The Glucuronyltransferase GlcAT-P Is Required for Stretch Growth of Peripheral Nerves in Drosophila

During development, the growth of the animal body is accompanied by a concomitant elongation of the peripheral nerves, which requires the elongation of integrated nerve fibers and the axons projecting therein. Although this process is of fundamental importance to almost all organisms of the animal kingdom, very little is known about the mechanisms regulating this process. Here, we describe the identification and characterization of novel mutant alleles of GlcAT-P, the Drosophila ortholog of the mammalian glucuronyltransferase b3gat1. GlcAT-P mutants reveal shorter larval peripheral nerves and an elongated ventral nerve cord (VNC). We show that GlcAT-P is expressed in a subset of neurons in the central brain hemispheres, in some motoneurons of the ventral nerve cord as well as in central and peripheral nerve glia. We demonstrate that in GlcAT-P mutants the VNC is under tension of shorter peripheral nerves suggesting that the VNC elongates as a consequence of tension imparted by retarded peripheral nerve growth during larval development. We also provide evidence that for growth of peripheral nerve fibers GlcAT-P is critically required in hemocytes; however, glial cells are also important in this process. The glial specific repo gene acts as a modifier of GlcAT-P and loss or reduction of repo function in a GlcAT-P mutant background enhances VNC elongation. We propose a model in which hemocytes are required for aspects of glial cell biology which in turn affects the elongation of peripheral nerves during larval development. Our data also identifies GlcAT-P as a first candidate gene involved in growth of integrated peripheral nerves and therefore establishes Drosophila as an amenable in-vivo model system to study this process at the cellular and molecular level in more detail

The role of sulfoglucuronosyl glycosphingolipids in the pathogenesis of monoclonal IgM paraproteinemia and peripheral neuropathy

In IgM paraproteinemia and peripheral neuropathy, IgM M-protein secretion by B cells leads to a T helper cell response, suggesting that it is antibody-mediated autoimmune disease involving carbohydrate epitopes in myelin sheaths. An immune response against sulfoglucuronosyl glycosphingolipids (SGGLs) is presumed to participate in demyelination or axonal degeneration in the peripheral nervous system (PNS). SGGLs contain a 3-sulfoglucuronic acid residue that interacts with anti-myelin-associated glycoprotein (MAG) and the monoclonal antibody anti-HNK-1. Immunization of animals with sulfoglucuronosyl paragloboside (SGPG) induced anti-SGPG antibodies and sensory neuropathy, which closely resembles the human disease. These animal models might help to understand the disease mechanism and lead to more specific therapeutic strategies. In an in vitro study, destruction or malfunction of the blood-nerve barrier (BNB) was found, resulting in the leakage of circulating antibodies into the PNS parenchyma, which may be considered as the initial key step for development of disease

Characteristics and Surgical Treatment of Dolichoectatic and Fusiform Aneurysms

Dolichoectatic and fusiform aneurysms represent a small subset of cerebral aneurysms and are often among the most difficult to treat. A consecutive series of 40 patients with 41 of these two types of aneurysms is presented, including their clinical characteristics and surgical treatments. Common to all aneurysms was the pathological involvement of a length of blood vessel with separate inflow and outflow sites (nonsaccular). However, dolichoectatic aneurysms have markedly different symptoms and surgical treatments dependent on their location in either the anterior or posterior circulation. Anterior circulation aneurysms involved the petrous internal carotid artery (ICA) in one, the supraclinoid ICA in three, the middle cerebral artery in 13, and the anterior cerebral artery in four patients. Posterior circulation aneurysms involved the basilar artery in 13, the vertebral artery in six, and the posterior inferior cerebellar artery in one patient. Various surgical procedures were performed, including direct clipping, trapping with bypass, proximal occlusion, resection with reanastomosis, transposition, aneurysmorrhaphy with thrombectomy, and wrapping. There was no surgical mortality in the patient series, and treatment was effective in many patients. Overall, outcome at late follow up was good (Glasgow Outcome Scale scores 1-2) in 78% of patients. Patients with anterior circulation aneurysms had better outcomes than patients with posterior circulation aneurysms, with good outcomes in 90% and 65% of the cases, respectively. Dolichoectatic and giant serpentine aneurysms may develop from smaller fusiform aneurysms and represent a spectrum of the same pathological entity. Arterial dissection may also play a role in the initial development of these aneurysms

Clinical phenotype of patients with neuropathy associated with monoclonal gammopathy: a comparative study and a review of the literature

The objective of this study was to investigate if the clinical and electrophysiological phenotype of patients with polyneuropathy associated with IgM monoclonal gammopathy (IgM-PNP) is related to the presence of antibodies against gangliosides or myelin-associated glycoprotein (MAG). We compared clinical and nerve conduction study (NCS) characteristics of 11 IgM-PNP patients with antibodies against asialo-GM1 or gangliosides (GM1, GD1a, GD1b, GM2 or GQ1b) to 11 consecutive IgM-PNP patients with anti-MAG neuropathy and to 9 IgM-PNP patients without antibodies against either MAG or gangliosides. Patients with anti-ganglioside antibodies could not be differentiated from those with anti-MAG antibodies based on clinical characteristics. However, within the group of anti-ganglioside antibody positive patients, antibodies against GD1b and GQ1b were associated with a purely sensory neuropathy (p = 0.002), while asymmetric weakness with symmetric sensory loss was associated with anti-asialo-GM1 antibodies. In conclusion, polyneuropathy associated with IgM monoclonal gammopathy and anti-ganglioside antibodies clinically resembles anti-MAG neuropathy. Pure sensory neuropathy and marked asymmetry may suggest the presence of anti-ganglioside rather than anti-MAG antibodies