Biomedical subjects

Sang-Wook Lee

Publications and source records attributed to Sang-Wook Lee.

At least 19 recordsLinked to original sources

PubMed2006

Optimal time interval between capecitabine intake and radiotherapy in preoperative chemoradiation for locally advanced rectal cancer.

PURPOSE: Capecitabine and its metabolites reach peak plasma concentrations 1 to 2 hours after a single oral administration, and concentrations rapidly decrease thereafter. We performed a retrospective analysis to find the optimal time interval between capecitabine administration and radiotherapy for rectal cancer. METHODS AND MATERIALS: The time interval between capecitabine intake and radiotherapy was measured in patients who were treated with preoperative radiotherapy and concurrent capecitabine for rectal cancer. Patients were classified into the following groups. Group A1 included patients who took capecitabine 1 hour before radiotherapy, and Group B1 included all other patients. Group B1 was then subdivided into Group A2 (patients who took capecitabine 2 hours before radiotherapy) and Group B2. Group B2 was further divided into Group A3 and Group B3 with the same method. Total mesorectal excision was performed 6 weeks after completion of chemoradiation and the pathologic response was evaluated. RESULTS: A total of 200 patients were enrolled in this study. Pathologic examination showed that Group A1 had higher rates of complete regression of primary tumors in the rectum (23.5% vs. 9.6%, p = 0.01), good response (44.7% vs. 25.2%, p = 0.006), and lower T stages (p = 0.021) compared with Group B1; however, Groups A2 and A3 did not show any improvement compared with Groups B2 and B3. Multivariate analysis showed that increases in primary tumors in the rectum and good response were only significant when capecitabine was administered 1 hour before radiotherapy. CONCLUSION: In preoperative chemoradiotherapy for rectal cancer, the pathologic response could be improved by administering capecitabine 1 hour before radiotherapy.

Adult↗

PubMed2006

F-18 FDG-PET as a routine surveillance tool for the detection of recurrent head and neck squamous cell carcinoma.

In order to determine the efficacy and proper timing of routine PET scans for surveillance of recurrent head and neck squamous cell carcinoma (HNSCC), we evaluated the diagnostic performance of routine PET scans in relation to time interval from completion of treatment. Amongst 206 retrospectively evaluated post-treatment PET scans of 159 patients with HNSCC, 156 were performed for routine surveillance in subclinical cases. Diagnostic performance of PET scan and follow-up outcome were evaluated in relation to the time interval (2-6months, 6-12months, 12-24months, and >24months) of PET scan from the completion of treatment. Overall sensitivity and NPV of these PET scans for recurrence were 92.5% and 94.8%, compared with 55.0% and 76.9% for conventional evaluation methods. In the 156 routine scans, the diagnostic sensitivity, specificity, and NPV for locoregional recurrence were 90%, 91% and 97%, respectively, and the values for distant metastases and second primary cancers were 100%, 97% and 100%, respectively. The diagnostic accuracy of routine PET scans was not significantly altered by the time interval. Most (97%) of true negative cases on routine PET scans had no recurrence during a median 14months follow-up. PET scan may be a useful tool in routine surveillance for detection of recurrence in subclinical patients. For routine surveillance, the initial PET scan should be performed within 6months after completion of treatment and the proper timing of next routine PET scan for subclinical patient with initial negative PET result might be 1year after initial PET scan.

Adult↗

PubMed2006

Importance of flow division on transition to turbulence within an arteriovenous graft.

Transitional blood flow in an arteriovenous graft under various conditions of flow division was examined through direct numerical simulation. This junction consists of an inlet vessel (prosthetic graft) connected to a host vessel (vein) at an acute angle (21.6 degrees ). Inlet Reynolds numbers, based on mean velocity and graft inlet diameter, ranged from 800 to 1400. Various flow divisions between the two ends of the host vessel (i.e., the proximal venous segment, PVS, and distal venous segment, DVS) were considered (PVS:DVS ratios of 100:0, 85:15, 70:30 and 115:(15)). The numerical technique employed the spectral element method which is a high-order discretization ideally suited to the simulation of transitional flows in complex domains. High velocity and pressure fluctuations were observed for the PVS:DVS=70:30 and 85:15 cases and absent from the 100:0 and 115:(15) cases; the results indicate the importance of flow division on the development of turbulence in this junction. Transition to turbulence was observed at Reynolds numbers as low as 1000 and 800 under flow divisions of 85:15 and 70:30, respectively, significantly lower than the critical value of 2100. The frequency spectra of velocity fluctuations indicated a significant intensity within the frequency range of approximately 300Hz downstream of the junction. An adverse pressure gradient developed in the PVS when graft inflow divided into opposite directions in the junction. This pressure gradient had a destabilizing effect on the flow and enhanced transition to turbulence in the PVS. These findings suggest that measurements of in vivo flow rates at the inlet and outlets are critical for the accurate prediction of arteriovenous hemodynamics. A potential clinical application of these results might be to close off the DVS during graft construction to ensure a 100:0 flow division.

Animals↗

PubMed2006

Templated carbon nanofiber with mesoporosity and semiconductivity.

We have newly fabricated a long one-dimensional (1D) mesoporous carbon nanofiber by using a mesoporous silica nanofiber template. The resulting mesoporous carbon nanofiber shows the unique mesoporous structure of circularly wound nanochannel alignment perpendicular to the long fiber axis and the high gas sorption property, which interestingly presents the p-type semiconducting behavior.

Letter↗

PubMed2006

Topographic control of lipid-raft reconstitution in model membranes.

Liquid-ordered (L(O)) domains reconstituted in model membranes have provided a useful platform for in vitro studies of the lipid-raft model, in which signalling membrane molecules are thought to be compartmentalized in sphingolipid- and cholesterol-rich domains. These in vitro studies, however, have relied on an uncontrolled phase-separation process that gives a random distribution of L(O) domains. Obviously, a precise control of the size and spatial distribution of the L(O) domains would enable a more systematic large-scale in vitro study of the lipid-raft model. The prerequisite for such capability would be the generation of a well-defined energy landscape for reconstituting the L(O) domain without disrupting the two-dimensional (2D) fluidity of the model membrane. Here we report controlling the reconstitution of the L(O) domains in a spatially selective manner by predefining a landscape of energy barriers using topographic surface modifications. We show that the selective reconstitution spontaneously arises from the 2D brownian motion of nanoscale L(O) domains and signalling molecules captured in these nanodomains, which in turn produce a prescribed, concentrated downstream biochemical process. Our approach opens up the possibility of engineering model biological membranes by taking advantage of the intrinsic 2D fluidity. Moreover, our results indicate that the topographic configuration of cellular membranes could be an important machinery for controlling the lipid raft in vivo.

Biophysics↗

PubMed2006

Treatment-induced menstrual changes in very young (<35 years old) breast cancer patients.

PURPOSE: To evaluate the treatment-induced menstrual changes in very young (< 35 years old) breast cancer patients. METHODS AND MATERIALS: We retrospectively examined the clinical records of 160 patients, ranging in age from 18 to 34 years old (median age, 32 years), treated between June 1992 and December 2002. One hundred twenty patients underwent mastectomy and 40 underwent breast conserving surgery. Postoperatively, 80 patients were treated with alkylating agent-based chemotherapy regimens (CMF) and 80 with anthracycline-based regimens (AD). In addition, 57 patients received adjuvant radiotherapy, and 77 received anti-estrogen therapy. Treatment-induced menstrual changes and present menstrual status were evaluated from hospital records and by one-to-one interviews. The median follow-up period was 54 months (range, 29-156 months). RESULTS: Treatment-induced menstrual change (amenorrhea) was occurred in 59 (36.9%) patients, 25 (31.3%) of those treated with CMF and 34 (42.5%) with AD (p=0.142). Amenorrhea occurred after a median 2 cycles of chemotherapy (range, 1-6 cycles). Menstruation resumed in 49 (83.1%) patients, 20 (80%) of those treated with CMF and 29 (85.3%) with AD (p=0.6). Median time to resumption of menstruation was median 3.5 months (range, 1-18 months) after amenorrhea. Disease recurred in 10 (16.9%) patients who experienced treatment-induced menstrual changes and in 18 (17.8%) of those who did not (p=0.89). CONCLUSION: Although the overall incidence of treatment-induced menstrual change in breast cancer patients under age 35 was similar to that reported elsewhere, the rate of recovery from these change is higher. We observed no difference between CMF and AD treated patients in rates of amenorrhea or recovery from these changes.

Adolescent↗

PubMed2006

Orbital marginal zone B-cell lymphoma of MALT: radiotherapy results and clinical behavior.

PURPOSE: To elucidate the clinical behavior and treatment outcome of low-grade primary orbital lymphoma arising from mucosa-associated lymphoid tissue (MALT). METHODS AND MATERIALS: Forty-eight patients with pathologically confirmed marginal zone B-cell lymphoma of MALT were treated with radiotherapy (RT). Thirty-eight patients (79.1%) received thorough staging workup studies including bone marrow biopsy. Radiation doses ranged from 5.4 to 30.6 Gy (median, 30.6 Gy). Median follow-up period was 70 months. RESULTS: Only 2 patients revealed extraorbital lymphoma involvement (bone marrow, skin). Forty-six of 52 eye lesions showed complete response to RT. Six lesions demonstrated a partial response and showed gradual regression during the follow-up period of 39-72 months. Three patients experienced local recurrences at 34, 48, and 52 months after RT, which seemed to be related to improper use of the lens shield. Salvage re-RT was successful. The 10-year actuarial relapse-free survival, cause-specific survival, and overall survival rates were 93.1%, 97.9%, and 86.9%, respectively. CONCLUSION: Most of the MALT lymphoma of the orbit was localized at diagnosis and extraorbital relapse rarely occurred. Therefore, extensive staging workup at the time of diagnosis and follow-up studies to detect distant relapse may not be obligatory. Low-dose RT alone with proper lens shielding is the optimum treatment modality for orbital MALT lymphoma.

Adult↗

PubMed2006

Expression of Ku80 correlates with sensitivities to radiation in cancer cell lines of the head and neck.

The Ku protein is essential for the repair of a majority of DNA double-strand breaks in mammalian cells. The purpose of this study was to investigate the relationship between the expression of Ku70/80 and sensitivity to radiation in cancer cell lines of the head and neck. The sensitivity to radiation in various head and neck cancer cell lines (AMC-HN-1 to -9) was analyzed by colony forming assay. Of the nine cell lines examined, the most radiosensitive cell line (AMC-HN-3) and the most radioresistant cell line (AMC-HN-9) were selected for this experiments. The expression of Ku70/80 was examined after irradiation using real time PCR, Western blotting and immunofluorescence in two different cell lines. Cell cycle distribution after irradiation were analysed. A differential radioresponse was demonstrated by expression of Ku70/80 in AMC-HN-3 and AMC-HN-9 cells. While the expression of Ku70 was slightly increased in the radioresistant AMC-HN-9 cell line, the expression of Ku80 was remarkably increased, suggesting a correlation between Ku80 expression and radiation resistance. Overexpression of Ku80 plays an important role in the repair of DNA damage induced by radiation. Ku80 expression may provide an effective predictive assay of radiosensitivity in head and neck cancers.

Antigens, Nuclear↗

PubMed2006

Use of 3'-deoxy-3'-[18F]fluorothymidine PET to monitor early responses to radiation therapy in murine SCCVII tumors.

PURPOSE: 3'-Deoxy-3'-[(18)F]fluorothymidine (FLT) is a promising new radiopharmaceutical for imaging cell proliferation. We evaluated whether FLT PET can be used to monitor early responses to radiation treatment. METHODS: C3H/HeN mice bearing murine squamous cell carcinomas were randomized to irradiation with 0, 10, or 20 Gy. Twenty-four hours later, the mice were sacrificed for histopathological and biological assessment such as cell cycle analysis, Hoechst staining, and clonogenic cell survival assay. PET scans were performed on other mice after injection of [(18)F]FLT or [(18)F]fluorodeoxyglucose (FDG) before and after radiation treatment, and tumor growth was assessed over 9 days. RESULTS: Histopathological examination detected no morphological changes 24 h after radiation treatment, but cell cycle analysis showed that irradiated tumors had a decreased fraction of cells in S phase and an increased fraction in G2-M phase, compared with nonirradiated tumors. Irradiated tumors also had a higher incidence of apoptotic features and reduced clonogenic cell survival. Tumor growth was significantly delayed in irradiated mice (p<0.001) compared with control mice. PET images showed increased tumoral uptake of both FLT and FDG before radiation treatment. Following irradiation, FLT uptake differed significantly (p=0.020) from that in control mice. In contrast, FDG uptake after irradiation did not differ significantly from that in control mice. CONCLUSION: Our finding that tumor uptake of FLT was reduced at 24 h after radiation treatment suggests that FLT PET may be a promising imaging modality for monitoring the early effects of radiation therapy.

Animals↗

PubMed2006

Clinical results of stereotactic body frame based fractionated radiation therapy for primary or metastatic thoracic tumors.

The aim of this study was to evaluate the treatment outcomes of stereotactic body radiation therapy for treating primary or metastatic thoracic tumors using a stereotactic body frame. Between January 1998 and February 2004, 101 lesions from 91 patients with thoracic tumors were prospectively reviewed. A dose of 10-12 Gy per fraction was given three to four times over consecutive days to a total dose of 30-48 Gy (median 40 Gy). The overall response rate was 82%, with 20 (22%) complete responses and 55 (60%) partial responses. The one- and two-year local progression free survival rates were 90% and 81%, respectively. The patients who received 48 Gy showed a better local tumor control than those who received less than 48 Gy (Fisher exact test; p = 0.004). No pulmonary complications greater than a RTOG toxicity criteria grade 2 were observed. The experience of stereotactic body frame based radiation therapy appears to be a safe and promising treatment modality for the local management of primary or metastatic lung tumors. The optimal total dose, fractionation schedule and treatment volume need to be determined after a further follow-up of these results.

Adolescent↗

PubMed2006

Association of the GSTP1 and NQO1 polymorphisms and head and neck squamous cell carcinoma risk.

The GSTP1 and NQO1 have been reported to be associated with an increased risk for smoking related head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to determine the effect of these metabolic gene polymorphisms on the risk of HNSCC. The study population included 294 histologically confirmed HNSCC cases and 333 controls without cancer. Genotyping analysis of the GSTP1 Ile105Val and NQO1 Trp139Arg genes was performed by polymerase chain reaction-based techniques on DNA prepared from peripheral blood. The Mantel-Haenszel chi2 test was used for statistical analysis. The allele frequencies of the GSTP1 and NQO1 polymorphisms were not statistically significant between cases and controls. In analyzing the association between smoking amounts and genetic polymorphisms, GSTP1 and NQO1 polymorphisms were associated with cigarette smoking amounts in cases. G allele containing genotypes in GSTP1 and T allele containing genotypes in NQO1 were associated with a tobacco dose-dependent increase in risk of HNSCC and these genotype distributions were statistically significant (p<0.05). We found that the GSTP1 105Val allele and NQO1 139Arg allele were associated with tobacco dose-dependent increase in risk of HNSCC. GSTP1 and NQO1 genotype polymorphisms may play an important role in the development of smoking related HNSCC.

Adult↗

PubMed2005

Preparation of nanoporous MgO-coated TiO2 nanoparticles and their application to the electrode of dye-sensitized solar cells.

Sol-gel-derived Mg(OH)(2) gel was coated onto TiO(2) nanoparticles, and the subsequent thermal topotactic decomposition of the gel formed a highly nanoporous MgO crystalline coating. The specific surface area of the electrode that was prepared from the core-shell-structured TiO(2) nanoparticles significantly increased compared with that of the uncoated TiO(2) electrode. The increase in the specific surface area of the MgO-coated TiO(2) electrode was attributed to the highly nanoporous MgO coating layer that resulted from the topotactic reaction. Dye adsorption behavior and solar cell performance were significantly enhanced by employing the MgO-coated TiO(2) electrode. Optimized coating of a MgO layer on TiO(2) nanoparticles enhanced the energy conversion efficiency as much as 45% compared to that of the uncoated TiO(2) electrode. This indicates that controlling the extrinsic parameters such as the specific surface area is very important to improve the energy conversion efficiency of TiO(2)-based solar cells.

Letter↗

PubMed2005

The polymorphism and haplotypes of XRCC1 and survival of non-small-cell lung cancer after radiotherapy.

PURPOSE: The X-ray repair cross-complementing Group 1 (XRCC1) protein is involved mainly in the base excision repair of the DNA repair process. This study examined the association of 3 polymorphisms (codon 194, 280, and 399) of XRCC1 and lung cancer in terms of whether or not these polymorphisms have an effect on the survival of lung cancer patients who have received radiotherapy. METHODS AND MATERIALS: Between January 2000 and April 2004, 229 lung cancer patients with non-small-cell lung cancer in Stages I-III were enrolled. Genotyping was performed by single base primer extension assay using the SNP-IT Kit with genomic DNA samples from all patients. The haplotype of the XRCC1 polymorphisms was estimated by PHASE version 2.1. RESULTS: The patients consisted of 191 (83.4%) males and 38 (16.6%) females with a median age of 62 (range, 26-88 years). Sixty percent of the patients were included in Stage I-IIIa. The median progression-free and overall survival was 13 months and 16 months, respectively. The XRCC1 codon 194, histology, and stage were shown to be significant predictors of the progression-free survival. The 6 haplotypes among the XRCC1 polymorphisms (194, 280, and 399) were estimated by PHASE v.2.1. The patients with haplotype pairs other than the homozygous TGG haplotype pairs survived significantly longer (p = 0.04). CONCLUSIONS: Polymorphisms of XRCC1 have an effect on the survival of lung cancer patients treated with radiotherapy, and this effect seems to be more significant after the haplotype pairs are considered.

Adult↗

PubMed2005

Preoperative concurrent radiotherapy with capecitabine before total mesorectal excision in locally advanced rectal cancer.

PURPOSE: Capecitabine is an attractive radiosensitizer which can be tumor specific. This study was undertaken to evaluate the toxicity and efficacy of oral capecitabine when used with preoperative radiation therapy. METHODS AND MATERIALS: We conducted a prospective Phase II trial to assess the pathologic response, sphincter preservation effect, and acute toxicity of preoperative chemoradiation (CRT) in locally advanced (uT3-4/N +) but resectable adenocarcinoma of the lower two-thirds of the rectum. The radiation dose was 50 Gy over 5 weeks (46 Gy to whole pelvis + 4 Gy boost), and capecitabine was administered daily at a dose of 1650 mg/m(2) during the entire course of radiation therapy. Surgery was performed with standardized total mesorectal excision 4 to 6 weeks after completion of CRT and followed by four cycles of capecitabine (2500 mg/m(2)/day for 14 days). RESULTS: Ninety-five patients were entered into this study; their median age was 55 (range, 31-75 years). Ninety (95%) patients completed preoperative CRT as planned, and complete resection was achieved in 92 of 94 resected cases (98%). Downstaging rate was 71% (56/79) on endorectal ultrasonography, and it was 76% (71/94) on pathology finding. No tumor cell was observed in the specimens of 11 patients (12%). Among the 54 whose tumor was located within 5 cm from the anal verge, 40 patients (74%) underwent sphincter-preserving procedures. Elevation of the distal tumor margin from the anal verge by preoperative CRT was 0.8 +/- 1.3 cm. Grade 3 toxicities were rare (diarrhea in 3% and neutropenia in 1%). CONCLUSION: Preoperative CRT using capecitabine achieved encouraging rates of tumor downstaging and sphincter preservation with a low toxicity profile.

Adolescent↗

PubMed2005

Expressions of Ku70 and DNA-PKcs as prognostic indicators of local control in nasopharyngeal carcinoma.

PURPOSE: The objective of this study was to determine whether the expressions of the two components of DNA-dependent protein kinase, Ku70 and DNA-protein kinase catalytic subunit (DNA-PKcs), influence the response to radiotherapy (RT) and outcome of treatment of nondisseminated nasopharyngeal carcinoma (NPC) in patients who received definitive RT. METHODS AND MATERIALS: Sixty-six patients with NPC who were treated with radiotherapy alone or with concurrent chemotherapy between June 1995 and December 2001 were divided into groups based on the levels of immunoreactivity for Ku70 and DNA-PKcs in pretreatment biopsy specimens. The overexpression of Ku70 or DNA-PKcs groups included patients whose biopsy specimens showed at least 50% immunopositive tumor cells; patients in which less than 50% of the tumor cells in the biopsy tissues were immunopositive were placed in the low Ku70 and DNA-PKcs groups. The immunoreactivities for Ku70 and DNA-PKcs were retrospectively compared with the sensitivity of the tumor to radiation and the patterns of therapy failure. Univariate analyses were performed to determine the prognostic factors that influenced locoregional control of NPC. RESULTS: The 5-year locoregional control rate was significantly higher in the low Ku70 group (Ku-) (85%) than in the high Ku70 group (Ku+) (42%) (p = 0.0042). However, there were no differences in the metastases-free survival rates between the 2 groups (Ku70+, 82%; Ku70- 78%; p = 0.8672). Univariate analysis indicated that the overexpression of Ku70 surpassed other well-known predictive clinicopathologic parameters as an independent prognostic factor for locoregional control. Eighteen of 22 patients who had locoregional recurrences of the tumor displayed an overexpression of Ku70. No significant association was found between the level of DNA-PKcs expression and the clinical outcome. CONCLUSIONS: Our data suggest that the level of Ku70 expression can be used as a molecular marker to predict the response to RT and the locoregional control after RT and concurrent chemotherapy in patients with nondisseminated NPC.

Adult↗

PubMed2005

FDG-PET in the prediction of pathologic response after neoadjuvant chemoradiotherapy in locally advanced, resectable esophageal cancer.

PURPOSE: To assess the efficacy of 18Fluorodeoxyglucose-positron emission tomography (FDG-PET) for predicting a pathologic response in locally advanced esophageal cancer after neoadjuvant chemoradiotherapy. METHODS AND MATERIALS: All enrolled patients were treated with neoadjuvant chemoradiotherapy followed by esophagectomy and underwent two FDG-PET scans, before and after neoadjuvant chemoradiotherapy. We compared the results of the preoperative FDG-PET scans with the pathologic results. RESULTS: From July 2001 to July 2004, 32 patients (29 men and 3 women) were enrolled in this study. Pathologic complete response (pCR) in the esophagus was achieved in 21 of 32 patients (66%). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in the primary tumors of the preoperative FDG-PET were 27%, 95%, 75%, and 71%, respectively. In regional lymph nodes, these values were 16%, 98%, 36%, and 93%, respectively. The mean standardized uptake value (SUV) of primary tumors was initially 5.6 +/- 3.6 and changed to 1.5 +/- 1.3 after neoadjuvant chemoradiotherapy (p < 0.05). If analysis of metabolic response (SUV decrease, DeltaSUV) was limited to initially highly metabolic primary tumors (SUV > or =4.0), pathologic response was correlated with metabolic response (p = 0.006). CONCLUSIONS: This study suggested that the pathologic response of an initially highly metabolic tumor after neoadjuvant chemoradiotherapy could be correlated with the metabolic response, and FDG-PET can provide additional information on tumor response to chemoradiotherapy.

Aged↗

PubMed2005

Phase II study of radiotherapy with three-dimensional conformal boost concurrent with paclitaxel and cisplatin for Stage IIIB non-small-cell lung cancer.

PURPOSE: To evaluate the efficacy and toxicity of concurrent chemoradiotherapy with paclitaxel/cisplatin for Stage IIIB locally advanced non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS: Radiotherapy was administered to a total dose of 70.2 Gy (daily fraction of 1.8 Gy, 5 days/wk), over an 8-week period, combined with chemotherapy. The chemotherapy consisted of weekly 40 mg/m2 of paclitaxel plus 20 mg/m2 of cisplatin for 8 consecutive weeks. All patients received three-dimensional conformal radiotherapy (3D-CRT), based on computed tomography simulated planning after 41.4 Gy. The median follow-up period of survivors was 24 months. RESULTS: Between January 2000 and October 2002, 135 patients with a median age of 60 years were enrolled and analyzed in this prospective trial. The overall response rate was 75% including 2 cases of complete response. The major patterns of failure were local failure and distant metastasis. The 2-year overall and progression-free survival rates were 37% and 18%, respectively. The median overall and progression-free survival times were 17 months and 9 months, respectively. Hematologic toxicity >Grade 2 was observed in 19% of patients and severe non-hematologic toxicity was infrequent. CONCLUSIONS: Three-dimensional conformal radiotherapy, combined with paclitaxel and cisplatin chemotherapy, was associated with a satisfactory outcome with manageable toxicity. Further investigations are needed to improve the local control.

Adenocarcinoma↗

PubMed2005

Development and evaluation of an optimization-based model for power-grip posture prediction.

An optimization-based model for power-grip posture prediction was proposed. The model was based on the premise that the hand prehensile configuration in a power grip best conforms to the object shape. This premise was embodied by an optimization procedure that minimized the sum of distances from the finger joints to the object surface. The model was evaluated against data from an experiment that measured the grasp postures of 28 subjects having diverse anthropometry. The intra- and inter-person variabilities in grip postures were empirically assessed and used as benchmark values for model evaluation. The evaluation showed that the root-mean-square (RMS) values of angle differences between the predicted and measured postures had a 13.7 degrees grand mean (across all joints, subjects, and two cylindrical handles grasped), whereas the RMS values of the inter- and intra-person variabilities in measured postures had grand means of 13.0 degrees and 4.4 degrees , respectively. The model can be readily generalized to the prediction of postures in power-grasping objects of different shapes, and adapted for testing alternative prehensile strategies or performance criteria.

Adult↗