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Biomedical subjects

K Konishi

Publications and source records attributed to K Konishi.

At least 91 records · Page 5Linked to original sources
PubMed1998

The truncated form of the Epstein-Barr virus LMP-1 is dispensable or complimentable by the full-length form in virus infection and replication.

The Epstein-Barr virus (EBV) latent membrane protein-1 (LMP-1) gene of the Akata virus strain was cloned, and its nucleotide sequence was determined. Compared with the B95-8 strain, the translation initiation codon for the truncated LMP-1 gene, which is expressed in the lytic cycle, was lost. Immunoblotting showed that Akata EBV produces no truncated LMP-1 protein in any state and that the full-length LMP-1 protein is expressed at a significant level during lytic infection. The results suggest that the truncated LMP-1 protein is dispensable for EBV infection and replication or that the full-length form can "functionally" complement the truncated form if the truncated form has a function.

Base Sequence↗
PubMed1998

Skeletal muscle myosin monomer in equilibrium with filaments forms a folded conformation.

Rabbit skeletal myosin forms stable filaments under physiological conditions, and only a small amount stays as a monomer in equilibrium with filaments. The myosin monomers were observed in two conformational states, as extended and folded forms upon electron microscopy and gel filtration high performance liquid chromatography. The fraction of monomers in the folded conformation increased with a decrease in the concentration of NaCl below 0.2 M, and the conformational state was affected neither by the presence of ATP nor by the phosphorylation of regulatory light chain. In most of the folded monomers, the tail bent back toward the heads at one region, 45 nm apart from the head-tail junction, and the remaining tail portion containing the C-terminal tip appeared to interact with the head-tail junction. Only a small percentage of the folded monomers was in a more compact conformation close to the 10 S conformation of vertebrate smooth muscle and non-muscle myosins. The folded monomers, however, may not trap the products of ATP hydrolysis as assessed by single turnover experiments. The percentage of monomers in the 10 S-like conformation was increased by the exchange of a regulatory light chain with the smooth muscle light chain, indicating the participation of head-tail junction, including the regulatory light chain in the formation of folded conformation. The folded conformation may be common to various myosin IIs, suggestive of common roles for the folded monomers.

Animals↗
PubMed1998

Primary small cell carcinoma of the esophagus: flow cytometric analysis and immunohistochemical staining for the p53 protein and proliferating cell nuclear antigen.

BACKGROUND AND OBJECTIVES: The purpose of this study was to determine the clinical course and effects of histopathologic characteristics of specific tumors including DNA contents and immunohistochemical aspects in patients with small cell carcinoma of the esophagus. METHODS: Medical records of 4 patients who presented with small cell carcinoma of the esophagus were retrospectively reviewed. RESULTS: DNA aneuploidy was observed in 2 cases. Staining for the p53 product was positive in all cases. The average proliferating cell nuclear antigen (PCNA) labeling rate (LR) was 77.6% (64.0-90.8%). The estimated median survival was 42 days for all patients. Distant metastases were observed in 2 of the 4 patients. CONCLUSIONS: Higher PCNA LR of small cell carcinoma may be an unfavorable characteristic of biological behavior. Patients with disseminated disease should have symptomatically palliative operation combined with chemotherapy.

Aged↗
PubMed1998

Gene structure, cDNA cloning, and expression of the rat cytokine-induced neutrophil chemoattractant-2 (CINC-2) gene.

Cytokine-induced neutrophil chemoattractant-2 (CINC-2) belongs to the CXC chemokine family and consists of two isoforms, CINC-2 alpha and CINC-2 beta. We have studied the genomic organization and expression of the CINC-2 gene. The gene spans approximately 14 kb and is composed of three common exons, one CINC-2 alpha-specific exon and two CINC-2 beta specific exons. This finding suggests that two isoforms of CINC-2 are encoded by mRNAs produced by alternative splicing. Each isoform is encoded in four exons, and exon-intron boundaries are placed identically within the aligned sequences of CXC chemokines. The CINC-2 alpha-specific exon encodes an extra C-terminal serine residue, in addition to three amino acid residues (DKS) which were determined from amino acid sequence analysis of CINC-2 alpha previously. The 5' flanking region of the gene contains a TATA box and putative binding sites for NF-kappa B and AP-1. Northern blot analyses showed that the mRNA level for CINC-2 was very low in rat peritoneal macrophages without stimulation and increased up to 4 h after lipopolysaccharide stimulation, similar to that for CINC-1 or CINC-3. Thereafter, the mRNA expression decreased gradually. However, the mRNA level of CINC-2 remained high 24 h after stimulation, in contrast to that of CINC-1 or CINC-3. These data indicate the expression of CINC-2 is regulated differently among the CINCs.

Animals↗
PubMed1998

Surgical treatment of Cronkhite-Canada syndrome associated with protein-losing enteropathy: report of a case.

PURPOSE: The case of a patient with Cronkhite-Canada syndrome, who developed a protein-losing enteropathy, is reported. METHODS: After localization of the protein-losing region, a right colectomy was performed. RESULTS: Hypoproteinemia and ectodermal changes improved postoperatively. CONCLUSIONS: Surgery is an effective treatment for protein-losing enteropathy in Cronkhite-Canada syndrome. Ectodermal changes improve after correcting malnutrition.

Female↗
PubMed1998

Diffuse bilateral thalamic astrocytomas as examined serially by MRI.

We report the case of a 13-year-old girl with diffuse bilateral thalamic astrocytomas. Incoordination was observed at the onset. Cranial computed tomography (CT) showed enlarged thalami, and magnetic resonance imaging (MRI) revealed these lesions to be symmetrically enlarged with high intensity on the T2-weighted image. Owing to these atypical findings in the neuroimaging studies, we had difficulty in making the correct diagnosis of a brain tumor. After the diagnosis of diffuse bilateral thalamic astrocytomas was obtained, we performed hyperfractionated radiotherapy followed by chemotherapy. Radiation therapy was effective for a while, but the girl's condition deteriorated again and she died 8 months after admission. Although diffuse bilateral thalamic astrocytomas are difficult to diagnose because they do not resemble most other neoplasms on neuroimaging studies, pediatricians should keep this entity in mind in order to arrive at a precise and prompt diagnosis.

Adolescent↗
PubMed1998

Cytological evidence of spontaneous androgenesis in the freshwater clam Corbicula leana Prime.

Cytological observations and DNA microfluorometry of the hermaphrodite freshwater triploid clam Corbicula leana revealed unusual androgenetic development as follows: (1) the maternal genome of zygotes was extruded as two polar bodies just after karyokinesis of the first meiosis, (2) only chromosomes derived from one male pronucleus constituted the metaphase of the first cleavage of zygotes, (3) DNA content of 7-day-old veliger larvae was identical to the somatic cells of the parent. This spontaneous androgenetic process in C. leana zygotes is the first case in the phylum Mollusca and may be related to the specialized mode of reproduction; i.e. hermaphroditism and self-fertilization.

Animals↗
PubMed1998

Rectal mucosal hemodynamics, evaluated by reflectance spectrophotometry, in patients with chronic hepatitis.

To evaluate rectal mucosal hemodynamics in patients with chronic hepatitis, we employed reflectance spectrophotometry and examined the results in relation to the presence and severity of chronic hepatitis. Twenty-six patients with histologically diagnosed chronic hepatitis and 21 controls were examined for rectal vascular findings by endoscopy. Indices (I) of rectal mucosal oxygen saturation (ISO2) and rectal mucosal hemoglobin (IHb) concentration were measured. To minimize the effects of systemic anemia, the IHb was divided by blood Hb concentration, giving the rectal index for Hb (RHb). The relationship between rectal mucosal hemodynamics and the histological grade of chronic hepatitis was studied. Rectal vascular lesions were observed in three patients with chronic hepatitis (11.5%). The RHb in patients with chronic hepatitis was significantly higher than that in the controls (5.74 +/- 0.71 and 4.82 +/- 1.12, respectively; P < 0.01). There was no significant difference in ISO2 levels (44.23 +/- 5.84 and 41.94 +/- 4.91, respectively). No significant correlation was observed between rectal mucosal hemodynamics and the histological severity of chronic hepatitis, although rectal mucosal hemodynamics changed in patients with chronic hepatitis. Early vascular changes were observed in the rectal mucosa of patients with chronic hepatitis.

Adult↗
PubMed1998

cDNA cloning and predicted primary structure of scallop sarcoplasmic reticulum Ca(2+)-ATPase.

Sarcoplasmic reticulum (SR) Ca(2+)-ATPase of the scallop cross-striated adductor muscle was purified with deoxycholate and digested with lysyl endopeptidase for sequencing of the digested fragments. Overlapping cDNA clones of the ATPase were isolated by screening the cDNA library with an RT-PCR product as a hybridization probe, which encodes the partial amino acid sequence of the ATPase. The predicted amino acid sequence of the ATPase contained all the partial sequences determined with the proteolytic fragments and consisted of the 993 residues with approximately 70% overall sequence similarity to those of the SR ATPases from rabbit fast-twitch and slow-twitch muscles. An outline of the structure of the scallop ATPase molecule is predicted to mainly consist of ten transmembrane and five 'stalk' domains with two large cytoplasmic regions as observed with the rabbit ATPase molecules. The sequence relationship between scallop and other sarco/endoplasmic reticulum-type Ca(2+)-ATPases is discussed.

Amino Acid Sequence↗
PubMed1998

Role of amino acids in cochlear degeneration: deprivation of cystine induces death of cochlear hair cells of guinea pigs in vitro.

Redox regulation reportedly plays a role in maintaining cochlear homeostasis. However, little is known about the roles of oxidation-reduction systems in the cochlea. We examined the role of the cystine/cysteine oxidation-reduction system in survival of cochlea hair cells in vitro. The survival of hair cells was evaluated in cochlea specimens following incubation with the medium supplemented with various concentrations of cystine. Dying hair cells were detected by the trypan blue extrusion method. The rates of cell death for both outer and inner hair cells increased significantly with a decrease in the concentration of cystine. In addition, the rate of cell death of IHCs tended to be higher than that of OHCs. These findings suggest that the cystine/cysteine system might be required for maintenance of homeostasis in cochlear hair cells, especially in IHCs.

Animals↗
PubMed1998

Role of amino acids in cochlear degeneration: morphological changes in cochlear outer hair cells following glutamate application.

Glutamate is an excitatory neurotransmitter in the cochlea and has toxic effects on the organ of Corti in various pathological conditions. The toxic effects of glutamate have not been determined in detail. In this study, we examined morphological changes in the organ of Corti of guinea pigs following local application of glutamate. Morphological changes were noted in outer hair cells. Degeneration of outer hair cells was found 24 h after glutamate treatment. The extent of degeneration depended on exposure time. Inner hair cells did not exhibit any degeneration. In addition, no degenerative changes were detected in nerve endings attached to hair cells. These findings suggest that outer hair cells are the initial site of degeneration caused by application of excess glutamate to the inner ear.

Animals↗
PubMed1998

Hereditary nonpolyposis colorectal cancer associated with duodenal carcinoma: a case report.

Hereditary nonpolyposis colorectal cancer is an autosomal, dominantly inherited disease, characterized by an early age of onset, right colon predominance and an association with various extracolorectal malignancies. We present a case of a 47-year-old woman who met the clinical criteria for the diagnosis of hereditary nonpolyposis colorectal cancer from her past and family histories. She had undergone operations for uterine cancer (histology not confirmed) at age 35 and for advanced cancer of the ascending colon at age 45. Gastroendoscopy revealed a flat elevated lesion, 20 mm in size, with a protrusion (type IIa + Is) in the second portion of the duodenum in March 1996. Additionally, colonoscopy showed a flat elevated lesion, 30 mm in size, with an irregular and nodular surface (type IIa, laterally spreading tumor) in the descending colon. After the operation, the resected specimen of the duodenum histologically showed a well-differentiated adenocarcinoma associated with a tubulo-villous adenoma which had invaded the submucosal layer. The tumor of the colon was histologically confirmed to be a moderately-differentiated adenocarcinoma with submucosal invasion. A high frequency of replication error positivity (4/5 loci) was detected in both of the tumors. Reports of early cancer of the duodenum, associated with extracolorectal malignancies in hereditary nonpolyposis colorectal cancer, are very rare in the literature. Although it is difficult to determine which extracolorectal tumor sites should be taken into consideration by screening programs, we believe that careful observation by upper gastrointestinal endoscopy, which includes the duodenum, is necessary for patients with hereditary nonpolyposis colorectal cancer.

Colonoscopy↗
PubMed1998

Solution structure of CINC/Gro investigated by heteronuclear NMR.

Cytokine-induced neutrophil chemoattractant (CINC/Gro) is a chemotactic factor for neutrophils in the rat and a member of the CXC chemokine family. The refined three-dimensional structure of CINC/Gro was derived with the aid of heteronuclear magnetic resonance spectroscopy and a hybrid method of distance geometry and simulated annealing. The backbone atomic r.m.s. differences for 19 structures about the mean coordinates for residues 7 to 70 are 0.69+/-0.15 A for the dimer and 0.56+/-0.13 A for the monomer. The N terminal region containing an ELR sequence, an essential motif for chemotactic activity, is disordered in solution, as in other CXC chemokines. The dimer structure consists of a six-stranded anti-parallel beta sheet with two C-terminal alpha helices on the beta sheet. The overall dimer structure of CINC/Gro is similar to that of human MGSA, though the backbone r.m.s.d.s between CINC/Gro and the two MGSA structures were high (1.81 and 2.34 A for the monomer) in spite of the high sequence homology (67%). The major difference resides in the relative position of the C-terminal alpha helix with respect to the beta sheet. This results in a difference of interhelical distances in the dimer: wider (15 A) in CINC/Gro, as in IL-8, than in MGSA (11.7 and 10 A).

Animals↗
PubMed1998

Conformation, filament assembly, and activity of single-headed smooth muscle myosin.

Single-headed myosin was prepared by digestion of porcine aorta smooth muscle myosin with Staphylococcus aureus V8 protease in the presence of actin. The single-headed myosin preparation contained intact light chains, a rod fragment of a heavy chain, and a heavy chain of which only a minor fraction contained a nick in the head segment. Below 0.2 M NaCl, the single-headed myosin showed a decrease in Ca2+-ATPase activity and an increase in the elution time on gel filtration HPLC in a phosphorylation-dependent manner, indicating a phosphorylation-dependent conformational transition between the extended and folded forms. These conformations were confirmed by electron microscopic observation of rotary-shadowed samples of single-headed myosin. However, the conformational transition of single-headed myosin occurred in a narrower range with lower salt concentrations than that of double-headed myosin. The filament assembly of single-headed myosin was thus facilitated and phosphorylation-independent. The single-headed myosin also showed high actin-activated ATPase activity independent of phosphorylation. These results indicate that the two-headed structure of smooth muscle myosin is not essential for the conformational transition, but is required for the phosphorylation-dependent regulation of enzymatic activity and filament assembly.

Actin Cytoskeleton↗
PubMed1998

Effect of FK480, a CCK-A receptor antagonist, on spontaneously developed chronic pancreatitis in WBN/Kob rats.

The effect of FK480, a cholecystokinin-A (CCK-A) selective receptor antagonist, on spontaneously developed chronic pancreatitis was examined in WBN/Kob rats. Animals at age 18 weeks (18w-Control) already had the histologic appearance of chronic pancreatitis as indicated by inflammatory cell infiltration and fibrotic degeneration with interstitial edema. Rats treated with vehicle from 18 to 26 weeks of age (26w-Control) showed further development of pancreatitis as characterized by more extensive appearance of inflammatory cell infiltration and fibrotic changes, with the pancreatic weight significantly decreased. Serum amylase levels of 26w-Control animals were slightly decreased compared with those of 18w-Control animals, although the difference was not statistically significant. When rats were treated orally with 1, 10, and 100 microg/kg FK480 from 18 to 26 weeks of age, the decrease in serum amylase levels recovered dose dependently compared with 26w-Control, and the level in animals treated with 100 microg/kg FK480 was almost the same as that in 18w-Control rats. Histologic examinations revealed that the appearance of the pancreas of animals treated with FK480 was slightly improved with respect to inflammatory cell infiltration and edematous changes at the highest dose examined, although the difference was not statistically significant. Although blockade of the CCK-A receptor could be considered to exacerbate chronic pancreatitis due to possible inhibition of the trophic action of CCK, our results suggest that CCK-A receptor antagonists may not be detrimental to chronic pancreatitis.

Amylases↗
PubMed1998

Developmental changes in enzyme activities and in structural features of rat masticatory muscle mitochondria.

The functional ability of a muscle is closely related to the activities of the mitochondria, which are energy-producing organelles in muscle cells. The development of the mammalian masticatory muscle progresses dramatically when feeding behavior changes from suckling to mastication, but it is unclear how the energy-producing systems of the mitochondria change. In this paper, the development of rat masticatory muscle mitochondria was investigated in terms of enzyme activities of the mitochondrial respiratory chain and the structural and numerical development of mitochondria, especially regarding the change in feeding behavior from suckling to mastication. Using isolated mitochondria from the masticatory muscle, we measured succinate dehydrogenase, NADH dehydrogenase, succinate-O2 oxidoreductase, and NADH-O2 oxidoreductase. These were found to be increased in the 15-day postnatal rat compared with the 0- to 10-day postnatal rat. The structural development of mitochondria was gradual in the 0- to 15-day postnatal rat. However, a notable increase was found in the cross-sectional area of mitochondria between 10 and 15 days postnatally. The number of mitochondria per muscle fiber was apparently constant during the same period. We demonstrated that the change in feeding behavior was well-correlated with an increase in mitochondrial enzyme activity, also supported by the early structural development of mitochondria.

Aging↗
PubMed1998

Plasma beta-carotene, retinol, and alpha-tocopherol levels in relation to glycemic control of children with insulin-dependent diabetes mellitus.

Plasma beta-carotene, alpha-tocopherol and retinol were measured in 15 female and 5 male children with insulin-dependent diabetes mellitus (IDDM), and the correlations with plasma hemoglobin A1c (HbA1c) and fructosamine were analyzed. Twelve female and 8 male children served as age-matched controls. The plasma beta-carotene and alpha-tocopherol levels of the IDDM children were significantly higher than those of the control children, but there were no differences in plasma retinol or total lipid levels. The plasma beta-carotene level, beta-carotene/retinol ratio and beta-carotene/total lipids ratio each showed significant correlations with serum HbA1c and fructosamine in all subjects studied. Similarly, the plasma alpha-tocopherol level and alpha-tocopherol/total lipids ratio were correlated with these indexes of glycemic control. These findings suggest certain mechanisms may exist to prevent lipid peroxidation and vascular complications in IDDM patients.

Adolescent↗