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Biomedical subjects

T Amano

Publications and source records attributed to T Amano.

At least 325 records · Page 18Linked to original sources
PubMed1984

Separate fractions of mRNA from Torpedo electric organ induce chloride channels and acetylcholine receptors in Xenopus oocytes.

Poly(A)+ mRNA extracted from the electric organ of Torpedo was fractionated by sucrose density gradient centrifugation. After injection into Xenopus oocytes one mRNA fraction induced the appearance of chloride channels in the oocyte membrane. Many of these channels were normally open, and the ensuing chloride current kept the resting potential of injected oocytes close to the chloride equilibrium potential. When the membrane was hyperpolarized, the chloride current was reduced. A separate fraction of mRNA induced the incorporation of acetylcholine receptors into the oocyte membrane. When translated in a cell-free system this fraction directed the synthesis of the alpha, beta, gamma, and delta subunits of the acetylcholine receptor. In contrast, the mRNA fraction that induced the chloride channels caused the synthesis of the delta subunit, a very small amount of alpha, and no detectable beta or gamma subunits. This suggests that the size of the mRNA coding for the chloride channel is similar to the preponderant species of mRNA coding for the delta subunit of the acetylcholine receptor.

Animals↗
PubMed1984

Phylogenetical and ontogenetical studies on the molecular weight heterogeneity of bovine serum transferrin.

Antitransferrin (Tf) rabbit serum was highly specific: it reacted with Tfs of ruminants, such as European breeds and Zebu breeds of cattle, Bali cattle, banteng, swamp and river types of water buffalo, anoa, goat, sheep, deer, antelope, camel, and giraffe, but did not react with serum of other non-ruminant species, such as pig, wild boar, hippopotamus, horse, rabbit, rat, chicken, etc. Electrophoresis of Tf and immunoglobulin G (IgG) complexes was carried out using sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE). Within ruminants, the following species showed two Tf molecules on SDS-PAGE; European and Zebu cattle, Bali cattle, banteng, two types of water buffalo, and two species of anoa. Other ruminants, sheep, goat, deer, antelope, camel, and giraffe, etc., showed only one Tf molecule. The Tf heterogeneity in molecular weight was, thus, restricted to Bos, Bubalus, and Anoa. The molecular weight of Tf of water buffalo was slightly larger than that of cattle on the gel. The peptide pattern from cyanogen bromide cleavage of Tf of the water buffalo differed clearly from that of cattle. Fetal Tf showed only one molecule during development, but a newborn calf has two Tf molecules, (one large and one small) within 18 hr after birth. We suggest, therefore, that the small molecules formed during the last month of gestation. The peptide patterns of adult and fetal Tfs cleaved by cyanogen bromide differed with regard to the two large peptides; fetal Tf, lacking the second-largest peptide, had twice the amount of the largest peptide compared with adult Tf. From these results, we suggest that a change in peptide sequence occurs from the last month of gestation, when the largest peptide is degraded to the second largest. However, a Tf-like protein detected in the liver microsomal fraction has only one molecular size, both in adult and in fetal livers.

Animals↗
PubMed1984

[A study on non-sterile intermittent self-catheterization for voiding dysfunction following radical uterine or rectal carcinoma surgery].

To determine the effectiveness of non-sterile intermittent self-catheterization, a study was made of 35 patients who had radical surgery of the carcinoma of the uterus or rectum between January, 1978 and October, 1982. These cases were divided into 2 groups; (1) early instituted group of 27 patients who used self-catheterization within 3 months following surgical intervention; (2) late instituted group of 8 patients who received drug treatment for more than 3 months after surgical treatments and then used self-catheterization. After the introduction of self-catheterization, urinary tract infection was evaluated on the basis of the incidence of pyuria defined as more than 5 white blood cells per high magnification field. In 16 of the 35 patients, the incidence of pyuria ranged from 0 to 20 per cent. Regarding prognostic results in the first group the application of self-catheterization, 6 patients had a residual urine ratio ranging from 0 to 20 per cent and were able to void at will. Uroflometry was performed in 9 patients in the first group. In 8 of these patients, UP max values increased 3 months after self-catheterization as compared with those before self-catheterization although their values were still lower than normal. Non-sterile intermittent self-catheterization can shorten the stay in hospital and enable the patient to live a catheter-free life.

Adult↗
PubMed1983

Specific uncoupling by islet-activating protein, pertussis toxin, of negative signal transduction via alpha-adrenergic, cholinergic, and opiate receptors in neuroblastoma x glioma hybrid cells.

Exposure of NG108-15 hybrid cells to islet-activating protein (IAP), pertussis toxin, caused strong ADP-ribosylation of one of the membrane proteins with a molecular weight of 41,000. This ADP-ribosylation was paralleled by decreases in the inhibition of cAMP accumulation in intact cells or associated with reversal of the inhibition of GTP-dependent membrane adenylate cyclase, via alpha-adrenergic, cholinergic muscarinic, or opiate receptors. The affinity of these receptors for agonists was lowered by guanyl-5'-yl beta-gamma-imidodiphosphate (Gpp(NH)p) reflecting their coupling to the guanine nucleotide regulatory protein in this cell line. This effect of Gpp(NH)p was lost in membranes of IAP-treated cells; in the absence of Gpp(NH)p, the affinity for agonist was lower in treated than in nontreated cells. In contrast, the function of these receptors to bind antagonists remained unaltered in IAP-treated cells. Thus, IAP treatment of NG108-15 cells caused specific uncoupling of negative signal transduction from inhibitory receptors to the adenylate cyclase catalytic unit via the guanine nucleotide regulatory protein, as a result of ADP-ribosylation of one of the subunits of the regulatory protein.

Adenosine Diphosphate Ribose↗
PubMed1983

Transmitter responsiveness in two newly isolated clones of neuroblastoma X glioma hybrid.

Mouse neuroblastoma clone N1E-115 cells and rat glioma clone C6 cells were hybridized and two new clones were isolated. One clone, designated NG115-301, possessed weak electric excitability to an applied current pulse, while another clone, NG115-401, generated an action potential in response to the pulse. The former clone responded to serotonin and catecholamines with slow hyperpolarizations, while the latter clone responded to catecholamines with transient depolarizations. Both clones did not respond to acetylcholine. These types of responses have not been reported in any available clones. These clones may enrich the repertoire of cell clones useful for the characterization of transmitter reception mechanisms in the nervous system.

Animals↗
PubMed1983

Cerebral vasomotor responsiveness during 100% oxygen inhalation in cerebral ischemia.

Cerebral vasoconstrictor responsiveness to 100% oxygen inhalation was measured in 149 subjects, including normal healthy volunteers and those with risk factors for cerebral arteriosclerosis (N = 87). Test results were compared among patients with hemispheric stroke and vertebrobasilar insufficiency (N = 62) with the 133Xe inhalation method. Normal volunteers without risk factors (N = 49), aged 25 to 86 years, showed symmetrical vasoconstriction. Asymptomatic subjects with risk factors (N = 38) and those with vertebrobasilar insufficiency (N = 25) had decreased hemispheric gray matter flow (Fg) values during rest, but vasoconstrictor responsiveness to 100% oxygen inhalation was not significantly reduced. In patients with acute hemispheric infarction, regional vasoconstrictor responsiveness to 100% oxygen inhalation was lost and/or paradoxically reversed; in patients with chronic hemispheric infarction, it was decreased. Testing vasomotor responses during hyperoxia is safe, clinically helpful, and demonstrates impaired vasomotor reactivity in infarcted regions.

Adult↗
PubMed1983

Cerebral vasomotor responses during oxygen inhalation. Results in normal aging and dementia.

Resting-state regional gray matter flow (Fg) values and cerebral vasoconstrictor responses induced by 100% oxygen inhalation were measured with the 133 Xe inhalation method in normal healthy volunteers aged between 15 and 86 years and in patients with senile dementia of Alzheimer's type (SDAT) or multi-infarct dementia (MID). Cross-sectional analysis revealed that there were linear decreases of oxygen responses with advancing age in 84 normal volunteers between the second to ninth decades. Eleven patients with SDAT showed bilateral and symmetrical reductions of resting-state Fg values compared with 22 age-matched normal healthy volunteers. Eight patients with MID showed no significant reduction of mean Fg values compared with normal controls and patients with SDAT. Oxygen vasoconstrictive responses in SDAT were symmetrical and similar to those seen in age-matched controls. Compared with patients with SDAT, patients with MID showed reduced oxygen vasoconstrictive responses that were asymmetrical between hemispheres as well as heterogeneous within hemispheres. Testing cerebral vasoconstrictor responses by 100% oxygen inhalation is helpful for differentiating SDAT from MID.

Aged↗
PubMed1983

Transfer function through regional cerebral cortex evaluated by a photoelectric method.

A new technique is reported for obtaining the transfer function through the regional cerebral cortex. Tissue carbon-black (CB) dilution curves were recorded with a photoelectric apparatus used as a densitometer head in cat cortex in situ following intracarotid injection of 0.2 ml of 1/40 diluted CB solution. The linearity and stationarity of the vascular system, reproducibility of the curve, and recirculation were tested. The tissue CB dilution curve, a cumulative distribution function, was first differentiated yielding two curves comprising the inlet and outlet curves. The error due to "overlapping" was corrected for by extrapolation using the gamma-density function. The transfer function through the cortex was then calculated by numerical deconvolution of the inlet and outlet curves. The validity of the calculated transfer function was verified by comparison with that obtained from actual CB dilution curves recorded simultaneously from the pial artery and superior sagittal sinus. The transfer function was further subjected to moment analysis for determining the intraparenchymal circulatory parameters of the cerebral cortex. Some examples demonstrating the applicability of technique are given.

Animals↗
PubMed1983

A simplified quantification method of complex-release activity using peroxidase as immune complex antigen.

The complement-mediated solubilization of precipitable immune complexes (complex-release activity) in serum specimens was determined by a simplified method using peroxidase as an immune complex antigen. The results correlated well with the hemolytic activity via the classical complement pathway and that via the alternative complement pathway. This simplified method proved to be reliable and useful.

Antigen-Antibody Complex↗
PubMed1982

Modulation by islet-activating protein of adenylate cyclase activity in C6 glioma cells.

The cAMP content of intact cells as well as adenylate cyclase of the membrane-rich particulate fractions was studied with C6 glioma cells that had been exposed to the culture medium supplemented with islet-activating protein (IAP), one of the pertussis toxins. Both the increase in the cellular cAMP content in response to a beta-adrenergic agonist and the stimulation of membrane adenylate cyclase by the beta-agonist and/or GTP were markedly enhanced by the IAP treatment of C6 cells, but no change was induced in affinities of the agonist (or an antagonist) or GTP for their respective sites of action (or binding). The concentration of IAP required for the half-maximal enhancement was as low as 1 pg/ml, when the time of cell exposure to the toxin was prolonged to 18 h. No enhancement was observed for the basal cAMP content or basal enzyme activity, nor was activation of adenylate cyclase by Gpp(NH)p (or NaF) affected by IAP treatment. The Vmax value of a specific and low Km GTPase was significantly smaller in the membranes of IAP-treated cells than in those of control cells. Cholera toxin treatment of cells activated adenylate cyclase without exerting any influence on these IAP actions. Thus, IAP would appear to enhance beta-receptor-coupled stimulation of adenylate cyclase, in a manner distinct from cholera toxin, by rendering more GTP available to the GTP sites on the regulatory subunit of the receptor-enzyme system.

Adenine Nucleotides↗