Molecular mechanisms and physiological functions of mitophagy.

Degradation of mitochondria via a selective form of autophagy, named mitophagy, is a fundamental mechanism conserved from yeast to humans that regulates mitochondrial quality and quantity control. Mitophagy is promoted via specific mitochondrial outer membrane receptors, or ubiquitin molecules conjugated to proteins on the mitochondrial surface leading to the formation of autophagosomes surrounding mitochondria. Mitophagy-mediated elimination of mitochondria plays an important role in many processes including early embryonic development, cell differentiation, inflammation, and apoptosis. Recent advances in analyzing mitophagy in vivo also reveal high rates of steady-state mitochondrial turnover in diverse cell types, highlighting the intracellular housekeeping role of mitophagy. Defects in mitophagy are associated with various pathological conditions such as neurodegeneration, heart failure, cancer, and aging, further underscoring the biological relevance. Here, we review our current molecular understanding of mitophagy, and its physiological implications, and discuss how multiple mitophagy pathways coordinately modulate mitochondrial fitness and populations.

A ubiquitin-proteasome pathway degrades the inner nuclear membrane protein Bqt4 to maintain nuclear membrane homeostasis.

Aberrant accumulation of inner nuclear membrane (INM) proteins is associated with deformed nuclear morphology and mammalian diseases. However, the mechanisms underlying the maintenance of INM homeostasis remain poorly understood. In this study, we explored the degradation mechanisms of the INM protein Bqt4 in the fission yeast Schizosaccharomyces pombe. We have previously shown that Bqt4 interacts with the transmembrane protein Bqt3 at the INM and is degraded in the absence of Bqt3. Here, we reveal that excess Bqt4, unassociated with Bqt3, is targeted for degradation by the ubiquitin-proteasome system localized in the nucleus and Bqt3 antagonizes this process. The degradation process involves the Doa10 E3 ligase complex at the INM. Bqt4 is a tail-anchored protein and the Cdc48 complex is required for its degradation. The C-terminal transmembrane domain of Bqt4 was necessary and sufficient for proteasome-dependent protein degradation. Accumulation of Bqt4 at the INM impaired cell viability with nuclear envelope deformation, suggesting that quantity control of Bqt4 plays an important role in nuclear membrane homeostasis.

Single-Nucleus RNA Sequencing Reveals Loss of Distal Convoluted Tubule 1 Renal Tubules in HIV Viral Protein R Transgenic Mice.

Although hyponatremia and salt wasting are common in patients with HIV/AIDS, the understanding of their contributing factors is limited. HIV viral protein R (Vpr) contributes to HIV-associated nephropathy. To investigate the effects of Vpr on the distal tubules and on the expression level of the Slc12a3 gene, encoding the sodium-chloride cotransporter (which is responsible for sodium reabsorption in distal nephron segments), single-nucleus RNA sequencing was performed on kidney cortices from three wild-type (WT) and three Vpr transgenic (Vpr Tg) mice. The percentage of distal convoluted tubule (DCT) cells was significantly lower in Vpr Tg mice compared with WT mice (P < 0.05); in Vpr Tg mice, Slc12a3 expression was not significantly different in DCT cells. The Pvalb+ DCT1 subcluster had fewer cells in Vpr Tg mice compared with those in WT mice (P < 0.01). Immunohistochemistry revealed fewer Slc12a3+Pvalb+ DCT1 segments in Vpr Tg mice. Differential gene expression analysis between Vpr Tg and WT samples in the DCT cluster showed down-regulation of the Ier3 gene, which is an inhibitor of apoptosis. The in vitro knockdown of Ier3 by siRNA transfection induced apoptosis in mouse DCT cells. These observations suggest that the salt-wasting effect of Vpr in Vpr Tg mice is likely mediated by Ier3 down-regulation in DCT1 cells and loss of Slc12a3+Pvalb+ DCT1 segments.

Application of non-negative matrix factorization in oncology: one approach for establishing precision medicine.

The increase in the expectations of artificial intelligence (AI) technology has led to machine learning technology being actively used in the medical field. Non-negative matrix factorization (NMF) is a machine learning technique used for image analysis, speech recognition, and language processing; recently, it is being applied to medical research. Precision medicine, wherein important information is extracted from large-scale medical data to provide optimal medical care for every individual, is considered important in medical policies globally, and the application of machine learning techniques to this end is being handled in several ways. NMF is also introduced differently because of the characteristics of its algorithms. In this review, the importance of NMF in the field of medicine, with a focus on the field of oncology, is described by explaining the mathematical science of NMF and the characteristics of the algorithm, providing examples of how NMF can be used to establish precision medicine, and presenting the challenges of NMF. Finally, the direction regarding the effective use of NMF in the field of oncology is also discussed.

The polymyxin-B direct hemoperfusion OPTimal Initiation timing with Catecholamine PMX-OPTIC study: A multicenter retrospective observational study.

BACKGROUND: Polymyxin-B direct hemoperfusion (PMX-DHP) is an endotoxin adsorption column-based blood purification therapy. Since one of the most potent effects of PMX-DHP is blood pressure elevations, it may be the most effective when it is introduced at the time when the need for vasopressors is the greatest, which, in turn, may reduce mortality. METHODS: A multicenter retrospective study was conducted at 24 ICUs in Japan. In each ICU, the 20 most recent consecutive cases of septic shock treated with PMX-DHP were analyzed. The duration between the time of the peak vasopressive agent dose, expressed as the noradrenaline equivalent dose (NEq), and the time of PMX initiation was evaluated. The primary outcome was 28-day mortality, and a multivariable analysis was performed to investigate factors associated with mortality. RESULTS: A total of 480 septic shock patients were included in the analysis. Among all patients, the 28-day mortality group was older, more severely ill, and had a higher body mass index. The NEq peak and NEq on PMX-DHP initiation were both higher in deceased patients. Regarding the timing of PMX-DHP initiation from the NEq peak, -4 << 4 h had more survivors (229/304, 75.3%) than ≤-4 h (50/75, 66.7%) and ≥4 h (66/101, 65.4%) (p = 0.085). When -4 << 4 h was assigned as a reference, the timing of PMX-DHP initiation from the NEq peak of ≤-4 h had an odds ratio of 1.96 (1.07-3.58), p = 0.029, while ≥4 h had an odds ratio of 1.64 (0.94-2.87), p = 0.082 for 28-day mortality, in the multivariable regression analysis. A spline curve of the relationship between the probability of death and the timing of PMX-DHP initiation from the NEq peak showed a downward convex curve with a nadir at timing = 0. The odds ratios of the timing of PMX-DHP initiation other than -4 << 4 h were significantly higher in an older age, male sex, lower BMI, more severe illness, and higher oxygenation. CONCLUSIONS: The induction of PMX-DHP at the time of the peak vasopressor dose correlated with lower mortality. PMX-DHP is one of the options available for elevating blood pressure in septic shock, and its initiation either too early or late for shock peak may not improve the outcome.

Pre-milling technique improves the accuracy of posterior femoral condyle cut and reduces the tibial recut in Oxford unicompartmental knee arthroplasty.

BACKGROUND: Recuts are sometimes needed in UKA because of inadequate posterior tibial cut thickness. We investigated the efficacy of a pre-milling technique (the first milling is done prior to the posterior condylar cut) in Oxford unicompartmental knee arthroplasty to enhance bone cut thickness and to minimize tibial recuts. PATIENTS AND METHODS: Between January 2021 and January 2023, a posterior condyle cut was made before milling in 213 knees in 152 patients (conventional group), while the pre-milling technique was used in 198 knees in 140 patients (pre-milling group). The thickness of the posterior condyle and the rate of tibial recuts were compared between the groups. RESULTS: The bone cut thickness was thinner in the conventional group than in the pre-milling group in small-size (4.7 mm ± 0.6 mm and 5.0 mm ± 0.6 mm, P = 0.0001) and in medium-size (5.1 mm ± 0.5 mm and 5.4 mm ± 0.5 mm, 0.0001) femoral components, whereas there was no difference in large-size femoral components. However, the thickness was still less than the component thickness (5.17 mm for small, 5.57 mm for medium and 6.17 mm for large) in both groups. Tibial recuts were more prevalent in the conventional group than in the pre-milling group (14 knees, 7%, 3 knees 2%, P = 0.002). CONCLUSIONS: The pre-milling technique was found to increase the bone cut thickness in small and medium femoral components, reducing the need for tibial recuts. Further research is warranted to optimize the pre-milling technique and to investigate its long-term impact on patient outcomes.

Propensity of the tight mid-flexion and loose flexion gap despite the adjustment of extension and flexion gaps in Oxford unicompartmental knee arthroplasty: retrospective study.

PURPOSE: A well-balanced joint gap is necessary in Oxford unicompartmental knee arthroplasty (OUKA) to prevent mobile-bearing dislocation. While the gaps between 20° (extension) and 100° (flexion) are precisely adjusted using the incremental mill system, there has been insufficient evaluation of gaps in other angles. We hypothesized that the gap is not always the same in other angles. This retrospective study aimed to evaluate the gap in full-extension (0°), mid-flexion (60°) and deep flexion (130°) for comparison with those in extension and flexion gaps. METHODS: We evaluated 119 knees in 83 patients (51 females, 31 males, aged 71.9 years). The full-extension and mid-flexion gaps were compared with the extension gap, and the deep flexion gap was contrasted with the flexion gap. Each gap was classified into isometric, tight or loose, for evaluation of contributing factors. RESULTS: Although the full-extension gap tended to be isometric (45%), the mid-flexion tended to be tight (48%), whereas the deep-flexion was loose in most knees (84%) (P = 0.002). The tight mid-flexion and loose deep flexion gap pattern accounted for 44% of the total knees, especially so with smaller femoral components (P = 0.004). CONCLUSION: Our results highlight the propensity of tight mid-flexion and loose flexion gap despite the adjustment of extension and flexion gaps in OUKA. Although the effect of such a minor gap imbalance is still unknown, the pattern was more prevalent in patients with smaller-sized femoral components. Use of a larger femoral component may equalize the gap throughout the motion arc.

Antisense oligonucleotides ameliorate kidney dysfunction in podocyte-specific APOL1 risk variant mice.

Coding variants (named G1 and G2) in Apolipoprotein L1 (APOL1) can explain most excess risk of kidney disease observed in African American individuals. It has been proposed that risk variant APOL1 dose, such as increased risk variant APOL1 level serves as a trigger (second hit) for disease development. The goal of this study was to determine whether lowering risk variant APOL1 levels protects from disease development in a podocyte-specific transgenic mouse disease model. We administered antisense oligonucleotides (ASO) targeting APOL1 to podocyte-specific G2APOL1 mice and observed efficient reduction of APOL1 levels. APOL1 ASO1, which more efficiently lowered APOL1 transcript levels, protected mice from albuminuria, glomerulosclerosis, tubulointerstitial fibrosis, and renal failure. Administration of APOL1 ASO1 was effective even for established disease in the NEFTA-rtTA/TRE-G2APOL1 (NEFTA/G2APOL1) mice. We observed a strong correlation between APOL1 transcript level and disease severity. We concluded that APOL1 ASO1 may be an effective therapeutic approach for APOL1-associated glomerular disease.

Trans patellar tendon sagittal tibial cut for lateral unicompartmental knee arthroplasty-location of the split- CT simulation study.

BACKGROUND: In lateral unicompartmental knee arthroplasty (UKA), a sagittal cut is often performed through the patellar tendon (PT). Although the approach is likely widely used, it has not been described in detail, especially regarding the site of the split. This study aimed to clarify where the split should be made. METHODS: This single-center retrospective cohort study included 49 consecutive patients and 51 knees with lateral osteoarthritis. Using preoperative computed tomography, we measured the distance from the medial edge of the PT to the intersection of the PT and the sagittal cutting line, defined as a line parallel to the Akagi's line and passing the tip of the lateral tibial spine. RESULTS: The sagittal cut line passed a mean of 45 ± 11% of the patellar tendon width from the PT medial edge. CONCLUSIONS: The tendon split should be made just medial to the center of the PT because it is where the sagittal cut line for lateral UKA passes.

Approximately 41% of knees have a looser gap in full extension than in 20° flexion after Oxford unicompartmental arthroplasty.

INTRODUCTION: In Oxford unicompartmental knee arthroplasty (OUKA), the flexion and extension gaps should be adjusted to prevent mobile-bearing dislocation. The extension gap is recommended to be evaluated in the 20° flexion position to avoid underestimation due to tension of the posterior capsule. However, we have become aware of a looser gap in full extension than in 20° flexion in some instances. MATERIALS AND METHODS: We retrospectively investigated 83 knees in 60 patients who underwent OUKA between January and June 2020. During surgery, the extension gaps were measured in both full extension and 20° flexion. The knees were classified into two groups: the gap was looser in full extension (0° group), and the gap was equal or looser in 20° flexion than in full extension (20° group). The hip-knee-ankle angle (HKAA), the lateral distal femoral angle (LDFA), the medial proximal tibia angle (MPTA), the posterior tibial slope angle (PTSA), and the last spigot size were also measured and compared between the groups. RESULTS: There was looseness in approximately 41% of knees (34 out of 83 knees) in full extension. In the knees in the 0° group, the last spigot size was significantly smaller (median 1 and 2, P < 0.01). However, there were no significant differences in the HKAA, MPTA, LDFA or PTSA between the groups. CONCLUSIONS: Approximately 41% of knees have a looser gap in full extension than in 20° flexion after OUKA. Further investigation is needed to better understand which extension gap should be used in such cases, and to find the contributing factors in loose full extension gap other than the size of the last spigot.