Adjustment of DLCO for hemoglobin concentration

The equation proposed by Cotes and coworkers is currently considered as the most acceptable to correct carbon monoxide diffusing capacity (DLCO) for hemoglobin concentration [Hb] by both the American Thoracic Society (ATS) and the European Respiratory Society (ERS) guidelines for standardization of DLCO. In a previous study on 24 anemic patients undergoing bone marrow transplantation (1), we found that DLCO is underestimated using the equation of Cotes and coworkers. To further explore this finding, 28 anemic patients ([Hb] = 8.2 +/- 1.0 (SD) g/dl) with chronic renal failure were prospectively studied during the recovery period of anemia (5.4 +/- 3.5 mo). In all 28 subjects, the slope deltaDLCO/delta[Hb] computed as ratio of overall change in DLCO to overall change in [Hb] throughout the study period was 1.40 +/- 0.72 ml CO/min/mm Hg/g/dl. The individual relationship between measured DLCO and [Hb] closely fitted a simple linear regression. The resulting equations for adjustment of DLCO (DLCOadj) to a standard [Hb] of 14.6 g/dl for men and 13.4 g/dl for women are: [equations: see text]. The present adjustment function for DLCO is linear and independent of the observed DLCO values, whereas the formulas previously proposed are curvilinear, DLCO correction varying with the measured DLCO values. For a measured DLCO of 15 ml CO/min/mm Hg and [Hb] ranging from 7 to 12 g/dl, the present DLCO adjustment is higher (by 2.7 ml CO/min/mm Hg, on average) than that proposed by Cotes and coworkers. This difference appears to be relevant for a precise interpretation of DLCO in patients with normocytic anemia in different clinical conditions.

[Usefulness of HLA-DR expression in tubular cells of transplanted kidney for the diagnosis of rejection]

BACKGROUND

Fine needle aspiration is a useful technique as a monitorization method after kidney transplantation for diagnosis of rejection. In addition to the cells of the intrarenal inflammatory infiltrate, the material obtained contains an important quantity of parenchymatous renal cells. The expression of class II HLA antigens in renal tubular cells has been related with episodes of rejection. The aim of this study was to determine the clinical usefulness of fine needle aspiration in diagnosis and control of kidney transplant rejection.

PATIENTS AND METHODS

HLA-DR expression of renal tubular cells obtained in 155 fine needle aspirations carried out in 36 consecutive kidney transplantations were prospectively studied. The technique used was that of alkaline phosphatase. The study period included the two months following the graft.

RESULTS

Rejection was considered to occur on expression of HLA-DR in more than 20% of tubular cells and as thus this method showed a sensitivity and specificity of 78 and 79%, respectively. Likewise, a good correlation was observed between the persistence of tubular HLA-DR expression following rejection treatment and severity of the same. The group of patients with stable renal function presented a slight, transitory expression within the first 10-12 days after transplantation.

CONCLUSIONS

HLA-DR expression of the tubular cells obtained by aspiration puncture is a useful method for the diagnosis and control of kidney transplant rejection.

Polymerization of normal and intact beta 2-microglobulin as the amyloidogenic protein in dialysis-amyloidosis

The primary structure of beta 2-microglobulin (beta 2m), the major constituent protein of beta 2-microglobulin amyloidosis (A beta 2m) or dialysis-amyloidosis, was initially shown to be identical to serum beta 2m, thereby strongly suggesting the polymerization of intact beta 2m in tissues. Recent biochemical data have been controversial, showing beta 2m acidic isoforms, fragmentation and amino acid sequence alteration of deposited beta 2m. The aim of this study was to reinvestigate beta 2m amyloid deposits for the presence of beta 2m fragments and/or amino acid sequence alteration. Four amyloid-laden tissues (3 femoral bone amyloid cysts and 1 heart tissue) from dialysis patients were used to isolate amyloidogenic beta 2m. Amyloid fibrils were isolated using the classic water extraction method, and purified in 6 M guanidine on a gel-filtration column. The protein was further purified on 17% SDS-PAGE gel, and transferred to a nitrocellulose membrane for immunostaining with antihuman beta 2m. beta 2m samples were microsequenced using the standard 03RPTH program on a 470A gas-phase sequencer, and HPLC was performed after digestion with trypsin. Two peaks were obtained with the gel filtration column, the second corresponding by molecular weight to beta 2m. SDS-PAGE analysis of this peak under reducing conditions, demonstrated one major band at 12,000 Da and a minor band at 25,000 Da (monomer and dimer), and no lower molecular weight bands were observed. The 12 kDa band was micro-sequenced and the amino acid sequence corresponded to that of normal beta 2m through the 40th residue. Amino acid sequence analysis showed no difference from normal beta 2m in any of the beta 2m proteins contained in the amyloid deposits isolated from the four studied tissues. Also, the HPLC profile of the four protein samples were strictly normal and identical to a commercial preparation of beta 2m. The present study demonstrates that beta 2m molecules polymerized in amyloid fibrils and deposits are intact and have a normal amino acid sequence, and produced by a specific and unique fibrillogenetic mechanism, which does not require proteolytic processing from the precursor protein to the amyloid fibrils.

Hereditary hepatic and systemic amyloidosis caused by a new deletion/insertion mutation in the apolipoprotein AI gene

We report a Spanish family with autosomal-dominant non-neuropathic hereditary amyloidosis with a unique hepatic presentation and death from liver failure, usually by the sixth decade. The disease is caused by a previously unreported deletion/insertion mutation in exon 4 of the apolipoprotein AI (apoAI) gene encoding loss of residues 60-71 of normal mature apoAI and insertion at that position of two new residues, ValThr. Affected individuals are heterozygous for this mutation and have both normal apoAI and variant molecules bearing one extra positive charge, as predicted from the DNA sequence. The amyloid fibrils are composed exclusively of NH2-terminal fragments of the variant, ending mainly at positions corresponding to residues 83 and 92 in the mature wild-type sequence. Amyloid fibrils derived from the other three known amyloidogenic apoAI variants are also composed of similar NH2-terminal fragments. All known amyloidogenic apoAI variants carry one extra positive charge in this region, suggesting that it may be responsible for their enhanced amyloidogenicity. In addition to causing a new phenotype, this is the first deletion mutation to be described in association with hereditary amyloidosis and it significantly extends the value of the apoAI model for investigation of molecular mechanisms of amyloid fibrillogenesis.

Cellular bioenergetics after erythropoietin therapy in chronic renal failure

After erythropoietin (rHuEPO) therapy, patients with chronic renal failure (CRF) do not improve peak O2 uptake (VO2 peak) as much as expected from the rise in hemoglobin concentration ([Hb]). In a companion study, we explain this phenomenon by the concurrent effects of fall in muscle blood flow after rHuEPO and abnormal capillary O2 conductance observed in CRF patients. The latter is likely associated with a poor muscle microcirculatory network and capillary-myofiber dissociation due to uremic myopathy. Herein, cellular bioenergetics and its relationships with muscle O2 transport, before and after rHuEPO therapy, were examined in eight CRF patients (27 +/- 7.3 [SD] yr) studied pre- and post-rHuEPO ([Hb] = 7.8 +/- 0.7 vs. 11.7 +/- 0.7 g x dl-1) during an incremental cycling exercise protocol. Eight healthy sedentary subjects (26 +/- 3.1 yr) served as controls. We hypothesize that uremic myopathy provokes a cytosolic dysfunction but mitochondrial oxidative capacity is not abnormal. 31P-nuclear magnetic resonance spectra (31P-MRS) from the vastus medialis were obtained throughout the exercise protocol consisting of periods of 2 min exercise (at 1.67 Hz) at increasing work-loads interspersed by resting periods of 2.5 min. On a different day, after an identical exercise protocol, arterial and femoral venous blood gas data were obtained together with simultaneous measurements of femoral venous blood flow (Qleg) to calculate O2 delivery (QO2leg) and O2 uptake (VO2leg). Baseline resting [phosphocreatine] to [inorganic phosphate] ratio ([PCr]/[Pi]) did not change after rHuEPO (8.9 +/- 1.2 vs. 8.8 +/- 1.2, respectively), but it was significantly lower than in controls (10.9 +/- 1.5) (P = 0.01 each). At a given submaximal or peak VO2leg, no effects of rHuEPO were seen on cellular bioenergetics ([PCr]/[Pi] ratio, %[PCr] consumption halftime of [PCr] recovery after exercise), nor in intracellular pH (pHi). The post-rHuEPO bioenergetic status and pHi, at a given VO2leg, were below those observed in the control group. However, at a given pHi, no differences in 31P-MRS data were detected between post-rHuEPO and controls. After rHuEPO, at peak VO2, Qleg fell 20% (P < 0.04), limiting the change in QO2leg to 17%, a value that did not reach statistical significance. The corresponding O2 extraction ratio decreased from 73 +/- 4% to 68 +/- 8.2% (P < 0.03). These changes indicate that maximal O2 flow from microcirculation to mitochondria did not increase despite the 50% increase in [Hb] and explain how peak VO2leg and cellular bioenergetics (31P-MRS) did not change after rHuEPO. Differences in pHi, possibly due to lactate differences, between post-rHeEPO and controls appear to be a key factor in the abnormal muscle cell bioenergetics during exercise observed in CRF patients.

Effects of erythropoietin on muscle O2 transport during exercise in patients with chronic renal failure

Erythropoietin (rHuEPO) has proven to be effective in the treatment of anemia of chronic renal failure (CRF). Despite improving the quality of life, peak oxygen uptake after rHuEPO therapy is not improved as much as the increase in hemoglobin concentration ([Hb)] would predict. We hypothesized that this discrepancy is due to failure of O2 transport rates to rise in a manner proportional to [Hb]. To test this, eight patients with CRF undergoing regular hemodialysis were studied pre- and post-rHuEPO ([Hb] = 7.5 +/- 1.0 vs. 12.5 +/- 1.0 g x dl-1) using a standard incremental cycle exercise protocol. A group of 12 healthy sedentary subjects of similar age and anthropometric characteristics served as controls. Arterial and femoral venous blood gas data were obtained and coupled with simultaneous measurements of femoral venous blood flow (Qleg) by thermodilution to obtain O2 delivery and oxygen uptake (VO2). Despite a 68% increase in [Hb], peak VO2 increased by only 33%. This could be explained largely by reduced peak leg blood flow, limiting the gain in O2 delivery to 37%. At peak VO2, after rHuEPO, O2 supply limitation of maximal VO2 was found to occur, permitting the calculation of a value for muscle O2 conductance from capillary to mitochondria (DO2). While DO2 was slightly improved after rHuEPO, it was only 67% of that of sedentary control subjects. This kept maximal oxygen extraction at only 70%. Two important conclusions can be reached from this study. First, the increase in [Hb] produced by rHuEPO is accompanied by a significant reduction in peak blood flow to exercising muscle, which limits the gain in oxygen transport. Second, even after restoration of [Hb], O2 conductance from the muscle capillary to the mitochondria remains considerably below normal.

Study of kidney rejection following simultaneous kidney-pancreas transplantation

Simultaneous kidney-pancreas (SKP) transplantation is associated with increased risk of kidney rejection (KR) due to an unknown mechanism. The aim of this study is to analyze the characteristics of KR in 44 SKP transplantations under quadruple immunosuppressive therapy and to evaluate the response to treatment and its effect on renal allograft survival and renal function. The mean follow-up was 25 +/- 14 months. Seventy-seven percent of the patients (34 of 44) presented an acute renal allograft rejection. Sixty-six percent (29 of 44) had one rejection episode and 11% (5 of 4) 2 episodes. KR was early (85% in the first month after transplantation), intense (3.7-fold increase in creatinine) and had great clinical features. Twenty-eight percent of the patients had an early relapse during the first month after treatment. KR did not affect the survival of the renal allograft in the short-term (1 and 2 years). Overall, 62% were corticosensitive (CS) and the remaining 38% were corticoresistant (CR). The group with an isolated rejection without relapse was CS in 69% of the cases, achieved complete remission in 73% and renal function was not affected at 1 and 2 years [115 +/- 26 mumol/l (1.3 +/- 0.3 mg/dl) and 150 +/- 53 mumol/l (1.7 +/- 0.6 mg/dl)] in comparison with the group without rejection [97 +/- 18 mumol/l (1.1 +/- 0.2 mg/dl) and 115 +/- 35 mumol/l (1.3 +/- 0.4 mg/dl); p = NS]. On the other hand, the group with an early relapse of the first rejection and the group with two rejections were principally CR (62 and 60%, respectively), had partial remission with treatment (50 and 60%) and had worse renal function at 1 and 2 years [212 +/- 71 mumol/l (2.4 +/- 0.8 mg/dl) and 221 +/- 53 mumol/l (2.5 +/- 0.6 mg/dl)] than in the group with isolated KR (p < 0.05 and p < 0.001). In conclusion, despite intense immunosuppressive treatment, the frequency of rejection of a renal allograft in SKP is high. The response to treatment is satisfactory and does not affect the survival of the allograft in the short-term. However, multiple episodes or early relapse of rejection are associated with higher creatinine levels.

Role of secondary hyperparathyroidism in the development of post-transplant acute tubular necrosis

Post-transplant cure tubular necrosis (ATN) represents the most frequent cause of delayed graft function in the immediate post-transplant period. Several causes have been associated with the development of post-transplant ATN such as donor and recipient ages, cold-warm ischemia times, HLA mismatches, and postoperative hypotension. In the present study, we retrospectively evaluated the role of secondary hyperparathyroidism and high parathyroid hormone (PTHi) blood levels in the development of post-transplant ATN. One hundred patients submitted to cadaveric renal transplant between January 1992 and March 1993 in our unit were included. Twenty-seven patients (27%) developed post-transplant ATN and seventy-three (73%) did not. Post-transplant ATN was significantly associated with gender (p < 0.01), recipient age (p < 0.01), number of transplantations (p < 0.01), time on hemodialysis (p < 0.001), cold ischemic time (p < 0.05) and PTHi levels (p < 0.001). The bivariate and multivariate statistical analyses demonstrated that the development of post-transplant ATN was significantly more frequent in females; retransplanted patients, patients with a time on dialysis of more than 5 years, recipients over 60 years old, patients with a PTHi blood level higher than 240 pg/ml (4 times normal level) and a cold ischemia time of more than 18 h. Based on these results, we conclude that high PTHi blood levels in the renal transplant recipients represent a relevant factor in the development of post-transplant ATN. The administration of intravenous pulsed of 1,25(OH)2D3 and/or a calcium channel blocker in the perioperative period could be useful to decrease the incidence and severity of post-transplant ATN in these patients.

Dialysis-related amyloidosis: visceral involvement and protein constituents

beta 2-M amyloidosis mainly concerns dialysis patients and typically presents with osteoarticular symptoms. In order to precise the incidence and gravity of visceral involvement, subcutaneous abdominal fat aspirates, skin and rectal biopsies, as well as echocardiograms were performed in 26 patients with severe beta 2-M amyloidosis. Visceral amyloidosis was confirmed in 58% and the numbers were even higher when including heart abnormalities suggestive of amyloidosis (81%). Clinical manifestations of visceral involvement were usually not severe and include odynophagia, gastrointestinal haemorrhage, intestinal obstruction, kidney stones, myocardial dysfunction and subcutaneous tumours. The removal and synthesis rates of beta 2-M were assessed during dialysis. Serum 131I-beta 2-M levels decreased by 5-10% with cuprophane and by 40-45% with polysulfone and polyacrylonitrile membranes. These reduction rates were higher than those found with unlabelled beta 2-M suggesting an increased synthesis or release during dialysis. The protein constituents of amyloid deposits were studied. Two different preparative methods to extract the proteins from amyloid deposits were used. TCA precipitation showed the presence of several proteins which were not observed with PBS homogenizing and resuspending in guanidine. The protein constituents of amyloid fibrils were studied by both, two dimensional gel electrophoresis (2D-gel) as well as protein sequencing after gel filtration. Similarly, the technical approach used for protein analysis greatly influenced the results. It was observed that 2D-gel displayed the presence of proteins which were missed by the gel filtration technique. Some of the proteins contained in amyloid deposits in addition to beta 2-M, were identified as globin chains, kappa and lambda light chains of immunoglobulins, and alpha 2 macroglobulin. A putative participation of these other protein constituents on the pathogenesis of beta 2-microglobulin amyloidosis is discussed.

DNA flow cytometric analysis in renal neoplasms associated with acquired renal cystic disease

In order to better understand the potential malignancy of renal neoplasms arising in patients with acquired renal cystic disease and to try and establish differences from other renal tumours we analysed DNA ploidy as well as the level of S-phase fraction in 11 neoplasms associated with acquired cystic disease by means of flow cytometry. The results were correlated with known prognostic factors such as nuclear grade, size and stage, as well as the clinical behaviour of the tumours. We found a close relationship between DNA aneuploidy and high S-phase fraction and a poor clinical outcome. We also found some differences in the DNA ploidy profile of these tumours when compared with those reported in other renal neoplasms.

Transplantation of kidneys from donors with hepatitis C antibody into recipients with pre-transplantation anti-HCV

Hepatitis C virus (HCV) is transmitted by organ transplantation. Consequently, several organ procurement organizations have imposed a moratorium on use of organs from anti-HCV positive donors. Because of the inadequate supply of cadaver kidneys for transplantation, we adopted a policy to transplant kidneys from anti-HCV donors into anti-HCV positive recipients. During the period between March 1990 and December 1992, 24 anti-HCV positive dialysis patients received a kidney from anti-HCV positive donors (group I) and 40 anti-HCV positive patients received a kidney from anti-HCV negative donors (group II). We compared the prevalence of liver disease, anti-HCV, HCV RNA, graft and patient survival between groups. Pre-transplantation 17 of 24 (71%) patients in group I and 31 of 40 (79%) of patients in group II had serum HCV RNA. Post-transplantation follow-up was 26 +/- 8 months and 30 +/- 10 months in groups I and II, respectively. During follow-up, elevated ALT levels were present in 7 of 24 (29%) and 16 of 40 (40%) of patients in groups I and II, respectively (P > 0.05). Post-transplantation, all patients in both groups retained anti-HCV. The prevalence of HCV RNA post-transplantation was 22 of 23 (96%) patients in group I and 30 of 39 (77%) of patients in group II (P > 0.05). Graft and patient survival in group I (96% and 100%, respectively) were not significantly different from those in group II (93% and 98%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)