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Our hospital was introduced in the media as the hospital at which the first patient who died of COVID-19 infection in Japan was hospitalized Patients with pneumonia associated with COVID-19 sometimes show rapid deterioration of the respiratory status, with a poor prognosis The cases encountered by us that we report here also needed intensive long-term respiratory management ARDS is an important pathological condition complicating COVID-19 pneumonia From the perspective of the continuing pathology of ARDS, we treated the patients with a steroid and sivelestat However, it became clear that the respiratory pathology in the patients could not be adequately addressed by the uniform treatment protocol for ARDS In conclusion, inpatient treatment in a local community-based small hospital without an ICU can be extremely difficult

The newt, a group of urodele amphibians, has outstanding ability to repeatedly regenerate various body parts, even in the terrestrial life-stage. In this animal, when the limb is amputated, a cell mass named the blastema appears on the stump and eventually gives rise to a new functional limb. Erythrocytes (red blood cells) in most non-mammalian vertebrates, including the newt, preserve their nucleus throughout their life-span, although physiological roles of such nucleated erythrocytes, other than oxygen delivery, are not known. Here we report novel behavior of erythrocytes in the newt. We identified an orphan gene Newtic1, whose transcripts significantly increased in the blastema. Newtic1 was expressed in a subset of erythrocytes that formed a novel clump (EryC). EryC formed a complex with monocytes and was circulating throughout the body. When the limb was amputated, EryCs were newly generated in the stump and accumulated into a distal portion of the growing blastema. Our data suggested that the newt erythrocytes carried multiple secretory molecules including growth factors and matrix metalloproteases, and were capable of delivering these molecules into the blastema as a form of EryCs. This study provides insight into regulations and roles of nucleated erythrocytes, that are independent of oxygen delivery.

In many animals, the germ plasm is sufficient and necessary for primordial germ cell (PGC) formation. It contains germinal granules and abundant mitochondria (germline-Mt). However, the role of germline-Mt in germ cell formation remains poorly understood. In Xenopus, the germ plasm is distributed as many small islands at the vegetal pole, which gradually aggregates to form a single large mass in each of the four vegetal pole cells at the early blastula stage. Polymerized microtubules and the adapter protein kinesin are required for the aggregation of germ plasm. However, it remains unknown whether germline-Mt trafficking is important for the cytoplasmic transport of germinal granules during germ plasm aggregation. In this study, we focused on the mitochondrial small GTPase protein Rhot1 to inhibit mitochondrial trafficking during the germ plasm aggregation. Expression of Rhot1ΔC, which lacks the C-terminal mitochondrial transmembrane domain, inhibited the aggregation of germline-Mt during early development. In Rhot1-inhibited embryos, germinal granule components did not aggregate during cleavage stages, which reduced the number of PGCs on the genital ridge at tail-bud stage. These results suggest that mitochondrial trafficking is involved in the aggregation of germinal granule components, which are essential for the formation of PGCs.

Digital mock-up (DMU) and/or compound document with 3D data are one of the most important methods to represent a product model. Since the data size of 3D models becomes greater year by year, 3D data compression and retrieval algorithm is required to easily exchange such information through the Internet. Because broadband is still not popular in some regions in the world, it is necessary to send huge data in a small size as much as possible. Therefore, in this paper we developed an application system that transfers 3D surface models and then the performance of the 3D surface compression and retrieval algorithm is evaluated.

To explore the origins and consequences of tetraploidy in the African clawed frog, we sequenced the Xenopus laevis genome and compared it to the related diploid X. tropicalis genome. We characterize the allotetraploid origin of X. laevis by partitioning its genome into two homoeologous subgenomes, marked by distinct families of 'fossil' transposable elements. On the basis of the activity of these elements and the age of hundreds of unitary pseudogenes, we estimate that the two diploid progenitor species diverged around 34 million years ago (Ma) and combined to form an allotetraploid around 17-18 Ma. More than 56% of all genes were retained in two homoeologous copies. Protein function, gene expression, and the amount of conserved flanking sequence all correlate with retention rates. The subgenomes have evolved asymmetrically, with one chromosome set more often preserving the ancestral state and the other experiencing more gene loss, deletion, rearrangement, and reduced gene expression.

Cell signaling pathways, such as Wnt, Hedgehog (Hh), Notch, and Hippo, are essential for embryogenesis, organogenesis, and tissue homeostasis. In this study, we analyzed 415 genes involved in these pathways in the allotetraploid frog, Xenopus laevis. Most genes are retained in two subgenomes called L and S (193 homeologous gene pairs and 29 singletons). This conservation rate of homeologs is much higher than that of all genes in the X. laevis genome (86.9% vs 60.2%). Among singletons, 24 genes are retained in the L subgenome, a rate similar to the average for all genes (82.8% vs 74.6%). In addition, as general components of signal transduction, we also analyzed 32 heparan sulfate proteoglycan (HSPG)-related genes and eight TLE/Groucho transcriptional corepressors-related genes. In these gene sets, all homeologous pairs have been retained. Transcriptome analysis using RNA-seq data from developmental stages and adult tissues demonstrated that most homeologous pairs of signaling components have variable expression patterns, in contrast to the conservative expression profiles of homeologs for transcription factors. Our results indicate that homeologous gene pairs for cell signaling regulation have tended to become subfunctionalized after allotetraploidization. Diversification of signaling pathways by subfunctionalization of homeologs may enhance environmental adaptability. These results provide insights into the evolution of signaling pathways after polyploidization.

Xenopus laevis has an allotetraploid genome of 3.1 Gb, in contrast to the diploid genome of a closely related species, Xenopus tropicalis. Here, we identified 412 genes (189 homeolog pairs, one homeologous gene cluster pair, and 28 singletons) encoding transcription factors (TFs) in the X. laevis genome by comparing them with their orthologs from X. tropicalis. Those genes include the homeobox gene family (Mix/Bix, Lhx, Nkx, Paired, POU, and Vent), Sox, Fox, Pax, Dmrt, Hes, GATA, T-box, and some clock genes. Most homeolog pairs for TFs are retained in two X. laevis subgenomes, named L and S, at higher than average rates (87.1% vs 60.2%). Among the 28 singletons, 82.1% were deleted from chromosomes of the S subgenome, a rate similar to the genome-wide average (82.1% vs 74.6%). Interestingly, nkx2-1, nkx2-8, and pax9, which reside consecutively in a postulated functional gene cluster, were deleted from the S chromosome, suggesting cluster-level gene regulation. Transcriptome correlation analysis demonstrated that TF homeolog pairs tend to have more conservative developmental expression profiles than most other types of genes. In some cases, however, either of the homeologs may show strongly different spatio-temporal expression patterns, suggesting neofunctionalization, subfunctionalization, or nonfunctionalization after allotetraploidization. Analyses of otx1 suggests that homeologs with much lower expression levels have undergone greater amino acid sequence diversification. Our comprehensive study implies that TF homeologs are highly conservative after allotetraploidization, possibly because the DNA sequences that they bind were also duplicated, but in some cases, they differed in expression levels or became singletons due to dosage-sensitive regulation of their target genes.

Bisphenol A (BPA) is being recognized as an endocrine-disrupting chemical (EDC). Recently, several reports indicated that BPA affects the central nervous system (CNS) during embryonic development. However, the molecular mechanism of BPA in the CNS is not well known. Here, we show that BPA affected Notch signaling by inhibiting the activity of the Notch intracellular domain (NICD) cleavage-related enzyme, gamma-secretase (gamma-secretase), at the neurula stage of the Xenopus laevis. BPA caused various morphologic aberrations including scoliosis, eye dysplasia, and loss of pigments in the X. laevis tadpole. These abnormalities were seen whenever BPA was used at the neurula stage. In addition, the expression levels of several marker mRNAs at the neurula stage were investigated by RT-PCR, and we found that the mRNAs expression of ectodermal marker, Pax6, CNS marker, Sox2, and neural crest marker, FoxD3, were decreased by treatment with BPA. These genes contribute to the neural differentiation at the neurula stage, and also the downstream factors of Notch signaling. Injection of NICD but not a Notch ligand, delta 1, rescued the abnormalities caused by BPA. We subsequently assayed the inhibition of the activities of NICD cleavage-related enzymes, tumor necrosis factor alpha converting enzyme, and gamma-secretase, by BPA and found that BPA inhibited the gamma-secretase activity. Furthermore, we expressed presenilin, a main component of gamma-secretase, in Escherichia coli and found the direct binding of BPA with presenilin. These results suggest that BPA affected the neural differentiation by inhibiting gamma-secretase activity, leading to neurodevelopmental abnormalities.

The CSL (CBF-1, Suppressor of Hairless, Lag-1) transcriptional factor is an important mediator of Notch signal transduction. It plays a key role in cell fate determination by cell-cell interaction. CSL functions as a transcriptional repressor before the activation of Notch signaling. However, once Notch signaling is activated, CSL is converted into a transcriptional activator. It remains unclear if CSL has any function during early development before neurogenesis, while transcriptional products exist from the maternal stage. Here, we analyzed the function of Xenopus Suppressor of Hairless (XSu(H)) using morpholino antisense oligonucleotides (MO), which interfere with the translation of transcripts. In Xenopus embryos, maternal transcripts of both XSu(H)1 and XSu(H)2 were ubiquitously observed until the blastula stage and thereafter only XSu(H)1 was zygotically transcribed. Knockdown experiments with MO demonstrated that XSu(H)2 depletion caused a decrease in the expression of the Xbrachyury, MyoD and JNK1 genes. Morphological and histological examinations indicated that XSu(H)2 depletion caused abnormal gastrulation, which resulted in severe defects of the notochord and somitic mesoderm. The effect of XSu(H)2-MO was completely rescued by co-injection of XSu(H)2 mRNAs, but not by XSu(H)1 mRNAs. XESR-1, a Notch signaling target gene, inhibited Xbrachyury expression. However, expression of the XESR-1 gene was not induced by depletion of XSu(H)2. Co-injection of the dominant-negative form of XESR-1 could not rescue the suppression of Xbrachyury expression in the XSu(H)2-depleted embryo. These results suggest that XSu(H)2 is involved in mesoderm formation and the cell movement of gastrula embryos in a different manner from the XESR-1-mediated Notch signaling pathway.

Bisphenol A (BpA) is widely used in industry and dentistry. Its effects on the embryonic development of Xenopus laevis were investigated. Xenopus embryos at stage 10.5 were treated with BpA. Developmental abnormalities were observed at stage 35; malformation of the head region including eyes and scoliosis. The expression of several markers of embryonic development was investigated by reverse transcription-polymerase chain reaction (RT-PCR). The pan-neural marker SOX-2, the neural stem cell marker nrp-1, the mesodermal marker MyoD, and the endodermal marker sox17alpha, were used. Although the expression of marker genes was not changed by treatment with BpA, that of Pax-6, a key regulator of the morphogenesis of the eyes, was decreased by BpA. Pax-6 is a downstream factor of Notch signaling. So, the expression of a typical Notch-dependent factor, ESR-1, was investigated in the presence of BpA. The expression of ESR-1 was efficiently suppressed by BpA. In whole mount in situ hybridization (WISH), Pax-6 was expressed in the central nervous system and eyes. The expression was lost completely on treatment with BpA. The expression of ESR-1 in the central nervous system and eyes also disappeared with BpA treatment. Injection of the intracellular domain of Notch efficiently recovered ESR-1 expression in the presence of BpA although injection of a ligand for notch, Delta, did not. These results suggest that BpA decreased the expression of ESR-1 by disrupting the Notch signal.

The value of 3D CAD models is continuously increasing in downstream processes. The more extensive use of a 3D model outside traditional design and manufacturing is trending now. To distribute 3D data quickly to downstream departments is significant boosts to product quality, production costs, and delivery to markets. Unfortunately, interoperability causes poor communication since downstream applications rely on the reusability and interoperability of CAD models. However, 3D CAD data size for expressing precise forms tends to be big and time-consuming for computation, which may interfere in the communication. In addition, downstream processes emphasize surface smoothness more than precision. Therefore, this paper describes the reconstruction method of a smooth surface by integrating the advantages of Gregory and B-spline surfaces. In this paper, a new surface representation is proposed. Two surfaces are connected with G1-continuity by using the control points at the common boundary obtained from jo...

Mastermind, which is a Notch signal component, is a nuclear protein and is thought to contribute to the transactivation of target genes. Previously we showed that XMam1, Xenopus Mastermind1, was essential in the transactivation of a Notch target gene, XESR-1, and was involved in primary neurogenesis. To examine the function of XMam1 during Xenopus early development in detail, XMam1-overexpressed embryos were analyzed. Overexpression of XMam1 ectopically caused the formation of a cell mass with pigmentation on the surface of embryos and expressed nrp-1. The nrp-1-positive cell mass was produced by XMam1 without expression of the Notch target gene, XESR-1, and not by the activation form of Notch, NICD. The ectopic expression of nrp-1 was not inhibited by co-injection of XMam1 with a molecule known to inhibit Notch signaling. The nrp-1 expression was also recognized in the animal cap injected with XMam1DeltaN, which lacks the basic domain necessary for interacting with NICD and Su(H). These results show that XMam1 has the ability to induce the cell fate into the neurogenic lineage in a Notch-independent manner.

The Notch ligands, Delta/Serrate/Lag-2 (DSL) proteins, mediate the Notch signaling pathway in a numerous developmental processes in multicellular organisms. Although the ligands induce the activation of the Notch receptor, the intracellular domain-deleted forms of the ligands cause dominant-negative phenotypes, implying that the intracellular domain is necessary for the Notch signal transduction. Here we examined the role of the intracellular domain of Xenopus Serrate (XSICD) in Xenopus embryos. X-Serrate-1 has the putative nuclear localization sequence (NLS) in downstream of the transmembrane domain. Biochemical analysis revealed that XSICD fragments are cleaved from the C-terminus side of X-Serrate-1. Fluorescence microscopic analysis showed that the nuclear localization of XSICD occurs in the neuroectoderm of the embryo injected with the full-length X-Serrate-1/GFP. Overexpression of XSICD showed the inhibitory effect on primary neurogenesis. However, a point mutation in the NLSs of XSICD inhibited the nuclear localization of XSICD, which caused the induction of a neurogenic phenotype. The animal cap assay revealed that X-Serrate-1 suppresses primary neurogenesis in neuralized animal cap, but X-Delta-1 does not. Moreover, XSICD could not activate the expression of the canonical Notch target gene, XESR-1 in contrast to the case of full-length X-Serrate-1. These results suggest that the combination of XSICD-mediated intracellular signaling and the extracellular domain of Notch ligands-mediated activation of Notch receptor is involved in the primary neurogenesis. Moreover, we propose a bi-directional signaling pathway mediated by X-Serrate-1 in Notch signaling.

We have cloned a novel krüppel-like transcription factor of Xenopus that encodes POZ/zinc finger protein by expression cloning. Overexpression of mRNA resulted in interference with gastrulation. Because the injected embryo looks like a mushroom in appearance at the neurula stage, we have named this gene champignon (cpg). In cpg-injected embryos, the blastopore appeared normally, but regressed thereafter. The injected embryos then elongated along the primary dorsoventral axis during the tailbud stage. Histologic sections and reverse transcription-polymerase chain reaction analysis showed that cpg had no effect on the cell differentiation. The animal pole region of cpg-injected embryos was thick during the gastrula stage, and mesodermal cells remained in the marginal zone. Furthermore, neither Keller-sandwich explants nor activin-treated animal cap explants excised from cpg-injected embryos elongated. These results suggest that cpg acts as a potent inhibitor of cell migration and cell intercalation during gastrulation.

A cDNA encoding Xenopus type I collagen alpha 1 (Xenopus COL1A1) has been isolated from an ovary cDNA library. The COL1A1 cDNA is approximately 5.7 kb pairs and encodes 1447 amino acids. The putative COL1A1 polypeptide shares high identities of amino acid sequence with other vertebrate COL1A1 proteins. The level of Xenopus COL1A1 transcripts was increased markedly in the posterior region of the embryo at the tail-bud stage, then gradually spread to the anterior region. Histological observations of the tail-bud embryos showed that COL1A1 was mainly expressed in the inner layer of the posterior dorsal epidermis exposed to the somite mesoderm, except for in the dorsal fin. Less intense signals were also detected in the outer layer of the dorsal epidermis and dermatome. The expression of COL1A1 was increased in posteriorized embryos resulting from treatment with retinoic acid but decreased in hyper-dorsalized embryos resulting from lithium chloride treatment. These results suggest that COL1A1 is a major component of the dorsal dermis exposed to the somite in Xenopus embryos, but its expression is not related to the temporal sequence of somite segregation.

A novel gene, Xerl (Xenopus EGF-like repeat with laminin-G domain protein) was isolated from a Xenopus head cDNA library prepared from tailbud. This gene encoded 779 amino acids including a potential signal sequence, twelve EGF-like repeats, a laminin-G domain, a RGD sequence and a VWF motif. In the EGF-like repeat and the laminin-G domain, Xerl showed similarity to those of Drosophila Crumbs, respectively. Zygotic expression of Xerl began at late gastrula, and increased through neurula up to the tailbud stage. In adult organs, Xerl was detected in brain and eye. Whole-mount in situ hybridization showed that Xerl expression occurred first in the anterior bilateral region of neurula and gradually localized to retina and forebrain and boundaries of midbrain and hindbrain.

Blastomeres of the 16-cell stage embryos of the sea urchin, Hemicentrotus pulcherrimus, were separated by an elutriator. By differential display, several RNA species that are enriched in micromeres are detected and their cDNA was cloned. One of the cloned cDNA encodes mt 12S rRNA. cDNA for mt 16S rRNA was also cloned from the cDNA library of unfertilized eggs. Two mt rRNAs contain poly(A) tails in their 3′ ends. Both mt rRNAs distribute asymmetrically along a vegetal-animal axis of the 16-cell embryos and are enriched in micromeres, and this is also confirmed by whole mount in situ hybridization as well as electron microscopic in situ hybridization. As development proceeds, these mt rRNAs become more enriched in small micromeres. Results of electron microscopical in situ hybridization reveal both mt rRNAs localize extramitochondrially. Though at present we have no evidence on the role of the extramitochondrial mt rRNAs in sea urchin development, it is speculated considering roles of extramitochon...

A protocol was developed to fractionate micromeres, mesomeres and macromeres of 16-cell stage sea urchin embryos by elutriation. The purities of these fractions were 99%, 93%, and 90%, and their recoveries were 75%, 31%, and 42%, respectively. Using this method, several hundred milligrams of each blastomere type were obtainable from a single-pair mating. On culture, micromeres formed spicules in the presence of horse serum, mesomeres developed into ciliated ectodermal vesicles and macromeres formed gastrula-like or exogastrula-like embryoids with spicules. To analyze the different structures characteristic of the blastomere lineage, we examined the expressions of marker genes. Cells of the micromere lineage expressed the primary mesenchyme-specific SM50 gene exclusively, those of the mesomere lineage expressed the ectoderm-specific arylsulfatase gene strongly, and SM50 and the endoderm-specific Endo 16 genes weakly, whereas those of the macromere lineage expressed all three marker genes. These results indicate that blastomeres fractionated by elutriation were equivalent to those isolated by hand under a microscope with respect to development and gene expression.

The notch signaling pathway is widely conserved from vertebrates to invertebrates and mediates the specification of numerous cell fates during developmental processes. In the Xenopus gastrula embryo, Xdelta1, one of the Notch ligands, is expressed in the prospective mesoderm prior to Xbra expression. Here, we examined the role of Notch signaling in mesoderm formation. Embryos injected with Xdelta1 morpholino oligo DNA showed a severe gastrulation defect and suppression of Xbra expression, which were completely rescued by co-injection with the active form of Notch. In order to fully understand the role of Notch signaling, we examined the expression of the Notch target genes XESR1 and XESR5. RT-PCR and whole-mount in situ hybridization analyses showed that XESR5 was highly expressed in the marginal zone of the early gastrula embryo, whereas expression of XESR1 was not detected. Animal cap assays indicated that expression of XESR5 was not induced by Notch signaling but by nodal signaling. To clarify the role of XESR5 in the gastrula embryo, a dominant negative form of XESR5 was injected into the prospective mesoderm. The truncated form of XESR5 induced the ectopic expression of XESR1, which caused a decrease in Xbra expression and defective gastrulation. In contrast, the truncated form of XESR1 caused an upregulation of XESR5 resulting in an increase in Xbra expression. The antagonistic effect of XESR1 and XESR5 suggests a dual regulation in which XESR5 produces a competent area for mesoderm formation by suppressing the gene expression of XESR1, while XESR1 sharpens the boundary of Xbra expression.

Abnomalities in serum cholinesterase (ChE) are rarely reported in Japan. In the past 20 years, 30 cases have been reported and only three of these occurred in children. We experienced a patient presenting with very low ChE levels who had an attack of prolonged apnea over along period following a radical operation on a right external inguinal hernia. The patient was an one-year-old female infant. There was no past or family history and no abnormalities in ordinary tests on admission. Anesthesia was induced by 10 mg of SCC intravenously and was maintained by GOF after intubation. The operating time was 13 minutes, but spontaneus respiration was delayed to appear postopertively. The serum ChE was 1 mu/ml (normal range: 173432 mu/ml) and it took about 3 hours were spontanous respiration appeared. The postoperative course was favorable thereafter. The diagnosis of the disease was suspected from nerve stimulation during anesthesia, and was confirmed by taking blood samples. It appears that a nerve stimulator is effective as a monitor of prolonged apnea.

Xoom has been identified as a novel gene that plays an important role in gastrulation of Xenopus laevis embryo. Although Xoom is actively transcribed during oogenesis, distribution and function of its translation product have not yet been clarified. In the present study, the polyclonal antibody raised against Xoom was generated to investigate a behavior of Xoom protein. Anti-Xoom antibodies revealed that there are two forms of Xoom protein in Xenopus embryos: (i) a 45 kDa soluble cytoplasmic form; and (ii) a 44 kDa membrane-associated form. Two forms of Xoom protein were ubiquitously detected from unfertilized egg to tadpole stage, with a qualitative peak during blastula and gastrula stages. Immunohistochemical examination showed that Xoom protein is maternally stored in the animal subcortical layer and divided into presumptive ectodermal cells during cleavage stages. Enzymatic digestion of membrane protein and immunologic detection of Xoom showed that Xoom exists as a membrane-associated protein. To examine a function of Xoom protein, anti-Xoom antibodies were injected into blastocoele of stage 7 blastula embryo. Anti-Xoom antibodies caused gastrulation defect in a dose- dependent manner. These results suggest that maternally prepared Xoom protein is involved in gastrulation movement on ectodermal cells.

Gastrulation is the most dynamic cell movement and initiates the body plan in amphibian development. In contrast to numerous molecular studies on mesodermal induction, the driving force of gastrulation is as yet poorly understood. A novel transmembrane protein, Xoom, was previously reported, which is required for Xenopus gastrulation. In the present study, the role of Xoom during Xenopus gastrulation was further examined in detail. Overexpression and misexpression of Xoom induced overproduction of Xoom protein, but not a changed phenotype. However, Xoom antisense ribonucleic acid (RNA) injection reduced the Xoom protein and caused gastrulation defects without any influence on the involution and translation levels of mesodermal marker genes. Normal migrating activity of dorsal mesodermal cells was recognized in the antisense RNA-injected explant. Morphological examination using artificial exogastrulation showed that convergent extension of mesodermal cells occurred normally, but the ectodermal cell layer significantly shrank in the antisense RNA-injected embryo. Comparison of cell shape among various experimental conditions showed that inhibition of cell spreading occurs specifically in the outer ectodermal layer of the antisense RNA-injected embryo. Cytochemical examination indicated disorganization of F-actin in the ectodermal cells of the antisense RNA-injected embryo. These results suggest that Xoom plays an important role in the epibolic movement of ectodermal cells through some regulation of actin filament organization.

Different features in the fibroblasts and the macrophages, which are prominent cell types in the dermis of the dorsal tail fin of the larval axolotl, Ambystoma mexicanum, and the tadpole, Rana japonica, were examined by light and electron microscopy. At the non-metamorphic stages, the cytoplasm of the macrophage, loaded with numerous lysosomes, is generally located in the cell periphery. Outstanding was the presence of many ruffles or microvillous projections of different shapes and sizes in the plasma membrane. In contrast, the fibroblasts are spindle-shaped and possess less numerous microvillous projections compared with the macrophages, and extracellular spaces neighboring the fibroblasts are loaded with collagen fibers. The fibroblasts are located superficially and sometimes contact each other by the desmosomes. The macrophages are situated relatively deep in the dermis. At the metamorphic stages, both fibroblasts and macrophages contain many phagolysosomes in common, but the desmosomes still remain between the fibroblasts, and therefore the fibroblasts are distinguished from the macrophages. The macrophages are characterized by the their phagolysosomes which contain degenerating cells or cell debris of fibroblasts, myelinated nerve fibers and neutrophils. The macrophages also exhibit a higher endocytotic activity than the fibroblasts for the injected foreign particles (FITC-dextran or latex beads). On the other hand, the phagolysosomes (or autophagolysosomes) of the fibroblasts are characterized by intracellular collagen fibers. These different phagolysosomes between the macrophages and the fibroblasts mean that they may play different roles in the degeneration of the cellular or the extracellular components, respectively, of the tail fins during metamorphosis.

Recently, tracheostomy has been utilized widely, both in critical and intensive care patients, as a means of providing more secured airways, especially for those who require intensive and long-term respiratory care. In brief, tracheostomy-once considered an emergency procedure-has not become one of the elective procedures for such patients.However, tracheostomy complications such as bleeding, infection, emphysema, granulations, tracheal stenosis and other post-tracheostomy complications still are encountered in some cases even in skilled and experienced hands.Among 210 of our recent tracheostomy cases, there were four most informative cases of tracheostomy complications encountered during tracheostomy and in the post-tracheostomy period, suggesting the importance of proper selection of the cannula, atraumatic technique, fixation and position of the cannula, and prevention of post-operative granulation formation. In a fifth and very unusual case, a suture was accidentally swallowed and lodged at the esophageal orifice and remained until routine post-tracheostomy X-ray taken approximately 4 weeks later.The carefully planned and practiced tracheostomy with endotracheal tube in place under optimal anesthetic state would be the choice in avoiding such unfavorable complications.