Kenichi Oshima

Clinical Features of Schizophrenia With Enhanced Carbonyl Stress

Accumulating evidence suggests that advanced glycation end products, generated as a consequence of facilitated carbonyl stress, are implicated in the development of a variety of diseases. These diseases include neurodegenerative illnesses, such as Alzheimer disease. Pyridoxamine is one of the 3 forms of vitamin B6, and it acts by combating carbonyl stress and inhibiting the formation of AGEs. Depletion of pyridoxamine due to enhanced carbonyl stress eventually leads to a decrease in the other forms of vitamin B6, namely pyridoxal and pyridoxine. We previously reported that higher levels of plasma pentosidine, a well-known biomarker for advanced glycation end products, and decreased serum pyridoxal levels were found in a subpopulation of schizophrenic patients. However, there is as yet no clinical characterization of this subset of schizophrenia. In this study, we found that these patients shared many clinical features with treatment-resistant schizophrenia. These include a higher proportion of inpatients, low educational status, longer durations of hospitalization, and higher doses of antipsychotic medication, compared with patients without carbonyl stress. Interestingly, psychopathological symptoms showed a tendency towards negative association with serum vitamin B6 levels. Our results support the idea that treatment regimes reducing carbonyl stress, such as supplementation of pyridoxamine, could provide novel therapeutic benefits for this subgroup of patients.

Assessment of copy number variations in the brain genome of schizophrenia patients.

BackgroundCytogenomic mutations and chromosomal abnormality are implicated in the neuropathology of several brain diseases. Cell heterogeneity of brain tissues makes their detection and validation difficult, however. In the present study, we analyzed gene dosage alterations in brain DNA of schizophrenia patients and compared those with the copy number variations (CNVs) identified in schizophrenia patients as well as with those in Asian lymphocyte DNA and attempted to obtain hints at the pathological contribution of cytogenomic instability to schizophrenia.ResultsBrain DNA was extracted from postmortem striatum of schizophrenia patients and control subjects (n = 48 each) and subjected to the direct two color microarray analysis that limits technical data variations. Disease-associated biases of relative DNA doses were statistically analyzed with Bonferroni’s compensation on the premise of brain cell mosaicism. We found that the relative gene dosage of 85 regions significantly varied among a million of probe sites. In the candidate CNV regions, 26 regions had no overlaps with the common CNVs found in Asian populations and included the genes (i.e., ANTXRL, CHST9, DNM3, NDST3, SDK1, STRC, SKY) that are associated with schizophrenia and/or other psychiatric diseases. The majority of these candidate CNVs exhibited high statistical probabilities but their signal differences in gene dosage were less than 1.5-fold. For test evaluation, we rather selected the 10 candidate CNV regions that exhibited higher aberration scores or larger global effects and were thus confirmable by PCR. Quantitative PCR verified the loss of gene dosage at two loci (1p36.21 and 1p13.3) and confirmed the global variation of the copy number distributions at two loci (11p15.4 and 13q21.1), both indicating the utility of the present strategy. These test loci, however, exhibited the same somatic CNV patterns in the other brain region.ConclusionsThe present study lists the candidate regions potentially representing cytogenomic CNVs in the brain of schizophrenia patients, although the significant but modest alterations in their brain genome doses largely remain to be characterized further.

Relative paucity of tau accumulation in the small areas with abundant Aβ42-positive capillary amyloid angiopathy within a given cortical region in the brain of patients with Alzheimer pathology

Cerebral amyloid angiopathy (CAA) is a manifestation of amyloid β-protein (Aβ) accumulation in the elderly as well as in patients with Alzheimer’s disease (AD). Two types of CAA have been noted, based on the type of vasculature in which Aβ is deposited: cerebral capillary amyloid angiopathy (capCAA) and non-capCAA. Non-capCAA is a common form of CAA that consists of Aβ deposited in arteries and arterioles. Recent information on Aβ metabolism in the brain suggests that non-capCAA is associated with Aβ secretion into the cerebrospinal fluid via the perivascular space, whereas capCAA is associated with Aβ removal to blood plasma via the capillary endothelium. Aβ40, a major and relatively soluble Aβ isoform, is deposited predominantly in non-capCAA, and Aβ42, which is insoluble and associated more closely than Aβ40 with AD, is deposited predominantly in capCAA. Studying small areas of microscopic size within a given cortical region, we found an inverse association of capCAA and senile plaques. We also found a relative paucity of tau pathology in the small areas with abundant capCAA compared with the small areas with abundant senile plaques within a cortical region with the same cytoarchitecture. We suppose that both capCAA and senile plaques indicate high Aβ42 in the neuropil but that only Aβ42 in the form of insoluble deposits in senile plaques promotes tau abnormality.

Distribution of cerebral cortical lesions in diffuse neurofibrillary tangles with calcification: a clinicopathological study of four autopsy cases showing prominent parietal lobe involvement

We investigated clinicopathologically four Japanese autopsy cases of diffuse neurofibrillary tangles with calcification (DNTC), which has been believed to be characterized by temporal or temporofrontal circumscribed lobar atrophy, and examined the distribution of their cerebral cortical lesions using hemisphere specimens. The lesions were classified into three categories (slight, moderate, and severe). Severe lesions were present in the temporal lobes and insular gyri of all four cases, consistent with the studies reported to date. In contrast, severe lesions were encountered in the parietal lobe of case 1 and moderate lesions were found in the parietal lobes of cases 2–4. Furthermore, moderate lesions of the precentral gyrus were present in cases 2–4, and moderate lesions of the postcentral gyrus were encountered in all four cases. We postulate that the distribution of cerebral cortical lesions in DNTC is more widespread than previously assumed. Our data also indicate that the unusual clinical signs of DNTC reported by several Japanese researchers, including parietal signs such as apraxia and agnosia, are roughly consistent with the topographic distribution of cerebral cortical lesions in DNTC elucidated in this study.

A method for estimating spatial resolution of real image in the Fourier domain

Spatial resolution is a fundamental parameter in structural sciences. In crystallography, the resolution is determined from the detection limit of high‐angle diffraction in reciprocal space. In electron microscopy, correlation in the Fourier domain is used for estimating the resolution. In this paper, we report a method for estimating the spatial resolution of real images from a logarithmic intensity plot in the Fourier domain. The logarithmic intensity plots of test images indicated that the full width at half maximum of a Gaussian point spread function can be estimated from the images. The spatial resolution of imaging X‐ray microtomography using Fresnel zone‐plate optics was also estimated with this method. A cross section of a test object visualized with the imaging microtomography indicated that square‐wave patterns up to 120‐nm pitch were resolved. The logarithmic intensity plot was calculated from a tomographic cross section of brain tissue. The full width at half maximum of the point spread function estimated from the plot coincided with the resolution determined from the test object. These results indicated that the logarithmic intensity plot in the Fourier domain provides an alternative measure of the spatial resolution without explicitly defining a noise criterion.

Schizophrenia: maternal inheritance and heteroplasmy of mtDNA mutations.

Role of mitochondrial pathology in schizophrenia has not been fully clarified. We searched for distinctive variants in mtDNA extracted from the gray matter of postmortem brains and from peripheral blood samples. We screened mtDNA region containing 5 genes encoding subunits of cytochrome c oxidase and ATPases. Polymorphisms not already reported in databases are recorded as unregistered rare variants. Four unregistered, non-synonymous rare variants were detected in 4 schizophrenic samples. Seven registered non-synonymous variants were not previously detected in non-psychotic Japanese samples registered in the mtSNP database. These variants may contribute to disease pathophysiology. In one family, compound mutations showed co-segregation with schizophrenia. MtDNA mutations could confer a risk for schizophrenia in the Japanese population, although further analyses are needed.

Replication of enhanced carbonyl stress in a subpopulation of schizophrenia

OXYTOCIN (OXT) SIGNALING THROUGH its receptor (OXTR) has been implicated in the pathophysiology of autism spectrum disorders (ASD). Our previous study showed a decrease in relative ratios of N-acetylaspartate to creatine (NAA/Cr) in the right medial temporal lobe (MTL) in ASD individuals. Here, we investigated the effects of OXTR on right MTL NAA/Cr in ASD individuals. This study was approved by the Ethics Committee on Genetics of the Niigata University School of Medicine. All participants and their parents provided written informed consent. DNA samples were taken from 26 ASD individuals (21 boys and five girls; mean age = 13.1 ± 3.6 years) who overlapped with those in our previous study. Detailed protocol for proton magnetic resonance spectroscopy has been previously described. We genotyped 14 single nucleotide polymorphisms (SNP) in OXTR using the TaqMan 5′-exonuclease assay. We compared mean right MTL NAA/Cr between major allele homozygotes and minor allele carriers of each SNP using ANCOVA with age and full-scale IQ as covariates. Power calculations were performed using G*Power v3.1.7 (http://www.psycho.uni-duesseldorf.de/ abteilungen/aap/gpower3). We observed nominally significant differences in mean NAA/Cr in the right MTL, including the amygdala– hippocampus region, between major allele homozygotes and minor allele carriers of two SNP: 1.14 ± 0.23 and 1.40 ± 0.21, respectively (P = 0.010) for rs9840864; and 1.18 ± 0.27 and 1.41 ± 0.18, respectively (P = 0.020) for rs11706648. Our study is in line with earlier studies reporting an association between OXTR and neuroimaging indices for the amygdala and hippocampus. There are some limitations of the present study. First, the associations between two SNP and the right MTL NAA/Cr did not survive a multiple testing correction. Sixty-two samples are needed to detect the associations with an α of 0.0036 (0.05/ 14) and a power of 0.8, under the favorable assumption that the effect size d is 1.0 and the numbers of each group are equal. Second, we used a ratio rather than absolute quantification of neurochemical metabolites. As such, we cannot determine whether NAA/Cr variation by the genetic polymorphisms was due to an alteration of NAA or Cr concentration. In conclusion, our findings obtained from an imaginggenetics approach provided preliminary evidence for the association between OXTR and neuronal function in the MTL in ASD individuals. Advances in such an approach appear to be promising for understanding ASD with diverse causes. REFERENCES

Alcoholic cerebellar degeneration: A clinicopathological study of six Japanese autopsy cases and proposed potential progression pattern in the cerebellar lesion

Alcoholic cerebellar degeneration (ACD) is one of the most common neurological complications in alcoholics. As far as we know, however, only four Japanese autopsy cases of ACD have been reported, and only limited clinicopathological data on this disease are now available in Japan. The aims of this study were: (i) to examine the clinicopathological correlation of six Japanese autopsy cases of ACD, including three asymptomatic cases; and (ii) to elucidate the pattern of progression of the cerebellar lesion in ACD. All six alcoholics were histopathologically diagnosed as having “pure” ACD without Wernicke’s encephalopathy. The characteristics of the topographical distribution of the cerebellar lesion were as follows. Symptomatic cases (cases 1–3) showed more severe and widespread change than asymptomatic cases (cases 4–6). Even in case 6, which had the mildest lesion, the anterior vermis developed a moderate change (Purkinje cell loss and narrowing of the molecular layer). In cases 4 and 5 with more severe and widespread lesions, the superior and posterior vermis and the adjacent regions of the superior hemisphere, including the anterior lobe and simple lobule, were involved. In all symptomatic cases, the anterior superior hemisphere had severe lesions involving the granular cell layer. In contrast to asymptomatic cases, all symptomatic cases also had severe to moderate lesions in the anterior inferior hemisphere. In cases 1 and 2 with the most severe lesions, the moderate to severe changes were distributed in the posterior and inferior portions of both the vermis and hemisphere. These findings suggest that in ACD, severe lesions successively develop: (i) in the anterior superior vermis; (ii) anterior superior hemisphere; (iii) anterior inferior hemisphere; and (iv) anterior inferior vermis. In addition, cerebellar symptoms may frequently occur if the anterior superior hemisphere and anterior inferior hemisphere, in addition to the anterior superior vermis, are involved.

Atypical FTLD‐FUS associated with ALS‐TDP: A case report

A 30‐year‐old Japanese woman without relevant family history presented with a behavioral abnormality followed by motor weakness about 14 years later. The patient died at age 45. Post mortem examination revealed degeneration of the frontal and temporal lobes, as well as lower motor neurons in the brainstem and spinal cord. These features were reported previously as being consistent with a diagnosis of frontotemporal lobar degeneration (FTLD) with amyotrophic lateral sclerosis (ALS). In the present study, we show abundant fused in sarcoma (FUS)‐positive dystrophic neurites but only a few neuronal cytoplasmic inclusions in the frontal and temporal cortices. TAR DNA‐binding protein 43 (TDP‐43)‐positive inclusions were absent in the cerebrum. However, TDP‐43‐positive inclusions were present in the lower motor neurons of the brainstem and spinal cord. To our knowledge, this is the first report of a case in which FTLD‐FUS pathology is of a dystrophic neurites‐predominant type and FTLD‐FUS is associated with ALS‐TDP.

Pathological features of FTLD-FUS in a Japanese population: Analyses of nine cases

We investigated the pathological features of frontotemporal lobar degeneration (FTLD) with fused in sarcoma protein (FUS) accumulation (FTLD-FUS) in the Japanese population. Only one out of nine FTLD-FUS cases showed pathology that corresponds to atypical FTLD with ubiquitin-positive inclusions (aFTLD-U). Five were basophilic inclusion body disease (BIBD) and two were neuronal intermediate filament inclusion disease. The last case was unclassifiable and was associated with dystrophic neurites (DNs) as the predominant FUS pathology. The results of this study indicate an ethnic difference from western countries. In Japan, BIBD is the most common subtype of FTLD-FUS and aFTLD-U is rare, a finding which contrasts with aFTLD-U being the most common form in western countries. Immunohistochemical analyses of these FTLD-FUS cases reveal that FUS abnormally accumulated in neuronal cytoplasmic inclusions (NCIs) and DNs has an immunohistochemical profile distinct from that of normal, nuclear FUS. NCIs and DNs are more readily stained than the nuclei by antibodies to the middle portion of FUS. Antibodies to the carboxyl terminal portion, on the other hand, stain the nuclei more readily than NCIs and DNs. Such an immunohistochemical profile of NCIs and DNs was similar to that of cytoplasmic granular FUS staining which we previously reported to be associated with dendrites and synapses. Redistribution of FUS from the nucleus to the cytoplasm could be associated with the formation of abnormal FUS aggregates in FTLD-FUS.