Comprehensive workflow encompassing discovery, verification, and quantification of indicator peptide in snail mucin using LC-quadrupole Orbitrap high-resolution tandem mass spectrometry.

Peptidomics analysis was conducted using high-resolution tandem mass spectrometry (MS2) to determine the peptide profile of snail-derived mucin extract (SM). The study was also aimed to identify an indicator peptide and validate a quantification method for this peptide. The peptide profiling and identification were conducted using discovery-based peptidomics analysis employing data-dependent acquisition, whereas the selected peptides were verified and quantified using parallel reaction monitoring acquisition. Among the 16 identified peptides, the selected octapeptide (TEAPLNPK) was quantified via precursor ion ionization (m/z 435.2400), followed by quantification of the corresponding quantifier ion fragment (m/z 639.3824) using MS2. The quantification method was optimized and validated in terms of specificity, linearity, accuracy, precision, and limit of detection/quantification. The validated method accurately quantified the TEAPLNPK content in the SM as 7.5 ± 0.2 µg/g. Our study not only identifies an indicator peptide from SM but also introduces a novel validation method, involving precursor ion ionization and quantification of specific fragments. Our findings may serve as a comprehensive workflow for the monitoring, selection, and quantification of indicator peptides from diverse food resources.

Modulation of gut microbiota ecosystem by a glucan-rich snail mucin heteropolysaccharide attenuates loperamide-induced constipation.

The present study aimed to investigate the effect of oral administration of snail-derived mucin extract (SM) on ameliorating constipation symptoms of loperamide-induced constipated rats (n = 6). The analytical results indicated that SM mainly contains a glucan-rich snail mucin heteropolysaccharide with high molecular weights (108.5-267.9 kDa), comprising primarily of glucose (64.9 %) and galactose (22.4 %) with some deoxyhexoses (5.0 %) and hexosamines (4.9 %). Daily SM administration at doses of 10-40 mg/kg/day to the loperamide-induced constipated rats significantly (p < 0.05) ameliorated the deterioration in fecal parameters, such as numbers and weight of feces, fecal water contents, and gastrointestinal transit ratio. The histomorphometric results showed that the loperamide-induced decreases in the thickness of mucosal and muscularis mucosae layers as well as the distribution of mucin and c-KIT-positive areas were significantly (p < 0.05) improved via SM consumption at all doses tested. SM administration at all doses significantly increased the expression of genes encoding tryptophan hydroxylases (TPH1 and TPH2; p < 0.05), tight junction molecules (OCLN, CLDN1, and TJP1; p < 0.05), and mucin (MUC2 and MUC4; p < 0.05), but significantly decreased the aquaporin-encoding genes (AQP3 and AQP8; p < 0.05). Gut microbial community analysis indicated that SM administration could modulate loperamide-induced dysbiosis by increasing the phyla Actinobacteria (11.72-12.64 % at 10-40 mg/kg doses; p < 0.05) and Firmicutes (79.33 % and 74.24 % at 20 and 40 mg/kg doses; p < 0.05) and decreasing the phyla Bacteroidetes (5.98-12.47 % at 10-40 mg/kg doses; p < 0.05) and Verrucomicrobia (2.21 % and 2.78 % at 20 and 40 mg/kg doses; p < 0.05), suggesting that SM administration is effective in ameliorating constipation by controlling gut microbial communities. These findings can be utilized as fundamental data for developing novel functional materials using SM to prevent or treat constipation.

FeS2-incorporated 3D PCL scaffold improves new bone formation and neovascularization in a rat calvarial defect model.

199Three-dimensional (3D) scaffolds composed of various biomaterials, including metals, ceramics, and synthetic polymers, have been widely used to regenerate bone defects. However, these materials possess clear downsides, which prevent bone regeneration. Therefore, composite scaffolds have been developed to compensate these disadvantages and achieve synergetic effects. In this study, a naturally occurring biomineral, FeS2, was incorporated in PCL scaffolds to enhance the mechanical properties, which would in turn influence the biological characteristics. The composite scaffolds consisting of different weight fractions of FeS2 were 3D printed and compared to pure PCL scaffold. The surface roughness (5.77-fold) and the compressive strength (3.38-fold) of the PCL scaffold was remarkably enhanced in a dose-dependent manner. The in vivo results showed that the group with PCL/ FeS2 scaffold implanted had increased neovascularization and bone formation (2.9-fold). These results demonstrated that the FeS2 incorporated PCL scaffold might be an effective bioimplant for bone tissue regeneration.

Evaluation of Auricular Cartilage Reconstruction Using a 3-Dimensional Printed Biodegradable Scaffold and Autogenous Minced Auricular Cartilage.

Auricular cartilage reconstruction represents one of the greatest challenges for otolaryngology-head and neck surgery. The native structure and composition of the auricular cartilage can be achieved by combining a suitable chondrogenic cell source with an appropriate scaffold. In reconstructive surgery for cartilage tissue, autogenous cartilage is considered to be the best chondrogenic cell source. Polycaprolactone is mainly used as a tissue-engineered scaffold owing to its mechanical properties, miscibility with a large range of other polymers, and biodegradability. In this study, scaffolds with or without autogenous minced auricular cartilage were implanted bilaterally in rabbits for auricular regeneration. Six weeks (n = 4) and 16 weeks (n = 4) after implantation, real-time quantitative reverse transcription polymerase chain reaction and histology were used to assess the regeneration of the auricular cartilage. Quantitative reverse transcription polymerase chain reaction analysis revealed that the messenger RNA expression of aggrecan, collagen I, and collagen II was higher in scaffolds with 50% minced cartilage than the scaffold-only groups or scaffolds with 30% minced cartilage (P < 0.05). Furthermore, histological analysis demonstrated significantly superior cartilage regeneration in scaffolds with the minced cartilage group compared with the scaffold-only and control groups (P < 0.05). Autogenous cartilage can be easily obtained and loaded onto a scaffold to promote the presence of chondrogenic cells, allowing for an improvement of the reconstruction of auricular cartilage. Here, the regeneration of auricular cartilage was also successful in the 50% minced cartilage group. The results presented in this study could have clinical implications, as they demonstrate the potential of a 1-stage process for auricular reconstruction.

Restoration of the inferomedial orbital strut using a standardized three-dimensional printing implant.

The inferomedial orbital strut (IOS) is the thin bony junction of the orbital medial wall and floor. Its fracture is common and leads to serious complications, including enophthalmos, globe dystopia and diplopia. However, anatomical restoration of the IOS is challenging owing to reduced structural support; sound anatomical background and accurate implants are therefore essential. The aim of the present study was to incorporate data from cadaveric orbit anatomy into three-dimensional (3D) printing technology and to reconstruct the complex orbital fracture elaborately. After averaging the data from computed tomography (CT) images of 100 adult cadavers, the dimensions of the IOS were extracted, and a tangent sphere was created using a computer-aided design program. The curves were compared with the CT data of 10 adult patients from the simulation test. Based on these data, a standardized 3D implant, 1.15 mm thick, was designed using polycaprolactone. The implant was placed in five patients with complex orbital fractures. The radius of the sphere in contact with the orbit, measuring 33.54 mm, was confirmed to be appropriate. A comparison between the normal side volume (V0) and the postoperative volume (Vpost ) showed that they were statistically similar. Furthermore, a comparison between V0 and the preoperative volume (Vpre ), and Vpost compared with Vpre also showed a statistically significant difference (P < 0.05). On follow-up, the preoperative ocular symptoms were resolved. The orbital data obtained from 100 cadavers provided standardized orbital anatomy, and 3D printed implants were created. The implants were anatomically accurate with regard to the orbital cavity and adequately covered the simulation model. The implant also showed satisfactory results when applied clinically in actual patients.

Sensitivity Improvement of Urchin-Like ZnO Nanostructures Using Two-Dimensional Electron Gas in MgZnO/ZnO.

This paper introduces a strategy for improving the sensitivity of a gas sensor to NO2 gas. The gas sensor was fabricated using urchin-like ZnO nanostructures grown on MgO particles via vapor-phase growth and decorated with MgZnO nanoparticles via a sol-gel process. The urchin-like ZnO gas sensor decorated with MgZnO showed higher sensitivity to NO2 gas than a pristine urchin-like ZnO gas sensor. When ZnO and MgZnO form a heterojunction, a two-dimensional electron gas is generated. This improves the performance of the fabricated gas sensor. The growth morphology, atomic composition, and phase structure were confirmed through field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

Improved Sensitivity of α-Fe2O3 Nanoparticle-Decorated ZnO Nanowire Gas Sensor for CO.

A strategy for improving the sensitivity of a sensor for detecting CO and NH3 gases is presented herein. The gas sensor was fabricated from ZnO metal oxide semiconductor nanostructures grown via a vapor⁻liquid⁻solid process and decorated with α-Fe2O3 nanoparticles via a sol⁻gel process. The response was enhanced by the formation of an α-Fe2O3/ZnO n⁻n heterojunction and the growth of thinner wires. ZnO nanowires were grown on indium⁻tin⁻oxide glass electrodes using Sn as a catalyst for growth instead of Au. The structure and elemental composition were investigated using field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The gas sensing results indicate that the response value to 100 ppm CO was 18.8 at the optimum operating temperature of 300 °C.

Effects of dexamethasone and hydrocortisone on rocuroniuminduced neuromuscular blockade and reversal by sugammadex in phrenic nerve-hemidiaphragm rat model.

BACKGROUND: The facilitator effects of steroids on neuromuscular transmission may cause resistance to neuromuscular blocking agents. Additionally, steroids may hinder sugammadex reversal of neuromuscular blockade, but these findings remain controversial. Therefore, we explored the effect of dexamethasone and hydrocortisone on rocuronium-induced neuromuscular blockade and their inhibitory effect on sugammadex. METHODS: We explored the effects of steroids, dexamethasone and hydrocortisone, in vitro using a phrenic nerve-hemidiaphragm rat model. In the first phase, an effective dose of rocuronium was calculated, and in the second phase, following sugammadex administration, the recovery of the train-of-four (TOF) ratio and T1 was evaluated for 30 minutes, and the recovery index was calculated in dexamethasone 0, 0.5, 5, and 50 µg/ml, or hydrocortisone 0, 1, 10, or 100 µg/ml. RESULTS: No significant effect of steroids on the effective dose of rocuronium was observed. The TOF ratios at 30 minutes after sugammadex administration were decreased significantly only at high experimental concentrations of steroids: dexamethasone 50 µg/ml and hydrocortisone 100 µg/ml (P < 0.001 and P = 0.042, respectively). There were no statistical significances in other concentrations. No differences were observed in T1. Recovery index was significantly different only in 100 µg/ml of hydrocortisone (P = 0.03). CONCLUSIONS: Acute exposure to steroids did not resist the neuromuscular blockade caused by rocuronium. And inhibition of sugammadex reversal on rocuronium-induced neuromuscular blockade is unlikely at typical clinical doses of dexamethasone and also hydrocortisone. Conclusively, we can expect proper effects of rocuronium and sugammadex when dexamethasone or hydrocortisone is used during general anesthesia.

New clinical application of three-dimensional-printed polycaprolactone/ß-tricalcium phosphate scaffold as an alternative to allograft bone for limb-sparing surgery in a dog with distal radial osteosarcoma.

Limb-sparing surgery is one of the surgical options for dogs with distal radial osteosarcoma (OSA). This case report highlights the novel application of a three-dimensional (3D)-printed patient-specific polycaprolactone/ß-tricalcium phosphate (PCL/ß-TCP) scaffold in limb-sparing surgery in a dog with distal radial OSA. The outcomes evaluated included postoperative gait analysis, complications, local recurrence of tumor, metastasis, and survival time. Post-operative gait evaluation showed significant improvement in limb function, including increased weight distribution and decreased asymmetry. The implant remained well in place and increased bone opacity was observed between the host bone and the scaffold. There was no complication due to scaffold or surgery. Significant improvement in limb function and quality of life was noted postoperatively. Local recurrence and pulmonary metastasis were identified at 8 weeks postoperatively. The survival time from diagnosis of OSA to death was 190 days. The PCL/ß-TCP scaffold may be an effective alternative to cortical allograft in limb-sparing surgery for bone tumors.

Cleft Alveolus Reconstruction Using a Three-Dimensional Printed Bioresorbable Scaffold With Human Bone Marrow Cells.

Bone tissue engineering technology based on scaffold has been applied for cleft lip and palate treatment. However, clinical applications of patient-specific three-dimensional (3D) scaffolds have rarely been performed. In this study, a clinical case using patient-specific 3D-printed bioresorbable scaffold with bone marrow stromal cells collected from iliac crest in the operating room has been introduced. At 6-month after transplantation, the bone volume of the newly regenerated bone was approximately 45% of the total defect volume. Bone mineral density of the newly regenerated bone was about 75% compared to the surrounding bone. The Hounsfield unit value was higher than that of cancellous maxillary alveolar bone and lower than that of the cortical maxillary alveolar bone. Bone-marrow-derived mesenchymal stem cells-seeded 3D-printed patient-specific polycaprolactone scaffolds offer a promising alternative for alveolar cleft reconstruction and other bony defects.

Synergistic Effects of Beta Tri-Calcium Phosphate and Porcine-Derived Decellularized Bone Extracellular Matrix in 3D-Printed Polycaprolactone Scaffold on Bone Regeneration.

Bone-derived extracellular matrix (ECM) is widely used in studies on bone regeneration because of its ability to provide a microenvironment of native bone tissue. However, a hydrogel, which is a main type of ECM application, is limited to use for bone graft substitutes due to relative lack of mechanical properties. The present study aims to fabricate a scaffold for guiding effective bone regeneration. A polycaprolactone (PCL)/beta-tricalcium phosphate (ß-TCP)/bone decellularized extracellular matrix (dECM) scaffold capable of providing physical and physiological environment are fabricated using 3D printing technology and decoration method. PCL/ß-TCP/bone dECM scaffolds exhibit excellent cell seeding efficiency, proliferation, and early and late osteogenic differentiation capacity in vitro. In addition, outstanding results of bone regeneration are observed in PCL/ß-TCP/bone dECM scaffold group in the rabbit calvarial defect model in vivo. These results indicate that PCL/ß-TCP/bone dECM scaffolds have an outstanding potential as bone graft substitutes for effective bone regeneration.

Reconstruction of Complex Maxillary Defects Using Patient-specific 3D-printed Biodegradable Scaffolds.

Reconstruction of maxilla defects has remained one of the most challenging problems in craniomaxillofacial reconstruction because it typically requires harvesting and grafting of autologous bone, which poses limitations related to the difficulties in accurately reconstructing the defected bone and the highly prolonged duration of surgery. We employed tissue-engineered, patient-specific, 3-dimensional (3D)-printed biodegradable scaffolds for maxillofacial bone reconstruction in patients with complex maxillary defects after surgical removal of cancer. A customized polycaprolactone (PCL) scaffold was designed and fabricated for each patient. For this purpose, we used computer-aided design and manufacturing combined with 3D printing technology. The patients implanted with the PCL scaffolds were followed up for up to 2 years with careful evaluation of morphological changes in the face. We confirmed that the patient-specific 3D-printed PCL scaffold effectively filled the maxillary defect and promoted regeneration of the deficient tissue while remaining stable in the body for a relatively long period. Employing customized tissue-engineered scaffolds built using the patient's computed tomography data and an extrusion-based 3D printing system is safe and clinically feasible, helping create and maintain improved morphological features of the face, which represents the most important aspect from the perspective of the patients.

Development and Assessment of a 3D-Printed Scaffold with rhBMP-2 for an Implant Surgical Guide Stent and Bone Graft Material: A Pilot Animal Study.

In this study, a new concept of a 3D-printed scaffold was introduced for the accurate placement of an implant and the application of a recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded bone graft. This preliminary study was conducted using two adult beagles to evaluate the 3D-printed polycaprolactone (PCL)/ß-tricalcium phosphate (ß-TCP)/bone decellularized extracellular matrix (bdECM) scaffold conjugated with rhBMP-2 for the simultaneous use as an implant surgical guide stent and bone graft material that promotes new bone growth. Teeth were extracted from the mandible of the beagle model and scanned by computed tomography (CT) to fabricate a customized scaffold that would fit the bone defect. After positioning the implant guide scaffold, the implant was placed and rhBMP-2 was injected into the scaffold of the experimental group. The two beagles were sacrificed after three months. The specimen block was obtained and scanned by micro-CT. Histological analysis showed that the control and experimental groups had similar new bone volume (NBV, %) but the experimental group with BMP exhibited a significantly higher bone-to-implant contact ratio (BIC, %). Within the limitations of this preliminary study, a 3D-printed scaffold conjugated with rhBMP-2 can be used simultaneously as an implant surgical guide and a bone graft in a large bone defect site. Further large-scale studies will be needed to confirm these results.

Precise stacking of decellularized extracellular matrix based 3D cell-laden constructs by a 3D cell printing system equipped with heating modules.

Three-dimensional (3D) cell printing systems allow the controlled and precise deposition of multiple cells in 3D constructs. Hydrogel materials have been used extensively as printable bioinks owing to their ability to safely encapsulate living cells. However, hydrogel-based bioinks have drawbacks for cell printing, e.g. inappropriate crosslinking and liquid-like rheological properties, which hinder precise 3D shaping. Therefore, in this study, we investigated the influence of various factors (e.g. bioink concentration, viscosity, and extent of crosslinking) on cell printing and established a new 3D cell printing system equipped with heating modules for the precise stacking of decellularized extracellular matrix (dECM)-based 3D cell-laden constructs. Because the pH-adjusted bioink isolated from native tissue is safely gelled at 37 °C, our heating system facilitated the precise stacking of dECM bioinks by enabling simultaneous gelation during printing. We observed greater printability compared with that of a non-heating system. These results were confirmed by mechanical testing and 3D construct stacking analyses. We also confirmed that our heating system did not elicit negative effects, such as cell death, in the printed cells. Conclusively, these results hold promise for the application of 3D bioprinting to tissue engineering and drug development.

Effects of genistein supplementation on genome­wide DNA methylation and gene expression in patients with localized prostate cancer.

Epidemiological studies have shown that dietary compounds have significant effects on prostate carcinogenesis. Among dietary agents, genistein, the major isoflavone in soybean, is of particular interest because high consumption of soy products has been associated with a low incidence of prostate cancer, suggesting a preventive role of genistein in prostate cancer. In spite of numerous studies to understand the effects of genistein on prostate cancer, the mechanisms of action have not been fully elucidated. We investigated the differences in methylation and gene expression levels of prostate specimens from a clinical trial of genistein supplementation prior to prostatectomy using Illumina HumanMethylation450 and Illumina HumanHT-12 v4 Expression BeadChip Microarrays. The present study was a randomized, placebo-controlled, double-blind clinical trial on Norwegian patients who received 30 mg genistein or placebo capsules daily for 3-6 weeks before prostatectomy. Gene expression changes were validated by quantitative PCR (qPCR). Whole genome methylation and expression profiling identified differentially methylated sites and expressed genes between placebo and genistein groups. Differentially regulated genes were involved in developmental processes, stem cell markers, proliferation and transcriptional regulation. Enrichment analysis suggested overall reduction in MYC activity and increased PTEN activity in genistein-treated patients. These findings highlight the effects of genistein on global changes in gene expression in prostate cancer and its effects on molecular pathways involved in prostate tumorigenesis.

Cerebral/Peripheral Vascular Reactivity and Neurocognition in Middle-Age Athletes.

INTRODUCTION: Midlife vascular disease risk is associated with higher incidence of cognitive impairment in late life. Regular aerobic exercise improves vascular function, which in turn may translate into better cognitive function. The purpose of this study was to determine the associations among cardiorespiratory fitness, cerebral and peripheral vascular reactivity, and cognitive function in sedentary and endurance-trained middle-age adults. METHODS: Thirty-two endurance-trained and 27 healthy sedentary participants ages 43-65 yr underwent measurements of maximal oxygen uptake (VO2max), neurocognitive assessment, cerebrovascular reactivity to CO2 (CVR), and brachial artery flow-mediated dilation (FMD). RESULTS: There were no group differences in age, sex, education level, fasting blood glucose, and blood pressure. Compared with sedentary subjects, endurance-trained athletes demonstrated better cognitive performance on memory (z-score: -0.36 ± 1.11 vs 0.30 ± 0.76, P < 0.01), attention-executive function (z-score: -0.21 ± 0.53 vs 0.18 ± 0.72, P = 0.02), and total cognitive composite scores (z-score: -0.27 ± 0.63 vs 0.23 ± 0.57, P < 0.01). Furthermore, brachial FMD (4.70% ± 2.50% vs 7.13% ± 3.09%, P < 0.01) and CVR (4.19% ± 0.71%·mm Hg⁻¹ vs 4.69% ± 1.06%·mm Hg⁻¹, P = 0.052) were greater in endurance-trained individuals than in the sedentary subjects. Total cognitive composite scores showed a significant positive association with brachial FMD (r = 0.36, P < 0.01) and CVR (r = 0.30, P = 0.03). Finally, when brachial FMD and CVR were entered as covariates, fitness-related group differences in total cognitive composite score were significantly attenuated (all P > 0.05). CONCLUSION: Endurance-trained middle-age adults demonstrated better cognitive performance, which may, at least in part, be mediated by their enhanced vascular function, including cerebral and endothelial-dependent vascular reactivity.

Aerobic fitness and cognitive function in midlife: an association mediated by plasma insulin.

Insulin resistance in midlife increases the risk of dementia in late-life. In contrast, habitual aerobic exercise is an established strategy to ameliorate insulin resistance which may translate into better cognitive outcome. To determine the role of plasma insulin in mediating the relation between cardiorespiratory fitness and cognitive function, fifty-eight adults completed assessments of plasma insulin levels, maximal oxygen consumption (VO2max), and neuropsychological test performance. Endurance-trained subjects demonstrated better cognitive outcome (total composite z-score: 0.21 ± 0.08 versus -0.26 ± 0.10, P = 0.001) and lower concentrations of plasma insulin (12.6 ± 0.6 versus 21.3 ± 1.5 ulU/mL, P < 0.001) than sedentary subjects. Greater VO2max was significantly associated with higher memory performance (ß = 0.37, P = 0.01) and lower plasma insulin levels (ß = -0.68, P < 0.001). The significant association between VO2max and memory performance was abolished when the indirect effect of plasma insulin was statistically removed (ß = 0.24, P = 0.19). Fitness-related cognitive enhancement may be mediated, at least in part, by plasma insulin levels.

A questionnaire study investigating the prevalence of chronic postoperative pain.

BACKGROUND: Chronic postoperative pain (CPOP) is defined as pain of at least 2 months duration after a surgical procedure. Until recently, it has been a neglected topic, because it can occur after a wide spectrum of operations; however, little is known regarding its underlying mechanism, prevalence, risk factors, and treatments. We investigated characteristics of CPOP after various operations via a questionnaire. METHODS: Patients were contacted at > 2 months after surgery, irrespective of sex, type of operation or anesthesia method, and a follow-up pain questionnaire was administered by phone. RESULTS: One hundred forty-five of 400 patients (36.3%) described CPOP. The prevalence of CPOP was significantly lower in laparoscopic surgery (29/159, 18.2%) than open surgery (116/241, 48.1%). The prevalence of CPOP was higher with the use of PCA (patient controlled analgesia), (45.3%) than without PCA (24.6%). There were no significant differences regarding sex, anesthetic method, or duration of operation. CONCLUSIONS: Our results indicate that the prevalence of CPOP may be related to use of an endoscope and PCA. However, it is difficult to completely explain the correlation, because this is a complex area of research. More research is needed to improve the quality of pain relief.

Ropivacaine for ultrasound-guided interscalene block: 5 mL provides similar analgesia but less phrenic nerve paralysis than 10 mL.

PURPOSE: Interscalene brachial plexus block (interscalene block) complications usually depend on the dose administered. The objective of this study was to determine whether ultrasound-guided interscalene block with a 5-mL dose of 0.75% ropivacaine would have sufficient analgesic efficacy after shoulder arthroscopic surgery when compared with a 10-mL dose. METHODS: Patients undergoing arthroscopic rotator cuff repair surgery (n = 60) were assigned randomly to one of two groups receiving 5 mL (Group 5) or 10 mL (Group 10) of 0.75% ropivacaine. Ultrasound-guided interscalene block was performed using the in-plane technique, and general anesthesia was administered. Time to first analgesic request was recorded, and the following issues were assessed in the postanesthesia care unit at six, 12, 24, and 48 hr postoperatively: postoperative pain as determined by a visual analogue scale (VAS), patient satisfaction, hemidiaphragmatic paralysis, other block-related complications, and postoperative nausea and vomiting (PONV). RESULTS: There was no significant difference between groups in time to first analgesic requirement (median [interquartile range] for Group 5: 16 [12-48] hr, Group 10: 18 [12-48] hr; P = 0.907). The postoperative pain VAS score was similar in both groups. The incidence of hemidiaphragmatic paralysis on postoperative chest x-ray was 33% in Group 5 and 60% in Group 10 (P = 0.035). However, the incidences of other block-related complications, PONV, and patient satisfaction were not significantly different between groups. CONCLUSION: Interscalene block performed under ultrasound guidance with 0.75% ropivacaine 5 mL showed analgesic efficacy similar to that with 0.75% ropivacaine 10 mL, but with a lower incidence of hemidiaphragmatic paralysis.