Cerebral edema associated with diabetic ketoacidosis: Two case reports

Background

Diabetic ketoacidosis (DKA) is associated with a high mortality rate, especially if cerebral edema develops during the disease course. It is rarer and more severe in adults than in children. We present cases of two patients with cerebral edema-related DKA.

Case presentation

The first patient was a 38-year-old man with diabetes mellitus who presented with DKA-related disturbed consciousness. Although glycemic correction was performed slowly, he showed pupil dilation 11 h later. He underwent emergency ventricular drainage, but died of cerebral herniation. The second patient was a 25-year-old woman who presented with impaired consciousness secondary to DKA. Head computed tomography showed subarachnoid hemorrhage and cerebral edema. No related intraoperative findings were observed; it was concluded that the first computed tomography scan revealed pseudo-subarachnoid hemorrhage.

Conclusion

Diabetic ketoacidosis-related cerebral edema develops despite treatment according to guidelines and is difficult to predict. Therefore, adult patients should be treated cautiously during DKA management.

Chirality-Induced Spin Polarization over Macroscopic Distances in Chiral Disilicide Crystals

A spin-polarized state is examined under charge current at room temperature without magnetic fields in chiral disilicide crystals NbSi_{2} and TaSi_{2}. We found that a long-range spin transport occurs over ten micrometers in these inorganic crystals. A distribution of crystalline grains of different handedness is obtained via location-sensitive electrical transport measurements. The sum rule holds in the conversion coefficient in the current-voltage characteristics. A diamagnetic nature of the crystals supports that the spin polarization is not due to localized electron spins but due to itinerant electron spins. A large difference in the strength of antisymmetric spin-orbit interaction associated with 4d electrons in Nb and 5d ones in Ta is oppositely correlated with that of the spin polarization. A robust protection of the spin polarization occurs over long distances in chiral crystals.

Comparison of direct anterior approach and posterior approach total hip arthroplasty: More than 5-year follow-up

Purpose

In this study we compare the surgical outcome of DAA and PA more than 5-year follow-up evaluation.

Materials and methods

This is a retrospective cohort single-surgeon study of consecutive primary THAs using the DAA or PA.

Results

There was no significant difference in HHS and JHEQ score. Posterior dislocation occurred in 4 cases in PA group (9.5%, p = 0.038) while there was no dislocation in DAA group.

Conclusion

Both DAA and PA yield good results at the final follow-up in terms of function, quality of life, and survivorship. However dislocation was significantly higher in PA group.

A life-table analysis of the intrauterine fate of malformed human embryos and fetuses

BACKGROUND

Various malformations are frequently encountered in spontaneously aborted embryos and fetuses. Thus, spontaneous abortion appears to be a screening device for abnormal conceptuses ("teratothanasia"). However, the prevalence rate of abnormal conceptuses at each gestational stage is unknown and the true picture of prenatal natural selection remains to be elucidated.

METHODS

An in utero life-table of normal and malformed human conceptuses was constructed utilizing the data for human embryos and fetuses procured after therapeutic abortion and kept in the Kyoto Collection of Human Embryos (N = 21,798).

RESULTS

The prevalence of external major malformations was estimated to be 9.6% at the start of the fifth week after fertilization and drop to 9.2, 8.5, and 7.5% during the following weeks. The malformation rate decreased to 5.3% by the end of the embryonic period (the eighth week), 2.8% by the 13th week and 1% at term. The prenatal mortality rate of externally malformed conceptuses between the fifth week of gestation and term was 92.8%, whereas the corresponding rate for externally normal embryos was 24.9%. The prenatal mortality rates of embryos with neural tube defects and holoprosencephaly were 96.0 and 99.7%, respectively.

CONCLUSIONS

Abnormal development occurs frequently early in development and many of the malformed embryos/fetuses die in utero to end in spontaneous abortion. Natural prenatal screening of abnormal conceptuses most likely contributes to reducing the birth of malformed infants.

25th anniversary of the Berlin workshop on developmental toxicology: DevTox database update, challenges in risk assessment of developmental neurotoxicity and alternative methodologies in bone development and growth

25 years after the first Berlin Workshop on Developmental Toxicity this 10th Berlin Workshop aimed to bring together international experts from authorities, academia and industry to consider scientific, methodologic and regulatory aspects in risk assessment of developmental toxicity and to debate alternative strategies in testing developmental effects in the future. Proposals for improvement of the categorization of developmental effects were discussed as well as the update of the DevTox database as valuable tool for harmonization. The development of adverse outcome pathways relevant to developmental neurotoxicity (DNT) was debated as a fundamental improvement to guide the screening and testing for DNT using alternatives to animal methods. A further focus was the implementation of an in vitro mechanism-based battery, which can support various regulatory applications associated with the assessment of chemicals and mixtures. More interdisciplinary and translation research should be initiated to accelerate the development of new technologies to test developmental toxicity. Technologies in the pipeline are (i) high throughput imaging techniques, (ii) models for DNT screening tests, (iii) use of computer tomography for assessment of thoracolumbar supernumerary ribs in animal models, and (iv) 3D biofabrication of bone development and regeneration tissue models. In addition, increased collaboration with the medical community was suggested to improve the relevance of test results to humans and identify more clinically relevant endpoints. Finally, the participants agreed that this conference facilitated better understanding innovative approaches that can be useful for the identification of developmental health risks due to exposure to chemical substances.

Chirality-Induced Spin-Polarized State of a Chiral Crystal CrNb_{3}S_{6}

Chirality-induced spin transport phenomena are investigated at room temperature without magnetic fields in a monoaxial chiral dichalcogenide CrNb_{3}S_{6}. We found that spin polarization occurs in these chiral bulk crystals under a charge current flowing along the principal c axis. Such phenomena are detected as an inverse spin Hall signal which is induced on the detection electrode that absorbs polarized spin from the chiral crystal. The inverse response is observed when applying the charge current into the detection electrode. The signal sign reverses in the device with the opposite chirality. Furthermore, the spin signals are found over micrometer length scales in a nonlocal configuration. Such a robust generation and protection of the spin-polarized state is discussed based on a one-dimensional model with an antisymmetric spin-orbit coupling.

Categorization of fetal external findings in developmental toxicology studies by the Terminology Committee of the Japanese Teratology Society

Categorization of fetal external findings in common laboratory animals, intended to make the agreement at Berlin Workshop in 2014 more practical, was proposed by the Terminology Committee of the Japanese Teratology Society at the Workshop in the 55th Japanese Teratology Society Annual Meeting in 2015. In the Workshop, 73 external findings, which had been categorized as "Gray zone" anomalies but not as "Malformation" or "Variation" in the 2014 Berlin Workshop, were discussed and classified as Malformation, "Non-structural abnormality," Variation, and "Not applicable." The proposal was based on the results of a survey conducted in 2014, where 20 facilities (including pharmaceutical, chemical, and pesticide companies and contract laboratories) and 2 selected expert teratologists in Japan were asked for their opinions on the categorization of these findings. Based on the discussion, Japanese Teratology Society members have agreed that 42 out of the 73 findings can be classified as Malformations (38), Non-structural abnormalities (3), Malformations/Non-structural abnormalities (1), and Variations (0), while the remaining 31 findings were recommended to be categorized as Not applicable for fetuses. The details of the classification are shown on the website of the Japanese Teratology Society (http://www.umin.ac.jp/cadb/External.pdf).

Clinical and Demographic Evaluation of a Holoprosencephaly Cohort From the Kyoto Collection of Human Embryos

Holoprosencephaly (HPE) is a genetically and phenotypically heterogeneous disorder involving developmental defects. HPE is a rare condition (1/10,000-20,000 newborns) but can be found as frequently as 1/250 among conceptions, suggesting that most HPE embryos are incompatible with postnatal life and result in spontaneous abortions during the first trimester of gestation. Beginning in 1961, the Kyoto University in Japan collected over 44,000 human conceptuses in collaboration with several hundred domestic obstetricians. Over 200 cases of HPE have been identified in the Kyoto collection, which represents the largest single cohort of HPE early stage embryo specimens. In this study, we present a comprehensive clinical and demographic evaluation of this HPE cohort prior to genomic analysis. The total percentage of the threatened abortion among HPE embryos in the Kyoto collection was 67%. Almost 20% of the women with embryos affected by HPE had experienced spontaneous miscarriage. In addition, there was a significant tendency that the mothers with HPE cases had fewer live births than the control. Moreover, in 70% of cases, the mother reported bleeding during pregnancy, a higher percentage than expected, indicating that most of the conceptions with HPE embryos tend to be terminated spontaneously. There were no differences in smoking between mothers with HPE affected and unaffected pregnancies; however, alcohol use was higher in women with pregnancies affected by HPE. In this study, we precisely characterize the phenotype and environmental influences of embryos affected by HPE allowing the future leveraging of genomic technologies to further understand the genetics of forebrain development. Anat Rec, 301:973-986, 2018. © 2018 Wiley Periodicals, Inc.

Elevated Na+/H+ exchanger-1 expression enhances the metastatic collective migration of head and neck squamous cell carcinoma cells

Cancer cells can migrate as collectives during invasion and/or metastasis; however, the precise molecular mechanisms of this form of migration are less clear compared with single cell migration following epithelial-mesenchymal transition. Elevated Na⁺/H⁺ exchanger1 (NHE1) expression has been suggested to have malignant roles in a number of cancer cell lines and in vivo tumor models. Furthermore, a metastatic human head and neck squamous cell carcinoma (HNSCC) cell line (SASL1m) that was isolated based on its increased metastatic potential also exhibited higher NHE1 expression than its parental line SAS. Time-lapse video recordings indicated that both cell lines migrate as collectives, although with different features, e.g., SASL1m was much more active and changed the direction of migration more frequently than SAS cells, whereas locomotive activities were comparable. SASL1m cells also exhibited higher invasive activity than SAS in Matrigel invasion assays. shRNA-mediated NHE1 knockdown in SASL1m led to reduced locomotive and invasive activities, suggesting a critical role for NHE1 in the collective migration of SASL1m cells. SASL1m cells also exhibited a higher metastatic rate than SAS cells in a mouse lymph node metastasis model, while NHE1 knockdown suppressed in vivo SASL1m metastasis. Finally, elevated NHE1 expression was observed in human HNSCC tissue, and Cariporide, a specific NHE1 inhibitor, reduced the invasive activity of SASL1m cells, implying NHE1 could be a target for anti-invasion/metastasis therapy.

Magnetic resonance microscopy of chemically fixed human embryos at high spatial resolution

We acquired magnetic resonance (MR) microscopic images of chemically fixed human embryos of Carnegie stages 16 to 22 with a large image matrix (256 × 256 × 512) using an MR microscope that we developed with a 9.4-tesla vertical wide-bore superconducting magnet and a dual-channel receiver system to extend the dynamic range of the MR signal. The images showed clear anatomical structures at spatial resolutions of (40 µm)(3) to (60 µm)(3). We concluded that the experimental technique we developed will aid construction of the next anatomical database of the collection of chemically fixed human embryos.

A detailed comparison of mouse and human cardiac development

BACKGROUND

Mouse mutants are used to model human congenital cardiovascular disease. Few studies exist comparing normal cardiovascular development in mice vs. humans. We carried out a systematic comparative analysis of mouse and human fetal cardiovascular development.

METHODS

Episcopic fluorescence image capture (EFIC) was performed on 66 wild-type mouse embryos from embryonic day (E) 9.5 to birth; 2-dimensional and 3-dimensional datasets were compared with EFIC and magnetic resonance images from a study of 52 human fetuses (Carnegie stage 13-23).

RESULTS

Time course of atrial, ventricular, and outflow septation were outlined and followed a similar sequence in both species. Bilateral venae cavae and prominent atrial appendages were seen in the mouse fetus; in human fetuses, atrial appendages were small, and a single right superior vena cava was present. In contrast to humans with separate pulmonary vein orifices, a pulmonary venous confluence with one orifice enters the left atrium in mice.

CONCLUSION

The cardiac developmental sequences observed in mouse and human fetuses are comparable, with minor differences in atrial and venous morphology. These comparisons of mouse and human cardiac development strongly support that mouse morphogenesis is a good model for human development.

Roles of retinoic acid signaling in normal and abnormal development of the palate and tongue

Palatogenesis involves various developmental events such as growth, elevation, elongation and fusion of opposing palatal shelves. Extrinsic factors such as mouth opening and subsequent tongue withdrawal are also needed for the horizontal elevation of palate shelves. Failure of any of these steps can lead to cleft palate, one of the most common birth defects in humans. It has been shown that retinoic acid (RA) plays important roles during palate development, but excess RA causes cleft palate in fetuses of both rodents and humans. Thus, the coordinated regulation of retinoid metabolism is essential for normal palatogenesis. The endogenous RA level is determined by the balance of RA-synthesizing (retinaldehyde dehydrogenases: RALDHs) and RA-degrading enzymes (CYP26s). Cyp26b1 is a key player in normal palatogenesis. In this review, we discuss recent progress in the study of the pathogenesis of RA-induced cleft palate, with special reference to the regulation of endogenous RA levels by RA-degrading enzymes.

The regulation of endogenous retinoic acid level through CYP26B1 is required for elevation of palatal shelves

BACKGROUND

In previous studies, we investigated the effects of excess retinoic acid (RA) during palatogenesis by RA administration to pregnant mice. In the present study, we deleted Cyp26b1, one of the RA-degrading enzymes, to further study the effects of excess RA in the normal developing palate and to understand how endogenous levels of RA are regulated.

RESULTS

Excess RA, due to the absence of Cyp26b1, targets cells in the bend region of the palatal shelves and inhibits their horizontal elevation, leading to cleft palate. An organ culture of Cyp26b1-/- palatal shelves after tongue removal did not rescue the impaired elevation of the palatal shelves. The expression of Fgf10, Bmp2, and Tbx1, important molecules in palatal development, was down-regulated. Cell proliferation was decreased in the bend region of palatal shelves. Tongue muscles were hypoplastic and/or missing in Cyp26b1-/- mice.

CONCLUSIONS

We demonstrated that CYP26B1 is essential during palatogenesis. Excess RA due to the lack of Cyp26b1 suppresses the expression of key regulators of palate development in the bend region, resulting in a failure in the horizontal elevation of the palatal shelves. The regulation of RA signaling through CYP26B1 is also necessary for the development of tongue musculature and for tongue depression.

Muscle patterning in mouse and human abdominal wall development and omphalocele specimens of humans

Human omphalocele is a congenital defect of the abdominal wall in which the secondary abdominal wall structures (muscle and connective tissue) in an area centered around the umbilicus are replaced by a translucent membranous layer of tissue. Histological examination of omphalocele development and moreover the staging of normal human abdominal wall development has never been described. We hypothesized that omphalocele is the result of an arrest in the secondary abdominal wall development and predicted that we would observe delays in myoblast maturation and an arrest in secondary abdominal wall development. To look for evidence in support of our hypothesis, we performed a histological analysis of normal human abdominal wall development and compared this to mouse. We also conducted the first histological analysis of two human specimens with omphalocele. In these two omphalocele specimens, secondary abdominal wall development appears to have undergone an arrest around Carnegie Stage 19. In both specimens disruptions in the unidirectional orientation of myofibers were observed in the external and internal obliques, and rectus abdominis but not in the transversus abdominis. These latter findings support a model of normal abdominal wall development in which positional information instructs the orientation of myoblasts as they organize into individual muscle groups.

Harmonization of description and classification of fetal observations: achievements and problems still unresolved: report of the 7th Workshop on the Terminology in Developmental Toxicology Berlin, 4-6 May 2011

This article summarizes the 7th Workshop on the Terminology in Developmental Toxicology held in Berlin, May 4-6, 2011. The series of Berlin Workshops has been mainly concerned with the harmonization of terminology and classification of fetal anomalies in developmental toxicity studies. The main topics of the 7th Workshop were knowledge on the fate of anomalies after birth, use of Version 2 terminology for maternal-fetal observations and non-routinely used species, reclassification of "grey zone" anomalies and categorization of fetal observations for human health risk assessment. The paucity of data on health consequences of the postnatal permanence of fetal anomalies is relevant and further studies are needed. The Version 2 terminology is an important step forward and the terms listed in this glossary are considered also to be appropriate for most observations in non-routinely used species. Continuation of the Berlin Workshops was recommended. Topics suggested for the next Workshop were grouping of fetal observations for reporting and statistical analysis.

Imaging of the human embryo with magnetic resonance imaging microscopy and high-resolution transvaginal 3-dimensional sonography: human embryology in the 21st century

OBJECTIVE

This article illustrates early human development, demonstrated by magnetic resonance (MR) microscopy and computer graphics on human embryo specimens, and advanced 3-dimensional (3D) sonography in clinical obstetrics.

STUDY DESIGN

Fixed human embryo specimens were imaged by MR microscopy coupled with computer graphics technology. Transvaginal 3D sonography was used to examine embryos in ongoing gestations and compare embryological findings.

RESULTS

Advances in MR microscopy allowed detailed visualization of embryo specimens. Computational techniques allowed reconstruction of tomographic images to render them as 3D structures. High-resolution transvaginal 3D sonography produced images that demonstrated the neural tube from week 6; brain anatomy and vasculature from week 8; and craniofacial morphology and other structures from week 11.

CONCLUSION

MR microscopy is a novel technique that enables nondestructive, high-resolution imaging of embryo specimens. On the other hand, 3D sonoembryology allows detailed anatomical visualization in vivo and is the basis for the assessment of anomalies as well as human development.

Developmental atlas of the early first trimester human embryo

Rapid advances in medical imaging are facilitating the clinical assessment of first-trimester human embryos at increasingly earlier stages. To obtain data on early human development, we used magnetic resonance (MR) imaging and episcopic fluorescence capture (EFIC) to acquire digital images of human embryos spanning the time of dynamic tissue remodeling and organogenesis (Carnegie stages 13 to 23). These imaging data sets are readily resectioned digitally in arbitrary planes, suitable for rapid high-resolution three-dimensional (3D) observation. Using these imaging datasets, a web-accessible digital Human Embryo Atlas (http://apps.devbio.pitt.edu/humanatlas/) was created containing serial 2D images of human embryos in three standard histological planes: sagittal, frontal, and transverse. In addition, annotations and 3D reconstructions were generated for visualizing different anatomical structures. Overall, this Human Embryo Atlas is a unique resource that provides morphologic data of human developmental anatomy that can accelerate basic research investigations into developmental mechanisms that underlie human congenital anomalies.

Methylnitrosourea induces neural progenitor cell apoptosis and microcephaly in mouse embryos

BACKGROUND

Prenatal exposure to methylnitrosourea (MNU), an alkylating agent, induces microcephaly in mice. However, its pathogenetic mechanism has not been clarified, especially that in the development of the cerebral cortex.

METHODS

ICR mice were treated with MNU at 10 mg/kg intraperitoneally on day 13.5 or 15.5 of gestation, and the embryos were observed histologically 24 hr after treatment with MNU or at term. To clarify the pathogenesis of microcephaly and histological changes, especially apoptosis, neurogenesis, and neural migration/positioning, we performed histological analysis employing a cell-specific labeling experiment using thymidine-like substances (BrdU, CldU, and IdU) and markers of neurons/neural stem cells.

RESULTS

Histological abnormalities of the dorsal telencephalon, and the excessive cell death of proliferative neural progenitor/stem cells were noted in the MNU-treated embryos. The highest frequencies of cell death occurred at 36 hr after MNU treatment, and little or no neurogenesis was observed in the ventricular zone of the dorsal telencephalon. Abnormality of the radial migration was caused by the reduction of radial fibers in the radial glias. Birth-date analysis revealed the abnormal positioning of neurons and aberrant lamination of the cerebral cortex.

CONCLUSIONS

Our data suggest that prenatal exposure to MNU induces the excessive cell death of neural precursor/stem cells, and the defective development of the cerebral cortex, resulting in microcephalic abnormalities.

Early pathogenesis of holoprosencephaly

Holoprosencephaly (HPE) is one of the most common malformations encountered in early human embryos. It is assumed that more than 90% of HPE embryos die in utero and are eliminated by spontaneous abortion. Embryonic HPE displays some characteristic craniofacial phenotypes, which are not necessarily comparable to those in postnatal HPE cases. In this article, we summarize our studies on HPE in human embryos and discuss the pathogenesis of HPE malformations.

Dysregulation of the PDGFRA gene causes inflow tract anomalies including TAPVR: integrating evidence from human genetics and model organisms

Total anomalous pulmonary venous return (TAPVR) is a congenital heart defect inherited via complex genetic and/or environmental factors. We report detailed mapping in extended TAPVR kindreds and mutation analysis in TAPVR patients that implicate the PDGFRA gene in the development of TAPVR. Gene expression studies in mouse and chick embryos for both the Pdgfra receptor and its ligand Pdgf-a show temporal and spatial patterns consistent with a role in pulmonary vein (PV) development. We used an in ovo function blocking assay in chick and a conditional knockout approach in mouse to knock down Pdgfra expression in the developing venous pole during the period of PV formation. We observed that loss of PDGFRA function in both organisms causes TAPVR with low penetrance (approximately 7%) reminiscent of that observed in our human TAPVR kindreds. Intermediate inflow tract anomalies occurred in a higher percentage of embryos (approximately 30%), suggesting that TAPVR occurs at one end of a spectrum of defects. We show that the anomalous pulmonary venous connection seen in chick and mouse is highly similar to TAPVR discovered in an abnormal early stage embryo from the Kyoto human embryo collection. Whereas the embryology of the normal venous pole and PV is becoming understood, little is known about the embryogenesis or molecular pathogenesis of TAPVR. These models of TAPVR provide important insight into the pathogenesis of PV defects. Taken together, these data from human genetics and animal models support a role for PDGF-signaling in normal PV development, and in the pathogenesis of TAPVR.

Sonic hedgehog is involved in formation of the ventral optic cup by limiting Bmp4 expression to the dorsal domain

Accumulating evidence suggests that Sonic hedgehog (Shh) signaling plays a crucial role in eye vesicle patterning in vertebrates. Shh promotes expression of Pax2 in the optic stalk and represses expression of Pax6 in the optic cup. Shh signaling contributes to establishment of both proximal-distal and dorsal-ventral axes by activating Vax1, Vax2, and Pax2. In the dorsal part of the developing retina, Bmp4 is expressed and antagonizes the ventralizing effects of Shh signaling through the activation of Tbx5 expression in chick and Xenopus. To examine the roles of Shh signaling in optic cup formation and optic stalk development, we utilized the Smoothened (Smo) conditional knockout (CKO) mouse line. Smo is a membrane protein which mediates Shh signaling into inside of cells. Cre expression was driven by Fgf15 enhancer. The ventral evagination of the optic cup deteriorated from E10 in the Smo-CKO, whereas the dorsal optic cup and optic stalk develop normally until E11. We analyzed expression of various genes such as Pax family (Pax2/Pax6), Vax family (Vax1/Vax2) and Bmp4. Bmp4 expression was greatly upregulated in the optic vesicle by the 21-somite stage. Then Vax1/2 expression was decreased at the 20- to 24-somite stages. Pax2/6 expression was affected at the 27- to 32-somite stages. Our data suggest that the effects of the absence of Shh signaling on Vax1/Vax2 are mediated through increased Bmp4 expression throughout the optic cup. Also unchanged patterns of Raldh2 and Raldh3 suggest that retinoic acid is not the downstream to Shh signaling to control the ventral optic cup morphology.

Mechanism of skull suture maintenance and interdigitation

Skull sutures serve as growth centers whose function involves multiple molecular pathways. During periods of brain growth the sutures remain thin and straight, later developing complex fractal interdigitations that provide interlocking strength. The nature of the relationship between the molecular interactions and suture pattern formation is not understood. Here we show that by classifying the molecules involved into two groups, stabilizing factors and substrate molecules, complex molecular networks can be modeled by a simple two-species reaction-diffusion model that recapitulates all the known behavior of suture pattern formation. This model reproduces the maintenance of thin sutural tissue at early stages, the later modification of the straight suture to form osseous interdigitations, and the formation of fractal structures. Predictions from the model are in good agreement with experimental observations, indicating that the model captures the essential nature of the interdigitation process.

Intrauterine environment-genome interaction and children's development (3): Assisted reproductive technologies and developmental disorders

In vitro fertilization (IVF) and other assisted reproductive technologies (ART) are widely used clinically as infertility treatments. Although ART procedures are generally considered safe, some studies have suggested an increase in the occurrence of major malformations and some other complications in babies conceived by ART. Further, it has recently been suggested that ART are associated with imprinting disorders in the offspring such as Beckwith-Wiedemann syndrome and Angelman syndrome. We review the human and animal studies investigating the outcome of ART pregnancies and discuss the potential risk of ART to pre- and perinatal development.

Terminology of developmental abnormalities in common laboratory mammals (version 2)

This update (Version 2) of the Terminology of Developmental Abnormalities in Common Laboratory Mammals (Version 1) incorporates improvements and enhancements to both content and organization of the terminology to enable greater flexibility in its application, while maintaining a consistent approach to the description of findings. The revisions are the result of an international collaboration among interested organizations, advised by individual experts and the outcomes of several workshops. The terminology remains organized into tables under the broad categories of external, visceral, and skeletal observations, following the manner in which data are typically collected and recorded in developmental toxicity studies. This arrangement of the tables, as well as other information provided in appendices, is intended to facilitate the process of specimen evaluation at the laboratory bench level. Only the commonly used laboratory mammals (i.e. rats, mice, rabbits) are addressed in the current terminology tables. The inclusion of other species that are used in developmental toxicity testing, such as primates, is considered outside the scope of the present update. Similarly, categorization of findings as, for example, 'malformation' or 'variation' remains unaddressed, in accordance with the overall principle that the focus of this document is descriptive terminology and not diagnosis or interpretation. The skeletal terms have been augmented to accommodate cartilage findings.

Isolated levocardia: prenatal diagnosis and management

Isolated levocardia (IL) is a rare condition of situs anomaly in which there is a normal left-sided heart (levocardia) with dextro position of the abdominal viscera. IL has been reported in children and adults with complex cardiac defects, whereas there are only few published reports regarding the prenatal diagnosis of IL. We report two prenatal cases of IL diagnosed by ultrasonography and magnetic resonance imaging (MRI). In both cases, fetal cardiac function remained within the normal range throughout pregnancy, and no treatment for the heart was required after birth. For the dextro position of abdominal viscera, one case was followed without any surgical procedure, but the other case required prophylactic operation due to malrotation of the small intestine. Although the prognosis of IL largely depends on the severity of associated cardiac anomaly, future bowel obstruction caused by intestinal malrotation may also be life-threatening. In this respect, prenatal diagnosis of IL is important, even when there is no associated cardiac structural anomaly. If IL is suspected in routine fetal ultrasonography, MRI may be recommended to obtain more detailed information on the anatomy of abdominal viscerae, and careful observation for bowel problems is required, especially after oral nutrition is started.

Hedgehog signaling is involved in development of the neocortex

Sonic hedgehog (Shh) function is essential for patterning and cell fate specification, particularly in ventral regions of the central nervous system. It is also a crucial mitogen for cerebellar granule neuron precursors and is important in maintenance of the stem cell niche in the postnatal telencephalon. Although it has been reported that Shh is expressed in the developing dorsal telencephalon, functions of Shh in this region are unclear, and detailed characterization of Shh mRNA transcripts in situ has not been demonstrated. To clarify the roles of Shh signaling in dorsal pallium (neocortex primordium) development, we have knocked out the Shh and Smo genes specifically in the early developing dorsal telencephalon by using Emx1cre mice. The mutants showed a smaller dorsal telencephalon at E18.5, which was caused by cell cycle kinetics defects of the neural progenitor/stem cells. The cell cycle length of the progenitor/stem cells was prolonged, and the number of cycle-exiting cells and neurogenesis were decreased. Birth-date analysis revealed abnormal positioning of neurons in the mutants. The characteristics of the subventricular zone, ventricular zone and subplate cells were also affected. Weak immunoreactivity of Shh was detected in the dorsal telencephalon of wild types. Reduced Shh immunoreactivity in mutant dorsal telencephalons supports the above phenotypes. Our data indicate that Shh signaling plays an important role in development of the neocortex.

Fetal ethanol exposure activates protein kinase A and impairs Shh expression in prechordal mesendoderm cells in the pathogenesis of holoprosencephaly

BACKGROUND

In humans, fetal ethanol exposure can cause holoprosencephaly (HPE), one of the most common birth defects that is characterized by brain, facial, and oral abnormalities. However, the pathogenesis of HPE is not clear. In the present study, we investigated the teratogenic mechanism of ethanol-induced brain and facial malformations in mice.

METHODS

Pregnant C57BL/6J mice were administered ethanol on E7 and facial and brain malformations were characterized on E10.5. We examined the effect of fetal ethanol exposure on Shh expression and activation of protein kinase A (PKA) because mutations in the human Shh gene are the most frequent cause of autosomal-dominant inherited HPE and PKA is a potent endogenous antagonist of Shh signaling.

RESULTS

Fetal ethanol exposure on E7 induced severe midline defects characteristic of HPE. Ethanol exposure impaired Shh expression and induced excessive apoptosis only along the anterior edge of the prechordal mesendoderm (PME). In addition, ethanol activated PKA in anterior PME cells. Pretreatment of embryos with antioxidants, such as vitamins C or E, prevented the development of ethanol-induced HPE.

CONCLUSIONS

Shh expression in PME cells is involved in the pathogenesis of ethanol-induced HPE. Ethanol may impair Shh expression indirectly by activating PKA. The inhibition of excessive apoptosis in PME cells by antioxidants implies that oxidative stress may underlie the teratogenic actions of ethanol. Thus, antioxidant treatment may be a simple preventative measure that could reduce the incidence of HPE following fetal ethanol exposure.

Expression dynamics of the LIM-homeobox genes, Lhx1 and Lhx9, in the diencephalon during chick development

The diencephalon is the caudal part of the developing forebrain, which corresponds to prosomeres 1 to 3. The mature diencephalon is functionally and anatomically divided into well-defined nuclei. Previous researches have shown that LIM-homeobox genes are important transcription factors during diencephalon regionalization in mice. Here we examined expression patterns of several chick orthologs of LIM-homeobox genes. Lhx1 and Lhx9 were expressed in the diencephalon from early stages and their expression in the diencephalon became restricted to prosomeres 1 and 2 in distinct fashions. Then we also studied the regulatory effects of possible upstream signals by in ovo electroporation. Lhx1 was found to be up-regulated by Shh signaling. Whereas Lhx9 was up-regulated by Wnt3a and Fgf15, it was down-regulated by Shh. Our data suggest that the LIM-homeobox genes, Lhx1 and Lhx9, regulated by ventral and/or dorsal signals, may play important roles in controlling regionalization of the diencephalon during chick development.

Involvement of the axially condensed tail bud mesenchyme in normal and abnormal human posterior neural tube development

Development of the posterior neural tube (PNT) in human embryos is a complicated process which involves both primary and secondary neurulation. Normal development of the human PNT should be understood to elucidate the pathogenesis of spinal neural tube defects, but there have been some discrepancies among previous reports. We examined histologically 20 human embryos around the stage of the posterior neuropore closure and found that the developing PNT can be divided into three parts: (1) the most rostral region which corresponds to the posterior part of the primary neural tube; (2) the junctional region of the primary and secondary neural tubes; and (3) the caudal region which emerges from the neural cord. In the junctional region, the axially condensed mesenchyme (AM) intervened between the neural plate/tube and the notochord. The AM appeared to be incorporated into the most ventral part of the primary neural tube, and no cavity was observed in the AM. Interestingly, we found three cases of human embryos with lumbosacral myeloschisis in which the open primary neural tube and the closed secondary neural tube overlapped dorso-ventrally. The open and closed neural tubes appeared to be part of the primary and the AM-derived secondary neural tubes, respectively. Thus, these findings suggest that in embryos with lumbosacral myeloschisis, the AM may not be incorporated into the ventral part of the primary neural tube but aberrantly differentiate into the secondary neural tube containing cavities, leading to dorso-ventral overlapping of the primary and secondary neural tubes. These findings suggest that the AM in human embryos plays some role in normal and abnormal development of the human posterior neural tube.

Expression of Fgf15 is regulated by both activator and repressor forms of Gli2 in vitro

Fibroblast growth factor 15 (Fgf15) is expressed in the medial region of diencephalon and midbrain by the seven-somite stage. In the previous studies, we showed that Sonic hedgehog signaling through Gli protein is required for Fgf15 expression in this region. The Fgf15 expression domain overlapped with that of Gli2 and the Gli-binding site (GliBs) is located in the 3.6-kb 5'-flanking enhancer/promoter region of the Fgf15 gene. In this study, we identified the two additional Gli-binding sites in row, called Gli-responsive elements (GliREs). Chromatin immunoprecipitation assay indicated that Gli2 directly binds to GliREs. The results from luciferase assays indicated that the Gli2 activator form binds to the GliBS and that the Gli2 repressor form binds to the GliREs. These findings suggest that the repressor form of Gli2 preferentially binds to the GliREs to control Fgf15 expression.

Visualization of human prenatal development by magnetic resonance imaging (MRI)

It is essential to visualize the structures of embryos and their internal organs three-dimensionally to analyze morphogenesis; this used to rely solely on serial histological sectioning and solid reconstruction, which were tedious and time-consuming. We have applied imaging with a magnetic resonance (MR) microscope equipped with a 2.35 T superconducting magnet to visualize human embryos; we were successful in acquiring high-resolution sectional images and in identifying the detailed structures of major organs. The imaging process was facilitated by using a super-parallel MR microscope. A dataset of MR images of more than 1,000 human embryos, now collected, will be important for future biomedical research and for education.

Epigenetics: the DNA methylation profile of tissue-dependent and differentially methylated regions in cells

Methylation of DNA, which occurs at cytosines of CpG sequences, is a unique chemical modification of the vertebrate genome. Methylation patterns can be copied to daughter DNA after mitosis; thus DNA methylation has been suggested to act as a "cellular memory of the genome function". Genome-wide analysis of DNA methylation revealed that there are numerous tissue-dependent differentially methylated regions (T-DMRs) in unique sequences of the mammalian genome. There are T-DMRs in both CpG-rich and -poor sequences. Methylation of T-DMRs is responsible for gene-silencing and chromatin structure change. Each tissue/cell type has a unique DNA methylation profile that consists of methylation patterns of numerous loci in the genome. DNA methylation profiles are not associated with bulk DNA, which is mainly comprised of repetitive sequences. Disruption of DNA methylation profiles putatively produce abnormal cells and tissues. Cloned mice produced by somatic nuclear transfer are associated with aberrant DNA methylation profiles. Tissue/cell type-specific DNA methylation profiles can provide a novel viewpoint for understanding normal and aberrant development, in terms of both differentiation and reproduction.