Targeted rescue of synaptic plasticity improves cognitive decline in sepsis-associated encephalopathy.

Sepsis-associated encephalopathy (SAE) is a frequent complication of severe systemic infection resulting in delirium, premature death, and long-term cognitive impairment. We closely mimicked SAE in a murine peritoneal contamination and infection (PCI) model. We found long-lasting synaptic pathology in the hippocampus including defective long-term synaptic plasticity, reduction of mature neuronal dendritic spines, and severely affected excitatory neurotransmission. Genes related to synaptic signaling, including the gene for activity-regulated cytoskeleton-associated protein (Arc/Arg3.1) and members of the transcription-regulatory EGR gene family, were downregulated. At the protein level, ARC expression and mitogen-activated protein kinase signaling in the brain were affected. For targeted rescue we used adeno-associated virus-mediated overexpression of ARC in the hippocampus in vivo. This recovered defective synaptic plasticity and improved memory dysfunction. Using the enriched environment paradigm as a non-invasive rescue intervention, we found improvement of defective long-term potentiation, memory, and anxiety. The beneficial effects of an enriched environment were accompanied by an increase in brain-derived neurotrophic factor (BDNF) and ARC expression in the hippocampus, suggesting that activation of the BDNF-TrkB pathway leads to restoration of the PCI-induced reduction of ARC. Collectively, our findings identify synaptic pathomechanisms underlying SAE and provide a conceptual approach to target SAE-induced synaptic dysfunction with potential therapeutic applications to patients with SAE.

Temporary and highly variable recovery of neuromuscular dysfunction by electrical stimulation in the follow-up of acute critical illness neuromyopathy: a pilot study.

BACKGROUND: In sepsis-associated critical illness neuromyopathy (CIPNM) serial electrical stimulation of motor nerves induces a short-lived temporary recovery of compound muscle action potentials (CMAPs) termed facilitation phenomenon (FP). This technique is different from other stimulation techniques published. The identification of FP suggests a major functional component in acute CIPNM. METHODS: From our previous study cohort of 18 intensive care unit patients with sepsis associated CIPNM showing profound muscle weakness and low or missing CMAPs on nerve conduction studies, six patients with different severity could be followed. In a pilot sub-study we analyzed the variability of FP during follow up. Over up to 6 weeks we performed 2-6 nerve conduction studies with our novel stimulation paradigm. Motor nerves were stimulated at 0.2-0.5 Hz with 60-100 mA at 0.2-0.5 ms duration, and CMAP responses were recorded. Standard motor nerve conduction velocities (NCV) could be done when utilizing facilitated CMAPs. Needle electromyography was checked once for spontaneous activity to discover potential denervation and muscle fiber degeneration. Serum electrolytes were checked before any examination and corrected if abnormal. RESULTS: In all six patients a striking variability in the magnitude and pattern of FP could be observed at each examination in the same and in different motor nerves over time. With the first stimulus most CMAPs were below 0.1 mV or absent. With slow serial pulses CMAPs could gradually recover with normal shape and near normal amplitudes. With facilitated CMAPs NCV measurements revealed low normal values. With improvement of muscle weakness subsequent tests revealed larger first CMAP amplitudes and smaller magnitudes of FP. Needle EMG showed occasional spontaneous activity in the tibialis anterior muscle. CONCLUSION: In this pilot study striking variability and magnitude of FP during follow-up was a reproducible feature indicating major fluctuations of neuromuscular excitability that may improve during follow-up. FP can be assessed by generally available electrophysiological techniques, even before patients could be tested for muscle strength. Large scale prospective studies of the facilitation phenomenon in CIPNM with or without sepsis are needed to define diagnostic specificity and to better understand the still enigmatic pathophysiology. TRIAL REGISTRATION: This trial was registered at the Leipzig University Medical Center in 2021 after approval by the Ethics Committee.

Temporary reversal of nerve and muscle dysfunction by serial electrical stimulation in critical illness neuromyopathy.

OBJECTIVE: Critical Illness Neuromyopathy (CIPNM) is a complication in sepsis patients with still enigmatic disease mechanisms. We investigated a novel electrical stimulation method to better define neuromuscular dysfunction in patients with CIPNM. METHODS: We studied 18 sepsis CIPNM patients on intensive care units, 13 at an early and 5 at a later disease stage, 7 sepsis control, and 8 neuropathy control patients. We applied slow conditioning electrical pulses at motor nerves and directly at the muscle to investigate a facilitation phenomenon (FP) of small or absent compound motor action potentials (CMAPs). RESULTS: Serial pulses induced a 2 to 490-fold increase in CMAP amplitudes in 17/18 Intensive Care Unit (ICU)-CIPNM patients (p < 0.001). These effects were short lived and reproducible. Direct muscle stimulation in the tibialis anterior muscle resulted in up to 130-fold FP in 7/9 patients tested (p < 0.01). In 4/5 post-ICU CIPNM patients FP was up to 10-fold. None of the 7 ICU sepsis control patients without CIPNM with similar disease severity and none of 8 neuropathy patients showed FP (p < 0.001). On needle EMG only 5/16 ICU patients tested revealed spontaneous activity. CONCLUSIONS: Conditioning electrical stimulation detected a functional component of the disease process showing temporary improvement in sepsis-associated CIPNM. SIGNIFICANCE: New test differentiates functional from degenerative pathology.

Functional predictors of treatment induced diabetic neuropathy (TIND): a prospective pilot study using clinical and neurophysiological functional tests.

BACKGROUND: A treatment-induced drop in HbA1c has been suggested to be a risk factor for TIND. METHODS: From 60 included patients with severe diabetes mellitus (HbA1c over 8.5) only 21 patients adhered to the study protocol over 1 year with a battery of autonomic nervous system tests scheduled before and after starting antidiabetic treatment. RESULTS: In patients with a drop of HbA1c greater than 2 per cent points only some neurophysiologic tests and lab values tended to deteriorate with a trend to improve at later time points along the study. None of these changes were statistically significant, most likely because the study failed to reach the planned number of patients. CONCLUSION: Poor adherence to diabetes treatment and to following the study protocol were the assumed obstacles in our patient cohort selected for very high HbA1c levels. In future studies a multi-center trial and case numbers of up to 500 patients may be needed to account for drop outs in the range observed here. Moreover, the number of tests in each patient at each visit may have to be reduced and special educational group sessions are warranted to cope with the limited adherence. Trial registration Ethic Committee University of Leipzig 439/15-ek. Registered 22 April 2016.

Inflammatory Mechanisms in the Pathophysiology of Diabetic Peripheral Neuropathy (DN)-New Aspects.

The pathogenesis of diabetic neuropathy is complex, and various pathogenic pathways have been proposed. A better understanding of the pathophysiology is warranted for developing novel therapeutic strategies. Here, we summarize recent evidence from experiments using animal models of type 1 and type 2 diabetes showing that low-grade intraneural inflammation is a facet of diabetic neuropathy. Our experimental data suggest that these mild inflammatory processes are a likely common terminal pathway in diabetic neuropathy associated with the degeneration of intraepidermal nerve fibers. In contrast to earlier reports claiming toxic effects of high-iron content, we found the opposite, i.e., nutritional iron deficiency caused low-grade inflammation and fiber degeneration while in normal or high non-heme iron nutrition no or only extremely mild inflammatory signs were identified in nerve tissue. Obesity and dyslipidemia also appear to trigger mild inflammation of peripheral nerves, associated with neuropathy even in the absence of overt diabetes mellitus. Our finding may be the experimental analog of recent observations identifying systemic proinflammatory activity in human sensorimotor diabetic neuropathy. In a rat model of type 1 diabetes, a mild neuropathy with inflammatory components could be induced by insulin treatment causing an abrupt reduction in HbA1c. This is in line with observations in patients with severe diabetes developing a small fiber neuropathy upon treatment-induced rapid HbA1c reduction. If the inflammatory pathogenesis could be further substantiated by data from human tissues and intervention studies, anti-inflammatory compounds with different modes of action may become candidates for the treatment or prevention of diabetic neuropathy.

Treatment-Induced Neuropathy in Diabetes (TIND)-Developing a Disease Model in Type 1 Diabetic Rats.

Treatment-induced neuropathy in diabetes (TIND) is defined by the occurrence of an acute neuropathy within 8 weeks of an abrupt decrease in glycated hemoglobin-A1c (HbA1c). The underlying pathogenic mechanisms are still incompletely understood with only one mouse model being explored to date. The aim of this study was to further explore the hypothesis that an abrupt insulin-induced fall in HbA1c may be the prime causal factor of developing TIND. BB/OKL (bio breeding/OKL, Ottawa Karlsburg Leipzig) diabetic rats were randomized in three groups, receiving insulin treatment by implanted subcutaneous osmotic insulin pumps for 3 months, as follows: Group one received 2 units per day; group two 1 unit per day: and group three 1 unit per day in the first month, followed by 2 units per day in the last two months. We serially examined blood glucose and HbA1c levels, motor- and sensory/mixed afferent conduction velocities (mNCV and csNCV) and peripheral nerve morphology, including intraepidermal nerve fiber density and numbers of Iba-1 (ionized calcium binding adaptor molecule 1) positive macrophages in the sciatic nerve. Only in BB/OKL rats of group three, with a rapid decrease in HbA1c of more than 2%, did we find a significant decrease in mNCV in sciatic nerves (81% of initial values) after three months of treatment as compared to those group three rats with a less marked decrease in HbA1c <2% (mNCV 106% of initial values, p ≤ 0.01). A similar trend was observed for sensory/mixed afferent nerve conduction velocities: csNCV were reduced in BB/OKL rats with a rapid decrease in HbA1c >2% (csNCV 90% of initial values), compared to those rats with a mild decrease <2% (csNCV 112% of initial values, p ≤ 0.01). Moreover, BB/OKL rats of group three with a decrease in HbA1c >2% showed significantly greater infiltration of macrophages by about 50% (p ≤ 0.01) and a decreased amount of calcitonin gene related peptide (CGRP) positive nerve fibers as compared to the animals with a milder decrease in HbA1c. We conclude that a mild acute neuropathy with inflammatory components was induced in BB/OKL rats as a consequence of an abrupt decrease in HbA1c caused by high-dose insulin treatment. This experimentally induced neuropathy shares some features with TIND in humans and may be further explored in studies into the pathogenesis and treatment of TIND.

Soluble dimeric prion protein ligand activates Adgrg6 receptor but does not rescue early signs of demyelination in PrP-deficient mice.

The adhesion G-protein coupled receptor Adgrg6 (formerly Gpr126) is instrumental in the development, maintenance and repair of peripheral nervous system myelin. The prion protein (PrP) is a potent activator of Adgrg6 and could be used as a potential therapeutic agent in treating peripheral demyelinating and dysmyelinating diseases. We designed a dimeric Fc-fusion protein comprising the myelinotrophic domain of PrP (FT2Fc), which activated Adgrg6 in vitro and exhibited favorable pharmacokinetic properties for in vivo treatment of peripheral neuropathies. While chronic FT2Fc treatment elicited specific transcriptomic changes in the sciatic nerves of PrP knockout mice, no amelioration of the early molecular signs demyelination was detected. Instead, RNA sequencing of sciatic nerves revealed downregulation of cytoskeletal and sarcomere genes, akin to the gene expression changes seen in myopathic skeletal muscle of PrP overexpressing mice. These results call for caution when devising myelinotrophic therapies based on PrP-derived Adgrg6 ligands. While our treatment approach was not successful, Adgrg6 remains an attractive therapeutic target to be addressed in other disease models or by using different biologically active Adgrg6 ligands.

Focal brain ischemia in mice does not cause electrophysiological signs of critical illness neuropathy.

OBJECTIVE: Critical illness polyneuropathy (CIP) is a common complication of severe systemic illness treated in intensive care medicine. Ischemic stroke leads to an acute critical injury of the brain with hemiparesis, immunosuppression and subsequent infections, all of which require extended medical treatment. Stroke-induced sarcopenia further contributes to poor rehabilitation and is characterized by muscle wasting and denervation in the paralytic, but also the unaffected limbs. Therefore, we asked whether stroke leads to an additional CIP-like neurodegeneration. RESULTS: Focal brain ischemia was induced in adult mice by 60-min middle cerebral artery occlusion (MCAo) following reperfusion and led to functional deficits and marked hemispheric brain atrophy. Nerve conduction function and muscle potentials were measured in the ipsilateral sciatic nerve and gastrocnemius and quadriceps muscle with electroneurography/-myography on days 10, 22, 44 after stroke. An additional crush-injury to the sciatic nerve was included in two sham mice as positive control (sham +). We found no differences in nerve conduction function nor spontaneous electromyographic activity between MCAo and sham animals. Sham + mice developed marked reduction of the motor action potential amplitudes and conduction velocities with pathologic spontaneous activity. In conclusion, we found no peripheral nerve dysfunction/degeneration as signs of a CIP-like phenotype after MCAo.

Mice carrying an analogous heterozygous dynamin 2 K562E mutation that causes neuropathy in humans develop predominant characteristics of a primary myopathy.

Some mutations affecting dynamin 2 (DNM2) can cause dominantly inherited Charcot-Marie-Tooth (CMT) neuropathy. Here, we describe the analysis of mice carrying the DNM2 K562E mutation which has been associated with dominant-intermediate CMT type B (CMTDIB). Contrary to our expectations, heterozygous DNM2 K562E mutant mice did not develop definitive signs of an axonal or demyelinating neuropathy. Rather, we found a primary myopathy-like phenotype in these mice. A likely interpretation of these results is that the lack of a neuropathy in this mouse model has allowed the unmasking of a primary myopathy due to the DNM2 K562E mutation which might be overshadowed by the neuropathy in humans. Consequently, we hypothesize that a primary myopathy may also contribute to the disease mechanism in some CMTDIB patients. We propose that these findings should be considered in the evaluation of patients, the determination of the underlying disease processes and the development of tailored potential treatment strategies.

The Role of Iron and Nerve Inflammation in Diabetes Mellitus Type 2-Induced Peripheral Neuropathy.

Peripheral diabetic neuropathy (PDN) is one of the most common complications of diabetes mellitus. Previous studies showed an association between dietary iron load and inflammation in the development of PDN in a rat model of type 1 diabetes (T1D). Here we investigated the role of iron and neural inflammation in development of PDN in a animal model of obesity and type 2 diabetes (T2D). 3-month-old db/db mice were fed with a high, standard or low iron diet for 4 months. High iron chow lead to a significant increase in motor nerve conduction velocities compared to mice on standard and low iron chow. Direct beneficiary effects on lowering blood glucose and HbA1c concentrations were shown in the high iron treated diabetic mice. Numbers of pro-inflammatory M1 macrophages were reduced in nerve sections, and anti-inflammatory M2 macrophages were increased in db/db mice on high iron diet compared to other groups. These results confirm and extend our previous findings in STZ-diabetic rats by showing that dietary non-hem iron supplementation may partly prevent the development of PDN in opposition to iron restriction. The identification of these dietary iron effects on the metabolic and inflammatory mechanisms of PDN supports a role of dietary iron and leads us to suggest testing for iron levels in human diabetic patients.

Schwann cells, but not Oligodendrocytes, Depend Strictly on Dynamin 2 Function.

Myelination requires extensive plasma membrane rearrangements, implying that molecules controlling membrane dynamics play prominent roles. The large GTPase dynamin 2 (DNM2) is a well-known regulator of membrane remodeling, membrane fission, and vesicular trafficking. Here, we genetically ablated Dnm2 in Schwann cells (SCs) and in oligodendrocytes of mice. Dnm2 deletion in developing SCs resulted in severely impaired axonal sorting and myelination onset. Induced Dnm2 deletion in adult SCs caused a rapidly-developing peripheral neuropathy with abundant demyelination. In both experimental settings, mutant SCs underwent prominent cell death, at least partially due to cytokinesis failure. Strikingly, when Dnm2 was deleted in adult SCs, non-recombined SCs still expressing DNM2 were able to remyelinate fast and efficiently, accompanied by neuropathy remission. These findings reveal a remarkable self-healing capability of peripheral nerves that are affected by SC loss. In the central nervous system, however, we found no major defects upon Dnm2 deletion in oligodendrocytes.

The role of dietary non-heme iron load and peripheral nerve inflammation in the development of peripheral neuropathy (PN) in obese non-diabetic leptin-deficient ob/ob mice.

INTRODUCTION: Here, we investigated inflammatory signs of peripheral nerves in leptin-deficient obese ob/ob mice and the modulating effects of the exogenous iron load. METHODS: Ob/ob and ob/+ control mice were fed with high, standard, or low iron diet for four months. RESULTS: We found intraepidermal nerve fiber degeneration in foot skin and low-grade neuropathic abnormalities including mildly slowed motor and compound sensory nerve conduction velocities and low-grade macrophage and T-cell infiltration without overt neuropathology in sciatic nerves of all ob/ob mice. Low dietary iron load caused more pronounced abnormalities than high iron load in ob/ob mice. DISCUSSION: Our data suggest that dietary non-heme iron deficiency may be a modulating factor in the pathogenesis of peripheral neuropathy in obese ob/ob mice with metabolic syndrome. Once the mechanisms can be further elucidated, how low dietary iron augments peripheral nerve degeneration and dysfunction via pro-inflammatory pathways and new therapeutic strategies could be developed. ABBREVIATIONS: CMAP: compound muscle action potential; cSNCV: compound sensory nerve conduction velocity; IENFD: intraepidermal nerve fiber density; LDL: low-density lipoprotein; MetS: metabolic syndrome; MNCV: motor conduction velocity; NCV: nerve conduction velocity; PN: peripheral neuropathy; PNS: peripheral nervous system; STZ: streptozotocin; T2D: type 2 diabetes mellitus; TNF alpha: tumor necrosis factor alpha; WHO: World Health Organization.

Defective synaptic transmission causes disease signs in a mouse model of juvenile neuronal ceroid lipofuscinosis.

Juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease) caused by mutations in the CLN3 gene is the most prevalent inherited neurodegenerative disease in childhood resulting in widespread central nervous system dysfunction and premature death. The consequences of CLN3 mutation on the progression of the disease, on neuronal transmission, and on central nervous network dysfunction are poorly understood. We used Cln3 knockout (Cln3Δex1-6) mice and found increased anxiety-related behavior and impaired aversive learning as well as markedly affected motor function including disordered coordination. Patch-clamp and loose-patch recordings revealed severely affected inhibitory and excitatory synaptic transmission in the amygdala, hippocampus, and cerebellar networks. Changes in presynaptic release properties may result from dysfunction of CLN3 protein. Furthermore, loss of calbindin, neuropeptide Y, parvalbumin, and GAD65-positive interneurons in central networks collectively support the hypothesis that degeneration of GABAergic interneurons may be the cause of supraspinal GABAergic disinhibition.

Cellular infiltrates in skin and sural nerve of patients with polyneuropathies.

INTRODUCTION: The aim of this study was to determine the diagnostic usefulness of skin punch biopsies with emphasis on visualization and quantification of T-cells and macrophages in patients with polyneuropathies. METHODS: We quantified inflammatory cells in skin samples (lower leg, upper thigh) in 187 patients and compared data with counts in their sural nerve biopsies and with skin biopsies from 32 healthy volunteers. RESULTS: Vessel-bound T-cells and macrophages were increased in proximal and distal skin samples of neuropathy patients compared with controls (P < 0.001 in both). Patients with vasculitic neuropathy had increased T-cell and macrophage counts in distal skin compared with controls (P < 0.01; for scattered macrophages/mm2 diagnostic sensitivity 71% and specificity 79%). In patients with vasculitic neuropathy, distal skin perivascular inflammatory cell counts also correlated with those in sural nerve biopsies (P < 0.001). CONCLUSION: Neuropathy per se may lead to skin inflammation. In cases of possible vasculitic neuropathy, skin biopsy may be an additional tool to support the diagnosis. Muscle Nerve 55: 884-893, 2017.

Tor1a+/- mice develop dystonia-like movements via a striatal dopaminergic dysregulation triggered by peripheral nerve injury.

Isolated generalized dystonia is a central motor network disorder characterized by twisted movements or postures. The most frequent genetic cause is a GAG deletion in the Tor1a (DYT1) gene encoding torsinA with a reduced penetrance of 30-40 % suggesting additional genetic or environmental modifiers. Development of dystonia-like movements after a standardized peripheral nerve crush lesion in wild type (wt) and Tor1a+/- mice, that express 50 % torsinA only, was assessed by scoring of hindlimb movements during tail suspension, by rotarod testing and by computer-assisted gait analysis. Western blot analysis was performed for dopamine transporter (DAT), D1 and D2 receptors from striatal and quantitative RT-PCR analysis for DAT from midbrain dissections. Autoradiography was used to assess the functional DAT binding in striatum. Striatal dopamine and its metabolites were analyzed by high performance liquid chromatography. After nerve crush injury, we found abnormal posturing in the lesioned hindlimb of both mutant and wt mice indicating the profound influence of the nerve lesion (15x vs. 12x relative to control) resembling human peripheral pseudodystonia. In mutant mice the phenotypic abnormalities were increased by about 40 % (p < 0.05). This was accompanied by complex alterations of striatal dopamine homeostasis. Pharmacological blockade of dopamine synthesis reduced severity of dystonia-like movements, whereas treatment with L-Dopa aggravated these but only in mutant mice suggesting a DYT1 related central component relevant to the development of abnormal involuntary movements. Our findings suggest that upon peripheral nerve injury reduced torsinA concentration and environmental stressors may act in concert in causing the central motor network dysfunction of DYT1 dystonia.

Efficacy of Polyvalent Human Immunoglobulins in an Animal Model of Neuromyelitis Optica Evoked by Intrathecal Anti-Aquaporin 4 Antibodies.

Neuromyelitis Optica Spectrum Disorders (NMOSD) are associated with autoantibodies (ABs) targeting the astrocytic aquaporin-4 water channels (AQP4-ABs). These ABs have a direct pathogenic role by initiating a variety of immunological and inflammatory processes in the course of disease. In a recently-established animal model, chronic intrathecal passive-transfer of immunoglobulin G from NMOSD patients (NMO-IgG), or of recombinant human AQP4-ABs (rAB-AQP4), provided evidence for complementary and immune-cell independent effects of AQP4-ABs. Utilizing this animal model, we here tested the effects of systemically and intrathecally applied pooled human immunoglobulins (IVIg) using a preventive and a therapeutic paradigm. In NMO-IgG animals, prophylactic application of systemic IVIg led to a reduced median disease score of 2.4 on a 0-10 scale, in comparison to 4.1 with sham treatment. Therapeutic IVIg, applied systemically after the 10th intrathecal NMO-IgG injection, significantly reduced the disease score by 0.8. Intrathecal IVIg application induced a beneficial effect in animals with NMO-IgG (median score IVIg 1.6 vs. sham 3.7) or with rAB-AQP4 (median score IVIg 2.0 vs. sham 3.7). We here provide evidence that treatment with IVIg ameliorates disease symptoms in this passive-transfer model, in analogy to former studies investigating passive-transfer animal models of other antibody-mediated disorders.

Immunoadsorption versus plasma exchange versus combination for treatment of myasthenic deterioration.

OBJECTIVES: The goal of this study was to analyze safety and assess the efficacy of standard plasma exchange (PE) compared with immunoadsorption (IA) alone, or an alternating combination of both in deteriorating myasthenia gravis (MG). METHODS: A total of 72 patients with MG who had received PE procedures for treatment of severe deterioration were retrospectively analyzed. They received either five cycles of PE (1-1.5 plasma volumes), or five cycles of IA in line with plasma separation, or a sequential alternating procedure of one cycle of PE followed by two cycles of IA, which was repeated once or more if needed. RESULTS: A total of 19 patients received PE, 24 patients IA, and 29 the alternating combination therapy. All groups were equally distributed by sex and mean MG score before treatment. The number of treatment cycles and days on therapy did not differ between the groups. Mean MG scores at discharge were 3.0 (PE), 1.8 (IA) and 1.6 (combination) (p = 0.028 for combination versus PE). Inpatient time was 30.7 days (PE), 22.3 days (IA) and 20.0 days in combination therapy (p < 0.05 for combination versus PE). Side effects such as allergic reactions or hypocoagulability were significantly more frequent in the PE group (37% in PE versus 4% in IA and 3.6% in the alternating combination, p < 0.05). CONCLUSION: Semiselective IA in combination with PE, and to a lesser extent IA alone, was associated with a shorter hospital stay and more pronounced reduction of the MG score than PE.

Malignancies after mitoxantrone for multiple sclerosis: A retrospective cohort study.

OBJECTIVE: To assess the therapy-related risk of malignancies in mitoxantrone-treated patients with multiple sclerosis. METHODS: This retrospective observational cohort study included all mitoxantrone-treated patients with multiple sclerosis seen at our department between 1994 and 2007. We collected follow-up information on medically confirmed malignancies, life status, and cause of death, as of 2010. Malignancy rates were compared to the German national cancer registry matched for sex, age, and year of occurrence. RESULTS: Follow-up was completed in 676 of 677 identified patients. Median follow-up time was 8.7 years (interquartile range 6.8-11.2), corresponding to 6,220 person-years. Median cumulative mitoxantrone dose was 79.0 mg/m(2) (interquartile range 50.8-102.4). Thirty-seven patients (5.5%) were diagnosed with a malignancy after mitoxantrone initiation, revealing a standardized incidence ratio of 1.50 (95% confidence interval [CI] 1.05-2.08). Entities included breast cancer (n = 9), colorectal cancer (n = 7), acute myeloid leukemia (n = 4, 0.6%), and others (each entity n = 1 or 2). The standardized incidence ratio of colorectal cancer was 2.98 (95% CI 1.20-6.14) and of acute myeloid leukemia 10.44 (95% CI 3.39-24.36). It was not increased for other entities including breast cancer. Multivariate Cox regression identified higher age at treatment initiation but neither cumulative mitoxantrone dose (>75 vs ≤75 mg/m(2)) nor treatment with other immunosuppressive drugs or sex as a risk factor. Fifty-five patients had died, among them 12 of a malignancy and 43 reportedly of other causes. CONCLUSIONS: While the overall incidence of malignancies was only mildly increased, the risk of leukemia and colorectal cancer was heightened. If confirmed, posttherapy colonoscopy could become advisable.

The role of nerve inflammation and exogenous iron load in experimental peripheral diabetic neuropathy (PDN).

BACKGROUND: Iron is an essential but potentially toxic metal in mammals. Here we investigated a pathogenic role of exogenous iron in peripheral diabetic neuropathy (PDN) in an animal model for type 1 diabetes. METHODS: Diabetes was induced by a single injection of streptozotocin (STZ) in 4-month-old Sprague-Dawley rats. STZ-diabetic rats and non-diabetic rats were fed with high, standard, or low iron diet. After three months of feeding, animals were tested. RESULTS: STZ-rats on standard iron diet showed overt diabetes, slowed motor nerve conduction, marked degeneration of distal intraepidermal nerve fibers, mild intraneural infiltration with macrophages and T-cells in the sciatic nerve, and increased iron levels in serum and dorsal root ganglion (DRG) neurons. While motor fibers were afflicted in all STZ-groups, only a low iron-diet led also to reduced sensory conduction velocities in the sciatic nerve. In addition, only STZ-rats on a low iron diet showed damaged mitochondria in numerous DRG neurons, a more profound intraepidermal nerve fiber degeneration indicating small fiber neuropathy, and even more inflammatory cells in sciatic nerves than seen in any other experimental group. CONCLUSIONS: These results indicate that dietary iron-deficiency rather than iron overload, and mild inflammation may both promote neuropathy in STZ-induced experimental PDN.