Haemodialysis Access: A Single Centre UK Experience

Background

The aim of this study was to determine whether the US National Kidney Foundation Disease Outcome Quality Initiative (K/DOQI) guidelines on haemodialysis access could be achieved and to examine its relevance to patients on dialysis in the UK.

Method

A cross sectional study of chronic haemodialysis patients at our institution which involved case note review and measurements of biochemical parameters and dynamic venous pressure (dVP) was performed. Patients with polytetrafluoroethylene (PTFE) grafts were followed prospectively for 18 months.

Results

262 patients were studied - 12%, 43%, 30% and 15% underwent dialysis through dialysis catheters, radial-cephalic fistulae (rAVF), brachial-cephalic fistulae (bAVF) and PTFE grafts respectively. RAVFs, bAVFs and PTFE grafts were the primary access (i.e. the first access created for the patient) in 58%, 35% and 7% respectively. Compared with patients of Caucasian origin, patients of Afro-Caribbean race were 3.80 times (95% confidence limit: 1.51 – 9.53) more likely to have a PTFE graft. Patients with higher “dry weights” were more likely to have PTFE grafts (p<0.005 by ANOVA). Dialysis adequacy was similar irrespective of type and site of access. We found that 64% of PTFE grafts, 46% of bAVFs and 13% of rAVF had dVPs greater than 150 mmHg, (p<0.0001 by χ2). This threshold recommended by DOQI predicted 12 of 13 dysfunctional grafts, but had a positive predictive value of only 50%.

Conclusion

We have demonstrated that the K/DOQI guidelines are not only achievable, but that they can be exceeded by a considerable margin. Our data also suggest that the demographic details of patients within a unit will influence the achievable proportion of AVF: PTFE grafts (the proportion of PTFE grafts in Afro-Caribbeans being 3 times higher than in Whites). Although a dVP >150 mmHg proved sensitive in predicting future graft dysfunction, it had low specificity.

AZA-MS: a novel multiparameter mass spectrometry method to determine the intracellular dynamics of azacitidine therapy in vivo

The cytidine analogue, 5-azacytidine (AZA; 5-AZA-cR), is the primary treatment for myelodysplastic syndrome and chronic myelomonocytic leukaemia. However, only ~50% of treated patients will respond to AZA and the drivers of AZA resistance in vivo are poorly understood. To better understand the intracellular dynamics of AZA upon therapy and decipher the molecular basis for AZA resistance, we have developed a novel, multiparameter, quantitative mass spectrometry method (AZA-MS). Using AZA-MS, we have accurately quantified the abundance of the ribonucleoside (5-AZA-cR) and deoxyribonucleoside (5-AZA-CdR) forms of AZA in RNA, DNA and the cytoplasm within the same sample using nanogram quantities of input material. We report that although AZA induces DNA demethylation in a dose-dependent manner, it has no corresponding effect on RNA methylation. By applying AZA-MS to primary bone marrow samples from patients undergoing AZA therapy, we have identified that responders accumulate more 5-AZA-CdR in their DNA compared with nonresponders. AZA resistance was not a result of impaired AZA metabolism or intracellular accumulation. Furthermore, AZA-MS has helped to uncover different modes of AZA resistance. Whereas some nonresponders fail to incorporate sufficient 5-AZA-CdR into DNA, others incorporate 5-AZA-CdR and effect DNA demethylation like AZA responders, but show no clinical benefit.

Morphological and proteomic analysis of biofilms from the Antarctic archaeon, Halorubrum lacusprofundi

Biofilms enhance rates of gene exchange, access to specific nutrients, and cell survivability. Haloarchaea in Deep Lake, Antarctica, are characterized by high rates of intergenera gene exchange, metabolic specialization that promotes niche adaptation, and are exposed to high levels of UV-irradiation in summer. Halorubrum lacusprofundi from Deep Lake has previously been reported to form biofilms. Here we defined growth conditions that promoted the formation of biofilms and used microscopy and enzymatic digestion of extracellular material to characterize biofilm structures. Extracellular DNA was found to be critical to biofilms, with cell surface proteins and quorum sensing also implicated in biofilm formation. Quantitative proteomics was used to define pathways and cellular processes involved in forming biofilms; these included enhanced purine synthesis and specific cell surface proteins involved in DNA metabolism; post-translational modification of cell surface proteins; specific pathways of carbon metabolism involving acetyl-CoA; and specific responses to oxidative stress. The study provides a new level of understanding about the molecular mechanisms involved in biofilm formation of this important member of the Deep Lake community.

Aptamer based peptide enrichment for quantitative analysis of gonadotropin-releasing hormone by LC-MS/MS

Over recent years threats to racing have expanded to include naturally occurring biological molecules, such as peptides and proteins, and their synthetic analogues. Traditionally, antibodies have been used to enable detection of these compounds as they allow purification and concentration of the analyte of interest. The rapid expansion of peptide-based therapeutics necessitates a similarly rapid development of suitable antibodies or other means of enrichment. Potential alternative enrichment strategies include the use of aptamers, which offer the significant advantage of chemical synthesis once the nucleic acid sequence is known. A method was developed for the enrichment, detection and quantitation of gonadotropin-releasing hormone (GnRH) in equine urine using aptamer-based enrichment and LC-MS/MS. The method achieved comparable limits of detection (1 pg/mL) and quantification (2.5 pg/mL) to previously published antibody-based enrichment methods. The intra- and inter-assay precision achieved was less than 10% at both 5 and 20 pg/mL, and displayed a working dynamic range of 2.5-100 pg/mL. Significant matrix enhancement (170 ± 8%) and low analytical recovery (29 ± 15%) was observed, although the use of an isotopically heavy labelled GnRH peptide, GnRH (Pro(13)C5,(15)N), as the internal standard provides compensation for these parameters. Within the current limits of detection GnRH was detectable up to 1h post administration in urine and identification of a urinary catabolite extended this detection window to 4h. Based on the results of this preliminary investigation we propose the use of aptamers as a viable alternative to antibodies in the enrichment of peptide targets from equine urine.

Quantitative proteomics of delirium cerebrospinal fluid

Delirium is a common cause and complication of hospitalization in older people, being associated with higher risk of future dementia and progression of existing dementia. However relatively little data are available on which biochemical pathways are dysregulated in the brain during delirium episodes, whether there are protein expression changes common among delirium subjects and whether there are any changes which correlate with the severity of delirium. We now present the first proteomic analysis of delirium cerebrospinal fluid (CSF), and one of few studies exploring protein expression changes in delirium. More than 270 proteins were identified in two delirium cohorts, 16 of which were dysregulated in at least 8 of 17 delirium subjects compared with a mild Alzheimer's disease neurological control group, and 31 proteins were significantly correlated with cognitive scores (mini-mental state exam and acute physiology and chronic health evaluation III). Bioinformatics analyses revealed expression changes in several protein family groups, including apolipoproteins, secretogranins/chromogranins, clotting/fibrinolysis factors, serine protease inhibitors and acute-phase response elements. These data not only provide confirmatory evidence that the inflammatory response is a component of delirium, but also reveal dysregulation of protein expression in a number of novel and unexpected clusters of proteins, in particular the granins. Another surprising outcome of this work is the level of similarity of CSF protein profiles in delirium patients, given the diversity of causes of this syndrome. These data provide additional elements for consideration in the pathophysiology of delirium as well as potential biomarker candidates for delirium diagnosis.

Time-dependent effects of Prkce deletion on glucose homeostasis and hepatic lipid metabolism on dietary lipid oversupply in mice

AIMS/HYPOTHESIS

We examined the time-dependent effects of deletion of the gene encoding protein kinase C epsilon (Prkce) on glucose homeostasis, insulin secretion and hepatic lipid metabolism in fat-fed mice.

METHODS

Prkce(-/-) and wild-type (WT) mice were fed a high-fat diet for 1 to 16 weeks and subjected to i.p. glucose tolerance tests (ipGTT) and indirect calorimetry. We also investigated gene expression and protein levels by RT-PCR, quantitative protein profiling (isobaric tag for relative and absolute quantification; iTRAQ) and immunoblotting. Lipid levels, mitochondrial oxidative capacity and lipid metabolism were assessed in liver and primary hepatocytes.

RESULTS

While fat-fed WT mice became glucose intolerant after 1 week, Prkce(-/-) mice exhibited normal glucose and insulin levels. iTRAQ suggested differences in lipid metabolism and oxidative phosphorylation between fat-fed WT and Prkce(-/-) animals. Liver triacylglycerols were increased in fat-fed Prkce(-/-) mice, resulting from altered lipid partitioning which promoted esterification of fatty acids in hepatocytes. In WT mice, fat feeding elevated oxygen consumption in vivo and in isolated liver mitochondria, but these increases were not seen in Prkce(-/-) mice. Prkce(-/-) hepatocytes also exhibited reduced production of reactive oxygen species (ROS) in the presence of palmitate. After 16 weeks of fat feeding, however, the improved glucose tolerance in fat-fed Prkce(-/-) mice was instead associated with increased insulin secretion during ipGTT, as we have previously reported.

CONCLUSIONS/INTERPRETATION

Prkce deletion ameliorates diet-induced glucose intolerance via two temporally distinct phenotypes. Protection against insulin resistance is associated with changes in hepatic lipid partitioning, which may reduce the acute inhibitory effects of fatty acid catabolism, such as ROS generation. In the longer term, enhancement of glucose-stimulated insulin secretion prevails.

Proteomic assessment of host-associated microevolution in the fungus Thielaviopsis basicola

Thielaviopsis basicola, a soil-borne pathogen with a broad host range and a cosmopolitan distribution, is emerging as a major risk to sustainable cotton production in Australia. Previous studies suggested that host specialization has occurred making T. basicola an ideal model for a comparative proteomic analysis of strains isolated from different hosts. Elucidation of the genomic diversity and investigation of the functional differences in the Australian population could provide valuable information towards disease control. In this study, isolates of T. basicola were investigated for genomic (internal transcribed spacers region), proteomic and cotton virulence level variations. Internal transcribed spacers sequence analysis revealed that isolates are grouped based on host of origin irrespective of geographical origin. At the proteome level a degree of diversity was apparent and hierarchical clustering analysis of the data also demonstrated a close correlation between the proteome and the host of origin. LC-MS/MS analysis and identification using cross-species similarity searching and de novo sequencing of host-specific differentially expressed proteins and the virulence-correlated proteome allowed successful identification of 43 spots. The majority were found to be involved in metabolism. Spots that were correlated with host and virulence differences included a hypothetical protein with a Rossman-fold NAD(P)(+)-binding protein domain, glyceraldehyde-3-phosphate dehydrogenase, arginase and tetrahydroxynaphthalene reductase.

Redox control of β2-glycoprotein I-von Willebrand factor interaction by thioredoxin-1

BACKGROUND

 β(2) -Glycoprotein I (β(2) GPI) is an abundant plasma protein that is closely linked to blood clotting, as it interacts with various protein and cellular components of the coagulation system. However, the role of β(2) GPI in thrombus formation is unknown. We have recently shown that β(2) GPI is susceptible to reduction by the thiol oxidoreductases thioredoxin-1 and protein disulfide isomerase, and that reduction of β(2) GPI can take place on the platelet surface.

METHODS

 β(2) GPI, reduced by thioredoxin-1, was labeled with the selective sulfhydryl probe N(a)-(3-maleimidylpropionyl)biocytin and subjected to mass spectrometry to identify the specific cysteines involved in the thiol exchange reaction. Binding assays were used to examine the affinity of reduced β(2) GPI for von Willebrand factor (VWF) and the effect of reduced β2GPI on glycoprotein (GP)Ibα binding to VWF. Platelet adhesion to ristocetin-activated VWF was studied in the presence of reduced β(2) GPI.

RESULTS

We demonstrate that the Cys288-Cys326 disulfide in domain V of β(2) GPI is the predominant disulfide reduced by thioredoxin-1. Reduced β(2) GPI in vitro displays increased binding to VWF that is dependent on disulfide bond formation. β(2) GPI reduced by thioredoxin-1, in comparison with non-reduced β(2) GPI, leads to increased binding of GPIbα to VWF and increased platelet adhesion to activated VWF.

CONCLUSIONS

Given the importance of thiol oxidoreductases in thrombus formation, we provide preliminary evidence that the thiol-dependent interaction of β(2) GPI with VWF may contribute to the redox regulation of platelet adhesion.

Belatacept as maintenance immunosuppression for postrenal transplant de novo drug-induced thrombotic microangiopathy

De novo posttransplant thrombotic microangiopathy (TMA) is a complication of solid organ transplantation, which remains difficult to treat. In many cases, immunosuppressants and particularly calcineurin inhibitors, trigger TMA. Although withdrawing the offending drug may lead to resolution of TMA, graft and patient outcomes are poor. Specific treatments, including plasma exchange, have not gained widespread acceptance in those with fulminant disease and new approaches to the condition are urgently needed. We report a case of posttransplant de novo TMA presenting serially in association with ciclosporin, tacrolimus and sirolimus in a young recipient of a living donor kidney transplant. We describe a patient treated with belatacept, a novel CTLA4 Ig fusion protein, as ongoing maintenance immunosuppression to allow avoidance of conventional agents once associated with TMA. We report excellent early graft outcome, with no adverse events using this strategy. We suggest that belatacept may have a role in this traditionally difficult-to-treat group of patients.

Randomized controlled study of biocompatible peritoneal dialysis solutions: effect on residual renal function

Residual kidney function is important for patient and technique survival in peritoneal dialysis (PD). Biocompatible dialysis solutions are thought to improve function and viability of peritoneal mesothelial cells and to preserve residual renal function (RRF). We conducted a randomized controlled study comparing use of biocompatible (B) with standard (S) solutions in 93 incident PD patients during a 1-year period. The demographics, comorbidities, and RRF of both groups were similar. At 3 and 12 months, 24-h urine samples were collected to measure volume and the mean of urea and creatinine clearance normalized to body surface area. Surrogate markers of fluid status, diuretic usage, C-reactive protein concentration, peritonitis episodes, survival data, and peritoneal equilibrium tests were also collected. Changes in the normalized mean urea and creatinine clearance were the same for both groups, with no significant differences in secondary end points. Despite non-randomized studies suggesting benefits of these newer biocompatible solutions, we could not detect any clinically significant advantages. Additional studies are needed to determine if advantages are seen with longer term use.

Antigen-epitope retrieval to facilitate proteomic analysis of formalin-fixed archival brain tissue

Formalin is a routine fixative facilitating tissue preservation and histopathology. Proteomic techniques require freshly frozen specimens, which are often difficult to procure, and methods facilitating proteomic analysis of archival formalin-fixed brain tissue are lacking. We employed antigen-epitope-retrieval principles to facilitate proteomic analysis of brain tissue that had been fixed and stored in formalin for 3-7 years. Twenty-micrometer-thick cryopreserved OCT-embedded sections from inferior temporal cortex of human (7 years in formalin) or mouse brain specimens (3 years in formalin) were hematoxylin-/eosin-stained. Approximately 16-64-mm2 areas of the tissue sections were manually scraped off slides, or approximately 2 mm2 of human brain cortex was captured off membrane-coated slides using laser microdissection. Tissue was treated using various pH and temperature conditions prior to trypsin digestion and nano-LC-MS/MS. The largest number of proteins were retrieved by solubilization at pH 9 at 95 degrees C for 1 h; treatments at pH 4 or 6 at 25 or 65 degrees C were generally ineffective. Three-year formalin-fixed murine tissue did not yield more proteins compared to human tissue. Use of formalin-fixed tissue for proteomics is an invaluable tool for medical research. The combination of proteomics and microdissection enables selective enrichment and identification of novel, unique, or abundant proteins that may be important in pathogenesis.

High glucose initiates calpain-induced necrosis before apoptosis in LLC-PK1 cells

Cells exposed to high ambient glucose concentrations are subject to increases in intracellular calcium ([Ca(2+)](i)). We therefore considered it likely that the calcium-dependent cysteine protease calpain would play a role in the development of high glucose-induced cell injury. After 3 and 24 h, high glucose concentrations (25 mM D-glucose) produced almost identical increases in the degree of necrotic cell death in kidney proximal tubular epithelial cells (LLC-PK(1)) compared to cells treated with control glucose (5 mM D-glucose). Necrotic cell death could be restricted by inhibiting the activity of calpain. High glucose-treated LLC-PK(1) cells were found to have significantly elevated [Ca(2+)](i) concentrations within 1 h, and elevated calpain activity within 2 h compared to control treated cells. The DNA nick sensor poly(ADP-ribose) polymerase (PARP) has previously been shown to be an important driver of high glucose-induced cell death, but here we found that although PARP activity was increased after 24 h, it was unaltered after 3 h. Furthermore, PARP inhibition with PJ-34 did not restrict early high glucose-induced necrosis. Using a gene knockdown strategy with small interference RNA, we found that silencing calpain was effective in reducing the degree of early high glucose-induced necrosis. We conclude that high glucose concentrations evoke an early, calpain-mediated necrosis in cultured proximal tubular cells that is PARP-independent, and precedes the previously recognized activation of apoptosis.

Sarcoid tubulo-interstitial nephritis: Long-term outcome and response to corticosteroid therapy

Sarcoidosis is a chronic relapsing multi-systemic disorder characterized by the development of non-caseating granulomas. Granulomatous tubulo-interstitial nephritis is an uncommon manifestation of this condition. We identified 39 patients with sarcoidosis and renal disease from a single center of whom 17 patients had biopsy-proven tubulo-interstitial nephritis. They were analyzed with respect to demographic and clinical features, including response to corticosteroids and length of follow-up. They all presented with significant renal impairment. At presentation the mean+/-s.d. estimated glomerular filtration rate (eGFR) was 26.8+/-14 ml/min by modification of diet in renal disease (MDRD) equation 7. With treatment there was a significant improvement in renal function with eGFR 49.6+/-5.2 ml/min (P<0.01) at 1 year, and 47.9+/-6.8 ml/min (P<0.05) at the last review. The median follow-up was 84 months (range 6-284 months). Patients with chronic kidney disease (CKD) 3, the mean eGFR was 38.30+/-2.4 ml/min at presentation and 60.2+/-7.4 ml/min at 1 year (P=0.02) and in CKD 4 it improved from 19+/-2 to 38+/-6.6 ml/min at 1 year (P<0.05). After the 1st year, the change in eGFR was +0.8 ml/min/year for CKD 3 and -2 ml/min/year for CKD 4 (P<0.05). Three patients ceased their therapy either due to complications or poor compliance and experienced a worsening of renal function which was then reversed on re-commencing corticosteroids. Corticosteroids are effective in advanced tubulo-interstitial nephritis due to sarcoidosis. Long-term treatment is necessary to preserve renal function and to delay the onset of end-stage renal disease.

Alpha B-crystallin is a major component of glial cytoplasmic inclusions in multiple system atrophy

Multiple system atrophy (MSA) is characterized by the formation of oligodendroglial cytoplasmic inclusions (GCIs) consisting of alpha-synuclein filaments. AlphaB-crystallin, a small chaperone protein that binds to unfolded proteins and inhibits aggregation, has been documented in GCIs. We investigated the relative abundance and speciation of alphaB-crystallin in GCIs in MSA brains. We also examined the influence of alphaB-crystallin on the formation of cytoplasmic inclusions in cultured glial cells. Immunohistochemistry and confocal microscopy revealed alphaB-crystallin is a prominent component of GCIs, more abundant than in Lewy bodies in Lewy body dementia. One- and two-dimensional gel electrophoresis and mass spectrometric analysis of GCIs immunopurified from MSA brains indicated that alphaB-crystallin is a major protein component with multiple post-translationally modified species. In cultured C6 glioma cells treated with the proteasomal inhibitor, lactacystin, to induce accumulation of ubiquitinated proteins, a subset of cells showed increased cytoplasmic staining for alphaB-crystallin. Proteasome-inhibited cells transfected with GFP-tagged alpha-synuclein resulted in ubiquitin- and alphaB-crystallin-positive aggregates resembling GCIs in MSA brains. Our results indicate that alphaB-crystallin is a major chaperone in MSA, and suggest a role of the protein in the formation of inclusion bodies in glial cells.

Recurrence of Wegener's granulomatosis 13 years after renal transplantation

Wegener's granulomatosis (WG) can cause renal failure, requiring long-term renal replacement therapy. Renal transplantation in patients with WG is successful, but the risk for recurrence of the disease necessitates continued vigilance. We report a patient that originally presented with acute renal failure secondary to a pauci-immune focal necrotizing crescentic glomerulonephritis. Subsequent nasal involvement and serologic tests for antineutrophil cytoplasmic antibodies suggested a diagnosis of WG.

Targeting the function of mature dendritic cells by human cytomegalovirus: a multilayered viral defense strategy

Human cytomegalovirus (HCMV) can suppress and evade the immune system. We have identified as a mechanism the ability of HCMV to infect dendritic cells (DC), which initiate the antiviral immune response. HCMV-infected DC show enhanced expression of costimulatory molecules. In contrast, MHC molecules are partially downregulated, leading to a reduced antigen-presenting capacity. Moreover, the apoptosis-inducing ligands CD95L (FasL) and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) are upregulated, thereby enabling HCMV-infected DC to delete activated T lymphocytes. This additional layer of viral defense is complemented by nondeletional mechanisms, which suppress surviving T cells. Thus, infection of DC allows the virus to blunt the antiviral T cell response by a multilayered defense strategy and could play a pivotal role in HCMV-triggered immunosuppression.

Novel intra- and inter-molecular sulfinamide bonds in S100A8 produced by hypochlorite oxidation

Hypochlorite is a major oxidant generated when neutrophils and macrophages are activated at inflammatory sites, such as in atherosclerotic lesions. Murine S100A8 (A8) is a major cytoplasmic protein in neutrophils and is secreted by macrophages in response to inflammatory stimuli. After incubation with reagent HOCl for 10 min, approximately 85% of A8 was converted to 4 oxidation products, with electrospay ionization mass spectrometry masses of m/z 10354, 10388, 10354 +/- 1, and 20707 +/- 3. All were resistant to reduction by dithiothreitol. Initial formation of a reactive Cys sulfenic acid intermediate was demonstrated by the rapid conjugation of 5,5-dimethyl-1,3-cyclohexanedione (dimedone) to HOCl-treated A8 to form stable adducts. Matrix-assisted laser desorption-reflectron time of flight peptide mass fingerprinting of isolated oxidation products confirmed the mass additions observed in the full-length proteins. Both Met(36/73) were converted to Met(36/73) sulfoxides. An additional product with an unusual mass addition of m/z 14 (+/-0.2) was identified and corresponded to the addition of oxygen to Cys(41), conjugation to various epsilon-amines of Lys(6), Lys(34/35), or Lys(87) with loss of dihydrogen and formation of stable intra- or inter-molecular sulfinamide cross-links. Specific fragmentations identified in matrix-assisted laser desorption-post source decay spectra and low energy collisional-induced dissociation tandem mass spectroscopy spectra of sulfinamide-containing digest peptides confirmed Lys(34/35) to Cys(41) sulfinamide bonds. HOCl oxidation of mutants lacking Cys(41) (Ala(41)S100A8) or specific Lys residues (e.g. Lys(34/35), Ala(34/35)S100A8) did not form sulfinamide cross-links. HOCl generated by myeloperoxidase and H(2)O(2) and by phorbol 12-myristate 13-acetate-activated neutrophils also formed these products(.) In contrast to the disulfide-linked dimer, oxidized monomer retained normal chemotactic activity for neutrophils. Sulfinamide bond formation represents a novel oxidative cross-linking process between thiols and amines and may be a general consequence of HOCl protein oxidation in inflammation not identified previously. Similar modifications in other proteins could potentially regulate normal and pathological processes during aging, atherogenesis, fibrosis, and neurogenerative diseases.

Proinflammatory properties of the human S100 protein S100A12

S100 proteins represent a new class of chemoattractants. Here we extend earlier evidence for the proinflammatory properties of human S100A12. A12 induced migration of monocytoid cells, with optimal activity at 10(-10) M and potency of >10(-9) M C5a. Neutrophils were poorly responsive, and lymphocyte migration was not affected. Actin polymerization in monocytoid cells was accompanied by a sustained [Ca(2+)]i flux of a magnitude comparable with C5a. A12 elicited a transient infiltration of neutrophils (4-8 h) and more delayed recruitment of monocytes (8-24 h) in vivo. A12 (approximately 70 nM) was present in synovial fluid (SF) from rheumatoid arthritis patients, and synovium contained A12-positive neutrophils in the sublining and interstitial region, often surrounding the perivasculature but rarely in the synovial lining layer, although some macrophages were positive. The A12 gene was transiently up-regulated in monocytes by tumor necrosis factor alpha (6 h); induction by lipopolysaccharide (LPS) was sustained (12-48 h). A12 may contribute to leukocyte migration in chronic inflammatory responses.

An unexpected cause of muscle pain in diabetes

Diabetic muscle infarction is a rare condition which may present to a rheumatologist. It was first reported in 1965. Two illustrative cases are described here and the mechanisms of pathogenesis discussed. Analysis of the published data, results of the muscle biopsies, and a technetium-99m sestamibi scan suggest that the condition, which occurs against a background of diabetic microangiopathy, can be triggered by an ischaemic event and causes extensive muscle necrosis through hypoxia-reperfusion injury and compartment syndrome.

Safety and tolerability of a multidose formulation of epoetin beta in dialysis patients. Collaborative Study Group

AIM

Previous studies in healthy volunteers and renal patients have demonstrated the favorable tolerability of a new multidose formulation of epoetin beta. The aim of this open, multicenter study was to further assess the safety, tolerability and efficacy of this formulation ofepoetin beta in patients with end-stage renal disease (ESRD).

MATERIALS AND METHODS

375 adult patients receiving maintenance epoetin therapy for renal anemia were switched to the multidose formulation of epoetin beta for 12 weeks, using the same dosage and route of administration.

RESULTS

Adverse events were experienced by 123 patients (33%), most commonly hypertension (5.6%) and hypotension (4.5%). Few patients (2%) were prematurely withdrawn because of tolerability concerns. No clinically relevant changes in blood pressure or laboratory variables were observed. Compared with baseline, hemoglobin and hematocrit values remained essentially unchanged during treatment with this new formulation of epoetin beta. No changes in iron metabolism parameters were apparent, and nearly all patients (94%) did not require blood transfusions during the study.

CONCLUSION

The results of this study indicate that the multidose formulation of epoetin beta is safe and well tolerated in patients with ESRD. Moreover, switching patients to this new formulation of epoetin beta does not compromise therapeutic efficacy.

Cytomegalovirus infection of vascular cells induces expression of pro-inflammatory adhesion molecules by paracrine action of secreted interleukin-1beta

BACKGROUND

Infection with human cytomegalovirus (HCMV) has been associated with vascular disease processes such as vascular allograft rejection, transplantation vasculopathy, restenosis after angioplasty, and native atherosclerosis. To elucidate underlying pathomechanisms, the effect of acute HCMV infection on the expression of pro-inflammatory adhesion molecules on human umbilical vein endothelial cells (HUVEC) and human vascular smooth muscle cells (hvSMC) was examined.

METHODS AND RESULTS

Cells were infected in vitro with clinical strains of HCMV and the resulting changes in adhesion molecule expression were quantified by histology and flow cytometric analysis. On HUVEC, surface expression of vascular cell adhesion molecule-1 and E-selectin was induced de novo on HCMV infection and intercellular adhesion molecule-1 expression was increased by >200%. On hvSMC, intercellular adhesion molecule-1 surface expression induced de novo, although vascular cell adhesion molecule-1 and E-selectin were not changed. Expression of major histocompatibility complex (MHC) class II, lymphocyte-function associated antigen 3 (LFA-3; CD58), and CD40 was not altered by HCMV infection in either cell type. In partially infected cultures, up-regulation of surface molecules also occurred on noninfected cells, suggesting a paracrine mechanism via a soluble factor. Expression of surface molecules could be enhanced in noninfected HUVEC and hvSMC by incubation with virus-free conditioned supernatant from HCMV-infected cells or by coincubation in transwells with infected cells. The responsible agent could be identified as IL- interleukin- (IL) 1beta by detection of de novo secretion of IL-1beta by HCMV-infected cells and by prevention of adhesion molecule up-regulation after addition of an IL-1-converting enzyme inhibitor or IL-1 receptor antagonist. Surface molecule up-regulation could be suppressed by UV inactivation of virus, but not by treatment of cell cultures with inhibitors of viral replication (ganciclovir).

CONCLUSION

We propose that HCMV infection induces IL-1beta release and subsequent up-regulation of pro-inflammatory adhesion molecules on noninfected neighboring cells through a paracrine mechanism. This may lead to local potentiation of the inflammatory effects of HCMV infection, not amenable to current therapeutic antiviral strategies.

Increased plasma malondialdehyde levels in glomerular disease as determined by a fully validated HPLC method

BACKGROUND

Reactive oxygen species and particularly free radical induced lipid peroxidative tissue damage have been implicated in the pathogenesis of various renal diseases. Lipid peroxidation is assessed indirectly by the measurement of secondary products, such as malondialdehyde (MDA), using the widely employed thiobarbituric acid reactive substances (TBARS) method. However, this method lacks sensitivity and specificity. We have therefore developed and validated an HPLC (high-performance liquid chromatography) method for measurement of MDA and applied this to a variety of plasma samples in renal patients.

METHODS

The optimized method involves antioxidant treatment of the plasma sample, followed by a protein precipitation step using trichloroacetic acid, acid hydrolysis and formation of an MDA thiobarbituric acid complex. The MDA-(TBA)2 adduct is separated from other interfering compounds by C18 reverse-phase HPLC techniques, with visible detection at 532 nm.

RESULTS

The assay was linear over the ranges 0.25-1.0 microM MDA and the detection limit was 0.06 microM MDA. Within-run precision was <4.5% and between-run precision was <10.0%. MDA plasma concentrations (mean+/-SD) were higher in ESRF diabetic patients (0.32 +/- 0.14 microM, n=20), non-diabetic ESRF patients (0.32 +/- 0.09 microM, n=20), and CRF patients (0.14 +/- 0.06 microM, n=40) compared to healthy controls (0.11 +/- 0.03 microM, n=40), (P < 0.001, P < 0.001 and P = 0.008). Levels were similar in healthy controls with normal renal function and transplanted patients (0.12 +/- 0.03 microM MDA, n=40), (P=NS). No correlation was observed between MDA and creatinine levels (r2 = 0.05, n=80), which suggests that MDA does not correlate with the degree of renal impairment. We matched CRF patients with glomerular and non-glomerular causes of renal failure for creatinine levels and found that MDA levels were higher in patients with glomerulonephritis (0.16 +/- 0.06 microM) than in those with CRF from non-glomerular causes (0.12 +/- 0.04 microM, P = 0.002).

CONCLUSIONS

We have introduced a reliable and sensitive HPLC technique to enhance the specificity of MDA-(TBA)2 measurement, with a significant improvement in HPLC column life. Using this method, picomole quantities of MDA can be detected in plasma. We have shown that MDA levels are significantly raised in patients with CRF due to glomerulonephritis, regardless of serum creatinine, which suggests that there is oxidative injury independent of any possible MDA retention due to renal impairment.

Oxidation regulates the inflammatory properties of the murine S100 protein S100A8

The myeloid cell-derived calcium-binding murine protein, S100A8, is secreted to act as a chemotactic factor at picomolar concentrations, stimulating recruitment of myeloid cells to inflammatory sites. S100A8 may be exposed to oxygen metabolites, particularly hypochlorite, the major oxidant generated by activated neutrophils at inflammatory sites. Here we show that hypochlorite oxidizes the single Cys residue (Cys41) of S100A8. Electrospray mass spectrometry and SDS-polyacrylamide gel electrophoresis analysis indicated that low concentrations of hypochlorite (40 microM) converted 70-80% of S100A8 to the disulfide-linked homodimer. The mass was 20,707 Da, 92 Da more than expected, indicating additional oxidation of susceptible amino acids (possibly methionine). Phorbol 12-myristate 13-acetate activation of differentiated HL-60 granulocytic cells generated an oxidative burst that was sufficient to efficiently oxidize exogenous S100A8 within 10 min, and results implicate involvement of the myeloperoxidase system. Moreover, disulfide-linked dimer was identified in lung lavage fluid of mice with endotoxin-induced pulmonary injury. S100A8 dimer was inactive in chemotaxis and failed to recruit leukocytes in vivo. Positive chemotactic activity of recombinant Ala41S100A8 indicated that Cys41 was not essential for function and suggested that covalent dimerization may structurally modify accessibility of the chemotactic hinge domain. Disulfide-dependent dimerization may be a physiologically significant regulatory mechanism controlling S100A8-provoked leukocyte recruitment.

Overexpression, oxidative refolding, and zinc binding of recombinant forms of the murine S100 protein MRP14 (S100A9)

Recombinant murine MRP14 (mMRP14) was produced in Escherichia coli using the pGEX expression system. The mass of fusion protein, by electrospray ionization-mass spectrometry (ESI/MS), was 39,213 Da which compares well with the theoretical mass (39,210.4 Da). Thrombin digestion of fusion protein was expected at a cloned thrombin consensus sequence (. LVPRGS. ) located between glutathione S-transferase and mMRP14. Analysis of products of digestion by C4 reverse-phase HPLC and SDS-PAGE/Western blotting revealed two immunoreactive cleavage products with molecular weights around 13, 000. Masses of the two proteins determined by ESI/MS were 13,062 and 11,919 Da. The larger product corresponded to the expected mass of recombinant mMRP14 (13,061.9 Da). Analysis of the protein sequence of recombinant mMRP14 revealed a thrombin-like consensus sequence (. NNPRGH. ) located close to the C-terminus. The smaller protein corresponded to a truncated form of rec mMRP14 (rec MRP141-102) with a calculated mass of 11,918.6 Da. Optimization of the cleavage conditions resulted in >95% full-length rec mMRP14. Native mMRP14 contains one intramolecular disulfide bond between Cys79 and Cys90. The full-length recombinant protein was renatured and oxidized in ammonium acetate (pH approximately 7) for 96 h and formed >95% of the native intramolecular disulfide-bonded form. MRP141-102 bound substantially less 65Zn2+ compared to native mMRP14 or rec mMRP14 after transfer to polyvinylidene difluoride and incubation with 65ZnCl2, implicating the His residues located within the C-terminal domain in Zn2+ binding.

Identification of posttranslational modifications and cDNA sequencing errors in the rat S100 proteins MRP8 and 14 using electrospray ionization mass spectrometry

MRP8 and 14 are S100 proteins expressed by myeloid cells and are predicted to have important functions in inflammation. The proteins were isolated from spleens from three rat strains. Electrospray ionization mass spectrometry indicated masses of 10,149 +/- 2 Da for MRP8 and 13,069 +/- 2 Da for MRP14 compared to masses calculated from proteins derived from their cDNA sequences of 10,211 and 13,214 Da, respectively, indicating posttranslational modifications and/or errors in the derived protein sequences. Several endoprotease digest peptides did not correspond to any theoretical digest products after comparison of ESI masses with those derived from the theoretical digest. Both proteins were N-terminally acetylated after deletion of the initiator Met, reducing the theoretical masses by 89 Da. A peptide with mass 28 Da greater than the theoretical was isolated from the Asp N digestion of MRP8. N-terminal sequencing indicated translated Val instead of the predicted Ala at position 72 of MRP8. A peptide 56 Da less than the theoretical was isolated from the chymotryptic digestion of MRP14, and the carboxyamidomethylated form was N-terminally sequenced and found to have translated Ser instead of the predicted Arg at position 105. In addition, His106 was methylated. The corrected theoretical masses, incorporating the posttranslational modifications and sequencing errors, are 10,149.4 and 13,069.9 Da for MRP8 and 14, respectively, in good agreement with the experimental masses.

Identification of noncovalent dimeric complexes of the recombinant murine S100 protein CP10 by electrospray ionization mass spectrometry and chemical cross-linking

CP10 is a chemotactic S100 protein expressed by murine myeloid cells. A specific noncovalently linked dimeric complex of recombinant Ala43 CP10 was identified after electrospray ionization mass spectrometry using a nondenaturing solvent of 5-mM ammonium acetate (pH 6.5) and source temperature of 50 degrees C. With a low cone voltage (75 V), major ions were observed at approximately 2075, 2305, and 2613 Da, which were attributed to partially desolvated multiply charged noncovalently linked dimeric species (+10, +9, and +8 charge states, respectively). Deconvolution produced a broad peak centered around 20750 Da corresponding to the approximate mass of dimeric recombinant Ala43 CP10. Increasing the cone voltage, the collisionally activating the complex, gradually reduced the intensity of these dimeric ions, with a concomitant increase in higher and lower charge state monomeric ions. The intensities of these dimeric ions were greatly reduced in spectra recorded with a source temperature of 140 degrees C and cone voltage of 75 V, indicating a thermally unstable noncovalent complex. Similar spectra were obtained using recombinant CP10. Specific noncovalent S100 dimeric complexes were confirmed by chemically cross-linking recombinant Ala43 CP10 or CP10 with bis (sulfosuccinimidyl) suberate, followed by SDS/PAGE. The dominant silver-stained and CP10-immunoreactive component migrated at 20,000 suggested that the complex represents the major isoform in solution.

Diagnostic contribution of renal allograft biopsies at various intervals after transplantation

Renal allograft biopsy is the accepted gold standard for investigating episodes of graft dysfunction in the early posttransplant period. The situation is less clear in late transplant biopsies. Later renal biopsies performed for graft dysfunction or as part of a routine investigative protocol have not been subjected to detailed critical evaluation. Two hundred sixty-three consecutive renal allograft biopsies in a single center were evaluated. They were arbitrarily divided into three groups based on interval after transplantation: group 1, up to 3 months (n=117); group 2, 4-12 months (n=60); and group 3, greater than 12 months after transplantation (n=86). There were no significant differences in demographic factors among the groups. The mean interval after transplantation was 0.8+/-0.1 months in group 1, 6.1+/-0.3 months in group 2, and 40.1+/-3.4 months in group 3. There were six principal diagnostic categories: acute rejection (AR), chronic rejection (CR), cyclosporine (CsA) nephrotoxicity, acute tubular necrosis (ATN), normal, and others. A statistically significant decrease in the frequency of AR (P<0.001) was seen in group 3 (3%) compared with groups 1 (43%) and 2 (37%). In contrast, the frequency of CR was significantly higher (P<0.001) in group 3 (71%) compared with groups 1 (0) and 2 (10%). ATN was seen almost exclusively in group 1. All but one of the 37 patients with ATN were in this group. CsA nephrotoxicity remained an important cause of graft dysfunction in all three groups, with no significant difference in incidence among the three groups. The differences between groups with other histological types were not significant. Patient management was changed based on the biopsy report in 84 patients in group 1 (72%), 45 patients in group 2 (75%), and only 16 patients in group 3 (19%) (P<0.001). In only seven patients in group 3 did the change in management result in a significant change in serum creatinine. All of these seven patients had CsA nephrotoxicity on biopsy and also had a significantly higher level of CsA compared with those with AR or CR. Thus, the diagnosis might have been possible without the need for biopsy. We conclude that late renal allograft biopsies are only rarely helpful in patient management and as such should be an investigation of last resort.

Characterization of a mutant recombinant S100 protein using electrospray ionization mass spectrometry

Two recombinant proteins derived by thrombin cleavage of a fusion protein between glutathione-S-transferase and CP10 (Chemotactic protein 10 kDa) were separated by C4 reversed-phase high-performance liquid chromatography (RP-HPLC). Both proteins were recognised by a polyclonal antibody to native CP10 following sodium dodecyl sulphate/polyacryamide gel electrophoresis (SDS/PAGE) and Western blotting. The major form (approximately 90%) had a mass of 10308 Da, by electrospray mass spectrometry (ESI-MS), which compared well with the theoretical mass of rCP10 (10307.6 Da) whereas the minor component (approximately 10%) had a mass of 11333 Da, 1025 mass units greater than expected. One sequence was obtained by N-terminal sequencing, suggesting that the N-terminus was not modified. The mass of peptides isolated after Asp-N digestion and C18 RP-HPLC were determined by ESI-MS and each assigned a probable sequence based on the expected peptide man of rCP10. The mutant protein produced one additional peak at 10.0 min with mass 1639 Da and the sequence DSHKEQQRGIPGNSS by Edman degradation. The first 5 amino acids corresponded to the last 5 C-terminal amino acids of rCP10. Analysis of the cDNA sequence of the expression vector used to produce rCP10 indicated that the 10 additional C-terminal amino acids were translated after the insertion of glutamine at the normal TAG stop codon. Another stop codon (TGA) located 27 base pairs downstream halts translation. The calculated mass of the mutant protein is 11332.7 Da, in good agreement with the experimental mass. Readthrough occurs in strains of E. coli (eg JPA101) with the amber mutation supE, and this allowed substitution of glutamine at TAG codons in approximately 5-10% of transcripts.

Isolation of the murine S100 protein MRP14 (14 kDa migration-inhibitory-factor-related protein) from activated spleen cells: characterization of post-translational modifications and zinc binding

MRP14 (macrophage migration-inhibitory factor-related protein of molecular mass 14 kDa) is an S100 calcium binding protein constitutively expressed in human neutrophils which may be associated with cellular activation/inflammation. Murine MRP14 expression was up-regulated following concanavalin A activation of spleen cells, and the protein was isolated from conditioned medium in high yield (approx. 500 ng/ml). MRP14 had a mass of 12972 +/- 2 Da by electrospray ionization MS, whereas the theoretical mass derived from the cDNA sequence, after removal of the initiator Met, was 12918 Da, suggesting that the protein was post-translationally modified. We identified four post-translational modifications of MRP14: removal of the N-terminal Met, N-terminal acetylation, disulphide bond formation between Cys79 and Cys90, and 1-methylation of His106; the calculated mass was then 12971.8 Da. Methylation of His106 was further characterized after incubation of spleen cells with L-[methyl-3H]Met during concanavalin A stimulation. Sequential analysis of a peptide (obtained by digestion with Lys C) containing methylated His indicated that > 80% of the label in the cycle corresponded to His106, suggesting that the methyl residue was transferred from S-adenosyl-L-methionine. Comparison of the C18 reverse-phase HPLC retention times of phenylthiocarbamoyl derivatives of a hydrolysed digest peptide of MRP14 with those of standards confirmed methyl substitution on the 1-position of the imidazole ring. MRP14 bound more 85Zn2+ than the same amounts of the 10 kDa chemotactic protein (CP10) or S100 beta. Ca2+ decreased Zn2+ binding in S100 beta but it did not influence binding to MRP14, suggesting that the Zn2+ binding site was distinct from and independent of the two Ca2+ binding domains.

The structures of the frenatin peptides from the skin secretion of the giant tree frog Litoria infrafrenata

The granular dorsal glands of the giant tree frog Litoria infrafrenata contain five peptides including caerulein (a known neuropeptide), and four new peptides named franatins 1 (MH+ = 1140 Da), 2 (1423), 3 (2180), 4 (2493). The amino acid sequences of the frenatins are detailed: their structures do not correspond to those of peptides isolated from other amphibians or animals. Frenatin 3, Gly-Leu-Met-Ser-Val-Leu -Gly-His-Ala-Val-Gly-Asn-Val-Leu-Gly-Gly-Leu-Phe-Lys-Ser-(OH), has wide spectrum antimicrobial properties.

Membranous nephropathy complicating adenolymphoma of the parotid (Warthin's tumour)

Membranous nephropathy has been described in association with many malignancies including various lymphomas. However, it has not been previously described as a complication of benign solid adenolymphoma of the parotid, also called Warthin's tumour. We describe a patient who presented with an adenolymphoma of the parotid, and developed a severe nephrotic syndrome due to membranous nephropathy 6 months after the parotid swelling. The nephrotic syndrome resolved following parotidectomy and a short course of immunosuppression with prednisolone and cyclophosphamide. The possible pathophysiologic mechanisms are discussed.

Clinical pharmacokinetics of oral acyclovir in patients on continuous ambulatory peritoneal dialysis

It is increasingly recognised that dose adjustment of oral acyclovir in continuous ambulatory peritoneal dialysis (CAPD) patients is necessary to avoid neurotoxicity. A single 800-mg oral dose of acyclovir was administered to 10 uninfected anuric patients who were treated by CAPD. Serial blood and CAPD bag samples were analysed for acyclovir during the 31 h after dosing. Serum acyclovir levels were measured using radioimmunoassay and the pharmacokinetic parameters were estimated by linear regression using the STRIPE computer programme. Peak plasma levels of 8.95 +/- 3.95 microM were achieved at 4.1 +/- 1.85 h with the T1/2 calculated to be 14.52 +/- 3 h. The mean predicted serum acyclovir levels at steady state after 1,600-, 800- and 600-mg daily doses were 13.76, 6.88 and 5.16 microM, respectively. The present recommended daily doses of acyclovir (1,600 mg) for end-stage renal disease patients leads to supratherapeutic levels therefore increasing the risk and incidence of neurotoxicity. Computer modelling of various dosage simulations suggests that daily doses of 800 and 600 mg will achieve therapeutic levels (4-8 microM).

Novel Uperin Peptides From the Dorsal Glands of the Australian Floodplain Toadlet Uperoleia inundata

The dorsal glandular extract of the floodplain toadlet Uperoleia inundata contains more than 50 peptides: we report the amino acid sequences and bioactivity data of 13 of these. The peptides have been sequenced by using a combination of mass spectrometry and automated Edman sequencing. Ten of the peptides have been synthesized in order to confirm their structures, and to enable bioassays to be carried out. Ten peptides are host- defence agents, including ( i ) a powerful new neuropeptide of the tachykinin family which we name uperin 1.1 [ pGlu Ala Asp Pro Asn Ala Phe Tyr Gly Leu Met (NH2)], and (ii) nine antibiotic peptides including five uperins 2 [e.g. uperin 2.1, Gly Ile Val Asp Phe Ala Lys Lys Val Val Gly Gly Ile Arg Asn Ala Leu Gly Ile (OH)], three uperins 3 [e.g. uperin 3.1, Gly Val Leu Asp Ala Phe Arg Lys Ile Ala Thr Val Val Lys Asn Val Val (NH2)] and uperin 4.1 [ Gly Val Gly Ser Phe Ile His Lys Val Val Ser Ala Ile Lys Asn Val Ala (NH2)]. The function of the three other characterized peptides in the amphibian integument is not known, viz. ( i ) uperin 5.1 [ Phe Gln Phe Val Asn Pro Ser Asp Ile Val Phe Gly Ser (OH)] and (ii) the two uperins 6 [e.g. uperin 6.1, Gly Leu Ala Gly Ala Ile Ser Ser Ala Leu Asp Lys Leu Lys Gln Ser Gln Leu Ile Lys Asn Tyr Ala Lys Lys Leu Gly Tyr Pro Arg (OH)].

Urinary C5b-9 excretion and clinical course in idiopathic human membranous nephropathy

Recent reports suggested that the presence of terminal complement complex (C5b-9) in urine from patients with idiopathic membranous nephropathy (IMN) may indicate on-going immunological damage. This report documents the relationship between C5b-9 excretion and clinical outcome in 35 adult patients with biopsy-proven IMN and progressively declining renal function. There were two groups of patients. Group I received one of three treatment regimens: prednisolone alone, prednisolone and chlorambucil, or prednisolone and cyclophosphamide (N = 22). Group II received no immunosuppressive therapy (N = 17). Three of the 18 patients receiving immunosuppressive drugs had more than one treatment regimen as they experienced a clinical relapse during the study period; hence 22 treatments were available for analysis. Urine samples were collected regularly and urinary C5b-9 (uC5b-9) was determined by ELISA. Both groups were similar with respect to age, sex distribution, and the duration of follow-up. An improvement in proteinuria and creatinine clearance was noted in the immunosuppressed group. Thirty-five patients were excreting C5b-9 initially (18 from group I and 17 from group II); 17 patients continued to excrete C5b-9 at the end of the observation period. These 17 patients had a significantly worse clinical outcome when compared to the 18 patients whose C5b-9 excretion became negative, either spontaneously or with treatment (P < 0.005). These results indicate that continuing C5b-9 excretion is correlated with a poor clinical outcome. They also suggest that uC5b-9 is a dynamic marker of ongoing immunological injury, and therefore may be useful in the initial assessment and monitoring of patients with IMN and in identifying patients who may derive benefit from immunosuppressive therapy.

Reversible renal failure due to the antiphospholipid antibody syndrome, pre-eclampsia and renal thrombotic microangiopathy

A 27-year-old Caucasian female, with a past history of recurrent spontaneous abortions, was admitted with pre-eclampsia at 26 weeks' gestation during her sixth pregnancy. She was previously known to have antiphospholipid antibodies since her fifth abortion, but had no clinical or serological evidence of systemic lupus erythematosus. A small-for-dates infant was delivered by emergency Caesarean section at 27 weeks for poor placental blood flow and fetal distress. She was transferred to the renal unit on the sixth post partum day with pulmonary edema, hypertension, disseminated intravascular coagulation and acute renal failure. Renal biopsy showed lesions compatible with thrombotic microangiopathy with diffuse glomerular necrosis. She was plasma exchanged and remained dialysis dependent for 7 months. Antiphospholipid antibodies were present in high titres and were the presumed cause of her acute renal failure. The patient now has stable renal function with a creatinine clearance of 30 ml/min for over two years. The late recovery of renal function is unique in the above circumstances.

Development of human T-cell lymphotropic virus type I-associated adult T-cell leukemia/lymphoma during immunosuppressive treatment following renal transplantation

Although it is recognized that there is an increased incidence of lymphoproliferative disorders among patients who have received immunosuppressive therapy following transportation, there have been few reports of adult T-cell leukemia/lymphoma (ATLL) developing in previously asymptomatic carriers of human T-cell lymphotropic virus type I (HTLV-I) who have undergone transplantation. We describe the development of such a tumor in a man who was HTLV-I-positive and received immunosuppressive treatment following renal transplantation. As the number of individuals in ethnic groups at risk for organ transplantation increases, it would seem prudent to screen such individuals for carriage of HTLV-I before transplantation and to follow them prospectively to confirm if transplantation and immunosuppression predispose to the development of ATLL.

Avoiding acyclovir neurotoxicity in patients with chronic renal failure undergoing haemodialysis

Acute neurotoxicity following the administration of the recommended oral dose of acyclovir (800 mg twice daily) to dialysis-dependent patients is increasingly recognised. This suggests that the recommended dose is too high. Little is known of the pharmacokinetics of oral acyclovir in dialysis patients. We studied 7 patients with oliguric end stage renal failure receiving haemodialysis. Following haemodialysis, each patient received a single 800-mg tablet of acyclovir. Plasma acyclovir levels were monitored over the next 48 h as well as before and after the next routine dialysis. Peak plasma levels were achieved at 3 h (12.54 +/- 1.76 microM, range 8.5-17.5 microM) with the half-life calculated to be 20.2 +/- 4.6 h. Mean plasma level of 6.29 +/- 0.94 microM were within the quoted range to inhibit herpes zoster virus (4-8 microM) at 18 h. Haemodialysis (4-5 h) eliminated 51 +/- 11.5% of the acyclovir which remained at 48 h. Computer modelling of various dose modifications suggests that a loading dose of 400 mg and a maintenance dose of 200 mg twice daily is sufficient to maintain a mean plasma acyclovir level of 6.4 +/- 0.8 microM. A further loading dose (400 mg) after dialysis would raise the residual acyclovir concentration by 6.1 +/- 1.0 microM. Such a dose modification should prevent neurotoxicity, whilst the rapid elimination of acyclovir by a single haemodialysis treatment provides both a diagnostic and therapeutic tool when toxicity is suspected.

The Structures of Four Tryptophyllin and Three Rubellidin Peptides From the Australian Red Tree Frog Litoria rubella

The peptide content of the glandular secretions of Litoria rubella specimens collected from Derby and Lake Argyle (Kimberley region of Western Australia) and from near Darwin in the Northern Territory are all quite different; this suggests that there are different frog populations in these three areas. These different populations may be indicative of either different species or different sub-species of frog. There are two separate families of peptides in the glandular secretion of 'Litoria rubella': ( i ) those corresponding to the tryptophyllin family (tetra- to hepta -peptides all containing the residues Pro and Trp ), and (ii) the rubellidinins ( pentapeptides all containing two Phe residues at positions 3 and 4). To ate, no biological activity has been found for any of these peptides, but it is suspected that the tryptophyllins may be neurotransmitters or neuromodulators.

Peptides From Australian Frogs. The Structures of the Dynastins From the Banjo Frogs Limnodynastes interioris, Limnodynastes dumerilii and Limnodynastes terraereginae

The dermal glandular extracts of the tibial (calf) glands of the Australian banjo frogs Limnodynastes interioris, Limnodynastes dumerilii and Limnodynastes terraereginae each contain a different peptide, which we have named dynastin 1, 2 and 3 respectively. The determination of the sequences of these peptides is detailed.