Narrow QRS ectopy with concealed connections from a para-Hisian origin to the proximal left fascicles.

INTRODUCTION: Catheter ablation of ectopy originating from the vicinity of the His bundle can be challenging. METHODS AND RESULTS: We report a case of a 33-year-old man with narrow QRS ectopy with preferential conduction from a para-Hisian origin to the proximal left fascicles, which was successfully eliminated by radiofrequency ablation in the right coronary cusp, guided by ultrahigh-resolution mapping of the His bundle, bundle branch, and fascicular electrograms. CONCLUSION: Some narrow QRS ectopy may originate from the vicinity of the conduction system, instead of the "true" conduction system, and have concealed connections from its origin to the conduction system.

Comparison of phrenic nerve injury and its effect on the extrapulmonary vein structures with cryoballoon and hot-balloon ablation systems: considering the lesion created on the superior vena cava as a surrogate marker.

Preventing phrenic nerve injury (PNI) during balloon-based ablation is essential. The superior vena cava-right atrial (SVC-RA) junction is located just opposite the balloon position during right superior pulmonary vein (RSPV) ablation, and the phrenic nerve runs nearby on the lateral side. We compared the occurrence of PNI between the two balloon-based ablation systems and also the lesions created at the SVC-RA junction, which were expected to represent the effect on extra-PV structures. Cryoballoon ablation (CBA, n = 110) and hot-balloon ablation (HBA, n = 90) were performed in atrial fibrillation patients. High-density maps of the SVC-RA junction were created in 93 patients (CBA = 53, HBA = 40), and the damaged area (< 1.0 mV) was determined as an "SVC lesion". CBA had a higher occurrence of transient PNI (7.3% vs 1.1%, p = 0.035), but all recovered during the 6-month follow-up. An apparent SVC lesion was documented in 43% of the patients (40/93), and all patients with PNI had this lesion. CBA created a frequent (CBA vs HBA = 55% vs 28%, p = 0.008) and wider (0.8[0.4-1.7] cm2 vs 0.5[0.3-0.7] cm2, p = 0.005) SVC lesion than HBA. A multivariate analysis revealed that the use of a CBA system was a predictive factor of the occurrence of SVC lesions. CBA had a higher occurrence of transient PNI but not a permanent form. Every patient with PNI had lesions on the SVC-RA junction, and CBA revealed more substantial ablation effects at the SVC-RA junction than HBA. This may be caused by the different characteristics of the two balloon-based ablation systems and their balloon positions.

Clinical and Angiographic Outcomes of Elective Paclitaxel-Coated Balloon Angioplasty in Comparison with Drug-Eluting Stents for De Novo Coronary Lesions in Large Vessels.

We retrospectively examined the feasibility of paclitaxel-coated balloon (PCB) angioplasty for de novo stenosis in large coronary vessels (LV; pre- or postprocedural reference vessel diameter ≥ 2.75 mm) in comparison with placement of drug-eluting stents (DESs).Consecutive de novo stenotic lesions in the LV electively and successfully treated with either PCB (n = 73) or DESs (n = 81) from January 2016 to December 2018 at our center were included. The primary endpoint was the incidence of target lesion failure (TLF), including cardiac death, nonfatal myocardial infarction, and target vessel revascularization. The impact of PCB on TLF was examined using Cox proportional hazards models by including 39 variables. The secondary endpoint, angiographic restenosis, defined as a follow-up percent diameter stenosis > 50, was examined in angiographic follow-up lesions after PCB angioplasty (n = 56) and DES placement (n = 53). This retrospective investigation was conducted in July 2022.The mean PCB size and length were 3.23 ± 0.42 and 18.4 ± 4.3 mm, respectively. The TLF frequency in the PCB group (6.8% during the mean observational interval of 1536 ± 538 days) was not significantly different from that in the DES group (14.6%, 1344 ± 606 days, P = 0.097). PCB was not a significant predictor of TLF in the univariate analysis (hazard ratio: 0.424; 95%CI: 0.15-1.21; P = 0.108). There was no angiographic restenosis after PCB angioplasty.The present observational single-center study showed that PCB for de novo stenosis in the LV had no significant adverse impact on TLF and had favorable angiographic outcomes.

A Propensity Score-Matched Comparison of Midterm Outcomes Between Drug-Coated Balloons and Drug-Eluting Stents for Patients with Acute Coronary Syndrome.

We conducted a single-center, retrospective, lesion-based study to examine the safety and efficacy of drug-coated balloons (DCBs) for de novo coronary stenosis in patients with acute coronary syndrome (ACS) by comparing them with those of drug-eluting stents (DESs).A total of 309 consecutive lesions in patients with ACS who were successfully treated by emergent procedures using either a DCB (n = 107) or a DES between January 2016 and December 2019 were included in the study. The primary endpoint was the incidence of target lesion failure (TLF), defined as cardiac death without mortality due to ACS, non-fatal myocardial infarction, and any target lesion revascularization, including acute occlusion, after DCB use and definite stent thrombosis after DES placement. A propensity score-matched analysis was used to adjust the 36 baseline variables. Retrospective investigations were conducted in January 2021.Baseline adjustment yielded 91 lesions in each group, with a mean balloon size of 3.02 ± 0.22 mm and a mean length of 20.9 ± 6.2 mm in the DCB group. The frequency of TLF in the DCB group (9.9% during the mean observational interval of 671 ± 508 days) was not significantly different from that in the DES group (13.2% during a period of 626 ± 543 days, P = 0.467). The cumulative TLF-free ratio in the DCB group was not significantly different from that in the DES group (P = 0.475, log-rank test).The present propensity score-matched comparison showed statistically equivalent midterm clinical outcomes after DCB use to those of DES placement for de novo lesions in patients with ACS treated by emergent procedures.

Cryofreezing for slow-pathway modification in patients with slow-fast AVNRT: Efficacy, safety, and electroanatomical relation between sites of transient AV block and sites of successful cryoablation.

INTRODUCTION: Cryoablation has emerged as an alternative to radiofrequency ablation for treating atrioventricular nodal reentrant tachycardia (AVNRT). The aim of this prospective study was to evaluate the efficacy and safety of cryoapplication at sites within the mid/high septal region of Koch's triangle and the relation between sites of transient AV block (AVB) and sites of successful cryoablation. METHODS AND RESULTS: Included were 45 consecutive patients undergoing slow-fast AVNRT cryoablation. Initial delivery of cryoenergy was to the mid-septal to high septal region of Koch's triangle. Transient AVB occurred during cryoenergy delivery in 62% (28/45) of patients. Median distance between sites at which cryofreezing successfully eliminated slow pathway conduction and sites of AVB was 4.0 (3.25-5.0) mm. Sites of successful cryoablation tended to be to the left and inferior to the AVB sites. The atrial/ventricular electrogram ratio was significantly lower at sites of successful cryoablation than at AVB sites (0.25 [0.17-0.56] vs. 0.80 [0.36-1.25], p < .001). Delayed discrete or fractionated atrial electrograms were recorded more frequently at sites of successful cryoablation than at AVB sites (78% vs. 20%, p < .001). No persistent AV conduction disturbance occurred, and 96% (43/45) of patients showed absence of recurrence at a median follow-up time of 25.0 months. CONCLUSION: Cryoablation of slow-fast AVNRT and targeting the mid/high septal region of Koch's triangle was highly successful. AVB frequently emerged near the site at which the slow pathway was eliminated but always resolved by regulating the energy delivery under careful monitoring, and it may be distinguishable by its local electrogram features.

Pyrophosphate amplification reaction for measuring amino acid concentrations with high sensitivity using aminoacyl-tRNA synthetase from Escherichia coli.

To measure amino acid concentrations with high sensitivity, the pyrophosphate amplification reaction conditions of histidyl-tRNA synthetase (HisRS) and tyrosyl-tRNA synthetase (TyrRS) were examined. The amount of pyrophosphate produced by reactions involving HisRS and TyrRS was amplified compared with the amount of the initial substrate L-amino acid after the addition of excess adenosine-5'-triphosphate and magnesium ions, with incubation at 50°C in an alkaline pH. The amount of pyrophosphate produced in the HisRS and TyrRS reactions was approximately 24- and 16-fold higher than the initial amount of L-His and L-Tyr, respectively. The pyrophosphate amplification reactions involving HisRS and TyrRS showed high substrate specificity for L-His and L-Tyr, respectively. Products of pyrophosphate amplification were identified as p1, p4-di(adenosine) 5'-tetraphosphate, and adenosine-5'-monophosphate using high-performance liquid chromatography. A strong positive correlation was observed for 0 to 50 µM of L-His and L-Tyr in the pyrophosphate amplification reaction (R = 0.98 and R = 1.00, respectively). Abbreviations: L-His: L-histidine; L-Tyr: L-tyrosine; aaRSs: aminoacyl-tRNA synthetases; ATP: adenosine-5'-triphosphate; aminoacyl-AMP-aaRS: aminoacyl-adenylate intermediate; Ap4A, P1, P4-di(adenosine) 5'-tetraphosphate; AMP: adenosine-5'-monophosphate; PAR: pyrophosphate amplification rate.

Does Selective Posterior Tibial Slope Technique in Cruciate-Retaining Total Knee Arthroplasty Result in the Elimination of Posterior Cruciate Ligament Management?

In cruciate-retaining total knee arthroplasty (CR-TKA), intraoperative posterior cruciate ligament (PCL) management is necessary because retention of optimum PCL tension with high reproducibility is difficult. If PCL management is not performed appropriately, problems such as postoperative pain, poor range of motion, and a feeling of instability may occur. The posterior tibial slope (PTS) has a major influence on the tension of the PCL in CR-TKA. Changes in femoral posterior condylar offset also influences PCL tension in CR-TKA. We designed a surgical procedure in which the PTS is adjusted in association with the posterior condylar offset during surgery. The postoperative clinical results of the primary total knee arthroplasty 159 knee performed by this procedure were favorable. In addition, none of the knees required management of PCL. In our procedure, PCL management, which is the main problem in CR-TKA, is not necessary, and this may be the main advantage of the new procedure.

Characteristics of radiofrequency lesions in patients with symptomatic periesophageal vagal nerve injury after pulmonary vein isolation.

Background: Periesophageal vagal nerve injury (PNI) is an unpredictable and serious complication of atrial fibrillation (AF) ablation. We aimed to identify the factors associated with symptomatic PNI. Methods: This study included 1391 patients who underwent ablation index-guided pulmonary vein isolation (PVI) using the CARTO system. The target ablation index was set at 550, except for the left atrial (LA) posterior wall near the esophagus, where radiofrequency (RF) power and duration were limited. Ten patients (0.72%) were diagnosed with symptomatic PNI. We randomly selected 40 patients without PNI (1:4 ratio) matched based on age, sex, body mass index, LA diameter, type of AF, and esophageal location. We measured the shortest distance from the RF lesions to the esophagus (LED) and classified the RF lesions according to the LED into four groups: 0-5, 5-10, 10-15, and 15-20 mm. We conducted a comparative analysis of classified RF lesions between patients with PNI (n = 10) and those without (n = 40). Results: The contact force at LED 0-5 mm was significantly higher in patients with PNI than in those without (14.6 ± 1.7 vs. 12.0 ± 2.9 g; p = .01). Multivariate logistic analysis revealed that the independent factor for PNI was contact force at an LED of 0-5 mm (odds ratio: 1.506; 95% confidence interval: 1.053-2.153; p = .025). Conclusions: The symptomatic PNI was significantly associated with a higher contact force near the esophagus. Strategies for regulating contact force near the esophagus may aid in the prevention of PNI.

Analysis of functional ingredients of tempe-like fermented Moringa oleifera seeds (Moringa tempe) prepared with Rhizopus species.

Tempe is a fermented food prepared by fermenting soybeans with Rhizopus species. However, there have recently been concerns about the stable supply of raw soybeans due to global warming and other factors. Moringa is a plant whose cultivation area is expected to expand in the future, and its seeds contain abundant proteins and lipids, and thus could be used as an alternative to soybeans. To develop a novel functional Moringa food, we fermented dehulled Moringa seeds with Rhizopus oligosporus and Rhizopus stolonifer using the solid fermentation method of tempe and investigated changes in the functional components, such as free amino acids and polyphenols, of the respective obtained Moringa tempe Rm and Rs. After 45 h of fermentation, the total content of free amino acids, mainly including gamma-aminobutyric acid and l-glutamic acid, in Moringa tempe Rm was about three times higher, while that in Moringa tempe Rs was almost the same, compared to that in unfermented Moringa seeds. Moreover, after 70 h of fermentation, both Moringa tempe Rm and Rs had approximately four times higher polyphenol content and significantly higher antioxidant activity than did unfermented Moringa seeds. Further, the content of each residual chitin-binding protein of defatted Moringa tempe Rm and Rs was almost the same as that of unfermented Moringa seeds. Taken together, Moringa tempe was rich in free amino acids and polyphenols, exhibited better antioxidant activity, and retained the levels of its chitin-binding proteins, suggesting that Moringa seeds could be used as an alternative to soybean for tempe preparation.

Unusual QRS complexes associated with the simultaneous presence of a right-sided accessory pathway, fasciculoventricular pathway, and incomplete right bundle branch block.

A 52-year-old man presented with delta waves on a body surface electrocardiogram, which suggested the presence of a right-sided accessory pathway (AP). Patients with right-sided APs generally have an rS pattern in leads V1-2, while he had an rS in lead V1 but an Rs in lead V2, which could not rule out the possibility of the presence of a septal AP or fasciculoventricular pathway (FVP). On the other hand, patients with septal APs or FVPs generally have a QS pattern in lead V1 instead of an rS pattern. An electrophysiological study demonstrated that the simultaneous presence of a right-sided posterolateral AP and FVP with incomplete right bundle branch block (ICRBBB) generated those unusual QRS complexes. The FVP arose distal to the site with ICRBBB, and the ICRBBB delayed the initiation of the FVP conduction. The delayed QS and Rs waves in leads V1-2 generated by the FVP conduction with ICRBBB appeared to produce rS and Rs patterns in leads V1-2, respectively. A radiofrequency application along the posterolateral tricuspid annulus eliminated the right-sided AP conduction. If the localization of APs based on the QRS morphology is difficult, multiple APs or an FVP with a conduction system disturbance should be noted. Learning objective: Patients with right-sided posterolateral accessory pathways (APs) generally have an rS pattern in lead V2, while patients with fasciculoventricular pathways (FVPs) generally have a QS pattern in lead V1. The present case with a suspected right-sided posterolateral AP had unusual QRS complexes, an rS in lead V1, Rs in lead V2, and monophasic R in leads V3-6, which were associated with the simultaneous presence of a right-sided posterolateral AP, FVP, and incomplete right bundle branch block.

Chronic Effect of HotBalloon-Based Wide Planar Ablation on Epicardial Adipose Tissue in Persistent Atrial Fibrillation.

Background: Adverse atrial remodeling, including epicardial adipose tissue (EAT) deposition in the left atrium (LA), is implicated in atrial fibrillation (AF). Radiofrequency hotballoon (RHB) ablation can produce wide planar lesions because the balloon is highly compliant; however, chronic effects of RHB ablation on structural remodeling remain unknown. This clinical-experimental investigation characterized chronic effects of RHB ablation on EAT in persistent AF (PsAF). Methods and Results: The clinical study involved 91 patients (obese, n=30; non-obese, n=61) undergoing RHB ablation for PsAF. LA-EAT was assessed from computed tomography images obtained before ablation and 6 months later. Tissue effects of RHB ablation were explored in a chronic swine model. RHB ablation significantly reduced LA volume (mean [±SD] 177.7±29.7 vs. 138.4±29.6 mL; P<0.001) and LA-EAT volume (median [interquartile range] 22.0 [12.4-33.3] vs. 16.5 [7.9-25.8] mL; P<0.001). The reduction in EAT was significantly greater in the pulmonary vein (PV) antrum than in other LA regions (37.9% vs. 15.8%; P<0.001). The percentage reduction in PV antrum EAT was equivalent between obese and non-obese patients, as was the postablation success rate (73% vs. 70%; P=0.77). RHB ablation produced transmural lesions reaching the pigs' epicardial fat region. Conclusions: RHB-based planar-transmural lesions altered the structurally remodeled LA, including EAT. Further studies are needed to determine whether factors other than PV isolation contribute to the clinical success of RHB ablation.

Noncontact Charge Density Mapping-Guided Ablation of Persistent Atrial Fibrillation With a Multiple Trigger-Based Mechanism.

We present a case of radiofrequency catheter ablation of persistent atrial fibrillation (AF) with a trigger-based mechanism, guided by novel noncontact charge density mapping, which resulted in the simultaneous achievement of the termination of AF and complete elimination of multiple triggers that induced repeated recurrences of AF immediately after cardioversion. (Level of Difficulty: Advanced.).

Is creation of a fully circumferential lesion set necessary for laser balloon ablation-based pulmonary vein isolation?

BACKGROUND: Despite reports of remote pulmonary vein (PV) stenosis after visually guided laser balloon (VGLB) ablation, circumferential (360°) lesion sets are routinely performed. This study aimed to determine whether fully circumferential lesion creations are required for all PVs to achieve PV isolations (PVIs) and to determine PV's vulnerability to chronic-phase stenosis. METHODS: Fifty-one patients with paroxysmal atrial fibrillation underwent mapping-guided PVIs using circular mapping catheters. VGLB ablation was performed circumferentially beginning at the 12 o'clock position and continued clockwise or counterclockwise. PVIs obtained within the bounds of the first half of the circumferential lesion (≤ 180°) were defined as "early PVIs." RESULTS: "Early PVIs" were documented in real time for 39% (80/204) of the PVs and at a significantly greater frequency among lower PVs than upper PVs (60.1% vs. 17.6%; p < 0.0001). The PV sleeve length, PV diameter, and isolation of ipsilateral PVs within a semicircular lesion set were identified as predictors of an "early PVI" phenomenon. The amount of energy delivered to the lower PVs was significantly less than that to the upper PVs (5553 [5089-6188] vs. 3559 [2793-4380] J; p < 0.0001), but the incidence of narrowing of the lower PVs at 6 months was comparable to that of the upper PVs (p = 0.73). CONCLUSION: Our study revealed electrical isolations of more than 60% of the lower PVs while creating the first half of the circumferential lesions. Crosstalk via the carina region was presumably involved due to the preceding upper PVI. Further study is needed to determine whether energy delivery adjustments are needed for lower PVs to avoid chronic narrowing.

Incidence, distribution, and electrogram characteristics of endocardial-epicardial connections identified by ultra-high-resolution mapping during a left atrial posterior wall isolation of atrial fibrillation.

PURPOSE: The left atrial posterior wall (LAPW) can be a target for atrial fibrillation (AF) catheter ablation but is sometimes difficult to completely isolate due to the presence of endocardial-epicardial connections. We aimed to investigate the incidence and distribution of epicardial residual connections (epi-RCs) and the electrogram characteristics at epi-RC sites during an initial LAPW isolation. METHODS: We retrospectively studied 102 AF patients who underwent LAPW mapping before and after a first-pass linear ablation along the superior and inferior LAPW (pre-ablation and post-ablation maps) using an ultra-high-resolution mapping system (Rhythmia, Boston Scientific). RESULTS: Epi-RCs were observed in 41 patients (40.2%) and were widely distributed in the middle LAPW area and surrounding it. The sites with epi-RCs had a higher bipolar voltage amplitude and greater number of fractionated components than those without (median, 1.09 mV vs. 0.83 mV and 3.9 vs. 3.4 on the pre-ablation map and 0.38 mV vs. 0.27 mV and 8.5 vs. 4.2 on the post-ablation map, respectively; P < 0.001). Receiver operating characteristic analyses demonstrated that the number of fractionated components on the post-ablation map had a larger area under the curve of 0.847 than the others, and the sensitivity and specificity for predicting epi-RCs were 95.4% and 62.1%, respectively, at an optimal cutoff of 5.0. CONCLUSIONS: Among the patients with epi-RCs after a first-pass LAPW linear ablation, areas with a greater number of fractionated components (> 5.0 on the post-ablation LAPW map) may have endocardial-epicardial connections and may be potential targets for touch-up ablation to eliminate the epi-RCs.

Improvement of substrate recognition in branched-chain aminoacyl-tRNA synthetases from Escherichia coli under conditions of pyrophosphate amplification.

Isoleucyl-tRNA synthetase (IleRS), leucyl-tRNA synthetase (LeuRS), and valyl-tRNA synthetase (ValRS) are enzymes that have potential for the determination of l-isoleucine, l-leucine, and l-valine in food products and plasma. However, the disadvantages of these enzymes are their specificity and sensitivity. Here, we examined the substrate specificity of IleRS, LeuRS, and ValRS under various conditions of pyrophosphate amplification to improve their specificity and sensitivity. The amount of pyrophosphate produced in IleRS, LeuRS, and ValRS reactions was amplified after the addition of excess adenosine-5'-triphosphate and magnesium ions, and was approximately 9-, 8-, and 7-fold higher, respectively, for each of the initial l-amino acid substrates (50 µM). However, in addition to their target amino acids, IleRS, LeuRS, and ValRS also reacted with l-valine, l-lysine, and l-threonine, respectively. This substrate misrecognition was overcome by making the reaction pH more acidic and by increasing the magnesium ion concentration. The pyrophosphate amplification in IleRS, LeuRS, and ValRS reactions resulted in the production of p1, p4-di (adenosine) 5'-tetraphosphate. We also observed a strong positive correlation (R = 0.99) between the amount of pyrophosphate produced and the initial concentration of l-amino acid with 5 and 50 µM l-isoleucine, l-leucine, and l-valine. Our results suggest that amino acid assays using IleRS, LeuRS, and ValRS are promising methods to accurately measure l-valine, l-isoleucine, and l-leucine in food products and plasma.

Kinetic Modeling of CO2 and H2O Gasification Reactions for Metallurgical Coke Using a Distributed Activation Energy Model.

A distributed activation energy model (DAEM) was applied to the kinetic analysis of CO2 and H2O gasification reactions for pulverized metallurgical coke. The results of the scanning electron microscopy observations and CO2 gas adsorption suggested that the gasification reaction occurs at the particle surface. Therefore, a grain model was employed as a gasification reaction model. The reaction rates of CO2 and H2O gasification were evaluated based on the DAEM. The activation energy changed as the reaction progressed and hardly depended on the particle size. The activation energies were 200-260 kJ/mol in CO2 gasification and 220-290 kJ/mol in H2O gasification. The frequency factor of H2O gasification was approximately 10 times larger than that of CO2 gasification, regardless of the progress of the reaction. At the same activation energy level, the frequency factor showed a higher value with a decrease in the particle size. This result was consistent with the theory of the grain model and indicated that the gasification reaction of the pulverized coke with a micrometer scale occurs on the surface of the coke particle. Furthermore, the value predicted by the DAEM was in good agreement with the experimental one.

Isolation and identification of the antimicrobial substance included in tempeh using Rhizopus stolonifer NBRC 30816 for fermentation.

In this study, we focus on the antimicrobial properties of tempeh, a soybean fermented food, against oral bacteria. Tempeh showed antimicrobial activity against dental caries pathogenic bacterium Streptococcus mutans at a final concentration of 1 mg/mL. An antimicrobial substance contained in tempeh was present in the 100 kDa or greater fraction generated by ultrafiltration, but it was found not to be proteinaceous by native-PAGE, SDS-PAGE and protein degradation tests. Next, when the fraction was purified with an ODS column, the 80% and 100% methanol eluates showed antimicrobial activity against S. mutans. The 100% methanol eluate was further subjected to a 2nd column purification, and isolation of the target was confirmed by HPLC. When the isolated material was analyzed by ESI-MS, the m/z was 279.234. Further analysis by Raman spectroscopy revealed a peak similar to linoleic acid. This substance also possessed antimicrobial properties equivalent to linoleic acid.

Beneficial Effects of Dietary Tempeh Prepared with Rhizopus stolonifer on Liver Function in Rats Fed with a High-Fat Diet.

The regional standard for tempeh established by the Codex Alimentarius defines the use of Rhizopus oligosporus, R. oryzae, and/or R. stolonifer as soybean tempeh starters. However, comparative studies on the functions of tempeh prepared with these Rhizopus species are scarce. In the present study, we examined the effects of dietary tempeh prepared with these three Rhizopus species using rats fed with a high-fat diet. Compared to the control diet, consumption of tempeh prepared with R. stolonifer significantly suppressed serum levels of aspartate transaminase, total bilirubin, and ammonium (indices of liver function). However, less or no suppression was observed with tempeh prepared with R. oligosporus or R. oryzae. Serum levels of triglyceride, total cholesterol, HDL cholesterol, and glucose were unaffected. Liver levels of free cholesterol, a parameter relating to liver injury, were significantly decreased by the three types of the tempeh examined; however, there was no difference in the free cholesterol levels among the tempeh groups. We conclude that the ingestion of tempeh prepared with R. stolonifer might have beneficial effects pertaining to the liver function in rats fed with high-fat diets.

Frictional properties of regenerated cartilage in vitro.

Although tribological function is the most important mechanical property of articular cartilage, few studies have examined this function in tissue-engineered cartilage. We investigated changes in the frictional properties of cartilage regenerated from the inoculation of rabbit chondrocytes into fibroin sponge. A reciprocating friction-testing apparatus was used to measure the friction coefficient of the regenerated cartilage under a small load. The specimen was slid against a stainless steel plate in a water vessel filled with physiological saline. The applied load was 0.03 N, the stroke length was 20 mm, and the mean sliding velocity was 0.8 mm/s. The friction coefficient of the regenerated cartilage decreased with increasing cultivation time, because a hydrophilic layer of synthesized extracellular matrix was formed on the fibroin sponge surface. The friction coefficient of the regenerated cartilage was as low as that of natural cartilage in the early stages of the sliding tests, but it increased with increasing duration of sliding owing to exudation of interstitial water from the surface layer.