Effect of age on protein catabolic rate, morbidity, and mortality in uraemic patients with adequate dialysis

To test the validity of the assumption that the protein catabolicrate (PCRn g/kg/day) is dependent on the normalized dose ofdialysis (Kt/V urea), and to try to define the charactensticsof the patients in the undefined domain A of the mechanisticmap of the National Cooperative Dialysis Study (NCDS), whichshould include patients with adequate amount of dialysis butinadequate PCRn, urea kinetic model ling was performed over12 months on 85 patients undergoing haemodialysis All the patientswere man aged to maintain a Kt/V urea 0.9. During the entireperiod of study the total number of hospitalizations and thenumber of days of hospitalization were recorded. Total serumproteins and serum albumin concentrations were measured at thestart and at the end of the study. The results of the studyshow that there was no correlation between Kt/V and PCRn norbetween Kt/V and patient's age, but there was a strong inversecorrelation between age and PCRn (r=0.578; P <0.0001). Furtherdivision of the patients into four groups according to age showedthat the lowest values of PCRn were for the group of patients75 years old. Twelve patients with PCRn0.8 and Kt/V0.9 wereincluded in domain A of the mechanistic map. Eleven (92%) ofthese 12 patients were years old. No correlations were foundbetween the total number of hospitalizations, the total daysof hospitalization, Kt/V, time on HD, body weight and PCRn bymultiple regression analysis, while the inverse correlationbetween PCRn and age was confirmed. Body weight, total serumproteins and serum albumin concentration remained stable throughoutthe study. However, the basal serum albumin was less in thegroup of patients 75 years old. We conclude that if an adequateamount of dialysis is delivered, the protein intake becomesindependent of the quantity of dialysis and dependent on otherfactors not yet known. In this situation, the age of the patientsexerts a great negative influence on PCRn, particularly in patients75 years old. In the 12 patients from the whole group with Kt/V0.9 and PCRn 0.8g/kg/day (domain A of the mechanistic map),we could find no differences in death, hospitalization rate,or duration of hospitaliza flon compared to the others. Thereduced PCRn in the oldest patients does not affect body weight,total serum protein, and serum albumin concentrations over time.This suggests that these patients might do well even with lessprotein intake.     

Interleukin-8 in chronic renal failure and dialysis patients

A total of 105 patients participated in this study, including10 with chronic glomerulonephritis with normal renal function(CGN patients), 36 uraemic patients (CRF patients), 19 continuousambulatory peritoneal dialysis patients (CAPD) without peritonitis,three CAPD patients with peritonitis, 37 patients undergoingchronic haemodialysis (HD) divided into short-term HD, 15 patients;medium-term HD, 12 patients; and long-term HD, 10 patients.IL-8 and two other proinflammatory cytokines, IL-6 and TNFweretested using a specific immunoassay. IL-8, IL-6, and TNFc serumlevels were significantly increased in patients with chronicrenal failure compared to their levels in normal individuals(P<0.000l, P<0.05 and P<0.000l respectively). The mostpronounced incre ment in IL-8, IL-6 and TNF serum levels wasobserved in CAPD patients (P<0.000l). CAPD patients withoutperitonitis showed relatively low levels of IL-8 or IL-6 inperitoneal dialysate effluents (PDE), whereas PDE-TNF were notdetectable in almost all patients tested. Patients with peritonitisshowed very high serum and PDE levels of IL-8, IL-6 and TNF.The clinical recovery from peritonitis was characterized bya rapid fall in IL-8, IL-6 and TNF in serum and dialysate. HDpatients showed a significant increase in serum levels of IL-8and also IL-6 and TNFcompared to normal individuals (P<0.05,P<0.05 and P<0.01 respectively). HD duration influencedserum levels of IL-8 and TNF since they were significantly higherin short-term HD patients than medium- or long-term HD patients(respectively P<0.05, P<0.00l for IL-8, and P<0.01,P<0.001 for TNF Pre-HD IL-6 levels were not influenced byHD duration. No major modification of IL-8 serum levels couldbe evinced after and before HD sessions in the short-term group,but concentrations of this cytokine were significantly higherafter HD in medium- and long-term HD patients (P<0.05, P<0.0lrespectively). In contrast, HD session did not influence IL-6and TNF levels. We conclude that the cytokine profile is perturbedin uraemia and during dialysis, and that this should be consideredas an inflammatory status.     

Age and gender-related incidence of chronic renal failure in a French urban area: a prospective epidemiologic study

OBJECTIVE.: To determine the age- and gender-related incidence of chronicrenal failure in a French urban area. METHODS.: Prospective study of adult patients newly identified as havingestablished, chronic renal failure defined by serum creatinine(Scr) 200 µmol/l, with the cooperation of all nephrologyand dialysis units in the Ile de France district (10,660,000inhabitants) during a 1-year period. RESULTS.: 2775 patients (1780 males, 995 females) were referred with Scr200 µmol/l between July 1991 and June 1992, an overallincidence of 260/million population. 847 had advanced renalfailure (Scr 500 µmol/l) and 541 patients (19.5%) were75 years of age. The age-related incidence was 92, 264, 523and 619/million population in the age groups 20–39, 40–59,60–74 and 75 years old, respectively. The annual incidencewas twice as high in males than in females up to 75 years andthree times as high in patients 75 years (1124 vs 356/millionpopulation). Based on the proportion of patients reaching end-stagerenal failure within one year of referral, the minimal estimationof the need for supportive therapy is 81/million/year. CONCLUSIONS.: This epidemiological study in a large French urban area indicatesan incidence of 260 patients per million population annuallyreferred to nephrology units for chronic renal failure definedby Scr 200 µmol/l, with a marked preponderance of malesand a dramatic increase of incidence with age in both genders.     

The equivalent renal urea clearance: a new parameter to assess dialysis dose

BACKGROUND.: Currently the total (dialytic plus renal) urea clearance (KT)is computed as Kt/V plus the equivalent Kt/V (KT/V_KR) providedby the renal urea clearance (KR). However, KT/V_KR is computedwith two different formulae, by Gotch and Keshaviah respectively.Moreover Teschan suggested a weekly KT, that is a multiple ofKeshaviah's KT. We suggest the equivalent renal urea clearance(EKR), that kinetically quantifies the ‘time-averagedKT’ and is independent of treatment type and schedule. METHODS.: Computer simulation has been used to analyse the relationshipbetween EKR, as corrected for urea volume (EKRc), and Kt/V.Data from 66 HD patients, of whom eight were on once-weeklyand 11 on twice-weekly HD, had been used to compare EKR withcurrent KTs. RESULTS.: For each individual schedule, the relationship between EKRcand Kt/V is linear and each ml/min of KR increases EKR by thesame amount. For instance, for thrice-weekly HD patients, EKRc=1+10xKt/V:so that, the critical Kt/V values of 0.8 and 1.0 correspondto EKRc values of 9.0 and 11 ml/min respectively, independentlyfrom treatment type and schedule. As to the clinical data, allonce- and twice-weekly patients had a significant KR and excellentclinical status, but most of them had 9EKRc<11 ml/min. Afterappropriate reconciliation of units, it has been found thatkinetic KT was overestimated by about 10–12% (range, 2–23%)by Keshaviah and Teschan's KT, and by about 2–7% (range,0.3–15%) by Gotch's KT. CONCLUSIONS.: EKRc can account for KR and provide guidelines for all typesof dialysis treatments: as far as urea is concerned, dialysisadequacy should require EKRc11 ml/min. However, it is likelythat EKRc9 ml/min could suffice for patients with a substantialresidual renal function.     

Expression and function of fibronectin receptors on peripheral mononuclear cells in IgA nephropathy

The ß1 integrin family, major adhesive receptors forthe extracellular matrix (ECM), have been reported to be presentin normal and diseased kidneys. Attachment of glomerular cellsto ECM is mediated by ß1 integrins. Several membersof the ß1 integrins are referred to as VLA (very lateactivation) antigens. Peripheral mononuclear cells also expressVLA antigens in both resting and activated states. We examinedthe expression and function of VLA antigens on peripheral lymphocytesand monocytes in patients with IgA nephropathy using monoclonalantibodies (mAbs) specific for VLA -chains. Peripheral lymphocytesfrom patients with IgA nephropathy expressed VLA-4 and 5, butnot VLA-1 2 or 3. Peripheral monocytes from patients with IgAnephropathy expressed VLA-2 4 and 5, but not VLA-1 or 3. Theexpression of VLA adhesive receptors was observed in healthyindividuals. Adhesion assay to fibronectin revealed augmentedadhesion of mononuclear cells in IgA nephropathy (P<0.05),and this increased adhesion was inhibited by mAbs to VLA-4 and5. The expression of ß1 integrins in IgA nephropathywas similar to that of healthy individuals, but the functionof these molecules in terms of adhesion to fibronectin thoughVLA-4 and VLA-5 is increased in these patients. These findingssuggest that the activation of fibronectin receptors on peripheralmononuclear cells plays an important role in the pathogenicprocess of IgA nephropathy.     

Lipoprotein (a) in patients on maintenance haemodialysis and continuous ambulatory peritoneal dialysis

Lipoprotein (a) concentrations and apoprotein (a) isoforms weremeasured in 99 haemodialysis and 79 peritoneal dialysis patientsand compared with a normal population. Peritoneal dialysis patientsdemonstrated a threefold and haemodialysis a twofold increasein median Lp(a) values compared to controls (P0.001). The peritonealdialysis group had significantly more patients with Lp(a) valuesgreater than 30 mg/dl compared to controls, (53% versus 22%P0.001). In addition both patient groups demonstrated significanthypertriglyceridaemia (P0.001), reduction in HDL (P0.001) andelevation of the cholesterol/HDL ratio (P0.001) compared withcontrols. Peritoneal dialysis patients also demonstrated significanthypercholesterolaemia (P0.003). Lipoprotein (a) concentrations are considerably elevated inpatients on maintenance dialysis and this occurs in additionto the typical lipoprotein disturbances. This elevation mayincrease vascular risk, particularly in the peritoneal dialysisgroup who also have hypercholesterolaemia and reduced HDL.     

Serum {alpha}2-macroglobulin in haemodialysis patients: baseline and kinetic studies

The pathogenesis of dialysis related amyloidosis remains unresolveddespite the identification of ß₂-microglobulin (ß₂M)as the major protein constituent, as well as other proteinsbeing present in the deposits. Among the latter we have assessedthe serum concentrations of ₂-macroglobulin (₂M) both in thebaseline stage and during the haemodialysis (HD) procedure.We have also assessed the influence of the membrane on ₂M kinetics. Fifteen HD patients with histologically proven dialysis-relatedamyloidosis (DRA group) and 15 HD patients clinically and radiologicallyconsidered dialysis-related amyloidosis free (control group)were included in the baseline study. Blood was sampled the daybefore the second dialysis of the week and ₂M, ß₂Mand ₁, antitrypsin were determined along with the routine biologicalanalysis of these patients. Serum ₂M was greater in dialysis-relatedamyloidosis than in control patients (t = 2.35; P<0.026).Serum ß₂M was similar in both groups. The serum ₂Mand ß₂M correlated in patients with dialysis-relatedamyloidosis (r = 0.64; P<0.01), while no correlation wasfound in controls (r = 0.17; NS). Stepwise analysis taking thepresence of dialysis-related amyloidosis as the dependent variableretained the serum ₂M concentration as the first variable inthe model (F = 4.4; partial r = 0.38; P<0.046). The sameproteins were determined in another group of seven patients,before and hourly during HD as well as 2 and 8 h after the endof HD during nine consecutive dialyses (3 cycles of 3 HD eachusing AN69 and cuprophane membranes in a crossover design).Serum ₂M significantly increased from hour 3 and continued toincrease 2 hours post-HD (+11% and +9% with AN69 and cuprophanerespectively; P<0.001). Total proteins peaked at hour 4 (+4% and +3% P<0.01) and decreased after HD. Serum ß₂Msignificantly decreased with AN69 HD ( – 29% P<0.001)and remained unchanged during cuprophane HD. In conclusion, significant increases in serum ₂M are observedimmediately after and during the early post-dialysis periods,regardless of the membrane used. Further, serum ₂M correlateswith ß₂M only in patients with dialysis-related amyloidosis,and this variable was retained in the multivariate regressionanalysis to predict dialysis-related amyloidosis. Although thebaseline results require confirmation with larger studies, wepostulate that the present results are of relevance for dialysis-relatedamyloidosis pathogenesis since ₂M, previously identified indialysis related amyloid deposits, is closely related to acute-phasereactant proteins, and interacts with the main infiltratingcells of the deposits (macrophages). ₂M modifications couldrepresent a new manifestation of the inflammatory response tothe haemodialysis procedure.     

The renal histopathology in systemic vasculitis: an international survey study of inter- and intra-observer agreement

In order to relate histopathological findings of the kidneyin systemic vasculitis to renal outcome, scoring of variousmorphological parameters is necessary. Therefore, we conducteda standardization study for evaluating renal biopsies from patientswith systemic vasculitis. Four experienced renal pathologistsfrom four European centres joined in the study. A scoring protocolwas devised that required the observers to score an extensivenumber of histopathological lesions either quantitatively (asa percentage of the total number of glomeruli) or dichotomously(on a present/absent scale). Twenty renal biopsies were scoredindividually by all the observers, from which the inter-observervariability was analysed. Ten randomly chosen biopsies werescored again, in order to obtain the intra-observer variability.For inter-observer agreement, the evaluation of the quantitativevariables was satisfactory for both rounds (0.55Kendall's W0.95and 0.59W0.96, respectively, with all P<0.05). However, theinter-observer agreement for the dichotomous data was poor (K0.30in more than half of the parameters in both rounds). Also thedata on intra-observer agreement showed more favourable resultsfor the analysis of the quantitative data (Pearson's r>0.45in more than 85% of the variables in both rounds) than for thedichotomous scoring system (K0.30 in more than half of the variables).It is concluded that even between experienced renal pathologistsdiscrepancies occur in scoring kidney biopsies. Inter- and intra-observeragreement is greater if a quantitative method for reviewingthe biopsies is applied that requires the observers to scorethe tissue specimens systematically.     

Risk factors of the progression of abdominal aortic calcification in patients on chronic haemodialysis

Background. Vascular calcification is an independent determinantof cardiovascular events in maintenance haemodialysis (HD) patients.It is not known whether acute changes of the serum calcium concentrationbefore and after HD (Ca) are associated with the developmentof aortic calcification. Methods. We enrolled 71 patients dialysed with a dialysate with3.0 mEq/l calcium and determined their aortic calcificationindex (ACI) by abdominal computed tomography twice at an intervalof 3 years. To identify the factors contributing to the rateof progression of aortic calcification, we analysed the averagevalues for clinical and laboratory data obtained between thefirst and second evaluations of ACI. Results. The second ACI (mean ± SD: 80.2 ± 63.9)was significantly greater than the first ACI (61.0 ±61.0) after an interval of 35.8 ± 4.2 months. The annualizedchange of ACI (ACI/year) was significantly and directly associatedwith the Ca and C-reactive protein (CRP) (both P < 0.001,P for trend). Stepwise multivariate regression analysis revealedthat ACI/year was positively and independently associated withCRP, presence of diabetes mellitus and Ca, but negatively associatedwith a premenopausal status in women. Similarly, Ca was positivelyand independently associated with ACI/year and the ultrafiltrationrate, but was negatively associated with pre-HD Ca. Conclusion. The increase of serum calcium after HD was relatedto the rate of progression of aortic calcification. Excess calciumis transferred into patients on HD when using a dialysate of3.0 mEq/l calcium. This may be a risk factor for the developmentof vascular calcification.     

Plasma Concentrations of Atrial Natriuretic Peptide in Relation to Body Fluid Status in Chronic Uraemia

Basal plasma -human natriuretic peptide (-hANP) values werefound to be significantly higher in 7 fluid-overloaded chronicdialysis patients than in 13 non-dialysed renal patients withoutextracellular fluid (ECF) expansion. Iso-osmotic reduction ofthe body weight by a single 3-h ultrafiltration caused -hANPto decrease significantly in all anuric patients to values comparableto those of non-dialysed subjects. In this latter group, however,there was a significant inverse relationship between -hANP andglomerular filtration rate but not between -hANP and total bloodvolume. These findings suggest that both ECF expansion and impairedrenal removal of -hANP might be responsible for the high -hANPin chronic uraemia.     

Once-weekly erythropoietic therapy: is there a difference between the available preparations?

Sir, Iain Macdougall provided, in general, a comprehensive reviewof once-weekly administrations of epoetin , epoetin ßand darbepoetin [1]. However, additional mention could havebeen made of the differences between epoetin and epoetin ß,as well as further analysis of the data from studies of subcutaneous(s.c.) administration. With regard to the differences between epoetin and epoetin     

Relationship between elevated creatine phosphokinase and the clinical spectrum of rhabdomyolysis

The incidence, causes and complications of severe rhabdomyolysis(creatine phosphokinase (CK) 5000 U/l) were studied during a7-year study period in a large university hospital population.This condition was present in 0.074% of all admitted patients.The mortality in the study group (n=93) was 32% and the incidenceof acute renal failure (ARF) 51%. Ischaemia was the most frequentcause, and drugs, alcohol and/or coma were the second most commoncause of severe rhabdomyolysis. Patients with rhabdomyolysisdue to ischaemia were older, had ARF more often, and also hadthe highest mortality. Hyperkalaemia (potassium 5.5 mmol/1)occurred in 13% of the patients, and all of them had or developedan impaired renal function. Hypocalcaemia (calcium 2.00 mmol/1)was found in 41%. The incidence of ARF and electrolyte disturbanceswas higher in patients with CK levels exceeding 15 000 U/l.Mortality was significantly higher in patients with ARF. Plasmaconcentrations of potassium and calcium correlated better withthe severity of renal failure than with the maximal height ofplasma CK.     

Sera from patients with anti-GBM nephritis including Goodpasture syndrome show heterogenous reactivity to recombinant NC1 domain of type IV collagen {alpha} chains

BACKGROUND.: Goodpasture (GP) syndrome is defined by the clinical associationof pulmonary haemorrhage with rapidly progressive glomerulonephritis.The disease is caused by pathogenic autoantibodies directedagainst type IV collagen, which is a major structural componentof glomerular basement membranes (GBM). METHODS.: The non-collagenous domains (NC1) of all six human type IV collagenchains was produced in E. coli as recombinant fusion proteinswith glutathione-S transferase. Sera from 10 patients with differenttypes of anti-GBM nephritis, including GP syndrome, were testedfor reactivity with the six proteins using immunoblotting ofdenatured and reduced proteins and ELISA without reduction. RESULTS.: All 10 sera reacted with the 3(IV) collagen chain by immunoblottingand ELISA. One serum also recognized the 2(IV) 4(IV), 5(IV)and 6(IV) chains by immunoblotting. ELISA measurements revealedreactivity of several other sera with 2(IV), 4(IV) or 6(IV)but not with 5(IV) collagen chains. No reactivity was observedwith the 1(IV) chain. CONCLUSION.: Autoantibodies in anti-GBM nephritis may not be directed onlyagainst the 3(IV) collagen chain and they frequently recognizeconformational epitopes.     

Interleukin 6 production by human proximal tubular epithelial cells in vitro: analysis of the effects of interleukin-1{alpha} (IL-1{alpha}) and other cytokines

Proximal tubular epithelial cells (PTEC) from human renal tissueobtained from biopsy or nephrectomy were grown in monocultureand evaluated in vitro at passage 2–4 for interleukin6 (IL-6) production in response to medium alone or to interleukin1 alpha (IL-1), tumour necrosis factor alpha (TNF), interleukin2 (IL-2), interferon gamma (INF) or lipopolysaccharide (LPS).IL-6 bioactivity was quantitated using the IL-6-dependent murinehybridoma cell line (B9) and expressed as IL-6 units/ml/10⁵PTEC. PTEC cell lines exposed to medium alone produced intermediateamounts of IL-6 with substantial variability between cell lines.Introduction of IL-1 resulted in a dose- and time-dependentincrease in IL-6 production by PTEC that was maximal at 1 ng/mlIL-1 at 24 h. All PTEC cell lines showed an increased IL-6 productionon exposure to IL-1 varying from 1.3- to 24-fold increase overbaseline production. This response was completely blocked byanti-rIL-1. No significant IL-6 production by PTEC could beinduced by TNF, IL-2, IFN, or LPS over a broad dosage range.Cycloheximide inhibited IL-6 production without irreversiblecell toxicity, indicating de-novo synthesis. IL-6 produced byPTEC had a molecular weight of 26-29 kDa as demonstrated byWestern blot analysis. Using PCR analysis we could demonstrateupregulation by IL-1 of IL-6 mRNA in a dose-response fashion,indicating that IL-1 regulates IL-6 production at a pretranslationalvalue of protein synthesis. These results show that human culturedPTEC produce IL-6 under both normal and IL-1-stimulated conditions,and suggest that they may have a regulatory function in responseto cytokines in the setting of inflammation in the renal cortex.     

Acute effect of oral, intraperitoneal, and intravenous 1{alpha}-hydroxycholecalciferol on markers of bone metabolism

OBJECTIVE: To study the acute effect of 1-hydoxycholecalciferol (1-OHD₃)on serum levels of alkaline phosphatase, Ca²⁺, osteocalcin,parathyroid hormone (PTH), phosphate and type I and III procollagens(PICP and PIIINP respectively) in patients undergoing peritonealdialysis. Also, 1,25-(OH)₂D₃ was measured. DESIGN: Single doses of 1-OHD₃ (80 ng/kg body wt) were given in randomizedcross-over fashion, orally, intraperitoneally (i.p.) and intravenously(i.v.) on three occasions. Blood was sampled at 0, 1, 6, 12,and 24 h after administration of 1-OHD₃. MAIN RESULTS: Following oral administration of 1-OHD₃, a decrease in serumalkaline phosphatase was seen when levels at 1 and 6 h werecompared to baseline (P<0.05). Oral and i.v. drug administrationsresulted in an increasing trend in serum Ca²⁺ throughout thestudy (P<0.05). Moreover, a difference in serum Ca²⁺ wasfound when 24-h levels after oral 1-OHD₃ dose was compared tobaseline (P<0.05). Serum osteocalcin at 12 and 24 h afteroral 1-OHD₃ compared to baseline were increased (P<0.05).Intact PTH followed a circadian rhythm after all three routesof drug delivery. After 24 h, significant decreases of intactPTH were observed in the oral and i.v. group. No changes inserum phosphate and serum PICP levels were observed over timeafter oral, i.p., and i.v. delivery of 1-OHD₃However, serumPIIINP following oral and i.p. administration of 1-OHD₃ decreasedat 1 and 6 h (P<0.05). CONCLUSION: Oral and iv. administration of 1-OHD₃ does influence serum levelsof osteocalcin, PTH, and PIINP. Noticeable is the significantincrease in serum osteocalcin after oral administration of 1-OHD₃,the remarkable increase (22.6%) in osteocalcin 24 h after i.v.1-OHD₃, though not statistically significant, the increase inserum PTH levels 12 h following oral and i.v. doses of 1-OHD₃and the moderate effect on serum Ca²⁺ levels.     

Imbalance between intraperitoneal coagulation and fibrinolysis during peritonitis of CAPD patients: the role of mesothelial cells

We compared peritoneal dialysis effluents from 18 CAPD patientswho had not suffered from peritonitis during the last 6 months(group 1) with the effluents from five patients with acute peritonitis(group 2), measuring activation markers of coagulation and fibrinolysis.These markers included prothrombin fragment F1+2 (F1+2), thrombin-antithrombinIII complex (TAT), fibrin monomer (FM), and fibrin degradationproducts (FbDP). In the dialysate of group 1 we found remarkablyhigh levels of F1+2, TAT and FM concomitant with a high concentrationof FbDP, indicating a high rate of intraperitoneal fibrin turnover.The balance between peritoneal generation and degradation offibrin was disturbed in untreated patients of group 2, who hadsignificantly higher levels of coagulation markers and a higherratio between FM and FbDP. Seven days after treatment with intraperitonealadministration of antibiotics and heparin, F1+2, TAT, FM andFbDP decreased significantly. To evaluate the role of mesothelial cells (MC) in the high peritonealfibrin turnover we investigated the expression of tissue-typeplasminogen activator (t-PA), urokinase-type plasminogen activator(u-PA), plasminogen activator inhibitor type-1 (PAI-1), andtissue factor in cultured human peritoneal MC under basal conditionsand after exposure to tumour necrosis factor (TNF) interleukin-1(IL-1), or bacterial lipopolysaccharide (LPS). The exposureof MC to TNF or to a lesser extent IL-1 or LPS reduced theirfibrinolytic activity by decreasing t-PA production and increasingPAI-1 synthesis. Furthermore the addition of TNF resulted inactivation of the coagulation cascade by the expression of tissuefactor. These in-vitro findings explain the imbalance betweenintraperitoneal coagulation and fibrinolysis during peritonitisof CAPD patients.     

Animal models of Alport syndrome.

Introduction The last decade of the twentieth century was a very productiveperiod for the study of Alport syndrome. Alport syndrome wasshown to result from mutations in certain members of the typeIV collagen family of proteins, the 3(IV), 4(IV), and 5(IV)chains. Several hundred different mutations in the COL4A5 gene,which encodes the 5(IV) chain, were described in patients withX-linked Alport syndrome [1]. A few dozen mutations were foundin the COL4A3 and COL4A4 genes, which respectively encode the3(IV) and 4(IV) chains, in patients with autosomal recessiveAlport syndrome [2,3]. Autosomal dominant Alport syndrome, dueto heterozygous mutations in COL4A3 or COL4A4, was establishedas an entity, and distinguished from Fechtner and Epstein syndromes,which arise from mutations in a non-collagen locus, MYH9 [4–7].Investigators established that mutations in the 3(IV), 4(IV),or      

Tissue-specific distribution of the Goodpasture antigen demonstrated by 2-D electrophoresis and Western blotting

The target of autoantibodies in Goodpasture's disease, the Goodpastureantigen has recently been characterized as the NC1 domain ofthe 3 chain of type IV collagen. In order to study the Goodpastureantigen in different organs, NC1 domains were isolated frombasement membranes (BM) of human glomeruli (GBM), tubules (TBM),alveoli (ABM), placenta (PBM) and aorta (VBM). NC1 preparationswere separated by 2-D electrophoresis, and silver stained orimmunoblotted to determine the subunit structure and antigenicityof different basement membranes. All basement membranes containedmonomeric components of MW 26 kDa and 24 kDa, and associateddimers, corresponding to the 2-D location of 1(IV) and cc2(IV)chains respectively. However, GBM, ABM, and to a lesser extentTBM possessed an extra set of monomeric components of MW 28kDa and associated dimers corresponding to the proposed locationof 3(IV) and 4(IV) chains. 2-D-separated polypeptides were Westernblotted with autoantibodies from patients with Goodpasture'sdisease, a monoclonal antibody to the Goodpasture antigen (P1)and a monoclonal antibody to the bovine 3(IV) chain. The predominantbinding of all these reagents was to cationic 28 kDa monomersof GBM, ABM and TBM, corresponding to the 3(IV) chain, althoughautoantibodies and P1 also bound to neutral 28 kDa monomers,corresponding to the 4(IV) chain. Autoantibodies bound weaklyto more neutral components of PBM and VBM, but neither monoclonalantibody bound to these basement membranes. This study suggeststhat there are two separate type IV collagen networks: one containingthe l(IV) and 2(IV) chains appears to be present in all basementmembranes, and the other containing the 3(IV) and 4(IV) chainshas a tissue specific distribution. The latter network bearingthe Goodpasture antigen is expressed in the basement membranesof both kidney and lung, the organs involved in Goodpasture'sdisease.     

Changes in the expression of adhesion molecules as peripheral blood monocytes differentiate into peritoneal macrophages

Peritoneal macrophages, derived from peripheral blood monocytes,are the chief cellular defenders against invasion of the peritonealcavity by infectious organisms. Monocyte migration into theperitoneal cavity depends upon a coordinated series of adhesiveevents, utilizing cell surface receptors known as adhesion molecules.in order to better understand the mechanisms of leucocyte infiltrationof the peritoneum during peritonitis, we studied the relativeexpression of adhesion molecules on monocytes and peritonealmacrophages from patients on continuous ambulatory peritonealdialysis (CAPD). Peripheral blood and spent peritoneal dialysisfluid were obtained from patients undergoing CAPD, and the levelof expression of various adhesion molecules on the monocytes/macrophagesanalysed by flow cytometry using receptor-specific monoclonalantibodies. Monocytes were also purified from the peripheralblood of volunteer donors, cultured in vitro for varying periods,and analysed in the same manner. Consistent differences in expressionof certain adhesion molecules were found between monocytes andperitoneal macrophages, and similar changes occurred on monocytescultured in vitro. Concurrent infection had no clear effect.Several receptors (integrins 4ß1 6ß1, Lß₂;and IIbß3, and platelet endothelial cell adhesionmolecule-1) were significantly decreased on peritoneal macrophages,while only the integrin vß5 increased. It is concludedthat monocyte differentiation into peritoneal macrophages isaccompanied by characteristic alterations in the adhesion moleculerepertoire on the cell surface, emphasizing the different adhesiverequirements of these two cell types.     

Peripheral blood mononuclear cells from patients with chronic renal failure release factors which suppress erythropoietin secretion in vitro

Decreased production of erythropoietin (Epo) as a result ofreduced renal mass is considered the main factor underlyingthe anaemia that is invariably associated with chronic renalfailure (CRF). Other mechanisms such as accumulation of inhibitorsof Epo also contribute. In this study we show that supernatantfrom peripheral blood mononuclear cells (PBMC) cultured frompatients with CRF inhibits Epo release by Hep G2 cells in vitro.Ten patients (5 male) with CRF (mean age 42 years, range 25–60)were studied. Five were approaching end-stage renal failureand five were maintained on haemodialysis (HD). Ten apparentlyhealthy volunteers were used as controls. Full blood countsand serum Epo (RIA) levels were determined and adherent PBMCwere cultured for 48 h with and without LPS. There was a significantrise in TNF- and IL1-ß levels measured in monocytesupernatant (MS) from patients and controls after LPS stimulation(P<0.05) and in IL-l levels in patients (P<0.05). IL-1ßlevels were higher in patients compared to controls both beforeand after stimulation with LPS (P<0.05). Hep G2 cells werecultured in 5% CO₂ and 20% O₂ and incubated with MS from patientsand controls for 24 h. Hep G2 harvest fluids were then analysedfor Epo levels, which were expressed as a function of totalcell protein (mU/mg). Epo production was inhibited by MS frompatients compared to controlsboth before and after stimulationwith LPS (P<0.0001). There was, however, no direct correlationbetween the degree of Epo suppression and concentrations ofMS TNF-, IL-l, and IL-ß. Inhibition byspecific polyclonalanti-TNF- antibodies and anti-IL-ß antibodies didnot abrogate the inhibition ofEpo release by Hep G2 cells. Theseresults demonstrate that although PBMC from patients with CRFproduce factors that inhibit Hep G2 cell secretion of Epo invitro, this effect does not appear to be directly related tothe proinflammatory cytokines TNF-, IL-l, and IL-ß.