Learning curve of robotic rectal surgery using risk-adjusted cumulative summation: a 5-year institutional experience.

PURPOSE: Outline learning phases of robot-assisted laparoscopic surgery for rectal cancer and compare surgical and clinical outcomes between each phase of robot-assisted laparoscopic surgery and the mastery phase of conventional laparoscopic surgery. METHODS: From 2015 to 2020, 210 patients underwent rectal cancer surgery at Sendai Medical Center. We performed conventional laparoscopic surgery in 110 patients and, laparoscopic surgery in 100 patients. The learning curve was evaluated using the cumulative summation method, risk-adjusted cumulative summation method, and logistic regression analysis. RESULTS: The risk-adjusted cumulative summation learning curve was divided into three phases: phase 1 (cases 1-48), phase 2 (cases 49-80), and phase 3 (cases 81-100). Duration of hospital stay (13.1 days vs. 18.0 days, respectively; p = 0.016) and surgery (209.1 min vs. 249.5 min, respectively; p = 0.045) were significantly shorter in phase 3 of the robot-assisted laparoscopic surgery group than in the conventional laparoscopic surgery group. Blood loss volume was significantly lower in phase 1 of the robot-assisted laparoscopic surgery group than in the conventional laparoscopic surgery group (17.7 ml vs. 79.7 ml, respectively; p = 0.036). The International Prostate Symptom Score was significantly lower in the robot-assisted laparoscopic surgery group (p = 0.0131). CONCLUSIONS: Robot-assisted laparoscopic surgery for rectal cancer was safe and demonstrated better surgical and clinical outcomes, including a shorter hospital stay, less blood loss, and a shorter surgical duration, than conventional laparoscopic surgery. After experience with at least 80 cases, tactile familiarity can be acquired from visual information only (visual haptic feedback). CLINICAL TRIAL REGISTRATION: UMIN reference no. UMIN000019857.

Improvement and stabilization of optical hydrogen sensing ability of Au-Pd alloys.

Formation of metal hydrides is a signature chemical property of hydrogen and it can be leveraged to enact both storage and detection of this technologically important yet extremely volatile gas. Palladium shows particular promise as a hydrogen storage medium as well as a platform for creating rapid and reliable H2 optical sensor devices. Furthermore, alloying Pd with other noble metals provides a technologically simple yet powerful way of enacting control over the structural and catalytic properties of the resultant material. Similarly, in addition to alloying, different top-down and bottom-up Pd nanostructuring methods have been proposed and investigated specifically for creating optical H2 sensors. In this work it was determined that the hydrogen sensing ability of a series of Pd-Au alloy films could be improved by way of a hydrogen over exposure (HOE) treatment. Structural investigation showed that the HOE treatment, in addition to irreversibly altering the film morphology, results in a 1 to 2% expansion in the lattice constant of the metal. By combining a cyclic HOE treatment and alloy aging through annealing, the hydrogen detection sensitivity and response rates of Pd-Au films could be stabilized so that their performance would no longer be appreciably affected by repeated hydrogen uptake and release cycles. This work takes a further step towards routine all-optical detection of part-per-million level hydrogen gas concentrations in Pd-Au alloy films and discussion of ways to enhance response rates is provided.

A three-dimensional computed tomography angiography study of the anatomy of the accessory middle colic artery and implications for colorectal cancer surgery.

PURPOSE: In the present study, we focused on the accessory middle colic artery and aimed to increase the safety and curative value of colorectal cancer surgery by investigating the artery course and branching patterns. METHODS: We included 143 cases (mean age, 70.4 ± 11.2 years; 86 males) that had undergone surgery for neoplastic large intestinal lesions at the First Department of Surgery at Yamagata University Hospital between August 2015 and July 2018. We constructed three-dimensional (3D) computed tomography (CT) angiograms and fused them with reconstructions of the large intestines. We investigated the prevalence of the accessory middle colic artery, the variability of its origin, and the prevalence and anatomy of the arteries accompanying the inferior mesenteric vein at the same level as the origin of the inferior mesenteric artery. RESULTS: Accessory middle colic artery was observed in 48.9% (70/143) cases. This arose from the superior mesenteric artery in 47, from the inferior mesenteric artery in 21, and from the celiac artery in two cases. In 78.2% (112/143) cases, an artery accompanying the inferior mesenteric vein was present at the same level as the origin of the inferior mesenteric artery; this artery was the left colic artery in 92, the accessory middle colic artery in 11, and it divided and became the left colic artery and the accessory middle colic artery in 10 cases. CONCLUSION: 3D CT angiograms are useful for preoperative evaluation. Accessory middle colic arteries exist and were observed in 14.9% of cases.

Characteristics of Highly Sensitive Hydrogen Sensor Based on Pt-WO3/Si Microring Resonator.

Hydrogen gas has attracted attention as a new energy carrier, and simple but highly sensitive hydrogen sensors are required. We fabricated an optical hydrogen sensor based on a silicon microring resonator (MRR) with tungsten oxide (WO3) using a complementary metal-oxide-semiconductor (CMOS)-compatible process for the MRR and a sol-gel method for the WO3 layer and investigated its sensing characteristics at device temperatures of 5, 20, and 30 °C. At each temperature, a hydrogen concentration of as low as 0.1 vol% was successfully detected. The gas sensitivity increased with decreasing temperature. The dependence of the sensitivity on the device temperature can be attributed to the thickness of tungsten bronze (HxWO3) formed by WO3 during exposure to hydrogen gas. In addition, a hydrogen gas sensor based on a silicon-MRR-enhanced Mach-Zehnder interferometer (MRR-MZI) is proposed and its significantly high sensing ability using improved changes in the transmittance of light is theoretically discussed.

Optical readout of hydrogen storage in films of Au and Pd.

For hydrogen sensor and storage applications, films of Au and Pd were (i) co-sputtered at different rates or (ii) deposited in a sequentially alternating fashion to create a layered structure on a cover glass. Peculiarities of hydrogen uptake and release were optically monitored using 1.3 µm wavelength light. Increase of optical transmission was observed for hydrogenated Pd-rich films of 10-30 nm thickness. Up to a three times slower hydrogen release took place as compared with the hydrogen uptake. Compositional ratio of Au:Pd and thermal treatment of films provided control over the optical extinction changes and hydrogen uptake/release time constants. Higher uptake and release rates were observed in the annealed Au:Pd films as compared to those deposited at room temperature and were faster for the Auricher films. Three main parameters relevant for sensors: sensitivity, selectivity, stability (reproducibility) are discussed together with the hydrogenation mechanism in Au:Pd alloys.

[Compliance with FOLFOX4 for Stage III colon cancer in the adjuvant setting].

AIMS: The usefulness of oxaliplatin(L-OHP)as adjuvant chemotherapy for Stage III colon cancer has been shown in clinical trials, such as the MOSAIC trial. The Leucovorin, fluorouracil, and oxaliplatin(FOLFOX)regimen has been recommended as adjuvant chemotherapy for colorectal cancer in Japan. In the MOSAIC trial, 74.7% of patients completed all planned treatment cycles. Neurological toxicity caused byL -OHP is one of the factors for discontinuing treatment. Therefore, we planned to administer FOLFOX4 as postoperative adjuvant chemotherapy and evaluated the safety and feasibility of this regimen. METHODS: From November 2009, 13 patients with Stage III colon cancer who had undergone complete resection of a primary tumor were enrolled. Patients received 4 cycles of FOLFOX4, followed by 4 cycles of the simplified fluorouracil and Leucovorin (LV5FU2)regimen and 4 additional cycles of FOLFOX4(12 cycles in total). RESULTS: Thirteen patients were treated with our FOLFOX4 regimen. In total, 11 patients(84.6%)completed all 12 planned treatment cycles. The median L-OHP dose per patient was 560mg/m / 2(compared with the per-protocol 12-cycle dose of 680 mg/m2). Grade 1 neurological toxicity during treatment was reported in 10 patients(76.9%). Neurological toxicity was reduced during the 4 cycles without L-OHP. CONCLUSION: Our FOLFOX4 regimen showed reduced neurological toxicity compared to other trials and can be used safely.

Potential urinary function benefits of initial robotic surgery for rectal cancer in the introductory phase.

We aimed to evaluate the advantages and disadvantages of initial robotic surgery for rectal cancer in the introduction phase. This study retrospectively evaluated patients who underwent initial robotic surgery (n = 36) vs. patients who underwent conventional laparoscopic surgery (n = 95) for rectal cancer. We compared the clinical and pathological characteristics of patients using a propensity score analysis and clarified short-term outcomes, urinary function, and sexual function at the time of robotic surgery introduction. The mean surgical duration was longer in the robot-assisted laparoscopy group compared with the conventional laparoscopy group (288.4 vs. 245.2 min, respectively; p = 0.051). With lateral pelvic lymph node dissection, no significant difference was observed in surgical duration (508.0 min for robot-assisted laparoscopy vs. 480.4 min for conventional laparoscopy; p = 0.595). The length of postoperative hospital stay was significantly shorter in the robot-assisted laparoscopy group compared with the conventional laparoscopy group (15 days vs. 13.0 days, respectively; p = 0.026). Conversion to open surgery was not necessary in either group. The International Prostate Symptom Score was significantly lower in the robot-assisted laparoscopy group compared with the conventional laparoscopy group. Moderate-to-severe symptoms were more frequently observed in the conventional laparoscopy group compared with the robot-assisted laparoscopy group (p = 0.051). Robotic surgery is safe and could improve functional disorder after rectal cancer surgery in the introduction phase. This may depend on the surgeon's experience in performing robotic surgery and strictly confined criteria in Japan.

Laparoscopic Proctocolectomy With Transanal Total Mesorectal Excision for Ulcerative Colitis.

Transanal total mesorectal excision (TaTME) refers to endoscopic retrograde total mesorectal excision and is becoming increasingly popular worldwide. TaTME improves surgical manipulation and minimizes the risk of local recurrence of rectal cancer by ensuring circumferential resection margins. TaTME is mainly indicated for patients in whom transabdominal approaches are expected to be technically challenging. We extended the indications for TaTME to include surgery for ulcerative colitis lesions that might be cancerous in the rectum. Here, we report a case of proctocolectomy with TaTME for ulcerative colitis. A 38-year-old woman who was receiving treatment for ulcerative colitis underwent a biopsy for random samples from the transverse colon to the rectum. Histopathological findings revealed noninvasive dysplasia with p53 overexpression, suggestive of cancer. We extended the indication of TaTME to surgery for ulcerative colitis. We formed two surgical teams and performed laparoscopic proctocolectomy with TaTME simultaneously. This simultaneous operation reduced the duration of the procedures in the present case. The patient was discharged without any complications and underwent loop ileostomy closure four months postoperatively. The patient recovered without significant loss of the anal sphincter function and is doing well four months after the second surgery. We propose laparoscopic proctocolectomy with TaTME to be conducted simultaneously by two teams as a safe and effective technique that is associated with a shorter operation time than that reported previously. Additionally, TaTME was useful in confirming the appropriate dissection layer as well as in surgical manipulation. Hence, TaTME could serve as a useful therapeutic option for ulcerative colitis surgery.

A Novel Assessment of Factor VIII Activity by Template Matching Utilizing Weighted Average Parameters from Comprehensive Clot Waveform Analysis.

BACKGROUND: Activated partial thromboplastin time (aPTT)-based clot waveform analysis is used to evaluate the comprehensive dynamics of fibrin clot formation. In addition, the technique can be usefully utilized for the rapid assessment of factor (F)VIII procoagulant activity in various clinical settings in patients with hemophilia A (HA). We defined a novel algorithm based on the weighted average parameters from aPTT-based waveforms to devise a template-matching procedure for assessing FVIII activity (FVIII:C). METHODS: The first derivatives of original clot waveforms triggered by the aPTT reagent (Coagpia APTT-N) were used to determine weighted averages of areas surrounded by the waveform at different percentages of maximum height in various clotting factor-deficient plasmas. Prepared templates based on 50 weighted average-related parameters were compared with 78 aPTT-prolonged plasmas. RESULTS: Original nonsmoothed waveforms of the various clotting factor-deficient plasmas with prolonged aPTTs demonstrated a variety of shapes. The weighted averages were calculated after adjustments for different baselines, and the patterns seemed to be governed by the specific clotting factor deficiency. The weighted average-related parameters including baseline wedge (r 2 = 0.998) and aspect ratio (r 2 = 0.998) were highly correlated with FVIII:C levels. Template-matching analyses based on weighted average-related waveform parameters obtained from 158 samples demonstrated that the sensitivity was 97.2% and specificity was 83.3% in aPTT-prolonged plasmas (n = 78). CONCLUSION: This novel algorithm based on weighted averages of aPTT-based waveforms together with template-matching may support clinical usefulness for judging of HA and may aid clinical management in the patients in the absence of specific clotting factor assays.

Transanal total mesorectal excision and transabdominal robotic surgery for rectal cancer: A retrospective study.

BACKGROUND: Transabdominal robotic surgery and transanal total mesorectal excision (TaTME) are newly introduced strategies for rectal cancer. These procedures might have many advantages in rectal cancer treatment in terms of improving oncological and functional outcomes, especially in cases involving advanced cancer or technical difficulty. In the present study, we aimed to clarify the advantages and disadvantages of transabdominal robotic surgery and laparoscopic TaTME as a hybrid surgery for rectal cancer. MATERIALS AND METHODS: We retrospectively evaluated six patients who underwent hybrid surgery for rectal cancer from August 2018 to April 2020. Both clinical and pathological outcomes were assessed. RESULTS: Two patients showed circumferential margin involvement both before and after neoadjuvant therapy. Three patients were planned to undergo hybrid surgery with intersphincteric resection because of a narrow pelvis. One patient was planned to undergo hybrid surgery for a giant tumor of >10 cm. The median length of hospitalization was 17 days. No patients required conversion to an open procedure. All patients underwent formation of defunctioning ileostomies. Two patients had a stapled anastomosis and four had a hand-sewn coloanal anastomosis. Complications included one case of anastomotic leakage, which was managed conservatively with ultrasound- and computed tomography-guided drainage and antibiotics. Histological analysis revealed that all specimens had a negative radial margin and distal margin. The median number of lymph nodes harvested was 17.5. Two patients showed extensive lymph node metastases, including lateral node metastasis. CONCLUSION: Hybrid surgery was performed safely and may improve oncological outcomes for rectal cancer. This technique has many potential benefits and would be alternative option in multimodal strategies for rectal cancer.

Undifferentiated carcinoma of the transverse colon with rhabdoid features that developed during treatment of non-small cell lung carcinoma with pembrolizumab: a case report.

BACKGROUND: Undifferentiated carcinoma of the colon is rare, and its prognosis is very poor. We report a case of undifferentiated carcinoma of the colon with rhabdoid features developed during treatment of non-small lung carcinoma (NSCLC) with pembrolizumab. CASE PRESENTATION: A 58-year-old man was diagnosed with transverse colon cancer during chemotherapy with pembrolizumab for NSCLC. Laparoscopic right hemicolectomy was performed. The histopathological diagnosis was undifferentiated carcinoma with rhabdoid features and lymph node metastasis. Immunohistochemically, programmed death ligand 1 (PD-L1) showed positivity. The microsatellite instability (MSI) status was low. He continued to receive pembrolizumab for NSCLC, and there have been no signs of colon cancer recurrence and progression of NSCLC for 15 months. CONCLUSION: We present the case of an undifferentiated carcinoma of the transverse colon with rhabdoid features. The development of the tumor with the expression of PD-L1 during pembrolizumab might have been associated with the low MSI.

Metamaterial for Hydrogen Sensing.

A hydrogen sensor based on plasmonic metasurfaces is demonstrated to exhibit the industry-required 10 s reaction time and sensitivity. It consists of a layer of either Y or WO3 sandwiched between a top Pd nanodisk and a Au mirror at the base. The phase change layer (Y, WO3) reacts with hydrogen, and the corresponding change of the refractive index (permittivity) is detected by the spectral shift of the resonance dip in reflectance at the IR spectral window. This direct reflectance readout of the permittivity change due to hydrogen uptake is fast and is facilitated by radiation field enhancement extending into the phase change volume. Numerical modeling was used to elucidate the effects that real and imaginary parts of the refractive index exert on the spectral shifts of resonance. The mechanism of sensor performance is outlined, and a possibility to tune its spectral range of operation by the diameter of the Pd nanodisk and thickness of the phase change material makes this design applicable to other molecular detection applications including surface-enhanced IR absorption.

Electrophysiological abnormalities of spatial attention in adults with autism during the gap overlap task.

OBJECTIVE: We evaluated event-related potentials (ERPs) elicited by attentional disengagement in individuals with autism. METHODS: Sixteen adults with autism, 17 adults with mental retardation and 14 healthy adults participated in this study. We recorded the pre-saccade positive ERPs during the gap overlap task under which a peripheral stimulus was presented subsequent to a stimulus in the central visual field. Under the overlap condition, the central stimulus remained during the presentation of the peripheral stimulus and therefore participants need to disengage their attention intentionally in order to execute the saccade to the peripheral stimulus due to the preservation of the central stimulus. RESULTS: The autism group elicited significantly higher pre-saccadic positivity during a period of 100-70 ms prior to the saccade onset than the other groups only under the overlap condition. The higher amplitude of pre-saccadic positivity in the overlap condition was significantly correlated with more severe clinical symptoms within the autism group. CONCLUSIONS: These results demonstrate electrophysiological abnormalities of disengagement during visuospatial attention in adults with autism which cannot be attributed to their IQs. SIGNIFICANCE: We suggest that adults with autism have deficits in attentional disengagement and the physiological substrates underlying deficits in autism and mental retardation are different.

Differential topographic pattern of EEG coherence between simultaneous and successive coding tasks.

The concept of two types of information coding, simultaneous and successive processing, is now well supported by extensive studies with factor analysis. However, few EEG evidence on processing types have been reported. In the present study we investigated whether varying demands on simultaneous or successive processing are reflected by different pattern of EEG coherence change from the passive condition to the active condition. We computed EEG coherence during simultaneous and successive processing tasks in both passive and active conditions. Under the passive condition, participants were just to perceive the presented stimuli. In the active condition, participants were required to remember the presented stimuli and then reproduce or recognize the remembered stimuli. Our result revealed the different topographic patterns of coherence change from the passive to the active condition between the simultaneous and the successive task. In the successive processing task, bilateral frontal-left temporal coherence in beta showed a significant decrease during the active condition, supporting Luria's model of the two information coding types. The condition effect of coherence in the simultaneous processing task was rather unclear. Our data also indicated that more task related cognitive processes, rather than the task-independent processes such as attentional demand, were reflected in EEG coherence of higher frequency bands. The different EEG coherence patterns seen in the simultaneous and successive tasks suggested the first step evidence that EEG coherence pattern may differentiate two distinctive types of information coding.

Validation of the 2012 Fukuoka Consensus Guideline for Intraductal Papillary Mucinous Neoplasm of the Pancreas From a Single Institution Experience.

OBJECTIVES: The 2012 Fukuoka consensus guideline has stratified the risks of malignant intraductal papillary mucinous neoplasm (IPMN) of the pancreas into "high-risk stigmata" (HRS) and "worrisome feature" (WF). This study aimed to evaluate its clinical validity based on a single institution experience. METHODS: Eighty-nine patients who underwent surgical resection with pathological diagnosis of IPMN were retrospectively studied. RESULTS: High-risk stigmata was significantly correlated with the prevalence of malignant IPMN as compared with WF. The positive predictive values of HRS and WF were 66.7% and 35.7% for branch duct IPMN and 80% and 38.1% for main duct IPMN, respectively. Univariate analysis indicated that all the factors in HRS and WF had statistical significance. Whereas multivariate analysis revealed only enhanced solid component (odds ratio [OR], 50.01; P = 0.008), presence of mural nodule (OR, 73.83; P < 0.001) and lymphadenopathy (OR, 20.85; P = 0.03) were independent predictors. Scoring HRS and WF by different numbers of positive factors resulted in improved predictive value. The area under the curve of HRS score was significantly lower than that of WF or HRS + WF score (0.680 vs 0.900 or 0.902, respectively; P < 0.001). CONCLUSIONS: As supplementary to the 2012 Fukuoka guideline, we suggest that calculating scores of WF and HRS may have superior diagnostic accuracy in predicting malignant IPMN.

Potentiation of radioimmunotherapy with response-selective peptide agonist of human C5a.

UNLABELLED: Physiologic barriers to the delivery of macromolecules to solid tumors are a major obstacle to the clinical success of radioimmunotherapy (RIT). Only a small fraction of the injected dose of the radiolabeled monoclonal antibody (mAb) localizes at the tumor site. This situation worsens as the tumor burden increases. It is hypothesized that improvements to RIT of adenocarcinoma can be realized by inclusion of vasoactive agents, in particular agents able to increase the vascular permeability of tumor capillaries. In these studies, a response-selective peptide agonist of human C5a, GCGYSFKPMPLaR (AP), was used to transiently increase tumor vascular permeability in an effort to improve RIT of solid tumors. METHODS: Athymic mice xenografted with human colorectal adenocarcinoma LS174T were treated intravenously with low doses (9.25 MBq) of 131I-labeled mAb B72.3 in combination with various intravenous doses of AP. The progression of the disease or the loss of >20% body weight was taken as the endpoint. Biodistribution and tumor uptake kinetics were studied in the same tumor-antibody system. RESULTS: The uptake of 125I-B72.3 in LS174T xenografts increased in a dose-dependent manner with an apparent maximal effect between 3 and 6 h after intravenous administration of AP. Augmenting the dose of 9.25 MBq 131I-B72.3 with a single administration of 0.1 mg AP delayed tumor growth nearly 2-fold; the tumor quadrupling time (T(q)) was 14.2 +/- 3.3 d for 131I-B72.3 alone versus 26.0 +/- 3.6 d for 131I-B72.3 plus 0.1 mg AP (P < 0.001). An additional dose of 0.1 mg AP 24 h after 131I-B72.3 further improved the therapeutic outcome (T(q) = 48.5 +/- 7.9 d; P < 0.001) and resulted in several cases of tumor regression. CONCLUSION: The inclusion of agonist peptides of human C5a in the RIT scheme results in improved tumor responses without any manifest side effects.

Developmental change of neurocognitive motor behavior in a continuous performance test with different interstimulus intervals.

OBJECTIVE: We investigated the neurocognitive process of motor control using event-related potentials during a cued continuous performance test with different interstimulus intervals in healthy children, and examined their neurocognitive process in motor execution and in motor inhibition. METHODS: Twenty-eight children group by age (9 years n=8, 11 years n=9, 13 years n=11) and 10 adults participated. In cued continuous performance test, subjects were asked to press a button when '9' appeared immediately after '1.' To maintain uncertainty in the stimulus series, we used 3 interstimulus intervals between the warning stimulus and subsequent target (800 ms, 1500 ms, 3000 ms). RESULTS: Effects of different interstimulus intervals were observed in the reaction time of hits regardless of the age of the subject. In adults, spatial distribution of the P3 component elicited by targets was centro-parietal maximum that was discriminable from the distribution of No-go P3, which was characterized by centro-parietal dominant distribution under all interstimulus interval (ISI) conditions. However, in younger children (9 years), the P3 component elicited by No-go distributed to the centro-frontal area, and P2/N2 with a significant anterior negative/posterior positive distribution was observed. As age increased, the dominant distribution of No-go P3 shifted significantly to a more anterior area compared with that of Target P3, and significantly prolonged ISI brought No-go P3 with centro-frontal dominant distribution that might indicate motor inhibition. CONCLUSIONS: These results indicated that behavioral change in the developmental course might be concerned with automatization of orientation and evaluation of stimulus relevance. Furthermore, efficient motor control might be enabled by establishment of an inhibitory process in the anterior area, in addition to an executive process in the posterior area.

[A case of recurrent breast cancer with lung metastasis and overexpression of HER2 that responded to UFT and cyclophosphamide combination therapy after sequential treatments with epirubicin, taxanes, and trastuzumab].

We describe a 57-year-old woman who underwent modified mastectomy for right breast cancer (T2N0M0) with overexpression of HER2, in whom lung metastasis developed 3 years after operation. She received sequential chemotherapy, including epirubicin plus cyclophosphamide, docetaxel, paclitaxel and trastuzumab, but the lung lesion progressed after transiently showing a partial response. Oral treatment with UFT and cyclophosphamide was begun as fifth-line treatment. The lung tumor shrank after 2 months, and a partial response has been maintained during continued treatment with UFT and cyclophosphamide. No adverse effects have occurred. We regard combination therapy with oral UFT and cyclophosphamide to be useful for the management of metastatic breast cancer, even in heavily pretreated cases with overexpression of HER2.

Speech perception in noise deficits in Japanese children with reading difficulties: effects of presentation rate.

We examined the effects of presentation rate on speech perception in noise and its relation to reading in 117 typically developing (TD) children and 10 children with reading difficulties (RD) in Japan. Responses in a speech perception task were measured for speed, accuracy, and stability in two conditions that varied stimulus presentation rate: high rate and same rate conditions. TD children exhibited significantly more stable responses in the high rate condition than they did in the same rate condition. Multiple regression analyses indicated that response stability in the high rate condition accounted for a unique amount of variance in reading and mora deletion. As a group, children with RD performed less accurately than did TD children in the high rate condition, but not in the same rate condition. Findings suggest that the dependence of speech perception on stimulus context relates to reading proficiency or difficulty in Japanese children. The influences of phonology and orthography of language on the relationships between speech perception and reading are discussed.