Human Primordial Germ Cell-Like Cell Induction from Pluripotent Stem Cells by SOX17 and PRDM1 Expression

Human primordial germ cell (PGC) development initiates about 2 weeks after fertilization during embryogenesis. Unique molecular events follow, including epigenetic resetting, to establish functional gametes (egg and sperm). Due to the inaccessibility of human embryos, it is essential to have an amenable experimental platform to investigate the mechanisms and potential dysfunctions of the events. We previously established a PGC-like cell (PGCLC) differentiation method using human pluripotent stem cells (PSCs) via induction of precursor cells followed by stimulation with a cytokine cocktail including BMP. We also revealed that the expression of PGC specifiers, SOX17 and PRDM1, can robustly induce PGCLCs from PSCs without the cytokines. The balance of SOX17 and PRDM1 is critical for germ cell fate since the two factors also regulate endoderm differentiation. Here we describe a detailed procedure for PGCLC differentiation with the balanced induction of SOX17 and PRDM1. The protocol can be used for PGC induction in other mammalian species exhibiting PGCs with SOX17 expression. Together, these studies will advance the understanding of germ cell biology and its applications in reproductive technology and medicine.

DMRT1 regulates human germline commitment

Germline commitment following primordial germ cell (PGC) specification during early human development establishes an epigenetic programme and competence for gametogenesis. Here we follow the progression of nascent PGC-like cells derived from human embryonic stem cells in vitro. We show that switching from BMP signalling for PGC specification to Activin A and retinoic acid resulted in DMRT1 and CDH5 expression, the indicators of migratory PGCs in vivo. Moreover, the induction of DMRT1 and SOX17 in PGC-like cells promoted epigenetic resetting with striking global enrichment of 5-hydroxymethylcytosine and locus-specific loss of 5-methylcytosine at DMRT1 binding sites and the expression of DAZL representing DNA methylation-sensitive genes, a hallmark of the germline commitment programme. We provide insight into the unique role of DMRT1 in germline development for advances in human germ cell biology and in vitro gametogenesis.

An incidentally discovered paraganglioma that caused sinus arrest after resection

Paragangliomas are neural-crest-derived nonepithelial neuroendocrine tumors distributed along the parasympathetic and sympathetic nerves. To our knowledge, no studies were reported regarding sinus arrest on day 4 after paraganglioma resection. A 66-year-old female patient with a history of pulmonary vein isolation visited our department for sigmoid colon cancer treatment. Enhanced computed tomography revealed an enhanced small nodule-like lymph node near the root of the inferior mesenteric artery. The patient underwent laparoscopic colectomy with regional lymph node dissection. Postoperatively, paroxysmal atrial fibrillation attacks developed, and the patient resumed oral medication. Additionally, sinus arrest after tachycardia developed. Changing the oral medication could maintain her circulatory dynamics. Pathological examination revealed that differentiated tubular adenocarcinoma infiltrated the submucosa. Immunohistochemically, the excised nodule as a lymph node was considered a functional paraganglioma. Our case indicates that paraganglioma resection and oral medication resumption may contribute to sinus arrest. When arrhythmias affecting the circulation occur perioperatively, the presence of a catecholamine-producing tumor should be considered in addition to cardiac disease. J. Med. Invest. 70 : 503-507, August, 2023.

Falciform ligament abscess with disseminated intrahepatic foci: a case report

Background

Falciform ligament abscess (FLA) is a rare disease, and its diagnosis can be challenging without typical image findings of an abscess. We report a patient with FLA that presented as a mass, with an indistinct border between it and the liver, in addition to disseminated foci within the liver. This made it difficult to determine whether it was FLA or a malignancy.

Case presentation

A 69-year-old man presented with epigastric pain. Contrast-enhanced computed tomography revealed a 25-mm mass below the middle of the diaphragm. Based on an initial diagnosis of infection of the falciform ligament, we administered conservative antibiotic treatment and there was initial improvement in the patient’s clinical condition and laboratory data. However, he continued to experience mild epigastric pain. A month later, imaging studies revealed enlargement of the falciform ligament mass and the emergence of a new nodule in the liver, whereas laboratory findings showed re-elevated C-reactive protein levels. Since conservative treatment had failed, we decided to perform surgery. Considering the imaging study findings, malignant disease could not be ruled out. Based on the operative findings, we performed combined resection of the falciform ligament, left liver, and gallbladder. Histopathological examination of the resected specimens revealed extensive neutrophil infiltration and the presence of giant cells and foam cells within the lesions. These findings were indicative of abscess. Pseudomonas aeruginosa was cultured from the pus in the falciform ligament mass and bile in the gallbladder. Although multiple abscesses postoperatively developed in the residual portion of the liver, they could be treated through antibiotic therapy.

Conclusions

FLA can spread to both adjacent and distant organs via its rich vascular and lymphatic networks. When FLA displays atypical image findings and/or an atypical clinical course, it can be difficult to distinguish it from malignant disease. In such cases, surgical treatment, with intraoperative pathological diagnosis, should be attempted.

[A Case Report of Perianal Paget's Disease Treated with Robot-Assisted Surgery for Positive Margins after Local Excision]

The patient is a 73-year-old man who was diagnosed with perianal Paget's disease by skin biopsy. Biopsy from the dentate line did not show any tumor cells. The patient was considered to undergo sphincter-preserving local resection and subsequently underwent the procedure. Histopathological examination of the resected specimen revealed perianal Paget's disease with a positive anorectal margin. The patient was referred to our department due to postoperative anal stenosis. On the 32nd postoperative day, a double barreled sigmoid colostomy was performed. However, considering the inability to adequately check for detect due to anorectal stenosis and the expected unfavorable anorectal function caused by sphincter- preserving re-operation, a robot-assisted abdominoperineal resection(D1)was performed 7 months after the initial surgery. Histopathological examination of the resected specimen revealed no residual tumor cells in the resected specimen. After local excision for perianal Paget's disease, the skin of the buttock becomes scarred due to skin valve formation and skin grafting, making closure of the perineal wound difficult when performing abdominoperineal resection. In robot-assisted surgery, it is relatively easy to remove the anorectal muscles from the abdominal cavity and reach the sciatico-rectal fossa, thus reducing the size of the perineal wound.

[A Case of Advanced Gastric Cancer with Para-Aortic Lymph Node Metastasis with Long-Term Survival by Chemotherapy and Surgery]

Chemotherapy is the standard treatment for unresectable gastric cancer, but there is no clear evidence of therapeutic lymphadenectomy in conversion surgery after the tumor shrinks or the combined effect of perioperative chemotherapy. A 63-year-old man was diagnosed with advanced gastric cancer by upper gastrointestinal endoscopy; computed tomography (CT)showed swelling of the gastric regional lymph nodes, abdominal para-aortic lymph nodes, and left supraclavicular lymph node. After 4 courses of combination therapy with S-1 and cisplatin(SP therapy), CT showed that the left supraclavicular lymph node disappeared and the para-aortic lymph node was reduced. Distal gastrectomy and D2 plus para-aortic lymph node dissection were performed as conversion surgery. Two courses of postoperative SP therapy were administered, and S-1 monotherapy was continued for 2 years and 6 months. After 5 years and 1 month since the operation, the patient is alive without recurrence. This case shows that SP therapy can be effective as chemotherapy for unresectable gastric cancer. In addition, that conversion surgery after chemotherapy may contribute to recurrence-free survival.

Tumors Widely Express Hundreds of Embryonic Germline Genes

We have recently described a class of 756 genes that are widely expressed in cancers, but are normally restricted to adult germ cells, referred to as germ cell cancer genes (GC genes). We hypothesized that carcinogenesis involves the reactivation of biomolecular processes and regulatory mechanisms that, under normal circumstances, are restricted to germline development. This would imply that cancer cells share gene expression profiles with primordial germ cells (PGCs). We therefore compared the transcriptomes of human PGCs (hPGCs) and PGC-like cells (PGCLCs) with 17,382 samples from 54 healthy somatic tissues (GTEx) and 11,003 samples from 33 tumor types (TCGA), and identified 672 GC genes, expanding the known GC gene pool by 387 genes (51%). We found that GC genes are expressed in clusters that are often expressed in multiple tumor types. Moreover, the amount of GC gene expression correlates with poor survival in patients with lung adenocarcinoma. As GC genes specific to the embryonic germline are not expressed in any adult tissue, targeting these in cancer treatment may result in fewer side effects than targeting conventional cancer/testis (CT) or GC genes and may preserve fertility. We anticipate that our extended GC dataset enables improved understanding of tumor development and may provide multiple novel targets for cancer treatment development.

Combined resection of the hepatic artery without reconstruction in pancreaticoduodenectomy: a case report of pancreatic cancer with an aberrant hepatic artery

Background

Pancreaticoduodenectomy (PD) is rarely performed for pancreatic cancer with hepatic arterial invasion owing to its poor prognosis and high surgical risks. Although there has been a recent increase in the reports of PD combined with hepatic arterial resection due to improvements in disease prognosis and operative safety, PD with major arterial resection and reconstruction is still considered a challenging treatment.

Case presentation

A 61-year-old man with back pain was diagnosed with pancreatic head and body cancer. Although distant metastasis was not confirmed, the tumor had extensively invaded the hepatic artery; therefore, we diagnosed the patient with locally advanced unresectable pancreatic cancer. After gemcitabine plus nab-paclitaxel (GnP) therapy, the tumor considerably decreased in size from 35 to 20 mm. Magnetic resonance imaging revealed a gap between the tumor and the hepatic artery. Tumor marker levels returned to their normal range, and we decided to perform conversion surgery. In this case, an artery of liver segment 2 (A2) had branched from the left gastric artery; therefore, we decided to preserve A2 and perform PD combined with hepatic arterial resection without reconstruction. After four cycles of GnP therapy, we performed hepatic arterial embolization to prevent postoperative ischemic complications prior to surgery. Immediately after embolization, collateral arterial blood flow to the liver was observed. Operation was performed 19 days after embolization. Although there was a temporary increase in liver enzyme levels and an ischemic region was found near the surface of segment 8 of the liver after surgery, no liver abscess developed. The postoperative course was uneventful, and S-1 was administered for a year as adjuvant chemotherapy. The patient is currently alive without any ischemic liver events and cholangitis and has not experienced recurrence in the past 4 years since the surgery.

Conclusions

In PD for pancreatic cancer with hepatic arterial invasion, if a part of the hepatic artery is aberrant and can be preserved, combined resection of the common and proper hepatic artery without reconstruction might be feasible for both curability and safety.

Correction to: Unique numerical competence of Asian elephants on the relative numerosity judgment task

The article Unique numerical competence of Asian elephants on the relative numerosity judgment task, written by Naoko Irie, Mariko Hiraiwa‑Hasegawa and Nobuyuki Kutsukake, was originally published Online First without Open Access.

Author Correction: Segregation of mitochondrial DNA heteroplasmy through a developmental genetic bottleneck in human embryos

In the version of this Letter originally published, an author error led to the affiliations for Brendan Payne, Jonathan Coxhead and Gavin Hudson being incorrect. The correct affiliations are: Brendan Payne: 3Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK. 6Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK; this is a new affiliation 6 and subsequent existing affiliations have been renumbered. Jonathan Coxhead: 11Genomic Core Facility, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK; this is a new affiliation 11 and subsequent existing affiliations have been renumbered. Gavin Hudson: 3Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK. In addition, in Fig. 2d, the numbers on the x-axis of the left plot were incorrectly labelled as negative; they should have been positive. These errors have now been corrected in all online versions of the Letter.

A PAX5-OCT4-PRDM1 developmental switch specifies human primordial germ cells

Dysregulation of genetic pathways during human germ cell development leads to infertility. Here, we analysed bona fide human primordial germ cells (hPGCs) to probe the developmental genetics of human germ cell specification and differentiation. We examined the distribution of OCT4 occupancy in hPGCs relative to human embryonic stem cells (hESCs). We demonstrated that development, from pluripotent stem cells to germ cells, is driven by switching partners with OCT4 from SOX2 to PAX5 and PRDM1. Gain- and loss-of-function studies revealed that PAX5 encodes a critical regulator of hPGC development. Moreover, an epistasis analysis indicated that PAX5 acts upstream of OCT4 and PRDM1. The PAX5-OCT4-PRDM1 proteins form a core transcriptional network that activates germline and represses somatic programmes during human germ cell differentiation. These findings illustrate the power of combined genome editing, cell differentiation and engraftment for probing human developmental genetics that have historically been difficult to study.

Segregation of mitochondrial DNA heteroplasmy through a developmental genetic bottleneck in human embryos

Mitochondrial DNA (mtDNA) mutations cause inherited diseases and are implicated in the pathogenesis of common late-onset disorders, but how they arise is not clear1,2. Here we show that mtDNA mutations are present in primordial germ cells (PGCs) within healthy female human embryos. Isolated PGCs have a profound reduction in mtDNA content, with discrete mitochondria containing ~5 mtDNA molecules. Single-cell deep mtDNA sequencing of in vivo human female PGCs showed rare variants reaching higher heteroplasmy levels in late PGCs, consistent with the observed genetic bottleneck. We also saw the signature of selection against non-synonymous protein-coding, tRNA gene and D-loop variants, concomitant with a progressive upregulation of genes involving mtDNA replication and transcription, and linked to a transition from glycolytic to oxidative metabolism. The associated metabolic shift would expose deleterious mutations to selection during early germ cell development, preventing the relentless accumulation of mtDNA mutations in the human population predicted by Muller's ratchet. Mutations escaping this mechanism will show shifts in heteroplasmy levels within one human generation, explaining the extreme phenotypic variation seen in human pedigrees with inherited mtDNA disorders.

What Can Stem Cell Models Tell Us About Human Germ Cell Biology?

Fusion of sperm and egg generates a totipotent zygote that develops into a whole organism. Accordingly, the "immortal" germline transmits genetic and epigenetic information to subsequent generations with consequences for human health and disease. In mammals, primordial germ cells (PGCs) originate from peri-gastrulation embryos. While early human embryos are inaccessible for research, in vitro model systems using pluripotent stem cells have provided critical insights into human PGC specification, which differs from that in mice. This might stem from significant differences in early embryogenesis at the morphological and molecular levels, including pluripotency networks. Here, we discuss recent advances and experimental systems used to study mammalian germ cell development. We also highlight key aspects of germ cell disorders, as well as mitochondrial and potentially epigenetic inheritance in humans.

Principles of early human development and germ cell program from conserved model systems

Human primordial germ cells (hPGCs), the precursors of sperm and eggs, originate during weeks 2-3 of early post-implantation development. Using in vitro models of hPGC induction, recent studies have suggested that there are marked mechanistic differences in the specification of human and mouse PGCs. This may be due in part to the divergence in their pluripotency networks and early post-implantation development. As early human embryos are not accessible for direct study, we considered alternatives including porcine embryos that, as in humans, develop as bilaminar embryonic discs. Here we show that porcine PGCs originate from the posterior pre-primitive-streak competent epiblast by sequential upregulation of SOX17 and BLIMP1 in response to WNT and BMP signalling. We use this model together with human and monkey in vitro models simulating peri-gastrulation development to show the conserved principles of epiblast development for competency for primordial germ cell fate. This process is followed by initiation of the epigenetic program and regulated by a balanced SOX17-BLIMP1 gene dosage. Our combinatorial approach using human, porcine and monkey in vivo and in vitro models provides synthetic insights into early human development.

Efficient Induction and Isolation of Human Primordial Germ Cell-Like Cells from Competent Human Pluripotent Stem Cells

We recently reported a robust and defined culture system for the specification of human primordial germ cell-like cells (hPGCLCs) from human pluripotent stem cells (hPSCs), both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) in vitro (Irie et al. Cell 160: 253-268, 2015). Similar attempts previously produced hPGCLCs from hPSCs at a very low efficiency, and the resulting cells were not fully characterized. A key step, which facilitated efficient hPGCLC specification from hPSCs, was the induction of a "competent" state for PGC fate via the medium containing a cocktail of four inhibitors. The competency of hPSCs can be maintained indefinitely and interchangeably with the conventional/low-competent hPSCs. Specification of hPGCLC occurs following sequential expression of key germ cell fate regulators, notably SOX17 and BLIMP1, as well as initiation of epigenetic resetting over 5 days. The hPGCLCs can be isolated using specific cell surface markers without the need for generating germ cell-specific reporter hPSC lines. This powerful method for the induction and isolation of hPGCLCs can be applied to both hESCs and iPSCs, which can be used for advances in human germ line biology.

Germline competency of human embryonic stem cells depends on eomesodermin

In humans, germline competency and the specification of primordial germ cells (PGCs) are thought to occur in a restricted developmental window during early embryogenesis. Despite the importance of specifying the appropriate number of PGCs for human reproduction, the molecular mechanisms governing PGC formation remain largely unexplored. Here, we compared PGC-like cell (PGCLC) differentiation from 18 independently derived human embryonic stem cell (hESC) lines, and discovered that the expression of primitive streak genes were positively associated with hESC germline competency. Furthermore, we show that chemical inhibition of TGFβ and WNT signaling, which are required for primitive streak formation and CRISPR/Cas9 deletion of Eomesodermin (EOMES), significantly impacts PGCLC differentiation from hESCs. Taken together, our results suggest that human PGC formation involves signaling and transcriptional programs associated with somatic germ layer induction and expression of EOMES.

Changes in the Small Intestine of a Cat Associated with Barium Sulphate Following Contrast Radiography

A 7-year-old neutered male domestic short-haired cat that had undergone contrast radiography of the bowel with barium sulphate after acute episodes of vomiting 2 months previously, was presented with chronic vomiting, anorexia and weight loss. Abdominal radiography and ultrasonography revealed residual contrast enhancement and an obstruction of the small intestine. A contracted and stenosed ileum and distal jejunum were identified by exploratory laparotomy and surgically resected; subsequently, the clinical signs resolved. Histopathological examination of the ileum revealed mucosal ulceration with severe submucosal granulation tissue formation associated with scattered foreign crystalline material. Energy-dispersive X-ray spectroscopy revealed that the crystals contained barium sulphate. This is the first report in animals of the rare complication of barium sulphate incorporation into the gastrointestinal mucosa after contrast radiography.

Asian elephants acquire inaccessible food by blowing

Many animals acquire otherwise inaccessible food with the aid of sticks and occasionally water. As an exception, some reports suggest that elephants manipulate breathing through their trunks to acquire inaccessible food. Here, we report on two female Asian elephants (Elephas maximus) in Kamine Zoo, Japan, who regularly blew to drive food within their reach. We experimentally investigated this behaviour by placing foods in inaccessible places. The elephants blew the food until it came within accessible range. Once the food was within range, the elephants were increasingly less likely to blow as the distance to the food became shorter. One subject manipulated her blowing duration based on food distance: longer when the food was distant. These results suggest that the elephants used their breath to achieve goals: that is, they used it not only to retrieve the food but also to fine-tune the food position for easy grasping. We also observed individual differences in the elephants' aptitude for this technique, which altered the efficiency of food acquisition. Thus, we added a new example of spontaneous behaviour for achieving a goal in animals. The use of breath to drive food is probably unique to elephants, with their dexterous trunks and familiarity with manipulating the act of blowing, which is commonly employed for self-comfort and acoustic communication.

A Unique Gene Regulatory Network Resets the Human Germline Epigenome for Development

Resetting of the epigenome in human primordial germ cells (hPGCs) is critical for development. We show that the transcriptional program of hPGCs is distinct from that in mice, with co-expression of somatic specifiers and naive pluripotency genes TFCP2L1 and KLF4. This unique gene regulatory network, established by SOX17 and BLIMP1, drives comprehensive germline DNA demethylation by repressing DNA methylation pathways and activating TET-mediated hydroxymethylation. Base-resolution methylome analysis reveals progressive DNA demethylation to basal levels in week 5-7 in vivo hPGCs. Concurrently, hPGCs undergo chromatin reorganization, X reactivation, and imprint erasure. Despite global hypomethylation, evolutionarily young and potentially hazardous retroelements, like SVA, remain methylated. Remarkably, some loci associated with metabolic and neurological disorders are also resistant to DNA demethylation, revealing potential for transgenerational epigenetic inheritance that may have phenotypic consequences. We provide comprehensive insight on early human germline transcriptional network and epigenetic reprogramming that subsequently impacts human development and disease.

SOX17 is a critical specifier of human primordial germ cell fate

Specification of primordial germ cells (PGCs) marks the beginning of the totipotent state. However, without a tractable experimental model, the mechanism of human PGC (hPGC) specification remains unclear. Here, we demonstrate specification of hPGC-like cells (hPGCLCs) from germline competent pluripotent stem cells. The characteristics of hPGCLCs are consistent with the embryonic hPGCs and a germline seminoma that share a CD38 cell-surface marker, which collectively defines likely progression of the early human germline. Remarkably, SOX17 is the key regulator of hPGC-like fate, whereas BLIMP1 represses endodermal and other somatic genes during specification of hPGCLCs. Notable mechanistic differences between mouse and human PGC specification could be attributed to their divergent embryonic development and pluripotent states, which might affect other early cell-fate decisions. We have established a foundation for future studies on resetting of the epigenome in hPGCLCs and hPGCs for totipotency and the transmission of genetic and epigenetic information.

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A defined model for hPGCLC specification from germline-competent hESCs

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Expression profiles of hPGCLCs match with authentic hPGCs

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SOX17 is the key regulator of hPGCLC

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CD38 glycoprotein is a cell-surface marker of the human germline

Germ cell specification and pluripotency in mammals: a perspective from early embryogenesis

Germ cells are unique cell types that generate a totipotent zygote upon fertilization, giving rise to the next generation in mammals and many other multicellular organisms. How germ cells acquire this ability has been of considerable interest. In mammals, primordial germ cells (PGCs), the precursors of sperm and oocytes, are specified around the time of gastrulation. PGCs are induced by signals from the surrounding extra-embryonic tissues to the equipotent epiblast cells that give rise to all cell types. Currently, the mechanism of PGC specification in mammals is best understood from studies in mice. Following implantation, the epiblast cells develop as an egg cylinder while the extra-embryonic ectoderm cells which are the source of important signals for PGC specification are located over the egg cylinder. However, in most cases, including humans, the epiblast cells develop as a planar disc, which alters the organization and the source of the signaling for cell fates. This, in turn, might have an effect on the precise mechanism of PGC specification in vivo as well as in vitro using pluripotent embryonic stem cells. Here, we discuss how the key early embryonic differences between rodents and other mammals may affect the establishment of the pluripotency network in vivo and in vitro, and consequently the basis for PGC specification, particularly from pluripotent embryonic stem cells in vitro.

Effective expansion of engrafted human hematopoietic stem cells in bone marrow of mice expressing human Jagged1

The human immune system can be reconstituted in experimental animals by transplanting human hematopoietic stem cells (hHSCs) into immunodeficient mice. To generate such humanized mice, further improvements are required, particularly to ensure that transplanted hHSCs are maintained in mice and proliferate long enough to follow prolonged immune responses to chronic diseases or monitor therapeutic effects. To prepare the relatively human bone marrow environment in mice, we generated nonobese diabetic/severe combined immunodeficiency/interleukin-2 receptor gamma chain null (NOG) mice expressing human Jagged1 (hJ1) in an osteoblast-specific manner (hJ1-NOG mice) to examine whether Notch signaling induced by hJ1 mediates hHSC proliferation and/or maintenance in mice. The established hJ1-NOG mice possess relatively larger bone marrow space and thinner cortical bone compared with nontransgenic littermates, but the number of c-kit(+) Sca-1(+) lineage(-) cells was not significantly different between hJ1-NOG and nontransgenic littermates. In the transplantation experiments of CD34(+) cells obtained from human cord blood, CD34(+)CD38(-) cells (hHSCs) were more increased in hJ1-NOG recipient mice than in nontransgenic littermates in mouse bone marrow environment. In contrast, the transplanted mouse c-kit(+) Sca-1(+) lineage(-) cells did not show significant increase in the same hJ1-NOG mice. These results suggest that hJ1-NOG mice could contribute to the growth of transplanted human CD34(+) cells in a human-specific manner and be useful to study the in vivo behavior and/or development of human stem cells, including cancer stem cells and immune cells.

Bidirectional signaling through ephrinA2-EphA2 enhances osteoclastogenesis and suppresses osteoblastogenesis

Bone is remodeled constantly throughout life by bone-resorbing osteoclasts and bone-forming osteoblasts. To maintain bone volume and quality, differentiation of osteoclasts and osteoblasts is tightly regulated through communication between and within these two cell lineages. Previously we reported that cell-cell interaction mediated by ephrinB2 ligand on osteoclasts and EphB4 receptor on osteoblasts generates bidirectional anti-osteoclastogenic and pro-osteoblastogenic signals into respective cells and presumably facilitates transition from bone resorption to bone formation. Here we show that bidirectional ephrinA2-EphA2 signaling regulates bone remodeling at the initiation phase. EphrinA2 expression was rapidly induced by receptor activator of NF-kappaB ligand in osteoclast precursors; this was dependent on the transcription factor c-Fos but independent of the c-Fos target gene product NFATc1. Receptor EphA2 was expressed in osteoclast precursors and osteoblasts. Overexpression experiments revealed that both ephrinA2 and EphA2 in osteoclast precursors enhanced differentiation of multinucleated osteoclasts and that phospholipase Cgamma2 may mediate ephrinA2 reverse signaling. Moreover, ephrinA2 on osteoclasts was cleaved by metalloproteinases, and ephrinA2 released in the culture medium enhanced osteoclastogenesis. Interestingly, differentiation of osteoblasts lacking EphA2 was enhanced along with alkaline phosphatase, Runx2, and Osterix expression, indicating that EphA2 on osteoblasts generates anti-osteoblastogenic signals presumably by up-regulating RhoA activity. Therefore, ephrinA2-EphA2 interaction facilitates the initiation phase of bone remodeling by enhancing osteoclast differentiation and suppressing osteoblast differentiation.

Bidirectional ephrinB2-EphB4 signaling controls bone homeostasis

Bone homeostasis requires a delicate balance between the activities of bone-resorbing osteoclasts and bone-forming osteoblasts. Various molecules coordinate osteoclast function with that of osteoblasts; however, molecules that mediate osteoclast-osteoblast interactions by simultaneous signal transduction in both cell types have not yet been identified. Here we show that osteoclasts express the NFATc1 target gene Efnb2 (encoding ephrinB2), while osteoblasts express the receptor EphB4, along with other ephrin-Eph family members. Using gain- and loss-of-function experiments, we demonstrate that reverse signaling through ephrinB2 into osteoclast precursors suppresses osteoclast differentiation by inhibiting the osteoclastogenic c-Fos-NFATc1 cascade. In addition, forward signaling through EphB4 into osteoblasts enhances osteogenic differentiation, and overexpression of EphB4 in osteoblasts increases bone mass in transgenic mice. These data demonstrate that ephrin-Eph bidirectional signaling links two major molecular mechanisms for cell differentiation--one in osteoclasts and the other in osteoblasts--thereby maintaining bone homeostasis.

[Transcription factors in osteoclast differentiation]

Osteoclasts are specialized, multinucleated macrophages that resorb bone. Genetic experiments in mice revealed that the three families of transcription factors, nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1), and nuclear factor of activated T-cells (NFAT) are each essential for osteoclast differentiation. Macrophage colony stimulating factor (M-CSF), receptor activator of NF-kappaB ligand(RANKL), and other osteoclastogenic ligands activate the NF-kappaB components p50 or p52, the AP-1 component c-Fos, and NFATc1 in osteoclast precursors. Consequently, diverse groups of genes are transcribed, including those encoding tartrate-resistant acid phosphatase (TRAP), calcitonin receptor, cathepsin K and interferon-beta. Surprisingly, recent studies have begun to uncover a linear relationship among these transcription factors, including the c-Fos-NFATc1 transcriptional activation cascade.

[Penetrating head injury caused by an icepick]

The patient was a 39-year-old man, with a three year history of schizophrenia, who attempted suicide by piercing his head with an icepick. Spinal cord injuries and shock caused by falling from the fifth floor of the building following this penetrating injury were also noted on admission. The CT scan revealed that the icepick had deeply penetrated the posterior fossa from the forehead. No new neurological deficits or cerebrospinal fluid leakage appeared after admission. The icepick was removed completely without difficulty. In penetrating head injuries, early assessment with cerebral angiography to determine the extent of vascular injury is useful for deciding if surgery should be performed.

Synergistic bactericidal effects of acrinol and tetracycline against Pseudomonas aeruginosa

Combined treatment of acrinol (Ac) and tetracycline hydrochloride (Tc) against Pseudomonas aeruginosa strains isolated from clinical specimens synergistically increased the bactericidal effect. The minimum bactericidal concentration (MBC) of Ac against P. aeruginosa strain no. 985 was 200 microg/ml, while the MBC of Ac against strains no. 47 and no. 783 was above 800 microg/ml for each. The MBC of Tc was above 400 microg/ml against each of the tested strains. However, simultaneous treatment with 25 microg/ml Ac and 200 microg/ml Tc against P. aeruginosa strain no. 985 decreased the viable cell number from 107 cfu/ml to <10 cfu/ml within 24 h, while a higher concentration of Tc (400 microg/ml) with Ac (25 microg/ml) reduced the viable cell number to <10 cfu/ml within 8 h. A similar synergistic bactericidal effect of Ac and Tc was observed in strains no. 47 and no. 783 by treatment with 200 microg/ml Ac and 200 microg/ml or 400 microg/ml Tc. The degree of bactericidal effect against P. aeruginosa was proportional to the concentration of Tc under the condition of a constant concentration of Ac. Furthermore, Ac-treated cells of strain no. 47 were killed by a following Tc treatment, but cells pretreated with Tc did not show such a sensitivity to Ac. To induce the synergistic effect of Ac and Tc, Ac must be applied to P. aeruginosa before or at the same time as Tc.

Randomized controlled trial of exercise training for older people (Sendai Silver Center Trial; SSCT): study design and primary outcome

Physical exercise is expected to improve and maintain physical function in older people, thus promoting health and preventing or postponing the onset of disability in later life. The Sendai Silver Center Trial (SSCT) was a randomized controlled trial designed to evaluate the efficacy of exercise training among healthy free-living older people. Sixty-five eligible participants, aged from 60 to 81 years, were randomly allocated to an exercise group or a control group. The subjects in the exercise group were asked to attend training classes at the Sendai Silver Center, a municipal health and welfare facility in the center of Sendai City, at least twice a week for 25 weeks. Each training class, lasting two hours, started with a warm-up session, followed by an endurance session with a bicycle ergometer, and a resistance exercise training session using rubber films, and ended with a cool-down session. The subjects in the control group were asked to attend recreational classes at the Center twice a month. There were no drop-outs or accidents during the intervention. Comparison of maximum oxygen consumption (VO2max) before and after the 25-week intervention revealed a significant increase in the exercise group (2.1 ml/kg/min) but no significant change in the control group. Our result is equivalent to the participants becoming younger in aerobic capacity by five years after six months of exercise training.

[A study on incidence of developmental disabilities in Higashi-Osaka City, Japan, 1988-1992]

A population based statistical analysis was performed of the incidence of developmental disabilities in Higashi-Osaka, a city in Osaka Prefecture with a population of about 500,000. The number of live births during 1988-1992 was 24,980, of whom those with cerebral palsy (CP), severe motor and intellectual disability syndrome (SMIDS), infantile autism, mental retardation (MR) and Down syndrome numbered 30, 21, 26, 268 and 25, respectively. And the respective incidence rates per 1,000 were 1.20, 0.84, 1.04, 10.7 and 1.0. For CP, the percentage of premature children was 63%, higher than in previous reports. Extremely low-birth-weight premature children (< 999 g birth weight) were especially notable at 20% of the CP total. For SMIDS, it is more important to understand the significance of medical care to support sufferers' social lives. High functional autistic children could not be evaluated at our center, though autism accounted for 8.6% of mental retardation. The medical functions of community institutions enable them to perform continuous, population based study of the incidence and situation of developmental disabilities.

Epileptic seizures in the 4p- syndrome: report of two cases

We report ictal phenomena in two patients with the 4p- syndrome captured on simultaneous video-EEG monitor. One patient, diagnosed as having partial epilepsy, had complex partial seizures and hemiconvulsive status epilepticus. This was associated with more severe mental retardation. The second patient was diagnosed as having the West syndrome and exhibited tonic spasms with a cluster formation. We conclude that various types of epileptic seizures may occur in patients with the 4p- syndrome, including grand mal and myoclonic seizures.

[A case of 18 q-syndrome associated with status epilepticus]

A 15-year-old boy with 18 q-syndrome manifesting a status epilepticus is reported. He has been already diagnosed as epilepsy because of grand mal seizures at six months earlier, and abnormal EEG findings. Unilateral status epilepticus developed at 15 years of age, which were characterized by alternative repetition of horizontal nystagmus to the right and clonic convulsion of the right (mainly upper) extremities every several minutes. Ictal EEG showed continuous 2 Hz high voltage slow waves superimposed by spikes and polyspikes which transformed to localized, irregular spike discharges in the left occipital region at the end of the status. The chromosomal study revealed a partial deletion of the long arm of No. 18. He had severe mental retardation, and a typical karyotype for 18 q-syndrome with reduced prominence of the midface region, short stature and whorls on all finger tips. The immaturity of the brain probably relates to this kind of unilateral status epilepticus.

Right hemisphere dominance in arousal induced by facilitating positions

To clarify whether there is left-right difference in arousal induced by position changes, vocal reaction times (RTs) were measured at three different positions of the arms for 10 normal subjects. RTs at the facilitating position of either arm were faster than RTs at the neutral position, and RTs at the facilitating position of the left arm were faster than those of the right. The results indicate that the left facilitating position is more effective for increasing arousal than the right one.

Motor reaction time as a measure of rapid force generation of a muscle

Motor reaction time (MT) of the vastus medialis, latency from the EMG onset to initiation of the actual movement of the lower leg, was examined for 19 normal subjects during rapid extension of the knee joint at various angles from 90 degrees to 0 degrees in the sitting posture. Muscular tension produced by maximal voluntary contraction (MVC) was measured at 80 degrees of the knee joint for 19 subjects. Also, EMG activities during period of MT were integrated at each angle of the knee for five subjects. MT correlated linearly with the integrated EMG, indicating that MT was a variable representing muscular force required for initiation of the movement. MT increased with extension of the knee and the increment was attributed to the increased effective load of the lower leg due to gravity in the range from 90 degrees to 30 degrees of knee flexion. Thus, MT could be defined solely by the external load against the movement in the mid-range of the joint angle. Moreover, at 80 degrees knee flexion MT did not relate to MVC. It is suggested that MT provides a useful means to evaluate a muscular function in rapid movement and is applicable to both normal and pathological situations.

Conversion of low density lipoprotein 1 (LDL1, 1.019 less than d less than 1.045) to low density lipoprotein 2 (LDL2, 1.045 less than d less than 1.063) by hepatic triglyceride lipase

The role of lipoprotein lipase and hepatic lipase in the conversion of LDL1 (1.019 less than d less than 1.045) to LDL2 (1.045 less than 1.063) were investigated on the basis of incubation of 125I-LDL1 with postheparin plasma (PHP) at NaCl concentrations of both 0.15 M and 1.0 M. Insignificant small increments of radioactivity and apoprotein B specific activity of LDL2 were observed even when 125I-LDL1 was incubated with preheparin plasma as the control. When 125I-LDL1 was incubated with PHP, the LDL1 radioactivity decreased and the LDL2 radioactivity increased significantly. the apoprotein B specific activity was also increased in the LDL2 fraction. One molar NaCl did not inhibit these changes. It is concluded that hepatic triglyceride lipase was the major mediator in the conversion of LDL1 to LDL2.