Search PubMed⌕ Search

Biomedical subjects

Y Kimata

Publications and source records attributed to Y Kimata.

At least 19 recordsLinked to original sources
PubMed2006

Immediate maxillary reconstruction after malignant tumor extirpation.

AIMS: Immediate maxillary reconstruction after malignant tumor extirpation differs from other types of maxillary reconstruction. Our reconstruction algorithm is described in this article. METHODS: One hundred ninety-four patients who had undergone maxillectomy for malignant tumors were reviewed, and maxillectomy defects were classified with the method of Cordeiro and Santamaria. RESULTS: Mean total blood loss was 848 ml, and 71 patients died within 2 years after surgery. For type IIIa defects of the orbital floor, titanium mesh or vascularized bone or cartilage was used for reconstruction, but the rate of postoperative complications did not differ between titanium and autografts. Therefore, to reconstruct orbital floor defects we have recently used only titanium mesh. For type I or II defects, we use autografts for only selected cases. CONCLUSIONS: We strive to perform less-invasive reconstructive surgery after resection for maxillary malignancy.

Aged↗
PubMed2001

Efficient radical trapping at the surface and inside the phospholipid membrane is responsible for highly potent antiperoxidative activity of the carotenoid astaxanthin.

The effects of the carotenoids beta-carotene and astaxanthin on the peroxidation of liposomes induced by ADP and Fe(2+) were examined. Both compounds inhibited production of lipid peroxides, astaxanthin being about 2-fold more effective than beta-carotene. The difference in the modes of destruction of the conjugated polyene chain between beta-carotene and astaxanthin suggested that the conjugated polyene moiety and terminal ring moieties of the more potent astaxanthin trapped radicals in the membrane and both at the membrane surface and in the membrane, respectively, whereas only the conjugated polyene chain of beta-carotene was responsible for radical trapping near the membrane surface and in the interior of the membrane. The efficient antioxidant activity of astaxanthin is suggested to be due to the unique structure of the terminal ring moiety.

Adenosine Diphosphate↗
PubMed2001

Translational control by the ER transmembrane kinase/ribonuclease IRE1 under ER stress.

Under conditions of endoplasmic reticulum (ER) stress, mammalian cells induce both translational repression and the unfolded protein response that transcriptionally activates genes encoding ER-resident molecular chaperones. To date, the only known pathway for translational repression in response to ER stress has been the phosphorylation of eIF-2alpha by the double-stranded RNA-activated protein kinase (PKR) or the transmembrane PKR-like ER kinase (PERK). Here we report another pathway in which the ER transmembrane kinase/ribonuclease IRE1beta induces translational repression through 28S ribosomal RNA cleavage in response to ER stress. The evidence suggests that both pathways are important for efficient translational repression during the ER stress response.

Amino Acid Sequence↗
PubMed2001

Diphtheria toxin receptor-mediated conditional and targeted cell ablation in transgenic mice.

Specific cell ablation is a useful method for analyzing the in vivo function of cells. We have developed a simple and sensitive method for conditional cell ablation in transgenic mice, called "toxin receptor-mediated cell knockout." We expressed the diphtheria toxin (DT) receptor in transgenic mice using a hepatocyte-specific promoter and found that injection of DT caused fulminant hepatitis. Three independently established transgenic lines demonstrated a good correlation between the sensitivity of hepatocytes to DT and the expression level of the DT receptors. Moreover, the degree of hepatocyte damage was easily controlled over a wide range of doses of injected DT without any obvious abnormalities in other cells or tissues. This system is useful for generating mouse models of disease and for studying the recovery or regeneration of tissues from cell damage or loss. As DT is a potent inhibitor of protein synthesis in both growing and non-growing cells, the method is applicable to a wide range of cells and tissues in mice or in other DT-insensitive animals.

Albumins↗
PubMed2001

Deep circumflex iliac perforator flap with iliac crest for mandibular reconstruction.

The deep circumflex iliac myocutaneous perforator (DCIP) flap with iliac crest was used to reconstruct oromandibular defects in 10 patients. In seven of the patients a dominant perforator was found preoperatively using a Doppler flowmeter; in five of these seven patients a DCIP flap was successfully transferred. In two of the seven patients the dominant perforators were too narrow: one patient underwent a standard osteocutaneous flap transfer and one patient underwent a second flap transfer. In three patients no dominant perforator was found before or during surgery. The freedom of the DCIP flap from the harvested iliac crest facilitates correct positioning. However, to ensure that the DCIP flap can be safely elevated, the presence of perforators must be confirmed preoperatively. Even when a perforator has been identified, complicated dissection may be necessary. We stress the importance of a thorough knowledge of the anatomy of second flaps and of obtaining informed consent to use them.

Adult↗
PubMed2001

Mandibular reconstruction using microvascular free flaps: a statistical analysis of 178 cases.

For this article, 178 consecutive cases of mandibular reconstruction using microvascular free flaps and performed from 1979 to 1997 were studied. The purpose of this report is to compare flap success rates, complications, and aesthetic and functional results. The ages of the 131 men and 47 women ranged from 13 to 85 years, with an average of 55 years. Donor sites included the rib (11 cases), radius (one case), ilium (36 cases), scapula (51 cases), fibula (34 cases), and soft-tissue flaps with implant (45 cases). Complications included total flap necrosis, partial flap necrosis, major fistula formation, and minor fistula formation. The rate of total flap necrosis involving the ilium and fibula was significantly higher than that of all other materials combined (p < 0.05). The overall rate of implant plate removal, which resulted from the exposure or fracture of the plate, was 35.6 percent (16 of 45 cases). Each mandibular defect was classified by the extent of the bony defect and by the extent of the soft-tissue defect. The extent of the mandibular bony defect was classified according to the HCL method of Jewer et al. The extent of the soft-tissue defect was classified into four groups: none, skin, mucosal, and through-and-through. According to these classifications, functional and aesthetic assessments of deglutition and contour were performed on 115 subjects, and speech was evaluated in 110. To evaluate the postoperative results, points were assigned to each assessment of deglutition, speech, and mandibular contour. Statistical analysis between pairs of bone-defect groups revealed that there was no significant difference in each category. Regarding deglutition, statistical analysis between pairs of soft-tissue-defect groups revealed there were significant differences (p < 0.05) between the none and the mucosal groups and also between the none and the through-and-through groups. Regarding speech, there was a significant difference (p < 0.05) between the none and the through-and-through groups. Regarding contour, there were significant differences (p < 0.01) between the none and the through-and-through groups and between the mucosal and the through-and-through groups. The points given for each function, depending on the reconstruction material, revealed that there was no significant difference between pairs of material groups. From this prospective study, the authors have developed an algorithm for oromandibular reconstruction. When the bony defect is lateral, the ilium, fibula, or scapula should be chosen as the donor site, depending on the extent of the soft-tissue defect. When the bony defect is anterior, the fibula is always the best choice. When the soft-tissue defect is extensive or through-and-through with an anterior bony defect, the fibula should be used with other soft-tissue flaps.

Adolescent↗
PubMed2001

Molecular characterization of two Arabidopsis Ire1 homologs, endoplasmic reticulum-located transmembrane protein kinases.

A major response of eukaryotic cells to the presence of unfolded proteins in the lumen of the endoplasmic reticulum (ER) is to activate genes that encode ER-located molecular chaperones, such as the binding protein. This response, called the unfolded protein response, requires the transduction of a signal from the ER to the nucleus. In yeast (Saccharomyces cerevisiae) and mammalian cells, an ER-located transmembrane receptor protein kinase/ribonuclease called Ire1, with a sensor domain in the lumen of the ER, is the first component of this pathway. Here, we report the cloning and derived amino acid sequences of AtIre1-1 and AtIre1-2, two Arabidopsis homologs of Ire1. The two proteins are located in the perinuclear ER (based on heterologous expression of fusions with green fluorescent protein). The expression patterns of the two genes (using beta-glucuronidase fusions) are nearly nonoverlapping. We also demonstrate functional complementation of the sensor domains of the two proteins in yeast and show that the Ire1-2 protein is capable of autotransphosphorylation. These and other findings are discussed in relation to the involvement of these genes in unfolded protein response signaling in plants.

Amino Acid Sequence↗
PubMed2000

Identification of a novel mammalian endoplasmic reticulum-resident KDEL protein using an EST database motif search.

Several endoplasmic reticulum (ER)-resident proteins contain a unique C-terminal sequence (KDEL) which is required for the retention of these proteins in the ER. By searching a mouse EST database for records containing the nucleotide sequence encoding the KDEL motif, we extracted cDNAs encoding putative novel ER-resident proteins in addition to all of the known ER proteins bearing the KDEL motif. Using the sequence information obtained by this database search, we cloned the cDNA encoding a novel KDEL motif-bearing protein, ER protein 58 (EP58), sharing no significant homology to any of the known ER-resident proteins. Subcellular localization of EP58 in the ER was confirmed by cytoimmunofluorescence studies using epitope-tagged EP58. The EP58 gene was primarily expressed in embryo, placenta, and adult heart. Neither heat shock nor ER stress as tested here was sufficient to induce expression of the EP58 gene. A putative role of the N-terminal half of EP58 in protein-protein interaction is suggested by its similarity to the filamin rod domain. Similarity of the EP58 sequence with bacterial and fungus proteins suggests a possible role for EP58 in polysaccharide biosynthesis.

Amino Acid Sequence↗
PubMed2000

Dissociation of Kar2p/BiP from an ER sensory molecule, Ire1p, triggers the unfolded protein response in yeast.

The unfolded protein response (UPR) is a signal transduction pathway induced by a variety of endoplasmic reticulum (ER) stresses and functions to maintain homeostasis of the cellular membrane in eukaryotes. Various ER stresses result in the accumulation of unfolded proteins in the ER, which is sensed by the transmembrane protein kinase/ribonuclease Ire1p that transmits a signal from the ER to the nucleus in Saccharomyces cerevisiae. Here we report that the yeast ER chaperone Kar2p/BiP, a member of the HSP70 family found in the ER, directly regulates the UPR by the interaction with Ire1p. In the absence of ER stress, Kar2p binds the lumenal domain of Ire1p and keeps Ire1p in an inactive unphosphorylated state. Upon exposure of cells to ER stresses, Kar2p is released from Ire1p, resulting in activation of Ire1p and signal transduction to the nucleus. Subsequently, KAR2 mRNA is induced and Kar2p accumulates in the ER in a time-dependent manner, restoring the system to the basal state. This negative autoregulation is similar to the regulation of mammalian cytosolic chaperone Hsp70 via its interaction with heat shock factor 1.

Cloning, Molecular↗
PubMed2000

The Saccharomyces cerevisiae RuvB-like protein, Tih2p, is required for cell cycle progression and RNA polymerase II-directed transcription.

Two highly conserved RuvB-like putative DNA helicases, p47/TIP49b and p50/TIP49a, have been identified in the eukaryotes. Here, we study the function of Saccharomyces cerevisiae TIH2, which corresponds to mammalian p47/TIP49b. Tih2p is required for vegetative cell growth and localizes in the nucleus. Immunoprecipitation analysis revealed that Tih2p tightly interacts with Tih1p, the counterpart of mammalian p50/TIP49a, which has been shown to interact with the TATA-binding protein and the RNA polymerase II holoenzyme complex. Furthermore, the mutational study of the Walker A motif, which is required for nucleotide binding and hydrolysis, showed that this motif plays indispensable roles in the function of Tih2p. When a temperature-sensitive tih2 mutant, tih2-160, was incubated at the nonpermissive temperature, cells were rapidly arrested in the G(1) phase. Northern blot analysis revealed that Tih2p is required for transcription of G(1) cyclin and of several ribosomal protein genes. The similarities between the mutant phenotypes of tih2-160 and those of taf145 mutants suggest a role for TIH2 in the regulation of RNA polymerase II-directed transcription.

Bacterial Proteins↗
PubMed2000

Sfb2p, a yeast protein related to Sec24p, can function as a constituent of COPII coats required for vesicle budding from the endoplasmic reticulum.

The COPII coat is required for vesicle budding from the endoplasmic reticulum (ER), and consists of two heterodimeric subcomplexes, Sec23p/Sec24p, Sec13p/Sec31p, and a small GTPase, Sar1p. We characterized a yeast mutant, anu1 (abnormal nuclear morphology) exhibiting proliferated ER as well as abnormal nuclear morphology at the restrictive temperature. Based on the finding that ANU1 is identical to SEC24, we confirmed a temperature-sensitive protein transport from the ER to the Golgi in anu1-1/sec24-20 cells. Overexpression of SFB2, a SEC24 homologue with 56% identity, partially suppressed not only the mutant phenotype of sec24-20 cells but also rescued the SEC24-disrupted cells. Moreover, the yeast two-hybrid assay revealed that Sfb2p, similarly to Sec24p, interacted with Sec23p. In SEC24-disrupted cells rescued by overexpression of SFB2, some cargo proteins were still retained in the ER, while most of the protein transport was restored. Together, these findings strongly suggest that Sfb2p functions as the component of COPII coats in place of Sec24p, and raise the possibility that each member of the SEC24 family of proteins participates directly and/or indirectly in cargo-recognition events with its own cargo specificity at forming ER-derived vesicles.

COP-Coated Vesicles↗
PubMed2000

Impaired proteasome function rescues thermosensitivity of yeast cells lacking the coatomer subunit epsilon-COP.

Formation of COPI-coated transport vesicles requires a cytosolic protein complex consisting of seven subunits: alpha-, beta-, beta'-, gamma-, delta-, epsilon- and zeta-COP, collectively designated coatomer. The yeast Saccharomyces cerevisiae gene encoding the epsilon-COP subunit is known as SEC28/ANU2. anu2 null mutant cells (anu2Delta) are temperature-sensitive, and alpha-COP is rapidly degraded in these cells when they are shifted to the restrictive temperature. We isolated extragenic suppressors that rescue the temperature-sensitive growth defect of anu2Delta cells. Genetic analysis revealed that one of the suppressors is allelic to PRE8 (PRS4), which encodes a 20 S proteasome subunit. In the presence of a proteasome inhibitor, MG132, anu2Delta cells did not cease growth even at the restrictive temperature. Furthermore, MG132 inhibited the rapid decrease of alpha-COP levels in anu2Delta cells shifted to the restrictive temperature. However, secretion of certain proteins by these cells was impaired even in the presence of MG132. In conclusion, impairment of proteasome-dependent proteolysis rescued some, but not all, temperature-sensitive defects of anu2Delta cells. These results are discussed in terms of evidence that epsilon-COP plays a critical role in maintaining the structural integrity of alpha-COP.

Adenosine Triphosphatases↗
PubMed2000

Anterolateral thigh flap donor-site complications and morbidity.

The authors examined donor-site complications and morbidity in 37 patients after reconstruction with free or pedicled anterolateral thigh flaps. Intraoperative assessment included damage to the vastus lateralis muscle and whether the main pedicle of the rectus femoris muscle had been killed. Postoperative assessment of the donor site included wound healing, range of motion, muscle strength, gait, and sensation. Patients were surveyed with a questionnaire about fatigue in their activities of daily life and the appearance of the donor site. All 32 patients who underwent primary skin closure could perform activities of daily life normally, and most (87.5 percent) reported that donor-site appearance was satisfactory. However, the severity of donor-site dysfunction was related to the degree of damage to the vastus lateralis muscle, and most patients (87.5 percent) had some loss of sensation at the anterolateral aspect of the thigh. Because of adhesions between the meshed skin graft and the underlying fascia, range of motion at the hip and knee was limited in significantly more patients who had received split-thickness skin grafts (60 percent) than patients who had undergone primary skin closure (3.1 percent). Therefore, wider flaps or flaps harvested nearer the knee may increase donor-site morbidity. The authors concluded that the incidence of long-term morbidity with the anterolateral thigh flap is low, although it is increased when the flap includes the vastus lateralis muscle or is wider and requires additional skin grafting at the donor site.

Adult↗
PubMed2000

Postoperative complications and functional results after total glossectomy with microvascular reconstruction.

Microsurgical reconstruction after total glossectomy can greatly improve quality of life; however, postoperative functional results are often unstable, and the effectiveness of total glossectomy remains questionable. To determine the problems of reconstruction after total glossectomy with laryngeal preservation and to examine the functional results of swallowing and speech, 30 patients who had undergone total glossectomy and reconstruction with free flaps were reviewed for this study. The patients ranged in age from 20 to 73 years, and 23 of the 30 had undergone reconstruction with a rectus abdominis musculocutaneous flap. Wider and thicker flaps were designed and transferred and were sutured to suspend the larynx. To maintain physiologic swallowing function after surgery, the extent of laryngeal suspension and cricopharyngeal myotomy was limited. Of the 30 patients, 21 (70 percent) could be decannulated with laryngeal preservation; 20 of these 21 could tolerate a normal/soft/pureed diet, and 1 was limited to a fluid diet. Speech was intelligible in 16 of the 19 patients evaluated. In 9 of the 30 patients, laryngeal function could not be preserved. In four of these nine patients, additional resection combined with total glossectomy caused severe aspiration and recurrent pneumonia. Two patients with preoperative cerebral dysfunction were also poor candidates for laryngeal preservation. Additionally, the transferred flap's lack of bulk in the oral cavity and the advanced age (73 years) of one patient and the poor motivation of another may have contributed to postoperative aspiration. Aspiration occurred in one patient because of local recurrence of a tumor. The presence of preoperative cerebral dysfunction (p = 0.025), resection of the epiglottis (p = 0.005), and postoperative orocutaneous fistulas (p = 0.04) were significantly associated with the failure of laryngeal preservation. However, because of the difficulty of enrolling a sufficient number of patients in the study and the inherent limitations of retrospective studies, multivariate analysis in this study showed that no factors, such as patient age, flap volume, and the type of neck dissection, were significant predictors of laryngeal preservation. Although prospective studies are necessary, the function of individual patients must be assessed so that the study experiences discussed here can be applied to subsequent patients.

Adult↗
PubMed2000

Elongation factor 2 in the liver and skeletal muscle of mice is decreased by starvation.

We examined whether starvation affected the amount of EF-2 protein as well as the level of its mRNA in the liver and skeletal muscle of mice, to understand the molecular mechanism for nutritional adaptation of protein-turnover. Although the amount of EF-2 was diminished by starvation in each of the tissues examined, the amount of EF-2 mRNA did not decrease in parallel with the protein.

Animals↗
PubMed1999

Free adipofascial flap for scalp reconstruction: case report.

The authors describe a case in which a large defect of the scalp was present after tumor excision. It was covered with a free adipofascial flap and a split-thickness skin graft, with satisfactory results. Numerous similar cases of scalp defects reconstructed with other free flaps have been described. But since donor-site morbidity is minimized with free adipofascial flaps, they should be used more often for reconstruction of scalp defects.

Adipose Tissue↗