PubMed Health⌕ Search

Biomedical subjects

Kei Ito

Publications and source records attributed to Kei Ito.

34 records · Page 2Linked to original sources
PubMed2004

Engulfing action of glial cells is required for programmed axon pruning during Drosophila metamorphosis.

BACKGROUND: Axon pruning is involved in establishment and maintenance of functional neural circuits. During metamorphosis of Drosophila, selective pruning of larval axons is developmentally regulated by ecdysone and caused by local axon degeneration. Previous studies have revealed intrinsic molecular and cellular mechanisms that trigger this pruning process, but how pruning is accomplished remains essentially unknown. RESULTS: Detailed analysis of morphological changes in the axon branches of Drosophila mushroom body (MB) neurons revealed that during early pupal stages, clusters of neighboring varicosities, each of which belongs to different axons, disappear simultaneously shortly before the onset of local axon degeneration. At this stage, bundles of axon branches are infiltrated by the processes of surrounding glia. These processes engulf clusters of varicosities and accumulate intracellular degradative compartments. Selective inhibition of cellular functions, including endocytosis, in glial cells via the temperature-sensitive allele of shibire both suppresses glial infiltration and varicosity elimination and induces a severe delay in axon pruning. Selective inhibition of ecdysone receptors in the MB neurons severely suppressed not only axon pruning but also the infiltration and engulfing action of the surrounding glia. CONCLUSIONS: These findings strongly suggest that glial cells are extrinsically activated by ecdysone-stimulated MB neurons. These glial cells infiltrate the mass of axon branches to eliminate varicosities and break down axon branches actively rather than just scavenging already-degraded debris. We therefore propose that neuron-glia interaction is essential for the precisely coordinated axon-pruning process during Drosophila metamorphosis.

Alleles↗
PubMed2004

Integration of chemosensory pathways in the Drosophila second-order olfactory centers.

BACKGROUND: Behavioral responses to odorants require neurons of the higher olfactory centers to integrate signals detected by different chemosensory neurons. Recent studies revealed stereotypic arborizations of second-order olfactory neurons from the primary olfactory center to the secondary centers, but how third-order neurons read this odor map remained unknown. RESULTS: Using the Drosophila brain as a model system, we analyzed the connectivity patterns between second-order and third-order olfactory neurons. We first isolated three common projection zones in the two secondary centers, the mushroom body (MB) and the lateral horn (LH). Each zone receives converged information via second-order neurons from particular subgroups of antennal-lobe glomeruli. In the MB, third-order neurons extend their dendrites across various combinations of these zones, and axons of this heterogeneous population of neurons converge in the output region of the MB. In contrast, arborizations of the third-order neurons in the LH are constrained within a zone. Moreover, different zones of the LH are linked with different brain areas and form preferential associations between distinct subsets of antennal-lobe glomeruli and higher brain regions. CONCLUSIONS: MB is known to be an indispensable site for olfactory learning and memory, whereas LH function is reported to be sufficient for mediating direct nonassociative responses to odors. The structural organization of second-order and third-order neurons suggests that MB is capable of integrating a wide range of odorant information across glomeruli, whereas relatively little integration between different subsets of the olfactory signal repertoire is likely to occur in the LH.

Animals↗
PubMed2004

Endoscopic approach to early diagnosis of pancreatic cancer.

Since its development, endoscopic retrograde cholangiopancreatography (ERCP) has been playing a major role in the diagnosis of pancreatic diseases. The recent development of magnetic resonance cholangiopancreatography has accelerated the shift in the role of ERCP toward more therapy-oriented applications. In the diagnosis and treatment of curable pancreatic cancer, however, ERCP remains the mainstay of imaging modalities. ERCP is not simply a method with which to obtain x-ray images of the pancreatic duct. Collection of pure pancreatic juice, transpapillary biopsy/brush cytology of the pancreatic duct, intraductal ultrasonography, and peroral pancreatoscopy are all performed based on the ERCP technique. Endoscopic ultrasonography (EUS) has a high spatial resolution and provides tomographic images of the pancreas and its neighboring organs. EUS is now widely used in evaluation of the local extent of pancreatic cancer and the differential diagnosis of cystic lesions of the pancreas. EUS-guided fine needle aspiration biopsy/cytology is performed to obtain a histologic diagnosis before beginning chemotherapy. Although the number of pancreatic cancer patients who are candidates for surgery is limited at present, there is an increasing need for ERCP-based techniques in both the diagnosis and treatment of pancreatic neoplasms.

Carcinoma, Pancreatic Ductal↗
PubMed2004

Percutaneous cholecystostomy versus gallbladder aspiration for acute cholecystitis: a prospective randomized controlled trial.

OBJECTIVE: This study was performed to determine and compare the effectiveness and incidence of complications of percutaneous cholecystostomy and gallbladder aspiration in cases of severe acute cholecystitis. SUBJECTS AND METHODS. Fifty-eight patients with severe acute cholecystitis who did not improve after antibiotic treatment were included in this study. The patients were randomized into either the percutaneous cholecystostomy group (n = 30) or the gallbladder aspiration group (n = 28). Under sonographic guidance, percutaneous cholecystostomy was performed in the usual manner using a 6.5- or 7-French catheter. Gallbladder aspiration was carried out with a 21-gauge needle under sonographic guidance. The technical success, clinical response, and complications in each group were evaluated. RESULTS: Percutaneous cholecystostomy and gallbladder aspiration were technically successful in 30 patients (100%) and 23 patients (82%), respectively (not statistically significant). In five patients (18%) of the gallbladder aspiration group, aspiration was unsuccessful because of replacement of bile with dense biliary sludge or pus. Good clinical response was obtained in 27 patients (90%) of the percutaneous cholecystostomy group and in 14 patients (61%) of the gallbladder aspiration group (p < 0.05). As for complications, dislodgment of the catheter occurred in one patient of the percutaneous cholecystostomy group and minor bleeding in one patient after gallbladder aspiration. No major complications or procedure-related deaths occurred in either group. CONCLUSION: For severe acute cholecystitis, percutaneous cholecystostomy was superior to gallbladder aspiration in terms of clinical effectiveness and had the same complication rate as gallbladder aspiration.

Acute Disease↗
PubMed2003

Developmental origin of wiring specificity in the olfactory system of Drosophila.

In both insects and mammals, olfactory receptor neurons (ORNs) expressing specific olfactory receptors converge their axons onto specific glomeruli, creating a spatial map in the brain. We have previously shown that second order projection neurons (PNs) in Drosophila are prespecified by lineage and birth order to send their dendrites to one of approximately 50 glomeruli in the antennal lobe. How can a given class of ORN axons match up with a given class of PN dendrites? Here, we examine the cellular and developmental events that lead to this wiring specificity. We find that, before ORN axon arrival, PN dendrites have already created a prototypic map that resembles the adult glomerular map, by virtue of their selective dendritic localization. Positional cues that create this prototypic dendritic map do not appear to be either from the residual larval olfactory system or from glial processes within the antennal lobe. We propose instead that this prototypic map might originate from both patterning information external to the developing antennal lobe and interactions among PN dendrites.

Animals↗
PubMed2003

Cautionary observations on preparing and interpreting brain images using molecular biology-based staining techniques.

Though molecular biology-based visualization techniques such as antibody staining, in situ hybridization, and induction of reporter gene expression have become routine procedures for analyzing the structures of the brain, precautions to prevent misinterpretation have not always been taken when preparing and interpreting images. For example, sigmoidal development of the chemical processes in staining might exaggerate the specificity of a label. Or, adjustment of exposure for bright fluorescent signals might result in overlooking weak signals. Furthermore, documentation of a staining pattern is affected easily by recognized organized features in the image while other parts interpreted as "disorganized" may be ignored or discounted. Also, a higher intensity of a label per cell can often be confused with a higher percentage of labeled cells among a population. The quality, and hence interpretability, of the three-dimensional reconstruction with confocal microscopy can be affected by the attenuation of fluorescence during the scan, the refraction between the immersion and mounting media, and the choice of the reconstruction algorithm. Additionally, visualization of neurons with the induced expression of reporter genes can suffer because of the low specificity and low ubiquity of the expression drivers. The morphology and even the number of labeled cells can differ considerably depending on the reporters and antibodies used for detection. These aspects might affect the reliability of the experiments that involves induced expression of effector genes to perturb cellular functions. Examples of these potential pitfalls are discussed here using staining of Drosophila brain.

Animals↗
PubMed2003

Serous cystadenoma of the pancreas associated with obstructive jaundice.

We herein report a case of pancreatic serous cystadenoma in a patient who presented with jaundice, and we provide a review of the literature. A 53-year-old man was admitted with complaints of jaundice and weight loss. With a preoperative diagnosis of pancreatic serous cystadenoma with obstructive jaundice, he underwent pylorus-preserving pancreatoduodenectomy. A cystic tumor partially protruding into the bile duct was observed in the pancreatic head. Histology verified serous cystadenoma of the pancreas. Histologically, no atypia was proven in the epithelium. There have been only eight case reports dealing with serous cystadenoma of the pancreas with obstructive jaundice. Although serous cystadenoma of the pancreas has essentially a benign nature, pylorus-preserving pancreatoduodenectomy is the treatment of choice when available to avoid the recurrence of obstructive jaundice.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed2003

Abnormal arrangement of the pancreato-biliary ductal system associated with advanced gallbladder cancer diagnosed 3 years after follow-up ultrasonography.

We herein report a case of abnormal arrangement of the pancreato-biliary ductal system (AAPB) followed by advanced gallbladder cancer 9 years after the initial endoscopic retrograde cholangiopancreatography (ERCP) diagnosis and almost 3 years after follow-up ultrasonography (US). A 65-year-old woman was referred to our department from a private clinic because of difficulty in controlling her diabetes mellitus. The patient had no complaints, and physical examination revealed no jaundice in her skin or conjunctiva. ERCP demonstrated the presence of AAPB (bile duct-main type) without congenital dilatation of the bile duct or irregularity in the gallbladder wall. She did not wish to undergo cholecystectomy. Follow-up transabdominal US revealed no change in the gallbladder. Two years and 9 months after this US examination, she developed advanced gallbladder cancer involving the liver and bile duct, with paraaortic lymph node metastases confirmed by US, computed tomography, and ERCP. This case re-emphasizes the necessity for patients with AAPB to undergo intensive follow-up examinations or cholecystectomy when the diagnosis of AAPB has been established.

Aged↗
PubMed2003

Development of clinical pathway in S-1 chemotherapy for gastric cancer.

We have developed a clinical pathway to enable the safe continuous administration of S-1 (TS-1) in ambulatory care for patients with advanced gastric cancer. The S-1 clinical pathway includes a pathway for clinicians, a pathway for patients, and such assist tools as a medication diary, an explanatory document containing instructions relating to patient compliance, a table of associations between adverse reactions and prodromes, and general principles for dose reduction and withdrawal. These pathways and assist tools will improve the patient's perception of adverse reactions, thereby contributing to early discovery and rapid action against adverse events. The S-1 clinical pathway has been used with ten patients. S-1 administration has been continued in seven patients. In four of the seven patients, continued administration on the occurrence of adverse reactions was made possible by the use of appropriate measures such as drug withdrawal or dose reduction. It was confirmed that the S-1 clinical pathway was a useful tool for cancer chemotherapy in ambulatory care.

Adult↗
PubMed2003

Neutrophil-rich anaplastic large cell lymphoma presenting in the skin.

A neutrophil-rich anaplastic large cell lymphoma (ALCL) presented in the skin of a 47-year-old Japanese woman. The solitary cutaneous lesion was an eroded, 10-mm, dome-shaped nodule involving the skin of her left upper arm. Histologically, it showed a proliferation of pleomorphic, anaplastic, large tumor cells with nuclei of various shapes, including embryo-shaped, Reed-Sternberg cell-like binucleated, and wreath-shaped multiple nuclei, in the dermis and subcutaneous tissues. There was an admixture of neutrophils ranging from about 30% to more than 50% per field. Immunophenotypically, the neoplastic cells were positive for CD30, CD4, leukocyte common antigen, anaplastic lymphoma kinase-1, epithelial membrane antigen, and granzyme B. She had no peripheral neutrophilia. The lesson was excised, and the site on the left upper arm was irradiated. Six and a half months after diagnosis, however, swelling of a left axillary lymph node appeared; it also showed a proliferation of anaplastic large tumor cells admixed with numerous neutrophils ranging from about 25% to more than 60% per field. Southern blot analysis of T-cell receptor gene rearrangement revealed a clonal band. The patient was treated with six courses of cyclophosphamide, doxorubicin, vincristine, and prednisolone chemotherapy with complete remission. Seventeen cases of neutrophil-rich ALCL arising in the skin, lymph node, muscle, testis, and skull bone were reviewed. This form may possibly be induced by trauma or irritation of conventional ALCL, although the true mechanism for the infiltration of neutrophils is still unclear.

Anaplastic Lymphoma Kinase↗
PubMed2002

Mushroom bodies are not required for courtship behavior by normal and sexually mosaic Drosophila.

To elucidate the effect of feminization of male Drosophila brain cells on courtship control, we performed a large scale screening of expression drivers that can suppress male-specific behavior with transformer gene expression. Two drivers caused essentially total courtship suppression. The expression pattern of these drivers did not show any correlation with the mushroom bodies or the antennal lobes, the regions that have been suggested to play important roles in courtship. Ablation of mushroom bodies using hydroxyurea treatment did not affect this courtship suppression. The ablation did not change either wild-type heterosexual behavior or bisexual behavior caused by transformer expression driven by the same drivers used in the previous studies to suggest the involvement of the mushroom bodies in courtship. Our results show that feminization of different nonoverlapping cells in other parts of the protocerebrum was sufficient to cause the same bisexual or suppressed-courtship phenotype. Thus, contrary to previous assumptions, the mushroom bodies are not required for the control of courtship. Present evidence supports its mediation by other distributed protocerebral regions.

Animals↗
PubMed2002

Diagnosis of pT2 gallbladder cancer by serial examinations with endoscopic ultrasound and angiography.

BACKGROUND: The prognosis of pT2 gallbladder cancer correlates with whether appropriate surgery for the spread of cancer has been performed. Therefore, accurate preoperative T staging is especially important. We carried out this study to evaluate the usefulness of serial examinations by endoscopic ultrasound (EUS) and angiography for the T staging of pT2 gallbladder cancer. METHODS: Forty-eight patients with gallbladder cancer who underwent both EUS and surgery between 1983 and 1998 were included in this study. The accuracy of serial examination by both EUS and angiography in T staging, based on previously established diagnostic criteria, was retrospectively evaluated. First, the presence or absence of subserosal tumor invasion was assessed by EUS alone. Second, in equivocal cases, the depth of tumor invasion was further evaluated by angiographic findings. RESULTS: Twenty-four patients were correctly diagnosed as having other than pT2 cancer by EUS alone. Angiographic findings were reviewed in 19 of the remaining patients, who had pT1, pT2, or a small number of pT3 lesions. The sensitivity, specificity, and overall accuracy in the T staging of pT2 gallbladder cancer was 81.8%, 90.6%, and 88.4%, respectively. CONCLUSIONS: Serial angiographic examination following adequate patient selection by EUS is effective and efficient for the diagnosis of pT2 gallbladder cancer.

Adult↗
PubMed2002

Solid cystic tumor of the pancreas: report of six cases and a review of the Japanese literature.

Although many cases of solid cystic tumor of the pancreas (SCT) have been reported, its nature and histogenesis remain controversial. We herein report six cases of SCT, including three cases of noncystic type. A review of 22 cases of noncystic type SCT, including our 3 cases, was carried out to compare their features with those of 173 cases of classic SCT reported in Japan. Noncystic type SCTs tend to occur in male patients and are smaller in size and less frequently symptomatic, although they show histological characteristics similar to those of classic SCTs. The developmental process might be a cause of cyst formation. The accumulation and analysis of many, at present, "atypical" cases for clarification of its nature, will, it is hoped, lead to a new nomenclature for this condition that adequately describes its biological origin.

Adolescent↗
PubMed2002

Perforated duodenal ulcer associated with an incarcerated hiatal hernia: report of a case.

We report the case of a perforated duodenal ulcer and diffuse peritonitis associated with an incarcerated hiatal hernia. A 77-year-old woman with a 17-year history of rheumatoid arthritis treated with nonsteroidal anti-inflammatory drugs, who had also been receiving treatment for non-Hodgkin's lymphoma over 4 years, was referred to us for investigation of nausea and vomiting. An abdominal compute tomography (CT) scan showed an incarcerated hiatal hernia and free air in the hernia sac. Emergency laparotomy revealed an incarcerated hiatal hernia involving the stomach, transverse colon, and omentum. A perforated ulcer was also found in the posterior wall of the first portion of the duodenum. The combination of these disorders is thought to be rare in patients with a hiatal hernia and free air in its sac. As the reported mortality of perforated gastric ulcer associated with a hiatal hernia is high, early elective surgery should be performed in patients with a duodenal ulcer associated with a hiatal hernia.

Aged↗
PubMed2002

Embryonic and larval development of the Drosophila mushroom bodies: concentric layer subdivisions and the role of fasciclin II.

Mushroom bodies (MBs) are the centers for olfactory associative learning and elementary cognitive functions in the arthropod brain. In order to understand the cellular and genetic processes that control the early development of MBs, we have performed high-resolution neuroanatomical studies of the embryonic and post-embryonic development of the Drosophila MBs. In the mid to late embryonic stages, the pioneer MB tracts extend along Fasciclin II (FAS II)-expressing cells to form the primordia for the peduncle and the medial lobe. As development proceeds, the axonal projections of the larval MBs are organized in layers surrounding a characteristic core, which harbors bundles of actin filaments. Mosaic analyses reveal sequential generation of the MB layers, in which newly produced Kenyon cells project into the core to shift to more distal layers as they undergo further differentiation. Whereas the initial extension of the embryonic MB tracts is intact, loss-of-function mutations of fas II causes abnormal formation of the larval lobes. Mosaic studies demonstrate that FAS II is intrinsically required for the formation of the coherent organization of the internal MB fascicles. Furthermore, we show that ectopic expression of FAS II in the developing MBs results in severe lobe defects, in which internal layers also are disrupted. These results uncover unexpected internal complexity of the larval MBs and demonstrate unique aspects of neural generation and axonal sorting processes during the development of the complex brain centers in the fruit fly brain.

Animals↗