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Biomedical subjects

K Ohno

Publications and source records attributed to K Ohno.

At least 325 records · Page 18Linked to original sources
PubMed1996

A tyrosine kinase-like molecule is localized in the nuclear membrane of neurons: hippocampal behavior under stress.

Protein tyrosine kinases play important roles in the development of the mammalian nervous system during embryogenesis and in the maintenance of function of the adult brain. Using a semi-nested PCR technique based on a short amino acid motif of protein tyrosine kinases, we isolated a human genomic DNA encoding a peptide whose sequence was related to known mammalian protein tyrosine kinases. The expression was examined by Northern blot analysis, and transcripts were detected almost exclusively in the brain. The corresponding cDNA was sequenced, and it was revealed that the gene designated as byk coded for a receptor-like molecule with a motif of protein tyrosine kinase. Immunohistochemical analysis demonstrated that the Byk protein was expressed in neurons and was located in the nuclear envelope. To understand the physiological significance of the Byk protein, we investigated the behavior of this molecule in the hippocampus after ischemia. Byk-like immunoreactivity disappeared from the neurons in the fields CA1 through CA3 and the dentate gyrus of the hippocampus following 20 min of ischemia. After recirculation of blood flow, neurons in the CA3 field and the dentate gyrus re-expressed Byk-like antigen but CA1 neurons did not. Interestingly, Byk-like immunoreactivity was detected in microglial cells and astrocytes in the CA1 field that were activated after ischemia. Byk could be a new tool to study the neuron-glia and glia-glia interactions.

Amino Acid Sequence↗
PubMed1996

Masticatory function of postoperative tumor patients rehabilitated with osseointegrated implants.

PURPOSE: This study determined the level of masticatory function that can be achieved with osseointegrated implants in postoperative tumor patients. PATIENTS AND METHODS: Masticatory function was evaluated in 15 postoperative tumor patients with implants, 22 nontumor patients with implants, and 15 natural dentate controls. The area of occlusal contact was evaluated with a pressure-sensitive, color-developing bite sheet analyzed by computer. Chewing performance was evaluated by a low-adhesive, color-developing, chewing-gum system. RESULTS: Subjects in the tumor group had load-bearing tooth contacts similar to those of the natural dentate controls and nontumor implant patients. Continuity of the mandible was essential to sustain occlusal load. The presence of the hypoglossal nerve was the main factor in determining restoration of chewing performance. CONCLUSIONS: Surgical efforts to preserve the mobility of the residual tongue and prosthetic approaches to restore impaired mobility to as great an extent as possible are especially important for better functional rehabilitation of patients who have defects of the hypoglossal nerve.

Adult↗
PubMed1996

Histologic and microradiologic comparison of block and particulate cancellous bone and marrow grafts in reconstructed mandibles being considered for dental implant placement.

PURPOSE: Patterns of healing were investigated in mandibles reconstructed with three different techniques to assess their readiness for implant placement. PATIENTS AND METHODS: The subjects were 10 patients who had undergone mandibular reconstruction with either nonvascularized iliac block bone grafts (group 1; 3 patients), particulate cancellous bone and marrow (PCBM) grafts (group 2; 3 patients) for mandibular discontinuity, or PCBM grafts for mandibular marginal defects (group 3; 4 patients). Six (groups 2 and 3) or 12 months (group 1) after mandibular reconstruction, bone biopsy specimens were obtained for histologic examination with a trephine bur. As controls, bone specimens were obtained from ungrafted mandibles of patients undergoing dental implant placement. Undecalcified specimens were embedded in polyester resin and examined by routine light microscopy and microradiography. RESULTS: The morphology of the specimens from group 1 was similar to that of group 2, but not to that of the control subjects. However, the morphology of specimens from group 3 was generally similar to that of control subjects. CONCLUSION: These results suggest that mandibular reconstruction with PCBM grafts allows the placement of dental implants sooner than reconstruction with block bone grafts.

Adult↗
PubMed1996

Congenital myasthenic syndrome caused by decreased agonist binding affinity due to a mutation in the acetylcholine receptor epsilon subunit.

We describe the genetic and kinetic defects for a low-affinity fast channel disease of the acetylcholine receptor (AChR) that causes a myasthenic syndrome. In two unrelated patients with very small miniature end plate (EP) potentials, but with normal EP AChR density and normal EP ultrastructure, patch-clamp studies demonstrated infrequent AChR channel events, diminished channel reopenings during ACh occupancy, and resistance to desensitization by ACh. Each patient had two heteroallelic AChR epsilon subunit gene mutations: a common epsilon P121L mutation, a signal peptide mutation (epsilon G-8R) (patient 1), and a glycosylation consensus site mutation (epsilon S143L) (patient 2). AChR expression in HEK fibroblasts was normal with epsilon P121L but was markedly reduced with the other mutations. Therefore, epsilon P121L defines the clinical phenotype. Studies of the engineered epsilon P121L AChR revealed a markedly decreased rate of channel opening, little change in affinity of the resting state for ACh, but reduced affinity of the open channel and desensitized states.

Acetylcholine↗
PubMed1996

An anatomical study on the forearm vascular system.

The purpose of the present study was to establish the clinicoanatomical basis for the radial forearm flap. We conducted a morphometric investigation on 52 Japanese cadavers, of forearm vessels, for use in free forearm flaps. The mean inner diameter of the cephalic and median cubital veins at the interepicondylar line was 1.9 +/- 1.2 mm and 1.8 +/- 1.1 mm, respectively. Mean inner diameter of the radial artery and venae comitantes 1 cm distal to the origins of the radial and ulnar arteries was 2.3 +/- 0.5 mm and 1.6 +/- 0.5 mm, respectively. The longest segment of a superficial vein was 28.7 +/- 4.6 cm, it was measured between the basilic vein 5 cm proximal to the interepicondylar line and the cephalic vein at Lister's tubercle. The length of the radial artery was 18.1 +/- 1.7 cm. There were fewer valves in the basilic vein and cephalic vein proximal to the median cubital vein and in the brachial veins than in the distal antebrachial veins. From these results some of the clinicoanatomical considerations of forearm vessels which will form the clinicoanatomical basis of the free forearm flap should be clarified.

Adult↗
PubMed1996

Analysis of the articulation after glossectomy.

Rehabilitation of the oral cancer patient should aim to achieve not only morphological restoration but also post-operative functions. However, there are few reports describing quantitative evaluation of the latter. The authors have attempted quantitative evaluation of post-operative articulatory function after glossectomy, and report the evaluation of it by speech intelligibility, electropalatography (EPG), and acoustical analysis. Subjects were five directly sutured patients and five patients reconstructed with forearm flap, all after glossectomy. The target syllable was /ta/ from among speech intelligibility test samples. The speech intelligibility and acoustical analysis were investigated pre-operation, and 1,6 and 12 months post-operation. EPG data were collected by DP-01(RION) at 6 months post-operation. Acoustical analyses were carried out by consonant frequency characteristics and formant variance from consonant to vowel transitions. As a result, subjects reconstructed with a forearm flap showed higher restorative tendency than directly sutured subjects. Articulatory characteristics expected from acoustical analysis were more in agreement with the results of EPG than with the results of the speech intelligibility test. From the results, it was suggested that the acoustical analysis used for this research could reveal changes in articulatory movement and will be useful for quantitatively evaluating post-operative articulatory functions.

Adult↗
PubMed1996

Multi-drug delivery system using streptavidin-transforming growth factor-alpha chimeric protein.

Tissue-specific delivery of a variety of molecules has been a valuable technique for biological and medical research. Therefore, we have constructed a recombinant plasmid containing the coding regions for streptavidin core and mature human transforming growth factor-alpha (TGF-alpha). The recombinant plasmid has been expressed in Escherichia coli to produce a chimeric protein with both streptavidin and TGF-alpha activity. The streptavidin-TGF-alpha chimeric protein (ST-TGF-alpha) could efficiently transfer biotinylated beta-galactosidase into A431 cells via the epidermal growth factor receptor. More than 99% of the cells contained the enzyme transferred. Furthermore, ST-TGF-alpha complexed with biotinylated-glucose oxidase had a significant cytotoxic effect when incubated with A431 cells. These findings suggest that the ST-TGF-alpha chimeric protein could be used to deliver proteins of interest into target cells without the need for chemical linkage or genetic construction. Essentially, ST-TGF-alpha serves as a high-modular "molecular bridge" for the passage of a wide variety of effector molecules into target cells.

Amino Acid Sequence↗
PubMed1996

New mutations in acetylcholine receptor subunit genes reveal heterogeneity in the slow-channel congenital myasthenic syndrome.

Mutations in genes encoding the epsilon, delta, beta and alpha subunits of the end plate acetylcholine (ACh) receptor (AChR) are described and functionally characterized in three slow-channel congenital myasthenic syndrome patients. All three had prolonged end plate currents and AChR channel opening episodes and an end plate myopathy with loss of AChR from degenerating junctional folds. Genetic analysis revealed heterozygous mutations: epsilon L269F and delta Q267E in Patient 1, beta V266M in Patient 2, and alpha N217K in Patient 3 that were not detected in 100 normal controls. Patients 1 and 2 have no similarly affected relatives; in Patient 3, the mutation cosegregates with the disease in three generations. epsilon L269F, delta Q267E and beta V266M occur in the second and alpha N217K in the first transmembrane domain of AChR subunits; all have been postulated to contribute to the lining of the upper half of the channel lumen and all but delta Q267E are positioned toward the channel lumen, and introduce an enlarged side chain. Expression studies in HEK cells indicate that all of the mutations express normal amounts of AChR. epsilon L269F, beta V266M, and alpha N217K slow the rate of channel closure in the presence of ACh and increase apparent affinity for ACh; epsilon L269F and alpha N217K enhance desensitization, and epsilon L269F and beta V266M cause pathologic channel openings in the absence of ACh, rendering the channel leaky, delta Q267E has none of these effects and is therefore a rare polymorphism or a benign mutation. The end plate myopathy stems from cationic overloading of the postsynaptic region. The safety margin of neuromuscular transmission is compromised by AChR loss from the junctional folds and by a depolarization block owing to temporal summation of prolonged end plate potentials at physiologic rates of stimulation.

Adolescent↗
PubMed1996

The evaluation of masticatory function with low adhesive colour-developing chewing gum.

Many objective methods have been described to evaluate masticatory function. Recently, a new chewing gum system has been reported that utilizes a phloxine-sodium bicarbonate reaction and measures a chromatic coordinate as a functional indicator. A low-adhesive colour-developing chewing gum has been developed by selecting an appropriate gum base. This study examined the applicability of the system and reproducibility of results in subjects with different dental states. Tests were performed on 15 natural dentate subjects and 15 complete denture wearers after determination of germane test conditions through a pilot study. The colour was measured by a*, one of the coordinates in the L*a*b* colour system. All subjects could perform the test. The coefficient of variation ranged from 1.87% to 7.90%, averaging 5.15% in the natural dentate subjects and from 1.5% to 17.9%, averaging 9.75% in the complete denture wearers. The 95% confidence interval of a* was 28.76 +/- 1.76 in the natural dentate subjects and 10.05 +/- 2.58 in the complete denture wearers. The results indicated that this material can be useful for both complete denture wearers and subjects with a natural dentition with adequate reproducibility.

Adhesives↗
PubMed1996

A computerized method for evaluating balance of occlusal load.

In order to undertake a quantitative evaluation of balance occlusal load, the use of the Dental Prescale System was investigated. The method uses a test sheet that undergoes a colour-developing chemical reaction, for detecting contact area, and a computerized analysis system, for evaluating the balance of occlusal load. Twenty natural dentate subjects and 10 hemimaxillectomy patients participated in the study. Each subject bit a test sheet as hard as possible for 3 s. The balance of occlusal load was expressed as a percentage of the load on the side with the lesser occlusive load (%OLR). The %OLR ranged from 39.7% to 49.4% in the natural dentate subjects, and from 0% to 31.3% in the hemimaxillectomy patients at their resection site. The patients' low %OLRs were attributed to loss of sustaining structure and subjective occlusal adjustment by clinicians. Combining technical simplicity, relatively high reproducibility, and diverse analysis capability, this system is useful for quantitative evaluation of balance of occlusal load in clinical situations.

Adult↗
PubMed1996

Effects of restressing on the mechanical properties of stress-shielded patellar tendons in rabbits.

We studied the effects of restressing on the mechanical properties and morphology of stress-shielded rabbit patellar tendons. After completely unloading the patellar tendon for 1 to 3 weeks, tension was again applied to the tendon for subsequent 3 to 12 weeks. Although the stress shielding markedly decreased the tangent modulus and tensile strength of the tendon, restressing significantly increased them. However, the mechanical properties of the tendon were not completely recovered even after a prolonged period of restressing. The microstructure of the tendon was also restored by restressing, although the recovery was incomplete. These results indicate that the mechanical properties and morphology of tendinous tissue change in response to mechanical demands.

Animals↗
PubMed1996

Apoptosis involved in density-dependent regulation of rat fibroblastic 3Y1 cell culture.

When rat 3Y1 fibroblastic cells are cultured toward confluency, the cells go through maximum cell density (overshoot) before reaching post-confluence stationary cell density. After overshooting, a number of floating cells are found in the medium. In a long-term culture, a cyclic change in cell number, an increase after each medium refreshment and subsequent cell loss within a few days has been observed so that the cell populations in the monolayer maintain post-confluence stationary cell density at a constant level. The floating cells excluded trypan blue, but they had no ability to attach to the substrate and to form colonies after being reseeded in fresh medium. They had condensed and uniformly electron-dense chromatin with sharply circumscribed edges. Their DNA contained a laddering pattern in harmony with internucleosomal cleavage. The features were those of apoptosis. When floating cells appeared, apoptotic bodies were also observed in the monolayer. Most of them were found within the cytoplasm of intact cells, suggesting that apoptotic bodies were also faded away from the culture by being rapidly engulfed by neighboring intact cells. These suggest that apoptosis and subsequent detachment from the monolayer or engulfment by neighboring intact cells, in addition to inhibition of cell division, are basic mechanisms on the process of density-dependent regulation in monolayer culture of rat 3Y1 cells.

Animals↗
PubMed1996

Genetic profiles of three inbred strains derived from wild rats (Rattus norvegicus) trapped in Japan.

In order to establish the genetic profiles of three inbred strains of rats (MITB/Yag, MITC/Yag and MITE/Yag; commonly designated as Mitake strains), which were derived from wild specimens of the Rattus norvegicus trapped in Mitake-cho, Gifu, Japan, 63 microsatellite markers were typed in these strains as well as nine other laboratory inbred strains. The data indicate that the MITB and MITC strains are very closely related (3% polymorphism between these strains), whereas the third strain MITE/Yag is relatively different from the other two strains (36% with the MITB, 39% with the MITC). Eighty-three to 58% of polymorphic loci had different alleles between the Mitake strains and the other strains, but 65-35% between the latter strains. In addition, 14 new alleles were found in the Mitake strains. These results suggest that the Mitake strains are useful for linkage analysis.

Animals↗
PubMed1996

Mapping of the dilute-opisthotonus (dop) gene on chromosome 8 of the rat.

The rat dilute-opisthotonus (dop) autosomal recessive gene, causing ataxia and coat color dilution, was mapped on chromosome 8 by PCR-amplified microsatellite markers. To facilitate the linkage analysis, an intersubspecific cross with a Japanese wild rat strain was used. The recombination frequencies were 12.8% between Apoc3 and dop, and 32.1% between dop and Mylc1v. The following order of three genes is proposed; Apoc3-dop-Mylc1v. This mutation appears to be homologous to dilute-lethal (d1) of the mouse in terms of clinical symptoms, coat color effect and chromosomal location of the gene loci. Key words: ataxic mutant rat, dilute-opisthotonus (dop), gene mapping.

Animals↗
PubMed1996

Quantitation of cytochrome P450 enzymes (CYP1A1/2, 2B11, 2C21 and 3A12) in dog liver microsomes by enzyme-linked immunosorbent assay.

1. An enzyme-linked immunosorbent assay (ELISA) using specific antisera has been developed to quantify individual cytochrome P450 (P450) enzymes (1A1/2, 2B11, 2C21 and 3A12) in dog liver microsomes. 2. The specific contents of CYP1A1/2, 2B11, 2C21 and 3A12 in untreated male dog liver microsomes determined by the ELISA were 17, 48, 160 and 69 pmol/mg protein respectively, corresponding to 4, 10, 34 and 15% of total optically determined P450 respectively. These P450 enzymes in untreated female dog liver microsomes showed almost similar amounts and relative proportions to those observed in male dog liver microsomes. 3. The oral treatment of male dogs with phenobarbital (PB), rifampicin (Rif) or beta-naphthoflavone (beta-NF) induced significant increases in the contents of CYP1A1/2 (12-fold by beta-NF), 2B11 (16-fold by PB), 2C21 (2-fold by PB) and 3A12 (5-fold by PB and Rif), resulting in marked proportional alterations of the P450 enzymes in dog liver microsomes. 4. This ELISA method will be a useful tool for investigating possible influences (induct on/suppression) of xenobiotics on the expression of P450 enzymes in dog liver.

Animals↗
PubMed1996

Mitochondrial DNA mutations associated with the 11778 mutation in Leber's disease.

To clarify the characteristics of possible synergestic mitochondrial DNA (mtDNA) mutations associated with Leber's hereditary optic neuropathy (LHON), we analyzed the entire nucleotide sequences of mitochondrial genome of two Japanese patients from independent pedigrees harboring the 11778 mtDNA mutation, and compared their sequences with those of 47 disease and 6 normal controls. We have detected several unique mutations in the mtDNA in addition to the 11778 mutation. Two nucleotide substitutions, an A-to-G transition at position 856 in the 12S rRNA gene and an A-to-G transition at 14692 in the T psi C loop of the tRNA(Glu) gene, occurred at highly conserved sites among various species. These mutations in combination with the 11778 mutation might synergetically contribute to the pathogenesis of LHON.

Adolescent↗