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Biomedical subjects

T Hiramoto

Publications and source records attributed to T Hiramoto.

At least 37 records · Page 2Linked to original sources
PubMed1989

Preponderance of beta- over alpha-adrenoceptors in mediating the positive inotropic effect of phenylephrine in the ferret ventricular myocardium.

[3H]prazosin bound to the membrane fraction derived from the ferret ventricular muscle with high affinity in a saturable manner (Kd = 0.25 nmol/l and Bmax = 27 fmol/mg protein in the right ventricle). [3H]CGP-12177, a beta-adrenoceptor ligand, bound to the membrane fraction with a Kd value of 0.29 nmol/l and a Bmax of 42 fmol/mg protein. In the isolated ferret papillary muscle driven at 1 Hz at 37 degrees C, phenylephrine elicited a concentration-dependent positive inotropic effect. The maximal effect of phenylephrine was comparable to that of isoprenaline. Prazosin (0.3 mumol/l) shifted the concentration-response curve for phenylephrine slightly but significantly to the right, the maximal response being unaffected. In contrast, bupranolol (0.3 mumol/l) shifted the curve for phenylephrine markedly downwards: the maximal response was depressed significantly to 40% and the curve became less steep. In the presence of prazosin and bupranolol the curve was shifted to the right, being essentially parallel to the control curve. These results indicate that in the ferret ventricular myocardium both alpha- and beta-adrenoceptors mediate the positive inotropic effect of phenylephrine. The extent of contribution of the two classes of adrenoceptor is quite different from that in other mammalian species. In the ferret heart, beta-adrenoceptors predominate over alpha-adrenoceptors in mediating the positive inotropic effect of phenylephrine, although the number of beta-adrenoceptors is not especially high when compared with other species.

Adrenergic beta-Antagonists↗
PubMed1989

Repair of 254 nm ultraviolet-induced (6-4) photoproducts: monoclonal antibody recognition and differential defects in xeroderma pigmentosum complementation groups A, D, and variant.

Repair kinetics of ultraviolet (UV) light-induced (6-4) photoproducts in xeroderma pigmentosum complementation group A, D, and variant cells were studied by the enzyme-linked immunosorbent assay (ELISA) using a specific monoclonal antibody raised against (6-4) photoproducts, together with unscheduled DNA synthesis (UDS) and loss of T4 endonuclease V-susceptible sites (ESS). Group AXP35KO cells completely failed to repair both ESS (cyclobutane pyrimidine dimers) and antibody-recognizing (6-4) photoproducts until tested 24 h after irradiation, and had 2% early-time UDS. Group DXP43KO cells showed about 10% removal of both (6-4) photoproducts and ESS in 24 h, despite showing a residually higher level of 40% early-time and cumulative UDS. Thus, the results substantiated the extreme UV hypersensitivity of XP group A and D cells. However, XP52KO variant cells exhibited the normal level of UDS and ESS loss, but a slightly reduced repair of antibody-recognizing (6-4) photoproducts at 6 and 12 h after irradiation, which may account for a small UV hypersensitivity of the XP variant cells.

Antibodies, Monoclonal↗
PubMed1989

Clinical and photobiological characteristics of xeroderma pigmentosum complementation group F: a review of cases from Japan.

A 61-year-old female patient with xeroderma pigmentosum (XP), registered as XP46KO, was assigned to complementation group F by the cell fusion-complementation method. The XP46KO fibroblasts in culture exhibited a defective DNA repair capacity of 10-15% unscheduled DNA synthesis and a 3-fold sensitivity to the lethal effect of 254 nm ultraviolet light compared with normal cells. The patient had mild clinical symptoms consisting of numerous pigmented freckles and a small number of seborrheic keratosis-like papules. She had no skin cancers in the sun-exposed areas of the skin and so far no neurological abnormalities. A review of 11 Japanese group F patients revealed very mild skin symptoms with no ocular or neuro-psychiatric abnormalities. Single skin cancers occurred in only 3 of the 11 patients with an average age of 52 years for their first skin malignancy.

DNA↗
PubMed1989

Pulmonary lymphangiomyomatosis in childhood? Marked smooth muscle cell proliferation of the lung in a preadolescent girl with repeated pneumothorax and progressive dyspnea.

A 13-year-old girl with repeated spontaneous pneumothorax and progressive dyspnea is described. The biopsy specimen of the lung showed marked proliferation of smooth muscle cells in the thickened bullous wall and alveolar septa, which was similar to the findings of the pulmonary lymphangiomyomatosis. Pulmonary lymphangiomyomatosis is one of the diseases which should be considered when children have progressive dyspnea, chylous effusions and repeated spontaneous pneumothorax.

Adolescent↗
PubMed1988

Further characterization of the myocardial alpha-adrenoceptors mediating positive inotropic effects in the rabbit myocardium.

[3H]Prazosin bound with high affinity to the membrane fraction derived from the rabbit ventricular myocardium. Oxymetazoline displaced [3H]prazosin from its binding site, did not elicit a positive inotropic effect but antagonized the positive inotropic effect of phenylephrine mediated by alpha-adrenoceptors in the presence of a beta-antagonist. Naphazoline was more potent in displacing [3H]prazosin and behaved as a weak partial agonist. YM-12617 (5-[2-[[2-(2-ethoxyphenoxy)ethyl]amino]propyl]-2- methoxybenzenesulfonamide HCl), a potent selective alpha 1-antagonist, displaced [3H]prazosin and antagonized the alpha-mediated positive inotropic effect with equal potency. Thus, a good correlation was found between the potency of alpha-antagonists to displace [3H]prazosin and their ability to antagonize the alpha-mediated positive inotropic effect. On the other hand, there was no significant correlation between the Ki and the pD2 value of the alpha-agonists (norepinephrine, epinephrine, phenylephrine and naphazoline), indicating that there is a non-linear relationship between agonist binding to myocardial alpha 1-adrenoceptors and subsequent functional changes. Myocardial alpha 1-adrenoceptors showed some pharmacological characteristics which appear to be different from those in smooth muscle tissues.

Adrenergic alpha-Agonists↗
PubMed1988

Phorbol ester does not mimic, but antagonizes the alpha-adrenoceptor-mediated positive inotropic effect in the rabbit papillary muscle.

The phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) was used to examine the hypothesis that phosphoinositide turnover is involved in the regulation of myocardial contractility mediated by stimulation of alpha-adrenoceptors in the mammalian cardiac muscle. Exposure of the isolated rabbit papillary muscle electrically driven at a rate of 1 Hz at a temperature of 37 degrees C to TPA in concentrations of 10-1000 nmol/l for 30 min did not affect the basal force of contraction. The concentration-response curve for the positive inotropic effect of (-)-phenylephrine mediated by stimulation of alpha-adrenoceptors in the presence of (+/-)-bupranolol (100 nmol/l) was shifted to the right and downward by TPA in concentrations of 30-1000 nmol/l, while the effect of (-)-phenylephrine mediated by stimulation of beta-adrenoceptors in the presence of prazosin (100 nmol/l) was not decreased, but slightly enhanced by exposure of the muscle to relatively low concentrations of TPA (10-100 nmol/l). Incubation of the membrane fraction isolated from the rabbit ventricular muscle with TPA in vitro under the same condition as employed in the physiological experiments decreased the specific binding of [3H]prazosin but not that of [3H]CGP-12177, while the non-tumor promoting phorbol ester, alpha PDD, was ineffective. These results indicate that activation of protein kinase C by TPA does not mimic the positive inotropic effect of catecholamines mediated by activation of myocardial alpha-adrenoceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1988

Almitrine enhances in low dose the reactivity of pulmonary vessels to hypoxia.

Almitrine bismesylate (Alm) has been shown to increase arterial oxygen tension in patients with chronic obstructive pulmonary disease. This effect is though to be attributable to the enhancement of hypoxic pulmonary vasoconstriction (HPV). We evaluated the effect of various doses of Alm on HPV in terms of blood flow diversion associated with anoxic challenge to the left lower lobe (LLL) in dogs with the LLL and the rest of the lung separately ventilated. The stimulus-response curve shifted to the right with increasing rate of Alm infusion, suggesting that Alm enhances the reactivity of the pulmonary vessels to hypoxia. Low doses of Alm enhanced HPV, while higher doses attenuated it. This suggests that the degree of vasoconstriction in hypoxic and non-hypoxic regions depends on the dose of Alm. The same effects of Alm were also observed in peripheral chemoreceptor denervated dogs. It is supposed that the vasoconstriction induced by Alm may be attributable to a direct effect on pulmonary vessels rather than to a nervous reflex effect.

Almitrine↗
PubMed1988

The effect of sustained stellate ganglion stimulation on left ventricular contractility in the dog.

Although a progressive reduction in left ventricular contractility during sustained left stellate ganglion stimulation has been well documented, there have been no reports on the contractile state after nerve stimulation. Left ventricular contractility after cessation of 60 min of electrical (10 V. 10 Hz. 1 msec) left stellate ganglion stimulation has been assessed in open chest dogs. Before and 15 min after stimulation, left ventricular contractility was evaluated by the end-systolic pressure-segment length relationship using ultrasonic crystals during a stepwise aortic constriction to increase left ventricular afterload. Restimulation of the left stellate ganglion was also performed 15 min after cessation of the first stimulation. After sustained left stellate ganglion stimulation, the end-systolic points shifted to the right from the control and the slope of multiple pressure-segment length coordinates significantly decreased (102.5 +/- 16.1 to 76.5 +/- 10.2 mmHg/mm, mean +/- S.E., p less than 0.05, n = 5), indicating a depression of left ventricular contractility. Increased left ventricular dP/dt max and norepinephrine level in the coronary sinus gradually returned to near base line during 60 min of stimulation. These reduced responses lasted for at least 15 min after cessation of stimulation. The myocardial norepinephrine content was reduced to 0.59 +/- 0.08 (mean +/- S.E.) ng/mg wet tissue from 0.90 +/- 0.15 of the control level (p less than 0.05). These data suggested that left ventricular contractility decreased after sustained cardiac sympathetic nerve stimulation, probably due to norepinephrine reduction in the myocardium.

Animals↗
PubMed1988

No apparent neurologic defect in a patient with xeroderma pigmentosum complementation group D.

A 31-year-old female patient with xeroderma pigmentosum (XP) XP43KO was assigned to complementation group D by the cell-fusion complementation methods. Cultured XP43KO cells from our patient had the defective DNA repair phenotype showing a residual level of ultraviolet (UV)-induced unscheduled DNA synthesis (45% of normal) and an eightfold higher sensitivity to 254-nm UV killing, compared with normal cells. The phototest on the patient revealed the delayed maximum reaction to UV-B-induced erythema and lower minimal erythema doses at 290- and 300-nm monochromatic wavelengths. However, the XP43KO patient showed no apparent neurologic abnormalities and rather mild or moderate skin lesions at the age of 31 years, although DNA repair deficiency in XP43KO cells from our patient fell into the range of group D cells.

Adult↗
PubMed1987

[A case of malignant histiocytosis with paraplegia].

A 66-year-old man was admitted for shortness of breath and showed fever, abdominal fullness and paraplegia. Monocytosis amounting to 25% and an elevation of serum LDH (4,281 mIu), were remarkable in the laboratory findings. He died of pulmonary insufficiency about a month after admission. On autopsy hepatomegaly (1950 g), splenomegaly (780 g), but no lymphadenopathy and small infarction in the thoracic spinal cord causing paraplegia was noted. Histopathologically, the invasion of the tumor cells into the liver, spleen, lymph nodes, bone marrow and other organs was observed. Malignant histiocytosis was diagnosed by histologic and immunohistochemical studies (lysozyme positive, S-100 protein negative).

Aged↗
PubMed1986

Histopathological observation of the heart with diffuse and abnormal proliferation of mitochondria in myocardial cells (mitochondrial cardiomyopathy): report of an adult case.

An autopsy case of idiopathic dilated cardiomyopathy with abnormal proliferation of mitochondria in the myocardial cells is reported. The case is that of a 39-year-old male with congestive heart failure. The heart was 700 g and showed marked dilatation of all cardiac chambers with myocardial fibrosis of the left ventricular myocardium and interventricular septum, especially in the basal portion of the left ventricular posterior wall. Myocardial cells were hypertrophied with a marked increase of fine-granular sarcoplasm, containing numerous mitochondria, seen by electron microscopy. The mitochondria were usually round or oval and ranged in size from 0.3 to 1.2 micron in diameter. The cristae of these mitochondria frequently showed a concentric lamellar or reticular configuration. Myofibrils were unusually scarce, but the sarcomere structure and arrangement of myofilaments were well-preserved. Epicardial and intramural coronary vessels were almost normal. From these findings, we consider this to be an adult case of mitochondrial cardiomyopathy.

Adult↗