Possible involvement of urokinase-type plasminogen activator release from human peripheral blood lymphocytes in the pathophysiology of chronic allograft nephropathy.

BACKGROUND: Little is known of the fibrinolytic host immune mechanisms responsible for induction of chronic allograft nephropathy (CAN), defined as a loss in glomerular filtration rate (GFR) caused by tubular atrophy and interstitial fibrosis, often with fibrous intimal thickening in the small arteries. However, chronic rejection has been reported to be associated with decreased activity of the fibrinolytic system. In our previous study, [Deamino-Cys1, D-Arg8]-vasopressin (dDAVP) induced urokinase-type plasminogen activator (uPA) release from human peripheral T lymphocytes via arginine vasopressin (AVP) V2-receptor-mediated reaction enhanced by an AVP V1-receptor antagonist. Therefore, we examined the level of uPA released from peripheral T lymphocytes by AVP in transplant patients with CAN in comparison with control groups. PATIENTS AND METHODS: In this study, we evaluated in vitro uPA releasing activity of lymphocytes obtained from renal allograft patients with well-functioning grafts (n = 9), CAN (n = 5), or acute rejection episodes (n = 5) compared with lymphocytes from healthy volunteers with normal renal function (n = 12) or patients with renal insufficiency (n = 5). RESULTS: Lymphocytes prepared from patients with chronic allograft nephropathy showed a significantly lower increase in uPA release induced by the combination of the V1-receptor antagonist and dDAVP compared with those from the other groups. CONCLUSION: This finding suggested that a decrease in uPA release from human peripheral blood lymphocytes by AVP-related peptides may be potentially involved in the pathophysiology of CAN.

Effect of sample thickness on bite force studied with a multiple-point sheet sensor.

The aim of this study was to investigate the relationship between thickness of sample food and bite force. We designed a new sensor that can detect the pressure distribution between the incisor and molar teeth on one side, and the contact area between the food samples and the teeth. The force and contact area were directly measured in real time using the multiple-point sheet sensor, which is a very thin and flexible pressure-sensing device. Silicone rubber blocks were used as a sample food and were chewed with incisors and molars by 10 healthy women. The peak force, contact area, duration and impulse were greater between the incisors for a thicker specimen. The active pressure, defined as the ratio of the force to contact area, at peak was similar for different thicknesses. In contrast, with a 2 mm thick sample, the peak force and force related parameters were greatest in molar chewing. The force, contact area and duration were greater for molar chewing cycles than incisor ones. We verified that the thickness of samples influenced the chewing force of humans and the effects differed between incisors and molars.

Involvement of platelet-derived growth factor and histocompatibility of DRB 1 in chronic renal allograft nephropathy.

BACKGROUND: The role of activated T cells in graft arteriosclerosis, which is observed in chronic renal allograft nephropathy, and the involvement of major histocompatibility complex (MHC) incompatibility remain to be determined. We examined the effect of T lymphocytes that were obtained from renal transplant patients undergoing chronic rejection treated with cyclosporine (CsA) on platelet-derived growth factor (PDGF)-induced proliferation of cultured human vascular smooth muscle cells (SMC) and compared the proliferation activity of T lymphocytes with MHC incompatibility, especially DRB 1 mismatch. METHODS: Renal transplant patients with continued allograft function, who survived more than 1 year after transplantation, were recruited. Chronic rejection was documented by graft-biopsy findings together with increasing serum creatinine levels (10-20% per year). After the incubation of supernatant (conditioning medium) of cultured T cells from CsA-treated renal transplant patients with chronic rejection (n=18) and with normal renal function (n=14) as control, normal subjects (n=11) and chronic hemodialysis (HD) patients (n=5) with cultured SMC in the presence or absence of PDGF, DNA synthesis (3H-thymidine uptake) of SMC was examined. The in vitro effects of CsA on DNA synthesis of cultured SMC were also evaluated. RESULTS: The supernatant of cultured T cells from renal transplant patients with chronic rejection stimulated PDGF-induced DNA synthesis of SMC in a dose-dependent manner, showing significant enhancement as compared with control transplant patients, normal subjects, and chronic HD patients. The supernatant itself did not significantly stimulate DNA synthesis of SMC. No significant in vitro stimulation of CsA on DNA synthesis was observed. The supernatant of T cells obtained from recipients undergoing chronic rejection with two DRB 1 mismatches showed significantly higher enhanced activity of PDGF-induced DNA synthesis than the supernatant from those recipients without mismatch of DRB 1. On the other hand, no significant correlation of the enhanced activity by T cell supernatant to HLA A and B mismatch numbers was observed. CONCLUSIONS: Growth factor-promoting factors(s) derived from activated T cells associated with MHC class II DR expression, which promotes PDGF-induced proliferation of SMC, exists in renal transplant patients with chronic renal allograft nephropathy, and is probably involved in arteriosclerosis of the graft kidney.

Inhibitory effect of protein hydrolysates on calcium carbonate crystallization.

Protein hydrolysates, prepared by enzymatic digestion of soybean protein and egg white albumin using several proteases, inhibited the crystal growth of calcium carbonate. Each hydrolysate showed different inhibitory activities, suggesting the key role of peptide structures in the inhibition. The deamidation of protein hydrolysates by glutaminase increased not only the inhibitory activity toward the crystal growth of calcium carbonate but also the resistance of the hydrolysates against peptic digestion. Furthermore, the addition of sodium chloride, citric acid, or lactose into the reaction mixture enhanced the inhibitory activity. The protein hydrolysates inhibited both nucleation and crystal growth of calcium carbonate and also affected the crystal morphology.

Immunohistochemical study of human advanced glycation end-products (AGE) and growth factors in cardiac tissues of patients on maintenance dialysis and with kidney transplantation.

Cardiovascular disease is one of the most common complications of dialysis and renal transplant patients, and high levels of AGE are present in end-stage renal failure. To address the potential involvement of AGE and growth factors in the pathophysiology of cardiovascular complications, we performed immunostaining using cardiac tissues from autopsy cases of patients on maintenance dialysis (10 cases), long-term surviving renal transplant patients with functioning grafts (8 cases), control subjects with normal renal function (7 cases) and non diabetic subjects with mild renal insufficiency (8 cases). We used two types of AGE-antibodies, 6D12 [monoclonal anti-AGE antibody, recognizing N epsilon-(carboxymethyl) lysine(CML)-modified AGE] (oxidative AGE) and non-CML-PA [polyclonal, not recognizing CML], and antibodies against PDGFs, PDGF receptors and TGF beta. Positive 6D12 staining was observed in the coronary arterial walls and in macrophages. The accumulation of 6D12-reactive AGE in the coronary arterial walls of maintenance dialysis patients was significantly greater than that of control subjects (p < 0.05). Renal transplantation significantly reduced this accumulation (p < 0.05). On the other hand non-CML-PA mainly detected AGE in intracardiac arterioles and neural tissues. There was little difference in the accumulation of non-CML-AGE among the four groups. PDGFs and PDGF receptors were mainly detected in vascular endothelial cells and infiltrating cells of cardiac tissues of renal transplant patients, but not of maintenance dialysis patients. TGF beta was not detected in cardiovascular tissue of transplant patients. Our results indicated that the accumulation of oxidative AGE (CML-AGE) in the cardiac vascular tissue is one of the factors for cardiovascular complications of maintenance dialysis patients, and also that renal transplantation has a reducing effect on CML-AGE accumulation. PDGFs may be involved in the cardiovascular complications after renal transplantation.

[Role of tumor necrosis factor-alpha in insulin sensitivity and effect of low protein diet on the TNF-alpha response in patients with diabetic renal failure].

In patients with diabetic renal failure, attention must be paid to the prevention of atherosclerosis as well as the preservation of renal function. Insulin resistance is one of the important risk-factors of atherosclerosis and the involvement of tumor necrosis factor-alpha (TNF-alpha) has been shown in the pathogenesis of insulin resistance in some diseases. A low-protein diet (LPD) is recommended for patients with advanced renal disease, but a large proportion of the total caloric intake is supplied from carbohydrates and fat in LPD. Therefore, we designed a study to determine: (1) the effect of TNF-alpha on insulin sensitivity, and (2) the effect of LPD on the TNF-alpha response and the risk factors of atherosclerosis, such as insulin sensitivity and lipid metabolism, in patients with diabetic renal failure. Insulin sensitivity was measured by an euglycemic hyperinsulinemic clamp technique and serum TNF-alpha level and in vitro release of TNF-alpha from peripheral blood mononuclear cells (PBMCs) was measured in patients with diabetic renal failure. A significant negative correlation was observed between lipopolysaccharide-stimulated TNF-alpha release from PBMCs and insulin sensitivity (r = -0.58, p < 0.05). Secondly, risk factors of atherosclerosis were measured before and two weeks after the introduction of LPD in patients with diabetic renal failure. LPD did not have any significant effect on insulin sensitivity, the production of TNF-alpha by PBMCs, lipid metabolism and glucose metabolism. These results indicate that: (1) TNF-alpha derived from PBMCs might affect insulin sensitivity in patients with diabetic renal failure, and (2) LPD does not have any significant effect on the risk factors of atherosclerosis.

[Diurnal alteration of platelet-free Ca2+ in subjects with normal renal function and patients undergoing CAPD].

We examined the relation of diurnal alteration of platelet-free Ca2+ to blood pressure and plasma vasoactive substances in 6 subjects with normal renal function (N group) (with both normal GFR and normal urine concentration, and with the renal biopsy finding of minor glomerular change) and 7 patients undergoing CAPD (CAPD group), then evaluated the pathophysiological difference in diurnal variations between both groups and the effect of native kidney function. Diurnal values of platelet basal-free Ca2+ concentration in N showed a positive correlation with the corresponding PRA levels. On the other hand, in CAPD they showed a positive correlation with the corresponding levels of plasma AVP. The larger increases in platelet-free Ca2+ concentration due to thrombin stimulation were observed in the daytime and the smaller increases in the nighttime in the N groups. The thrombin-induced changes showed a positive correlation with the diurnal levels of mean blood pressure in N (p < 0.004). However, in contrast, in CAPD the increase in platelet-free Ca2+ due to thrombin tended to be larger in the nighttime and showed a negative correlation with the daily mean blood pressure levels (p < 0.004). These findings suggest that there might be differences in the regulation of intracellular-free Ca2+ dynamics and the diurnal variation between subjects with normal renal function and patients undergoing CAPD. Those differences could affect the progression of vascular disturbance in CAPD patients.