A key-point based real-time tracking of lung tumor in x-ray image sequence by using difference of Gaussians filtering and optical flow.

In radiation therapy, for accurate radiation dose delivery to a target tumor and reduction of the extra exposure of normal tissues, real-time tumor tracking is typically an important technique in lung cancer treatment since lung tumors move with patients' respiration. To observe a tumor motion in real time, x-ray fluoroscopic devices can be employed, and various tracking techniques have been proposed to track tumors. However, development of a fast and accurate tracking method for clinical use is still a challenging task since the obscured image of the tumor can cause decreased tracking accuracy and can result in additional processing time for remedying the accuracy. In this study, a new key-point-based tumor tracking method, which is sufficiently fast and accurate, is presented. Given an x-ray image sequence, the proposed method employs a difference-of-Gaussians filtering technique to detect key points in the tumor region of the first frame which are robust against noise and outliers in the subsequent frames. In the subsequent frames, these key points are tracked using a fast optical flow technique, and tumor motion is estimated via their movement. To evaluate the performance, the proposed method has been tested on several clinical kV and MV x-ray image sequences. The experimental results showed that the average of the root mean square errors of tracking were [Formula: see text] and [Formula: see text] for kV and MV x-ray image sequences, respectively. This tracking performance was more accurate than previous tracking methods. In addition, the average processing times for each frame were [Formula: see text] and [Formula: see text] for kV and MV image sequences, respectively, and the proposed method was faster than previous methods as well as shorter than frame acquisition interval. Therefore, the proposed method has the potential for both highly accurate and fast tumor tracking in clinical applications.

SU-D-BRA-02: An Extended Time-Variant Seasonal Autoregressive Model-Based Prediction for Irregular Breathing Motion Tracking.

PURPOSE: Real-time tumor position/shape measurement and dynamic beam tracking techniques allow accurate and continuous irradiation to moving tumor, but there can be a delay of several hundred milliseconds between observation and irradiation. A time-variant seasonal autoregressive (TVSAR) model has been proposed for compensating the delay by predicting respiratory tumor motion with sub-millimeter accuracy for a second latency. This is the-state-of-the-art model for almost regular breathing prediction so far. In this study, we propose an extended prediction method based on TVSAR to be usable for various breathing patterns, by predicting the residual component obtained from conventional TVSAR. METHODS: An essential core of the method is to take into account the residual component that is not predictable by only TVSAR. The residual component involves baseline shift, amplitude variation, and so on. In this study, the time series of the residual obtained for every new sample are predicted by using autoregressive (AR) model. The order and parameters of the AR model is adaptively determined for each residual component by using an information criterion. Eleven data sets of 3-D lung tumor motion, observed at Georgetown University Hospital by using Cyberknife Synchrony system, were used for evaluation of the prediction performance. RESULTS: Experimental results indicated that the proposed method is superior to those of conventional and the state-of-the-art methods for 0 to 1 s ahead prediction. The average prediction error of the proposed method was 0.920 plus/minus 0.348 mm for 0.5 s forward prediction. CONCLUSION: We have developed the new prediction method based on TVSAR model with adaptive residual prediction. The new method can predict various respiratory motions including not only regular but also a variety of irregular breathing patterns and thus can compensate the bad effect of the delay in dynamic irradiation system for moving tumor tracking. A part of this work has been financially supported by Varian Medical Systems Inc., Palo Alto, CA and Japan Society for the Promotion of Science (JSPS), Japan.

SU-E-J-135: 3-D Fourier-Based Volumetric Registration for Estimating Intra-Fractional Lung Tumor Motion.

PURPOSE: To develop a three-dimensional (3-D) volumetric registration algorithm to estimate the intra-fractional lung tumor motion between respiratory phases for improving the accuracy of radiotherapy treatment. METHODS: The 3-D thoracic CT volumes (512×512×160 voxels, with dimensions 0.97×0.97×2.5 mm3 ) in different respiratory phases were acquired on a General Electric Optima T580 scanner in cine mode. As a preprocess, a bicubic interpolation was used to interpolate the original 3-D volumes along the cephalo-caudal axis to volumes of size 512×512×400 voxels, with dimensions 0.97×0.97×1 mm3 . In each respiratory phase, a sub-volume covering the tumor was roughly specified manually. A 3-D phase correlation of two sub-volumes was computed by using the 3-D inverse Fourier transformation of the normalized cross power spectrum of two sub-volumes. The 3-D displacements along three axes were estimated by finding the location of the highest peak in the 3-D phase correlation. RESULTS: Experiments were conducted on an artificial 4-D CT data set and three clinical 4-D CT data sets. Experimental results shown that the proposed algorithm was capable of estimating the tumor motion between respiratory phases with a high-accuracy (mean square error <1 mm). CONCLUSIONS: This work extended the conventional image registration techniques from 2-D to 3-D for tumor motion estimation. This work indicates a potential for significant accuracy improvement in radiotherapy treatment planning. The high-accurate 3-D tumor motion information provides a reliable basis for expanding a clinical target volume (CTV) to a planning target volume (PTV) to incorporate the intra-fractional tumor motion.

Involvement of Rho kinase in the pathogenesis of acute pulmonary embolism-induced polystyrene microspheres in rats.

Acute pulmonary embolism (PE) is a life-threatening disease, and several vasoconstrictors, including endothelin-1 (ET-1), play a key role in vasoconstriction and hypoxemia during the development of PE. Rho kinase is activated by various vasoconstrictors resulting in vascular contraction and remodeling. Recent evidence has revealed an important role of Rho kinase in the pathogenesis of systemic and pulmonary vascular diseases. However, contribution of Rho kinase in PE remains unclear. We thus investigated the role of Rho kinase in the PE rat model induced by intrajugular administration of polystyrene microspheres (mean diameter, 26 microm). At 6 h following the administration of microspheres (1.5 ml/kg), right ventricular systolic pressure (RVSP) was higher in the PE than in the control rats (15.8 +/- 1.6 vs. 32.9 +/- 7.5 mmHg). Arterial oxygen tension was lower (92.3 +/- 12.5 vs. 66.0 +/- 17.7 Torr), and alveolar-arterial difference in oxygen partial pressure was higher (3.9 +/- 3.8 vs. 36.5 +/- 26.9 Torr) in the PE rats. Western blotting analysis revealed upregulation and downregulation in expression of vascular cell adhesion molecule-1 and endothelial nitric oxide synthase in lungs from the PE rats, respectively, and radioimmunoassay demonstrated an increase in plasma ET-1 levels. Lung Rho kinase alpha expression was greater in the PE rats. At 5 h following administration of microspheres (0.75 ml/kg), intravenous Rho kinase inhibitors HA1077 and Y27632 (3 mg/kg each) attenuated elevation of RVSP (22.0 +/- 3.7, 17.1 +/- 3.2, 14.3 +/- 2.6 mmHg, PE, PE+HA1077, PE+Y27632) and the severity of hypoxemia (66.3 +/- 16.2, 94.9 +/- 23.0, 89.1 +/- 8.5 Torr, PE, PE+HA1077, PE+Y27632) in the PE rats. These results suggest that pulmonary endothelial dysfunction and activation of Rho kinase may contribute to the potentiation of vasoconstriction and hypoxemia in the PE rats.

RASSF2, a potential tumour suppressor, is silenced by CpG island hypermethylation in gastric cancer.

RASSF2, a member of the RASSF1 family, has recently been identified as a potential tumour suppressor. We examined methylation status in multiple regions which included the CpG island and spanned the transcription start site of RASSF2 in 10 gastric cancer cell lines, as well as 78 primary gastric cancers and corresponding non-neoplastic gastric epithelia. Hypermethylation of RASSF2 in at least one of the regions examined was detected in seven (70%) of the 10 cell lines; two (20%) exhibited hypermethylation in all the regions examined including the transcription start site and lost expression of RASSF2 mRNA, which could, however, be restored by 5-aza-2' deoxycytidine treatment, while the other five (50%) cell lines exhibited hypermethylation at the 5'- and/or 3'- edge, with four of them expressing RASSF2 mRNA. In primary gastric cancers and corresponding non-neoplastic gastric epithelia, frequencies of RASSF2 methylation ranged from 29% (23 out of 78) to 79% (62 out of 78) and 3% (two out of 78) to 60% (47 out of 78), respectively, at different CpG sites examined. Methylation was frequently observed at the 5'- and 3'- edges, and became less frequent near the transcription start site in both the primary gastric cancers and corresponding non-neoplastic gastric epithelia. Hypermethylation near the transcription start site was mostly cancer-specific. We thus showed that RASSF2 is silenced by hypermethylation near the transcription start site in gastric cancer. Hypermethylation was found initially to occur at the 5'- and 3'- furthest regions of the CpG island in non-neoplastic gastric epithelia, to gradually spreads near the transcription start site to shut down RASSF2 expression, and ultimately to constitute a field-defect placing tissue increased risk for development of gastric cancer.

Electrophysiologic effects of an antiarrhythmic agent, bidisomide, on sodium current in isolated rat ventricular myocytes: comparison with mexiletine and disopyramide.

The effects of bidisomide, an antiarrhythmic agent, on sodium current (I(Na)) in isolated rat ventricular myocytes were investigated using a whole cell voltage clamp method. Bidisomide blocked I(Na) with a Ki of 214 microM at a holding potential of -140 mV. The blockade of I(Na) was enhanced at a less negative holding potential of -100 mV with a Ki of 21 microM. Bidisomide shifted the steady state inactivation curve to a negative potential direction by 20 mV without a significant change in the slope factor. Bidisomide slowed the time course of recovery of I(Na) at a holding potential of -140 mV with a slow recovery phase. The time constant of recovery phase for bidisomide, disopyramide and mexiletine were 2703, 1858 and 757 ms, respectively. The development of the block of I(Na) consisted of two phases in the presence of bidisomide. The fast and slow time constants were 11 and 648 ms. Bidisomide produced a use-dependent block of I(Na) when the depolarizing pulse was repeated at 1-3 Hz. Our results indicate that bidisomide binds to rat cardiac sodium channels and that the dissociation kinetics of bidisomide from the inactivated sodium channel is slower than that of disopyramide.

Both alpha(1A)- and alpha(1B)-adrenergic receptor subtypes couple to the transient outward current (I(To)) in rat ventricular myocytes.

1. Regulation of transient outward current (I(To)) by alpha(1)-adrenergic (alpha(1)AR) plays a key role in cardiac repolarization. alpha(1)ARs comprise a heterogeneous family; two natively expressed subtypes (alpha(1A) and alpha(1B)) and three cloned subtypes (alpha(1a), alpha(1b) and alpha(1d)) can be distinguished. We have examined the electrophysiological role of each alpha(1)AR subtype in regulating I(To) in isolated rat ventricular myocytes. 2. Reverse transcription-PCR study revealed the presence of three subtype mRNAs (alpha(1a), alpha(1b) and alpha(1d)) in rat myocytes. 3. Radioligand binding assay using [(125)I]-HEAT showed that the inhibition curves for alpha(1A)AR-selective antagonists (WB4101, 5-methylurapidil, (+)-niguldipine and KMD-3213) in rat ventricles best fit a two-site model, with 30% high and 70% low affinity binding sites. The high affinity sites were resistant to 100 microM chloroethylclonidine (CEC), while the low affinity sites were highly inactivated by CEC. 4. Whole cell voltage clamp study revealed that methoxamine reduced a 4-aminopyridine(4-AP)-sensitive component of I(To) in the isolated rat ventricle myocytes. Lower concentrations of KMD-3213 (1 nM) or 5-MU (10 nM) did not affect the methoxamine-induced reduction of I(To). On the other hand, CEC treatment (100 microM) of isolated myocytes reduced the methoxamine-induced reduction of I(To) by 46%, and the remaining response was abolished by lower concentrations of KMD-3213 or 5-MU. 5. The results indicate that rat ventricular myocytes express transcripts of the three alpha(1)AR subtypes (alpha(1a), alpha(1b) and alpha(1d)); however, two pharmacologically distinct alpha(1)AR subtypes (alpha(1A) and alpha(1B)) are predominating in receptor populations, with approximately 30% alpha(1A)AR and 70% alpha(1B)AR. Although both alpha(1A) and alpha(1B)AR subtypes are coupled to the cardiac I(To), alpha(1B)ARs predominantly mediate alpha(1)AR-induced effect.

The anti-ischemic effects of CP-060S during pacing-induced ischemia in anesthetized dogs.

CP-060 S, (-)-( S)-2-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-3-[3-[N-methyl-N-[2-(3 ,4-methylenedioxyphenoxy)ethyl]-amino]propyl]-1,3-thiazolidin++ +-4-one hydrogen fumarate, is a novel cardioprotective drug which prevents Na+-, Ca2+-overload and has Ca2+ channel blocking activity. We compared the anti-ischemic effects of CP-060S with those of diltiazem, a Ca2+ channel blocker, and R56865, N-[1-[4-(4-fluorophenoxy)butyl]-4-piperidinyl]-N-methyl-2-benzothiazo lamine, a Na+-, Ca2+-overload inhibitor, in a canine pacing-induced ischemia model. CP-060S 100 microg kg(-1) significantly suppressed the pacing-induced ischemic epicardial ST-segment elevation by maximally 75%, while diltiazem 100 microg kg(-1) suppressed it by maximally 35%. R56865 100 microg kg(-1) significantly suppressed the ST-segment elevation by maximally 30%. In addition, diltiazem 100 microg kg(-1) caused synergistic suppression of ST-segment elevation by 70% when administered simultaneously with R56865 100 microg kg(-1). These results suggest that a Na+-, Ca2+-overload preventive action and a Ca2+ channel blocking action independently contribute to the suppression of the ST-segment elevation. Therefore, CP-060S may suppress pacing-induced ST-segment elevation by a dual action by preventing Na+-, Ca2+-overload and the Ca2+ channel blockade.

A particle-receptor model for the insulin-induced closure of connexin43 channels.

Connexin43(Cx43) channels can be regulated by a variety of factors, including low pHi. Structure/function studies from this laboratory have demonstrated that pH gating follows a particle-receptor mechanism, similar to the "ball-and-chain" model of voltage-dependent inactivation of ion channels. The question whether the particle-receptor model is applicable only to pH gating or to other forms of Cx43 regulation as well remains. To address this question, we looked at the uncoupling effects of insulin and of insulin-like growth factor-1 (IGF) on Cx43 channels expressed in Xenopus oocytes. These agonists do not induce changes in pHi. Junctional conductance (Gj) was measured by the dual 2-electrode voltage-clamp technique. Control studies showed that relative Gj did not change spontaneously as a function of time. Continuous exposure of Cx43-expressing oocytes to insulin (10 micro/L) led to a decrease in Gj. After 80 minutes, Gj was 54+/-5% from control (n= 12). Exposure of oocytes to IGF (10 nmol/L) caused an even more pronounced change in Gj (37+/-4% of control, n=6). The time course of the IGF-induced uncoupling was similar to that observed after insulin exposure. The effect of insulin was abolished by truncation of the carboxyl-terminal domain of Cx43 at amino acid 257 (M257). Interestingly, as in the case of pH gating, coexpression of the carboxyl-terminal domain (amino acids 258 to 282) together with M257 rescued the ability of insulin to reduce coupling (Gj, 39+/-12% from control; n=6). Structure/function experiments using various deletion mutants of the carboxyl-terminal domain showed that insulin treatment does not modify Gj if amino acids 261 to 280 are missing from the Cx43 sequence. Our results suggest that a particle-receptor (or ball-and-chain) mechanism, similar to that described for pH gating, also applies to chemical regulation of Cx43 by other factors.

Purification and properties of rabbit muscle proteasome, and its effect on myofibrillar structure.

This paper describes the purification and properties of a multicatalytic proteinase complex, proteasome, from rabbit skeletal muscle, and its effect on myofibrillar structure. The purified proteasome gave a single band on polyacrylamide gel electrophoresis under non-denaturing conditions and gave eight bands under denaturing conditions, indicating that this enzyme comprises multiple hetero-subunits with low molecular mass. The purified proteasome was not activated by ATP and ubiquitin, and was markedly inhibited by Z-Leu-Leu-Leu-H (aldehyde). These data indicate that the purified proteasome is not 26S, but 20S. The proteasome degraded synthetic peptides maximally at pH 8.0. Relative to pH 8.0, activities were gradually decreased with the lowering of pH, but the degree of decrease was substrate-dependent, and the activity at pH 5.0 still retained about 30~60% of the activity at pH 8.0, indicating the possibility that the proteasome is active in the muscle during conditioning. When the proteasome was heated at 60 °C for 20 min and treated in the presence of 0.005% SDS, the activity increased over 1.5 and 4.5 times, respectively. SDS remarkably increased the V(max) value of the enzyme at pH 8.0. The proteasome was also activated by high hydrostatic pressure up to 100~150 M Pa and gradually decreased at 200 MPa or higher. Electron microscopic observation revealed that obvious gaps between filamentous structure, the complete loss of M-line and partial loss of Z-line structure were caused by proteasome.

Flow cytometry analysis of alpha1-adrenoceptor subtypes.

To characterize the alpha1-adrenoceptor subtypes, we developed a flow cytometry method using the fluorescent ligand BODIPY-FL prazosin and the anti-peptide antibody against the alpha1b-adrenoceptor amino terminus (designated 1B-N1-C) as probes. Three alpha1-adrenoceptors (alpha1a, alpha1b and alpha1d) expressed in CHO cells were detected by BODIPY-FL prazosin; however, only alpha1b-adrenoceptor subtype was detected by the anti-peptide antibody 1B-N1-C. Furthermore, the flow cytometry analysis with 1B-N1-C specifically identified alpha1b-adrenoceptor in native cells of hamster DDT1-MF2 cells, rat hepatocytes and cardiomyocytes.

Levels of calpain and calpastatin in meat subjected to high pressure.

The levels of µ-, m-calpain and calpastatin were assayed in pressurized rabbit muscle. The crude calpain level from the pressurized muscle at 100 MPa was almost the same with that of control. Above 100 MPa, the level of calpain decreased rapidly with increased pressure. At 300 MPa, the calpain level was almost inactivated. When the crude extract was pressurized, the calpain level followed the same tendency as that in the pressurized muscle. When the extracts from control or pressurized muscle were subjected to DEAE-Sephacel column chromatography, µ- and m-calpains and calpastatin lost their activity with increasing pressure, but the degree of loss was different for each. Calpains resisted changes in pressurization at 200 MPa and were inactivated over 200 MPa. Inactivation of calpastatin at 100 MPa was faster than that of calpains. From the results, it was concluded that calpain levels remained in muscle pressurized up to 200 MPa, whereas calpastatin levels were decreased by the pressurization. Thus the total activities of calpains in pressurized muscle appear to have been increased by the pressure treatment and this may result in tenderization of meat.

Effects of high pressure treatment on the flavour-related components in meat.

This paper describes the effects of high-pressure treatment on the water-soluble components of meat responsible for the flavor of meat. The amounts of peptides and amino acids as estimated by phenol reagent positive materials (PPM) apparently increased with increasing pressure applied to the muscle up to 300 MPa, but the differences between each treatment were not statistically significant. When the muscles were stored at 2°C for 7 days after the pressurization, increases in the amount of PPM were observed both in untreated and pressurized muscles. Apparently the contents of serine, glutamic acid, glutamine, glycine and alanine gradually increased in the extracts from pressurized muscle as the pressure increased up to 200 MPa, and some of them, especially glutamine and alanine, tended to decrease in the muscle pressurized at 300 MPa. When the muscles were stored for 7 days after the pressurization, apparent increases of the contents of aspartic acid, serine, proline, alanine and lysine were observed in the extracts both from untreated and pressurized muscles. However, significant differences were not observed in the contents of each amino acid between each treatment. The content of inosinic acid, which is considered to contribute to the 'umani' taste of the meat, was not reduced by the pressurization. High performance liquid chromatograph (HPLC) of soluble peptides revealed no significant changes in any fraction from the pressurized muscles up to 200 MPa and a significant decrease of the peptide fraction (approx. molecular weight 500) from the muscle pressurized at 300 and 400 MPa. When the muscles were stored after pressurization, significant increases in the peptide fraction of molecular weight 300 and the amino acid fraction, and a decrease of the peptide fraction of molecular weight 3000 were observed in the extracts both from the untreated and pressurized muscles. From the results, it is suggested that high-pressure treatment on the post mortem muscle causes almost the same changes in the components responsible for the flavor of meat as those observed in conditioned muscle.

Effects of high pressure treatment on the proteolytic enzymes in meat.

This paper describes the effects of high-pressure treatment on proteolytic enzymes in muscle, especially catheptic enzymes which influence meat tenderization, and on acid phosphatase, used as an index of disruption of lysosomal membranes. Acid phosphatase activity in the extract from pressurized muscle increased with increasing pressure applied to the muscle up to 500 MPa. Activity of cathepsin B, D and L increased up to 400 MPa, then tended to decrease at 500 MPa. Cathepsin H and aminopeptidase B decreased with the increasing pressure. Measurements of enzymic activity in the pressurized crude extract, to investigate the pressure effect on the enzymes themselves, showed that all enzymes studied in this paper lost their enzymic activity as applied pressure increased. When the pressurized extracts were subjected to the gel-filtration chromatography, a decrease in the activities of cathepsin H and aminopeptidase B and an increase in the activities of cathepsins B and L and acid phosphatase were observed. It seems that the decrease in activity of the enzymes eluted early from the column (cathepsin H and aminopeptidase B) is due to decrease in the amount of protein eluted by the pressure treatment, whereas the increase in activity of the enzymes eluted late (cathepsin B, L and acid phosphatase) is due to an increase in the amount of protein eluted. From the results, it was concluded that the pressure-induced increase in the amount of protease activity in the muscle was due to the release of the enzymes from lysosomes.

Long-term complications of dialysis: pathogenic factors with special reference to amyloidosis.

Amyloidosis, caused by amyloid containing beta 2-microglobulin (beta 2m), is a frequent complication of long-term hemodialysis. The precise mechanism of its pathogenesis is not known. While beta 2m is an amyloid protein, other factors likely are involved in the pathogenesis of such amyloidosis. In treating patients with dialysis-related amyloidosis, it is essential to remove as much beta 2m from the blood as possible. In this respect, progress has been made in developing a column to adsorb beta 2m from the blood. Using a combination of a high-flux dialyzer and an adsorption column, it becomes possible to efficiently eliminate beta 2m. We have treated four patients with this column in combination with a high-flux dialyzer three times a week for periods of one month or one year. The absorbent column eliminates beta 2m from the blood, and may thus halt or slow the progression of beta 2m-related amyloidosis. However, such treatment is still in a preliminary phase; long-term studies are required to determine clinical efficacy.