Capacity for the management of kidney failure in the International Society of Nephrology Middle East region: report from the 2023 ISN Global Kidney Health Atlas (ISN-GKHA)

The highest financial and symptom burdens and the lowest health-related quality-of-life scores are seen in people with kidney failure. A total of 11 countries in the International Society of Nephrology (ISN) Middle East region responded to the ISN-Global Kidney Health Atlas. The prevalence of chronic kidney disease (CKD) in the region ranged from 4.9% in Yemen to 12.2% in Lebanon, whereas prevalence of kidney failure treated with dialysis or transplantation ranged from 152 per million population (pmp) in the United Arab Emirates to 869 pmp in Kuwait. Overall, the incidence of kidney transplantation was highest in Saudi Arabia (20.2 pmp) and was lowest in Oman (2.2 pmp). Chronic hemodialysis (HD) and peritoneal dialysis (PD) services were available in all countries, whereas kidney transplantation was available in most countries of the region. Public government funding that makes acute dialysis, chronic HD, chronic PD, and kidney transplantation medications free at the point of delivery was available in 54.5%, 72.7%, 54.5%, and 54.5% of countries, respectively. Conservative kidney management was available in 45% of countries. Only Oman had a CKD registry; 7 countries (64%) had dialysis registries, and 8 (73%) had kidney transplantation registries. The ISN Middle East region has a high burden of kidney disease and multiple challenges to overcome. Prevention and detection of kidney disease can be improved by the design of tailored guidelines, allocation of additional resources, improvement of early detection at all levels of care, and implementation of sustainable health information systems.

Impact of Sodium-Glucose Cotransporter-2 Inhibitors in the Management of Chronic Kidney Disease: A Middle East and Africa Perspective

Chronic kidney disease (CKD) is a major public health concern in the Middle East and Africa (MEA) region and a leading cause of death in patients with type 2 diabetes mellitus (T2DM) and hypertension. Early initiation of sodium-glucose cotransporter - 2 inhibitors (SGLT-2i) and proper sequencing with renin-angiotensin-aldosterone system inhibitors (RAASi) in these patients may result in better clinical outcomes due to their cardioprotective properties and complementary mechanisms of action. In this review, we present guideline-based consensus recommendations by experts from the MEA region, as practical algorithms for screening, early detection, nephrology referral, and treatment pathways for CKD management in patients with hypertension and diabetes mellitus. This study will help physicians take timely and appropriate actions to provide better care to patients with CKD or those at high risk of CKD.

Biospecimen Repositories in Low- and Middle-Income Countries: Insights From an American University of Beirut and Memorial Sloan Kettering Collaboration

PURPOSE

Biobanking helps source tissue and blood for studying cancer genomics. Access to biorepository resources in low- and middle-income countries is lacking. Memorial Sloan Kettering Cancer Center (MSK) and the American University of Beirut (AUB) established a joint tissue biorepository at AUB in Beirut, Lebanon. The undertaking encountered key challenges that were unanticipated.

MATERIALS AND METHODS

Patients age 18 years or older were eligible for enrollment at AUB. After consent, biospecimens were obtained at the time of routine diagnostic and/or therapeutic interventions. Both normal and abnormal tissue and solid and/or liquid specimens were collected from varied body sites. Early on, declining consent was frequently observed, and this was highlighted for investigation to understand potential participants reasoning.

RESULTS

Of 850 patients approached, 704 (70.8%) elected to consent and 293 (29.5%) declined participation. The number of declined consents led to an amendment permitting the documentation of reasons for same. Of 100 potential participants who declined to consent and to whom outreach was undertaken, 63% indicated lack of research awareness and 27% deferral to their primary physician or family member. A financial gain for AUB was cited as concern by 5%, cultural boundaries in 4%, and 1% expressed concern about confidentiality. Of the patients who elected to consent, 682 biospecimens were procured.

CONCLUSION

The AUB-MSK biospecimen repository has provided a unique resource for interrogation. Patient participation rate was high, and analyses of those who elected not to consent (29%) provide important insights into educational need and the local and cultural awareness and norms.

Recommendations for Early and Comprehensive Management of Type 2 Diabetes and Its Related Cardio-Renal Complications

Type 2 diabetes (T2D) is a global health problem accompanied by an elevated risk of complications, the most common being cardiac and renal diseases. In Lebanon, the prevalence of T2D is estimated at 8-13%. Local medical practice generally suffers from clinical inertia, with gaps in the yearly assessment of clinical manifestations and suboptimal screening for major complications. The joint statement presented here, endorsed by five Lebanese scientific medical societies, aims at providing physicians in Lebanon with a tool for early, effective, and comprehensive care of patients with T2D. Findings from major randomized clinical trials of antidiabetic medications with cardio-renal benefits are presented, together with recommendations from international medical societies. Optimal care should be multidisciplinary and should include a multifactorial risk assessment, lifestyle modifications, and a regular evaluation of risks, including the risks for cardiovascular (CV) and renal complications. With international guidelines supporting a shift in T2D management from glucose-lowering agents to disease-modifying drugs, the present statement recommends treatment initiation with metformin, followed by the addition of sodium-glucose cotransporter 2 inhibitors or glucagon-like peptide-1 receptor agonists due to their CV and renal protection properties, whenever possible. In addition to the selection of the most appropriate pharmacological therapy, efforts should be made to provide continuous education to patients about their disease, with the aim to achieve a patient-centered approach and to foster self-management and adherence to the medical plan. Increasing the level of patient engagement is expected to be associated with favorable health outcomes. Finally, this statement recommends setting an achievable individualized management plan and conducting regular follow-ups to monitor the patients' glycemic status and assess their risks every 3-6 months.

Collagenofibrotic glomerulopathy in a kidney transplant recipient: A first report

Collagenofibrotic glomerulopathy (CG) is a rare disease characterized by the deposition of collagen type 3 fibrils in the glomeruli. Patients may have proteinuria, hematuria, and/or renal dysfunction. CG is considered a progressive disease with variable rates of progression. The definitive diagnosis is made by electron microscopy with the presence of characteristic subendothelial and mesangial curved, comma-like, banded collagen type 3 fibers of 40-65 nm periodicity. We are reporting the first case of CG in a kidney transplant recipient with kidney disease of unknown cause.

International Society of Nephrology Global Kidney Health Atlas: structures, organization, and services for the management of kidney failure in the Middle East

Kidney failure is the permanent impairment of kidney function associated with increased morbidity, hospitalization, and requirement for kidney replacement therapy. A total of 11 countries in the Middle East region (84.6%) responded to the survey. The prevalence of chronic kidney disease in the region ranged from 5.2% to 10.6%, whereas prevalence of treated kidney failure ranged from 152 to 826 per million population. Overall, the incidence of kidney transplantation was highest in Iran (30.9 per million population) and lowest in Oman and the United Arab Emirates (2.2 and 3.0 per million population, respectively). Long-term hemodialysis services were available in all countries, long-term peritoneal dialysis services were available in 9 (69.2%) countries, and transplantation services were available in most countries of the region. Public funding covered the costs of nondialysis chronic kidney disease care in two-thirds of countries, and kidney replacement therapy in nearly all countries. More than half of the countries had dialysis registries; however, national noncommunicable disease strategies were lacking in most countries. The Middle East is a region with high burden of kidney disease and needs cost-effective measures through effective health care funding to be available to improve kidney care in the region. Furthermore, well-designed and sustainable health information systems are needed in the region to address current gaps in kidney care in the region.

Corrigendum to "Tonelli M, Nkunu V, Varghese C, et al. Framework for establishing integrated kidney care programs in low- and middle-income countries" Kidney Int Suppl. 2020;10:e19-e23

[This corrects the article DOI: 10.1016/j.kisu.2019.11.002.].

Considerations on equity in management of end-stage kidney disease in low- and middle-income countries

Achievement of equity in health requires development of a health system in which everyone has a fair opportunity to attain their full health potential. The current, large country-level variation in the reported incidence and prevalence of treated end-stage kidney disease indicates the existence of system-level inequities. Equitable implementation of kidney replacement therapy (KRT) programs must address issues of availability, affordability, and acceptability. The major structural factors that impact equity in KRT in different countries are the organization of health systems, overall health care spending, funding and delivery models, and nature of KRT prioritization (transplantation, hemodialysis or peritoneal dialysis, and conservative care). Implementation of KRT programs has the potential to exacerbate inequity unless equity is deliberately addressed. In this review, we summarize discussions on equitable provision of KRT in low- and middle-income countries and suggest areas for future research.

Framework for establishing integrated kidney care programs in low- and middle-income countries

Secular increases in the burden of kidney failure is a major challenge for health systems worldwide, especially in low- and middle-income countries (LMICs) due to growing demand for expensive kidney replacement therapies. In LMICs with limited resources, the priority of providing kidney replacement therapies must be weighed against the prevention and treatment of chronic kidney disease, other kidney disorders such as acute kidney injury, and other noncommunicable diseases, as well as other urgent public health needs. Kidney failure is potentially preventable-not just through primary prevention of risk factors for kidney disease such as hypertension and diabetes, but also by timely management of established chronic kidney disease. Among people with established or incipient kidney failure, there are 3 key treatment strategies-conservative care, kidney transplantation, and dialysis-each of which has its own benefits. Joining up preventive care for people with or at risk for milder forms of chronic kidney disease with all 3 therapies for kidney failure (and developing synergistic links between the different treatment options) is termed "integrated kidney care" and has potential benefits for patients, families, and providers. In addition, because integrated kidney care implicitly considers resource use, it should facilitate a more sustainable approach to managing kidney failure than providing one or more of its components separately. There is currently no agreed framework that LMIC governments can use to establish and/or scale up programs to prevent and treat kidney failure or join up these programs to provide integrated kidney care. This review presents a suggested framework for establishing integrated kidney care programs, focusing on the anticipated needs of policy makers in LMICs.

Hungry bone syndrome two weeks after starting cinacalcet: a call for caution

Cinacalcet is an effective and safe alternative to parathyroidectomy in end stage renal disease (ESRD) patients with secondary hyperparathyroidism. Hypocalcemia is a known complication of treatment that is usually readily reversible upon discontinuation of the drug. It rarely manifests severely and symptomatically requiring hospital admission. We present the case of a 55 year old man with severe, symptomatic and prolonged hypocalcemia that occurred 2 weeks after starting cinacalcet. Cinacalcet induced a state of pharmacological parathyroidectomy with subsequent hungry bone syndrome. Serum calcium returned to normal range after 4 weeks of stopping the drug while receiving high doses of elemental calcium and vitamin D receptor activation therapy (VDRA).

Effects of weight reduction regimens and bariatric surgery on chronic kidney disease in obese patients

Increasing evidence nowadays is showing that obesity by itself, independent of other comorbidities like diabetes and hypertension, is associated with renal functional changes and structural damage. Intentional weight loss demonstrates beneficial reduction in proteinuria and albuminuria in patients with mild to moderate chronic kidney disease, particularly those whose renal damage is likely induced by obesity. The safety of some weight loss interventions, particularly the use of high-protein diets and/or medications, is questionable in this population due to the lack of well-designed randomized controlled studies reporting on their efficacy or harm. Bariatric surgery showed the most promising results with regards to ameliorating glomerular hyperfiltration and albuminuria albeit with a modest risk of increased perioperative complications with advanced stages of chronic kidney disease (CKD).

Nephrogenic systemic fibrosis and gadolinium-based contrast agents

The strong association between nephrogenic systemic fibrosis (NSF) and exposure to gadolinium-based contrast agents (GBCAs) has greatly affected the care of patients with kidney disease. NSF has been reported in patients with ESRD, CKD, and acute kidney injury (AKI). The majority of cases have occurred in patients with ESRD, but about 20% have been reported in patients with AKI or CKD stages 4 and 5. There is also a risk difference among GBCAs, with the Food and Drug Administration contraindicating 3 linear agents in patients at risk. Given the significant morbidity and mortality of NSF, it is imperative to identify individuals at risk. Although there are no data to support a role for hemodialysis (HD) in reducing the risk for NSF after administration of GBCAs, immediate HD is still recommended within 2 hours. Patients maintained on peritoneal dialysis seem to be at high risk and immediate HD is also recommended. However, this is not the current recommendation for CKD stages 4 and 5, especially with suspected lower risk of noncontraindicated agents. Individualized assessment is important and especially in those patients close to dialysis initiation. Instituting policies is important to address the imaging needs of patients with CKD and AKI while ensuring a balance between benefits and risks.

Tumor lysis syndrome and acute kidney injury: evaluation, prevention, and management

Tumor lysis syndrome (TLS) describes a constellation of biochemical and clinical abnormalities resulting from rapid and massive tumor cell death. TLS is frequently associated with hyperuricemia, hyperkalemia, hyperphosphatemia, and secondary hypocalcemia that may lead to serious clinical complications, including acute kidney injury and cardiac arrest. Identification of tumor- and patient-specific risk factors for TLS and early recognition of laboratory and clinical TLS based on established criteria are essential for preventing TLS and forestalling acute kidney injury. Early collaboration between oncologists and nephrologists will help improve assessment of patients' kidney function and risk factors, paving the way for timely and efficacious interventions.

Gadolinium-containing magnetic resonance image contrast agent promotes fibrocyte differentiation

Gadolinium-containing magnetic resonance imaging (MRI) contrast agents such as Omniscan are associated with nephrogenic systemic fibrosis (NSF). To determine if Omniscan can affect the differentiation of monocytes into fibroblast-like cells called fibrocytes that are found in the fibrotic lesions of NSF, peripheral blood mononuclear cells (PBMCs) from NSF patients, hemodialysis patients without NSF, and healthy, renally sufficient controls were exposed to Omniscan in a standardized in vitro fibrocyte differentiation protocol. When added to PBMCs, the gadolinium-containing MRI contrast agent Omniscan generally had little effect on fibrocyte differentiation. However, 10(-8) to 10(-3) mg/mL Omniscan reduced the ability of the fibrocyte differentiation inhibitor serum amyloid P (SAP) to decrease fibrocyte differentiation in PBMCs from 15 of 17 healthy controls and one of three NSF patients. Omniscan reduced the ability of SAP to decrease fibrocyte differentiation from purified monocytes, indicating that the Omniscan effect does not require the presence of other cells (such as T cells) in the PBMCs. Omniscan also reduced the ability of a different fibrocyte differentiation inhibitor, interleukin-12, to decrease fibrocyte differentiation. These data suggest that Omniscan interferes with the regulatory action of signals that inhibit the differentiation of monocytes to fibrocytes. J. Magn. Reson. Imaging 2009;30:1284-1288. (c) 2009 Wiley-Liss, Inc.

Successful use of intraperitoneal daptomycin in the treatment of vancomycin-resistant enterococcus peritonitis

Peritoneal dialysis-associated peritonitis from such resistant organisms as vancomycin-resistant enterococci increasingly is occurring and is challenging to treat. We describe 2 cases of vancomycin-resistant entercoccus peritonitis successfully treated with intraperitoneal daptomycin. Both patients were on automated peritoneal dialysis therapy with culture-positive vancomycin-resistant Enterococcus faecium peritonitis and were treated with 10 to 14 days of intraperitoneal daptomycin given every 4 hours through manual peritoneal dialysate exchanges. Despite the known degradation in dextrose solutions, intraperitoneal daptomycin was effective in clearing both infections. Neither patient experienced a relapse or repeated peritonitis. Additional studies of dosing and pharmacokinetics of intraperitoneal daptomycin in the treatment of patients with vancomycin-resistant enterococcus peritonitis are needed.

Long-term comparison of sevelamer hydrochloride to calcium-containing phosphate binders

AIM

In patients with end-stage renal disease (ESRD), hyperphosphataemia and an elevated calcium-phosphorus (Ca-P) product contribute to morbidity and mortality. Suggested target goals for serum phosphorus concentration and calcium-phosphorus product have recently been lowered. As a result, long-term comparative studies of the efficacy of phosphate binders are critical. This study compares the long-term efficacy of sevelamer hydrochloride to calcium-containing binders (CCB).

METHODS

A retrospective chart review was conducted in 30 patients receiving sevelamer hydrochloride for >1 years and 25 patients receiving CCB.

RESULTS

Patients on sevelamer hydrochloride had lower serum bicarbonate concentration than those on CCB, 18.6 +/- 2.7 versus 20.3 +/- 1.8 mmol/L (P = 0.0017). Serum phosphorus concentration was higher in patients on sevelamer hydrochloride compared to CCB 2.10 +/- 0.87 versus 1.74 +/- 0.28 mmol/L (P = 0.0013), as was the Ca-P product 4.97 +/- 0.94 mmol2L2 (62.1 +/- 11.8 mg2/dL2) versus 3.97 +/- 1.18 mmol2/L2 (49.7 +/- 14.7 mg2/dL2), P = 0.0009). Only 36% of patients on sevelamer hydrochloride compared with 68% on CCB (P = 0.015) met the serum phosphorus goal of < or =1.78 mmol/L.

CONCLUSION

Patients on sevelamer hydrochloride for >1 years compared to those on CCB had a lower serum bicarbonate concentration, a higher serum phosphorus concentration and a higher Ca-P product. Clinicians should balance the increase in calcium load with CCB versus the cost and effectiveness of sevelamer hydrochloride in choosing a phosphate binder for ESRD patients.

Cinacalcet for secondary hyperparathyroidism in patients receiving hemodialysis

BACKGROUND

Treatment of secondary hyperparathyroidism with vitamin D and calcium in patients receiving dialysis is often complicated by hypercalcemia and hyperphosphatemia, which may contribute to cardiovascular disease and adverse clinical outcomes. Calcimimetics target the calcium-sensing receptor and lower parathyroid hormone levels without increasing calcium and phosphorus levels. We report the results of two identical randomized, double-blind, placebo-controlled trials evaluating the safety and effectiveness of the calcimimetic agent cinacalcet hydrochloride.

METHODS

Patients who were receiving hemodialysis and who had inadequately controlled secondary hyperparathyroidism despite standard treatment were randomly assigned to receive cinacalcet (371 patients) or placebo (370 patients) for 26 weeks. Once-daily doses were increased from 30 mg to 180 mg to achieve intact parathyroid hormone levels of 250 pg per milliliter or less. The primary end point was the percentage of patients with values in this range during a 14-week efficacy-assessment phase.

RESULTS

Forty-three percent of the cinacalcet group reached the primary end point, as compared with 5 percent of the placebo group (P<0.001). Overall, mean parathyroid hormone values decreased 43 percent in those receiving cinacalcet but increased 9 percent in the placebo group (P<0.001). The serum calcium-phosphorus product declined by 15 percent in the cinacalcet group and remained unchanged in the placebo group (P<0.001). Cinacalcet effectively reduced parathyroid hormone levels independently of disease severity or changes in vitamin D sterol dose.

CONCLUSIONS

Cinacalcet lowers parathyroid hormone levels and improves calcium-phosphorus homeostasis in patients receiving hemodialysis who have uncontrolled secondary hyperparathyroidism.

Addition of sertraline to other therapies to reduce dialysis-associated hypotension

Sertraline has shown promise in the treatment of dialysis-associated hypotension (DAH) in a limited number of end-stage renal disease patients. We undertook a study to evaluate the effect of adding sertraline to other therapies for patients with documented DAH. We also measured the effect of sertraline on intradialytic haemodynamics. We used the ultrasound dilution technique (HD01 monitor) to measure cardiac output (CO), central blood volume (CBV) and peripheral vascular resistance (PVR) in these patients. The study was performed in two phases. Phase 1 was a control, while the second phase consisted of treatment with sertraline (50 mg/day). Cardiac output and central blood volume were measured 30 min following the initiation of dialysis and 30 min prior to the termination of dialysis. Blood pressure (BP) was monitored during haemodynamic measurements and throughout dialysis. Eighteen patients with documented DAH completed the study. Cardiac output, CBV and PVR were no different in the sertraline phase as compared with the control phase. The declines in systolic BP, diastolic BP and mean arterial pressures from pre-haemodialysis (HD) to lowest intradialytic and pre-HD to post-HD were not significantly different for the sertraline phase versus the control phase. In conclusion, it appears that sertraline has no additive effect on intradialytic haemodynamics to improve blood pressure in patients with DAH who are under therapy (with sodium modelling, cool dialysate and midodrine).

Vascular access surveillance: evaluation of combining dynamic venous pressure and vascular access blood flow measurements

BACKGROUND/AIMS

Vascular access thrombosis is one of the most morbid problems encountered by hemodialysis patients. Surveillance protocols utilizing venous pressure (Vp) and vascular access blood flow (VABF) measurements have been employed to preserve vascular access. We undertook a study to evaluate combined dynamic Vp and VABF measurements in the identification of vascular access impairment. We also assessed the effect of preventive repair on thrombosis rates in impaired vascular accesses identified by surveillance.

METHODS

Eighty-six chronic hemodialysis patients with a functioning vascular access were enrolled into the surveillance protocol. All vascular accesses with greater than 50% of monthly Vp readings >120 mm Hg or VABF <500 ml/min in arteriovenous fistulas (AVFs) and VABF <650 ml/min in arteriovenous grafts (AVGs), or a decrease in VABF >25% compared to the highest previously measured value, were considered positive. Stenosis >50% on fistulography or a thrombotic event were defined as a 'vascular access impairment episode' while a stenosis <50% or the absence of a thrombotic event was defined as 'no vascular access impairment episode'. Thrombosis rates and intervention rates were calculated per access year at risk.

RESULTS

The sensitivity and specificity of the combined surveillance protocol for AVFs were 73.3 and 91%, respectively. In AVGs, they were 68.8 and 87.5%, respectively. The rate of thrombotic events was lower in patients who underwent early repair. The addition of dynamic Vp did not reduce the thrombosis rate any further than surveillance based on VABF alone.

CONCLUSION

Combined monitoring for surveillance of AVFs improved sensitivity but had little benefit in AVGs over VABF monitoring alone. Raising VABF cutoff levels might increase and improve identification of vascular access risk for thrombosis, but at the expense of lower specificity.

Observations on HIV-associated renal disease in the era of highly active antiretroviral therapy

BACKGROUND

Renal disease in patients infected with HIV has evolved to include several lesions, including HIV-associated nephropathy (HIV-AN), which can promote progressive loss of renal function. Although angiotensin-converting enzyme inhibitors and corticosteroids are beneficial in selected patients, the effect of highly active antiretroviral therapy (HAART) on renal function is currently being explored.

METHODS

We undertook a retrospective study to determine the types of renal lesions present in patients infected with HIV with renal insufficiency and/or proteinuria during the era of HAART availability and the effect of HAART on renal outcomes in these patients. Patients with HIV infection referred to the renal clinic from July 1996 through December 2000 were evaluated. Patient characteristics and data were collected including CD4 count, viral load, serum creatinine, blood pressure, proteinuria, renal ultrasound, and biopsy results, and treatment with HAART. Study endpoints were doubling of serum creatinine, initiation of dialysis, or death.

RESULTS

Twenty-three patients met study criteria, 13 received HAART, and 10 did not. Baseline characteristics were similar except for renal function parameters, viral loads, and CD4 counts. A variety of lesions were noted on 12 renal biopsies. A clinical diagnosis of HIV-AN was made in the other 11 patients. Only 2 patients receiving HAART before renal evaluation were noted to have HIV-AN. In the HAART group, none of the patients, including those with HIV-AN, developed a doubling of serum creatinine. In the non-HAART group, all patients manifested a doubling of serum creatinine, 2 patients died, and 8 patients required dialysis.

CONCLUSIONS

A variety of renal lesions are noted in patients infected with HIV during the HAART era. Patients who received HAART maintained stable renal function, whereas patients who did not required dialysis therapy or died with advanced renal failure. It seems that HAART may improve renal outcomes in patients with HIV and renal disease.

Hemodynamics in patients with intradialytic hypotension treated with cool dialysate or midodrine

Cool dialysate and midodrine have been used successfully to treat intradialytic hypotension (IDH) in the end-stage renal disease population. However, the exact mechanisms by which these interventions improve hemodynamic stability are not well known. We undertook a study to evaluate the effect of these modalities on intradialytic hemodynamics in patients with documented dialysis-associated hypotension. We used the ultrasound dilution technique to measure cardiac output (CO), central blood volume (CBV), and peripheral vascular resistance (PVR) in these patients. The study was performed in two phases. Phase 1 consisted of control (1A) and cool dialysate (1B) studies, whereas phase 2 consisted of control (2A) and midodrine (2B) studies. CO, CBV, and PVR were measured 30 minutes after the initiation of hemodialysis (HD) and 30 minutes before the termination of HD using the HD01 monitor. Blood pressure was measured pre-HD and post-HD. Fourteen patients with documented IDH completed the study. CO and CBV were significantly more preserved in the cool dialysate and midodrine phases compared with control phases. PVR increased in all phases of the study. Declines in mean arterial pressures from pre-HD to post-HD were less with cool dialysate versus control and midodrine versus control. Ultrafiltration volumes were not significantly different between phases. Cool dialysate and midodrine appear to improve intradialytic hemodynamics in patients with dialysis-associated hypotension, mainly through the preservation of CBV and CO, rather than significantly elevating PVR.

Treatment of Severe Intradialytic Hypotension With the Addition of High Dialysate Calcium Concentration to Midodrine and/or Cool Dialysate

Treatment of intradialytic hypotension (IDH) in the end-stage renal disease population has been a difficult task for nephrologists caring for these patients. The presence of multiple pathogenic factors contributes to hemodynamic instability and explains why therapies that modulate only a specific aspect of the problem are only partially effective. Cool dialysate (34.5 degrees C to 35.5 degrees C) and midodrine may provide hemodynamic stability through an increase in peripheral vascular resistance, whereas high dialysate calcium concentration (HDCa; 3.5 mEq/L) improves intradialytic blood pressure through preservation of cardiac output. Theoretically, the combination of these two types of therapies might further reduce the frequency and severity of hypotension during hemodialysis (HD). We undertook a study to evaluate the effect of HDCa added to midodrine and/or cool dialysate in the treatment of patients with severe IDH. Twenty-eight patients met the entry criteria, and 23 patients completed the prospective crossover study. Five patients dropped out of the study secondary to hypercalcemia. The addition of HDCa significantly improved post-HD mean arterial pressure (MAP; 95.6 +/- 12.7 versus 90.8 +/- 12.5 mm Hg; P = 0.002). The decreases in MAP from pre-HD to lowest intradialytic (16.3 +/- 8.2 versus 20.6 +/- 10.0 mm Hg; P = 0.009) and pre-HD to post-HD (2.0 +/- 8.5 versus 8.15 +/- 10.8 mm Hg; P = 0.002) were significantly reduced with HDCa compared with low dialysate calcium. However, there were no significant improvements in symptoms of or interventions for IDH. Thus, it appears that the addition of HDCa to midodrine and/or cool dialysate further improves blood pressure in patients with IDH. However, this therapy did not reduce symptoms or interventions required for IDH. In addition, hypercalcemia complicated this therapy in 22% of the patients.

ACE inhibitors do not induce recombinant human erythropoietin resistance in hemodialysis patients

Angiotensin-converting enzyme (ACE) inhibitors may exacerbate anemia in patients with chronic renal failure, as well as in dialysis patients. To better answer this question, a prospective, crossover study was conducted to evaluate the effect of ACE inhibitors on recombinant human erythropoietin (rHuEPO) requirements in hemodialysis patients. Patients administered an ACE inhibitor when entering the study remained on this drug for the initial 4 months and were then switched to another antihypertensive agent for 4 more months. Patients not initially administered an ACE inhibitor were switched to lisinopril at 4 months. rHuEPO doses were adjusted using a sliding scale based on weekly laboratory hematocrit values. The inclusion criteria were met by 51 patients undergoing dialysis. Demographics were as follows: 61% were women, 64% were black, 46% had diabetes, average age was 53.2 +/- 13.3 years, and time on hemodialysis was 38.0 +/- 44.5 months. Thirty-three patients completed the study. Hematocrit averaged 32.7% +/- 1.9% while on ACE inhibitor therapy and 33.1% +/- 2.1% off ACE inhibitor therapy (P = 0.217). There was no difference in rHuEPO dose per treatment during each period (3,500 +/- 1,549 U on ACE inhibitor therapy versus 3,312 +/- 1,492 U off ACE inhibitor therapy; P = 0.300). No significant differences were found in degree of blood pressure control or various clinical and laboratory parameters that might be associated with rHuEPO resistance between the two periods. Similarly, no differences were found in hospitalization days, duration of infections, or transfusion requirements. These findings suggest that ACE inhibitors do not contribute to rHuEPO resistance in hemodialysis patients.

Immunochemical characterization of Na+/H+ exchanger isoform NHE4

Mammalian Na+/H+ exchangers (NHEs) are a family of transport proteins (NHE1-NHE5). To date, the cellular and subcellular localization of NHE4 has not been characterized using immunochemical techniques. We purified a fusion protein containing a portion of rat NHE4 (amino acids 565-675) to use as immunogen. A monoclonal antibody (11H11) was selected by ELISA. It reacted specifically with both the fusion protein and to a 60- to 65-kDa polypeptide expressed in NHE4-transfected LAP1 cells. By Western blot analysis, NHE4 was identified as a 65- to 70-kDa protein that was expressed most abundantly in stomach and in multiple additional epithelial and nonepithelial rat tissues including skeletal muscle, heart, kidney, uterus, and liver. Subcellular localization of NHE4 in the kidney was evaluated by Western blot analysis of membrane fractions isolated by Percoll gradient centrifugation. NHE4 was found to cofractionate with the basolateral markers NHE1 and Na+-K+-ATPase rather than the luminal marker gamma-glutamyl transferase. In stomach, NHE4 was detected by immunoperoxidase labeling on the basolateral membrane of cells at the base of the gastric gland. We conclude that NHE4 is a 65- to 70-kDa protein with a broad tissue distribution. In two types of epithelial cells, kidney and stomach, NHE4 is localized to the basolateral membrane.

Reduction in arteriovenous graft impairment: results of a vascular access surveillance protocol

Impairment of hemodialysis (HD) vascular access, remains a frustrating problem for both the patient who possesses an arteriovenous graft (AVG) and the nephrologist who cares for the patient. We instituted a vascular access surveillance protocol intended to detect and correct evolving stenosis in patients with AVGs. The principal screen was the observation of dynamic venous pressure (VP) at a blood flow rate of 200 mL/min during the first 5 minutes of each HD session. If VP at a blood flow rate of 200 mL/min was 140 mm Hg or greater in three of six consecutive readings, recirculation greater than 15% on two observations, graft-arm swelling observed, or prolonged bleeding postdialysis observed, then the patient was referred for angiography and then angioplasty or surgery if a vascular stenosis of greater than 50% was documented. Sixty-four patients with a synthetic AVG comprised the study group. Seventy-two episodes of AVG impairment (56 with stenosis > or = 50% on angiography, 16 with thrombosis) occurred in these patients during the study period. In 63 of 72 impairment episodes, the preceding vascular access screening test was positive. The calculated sensitivity and specificity of the vascular access protocol was 88% and 81%, respectively. Calculation of the sensitivity and specificity for the VP alone was 81% and 85%, respectively. Comparison of the study group with a similar historical control group (55 patients) showed a significantly lower thrombosis rate (P = 0.03; 95% confidence interval [CI], 0.025 to 0.375) in the study group (0.29 thrombotic episodes/graft-year at risk) versus the historical control group (0.49 thrombotic episodes/graft-year at risk). In summary, a vascular access surveillance protocol is a useful tool to predict patients at risk for AVG venous stenosis and/or thrombosis. A dynamic VP of 140 mm Hg or greater appears to be the optimal threshold pressure. A decrease in synthetic AVG thrombosis rate resulted from the use of this surveillance protocol.

Monoclonal antibodies for high-resolution localization of NHE3 in adult and neonatal rat kidney

Previous immunochemical studies have shown that NHE3 is an apical Na+/H+ exchanger in some renal epithelia. The purpose of the present study was to develop high-affinity, isoform-specific monoclonal antibodies (MAbs) that would be useful for carrying out high-resolution immunocytochemical studies of NHE3 in the adult and neonatal mammalian kidney. Three MAbs were developed to a fusion protein containing amino acids 702-832 of rabbit NHE3. Specificity was established by immunoblotting membranes from NHE-deficient LAP cells that had been transfected with either NHE1,-2, -3, or -4. With the use of high-resolution immunocytochemical techniques, NHE3 was found in vesicles in the apical cytoplasm of proximal tubule cells, as well as in the apical plasma membrane of the proximal tubule, and in both the thin and thick limbs of the loop of Henle. When localized in the 1-day-old rat kidney, NHE3 was first detected in the late stages of the S-shaped body. In later stages of nephron development, the pattern of NHE3 staining was similar to that seen in the adult. This study demonstrates 1) the specificity of three MAbs for Na+/H+ exchanger isoform NHE3; 2) NHE3 is present in an intracellular vesicular compartment in cells of the proximal tubule, consistent with possible regulation by membrane recycling; and 3) NHE3 is expressed on the apical membrane in early stages of the developing nephron.

Cathepsin D in intestinal ganglion cells. A potential aid to diagnosis in suspected Hirschsprung's disease

There is still a need for a better method of detecting immature ganglion cells in paraffin sections of colorectal luminal biopsies in cases suspected of Hirschsprung's disease. The lysosomal aspartic proteinase cathepsin D has been immunolocalized to various cell types, including ganglion cells. We investigated its expression in intestinal ganglion cells to determine whether it could be used as an aid in the detection of immature ganglion cells in rectal biopsies from children suspected of having Hirschsprung's disease. Routinely processed tissues of eight adult intestines resected for gunshot wounds and six ganglioneuromas (for mature ganglion cells), of six colons resected for neonatal necrotizing enterocolitis (for immature ganglion cells), and of 11 cases of suspected and three cases of known Hirschsprung's disease were immunostained with a polyclonal antibody to cathepsin D using the avidin-biotin-peroxidase method. In all cases, all ganglion cell bodies present showed intense granular cytoplasmic reactivity for cathepsin D. The granules crowded the cytoplasm and formed a collarette around the nucleus. In the submucosa, the only other immunoreactive cells were histiocytes, but they could be distinguished from ganglion cells by their characteristic nuclear features and their occurrence singly and unassociated with nerves. The three resection specimens with Hirschsprung's disease showed a clear transition between the ganglionic and the aganglionic segments. We conclude that cathepsin D is a promising marker of immature ganglion cells in cases suspected of Hirschsprung's disease.

Mucosal biopsy findings and venous abnormalities in idiopathic myointimal hyperplasia of the mesenteric veins

Idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV) is a rare cause of intestinal ischemia secondary to venous compromise. A patient with this condition who presented with crampy abdominal pain, diarrhea, and rectal bleeding initially attributed to inflammatory bowel disease had several colonoscopies and ultimately a sigmoid colectomy. The colonic mucosa in biopsies performed at initial presentation and subsequently and in the resection specimen contained numerous hyperplastic, thick-walled, hyalinized vessels in the lamina propria, which have not been described in this entity previously. Examination of the mucosa in 27 resection specimens of ischemic enterocolitis of various etiologies, in five resections of prolapsed rectum, and in seven colostomy specimens revealed no instance in which there were similar histologic abnormalities. When seen on biopsy, therefore, these features should lead to inclusion of IMHMV in the differential diagnosis. Furthermore, the characteristic lesions of the submucosal and extramural veins in IMHMV were compared with those of 14 examples, from several organs, of veins subjected to arterial pressure and 21 cases of venous hypertension. The marked similarity of the arterialized veins to the mural veins of IMHMV suggests a role for arteriovenous fistulization in the pathogenesis of IMHMV, and a mechanism by which this might occur is proposed.

Angiotensin-converting enzyme inhibitor therapy in chronic hemodialysis patients: any evidence of erythropoietin resistance?

Exacerbation of anemia associated with angiotensin-converting enzyme (ACE) inhibitor therapy has been noted to occur in patients with chronic renal failure, end-stage renal disease, and renal transplantation. Angiotensin-converting enzyme inhibitors appear to cause anemia through induction of decreased red blood cell production. There are data suggesting that ACE inhibitors may impair erythropoiesis via either suppression of angiotensin-mediated erythropoietin (EPO) production or bone marrow response to EPO. Patients on chronic hemodialysis receive recombinant human EPO (rHuEPO) for therapy of anemia and may also receive an ACE inhibitor for hypertension or congestive heart failure. We undertook a retrospective study to evaluate whether patients treated with ACE inhibitors developed a more severe anemia or required a higher dose of rHuEPO to maintain a similar hematocrit. Ninety-five of 108 chronic hemodialysis patients met study criteria (hemodialysis for 4 months and no treatment with an ACE inhibitor for at least 4 months = group 1; therapy with an ACE inhibitor for at least 4 months = group 2). Forty-eight patients (group 1, n = 24; group 2, n = 24) were available for analysis after exclusion for a variety of factors. There was no difference between the two groups in terms of baseline characteristics, number of blood transfusions or hospital days, or other laboratory parameters. There was no statistically significant difference in average hematocrit between group 1 (33.5% +/- 3.9%) and group 2 (32.6% +/- 1.6%). Similarly, no significant difference was observed for the average rHuEPO dose/treatment between group 1 (3,272 +/- 1,532 IU/treatment; 50.69 +/- 26.94 IU/kg/treatment) and group 2 (3,401 +/- 1,009 IU/treatment; 52.87 +/- 19.38 IU/kg/treatment). These results suggest that ACE inhibitors do not significantly induce more severe anemia or alter rHuEPO response in chronic hemodialysis patients.

An immunohistochemical study of thyroid Hurthle cells and their neoplasms: the roles of S-100 and HMB-45 proteins

The histological and cytological features of follicular thyroid neoplasms with oxyphilic change (Hurthle cell tumors) may lead to the differential diagnosis of metastatic malignant melanoma. S-100 and HMB-45 staining was studied in 18 Hurthle cell tumors, 6 Hurthle cell carcinomas, and 5 cases of Hashimoto's thyroiditis using a rabbit polyclonal antibody to S-100 protein, a mouse monoclonal antibody to HMB-45 protein, and the avidin alkaline phosphatase method. All 6 carcinomas and 17 of 18 Hurthle cell tumors exhibited strong cytoplasmic and nuclear staining for S-100. One Hurthle cell carcinoma also contained a spindle cell anaplastic area that was negative for S-100. All cases of Hashimoto's thyroiditis displayed intense staining in Hurthle cells for S-100, with weak to negative staining in nonoxyphilic follicular epithelium. In the three studied lesions, all cases were negative for HMB-45 protein. Three nonthyroid oncocytic tumors (renal oncocytoma, oncocytic carcinoma of the parotid, and parathyroid oxyphilic adenoma) were found to be negative for both S-100 and HMB-45 staining. Hurthle cell lesions should be included in the differential diagnosis of S-100-positive tumors. HMB-45 remains a marker more restricted to melanocytic lesions.