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T Saitoh

Publications and source records attributed to T Saitoh.

At least 19 recordsLinked to original sources
PubMed1992

An endosomal-lysosomal pathway for degradation of amyloid precursor protein.

We previously reported evidence for a lysosomal degradative pathway for APP and C-terminal fragments thereof, based on Western and immunocytochemical analysis of drug-treated cells. Here, we verify the existence of a lysosomal degradative pathway for APP using pulse chase immunoprecipitation analysis of drug-treated cells and fibroblasts with and without a known lysosomal hydrolase targeting defect. The results are consistent with the hypothesis that part or all of the beta-protein domain of APP is normally degraded by lysosomes. A mechanism for beta-protein deposition based on this data is hypothesized.

Amyloid beta-Protein Precursor↗
PubMed1992

Amyloid precursor protein is localized in growing neurites of neonatal rat brain.

Previous studies have indicated that amyloid precursor protein (APP) might be a trophic agent in the nervous system, possibly through the regulation of cell adhesion and the protease/protease inhibitor activity. Additionally, APP is upregulated during the development of the nervous system. In order to further study the role of APP in neuritic outgrowth, we examined the patterns of distribution of APP in the immature neonatal rat brain (P1). Laser-scanning confocal imaging of double-immunolabeled sections showed that a subpopulation of the anti-GAP43-immunoreactive outgrowing neurites contained APP immunoreactivity in the neocortex and hippocampus. These fine, long neuritic processes were also positive with antibodies against phosphorylated neurofilaments and were glial fibrillary acidic protein (GFAP) negative. In addition, anti-APP strongly immunolabeled neurons in the inner cortical layers, while GAP43 strongly immunolabeled the neuropil surrounding them. These observations are consistent with a previous study where APP was localized to aberrant sprouting neurites and suggest a possible role for APP in neuritic outgrowth in plaques of patients with Alzheimer's disease (AD), which might explain the abnormal neuritic response found in AD.

Amyloid beta-Protein Precursor↗
PubMed1992

The involvement of protein kinase C in activation-induced cell death in T-cell hybridoma.

T-cell hybridoma activated by a variety of stimuli such as anti-cell surface antigen, notably CD3 and T-cell receptors, and Con A undergoes a cell lysis process called activation-induced cell death (AICD). It was found that the major protein kinase C (PKC) isoform in the 2B4.11 T-cell hybridoma, PKC(alpha), was translocated from the cytosolic to the particulate fraction when these hybridoma cells were induced to die by plastic-adsorbed anti-CD3 antibodies. Inhibitors of protein phosphorylation rescued 2B4.11 cells from AICD as determined by the analysis of cellular metabolism and the proportion of living cells. Furthermore, PKC(alpha) down-regulation by phorbol ester treatment abolished AICD, and the degree of PKC down-regulation correlated well with the degree of AICD abolishment, suggesting that PKC activation represents an essential step in the molecular mechanisms underlying AICD in this T-cell hybridoma.

Alkaloids↗
PubMed1992

Localization of amyloid precursor protein in GAP43-immunoreactive aberrant sprouting neurites in Alzheimer's disease.

Previous in vitro studies have suggested that amyloid precursor protein (APP) could be involved in cell surface adhesion, neuritic growth and survival of hippocampal neurons. In the present study, involvement of APP in aberrant sprouting in Alzheimer's disease (AD) was studied by comparing immunolabeling patterns of anti-APP and anti-growth-associated protein 43 (anti-GAP43). Confocal laser imaging of frontal cortex sections double-immunolabeled for APP and GAP43 showed an increase, in AD, of presynaptic boutons immunostained with anti-GAP43 that contained anti-APP immunoreactivity. The neuritic plaques in AD cases presented intense anti-GAP43 immunoreactive abnormal neurites colocalized with anti-APP. Three-dimensional reconstruction of the plaques showed that anti-APP was colocalized with anti-GAP43 in 57.5% of the aberrant sprouting neurites. We conclude that co-expression of APP with GAP43 in the plaque might be involved in the aberrant sprouting response observed in AD.

Aged↗
PubMed1992

Casein kinase II is associated with neurofibrillary tangles but is not an intrinsic component of paired helical filaments.

Neurofibrillary tangles (NFT) are pathological cytoskeletal structures composed of paired helical filaments (PHF), and are found in neurons of patients afflicted with many neurodegenerative disorders, including Alzheimer's disease (AD). We previously found that an antiserum against casein kinase II (CK-II) stained NFT intensely in the brain tissue of AD patients. In the current study, we found that the anti-CK-II antiserum stains NFT and neuronal inclusions in many other neurodegenerative diseases as well, including Guam-Parkinson dementia complex, chromosome 18 deletion syndrome, progressive supranuclear palsy, Kufs' disease, and Pick's disease. This antiserum reacted, in crude brain homogenates, with both a doublet of Mr 43,000 and a Mr 27,000 Da protein which could correspond to the alpha, alpha', and beta chains of CK-II. The staining of these bands was adsorbed by preincubating anti-CK-II antiserum with purified CK-II. Preincubation of brain sections with purified CK-II strongly intensified the immunostaining of NFT with anti-CK-II, suggesting that NFT may bind CK-II. In the AD brain homogenates, the particulate CK-II levels are increased whereas the cytosolic levels are decreased without a change in total CK-II levels, consistent with the idea that CK-II binds to the particulate PHF, a major constituent of NFT. In accord with these findings, purified PHF bound CK-II, but purified PHF did not contain CK-II as its component. These results suggest that CK-II might be an extraneously deposited component of NFT. Thus, the altered CK-II compartmentalization might have significant consequences in the pathogenesis of AD.

Brain↗
PubMed1992

Bacterial expression, purification, and functional mapping of the amyloid beta/A4 protein precursor.

The secreted form of Alzheimer amyloid beta/A4 protein precursor (APP) has been shown to be involved in cell growth regulation (Saitoh, T., Sundsmo, M., Roch, J.-M., Kimura, N., Cole, G., Schubert, D., Oltersdorf, T., and Schenk, D.B. (1989) Cell 58, 615-622). Using a strong prokaryotic expression system, we expressed, in Escherichia coli, peptide fragments covering different regions of the secreted form of APP-695. The longest of these fragments (KB75, 572 amino acids from Val-20 to Ile-591), which contained neither the Kunitz-type protease inhibitor (KPI) domain nor the amyloid beta/A4-protein domain, was purified and shown to be biologically active in terms of growth regulation. Two other APP fragments (KB48, 316 amino acids from Val-20 to Met-335; and RB17, 150 amino acids from Thr-296 to Pro-445), overlapping by only 40 amino acids at a close site C-terminal to the KPI insertion site, were also active. Furthermore, a chemically synthesized 40-residue peptide corresponding to this region of overlap also stimulated the growth of A-1 fibroblasts. These results establish the presence of growth-promoting activity in the secreted form of APP-695 and suggest that the site of this activity of APP-695 lies within a 40-amino acid domain next to the KPI insertion site.

Amino Acid Sequence↗
PubMed1992

Serological alpha 1-antichymotrypsin in Down's syndrome and Alzheimer's disease.

alpha 1-Antichymotrypsin (ACT) is a serine protease inhibitor that is markedly elevated in the serum and cerebrospinal fluid of patients with Alzheimer's disease (AD). Patients with Down's syndrome are known to develop neuropathological changes of AD by age 40 years and many become demented. Therefore, in the present study, we obtained serum ACT levels from patients with Down's syndrome and AD, diagnosed by autopsy or clinically, and healthy control subjects. Newman-Keuls' multiple range test revealed a significantly greater (p less than 0.01) mean ACT level in the Autopsy AD (906.4 +/- 94.64 mg/L) and Clinical AD (745.00 +/- 59.95 mg/L) groups in contrast to the Old Control group (531.00 +/- 23.05 mg/L). The mean ACT level of the Down's Syndrome group (513.33 +/- 14.73 mg/L) was not significantly different from that of the Young Control subjects. Furthermore, we did not observe a positive correlation of ACT levels with age in the Down's Syndrome group, in spite of the age-dependent premature increase in neuropathological changes of AD that are known to occur in patients with Down's syndrome. A positive correlation between serum ACT levels and the density of plaques or tangles, neuropathological hallmarks of AD, in brains of patients with AD also did not exist. Thus, our results suggest that ACT levels may not parallel the development of the classical neuropathological hallmarks of AD.

Adult↗
PubMed1992

Localization of protein kinase C in human skeletal muscle.

The immunolocalization of protein kinase C (PKC) isozymes alpha, beta I and beta II, was investigated in human skeletal muscle. All three isozymes were present on the muscle fiber surface membrane and within the muscle fibers. The alpha-isozyme was most clearly delineated on the surface membrane of the muscle fiber and on small blood vessels in the connective tissue. The axons of myelinated intramuscular nerves stained intensely for the beta I isozyme, whereas the endoneurial connective tissue reacted more strongly for the alpha- and beta II-isozymes. PKC isozymes may regulate intracellular signal transduction in human skeletal muscle, as in the other tissues, but their exact role in muscle remains unknown.

Adult↗
PubMed1992

The role of alterations in free radical metabolism in mediating cognitive impairments in Down's syndrome.

Down's syndrome (DS) is a genetic disorder involving an excess of chromosome 21 (trisomy 21) in approximately 96% of the cases and comprises approximately 15% of the population with mental retardation (Heller, 1969). In addition to the constitutional mental deficiencies associated with the syndrome many DS patients develop dementia associated with Alzheimer's disease (AD) in their later years of life (Thase et al., 1984). The genetic locus for Cu,Zn-superoxide dismutase (SOD1), a key enzyme in free radical metabolism, is located on chromosome 21, and the activity level of this enzyme is elevated by approximately 50% in a variety of cells of DS patients (see Kedziora and Bartosz, 1988; Sinet, 1982). Because alterations in free radical metabolism may be involved in neuronal death and may be associated with a number of pathological manifestations of DS, it is important to understand the role of free radical metabolism in cognitive impairments of DS, the topic discussed in this chapter.

Aging↗
PubMed1992

Reverse flow in the intracranial arteries--the possible significance of comparative flow in the anterior cerebral and the basilar arteries.

Four infants with reverse flow patterns of the intracranial arteries are reported. Two with severe brain damage, had a reverse flow pattern in the anterior cerebral artery, which was recorded during the recovery stage from cardiac arrest. The other two patients showed a reverse flow pattern in the basilar artery and had a good prognosis. Reverse flow in the anterior cerebral artery suggests severe brain damage, but that in the basilar artery does not.

Basilar Artery↗
PubMed1992

Morphological characteristics of a transplantable nephroblastoma (NB-Y) in F344 rats and the relation of tumour growth to hyper-reninaemia in NB-Y-bearing rats.

A transplantable tumour, designated NB-Y, was established from a spontaneous nephroblastoma in an F344 rat. NB-Y was serially passaged in syngeneic rats by subcutaneous implantation up to the 49th generation. The transplants grew into nodules with an average diameter of 5 cm and average weight of 92.9 g 4 weeks after implantation. The primary tumour and NB-Y consisted mainly of sheets or clusters of undifferentiated blastemal cells, which reacted immunohistochemically for vimentin but not for keratin. Renin-containing cells were observed in the small blood vessel walls within the primary tumour, but neoplastic cells of both primary tumour and NB-Y failed to stain for renin. Plasma renin activity was significantly higher (40.7 ng per ml per h) in transplanted rats 4 weeks after implantation compared with non-transplanted controls (28.0 ng per ml per h). Hyperplastic juxtaglomerular cells were often observed in rats bearing NB-Y. Sinusoidal dilatation was present in the liver, adrenal glands, pituitary gland and bone marrow of recipients, suggesting abnormal blood flow provoked via the renin-angiotensin system. The present study revealed the development of hyper-reninaemia in NB-Y-bearing rats, but its pathogenesis remains unknown.

Anemia↗
PubMed1992

Alpha 2-adrenergic modulation of pancreatic glucagon secretion in rats.

The present study was designed to clarify the mechanism of adrenergic modulation of pancreatic glucagon secretion in rats under physiological conditions by 1) epinephrine infusion alone or together with adrenergic blockers and 2) administration of adrenergic agonists. Intravenous infusion of epinephrine alone (1 microgram/kg/min, equal to 0.7 nmol/kg/min) caused a significant increase in glucagon secretion. Phentolamine (an alpha blocker) or yohimbine (an alpha 2 blocker) administration completely inhibited the increase of glucagon secretion caused by epinephrine infusion, but neither the administration of bunazosin (an alpha 1 blocker) nor beta blockers inhibited it. Infusion of clonidine (an alpha 2 agonist) caused significant increase of glucagon secretion even at a low dose of 0.5 nmol/kg/min, although infusion of neither an alpha 1 nor a beta 2 agonist caused it even at the high dose of 40.0 nmol/kg/min. It is concluded that the alpha 2 receptor mechanism plays the most important role in the adrenergic modulation of glucagon secretion in rats under physiological conditions.

Adrenergic alpha-Agonists↗
PubMed1992

Balloon cystoscopy with neodymium:YAG laser.

We performed balloon cystoscopy for the diagnosis of gross hematuria as well as for the treatment of bladder tumor using the neodymium:YAG laser. Animal experiments were done to evaluate the efficacy of laser irradiation through the balloon, which proved to have the same effect as conventional laser irradiation. A total of 40 patients with bladder diseases was observed and treated by balloon cystoscopy, and the results were examined comparatively. Even with gross hematuria the structure of the mucosa and the tumor could be observed in detail without irrigating the inside of the bladder. Most bladder tumors were successfully treated with laser irradiation through the balloon through the optic lens system. Therefore, balloon cystoscopy appears to be a useful endoscopic modality in neodymium:YAG laser surgery for the treatment of bladder tumor.

Animals↗
PubMed1992

Simultaneous measurements of adenosine deaminase activity and tuberculostearic acid in pleural effusions for the diagnosis of tuberculous pleuritis.

Adenosine deaminase (ADA) activity and tuberculostearic acid (TSA) levels in pleural effusions were measured in 18 patients with active tuberculous pleuritis, 16 patients suspected of having tuberculous pleuritis, 14 patients with carcinomatous pleuritis, and 19 patients suffering from pleuritis of non-malignant and non-tuberculous etiology. In the patients with active tuberculous pleuritis, ADA was elevated in 56% and TSA was positive in 78%. In 83% of these patients, either ADA was elevated or TSA was positive. ADA was elevated together with a positive TSA in 50%. In contrast, TSA was positive in only 6% and ADA was elevated in 24% of the patients with non-tuberculous pleuritis, and none of these patients showed the combination of an elevation of ADA and a positive TSA. These results suggest that simultaneous measurements of both ADA and TSA in pleural effusions are useful for the diagnosis of tuberculous pleuritis.

Adenosine Deaminase↗
PubMed1992

Islet amyloid polypeptide/amylin in pancreatic beta-cell line derived from transgenic mouse insulinoma.

We examined the production and secretion of IAPP in a beta-cell line, MIN6, which is derived from an insulinoma obtained by targeted expression of the SV40 T-antigen gene in a transgenic mouse. RNA blot analysis revealed an abundance of IAPP and insulin II mRNA in the cells, findings comparable with those in the pancreas of a normal mouse. The presence of IAPP and insulin was confirmed immunohistochemically and by RIA. Analysis of the reverse-phase HPLC identified IAPP in cells with authentic mouse IAPP. Raising the glucose concentration from 5.6 to 25 mM failed to induce increments in IAPP and insulin II mRNAs. The cells secrete IAPP and insulin for short- and long-term incubations in response to concentration of glucose in the medium. These features resemble those of islet cells from normal animals. This beta-cell line will aid in analyzing the regulation of IAPP gene expression and the mechanisms of IAPP biosynthesis and secretion.

Amyloid↗
PubMed1992

Histological characteristics of lupus nephritis in F1 mice with chronic graft-versus-host reaction across MHC class II difference.

Renal lesions at the chronic phase of MHC class-II-disparate graft-versus-host reaction (GVHR) were examined. To induce GVHR, C57BL/6 (B6) spleen cells were injected twice into either (B6 x bm12)F1 (class-II-disparate), (B6 x bm1)F1 (class-I-disparate) or (bm1 x bm12)F1 mice (class-I + II-disparate). For comparison, (C57BL/10 x DBA/2)F1 (BDF1) mice injected with DBA/2 spleen cells were also used. (B6 x bm12)F1 and BDF1 recipients showed marked elevation of anti-DNA antibodies, circulating immune complexes (CIC) and the number of immunoglobulin producing cells (IgPC). At 20 weeks after cell injection, severe immune complex glomerulonephritis (ICGN) was observed in (B6 x bm12)F1 recipients, but was far less severe in (bm1 x bm12)F1 recipients and was not observed in (B6 x bm1)F1 recipients. ICGN was also observed in BDF1 recipients at 12 weeks after cell injection. By immunofluorescent microscopy, IC deposition was detected along the capillary loops and also in the mesangial area in (B6 x bm12)F1 recipients, while BDF1 recipients showed only a capillary pattern. By light microscopy, the renal lesion of (B6 x bm12)F1 recipients appeared similar to those of BDF1 recipients. Histologically, (B6 x bm12)F1 recipients serve as a good model for lupus glomerulonephritis induced by class-II-disparate GVHR.

Animals↗
PubMed1992

[The pathogenesis of hypercalciuria from the aspect of the response to human parathyroid hormone in Ca containing stone formers].

In order to clarify the pathogenesis of hypercalciuria, the response to extrinsic human parathyroid hormone (h-PTH) was studied the 21 patients with calcium containing urinary stone(s) and 5 normal controls (NO). The stone patients were classified into 3 groups from the result of the oral calcium loading test, i.e. Non-hypercalciura (NH, n = 8) and absorptive hypercalciuria (AH, n = 8) and renal hypercalciuria (RH, n = 5). Only in the AH group, urinary excretion of calcium (u-Ca) was strongly correlated to that of sodium (u-Na) in pre-load of h-PTH, and both increments were also correlated in post-load of h-PTH. As of this fact the increase in Na excretion seems to be responsible for a cause of hypercalciuria in the AH group. There was a significant correlation between the value of %TRP in pre-load of h-PTH and the rate of urinary phosphorus (P) increment between pre-load and post-load of h-PTH in the NO and NH groups. However, this relationship was not found in the AH and RH groups. These findings indicate that there is response disorder of P to h-PTH. In addition, serum P was low, plasma 1,25 (OH)2D was high, N-c-AMP was low in the AH group, whereas both serum P and %TRP were low in the RH group in pre-load of h-PTH. These findings are compatible with the primary renal P leak.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗