SU-E-J-69: Development of an Ambiguity-Free Optical Tracking System for SBRT

PURPOSE

Commercial optical tracking system such as BrainLab ExacTrac© suffers from ambiguous markers which can cause significant delay in patient treatment. We developed an ambiguity-free optical tracking system for high precision SBRT.

METHODS

The optical tracking system consists of a pair of camera sensors, 4∼8 infra-red (IR) reflective markers affixed on patient skin and in-house developed software. We developed an effective algorithm to automatically eliminate ambiguous markers. A recursive backtracking algorithm was developed to build one-to-one correspondence between reference markers and optical markers. The algorithm was able to deal with missing, misplaced, or occluded markers by introducing 'dummy' markers. Isocenter displacements were calculated in six-degree of freedom through rigid-body registration between reference markers and optical markers. The system accuracy was evaluated with a pelvis phantom against cone beam CT (CBCT) and ExacTrac. The impact of number of markers on tracking accuracy was also evaluated. The performance of automatic ambiguity elimination was assessed with synthetic and clinic marker patterns.

RESULTS

Difference of isocenter displacement reported by our system and commercial systems (CBCT, ExacTrac) were within 0.5 mm/0.1o. Impact of number of markers on tracking accuracy in our phantom test was negligible with isocenter displacement varying within 0.2 mm/0.2o when number of markers varied from 4 to 8. The system successfully identified and eliminated ambiguous markers in both synthetic and clinic marker patterns.

CONCLUSIONS

An accurate optical tracking system free of ambiguous markers was developed for patient positioning and monitoring in high precision SBRT. The developed algorithms to eliminate ambiguous markers and to handle missing, misplaced or occluded markers were effective and efficient.

SU-D-BRCD-02: A Novel Cylindrical 3D Water Scanner for Beam Data Collection: I. Validation of the Automatic-Setup

PURPOSE

To determine the accuracy and reproducibility of the automatic- setup procedure of a 3D water scanner (3D SCANNER, Sun Nuclear Corp). The procedure automatically aligns the scanner's coordinate system to the Linac coordinate system. A unique off-center detector holder extends the scan range to 630 mm, eliminating the need for scanner shifts for large-field scans.

METHODS

The automatic-setup procedure provides means to automatically (1) level the tank; (2) zero the detector position to water surface; (3) align the scanner's coordinate system to the Linac system; and (4) correct motor hysteresis. After automatic-setup, (1) and (2) were evaluated visually by three physicists. Step (3) was tested by moving one of the jaws to the isocenter and scans were made along the jaw edge. Angular misalignment between the scanner and the Linac would Result in a noticeably tilted profile. Step (4) was tested by scanning with the chamber moving forward and then backward five times. The accuracy of the off-center detector holder was tested by comparing scans made using the regularand the off-center detector holders. All tests were repeated three times.

RESULTS

All tests of the water surface and horizontal chamber movementwere acceptable from the nine independent evaluations. Scans along the jawedge resulted in < 1% in profile tilt, corresponding to < 0.05 degree in angular misalignment. Same direction scans resulted in field edge differences < 0.05 mm, and < 0.2 mm when compared to scans in thereverse direction. There was no difference in accuracy when different scan speeds were used. Profiles obtained using the regular and the off-centerdetector holders were identical.

CONCLUSIONS

The automatic-setupprocedure resulted in accurate alignment of the 3D SCANNER to the Linac. These results were user-independent. It also provides the ability to scan large fields without the need to change tank setup. This work was partially supported by a research grant from Sun Nuclear Corp., Melbourne, FL.

NUR77 inhibits the expression of TIMP2 and increases the migration and invasion of HTR-8/SVneo cells induced by CYR61

OBJECTIVE

To investigate the function and mechanism of CYR61 on the migration and invasion of the trophoblast cell line, HTR-8/SVneo cells.

STUDY DESIGN

The mRNA and protein levels of NUR77 in the placentas of normal and preeclampsia (PE) women were evaluated using real-time PCR and Western blot, respectively. Paraffin-embedded tissues were processed for localization of NUR77 protein in placental villus by immunohistochemistry. HTR-8/SVneo cells were cultured in the presence of CYR61, Ad-NUR77 or a small interfering RNA for NUR77 (Ad-sinur77). The expression of NUR77 in the HTR-8/SVneo cells was detected and the effects of CYR61 on the migration and invasion of HTR-8/SVneo cells were assessed in wound-healing and transwell experiments, respectively. Gelatin zymography was used to measure the MMP2 release in HTR-8/SVneo cells.

RESULTS

NUR77 is significantly decreased in the placenta of women with PE compared with the levels during a normal pregnancy. CYR61 can significantly increase the expression of NUR77 in HTR-8/SVneo cells. CYR61, as well as NUR77, can promote HTR-8/SVneo cells migration and invasion, which can be blocked by Ad-sinur77. Both CYR61 and Ad-nur77 reduced the mRNA expression of TIMP2 in HTR-8/SVneo cells.

CONCLUSIONS

CYR61 may promote HTR-8/SVneo cells migration and invasion through the upregulation of NUR77, leading to the increase of MMP2 release and the downregulation of TIMP2 expression.

A prototype of an anchoring and extending intestinal micro-robot and an in vitro experiment

In order to minimize the invasiveness of intestinal disease diagnosis and surgery, we propose an anchoring and extending micro-robot. The gait of the micro-robot was designed according to the biomechanical features of the intestinal tract. The locomotion condition showed that the anchoring capability and extending ability should be balanced to enhance locomotion efficiency. The mechanical and control system was designed and fabricated under the requirements of the locomotive model. The assembled micro-robot was 90 mm in length and 13 mm in diameter. The micro-robot prototype was tested in in vitro experiments; its locomotion efficiency was approximately 100% in an ideal environment, but around 50% in a pig's small bowel (20 mm in diameter). The in vitro experiment results demonstrated that the gait is feasible for locomotion in the small bowel although the diameter of the small bowel is a limiting factor.

MiR-135a functions as a selective killer of malignant glioma

Glioma is the most common and fatal primary brain tumor. Thus far, therapeutic strategies to efficiently and specifically antagonize glioma are limited and poorly developed. Here we report that glia-enriched miR-135a, a microRNA that is dramatically downregulated in malignant glioma and correlated with the pathological grading, is capable of inducing mitochondria-dependent apoptosis of malignant glioma by regulating various genes including STAT6, SMAD5 and BMPR2, as well as affecting the signaling pathway downstream. Moreover, this lethal effect is selectively towards malignant glioma cells, but not neurons and glial cells, through a novel mechanism. Our findings suggest an important role of miR-135a in glioma etiology and provide a potential candidate for malignant glioma therapy.

The clinical values of methylation status of P16 and APC genes in bile in diagnosis of malignant obstructive jaundice

171

Background: Preoperative definitive diagnosis of malignant obstructive jaundice caused by biliary and pancreatic carcinomas still remains a major challenge. Hypermethylation of tumor suppressor genes have been implied in carcinogenesis of biliary and pancreatic malignancies. The diagnostic values of methylation status of tumor suppressor genes in bile in malignant obstructive jaundice have not been well-documented.

Methods: Bile was prospectively collected from 70 patients with obstructive jaundice treated at our hospital between November 2008 and Sepetember 2009. Forty-eight of them were proved to be malignant obstructive jaundice (biliary carcinoma in 36, pancreatic carcinoma in 8 and duodenal carcinoma in 4) by pathological examination, and 22 were benign obstructive jaundice caused by cholelithiasis. DNA was extracted from bile and modified by sodium bisulfite. Methylation-specific PCR was run to detect methylation status of P16 and APC gene promoters. Their diagnostic values in malignant obstructive jaundice were assessed.

Results: Hypermethylation of P16 promoter was presented in 72.9% (35/48) malignant obstructive jaundice, and 9% (2/22) bengin obstructive jaundice (p<0.05). Hypermethylation of APC promoter was presented in 56.2% (27/48) malignant obstructive jaundice, and 9% (2/22) bengin obstructive jaundice (p<0.05). With respect to their diagnostic values in malignant obstructive jaundice, sensitivity, specificity, positive predictivity and negative predictivity were 72.9%, 90.9%, 94.6% and 60.6%, respectively, for P16 gene; 56.2%, 90.9%, 93.1%, 48.8%, respectively, for APC gene.

Conclusions: Methylation status of P16 and APC gene promoters in bile was valuable in diagnosis of malignant obstructive jaundice, with an excellent specificity. P16 gene had a higher sensitivity than APC gene.

No significant financial relationships to disclose.

First Report of Bituminaria Witches'-Broom in Australia Caused by a 16SrII Phytoplasma

Bituminaria bituminosa (L.) Stirt. is a perennial legume known as Arabian pea that is used as a forage in arid areas and for stabilization of degraded soils. It is widely distributed in the Mediterranean Basin with wider adaptation across the Canary Islands (4). In July 2010, during a survey for phytoplasma, some Canary Island B. bituminosa plants with typical phytoplasma symptoms, including stunted growth with small leaves, shortened internodes, and bushy growth, were found in seed multiplication nurseries at Medina, Perth, Western Australia (115°48.5'E; 32°13.2'S). Two samples from plants with clear disease symptoms and two visibly healthy plants were collected and total DNA was extracted with the Illustra DNA extraction kit Phytopure (GE Healthcare) according to the manufacturer's instructions. Direct and nested PCR were used to test the presence of phytoplasma 16S rDNA in samples with universal primers P1/P7 and R16F2n/R16R2, respectively (1,3). The PCR amplifications from all diseased samples yielded an expected product of 1.8 kb by direct and 1.2 kb by nested PCR, but not from the healthy plant samples. The direct PCR product was used as a template DNA in sequencing and the DNA sequence was deposited in the NCBI GenBank (Accession No. HQ404357). Sequence homology analysis indicated there was a perfect match between the two isolates. BLAST search of the NCBI GenBank revealed that B. bituminosa phytoplasma shares >99% sequence identity with Crotalaria witches'-broom phytoplasma (Accession No. EU650181.1), pear decline phytoplasma (Accession No. EF656453.1), and Scaevola witches'-broom phytoplasma (Accession No. AB257291.1). On the basis of BLAST analyses of 16S rRNA gene sequences, B. bituminosa phytoplasma in Western Australia appears to belong to the peanut witches'-broom group (16SrII-D) of phytoplasma. Restriction fragment length polymorphism analysis was also performed on nested PCR products of two samples of B. bituminosa phytoplasma by separate digestion with HaeIII, Hind6I, HpaII, MboI, RsaI, Tru9I, and T-HB8I restriction enzymes. Samples yielded patterns similar to alfalfa witches'-broom phytoplasma (Accession No. AF438413) belonging to subgroup 16SrII-D (2). To our knowledge, this is the first report of a phytoplasma of the 16SrII-D group infecting B. bituminosa in Australia and should be referred to as "Bituminaria witches'-broom phytoplasma" (BiWB). This report also indicates that the occurrence of the phytoplasma in B. bituminosa may be widespread in the Canary Islands and other species of Bituminaria might be susceptible to infection by Bituminaria witches'-broom phytoplasma. References: (1) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (2) A. J. Khan et al. Phytopathology 92:1038, 2002. (3) I.-M. Lee et al. Int. J. Syst. Evol. Microbiol. 54:337, 2004. (4) P. Mendez et al. Grassland Sci. Eur. 11:300, 2006.

BP neural network classification for bleeding detection in wireless capsule endoscopy

Bleeding in the digestive tract is one of the most common gastrointestinal tract (GI) diseases, as well as the complication of some fatal diseases. Wireless capsule endoscopy (WCE) allows physicians to noninvasively examine the entire GI tract. However it is very laborious and time-consuming to inspect large numbers of WCE images, which limits the wider application of WCE. It is therefore important to develop an automatic and intelligent computer-aided bleeding detection technique. In this paper, a new method aimed at bleeding detection in WCE images is proposed. Colour texture features distinguishing the bleeding regions from non-bleeding regions are extracted in RGB and HSI colour spaces; then a neural network using the colour texture features as the feature vector inputs is designed to recognize the bleeding regions. The experiments demonstrate that the bleeding regions can be correctly recognized and clearly marked out. The sensitivity of the algorithm is 93% and the specificity is 96%.

A micro creeping robot for colonoscopy based on the earthworm

Minimally Invasive Surgery (MIS) has become one of the most important research areas in the field of medical engineering. Robotic colonoscopy is a typical medical procedure that complies with the requirements of MIS. In this paper, a new novel miniature robot for intestinal inspection based on the earthworm is described; its diameter and length are 7.5 mm and 120 mm respectively. The micro robot is driven by a DC motor which has good performance and sufficient power. In this paper the structure and locomotion mechanism of this robot are introduced; the mechanical model is built; and simulation is carried out. The control system and software design are also discussed in detail. Some actuating characteristic experiments have been performed, where the micro robot creeps in declining rubber tubes. The experimental results are in accord with simulation results, and show that this kind of robot can move reliably in horizontal and certain declining tubes. This research has laid a foundation for the application of the miniature robot endoscope.

A novel c.545-546insG mutation in the loricrin gene correlates with a heterogeneous phenotype of loricrin keratoderma

BACKGROUND

Loricrin keratoderma (LK) is a group of congenital skin abnormalities characterized by the common features of honeycomb palmoplantar keratoderma and diffused ichthyosiform dermatosis. Earlier studies have shown that LK is associated with genetic defects of the loricrin gene.

OBJECTIVES

To determine the correlation between a loricrin mutation and a heterogeneous phenotype of loricrin keratoderma.

METHODS

We obtained DNA samples from a large family in which affected members showed more severe hyperkeratosis on the dorsal parts of their hands, mild palmoplantar keratoderma with no honeycomb-like manifestations and generalized ichthyosis. Screening of the loricrin gene was performed by direct sequencing of the entire coding region. Plasmids encoding the green fluorescent protein-tagged human loricrin were constructed and transferred to 293A cells for subcellular localization analyses.

RESULTS

Molecular analyses of the loricrin gene identified a novel insertion mutation c.545-546insG that resulted in a frameshift after codon 182. This mutation was predicted to produce a mutant protein with a frameshift of its C-terminal sequence of amino acids that embeds a newly generated nuclear localization signal (NLS), and to be 22 amino acids longer than the wild-type protein due to a delayed termination codon. The NLSs appear to result in an accumulation of mutant loricrin within nuclei.

CONCLUSIONS

Our results extend the repertoire of loricrin mutations underlying LK, provide further evidence that heterogeneous phenotypes of LK may be the result of genetic heterogeneity of loricrin mutations, and demonstrate that nuclear accumulation of mutant loricrin is due to the nuclear targeting sequences in the mutant C-terminus.

Genetic analysis of pod and seed resistance to pea weevil in a Pisum sativum×P. fulvum interspecific cross

Interspecific populations derived from crossing cultivated field pea, Pisum sativum, with the wild pea relative, Pisum fulvum, were scored for pod and seed injury caused by the pea weevil, Bruchus pisorum. Pod resistance was quantitatively inherited in the F2 population, with evidence of transgressive segregation. Heritability of pod resistance between F2 and F3 generations was very low, suggesting that this trait would be difficult to transfer in a breeding program. Seed resistance was determined for the F2 population by testing F3 seed tissues of individual F2 plants and pooling data from seed reaction for each F2 plant (inferred F2 genotype). Segregation for seed resistance in the F2 population of the cross Pennant/ATC113 showed a trigenic mode of inheritance, with additive effects and dominant epistasis towards susceptibility. Seed resistance was conserved over consecutive generations (F2 to F5) and successfully transferred to a new population by backcross introgression. Seed resistance in the backcross introgressed population segregated in a 63 : 1 ratio, supporting the three-gene inheritance model. It is proposed that complete resistance to pea weevil is controlled by three major recessive alleles assigned pwr1, pwr2, and pwr3, and complete susceptibility by three major dominant alleles assigned PWR1, PWR2, and PWR3. It is recommended that large populations (>300 F2 plants) would be required to effectively transfer these recessive alleles to current field pea cultivars through hybridisation and repeated backcrossing.

Enhancement of genetic diversity in canola-quality Brassica napus and B. juncea by interspecific hybridisation

Reciprocal crosses were made between Brassica napus cv. Mystic (canola) and B. juncea JN29 (near canola quality). The F1 hybrids were selfed and backcrossed in all possible combinations to parent plants. The greatest number of selfed fertile progeny were obtained when Mystic was the maternal parent, and its F1 was most successful in backcrosses to Mystic or JN29 as maternal or paternal parent. The predominant morphological type of fertile progeny was B. napus, but several B. juncea morphological types occurred in F2 and BC1-derived lines. F2 : 3 and BC1S0 : 1 progeny showed transgressive segregation for agronomic and seed quality traits in two contrasting field environments. Several of the B. juncea-type progeny had improved seed quality (lower total seed glucosinolates and higher % oleic acid) over the B. juncea parent. Selfing of interspecific hybrids between canola-quality B. napus and B. juncea has the potential to greatly enhance genetic diversity in canola-quality progeny of both species, without the loss of donor alleles that normally occurs with repeated backcrossing.

Noninvasive measurement of phenylalanine by iontophoretic extraction in patients with phenylketonuria

Phenylketonuria is an autosomal recessive disorder characterized by elevated concentrations of phenylalanine. Elevated phenylalanine concentrations can impair intellectual functions and the disease is treated with a lifelong diet and frequent monitoring of plasma phenylalanine concentrations. Previous in vitro studies have demonstrated the feasibility of iontophoretically enhanced transdermal transport of phenylalanine. Here we evaluate the feasibility of transdermal iontophoretic extraction of phenylalanine in vivo. Phenylalanine was iontophoretically extracted from the skin of healthy volunteers and of patients with phenylketonuria for up to 6 h and concentrations were compared with those measured in plasma. The amount of phenylalanine iontophoretically extracted from the skin declined over time, suggesting contribution of phenylalanine from the skin in the initial extraction. Phenylalanine iontophoretically extracted from skin correlated with plasma phenylalanine levels at plasma levels above 300 micromol/L. This correlation supports the feasibility of iontophoretic phenylalanine extraction for monitoring phenylketonuria.

Population genetics of Plasmodium resistance genes in Anopheles gambiae: no evidence for strong selection

Anopheles mosquitoes are the primary vectors for malaria in Africa, transmitting the disease to more than 100 million people annually. Recent functional studies have revealed mosquito genes that are crucial for Plasmodium development, but there is presently little understanding of which genes mediate vector competence in the wild, or evolve in response to parasite-mediated selection. Here, we use population genetic approaches to study the strength and mode of natural selection on a suite of mosquito immune system genes, CTL4, CTLMA2, LRIM1, and APL2 (LRRD7), which have been shown to affect Plasmodium development in functional studies. We sampled these genes from two African populations of An. gambiae s.s., along with several closely related species, and conclude that there is no evidence for either strong directional or balancing selection on these genes. We highlight a number of challenges that need to be met in order to apply population genetic tests for selection in Anopheles mosquitoes; in particular the dearth of suitable outgroup species and the potential difficulties that arise when working within a closely-related species complex.