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Biomedical subjects

A Shimada

Publications and source records attributed to A Shimada.

At least 343 records · Page 19Linked to original sources
PubMed1970

Comparison of the peptide composition of two histocompatibility-2 alloantigens.

The peptide composition of purified Histocompatibility-2 (H-2) reactive glycoprotein fragments from two murine strains allelic at the H-2 locus (H-2(b) and H-2(d)) were compared by a cellulose thin-layer peptide mapping micro technique. Approximately 70 per cent of the theoretical maximum number of peptides produced by cyanogen bromide cleavage and trypsin digestion were visualized by this technique. Most (38) of the peptides for the glycoproteins from these strains allelic for the H-2 locus were identical; however, three peptides of the H-2(b) and four peptides of the H-2(d) alloantigen were unique. The results demonstrate the remarkable similarity in protein structure between these two allelic products, but also show a small but reproducible difference in their peptide composition. The findings are consistent with the hypothesis that protein primary structure may determine wholly or in part their alloantigenic activities.

Amino Acids↗
PubMedDate not supplied

Resolution of DL-amino acids on a native cellulose column and a plausible mechanism for their resolution.

We have studied the resolution of DL-amino acids on a native cellulose column. All the DL-amino acids related to protein and their 16 DNP-DL-amino acids were separated. The resolution capability depends mainly upon the bulkiness of the side group attached to the alpha-carbon, but also on structural and functional interaction of amino acid with cellulose. We propose a plausible resolution mechanism that is thought to be governed by a so-called key and lock relation between an amino acid and cellulose. Then, the affinity of each enantiomer for cellulose was calculated based on the resolution factor, which was known to be some 10(-2) -10(-3) eV.

Amino Acids↗
PubMedDate not supplied

Age-related deterioration of long-term potentiation in the CA3 and CA1 regions of hippocampal slices from the senescence-accelerated mouse.

Long-term potentiation (LTP) is one candidate for the mechanism underlying memory storage. In the present study, we carried out electrophysiological studies on hippocampal slices prepared from the senescence-accelerated mouse (SAM-P/8), a strain which shows accelerated senescence and failure of certain types of learning in behavioral tests. The findings were compared with those noted in the SAM-R/1 substrain without severe symptoms of senescence. No significant differences were found between SAM-R/1 and SAM-P/8 of the same ages in responses in the absence of tetanic stimulation, and in LTP after tetanic stimulation. However, there were marked decreases in the degree of potentiation with aging in both strains.

Journal Article↗
PubMedDate not supplied

The WDHA syndrome: clinical and laboratory data on 28 Japanese cases.

During the period between 1967 and 1983, there were 28 WDHA patients in Japan. Clinically, these patients were not very different from those reported in western countries, but we have been able to add a few observations as follows. First, the WDHA patients with pancreatic endocrine tumors and those with neuroblastic tumors were present in almost equal numbers. Second, fluctuating hypercalcemia was often observed in patients with this syndrome, but it was not observed in any watery diarrhea due to the other etiologies. Third, the WDHA patients who have multiple endocrine neoplasia (MEN) type 1 have multiple tumors in the pancreas, indicating that the patients with MEN should be managed in a different manner in regard to determining tumor location as well as applying surgical treatment. When various types of tumors were examined for VIP content, it was found that many tumors have the potential to produce VIP, and when VIP is produced in large amounts, plasma VIP levels become elevated, resulting in the WDHA syndrome.

Achlorhydria↗
PubMedDate not supplied

Age-related cochlear degeneration in senescence-accelerated mouse.

Age-related hair cell loss and strial atrophy were investigated in an accelerated senescence-prone strain, SAMP1 mice, and an accelerated senescence-resistant strain, SAMR1 mice. The loss of inner and outer hair cells in SAMP1 progressed more rapidly than that in SAMR1 with age. In both strains, areas of the loss of inner and outer hair cells were located mainly in the apex and base. Atrophy of the stria vascularis was observed in both strains, but in SAMP1 it appeared to increase earlier than in SAMR1. These results reveal that age-related hair cell loss and atrophy of the stria vascularis comparable to that in the human cochlea occur earlier and progress more rapidly in SAMP1 than in SAMR1. Hearing impairment in SAM may be due to a combination of sensory and strial presbycusis as well as to neural presbycusis, as reported previously. The morphological changes in the cochlea observed in SAMP1 and SAMR1 make these strains suitable for the study of the mechanisms of presbycusis.

Aging↗
PubMedDate not supplied

Glomerulocystic kidney in a domestic dog.

Glomerulocystic kidney was diagnosed in a 5-year-old female Shiba dog, which died from chronic renal failure with convulsions, vomiting and diarrhoea. Haematological examination revealed non-regenerating anaemia, azotaemia and high serum creatinine. Grossly, both kidneys were mildly atrophic with multiple small cysts in the cortex. Histopathological examination revealed marked dilatation of Bowman's space, often with glomerular atrophy or loss, and mild interstitial fibrosis. Bowman's basement membranes (BMs) were tortuous and thickened, with patchy calcification. Glomerulo-tubular junctions in the urinary pole side of the kidneys had a stenotic appearance associated with thickening of Bowman's BMs and calcification. Focal interstitial fibrosis around the glomerulo-tubular junction was also found. Continuity with the proximal tubule was evident in cystic glomeruli. Ultrastructurally, marked thickening of Bowman's BMs with many granular deposits in the urinary pole side was observed. The findings indicate that glomerular cystic changes may have developed as a consequence of glomerulo-tubular junctional stenosis due to thickened Bowman's BMs and focal periglomerular fibrosis in the urinary pole side of the kidneys.

Animals↗
PubMedDate not supplied

Bilateral oedema with angiopathy in the dorsointernal area of the cerebral hemispheres of a domestic cat.

This report describes a feline case of oedema and angiopathy associated with the sudden onset of pyrexia and opisthotonus, followed by death one day later. Histologically, oedema and vascular lesions were found bilaterally in the dorso-internal area of the cerebral hemispheres. The vascular lesions consisted of perivascular exudation of periodic acid-Schiff-positive eosinophilic material and hyaline degeneration of the vascular walls. Immunohistochemically, the perivascular material reacted with anti-fibrinogen antibody; weak labelling for laminin was occasionally seen in the basement membranes of affected capillaries, arterioles and venules, in contrast to the strong labelling seen in the normal brain. Ultrastructurally, serum protein was observed in the space between the basement membranes of capillary endothelial cells and astrocytes, and vascular basement membranes were occasionally thickened. This is, to our knowledge, the first report of feline vasogenic oedema with a bilateral distribution in the cerebrum.

Animals↗
PubMedDate not supplied

N-methyl-D-aspartate receptor binding in brains of rats at different ages.

Potential age differences in N-methyl-D-aspartate (NMDA) receptor binding were evaluated in rat brain using [3H]dizocilpine and [3H]D,L-(E)-2-amino-4-propyl-5-phosphono-3-pentanoic acid (CGP 39653) as the radioligands. Neither [3H]dizocilpine nor [3H]CGP 39653 binding in hippocampus revealed any age difference (7 vs. 23-25 months) in Bmax or Kd. High-affinity [3H]dizocilpine binding showed a developmental increase (8 vs. 2 months) in hippocampus but not in frontal cortex. No senescence-related change (25 vs. 8 months) was observed in either region. The lack of senescence-related differences in these biochemical markers does not preclude the possibility of functional changes in the NMDA receptor with aging.

2-Amino-5-phosphonovalerate↗
PubMedDate not supplied

Age-dependent cerebral atrophy and cognitive dysfunction in SAMP10 mice.

Findings obtained from a series of studies to characterize age-dependent changes in brain morphology and behavior of inbred SAMP10 mice are reviewed. Following apparently normal development, SAMP10 mice developed brain atrophy with advancing age. The neocortex was diffusely atrophic in aged SAMP10 mice, with the frontal cortex being most affected. The entorhinal cortex, amygdala, and nucleus accumbens were also atrophic. Other subcortical structures were mildly atrophic, but the hippocampus was not atrophic. Mild to moderate hypertrophic astrocytosis was seen in the atrophied regions. Alzheimer's type pathology was not seen. The cortical atrophy was due to both loss and shrinkage of neurons. Brain atrophy was not remarkable in normal aging control SAMR10 mice. In accordance with above morphological changes, SAMP10 mice developed cognitive impairments with advancing age that were demonstrated by poor performance in passive avoidance and conditional avoidance tasks. All of these features of SAMP10 mice were inherited. SAMP10, therefore, is a unique model of age-dependent, inherited cerebral atrophy with cognitive dysfunction.

Aging↗
PubMedDate not supplied

Neuropathological studies on strains of senescence-accelerated mice (SAM) with age-related deficits in learning and memory.

In a series of inbred Senescence-Accelerated mice (SAM) strains, accelerated-senescence prone SAMP substrains show early onset and rapid advancement of senescence. SAMP8 and SAMP10, in particular, exhibit a significant age-related deterioration in memory and learning for passive and active avoidance tasks with, respectively, a low and high incidence of systemic senile amyloidosis. In the brains of both SAMP8 and SAMP10 strains, we have found numerous morphological alterations. Here we review the changes seen in both neuronal or glial components in SAMP8/P10 brains. They may serve as markers of the neuronal degeneration leading to the deficits in learning and memory.

Aging↗
PubMedDate not supplied

Disseminated histoplasmosis in a sea otter (Enhydra lutris).

Disseminated histoplasmosis was diagnosed in a 4.75-year-old, captive female sea otter (Enhydra lutris). At necropsy, the liver was found to be markedly swollen, with many nodules (4-12 mm in diameter). Histologically, macrophages containing numerous intracellular yeast-like organisms were noted in the liver, spleen, lung and kidney. These organisms were labelled immunohistochemically with anti-histoplasma yeast antibody. Ultrastructurally, the yeast-like organisms, 2-4 microm in diameter, were found within membranous structures in the cytoplasm of macrophages. This is the first confirmed report of disseminated histoplasmosis in sea otters.

Animals↗