Kazutaka Shiomi

Clinicopathological features of acute autonomic and sensory neuropathy

Acute autonomic and sensory neuropathy is a rare disorder that has been only anecdotally reported. We characterized the clinical, electrophysiological, pathological and prognostic features of 21 patients with acute autonomic and sensory neuropathy. An antecedent event, mostly an upper respiratory tract or gastrointestinal tract infection, was reported in two-thirds of patients. Profound autonomic failure with various degrees of sensory impairment characterized the neuropathic features in all patients. The initial symptoms were those related to autonomic disturbance or superficial sensory impairment in all patients, while deep sensory impairment accompanied by sensory ataxia subsequently appeared in 12 patients. The severity of sensory ataxia tended to become worse as the duration from the onset to the peak phase of neuropathy became longer (P<0.001). The distribution of sensory manifestations included the proximal regions of the limbs, face, scalp and trunk in most patients. It tended to be asymmetrical and segmental, rather than presenting as a symmetric polyneuropathy. Pain of the involved region was a common and serious symptom. In addition to autonomic and sensory symptoms, coughing episodes, psychiatric symptoms, sleep apnoea and aspiration, pneumonia made it difficult to manage the clinical condition. Nerve conduction studies revealed the reduction of sensory nerve action potentials in patients with sensory ataxia, while it was relatively preserved in patients without sensory ataxia. Magnetic resonance imaging of the spinal cord revealed a high-intensity area in the posterior column on T(2)*-weighted gradient echo image in patients with sensory ataxia but not in those without it. Sural nerve biopsy revealed small-fibre predominant axonal loss without evidence of nerve regeneration. In an autopsy case with impairment of both superficial and deep sensations, we observed severe neuronal cell loss in the thoracic sympathetic and dorsal root ganglia, and Auerbachs plexus with well preserved anterior hone cells. Myelinated fibres in the anterior spinal root were preserved, while those in the posterior spinal root and the posterior column of the spinal cord were depleted. Although recovery of sensory impairment was poor, autonomic dysfunction was ameliorated to some degree within several months in most patients. In conclusion, an immune-mediated mechanism may be associated with acute autonomic and sensory neuropathy. Small neuronal cells in the autonomic and sensory ganglia may be affected in the initial phase, and subsequently, large neuronal cells in the sensory ganglia are damaged.

Identification and characterization of islet amyloid polypeptide in mammalian gastrointestinal tract

We identified and determined the content and molecular form of islet amyloid polypeptide (IAPP/amylin) in the gastrointestinal (GI) tract of human, rat, mouse and cat. IAPP was isolated by anti- IAPP- IgG immunoaffinity chromatography and reverse-phase high performance liquid chromatography coupled with radioimmunoassays for human and rat/mouse IAPPs. Human IAPP [1-37], [17-37] and [24-37] were identified in human stomach with IAPP [1-37] being the major molecular form. In the GI tract of rat, mouse and cat, IAPP [1-37] and IAPP [19-37] were identified with the latter being the major molecular form. IAPP is present from stomach to colon with the highest concentration being observed in pyloric antrum of stomach. IAPP content in rat antrum fell to 69% of control after 4 days of fasting, with the molar ratio of IAPP [19-37] to IAPP [1-37] increasing from 1.4 in controls to 2.9 in fasted rats. Identification of IAPP and characteristic morphology of IAPP- cells in the GI tract indicate a possible biological function of IAPP as a gastrointestinal peptide.

Identification of a novel transthyretin variant (Val30→Leu) associated with familial amyloidotic polyneuropathy

A novel variant transthyretin which contains a leucine‐for‐valine substitution at position 30 was isolated and identified in the serum of a patient with familial amyloidotic polyneuropathy (FAP). The amino acid substitution was proven to result from a guanine‐to‐cytosine change at the first base of codon 30 located in exon 2 in the mutated transthyretin gene by restriction fragment length analysis on the amplified transthyretin gene using Cfr13 I. The study indicates that the point mutation of the transthyretin gene is a cause of the disorder.

Clinical features and neuropathological findings of familial amyotrophic lateral sclerosis with a His46Arg mutation in Cu/Zn superoxide dismutase

We examined the characteristic clinical features of one family of familial amyotrophic lateral sclerosis (FALS) with a His46Arg mutation in the enzyme Cu/Zn superoxide dismutase-1 (SOD1). The disease duration for this family was 18.1 +/- 13.2 (mean +/- S.D.) years, with the age at onset being 39.7 +/- 10.5 years old (mean +/- S.D.). The initial sign was distal weakness of the unilateral lower limb, extending to the lower limb of the other side. A wheel chair became necessary at 9.8 +/- 3.2 years after the onset. Upper limb weakness started at 15.5 +/- 8.9 years following from the onset. An autopsy was performed on a 71-year-old woman of the family with the mutation. Her disease duration was 47 years, and she died of pneumonia. She had no clear upper motor neuron involvement. Bulbar sign and respiratory muscle weakness had developed 2 years before her death. Neuropathological findings showed degeneration of corticospinal tracts, anterior/posterior spinocerebellar tracts, posterior columns, and Clarkes columns. There were few anterior horn cells in the lumbar spinal cord and no Lewy body-like hyaline inclusion bodies in these remaining anterior horn neurons. This is the first autopsy report of FALS with a His46Arg mutation in the SOD1 enzyme.

Ghrelin reverses experimental diabetic neuropathy in mice.

Ghrelin, an acylated peptide produced in the stomach, increases food intake and growth hormone secretion, suppresses inflammation and oxidative stress, and promotes cell survival and proliferation. We investigated the pharmacological potential of ghrelin in the treatment of polyneuropathy in uncontrolled streptozotocin (STZ)-induced diabetes in mice. Ghrelin or desacyl-ghrelin was administered daily for 4 weeks after STZ-induced diabetic polyneuropathy had developed. Ghrelin administration did not alter food intake, body weight gain, blood glucose levels, or plasma insulin levels when compared with mice given saline or desacyl-ghrelin administration. Ghrelin administration ameliorated reductions in motor and sensory nerve conduction velocities in diabetic mice and normalized their temperature sensation and plasma concentrations of 8-isoprostaglandin alpha, an oxidative stress marker. Desacyl-ghrelin failed to have any effect. Ghrelin administration in a mouse model of diabetes ameliorated polyneuropathy. Thus, ghrelins effects represent a novel therapeutic paradigm for the treatment of this otherwise intractable disorder.

Familial amyloidotic polyneuropathy with late-onset and well-preserved autonomic function: a Japanese kindred with novel mutant transthyretin (Ala97 to Gly).

We report the characteristics of one patient and two asymptomatic carriers from a Japanese family with familial amyloidotic polyneuropathy (FAP). The clinical features were somatic sensory and motor neuropathy with well-preserved autonomic function and late onset with slow insidious progression. These symptoms and signs are different from those of type 1 FAP. There were massive amyloid deposits with transthyretin (TTR) in the myocardium and the sural nerve. DNA sequencing of the TTR gene and amino acid sequence analysis of serum TTR revealed a new mutation in which Gly97 was substituted for Ala. We suggest that patients with somatic sensory and motor neuropathy of unknown origin without apparent autonomic dysfunction should be further studied for TTR mutation.

Molecular forms of islet amyloid polypeptide (IAPP/amylin) in four mammals

Using reverse-phase high performance liquid chromatography combined with radioimmunoassays for human and rat/mouse islet amyloid polypeptide (IAPP), we identified molecular forms of IAPPs in pancreata of four mammals including species in which islet amyloid deposition occurs (human and cat) and those in which amyloid deposition does not occur (rat and mouse). In human pancreas, IAPP (1-37) was the major molecular form, and IAPP (17-37), IAPP (24-37) and four IAPP-immunoreactive peptides were detected as minor components. In rat, mouse and cat pancreata, IAPP (1-37) and IAPP (19-37) were identified with the latter being the major molecular form. Major processing takes place at a single arginine residue at position 18 of rat/mouse and cat IAPPs, but not at the histidine at position 18 of human IAPP, indicating that arginine could yield different processing of IAPP between the 3 species and human. Different processing of IAPP by species suggests that processing of IAPP in pancreas is not responsible for islet amyloid formation. Identification of molecular forms of IAPP is helpful in elucidating the physiological function of the IAPP molecule and in determining the type of system regulating biosynthesis and catabolism of the peptide.

Establishment of hypersensitive radioimmunoassay for islet amyloid polypeptide using antiserum specific for its N-terminal region

Using a synthetic N-terminal hexadecapeptide of islet amyloid polypeptide (IAPP), we prepared an antiserum specific for IAPP[1-16] and established an extremely sensitive radioimmunoassay (RIA) for the peptide with a minimum detection level of 0.26 fmol/tube. Since the N-terminal sequence of IAPP is 100% conserved in many mammalian species, the RIA is widely applicable in quantifying their IAPP. Analyses of pancreatic extracts of human and hamster using reverse-phase high performance liquid chromatography coupled with the RIA revealed that almost all pancreatic IAPP consisted of IAPP[1-37]. On the other hand, rat and mouse pancreata contained substantial amounts of IAPP[1-16] and IAPP[1-17] in addition to IAPP[1-37] as a major molecular form. In human plasma, IAPP[1-37] is the major molecular form secreted into the circulation in response to glucose administration. The RIA established in this study is promising in elucidating the physiological functions and the pathophysiological significance of IAPP in diabetes mellitus.

Ghrelin prevents the development of experimental diabetic neuropathy in rodents

Ghrelin is an acylated peptide discovered in gastric extracts as an endogenous ligand for the growth hormone secretagogue (GHS) receptor. This peptide increases food intake and growth hormone secretion, suppresses inflammation and oxidative stress, and promotes cell survival and proliferation. Our study investigated the pharmacological effect of ghrelin in the prevention of polyneuropathy in streptozotocin-induced diabetes mellitus in C57BL/6N mice, GHS receptor-deficient mice, and growth hormone-deficient rats. Ghrelin or desacyl-ghrelin was administered daily for four weeks immediately after disease onset. The effects of ghrelin on food intake, body weight, blood glucose and plasma insulin levels, nerve conduction velocities, temperature sensation, and 8-isoprostaglandin F2α (8-iso-PGF2α) levels were examined. We found that ghrelin administration did not change food intake, body weight gain, blood glucose levels, or plasma insulin levels in C57BL/6N mice in comparison with mice treated with saline or desacyl-ghrelin administration. Ghrelin administration, but not desacyl-ghrelin, prevented motor and sensory polyneuropathy and reduced the plasma concentrations of 8-iso-PGF2α in C57BL/6N mice. Ghrelin also prevented the reduction in nerve conduction velocities in growth hormone-deficient rats, but not in GHS receptor-knockout mice. In conclusion, ghrelin administration in a rodent model of diabetes prevented polyneuropathy, and this effect was mediated through the GHS receptor and was independent of growth hormone. The protection against the development of experimental diabetic polyneuropathy by ghrelin could be key in preventing this otherwise intractable disorder.

Isolation and sequence determination of two N-terminal fragments of islet amyloid polypeptide in rat pancreas

Using a highly sensitive and specific radioimmunoassay (RIA) for the N-terminal hexadecapeptide of islet amyloid polypeptide (IAPP), we isolated two N-terminal fragments of IAPP from rat pancreas. They were identified as IAPP(1-16) and IAPP(1-17) by amino acid sequencing. The two fragments were also found in rat plasma. IAPP(1-37) was the major molecular form of rat IAPP, IAPP(1-16) and IAPP(1-17) accounting for 6.0% and 32.3% of the immunoreactivity for the N-terminal region of the peptide in pancreata of normally fed rats. In human pancreas, the N-terminal fragments of IAPP were not present, indicating that the processing of IAPP in the pancreas differs between human and rat. Food deprivation increased the molar ratios of IAPP(1-16) and IAPP(1-17) to IAPP(1-37) in comparison to values for fed rats. Identification of novel fragments of IAPP, in addition to IAPP(1-37), offers a promise for the elucidation of the physiological function of IAPP and the identification of factors that regulate the biosynthesis and catabolism of the peptide.