Identifying and reverting the adverse effects of white matter hyperintensities on cortical surface analyses

ありふれた脳の白質病変がMRI画像解析を悪化させていた --従来手法に機械学習を組み入れた改善手法の開発--. 京都大学プレスリリース. 2023-10-02.The Human Connectome Project (HCP)-style surface-based brain MRI analysis is a powerful technique that allows precise mapping of the cerebral cortex. However, the strength of its surface-based analysis has not yet been tested in the older population that often presents with white matter hyperintensities (WMHs) on T2-weighted (T2w) MRI (hypointensities on T1w MRI). We investigated T1-weighted (T1w) and T2w structural MRI in 43 healthy middle-aged to old participants. Juxtacortical WMHs were often misclassified by the default HCP pipeline as parts of the gray matter in T1w MRI, leading to incorrect estimation of the cortical surfaces and cortical metrics. To revert the adverse effects of juxtacortical WMHs, we incorporated the Brain Intensity AbNormality Classification Algorithm into the HCP pipeline (proposed pipeline). Blinded radiologists performed stereological quality control (QC) and found a decrease in the estimation errors in the proposed pipeline. The superior performance of the proposed pipeline was confirmed using an originally-developed automated surface QC based on a large database. Here we showed the detrimental effects of juxtacortical WMHs for estimating cortical surfaces and related metrics and proposed a possible solution for this problem. The present knowledge and methodology should help researchers identify adequate cortical surface biomarkers for aging and age-related neuropsychiatric disorders

A Method to Estimate the True Mahalanobis Distance from Eigenvectors of Sample Covariance Matrix

Abstract. In statistical pattern recognition, the parameters of distributions are usually estimated from training sample vectors. However, estimated parameters contain estimation errors, and the errors cause bad influence on recognition performance when the sample size is not sufficient. Some methods can obtain better estimates of the eigenvalues of the true covariance matrix and can avoid bad influences caused by estimation errors of eigenvalues. However, estimation errors of eigenvectors of covariance matrix have not been considered enough. In this paper, we consider estimation errors of eigenvectors and show the errors can be regarded as estimation errors of eigenvalues. Then, we present a method to estimate the true Mahalanobis distance from eigenvectors of the sample covariance matrix. Recognition experiments show that by applying the proposed method, the true Mahalanobis distance can be estimated even if the sample size is small, and better recognition accuracy is achieved. The proposed method is useful for the practical applications of pattern recognition since the proposed method is effective without any hyper-parameters.

Isolated Character Recognition by Searching Feature Points

Conventional segmentation technique cannot extract difficult characters such as an isolated character and a touching character. In this paper, we propose a novel character recognition method which executes segmentation and recognition simultaneously. This method enables us to extract and recognize such difficult characters. The effectiveness of the proposed method is confirmed by experiments. 1

Novel Immediate-Early Protein IE19 of Human Cytomegalovirus Activates the Origin Recognition Complex I Promoter in a Cooperative Manner with IE72

The major immediate-early (MIE) gene of human cytomegalovirus (HCMV) expresses IE86, IE72, IE55, and IE18 mRNA by differential splicing. Reverse transcription-PCR with IE72-specific primers generated an 0.65-kb cDNA from HCMV-infected fibroblast RNA, which does not correspond to any known MIE cDNA. Nucleotide sequencing revealed that the 0.65-kb cDNA is from exons 1, 2, and 3 and part of exon 4, indicating that it is derived from a novel alternatively spliced mRNA of the MIE gene. The cDNA encodes a 172-amino-acid polypeptide, termed IE19, which corresponds to an IE72 variant with an internal deletion from Val(86) to Pro(404) and appears as a band at 38 kDa on a sodium dodecyl sulfate-polyacrylamide gel. IE19 mRNA was expressed at a low level in the immediate-early, early, and late period of viral infection. IE19 was localized in nuclei, and a transient-expression assay revealed that IE19 enhances IE72-dependent activation of the HsOrc1 promoter, which is identified here as an IE72 target promoter. Another MIE protein, IE86, activated the same promoter but only weakly compared to IE72, and coexpression of IE19 did not alter the IE86-mediated transcriptional activation. In addition, IE19 did not enhance the IE72-dependent activation of the HCMV UL54 promoter. These results suggest that IE19 is a transcriptional coactivator that works with IE72

Placental Extravillous Cytotrophoblasts Persistently Express Class I Major Histocompatibility Complex Molecules after Human Cytomegalovirus Infection

Human cytomegalovirus (HCMV) downregulates the class I major histocompatibility complexes (MHCs), HLA-A and -B, in infected fibroblasts to escape from antigen-specific cytotoxic T lymphocytes. The HCMV genes responsible for the downregulation of MHCs are US2, US3, US6, and US11, which encode type I membrane proteins working at the endoplasmic reticulum (ER). However, it is largely unknown whether HCMV downregulates the class I MHC molecules in placental extravillous cytotrophoblasts (EVT), which express HLA-C, -E, and -G to protect a semiallogenic fetus from maternal natural killer (NK) cells at the fetomaternal interface. Here, we report that differentiated EVT prepared from human first-trimester chorionic villi persistently express class I MHC molecules upon HCMV infection. When these US proteins were expressed in uninfected EVT, they were localized at the ER in the entire cytoplasm. However, subsequent HCMV infection resulted in dissociation of these US proteins from the ER, which relocated toward the cell membrane. In fibroblasts, these US proteins were localized at the ER before and after HCMV infection. These results suggest that the US gene products are not integrated into ER of HCMV-infected EVT and fail to downregulate class I MHC molecules