Search PubMed⌕ Search

Biomedical subjects

S Higuchi

Publications and source records attributed to S Higuchi.

At least 487 records · Page 27Linked to original sources
PubMed1986

New method of testing for carbohydrate absorption in man. Xylose and sucrose absorption; effects of sucrase inhibition.

Absorption of carbohydrate was quantitated in 49 subjects without disease of the small bowel using a new technique for ileal perfusion. A double-lumen tube with an attached balloon was inserted retrograde through the colon and used to quantify arrival in the ileum of D-xylose and a nonabsorbable marker which had been taken orally. In the same way, absorption of sucrose and the effects of an inhibitor of alpha-glucosidase were also studied. Insertion of the assembly through the colon and intubation of the terminal ileum was usually possible within 30 min; we have designated the technique, endoscopic retrograde bowel insertion (ERBI). The test meals were 500 ml of water containing either 25 g D-xylose and 5 g polyethylene glycol (PEG 4000), or 100 g sucrose with 5 g PEG. Sucrose meals also contained 0, 100, or 200 mg of an inhibitor of alpha-glucosidase (BAYg5421). At the end of a 5-hr test period, the ratio of recovery of D-xylose relative to that of PEG indicated that 69% of D-xylose was absorbed. Five-hour urinary excretion of D-xylose was 31% of that ingested, or 45% of the D-xylose which was absorbed. Sucrose was recovered in ileal samples only when administered together with inhibitor. Rates of sucrose absorption with BAYg5421, 100 and 200 mg, were 75% and 65%, respectively. The perfusion technique of ERBI is a rapid and reproduceable approach to the distal small intestine of man which could be of value in the investigation of intestinal absorption.

Acarbose↗
PubMed1986

Lowering calcium in the nucleus tractus solitarius causes hypotension and bradycardia.

It has been shown that saline microinjected into the region of the nucleus tractus solitarius (NTS) causes, but artificial cerebrospinal fluid (CSF) in the same volume does not cause, hypotension and bradycardia. This study was done to examine the possibility that the difference in effects between saline and artificial CSF may be due to the lack of calcium ions in saline. In anesthetized rats, saline or artificial CSF with or without calcium ions was microinjected into the region of the NTS. Saline microinjected in volumes of 0.2 and 0.5 microliter produced the volume-dependent decreases in arterial pressure and heart rate. Saline with added calcium ions and artificial CSF did not elicit the hypotensive and bradycardic response, but artificial CSF without calcium ions produced hypotension and bradycardia. These results suggest that the lack of calcium ions in the injected solutions is the factor that determines the hypotensive and bradycardic response. These results suggest that lowering the local availability of calcium to the NTS neurons results in hypotension and bradycardia.

Animals↗
PubMed1986

Venous abnormality in normotensive young men with a family history of hypertension.

Maximal vasodilator capacity of resistance vessels has been shown to be reduced in normotensive young men with a family history of hypertension. The present study attempted to examine whether venous distensibility is decreased in normotensive men with hypertensive relatives. The venous pressure-volume relationship was determined in the forearm with a water-filled plethysmograph in 17 normotensive young men with hypertensive relatives (mean blood pressure, 85 +/- 2 [SE] mm Hg; age, 22 +/- 1 years) and 18 young men with no family history of hypertension (mean blood pressure, 81 +/- 2 mm Hg; age, 22 +/- 1 years). The venous pressure-volume curve in men with hypertensive relatives as compared to that in men with no family history of hypertension was shifted toward the pressure axis (p less than 0.001). This findings suggests that venous distensibility is decreased in normotensive young men with hypertensive relatives. Administration of phentolamine, 1 mg/min i.v. for 5 minutes, did not alter venous distensibility, and venous distensibility after phentolamine administration was less in men with hypertensive relatives than in men with no family history (p less than 0.001), which suggests that decreased venous distensibility found in normotensive young men with hypertensive relatives was unlikely to be related to alpha-adrenergic mechanisms. These results suggest that normotensive young men with a family history of hypertension have vascular abnormalities that involve veins as well as arteries.

Adult↗
PubMed1986

Comparative pharmacokinetics of a new benzamide neuroleptic drug in rats, dogs and monkeys using a stable isotope technique.

Comparative pharmacokinetics of a new benzamide neuroleptic drug, cis-N-(1-benzyl-2-methylpyrrolidine-3-yl)-5-chloro-2-methoxy-4-met hylamino benzamide (NBND) was studied in rats, dogs and monkeys using two deuterium-labelled compounds. NBND and 2H3-NBND, which showed no biological isotope effect, were co-administered p.o. and i.v. to rats, dogs and monkeys, and the plasma concentrations of unchanged drugs were simultaneously determined by g.l.c.-chemical ionization mass spectrometry with 2H7-NBND as an internal standard. The plasma half-lives (t1/2 beta) after i.v. administration were 1.6, 4.7 and 2.2 h in rats, dogs and monkeys at a dose of 0.2 mg/kg. Plasma clearances were 4.3, 1.7 and 1.4 l/h per kg in rats, dogs and monkeys. Absorption rate constants (Kab) were 1.1, 0.58 and 0.54 per h in rats, dogs and monkeys, at doses of 10, 3 and 5 mg/kg, respectively. Absolute bioavailabilities were 0.8, 9.5 and 1.3% in rats, dogs and monkeys, suggesting that all these species showed large first-pass effects, probably due to hepatic metabolism.

Administration, Oral↗
PubMed1986

Two modes of analgesic action of aspirin, and the site of analgesic action of salicylic acid.

The analgesic activities of aspirin and salicylic acid were investigated by means of the lame-walking test in adjuvant-induced hind-paw-oedematous rats. Aspirin showed ca. 4 times more potent analgesic activity than did salicylic acid in the lame-walking test. The analgesic activity of aspirin was decreased to the level of that of salicylic acid by injection of prostaglandin E2 into the inflamed tissue. The analgesic activity of salicylic acid was not decreased by the same treatment. Salicylic acid inhibited the lame-walking reaction when given intracerebroventricularly. On the other hand, salicylic acid did not inhibit the lame-walking reaction by topical administration on the inflamed hind paw. However, with topical administration, salicylic acid inhibited the carrageenin-induced hind-paw oedema. These results suggest that aspirin has two analgesic effects on the inflammatory pain; one may be the inhibition of prostaglandin biosynthesis by acetylation of cyclo-oxygenase, and the other may be an action due to salicylic acid. Salicylic acid may produce its analgesic action mainly via a central mechanism.

Analgesia↗
PubMed1985

Determination of plasma protein binding of propafenone in rats, dogs and humans by highly sensitive gas chromatography-mass spectrometry.

A highly sensitive method for the determination of propafenone in plasma has been established using gas chromatography-mass spectrometry with the deuterium-labelled compound as an internal standard. Plasma levels as low as 1 ng/ml were measured using 0.5-ml plasma samples. Plasma protein binding of the drug in rats, dogs and humans in vitro and in vivo was determined by the proposed method. About 90% of the drug was bound to the plasma protein in all species in vitro (20-500 ng/ml) and 69-88% in rats, 90-95% in dogs and 77-89% in humans after oral administration of the drug at doses of 50 mg/kg, 5 mg/kg and 200 mg per person, respectively.

Adrenergic beta-Antagonists↗
PubMed1985

Interactions of poly-N6-methyladenylic acid and N6-substituted-9-methyladenines with poly-5-bromouridylic acid: a novel base-pairing.

The interaction of poly-N6-methyladenylic acid (poly(m6A) with poly-5-bromouridylic acid (poly(BU) was studied by the mixing curve method. A.1 m6A: 2 BU stoichiometry was clearly indicated over a wide range of ionic strengths at neutral pH, while the binding of poly(m6A) to poly(U) is known to occur with 1 m6A:1 U. Digestion by nuclease S1 confirmed this stoichiometry, indicating the absence of single strands in a 1:2 mixture. Heating profile analysis and hydroxyapatite column chromatography provided further confirmation of this finding. To determine whether 1:2 stoichiometry holds in a monomer-polymer system, the interaction of N6-methyl-9-methyladenine (m6m9A), a corresponding monomer of poly(m6A), with poly(BU) was investigated. Equilibrium dialysis experiments showed the stoichiometry of the interaction to be 1 m6A:2 BU. Thus, we would describe some structural studies of the above complexes using c.d. and i.r. spectroscopy. Poly (m6A).2poly(BU) and m6m9A.2poly(BU) are helical and analogous to each other in structure, and the bases in the complexes are all bound by hydrogen-bonding. N6-(delta 2-isopentenyl)- and N6-allyl-9-methyladenine were also found to form complexes with poly(BU), giving similar c.d. spectra with that of m6m9A.2poly(BU). The melting experiments indicated the Tms to be substantially decreased, compared to the parent unmodified complexes, even though the Tm dependence of the polymer complex on salt concentration conforms to the typical triple strand. In the following, the biological significance of this novel pairing will be discussed.

Base Composition↗
PubMed1985

Arterial pressure and heart rate responses to calcium channel blockers administered in the brainstem in rats.

The study examined the possibility that organic calcium channel blockers alter autonomic nervous system function by acting on brainstem neurons. Intracisternal administration of diltiazem or verapamil produced dose-related decreases in arterial pressure and heart rate. Diltiazem administered by drop on the dorsal surface of the brainstem at the obex or microinjected directly into the nucleus tractus solitarius also decreased arterial pressure and heart rate. The responses were absent or markedly attenuated in rats previously treated with 6-hydroxydopamine or with bilateral electrolytic lesions of the nucleus tractus solitarius but were preserved in rats treated with atropine or with sham nucleus tractus solitarius lesions. Nifedipine or ethylene glycol-bis-(beta-aminoethyl ether)N,N'-tetraacetic acid administered on the dorsal surface of the brainstem at the obex decreased arterial pressure and heart rate. Vehicle, acid saline, or sucrose solution failed to alter arterial pressure or heart rate. These results suggest that organic calcium channel blockers produce excitation of the nucleus tractus solitarius neurons, directly or indirectly, which results in the withdrawal of sympathetic nervous activity and in the decrease in arterial pressure and heart rate. The results suggest that calcium ion plays an important role in maintaining integral function of neurons in the brainstem, particularly in the nucleus tractus solitarius.

Animals↗
PubMed1985

Pharmacological studies of furo [3,2-b] indole derivatives. I. Analgesic, anti-pyretic and anti-inflammatory effects of FI-302, N-(3-piperidinopropyl)-4-methyl-6-trifluoromethyl-furo [3,2-b]indole-2-carboxamide, in experimental animals.

The analgesic, anti-pyretic and anti-inflammatory effects of FI-302, N-(3-piperidinopropyl)-4-methyl-6-trifluoromethyl-furo [3,2-b]indole-2-carboxamide, a newly synthesized tricyclic compound, were investigated in comparison with those of nonsteroidal anti-inflammatory drugs (NSAIDs). FI-302 showed potent analgesic and antipyretic effects in the various models used. FI-302 showed an inhibitory effect on acute inflammatory response such as carrageenin-induced edema, but did not show any effect on chronic inflammatory response such as cotton pellet granuloma. These effects of FI-302 were about 2 to 7 times more potent than those of non-acidic NSAIDs such as mepirizole and tiaramide. Moreover, FI-302 had little or no ulcerogenic activity. From these results, it is conceivable that the spectrum of FI-302's activities is similar to those of non-acidic NSAIDs such as mepirizole and tiaramide. These results suggest that FI-302 is a new non-ulcerogenic anti-inflammatory compound, and should be suitably applicable for clinical purposes.

Animals↗