Inhibition of platelet-derived growth factor pathway suppresses tubulointerstitial injury in renal congestion.

OBJECTIVE: Increased central venous pressure in congestive heart failure is responsible for renal dysfunction, which is mediated by renal venous congestion. Pericyte detachment from capillaries after renal congestion might trigger renal fibrogenesis via pericyte-myofibroblast transition (PMT). Platelet-derived growth factor receptors (PDGFRs), which are PMT indicators, were upregulated in our recently established renal congestion model. This study was designed to determine whether inhibition of the PDGFR pathway could suppress tubulointerstitial injury after renal congestion. METHODS: The inferior vena cava between the renal veins was ligated in male Sprague-Dawley rats, inducing congestion only in the left kidney. Imatinib mesylate or vehicle were injected intraperitoneally daily from 1 day before the operation. Three days after the surgery, the effect of imatinib was assessed by physiological, morphological and molecular methods. The inhibition of PDGFRs against transforming growth factor-ß1 (TGFB1)-induced fibrosis was also tested in human pericyte cell culture. RESULTS: Increased kidney weight and renal fibrosis were observed in the congested kidneys. Upstream inferior vena cava (IVC) pressure immediately increased to around 20 mmHg after IVC ligation in both the imatinib and saline groups. Although vasa recta dilatation and pericyte detachment under renal congestion were maintained, imatinib ameliorated the increased kidney weight and suppressed renal fibrosis around the vasa recta. TGFB1-induced elevation of fibrosis markers in human pericytes was suppressed by PDGFR inhibitors at the transcriptional level. CONCLUSION: The activation of the PDGFR pathway after renal congestion was responsible for renal congestion-induced fibrosis. This mechanism could be a candidate therapeutic target for renoprotection against renal congestion-induced tubulointerstitial injury.

Impact of preoperative factors on catheter position in peritoneal dialysis: a prospective cohort study.

BACKGROUND: Peritoneal dialysis (PD) catheter malposition is one of the complications of renal replacement therapy. This study aimed to determine the preoperative factors that cause PD catheter malposition. METHODS: The prospective cohort study included patients who underwent PD catheter insertion surgery and had preoperative and postoperative computed tomography scans. We compared preoperative and intraoperative factors between the lower depth catheter group (group L) and upper depth catheter group (group U), and preoperative and intraoperative factors between the posterior catheter group (group P) and anterior catheter group (group A). In addition, PD catheter obstruction requiring surgical intervention in each group was followed up for 1 year. RESULTS: A total of 150 patients were categorized into groups L (n = 77) and U (n = 73), or groups P (n = 107) and A (n = 43). Body mass index (BMI; P = 0.02), subcutaneous fat area (P = 0.02), and rate of previous abdominal surgery (P = 0.01) were significantly lower in group L than in group U. In terms of anterior catheter position, females had more-anterior catheter positions. The time to PD catheter obstruction requiring surgical intervention (P = 0.03) was significantly lower in group U than in group L. CONCLUSIONS: High BMI, high subcutaneous fat area, high subcutaneous fat thickness, and previous abdominal surgery were identified as preoperative factors that cause the PD catheter to have an upper depth. Female sex was a preoperative influencing factor for the anterior PD catheter position.

Safety of peritoneal dialysis catheter surgery under dexmedetomidine and local anesthesia for elderly patients in Japan: a single-center prospective cohort study.

BACKGROUND: The number of patients aged ≥ 75 years and who need renal replacement therapy is steadily increasing. The study aimed to determine the safety of open surgery for peritoneal dialysis (PD) catheter placement in such patients. METHODS: This prospective cohort study included patients who underwent PD catheter placement by open surgery under dexmedetomidine (DEX) and local anesthesia at our institution from January 2015 to February 2021. Patients were divided into the following two groups according to age at the time of surgery: ≥ 75 years (group A) and < 75 years (group B). We compared the perioperative and postoperative complications (i.e., time to the first PD-related peritonitis and catheter obstruction requiring surgical intervention within 1 year) between the groups. RESULTS: A total of 118 patients were categorized into groups A (n = 65) and B (n = 53). No significant intergroup differences were observed in the postoperative fever, total duration of surgery, perioperative hemoglobin decrease, changes in the white blood cell count and C-reactive protein, postoperative catheter leakage, postoperative hospital stay, time to the first PD-related peritonitis, and catheter obstruction requiring surgical intervention within 1 year. CONCLUSIONS: The surgery for PD catheter placement by open surgery under DEX and local anesthesia in elderly patients is safe and effective.

The Impact of Preoperative Risk Factors on Peritoneal Dialysis-Related Peritonitis: A Single-Center Prospective Study in Japan.

Background and Objectives: Peritoneal dialysis (PD)-related peritonitis is a critical problem. However, preoperative risk factors for PD-related peritonitis have not been established. Thus, we aimed to determine the preoperative risk factors for PD-related peritonitis. Materials and Methods: This is a single-center prospective observational study. All peritonitis episodes during the study period were recorded, and preoperative and intraoperative clinical parameters were compared between patients with and without peritonitis to examine risk factors for PD-related peritonitis. Furthermore, subcutaneous and abdominal fat volumes were evaluated using computed tomography. Results: Among a total of 118 patients, 24 patients developed peritonitis. The proportion of male patients (83% vs. 61%, p = 0.04), body mass index (25 vs. 22 kg/m2, p = 0.04), and subcutaneous fat area (120 vs. 102 cm2, p = 0.01) were significantly higher and the proportion of patients living with family members (75% vs. 94%, p = 0.02) was significantly lower in the peritonitis group than in the non-peritonitis group. There were no significant differences in age, operation method, surgeon experience, previous abdominal surgery, medical history of diabetic nephropathy, serum albumin level, and renal function between the two groups. Conclusions: Male patients with high subcutaneous fat who are living alone might be at higher risk of PD-related peritonitis. These characteristics might be useful in risk assessment and patient education before PD induction.

Visualization of myelinated fiber bundles orientation during brain slice preparation by reflection polarized light microscopy.

Polarized light imaging (PLI) enables detecting the orientation of myelinated axon bundles in brain slices at microscopic resolution without histological staining. However, standard PLI requires labor-intensive procedures such as mounting brain cryosections on slide glasses. We developed an optical system that does not require a mounting procedure for PLI. Specifically, we developed an optical system to perform PLI in reflection mode (rPLI) instead of employing transmitted light as in standard PLI. We integrated this rPLI system with a conventional vibratome slicer whose cutting blade surface is a mirror. This combination allowed PLI measurements directly during the slicing procedure at room temperature. Thus, mounting procedure for PLI is not necessary. As a proof-of-concept experiment, a perfusion-fixed brain of a mouse was embedded in gelatin-containing agar and cut serially at 40~200 µm intervals. The slicing procedure was temporarily halted after each cut to capture the PLI images of the slice on the reflecting blade surface while the slice was still held up by the agar block. The orientation of the fiber bundle estimated with this method agreed with the results obtained from previous reports. Combination of a popular vibratome slicer and our rPLI system that uses versatile and inexpensive optical components would increase popularity of PLI and facilitates connectome studies at microscopic resolution. RESEARCH HIGHLIGHTS: Polarized light imaging (PLI) of brain slices was realized by using reflected light (rPLI) instead of transmitted light. The rPLI method allows detecting the myelinated fiber bundle orientation during slice preparation.