PubMed Health⌕ Search

Biomedical subjects

Daniel B Jones

Publications and source records attributed to Daniel B Jones.

At least 19 recordsLinked to original sources
PubMed2006

Construct and face validity and task workload for laparoscopic camera navigation: virtual reality versus videotrainer systems at the SAGES Learning Center.

BACKGROUND: Laparoscopic camera navigation (LCN) training on simulators has demonstrated transferability to actual operations, but no comparative data exist. The objective of this study was to compare the construct and face validity, as well as workload, of two previously validated virtual reality (VR) and videotrainer (VT) systems. METHODS: Attendees (n = 90) of the SAGES 2005 Learning Center performed two repetitions on both VR (EndoTower) and VT (Tulane Trainer) LCN systems using 30 degrees laparoscopes and completed a questionnaire regarding demographics, simulator characteristics, and task workload. Construct validity was determined by comparing the performance scores of subjects with various levels of experience according to five parameters and face validity according to eight. The validated NASA-TLX questionnaire that rates the mental, physical, and temporal demand of a task as well as the performance, effort, and frustration of the subject was used for workload measurement. RESULTS: Construct validity was demonstrated for both simulators according to the number of basic laparoscopic cases (p = 0.005), number of advanced cases (p < 0.001), and frequency of angled scope use (p < 0.001), and only for VT according to training level (p < 0.001) and fellowship training (p = 0.008). Face validity ratings on a 1-20 scale averaged 15.4 +/- 3 for VR vs. 16 +/- 2.6 for VT (p = 0.04). Ninety-six percent of participants rated both simulators as valid educational tools. The NASA-TLX overall workload score was 69.5 +/- 24 for VR vs. 68.8 +/- 20.5 for VT (p = 0.31). CONCLUSIONS: This is the largest study to date that compares two validated LCN simulators. While subtle differences exist, both VR and VT simulators demonstrated excellent construct validity, good face validity, and acceptable workload parameters. These systems thus represent useful training devices and should be widely used to improve surgical performance.

Adult↗
PubMed2006

Understanding patients' value of weight loss and expectations for bariatric surgery.

BACKGROUND: Few studies examine patients' expectations for bariatric surgery or the value patients place on weight loss. METHODS: 44 patients planning to undergo bariatric surgery were surveyed to examine patients' expectations and motivations for surgery. We also quantified how much patients valued different health and weight loss states using the standard gamble, an approach that estimates an outcome's value based on a patient's willingness to risk death to achieve the outcome. Utilities ranging from 0 to 1.00 were calculated where 1.00 represented the most desired state. RESULTS: Mean age of the patients was 42.6 years, and mean body mass index was 47.1 kg/m(2). The majority were women (n=42) and white (n=29), and reported poor quality of life. Most patients considered surgery for health reasons. Patients expected to lose 38% of their total body weight and would be disappointed if they did not lose at least 24% of their body weight. Significantly more patients were willing to risk death to achieve their "dream" weight (n=40) than to lose 20% (n=32) or 10% (n=17) of their total body weight. The respective utilities for these weight states were 0.98, 0.94, and 0.92. More patients were willing to risk death to undergo surgery (n=42) than to achieve a permanent weight loss of 20% (n=32), P<0.004. CONCLUSION: Patients appeared to value weight loss highly but had unrealistic expectations for bariatric surgery. Future studies should examine whether patient expectations, motivations, and value for realistic weight losses might predict outcomes and satisfaction after surgery.

Adult↗
PubMed2006

Measurement of the mechanical response of intra-abdominal organs of fresh human cadavers for use in surgical simulation.

Determination of soft tissue properties is essential for the realism of the virtual scenarios. The major challenge is that soft tissues exhibit complicated mechanical properties including viscoelastic, nonlinear, inhomogeneous, and rate dependent behaviors. Measurements on live human patients present significant risks, thus making the use of cadavers a logical alternative. Cadavers are widely used in present day surgical training, are relatively easy to procure through excellent donor programs and have the right anatomy, which makes them better candidates for training than the porcine model. To investigate the static and dynamic properties of soft tissue, we have developed a high precision tactile stimulator by modifying an existing haptic interface device, the Phantom, and used it to record the force-displacement behavior of intra-abdominal organs of fresh human cadavers at the US Surgical facility in Connecticut and Albany Medical College.

Abdomen↗
PubMed2005

Multicenter construct validity for southwestern laparoscopic videotrainer stations.

BACKGROUND: The "Southwestern" videotrainer stations have demonstrated concurrent validity (transferability to the operating room). The purpose of this study was to evaluate the Southwestern stations for construct validity (the ability to discriminate between subjects at different levels of experience). MATERIALS AND METHODS: From two surgical training programs, Institutional Review Board approved protocol data were collected from 142 subjects, including novice (medical students and R1, n = 66), intermediate (R2-R4, n = 67), and advanced (R5 and expert surgeons, n = 9) groups. All participants performed three repetitions on each of five stations. Completion time was scored for each task. Laparoscopic experience was determined from residency case log databases and from expert surgeon personal case logs. Results for the three groups were compared using one-way ANOVA, including relevant pair-wise comparisons. Correlations between number of laparoscopic cases performed and task scores were determined by Pearson's and Spearman's rho-correlation coefficients. RESULTS: The mean number of laparoscopic cases performed prior to completing the five tasks was 0 for novices, 9 for intermediates, and 431 for the advanced group. Significant differences (P < 0.001) were noted between groups for all five tasks and composite score. Task scores and composite scores significantly correlated with laparoscopic experience (P < 0.01). CONCLUSION: These data suggest that differences in laparoscopic ability are detected by performance on the videotrainer; thus, construct validity is demonstrated. Moreover, scores accurately reflect laparoscopic experience. Further validation may allow such simulators to be used for testing and credentialing purposes.

Adult↗
PubMed2005

Best practice recommendations for surgical care in weight loss surgery.

OBJECTIVE: To establish evidence-based guidelines for best practices for surgical care in weight loss surgery (WLS). RESEARCH METHODS AND PROCEDURES: We carried out a systematic search of English-language literature on WLS in MEDLINE and the Cochrane Library. Key words were used to narrow the field for a selective review of abstracts. Data extraction was performed, and evidence categories were assigned according to a grading system based on established evidence-based models. RESULTS: We assessed types of WLS, recommended guidelines for appropriateness, developed strategies for medical error reduction, established criteria for credentialing of systems and practitioners, and specified research needed for the future. DISCUSSION: Surgeon training, credentialing, and type of surgery performed were identified as key factors in patient safety. Other important issues in the delivery of best practice care included appropriate patient selection; use of a multidisciplinary treatment team; facility staffing, equipment, and administrative support; and early recognition and proper management of complications.

Biliopancreatic Diversion↗
PubMed2005

Staple-line buttressing material in gastric-bypass surgery.

The problem of obesity has reached epidemic proportions in the USA. More than 50% of adults are obese or overweight. The only therapeutic intervention that provides effective long-term weight loss for the severely obese is bariatric surgery. Roux-en-Y gastric bypass is the most commonly performed bariatric operation in the USA. Anastomotic leaks can cause life-threatening sepsis in the immediate postoperative period or delayed presentations with fistulas. Fibrin sealant and bovine pericardium have been used to reinforce the anastomosis in order to decrease the rate of this dreaded complication. This review will summarize current literature on the subject.

Anastomosis, Surgical↗
PubMed2005

Improved virtual surgical cutting based on physical experiments.

Simulation of surgical cutting is one of the most challenging tasks in the development of a surgery simulator. Changes in topology during simulation make any precomputed data meaningless. Moreover, the process is nonlinear and given the complexity of soft tissue mechanics, the underlying physics is not well understood. Therefore, fully realistic procedures for the simulation of surgical cutting at real time rates on single processor machines is possibly out of reach. We developed a geometry-based algorithm that is capable of simulating progressive cutting without increasing the number of primitives and have coupled it to a meshfree physically based simulation scheme. In this paper we enhance a geometrically efficient cutting algorithm by including physical information from actual cutting experiments.

Algorithms↗
PubMed2005

Training methods for minimally invasive bariatric surgery.

It is well-established that laparoscopic Roux-en-y gastric bypass is a technically challenging operation that requires a long learning curve. With the demand for bariatric surgery, particularly laparoscopic bariatric surgery on the rise, the focus has changed to ensure those performing this difficult procedure are trained appropriately. The ideal training would emphasize two things: (1) acquisition of advanced laparoscopic skills and intraoperative techniques, and (2) knowledge of preoperative and postoperative care of the bariatric patient. The current models for training for laparoscopic bariatric surgery fall into several categories: no training, formal courses, mini-fellowships, and formal minimally invasive surgery/bariatric fellowships. Each of these training paradigms is examined, as well as the available data that compare their effectiveness.

Bariatric Surgery↗
PubMed2004

Bioprocess-centered molecular design (BMD) for the efficient production of an interfacially active peptide.

The efficient expression and purification of an interfacially active peptide (mLac21) was achieved by using bioprocess-centered molecular design (BMD), wherein key bioprocess considerations are addressed during the initial molecular biology work. The 21 amino acid mLac21 peptide sequence is derived from the lac repressor protein and is shown to have high affinity for the oil-water interface, causing a substantial reduction in interfacial tension following adsorption. The DNA coding for the peptide sequence was cloned into a modified pET-31(b) vector to permit the expression of mLac21 as a fusion to ketosteroid isomerase (KSI). Rational iterative molecular design, taking into account the need for a scaleable bioprocess flowsheet, led to a simple and efficient bioprocess yielding mLac21 at 86% purity following ion exchange chromatography (and >98% following chromatographic polishing). This case study demonstrates that it is possible to produce acceptably pure peptide for potential commodity applications using common scaleable bioprocess unit operations. Moreover, it is shown that BMD is a powerful strategy that can be deployed to reduce bioseparation complexity.

Cloning, Molecular↗
PubMed2004

Screening protein refolding using surface plasmon resonance.

Surface plasmon resonance (SPR) measurements were used to screen refolding conditions to identify a physicochemical environment which gives an acceptable refolding yield for samples of glutathione-S-transferase (GST) denatured in 6 M guanidine hydrochloride and 32 mM dithiothreitol. The SPR measurements were performed on carboxymethylcellulose coated chips that could accommodate two separate flow paths. One side of the chip was derivatized with immobilized glutathione and the other with goat anti-GST antibody. This created a dual-derivatized chip capable of showing both the presence of GST and providing a measure of enzyme activity. The dual-derivatized chip could be regenerated using a two-step washing procedure and reused to analyze multiple samples from a screening study of protein refolding conditions. SPR measurements have been shown to be suitable for screening protein refolding conditions due to the high sensitivity, ease of chip regeneration and the ability to incorporate a control in the experimental design. The combination of such advantages with the high-throughput automated SPR systems currently available may be a valuable approach to determine conditions suitable for protein refolding following insoluble expression in a bacterial host.

Biosensing Techniques↗
PubMed2004

Basic ultrasound curriculum for medical students: validation of content and phantom.

Effective use of ultrasound requires an understanding of the physics, combined with the ability to interpret the sonographic images. The aim of our study was to evaluate the impact of a basic ultrasound curriculum using a phantom to train medical students. Twenty-eight first- to fourth-year medical students were randomized to two groups: a control group that received no formal training and a trained group that received basic ultrasound training. Both groups took an initial multiple-choice written test and an ultrasound hands-on test using an agarose-based tissue mimic containing various objects. The curriculum for the trained group consisted of reading the principles of ultrasound and a hands-on session over the phantom. After training, both groups underwent a second multiple-choice exam and ultrasound practical test. The initial and the post-training test results were analyzed using a two-tailed Student's t-test. Baseline written and practical test scores were similar for both groups. After training, written test scores improved (82% trained vs. 66% control, P < 0.001). Hands-on ultrasound task performance also improved with training (96% trained vs. 60% control, P <0.001). The trained group took a shorter time to obtain a clear image and found on average one more object per scan. Parameters such as time to obtain a useful image and number of objects recognized also improved with training. Basic sonographic physics, imaging, and interpretation can be effectively taught to medical students during a short training session.

Curriculum↗
PubMed2003

Assessment of basic human performance resources predicts operative performance of laparoscopic surgery.

BACKGROUND: Interest in laparoscopic surgery has prompted development of educational programs designed to teach and assess laparoscopic skills. Although these programs are beneficial, because of the inherent demands imposed by laparoscopy some aspects of operative performance might not improve with practice. This suggests that innate ability could predict level of operative skill. Assessment of operative and technical potential to date has relied largely on subjective rather than objective criteria. In this study, the relationships between objective measures of human basic performance resources (BPRs) and laparoscopic performance were evaluated using Nonlinear Causal Resource Analysis (NCRA), a novel predictive and explanatory modeling approach based on General Systems Performance Theory. STUDY DESIGN: Twenty urology residents were voluntary enrolled. Thirteen validated BPRs were measured and analyzed relative to operative laparoscopic performance (assessed by two experts) of two porcine laparoscopic nephrectomies (LN). The laparoscopic procedure, representing a High Level Task (HLT), was evaluated using a modified Global Rating of Operative Performance Scale. NCRA models were devised to predict performance of the HLT laparoscopic nephrectomies based on BPRs and to determine the limiting performance resource. RESULTS: NCRA models predicted excellent agreement with actual operative performance, suggesting that measures of innate ability (or BPRs) predicted performance of laparoscopic nephrectomy. In 65%, the prediction by NCRA was near identical to the expert rating on the HLT. In 25% of cases, NCRA overpredicted performance; in 10%, NCRA underpredicted performance of the HLT compared to the subjective ratings. Neuromotor channel capacity was the most common performance-limiting resource. CONCLUSIONS: Preliminary findings suggest objective prediction of laparoscopic performance with limiting resource diagnostics for an individual surgeon is possible and practical using appropriate new measurement and modeling methods. Selection of surgical candidates, training, and educational curriculum could be positively affected.

Adult↗
PubMed2003

Laparoscopic Heller myotomy with bolstering partial posterior fundoplication for achalasia.

BACKGROUND: The ideal antireflux procedure following laparoscopic Heller myotomy for achalasia is controversial. We present a novel laparoscopic technique of partial posterior fundoplication to bolster the myotomy. METHODS: Between August 1998 and March 2002, eight patients (five females and three males; median age, 40 years) underwent a laparoscopic Heller myotomy with bolstering partial posterior fundoplication. Results of barium swallow and manometry studies were consistent with achalasia. Failed medical treatments included balloon dilation, botulinum injection, and calcium channel blockers. RESULTS: The preoperative weight loss was 33 lb (range, 10-50) with a mean duration of symptoms of 29 months (range, 12-72). Seventy-one percent of the patients had reflux. Myotomy was confirmed with endoscopic guidance. Partial posterior fundoplication was performed with the edges of the myotomy on the right and left sides sutured to the stomach, which covered the myotomy. No conversion was required. In one patient, a perforation was recognized, repaired, and bolstered. The mean operative blood loss was 72 mL (range, 30-150). The mean operative time was 4 hours. Patients resumed solids at 2.5 days (range, 2-5). Postoperative complications included subcutaneous emphysema (n = 1), pneumothorax (n = 1), and umbilical port hernia (n = 1). None of the patients had reflux symptoms at 3 to 18 months of follow-up. CONCLUSION: Laparoscopic Heller myotomy with partial posterior fundoplication is technically feasible and effectively prevents reflux symptoms. Bolstering the myotomy may help heal small esophageal perforations.

Adult↗