Takeshi Yasuda

Expression of mRNAs for neurotrophins (NGF, BDNF, and NT-3) and their receptors (p75NGFR, trk, trkB, and trkC) in human peripheral neuropathies.

The steady-state mRNA levels of NGF, BDNF and NT-3, and the mRNA levels of their receptors p75NGFR, trk, trk,B and trkC were examined in various human peripheral neuropathies, to determine the correlation with myelinated fiber pathology and T cell and macrophage invasions in the diseased nerves. Steady state levels of p75NGFR mRNAs were significantly elevated in nerves with axonal pathology. In contrast, steady state levels of trkB and trkC mRNA levels were diminished, trk mRNA was not detected in the human nerves. The NGF, BDNF, and NT-3 mRNA levels were elevated in the diseased nerves. The increase in BDNF and NT-3 mRNA levels were proportional to the extent of invasion of the nerves by T cells and macrophages, but did not directly correlate with axonal nor demyelinating pathology, thus suggesting that inflammatory cell invasions are involved in the regulation of BDNF and NT-3 mRNA expressions. These neurotrophin and their receptor gene expressions in the diseased human nerves would be regulated by an underlying pathology-related process, and could play a role in peripheral nerve repair.

Immunohistochemical study of advanced glycation end products in aging and Alzheimer's disease brain

Advanced glycation end products (AGEs) in the brain were immunohistochemically examined in Alzheimers disease (AD) and aging using anti-AGE antibody recognizing mainly carboxymethyllysine. AGE positive staining diffusely located in the neuronal perikarya of hippocampus and parahippocampus in AD and aged brains without dementia, but not in young brains less than 17 years of age. Extra-neuroperikaryal AGE deposits were also detected in the neuropil of AD and aged brains. The extra-neuroperikaryal AGE deposits markedly increased in AD brains as compared to aged brains. These AGE-positive deposits in the neuropil were not related to the senile plaque identified by anti-beta amyloid protein antibody. These findings suggest a potential link of AGE accumulation in the central nervous system to the aging process of neurons and the degenerating process of AD neurons.

Advanced glycation end products co-localized with astrocytes and microglial cells in Alzheimer's disease brain

Abstractu2002u2002 In the previous study [Takeda et al. (1996) Neurosci Lett 221: 17–21], we reported that the advanced glycation end products (AGEs) in the external space of neuronal perikarya (extraneuroperikaryal AGE deposits) were significantly abundant in the Alzheimer’s brain. In this study, we investigated the spatial relationship of the extraneuroperikaryal AGE (carbocymethyllysine and pentosidine) deposits in astrocytes and microglial cells in the Alzheimer’s disease brain using double immunolabelling for AGEs and astrocyte or microglial cell markers. Most of the extraneuroperikaryal AGE deposits were co-localized with glial fibrillary acidic protein-positive astrocytes. AGE deposit-bearing astrocytes also contained Gomori-positive granules. Furthermore, some of the extraneuroperikaryal AGE deposits were co-localized with microglial cells. These extraneuroperikaryal AGEs may activate astrocyte and microglia, and play a role in pathogenesis of Alzheimer’s disease.

Clinicopathological features of chronic inflammatory demyelinating polyradiculoneuropathy in childhood

The clinical, electrophysiological, and pathological findings, and the therapeutic characteristics in ten children with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), whose onset age was less than 16 years, were evaluated. The clinical progression pattern of the initial phase divided the patients into two groups. One group (six patients) showed a subacute progression for up to 2 months after onset and a subsided progression over 3 months. Three patients in this group had a preceding febrile episode. The other group (four patients) showed a chronic insidious progression for more than 3 months. The former group of patients revealed a favourable response to corticosteroid therapy as compared with the latter group. However, other clinical and laboratory features at the peak impairment were not distinguishable between these two groups. Motor dominant neuropathy was common to all patients, and only three cases showed sensory disturbance on the distal limbs. No cases revealed cranial nerve involvement. Motor and sensory nerve conduction and sural nerve biopsy studies revealed the demyelinating nature of the neuropathy. These clinicopathological features suggest that the subacute progression form frequently associated with prodromal episode and rather favourable corticosteroid response is characteristic in childhood CIDP, while the chronic insidious progression form is indistinguishable from the common adult CIDP.

Neuronal and glial advanced glycation end product [Nε-(carboxymethyl)lysine] in Alzheimer's disease brains

Abstract. The cellular distribution of an advanced glycation end product [Nε-(carboxymethyl)lysine (CML)] in aged and Alzheimers disease (AD) brains was assessed immunohistochemically. CML was localized in the cytoplasm of neurons, astrocytes, and microglia in both aged and AD brains. Glial deposition was far more marked in AD brains than in aged brains, and neuronal deposition was also increased. On electron microscopic immunohistochemistry, neuronal CML formed granular or linear deposits associated with lipofuscin, and glial deposits formed lines around the vacuoles. Neuronal and glial deposits were prominent throughout the cerebral cortex and hippocampus, but were sparse in the putamen, globus pallidus, substantia nigra, and cerebellum, with glial deposits being far more prominent in AD brains. The distribution of neuronal and glial deposits did not correspond with the distribution of AD pathology. The extent of CML deposits was inversely correlated with neurofibrillary tangle formation, particularly in the hippocampus. Most hippocampal pyramidal neurons with neurofibrillary tangles did not have CML, and most of the neurons with heavy CML deposits did not have neurofibrillary tangles. In the hippocampus, neuronal CML was prominent in the region where neuronal loss was mild. These observations suggest that CML deposition does not directly cause neurofibrillary tangle formation or neuronal loss in AD.

Locations of crossover breakpoints within the CMT1A-REP repeat in Japanese patients with CMT1A and HNPP

Abstract The crossover breakpoints for Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP) are located in the CMT1A-REP repeat flanking a 1.5-Mb region of chromosome 17p11.2–12. The precise locations of the breakpoints are heterogeneous, and we analyzed the relative frequency distribution of breakpoints in 33 unrelated Japanese CMT1A and 3 unrelated HNPP families. The CMT1A-REP repeat region was divided into five regions, A, B, C, D and E, based on restriction site differences between the proximal and distal CMT1A-REP repeats. The frequency distribution of breakpoints within the CMT1A-REP repeat in the Japanese patients was 3% in region A, 78% in B/C and 19% in D, which is similar to that in Caucasian patients. This result also indicates that an 8-kb region defined by region B/C is a recombinational hotspot within the CMT1A-REP repeat in Japanese patients.

Clustering of CMT1A duplication breakpoints in a 700 bp interval of the CMT1A-REP repeat

The CMT1A‐REP repeat is proposed to mediate unequal crossover leading to a 1.5 Mb duplication in chromosome 17p11.2‐12 associated with Charcot‐Marie‐Tooth neuropathy type 1A (CMT1A). There is an apparent recombinational “hotspot” in the CMT1A‐REP repeat since the majority of crossover breakpoints for CMT1A are located within a 1.7 kb interval. Further to characterize the crossover breakpoint region, we constructed PCR primers that specifically amplify the duplication breakpoint junctions in a series of Japanese and Caucasian CMT1A patients. We mapped the breakpoints in 89% of patients within a 700 bp interval of the CMT1A‐REP repeat. This 700 bp region is 1.3 kb telomeric to a previously described mariner‐like transposable element. Our observations further define the location of crossovers for CMT1A and provide additional evidence that this region is a recombinational “hotspot” within the CMT1A‐REP repeat. Hum Mutat 11:109–113, 1998.

Peptidergic and adrenergic regulation of the intracellular 3′,5′-cyclic adenosine monophosphate content in cultured rat Schwann cells

We investigated the role of neuropeptides and adrenergic agonists in the regulation of intracellular 3,5-cyclic adenosine monophosphate (cyclic AMP) contents in cultured Schwann cells from sciatic nerve of neonatal Sprague-Dawley rats. Of the neuropeptides examined, vasoactive intestinal polypeptide (VIP) and secretin markedly stimulated the accumulation of intracellular cyclic AMP in a time- and dose-dependent manner with half maximum at 3 and 12 min, and 2.8 X 10(-5) and 5.0 X 10(-5) M, respectively. While somatostatin, substance P, adrenocorticotropin (ACTH), beta-endorphin, and nerve growth factor (NGF) did not show any effect on cyclic AMP metabolism, isoproterenol (IP), norepinephrine (NE) and epinephrine (E) also markedly elevated the Schwann cell cyclic AMP concentration. The rank-order of potency of these adrenergic catecholamines on cyclic AMP accumulation was isoproterenol greater than norepinephrine greater than epinephrine. Simultaneous addition of VIP or secretin to the Schwann cell culture synergistically enhanced the norepinephrine-induced elevation of intracellular cyclic AMP. The effect of norepinephrine was antagonized by a selective beta 1-adrenergic antagonist but not by beta 2- nor alpha-adrenergic antagonists. These results suggest that VIP, secretin, and beta 1-adrenergic agonists alone or synergistically may play a part in the regulation of metabolism of Schwann cells mediated through a cyclic AMP-dependent mechanism.

Gangliosides modulate Schwann cell proliferation and morphology

We examined the effect of gangliosides on Schwann cell cultures isolated from neonatal rat sciatic nerves. Addition of gangliosides (GM1, GM3, and ganglioside mixture) at concentrations between 0.25 and 2 mg/ml significantly diminished both the baseline rate of proliferation of the Schwann cells and their response to two types of mitogens, the axolemmal fragments and derivatives of adenosine 3-5-monophosphate (cAMP). Gangliosides, the sialic acid residue of which had been removed, were highly toxic to the Schwann cells, which went to indicate that sialic acid is necessary to produce the inhibitory effects. Gangliosides also produced prominent changes in the morphological appearance of the Schwann cells. Most of the Schwann cells treated with gangliosides had an elongated shape with long processes and an alignment of end-to-end or side-by-side cell adhesion. These effects of gangliosides apparently were not mediated by cAMP, since intracellular cyclic adenosine monophosphate (cAMP) of Schwann cells at a basal- and forskolin-stimulated level was not altered by the exogenous gangliosides. These findings indicate that the direct effect of gangliosides on Schwann cells should also be considered as a background mechanism of ganglioside-induced facilitation of neuronal regeneration.

Low uptake of [3H]2-deoxy-D-glucose by cultured rat Schwann cells.

[3H]2-Deoxy-D-glucose (2-DG) was used to investigate the glucose uptake in cultured rat Schwann cells from postnatal Sprague-Dawley rat sciatic nerves. The glucose uptake of Schwann cells slightly increased in a time- and dose-dependent manner. However, the maximal uptake level was much lower than that of ethylnitrosourea (ENU)-induced transformed rat schwannoma-like cells and fibroblasts. By autoradiography of the cultured system, we were able to visualize the accumulation of [3H]2-DG grains in the schwannoma-like cells and fibroblasts, but not in Schwann cells.