[Cardiovascular risk in the kidney transplant patient]

Renal transplants have experienced a spectacular development in recent years, significantly improving the quality of life and life expectancy of patients. However, mortality due to cardiovascular disease in recent years has become the first cause of death in renal transplant patients, ahead of infections and neoplasic disorders. The causes of this increase are due to the following reasons: 1) Important changes in the characteristics of the donor and the renal receptor. 2) A significant decrease in the immediate post-transplant mortality rates, and 3) increase in the incidence of cardiovascular risk factors in transplant patients.

Role of transforming growth factor-beta1 in the progression of chronic allograft nephropathy

Chronic allograft nephropathy is the principal cause of late graft loss after the first year of renal transplantation. Transforming growth factor-beta1 (TGF-beta1) is a key fibrogenetic cytokine involved in the fibrosis of a number of chronic diseases of the kidney and other organs, and recently evidence has shown that TGF-beta1 is involved in the pathogenesis of chronic renal allograft dysfunction. Production of TGF-beta1 in these circumstances may be modulated by the intrarenal renin-angiotensin system (angiotensin II induces TGF-beta1 production and secretion by the mesangial cells) and by a direct effect of cyclosporin A, which stimulates the synthesis and expression of TGF-beta1. In a prospective study of 14 renal transplant patients exhibiting chronic graft nephropathy, we demonstrated that treatment with losartan significantly decreased plasma levels of TGF-beta1 by >50%. There was a significant correlation (P=0.04) between the increase in circulating angiotensin II after 2 weeks and the decrease in plasma TGF-beta(1) at the end of the study period, suggesting that the degree of angiotensin II receptor blockade plays a decisive role in the synthesis of TGF-beta1. A significant decrease in circulating endothelin-1 (ET-1) levels also occurred during treatment with losartan, together with a decrease in proteinuria. In a randomized 2x2 crossover study, the effects of losartan and amlodipine on renal haemodynamics and on profibrogenetic cytokines were analysed. Whereas amlodipine increased the glomerular filtration rate (GFR) through an increase in the FF and P(G), losartan slightly decreased the GFR, but with a significant decrease in FF and P(G). With respect to the profibrogenetic cytokines, losartan decreased the plasma levels of TGF-beta1 and ET-1, while amlodipine did not significantly change TGF-beta1 and slightly increased ET-1.

Muscle angiogenic growth factor gene responses to exercise in chronic renal failure

Patients with chronic renal failure (CRF) have impaired exercise capacity even after erythropoietin treatment. We recently showed that although this is explained in part by reduced convective O(2) delivery to muscles, there is also an impairment of O(2) transport from muscle capillaries to the mitochondria. Given the importance of the capillary surface area for capillary mitochondrial O(2) transport and reports of reduced capillarity in CRF, we hypothesized that the angiogenic gene response to exercise is impaired in such patients. Six patients with CRF and six control subjects matched for age, size, and sedentary lifestyle exercised on a single occasion for 1 h at similar work intensities averaging 50% of maximal capacity. Exercise was confined to the knee extensors of a single leg by means of a specially designed leg-kick ergometer. A percutaneous biopsy of the quadriceps was taken within 30 min of cessation of exercise and compared with a similar biopsy done at different times without any prior exercise for 24 h. Conventional Northern blots were prepared and probed for vascular endothelial growth factor (VEGF; the major putative angiogenic growth factor for muscle), basic fibroblast growth factor (bFGF), and transforming growth factor (TGF)-beta(1). Data during both rest and exercise were successfully obtained in four subjects of each group. We also assessed muscle capillarity and mitochondrial oxidative capacity to relate to these changes. Mitochondrial oxidative capacity was normal, whereas capillary number per fiber was 12% lower than in normal subjects. VEGF mRNA abundance was increased after exercise by about one order of magnitude, with no reduction in response in CRF. For bFGF and TGF-beta(1), exercise elicited no response in either group. Reduced muscle capillarity in CRF does not, therefore, stem from reduced transcription of VEGF. To the extent that VEGF is important to exercise-induced angiogenesis in muscle, we suspect a posttranscriptional aberration in this response occurs in CRF to explain reduced capillarity.

Exploring treatment options in renal transplantation: the problems of chronic allograft dysfunction and drug-related nephrotoxicity

The immunosuppressive benefits of cyclosporine and tacrolimus in short-term and medium-term renal allograft survival are well documented. It is becoming increasingly clear that the basis of this immunosuppression, the inhibition of calcineurin, may be linked with nephrotoxicity, hypertension, hyperlipidemia, and new-onset diabetes mellitus, side effects that may lead to CRAD, death due to CVD, and late renal allograft loss. This clinical picture presents a clear need for new strategies that produce adequate immunosuppression to prevent acute rejection while simultaneously reducing the side effects associated with CNI-related therapies. Sirolimus combined with cyclosporine and tacrolimus has demonstrated an ability to reduce incidences of early acute rejection and, used as base therapy, has provided protection against acute rejection equivalent to that of cyclosporine, without the consequent nephrotoxicity associated with CNIs. In preliminary results from an ongoing clinical trial, sirolimus has been used to eliminate cyclosporine during maintenance immunosuppression, with subsequent improvements in measures of blood pressure and renal function. In addition, the antiproliferative properties of sirolimus and its ability to prevent graft vascular disease in animal studies make sirolimus a promising agent to decrease incidences of CRAD and improve long-term renal allograft survival. These findings point to a clear need to further explore both the efficacy of sirolimus immunotherapy and its long-term effects.

Hepatic familial amyloidosis caused by a new mutation in the apolipoprotein AI gene: clinical and pathological features

OBJECTIVE

Recently, we reported a nondescribed deletion/insertion mutation in the apolipoprotein AI gene as the cause of hereditary amyloidosis with hepatic presentation. We describe the clinical and pathological features of this type of amyloidosis in one affected family.

METHODS

Demographic, clinical, and biochemical data were obtained from 33 members of the family in whom the apolipoprotein AI gene was studied. Diagnosis was based on the detection of the apolipoprotein AI gene mutation, scintigraphy using radioionated serum amyloid P component, and histological and immunohistochemical studies.

RESULTS

Eight members with the mutation had hepatic involvement. Six patients were practically asymptomatic, presented with an elevation of alkaline phosphatase and gamma-glutamyl transpeptidase, and remained stable during follow-up (7.6 +/- 4.9 yr). One patient had jaundice, developed ascites and encephalopathy, and died of hepatorenal syndrome a few months after diagnosis. Jaundice and portal hypertension appeared in the remaining patient, who died 4 yr later.

CONCLUSION

This form of familial amyloidosis is characterized by elevation in serum alkaline phosphatase and gamma-glutamyl transpeptidase secondary to amyloid deposits in the portal tracts. Patients remain stable and asymptomatic for many years, but portal hypertension and liver failure can develop later in life and lead to death. Thus, patients should be observed regularly and liver transplantation should be indicated when progression is detected.

Effect of losartan on TGF‐β1 and urinary albumin excretion in patients with type 2 diabetes mellitus and microalbuminuria

BACKGROUND

The aim of the present study was to determine the effect of losartan on transforming growth factor-beta1 (TGF-beta1) plasma levels and urinary albumin excretion (UAE) in patients with type 2 diabetes mellitus, mild hypertension and microalbuminuria.

METHODS

Fourteen patients (eight males, aged 55+/-6 years) with type 2 diabetes mellitus, mild arterial hypertension and microalbuminuria, participating in an open, uncontrolled, pilot study were included. Patients were treated for 8 weeks with losartan. TGF-beta1 plasma levels, UAE and 24-h blood pressure monitoring were determined at baseline and at 4 and 8 weeks.

RESULTS

At 4 and 8 weeks of treatment, a reduction was observed in TGF-beta1 plasma levels (5.5+/-4.5 vs 2.0+/-0.6 and 2.6+/-1.0 ng/ml, P<0.005), UAE (96+/-65 vs 59+/-59 and 64+/-47 microg/min, P<0.01), 24-h systolic blood pressure (136+/-9 vs 129+/-9 and 130+/-10 mmHg, P<0.01) and 24-h diastolic blood pressure (77+/-9 vs 74+/-8 and 74+/-7 mmHg, P<0.03). Stratifying the patients by baseline TGF-beta1, seven had TGF-beta1 plasma values higher than normal controls. At 4 and 8 weeks, they showed a marked reduction in TGF-beta1 values (9.0+/-3.9 to 2.1+/-0.7 and 2.5+/-0.7 ng/ml, P<0.01) and UAE (106+/-83 to 49+/-42 and 38+/-26 microg/min, P<0.05), with good correlation between the percentage reduction of both parameters (r=0.83, P<0.01). The remaining seven patients, with normal baseline TGF-beta1 plasma levels, showed no change in TGF-beta1 plasma levels and UAE after treatment.

CONCLUSION

Treatment with losartan decreases TGF-beta1 plasma values and UAE in type 2 diabetes mellitus patients with high baseline TGF-beta1 levels, suggesting that TGF-beta1 may be a marker to detect patients who may particularly benefit from renin-angiotensin system blockade.

Impaired muscle oxygen transfer in patients with chronic renal failure

We hypothesized that impaired O2 transport plays a role in limiting exercise in patients with chronic renal failure (CRF). Six CRF patients (25 +/- 6 yr) and six controls (24 +/- 6 yr) were examined twice during incremental single-leg isolated quadriceps exercise. Leg O2 delivery (QO2(leg)) and leg O2 uptake (VO2(leg)) were obtained when subjects breathed gas of three inspired O2 fractions (FI(O2)) (0.13, 0.21, and 1.0). On a different day, myoglobin O2 saturation and muscle bioenergetics were measured by proton and phosphorus magnetic resonance spectroscopy. CRF patients, but not controls, showed O2 supply dependency of peak VO2 (VO2(peak)) by a proportional relationship between peak VO2(leg) at each inspired O2 fraction (0.59 +/- 0.20, 0.47 +/- 0.10, 0.43 +/- 0.10 l/min, respectively) and 1) work rate (933 +/- 372, 733 +/- 163, 667 +/- 207 g), 2) QO(2leg) (0.80 +/- 0.20, 0.64 +/- 0.10, 0.59 +/- 0.10 l/min), and 3) cell PO2 (6.3 +/- 5.4, 1.7 +/- 1.3, 1.2 +/- 0.7 mmHg). CRF patients breathing 100% O2 and controls breathing 21% O2 had similar peak QO2(leg) (0.80 +/- 0.20 vs. 0.79 +/- 0.10 l/min) and similar peak VO2(leg) (0.59 +/- 0.20 vs. 0.57 +/- 0.10 l/min). However, mean capillary PO2 (47.9 +/- 4.0 vs. 38.2 +/- 4.6 mmHg) and the capillary-to-myocite gradient (40.7 +/- 6.2 vs. 34.4 +/- 4.0 mmHg) were both higher in CRF patients than in controls (P < 0.03 each). We conclude that low muscle O2 conductance, but not limited mitochondrial oxidative capacity, plays a role in limiting exercise tolerance in these patients.

Dialysis-related amyloidosis after renal transplantation

There is no effective therapy for dialysis-related amyloidosis (DRA). The restoration of renal function with a functional graft seems the most reasonable therapy for this disturbing disease. Although there are not many prospective series on the efficacy of renal transplantation for DRA, all the studies agree that most of the patients experienced a significantly clinical improvement of the articular symptoms after a successful renal transplantation. Nevertheless, radiologic (bone cysts) and histologic lesions did not disappear after long-term follow-up.

[Non-convulsive status epilepticus secondary to adjusted cefepime doses in patients with chronic renal failure]

Fever is one of the most frequent causes of hospital admission in patients with end-stage renal disease. Lack of an identified source of infection and/or lack of clinical response to the first empirical antibiotic treatment favour the use of broader spectrum antibiotics. The availability of fourth-generation cephalosporins (e.g. cefepime) and the increasing incidence of bacterial resistances to classical antibiotics has increased their use in the clinical practice. We present two cases of non-convulsive status epilepticus in patients with advanced chronic renal failure who received cefepime at doses corrected for the degree of renal function according to the manufacturer's instrument as. The clinical symptoms included shouthough, processes, disorientation, loss of attention, and the later appearance of myoclonus. In both cases the electroencephalogram (EEG) was compatible with non-convulsive epileptic status. After cefepime withdrawal there was a clinical remission of symptoms and normalization of the EEG. It is concluded that cefepime treatment can induce a non-convulsive epileptic status in patients with advanced chronic renal failure. Pharmacokinetic studies are urgently needed to clearly define the appropriate dose of cefepime in patients with advanced chronic renal failure.