Factors associated with the progression of sagittal spinal deformity after total hip arthroplasty: a propensity score-matched cohort study.

PURPOSE: The functional interaction between the hip and spine in patients undergoing total hip arthroplasty (THA) is clinically significant, as it impacts post-operative outcomes. Therefore, this study aimed to identify factors associated with the progression of sagittal spinal deformity and assess the association with patient-reported outcomes. METHODS: This retrospective case-control study included 200 patients who underwent primary THA and completed a mean follow-up duration of 42.2 months (range, 24.0-78.0). We employed a multivariate logistic regression to identify variables predictive of a post-THA sagittal vertical axis (SVA) ≥ 50 mm, which was indicative of a spinal sagittal imbalance. Propensity score-matched cohorts for age, sex, body mass index, follow-up duration, hip flexion contracture, developmental dysplasia, pelvic incidence (PI), and SVA were created, and the outcomes were compared between the two groups. RESULTS: PI (odds ratio 1.39; 95% confidence interval 1.04-1.86, p = 0.033) was associated with an SVA ≥ 50 mm. After successfully matching patients with (n = 50) and without (n = 50) an SVA ≥ 50 mm, the minimum clinically important difference showed significant differences between the 50 matched pairs (p = 0.016 for EuroQol-5D, p = 0.003 for Hip Disability and Osteoarthritis Outcome Score Joint Replacement, and p < 0.001 for low back pain). CONCLUSION: PI is associated with the development of a positive sagittal spinal malalignment post-THA. This finding can assist surgeons in managing patient expectations and in optimising outcomes. Feasible strategies are warranted to minimise the risk of spinal deformity progression post-THA.

Usefulness of Probing Sensor Device for Evaluating Meniscal Suture and Scaffold Implantation.

Appropriate suture tension is a key factor in successful meniscal repair. This study aimed to clarify the appropriate value of meniscal stabilization with suture repair based on a probing procedure for healthy porcine menisci and a novel meniscal scaffold. After evaluating the reliability of the probing sensor, meniscal vertical tear and partial meniscectomy models were developed, in which suture repair and meniscal scaffold implantation were performed at suture intervals ranging between 20 and 2.5 mm. The residence forces at each interval were evaluated using a probing sensor. Moreover, a tensile test was conducted to evaluate the displacement and presence or absence of gaps. We found that normal and meniscal scaffolds should be fixed within 5 mm of suture interval. The probing residence forces required were at least 1.0 N for vertical tears and 3.0 N for meniscal scaffolds. These findings may be taken into consideration to reduce suture failure following meniscal tear repair and stabilizing meniscal scaffold fixation.

Worse Patient-Reported Outcomes and Spino-Pelvic Parameters After Total Hip Arthroplasty for Rapidly Progressive Osteoarthritis of the Hip Compared to Osteoarthritis: A Propensity-Matched Cohort Study.

BACKGROUND: This study aimed to assess the association between the disease process of hip osteoarthritis and total hip arthroplasty (THA) outcomes; this is a critical issue, as rapid progression has been postulated to be responsible for patient dissatisfaction after THA. METHODS: This retrospective case-control study included 255 patients who underwent THA and completed a mean follow-up duration of 42.1 months (range, 24.0 to 77.0). We classified patients into those who had (n = 26) and did not have (n = 229) rapidly progressive osteoarthritis of the hip (RPOA), defined as a narrowing rate of joint space ≥ 2 mm yearly or a ≥ 50% loss within 12 months, excluding any other cause of a destructive arthropathy. Propensity score-matched cohorts for age, sex, body mass index, and spino-pelvic measures were created, and the outcomes were compared between the 2 groups. RESULTS: After successfully matching RPOA (n = 25) and non-RPOA patients (n = 50), there were significant differences in minimum clinically important difference (P = .009 for European Quality of Life 5-Dimension, and P < .001 for low back pain), patient acceptable symptom state (P = .015 for European Quality of Life 5-Dimension, and P < .001 for Hip Disability and Osteoarthritis Outcome Score Joint Replacement score), patient satisfaction (P = .028), and T1 pelvic angle as an indicator of global sagittal spinal deformity (P = .017). There was a correlation between T1 pelvic angle and low back pain in the RPOA group (R = 0.628, P < .001). CONCLUSIONS: Patients who exhibited RPOA before undergoing THA showed worse patient-reported outcomes compared with those who did not have rapid progression. Our study highlights the critical role of the disease process in influencing THA outcomes, advocating for a paradigm shift toward more meticulous preoperative evaluations, including global spinal deformity, standardized diagnostic criteria, and tailored interventions.

The psoas muscle index as a useful predictor of total hip arthroplasty outcomes.

INTRODUCTION: The aim of this study is to assess the association between the psoas muscle index (PMI) and total hip arthroplasty (THA) outcomes. This is a critical issue as sarcopenia has been associated with poor patient satisfaction post-THA. MATERIALS AND METHODS: This was a retrospective case-control study of 205 THAs, with a mean follow-up of 3.6 (range, 2.0-5.5) years. Age, sex, serum immune markers, spinopelvic parameters, PMI (quantified as the cross-sectional area of the psoas, bilaterally, at L3 divided by the individual's height squared), and patient-reported outcomes were compared between patients 'with' (n = 118) and 'without' (n = 87) achievement of a minimum clinically important difference (MCID) improvement in the EuroQol 5-Dimension (EQ-5D), post-THA. Logistic regression and receiver operating characteristic curve analyses were used to identify predictive factors. RESULTS: A ≥ MCID improvement in the EQ-5D was associated with the PMI (odds ratio, 0.75; 95% confidence interval, 0.63-0.91; P = 0.028), prognostic nutritional index (odds ratio, 0.85; 95% confidence interval, 0.45-0.94; P = 0.043), and age (odds ratio, 1.09; 95% confidence interval, 1.01-1.18; P = 0.044). After adjusting the PMI threshold to 4.0 cm2/m2 for females and 6.4 cm2/m2 for males, there were significant differences in serum factors (P = 0.041 for albumin and P = 0.016 for a prognostic nutritional index < 40), MCID (P < 0.001 for EQ-5D, P < 0.001 for low back pain, and P = 0.008 for the Hip Disability and Osteoarthritis Outcome Score Joint Replacement score), patient satisfaction (P = 0.003), and T1 pelvic angle (P = 0.030). CONCLUSION: The PMI, which is associated with nutritional status and global sagittal spinal deformity, does predict THA outcomes. Therefore, it can be useful when discussing THA expectations with patients.

Effect of lateral hinge fractures for bone union and clinical outcomes following opening-wedge distal tibial tubercle osteotomy in comparison with opening-wedge high tibial osteotomy.

PURPOSE: Although the effects of lateral hinge fractures (LHF) on bone union and clinical outcomes after opening-wedge high tibial osteotomy (OWHTO) have been established, the effects of LHF after opening-wedge distal tibial tubercle osteotomy (OWDTO) are unclear. We hypothesised that LHF after OWDTO would be associated with delayed bone union and result in poorer clinical outcomes than expected for LHF after OWHTO. METHODS: This study enrolled 100 patients, with 50 OWDTO patients (18 men; mean age, 63.2 years) and 50 OWHTO patients compared based on the propensity score matched analysis. The effect of LHF on bone union was compared between the groups. Clinical outcomes were assessed using the Lysholm score and the Knee Injury and Osteoarthritis Outcome Score (KOOS) at the mean follow-up of 28 months. RESULTS: There was no between-group difference in the incidence rate of LHF. However, the rate of bone union at the anterior flange in the presence of an LHF was significantly lower in the OWDTO (26%) than in the OWHTO (80%) 3 months postoperatively (p < 0.05), but no difference was observed 12 months postoperatively. The Lysholm score was significantly lower for patients with LHF following OWDTO than for OWDTO patients without LHF or OWHTO patients with/without LHF 3 and 12 months postoperatively (p < 0.001); Lysholm score and KOOS were not different at the final follow-up. CONCLUSIONS: LHF after OWDTO was associated with delayed bone union and poor clinical outcomes until 12 months. This information can guide decisions regarding the indications and the management of patients after OWDTO. LEVEL OF EVIDENCE: IV.

Clinical significance of relative pelvic version measurement as a predictor of low back pain after total hip arthroplasty.

PURPOSE: To evaluate the association between the preoperative global alignment and proportion (GAP) score and low back pain (LBP) after total hip arthroplasty (THA). METHODS: This was a retrospective case-control study of 200 patients who underwent primary unilateral THA for hip osteoarthritis. The following variables were compared between individuals with (n = 76) and without (n = 124) LBP after THA over a mean follow-up of 2 years: age, sex, GAP score, and patient-reported outcome measures. Logistic regression and receiver operating characteristic curve analyses were used to detect predictive factors. RESULTS: The following parameters were predictive of post-THA LBP: relative pelvic version (RPV) <-7° (odds ratio, 1.43; 95% confidence interval, 1.10-1.72; P = 0.032) and relative lumbar lordosis <-15° (odds ratio, 1.13; 95% confidence interval, 1.04-2.13; P = 0.041) preoperatively. Using an RPV cutoff value of - 7° (specificity 61/64 = 0.953; sensitivity 121/136 = 0.890), there were significant between-group differences in LBP visual analog scale (P = 0.020), Oswestry Disability Index (ODI, P = 0.014), EuroQol 5-Dimension (P = 0.027), Hip Disability and Osteoarthritis Outcome Score Joint Replacement (HOOS JR, P = 0.012), patient satisfaction (P = 0.024). There was clinically meaningful improvement for LBP visual analog scale (P = 0.001), ODI (P = 0.004), and HOOS JR (P < 0.001). The RPV before THA was correlated with HOOS JR (r = 0.773, P = 0.012) and ODI (r = - 0.602, P = 0.032) postoperatively. CONCLUSION: Among the GAP score, a moderate-to-severe pelvic retroversion was significantly associated with LBP post-THA. The RPV measurement may be a useful predictor of THA outcome, which may influence patient satisfaction.

Safety and Efficacy of a Novel Polyglycolic Acid Meniscal Scaffold for Irreparable Meniscal Tear.

OBJECTIVE: Meniscal tears treated with a partial meniscectomy could induce knee osteoarthritis, thereby altering or damaging knee kinetics and biomechanics. We have developed a meniscal scaffold made of polyglycolic acid (PGA) coated with polylactic acid/caprolactone (PGA scaffold), which could induce new tissue growth of meniscus-like tissue. This study aimed to evaluate the safety and efficacy of a novel meniscal scaffold for the treatment of irreparable meniscal injuries. DESIGN: This study describes the findings of a cyclic torque test and first clinical trial of a PGA scaffold for inducing meniscus-like tissue in humans. As the first step, biomechanical testing of the PGA scaffold was performed using a cyclic torque test. Six patients underwent arthroscopic implantation of the PGA scaffold. Furthermore, the patients underwent preoperative clinical, serological, radiographic, and magnetic resonance imaging examinations at 3, 6, and 12 months postoperatively. The patients also underwent a second-look arthroscopy 12 months after implantation. RESULTS: Torque increased with increasing cyclic loading. However, no structural damage to the sample was noted after 70,000 loading cycles. All patients showed improvement in pain, Lysholm scores, Tegner activity scores, International Knee Documentation Committee, and knee injury and osteoarthritis outcome. The second-look arthroscopy revealed that meniscal tissue had regenerated in 5 patients (83%). Radiography and magnetic resonance imaging confirmed no progression of degenerative joint disease. CONCLUSIONS: The PGA scaffold could tolerate shear forces, did not produce safety concerns, and may have therapeutic potentials for irreparable meniscal tears in humans.

T1 pelvic angle is associated with rapid progression of hip arthrosis.

PURPOSE: To evaluate the association between global spinal malalignment and rapid progression of hip arthrosis. METHODS: This was a retrospective, case-control study including 90 patients, contributing 90 hips, who underwent hemi- or total hip arthroplasty at our institution. For analysis, hips were classified into a rapid progression group, defined as ≥ 2 mm destruction of the femoral head or loss of the hip joint space within a 12-month period (n = 30), and a non-rapid progression group, defined by no observable hip disease progression over a period more than 12 months (n = 60). Logistic regression analysis identified factors that predicted rapid progression, with a receiver operating characteristic curve analysis used to confirm factors. RESULTS: Significant between-group differences were identified for the following parameters: pelvic tilt (P = 0.002, PT), sagittal vertical axis (P = 0.002, SVA), and T1 pelvic angle (P < 0.001, TPA). On multiple logistic regression, PT (P = 0.002), SVA (P = 0.002), and TPA (P < 0.001) were predictive of a rapid progression on hip arthrosis, with the area under the curve being greater for TPA than PT (P = 0.035). CONCLUSION: Global spinal alignment is associated with rapid progression of hip arthrosis. TPA could assist in identifying patients at risk for rapid progression of hip arthrosis, allowing for time management.

A modified high-resolution melting-based assay (HRM) to identify the SARS-CoV-2 N501Y variant.

High-resolution melting (HRM) analysis is a PCR-based method that can be used as a screening assay to identify SARS-CoV-2 variants. However, conventional HRM assays hardly detect slight melting temperature differences at the A-T to T-A transversion. As the N501Y substitution results from A-T to T-A transversion in A23063, few or no studies have shown that a conventional HRM assay can identify N501Y variants. This study successfully developed an HRM assay for identifying the N501Y mutation. Two HRM assays were used in the N501 site because the discrimination results were affected by the virus copy numbers. One is a conventional HRM assay (detectable at 103-106 copies/mL) and the other is a modified HRM assay by adding the wild-type fragment (detectable at 105-1010 copies/mL). Using viral RNAs from cultured variants (Alpha, Beta, and Gamma), a modified HRM assay correctly identified three N501Y variants because of high-copy-number RNAs in those viral samples. The sensitivity and specificity of the N501Y assay were 93.3% and 100%, respectively, based on 209 clinical samples (105 for N501; 104 for N501Y). These results suggest that our HRM-based assay is a powerful tool for rapidly identifying various SARS-CoV-2 variants.

Species differences in activation of TRPA1 by resin additive-related chemicals relevant to indoor air quality.

Transient Receptor Potential Ankyrin 1 (TRPA1), which is expressed in the airways, has causative and exacerbating roles in respiratory diseases. TRPA1 is known as a target of sick building syndrome-related air pollutants, such as formaldehyde. Thus, an in vitro TRPA1 activation assay would be useful for predicting the potential risk of air pollution. In this study, we used human TRPA1 (hTRPA1)- and mouse TRPA1 (mTRPA1)-expressing cell lines to measure TRPA1 activation by the emerging indoor air pollutants 2-ethyl-1-hexanol (2-EH), a mixture of 2,2,4-trimethyl-1,3-pentanediol 1- and 3-monoisobutyrate (Texanol), and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB). The results indicated that 2-EH activated both hTRPA1 and mTRPA1 in a concentration-dependent manner, whereas TXIB did not activate hTRPA1 or mTRPA1. Texanol also activated hTRPA1 in a concentration-dependent manner. In contrast, a bell-shaped concentration-dependent curve was observed for mouse TRPA1 activation by Texanol, indicating inhibitory effects at a higher concentration range, which was also reported for menthol, a typical TRPA1 modulator. To further elucidate the mechanism underlying the species difference in TRPA1 activation by Texanol, V875G and G878V mutations were introduced into hTRPA1 and mTRPA1, respectively, which were reported to be key mutations for the inhibitory effect of menthol. These mutations switched the inhibitory effects of Texanol; thus, hTRPA1/V875G, but not mTRPA1/G878V, was inhibited at higher concentrations of Texanol. These results indicate that Texanol shares an interaction site with menthol. Overall, these findings suggest that careful interpretation is necessary when extrapolating rodent TRPA1-dependent toxicological effects to humans, especially with respect to the risk assessment of indoor air pollutants.

The flexion-extension gap is predictive of patient-reported outcome measures after cruciate-retaining total knee arthroplasty.

BACKGROUND: We aimed to evaluate the association between the flexion-extension gap difference and patient-reported outcome measures after total knee arthroplasty (TKA). METHODS: This was a retrospective case-control study of 60 cruciate-retaining single-radius TKAs. Soft tissue balancing was measured using an offset seesaw tensioner and centre-type digital knee balancer under joint distraction forces of 20-50 lbf and 1.5 times body mass index (1.5 BMI). At the last follow up of 2.0-6.5 (mean, 4.5) years postoperatively, patients were asked if they perceived their knee joint as 'natural' (26 knees) or 'artificial' (34 knees). Age, sex, and the flexion-extension gap were compared between the two groups. A receiver operating characteristic curve was used to determine cut-off values of variables predictive of a natural joint perception. RESULTS: Natural joint perception was associated with a greater flexion-extension gap difference under a distraction force of 1.5 BMI (P = 0.016), higher knee function (Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, P = 0.019), and quality of life (EuroQol 5-Dimension, P = 0.029). A gap difference of 0.95 mm under 1.5 BMI distraction predicted a natural joint perception post-TKA (sensitivity, 97.1%; specificity, 88.5%). Using a gap threshold of 1.0 mm under a 1.5 BMI distraction force yielded significant between-group differences in postoperative flexion (P = 0.040), satisfaction (P = 0.043), knee joint function (P < 0.001), quality of life (P = 0.032), and posterior femoral condylar offset (P = 0.037) CONCLUSION: A flexion-extension gap difference ≥1.0 mm under a distraction force of 1.5 BMI predicted superior outcomes, including patient satisfaction, after cruciate-retaining TKA. It was suggested that posterior femoral condylar offset could influence this finding.

A Rapid Screening Assay for Clarithromycin-Resistant Mycobacterium avium Complex Using Melting Curve Analysis with Nonfluorescent Labeled Probes.

Mycobacterium avium complex (MAC) thrives in various environments and mainly causes lung disease in humans. Because macrolide antibiotics such as clarithromycin or azithromycin are key drugs for MAC lung disease, the emergence of macrolide-resistant strains prevents the treatment of MAC. More than 95% of macrolide-resistant MAC strains are reported to have a point mutation in 23S rRNA domain V. This study successfully developed a melting curve assay using nonfluorescent labeled probes to detect the MAC mutation at positions 2058 to 2059 of the 23S rRNA gene (AA genotype, clarithromycin susceptible; TA, GA, AG, CA, AC, and AT genotypes, clarithromycin resistant). In the AA-specific probe assay, the melting peak of the DNA fragment of the AA genotype was higher than that of DNA fragments of other genotypes. Melting temperature (Tm) values of the AA genotype and the other genotypes were about 80°C and 77°C, respectively. DNA fragments of each genotype were identified correctly in six other genotype-specific probes (TA, GA, AG, CA, AC, and AT) assays. Using genomic DNA from six genotype strains of M. avium and four genotype strains of M. intracellulare, we confirmed that all genomic DNAs could be correctly identified as individual genotypes according to the highest Tm values among the same probe assays. These results indicate that this melting curve-based assay is able to determine MAC genotypes at positions 2058 to 2059 of the 23S rRNA gene. This simple method could contribute to the rapid detection of clarithromycin-resistant MAC strains and help to provide accurate drug therapy for MAC lung disease. IMPORTANCE Since macrolide antibiotics such as clarithromycin or azithromycin are key drugs in multidrug therapy for Mycobacterium avium complex (MAC) lung diseases, the rapid detection of macrolide-resistant MAC strains has important implications for the treatment of MAC. Previous studies have reported a correlation between drug susceptibility testing and the mutation of macrolide resistance genes. In this study, we developed a novel melting curve-based assay using nonfluorescent labeled probes to identify both clarithromycin-resistant M. avium and M. intracellulare with mutations in the 23S rRNA gene, which is the clarithromycin or azithromycin resistance gene. This assay contributed to not only the detection of MAC mutations but also the determination of all genotypes at positions 2058 to 2059 of the 23S rRNA gene. Furthermore, because nonfluorescent labeled probes are used, this assay is more easily and more immediately available than other methods.

The significance of the pelvic incidence measurement as a possible predictor of TKA outcome.

PURPOSE: To evaluate the association between the sagittal alignment of the pelvis and residual knee flexion contracture after total knee arthroplasty (TKA). This is important as a flexion contraction can be associated with the risk of poor outcomes and patient satisfaction after TKA. METHODS: This was a retrospective, case-control, study of 200 osteoarthritic knees, contributed by 200 patients, over a mean follow-up of 2.4 years. The following factors were compared between patients 'with' (46 knees) and 'without' (154 knees) a residual flexion contracture ≥ 10° after TKA: age, sex, pelvic incidence (PI), anterior femoral bowing, femoral component flexion angle (FFA), and patient-reported outcomes. Logistic regression and receiver operating characteristic curve analyses were used to identify predictive factors. RESULTS: The following factors were predictive of a residual flexion contracture ≥ 10°: a pelvic incidence ≥ 55° (odds ratio, 1.29; 95% confidence interval, 1.05-1.59; P = 0.031) and the FFA (odds ratio, 1.08; 95% confidence interval, 1.03-1.14; P = 0.044). A pelvic incidence cutoff of 55° yielded a significant between-group difference, with a sensitivity of 78.4% and specificity of 89.9% to differentiate a residual knee flexion contracture ≥ 10° (P = 0.001), patient satisfaction (P = 0.029), EuroQol 5-Dimension score (P = 0.028), anterior femoral curvature (P = 0.031), and Knee Injury and Osteoarthritis Outcome Score-Joint Replacement score (P = 0.046). CONCLUSION: A pelvic incidence > 55° is associated with a residual knee flexion contracture ≥ 10° after TKA. The significance of the pelvic incidence measurement as a possible predictor of TKA outcome was highlighted, including its impact on patient satisfaction. LEVEL OF EVIDENCE: III.

Biomechanical assessment of a novel meniscal scaffold compared to partial meniscectomy: A study on porcine meniscal injury.

This study aimed to investigate the appropriate size of scaffold implantation on stress distribution and evaluate its mechanical and biomechanical properties considering hydrolysis. The meniscus acts as a load distribution in the knee, and its biomechanical properties are essential for the development of the PGA scaffold. We established a novel meniscal scaffold, which consists of polyglycolic acid (PGA) covered with L-lactide-ε-caprolactone copolymer (P[LA/CL]). After 4 weeks of hydrolysis, the scaffold had a 7% volume reduction compared to the initial volume. In biomechanical tests, the implantation of scaffolds 20% larger than the circumferential and vertical defect size results in greater contact stress than the intact meniscus. In the mechanical evaluation associated with the decomposition behavior, the strength decreased after 4 weeks of hydrolysis. Meanwhile, in the biomechanical test considering hydrolysis, contact stress and area equivalent to intact were obtained after 4 weeks of hydrolysis. In conclusion, the implantation of the PGA scaffold might be a useful alternative to partial meniscectomy in terms of mechanical properties, and the PGA scaffold should be implanted up to 20% of the defect size.

Impact of the Weightbearing Line on Cartilage Regeneration of the Medial Knee Compartment after Open-Wedge High Tibial Osteotomy, Based on Second-Look Arthroscopy.

OBJECTIVE: Cartilage regeneration is multifactorial. This study aimed to optimize the biomechanical factor of weightbearing loading allowing for cartilage regeneration and elucidate the association between cartilage regeneration and clinical outcomes after medial open-wedge high tibial osteotomy (OWHTO). DESIGN: This was a retrospective, observational study of 142 patients who underwent OWHTO and subsequently underwent second-look arthroscopic assessment at a single orthopedic surgery center in Japan. Clinical and radiographic outcomes were compared between patients with (group R) and without (group D) cartilage regeneration, measured using the International Cartilage Repair Society grading system and the macroscopic staging system at the time second-look arthroscopy was performed. A receiver operating characteristic curve analysis was used to determine the optimal weightbearing line ratio (WBLR) for cartilage regeneration. RESULTS: Group R included 82 knees, and group D 60 knees. The WBLR was higher in group R (60.9% ± 6.7%) than in group D (55.6% ± 7.6%) (P < 0.001) and was associated with a greater improvement in clinical outcomes, namely the Lysholm scale score and all subscales of the Knee Injury and Osteoarthritis Outcome Score (P < 0.01). The WBLR predicted cartilage regeneration with an odds ratio of 1.11 (P = 0.001) and an area under the curve of 0.718, for a WBLR value of 62%. CONCLUSIONS: A WBLR of 62% was associated with cartilage regeneration after OWHTO and high patient-reported clinical outcomes.

Rapid Identification of SARS-CoV-2 Omicron BA.5 Spike Mutation F486V in Clinical Specimens Using a High-Resolution Melting-Based Assay.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariant BA.5 emerged as of February 2022 and replaced the earlier Omicron subvariants BA.1 and BA.2. COVID-19 genomic surveillance should be continued as new variants seem to subsequently appear, including post-BA.5 subvariants. A rapid assay is needed to differentiate between the currently dominant BA.5 variant and other variants. This study successfully developed a high-resolution melting (HRM)-based assay for BA.4/5-characteristic spike mutation F486V detection and demonstrated that our assay could discriminate between BA.1, BA.2, and BA.5 subvariants in clinical specimens. The mutational spectra at two regions (G446/L452 and F486) for the variant-selective HRM analysis was the focus of our assay. The mutational spectra used as the basis to identify each Omicron subvariant were as follows: BA.1 (G446S/L452/F486), BA.2 (G446/L452/F486), and BA.4/5 (G446/L452R/F486V). Upon mutation-coding RNA fragment analysis, the wild-type fragments melting curves were distinct from those of the mutant fragments. Based on the analysis of 120 clinical samples (40 each of subvariants BA.1, BA.2, and BA.5), this method's sensitivity and specificity were determined to be more than 95% and 100%, respectively. These results clearly demonstrate that this HRM-based assay is a simple screening method for monitoring Omicron subvariant evolution.

Species-Specific Activation of Transient Receptor Potential Ankyrin 1 by Phthalic Acid Monoesters.

Phthalic acid (PA) diesters are widely used in consumer products, as plasticizers, and are ubiquitous environmental pollutants. There is a growing concern about their adjuvant effect on allergic diseases. Although its precise mechanism remains unknown, possible involvement of transient receptor potential ankyrin 1 (TRPA1) has been suggested. Hence, in this study, the activation of human and mouse TRPA1s by a series of PA di- and monoesters was investigated using a heterologous expression system in vitro. Consequently, it was found that monoesters activated human TRPA1, where EC50 values were in the order of mono-hexyl > mono-heptyl > mono-n-octyl > mono-2-ethylhexyl > mono-isononyl and mono-isodecyl esters. Significant species differences in TRPA1 activation by PA monoesters were also discovered; PA monoesters activated human TRPA1 but not mouse TRPA1 in a concentration-dependent manner up to 50 µM. These findings suggest that PA esters may exert TRPA1-dependent adverse effects on humans, which have never been demonstrated in experimental animals.

Unfavorable cortical hypertrophy potentially predisposes to periprosthetic "axe splitter" fracture in a collarless polished curved triple-tapered cemented stem: The time-dependent radiographic change in five SC-stem cases.

BACKGROUND: The periprosthetic fracture of cemented polished tapered stems is occasionally called a "unique" or "axe splitter" fracture. However, there has been insufficient evidence regarding the association between the radiographic findings prior to incidence and this cumbersome fracture. To determine if there are any radiographic interpretations associated with this fracture pattern, we report the five SC-stem cases with total hip arthroplasty. METHODS: We investigate the patient characteristics and serial radiographs of five fracture cases and evaluate the time-dependent specific radiographical changes around the stem between pre-arthroplasty and fracture. RESULTS: Fractures developed at 3.5-6.4 years after surgery with low-grade injury or with no particular incentive. Femoral cortical hypertrophy at the distal medial side around the stem was observed in all cases before the development of fractures, at 2-6 years after primary surgery. The duration between cortical hypertrophy appearance to the development of fracture was 0.4-3.1 years. CONCLUSIONS: The appearance of this zone-specific cortical hypertrophy might play a key role in the occurrence of periprosthetic fractures. Further studies with larger sample sizes should be conducted to elucidate this eccentric periprosthetic fracture.

Isoform-Specific Quantification of Human Bitter Taste Receptor Transcripts Using Real-Time PCR Analysis.

Bitter taste receptors (TAS2Rs) are expressed by oral cavity cells in mammals and classically function as sensors for bitter compounds. There are 25 functional isoforms of human TAS2Rs, with individual bitter ligands. Each human TAS2R isoform is distributed in several tissues, such as the airway epithelia and gastrointestinal tract, and plays an important role in physiological functions. However, quantification of each isoform is difficult because of highly homologous sequences between some TAS2R isoforms. Therefore, differentiating the isoforms by their expression levels is suitable for clarifying the tissue-specific effects of bitter compounds. In this study, we developed a real-time quantitative PCR (qPCR) method to determine the expression of each TAS2R isoform. Using plasmid standards harboring each isoform, we confirmed that the current assay can quantify the gene expression of each isoform, with negligible interference from other isoforms. In addition, our methods can successfully discriminate between the mRNA expression of each isoform in human cell lines and tissues. Therefore, this qPCR method can successfully quantify the mRNA level of each TAS2R isoform. This method will contribute to a better understanding of the molecular mechanisms underlying the TAS2R ligand-activated signal transduction.