The localization of TGF-beta(1) mRNA and protein within tubular epithelial cells, along with its increased urinary excretion in patients with nephrotic syndrome, suggest the activation of these cells by filtered protein towards increased TGF-beta(1) production.
Raman spectroscopy is employed to investigate the temperature dependence of the E2g phonon mode of single-layer, few-layer (FL), and bulk hexagonal boron nitride (hBN) sheets, situated over Si/SiO2 (90 nm). Depending on the sample, two temperature regimes are recorded. In the low to mid range of the examined temperatures, the monolayer and FL samples exhibit significantly higher slopes compared to the thicker ones because of the thermal expansion of the underlying substrate. In the high-temperature region, all the examined samples show almost the same temperature slope, indicating slippage of the hBN sheets relative to the substrate and providing strong evidence that the slopes of the monolayer, FL, and bulk hBN are quite similar of about −0.020 cm–1/K. This is further justified from the full width at half-maximum versus T of the studied samples and the observed similarities of the thermal expansion coefficient (TEC) of one to three layers and bulk hBN, revealing a comparable level of anharmonicity for the E2g mode from the monolayer up to bulk hBN. Moreover, using a finite element method, we have determined the TEC of the underling substrate and the strain induced by TEC mismatch between the single-layer hBN and the substrate. Consequently, the intrinsic frequency shift of the E2g mode for the monolayer hBN upon temperature change is extracted. Finally, the vibrational response of monolayer hBN upon temperature is also examined by means of computational simulations, and satisfactory agreement with the experiment is obtained.
Background Long-term exposure of peritoneal membrane to bioincompatible dialysis solutions leads to structural changes and loss of ultrafiltration capability. Objective We studied the possible relationship between histologic change and the transport characteristics of peritoneal membrane and adequacy of dialysis in continuous ambulatory peritoneal dialysis (CAPD) patients. Patients and Methods The study included 18 CAPD patients (11 men, 7 women) who underwent a peritoneal biopsy either at initiation of treatment (group A, n = 9) or after a mean of 4 years on CAPD (group B, n = 9). The morphologic changes in the mesothelial cells and the vascular compartment and the thickness of the submesothelial collagenous zone were estimated and compared with observations from 6 patients with normal renal function who underwent biopsy of the parietal peritoneum during abdominal surgery. The relationship of the observed changes in CAPD patients to results from a peritoneal equilibration test (PET) and to adequacy of dialysis [total weekly creatinine clearance (CCr) and Kt/V urea] were also investigated. Results The main histologic changes in both groups of patients were loss of mesothelial cells and decrease in the normal mesothelial surface, thickening of the submesothelial collagenous zone, and presence of vascular hyalinosis. The thickness of the submesothelial collagenous zone in both groups of patients was significantly greater than that found in controls (410 μm and 580 μm vs 50 μm, p < 0.05). Although no significant difference was found between morphologic change in the peritoneal membrane of uremic patients starting on CAPD and those who had been on peritoneal dialysis (PD) for a mean period of 4 years, a trend was observed toward more severe lesions in the latter patients. The PET, CCr, and Kt/V urea were not significantly different in the two groups of patients. Those parameters also showed no significant changes when examined at initiation of CAPD and after a mean of 4 years of PD in the same patients (group B). No significant correlations were observed between the histologic changes and the PET, CCr, or Kt/V in both groups of patients. Conclusions Significant structural changes are observed in the peritoneal membrane of uremic patients, and those changes become worse with CAPD treatment. Structural changes are not followed by functional changes during the first 4 years on CAPD.
Objective To investigate the reason for increasing norepinephrine (NE) levels reported in continuous ambulatory peritoneal dialysis (CAPD) patients. Methods Norepinephrine was measured in the plasma and peritoneal dialysate of CAPD patients ( n = 22) and in the plasma and the urine of healthy subjects ( n = 20). It was also measured in the plasma of patients with chronic renal failure (CRF) ( n = 15) and patients on hemodialysis (HD) ( n = 15). Results It was found that NE was increased in CAPD patients compared with healthy individuals (687 ± 221 pg/mL vs 199 ± 25 pg/mL, p < 0.01). The daily removal of NE from the peritoneum of CAPD patients was lower compared with the amount of NE excreted in the urine of healthy subjects. Plasma NE increased after infusion of peritoneal dialysate. In 15 new patients on CAPD, it was found that NE plasma levels increased from 329 ± 67 pg/mL before initiation of dialysis, to 584 ± 173 pg/mL after 12 months of treatment ( p < 0.01). Finally, plasma NE in CAPD patients (687 ± 221 pg/mL) was significantly higher compared with the already increased levels in patients on HD or with CRF (406 ± 143 pg/mL and 378 ± 142 pg/mL, respectively). Conclusions It is concluded that CAPD in patients with end-stage renal disease is responsible for a progressive increase of plasma norepinephrine.
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