Options in uraemia therapy for diabetics with end-stage renal disease

In many countries, diabetic renal disease has become, or will soon become, the single most common cause of end-stage renal disease (ESRD). End-stage renal failure (ESRF) in type-2 diabetic patients is increasing worldwide. Incidence of ESRF caused by diabetic nephropathy (DN) in 1996 in the USA was 41.7% and prevalence was 32.4%. ESRD and ESRF caused by DN was 10%, 5-15% in different haemodialysis centres in adults in the year 2000 in the Republic of Macedonia. In this review article we discuss options in uraemia therapy for diabetics with ESRD. Assessment and treatment of a diabetic with ESRD must be highly individualized. Haemodialysis (HD) has emerged as the most common treatment for all forms of renal failure including diabetic nephropathy. In diabetics patients with ESRD, dialysis is started early at creatinine clearance as high as 15-20 ml/min, at serum creatinin levels as low as 3-5 mg/dl. The first choice of HD access in diabetics is an autologous a-v fistula of the Cimino-Brescia type. The A-V fistula should be created several months before starting HD when creatinine clearance is above 20-25 ml/min. When peritoneal dialysis (PD) is selected, advance planning should ensure that a suitable peritoneal catheter is in situ 2-4 weeks before starting dialysis. HD procedures should be with low ultrafiltration rates and prolonged duration of dialysis sessions. The ultrafiltration in diabetics should not exceed more than 500-600 ml/h on HD. This means dialysis sessions of more than 4h and, in larger patients, of more than 5h HD three times per week. Renal transplantation (RT) is a safe and effective treatment modality for diabetic subjects with ESRD. Cardiovascular disease and serious infections are the major causes of death in haemodialysed and transplanted diabetics. Despite recent improvement, rehabilitation of HD diabetics continues to be inferior to that of non-diabetics. Improvement of survival is a matter of reduction of cardiovascular death and infection.     

Effect of dialysis on oxidative stress in uraemia

It has been postulated that dialysis of patients with chronic renal failure (CRF) is associated with increased lipid peroxidation which may contribute to vascular and other complications of the syndrome. In the present study, a specific and precise technique [ferrous oxidation in xylenol orange (FOX) assay] was used to measure plasma lipid hydroperoxides (ROOHs) in three groups of uraemic patients. Patients were either studied before starting dialysis (n = 12) or on continuous ambulatory peritoneal dialysis (CAPD, n = 12) or haemodialysis (HD, n = 36) and compared to healthy controls (n = 20). Plasma ROOHs were markedly elevated in HD patients compared with the controls (7.01 +/- 2.9 microM versus 4.25 +/- 2.05 microM; P < 0.005, Mann-Whitney test). Plasma ROOH concentrations in the CAPD patients were increased but not significantly higher than controls (5.36 +/- 3.56 microM versus 4.25 +/- 2.05 microM). By contrast, no differences in ROOH levels were found between controls and predialysis patients. There was no difference in plasma thiobarbituric acid reactive substances (TBARS) between control and the three CRF groups. Absolute and cholesterol standardised plasma alpha-tocopherol levels were lower in the patients (whether they were on dialysis or not) than in the controls (18.62 +/- 6.88 microM versus 22.73 +/- 5.33 microM; P < 0.01 and 1.99 +/- 1.88 microM/mM versus 5.25 +/- 1.0 microM/mM; P < 0.0005, respectively). This study provides direct evidence that enhanced oxidative stress in CRF patients is related to the dialysis treatment rather than the disease itself. Further studies will be necessary to establish the relationships between plasma measures of oxidative stress and cardiovascular complications in CRF patients under dialysis and whether treatment with antioxidants may reduce oxidative stress or reverse adverse effects associated with dialysis.     

The effects of peritoneal dialysis and hemodialysis on serum tumor necrosis factor-alpha, interleukin-6, interleukin-10 and C-reactive-protein levels

BACKGROUND: Markers of an acute phase reaction, such as C-reactive protein (CRP) or tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6, are predictive for cardiovascular morbidity and mortality in normal subjects and in chronic renal failure patients. In this study, we aimed to investigate serum TNF-alpha, IL-6, IL-10 and CRP levels in continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD) patients. MATERIALS AND METHODS: Serum levels of TNF-alpha, IL-6, IL-10 and CRP levels were measured in 30 patients who were just diagnosed with end-stage renal failure and treated, with 16 CAPD (nine female, seven male) and 14 HD (eight female, six male) patients, before CAPD or HD treatment and after 3 months from the beginning of CAPD or HD in patients with no clinical signs of infection. The control groups were 20 healthy persons of similar age and sex. Serum levels of TNF-alpha, IL-6, IL-10 and CRP were measured by enzyme-linked immunosorbent assay in stable CAPD and HD patients and in healthy persons. RESULTS: The mean serum levels of TNF-alpha, IL-6, IL-10 and CRP showed no significant differences between the CAPD and HD patients for the beginning values and the third month of treatment. However, serum TNF-alpha, IL-6, IL-10 and CRP levels were higher than the control group in the CAPD and HD patients regarding the beginning values and the third month of treatment (p < 0.001). CONCLUSIONS: CAPD and HD of the renal replacement therapy have no effects on serum CRP and cytokines.     

Effect of human endopeptidase 24.11 ("enkephalinase") on IL-1-induced thymocyte proliferation activity

Endopeptidase 24.11 (enkephalinase) is a membrane bound protease involved in the degradation of neuropeptides and hormones. Its presence on cells of the thymus and lymph nodes suggests a possible role in the inactivation of immune system mediators. IL-1 (both purified IL-1 beta and an IL-1-rich supernatant) bioactivity, as measured in the thymocyte proliferation assay, was found to disappear upon incubation with endopeptidase 24.11. This inactivation was dependent on both incubation time and enzyme concentration. IL-1 beta was protected by the presence in the incubation medium of phosphoramidon, a specific inhibitor of endopeptidase 24.11. After incubation of IL-1-rich supernatant with the enzyme, the thymocyte proliferation activity could be restored by adding purified IL-1 beta to the samples, indicating that neither the enzyme nor the buffer had any toxic effect on thymocyte proliferation. In the same experimental conditions, IL-2 activity was not destroyed by endopeptidase 24.11.     

Effect of glucose concentration on peritoneal inflammatory cytokines in continuous ambulatory peritoneal dialysis patients

OBJECTIVE: It is known that glucose concentrations of peritoneal dialysis solutions are detrimental to the peritoneal membrane. In order to determine the effect of glucose concentration on cytokine levels of peritoneal fluid of continuous ambulatory peritoneal dialysis (CAPD) patients, a cross-sectional study was performed. METHODS: Nine non-diabetic CAPD patients participated in two 8-h dwell sessions of overnight exchanges in consecutive days, with 1.36% and 3.86% glucose containing peritoneal dialysis solutions (Baxter-Eczacibas). Peritoneal dialysis fluid tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 levels were measured. RESULTS: TNF-alpha levels after 1.36% and 3.86% glucose used dwells were 23+/-14 pg/ml and 28+/-4 pg/ml, respectively (p=0.78). The IL-6 levels were 106+/-57 pg/ml and 115+/-63 pg/ml (p=0.81), respectively. CONCLUSION: In our in vivo study we found that the glucose concentration of the conventional lactate-based CAPD solution has no effect on basal IL-6 and TNF-alpha levels of peritoneal fluid. Further in vivo studies with non-lactate-based CAPD solutions are needed in order to determine the effect of glucose concentration per se on cytokine release.     

Increased levels of plasma 8-EPI-PGF2α in patients with end stage renal failure

Summary

F₂-isoprostanes are a series of prostaglandin-F₂ like compounds specifically derived from peroxidation of arachidonic acid by a mechanism independent of the cyclooxygenase pathway. Of these, 8-epi PGF_2α is shown to be a potent vasoconstrictor. In this study, we have analysed plasma 8-epi PGF_2α as a marker of oxidative stress in patients with end stage renal failure (ESRF) undergoing haemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). Plasma F₂-isoprostanes were isolated by solid-phase extraction on a C₁₈ followed by an NH₂ cartridge. Quantitative analysis of the F₂-isoprostanes as pentafluorobenzyl (PFB) ester/trimethylsilyl (TMS) ether derivatives was carried out by gas chromatography-electron capture mass spectrometry. For 34 individuals with ESRF, the mean level of esterified 8-epi PGF_2α was 0.58 ± 0.22 M; range 0.21–1.16 nM. 8-epi PGF_2α concentration in the patient groups was markedly higher (P<0.0005 by separate variance t-test) than that of control subjects (n=15) 0.28 ± 0.17 nM; range 0.02–0.63 nM. There was no difference in levels of 8-epi PGF_2α in plasma from patients undergoing HD or CAPD, nor was there any association with age, plasma lipids or plasma creatinine. These data provide direct evidence of increased oxidative stress in individuals with ESRF. This marker should be useful in clinical studies examining the degree of oxidative stress in vivo and the therapeutic impact of antioxidants.     

Changes in the tumor marker concentration in female patients with hyper-, eu-, and hypothyroidism

The levels of 6 circulating tumor markers were evaluated in a total of 131 female subjects with altered thyroid states; 36 normal subjects, 46 hyperthyroid patients with Graves' disease, and 49 primary hypothyroid patients. The mean CEA concentration was observed to be significantly higher (p less than 0.02) in hypothyroid patients than in normal and hyperthyroid patients (1.1 +/- 0.1 ng/ml, 0.8 +/- 0.1 ng/ml and 0.8 +/- 0.1 ng/ml, respectively). Similarly, the mean serum CA 125 concentration in hypothyroid patients was higher (p less than 0.02) than in normal and hyperthyroid patients (13.0 +/- 2.6 U/ml, 7.6 +/- 1.1 U/ml and 5.5 +/- 0.8 U/ml, respectively), and the mean serum CA 15-3 concentration in hypothyroid patients was significantly higher than in normal subjects (p less than 0.01) and hyperthyroid patients (p less than 0.001) (16.2 +/- 0.9 U/ml, 13.9 +/- 0.6 U/ml and 10.6 +/- 0.5 U/ml, respectively). No statistical difference was found in mean CA 19-9 in the three subject groups. AFP in the hypothyroid patients (3.6 +/- 0.3 ng/ml) was significantly higher (p less than 0.05) than in normal subjects (2.6 +/- 0.2 ng/ml) and hyperthyroid patients (1.7 +/- 0.2 ng/ml) (p less than 0.01). On the other hand, serum ferritin was low in the hypothyroid patients (65.9 8.0 ng/ml) and significantly increased (69.1 +/- 9.0 ng/ml) (p less than 0.02) with the normalization of thyroid function. In hyperthyroidism, serum ferritin (70.2 +/- 7.0 ng/ml) was significantly higher than in the hypothyroid patients (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

A radioimmunoassay for the measurement of aminopeptidase (microsomal) in human serum

A radioimmunoassay for the measurement of aminopeptidase (microsomal) (AP) in human serum was developed by using antiserum to human kidney AP. AP purified from kidney and AP present in normal serum and in serum from a patient with obstructive jaundice gave parallel logit-log transformation lines, suggesting immunological identity. The mean concentration of AP in normal serum (n = 104) was 1.33 +/- 0.30 (mean +/- SD) micrograms/ml. Men had significantly higher serum AP levels (1.41 +/- 0.30 micrograms/ml) (p less than 0.005) than women (1.24 +/- 0.28 micrograms/ml). Serum AP levels of patients with hepatoma (2.26 +/- 0.87 micrograms/ml) and cancer of the pancreas or the biliary tract (2.90 +/- 0.67 micrograms/ml) were significantly higher (p less than 0.005) than those of normal subjects. Patients with acute and chronic hepatitis (2.06 +/- 0.66 micrograms/ml) also had significantly higher serum AP levels (p less than 0.005) than normal subjects. In pregnant women, however, the increase in AP activity without the increase in AP concentration showed that the increased AP activity was due to an enzyme other than AP. The enzyme levels and activities in normal serum as well as in patients' sera were significantly correlated (normal, r = 0.77; patients, r = 0.95). Based on the specific activity of AP purified from human plasma, the enzyme activity splitting L-alanyl-beta-naphthylamide is due almost completely to AP in normal subjects and in patients with hepatobiliary diseases.     

D-Amino acids in chronic renal failure and the effects of dialysis and urinary losses

Summary Total D-amino acids were measured in plasma for 20 non-dialysed patients (creatinine clearance < 12 ml/minute), 20 on CAPD, 20 on haemodialysis and 20 normals. Plasma D-tyrosine and D-phenylalanine were measured in 8 of each group by HPLC. Total D-amino acids, D-tyrosine and D-phenylalanine were significantly greater for patients than normals. D-amino acids and D-tyrosine correlated with creatinine and were decreased during HD. During dialysis, the mean losses for D-tyrosine and D-phenylalanine were similar, about 0.2 mg/CAPD exchange and 3 mg/4 hour haemodialysis (i.e. 2% of the total amino acid, as in plasma). Clearance was unaffected by stereochemical configuration. Urinary losses/24 hour in the non-dialysed patients were 0.35 mg D-tyrosine and 0.25 mg D-phenylalanine. Clearance for D-phenylalanine was greater than for the L-enantiomer. Increases in D-amino acids in renal failure are probably due to depletion of D-amino acid oxidase, but may be enhanced by a D-amino acid rich diet, peptide antibiotics and D-amino acid oxidase inhibiting drugs and metabolites. Possible toxic effects need further investigation.     

Radioimmunoassay of 5-androstene-3 beta,17 beta-diol in plasma and in breast cyst fluid

A simple and reliable radioimmunoassay for the determination of 5-androstene-3 beta, 17 beta-diol in peripheral plasma and in breast cyst fluid, after a chromatography on Celite microcolumn has been described and evaluated. The antiserum used was raised in rabbits injected with dehydroepiandrosterone-15 alpha-(O-carboxymethyl)-bovine serum albumin. In men below 40 years of age the levels ranged from 0.85 to 2.80 ng/ml (mean +/- SEM: 1.52 +/- 0.11; n = 24) and from 0.50 to 2.20 ng/ml (mean +/- SEM: 0.93 +/- 0.09; n = 20) in men aged between 41 and 62 years. The mean level was significantly different (P less than 0.001) between the 2 groups. A significant correlation (r = -0.56; P less than 0.01) was demonstrated between age and all male levels. In females the mean plasma level was in the follicular phase: 0.81 +/- 0.07 ng/ml (range: 0.40-1.50; n = 17; age: 19-41 years) and in the luteal phase: 0.83 +/- 0.05 ng/ml (range: 0.40-1.30; n = 29; age: 18-43 years). No cyclical change and no correlation with age could be evidenced. A significant difference (P less than 0.001) was shown between females and the young male group. In breast cyst fluid the levels ranged from 0.05 to 13.70 ng/ml (mean +/- SEM: 2.36 +/- 0.86; n = 20) whereas the sulfate concentrations ranged from 75 to 7500 ng/ml (mean +/- SEM: 1891 +/- 565; n = 15), thus demonstrating very wide inter-individual variations.     

High concentration of neutral endopeptidase (enkephalinase E.C. 3.4.24.11) in a malignant tumor: rat hepatoma 3924A

The activity of the membrane-bound neutral endopeptidase 24.11 was low in the normal liver (21 +/- 3 pmol/h/mg protein, mean +/- SE) but it increased 56-fold in rapidly-growing rat hepatoma 3924A. The identity of the enzyme in the tumor was established by immunoprecipitation and by using a specific inhibitor of neutral endopeptidase. The endopeptidase concentration in the differentiating and regenerating liver was lower than in normal tissue, 39 and 8% of the corresponding control. The activity of a plasma membrane marker enzyme carboxypeptidase M in the normal liver was 1.0 +/- 0.2 nmol/h/mg protein, it increased about 2-fold in the rapidly-growing hepatoma and in the differentiating liver, but was unchanged in regenerating liver. The function of the strikingly increased neutral endopeptidase activity in the rapidly growing hepatoma may relate to activation of autocrine or exocellular growth factors or to inactivation of cell proliferation-inhibitory factors. Such a biochemical change should confer selective advantages to the cancer cells.     

Independence of progesterone blockade of the luteinizing hormone surge in ewes from opioid activity at naloxone-sensitive receptors.

Fifteen ovariectomized ewes were treated with implants (s.c.) creating circulating luteal progesterone concentrations of 1.6 +/- 0.1 ng ml-1 serum. Ten days later, progesterone implants were removed from five ewes which were then infused with saline for 64 h (0.154 mol NaCl l-1, 20 ml h-1, i.v.). Ewes with progesterone implants remaining were infused with saline (n = 5) or naloxone (0.5 mg kg-1 h-1, n = 5) in saline for 64 h. At 36 h of infusion, all ewes were injected with oestradiol (20 micrograms in 1 ml groundnut oil, i.m.). During the first 36 h of infusion, serum luteinizing hormone (LH) concentrations were similar in ewes infused with saline after progesterone withdrawal and ewes infused with naloxone, but with progesterone implants remaining (1.23 +/- 0.11 and 1.28 +/- 0.23 ng ml-1 serum, respectively, mean +/- SEM, P greater than 0.05). These values exceeded circulating LH concentrations during the first 36 h of saline infusion of ewes with progesterone implants remaining (0.59 +/- 0.09 ng ml-1 serum, P less than 0.05). The data suggested that progesterone suppression of tonic LH secretion, before oestradiol injection, was completely antagonized by naloxone. After oestradiol injection, circulating LH concentrations decreased for about 10 h in ewes of all groups. A surge in circulating LH concentrations peaked 24 h after oestradiol injection in ewes infused with saline after progesterone withdrawal (8.16 +/- 3.18 ng LH ml-1 serum).(ABSTRACT TRUNCATED AT 250 WORDS)     

Continuous ambulatory peritoneal dialysis after the honeymoon: review of experience in Newcastle 1979-84.

Two hundred and twenty nine consecutive patients (129 men, mean age 45) were reviewed 12 to 65 months after starting treatment with continuous ambulatory peritoneal dialysis (CAPD) from January 1979 to December 1983. They received CAPD for a mean of 19.8 (range 0.5-62) months. Actuarial patient survival was 79% at 24 months and 72% at 36 months. Half of the 46 deaths were related to cardiovascular disease, while eight patients died of abdominal complications, including three patients with peritonitis. Peritonitis occurred at a rate of one episode per 35 patient weeks, and 88% of episodes were cleared by one or more courses of antibiotics. This still left peritonitis as the commonest cause of failure of CAPD, leading to a permanent change of treatment in 44 patients and temporary interruption in a further 25. CAPD remains a reasonable medium term treatment in chronic renal failure. Despite the persisting problem of peritonitis the results are comparable with those achieved by haemodialysis, and CAPD has become the treatment of first choice for end stage renal failure in Newcastle. In younger patients judged unsuitable for transplantation and facing long term dialysis, however, haemodialysis is preferred.     

Plasma Free Metanephrine and Normetanephrine Levels are Increased in Patients with Chronic Kidney Disease

ObjectivePatients with impaired renal function, particularly those on dialysis, frequently exhibit high blood pressure and hemodynamic instability, which often lead to pheochromocytoma assessment. Our objective was to assess plasma free metanephrine (MN) and normetanephrine (NMN) in chronic kidney disease patients (CKD) with or without dialysis.MethodsIn this prospective observational study we performed enzyme-linked immunosorbent assays (ELISAs) to evaluate plasma free MN and NMN in 48 CKD patients (15 with stage 3-5 CKD without dialysis, 26 on hemodialysis [HD], and 7 continuous ambulatory peritoneal dialysis [CAPD]), 30 patients with histologically proven pheochromocytoma, and 43 hypertensive patients. Adrenal masses were ruled out by abdominal computed tomography (CT) scans in all CKD and control hypertensive patients.ResultsAll 3 CKD groups (HD, CAPD, and CKD without dialysis) had significantly higher plasma free MN and NMN levels than the control hypertensive group (P < .0055). HD and CAPD patients had significantly lower plasma free NMN (P < .0055), but free MN levels were not significantly different than those observed in pheochromocytoma patients. In patients with HD, CAPD, and CKD without dialysis, plasma free MN and NMN were higher than manufacturer’s upper limits of normal in 57.7% and 28.5%, 13.3% and 61.5%, and 85.7% and 26.6%, respectively. Regression models showed that the number of dialysis years was significantly correlated with plasma free MN (r = 0.615, P < .001) but not free NMN.ConclusionPlasma free MN and NMN levels are frequently elevated in CKD patients, particularly in those on dialysis. Plasma free MN levels significantly overlap with the range in pheochromocytoma patients and correlate with the number of years on dialysis. (Endocr Pract. 2014;20:139-144)     

Adipocyte-derived hormones in heroin addicts: the influence of methadone maintenance treatment

Heroin addiction markedly affects the nutritional and metabolic status and frequently leads to malnutrition. The aim of our study was to compare circulating concentration of adipose tissue-derived hormones leptin, adiponectin and resistin in 12 patients with heroin addiction before and after one-year methadone maintenance treatment with the group of 20 age- and body mass index-matched healthy subjects. Basal serum leptin and adiponectin levels in heroin addicts were significantly decreased (3.4+/-0.4 vs. 4.5+/-0.6 ng/ml and 18.9+/-3.3 vs. 33.9+/-3.1 ng/microl, respectively; p 0.05) while serum resistin concentrations were increased compared to healthy subjects (10.1+/-1.2 vs. 4.6+/-0.3 ng/ml; p 0.05). Moreover, positive correlation of serum leptin levels with body mass index was lost in the addicts in contrast to control group. One year of methadone maintenance treatment normalized serum leptin, but not serum adiponectin and resistin concentrations. In conclusion, circulating concentrations of leptin, adiponectin and resistin are markedly altered in patients with chronic heroin addiction. These alterations appear to be relatively independent of nutritional status and insulin sensitivity.     

On the possible use of the serum level of 7 alpha-hydroxycholesterol as a marker for increased activity of the cholesterol 7 alpha-hydroxylase in humans

The possibility was investigated that the serum level of 7 alpha-hydroxycholesterol can be used as a marker for cholesterol 7 alpha-hydroxylase activity. Six patients with gallstone disease were found to have a mean level of 7 alpha-hydroxycholesterol in serum of 30 +/- 4 ng/ml (mean +/- SEM) as measured by isotope dilution-mass spectrometry, using deuterated 7 alpha-hydroxycholesterol as internal standard. After treatment with cholestyramine in a dose of 8 g twice daily for 2-3 weeks preoperatively, the serum level increased to 128 +/- 20 ng/ml (P less than 0.001). Eight other patients with gallstone disease had a mean level of 7 alpha-hydroxycholesterol in serum of 29 +/- 7 ng/ml. Treatment with chenodeoxycholic acid, 15 mg per kg body weight per day for 3-4 weeks before surgery, decreased the mean level to 20 +/- 7 ng/ml (P greater than 0.05). The activity of the cholesterol 7 alpha-hydroxylase in liver biopsies taken during operation was found to be 38 +/- 5 pmol/min per mg of protein in the group of patients treated with cholestyramine and 1.3 +/- 0.5 pmol/min per mg in the group of patients treated with chenodeoxycholic acid. Liver biopsies from a group of untreated patients (n = 13) had a mean cholesterol 7 alpha-hydroxylase activity of 7.6 +/- 1.5 pmol/min per mg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Soluble tumour necrosis factor-alpha receptor I and interleukin-6 as markers of activity in thyrotoxic Graves' disease.

Autoimmune thyroid diseases are thought to be mediated by pro-inflammatory cytokines such as TNFalpha and IL-6. Serum levels of cytokines may indicate activity levels of immune functions. We investigated serum levels of IL-6 and of the soluble receptor of TNFalpha in patients with newly diagnosed onset of Graves' hyperthyroidism. The predominantly female group consisted of 39 patients, mean fT4 was 47.6 pg/ml (normal values 7.5=19.0 pg/ml). After diagnosis, all patients were treated with anti-thyroid drugs. Soluble Tumour Necrosis Factor Receptor I (TNF-RI) serum levels were found significantly increased (mean 3.7+/-1.3 ng/ml; p<0,01) compared to a matched group of apparent healthy individuals (mean sTNF-RI 1.8+/-0.5 ng/ml) and to a matched group of patients with treated Graves' disease (mean sTNF-RI 1.9+/-0.6 ng/ml). When IL-6 was assessed only 4 of the 39 patients exhibited increased serum levels. Our finding may indicate that sTNF-RI and possibly its ligand, TNFalpha, could play an important role in the onset of the acute stage of Graves' disease.     

Single dose recombinant human erythropoietin reduces transforming growth factor beta in patients on chronic haemodialysis.

Short-term effects of recombinant human erythropoietin on serum levels of transforming growth factor beta-1, interleukin 1-alpha, interleukin 3, interferon gamma, and tumour necrosis factor alpha in patients with chronic renal failure on chronic haemodialysis were investigated. Recombinant human erythropoietin was applied subcutaneously in a dose of 75 IU/kg on 19 patients. Serum levels of transforming growth factor beta-1, interleukin 1-alpha, interleukin 3, interferon gamma, tumour necrosis factor alpha and erythropoietin, red blood cell parameters: red blood cell count, haemoglobin, haematocrit, and erythrocyte indices were determined before and after recombinant human erythropoietin single application. Transforming growth factor beta-1 serum levels were decreased after recombinant human erythropoietin (22.70 +/- 1.51 ng/ml versus 18.77 +/- 1.70 ng/ml (p < 0.01). None of the other investigated parameters was influenced significantly by recombinant human erythropoietin. Recombinant human erythropoietin in patients with chronic renal failure on chronic haemodialysis may influence anaemia not only through its stimulating effect on erythropoiesis, but also by direct oxygen-independent decrease of at least one of the negative regulators of erythropoiesis--the transforming growth factor beta.     

Peptidases in dog-ileum circular and longitudinal smooth-muscle plasma membranes. Their relative contribution to the metabolism of neurotensin

We established the content in neuropeptide-metabolizing peptidases present in highly purified plasma membranes prepared from the circular and longitudinal muscles of dog ileum. Activities were measured by the use of fluorigenic substrates and the identities of enzymes were confirmed by the use of specific peptidase inhibitors. Endopeptidase 24.11, angiotensin-converting enzyme, post-proline dipeptidyl aminopeptidase and aminopeptidases were found in both membrane preparations. Proline endopeptidase was only detected in circular smooth muscle plasma membranes while pyroglutamyl-peptide hydrolase was not observed in either tissue. The relative contribution of these peptidases to the inactivation of neurotensin was assessed. The enzymes involved in the primary inactivating cleavages occurring on the neurotensin molecule were as follows. In both membrane preparations, endopeptidase 24.11 was responsible for the formation of neurotensin-(1-11) and contributed to the formation of neurotensin-(1-10); a recently purified neurotensin-degrading neutral metallopeptidase was also involved in the formation of neurotensin-(1-10). A carboxypeptidase-like activity hydrolysed neurotensin at the Ile12-Leu13 peptide bond, leading to the formation of neurotensin-(1-12). Proline endopeptidase and endopeptidase 24.15 only occurred in circular muscle plasma membranes, yielding neurotensin-(1-7) and neurotensin-(1-8), respectively. In addition, the secondary processing of neurotensin degradation products was catalyzed by the following peptidases. In circular and longitudinal muscle membranes, angiotensin-converting enzyme converted neurotensin-(1-10) into neurotensin-(1-8) and tyrosine resulted from the rapid hydrolysis of neurotensin-(11-13) by bestatin-sensitive aminopeptidases. A post-proline dipeptidyl aminopeptidase activity converted neurotensin-(9-13) into neurotensin-(11-13) in circular muscle plasma membranes. The mechanism of neurotensin inactivation occurring in these membranes will be compared to that previously established for membranes from central origin.     

Circulating neuron-specific enolase in medullary thyroid cancer

The utility of determining circulating neuron-specific enolase (NSE) in medullary thyroid carcinoma was assessed in 25 patients followed up for a mean period of 45.6 months. In 5 patients tested before any treatment serum NSE concentrations were in the normal range. After total thyroidectomy abnormally high serum NSE concentrations (more than 9.8 ng/ml) were found in 1/3 patients with normal calcitonin (CT) in remission, in 2/10 with elevated CT levels but no evidence of disease and in 9/12 with elevated CT levels and documented metastases. The mean (+/- SD) NSE value in this last group was 12.0 +/- 12.6 ng/ml, significantly higher than in the other groups (p less than 0.005). The time course of serum NSE in patients with long follow-up seems to indicate that serum NSE rises when a large tumor mass is present and usually parallels the pattern of circulating CT. Effective treatment of the metastases is usually followed by reduction of serum NSE. Thus, serum NSE can serve as an additional humoral marker for medullary thyroid carcinoma, its elevation being associated with important metastatic involvement and with a poor prognosis of the tumor.