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T Tsukada

Publications and source records attributed to T Tsukada.

At least 271 records · Page 15Linked to original sources
PubMed1984

Glucuronidation of 7-hydroxycoumarin in periportal and pericentral regions of the liver lobule.

Rates of glucuronidation were measured at high substrate concentrations in specific zones of the liver lobule using micro-light guides placed on periportal and pericentral regions on the surface of livers from phenobarbital-treated rats. Livers were perfused with sulfate-free buffer under normoxic conditions, and fluorescence of free 7-hydroxycoumarin was monitored in the tissue. The formation of nonfluorescent 7-hydroxycoumarin glucuronide was then inhibited completely by perfusion with N2-saturated perfusate containing 20 mM ethanol. Under these conditions, fluorescence recorded from the surface of the liver was directly proportional to the concentration of substrate infused. The difference in 7-hydroxycoumarin fluorescence between N2 plus ethanol and normoxic perfusion was due to glucuronidation. Maximal rates of glucuronidation in periportal and pericentral regions of the liver lobule calculated with this new method were 9.6 and 35 mumoles/g/hr, respectively. Glucuronidation was half-maximal with 25-50 microM 7-hydroxycoumarin in both regions. Glucuronosyltransferase activity assayed in microdissected, freeze-dried tissue samples in vitro was 3-fold greater in pericentral areas than in periportal areas. This activity was half-maximal with 0.2 mM UDP-glucuronic acid and 54 microM 7-hydroxycoumarin in both regions of the liver lobule. Thus, the maximal capacity of the glucuronidation system determined in vitro is about 3-fold greater in pericentral than in periportal regions of the liver lobule, a difference which correlates well with measured rates of glucuronidation of 7-hydroxycoumarin in the two zones of the lobule in the intact, perfused liver.

Animals↗
PubMed1984

Pharmacological differentiation between large and small coronary vessels.

It has been reported that there are striking differences between large and small coronary arteries in their responsiveness to adenosine, nitroglycerin and catecholamines. The differential pharmacological responsiveness indicates differences in their excitation-contraction coupling mechanisms. Therefore, agents such as lyotropic anions (SCN-, NO3-, CH3SO4-) known to modulate these processes, and which by themselves do not have an inotropic effect, would be expected to differentially modulate the action of these substances on large and small coronary vessels. To test this hypothesis we studied the modulation by lyotropic anions of the effects of adenosine, nitroglycerin and verapamil on large and small intramural (0.5-0.6 mm diameter) dog coronary arteries. We have confirmed that small vessels are more sensitive to adenosine and verapamil and less sensitive to nitroglycerin than are large vessels. Replacement of Cl- by the lyotropic anions diminished the relaxing effects of adenosine in small vessels with the following order of potency, SCN- greater than NO3- greater than CH3SO4- greater than Cl-. NO3-. Replacement of Cl- resulted in almost total blockade of the adenosine response in small coronary arteries, whereas in large coronary vessels, the effects of nitroglycerin were reduced only 30%. The effects of verapamil in small vessels were slightly depressed whereas in large vessels its effects were unchanged. Our results further confirm that there are marked differences between the pharmacological responsiveness of large and small coronary vessels, indicating that these differences reside in the nature of their mechanisms controlling Ca++ translocation.

Adenosine↗
PubMed1983

Evidence for noradrenergic involvement in naloxone-induced stimulation of luteinizing hormone release in prepubertal female rats.

The effects of phenoxybenzamine an alpha-adrenergic blocker, propranolol a beta-adrenergic blocker, and diethyldithiocarbamate a noradrenaline synthesis inhibitor, on the LH increase induced by naloxone an opiate antagonist, was investigated in 25 day old female rats. Pretreatment with phenoxybenzamine or diethyldithiocarbamate suppressed the LH increase induced by naloxone, whereas pretreatment with propranolol had no significant effects on the naloxone-induced LH release. These results suggest that naloxone-induced increase in LH release is mediated via a noradrenergic mechanism.

Animals↗
PubMed1983

Nephelometric determination of plasminogen and plasmin inhibitors in human plasma using fibrin suspension as a substrate.

A nephelometric method is described for determination of plasminogen and two types of plasmin inhibitors in human plasma having different affinity toward plasmin. This method is based on the kinetic analysis of effects of whole plasma and plasmin inhibitor fraction obtained from plasma on the activity of exogenously added plasminogen which was determined by measuring the decrease of light scattering of fibrin suspension. With this method we have determined the activity of plasminogen and two types of inhibitors in the plasma of normal subjects and patients with high fibrinogen degradation product values. They include patients with various malignant tumors with DIC, chronic renal failure, sepsis, vascular diseases, and liver cirrhosis with hepatoma.

Female↗
PubMed1983

Biosynthesis and distribution of opioid peptides.

Group III opioid peptides are derived from proenkephalin B. The processing of this precursor peptide is still only partly understood and we still do not know how many final products come from proenkephalin B and whether Leu-enkephalin is produced from Group III peptides. However, potent biologic activity of Group III opioid peptides and existence of opiate-receptors specific for these peptides (k receptors) strongly suggest that Group III opioid peptides are not precursors of Leu-enkephalin but bioactive substances per se. Further studies should clarify details of the processing of proenkephalin B.

Adrenal Medulla↗
PubMed1983

Emperipolesis and annulate lamellae in erythroleukaemia.

The bone marrow in the erythraemic phase of 2 erythroleukaemia patients was studied electron microscopically. Emperipolesis of erythrocytes as well as annulate lamellae were revealed in the cytoplasm of the erythroblasts of these cases. It is assumed that these findings show a high rate of erythroblastic proliferation. This is the first report of emperipolesis within the erythroblast by erythroleukaemia. In addition, other various abnormalities, namely, nuclear-cytoplasmic asynchrony, nuclear bleb or cleft formation, abundant glycogen particles and ferruginous micelles in mitochondria such as described in some previous reports, were also recognized.

Adult↗
PubMed1983

Plasma adrenocorticotropin and cortisol responses to intravenous injection of corticotropin-releasing factor in the morning and evening.

Plasma ACTH and cortisol responses to corticotropin-releasing factor (CRF) were determined in the morning and evening in seven normal men. Either 100 micrograms synthetic ovine CRF or saline was given intravenously at 0900 h and at 2200 h. Blood samples were collected before and 15, 30, 45, 60, 90, and 120 min after CRF or saline injection. Plasma ACTH concentrations before and after CRF injection in the morning were significantly higher (P less than 0.05) than those in the evening at all times except 45 min after injection. Plasma cortisol concentrations before and at all times after CRF injection in the morning were also significantly higher (P less than 0.05) than those in the evening. However, neither the maximum increments in plasma ACTH and cortisol above the control levels nor increments at each time point following CRF injection in the morning differed significantly from those in the evening. Increments in the area under the ACTH and cortisol concentration curves after CRF injection in the morning also did not differ significantly from those in the evening. These results suggest that the responsiveness of the pituitary to CRF in the morning and in the evening does not differ significantly, although actual values of plasma ACTH and cortisol are higher in the morning.

Adrenocorticotropic Hormone↗
PubMed1983

[Clinical evaluation of cefotaxime in complicated urinary tract infections].

Fourteen cases with complicated urinary tract infection were treated with 2 g of cefotaxime for 5 days; in total doses of 10 g. Excellent or good results were obtained in 11 cases (78.6%) and no adverse reaction was observed. A curious finding was the development of eosinophilia in some patients. The causative mechanisms and clinical meanings of the phenomenon have not been clarified.

Adult↗