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Papers by Brian Allen
Clinical Cancer Research, 2004
Purpose: The BRAF gene encodes a serine/threonine kinase and plays an important role in the mitog... more Purpose: The BRAF gene encodes a serine/threonine kinase and plays an important role in the mitogen-activated protein kinase signaling pathway. BRAF mutations in sporadic colorectal cancer with microsatellite instability (MSI) are more frequently detected than those in microsatellite stable cancer. In this study, we sought to compare the frequencies of BRAF mutations in sporadic colorectal cancer with MSI with those in hereditary nonpolyposis colorectal cancer (HNPCC). Experimental Design: We analyzed BRAF mutations in 26 colorectal cancer cell lines, 80 sporadic colorectal cancers, and 20 tumors from HNPCC patients by DNA sequencing and sequence-specific PCR. The methylation status of the hMLH1 gene was measured by either sequencing or restriction enzyme digestion after NaHSO 3 treatment. Results: We observed a strong correlation of BRAF mutation with hMLH1 promoter methylation. BRAF mutations were present in 13 of 15 (87%) of the colorectal cell lines and cancers with methylated hMLH1, whereas only 4 of 91 (4%) of the cell lines and cancers with unmethylated hMLH1 carried the mutations (P < 0.00001). Sixteen of 17 mutations were at residue 599 (V599E). A BRAF mutation was also identified at residue 463 (G463V) in one cell line. In addition, BRAF mutations were not found in any cancers or cell lines with K-ras mutations. In 20 MSI؉ cancers from HNPCC patients, however, BRAF mutations were not detectable, including a subset of 9 tumors with negative hMLH1 immunostaining and methylated hMLH1. Conclusions: BRAF mutations are frequently present in sporadic colorectal cancer with methylated hMLH1, but not in HNPCC-related cancers. This discrepancy of BRAF mutations between sporadic MSI؉ cancer and HNPCC might be used in a strategy for the detection of HNPCC families.
Radiology, Jan 10, 2016
Purpose To determine, in a multicenter double-blinded placebo-controlled trial, whether maximal h... more Purpose To determine, in a multicenter double-blinded placebo-controlled trial, whether maximal hepatic arterial phase breath-holding duration is affected by gadoxetate disodium administration. Materials and Methods Institutional review board approval was obtained for this prospective multi-institutional HIPAA-compliant study; written informed consent was obtained from all subjects. At three sites, a total of 44 volunteers underwent a magnetic resonance (MR) imaging examination in which images were acquired before and dynamically after bolus injection of gadoxetate disodium, normal saline, and gadoterate meglumine, administered in random order in a single session. The technologist and volunteer were blinded to the agent. Arterial phase breath-holding duration was timed after each injection, and volunteers reported subjective symptoms. Heart rate (HR) and oxygen saturation were monitored. Images were independently analyzed for motion artifacts by three radiologists. Arterial phase br...
Gastroenterology, 2015
BACKGROUND & AIMS: Multigene panels are commercially available tools for hereditary cancer risk a... more BACKGROUND & AIMS: Multigene panels are commercially available tools for hereditary cancer risk assessment that allow for next-generation sequencing of numerous genes in parallel. However, it is not clear if these panels offer advantages over traditional genetic testing. We investigated the number of cancer predisposition gene mutations identified by parallel sequencing in individuals with suspected Lynch syndrome. METHODS: We performed germline analysis with a 25-gene, next-generation sequencing panel using DNA from 1260 individuals who underwent clinical genetic testing for Lynch syndrome from 2012 through 2013. All patients had a history of Lynch syndrome-associated cancer and/or polyps. We classified all identified germline alterations for pathogenicity and calculated the frequencies of pathogenic mutations and variants of uncertain clinical significance (VUS). We also analyzed data on patients' personal and family history of cancer, including fulfillment of clinical guidelines for genetic testing. RESULTS: Of the 1260 patients, 1112 met National Comprehensive Cancer Network (NCCN) criteria for Lynch syndrome testing (88%; 95% confidence interval [CI], 86%-90%). Multigene panel testing identified 114 probands with Lynch syndrome mutations (9.0%; 95% CI, 7.6%À10.8%) and 71 with mutations in other cancer predisposition genes (5.6%; 95% CI, 4.4%À7.1%). Fifteen individuals had mutations in BRCA1 or BRCA2; 93% of these met the NCCN criteria for Lynch syndrome testing and 33% met NCCN criteria for BRCA1 and BRCA2 analysis (P ¼ .0017). An additional 9 individuals carried mutations in other genes linked to high lifetime risks of cancer (5 had mutations in APC, 3 had bi-allelic mutations in MUTYH, and 1 had a mutation in STK11); all of these patients met NCCN criteria for Lynch syndrome testing. A total of 479 individuals had 1 or more VUS (38%; 95% CI, 35%-41%). CONCLUSIONS: In individuals with suspected Lynch syndrome, multigene panel testing identified high-penetrance mutations in cancer predisposition genes, many of which were unexpected based on patients' histories. Parallel sequencing also detected a high number of potentially uninformative germline findings, including VUS.
Journal of the American College of Radiology : JACR, 2017
Despite the frequent statement that "most men die with prostate cancer, not of it," the... more Despite the frequent statement that "most men die with prostate cancer, not of it," the reality is that prostate cancer is second only to lung cancer as a cause of death from malignancy in American men. The primary goal during baseline evaluation of prostate cancer is disease characterization, that is, establishing disease presence, extent (local and distant), and aggressiveness. Prostate cancer is usually diagnosed after the finding of a suspicious serum prostate-specific antigen level or digital rectal examination. Tissue diagnosis may be obtained by transrectal ultrasound-guided biopsy or MRI-targeted biopsy. The latter requires a preliminary multiparametric MRI, which has emerged as a powerful and relatively accurate tool for the local evaluation of prostate cancer over the last few decades. Bone scintigraphy and CT are primarily used to detect bone and nodal metastases in patients found to have intermediate- or high-risk disease at biopsy. The American College of Radi...
Journal of the American College of Radiology, 2012
Because virtually all patients with colonic cancer will undergo some form of surgical therapy, th... more Because virtually all patients with colonic cancer will undergo some form of surgical therapy, the role of preoperative imaging is directed at determining the presence or absence of synchronous carcinomas or adenomas and local or distant metastases. In contrast, preoperative staging for rectal carcinoma has significant therapeutic implications and will direct the use of radiation therapy, surgical excision, or chemotherapy. CT of the chest, abdomen, and pelvis is recommended for the initial evaluation for the preoperative assessment of patients with colorectal carcinoma. Although the overall accuracy of CT varies directly with the stage of colorectal carcinoma, CT can accurately assess the presence of metastatic disease. MRI using endorectal coils can accurately assess the depth of bowel wall penetration of rectal carcinomas. Phased-array coils provide additional information about lymph node involvement. Adding diffusion-weighted imaging to conventional MRI yields better diagnostic accuracy than conventional MRI alone. Transrectal ultrasound can distinguish layers within the rectal wall and provides accurate assessment of the depth of tumor penetration and perirectal spread, and PET and PET/CT have been shown to alter therapy in almost one-third of patients with advanced primary rectal cancer. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.
Journal of the American College of Radiology, 2014
Although localized renal cell carcinoma can be effectively treated by surgery or ablative therapi... more Although localized renal cell carcinoma can be effectively treated by surgery or ablative therapies, local or distant metastatic recurrence after treatment is not uncommon. Because recurrent disease can be effectively treated, patient surveillance after treatment of renal cell carcinoma is very important. Surveillance protocols are generally based on the primary tumor's size, stage, and nuclear grade at the time of resection, as well as patterns of tumor recurrence, including where and when metastases occur. Various imaging modalities may be used in the evaluation of these patients. Literature on the indications and usefulness of these radiologic studies is reviewed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a wellestablished consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.
Pose control for physically simulated characters has typically been based on proportional-derivat... more Pose control for physically simulated characters has typically been based on proportional-derivative (PD) controllers. In this paper, we introduce a novel, analytical solution to the 2nd-order ordinary differential equation governing PD control. The analytic solution is tailored to the needs of pose control for animation, and provides significant improvement in the precision of control, particularly for simulated characters in dynamic conditions.
Bulletin of the American …, 2010
Current Filamentation Instability, CFI, is of central importance for the propagation of relativis... more Current Filamentation Instability, CFI, is of central importance for the propagation of relativistic electron beams in plasmas and could play an important role in the generation of magnetic fields and of radiation in the after-glow of gamma ray bursts and for energy transport in the fast-...
Precise control with proportional-derivative (PD) control generally requires stiffness. The propo... more Precise control with proportional-derivative (PD) control generally requires stiffness. The proposed method determines critically damped PD control trajectories that precisely obtain target position and velocity constraints for arbitrary initial conditions. An analytic solution provides the PD control parameters, thereby determining the required impedance. The resulting controller precisely interpolates the target state by solving the full boundary-value problem. Control parameters are time-invariant, and need only be recomputed if the system diverges from the computed trajectory due to unexpected forces or noise. The resulting method provides control with automatically determined compliance, yielding natural response to perturbation. NOMENCLATURE (θ(t), ω(t)) Position and velocity at time t m(t) Moment of inertia at time t (θ 0 , ω 0 , t 0) Initial state of the system at time t 0 (θ d , ω d , t d) Desired state for the target time t d τ (t) Computed control torque for time t k Computed stiffness of PD controller γ Computed damping of PD controller
Objective: Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditar... more Objective: Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary bowel cancer. Multiple generations are affected with colorectal cancer at relatively young age, between 25 and 45 years. We conducted this study to investigate the frequency of HNPCC in Pakistani population, due to the high incidence of colorectal cancer in younger Pakistani adults and prevalence of consanguinity in this region. Methodology: Ninety histopathologically confirmed colorectal cancer patients between 12-50 years and their families were interviewed using a detailed questionnaire. The questions about family history of colorectal cancer, history of other cancers, age at diagnosis and consanguinity were asked. The pedigrees were drawn for all families based on given information. To confirm cancers reported in relatives, hospital records were also reviewed. Amsterdam criteria were used to label a family as HNPCC. Results: Seventeen patients (18.9%) had one or more first or second degree relatives under age 50 years with colorectal cancers suggestive of HNPCC. Another 15 patients (16.7%) had first or second degree relatives with a family history of other extra-colonic cancers including ovarian, breast, endometrium, lung, parotid, brain and bladder cancer. Of these 30 patients (33.3%) reported that their parents were first degree cousins. Conclusion: High frequency of HNPCC was seen in Pakistani population; higher proportion of colorectal cancer in young Pakistanis, strong prevalence of consanguineous marriages could be important factors for HNPCC occurrence in Pakistan. However future studies with large sample size along with genetic testing and screening programmes are warranted.
Genetics Selection …, 2005
The aim of this study was to compare the variance component approach for QTL linkage mapping in h... more The aim of this study was to compare the variance component approach for QTL linkage mapping in half-sib designs to the simple regression method. Empirical power was determined by Monte Carlo simulation in granddaughter designs. The factors studied (base values in parentheses) included the number of sires (5) and sons per sire (80), ratio of QTL variance to total genetic variance (λ = 0.1), marker spacing (10 cM), and QTL allele frequency (0.5). A single bi-allelic QTL and six equally spaced markers with six alleles each were simulated. Empirical power using the regression method was 0.80, 0.92 and 0.98 for 5, 10, and 20 sires, respectively, versus 0.88, 0.98 and 0.99 using the variance component method. Power was 0.74, 0.80, 0.93, and 0.95 using regression versus 0.77, 0.88, 0.94, and 0.97 using the variance component method for QTL variance ratios (λ) of 0.05, 0.1, 0.2, and 0.3, respectively. Power was 0.79, 0.85, 0.80 and 0.87 using regression versus 0.80, 0.86, 0.88, and 0.85 using the variance component method for QTL allele frequencies of 0.1, 0.3, 0.5, and 0.8, respectively. The log 10 of type I error profiles were quite flat at close marker spacing (1 cM), confirming the inability to fine-map QTL by linkage analysis in half-sib designs. The variance component method showed slightly more potential than the regression method in QTL mapping. quantitative trait loci / QTL detection / half-sib design / power
Radiographics, 2010
Percutaneous cryoablation of renal tumors requires a number of important steps for success and re... more Percutaneous cryoablation of renal tumors requires a number of important steps for success and relies heavily on imaging for treatment planning, intraprocedural guidance and monitoring, detection of untreated tumor, and surveillance for disease progression. Imaging-guided percutaneous cryoablation has several advantages over laparoscopic cryoablation. In particular, computed tomography (CT) and magnetic resonance (MR) imaging allow global evaluation of the ablation zone and an accurate depiction of the treatment margin. Ultrasonography allows real-time guidance of probe placement but cannot help depict ice ball formation as accurately as CT or MR imaging. Multiphasic CT or MR imaging should be performed at structured intervals following ablation. Treated tumors are expected to decrease in size over time, and lesion growth and internal or nodular enhancement are suspicious for tumor recurrence or progression. Complications include probe site pain, hematoma, incomplete ablation, and recurrent tumor. Current limitations of percutaneous cryoablation include the inability to control hemorrhage without intraarterial access and a lack of long-term follow-up data. Nevertheless, percutaneous cryoablation is an effective choice for minimally invasive nephron-sparing treatment of renal tumors. ©
… 항공우주| 국내연구성과| IP …
In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing... more In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing Body model with internally blown flaps. The test was performed at the NASA Langley 14 x 22 Foot Subsonic Tunnel at low speeds. Off-body measurements were obtained with a ...
… 항공우주| 국내연구성과| IP …
In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing... more In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing Body model with internally blown flaps. The test was performed at the NASA Langley 14 x 22 Foot Subsonic Tunnel at low speeds. Off-body measurements were obtained with a ...
International Wound Journal, 2009
Clinical Cancer Research, 2004
Purpose: The BRAF gene encodes a serine/threonine kinase and plays an important role in the mitog... more Purpose: The BRAF gene encodes a serine/threonine kinase and plays an important role in the mitogen-activated protein kinase signaling pathway. BRAF mutations in sporadic colorectal cancer with microsatellite instability (MSI) are more frequently detected than those in microsatellite stable cancer. In this study, we sought to compare the frequencies of BRAF mutations in sporadic colorectal cancer with MSI with those in hereditary nonpolyposis colorectal cancer (HNPCC). Experimental Design: We analyzed BRAF mutations in 26 colorectal cancer cell lines, 80 sporadic colorectal cancers, and 20 tumors from HNPCC patients by DNA sequencing and sequence-specific PCR. The methylation status of the hMLH1 gene was measured by either sequencing or restriction enzyme digestion after NaHSO 3 treatment. Results: We observed a strong correlation of BRAF mutation with hMLH1 promoter methylation. BRAF mutations were present in 13 of 15 (87%) of the colorectal cell lines and cancers with methylated hMLH1, whereas only 4 of 91 (4%) of the cell lines and cancers with unmethylated hMLH1 carried the mutations (P < 0.00001). Sixteen of 17 mutations were at residue 599 (V599E). A BRAF mutation was also identified at residue 463 (G463V) in one cell line. In addition, BRAF mutations were not found in any cancers or cell lines with K-ras mutations. In 20 MSI؉ cancers from HNPCC patients, however, BRAF mutations were not detectable, including a subset of 9 tumors with negative hMLH1 immunostaining and methylated hMLH1. Conclusions: BRAF mutations are frequently present in sporadic colorectal cancer with methylated hMLH1, but not in HNPCC-related cancers. This discrepancy of BRAF mutations between sporadic MSI؉ cancer and HNPCC might be used in a strategy for the detection of HNPCC families.
Radiology, Jan 10, 2016
Purpose To determine, in a multicenter double-blinded placebo-controlled trial, whether maximal h... more Purpose To determine, in a multicenter double-blinded placebo-controlled trial, whether maximal hepatic arterial phase breath-holding duration is affected by gadoxetate disodium administration. Materials and Methods Institutional review board approval was obtained for this prospective multi-institutional HIPAA-compliant study; written informed consent was obtained from all subjects. At three sites, a total of 44 volunteers underwent a magnetic resonance (MR) imaging examination in which images were acquired before and dynamically after bolus injection of gadoxetate disodium, normal saline, and gadoterate meglumine, administered in random order in a single session. The technologist and volunteer were blinded to the agent. Arterial phase breath-holding duration was timed after each injection, and volunteers reported subjective symptoms. Heart rate (HR) and oxygen saturation were monitored. Images were independently analyzed for motion artifacts by three radiologists. Arterial phase br...
Gastroenterology, 2015
BACKGROUND & AIMS: Multigene panels are commercially available tools for hereditary cancer risk a... more BACKGROUND & AIMS: Multigene panels are commercially available tools for hereditary cancer risk assessment that allow for next-generation sequencing of numerous genes in parallel. However, it is not clear if these panels offer advantages over traditional genetic testing. We investigated the number of cancer predisposition gene mutations identified by parallel sequencing in individuals with suspected Lynch syndrome. METHODS: We performed germline analysis with a 25-gene, next-generation sequencing panel using DNA from 1260 individuals who underwent clinical genetic testing for Lynch syndrome from 2012 through 2013. All patients had a history of Lynch syndrome-associated cancer and/or polyps. We classified all identified germline alterations for pathogenicity and calculated the frequencies of pathogenic mutations and variants of uncertain clinical significance (VUS). We also analyzed data on patients' personal and family history of cancer, including fulfillment of clinical guidelines for genetic testing. RESULTS: Of the 1260 patients, 1112 met National Comprehensive Cancer Network (NCCN) criteria for Lynch syndrome testing (88%; 95% confidence interval [CI], 86%-90%). Multigene panel testing identified 114 probands with Lynch syndrome mutations (9.0%; 95% CI, 7.6%À10.8%) and 71 with mutations in other cancer predisposition genes (5.6%; 95% CI, 4.4%À7.1%). Fifteen individuals had mutations in BRCA1 or BRCA2; 93% of these met the NCCN criteria for Lynch syndrome testing and 33% met NCCN criteria for BRCA1 and BRCA2 analysis (P ¼ .0017). An additional 9 individuals carried mutations in other genes linked to high lifetime risks of cancer (5 had mutations in APC, 3 had bi-allelic mutations in MUTYH, and 1 had a mutation in STK11); all of these patients met NCCN criteria for Lynch syndrome testing. A total of 479 individuals had 1 or more VUS (38%; 95% CI, 35%-41%). CONCLUSIONS: In individuals with suspected Lynch syndrome, multigene panel testing identified high-penetrance mutations in cancer predisposition genes, many of which were unexpected based on patients' histories. Parallel sequencing also detected a high number of potentially uninformative germline findings, including VUS.
Journal of the American College of Radiology : JACR, 2017
Despite the frequent statement that "most men die with prostate cancer, not of it," the... more Despite the frequent statement that "most men die with prostate cancer, not of it," the reality is that prostate cancer is second only to lung cancer as a cause of death from malignancy in American men. The primary goal during baseline evaluation of prostate cancer is disease characterization, that is, establishing disease presence, extent (local and distant), and aggressiveness. Prostate cancer is usually diagnosed after the finding of a suspicious serum prostate-specific antigen level or digital rectal examination. Tissue diagnosis may be obtained by transrectal ultrasound-guided biopsy or MRI-targeted biopsy. The latter requires a preliminary multiparametric MRI, which has emerged as a powerful and relatively accurate tool for the local evaluation of prostate cancer over the last few decades. Bone scintigraphy and CT are primarily used to detect bone and nodal metastases in patients found to have intermediate- or high-risk disease at biopsy. The American College of Radi...
Journal of the American College of Radiology, 2012
Because virtually all patients with colonic cancer will undergo some form of surgical therapy, th... more Because virtually all patients with colonic cancer will undergo some form of surgical therapy, the role of preoperative imaging is directed at determining the presence or absence of synchronous carcinomas or adenomas and local or distant metastases. In contrast, preoperative staging for rectal carcinoma has significant therapeutic implications and will direct the use of radiation therapy, surgical excision, or chemotherapy. CT of the chest, abdomen, and pelvis is recommended for the initial evaluation for the preoperative assessment of patients with colorectal carcinoma. Although the overall accuracy of CT varies directly with the stage of colorectal carcinoma, CT can accurately assess the presence of metastatic disease. MRI using endorectal coils can accurately assess the depth of bowel wall penetration of rectal carcinomas. Phased-array coils provide additional information about lymph node involvement. Adding diffusion-weighted imaging to conventional MRI yields better diagnostic accuracy than conventional MRI alone. Transrectal ultrasound can distinguish layers within the rectal wall and provides accurate assessment of the depth of tumor penetration and perirectal spread, and PET and PET/CT have been shown to alter therapy in almost one-third of patients with advanced primary rectal cancer. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.
Journal of the American College of Radiology, 2014
Although localized renal cell carcinoma can be effectively treated by surgery or ablative therapi... more Although localized renal cell carcinoma can be effectively treated by surgery or ablative therapies, local or distant metastatic recurrence after treatment is not uncommon. Because recurrent disease can be effectively treated, patient surveillance after treatment of renal cell carcinoma is very important. Surveillance protocols are generally based on the primary tumor's size, stage, and nuclear grade at the time of resection, as well as patterns of tumor recurrence, including where and when metastases occur. Various imaging modalities may be used in the evaluation of these patients. Literature on the indications and usefulness of these radiologic studies is reviewed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a wellestablished consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.
Pose control for physically simulated characters has typically been based on proportional-derivat... more Pose control for physically simulated characters has typically been based on proportional-derivative (PD) controllers. In this paper, we introduce a novel, analytical solution to the 2nd-order ordinary differential equation governing PD control. The analytic solution is tailored to the needs of pose control for animation, and provides significant improvement in the precision of control, particularly for simulated characters in dynamic conditions.
Bulletin of the American …, 2010
Current Filamentation Instability, CFI, is of central importance for the propagation of relativis... more Current Filamentation Instability, CFI, is of central importance for the propagation of relativistic electron beams in plasmas and could play an important role in the generation of magnetic fields and of radiation in the after-glow of gamma ray bursts and for energy transport in the fast-...
Precise control with proportional-derivative (PD) control generally requires stiffness. The propo... more Precise control with proportional-derivative (PD) control generally requires stiffness. The proposed method determines critically damped PD control trajectories that precisely obtain target position and velocity constraints for arbitrary initial conditions. An analytic solution provides the PD control parameters, thereby determining the required impedance. The resulting controller precisely interpolates the target state by solving the full boundary-value problem. Control parameters are time-invariant, and need only be recomputed if the system diverges from the computed trajectory due to unexpected forces or noise. The resulting method provides control with automatically determined compliance, yielding natural response to perturbation. NOMENCLATURE (θ(t), ω(t)) Position and velocity at time t m(t) Moment of inertia at time t (θ 0 , ω 0 , t 0) Initial state of the system at time t 0 (θ d , ω d , t d) Desired state for the target time t d τ (t) Computed control torque for time t k Computed stiffness of PD controller γ Computed damping of PD controller
Objective: Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditar... more Objective: Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary bowel cancer. Multiple generations are affected with colorectal cancer at relatively young age, between 25 and 45 years. We conducted this study to investigate the frequency of HNPCC in Pakistani population, due to the high incidence of colorectal cancer in younger Pakistani adults and prevalence of consanguinity in this region. Methodology: Ninety histopathologically confirmed colorectal cancer patients between 12-50 years and their families were interviewed using a detailed questionnaire. The questions about family history of colorectal cancer, history of other cancers, age at diagnosis and consanguinity were asked. The pedigrees were drawn for all families based on given information. To confirm cancers reported in relatives, hospital records were also reviewed. Amsterdam criteria were used to label a family as HNPCC. Results: Seventeen patients (18.9%) had one or more first or second degree relatives under age 50 years with colorectal cancers suggestive of HNPCC. Another 15 patients (16.7%) had first or second degree relatives with a family history of other extra-colonic cancers including ovarian, breast, endometrium, lung, parotid, brain and bladder cancer. Of these 30 patients (33.3%) reported that their parents were first degree cousins. Conclusion: High frequency of HNPCC was seen in Pakistani population; higher proportion of colorectal cancer in young Pakistanis, strong prevalence of consanguineous marriages could be important factors for HNPCC occurrence in Pakistan. However future studies with large sample size along with genetic testing and screening programmes are warranted.
Genetics Selection …, 2005
The aim of this study was to compare the variance component approach for QTL linkage mapping in h... more The aim of this study was to compare the variance component approach for QTL linkage mapping in half-sib designs to the simple regression method. Empirical power was determined by Monte Carlo simulation in granddaughter designs. The factors studied (base values in parentheses) included the number of sires (5) and sons per sire (80), ratio of QTL variance to total genetic variance (λ = 0.1), marker spacing (10 cM), and QTL allele frequency (0.5). A single bi-allelic QTL and six equally spaced markers with six alleles each were simulated. Empirical power using the regression method was 0.80, 0.92 and 0.98 for 5, 10, and 20 sires, respectively, versus 0.88, 0.98 and 0.99 using the variance component method. Power was 0.74, 0.80, 0.93, and 0.95 using regression versus 0.77, 0.88, 0.94, and 0.97 using the variance component method for QTL variance ratios (λ) of 0.05, 0.1, 0.2, and 0.3, respectively. Power was 0.79, 0.85, 0.80 and 0.87 using regression versus 0.80, 0.86, 0.88, and 0.85 using the variance component method for QTL allele frequencies of 0.1, 0.3, 0.5, and 0.8, respectively. The log 10 of type I error profiles were quite flat at close marker spacing (1 cM), confirming the inability to fine-map QTL by linkage analysis in half-sib designs. The variance component method showed slightly more potential than the regression method in QTL mapping. quantitative trait loci / QTL detection / half-sib design / power
Radiographics, 2010
Percutaneous cryoablation of renal tumors requires a number of important steps for success and re... more Percutaneous cryoablation of renal tumors requires a number of important steps for success and relies heavily on imaging for treatment planning, intraprocedural guidance and monitoring, detection of untreated tumor, and surveillance for disease progression. Imaging-guided percutaneous cryoablation has several advantages over laparoscopic cryoablation. In particular, computed tomography (CT) and magnetic resonance (MR) imaging allow global evaluation of the ablation zone and an accurate depiction of the treatment margin. Ultrasonography allows real-time guidance of probe placement but cannot help depict ice ball formation as accurately as CT or MR imaging. Multiphasic CT or MR imaging should be performed at structured intervals following ablation. Treated tumors are expected to decrease in size over time, and lesion growth and internal or nodular enhancement are suspicious for tumor recurrence or progression. Complications include probe site pain, hematoma, incomplete ablation, and recurrent tumor. Current limitations of percutaneous cryoablation include the inability to control hemorrhage without intraarterial access and a lack of long-term follow-up data. Nevertheless, percutaneous cryoablation is an effective choice for minimally invasive nephron-sparing treatment of renal tumors. ©
… 항공우주| 국내연구성과| IP …
In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing... more In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing Body model with internally blown flaps. The test was performed at the NASA Langley 14 x 22 Foot Subsonic Tunnel at low speeds. Off-body measurements were obtained with a ...
… 항공우주| 국내연구성과| IP …
In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing... more In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing Body model with internally blown flaps. The test was performed at the NASA Langley 14 x 22 Foot Subsonic Tunnel at low speeds. Off-body measurements were obtained with a ...
International Wound Journal, 2009