The -48 C/T polymorphism in the presenilin 1 promoter is associated with an increased risk of developing Alzheimer's disease and an increased Abeta load in brain

Mutations in the presenilin 1 gene (PS1) account for the majority of early onset, familial, autosomal dominant forms of Alzheimer's disease (AD), whereas its role in other late onset forms of AD remains unclear. A -48 C/T polymorphism in the PS1 promoter has been associated with an increased genetic risk in early onset complex AD and moreover has been shown to influence the expression of the PS1 gene. This raises the possibility that previous conflicting findings from association studies with homozygosity for the PS1 intron 8 polymorphism might be the result of linkage disequilibrium with the -48 CC genotype. Here we provide further evidence of increased risk of AD associated with homozygosity for the -48 CC genotype (odds ratio=1.6). We also report a phenotypic correlation with Abeta(40), Abeta(42(43)), and total Abeta load in AD brains. The -48 CC genotype was associated with 47% greater total Abeta load (p<0.003) compared to CT + TT genotype bearers. These results suggest that the -48 C/T polymorphism in the PS1 promoter may increase the risk of AD, perhaps by altering PS1 gene expression and thereby influencing Abeta load.

Amyloid beta protein deposition in patients with frontotemporal lobar degeneration: relationship to age and apolipoprotein E genotype

Amyloid beta protein (Abeta) deposition was investigated in the frontal cortex of 54 autopsy cases of frontotemporal lobar degeneration (FTLD) using methenamine silver staining, and immunohistochemistry employing the monoclonal end-specific antibodies BC05 and BA27 to visualize deposits containing Abeta(42(43)) and Abeta(40), respectively. Abeta was detected in 14 (26%) patients, nearly always in the form of diffuse Abeta(42(43)) containing plaques though some cored, neuritic plaques with trace amounts of Abeta(40) were occasionally seen. The 14 patients showing Abeta deposits were significantly older at onset of illness than those 40 patients without Abeta. It was only possible to genotype 46/54 cases, 16 of whom bore at least one copy of the Apolipoprotein E (APOE) epsilon4 allele, giving an allele frequency of 20%. Possession of APOE epsilon4 allele was significantly associated with deposition of Abeta such that 10/16 epsilon4 allele bearers had Abeta deposits. Eight of these ten patients showed only mild to moderate amounts of Abeta, but in two patients, one homozygous and one heterozygous for epsilon4 allele, there was extensive neuritic plaque and neurofibrillary tangle formation. In contrast, only few non-epsilon4 allele bearers (4/30) showed minor Abeta deposits. When stratifying for APOE epsilon4 allele, both bearers and non-bearers of epsilon4 allele with Abeta deposits had a significantly later age at onset than their respective groups without Abeta deposits. We conclude that the likelihood of Abeta deposition, as a secondary and coincidental feature unrelated to the primary pathological process, within the brains of individuals with FTLD will be high if patients have a sufficiently late onset of illness or happen to be a bearer of the APOE epsilon4 allele. Indeed 9/14 patients with Abeta deposits studied here had an onset of illness after 55 years of age and bore APOE epsilon4 allele.

Variant Alzheimer disease with spastic paraparesis: neuropathological phenotype

Variant Alzheimer disease (varAD) is clinically characterized by the combination of presenile dementia with spastic paraparesis and is caused by certain mutations of the presenilin 1 (PS-1) gene. We now present the unusual neuropathological phenotype of varAD as seen in 5 affected members of the original Finnish family with a genomic deletion encompassing exon 9 of the PS-1 gene. Their primary and association cortices and hippocampus showed a profusion of eosinophilic, roundish structures with distinct borders termed "cotton wool" plaques (CWPs). The CWPs were immunoreactive for Abeta42/43 but weakly or not at all for Abeta40 isoforms of the amyloid beta peptide (Abeta). They were devoid of a congophilic core, and fibrillar amyloid could not be identified within them by electron microscopy. Confocal microscopy showed reduced density of axons within individual CWPs and only few CWP-related PHF-tau-positive dystrophic neurites. CWPs were particularly numerous in the medial motor cortex representing the lower extremities, and degeneration of the lateral corticospinal tracts was observed at the level of the medulla oblongata and the spinal cord. In addition to the predominant CWPs, variable numbers of diffuse and cored plaques were found in the cerebral cortex. Diffuse and non-neuritic cored amyloid plaques but no CWPs occurred in the cerebellum. In conclusion, varAD in this Finnish family is distinct from classic AD because of the degeneration of lateral corticospinal tracts, predominance of CWPs devoid of fibrillar amyloid cores in the cerebral cortex, and presence of non-neuritic amyloid plaques in the cerebellum.

[Anesthetic management of the King-Denborough syndrome]

The King-Denborough syndrome (KDS) is a congenital myopathy with musculoskeletal abnormalities, and definitely associated with susceptibility to malignant hyperthermia (MH). We present the first report in Japan concerning the management of a KDS patient. A 2-year-old boy was scheduled for cryptorchidopexy. He had some physical signs of KDS, e.g. pectus excavatum, low-set ears, malar hypoplasia, micrognathia, ptosis and down-slanting palpebral fissures. Moreover, his mother and maternal grand-uncle had medical history of MH. Therefore, he was diagnosed as KDS by pediatricians. All of the preoperative examinations, including serum creatine phosphokinase level, are normal. Previous 15 case-reports suggest that in KDS patients MH might be triggered by volatile anesthetics. To avoid the trigger, we maintained the general anesthesia with propofol, fentanyl and vecuronium. During perioperative period, his body temperature was 36.3-38.1 degrees C, and no symptom of MH was observed. It is rare that a diagnosis of KDS is made preoperatively since the MH-induction is involved in the criteria of this syndrome. In the anesthesia of patients who are suspected of KDS from their characteristic features or familial histories, an anesthesiologist should pay attention to prevent MH. The total intravenous anesthesia method appears useful for the management of KDS.

Familial amyotrophic lateral sclerosis and parkinsonism-dementia complex of the Kii Peninsula of Japan: clinical and neuropathological study and tau analysis

We report the first case of neuropathologically verified parkinsonism-dementia complex of the Kii peninsula, together with the patient's brother, who had amyotrophic lateral sclerosis. The propositus woman developed parkinsonism and dementia at 63 years of age and died at 70 without displaying clinical features of amyotrophic lateral sclerosis. The brain exhibited marked atrophy of the frontal and temporal lobes. Microscopically, there were many neurofibrillary tangles in the central nervous system, most markedly in the mesial temporal lobe and deep nuclei, as well as changes of amyotrophic lateral sclerosis but no senile plaques or Lewy bodies. Neurofibrillary tangles exhibited twisted tubule structures on electon microscopic examination, and an analysis of insoluble tau protein extracted from the fresh brain revealed a 60-, 64-, 68-kD triplet. The tau gene exhibited no mutations. Her brother developed progressive bulbar palsy-type amyotrophic lateral sclerosis at 45 years of age and died at 49 without presenting with dementia or parkinsonism. Neuropathological examination revealed not only pathologic features of amyotrophic lateral sclerosis but also a moderate number of neurofibrillary tangles in the temporal cortex and deep nuclei. The siblings were neuropathologically similar despite their different clinical manifestations. These findings suggest that amyotrophic lateral sclerosis and parkinsonism-dementia complex of this family may be phenotypic variants of a tauopathy caused by genetic abnormalities.

Molecular cloning and expression of the novel splice variants of K(+) channel-interacting protein 2

Two cDNAs encoding the splice variants of K(+) channel-interacting protein 2 (KChIP2) recently reported as human KChIP2 have been identified from rat, mouse, and human heart by RT-PCR. A longer variant, KChIP2L encodes a protein of 270 amino acids, which has a 50-amino-acid insertion in N-terminus in comparison with a shorter one, KChIP2S. Interestingly, both KChIP2S and KChIP2L (KChIP2S/L) but not the original KChIP2 were expressed in human heart and umbilical vein endothelial cells (HUVECs). KChIP2S transcripts but not KChIP2L were predominantly expressed in rat, mouse, and human heart and HUVECs, whereas both transcripts were expressed at low levels in other tissues such as brain, aorta, and kidney. Using chimeric proteins of green fluorescence protein (GFP) fused to the N-terminus of KChIP2S/L, the interactions between Kv4.3 and KChIP2S/L were analyzed in native and Kv4.3-expressed HEK293 cells. Specific localization of GFP-fused KChIP2S/L proteins on or near cell membrane was observed only in Kv4.3-expressed HEK293 cells.

Co-localization of alpha-synuclein and phosphorylated tau in neuronal and glial cytoplasmic inclusions in a patient with multiple system atrophy of long duration

Neuronal and glial cytoplasmic inclusions (NCIs and GCIs), which contain alpha-synuclein as a major component, are characteristic cytopathological features of multiple system atrophy (MSA). We report MSA of 19 years' duration in a 73-year-old woman. Her initial symptom was parkinsonism, with dementia appearing about 8 years later. Postmortem examination showed marked atrophy of the frontal and temporal white matter and limbic system, in addition to the pathology typical of MSA. In the limbic system, severe neuronal loss and astrocytosis were observed, and the remaining neurons often had lightly eosinophilic, spherical cytoplasmic inclusions. Interestingly, a double-labeling immunofluorescence study revealed that the NCIs in the dentate gyrus and amygdaloid nucleus, and the GCIs in the frontal and temporal white matter often expressed both alpha-synuclein NACP-5 and phosphorylated tau AT8 epitopes. Double-immunolabeling electron microscopy of the NCIs in the dentate gyrus and the GCIs in the temporal white matter clearly revealed labeling of their constituent granule-associated filaments with NACP-5, and some of them were also labeled with AT8. These findings strongly suggested that some alpha-synuclein filaments were decorated with phosphorylated tau without formation of fibrils such as paired helical filaments. Immunoblotting of sarkosyl-insoluble tau indicated that the accumulated tau consisted mainly of four-repeat tau isoforms of 383 amino acids and 412 amino acids. We consider that the limbic system can be a major site of neurodegeneration in MSA of long duration. The mechanisms of such abnormal tau accumulation in the NCIs and GCIs are unknown.

In vitro/in vivo scaling of alprazolam metabolism by CYP3A4 and CYP3A5 in humans

We attempted to predict the in vivo metabolic clearance of alprazolam from in vitro metabolic studies using human liver microsomes and human CYP recombinants. Good correlations were observed between the intrinsic clearance (CL(int)) for 4-hydroxylation and CYP3A4 content and between the CL(int) for alpha-hydroxylation and CYP3A5 content in ten human liver microsomal samples. Using the recombinant CYP isoforms expressed in insect cells, the CL(int) for CYP3A4 was about 2-fold higher than the CL(int) for CYP3A5 in the case of 4-hydroxylation. However, the CL(int) for CYP3A5 was about 3-fold higher than the CL(int) for CYP3A4 in the case of alpha-hydroxylation. The metabolic rates for 4- and alpha-hydroxylation increased as the added amount of cytochrome b(5) increased, and their maximum values were 3- to 4-fold higher than those without cytochrome b(5). The values of CL(int), in vivo predicted from in vitro studies using human liver microsomes and CYP3A4 and CYP3A5 recombinants were within 2.5 times of the observed value calculated from literature data. The average CL(int) value (sum of 4- and alpha-hydroxylation) obtained using three human liver microsomal samples was 4-fold higher than that obtained using three small intestinal microsomal samples from the same donors, indicating the minor contribution of intestinal metabolism to alprazolam disposition. The area under the plasma concentration-time curve (AUC) of alprazolam is reported to increase following co-administration of ketoconazole and the magnitude of the increase predicted from the in vitro K(i) values and reported pharmacokinetic parameters of ketoconazole was 2.30-2.45, which is close to the value observed in vivo (3.19). A quantitative prediction of the AUC increase by cimetidine was also successful (1.73-1.79 vs 1.58-1.64), considering the active transport of cimetidine into the liver. In conclusion, we have succeeded in carrying out an in vitro/in vivo scaling of alprazolam metabolism using human liver microsomes and human CYP3A4 and CYP3A5 recombinants.

[Assessment of anesthesia satisfaction using direct interviews at post-anesthesia clinic]

The authors studied 5,034 consecutive patients undergoing elective surgery. Preoperative, intraoperative, and postoperative variables were gathered and patient satisfaction was assessed using direct interviews at pre- and post-anesthesia clinic. Fifty-nine percent of the 4,717 responders showed satisfaction and 4% showed dissatisfaction with anesthesia. The most undesirable perioperative outcome was vomiting/nausea. Other undesirable outcomes include discomfort of urine catheter, sore throat, memory of extubation, postoperative pain and so on. Anesthesiologist can improve the quality of anesthesia by preoperative explanation and preventative management for undesirable perioperative outcomes.

Effect of the APOE promoter polymorphisms on cerebral amyloid peptide deposition in Alzheimer's disease

Polymorphisms in the promoter region of the apolipoprotein E gene (APOE) affect the amount of amyloid peptide (Abeta) in the brains of patients with Alzheimer's disease. We measured Abeta load immunohistochemically in regions 8 and 9 of Brodman's area in 74 people with Alzheimer's disease. The amount of Abeta deposition was independent of APOE genotype in our cohort. These findings in patients with confirmed Alzheimer's disease are consistent with the hypothesis that variation in APOE expression directly affects Alzheimer's disease pathology.

Calpain-mediated degradation of p35 to p25 in postmortem human and rat brains

Tau in Alzheimer neurofibrillary tangles has been shown to be hyperphosphorylated and CDK5, GSK3, MAP kinase and SAP kinases are the candidate kinases for the phosphorylation of tau. Recently, it was reported that the conversion of p35, the activator of CDK5, to p25 was upregulated in Alzheimer's disease (AD) brains, and that p35 is cleaved to yield p25 by calpain. Here we show that p35 is rapidly cleaved to p25 in rat and human brains within a short postmortem delay and that the conversion of p35 to p25 is partially dependent on calpain activity. Immunoblot analysis of brains prepared from patients with AD or age-matched control individuals with a short postmortem delay revealed no specific increase in the levels of p25 in AD brains, whereas the levels of active form of calpain were increased in AD brains compared to the those in controls. These observations suggest that the conversion of p35 to p25 is a postmortem degradation event and may not be upregulated in AD brains.

Localization, Transport, and Uptake of -Aspartate in the Rat Adrenal and Pituitary Glands

Large amounts of D-aspartate (D-Asp) are present in the rat adrenal and pituitary glands. D-Asp is thought to be synthesized in the mammalian body and also accumulates in various tissues following intraperitoneal or intravenous administration. This report examines the origins of D-Asp in the adrenal and pituitary glands. We administered D-Asp to male rats intraperitoneally and immunolocalized this exogenous D-Asp in adrenal and pituitary tissue, using an anti-D-Asp antiserum which was previously developed in our laboratory. D-Asp levels in the rat adrenal gland have been shown to undergo a transient increase at 3 weeks of age and to decrease rapidly thereafter. We found that in the adrenal gland, exogenous D-Asp administered intraperitoneally was incorporated into the same region of the adrenal cortex in which endogenous D-Asp was present. By Northern and Western blot analysis and immunohistochemistry of glutamate (Glu) transporter, we also found that expression of the Glu transporter (GLAST), which has an affinity for D-Asp, transiently increased at 3 weeks of age and that localization patterns of the Glu transporter within the tissue were almost coincident with those of endogenous D-Asp. These observations suggest that D-Asp in the adrenal cortex of 3-week-old male rats is primarily acquired by uptake from the vascular system. We have previously shown that D-Asp is specifically localized in prolactin (PRL)-containing cells in the anterior lobe of the adult rat pituitary gland. Here we report that in the pituitary gland, exogenous D-Asp accumulated in endothelial cells, but not in PRL-containing cells. Northern and Western blot analysis and immunohistochemistry of Glu transporter revealed that developmental changes in the Glu transporter (GLAST) expression did not correlate with tissue levels of D-Asp and that the Glu transporter was not expressed in PRL-containing cells. These observations suggest that, in contrast to the adrenal gland, most of the D-Asp in the pituitary gland of adult male rats originates inside the gland itself.

[Effect of colforsin daropate hydrochloride after cardiopulmonary bypass]

We evaluated the effects of colforsin daropate hydrochloride (CDH) after cardiopulmonary bypass (CPB) in comparison with milrinone. CDH or milrinone were given during and after CPB combined with cathecholamines so as to maintain mean arterial pressure (mABP > 60 mmHg) and cardiac index (CI > 3.0 l.min-1.m-2). Hemodynamics measurement was done immediately after CPB (A 1), one hour after CPB (A 2) and after the chest closure (A 3). In CDH group, mABP was significantly higher compared with milrinone group. Also, CDH group showed a significant reduction in the cases of combined use of dobutamine (at A 2, A 3) and norepinephrine (at A 1, A 2) compared with milrinone group. In conclusion, colforsin daropate hydrochloride exerts more inotropic effect and could reduce the necessity of combined use of cathecholamine compared with milrinone.

Pick's disease is associated with mutations in the tau gene

Recently, mutations within the tau gene have been associated with some familial forms of frontotemporal dementia. To investigate whether tau gene mutations are also associated with Pick's disease, we analyzed the tau gene in 30 cases of pathologically confirmed Pick's disease. Two coding mutations were identified in separate cases of Pick's disease. A glycine-to-arginine mutation at codon 389 was detected in 1 case and a lysine-to-threonine mutation at codon 257 was identified in another. Analysis of dephosphorylated tau from the brain of the patient with the codon 389 mutation revealed a prominent band representing tau, with four microtubule-binding domains and no amino terminal inserts. This is in contrast to Pick's disease without any tau gene mutations, which consist of tau with mainly three microtubule-binding domains and only a trace of tau, with four microtubule-binding domains. Functional analysis of tau with these two mutations demonstrated a reduced ability of tau to promote microtubule assembly. Surprisingly, these mutations increased tau's susceptibility to calpain I digestion, suggesting that this feature may be related to the formation of a Pick type of histology. Moreover, these data suggest that Pick's disease is not a separate entity but part of the frontotemporal dementia disease spectrum.

[beta-amyloid cascade: current status and future directions]

The deposition of amyloid beta peptides (A beta) is one of the pathological hallmarks of Alzheimer's disease (AD) brains. A beta are composed of 40-42 amino acid peptides that are proteolytically cleaved from beta APP. The deposition as diffuse plaques of a species of A beta ending at the 42nd residue (A beta 42) is one of the earliest pathological changes of AD. Importantly, mutations in beta APP genes located in positions flanking the A beta sequences have been shown to cosegregate with the clinical manifestations of AD in a subset of familial AD (FAD) pedigrees. Moreover, mutations in presenilin (PS) 1 and 2, novel polytopic membrane proteins identified as causative molecules for the majority of FAD, also increase the production of A beta 42. These results support the notion that A beta (42) plays a key role in the cascadic development of AD. Recently, PS 1 and PS 2 are shown to be the catalytic subunits of gamma-secretase that cleave the intramembrane segments of beta APP and Notch. Future therapeutic approaches to reduce amyloid deposition, including inhibitors for beta- and gamma-secretases, as well as beta-amyloid vaccine therapy, raise high hopes towards the cure and prevention of AD, although the outcome thereof would be key to the consistency of amyloid cascade hypothesis.

Amyloid precursor proteins inhibit heme oxygenase activity and augment neurotoxicity in Alzheimer's disease

Amyloid precursor protein (APP) generates the beta-amyloid peptide, postulated to participate in the neurotoxicity of Alzheimer's disease. We report that APP and APLP bind to heme oxygenase (HO), an enzyme whose product, bilirubin, is antioxidant and neuroprotective. The binding of APP inhibits HO activity, and APP with mutations linked to the familial Alzheimer's disease (FAD) provides substantially greater inhibition of HO activity than wild-type APP. Cortical cultures from transgenic mice expressing Swedish mutant APP have greatly reduced bilirubin levels, establishing that mutant APP inhibits HO activity in vivo. Oxidative neurotoxicity is markedly greater in cerebral cortical cultures from APP Swedish mutant transgenic mice than wild-type cultures. These findings indicate that augmented neurotoxicity caused by APP-HO interactions may contribute to neuronal cell death in Alzheimer's disease.

A FE65 polymorphism associated with risk of developing sporadic late-onset alzheimer's disease but not with Abeta loading in brains

The FE65 protein was previously described interacting with amyloid protein precursor (APP) and mediating its internalization. Hu et al. (Hum. Genet., 103 (1998) 295) recently reported that a deletion polymorphism in intron 13 of the FE65 gene may be protective for sporadic Alzheimer's disease (AD) forms and suggested that this deletion may modify splicing between exon 13 and 14 (the two exons encoding the interaction domain of FE65 with APP). We tested the impact of this polymorphism in 646 controls and 639 sporadic AD cases. We were only able to detect a protective effect of the deletion in the population over 75 years (odds ratio = 0.53, 95% confidence interval (0.35-0.82), P= 0.002). Furthermore, no association of this polymorphism with Abeta40, Abeta42(43) and total Abeta loads were detected in 74 AD brains, although, we could expect that this deletion was associated with modifications of the APP metabolism. In conclusion, the FE65 gene may be a minor genetic determinant only for sporadic late-onset AD forms, although, we cannot conclude that this impact is mediated by a modulation of the APP process and/or Abeta peptide deposition.

Alpha-synuclein inclusions in amygdala in the brains of patients with the parkinsonism-dementia complex of Guam

We investigated by immunohistochemistry the deposition of alpha-synuclein in the brains of deceased patients with the parkinsonism-dementia complex (PDC) of Guam. Five of 13 PDC brains showed numerous alpha-synuclein positive neuronal inclusions and abnormal neurites, chiefly in the amygdala. Similar alpha-synuclein positive lesions were observed, although to a lesser extent, in the entorhinal cortex and the dorsal vagal nucleus. No alpha-synuclein positive inclusions were observed in motor cortex or locus coeruleus, and only a small number of positive inclusions were found in the Sommer's sector, temporal cortex, or substantia nigra. Some of the alpha-synuclein positive inclusions were reminiscent of cortical Lewy bodies (LB), but many of those in the amygdala coexisted with tau-positive pretangles and/or neurofibrillary tangles (NFT) within the same neurons. In these neurons, tau-positive shells encapsulated alpha-synuclein positive central cores or irregularly shaped alpha-synuclein-positive deposition intermingled with pretangles/NFT. Thus, the present study suggests that a common mechanism may govern aggregation of alpha-synuclein and tau in the amygdala, and that aggregation of alpha-synuclein may play some role in the neurodegenerative process of a tauopathy (i.e. PDC) in which Abeta deposition is virtually absent.

The nonconserved hydrophilic loop domain of presenilin (PS) is not required for PS endoproteolysis or enhanced abeta 42 production mediated by familial early onset Alzheimer's disease-linked PS variants

Presenilin 1 (PS1) and presenilin 2 (PS2) are polytopic membrane proteins that are mutated in the majority of early onset familial Alzheimer's disease (FAD) cases. Two lines of evidence establish a critical role for PS in the production of beta-amyloid peptides (Abeta). FAD-linked PS mutations elevate the levels of highly amyloidogenic Abeta ending at residue 42 (Abeta42), and cells with ablated PS1 alleles secrete low levels of Abeta. Several recent reports have shown that the hydrophilic loop (HL) domain, located between transmembrane domains 6 and 7, contains sites for phosphorylation, caspase cleavage, and sequences that bind several PS-interacting proteins. In the present report, we examined the metabolism of PS polypeptides lacking the HL domain and the influence of these molecules on Abeta production. We report that the deletion of the HL domain does not have a deleterious effect on the regulated endoproteolysis of PS, saturable accumulation of PS fragments, or the self-association of PS fragments. Abeta production was not significantly altered in cells expressing HL-deleted PS polypeptides compared with cells expressing full-length PS. Importantly, deletion of the HL domain did not affect FAD mutation-mediated elevation in the production of Abeta42. Furthermore, the deletion of the HL domain did not impair the role of PS1 or PS2 in facilitating Notch processing. Thus, our results argue against a biologically or pathologically relevant role for the HL domain phosphorylation and caspase cleavage and the association of PS HL domain-interacting proteins, in amyloid precursor protein metabolism and Abeta production or Notch cleavage.

Two brothers with frontotemporal dementia and parkinsonism with an N279K mutation of the tau gene

OBJECTIVE

To characterize the clinical diagnostic features, neuropathologic phenotype of tau deposition, and subunit structure of tau filaments in patients who had an asparagine-to-lysine substitution at codon 279 (the N279K missense mutation) of the gene for microtubule-associated tau protein.

BACKGROUND

The N279K mutation is a causative genetic defect for pallidopontonigral degeneration in an American kindred that presents with frontotemporal dementia (FTD) and parkinsonism.

METHODS

The authors analyzed retrospectively the clinical symptoms of two Japanese brothers who carry this mutation. Postmortem neuropathologic and electron microscopic studies, and Western blot analysis of insoluble tau were performed to correlate tau-mediated lesions with neurologic deficits.

RESULTS

Both patients exhibited impairment in recent memory, parkinsonism, and corticospinal disturbances in addition to FTD. Parkinsonism in one patient was responsive temporarily to l-dopa. There was intense tau deposition in the medial temporal cortices and upper and lower motor neurons with accompanying corticospinal tract degeneration. Two distinct tau isoforms with four microtubule-binding repeats, in hyperphosphorylated forms, were the primary constituents of insoluble tau, which aggregated to the filamentous component, termed "paired tubules," in neurons, oligodendrocytes, and astrocytes. The elemental filaments were hollow tubules measuring 11 to 12 nm in diameter, two of which adhered to each other along their longitudinal axes to form "paired tubules."

CONCLUSIONS

Early memory loss and pyramidal signs, which are atypical of FTD, can be presenting symptoms in this disorder. The authors demonstrated that the subunit structure of tau filaments is a pair of hollow tubules despite the prevailing twisted ribbon model.

Separation of aromatic isomers on cyclophane-bonded stationary phases

A cyclophane (CP66)-bonded silica gel stationary phase (CP66-SP) was prepared and the retention of water-insoluble hydrophobic compounds on it was investigated in comparison with that on the CP44-bonded stationary phase (CP44-SP) reported previously. Like CP44-SP, it retained aromatic compounds more strongly than the corresponding alicyclic compounds, as was expected by the cavity size of the cyclophane. The CP66-SP also showed isomer-selectivity for monosubstituted and disubstituted naphthalenes, but its selectivity was perfectly reversed to that of the CP44-SP. On the CP66-SP, isomers having methyl and ethyl groups at beta-position were eluted prior to those having groups at alpha-position, whereas on the CP44-SP beta-substituted naphthalenes were retained more strongly than alpha-substituted ones. Isomers of three- and four-ring aromatic compounds were also separated on these cyclophane-bonded stationary phases. The retention order on the CP66-SP was almost opposite to that on the CP44-SP; on the CP66-SP, the retention order was phenanthrene > anthracene, and chrysene > 1,2-benzanthracene > 2,3-benzanthracene, whereas on the CP44-SP, anthracene > phenanthrene, and 2,3-benzanthracene > chrysene > 1,2-benzanthracene. The retention mechanism of aromatic compounds is discussed on the basis of the structure of the cyclophane-involved complex.

Molecular cloning and characterization of a novel chloride intracellular channel-related protein, parchorin, expressed in water-secreting cells

We previously reported a 120-kDa phosphoprotein that translocated from cytosol to the apical membrane of gastric parietal cells in association with stimulation of HCl secretion. To determine the molecular identity of the protein, we performed molecular cloning and expression of the protein. Immunoblot analysis showed that this protein was highly enriched in tissues that secrete water, such as parietal cell, choroid plexus, salivary duct, lacrimal gland, kidney, airway epithelia, and chorioretinal epithelia. We named this protein "parchorin" based on its highest enrichment in parietal cells and choroid plexus. We obtained cDNA for parchorin from rabbit choroid plexus coding a protein consisting of 637 amino acids with a predicted molecular mass of 65 kDa. The discrepancy in size on 6% SDS-polyacrylamide gel electrophoresis is considered to be due to its highly acidic nature (pI = 4.18), because COS-7 cells transfected with parchorin cDNA produced a protein with apparent molecular mass of 120 kDa on 6% SDS-polyacrylamide gel electrophoresis. Parchorin is a novel protein that has significant homology to the family of chloride intracellular channels (CLIC), especially the chloride channel from bovine kidney, p64, in the C-terminal 235 amino acids. When expressed as a fusion protein with green fluorescent protein (GFP) in the LLC-PK1 kidney cell line, GFP-parchorin, unlike other CLIC family members, existed mainly in the cytosol. Furthermore, when Cl(-) efflux from the cell was elicited, GFP-parchorin translocated to the plasma membrane. These results suggest that parchorin generally plays a critical role in water-secreting cells, possibly through the regulation of chloride ion transport.

A novel mutation at position +12 in the intron following exon 10 of the tau gene in familial frontotemporal dementia (FTD-Kumamoto)

Exonic and intronic mutations in the tau gene cause familial frontotemporal dementia and parkinsonism linked to chromosome 17. Here, we describe a new mutation, consisting of a C-to-T transition at position +12 of the intron following exon 10 of the tau gene in the Kumamoto pedigree, showing frontotemporal dementia. The mutation caused a marked reduction in melting temperature of the tau exon 10-splicing regulatory element RNA and a large increase in exon 10-containing transcripts. Brain tissue from affected individuals showed an abnormal preponderance of exon 10-containing transcripts that was reflected at the protein level by an overproduction of tau isoforms with four microtubule-binding repeats. Immunostaining revealed the presence of tau aggregates in degenerating neurons and glial cells. Isolated tau filaments had a twisted ribbon-like morphology and were made of hyperphosphorylated four-repeat tau isoforms. The additional mutation located dose to the splice-donor site of the intron following exon 10 of the tau gene supports the view that intronic mutations exercize their pathogenic effect by destabilizing RNA secondary structure.