A concerted metabolic shift in early forebrain alters the CSF proteome and depends on MYC downregulation for mitochondrial maturation

Massive, coordinated cellular changes accompany the transition of central nervous system (CNS) progenitors from forebrain neurectodermal cells to specified neuroepithelial cells. We have previously found that MYC regulates the changing ribosomal and proteostatic landscapes in mouse forebrain precursors at embryonic days E8.5 and E10.5 (before and after neural tube closure; NTC) (Chau et al., 2018). Here, we demonstrate parallel coordinated transcriptional changes in metabolic machinery during this same stage of forebrain specification. Progenitors showed striking mitochondrial structural changes transitioning from glycolytic cristae at E8.5, to more traditional mitochondria at E10.5. Accordingly, glucose use shifted in progenitors such that E8.5 progenitors relied on glycolysis, and after NTC increasingly used oxidative phosphorylation. This metabolic shift was matched by changes in surrounding amniotic and cerebrospinal fluid proteomes. Importantly, these mitochondrial morphological shifts depend on MYC downregulation. Together, our findings demonstrate that metabolic shifting accompanies dynamic organelle and proteostatic remodeling of progenitor cells during the earliest stages of forebrain development.

Mice Expressing Myc in Neural Precursors Develop Choroid Plexus and Ciliary Body Tumors

Choroid plexus tumors and ciliary body medulloepithelioma are predominantly pediatric neoplasms. Progress in understanding the pathogenesis of these tumors has been hindered by their rarity and lack of models that faithfully recapitulate the disease. Here, we find that endogenous Myc proto-oncogene protein is down-regulated in the forebrain neuroepithelium, whose neural plate border domains give rise to the anterior choroid plexus and ciliary body. To uncover the consequences of persistent Myc expression, MYC expression was forced in multipotent neural precursors (nestin-Cre:Myc), which produced fully penetrant models of choroid plexus carcinoma and ciliary body medulloepithelioma. Nestin-mediated MYC expression in the epithelial cells of choroid plexus leads to the regionalized formation of choroid plexus carcinoma in the posterior domain of the lateral ventricle choroid plexus and the fourth ventricle choroid plexus that is accompanied by loss of multiple cilia, up-regulation of protein biosynthetic machinery, and hydrocephalus. Parallel MYC expression in the ciliary body leads also to up-regulation of protein biosynthetic machinery. Additionally, Myc expression in human choroid plexus tumors increases with aggressiveness of disease. Collectively, our findings expose a select vulnerability of the neuroepithelial lineage to postnatal tumorigenesis and provide a new mouse model for investigating the pathogenesis of these rare pediatric neoplasms.

Downregulation of ribosome biogenesis during early forebrain development

Forebrain precursor cells are dynamic during early brain development, yet the underlying molecular changes remain elusive. We observed major differences in transcriptional signatures of precursor cells from mouse forebrain at embryonic days E8.5 vs. E10.5 (before vs. after neural tube closure). Genes encoding protein biosynthetic machinery were strongly downregulated at E10.5. This was matched by decreases in ribosome biogenesis and protein synthesis, together with age-related changes in proteomic content of the adjacent fluids. Notably, c-MYC expression and mTOR pathway signaling were also decreased at E10.5, providing potential drivers for the effects on ribosome biogenesis and protein synthesis. Interference with c-MYC at E8.5 prematurely decreased ribosome biogenesis, while persistent c-MYC expression in cortical progenitors increased transcription of protein biosynthetic machinery and enhanced ribosome biogenesis, as well as enhanced progenitor proliferation leading to subsequent macrocephaly. These findings indicate large, coordinated changes in molecular machinery of forebrain precursors during early brain development.

Transcriptomic Characterization of SF3B1 Mutation Reveals Its Pleiotropic Effects in Chronic Lymphocytic Leukemia

Mutations in SF3B1, which encodes a spliceosome component, are associated with poor outcome in chronic lymphocytic leukemia (CLL), but how these contribute to CLL progression remains poorly understood. We undertook a transcriptomic characterization of primary human CLL cells to identify transcripts and pathways affected by SF3B1 mutation. Splicing alterations, identified in the analysis of bulk cells, were confirmed in single SF3B1-mutated CLL cells and also found in cell lines ectopically expressing mutant SF3B1. SF3B1 mutation was found to dysregulate multiple cellular functions including DNA damage response, telomere maintenance, and Notch signaling (mediated through KLF8 upregulation, increased TERC and TERT expression, or altered splicing of DVL2 transcript, respectively). SF3B1 mutation leads to diverse changes in CLL-related pathways.

Factors affecting the deceased organ donation rate in the Chinese community: an audit of hospital medical records in Hong Kong

INTRODUCTION

The number of actual donors per million population is the most commonly used metric to measure organ donation rates worldwide. It is deemed inadequate, however, because it does not take into account the potential donor pool. The aim of this study was to determine the true potential for solid organ donation from deceased brain-dead donors and the reasons for non-donation from potential donors in the Chinese community.

METHODS

Medical records of all hospital deaths between 1 January and 31 December 2014 at a large regional hospital in Hong Kong were reviewed. Those who were on mechanical ventilation with documented brain injury and aged ≤75 years were classified as possible organ donors. The reasons why some potential organ donors did not become utilised organ donors were recorded and evaluated.

RESULTS

Among 3659 patient deaths, 121 were classified as possible organ donors. The mean age of the possible organ donors was 59.4 years and 72.7% of them were male. The majority (88%) were from non-intensive care units. Of the 121 possible organ donors, 108 were classified as potential organ donors after excluding 13 unlikely to fulfil brain death criteria. Finally 11 patients became actual organ donors with an overall conversion rate of 10%. Reasons for non-donation included medical contra-indication (46%), failure to identify and inform organ donation coordinators (14%), failure of donor maintenance (11%), brain death diagnosis not established (18%), and refusal by relatives (11%).

CONCLUSIONS

It is possible to increase the organ donation rate considerably by action at different stages of the donation process. Ongoing accurate audit of current practice is necessary.

Progressive Differentiation and Instructive Capacities of Amniotic Fluid and Cerebrospinal Fluid Proteomes following Neural Tube Closure

After neural tube closure, amniotic fluid (AF) captured inside the neural tube forms the nascent cerebrospinal fluid (CSF). Neuroepithelial stem cells contact CSF-filled ventricles, proliferate, and differentiate to form the mammalian brain, while neurogenic placodes, which generate cranial sensory neurons, remain in contact with the AF. Using in vivo ultrasound imaging, we quantified the expansion of the embryonic ventricular-CSF space from its inception. We developed tools to obtain pure AF and nascent CSF, before and after neural tube closure, and to define how the AF and CSF proteomes diverge during mouse development. Using embryonic neural explants, we demonstrate that age-matched fluids promote Sox2-positive neurogenic identity in developing forebrain and olfactory epithelia. Nascent CSF also stimulates SOX2-positive self-renewal of forebrain progenitor cells, some of which is attributable to LIFR signaling. Our Resource should facilitate the investigation of fluid-tissue interactions during this highly vulnerable stage of early brain development.

Clozapine-induced acute interstitial nephritis

Acute interstitial nephritis is a common cause of acute kidney injury. Acute interstitial nephritis is most commonly induced by drug although the cause may also be infective, autoimmune, or idiopathic. Although eosinophilia and eosinophiluria may help identify this disease entity, the gold standard for diagnosis remains renal biopsy. Prompt diagnosis is important because discontinuation of the culprit drugs can reduce further kidney injury. We present a patient with an underlying psychiatric disorder who was subsequently diagnosed with clozapine-induced acute interstitial nephritis. Monitoring of renal function during clozapine therapy is recommended for early recognition of this rare side-effect.

Intrarenal abscess caused by community-associated methicillin-resistant Staphylococcus aureus in a transplanted kidney

Emergence of multidrug-resistant bacteria is important in solid organ transplant recipients, because it can jeopardize patient and graft survival. Methicillin-resistant Staphylococcus aureus (MRSA) infections are not rare in kidney transplant recipients. On the other hand, infections related to community-associated MRSA (CA-MRSA) strains are seldom reported in the literature. Herein, we report the first patient, to our knowledge, with CA-MRSA renal graft abscess who was successfully treated with drainage and parenteral antibiotics.

Vascular calcification in a young patient with end-stage renal disease

Vascular calcification in children with long-standing dialysis is a unique phenomenon. Hyperphosphataemia and hyperparathyroidism are the major pathogenic risk factors. We describe a young patient with end-stage renal disease diagnosed since childhood and underwent prolonged dialysis therapy. He was admitted for recurrent episodes of acute joint pain. Investigations confirmed diffuse periarticular, vascular, and intracardiac calcifications which were rarely seen in the young population. He underwent parathyroidectomy and incidentally found to have a co-existing papillary carcinoma of thyroid. After parathyroidectomy, serial X-rays showed resorption of these calcifications.

Malignancies after kidney transplantation: Hong Kong renal registry

Manystudies have shown that kidney transplant recipients have a higher incidence of cancers when compared with general population. However, most data on the posttransplant malignancies (PTM) are derived from Western literature and large population-based studies are rare. There is also lack of information about the posttransplant cancer-specific mortality rate. We conducted a population-based study of 4895 kidney transplants between 1972 and 2011, with data from the Hong Kong Renal Registry. Patterns of cancer incidence and mortality in our kidney transplant recipients were compared with those of the general population using standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) respectively. With 40 246 person-years of follow-up, 299 PTM was diagnosed. The SIR of all cancers was 2.94 (female 3.58 and male 2.58). Non-Hodgkin lymphoma (NHL), kidney, and bladder cancers had the highest SIRs. The overall SMR was 2.3 (female 3.4 and male 1.7) and the highest SMR was NHL. The patterns of PTM differ among countries. Increases in cancer incidence can now translate into similar increases in cancer mortality. NHL is important in our kidney transplant recipients. Strategies in cancer screening in selected patient groups are needed to improve transplant outcomes.

Impact of delayed graft function on renal function and graft survival in deceased kidney transplantation

OBJECTIVES

To define the risk factors for delayed graft function and study the impact of such delays on renal function and long-term allograft survival in renal transplant recipients.

DESIGN

Single-centre retrospective study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

Records of 118 Chinese renal transplant recipients from 1 July 1997 to 31 July 2005 were reviewed, and categorised into delayed and immediate graft function groups.

RESULTS

Delayed graft function was observed in about 19% of patients, for which cold ischaemic time was an important independent predictor. For each additional hour of cold ischaemic time, the odds ratio increased for delayed function by 0.002 (95% confidence interval, 0.001-0.003; P=0.03). Multivariate analysis revealed that neither cold ischaemic time nor delayed graft function was associated with acute rejection. On the other hand, at 1 year both delayed graft function (odds ratio=18.5; 95% confidence interval, 2.6-130.5; P=0.003) and donor age (1.2; 1.1-1.3; P=0.003) were related to a glomerular filtration rate of less than 30 mL/min. When renal function between patients with and without delayed graft function during the first 3 years was compared, it was significantly better in those without delayed graft function. However, there was no significant difference in death-censored graft survival between delayed graft function and immediate graft function groups.

CONCLUSIONS

Delayed graft function has a significant adverse effect on graft function at 1 year. Limiting cold ischaemic time is important as it is an independent predictor of delayed graft function.

A rare cause of nephrotic syndrome: lipoprotein glomerulopathy

Lipoprotein glomerulopathy is a rare kidney disease in which lipoprotein thrombi are seen in the glomerular capillaries. Most of these patients are found in Japan and East Asian countries. The presenting symptoms include proteinuria, an abnormal plasma lipoprotein profile that resembles type III hyperlipoproteinaemia, and a marked increase in serum apolipoprotein E concentration. Previous studies have suggested that lipoprotein glomerulopathy might be related to APOE gene mutation. No effective therapeutic regimen has been established for lipoprotein glomerulopathy. We report the first case of biopsy-proven lipoprotein glomerulopathy in Hong Kong in a patient who presented with nephrotic syndrome and dyslipidaemia. DNA analysis revealed apolipoprotein E Kyoto together with a novel apolipoprotein E mutation, apolipoprotein E (Asp230Tyr) Hong Kong. There was significant improvement in the clinical parameters and resolution of symptoms after the introduction of statins. Further studies will be needed to clarify the role of apolipoprotein E Hong Kong and its interaction with apolipoprotein E Kyoto in the pathogenesis of lipoprotein glomerulopathy.

Prevalence of metabolic syndrome in Chinese renal transplant recipients

OBJECTIVE

To investigate the prevalence of metabolic syndrome in Chinese renal transplant recipients, using two different sets of diagnostic criteria.

DESIGN

Cross-sectional study.

SETTING

Regional hospital, Hong Kong.

PATIENTS

All Chinese patients who received solitary living-related or cadaveric kidney transplantation from 1 July 1997 to 31 December 2005 in our hospital with follow-up of more than 6 months were recruited. The diagnosis of metabolic syndrome was made according to the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII) criteria and the International Diabetes Federation criteria.

RESULTS

Using the modified (Asian) NCEP-ATPIII criteria, a total of 39 (32%) of 121 patients had metabolic syndrome, which included 20/69 (29%) of the males and 19/52 (37%) of the females. Using the International Diabetes Federation criteria, metabolic syndrome was diagnosed in 26% of the patients, 22% in males and 31% in females. In our patients, the most common component of metabolic syndrome was hypertension and the least common was low high-density-lipoprotein-cholesterol level. Low high-density-lipoprotein-cholesterol levels were significantly more common in female patients.

CONCLUSION

This study shows that there is a high prevalence of metabolic syndrome in our Chinese renal transplant recipients.

Corticosteroid therapy in a Chinese patient with nephropathy associated with human immunodeficiency virus infection

A 52-year-old man with 6 years' history of human immunodeficiency virus infection who was receiving highly active antiretroviral therapy presented with acute renal failure and nephrotic syndrome. Renal biopsy revealed features consistent with nephropathy associated with human immunodeficiency virus infection. Treatment consisted of intravenous methylprednisolone followed by oral prednisolone. The patient's renal function improved, although proteinuria persisted. Human immunodeficiency virus-associated nephropathy is very rare in Asian populations and is more common among blacks. To the best of our knowledge, this is the first documented case of nephropathy associated with human immunodeficiency virus infection occurring in Hong Kong.

Prevention of recurrent central venous stenosis using endovascular irradiation following stent placement in hemodialysis patients

This study was done to evaluate the outcome after brachytherapy (BT) given to prevent restenosis after stent insertion for central venous stenosis in patients with ipsilateral hemodialysis arteriovenous fistulas (AVF). Angioplasty and stenting were performed on 9 primary central venous stenoses in 8 patients with AVF followed by BT, delivering Iridium-192 radiation using an afterloading technique. BT was also administered to three patients with five recurrent stenoses at the stent margins. There was no residual stenosis after angioplasty and stenting. Venographic follow-up (77-644 days, mean 272 days) showed no restenosis in seven primary stenoses. New strictures (45%-100%) developed at the stent margin in six veins (five patients). Angioplasty or stenting was performed for five margin stenoses in three patients, followed by a second BT. Residual stenosis before BT was 0-30%. In our venographic follow-up (140-329 days, mean 215 days), three restenoses occurred (35%-100%). All progressed to complete occlusion on later venographic follow-up irrespective of whether BT was given to the stent margin or not. The mean primary and assisted primary patency of the central veins were 359 days and 639 days, respectively. Endovascular irradiation with a noncentering source does not prolong the patency after angioplasty and stenting of central venous stenosis in hemodialysis patients.

Hypokalemic metabolic acidosis attributed to cough mixture abuse

This report describes a patient with mixed normal anion gap hyperchloremic metabolic and respiratory acidosis associated with hypokalemia attributed to cough mixture abuse. Metabolic acidosis was likely related to an overdose of ammonium chloride, whereas respiratory acidosis was probably related to the effect of hypokalemia on respiratory muscles, causing hypoventilation. Hypokalemia was caused by a transcellular shift of potassium induced by ephedrine and pseudoephedrine. Both ammonium chloride and ephedrine were probably present in the cough mixture obtained by our patient as an over-the-counter medication. Physicians should be aware of the potential for cough mixture abuse to cause major electrolyte disturbances that may carry the risk for major cardiac arrhythmias, particularly in youth.

Cefepime versus vancomycin plus netilmicin therapy for continuous ambulatory peritoneal dialysis-associated peritonitis

Cefepime is a cephalosporin with a broad spectrum of activity against most gram-positive and gram-negative pathogens. In this study, we attempted to compare the safety and efficacy of cefepime monotherapy against the potentially more toxic combination of vancomycin and netilmicin in the treatment of continuous ambulatory peritoneal dialysis (CAPD)-associated bacterial peritonitis. Eighty-one consecutive CAPD patients who presented with peritonitis from January 1, 1998, to June 30, 2000, were recruited for study. Patients were randomized to be administered either intraperitoneal (IP) cefepime, 1 g once daily (group A), or intravenous vancomycin and netilmicin at conventional doses (group B) for 10 days. Bacterial growth was obtained in 52 episodes (66%), and pathogens identified included gram-positive organisms (30 episodes; 38%), gram-negative organisms (14 episodes; 18%), mixed organisms (2 episodes; 2.5%), and fungus (6 episodes; 8%). Eight patients were excluded after randomization for various reasons (6 patients, fungal peritonitis; 2 patients, wrong diagnoses). Because of the relatively low peritonitis rate after the use of a disconnect system, the sample size of this study was relatively small, giving a power of 0.45. There were no significant differences in primary response rates and cure rates (no relapse >28 days after completion of antibiotic therapy) between both groups of patients (group A versus group B, 82% [32 of 39 patients] versus 85% [29 of 34 patients] and 72% [28 of 39 patients] versus 76% [26 of 34 patients], respectively; P = not significant). No significant side effect was encountered in either group. Total peritonitis-related hospitalizations were 84 patient-days (1, 7, 8, 11, 20, and 37 patient-days) and 115 patient-days (3, 6, 9, 14, 21, 21, and 41 patient-days), whereas total costs per patient cure were estimated to be US $1,039 and US $1,371 in groups A and B, respectively. We conclude that once-daily 1-g IP cefepime monotherapy is a simple, safe, and cost-effective alternative to vancomycin and netilmicin therapy in the treatment of CAPD-associated bacterial peritonitis.

Urea reduction ratio that considers effects of ultrafiltration and intradialytic urea generation

We modified the urea reduction ratio (URR) equation to correct the effects of ultrafiltration and intradialytic urea generation on the delivered dose of hemodialysis: mURR = [1 - (R/1 + 2*UF/BW) + 0.01*t] x 100% where mURR is modified URR, R is postdialysis plasma urea nitrogen (PUN) to predialysis PUN ratio, UF is ultrafiltrate volume in liters, BW is postdialysis body weight in kilograms, and t is dialysis session length in hours. The equation was validated against 145 hemodialysis treatments on 33 stable maintenance dialysis patients. The mURR values obtained closely predicted single-pool Kt/V (spKt/V) values. In contrast to conventional URR, the range of spKt/V values at each mURR value is narrow over a wide range of UF, t, and R values. Based on the mURR equation, mURR values of 64%, 70%, and 76% are mathematically equivalent to spKt/V levels of 1.0, 1.2, and 1.4, respectively. This equation can be a useful bedside tool to quantify hemodialysis dose.

Cytomegalovirus-induced tubulointerstitial nephritis in a renal allograft treated by foscarnet therapy

We report a female patient suffering from cytomegalovirus (CMV)-induced tubulointerstitial nephritis in a renal allograft 70 days after a cadaveric renal transplantation. CMV-induced renal allograft injury reported in the literature mainly related to immune-mediated mechanisms. In our patient, acute tubulointerstitial nephritis, associated with histological evidence of CMV infection, was demonstrated in the renal allograft biopsy. There were no histological features of allograft rejection, cyclosporin nephrotoxicity nor 'CMV glomerulopathy'. She was successfully treated by foscarnet therapy and a reduction in immunosuppression. Her renal function returned to baseline afterwards.

Abbreviated tacrolimus area-under-the-curve monitoring for renal transplant recipients

The area under the concentration time curve (AUC) for oral tacrolimus (FK) may provide a more precise model for FK monitoring after renal transplantation. The purpose of this study is to identify a simple, cost-effective method for predicting FK AUC. FK concentrations were measured at 0, 1, 2, 4, 6, 8, and 12 hours after the morning dose. The predicted AUCs (AUC(p)s) derived from regression equations were used to estimate the actual 12-hour AUCs (AUC(12)s). The relationship between AUC(p) and AUC(12) was validated by determining the coefficient of multiple determination (R(2)), percentage of prediction error (PE%), and percentage of absolute prediction error (APE%). Eighteen stable Oriental renal transplant recipients (9 men, 9 women) with a mean age of 42.6 +/- 6 years and mean body weight of 62.7 +/- 10 kg were recruited for the study. The FK AUC(12), trough, 2-hour, and 4-hour concentrations were 125 +/- 24 h. ng/mL (range, 87.7 to 181.9 h. ng/mL), 6 +/- 1.3 ng/mL, 18.1 +/- 4.7 ng/mL, and 11 +/- 2.4 ng/mL, respectively. Trough FK concentration did not have a significant correlation with AUC(12) (r = 0.34; P = 0.17). AUC(p) obtained by a two-time point regression equation using 2-hour (C2) and 4-hour (C4) FK concentrations: (AUC(P) = 16.2 + 2.4*C2 + 5.9*C4) obtained an R(2), PE%, and APE% of 0.93, -0.2% +/- 5.2% (range, -13% to 9.3%), and 3. 6% +/- 3.7% (range, 0.02% to 13%), respectively. We conclude that a two-point sampling method using C2 and C4 may be a more cost-effective FK monitoring strategy than morning FK trough levels in transplant recipients.

Subcutaneous nodules attributed to nocardiosis in a renal transplant recipient on tacrolimus therapy

We report a renal transplant patient who suffered from disseminated nocardiosis after empirical tacrolimus rescue therapy for chronic allograft rejection. The nocardiosis presented initially as only mildly tender subcutaneous calf nodules without any other signs of inflammation nor constitutional upset, which later spread to the lung and brain causing bronchopneumonia and brain abscesses. The risk factors for nocardial infection in our patient include the use of potent immunosuppressive agents such as tacrolimus, poorly controlled diabetes mellitus and kidney dysfunction. She responded well to combination antibiotic therapy comprising parenteral meropenem, cefotaxime and oral minocycline. We conclude that in transplant recipients, especially those receiving newer and more potent immunosuppressive agents like tacrolimus, nocardial infection can present as apparently 'cold' subcutaneous nodules without any systemic upset. An associated brain lesion should be excluded even in patients without neurological symptoms.

Comparison of double-bag and Y-set disconnect systems in continuous ambulatory peritoneal dialysis: a randomized prospective multicenter study

We performed a multicenter, single-blinded, prospective randomized study on the use of a double-bag disconnect system (B) versus a Y-set disconnect system (Y). The peritonitis rate, exit site infection, clinical outcome, and patients' acceptance to the procedure were assessed. A total of 120 new end-stage renal failure patients of three regional hospitals were randomized: 60 each to the B and the Y systems. The results of 60 patients on the B system and 51 on the Y system were analyzable. They were followed up for a median of 16 months. Peritonitis rates for the B and the Y systems were 33.5 and 29.4 patient-months per episode, respectively. Exit site infection rates for the B and Y systems were 17.4 and 16.0 patient-months per episode, respectively. Four catheters were removed in each group. Patients on the B system were hospitalized for 2.1 days per patient per year related to peritonitis and exit site infection, and those on the Y system were hospitalized for 1.2 days. There was no significant difference between the B and Y systems in the incidences of peritonitis (all causes and those due to coagulase-negative staphylococci), exit site infection, and in hospitalization days. However, there was a higher percentage of gram-positive infections in the Y system (52%) than in the B system (32%) and a lower percentage of gram-negative infections in the Y system (16%) than in the B system (32%). Patients on the B system had a better acceptance of the procedure than patients on the Y system, as assessed by a six-item, 10-point questionnaire (total score, 43.1 +/- 10.2 v 37.6 +/- 9.4; P < 0.005 at 1 month; 44.6 +/- 9.1 v 39.8 +/- 8.6; P < 0.01 at 6 months). From this study, it is concluded that the B and Y systems are similar in the incidences of peritonitis and exit site infection, although the B system is better accepted by patients. This is probably the first multicenter randomized study comparing the double-bag and Y-set disconnect system using only new patients who had never used other systems of continuous ambulatory peritoneal dialysis.

Determination of the solute removal index for urea by using a partial spent dialysate collection method

In 22 hemodialysis patients, during a dialysis session, the solute removal index (SRI) for urea obtained from the use of a partial spent dialysate collection method was compared with that derived from the use of a total spent dialysate collection technique. The partial spent dialysate collection method was used to harvest a small representative sample of the total spent dialysate. The volumes of spent dialysate collected by the partial and the total spent dialysate collection methods were 1.7 +/- 0.4 L and 129.6 +/- 15.3 L, respectively. The total amount of urea nitrogen removed by dialysis as estimated by the partial spent dialysate collection method was similar to that determined by the total spent dialysate collection approach. As a result, the SRI value for urea obtained by the partial spent dialysate collection method (namely, 63% +/- 8%) correlated very well (r = 0.95, P < 0.001) with that derived by the total spent dialysate collection technique (namely, 62% +/- 8%). Our data suggest that it is feasible to use a simple partial spent dialysate collection method to obtain SRI results in patients treated with hemodialysis.

A partial dialysate collection method

This study validates Ing's partial dialysate collection method, which employs proportionate collection using a side tube capped with a small-gauge plastic needle. The urea nitrogen and creatinine levels of the small representative fraction of spent dialysate collected in the above fashion are undistinguishable from those obtained from the total spent dialysate. The estimated urea nitrogen removed during hemodialysis using this approach is similar to that using the total dialysate collection method; Ing's method is simple and useful in quantifying the dialysis dosage and in its assessment of the nutritional status of patients on hemodialysis.

Pure red cell aplasia associated with thymic lymphoid hyperplasia and secondary erythropoietin resistance

Systemic disorders, often immune in nature, can sometimes be associated with the presence of thymic pathology. Thymic enlargement due to lymphoid hyperplasia or thymoma is a common occurrence in patients with myasthenia gravis. In patients with pure red cell aplasia, at least 10% to 15% of patients are found to have thymoma, usually of spindle cell or medullary type. Pure red cell aplasia with demonstrable thymic enlargement due to lymphoid follicular hyperplasia is distinctly unusual, and has not been previously reported. The authors report such a case developing in a patient with end-stage renal failure maintained on hemodialysis and erythropoietin therapy. Because the red cell aplasia resolved after thymectomy, the disease process was considered etiologically related to the reactive lymphoid hyperplasia.

Antilactoferrin antibody in systemic lupus erythematosus

Lactoferrin is a secondary granule protein of neutrophils. Seventy-nine systemic lupus erythematosus patients who fulfilled the ARA criteria for classification were tested for antibody against human lactoferrin (LF-ab) by ELISA. Thirty-one of these (39.2%) demonstrated elevated levels. There was significant correlation between LF-ab positivity and disease duration. Clinical flare was common with positive LF-ab (P less than 0.05). Disease manifestations were independent of antibody status except for an increased incidence of lymphadenopathy and crescentic gomerulonephritis among those who had LF-ab. No consistent immunofluorescence pattern could be demonstrated on alcohol-fixed neutrophils for the LF-ab positive sera. It is suggested that LF-ab is related to lupus activity, and can be useful as a marker for disease monitoring.