Search PubMed⌕ Search

Biomedical subjects

K Kohno

Publications and source records attributed to K Kohno.

At least 433 records · Page 24Linked to original sources
PubMed1987

Electron microscopic study of mucoepidermoid carcinoma in the pancreas.

An autopsy case of extremely rare mucoepidermoid carcinoma of the pancreas in a 58-year-old male was reported. The main tumor in the pancreatic tail associated with wide-spreading metastases, was histologically composed of squamous cancer cell nests intermingled with mucin-containing cells, but not true glandular structures except for metastatic foci in the liver. Electron microscopic findings of the main tumor revealed roughly three kinds of cancer cells, namely undifferentiated cells, squamous cells, and squamous cells with mucin-containing intracytoplasmic lumina, accompanied by variety of transitional forms. The mucin was similar to that of the intra-or interlobular duct epithelium of pancreas in mucin stains. Immunohistochemically, positive immune reaction of the cancer cells was observed by anti-keratin, -epithelial membrane antigen and -carcinoembryonic antigen sera. These findings suggested that the cancer cells originated from undifferentiated cells of pancreatic duct, which showed multipotency to differentiate predominantly into squamous cells, but also into mucin-producing cells.

Carcinoma↗
PubMed1987

[Liver abscess secondary to ventriculoperitoneal shunt].

Liver abscess is a rare complication following the ventriculoperitoneal (V-P) shunt operation. There has been only one case reported in the literature. We present a case of liver abscess developed about 3 months after V-P shunt operation. A 31-year-old female was admitted to our hospital in comatose condition due to second bleeding from an aneurysm of the right internal carotid artery on January 1, 1984. Obliteration of the aneurysm was performed on the following day. She received V-P shunt operation for the marked hydrocephalus on February 4, but she developed low spinal fluid pressure syndrome. She was able to walk by herself after the replacement of shunt valve on March 4. In the middle of April, she suffered from abdominal pain with a pyrexia for about 5 days. On May 13, a new peritoneal tube was placed in another part of the peritoneal cavity because of the recurrence of hydrocephalus. On the following day, she developed severe abdominal and back pains with a high fever. Abdominal CT scans and ultrasonogram were performed on May 22, showing a well-defined, cystic mass lesion in the liver and the peritoneal tube lying just beneath the mass lesion. Approximately 100 ml of white creamy pus was aspirated from the cystic mass by ultrasound-guided percutaneous puncture, and a 8.3 French pigtail nephrostomy catheter was left in place for 9 days until purulent drainage stopped. Microbiologic examination demonstrated staphylococcus epidermidis in the cerebrospinal fluid (CSF) from the shunt tube but was negative in the abscess fluid. The ventricular fluid was drained externally with the V-P shunt tube for a while, but the new ventricular drainage was instituted because of continuous positive cultures in the CSF from the shunt tube. Thereafter, the cultures of the CSF became negative and ventriculoatrial (V-A) shunt operation was performed on July 2. Postoperative course was uneventful. It is considered that the formation of the liver abscess seems to be caused by the focal injury to the liver surface by the insidiously infected peritoneal tube with St. epidermidis, and by the decrease in systemic resistance to infection. Percutaneous aspiration and drainage under the guidance of abdominal computed tomography or ultrasonography are very useful and efficient for the diagnosis and the treatment of liver abscess. When patients show signs of infection to the V-P shunt, we should remove the shunting system and place a new external ventricular drainage, and institute a V-A shunt after confirming negative cultures of the CSF.

Adult↗
PubMed1986

Large myelinated club endings on the Mauthner cell in the goldfish. A study with thin sectioning and freeze-fracturing.

Thin sectioning and freeze-fracturing have revealed the distribution of gap junctions and chemical synapses in the synaptic interface of the large myelinated club endings on the lateral dendrite of the goldfish Mauthner cell. In 12 samples of club endings fractured completely or nearly completely, the apposed synaptic membrane area averaged 39.090 microns2, of which 16.6% was occupied by gap junctions and about 4 to 5% by the active zones of chemical synapses. The numerical profile density (number per unit area of the synaptic membrane) of gap junctions varied greatly, from 1.78 to 6.30, and was mostly in inverse proportion to their size. The chemical synapses were located mainly in two places: in the circumferential rim of the synaptic membrane next to the widened extracellular space, and in the margins of intraterminal invaginations of the synaptic cleft. The axoplasm of the preterminal axon, just after losing its myelin sheath, was filled with microtubules, among which neurofilaments gathered into many small bundles. The correlation between the areas of gap junctions and the chemical synapses and the amplitude of the excitatory postsynaptic potentials (EPSP) is discussed.

Animals↗
PubMed1986

Promoter region of the human pro-alpha 1(II)-collagen gene.

We have isolated a genomic clone containing the 5'-terminal portion of the human pro-alpha 1(II)-collagen gene. This clone, HC2C, contains 10 kb of the gene and 6 kb of 5'-flanking sequences. It was selected by cross hybridization using a [32P]DNA probe containing the promoter region of the rat alpha 1(II)-collagen gene. We have determined the nucleotide sequence of the first exon and of 400 bp upstream. There is considerable homology between this human sequence and the corresponding rat sequence. As in the rat, the first exon contains a 155-bp untranslated segment and a 85-bp sequence coding for the signal peptide and a part of the N-propeptide of type-II procollagen. The segment preceding the transcription initiation site contains a conserved 'ATATAA' element, and several similar G + C-rich stretches. As in the rat gene, no 'CAT' element is evident between -70 and -120. We also find the sequence 5'-GTGGTCAGA-3' reported as an enhancer element in both viral and cellular genes, located around -290 bp. A high degree of homology exists between the atypical rat and human promoter structures; however, such homology is absent among the alpha 1(I), alpha 2(I) and alpha 1(III) promoters, which suggests that the unique alpha 1(II) sequences may be related to the specific expression of the alpha 1(II)-collagen gene.

Amino Acid Sequence↗
PubMed1986

Amino acid sequence of mammalian elongation factor 2 deduced from the cDNA sequence: homology with GTP-binding proteins.

Complementary DNA clones, pHEW1 and pRE2, coding for hamster and rat polypeptide chain elongation factor 2 (EF-2), respectively, were isolated and sequenced. It was shown that the cDNA insert in pHEW1 contains a 2574-base-pair open reading frame coding for an 857-amino acid polypeptide with Mr 95,192, excluding the initiation methionine. Comparative studies of sequence homology among EF-2 and several GTP-binding proteins show that five regions in the amino-terminal position of EF-2, corresponding to about 160 amino acids, show homology with GTP-binding proteins, including protein synthesis elongation and initiation factors, mammalian ras proteins, and transducin. The carboxyl-terminal half of EF-2 contains several regions that have 34-75% homology with bacterial elongation factor G. These results suggest that the amino-terminal region of EF-2 participates in the GTP-binding and GTPase activity whereas the carboxyl-terminal region interacts with ribosomes. Finally, the sequence provides direct evidence that diphthamide (2-[3-carboxy-amido-3-(trimethylammonio)propyl]histidine), the site of ADP-ribosylation by diphtheria toxin, is produced by post-translational modification of a histidine residue in the primary translational product.

Amino Acid Sequence↗
PubMed1985

Structure of the promoter of the rat type II procollagen gene.

We have isolated several overlapping genomic clones which contain the 5' terminal portion of the rat pro-alpha 1 (II) chain gene. These clones span about 20 kilobases (kb) of contiguous DNA containing 15 kb of the gene and 5 kb of the 5' flanking sequence. Electron microscopic analysis of mRNA-DNA hybrids by R-looping shows that collectively these clones contain 16 exons which code for approximately one-third of the pro-alpha 1 (II) chain. The sizes of the exons are small, except for the first exon which is relatively large. The nucleotide sequence of the first exon and the 1000 base pairs (bp) preceding it was determined. The first exon contains a 150-bp untranslated segment and an 85-bp sequence coding for the signal peptide and a part of the NH2-terminal propeptide of type II collagen. The segment preceding the transcription initiation site contains the "TATA" box and several G + C-rich stretches, whereas the "CAT" box is not evident between -70 and -120. The hexanucleotide sequence 5'-GGGCGG-3' is found in three different places between -200 and the TATA box. The inverted complement sequence of this hexanucleotide, 5'-CCGCCC-3', is located around both -220 and -450. The hexanucleotide and its inverted sequence have been found previously in the promoter region of the tk gene of herpes virus. These sequences are known to function in a mutually dependent manner as transcription signals for the tk gene; thus, they may play a role in determining the level of transcription of this cartilage gene. The hexanucleotide, 5'-CCGCCC-3', is also found in the 21-base pair repeats of the SV40 promoter and the promoter region of hydroxymethylglutaryl-CoA reductase gene. The sequence 5'-GTGGTTAGA-3' located around -280 is identical to the "core" sequence that has been reported as enhancer element in both viral and cellular genes. These unusual structures may be related to the tissue-specific expression of this gene.

Animals↗
PubMed1985

The incidence and developmental process of delayed traumatic intracerebral haematomas.

Although delayed traumatic intracerebral haematomas (DTICH) have been frequently reported especially after the advent of computerized tomography (CT), the developmental processes of traumatic intracerebral haematomas and the incidence of DTICH have not been described precisely. Based on early sequential CT examinations of 84 intracerebral haematomas for which initial CT scans were performed as early as within 6 hours of injury, we could ascertain four types of the developmental processes: Type I (39%) included the haematomas which were already evident in the initial CT scans, Type II (11%) the haematomas which were small or medium initially and increased their sizes afterwards, Type III (24%) the haematomas of which admission CT scans could not demonstrate any changes at the sites of development of the haematomas, and Type IV (26%) the haematomas of which initial CT scans showed a salt and pepper or flecked high-density appearance. Types III and IV denoted the DTICH and accounted for 50% of all the haematomas. Therefore, DTICH are thought to be not as uncommon as previously reported. Aetiologies and changes in the concepts of the DTICH are discussed, and it is stressed that, in the cases with eventual extra- and intra-cerebral combined haematomas, any surgical treatment of an extracerebral haematoma plays an important role in the development of DTICH.

Adolescent↗
PubMed1985

Characterization of diphtheria-toxin-resistant mutants lacking receptor function or containing nonribosylatable elongation factor 2.

Stable mutants resistant to diphtheria toxin (DT) were isolated from Chinese hamster ovary cells (CHO-K1) by single-step mutations with various mutagens. All the mutants were classified into two major groups as reported by other workers (4-6): toxin-entry mutants (DTrI) and translational mutants (DTRII) at the level of elongation factor 2 (EF-2). These mutants were further characterized by directly measuring the specific uptake of [125I]DT and the content of nonribosylatable EF-2 by two-dimensional gel analysis. DTrI mutants, which showed no cross-resistance to Pseudomonas exotoxin A (PA), had no ability to associate with [125I]DT and contained only ADP-ribosylatable EF-2, like wild-type cells. DTRIIb mutants maintained about 50% of the normal level of cellular protein synthesis in the presence of DT, and two-dimensional gel analysis directly showed that they contained equivalent amounts of ADP-ribosylatable and nonribosylatable EF-2 molecules. Fully toxin-resistant cells, named KEE1 (DTRIIa), were isolated from a DTRIIb mutant (KE1) by two-step mutation. KEE1 cells showed full resistance to DT and PA, the normal level of association with [125I]DT, and produced only nonribosylatable EF-2. Biochemical analysis of somatic cell hybrids indicated that the DT-resistant character of class II behaved codominantly. These results strongly supported the hypothesis that two copies of the gene for EF-2 are functional in CHO-K1 cells.

ADP Ribose Transferases↗
PubMed1985

The incidence of delayed traumatic intracerebral hematoma with extradural hemorrhages.

After introduction of computerized tomography (CT), we experienced 22 patients with traumatic extradural and intracerebral combined hematomas, of whom 15 underwent sequential CT scans. In 14 of the 22 patients or 13 of the 15 patients whose initial CT scans were performed early, within 6 hours after injury, intracerebral hematomas developed more slowly than extradural hematomas. In ten of the 13 patients, development of intracerebral hematomas was demonstrated only after removal of extradural hematomas, and in four patients acute brain swelling was observed during surgery. Therefore it is emphasized that the incidence of post-surgical intracerebral hematoma with extradural hemorrhages is high and that acute brain swelling during surgery for extradural hematomas is largely caused by the delayed intracerebral hematomas.

Adult↗