ACE gene sequence and nucleotide variants in IgA nephropathy

INTRODUCTION

Association studies with single nucleotide polymorphisms (SNPs) have been contradictory. Haplotypes may be more helpful. With gene sequencing, all SNPs can be found for construction of haplotypes.

METHODS

The ACE gene was sequenced in four healthy Chinese subjects and 20 patients with IgA nephropathy (IgAN) to observe if differences exist among SNPs and haplotypes. 20 patients on angiotensin 1-converting enzyme inhibitor/angiotensin receptor antagonist (ACEI/ATRA) therapy were then compared with another 20 patients not treated with ACEI /ATRA to determine their renal outcome in response to ACEI/ATRA therapy and whether their genetic profile of ACE gene could play a role in determining their outcome to ACEI /ATRA therapy and progression to end-stage renal failure (ESRF).

RESULTS

IgAN patients had 53 variants, of which 17 were unique, whereas normal subjects had 38 variants, of which two were unique (p less than 0.005). No unique variant was a significant risk factor for IgAN. Significant genotype and allele frequency differences in five variants were observed between IgAN patients with renal impairment and those with ESRF (p less than 0.02).

CONCLUSION

Our data suggests that at least in the ACE gene, haplotyping SNPs within a single gene seems to have no added advantage over genotyping the individual component SNPs. The D allele and haplotype 3 confer an adverse prognosis, while the I allele and haplotype 5 appear to be renoprotective. The data suggests that genotypes of the ACE gene are linked to certain haplotypes, which could influence IgAN patients' response to ACEI/ATRA therapy.

Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of urinary protein in acute kidney injury

Recent experimental and clinical studies have shown the importance of urinary proteomics in acute kidney injury (AKI). We analyzed the protein in urine of patients with clinical AKI using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) for its diagnostic value, and followed them up for 40 months to evaluate prognosis. Urine from 31 consecutive cases of AKI was analyzed with SDS-PAGE to determine the low, middle and high molecular weight proteins. Fractional excretion of sodium (FENa) was estimated from serum and urine creatinine and sodium (Na). The cases were followed-up for 40 months from the end of the recruitment of study cases. Glomerular protein was higher in the hematuria group when compared with the non-hematuria group (P <0.04) and in the AKI group than in the acute on chronic renal failure (AKI-on-CRF) group (P <0.002). Tubular protein was higher in the AKI-on-CRF group (P <0.003) than in the AKI group. Tubular protein correlated with FENa in groups with diabetes mellitus (DM), AKI-on-CRF, and without hematuria (P <0.03, P <0.02 and P <0.004, respectively). Pattern of protein did not differ between groups with and without DM and clinical acute tubular necrosis (ATN). At the end of 40 months follow-up, category with predominantly glomerular protein progressed to chronic renal failure (CRF) or end-stage renal failure in higher proportion (P <0.05). In clinical AKI, we observed that glomerular protein dominated in cases with glomerular insult, as indicated by hematuria. Tubular protein was common in the study cases with CRF, DM and cases without hematuria. This indicates tubulo-interstitial injury for AKI in these cases. Patients with predominantly glomerular protein had an adverse outcome.

Impact of patterns of proteinuria on renal allograft function and survival: a prospective cohort study

BACKGROUND

Proteinuria is an important complication in renal transplant recipients. The aim of this prospective study was to evaluate the long-term impact of transplant proteinuria patterns on allograft function and survival.

METHODS

We analyzed urinary protein of a cohort of 83 renal transplants with proteinuria ≥0.5 g/d by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and radial immunogel diffusion assay. After initial stratification and analysis, the cohort was followed up for 16 yr. The graft outcome and survival were analyzed using Cox regression model to determine their association with different patterns of initial transplant proteinuria.

RESULTS

Group with predominantly glomerular (middle- and high-molecular-weight with or without low-molecular-weight) proteinuria (61%) had higher serum creatinine (p < 0.001) than the group with predominantly tubular (low-molecular-weight) proteinuria (39%). The incidences of chronic graft dysfunction and graft loss had increased in the glomerular proteinuria group (p < 0.001, hazard ratio 3.6, 95% confidence interval 1.7-7.5 and p < 0.001, hazard ratio 4.9, 95% confidence interval 1.9-12.1, respectively). Patient death did not differ (p = 0.434, hazard ratio 1.5, 95% confidence interval 0.5-4.5).

CONCLUSION

  Proteinuria in renal transplants can be differentiated into glomerular and tubular types based on molecular weight. Glomerular proteinuria is associated with significant increase in graft dysfunction and graft loss.

Physician leadership

Doctors, because of the nature of their training and their profession, have to be leaders. Subsequently, when they specialise, leadership qualities are even more important if they are to be effective in leading the specialty team. It is common knowledge that doctors have become leaders in various sectors of society. One of the fundamental advantages a doctor has over others in leadership positions is his basic training in studying and understanding human nature. With years of practice and experience, the doctor, a student of human nature, has a good grasp of human behaviour which enables him to become a better leader. The six universal and timeless characteristics of great leaders are: ability to share a vision, surrounding oneself with great people, ability to coach other team members, ability to focus on perfection, developing emotional intelligence and ability to train effective leaders. I would like to see three essential qualities in a strong leader: ability to secure an "envisioned future", ability to sacrifice in order to cultivate loyalty, and courage to do the right thing and protect his people. An effective leader positions himself in a situation to ensure survival. Having secured the leadership position, one must take certain steps to strengthen one's leadership so that it will survive. Six strategies from the Art of War by Sun Tzu which are of great practical value are: walk the ground, have trusted lieutenants, information gathering, confuse the enemy, win most while doing nothing, and that which is too good will not last forever. Sometimes we have to change in order to survive. We need to get rid of outmoded practices and shed old burdens to take advantage of the present. The task of exiting from leadership is facilitated if one has groomed a successor. The longer one is in a leadership position, the more difficult it is for one to step down. Some organisations retain old leaders as advisors or mentors. They should be just seen and not heard and go about their work quietly, contributing to the department. A retired leader should be able to command respect from his peers and preserve his dignity.

Long term outcome of renal allografts in patients with immunoglobulin A nephropathy

Recurrent glomerular disease is an important cause of late allograft loss in renal transplant recipients. Immunoglobulin A nephropathy (IgAN) is a leading cause of end-stage renal disease (ESRD) worldwide and its recurrence has been reported in allografts. The present study examined outcomes following renal transplantation (RTX) in 101 patients with ESRD due to biopsy-proven IgAN, in comparison to non-IgA patients, and evaluated the incidence of recurrence. The study population (mean age 34.8 +/- 7.7 years; males 62.2%; Chinese 88.3%) underwent RTX under CsA immunosuppression between November 1984 and December 2004; as two patients underwent retransplantation during the study period, 103 allografts (56.3% cadaveric) were included for retrospective analysis. At time of analysis on 1 January 2005, 78 (75.7%) renal allografts (IgAN RTX) were functioning, of which 51 (49.5%) had normal serum creatinine, 27 (26.2%) had chronic allograft dysfunction, while 25 had graft losses, either due to patient death with functioning grafts (5.8%) or withdrawal to dialysis (18.5%). Persistent microscopic haematuria, not attributable to other causes or proteinuria > 1 g/day occurred in 42.7% and 13.6% of allografts respectively. Of 29 allografts biopsied for evaluation of proteinuria and/or renal dysfunction post-RTX, 8 (27.6%) had IgAN (overall histological recurrence, 7.8%). Of these, three had graft loss due to recurrent IgAN, three had elevated serum creatinine, while two had normal serum creatinine. Overall five and ten year patient survivals for IgAN RTX were 95.3% and 82.2%, and five and ten year actuarial graft survivals were 82.3% and 67.8% respectively. Five and ten year patient and graft survivals for IgAN RTX were not significantly different from that for non-IgAN RTX. In summary, RTX patients with IgAN have a low incidence of documented histological recurrence and recurrence contributing to graft loss occurs in only 2.9%. These results suggest that RTX is an excellent modality of renal replacement therapy in this population.

ATRA therapy restores normal renal function and renal reserve and prevents renal failure

This article presents clinical data which suggest that the current dosage of losartan 50 to 100 mg/day may not be the optimum in many cases, especially if used as monotherapy in the treatment of proteinuria and we may have to increase to 200 mg/day. However, about 30% of patients cannot take angiotensin-converting enzyme inhibitor (ACEI) because of the side effect of cough. To potentiate the anti-proteinuric effect of losartan, especially for patients who do not adhere to a low salt diet, a 12.5-mg dose of hydro-chlorothiazide may further decrease proteinuria. The main message of this article is that we would have to, in many instances, increase the dose of losartan to a minimum of 100 mg/day or 100 mg twice a day for some patients for optimal therapy. The second message is to monitor the creatinine clearance test (CCT) and to start therapy when CCT is reduced and not wait for serum creatinine to rise to abnormal levels (renal impairment) before starting therapy. The first group involves half a dozen patients with hypertension but no proteinuria. Therapy with losartan is shown to improve the renal function. This data suggest that losartan, apart from its use in reduction of proteinuria, can be used in patients with mild renal impairment without proteinuria to reverse the mild renal impairment and preserve renal function. The second group deals with 3 patients with low creatinine clearance. After a followup period of an average of 3 years, they all developed renal impairment. In another 6 patients, the data suggest that we should perhaps treat patients with low CCT as soon as possible and with dose ranging from 100 to 200 mg/day if necessary, to derive maximum beneficial effect. The third group highlights 5 patients with high CCT due to glomerular hyperfiltration. With time, the high CCT decreases and renal impairment sets in. The data suggest that patients with high CCT should be treated early to prevent renal impairment. The fourth group illustrates 6 patients where their proteinuria was markedly reduced with the increase of losartan from 100 mg/day to 200 mg/day, suggesting that losartan 200 mg/day is probably the optimum dose. In conclusion, apart from its traditional usage in reduction of proteinuria to retard progression to renal failure, the data suggest that losartan is also indicated in patients with renal impairment in the absence of proteinuria; patients with low CCT, patients with high CCT and patients who do not respond to a dosage of 100 mg/day should have the dosage increased to 100 mg twice daily to increase efficacy of losartan. It is hoped that with these new and earlier indications as well as increased dosage of losartan starting with 100 mg, whenever possible, and increasing to 200 mg/day, if there is no response, we can prevent more patients from developing renal failure. Based on these observations, further randomised controlled trials should be designed to address these issues.

MARS therapy in critically ill patients with advanced malignancy: a clinical and technical report

BACKGROUND/METHODS

Molecular Adsorbent Recirculating System (MARS) was used in three consecutive critically ill patients at the Singapore General Hospital with advanced malignancy and acute liver failure (ALF). Case 1 was a male patient with hepatocellular carcinoma (HCC) for which initial right hepatectomy was followed by left hepatectomy 5 months later for recurrent HCC. The postoperative course following second surgery was complicated by severe methicillin-resistant Staphylococcus aureus (MRSA) sepsis, mild azotaemia and subacute cholestatic liver failure. MARS was used thrice in this patient. Case 2 was a female patient with advanced acute lymphoblastic leukaemia (ALL) with post bone marrow transplantation (BMT) acute haemolytic-uraemic syndrome (HUS) secondary to cyclosporin A (Cy A), cytomegalovirus (CMV) infection, severe nosocomial pneumonia, acute renal failure (ARF) treated with continuous haemofiltration and acute veno-occlusive disease resulting in Budd-Chiari syndrome. The latter precipitated ALF. MARS was instituted twice. Case 3 was a male patient with advanced, refractory Hodgkin's disease previously treated with multiple courses of chemotherapy. ALF developed secondary to acute viral hepatitis B flare. He was given a trial of MARS once in the ICU. All the three patients eventually died.

RESULTS

Mean MARS intradialytic systemic pressures were as follows: systolic pressure range was 95 +/- 17 to 128 +/- 17 mmHg and diastolic pressure range was 51 +/- 5 to 67 +/- 7 mmHg. Pressure at albumin dialysate exit point from dialyser 1 (Ae) ranged from 253 +/- 11 to 339 +/- 15 mmHg and that at albumin dialysate entry point into dialyser 1 (Aa) ranged from 142 +/- 11 to 210 +/- 6 mmHg. Ultrafiltration (UF) was 633 +/- 622 mL over mean treatment duration of 6.3 +/- 0.9 h with a total heparin dose of 1583 +/- 817 IU. Coagulation status pre- and 6-h post-MARS was similar: aPTT (P=0.116) and platelet count (P=0.753). There were no bleeding complications or circuit thromboses. MARS had a significant de-uraemization effect (pre- and post-MARS serum creatinine and urea: P=0.046 and 0.028, respectively) but did not significantly attenuate blood lactate, ammonia or total bilirubin levels. Albumin dialysate (Ae - Aa) urea and creatinine concentrations appeared to be sharply attenuated after 6 h of MARS. In contrast, the removal of total bilirubin by albumin dialysate from the blood compartment appeared to plateau after 4 h of continuous MARS operation.

CONCLUSIONS

MARS was well-tolerated in critically ill patients with advanced and complicated cancer. Low-dose heparin was safe and did not compromise MARS circuit integrity. Although MARS had a significant de-uraemization effect, this appeared to be limited by the duration of MARS operation. Our data suggested that such a limit was reached earlier for total bilirubin. More data are needed to confirm the present findings and further delineate the saturation limit of MARS for different toxins that accumulate in ALF. This would affect the optimal duration of MARS therapy.

ACE gene polymorphism and disease progression of IgA nephropathy in Asians in Singapore

The deletion polymorphism of the angiotensin-converting enzyme (ACE) gene has been considered as a risk factor for IgA nephropathy and for its progression to end-stage renal failure. However, results from various studies are conflicting. We had genotyped the ACE gene in 100 patients with IgA nephropathy, 32 of whom were in end-stage renal failure and in 90 normal adult subjects. All DD cases were subjected to confirmation with a second PCR, performed with the insert-specific forward primer. Similar genotype frequencies were obtained for the 90 normal control subjects (II: 47%, ID: 44%, DD: 9%); for the 68 patients not in end-stage renal failure (ESRF) (II: 47%, ID: 46%, DD: 7%) and for the 32 patients with ESRF (II: 53%, ID: 38%, DD: 9%). The genotype frequencies in all 3 series are in Hardy-Weinberg equilibrium. These results suggest that ACE gene polymorphism is not a risk factor for IgA nephropathy and is not a predictor for its progression. Definitive proof of association between ACE gene polymorphism and progression in IgA nephropathy will require a prospective study, controlled for important risk factors, with adequate patient numbers and facility for confirming DD genotypes.

SDS-PAGE is underutilized as a tool for investigating renal patients

SDS-PAGE is an excellent single test for investigating proteinuria. It can provide much useful information on the underlying renal problem. Yet the literature hardly report a SDS-PAGE result in the management of renal patients. To examine how closely SDS-PAGE results may reflect biopsy findings, we investigated 11 patients scheduled for renal biopsy. Urine samples were taken at the same time for SDS-PAGE analysis using the PhastSystem (Pharmacia, Sweden). Comparing biopsy findings and SDS-PAGE results, the data show consistency in the revelation of tubular dysfunction and/or glomerular damage in all 11 patients. We concluded that the SDS-PAGE test is underutilized and suggest that its role for the management of renal patients be fully explored particularly in its potential for reducing the need for renal biopsy in certain patient groups.

Proteinuria: clinical signficance and basis for therapy

Proteinuria is the hallmark of renal disease and proteinuria exceeding 1 gm a day in patients with renal disease augers a poorer prognosis. Proteinuria has been shown to be tubulotoxic and directly contributes to renal deterioration. Patients with non-selective proteinuria are more likely to have progressive renal disease. Diabetic patients with persistent microhaematuria have about 20 times the risk of developing diabetic nephropathy. In essential hypertension, the onset of de novo proteinuria after years of adequate BP control is a marker of subsequent decline in renal function. In glomerulonephritis, more severe proteinuria is associated with faster rate of progression. Even though the initial phase of proteinuria in patients with glomerulonephritis is usually of immunological origin, in the vast majority of patients with established disease, the latter progressive phase of proteinuric glomerulopathy is the result of glomerular hyperfiltration which shifts glomerular non-selective pores to larger dimensions resulting in excessive leakage of protein in the urine. Endothelial injury resulting from glomerular hyperfiltration causes increase in local generation of Angiotensin II in the kidney as part of the hemodynamic response. ACE inhibitors and angiotensin II receptor antagonists (ATRA) can improve glomerular pore-selectivity by remodelling the glomerular basement membrane. In addition, these agents also have beneficial effects by decreasing TGF-beta production therapy decreasing mesangial cell proliferation, hence ameliorating disease progression in patients with diabetic nephropathy and IgA nephropathy. A number of recent clinical trials have shown that ACEI and ATRA therapy can retard the progression of renal deterioration in patients with NIDDM and those with IgA nephropathy and even restore normal renal function in those with mild renal impairment. Treatment and control of proteinuria in patients with renal disease should be regarded as important as treatment of hypertension as it can prevent renal failure.

Case reports of low dose cyclosporine. A therapy in adult minimal change nephrotic syndrome

INTRODUCTION

Many centres still use steroids to induce remission in patients with minimal change nephrotic syndrome (MCNS) and failing that to give a course of cyclophosphamide, though some centres are already using cyclosporine A (CsA) as an alternative. We report the benefits of CsA therapy in 3 adults with difficult to treat MCNS in whom low dose CsA therapy proved to be efficacious.

CLINICAL PICTURE AND OUTCOME

The first patient had her 1st relapse after 8 years and thereafter had 2 more relapses, within 3 months of each other, in spite of therapy with cyclophosphamide. With CsA therapy, at a dose of 3.5 mg/kg body weight (BW)/day, she achieved lasting remission of 22 months as of September 1999 and is still in remission. The second patient had his relapses of nephrotic syndrome over a period of 10 years when treated with prednisolone and cyclophosphamide. On the 13th relapse, he achieved a remission lasting 21 months after a 3 month course of CsA at a dose of 4 mg/kg BW/day. With the 14th relapse, he took half the dose of CsA prescribed [only the morning dose of neoral CsA (2 mg/kg BW/day)] and still achieved a remission and has been in remission since. The third patient was a young woman, married for 2 years without children. She could not tolerate prednisolone because of erosive gastritis and she responded to a pulse dose of intravenous cyclophosphamide for her 1st episode of nephrotic syndrome with complete remission. However, when she relapsed 5 months later she did not respond to a similar dose of i.v. cyclophosphamide and was therefore treated with CsA (4 mg/kg BW/day) which induced a prompt remission 1 month after commencement of therapy and she is still in remission. The trough CsA levels for the 3 patients (range 41 to 107 ng/mL) and the calculated average CsA levels were lower than that used for post renal transplant immunosuppression. The trough CsA levels were, however, similar to that used in patients with MCNS from other series, though achieved at lower CsA doses.

CONCLUSION

Our study shows that low dose CsA is a useful agent for induction of remission of MCNS and maintenance of lasting remission. A low dose CsA regimen will make CsA more affordable.

Action of dipyridamole and warfarin on growth of human endothelial cells cultured in serum-free media

OBJECTIVE

To study the anti-proliferative effect of Dipyridamole (anti-platelet), Dipyridamole with Warfarin, and Warfarin (anticoagulant) alone, in human endothelial cells in vitro.

DESIGN AND METHODS

Human endothelial cells were harvested from umbilical cords. Primary cultures were usually successful. However, subculture yields were usually contaminated with smooth muscle cells. We have developed an improved method for the isolation of endothelial cells by using Collagenase II, coating the culture flask with fibronectin and using serum-free media. The endothelial cells were characterised by anti-PECAM-1/PE (CD31) using Flow Cytometry with viability of 95% after trypsinization with 0.05% Trypsin and 1 mM EDTA. Growth and proliferation studies were performed in vitro in the presence of 5 microM Dipyridamole, 5 microM Dipyridamole with 5 microM Warfarin, 5 microM Warfarin alone by cell counts, (3)H-thymidine and (3)H-leucine incorporation.

RESULTS

The incorporation of (3)H-Leucine at day 6 in each test condition revealed no significant change. Control 12678 +/- 2968 CPM, Dipyridamole 8698 +/- 189 CPM, Dipyridamole and Warfarin 7541 +/- 413 CPM, and Warfarin alone 10711 +/- 732 CPM. With the incorporation of (3)H-Thymidine, Dipyridamole alone as well as Dipyridamole with Warfarin reduced the basal proliferation rates significantly when compared to controls. Control 14355 +/- 4441 CPM, Dipyridamole 1100 +/- 152 CPM (p<0.05), Dipyridamole with Warfarin 1092 +/- 272 CPM (p<0.05). Warfarin alone did not reduce proliferation significantly 12870 +/- 2677 CPM (NS).

CONCLUSIONS

We have developed a method to isolate pure endothelial cells from human umbilical cords using Serum-Free Media (SFM). EC with high purity was characterised by anti-PECAM-1/PE (CD31) using Flow Cytometry. Dipyridamole at a concentration of 5 microM inhibited the proliferation of endothelial cells at day 6 by 93%. These techniques can be used for routine analysis and proliferation studies.

ACEI/ATRA therapy decreases proteinuria by improving glomerular permselectivity in IgA nephritis

BACKGROUND

It has been postulated that angiotensin-converting enzyme inhibitor/angiotensin receptor antagonist (ACEI/ATRA) may decrease proteinuria in patients with glomerulonephritis by its action on the glomerular basement membrane. We therefore studied the relationship between the response of patients with IgA nephritis (IgAN) to ACEI/ATRA therapy by decreasing proteinuria and its effect on the selectivity index (SI) in these patients.

METHODS

Forty-one patients with biopsy-proven IgAN entered a control trial, with 21 in the treatment group and 20 in the control group. The entry criteria included proteinuria of 1 g or more and/or renal impairment. Patients in the treatment group received ACEI/ATRA or both with three monthly increases in dosage. In the control group, hypertension was treated with atenolol, hydrallazine, or methyldopa. The following tests were performed at three monthly intervals: serum creatinine, total urinary protein, SI, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and low molecular weight (LMW) proteinuria.

RESULTS

After a mean duration of therapy of 13 +/- 5 months, in the treatment group, there was no significant change in serum creatinine, proteinuria, or SI, but in the control group, serum creatinine deteriorated from 1.8 +/- 0.8 to 2.3 +/- 1.1 mg/dL (P < 0.05). Among the 21 patients in the treatment group, 10 responded to ACEI/ATRA therapy determined as a decrease in proteinuria by 30% (responders), and the other 11 did not respond (nonresponders). Among the responders, SI improved from a mean of 0.26 +/- 0.07 to 0.18 +/- 0. 07 (P < 0.001), indicating a tendency toward selective proteinuria. This was associated with an improvement in serum creatinine from mean 1.7 +/- 0.6 to 1.5 +/- 0.6 mg/dL (P < 0.02) and a decrease in proteinuria from a mean of 2.3 +/- 1.1 to 0.7 +/- 0.5 g/day (P < 0. 001). After treatment, proteinuria in the treatment group (1.8 +/- 1. 6 g/day) was significantly less than in the control group (2.9 +/- 1. 8 g/day, P < 0.05). The post-treatment SI in the responder group (0. 18 +/- 0.07) was better than that of the nonresponder group (0.33 +/- 0.11, P < 0.002). Eight out of 21 patients in the treatment group who had documented renal impairment had improved renal function compared with two in the control group (chi2 = 4.4, P < 0. 05). Of the eight patients in the treatment group who improved their renal function, three normalized their renal function compared with one from the control group.

CONCLUSION

Our data suggest that ACEI/ATRA therapy may be beneficial in patients with IgAN with renal impairment and nonselective proteinuria, as such patients may respond to therapy with improvement in protein selectivity, decrease in proteinuria, and improvement in renal function. ACEI/ATRA therapy probably modifies pore size distribution by reducing the radius of large unselective pores, causing the shunt pathway to become less pronounced, resulting in less leakage of protein into the urine.

Proteinuria and angiotensin converting enzyme (ACE) gene polymorphism

INTRODUCTION

Although proteinuria is traditionally regarded as the result of glomerular damage, recent evidence suggests that proteinuria can directly cause renal damage through lysosomal injury, growth factor induced tubular fibrosis and transcriptase genes which trigger vasoactive and inflammatory renal damage. The renin angiotensin system which releases angiotensin, a most powerful vasoconstrictor and mediator of mesangial cell proliferation and matrix expansion, has been associated with progressive renal injury. This paper reviews the role of angiotensin converting enzyme (ACE) gene polymorphisms in the genesis of progressive renal failure, as well as their role in the response of proteinuria to ACE inhibitor (ACEI) or angiotensin receptor antagonist (ATRA) therapy.

METHODOLOGY

The deletion/insertion polymorphism of the ACE gene has 3 genotypes DD, ID and II. Reported studies on the association of ACE gene polymorphisms with patients with IgA nephritis and progressive renal failure, including their response to ACEI or ATRA therapy, were reviewed.

RESULTS

Individuals with the DD genotypes have a higher risk of declining renal function with progressive IgA nephritis and more rapid deterioration to renal failure. Therapy with ACEI and or ATRA may be beneficial in patients with IgA nephritis with renal impairment and non-selective proteinuria as such patients may respond to therapy with improvement in protein selectivity, decrease in proteinuria and improvement in renal function.

CONCLUSION

ACE genotypes appear to predict antiproteinuric response to ACEI therapy. ACEI/ATRA therapy probably modifies pore size distribution by reducing the radius of large non-selective pores, causing the shunt pathway to become less pronounced resulting in less leakage of protein into the urine.

Rhabdomyolysis and acute renal failure complicating detergent ingestion

Rhabdomyolysis should be considered in the aetiology of all patients with unexplained acute renal failure (ARF). Early recognition provides the opportunity to initiate therapy aimed at preventing or limiting nephrotoxicity from the released heme pigment, myoglobin. We report an adult patient who developed ARF following the ingestion of a large amount of household detergent which, as far as we are aware, has not been previously described. The report illustrates the importance of measuring muscle enzyme levels and urinary myoglobin to confirm the possibility of rhabdomyolysis in any unusual presentation of ARF.

The changing pattern of glomerulonephritis in Singapore over the past two decades

This study reviews the pattern of glomerulonephritis (GN) in Singapore over the past 2 decades. In the earlier decade the pattern was typical of most Asian countries with mesangial proliferative GN (Mes GN) (56%) as the most common form of primary GN including the nephrotic syndrome (40%). In the 2nd decade the pattern undergoes a change. Though Mes GN is the commonest primary GN (42%), the commonest form of nephrotic syndrome is now minimal change disease (30%) with Mes GN decreasing to 25% among all primary nephrotic syndromes. Both minimal change and focal global sclerosis account for 50% of steroid/cyclophosphamide responsive GN today. Membranous GN though still uncommon, has increased from 3% (1st decade) to 6% (2nd decade) (p < 0.01). IgA nephritis is still the commonest primary GN occurring in Singapore (42% of all primary GN in the 1st decade and 45% in the 2nd decade). The present pattern of GN in Singapore, though, still predominantly Asian with the preponderance of mesangial proliferative GN with a relatively low incidence of membranous GN contrasts with the pattern in the West where membranous GN is the commonest form of primary GN. Even the incidence of FSGS has not increased as in the West where there is a rising incidence. The underlying basis for most GN in Singapore as in other Asian countries and elsewhere is antigen-driven: infective antigen as well as food or other allergens.

A case series of falciparum malaria-induced acute renal failure

Falciparum malaria is a disease of tropical climates which affects 270 million people annually and has an overall mortality of 1%. While the incidence of acute renal failure in malaria is less than 1%, mortality is reported to be as high as 45% in those with renal failure. We report the clinical course and outcome in 5 patients with falciparum malaria-induced acute renal failure treated at the Singapore General Hospital between June and July 1997. All 5 males, with mean age of 35.2 +/- 13.1 years, were admitted with history of fever and reported travel to a known malarious zone. Mean laboratory parameters upon admission included serum creatinine 725 +/- 515 mumol/L and serum urea 47 +/- 31 mmol/L. Three patients with hypotension on admission were started on haemodiafiltration, of whom 2 were subsequently converted to haemodialysis as their haemodynamics improved. Two remaining patients were started on intermittent bicarbonate haemodialysis. The overall mortality in our series was 20%, with 1 patient having died of complications of adult respiratory distress syndrome, disseminated intravascular coagulation and multiorgan failure. The remaining 4 survived and recovered their renal function. The single patient mortality occurred in the patient with admission serum creatinine of 1632 mumol/L, a value significantly higher than that of the 4 patients who survived (mean serum creatinine, 499 +/- 106 mumol/L, P < 0.002). These results suggest that falciparum malaria associated with acute renal failure is associated with a high morbidity, but early presentation and intervention with appropriate antimalarial and renal replacement therapy is associated with improved survival and recovery of renal function.

Conducting clinical trials in Singapore

All clinical trials in Singapore will now have to conform to the Medicines (Clinical Trials) Amended Regulations 1998 and the Singapore Good Clinical Practice (GCP) Guidelines 1998. The Medical Clinical Research Committee (MCRC) has been established to oversee the conduct of clinical drug trials in Singapore and together with the legislations in place, these will ensure that clinical trials conducted in Singapore are properly controlled and the well-being of trial subjects are safe guarded. All clinical drug trials require a Clinical Trial Certificate from the MCRC before the trial can proceed. The hospital ethics committee (EC) vets the application for a trial certificate before it is sent to MCRC. The drug company sponsoring the trial has to indemnify the trial investigators and the hospital for negligence arising from the trial. The MCRC, apart from ensuring the safety of trial subjects, has to provide continuing review of the clinical trial and monitors adverse events in the course of the trial. The EC will conduct continuing review of clinical trials. When a non-drug clinical trial is carried out, the EC will ensure that the proposed protocol addresses ethical concerns and meets regulatory requirements for such trials. There is great potential for pharmaceutical Research & Development (R&D) in Singapore. We must develop our skills and infrastructure in clinical trials to enable Singapore to be a regional hub for R&D of drugs in Asia.

Current therapeutic strategies in glomerulonephritis

Over the past 20 years the therapy of glomerulonephritis (GN) has evolved. Today apart from steroids and cyclophosphamide, newer agents like cyclopsorine A and tracrolimus (FK 506) have been reported to achieve remission (partial or complete) in patients with nephrotic syndrome due to various GN which have failed to respond to steroids and cyclophosphamide. For those patients who do not respond to any of the primary therapeutic agents, there are now other therapies available like angiotensin II converting enzyme inhibitors, angiotensin II receptor antagonists, dipyridamole, low dose warfarin including protein restriction and therapy aimed at hypercholesterolaemia in an attempt to retard progression to end stage renal failure. This paper presents a therapeutic approach for the various forms of primary GN.

Renal transplantation in cyclosporine-treated recipients at the Singapore General Hospital

1. The 5-year patient and graft survival rates for live-donor renal transplants undergoing transplantation with CsA-based immunosuppression at the Singapore General Hospital from 1985-1999 were 97.0% and 91.6%, respectively. The 5-year patient and graft survival rates for cadaveric renal transplant recipients from the same institution were significantly lower at 91.6% and 79.4%, respectively. Long-term graft survival as described by half-lives (T1/2) were 28.6 years and 20.4 years for live-donor and cadaveric grafts, respectively. 2. Tissue matching had no impact on graft or patient survivals in either live-donor or cadaveric renal transplants. However, sensitisation was associated with significantly worse graft survival in cadaveric transplant recipients. 3. Primary cadaveric transplant recipients enjoyed significantly better graft survival rates than retransplanted recipients (5-year survival rates of 80.1% and 65.0%, respectively; p = 0.032). 4. Among cadaveric renal transplant recipients, a single acute rejection episode was associated with worse long-term graft survival (T1/2 of 14.6 years and 37.0 years for those with and without rejection, respectively, p = 0.001). Likewise, delayed graft function was associated with worse overall graft survival (5-year graft survival rates of 70.7% vs. 86.8% in patients with and without DGF, respectively, p < 0.001). 5. Among cadaveric transplant recipients with a functioning kidney at 5 years after transplantation, 61.4% had normal renal function with serum creatinine levels < 141 mumol/L while 33.9% had mild renal dysfunction with SCr of 141-250 mumol/L. 6. The high graft and patient survival rates in this Asian population as reported from this single centre study may be attributed to selection of younger patients without overt ischaemic heart disease for transplantation and to good patient compliance to CsA therapy. Thus, recipient selection and ensuring patient compliance to treatment are key strategies in optimizing the use of a scarce resource such as organ transplants.

Pattern of proteinuria in tubular injury and glomerular hyperfiltration

Proteinuria is one of the bad prognostic indices in renal disease. This study compares the pattern of protein excretion in 10 patients with IgA nephropathy (IgAN), 10 patients with chronic glomerulonephritis approaching end-stage renal failure (ESRF) who still had proteinuria and 10 other patients with diabetic nephropathy (DN) with proteinuria but normal renal function. The pattern of proteinuria was analysed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing (IEF) and assayed for orosomucoid, alpha-1-microglobulin, retinol-binding protein, lysozyme, beta-2-microglobulin and N-acetyl-beta-D-glucosaminidase activity. Our data showed much similarity in the pattern of proteinuria between the DN and ESRF groups but significant differences with the IgAN group. The pattern of proteinuria in the IgAN group reflects glomerulonephritis whereas the similar pattern between the ESRF and DN groups may reflect hyperfiltration as well as tubular injury.

Plasma activity of contact coagulation factors in patients with IgA nephritis

Intraglomerular coagulation, initiated by the local activation of contact coagulation factors, has been suggested as one possible factor causing glomerular injury in IgA nephritis. The plasma activity of factor XII, prekallikrein and high molecular weight (HMW) kininogen were measured in 24 patients with biopsy-proven IgA nephritis and in 123 normal controls, using an activated partial thromboplastin time assay with the appropriate factor-deficient plasma as substrate. IgA patients had significantly lower plasma activity of factor XII (45.5% +/- 28.3% against 80.7% +/- 31.8%; mean +/- standard deviation, P < 0.001), prekallikrein (37.7% +/- 24.5% against 119.8% +/- 37.7%; P < 0.001) and HMW kininogen (72.8% +/- 37.8% against 119.1% +/- 42.8%; P < 0.001) when compared with controls. In the IgA patients, there was no significant correlation between factor XII, prekallikrein and HMW kininogen activity and 24-hour total urinary protein excretion, suggesting that the reduced plasma activity was not due to increased urinary loss of the coagulation factors. One possible explanation for these results is that the intrinsic coagulation pathway is activated in patients with IgA nephritis.

Recent concepts in the pathogenesis and therapy of IgA nephritis

In IgA nephritis (IgA Nx) there is a general defect in clearance of immune complexes. IgA molecules are poorly solubilised by the complement system and allows its deposition in the kidney. In patients with IgA Nx there is a defect both in the sera and in the renal tissue. Lack of genetically mediated mesangial reactivity towards IgA Nx prevents clinical and histological manifestations of IgA Nx. Binding of IgA deposits to mesangial cells causes secretion of cytokines associated with a decrease in prostaglandin E2 synthesis and increases in thromboxane A2 production which promotes mesangial cell proliferation. Angiotensin II induces mesangial cell contraction and efferent arteriovasoconstriction. Any form of therapy for IgA Nx must be rational and practical. To limit amounts of mesangial deposits one may attempt to reduce antigen load, down-regulate lymphokines and employ enzymes to remove glomerular immune deposits. The Department's guidelines for therapy of IgA Nx consist of control of systemic hypertension, use of angiotensin II converting enzyme inhibitor for glomerular hyperfiltration, dipyridamole and low-dose warfarin, a low protein diet and control of serum cholesterol to prevent lipid-induced glomerulosclerosis. Future therapeutic strategies may include inhibition of mediators and cytokines (platelet-derived growth factor antagonists and tumour necrosis factor inhibitors) and gene therapy.

Slow continuous ultrafiltration (SCUF)--the safe and efficient treatment for patients with cardiac failure and fluid overload

Slow Continuous ultrafiltration (SCUF) was first used in 1980 as an alternative mode of fluid removal for patients with oliguric acute renal dysfunction from whatever causes. The advantage of this treatment is that haemodynamic parameters remain stable in the presence of significant removal of fluid. We are describing our experience in 7 patients [age: 57 +/- 9 years; 4 male, 3 female] with cardiac failure and fluid overload who had undergone 8 sessions of SCUF. All of them had renal impairment and were resistant to diuretics. Blood lines were attached to a Kawasumi Renak-E dialyser (Cuprophane membrane) in series using Gambro AK10 dialysis blood pump. The following parameters were monitored: Blood pump (Qb): 175 +/- 26 ml/min, time (T): 393 +/- minutes. Venous pressure averaged a55 +/- 24 mmHg. We achieved ultrafiltration of 2,189 +/- 699 ml/session or 5.5 +/- 1.7 ml/hr. There was no significant change in blood pressure [systolic pre: 143 +/- 14, post: 136 +/- 13 mmHg, not significant; diastolic pre: 87 +/- 10, post: 83 + 10 mmHg, not significant and pulse rate [pre: 87 +/- 9 vs post: 84 +/- 2 per minute, not significant. Heparin dosage averaged 274 +/- 26 IU/hr during the SCUF. We conclude that SCUF is beneficial to diuretic resistant patients with cardiac failure and fluid overload in whom dialysis treatment is not required.

Isoelectric focusing and selectivity index in IgA nephrotic syndrome

Proteinuria in 13 patients with IgA nephritis with nephrotic syndrome (IgANS) was analysed by isoelectric focusing (IEF) and compared with 12 patients with minimal change nephrotic syndrome (MCNS) (n = 8) or focal global sclerosis nephrotic syndrome (FGS) (n = 4) to determine the pattern of proteinuria on IEF and to assess the value of IEF and protein selectivity index (SI) as predictors of response to therapy with predisolone or cyclophosphamide. Steroid/cyclophosphamide responsive patients with IgANS had SC:UA (cationic serum albumin with anionic urine albumin) or SA:UC (anionic serum albumin with cationic urine albumin) IEF patterns and steroid/cyclophosphamide unresponsive patients with IgANS had an SC:UC (cationic serum albumin with cationic urine albumin) IEF pattern. The majority of patients with MCNS or FGS who had an SA:UC IEF pattern were steroid responsive. SI was a better predictor of steroid/cyclophosphamide responsiveness in patients with IgANS (r = 0.78, p < 0.002 compared to IEF, r = 0.64, p < 0.02).

The impact of percutaneous renal biopsies on clinical management

Percutaneous renal biopsy (PRB) is now standard practice in clinical nephrology. One hundred consecutive non-transplant PRBs performed on adult patients at the Department of Renal Medicine, Singapore General Hospital, between January and August 1990, were analysed to examine the impact and complications of PRBs in a single institution. The study population consisted of 37 male and 63 female patients with a mean age of 32 +/- 11.9 years. The most frequent indications for PRB were systemic lupus erythematosus with renal involvement (41 patients), haematuria and proteinuria (27 patients) and the nephrotic syndrome (26 patients). Histological diagnoses included lupus nephritis in 45 patients, IgA nephritis in 19 patients, minimal change/focal global sclerosis in 14, non-IgA mesangioproliferative glomerulonephritis in seven and other histologies in the remainder. Eighty-two of our patients received renal-specific therapy, including 72 who received prednisolone or other immunosuppression, and 11 who received persantin and warfarin, in contrast to only 18 patients who received non-specific therapy including diuretics, antihypertensive drugs or dialysis. PRB led to change in therapy in 54% of all our patients, including 42 who had immunosuppressive drugs added to their therapeutic regimen and 11 who were commenced on persantin and/or warfarin. Complications of the procedure were minimal with flank pain in 6% and gross haematuria in 4%. As the inherent risks of inappropriate immunosuppression are well established, these results suggest that PRBs have a major impact on clinical management.

Continuous ambulatory peritoneal dialysis in type II diabetics

Forty-two Type II diabetic patients with end stage renal failure who had never previously received dialysis treatment were treated with continuous ambulatory peritoneal dialysis (CAPD) for a period of two to 48 months (average 16.8 months) with a total experience of 640 patient-months. Of the 42 patients, 29 (69%) were male and 13 (31%) were female. The mean duration of diabetes before dialysis was 12 years. Eleven patients (40%) were on dietary control alone, seven patients (24%) on oral hypoglycaemic control and ten patients (36%) on insulin treatment. Blood glucose control between these groups did not differ significantly. There was a significant gain in dry weight from a mean of 60.3 kg prior to dialysis to 74 kg two years after dialysis. There was no significant improvement in the haemoglobin level. Blood triglyceride levels increased from 214 +/- 63 mgm/dl to 283 mgm +/- 156 mgm/dl with an insignificant reduction in the cholesterol level. Serum calcium levels increased significantly from 8.0 +/- 1.3 to 9.1 +/- 1.0 mgm/dl in 12 months (p < 0.05). Serum alkaline phosphatase level remained stable. Blood pressure was stable throughout the dialysis period. Adequacy of dialysis clearance was shown by the mean value of serum urea 115 +/- 40 mgm/dl, serum creatinine 10.6 +/- 2.7 mgm/dl and serum phosphate 4.65 +/- 1.6 mgm/dl after two years on CAPD. No peritoneal membrane failure was reported.(ABSTRACT TRUNCATED AT 250 WORDS)