglobulin phenotype of neoplastic lymphoid cells. METHODS AND RESULTS: Retrospective study of bone marrow trephine biopsy specimens from patients with LPL, compared with selected cases representing chronic lymphocytic leukaemia (CLL) and multiple myeloma (MM) of known immunoglobulin light and heavy chain phenotype. Bone marrow mast cells were counted following immunohistochemical staining of sections for mast cell tryptase. We have confirmed previous observations that mast cell numbers are increased in bone marrow infiltrates of LPL. However, we found similarly high mast cell numbers in CLL. High mast cell numbers were associated with neoplastic lymphoid cells expressing an IgM kappa phenotype. Mast cell numbers were low in all cases of MM studied and in controls with no lymphoma present. We observed an apparent bias towards kappa light chain expression in our cases of LPL. CONCLUSIONS: Mast cell number should not be considered a reliable factor in the differential diagnosis of LPL and CLL when assessing bone marrow histology. Possible bias towards kappa light chain expression in LPL requires further study, as do the mechanism and functions of mast cell recruitment by neoplastic lymphoid cells.

Aged↗
PubMed2001

Laparoscopic marsupialization and hemisplenectomy for splenic cysts.

BACKGROUND: Splenic cysts are a rare clinical entity in the United States, and historically, management has consisted of either partial or total splenectomy via an open approach. Laparoscopic treatment of splenic cysts with preservation of splenic parenchyma offers several advantages. Compared with the open approach, a laparoscopic approach may result in less postoperative pain and a more rapid return to full activity. Compared with total splenectomy, splenic preservation eliminates the risk of overwhelming postsplenectomy infection. PATIENTS AND METHODS: We present two patients with splenic cysts. One patient was treated with laparoscopic marsupialization of the cyst and the other with laparoscopic hemisplenectomy. RESULTS: Both patients are without further symptoms at 26 and 5 months' follow-up, respectively. CONCLUSIONS: Laparoscopic marsupialization and hemisplenectomy are appropriate treatment options for patients with splenic cysts.

Adult↗
PubMed2001

An incentive plan for professional fee collections at an indigent-care teaching hospital.

The authors describe the implementation and development of an incentive plan to improve professional fee collections at an indigent-care teaching hospital. They theorized that an incentive plan based on relative value unit (RVU) productivity would increase billings and collections of professional fees. Unique RVU targets were set for individual services based on the number of faculty full-time equivalents and average reported productivity for academic physicians by specialty. The incentive plan was based on the level of expected faculty billings, measured in RVUs, for each department. A "base + incentive" model was used, with the base budget being distributed monthly throughout the year, and the incentive held as a "withhold" to be paid at the year's end only if the billing target in RVUs was met. Additionally, a task force worked with physician billing office and the hospital to improve collections. In the first year after implementation of the system was in place, important increases were noted in total RVU productivity (30.5% over the previous year) and in collections (49.5% over the previous year). Sixteen of 23 departments exceeded their incentive targets, and it was possible to make distributions of professional fees to those departments, to be used within the hospital system to enhance clinical services. Moreover, the plan created an overall positive attitude toward billings and documentation of faculty activities. The authors believe that this kind of incentive plan will be increasingly important for academic faculty working in public hospital systems.

Efficiency↗
PubMed2001

Verification of improved patient outcomes with a partially implantable hearing aid, The SOUNDTEC direct hearing system.

INTRODUCTION: Partially implantable hearing devices have been developed to address some of the user-perceived shortcomings of standard amplification systems. Partially implantable devices are purported to provide improved sound quality as a result of decreased occlusion, decreased feedback, and enhanced clarity resulting from increased high-frequency gain. Such improvements may result in greater user satisfaction. To justify selection of a partially implantable device and undergoing a minor surgical procedure, verification techniques must be used to document user improvement or increased satisfaction over conventional amplification. OBJECTIVE: To evaluate patient satisfaction with the SOUNDTEC direct hearing system. STUDY DESIGN: Within-subjects repeated measures design. METHODS: Objective and subjective evaluation pre- and post-implantation with the SOUNDTEC device. Verification techniques included tonal functional gain measures with traditional amplification and the SOUNDTEC device, word recognition in quiet (NU-6) and in noise (SPIN), the Abbreviated Profile of Hearing Aid Benefit (APHAB), and the Hough Ear Institute Profile (HEIP). RESULTS: Although there was no significant difference between optimal traditional amplification and the SOUNDTEC device for speech perception measures, the SOUNDTEC device yielded statistically significant increased high-frequency functional gain. Subjective reports indicated that the SOUNDTEC device provides a cleaner, more natural sound without feedback than traditional amplification. CONCLUSIONS: Partially implantable hearing aids may address some of the limitations of traditional amplification systems.

Adult↗
PubMed2001

Laparoscopic Roux-en-Y gastric bypass using the porcine model.

BACKGROUND: The laparoscopic Roux-en-Y gastric bypass (LRYGBP) may be performed using a variety of methods. The purpose of this study was to learn how to perform the Roux-en-Y gastric bypass operation laparoscopically, using a porcine model. MATERIALS AND METHODS: 11 domestic pigs (mean weight 47 kg) underwent LRYGBP. In 8 animals, a completely laparoscopic approach was attempted, while in 3 animals a hand-assist device was used. Techniques for anvil placement, pouch calibration, and limb-length measurement were evaluated. Animals were sacrificed at the end of the procedure, and operative results were recorded. RESULTS: The hand-assist device restored tactile feedback but obscured visualization. The gastrojejunostomy leak rate was 64%, and the jejunojejunostomy leak rate was 73%. Anvil placement using transgastric and transoral methods was feasible. Calibrating the pouch with a Baker's tube was more accurate than using anatomical landmarks. Measuring limb-lengths using Babcock clamps was reliable with practice. CONCLUSION: The frailty of the porcine small intestine may limit one's ability to achieve intact anastomoses. Despite the anatomic limitations, the porcine model was well-suited for skill development and evaluation of techniques for performing the LRYGBP operation.

Anastomosis, Roux-en-Y↗
PubMed2001

The impact of intense laparoscopic skills training on the operative performance of urology residents.

PURPOSE: As laparoscopy has become more commonplace in urology, increased emphasis has been placed on laparoscopic education. We assessed the impact of laparoscopic skills training on the operative performance of urological surgeons inexperienced with laparoscopy. MATERIALS AND METHODS: Urology residents were prospectively randomized to undergo laparoscopic skills training (6) or no training (6). Baseline assessment of operative performance (scale 0 to 35) during porcine laparoscopic nephrectomy was completed by all subjects. Cumulative time to complete laparoscopic tasks using an inanimate trainer was also recorded. The skills training group then practiced inanimate trainer tasks for 30 minutes daily for 10 days. The 2 groups then repeated the timed inanimate trainer tasks and underwent repeat assessment of the ability to perform porcine laparoscopic nephrectomy. RESULTS: At baseline no statistical difference was noted in laparoscopic experience, inanimate trainer time or overall operative assessment in the 2 groups. In the skills training group mean cumulative time to complete inanimate trainer tasks decreased from 341 to 176 seconds (p = 0.003), while in the control group it decreased from 365 to 301 (p = 0.15). Operative assessment improved from initial to repeat porcine laparoscopic nephrectomy regardless of the trained versus control randomization grouping (22.0 to 27.8, p = 0.0008 and 20.8 to 26.5, p = 0.00007, respectively). CONCLUSIONS: In vivo experience enables urological surgeons inexperienced with laparoscopy to improve significantly in all aspects of complex laparoscopic procedures. In this pilot study the magnitude of improvement was independent of additional training in laparoscopic skills. Educational curriculum should include in vivo practice in addition to skills training.

Animals↗