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Biomedical subjects

J Watanabe

Publications and source records attributed to J Watanabe.

At least 451 records · Page 25Linked to original sources

Enhancement of platelet aggregation by low-density lipoproteins from IDDM patients.

Low-density lipoprotein (LDL) is known to enhance platelet sensitivity to some aggregating agents. In this study, we observed that LDL isolated from patients with insulin-dependent diabetes mellitus (IDDM) enhanced thrombin-induced platelet aggregation to a greater extent than LDL isolated from matched controls (P less than .01). Thromboxane B2 production during aggregation was also significantly more enhanced by LDL isolated from IDDM than by control LDL (P less than .01). There was no difference in the lipid composition (free and esterified cholesterol, total phospholipids, and triglycerides) of LDL isolated from diabetic and control subjects. In contrast, the extent of glycosylation of LDL isolated from diabetic patients was significantly greater than that observed in LDL from normal subjects (P less than .01), and a positive correlation (r = .605, P less than .01) between the degree of LDL glycosylation and the rate of platelet aggregation was observed. LDL glycosylated in vitro enhanced thrombin-, collagen-, and adenosine 5'-diphosphate-induced platelet aggregation to a greater extent than control LDL (P less than .01). Although LDL glycosylated in vitro was taken up by platelets to a greater extent than control LDL (P less than .05), the lipid composition (free cholesterol and phospholipid) of platelets was not significantly changed. We postulate that an increased degree of glycosylation of LDL may enhance its uptake by platelets and lead to increased platelet reactivity to aggregating agents, probably by altering the structure of the platelet membrane. The enhancement of platelet aggregation by LDL may contribute to the accelerated development of atherosclerosis in diabetes mellitus.

Adolescent↗

Age dependence in capacity-limited jejunal decarboxylation of levodopa in rats.

The extent of levodopa decarboxylation in a jejunal preparation permitting continuous in situ collection of the mesenteric blood was compared in rats 5 to 104 weeks old. The fraction of the absorbed amount that was metabolized (decarboxylated) in the jejunal segment was relatively high (approximately 0.7 to 0.8) in 9- to 15-week-old rats, whereas the fraction in relatively aged (52- and 104-week-old) and young (5- and 7-week-old) rats was considerably less (approximately 0.4 or less). These fractions were found to correlate better with the extent of relative contribution of the intestine in producing the overall first-pass effect of this drug after oral administration. In addition, kinetic studies on the jejunal metabolism of levodopa in vitro showed that a capacity-limited (i.e. saturable) decarboxylation rate was highest in 11-week-old rats. Therefore, the capacity-limited decarboxylation rate in the small intestine may be a determining factor in the age-dependent systemic availability of this drug when administered orally.

Aging↗

Isolation of small cell lung cancer-associated antigen from human brain.

Previous studies have demonstrated that monoclonal antibody TFS-4 recognizes a cell surface antigen with a molecular weight of 124,000 expressed selectively on small-cell lung cancer but not on non-small-cell lung cancers and that it cross-reacts with human brain. The antigenic determinant on small-cell lung cancer and that on brain shared common characteristics, i.e., trypsin sensitivity, heat lability, and neuraminidase resistance, suggesting that they are similar peptides (T. Okabe et al., Cancer Res., 44: 5273-5278, 1984; J-i. Watanabe et al., Cancer Res., 47:826-829, 1987). In order to elucidate the nature of this unique antigen recognized by TFS-4, we have purified the antigen to homogeneity from human brain. The antigen was solubilized from brain with 0.5% Nonidet P-40, precipitated with 50% ammonium sulfate, and subsequently purified by sequential chromatographies, i.e., diethylaminoethyl-Sepharose ion exchange, immunoaffinity, and gel permeation high-pressure liquid chromatography. The antigenic reactivity was assessed by immunoblotting using TFS-4 as a primary antibody. The purified antigen showed a single protein band with a molecular weight of 124,000 on sodium dodecylsulfate-polyacrylamide gel electrophoresis detected by a silver staining technique. The results suggest that the antigen on brain tissues is structurally related to the molecule expressed on small-cell lung cancer.

Antibodies, Monoclonal↗

Monoclonal antibody that distinguishes small-cell lung cancer from non-small-cell lung cancer.

To examine whether a monoclonal antibody, TFS-4, can distinguish small-cell lung cancer from non-small-cell lung cancers, an extensive survey of fresh lung tumors, cancers from other organs, and normal tissue specimens has been carried out. The antibody has been shown to react specifically with small-cell lung cancer (15 of 15) but not with squamous cell carcinoma (0 of 20), adenocarcinoma (0 of 20) of the lung, or large-cell lung cancer (0 of 2). It reacted neither with other malignancies, including colorectal cancer, gastric cancer, and malignant lymphoma, nor with such normal tissues as trachea, lung, liver, pancreas, colon, kidney, spleen, skin, striated muscle, bone marrow, or peripheral blood cells. Interestingly, the antibody cross-reacted with central nervous tissues. The antigenic determinant on small-cell lung cancer and that on human brain were both heat labile and trypsin sensitive, but resisted treatment with neuraminidase, suggesting that they represent similar peptides. TFS-4 may be of clinical use in the diagnosis of small-cell lung cancer, while the antigen may help investigate the nature and origin of small-cell lung cancer.

Antibodies, Monoclonal↗

Physiological role of skeletal muscle glycogen in starved mice.

To study the physiological role of skeletal muscle glycogen in starved animals, effects of starvation on glycogen and glycogen phosphorylase (EC 2.4.1.1.) activity were studied in muscle fibers (morphologic study) and in whole muscles (biochemical study) of the rectus femoris muscle of mouse. Glycogen content in the liver of the starved animals was also measured. PAS reaction, strong in muscle fibers of fed animals, became weak predominantly in type IIB fibers after 2 days and almost disappeared after 4 days of starvation. Glycogen particles, numerous in the sarcoplasm between myofibrils of muscle fibers, decreased markedly predominantly in type IIB fibers after 2 days and almost disappeared after 4 days. Phosphorylase a activity, undetected in fibers of fed mice, appeared weak in type IIB fibers and very weak in type IIA fibers after 2 days and became moderate in type IIB fibers and weak in type IIA fibers after 4 days. Muscle glycogen content did not differ by 16 hours from the values of corresponding fed animals. However, liver glycogen content had already decreased after 8 hours and markedly so after 12 hours. The results support our hypothesis-"skeletal muscle glycogen is used for maintaining the blood glucose level in starved mice" (Hirose et al.: Anat. Rec., 216:133-138, 1986)-and show that type IIB fibers play a main role in maintaining the glucose level and that muscle glycogen is utilized after depletion of liver glycogen.

Animals↗

Significance of increase in glucose 6-phosphatase activity in brown adipose cells of cold-exposed and starved mice.

Cytochemical and biochemical glucose 6-phosphatase (G6Pase) activity was examined in brown adipose tissues of normal, cold-exposed, or starved mice. In addition, G6Pase activity in white adipose tissue and hexokinase activity in brown and white adipose tissues were biochemically measured. In normal animals, the reaction product for G6Pase activity was localized in the endoplasmic reticulum and nuclear envelope of brown adipose cells. The amount of the reaction product increased in cold-exposed or starved animals. Biochemical G6Pase activity (259.7 +/- 48.5 ng Pi/min/mg protein) in brown adipose tissues of normal animals was higher when the value was compared with values of other organs. Biochemical G6Pase and hexokinase activities increased rapidly in brown adipose tissues of cold-exposed animals, and a close relation was found between activities of the two enzymes. In brown adipose tissues of animals starved for 3 days, biochemical G6Pase activity increased, but hexokinase activity did not change. In white adipose tissues of normal, cold-exposed, or starved animals, G6Pase activity was very low, although the enzyme activity increased slightly in animals starved for 3 days. The results show that the high G6Pase activity in brown adipose cells probably relates to thermogenesis in cold-exposed animals and may be concerned with glucose release into the blood in starved animals.

Adipose Tissue, Brown↗

Glucose 6-phosphatase and glycogen phosphorylase activities in chondrocytes in epiphyseal cartilage of growing rats.

Glycogen, glycogen phosphorylase, and glucose 6-phosphatase (G6Pase) activities were examined cytochemically in chondrocytes of femoral epiphyseal cartilages and cartilaginous ribs of 3- and 7-day-old rats. G6Pase activity was also examined biochemically. Glycogen was abundant in chondrocytes of the reserve zone, while it became scarce in the cells of the proliferative zone. From the upper part (adjoining the proliferative zone) to the lower part of the hypertrophic zone, glycogen accumulated in chondrocytes and decreased in the cells of the degenerative zone. Inversely, glycogen phosphorylase a and G6Pase activities were relatively high in chondrocytes of the proliferative zone and upper hypertrophic zone and were low in the cells of the reserve zone, lower hypertrophic zone, and degenerative zone. The reaction product for G6Pase was present in the endoplasmic reticulum and nuclear envelope of all types of chondrocytes composing the cartilages, although the amounts of reaction product varied with the cell types in parallel with the histochemical results. Biochemical G6Pase activity was higher in epiphyseal cartilages than in cartilaginous ribs. The possible mechanism and significance of the accumulation and decrease of glycogen in chondrocytes of the epiphyseal cartilage were discussed.

Animals↗

Effects of changes in afterload impedance on left ventricular ejection in isolated canine hearts: dissociation of end ejection from end systole.

To examine how end systole differs from end ejection and also whether the slope of the end systolic pressure-volume relation can be approximated to that of the end ejection pressure-volume relation, nine isolated, perfused, paced canine hearts ejecting into a hydraulic loading system that simulated the aortic input impedance of a dog's arterial tree were studied. To measure left ventricular volume changes the heart was placed in a plethysmograph. Peripheral resistance (Rp) and arterial compliance (C) were independently varied from 1.9 (Rp = 1.9) to 3.3, 6.4, and 9.6 X 10(8) Pa.m-3.s (Rp run) with a constant value of compliance 1.3 X 10(-9) Pa-1.m3 (C = 1.3), and from C = 0.4 to C = 0.8, C = 1.3 and C = 2.3 (C run) with a constant value of resistance (Rp = 6.4). Five pressure-volume loops were obtained by changing the end diastolic volume at each value of compliance and peripheral resistance. It was clearly shown that ventricular ejection continued after end systole and the time duration between end systole and end ejection became longer with increasing arterial compliance (24(4) at C = 0.4 vs 49(4) ms at C = 2.3, p less than 0.001), while the time duration between end diastole and end systole was constant regardless of afterload impedance change. Regarding the left ventricular pressure-volume relation the end systolic relation was almost linear (r greater than or equal to 0.98) and the slope was not significantly affected by change in any afterload impedance tested. End ejection pressure-volume relation was also linear (r greater than or equal to 0.97) and the slopes in the peripheral resistance and compliance runs were lower than those of the end systolic pressure-volume relation in each corresponding run. The former slopes decreased at smaller values of Rp or larger values of C--namely, 4.4(0.6) at Rp = 9.6 vs 3.6(0.6) at Rp = 1.9, p less than 0.05; 4.8(0.6) at C = 0.4 vs 3.1(0.5) mmHg.ml-1 at C = 2.3, p less than 0.001. Thus it is concluded that end ejection is usually different from end systole and the time difference between them is affected by changes in arterial compliance. In addition, the slope of end ejection pressure-volume relation was dependent on the changes in afterload impedance and cannot be approximated to that of the end systolic pressure-volume relation.

Animals↗

Sodium, Potassium, Chloride, and Betaine Concentrations in Isolated Vacuoles from Salt-Grown Atriplex gmelini Leaves.

Vacuoles were isolated via protoplasts from the leaves of a halophyte Atriplex gmelini C.A.Mey., grown in culture solution supplemented with 250 millimolar NaCl. Lysis of the protoplasts was induced by lowering the medium osmolarity (1.2 to 1.0 molar sorbitol) and adding a detergent, a synthesized cholate derivative, 3-([3-cholamidopropyl] dimethylammonio)-1-propanesulfonate at a concentration of 0.5 millimolar and the resulting vacuoles were purified by successive dilution and floatation. Isolated vacuoles contained almost the same concentration of sodium (569 millimolar) and chloride (260 millimolar) as recorded in protoplasts (582 and 254 millimolar, respectively), suggesting that the vacuoles are the major sequestration site of NaCl in leaves of halophytes. Betaine concentration in the protoplasts was about 16 millimolar, while that in vacuoles was only about 0.24 millimolar, indicating that betaine is accumulated in the cytoplasm as a compatible solute.

Journal Article↗

Mandibular and parotid salivary excretion of procainamide and N-acetylprocainamide after intravenous administration of procainamide to rats.

Flow rate, protein level and pH of mandibular and parotid saliva samples in rats were almost stabilized 2 h after induction of salivation with pilocarpine (9.0 mg h-1 kg-1). Salivary excretion profiles of procainamide, 50 mg kg-1 i.v., and its metabolite N-acetylprocainamide (NAPA) were then investigated. Plasma and salivary procainamide levels declined bi-exponentially with time almost in parallel. Salivary procainamide levels (Y) from both types of gland were correlated with the plasma level (X) over a wide concentration range [Y = 0.108X + 1.96 (r = 0.795) for mandibular and Y = 0.917X (r = 0.974) for parotid glands]. The mean saliva to plasma concentration ratio (S/P ratio) was significantly higher in parotid (0.974 +/- 0.243) than in mandibular (0.284 +/- 0.119) saliva samples. Similar correlations and S/P ratios were observed for NAPA. Procainamide and NAPA mean S/P ratios for saliva from both glands were fairly consistent with the calculated value according to the pH-partition hypothesis.

Acecainide↗

High capacity for pulmonary first-pass elimination of propranolol in rats.

Plasma propranolol concentrations after i.v. and i.a. 1, 2.5, 5 and 10 mg kg-1 doses of the drug given intravenously or intra-arterially have been compared in 7-week-old male Wistar rats. The areas under the curves after i.a. dosing were almost twice those after i.v. dosing at any dose, despite the elimination half-lives being the same. The difference in total body clearance after i.a. dosing from that after i.v. dosing indicated a significant contribution by pulmonary clearance, which ranged from about 20 to 30 mL min-1 kg-1, to the overall first-pass elimination after the i.v. administration. The pulmonary extraction ratio was approximately 0.4 to 0.5 at the i.v. doses used. Mean pulmonary transit time was estimated to be about 1 to 2 min. There was no dose-dependence in the pulmonary first-pass elimination kinetics of propranolol.

Animals↗

Effect of age on gastrointestinal and hepatic first-pass effects of levodopa in rats.

Presystemic elimination of levodopa (20 mg kg-1) has been studied in 5- to 104-week-old male Wistar rats. The gastrointestinal and hepatic contribution to the overall first-pass effect was estimated separately after the drug had been administered intravenously, orally and intraportally. The contribution of the gut to the overall first-pass effect of this drug was greater than that of the liver in any age-group of the rats. Both the overall and intestinal first-pass effects of levodopa were greatest in 11-week-old rats and relatively small in both young (between weeks 5 and 7) and aged (between weeks 52 and 104) rats. In contrast, the hepatic first-pass effect did not show any significant age-dependent change. Age-related change in the jejunal blood flow could not explain the unique age-dependence in the intestinal first-pass metabolism of levodopa. However, the present age-dependence in the oral systemic availability of this drug between adult (11 weeks) and aged (52 to 104 weeks) rats was found to be similar to the tendency that has been reported between normal adult subjects and aged patients with Parkinson's disease.

Administration, Oral↗

Effects of the pericardium on the diastolic left coronary pressure-flow relationship in the isolated dog heart.

We studied the effects of the pericardium on diastolic left coronary pressure-flow relationships in heart-blocked and isolated canine preparations. In these preparations, the left and right coronary arteries were dilated with adenosine and perfused by means of a pressurized arterial reservoir. The diastolic left heart pressure (LHP) was controlled by the height of a reservoir connected to the left atrium and left ventricle. The right atrial and ventricular pressure i.e., coronary outflow pressure, was kept constant at 0 mm Hg. Before and after pericardiectomy, diastolic coronary pressure-flow relationships were obtained at three values of LHP (0, 15, and 30 mm Hg) with driving pressure decreasing (2 mm Hg/sec or less) from approximately 60 mm Hg to the actual zero-flow pressure (Pf = 0) during a single long diastole induced by cessation of ventricular pacing. The slopes of the coronary pressure-flow relationships were approximated by a linear regression analysis in which the correlation coefficients were greater than .98 in all cases. Before pericardiectomy, with LHP increasing from 0 to 15 and 30 mm Hg, the value of Pf = 0 significantly increased from 7 +/- 1 to 16 +/- 1 (p less than .01) and 28 +/- 2 mm Hg (p less than .01), respectively. After pericardiectomy, it increased from 7 +/- 1 to 14 +/- 1 (p less than .01) and 17 +/- 2 mm Hg (p less than .01), respectively. When LHP was at 0 and 15 mm Hg, the pericardiectomy had no effect on the value of Pf = 0.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Immunohistochemical studies on hemoglobin-haptoglobin and hemoglobin catabolism sites.

In order to clarify the catabolism sites of Hb-Hp and free Hb, the organ distributions of [125I]-Hb-Hp and [125I]-Hb were studied, and the cell types in each organ incorporating them were determined by immunohistochemical methods. After administration of [125I]-Hb-Hp in very small amounts to rats, 84.5% was incorporated into the liver, but the renal uptake was only 0.6%. [125I]-Hb was incorporated into the kidneys rather than into the liver when a fivefold greater amount of [125I]-Hb than the binding capacity of plasma Hp was administered. Parenchymal cells, but not Kupffer cells, in the liver were stained with anti-Hb or anti-Hp IgG after administration of Hb in an amount corresponding to the Hb binding capacity of Hp. The proximal tubule cells, but not the distal tubule cells, in the kidney were stained with anti-Hb IgG after administration of a fivefold greater amount of Hb than the binding capacity of Hp. On the basis of these results, we suggest that Hb-Hp was incorporated mainly into liver parenchymal cells and did not traverse glomeruli in the kidney. In contrast to Hb-Hp, free Hb could pass through the glomeruli easily and was incorporated into the proximal tubule cells.

Animals↗