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Biomedical subjects

T Hamada

Publications and source records attributed to T Hamada.

At least 271 records · Page 15Linked to original sources
PubMed1996

Central phenotype and related varieties of spinocerebellar ataxia 2 (SCA2): a clinical and genetic study with a pedigree in the Japanese.

The gene for SCA2 has been mapped to chromosome 12q23-q24.1, but the mutant gene remained to be identified. When studying a Japanese family with SCA2, we noted that clinical features and disability varied among patients, with the central feature being progressive ataxia-slow eye movement-hyporeflexia syndrome. Additional symptoms were parkinsonism with minor cerebellar deficits, and severe ataxia with choreoathetosis. Our experience plus related literature documentation indicates that choreoathetosis is not so rare at the advanced stage of the disease, with onset at an early age, and that the variety of SCA2 phenotype depends on age at onset and duration of the disorder.

Adult↗
PubMed1996

The influence of immersion solutions on the viscoelasticity of temporary soft lining materials.

OBJECTIVES: The purpose of this study was to examine the influence of laboratory immersion in a number of solvents on the viscoelasticity of temporary soft lining materials. It was an initial attempt to reproduce the changes seen clinically with a view to formulating more clinically relevant immersion regimes for the evaluation of these materials. METHODS: Changes in the viscoelasticity of four temporary soft lining materials following immersion at 37 + or - 1 degree C in 10% acetone/90% water, 20A% acetone/80% water and hexane was compared to a control immersion in distilled water using a penetrometer modified to record creep strain and strain during recovery. Testing was performed at 2 h and 24 h and then at 2, 4, 7, 21 and 28 d after sample preparation. Summary measures were used to describe individual specimen changes in derived values of initial and time dependent compliance and elastic recovery from 0-7, 7-28 and 0-28 d. RESULTS: Immersion in hexane resulted in at least a 50% reduction in compliance of 28 d. There was a significantly greater reduction in compliance for hexane immersion than for any other solvent (p<0.01). Immersion in 20% acetone resulted in an increase in compliance of around 1 mm/N after 1 wk compared with a reduction of up to 1 mm/N in distilled water. There was a reduction in elastic recovery for 3 out of 4 materials with 20% acetone/80% water solution. Changes in elastic recovery were smaller than those of compliance. SIGNIFICANCE: The reduction in compliance with hexane immersion suggests that this, or similar solvents, may form the basis of more clinically relevant immersion regimes. This may contribute to the development of improved temporary soft lining materials.

Acetone↗
PubMed1996

Lattice corneal dystrophy type II associated with familial amyloid polyneuropathy type IV.

BACKGROUND: Finnish-type familial amyloidosis (FAP-IV) is an autosomal, dominantly inherited disorder characterized by progressive polyneuropathy and lattice corneal dystrophy type II. The vast majority of families with this disorder originated from Finland. Only two families, in neighboring districts, have been reported in Japan previously. METHODS: The authors report two additional Japanese patients with FAF-IV. The proband, a 70-year-old man, had decreased perspiration and abnormal facial muscle movement. Results of neurologic examination showed bilateral facial and hypoglossal nerve palsies, and an autonomic disturbance, including orthostatic hypotension and dysfunction of perspiration. Histochemical, immunohistological, and DNA studies confirmed the diagnosis of FAP-IV. RESULTS: Results of ophthalmologic examination showed asymptomatic lattice corneal dystrophy of both eyes, but the appearance of the cornea was different from that described in the patients from Finland. Lattice lines in the authors' patient were very fine, short, and glassy and could be observed with indirect retroillumination, but might be missed with direct illumination by the slit-lamp microscope. The proband's younger half-sister, a 68-year-old woman, showed clinical findings and laboratory data similar to those of the proband. CONCLUSION: The authors report two Japanese patients with lattice corneal dystrophy type II related to FAP-IV. This is the third Japanese family with this disorder, and there is no familial relationship to the two previously reported families in Japan.

Aged↗
PubMed1996

Lymphocytic aleukemic leukemia cutis.

A 21-year-old male patient had localized papules on the chest and arms. Biopsy of a lesion showed it to be a malignant lymphoid neoplasm, and immunohistochemical studies confirmed a lymphoblastoma origin. Aberrant lymphoid cells were noted in the cutaneous blood vessels, but simultaneous examination of the peripheral blood showed no evidence of leukemia. One month elapsed before observable leukemic cells were found in the blood and sternal marrow, confirming the diagnosis of acute lymphocytic leukemia. Examination of a cutaneous biopsy specimen led to early diagnosis of the disease.

Adult↗
PubMed1996

cDNA cloning of a wounding-inducible gene encoding a plastid omega-3 fatty acid desaturase from tobacco.

A cDNA encoding the plastid omega-3 fatty acid desaturase was isolated from a tobacco (Nicotiana tabacum cv. SR1) leaf cDNA library. The amino terminal extension of the deduced amino acid sequence of this clone had a characteristic feature of the transit peptides of plastid-destined proteins. Northern analysis indicated that the mRNA corresponding to this cDNA was present in leaves, but was not detected in roots. Responses to wounding of the plastid and microsome omega-3 desaturase genes were investigated in tobacco leaves. The mRNA level of the plastid omega-3 desaturase gene increased to about 2-fold that of unwounded controls at 12 h after a wounding treatment. On the other hand, the mRNA level of the microsome omega-3 desaturase gene remained constant in the wounded leaves. Linolenic acid contents of major leaf polar lipids increased by wounding. These results indicate that wounding enhances the accumulation of the plastid omega-3 desaturase mRNA, and increases the conversion of linoleic acid to linolenic acid in leaf polar lipids.

Amino Acid Sequence↗
PubMed1996

Comfortable zone of the mandible evaluated by the constant stimuli method.

For evaluation of the comfortable zone (CZ) and the most comfortable position (MCP) of the occlusal vertical relation of the mandible, the constant stimuli method with three subjective categories of judgements was applied in 10 edentulous subjects. The evaluated CZ was stable and about 3 mm in width. The occlusal vertical dimension (OVD) of the existing dentures was found to be located within the CZ in nine of the 10 subjects.

Aged↗
PubMed1996

Alteration in the bite force and EMG activity with changes in the vertical dimension of edentulous subjects.

The bite force and EMG activity of jaw closing muscles were studied at seven different vertical jaw positions around the occlusal vertical dimension (OVD) in 10 edentulous subjects. When the masseteric EMG activity was maintained at constant values (40% and 20% of the maximum activity at the OVD), the bite force increased in proportion to increase of the vertical dimension. On the other hand, when the bite force was maintained at constant values (4 kg and 8 kg), the EMG activities of the jaw closing muscles decreased, with an increase of the vertical dimension. These results indicate that the OVD is not the position at which the most efficient exertion of the bite force is obtained.

Adaptation, Physiological↗
PubMed1996

Analysis of composition and structure of hard autopolymerizing reline resins.

The authors investigated the composition and structure of six hard auto-polymerizing reline resins. The chemical compositions, glass transition temperatures, molecular weights and particle size distributions of the powders, and the chemical compositions of the liquids were examined. The powder compositions were classified into three groups. The first group contained poly(methyl methacrylate). The second contained poly(ethyl methacrylate) and poly(methyl methacrylate/ethyl methacrylate) and the third contained poly(ethyl methacrylate). The average molecular weights of these powders was about 2 x 10(5). The indexes of molecular weight dispersion suggested that all powders contained polymers that had a narrow molecular weight distribution. The particle size distribution of these powders was classified into two groups. The first group was mainly in the range of 50-100 microns and the second mainly between 20 and 50 microns. The composition of the liquids was classified into three groups. The first group contained a monofunctional methacrylate monomer. The second contained a monofunctional methacrylate monomer and a plasticizer and the third contained monofunctional methacrylate monomers and cross-linking agents. The results of this experiment showed the differences in composition among the products. This will be useful for examining the relationship between the composition and mechanical properties of hard autopolymerizing reline resins.

Acrylic Resins↗
PubMed1996

The effects of cross-linking agents on the water sorption and solubility characteristics of denture base resin.

Six different cross-linking agents were added to the monomer component of an autopolymerizing denture base resin, and their effects on the water sorption and solubility were investigated. The results of this study suggested that the chemical nature of the polymer versus that of the water molecule directly affected the water sorption of denture base resin. The addition of a cross-linking agent decreased the solubility with increasing concentration.

Acrylic Resins↗
PubMed1996

Serum carnitine and disabling fatigue in multiple sclerosis.

The serum concentrations of total, free and acylcarnitine were compared in 25 patients with multiple sclerosis (MS) and among age- and sex-matched normal controls by the new enzymatic cycling method in order to clarify whether the fatigue in MS might be due to possible carnitine-related fatty acid metabolic abnormalities in the mitochondria of skeletal muscles. Patients with MS were divided into those with and those without excessive fatigue. Levels of total and free carnitine were not significantly different between MS patients and normal controls. Levels of acylcarnitine, whose decrease in chronic fatigue syndrome has been reported, were also similar between MS patients and normal controls. There was no difference in these carnitine levels between MS patients with and without excessive fatigue. We argue that acylcarnitine deficiency and fatty acid metabolic dysfunction in mitochondria are not relevant to the excessive fatigue in patients with MS, and further explanatory investigations are to be sought.

Adult↗
PubMed1996

Endometrial stromal sarcoma of the uterus with rhabdoid features.

A case of endometrial stromal sarcoma of the uterus with rhabdoid features, occurring in a 57 year old woman is reported. Electron microscopy and immunohistochemistry revealed that the rhabdoid cells contained intermediate filaments which were positive for vimentin, cytokeratin, alpha-smooth muscle actin, and muscle specific actin, but not for myoglobin and desmin. This indicated that the tumor in this case differed somewhat from the three rhabdoid tumors and an endometrial stromal sarcoma with rhabdoid differentiation previously reported and that, therefore, these tumors were heterogeneous.

Biomarkers, Tumor↗
PubMed1996

Clinical features and natural history of spinocerebellar ataxia type 1.

SCA1 is a dominant spinocerebellar ataxia (SCA) and a multi-systemic syndrome caused by abnormal expansion of unstable CAG repeat in a novel gene located on chromosome 6p22-p23. We clinically studied 35 Japanese SCA1 patients who were assumed to have come from a common origin. The age at onset ranged from 15-63 years, and significantly correlated with CAG repeat units of mutant alleles. Ataxia was the initial symptom, and the majority of patients had a similar history of signs and symptoms. Nystagmus was at first minimal, later attenuated, and a slow saccade followed. Limb tendon reflexes were mostly hyperactive and depressed with the development of diffuse amyotrophy. The cardinal feature was ataxia-hyperreflexia-late slow saccade syndrome with terminal amyotrophy. Although the phenotype of SCA1 overlaps with those of other dominant SCAs, some facets of the neurological events differ from either SCA2 with ataxia-hyporeflexia-slow saccade syndrome, or early-onset Machado-Joseph disease with dystonia-bradykinesia-spasticity syndrome.

Adolescent↗
PubMed1996

Basic imaging properties of a new screen-film system for chest radiography.

To evaluate the potential clinical usefulness of a new screen-film system (advanced screen-film system; AD system) for chest radiography, its fundamental imaging properties compared with a conventional screen-film system (HR-4/HR-S) were investigated. The basic imaging properties were evaluated by measuring characteristic (H&D) curves, relative speeds, MTFs (modulation transfer functions), WS (Wiener spectra), and x-ray attenuations of screens. The detail visibilities and pathological details of various diseases in chest radiographs of patients were evaluated subjectively. The film gradient of the AD system was slightly lower at low radiographic density, and higher at high density, as compared with a conventional screen-film system. The screen speed of the AD system was 212% greater than that of the conventional system, and the film speed was 53% that of the conventional film. As the result, the total speed of the AD system was slightly higher compared with the conventional system. The spatial resolution of the AD system was comparable to or slightly lower than that of the conventional system. The noise level of the AD system was considerably lower than that of the conventional system at low (D = 0.5) and middle (D = 1.0) radiographic density levels. However, it was high at high radiographic density (D = 1.8). The radiographic densities in the underpenetrated areas with the AD system were greater than those of the conventional system when the lung densities are matched comparable. Improvement in noise level with the AD system at low and middle density levels may be useful for detection of various diseases in chest radiographs.

Equipment Design↗
PubMed1996

Pheromone-induced stimulation of hypothalamic gonadotropin-releasing hormone pulse generator in ovariectomized, estrogen-primed goats.

As an example of pheromone-induced activation of reproductive function, the 'male effect' is well known in seasonally anestrous goats. The effect of this male pheromone on the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator activity was examined by monitoring the characteristic increases in the multiple-unit activity (MUA volleys) of the medial basal hypothalamus which had been associated with the pulsatile secretion of luteinizing hormone in ovariectomized goats carrying estradiol implants under 16L/8D condition. Male goat hair was used as the source of male pheromones, and the exposure to the hair was accurately timed to be midway between succeeding MUA volleys. The interval from the pheromone exposure to the subsequent volley was measured, so that the primer pheromone effect was assessed in terms of the stimulation of the GnRH pulse generator activity. Exposure to hair from an intact male goat resulted in occurrence of a MUA volley within a few minutes (1.7 +/- 0.2 min, n = 15) with the intervolley interval being apparently shortened as compared with the preexposure period. Hair from castrated male goats, on the other hand, had no such stimulatory effect at all on the hypothalamic GnRH pulse generator activity, but treatment of the castrated goats with testosterone for 2 months resumed the pheromone activity. The present results provide first direct evidence for the central action of the primer pheromone in a mammalian species, and pheromonal stimulation of the reproductive neuroendocrine system is shown to be exerted by instantaneously stimulating the hypothalamic GnRH pulse generator activity.

Animals↗