Childcare and Child Development in Japan.

For decades, the notion has persisted in developed countries that exclusive care by the mothers is best for the development of children up to 3 years of age. To examine the veracity of this "myth of the first three years" in Japan, we examined the effects of childcare facility use for children younger than 3 years on their development using the cohorts of the Longitudinal Survey of Newborns in the 21st Century conducted in Japan. Of the 47,015 respondents to the survey, we studied the children of 5,508 mothers with university/professional education to evaluate the relationships between primary early (< 2.5 years) childcare providers during weekday daytime hours and specific development indices for the ages of 2.5, 5.5, and 8 years. At the age of 2.5 and 5.5 years, children attending childcare facilities were judged as having more advanced developmental behaviors by their parents, such as being able to compose a two-word sentence (adjusted odds ratio [aOR]: 0.22) or to express emotions (aOR: 0.81), compared with those cared for by mothers. However, at the age of 8 years, children who attended childcare facilities as infants < 2.5 years showed more aggressive behavior in interrupting people (aOR: 1.20) and causing disturbances in public (aOR: 1.26) than those cared for by mothers (after adjustment for numerous child and parental factors). Although these results are generally consistent with previous studies, issues potentially involved with problem behavior such as quality of childcare require further investigation, as does the case of children of mothers with more modest educational attainment.

Relationship between medical students' career priority and specialty choice: A nationwide multicenter survey.

BACKGROUND: The shortage of physicians in several specialties has been brought to public attention in several countries. However, little is known about factors affecting medical students' specialty choice. The objectives of our study were to illustrate medical students' career priority clusters and to assess their association with specialty preference. METHODS: We conducted a nationwide multicenter survey in 2015 at 17 medical schools. The study participants were asked their top three specialty preferences, demographic characteristics, and 14 career priority questions. Multilevel logistic regression models were used to determine the effect of each variable on student career choice. RESULTS: A total of 1264 responses were included in the analyses. The top five specialty choices were internal medicine: 833, general practice: 408, pediatrics: 372, surgery: 344, and emergency medicine: 244. An exploratory factor analysis mapped the 14 career priorities into 3-factor solution: "primary care orientation," "advanced and specific care," and "personal life orientation." Multilevel logistic regression models yielded satisfactory accuracy with the highest ROC curve (AUROC) noted in surgery (0.818), general practice (0.769), and emergency medicine (0.744). The career priorities under "primary care orientation" had positive association with choosing general practice, emergency medicine, internal medicine, and pediatrics. The "advanced and specific care" career priorities facilitated surgery and emergency medicine choice, while reducing the likelihood of choosing less procedure-oriented specialties, such as internal medicine, general practice, and pediatrics. CONCLUSIONS: Our results demonstrated medical students' career priorities and their association with specialty preference. Individualized career support may be beneficial for both medical students and each specialty fields.

Multistep thermal decomposition of granular sodium perborate tetrahydrate: a kinetic approach to complex reactions in solid-gas systems.

This article demonstrates a kinetic approach to partially overlapping multistep chemical reactions in solid-gas systems as exemplified by the thermal decomposition of granular sodium perborate tetrahydrate. This reaction proceeds via successive thermal dehydration and decomposition occurring at different temperatures to form sodium metaborate. Each reaction process comprises several kinetic steps originating from different physicochemical and physico-geometric phenomena. The partially overlapping multistep processes were characterized using available thermoanalytical techniques and microscopic observations. Conventional isoconversional kinetic analysis and empirical mathematical deconvolution were applied to each reaction process as preliminary kinetic approaches to extracting provable kinetic information. Then, each reaction process was analyzed kinetically based on a cumulative kinetic equation, i.e., kinetic deconvolution analysis. The results of the kinetic deconvolution analysis were further examined by comparison with other kinetic information for the specific kinetic steps obtained from different thermoanalytical measurements. From the results of this comprehensive kinetic approach, the kinetic features of the thermal dehydration and decomposition processes were revealed by identifying their contributing physicochemical and physico-geometric phenomena and evaluating their influences on the overall multistep processes.

What determines medical students' career preference for general practice residency training?: a multicenter survey in Japan.

BACKGROUND: Few studies have systematically explored factors affecting medical students' general practice career choice. We conducted a nationwide multicenter survey (Japan MEdical Career of Students: JMECS) to examine factors associated with students' general practice career aspirations in Japan, where it has been decided that general practice will be officially acknowledged as a new discipline. METHODS: From April to December 2015, we distributed a 21-item questionnaire to final year medical students in 17 medical schools. The survey asked students about their top three career preferences from 19 specialty fields, their demographics and their career priorities. Multivariable logistic regression was used to determine the effect of each item. RESULTS: A total of 1264 responses were included in the analyses. The top three specialty choice were internal medicine: 833 (65.9%), general practice: 408 (32.3%), and pediatrics: 372 (29.4%). Among demographic factors, "plan to inherit other's practice" positively associated with choosing general practice, whereas "having physician parent" had negative correlation. After controlling for potential confounders, students who ranked the following items as highly important were more likely to choose general practice: "clinical diagnostic reasoning (adjusted odds ratio (aOR): 1.65, 95% CI 1.40-1.94)", "community-oriented practice (aOR: 1.33, 95% CI 1.13-1.57)", and" involvement in preventive medicine (aOR: 1.18, 95% CI 1.01-1.38)". On the contrary, "acute care rather than chronic care", "mastering advanced procedures", and "depth rather than breadth of practice" were less likely to be associated with general practice aspiration. CONCLUSIONS: Our nationwide multicenter survey found several features associated with general practice career aspirations: clinical diagnostic reasoning; community-oriented practice; and preventive medicine. These results can be fundamental to future research and the development of recruitment strategies.

Re-evaluation of MIB-1 immunostaining for diagnosing hyalinizing trabecular tumour of the thyroid: semi-automated techniques with manual antigen retrieval are more accurate than fully automated techniques.

Hyalinizing trabecular tumour (HTT) immunohistochemically shows cell membranous immunoreactivity for MIB-1. This aberrant immunoreactivity is an important factor for the diagnosis of HTT. However, fully automated stainers frequently fail to confirm the immunoreactivity. The aim of this study is to investigate the cause of false negative cell membranous immunoreactivity for MIB-1 in HTT using fully automated stainers, to determine potential reasons for the problem, and to establish methods confirming cell membranous immunoreactivity for MIB-1 in HTT. Six participating institutions examined immunoreactivity for MIB-1 in 10 HTT cases using two approaches: fully automated and semi-automated methods. In the latter, antigen retrieval was carried out using manual methods adopted for routine assays at each institute. The autostainers used included the BOND-MAX, BOND-III, Benchmark XT, and Omnis systems. Using fully automated methods, institute E showed cell membranous MIB-1 positivity in all HTT cases. In contrast, at institute D, all HTT cases were negative. The positive rates of the remaining four institutes ranged from 10% to 20%. The incidence of positive cases using semi-automated methods was 100%, 90%, 90%, 30%, 80%, and 100% at institutes A, B, C, D, E, and F, respectively. We assert that antigen retrieval should be conducted manually for diagnosis of HTT; furthermore, definitively diagnosed HTT should be prepared as the external positive control.

Glyceryl monooleyl ether-based liquid crystalline nanoparticles as a transdermal delivery system of flurbiprofen: characterization and in vitro transport.

Liquid crystalline nanoparticles (LCNs) were prepared using glyceryl monooleyl ether (GME) by the modified film rehydration method. Hydrogenated lecithin (HL), 1,3-butylene glycol (1,3-BG), and Poloxamer 407 were used as additives. The prepared LCN formulations were evaluated based on particle size, small-angle X-ray diffraction (SAXS) analysis, (1)H- and (19)F-NMR spectra, and in vitro skin permeation across Yucatan micropig skin. The composition (weight percent) of the LCN formulations were GME-HL-1,3-BG (4 : 1 : 15), 4% GME-based LCN and GME-HL-1,3-BG (8 : 1 : 15), 8% GME-based LCN and their mean particle sizes were 130-175 nm. Flurbiprofen 5 and 10 mg was loaded into 4% GME-based LCN and 8% GME-based LCN systems, respectively. The results of SAXS and NMR suggested that both flurbiprofen-loaded formulations consist of particles with reverse type hexagonal phase (formation of hexosome) and flurbiprofen molecules were localized in the lipid domain through interaction of flurbiprofen with the lipid components. Flurbiprofen transport from the LCN systems across the Yucatan micropig skin was increased compared to flurbiprofen in citric buffer (pH=3.0). The 8% GME-based LCN systems was superior to the 4% GME-based LCN for flurbiprofen transport. Since the internal hexagonal phase in the 8% GME-based LCN systems had a higher degree of order compared to the 4% GME-based LCN in SAXS patterns, the 8% GME-based LCN system had a larger surface area, which might influence flurbiprofen permeation. These results indicated that the GME-based LCN system is effective in improving the skin permeation of flurbiprofen across the skin.

[Normal values of retinal sensitivity determined by macular integrity assessment].

PURPOSE: To investigate the macular sensitivity of healthy eyes of a wide age range as determined by macular Integrity Assessment (MAIA), and to investigate factors affecting macular sensitivity. SUBJECTS AND METHODS: A total of 120 eyes of 120 healthy volunteers with a best-corrected visual acuity of 20/20 or better, and of a mean age of 43.1 years. Macular sensitivity was examined by a standard grid, a 37-stimuli grid covering the central 10 degrees of the retina including one centering point. RESULTS: The central sensitivity (CS) was 28.9 dB for subjects under 20 years, 27.2 dB for subjects between 20 to 60 years, and 24.5 dB for subjects over 60 years. The average sensitivity (AS) was 29.6 dB for subjects under 20 years, and after that the sensitivity was 28.7 dB and 26.3 dB. Both CS and AS in subjects over 60 years exhibited a significantly lower sensitivity than in subjects under the age of 20 (p = 0.01). Regression analysis results indicated that the sensitivity gradually decreased by approximately 0.6 dB every 10 years (p = 0.01). The age and development of axial length were statistically significant factors influencing the decline in sensitivity (p = 0.01). When each stimulus position was investigated, the center (0 degrees) was significantly lower (26.4 dB) than surrounding stimulus positions (1 degree: 28.9 dB, 3 degrees: 28.7 dB, 5 degrees: 27.8 dB) (p = 0.01). CONCLUSION: The macular sensitivity in healthy Japanese subjects calculated by MAIA exhibited a significantly low value with aging, and sensitivity decreased with the advance in the development of axial length. The sensitivity of surrounding stimulus positions was higher than in the center (0 degrees).

Transdermal delivery of flurbiprofen from surfactant-based vesicles: particle characterization and the effect of water on in vitro transport.

Flurbiprofen loaded rigid and elastic vesicles comprising the bilayer-forming surfactant sucrose-ester laurate were prepared by the film rehydration and extrusion method. The charge-inducing agent sodium dodecyl sulfate, and the micelle-forming surfactants, sorbitan monolaurate, polyethylene glycol monolaurate, and polysorbate 20, were used to enhance elasticity. Vesicle formulations were evaluated for size, zeta potential, (1)H and (19)F nuclear magnetic resonance (NMR) spectra, and in vitro skin permeation across Yucatan micropig (YMP) skin. Vesicle formulations were stable for 2 weeks and their mean sizes were 95-135 nm. NMR spectroscopy showed that flurbiprofen molecular mobility was restricted by interaction with vesicle components because of entrapment in vesicle bilayers. Moreover, sorbitan monolaurate-containing vesicles strongly retained flurbiprofen molecules. After non-occlusive application to YMP skin, flurbiprofen transport from all vesicle formulations was superior to that of flurbiprofen alone and remarkably decreased after water vaporization. Polarization microscopy and small-angle X-ray diffraction analysis showed that the vesicle formulation was transferred to liquid crystalline state. Suppression of vesicle transition to the liquid crystalline state was observed with applications of both large quantities and diluted samples. The presence of water in the formulations was associated with maintenance of the vesicle structure and greater flurbiprofen transport across YMP skin.

Factors associated to the career choice of family medicine among Japanese physicians: the dawn of a new era.

BACKGROUND: Despite recent developments in post-graduate family medicine training in Japan, the numbers of junior doctors entering family medicine residencies are still limited. The objective of this qualitative study was to investigate the possible factors associated to the career choice of family medicine, especially in the context of the newly established family medicine programs in Japan. METHODS: From December 2010 to January 2011, we distributed a semi-structured questionnaire about career choice to 58 physician members of the Japan Primary Care Association, and 41 of them responded. Four researchers used the Modified Grounded Theory Approach (Kinoshita, 2003) for three-stage conceptualization. RESULTS: We extracted a conceptual model of the choice of newly established family medicine as a career in Japan, consisting of six categories and 77 subordinate concepts from 330 variations. The subcategories of personal background affecting the family-medicine career choice were characteristics ("self-reliance," "pioneering spirit"), career direction ("community/rural-orientedness," "multifaceted orientation") and experience (e.g., "discomfort with fragmented care"). We divided the influencing factors that were identified for career choice into supporters (e.g., "role model"), conflict of career choice (e.g., "anxiety about diverse/broad practice"), and the dawn of a new era in family medicine in Japan (e.g., "lack of social recognition," "concern about livelihood," and "too few role models"). CONCLUSIONS: Although the dawn of a new era seemed a rather negative influencer, it was unique to our study that the dawn itself could attract those with a "pioneering spirit" and an "attitude of self-training." Unlike previous studies, the positive factors such as lifestyle and the short residency program were not shown to be part of family medicine's attractiveness. In contrast, "concern about livelihood" was specific among our respondents and was related to career choice in the dawn period. "Community-orientedness" and "multifaceted orientation" (which have aspects in common with previous studies' findings) would appear to be universal regardless of cultural and medical system differences. In our study, these universal factors were also found to be part of the attractiveness of family medicine from the practitioners' viewpoints, and these factors may become great influencers for family medicine candidates.

Simple immobilization of antibody in organic/inorganic hybrid thin films for immunosensing.

Simple method to immobilize antibody in organic/inorganic hybrid thin films, prepared easily by using liquid phase deposition (LPD), was proposed to enhance the sensitivity, reproducibility and stability of immunosensing chips. The LPD method could embed a monoclonal antibody of C-reactive protein (Anti-CRP), which is mixed with poly(l-lysine) (PL) as an organic binder, on/in titanium oxide thin layer deposited onto a surface plasmon resonance (SPR) sensing chip (F(Anti-CRP-PL)), allowing simple immobilization of anti-CRP capable of CRP detection. As a control, anti-CRP was non-covalently immobilized after preparing the titanium oxide layer containing PL (SIF(Anti-CRP-PL)). Binding experiments of CRP on the prepared sensor chips were performed by SPR measurements. The CRP binding capacity of anti-CRP on F(Anti-CRP-PL) was 54% greater than that of anti-CRP on SIF (Anti-CRP-PL), suggesting that the immobilization method could retain good antigen-binding activity of anti-CRP. Reproducibility of the antigen-antibody interaction was estimated by SPR using 10mM HCl as the regeneration regent. CRP was repeatedly detected, and the detection limit was calculated to be 19.9ngmL(-1) (CV: 8.9%). By using this method, antibodies could be simply immobilized to various kinds of sensing chips for the development of immunosensing systems.

[Hypertrophic cardiomyopathy].

A 68-year-old woman with severe cardiac dysfunction due to dilated phase of hypertrophic cardiomyopathy was diagnosed with sigmoid cancer and scheduled for high anterior resection. Preoperative left ventricular ejection fraction (EF) was 16% by transthoracic echocardiography. After placement of an epidural catheter at the T12-L1 interspace, and artery catheters in the left radial artery for invasive blood pressure monitoring and in the right femoral artery for stand-by IABE general anesthesia was induced by midazolam, fentanyl and sevoflurane, and maintained with sevoflurane. Analgesia was obtained by epidural administration of 1% lidocaine and 0.2% ropivacaine. A central venous catheter was placed in the right internal jugular vein through which dobutamine was infused throughout the operation. Cardiac function monitored by transesophageal echocardiography showed EF of 9% just after insertion. After arbitrary administration of phenylephrine and landiolol, the operation and anesthesia were completed without serious problems. However, congestive heart failure worsened on postoperative day 2, and was improved by increasing dobutamine and by administration of milrinone.

Preparation of (001)-oriented Pb(Zr,Ti)O3 thin films and their piezoelectric applications.

Preparation of (001)-oriented Pb(Zr,Ti)O(3) (PZT) thin films and their applications to a sensor and actuators were investigated. These thin films, which have a composition close to the morphotropic phase boundary, were epitaxially grown on (100)MgO single-crystal substrates by RF magnetron sputtering. These (001)-oriented PZT thin films could be obtained on various kinds of substrates, such as glass and Si, by introducing (100)-oriented MgO buffer layers. In addition, the (001) oriented PZT thin films could be obtained on Si substrates without buffer layers by optimizing the sputtering conditions. All of these thin films showed excellent piezoelectric properties without the need for poling treatment. The PZT thin films on the MgO substrates had a high piezoelectric coefficient, d(31), of -100 pm/V, and an extremely low relative dielectric constant, epsilon(r), of 240. The PZT thin films on Si substrate had a very high d(31) of -150 pm/V and an epsilon(r) = 700. These PZT thin films were applied to an angular rate sensor with a tuning fork in a car navigation system, to a dual-stage actuator for positioning the magnetic head of a high-density hard disk drive, and to an actuator for an inkjet printer head for industrial on-demand printers.

Molecular genetic alterations and gene expression profile of a malignant rhabdoid tumor of the kidney.

Malignant rhabdoid tumor of the kidney (MRTK) is a rare but highly aggressive tumor in children, and knowledge about the molecular signature of this tumor is limited. We report the molecular genetic alterations and gene expression profile of an MRTK tumor that arose in a 4-month-old Japanese girl. Fluorescence in situ hybridization and Southern blot analyses revealed a homozygous deletion of an approximately 0.29-Mb genomic region bordered by the Rgr and DDT genes in these tumor cells. This deleted region encodes SMARCB1, a candidate tumor suppressor gene for MRTK. Using a high-density oligonucleotide DNA array, we found increased expression of 25 genes, including genes involved in the cell cycle (10 genes), DNA replication (3 genes), cell growth (5 genes), and cell proliferation (5 genes), in this MRTK tumor sample, compared with a noncancerous kidney (NK) sample. On the other hand, 64 genes, including 4 genes regulating apoptosis, were found to show decreased expression in this MRTK tumor sample, compared with the NK sample. Among these alterations, we found alterations of expression of some genes, such as IGF2, MDK, TP53, and TNFSF10, in this MRTK tumor, as described previously. The molecular genetic alterations and altered pattern of gene expression found in this case may have contributed to the biological characteristics of the MRTK tumor that arose in our patient.

Screening for control genes in rat global cerebral ischemia using high-density oligonucleotide array.

From conventional relative gene expression analyses (Northern blotting, in situ hybridization, and RT-PCR), it has been reported that the expression of control genes, such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and beta-actin, used as references may be affected by ischemia. Therefore, we extended searching and evaluation at the mRNA level of transcripts whose expression levels were not changed by cerebral ischemia, using a high-density oligonucleotide array and statistical analysis in a rat global cerebral ischemia and reperfusion model. We added a hyperthermic factor and localization factor to ischemia and identified transcripts with a stable expression level under conditions even more disadvantageous than ischemia only. Screening of more than 8,000 transcripts with the Rat Genome U34A array yielded 28 transcripts, which we listed and classified according to their expression level. Widely used control genes, GAPDH and beta-actin, were not included, although cyclophilin A was included. In addition, we conducted a functional classification based on gene ontology. Under the functional classification of the 28 transcripts, many genes tended to be associated with metabolism. In conclusion, use of several transcripts is recommended, such as those we identified, as references in the analysis of gene expression in pathological models of ischemia.

Alteration of serum/glucocorticoid regulated kinase-1 (sgk-1) gene expression in rat hippocampus after transient global ischemia.

Expression of the serum/glucocorticoid regulated kinase-1 (sgk-1) gene has been reported to be induced by various stress stimuli such as hyper- or hypo-osmotic stress, UV irradiation, and heat shock stress; however, its association with global ischemia in the brain has not been studied. Using high-density oligonucleotide array analysis, we found that the sgk-1 gene was one of the genes showing alteration of expression in the rat hippocampus during 1-4 h of reperfusion after 10 min of transient global cerebral ischemia. Using TaqMan RT-PCR analysis, we confirmed an increased level of sgk-1 gene expression with statistical significance in the rat hippocampus at 2 h of reperfusion after 10 min of transient global cerebral ischemia. Using in situ hybridization (ISH) analysis, the increased level of sgk-1 gene expression was found to localize in pyramidal cells of CA2 and CA3 regions of the hippocampus after 2 h of reperfusion. These results provide an insight into the alterations of sgk-1 gene expression in the rat hippocampus after transient global cerebral ischemia.

Profiling of genes associated with transcriptional responses in mouse hippocampus after transient forebrain ischemia using high-density oligonucleotide DNA array.

Several cascades of changes in gene expression have been shown to be involved in the neuronal injury after transient cerebral ischemia; however, little is known about the profile of genes showing alteration of expression in a mouse model of transient forebrain ischemia. We analyzed the gene expression profile in the mouse hippocampus during 24 h of reperfusion, after 20 min of transient forebrain ischemia, using a high-density oligonucleotide DNA array. Using statistical filtration (Welch's ANOVA and Welch's t-test), we identified 25 genes with a more than 3.0-fold higher or lower level of expression on average, with statistical significance set at p<0.05, in at least one ischemia-reperfusion group than in the sham group. Using unsupervised clustering methods (hierarchical clustering and k-means clustering algorithms), we identified four types of gene expression pattern that may be associated with the response of cell populations in the hippocampus to an ischemic insult in this mouse model. Functional classification of the 25 genes demonstrated alterations of expression of several kinds of biological pathways, regulating transcription (Bhlhb2, Jun, c-fos, Egr1, Egr2, Fosb, Junb, Ifrd1, Neurod6), the cell cycle (c-fos, Fosb, Jun, Junb, Dusp1), stress response (Dusp1, Dnajb1, Dnaja4), chaperone activity (Dnajb1, Dnaja4) and cell death (Ptgs2, Gadd45g, Tdag51), in the mouse hippocampus by 24 h of reperfusion. Using hierarchical clustering analysis, we also found that the same 25 genes clearly discriminated between the sham group and the ischemia-reperfusion groups. The alteration of expression of 25 genes identified in this study suggests the involvement of these genes in the transcriptional response of cell populations in the mouse hippocampus after transient forebrain ischemia.

Transcriptional profiling in hepatoblastomas using high-density oligonucleotide DNA array.

Hepatoblastoma is a common hepatic tumor in children. Although evidence regarding cytogenetic and molecular genetic alterations in hepatoblastomas has been reported, the molecular events affecting the biologic characteristics of this tumor, including alterations of the gene expression profile, are largely unknown. To identify genes differentially expressed between nondiseased liver (NDL) and hepatoblastoma tumor (HBT), we analyzed the gene expression profile in 14 NDL and 16 HBT samples using a high-density oligonucleotide DNA array. Using Mann-Whitney U test followed by the k-nearest neighbor algorithm, we identified 26 genes (predictor genes) that were able to assign unknown samples derived from NDL and HBT to either the NDL group or HBT group with 100% accuracy. Using a cross-validation approach, we confirmed that the k-nearest neighbor algorithm assigned the particular samples derived from NDL and HBT to either the NDL or HBT group with 93.3% (28/30 samples) accuracy. In the 26 predictor genes, we found alteration of the expression of genes regulating cell division (NAP1L1, STMN1, CCNG2, and CDC7L1) and tumor cell growth (IGF2 and IGFBP4) in HBT. Four predictor genes (ETV3, TPR, CD34, and NR1I3) were also found to be mapped to the chromosomal region 1q21 approximately q32, which has been reported to be frequently involved in the development of hepatoblastoma. The findings obtained in this study suggest that alteration of the expression of some genes regulating cell division and tumor cell growth may be characteristics of the gene expression profile in HBT, and that alteration of the expression of the four predictor genes mapped to chromosomal region 1q21 approximately q32 may also contribute to the differences in gene expression profile between NDL and HBT.

Localization of thioredoxin-interacting protein (TXNIP) mRNA in epithelium of human gastrointestinal tract.

Thioredoxin-interacting protein (TXNIP) is a negative regulator of thioredoxin. However, its role in the gastrointestinal (GI) epithelium is as yet unknown. Using in situ hybridization, we demonstrated that mRNA of TXNIP was differentially expressed in the epithelium of the human GI tract. TXNIP transcript was especially prominent in terminal differentiated cells. TXNIP was also highly expressed in lymphocytes in the lymphoid follicles. Our results suggest a new potential role of TXNIP in the differentiation of epithelial cells and in mucosal immunity of the GI tract.

Profiling of genes differentially expressed between fetal liver and postnatal liver using high-density oligonucleotide DNA array.

The liver is an essential organ in humans not only for the production and storage of energy but also for detoxification of chemical compounds, but knowledge about changes in the gene expression profile in the human liver during the prenatal and postnatal periods is limited. Profiling of genes differentially expressed between the fetal liver (FL) and the postnatal liver (PNL) is one of the methods to investigate candidates affecting the difference in biological characteristics between FL and PNL. To identify genes differentially expressed between FL and PNL (childhood and adult liver), we analyzed the gene expression profiles across 9 FL and 14 PNL samples using a high-density oligonucleotide DNA array. Using Mann-Whitney U test followed by k-nearest-neighbors (supervised learning method) and hierarchical clustering (unsupervised learning method) algorithms, we found 33 genes clearly discriminating between the FL group and PNL group. The functional classification of the 33 genes identified was related to several kinds of biological pathways, regulating the cell cycle (PCNA, CDC7L1, CCND3, YWHA1, PKMYT1), DNA replication and repair (RFC4, RECQ2, PCNA, NAP1L1), cell growth (IGF2, IGFBP2, PRSS11), hormonal signals (AR, SRD5A1, NR1I3), and cellular metabolism (E2-EPF, WWP1, CYP2C9, CYP2E1, CYP2A6, CYP2A7, CYP2A13, CYP4F2, CYP3A4, DDT). The results presented herein provide evidence of a differential expression profile of genes regulating the cell cycle, DNA replication and repair, cell growth, regulation of hormonal signals, and cellular metabolism, between FL and PNL in humans. The 33 genes identified in this study are suggested to be useful markers clearly discriminating between FL and PNL using the gene expression profile.