PubMed Health⌕ Search

Biomedical subjects

M Sameshima

Publications and source records attributed to M Sameshima.

At least 19 recordsLinked to original sources
PubMed1992

Correlation of axenic linkage groups with the position of the microtubule-organizing center in aggregating Dictyostelium.

Positioning of the microtubule-organizing center (MTOC) in Dictyostelium discoideum was found to be genetically regulated. We examined the wild-type strain NC-4 cells independently maintained in different laboratories, freshly recovered cells from spores stocked for over 20 years, the temperature-sensitive growth mutant HU49 isolated from NC-4, as well as strain V-12 which is the opposite mating-type to NC-4. During aggregation on nonnutrient agar plates, all these strains showed similar cell polarity, as defined by the alignment of the nucleus ahead of the MTOC. By contrast, in Ax2 and Ax3, axenic strains carrying axenic mutations on linkage groups II and III, the MTOC was usually positioned ahead of the nucleus. Cells containing axenic linkage group II but not III positioned the MTOC ahead of the nucleus. Conversely cell polarity of strains including axenic linkage group III but not II was similar to that of wild-type cells. Thus axenic linkage group II, probably axeC or other linked gene(s) not yet identified, is responsible for the location of the MTOC anterior to the nucleus during aggregation. The anterior positioning of the MTOCs was prevented by growth on bacteria in cells carrying both axenic linkage groups, but not in those carrying only axenic linkage group II.

Animals↗
PubMed1991

The polypeptide encoded by the cDNA for human cell surface antigen Fas can mediate apoptosis.

Mouse anti-Fas monoclonal antibody has a cytolytic activity on human cells that express the antigen. Complementary DNAs encoding the cell surface antigen Fas were isolated from a cDNA library of human T cell lymphoma KT-3 cells. The nucleotide sequence of the cDNAs revealed that the molecule coding for the Fas antigen determinant is a 319 amino acid polypeptide (Mr 36,000) with a single transmembrane domain. The extracellular domain is rich in cysteine residue, and shows a similarity to that of human tumor necrosis factor receptors, human nerve growth factor receptor, and human B cell antigen CD40. Murine WR19L cells or L929 cells transformed with the human Fas antigen cDNA were killed by the anti-Fas antibody in the process known as apoptosis.

Amino Acid Sequence↗
PubMed1990

[A case of Merkel cell carcinoma of the eyelid].

An 84-year-old man with Merkel cell carcinoma in the right upper-eyelid is reported. The patient presented with a rapidly growing, reddish-purple, solid tumor with a relatively well-defined margin in the skin of the lid. Increased neuron specific enolase content in the blood returned to normal several months after resection of the tumor and 70 Gy postoperative cobalt radiation. Histopathologic examination of the resected specimen revealed that the tumor was limited by intact epidermis and occupied by moderate-sized, round malignant cells with marked mitoses and scant cytoplasm. The neoplastic cells were positively stained by labeled antibodies for neuron specific enolase, keratin and epithelial membrane antigen. Electron microscopic examination showed abundant perinuclear microfilaments and dense core granules.

Aged↗
PubMed1989

Ocular manifestations in patients infected with human T-lymphotropic virus type I.

Ocular manifestations in patients infected with human T-lymphotropic retrovirus type I (HTLV-I) consisted of a wide range of neoplastic, infectious and noninfectious vascular or inflammatory lesions. These disorders were associated with two distinct HTLV-I-induced systemic diseases, ie, adult T-cell leukemia/lymphoma and HTLV-I-associated myelopathy. Five of the 10 cases of adult T-cell leukemia/lymphoma had inflammatory or opportunistic infectious ocular lesions, including cytomegalovirus retinitis or eyelid tumor as part of generalized lymphomas. Four of the 17 cases of HTLV-I-associated myelopathy showed noninfectious lesions such as isolated, transient cotton-wool spots and granulomatous iridocylitis. Twenty-four (26.9%) of 89 cases with various ocular diseases but no HTLV-I-induced systemic disease had antibodies to HTLV-I in the serum. The aqueous humor antibodies to HTLV-I in the seropositive carriers were negative, except one carrier case who showed isolated cotton-wool spots in one eye and massive vitreous opacities in the other eye.

Adult↗
PubMed1988

The position of the microtubule-organizing center relative to the nucleus is independent of the direction of cell migration in Dictyostelium discoideum.

Dictyostelium amoebae can migrate in several different modes. We tested for correlations of the direction of cell locomotion with the relative positions of the nucleus and microtubule-organizing center (MTOC). Five cases were analyzed on electron micrographs with a microcomputer. Each mode of movement showed characteristic locations of the MTOC relative to the nucleus; however, they differed in the various cases. In randomly migrating interphase amoebae, the number of cells with the MTOC located behind the nucleus was twice as great as those with the MTOC located ahead of the nucleus. During chemotactic migration toward folic acid, cells with the MTOC behind the nucleus were more numerous, with a concomitant reduction of anterior MTOCs. When amoebae aggregated on agar plates, a posterior location of the MTOC was most strikingly favored, whereas in cells aggregating under submerged conditions, the MTOC was indifferently anterior or posterior to the nucleus. (It may be significant that EDTA-resistant cell-cell adhesion was fully expressed in the former cells, but weaker in the latter.) Finally, in the case of chemotactically migrating cells from dissociated pseudoplasmodia, which adhere by means of other molecules, the MTOC was consistently ahead of the nucleus. Thus the MTOC shows no necessary preferential position anterior or posterior to the nucleus; its position, rather, correlates with the type of migration and perhaps with the nature of cell-cell adhesion.

Cell Movement↗
PubMed1988

Tc-99m hexamethylpropylene-amine oxine (HM-PAO) uptake in a bone metastasis.

Uptake of Tc-99m Hexamethylpropylene-amine Oxine (HM-PAO) was seen in bone metastases from carcinoma of the lung. The uptake was prominent when compared to Tc-99m MDP, I-123 IMP, and Ga-67 citrate. Brain imaging with Tc-99m HM-PAO and N-isopropyl-p-[I-123] iodoamphetamine (IMP) is now frequently performed. Uptake of these agents has been reported in brain tumors and melanomas. In this report, uptake of Tc-99m HM-PAO in a metastatic lesion in bone is discussed.

Aged↗
PubMed1988

Complications of hypermature cataract: spontaneous absorption of lens material and phacolytic glaucoma-associated retinal perivasculitis.

Uncommon complications of hypermature cataract in two aged patients are described. One patients, a 58-year-old woman, with unilateral hypermature cataract secondary to Fuchs' heterochromic cyclitis developed spontaneous absorption of the lens material, followed by its dislocation into the anterior chamber. The other patient, a 63-year-old woman, showed phacolytic glaucoma associated with extensive retinal perivasculitis which concurred with leakage of hypermature cataractous lens material and subsided with its complete absorption. Histopathology of the membraneous cataract revealed degenerative changes of the capsule and extinction of the epithelial cells and cortical fibers.

Absorption↗
PubMed1987

Temporal relationships of EMG changes preceding voluntary movement to premovement cortical potential shifts.

The silent period and a rhythmic slower wave in EMG appear preceding a rapid voluntary movement (Tanii 1984). The present study was performed to investigate temporal relationships of the EMG changes preceding movement to premovement cortical potential shifts, in order to clarify whether the EMG changes are related to preparation and initiation of voluntary movement. A strong push of a hard band with the right wrist was conducted rapidly following a slightly sustained contraction. The surface EMG was detected from the right triceps brachii muscle. The EEG was recorded from C3, Cz and C4. Slowing of the EMG occurred before the movement in addition to the slower wave. The EMG slower waves were accompanied by a negative deflection of raw EEG potentials. The averaged cortical potentials preceding movement fell into 3 negative potentials. The first potential started about 1.0 sec before the EMG burst. Many of the EMG slower waves occurred in the phase of the second potential occurring 330-510 msec before the EMG burst. Premovement silent period appeared in the phase of the third potential occurring 30-60 msec before the EMG burst. Amplitude of these potentials was larger in the contralateral hemisphere than in the ipsilateral one. This asymmetry became statistically significant in the phase of the second potential. The results suggest that the EMG slower waves and the premovement silent period are associated with preparation and initiation of voluntary movement.

Adult↗
PubMed1987

Electron microscopic studies of giant nucleus-like structure formed by lambda DNA introduced into the cytoplasm of Xenopus laevis fertilized eggs and embryos.

When bacteriophage lambda DNA was injected into the cytoplasm of the fertilized egg of Xenopus laevis, giant nucleus-like structures were assembled around the injected DNA. These nucleus-like structures survived during cleavage and were partitioned into blastomeres at the blastula stage. The nucleus-like structures formed in the uncleaved fertilized eggs and the blastula cells were both surrounded by a bilayer nuclear membrane with nuclear pore complexes. The ultrastructural features of the lambda DNA-induced nucleus-like structure were considerably different from those of the normal blastula nucleus: although the nuclear pore complexes appeared to be normal, the 'nucleoplasm' was much too homogeneous as compared with that of the normal nucleus.

Animals↗
PubMed1987

Specialization of the interphotoreceptor matrices around cone and rod photoreceptor cells in the monkey retina, as revealed by lectin cytochemistry.

The binding sites of two lectins, peanut agglutinin (PNA) and wheat germ agglutinin (WGA), in the interphotoreceptor matrix (IPM) and photoreceptor plasma membranes of the Japanese monkey (Macaca fuscata) retina were localized using a pre-embedding staining method with ferritin-conjugated (Fer) lectins as well as a postembedding staining method with fluorescence-labeled (FITC) lectins. FITC-PNA, but not WGA, stained cylindrical domains of the IPM around cone outer and inner segments, while the IPM around rods stained with FITC-WGA but not PNA. When the intact (not detached) retinal tissues were incubated with Fer-lectin, the lectin generally labeled neither the IPM nor photoreceptor plasma membranes, but labeled only those structures in detached portions occurring at the edges of occasional retinal tissue blocks. Thus, the neural retinas physically isolated from the retinal pigment epithelium (RPE) were utilized principally here. Ultrastructurally, the IPM in the intact retina consisted of granular and filamentous materials; the IPM in the isolated neutral retina also retained those components, although somewhat loosely organized, and the IPM around cones appeared to be preserved better than did the IPM around rods. Fer-PNA bound to the IPM associated with cones, but not rods; Fer-WGA bound to the rod- but not cone-associated IPM. The ferritin particles were found to lie close to the granular and filamentous materials. Those photoreceptor-associated IPMs extended to the apical surface of the RPE in detached portions or to the apical villi of the RPE which were frequently found in the isolated neural retinas. Also, Fer-PNA labeled the cone, but not rod, plasma membranes; Fer-WGA bound heavily to the plasma membranes of rod and cone outer segments, but sparsely to those of their inner segments. These results suggest that the IPM comprises chemically and physically differential domains specialized for cone and rod photoreceptor cells, and that these specialized IPM are structurally so stable that may be involved in isolating photoreceptor cells physicochemically from each other and in the interactions between the photoreceptors and the RPE, such as retinal adhesion.

Animals↗
PubMed1987

Leber's hereditary optic neuropathy: mitochondrial and biochemical studies on muscle biopsies.

Two patients with Leber's hereditary optic neuropathy underwent morphological and biochemical investigations of muscle biopsy samples from the biceps brachii. Although clinically there was no muscle weakness or atrophy, specific histochemical and electron microscopic examinations showed mild but distinct myopathic changes, including abnormal oxidative enzyme activities, aggregates of enlarged mitochondria in the subsarcolemmal regions, and disruptions of myofilaments. Biochemical analyses of mitochondria isolated from muscle samples did not show and deficiency in respiratory-chain enzyme complexes or defect in content of cytochromes. Leber's hereditary optic neuropathy is assumed to be a multisystem disorder involving skeletal muscle also.

Adolescent↗
PubMed1987

[Analysis of motor control and kinesthetic perception in patients with progressive muscular dystrophy].

The purpose of this study was to examine motor control and kinesthetic perception of upper extremity in patients with Duchenne progressive muscular dystrophy. Nine normal subjects and nine subjects with muscular dystrophy performed a pursuit tracking task with step wave target by means of isometric contraction, and simultaneously estimated magnitude of muscular tension during tracking behavior. The results were as follows: (1) the muscular electrical activity measured from the EMGs was directly proportional to the muscular tension for both the normal and the muscular dystrophy groups, (2) the speed of step response for the muscular dystrophy group was slower than that for the normal group, and (3) the exponent of power function for the muscular dystrophy group tended to be smaller than that for the normal group. These results were discussed in terms of the stage of disability in progressive muscular dystrophy.

Child↗