Protein and DNA oxidation in spinal injury: neurofilaments--an oxidation target.

This study measured the time courses of protein and DNA oxidation following spinal cord injury (SCI) in rats and characterized oxidative degradation of proteins. Protein carbonyl content-a marker of protein oxidation-significantly increased at 3-9 h postinjury and the ratio 8-hydroxy-2-deoxyguanosine/deoxyguanosine-an indicator of DNA oxidation-was significantly higher at 3-6 h postinjury in the injured cords than in the sham controls. This suggests that oxidative modification of proteins and DNA contributes to secondary damage in SCI. Densities of selected bands on coomassie-stained gels indicated that most proteins were degraded. Neurofilament protein (NFP) was particularly evaluated immunohistochemically; its light chain (NFP-68) was gradually degraded in nerve fibers, neuron bodies, and large dendrites following SCI. A mixture of Mn (III) tetrakis (4-benzoic acid) porphyrin (10 mg/kg)-a novel SOD mimetic-and nitro-L-arginine (1 mg/kg)-an inhibitor of nitric oxide synthase-injected intraperitoneally, increased NFP-68 immunoreactivity and the numbers of NFP-positive nerve fibers post-SCI, correlating NFP degradation in SCI to free radical-triggered oxidative damage for the first time. Therefore, blockage of protein and DNA oxidation in the secondary injury stage may improve long-term recovery-important information for development of the SCI therapies.

Association of a better kidney graft survival with the presence of circulating immune complexes before transplantation.

The presence of circulating immune complexes was investigated using the C1q-binding assay before and after kidney transplantation in 48 patients with renal failure. Circulating immune complexes were found in 54% of the patients. The presence of circulating immune complexes prior to grafting was associated with a better renal graft survival. Median survival time of grafts in patients with circulating immune complexes was more than 18 months as compared with 21/2 months in patients without such complexes. The incidence of circulating immune complexes in patients before transplant could not be related to the renal disease, viral infections, blood transfusions, or serum levels of lymphocytotoxic antibodies, IgG, or IgM.

Effect of factors inhibiting HLA-DR antibodies before transplantation on kidney graft survival.

Blood transfusions administered before renal allografts are known to enhance graft survival. Among alternative hypotheses proposed to explain this effect, one of the most attractive is the possible induction of antiidiotypic antibodies directed against the specific antigen-binding site of donor-specific antibodies. In order to determine if such blocking antibodies are generated after blood transfusions, serial serum samples obtained before transplantation from 44 kidney recipients were analyzed for the development of HLA-DR alloantisera inhibitory activity by a microcytotoxicity inhibition assay. A significant correlation was found between the presence of inhibitory factors before transplantation and prolonged graft survival. However a clear relation between the development of inhibitory factors and the administration of transfusions could not be established. In addition the sera of 36 patients were studied for the presence of circulating immune complexes (CIC) before grafting. The presence of CIC was clearly associated with that of inhibitory factors, and with a prolonged graft survival. Thus these studies provide support for the development of blocking (possibly antiidiotypic) antibodies to anti-MHC in human renal graft recipients.

Multiple site estimates of erythropoietin and renin in polycythemic kidney transplant patients.

The development of polycythemia after renal transplantation is a well known phenomenon and its etiology remains controversial. In particular, it is unknown whether inappropriate erythropoietin (EPO) production could be a reason. Utilizing a sensitive radioimmunoassay for EPO we have measured EPO concentrations in venous blood from native and grafted kidneys in three normocythemic and seven polycythemic patients. We found that (1) in our posttransplantation polycythemic patients there are inappropriately high systemic EPO levels, hence that posttransplantation polycythemia is related to EPO overproduction. (2) This high EPO production comes from the native kidneys. (3) There is a correlation between EPO and renin levels in the peripheral as well as in native and transplanted kidneys' venous samples.

Kinetics of cellular viability in warm versus cold ischemia conditions of kidney preservation. A biometric study.

We have determined the kinetics of the cellular viability ratio (CVR), defined as the number of living cells over the total cell count, in pig kidneys using propidium iodide and fluorescein diacetate staining, as a function of time and preservation conditions. The kidneys were preserved in warm or cold ischemia in order to mimic the conditions of transplantation from non-heart-beating donors or multiple removal with optimal preservation of the graft, respectively. To determine the CVR, the cells were obtained by a fine-needle aspiration biopsy, which minimizes the damage to the graft. A biometric analysis by regression enabled the determination of the time dependence for warm ischemia (CVR(t) = 80.0 x e(-0.733-t)(+2.7/-0.36)) and for cold ischemia (CVR(t) = 80.0 x e(-0.022-t)(+1.57/-0.64)) with a confidence interval of 95%. These master curves allow us to predict, under the described conditions, the CVR after a given ischemia time. The half-life of the cells can be deduced from the time-dependent CVR(t), and is 0.64 hr (38 min) for warm ischemia and 21.4 hr for cold ischemia. Further, the CVR for a given kidney can be used to assess its condition at removal: if the CVR is below 48% at 2 hr after removal, one can conclude that the organ has suffered a period of warm ischemia.

Effects of dialysate composition during hemodialysis on left ventricular function.

To determine the effects of dialysate composition during hemodialysis on left ventricular systolic and diastolic function, 12 patients treated by chronic hemodialysis (mean age 40.8 +/- 2.7 years), without overt heart disease, were studied by Doppler-echocardiography successively before and after acetate hemodialysis (AHD), bicarbonate hemodialysis (BHD), and acetate-free biofiltration (AFB). The three types of hemodialysis resulted in a comparable decrease of the body weight. Mean arterial blood pressure decreased by 5 mm Hg (NS), 8 mm Hg (NS) and 10 mm Hg (P < 0.05) during AHD, BHD and AFB, respectively. There was a significant increase of the heart rate and the shortening fraction of the left ventricular diameter after AHD, but not after BHD and AFB. Mean total systemic resistance increased by 20% after AHD, 18% after BHD and by 7% after AFB (all changes NS). During each type of hemodialysis there was a significant reduction of the peak velocity of the early diastolic rapid filling wave (peak E) without change of the peak filling velocity during atrial contraction (peak A). During AHD and BHD the pressure half-time of the early filling phase (TP/2) increased, and the velocity-integral of the early diastolic filling phase (E-area) decreased. However, TP/2 and E-area did not change significantly after AFB.(ABSTRACT TRUNCATED AT 250 WORDS)

L-type voltage-gated calcium channels modulate kainic acid neurotoxicity in cerebellar granule cells.

This study reports on the regulation of kainate neurotoxicity in cerebellar granule cells by calcium entry through voltage-gated calcium channels and by calcium release from internal cellular stores. Kainate neurotoxicity was prevented by the AMPA selective antagonist LY 303070 (10 microM). Kainate neurotoxicity was potentiated by cadmium, a general voltage-gated calcium channel blocker, and the L-type voltage-gated calcium channel blocker nifedipine. The antagonists of intracellular Ca2+ ([Ca2+]i) release, thapsigargin and ryanodine, were also able to potentiate kainate neurotoxicity. Kainate treatment elevated [Ca2+]i concentration with a rapid initial increase that peaked at 1543 nM and then declined to plateau at approximately 400 nM. Nifedipine lowered the peak response to 764 nM and the plateau response to approximately 90 nM. Thapsigargin also lowered the kainate-induced increase in [Ca2+]i (640 nM peak, 125 nM plateau). The ryanodine receptor agonist caffeine eliminated the kainate-induced increase in [Ca2+]i, and reduced kainate neurotoxicity. Kainate neurotoxicity potentiated by nifedipine was not prevented by RNA or protein synthesis inhibitors, nor by the caspase inhibitors YVAD-CHO and DEVD-CHO. Neither DNA laddering nor the number of apoptotic nuclei were increased following treatment with kainate and nifedipine. Increased nuclear staining with the membrane impermeable dye propidium iodide was observed immediately following kainate treatment, indicating a loss of plasma membrane integrity. Thus, kainate neurotoxicity is prevented by calcium entry through L-type calcium channels.

Bolus dose response characteristics of single chain urokinase plasminogen activator and tissue plasminogen activator in a dog model of arterial thrombosis.

Tissue plasminogen activator (t-PA) and single chain urokinase-plasminogen activator (scu-PA) are relatively "fibrin-specific" thrombolytic drugs with short plasma half lives of 6-8 minutes. Most treatment regimens with these agents utilize a bolus injection followed by continuous drug infusion, usually combined with anticoagulant therapy. The purpose of this study was to establish the dose-response characteristics for scu-PA and t-PA, when given as a single intravenous bolus injection, in a dog model of arterial thrombosis. Eight groups of 6 dogs each were given one of the following doses of scu-PA (mg/kg): 0.20, 0.50, 1.00, 2.00; or t-PA: 0.05, 0.10, 0.20; or an equivalent amount of saline (control group). All doses were given as a single bolus injection 60 minutes after formation of a totally occlusive femoral artery thrombus. Thrombolysis was measured by monitoring the continuous decrement of 125I activity from a radiolabelled thrombus. Ninety minutes after drug injection, all scu-PA treated dogs showed greater thrombolysis (30%, 45%, 56%, and 67%, respectively) than the control group (15%, p less than 0.01). The 0.10 and 0.20 mg/kg t-PA treated dogs showed greater thrombolysis (35% and 49%, respectively) than the control group (15%, p less than 0.01). Both scu-PA and t-PA caused a partial and dose-dependent decrease in alpha 2-antiplasmin activity but scu-PA caused a greater depletion (72% vs. 18%, respectively, p less than 0.05) at 60 minutes after the highest dose of drug administration. Both drugs showed a longer than expected thrombolytic effect based upon the known half lives. Neither drug caused significant changes in the prothrombin time, activated partial thromboplastin time, thrombin time, hematocrit, platelet count, or fibrin degradation product concentration. Single bolus injections of scu-PA and t-PA produce safe and effective thrombolysis in this dog model of arterial thrombosis.

Traumatic rupture of the urinary tract in a patient presenting nephrogenic diabetes insipidus associated with hydronephrosis and chronic renal failure: case report and review of the literature.

We report the case of a 34-year-old Japanese man suffering from a nephrogenic diabetes insipidus (NDI) associated with bilateral hydronephrosis, hydroureters and enlarged trabeculated bladder without obstruction. He also presented with chronic renal failure which has rarely occurred in similar cases. The patient was admitted after a traumatic rupture of the left urinary tract which had never been described until now in NDI. He was treated successfully by transient peritoneal and vesical drainages. This paper focuses on the very rare complication of chronic renal failure secondary to hydronephrosis in cases of NDI. The literature of this association is reviewed.

Hemostatic disturbances induced by two hollow-fiber hemodialysis membranes.

The effects on hemostasis of two high-flux membranes in hollow-fiber configuration, polyamide (PAM) and polyacrylonitrile (AN69), were analyzed in a cross-over study involving ten chronic hemodialyzed patients. Blood samples were obtained at arterial and venous sites of the extracorporeal circuit before dialysis and at 15, 30 and 180 min. Primary hemostasis: PAM induced an early significant drop in platelet counts, but at 180 min there was no longer any difference between membranes. Beta-thromboglobulin release by PAM was significantly higher at all time points. Coagulation: thrombin-antithrombin III complexes (TAT) and fibrinopeptide A increased significantly, the highest values being found with AN69. With both membranes the arterio-venous differences in TAT levels were negative throughout the sessions. Fibrinolysis: no significant differences were observed. In conclusion, both membranes induced hemostatic changes. Although these two hollow-fiber dialyzers look relatively similar, the changes observed were different, polyamide acting mainly on primary hemostasis and polyacrylonitrile on coagulation.

Comparison of two hemodialysis membranes, polyacrylonitrile and cellulose acetate, on complement and coagulation systems.

Two hemodialysis membranes, polyacrilonitrile (AN 69) and cellulose acetate (CA), were compared for their effects on complement and hemostasis. Two groups of 5 patients, in dialysis for more than 5 years, were successively dialysed for 4 weeks periods with each type of membrane. We measured C3a (complement activation), platelets and beta-thromboglobulin (platelet activation), thrombin-antithrombin III complexes and fibrinopeptide A (coagulation activation), using C-Reactive Protein as a control for dilution effects. As previously shown, activation of complement was more important with CA than with AN 69 (p less than 0.01). In contrast, activation of coagulation (increase in fibrinopeptide A and thrombin-antithrombin III complexes) was more pronounced with AN 69 than with CA. This study emphasizes the need to consider different biological systems when the bioincompatibility of a hemodialysis membrane is evaluated.

[Rheumatologic complications in patients treated with intermittent hemodialysis]. / Complications rhumatologiques des patients traités par hémodialyse périodique.

Long-term hemodialysis is complicated by rheumatological problems. They can vary from pain syndromes without clinical signs to severe destructive arthritis. The latter is often associated with severe disability. Its origin can be related to deposition of amyloid or synovial overloading with aluminium or iron. Different factors influence its occurrence, such as the type of dialysis membrane used or the quantity of aluminium consumed by these hemodialysed patients. The authors evaluated the frequency and the type of rheumatic disorders in the hemodialysis center of the HCU in Geneva. A comparison of these findings with previous reports is presented and the etiopathogenesis is discussed.