Spinal and bulbar muscular atrophy: skeletal muscle pathology in male patients and heterozygous females

Spinal and bulbar muscular atrophy (SBMA) is an adult form of X-linked motor neuron disease caused by an expansion of a CAG repeat sequence in the first exon of the androgen receptor (AR) gene. Nuclear accumulation of mutant AR with expanded polyglutamines in motor neurons is a major pathogenic mechanism. To characterize muscle involvement in SBMA the skeletal muscle biopsies of 8 SBMA patients and 3 female carriers were studied. Six of 8 SBMA patients showed myogenic changes together with the neurogenic atrophy in their muscle biopsy. Myopathic abnormalities did not correlate with disease duration and were more prominent in the muscle of patients with an higher degree of disability. In all patients plasma CK levels were more elevated than what usually occurs in denervative diseases. Both neurogenic and myopathic changes were also observed in female carriers. Here we suggest that myopathic changes in SBMA muscle are not only related to denervation and that muscle satellite cells may have a role in the pathogenesis of muscle damage.     

Novel autoantigens recognized by CSF IgG from Hashimoto's encephalitis revealed by a proteomic approach

To identify the target of IgG autoimmune response in Hashimoto's encephalopathy (HE), we studied the binding of IgG present in serum and cerebro-spinal fluid (CSF) from six patients with HE and 15 controls to human central nervous system (CNS) white matter antigens by 2D-PAGE and immunoblotting and by immunohistochemistry. We found that CSF IgG from HE patients specifically recognized 3 spots, which were identified as dimethylargininase-I (DDAHI) and aldehyde reductase-I (AKRIAI). DDAHI was present in two isoforms recognized respectively by five and four HE patients; immunohistochemistry with anti-DDAHI antiserum depicted endothelial cells in normal human CNS. AKRIAI was recognized by three HE CSF and this enzyme was widely distributed on neurons and endothelia by immunohistochemistry. IgG from HE CSF immunostained both neuronal and endothelial cells in mouse CNS. The presence of these autoantibodies selectively in the CSF of HE patients may have important diagnostic and pathogenetic implications, since the autoimmune response to these enzymes may lead to vascular and/or neuronal damage, two major mechanisms involved in the pathogenesis of HE.     

2-(4-Chlorobenzyl)-3-hydroxy-7,8,9,10-tetrahydrobenzo[H]quinoline-4-carboxylic acid (PSI-697): identification of a clinical candidate from the quinoline salicylic acid series of P-selectin antagonists

P-selectin-PSGL-1 interaction causes rolling of leukocytes on the endothelial cell surface, which subsequently leads to firm adherence and leukocyte transmigration through the vessel wall into the surrounding tissues. P-selectin is upregulated on the surface of both platelets and endothelium in a variety of atherosclerosis-associated conditions. Consequently, inhibition of this interaction by means of a small molecule P-selectin antagonist is an attractive strategy for the treatment of atherosclerosis. High-throughput screening and subsequent analoging had led to the identification of compound 1 as the lead candidate. Herein, we report the continuation of this work and the discovery of a second-generation series, the tetrahydrobenzoquinoline salicylic acids. These compounds have improved pharmacokinetic properties, and a number of them have shown oral efficacy in mouse and rat models of atherogenesis and vascular injury. The lead 31 (PSI-697), is currently in clinical development for the treatment of atherothrombotic vascular events.     

Double-strand breaks may initiate the inversion mutation causing the Hunter syndrome

We have previously shown that patients with the Hunter syndrome frequently have suffered from a recombination event between the IDS gene and its putative pseudogene, IDS-2, resulting in an inversion of the intervening DNA. The inversion, which might be the consequence of an intrachromosomal mispairing, is caused by homologous recombination between sequences located in intron 7 of the IDS gene and sequences located distal of exon 3 in IDS-2. In order to gain insight into the mechanisms causing the inversion, we have isolated both inversion junctions in six unrelated patients. DNA sequence analysis of the junctions showed that all recombinations have taken place within a 1 kb region where the sequence identity is >98%. An interesting finding was the identification of regions with alternating IDS gene and IDS-2 sequences present at one inversion junction, suggesting that the recombination event has been initiated by a double-strand break in intron 7 of the IDS gene. The results from this study suggest that homologous recombination in man could be explained by mechanisms similar to those described for Saccharomyces cerevisiae. The results also have practical implications for diagnosis of patients with the Hunter syndrome.      

Hyaluronan and Human Endothelial Cell Behavior

Hyaluronan (HA) is the only nonsulphated glycosaminoglycan of extracellular matrix. In mammals HA is synthesised by three homologues HA synthases: HAS1, HAS2, and HAS3. The HA is daily catabolized by the hyaluronidase enzymes to either oligosaccharides or larger polymer. Despite its simple structure, HA is involved in a great number of biological functions, such as cell proliferation and migration, morphogenesis, wound healing, inflammation, angiogenesis, and tumor growth. Moreover, an important biological role is related to HA oligosaccharides that stimulate cytokine secretion and endothelial cell proliferation. Nevertheless no data about HA presence in endothelium are reported in literature. Several studies underline HA involvement in endothelial cell proliferation, migration, new vessels formation, and leucocytes recruitment. We review the role of HA in endothelial cell in normal condition and during vascular injury.     

Long-lasting modulation of human motor cortex following prolonged transcutaneous electrical nerve stimulation (TENS) of forearm muscles: evidence of reciprocal inhibition and facilitation

Several lines of evidence indicate that motor cortex excitability can be modulated by manipulation of afferent inputs, like peripheral electrical stimulation. Most studies in humans mainly dealt with the effects of prolonged low-frequency peripheral nerve stimulation on motor cortical excitability, despite its being known from animal studies that high-frequency stimulation can also result in changes of the cortical excitability. To investigate the possible effects of high-frequency peripheral stimulation on motor cortical excitability we recorded motor-evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) of the left motor cortex from the right flexor carpi radialis (FCR), extensor carpi radialis (ECR), and first dorsal interosseous (FDI) in normal subjects, before and after transcutaneous electrical nerve stimulation (TENS) of 30 min duration applied over the FCR. The amplitude of MEPs from the FRC was significantly reduced from 10 to 35 min after TENS while the amplitude of MEPs from ECR was increased. No effects were observed in the FDI muscle. Indices of peripheral nerve (M-wave) and spinal cord excitability (H waves) did not change throughout the experiment. Electrical stimulation of the lateral antebrachial cutaneous nerve has no significant effect on motor cortex excitability. These findings suggest that TENS of forearm muscles can induce transient reciprocal inhibitory and facilitatory changes in corticomotoneuronal excitability of forearm flexor and extensor muscles lasting several minutes. These changes probably may occur at cortical site and seem to be mainly dependent on stimulation of muscle afferents. These findings might eventually lead to practical applications in rehabilitation, especially in those syndromes in which the excitatory and inhibitory balance between agonist and antagonist is severely impaired, such as spasticity and dystonia.M. Tinazzi and S. Zarattini contributed equally to the work     

A mutation screening by DHPLC of PSEN1 and APP genes reveals no significant variation associated with the sporadic late-onset form of Alzheimer's disease

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is usually divided into familial and sporadic forms, according to family history. The familial form has often been reportedly caused by mutations in amyloid precursor protein (APP), presenilin-1 (PSEN1), or presenilin-2 (PSEN2) genes, whereas the genetic component for the sporadic form is less clear. We carried out mutation screening in exons 16 and 17 of APP, and in exons 3, 4, 5, 6, 7, 10 of PSEN1 genes in patients with the sporadic late-onset form of AD (LOAD). The aim of this study was to ascertain whether any variation in these genes, besides that of the well-known apolipoprotein E common polymorphism, could be involved in the onset of the disease. To search for the single nucleotide substitutions, we examined 172 LOAD patients by the denaturing high-performance liquid chromatography (DHPLC) technique. Only one same-sense mutation in exon 4 of PSEN1 gene (N32) was observed in this patient group. We concluded that the variation in the screened exons of the APP and PSEN1 genes, reportedly associated with familial AD, is not present in LOAD.     

Defective temporal discrimination of passive movements in Parkinson's disease

Perception of limb position and motion is abnormal in Parkinson's disease (PD). Despite the fact that the processing of proprioceptive inputs is inherently temporal, most studies have assessed spatial aspects of proprioception in PD patients. Here, we use a recently described method to test whether deficits also exist in temporal discrimination of proprioceptive inputs. We induced index finger abduction or wrist flexion through percutaneous electrical stimulation of the motor point of the first dorsal interosseous muscle (FDI) or the flexor carpii radialis (FCR), respectively. Twelve patients with unilateral bradykinetic-rigid PD and 12 healthy subjects were asked to report whether pairs of stimuli separated by different time intervals produced single or double index finger abduction movement or wrist flexion. The shortest interval at which subjects reported two separated movements was considered as temporal movement discrimination threshold. Results showed that thresholds were significantly higher in PD patients than in control subjects for both FCR and FDI muscle, thus demonstrating for the first time that temporal proprioceptive processing is altered in PD.