We developed a new immunohistochemical method by which normal tau antigenicity can be visualized in paraffin sections of formalin-fixed brain tissue. This method consists of autoclave pretreatment of ...sections immersed into distilled water (hydrated autoclaving) before incubation with anti-tau antibodies. In normal human brain, immunoreactive tau was detected in neuronal cell bodies and dendrites, axon fibers, astroglia, oligodendroglia and gray matter neuropil. In previous studies on normal tau distribution, different optimized fixations that effectively preserve tau antigenicity were used but none of these revealed all of these compartments together. Our method is therefore considered to be more sensitive for detecting normal tau immunoreactivity. In addition, hydrated autoclaving had an enhancing effect on the abnormally phosphorylated (modified) tau immunoreactivity in formalin-fixed brains. In hydrated autoclaving of sections from patients with Alzheimer's disease, neuropil threads, senile plaques, extracellular and intracellular tangles were enhanced in quantity and in staining intensity. Therefore, modified tau appears to accumulate more densely than expected from conventional immunohistochemistry. Immunoblot analysis showed that normal or modified tau immunoreactivity was totally or partially eliminated on formalin treatment and could be revisualized by hydrated autoclaving, an event presumably related to recovering of formalin-masked tau antigens through denaturation by hydrated autoclaving.
A new method, which enabled the first immunohistochemical documentation of abnormal prion protein (PrP) in all patients with Creutzfeldt-Jakob disease (CJD), was established. This method designated ...as "hydrolytic autoclaving" revealed punctate PrPCJD stainings around the neuronal cell bodies and dendrites in CJD brains. These punctate stainings were almost identical with that of synaptophysin, suggesting PrPCJD accumulations in the synaptic structures. Subcellular fractionation revealed that prion protein in Creutzfeldt-Jakob disease (PrPCJD) was most concentrated in the synaptosomal fraction. In CJD patients with a long clinical course, synaptophysin immunoreactivity decreased, and synaptic PrPCJD accumulated with a wider distribution. These results suggest that synaptic PrPCJD accumulations might be responsible for the neuronal dysfunction and degeneration in CJD.
Surgical, pharmacological and genetic lesion studies have revealed distinct anatomical sites involved with different forms of learning. Studies of patients with localized brain damage and work in ...rodent model systems, for example, have shown that the hippocampal formation participates in acquisition of declarative tasks but is not the site of their long-term storage. Such lesions are usually irreversible, however, which has limited their use for dissecting the temporal processes of acquisition, storage and retrieval of memories. Studies in bees and flies have similarly revealed a distinct anatomical region of the insect brain, the mushroom body, that is involved specifically in olfactory associative learning. We have used a temperature-sensitive dynamin transgene, which disrupts synaptic transmission reversibly and on the time-scale of minutes, to investigate the temporal requirements for ongoing neural activity during memory formation. Here we show that synaptic transmission from mushroom body neurons is required during memory retrieval but not during acquisition or storage. We propose that the hebbian processes underlying olfactory associative learning reside in mushroom body dendrites or upstream of the mushroom body and that the resulting alterations in synaptic strength modulate mushroom body output during memory retrieval.
We analysed the epidemiological data and clinical features of patients with prion diseases that had been registered by the Creutzfeldt-Jakob Disease Surveillance Committee, Japan, over the past 10 ...years, since 1999. We obtained information on 1685 Japanese patients suspected as having prion diseases and judged that 1222 patients had prion diseases, consisting of definite (n = 180, 14.7%) and probable (n = 1029, 84.2%) cases, except for dura mater graft-associated Creutzfeldt–Jakob disease which also included possible cases (n = 13, 1.1%). They were classified into 922 (75.5%) with sporadic Creutzfeldt–Jakob disease, 216 (17.7%) with genetic prion diseases, 81 (6.6%) with acquired prion diseases, including 80 cases of dura mater graft-associated Creutzfeldt–Jakob disease and one case of variant Creutzfeldt–Jakob disease, and three cases of unclassified Creutzfeldt–Jakob disease (0.2%). The annual incidence rate of prion disease ranged from 0.65 in 1999 to 1.10 in 2006, with an average of 0.85, similar to European countries. Although methionine homozygosity at codon 129 polymorphism of the prion protein gene was reported to be very common (93%) in the general Japanese population, sporadic Creutzfeldt–Jakob disease in Japan was significantly associated with codon 129 homozygosity (97.5%), as reported in western countries. In sporadic Creutzfeldt–Jakob disease, MM1 type (Parchi’s classification) is the most common, as in western countries. Among atypical sporadic Creutzfeldt–Jakob disease cases, the MM2 type appeared most common, probably related to the very high proportion of methionine allele in the Japanese population. As for iatrogenic Creutzfeldt–Jakob disease, only dura mater graft-associated Creutzfeldt–Jakob disease cases were reported in Japan and, combined with the data from previous surveillance systems, the total number of dura mater graft-associated Creutzfeldt–Jakob disease was 138, comprising the majority of worldwide dura mater graft-associated Creutzfeldt–Jakob disease patients. Regarding genetic prion diseases, the most common mutation of prion protein gene was V180I (41.2%), followed by P102L (18.1%), E200K (17.1%) and M232R (15.3%), and this distribution was quite different from that in Europe. In particular, V180I and M232R were quite rare mutations worldwide. Patients with V180I or M232R mutations rarely had a family history of prion diseases, indicating that a genetic test for sporadic cases is necessary to distinguish these from sporadic Creutzfeldt–Jakob disease. In conclusion, our prospective 10-year surveillance revealed a frequent occurrence of dura mater graft-associated Creutzfeldt–Jakob disease, and unique phenotypes of sporadic Creutzfeldt–Jakob disease and genetic prion diseases related to the characteristic distribution of prion protein gene mutations and polymorphisms in Japan, compared with those in western countries.
A clinicopathologic study was made of 16 patients with amyloidosis and with clinical signs of intestinal pseudo-obstruction. amyloid deposits in the small intestine were proved in all cases by ...endoscopic or intra-operative biopsies, and immunohistochemical study identified the chemical types of amyloid protein: amyloid A protein (AA) in 13 cases, light chain protein (AL) in two, and beta 2-microglobulin (AH) in one. Clinically, an acute self limiting obstructive condition was evident in 13 cases with AA, and 12 of them returned to normal bowel function after receiving total parenteral nutrition. Two cases with AL and one with AH presented chronic, intermittent, obstructive symptoms, and medical treatment, including total parenteral nutrition, was ineffective with no recovery of intestinal propulsion. Pathological examination of the necropsy specimens in seven cases showed considerable differences in the preferential sites of gastrointestinal deposits between the chemical types of amyloid; extensive infiltration and replacement of the muscularis propria by amyloid deposits throughout the gastrointestinal tract, especially the small intestine, were found in the AL and the AH cases, while amyloid deposits in the myenteric plexus without appreciable muscle infiltration were shown in the AA cases. These results show that intestinal pseudo-obstruction in patients with amyloidosis is caused by either myopathy or neuropathy, and that chemical types of amyloid may determine which of the two factors has the dominant affect on the bowel function.
The cAMP-responsive transcription factor, CREB, is required for formation of long-term memory (LTM) in Drosophila melanogaster and regulates transcription of a cricadian clock gene, period (per). ...Involvement of CREB both in LTM and circadian rhythm raises the possibility that per also plays a role in LTM. Assaying the experience-dependent courtship inhibition in male flies as a measure for LTM, we show here that per mutants are defective in LTM formation. This defect was rescued by induction of a wild-type per transgene in a per-null mutant, and overexpression of per enhanced LTM formation in the wild-type background. Furthermore, we found that synaptic transmission through per-expressing cells is most likely to be required during retrieval of LTM. In contrast, mutations in other clock genes (timeless, dClock, and cycle) did not affect LTM formation. Thus, independent of the core oscillator of circadian clock, per plays a key role in LTM formation.
Phospholipid hydroperoxide glutathione peroxidase (PHGPx) is the only known intracellular antioxidant enzyme that can directly reduce lipid hydroperoxide in membrane. Mitochondrial and ...non-mitochondrial PHGPx and sperm nuclei GPx are transcribed from one gene by alternative transcription using different first exons Ia and Ib, respectively. To examine the role of PHGPx in development, we generated mice deficient in PHGPx by a targeted disruption of all exons of the PHGPx gene. Heterozygotes are viable, fertile, and appear normal, despite having decreased levels of three types of PHGPx mRNA and protein. Embryos homozygous for PHGPx-null die between 7.5 and 8.5 days post coitum (dpc), probably developing distal apoptosis. We examined the expression of PHGPx in mouse embryos using immunohistochemical analysis with anti-PHGPx mAb. The expression of PHGPx was detected in the embryonic ectoderm and the yolk sac membrane at 7.5
dpc. The results demonstrated that PHGPx is expressed in early gastrulation stage at 7.5
dpc and that the expression of PHGPx was essential for normal mouse development.
To clarify a clinical and neuropathologic phenotype of an inherited prion disease associated with a missense mutation at codon 105 in the prion protein (PrP) gene that was originally described as a ...variant of Gerstmann-Sträussler-Scheinker disease demonstrating spastic paraparesis.
Two siblings from a Japanese family are described. PrP gene analyses, neuropathologic studies with immunohistochemistry, and Western blot analysis of the PrP were performed.
Both patients showed a missense (proline-->leucine) mutation at codon 105 and a methionine/valine polymorphism at codon 129 of the PrP gene. Clinically, Patient 1 presented with progressive spastic paraparesis, ataxia, and dementia. Patient 2, the sister of Patient 1, showed prominent action myoclonus and dementia. Neuropathologically, multiple PrP-positive amyloid plaques and diffuse PrP deposition in the deep cortical layers were found in the cerebral cortex with primarily frontal dominant atrophy in both patients. Tau-positive pathologic structures including neurofibrillary tangles, neuropil threads, and dystrophic neurites around the plaques were abundant in the brain of Patient 2. In contrast, the tau pathology was scarce in Patient 1. Western blot analysis of the brain showed different patterns of detergent-insoluble PrP fragments between the patients.
Despite the identical codon 105 mutation and codon 129 polymorphism of the PrP gene, remarkable clinical and neuropathologic differences, and PrP heterogeneity were present between the affected siblings. The phenotypic variability might be related to PrP heterogeneity.
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