Human hypertension caused by mutations in WNK kinases.

Hypertension is a major public health problem of largely unknown cause. Here, we identify two genes causing pseudohypoaldosteronism type II, a Mendelian trait featuring hypertension, increased renal salt reabsorption, and impaired K+ and H+ excretion. Both genes encode members of the WNK family of serine-threonine kinases. Disease-causing mutations in WNK1 are large intronic deletions that increase WNK1 expression. The mutations in WNK4 are missense, which cluster in a short, highly conserved segment of the encoded protein. Both proteins localize to the distal nephron, a kidney segment involved in salt, K+, and pH homeostasis. WNK1 is cytoplasmic, whereas WNK4 localizes to tight junctions. The WNK kinases and their associated signaling pathway(s) may offer new targets for the development of antihypertensive drugs.

Interpreting regulatory authority guidance on immunosuppressive therapy for renal transplantation: a response to the UK's National Institute for Clinical Excellence (NICE).

AIMS: A group of UK consultant transplant physicians and surgeons (the Consensus Group) met to consider the implications and interpretation of the National Institute for Clinical Excellence's (NICE) Technology Appraisal No. 85 on the use of immunosuppressive therapy for renal transplantation in adults. METHODS: This group considered what the implications of these guidelines might be for clinical practice and consensus was developed on those areas which were potentially open to different interpretations. A wider survey of nephrologists and transplant surgeons throughout the UK was also performed to gauge the impact of the NICE recommendations. RESULTS AND CONCLUSIONS: The outcome of the discussions of the Consensus Group are presented with particular reference to the recommendations of how to respond to calcineurin inhibitor (CNI) intolerance. The survey suggested that the publication of this NICE guidance has resulted in relatively few changes in prescribing practice: UK transplant centers continue to use a wide range of locally developed protocols for immunosuppressive therapy. These include the use of agents such as mycophenolate mofetil (MMF) and sirolimus, despite the fact that both drugs appeared to receive only conditional acceptance in the NICE Guidelines.

Angioplasty and STent for Renal Artery Lesions (ASTRAL trial): rationale, methods and results so far.

Atherosclerotic renovascular disease (ARVD) is a relatively common condition which may lead to progressive renal dysfunction, and eventually to end-stage renal failure. Revascularization has been used in an attempt to prevent progression of ARVD, despite a lack of evidence for a benefit on kidney function. Therefore, large-scale randomized trials are needed to determine reliably whether or not there is any worthwhile benefit. The Angioplasty and STent for Renal Artery Lesions (ASTRAL) trial comparing renal function in ARVD patients randomized to either revascularization or medical management alone was designed to provide this evidence. ASTRAL started recruiting in November 2000 and, as of the end of 2006, 731 patients have been randomized into the trial (19 patients short of its minimum target of 750 patients). A pooled analysis (not split by treatment arm) of all patients shows that serum creatinine increased in the first 6 months then remained relatively steady, whereas blood pressure has decreased from baseline. The trial is due to close to recruitment in April 2007, with the first presentation of the results of the randomized treatment comparison planned for the spring of 2008. To date ASTRAL is by far the largest randomized trial in ARVD, and will provide the most reliable and timely evidence on the role, if any, of revascularization in ARVD with which to guide the treatment of future patients.

Liposome-entrapped contact inhibitory factor: transfer of capacity for density-dependent growth to melanoma cells.

Contact inhibitory factor (CIF) is a growth inhibitor obtained from conditioned culture medium of a contact-inhibited line of hamster melanocytic cells, which reversibly restores density-, anchorage-, and serum-dependent growth to melanoma cells. The usefulness of liposomes as carriers for CIF was investigated in vitro. The stability of liposomes prepared both with and without CIF was demonstrated by measuring the rate of efflux of a K2CrO4 marker. Anionic multilamellar lipid vesicles (7 phosphatidylcholine:2 dicetyl phosphate:1 cholesterol) prepared with CIF-containing material and separated from unentrapped CIF by gel filtration on Sepharose 2B, showed retarded leakage of a K2CrO4 marker (half-efflux at 77 h) when compared with identical liposomes lacking CIF (half-efflux at 40 h). When added to subconfluent cultures of hamster melanoma cells, liposome-entrapped CIF restored contact-inhibited growth. Compared with aqueous solutions of CIF, liposome-CIF effects were characterized by longer latency and more sustained duration. The ability of CIF-bearing liposomes to effectively restore density-dependent growth in vitro should facilitate in vivo studies of the effects of this potent growth inhibitor on melanoma and other neoplasms.

Contact inhibitory factor also restores anchorage and serum dependence to hamster melanoma cells.

Conditioned medium (CM) from confluent cultures of the contact-inhibited hamster melanocytic cell line, FF, contains a biologic activity, contact inhibitory factor (CIF), which reversibly restores density-dependent growth to melanoma cells. When a hydrophobic affinity-concentrated extract of CIF-containing CM was incorporated in agarose at a concentration of 1000 micrograms protein/ml, it restored anchorage-dependent growth to RPMI 1846 hamster melanoma cells. Colony-forming efficiency in CIF-treated wells decreased to 5% from levels of 51.5% in controls prepared with regular growth medium. In addition, CIF-containing CM restored serum-dependent growth to RPMI 1846 cells, markedly restricting proliferation in 1% calf serum-containing medium. Control cultures containing 1% calf serum and either complete growth medium or CM from the non-contact-inhibited hamster melanoma line itself, supported proliferation of RPMI 1846 cells to levels 3.9 X and 3.7 X that of CIF-treated cultures, respectively. CIF is the first factor derived from contact-inhibited mammalian cell cultures that has been shown to restore density-, anchorage-, and serum-dependent growth to malignant melanoma cells.

Expression of vitiligo antigen on a revertant line of hamster melanoma cells.

Our laboratory has recently reported that over 80% of patients with common vitiligo have circulating antibodies to cell-surface antigens on normal human melanocytes. The slow growth rate of these cells limits the assays that can be performed for antibody detection. We now have found that the antigens defined by vitiligo sera on melanocytes are also expressed on FF cells, a revertant line of hamster melanoma cells. These antigens can be detected both by indirect immunofluorescence and specific immunoprecipitation assays. The presence of "vitiligo" antigens on hamster FF cells will aid further study of the abnormal immune response in vitiligo.

Ambulatory blood pressure and left ventricular mass in cyclosporin- and non-cyclosporin-treated renal transplant recipients.

OBJECTIVES: First, to determine the relationship between left ventricular mass (LVM) and clinic and 24-h ambulatory blood pressure parameters in normotensive renal transplant recipients. Secondly, to assess the influence of immunosuppression protocol on diurnal blood pressure and target-organ response. DESIGN: Measurement of supine clinic blood pressure, non-invasive 24-h ambulatory blood pressure and echocardiographically determined LVM. PATIENTS: Twenty-eight stable, normotensive renal transplant recipients taking no antihypertensive therapy (16 cyclosporin-treated and 12 non-cyclosporin-treated). SETTING: Community-based ambulatory patients reviewed in tertiary referral centre. MAIN OUTCOME MEASURES: Clinic blood pressure, mean 24-h, daytime and night-time ambulatory blood pressure and LVM. RESULTS: Mean 24-h blood pressure exceeded that recorded in the clinic. Twenty-five per cent of patients had left ventricular hypertrophy despite the absence of hypertension, and this was more common in cyclosporin-treated than in non-cyclosporin-treated patients. Mean daytime systolic blood pressure was the best predictor of LVM, being superior to clinic blood pressure and any diastolic blood pressure parameter. An attenuated nocturnal blood pressure fall ('non-dipper' pattern) was common, especially in those patients treated with cyclosporin, and was associated with higher LVM. CONCLUSION: In normotensive renal transplant recipients, a group at risk of cardiovascular disease, 24-h ambulatory blood pressure is closely related to the development of left ventricular hypertrophy, and may prove useful in optimizing treatment strategies to reduce cardiovascular morbidity.

Acute reversal of cyclosporine nephrotoxicity by neutral endopeptidase inhibition in stable renal transplant recipients.

BACKGROUND: Atrial natriuretic peptide and cyclosporine have opposing effects on renal hemodynamics and excretory function. METHODS: Twelve male stable cyclosporine-treated renal transplant recipients received a single 100-mg i.v. dose of the neutral endopeptidase EC 24.11 inhibitor candoxatrilat in a double-blind, placebo-controlled cross-over study. Each study day consisted of 2 hr of baseline and 7 hr of postdose evaluation. RESULTS: After administration of candoxatrilat, plasma atrial natriuretic factor rose from 12.8+/-1.6 (mean +/- SEM) to 44.1+/-6.8 pmol/L (P<0.001) in association with a threefold increase in urine cGMP excretion (573+/-195 pmol/min baseline to 1823+/-545 pmol/ min; P<0.001), marked natriuresis (207+/-34 micromol/min baseline to 416+/-62 micromol/min; P<0.001), fractional sodium excretion (3.3+/-0.5% baseline to 5.6+/-0.7%; P<0.01), and diuresis (3.4+/-0.5 ml/min baseline to 7.4+/-1 ml/min; P<0.001). All parameters remained elevated above baseline for the remaining 7-hr study period. In response to candoxatrilat, the glomerular filtration rate rose by 19% (P=0.01), renal plasma flow by 7% (P=0.04), renal blood flow by 13% (P=0.03) in association with an increase in filtration fraction from 24+/-2% to 28+/-2% (P=0.002) and small fall in renal vascular resistance from 0.38+/-0.04 to 0.30+/-0.04 mmHg x min x 1.73 m2 x ml(-1) (P=0.02). There was a fall in plasma angiotensin II without a change in plasma renin concentration or plasma aldosterone. Median urinary albumin excretion increased after candoxatrilat administration from 48 (3-131) to 114 (32-641) microg/min (P<0.01). CONCLUSIONS: Acute neutral endopeptidase inhibition with candoxatrilat appears to reverse the adverse renal hemodynamic and renal excretory effects of cyclosporine in stable renal transplant recipients.

Chronic renal failure following liver transplantation: a retrospective analysis.

BACKGROUND: Liver transplant recipients are at risk of chronic renal disease, principally as a result of nephrotoxicity of the commonly used immunosuppressive agents cyclosporine and tacrolimus. We have investigated the incidence of chronic renal failure and its risk factors in our transplant population, which was treated predominantly with cyclosporine. METHODS: A single-center retrospective study was done of 883 consecutive adult patients receiving a first liver transplant between 1982 and 1996. Potential risk factors for the development of chronic renal failure were recorded, including serial measurements of cyclosporine therapy and renal function. RESULTS: Severe chronic renal failure (serum creatinine level >250 microM/L for at least 6 months) developed in 25 patients, representing 4% of patients surviving 1 year or more. Twelve of these patients developed end-stage renal failure and mortality was 44%. The predominant cause of renal failure was cyclosporine nephrotoxicity. Serum creatinine as early as 3 months after surgery was strongly associated with the eventual development of severe chronic renal failure (P=0.001), and this group could be further subdivided into two groups with differing risk factors. The first group had early (<1 year) renal dysfunction, with older age (P=0.03), cytomegalovirus infection (P=0.03), need for perioperative renal replacement therapy (P=0.06), and regrafting (P=0.06) as risk factors for eventual renal failure; the second group had late-onset (>1 year) renal dysfunction, with cyclosporine levels at 1 month after surgery (P=0.007) and daily and cumulative cyclosporine dosage at 5 years (P=0.01 for both) as risk factors. CONCLUSIONS: With improved survival of liver transplant recipients, chronic renal failure has become an important cause of morbidity and is associated with a high mortality. Many patients at risk of severe chronic renal failure may be identified at an early stage. Treatment regimens that avoid or prevent cyclosporine-induced nephrotoxicity are urgently required for this population.

Recovery of renal function after autologous stem cell transplantation in myeloma patients with end-stage renal failure.

The disease-free survival of patients with myeloma and severe renal failure after high-dose melphalan and autologous stem cell rescue is similar to those with normal renal function at the time of the autograft. However, recovery of renal function after intensive treatment is uncommon and patients with end-stage renal failure continue to be dialysis-dependent. We report two patients with myeloma who required regular haemodialysis from diagnosis, but became dialysis-independent after a high-dose melphalan autograft. Thus, in some patients, renal function may be partially salvageable despite the requirement for dialysis at the time of autografting.

Urinary albumin excretion: a predictor of glomerular findings in adults with microscopic haematuria.

BACKGROUND: Microscopic haematuria without proteinuria is a common clinical finding. When urological causes are excluded, usual findings on renal biopsy are IgA nephropathy (which can progress to end-stage renal failure) or thin basement membrane nephropathy (which has an excellent prognosis). A non-invasive test to discriminate between the two would be useful. AIM: To examine the value of measurement of urinary albumin excretion in discriminating glomerular causes of microscopic haematuria in patients without proteinuria on urine dipstick tests. DESIGN: Single-centre retrospective cross-sectional observational study. METHODS: Adult patients who underwent renal biopsy for microscopic haematuria over a 6-year period from January 1994 were identified. Study entry required normal renal function, no proteinuria detected by dipstick, and urinary albumin excretion <300 mg/24 h. Patients with IgA nephropathy had follow-up for a mean of 58 months after biopsy. RESULTS: Of 169 patients fulfilling study criteria, 119 (70%) had normoalbuminuria (<30 mg/24 h); 52 (30%) had microalbuminuria (30-299 mg/24 h). Of those with normoalbuminuria, 106 (89%) had thin basement membrane nephropathy or no glomerular abnormality. Thirteen (11%) had IgA nephropathy, and of 12 of these followed-up for a mean 64 months, none developed overt, dipstick-positive proteinuria. In contrast, 24 (48%) of those with microalbuminuria had IgA nephropathy, and of 22 followed-up for a mean 55 months, five developed overt proteinuria. DISCUSSION: Urinary albumin excretion is an indicator of likely glomerular findings in microscopic haematuria, and may influence whether a renal biopsy is necessary.

Genotypic and phenotypic properties of coagulase-negative staphylococci causing dialysis catheter-related sepsis.

Sixty coagulase-negative staphylococcus (CNS) isolates were recovered from the blood cultures or peritoneal dialysate effluent of 43 patients on renal dialysis. The patients had either renal dialysis catheter-related sepsis (CRS) or continuous ambulatory peritoneal dialysis (CAPD)-associated peritonitis. Isolates were characterized by biotyping, and genotyped by pulsed-field gel electrophoresis (PFGE). Phenotypic properties of the strains were also investigated. Several genotypes were identified with no one specific strain of CNS being associated with CRS. However, closely related strains were isolated from several patients within the units studied, suggesting horizontal transfer of micro-organisms. Genotypic macro-restriction profiles did not concur with phenotypic profiles or biotypes, confirming that genotyping is required for epidemiological studies. All staphylococcal strains were investigated for the production of phenotypic characteristics. Significant differences were predominantly seen in the production of lipase, esterase and elastase in strains isolated from the renal patients with CRS and CAPD-associated peritonitis, compared with a non-septic control group. These phenotypic characteristics may therefore have a role in the maintenance of CRS in renal patients.

Improving prescribing using a rule based prescribing system.

OBJECTIVE: To test the hypothesis that the prescribing behaviour of doctors would improve after having experience with a computerised rule based prescribing system. DESIGN: A prospective observational study of changes in prescribing habits resulting from the use of a computerised prescribing system in (1) a cohort of experienced users compared with a new cohort, and (2) a single cohort at the beginning and after 3 weeks of computer aided prescribing. SETTING: 64 bed renal unit in a teaching hospital. INTERVENTION: Routine use of a computerised prescribing system by doctors and nurses on a renal unit from 1 July to 31 August 2001. MAIN OUTCOME MEASURES: Number of warning messages generated by the system; proportion of warning messages overridden; comparison between doctors of different grades; comparison by doctors' familiarity with the system. RESULTS: A total of 51,612 records relating to 5995 prescriptions made by 103 users, of whom 42 were doctors, were analysed. The prescriptions generated 15,853 messages, of which 6592 were warning messages indicating prescribing errors or problems. Doctors new to the system generated fewer warning messages after using the system for 3 weeks (0.81 warning messages per prescription v 0.42 after 3 weeks, p = 0.03). Doctors with more experience of the system were less likely to generate a warning message (Spearman's rho = -0.90, p = 0.04) but were more likely to disregard one (Spearman's rho = -1, p<0.01). Senior doctors were more likely than junior doctors to ignore a warning message. CONCLUSIONS: Doctors are influenced by the experience of using a computerised prescribing system. When judged by the number of warning messages generated per prescription, their prescribing improves with time and number of prescriptions written. Consultants and registrars are more likely to use their clinical judgement to override warning messages regarding prescribed drugs.

Atherosclerotic renal artery stenosis: is it worth diagnosing?

Atherosclerotic renal artery stenosis (ARAS) is the commonest cause of secondary hypertension and is the cause of end stage renal failure in up to 20% of patients starting dialysis. Associated with it is a high morbidity and appalling mortality. The aetiology of ischaemic nephropathy is complex and is not simply related to renal artery narrowing. Captopril renography is sensitive and specific for diagnosing ARAS in patients with normal renal function. In those with renal impairment gadolinium-enhanced MRA or spiral CT angiography clearly define renal anatomy. Over 80% of ARAS is ostial. Studies of revascularisation with angioplasty show poor short and long term patency rates. Renal artery stenting leads to high initial technical success and long term patency. Recent randomised controlled trials in patients with renovascular hypertension demonstrate no clear benefit of adequate revascularisation over medical therapy. Renal artery stenting for renal protection in ARAS appears more encouraging and current randomised controlled trials are in progress to answer the question definitively.