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Biomedical subjects

M Fujimoto

Publications and source records attributed to M Fujimoto.

At least 559 records · Page 31Linked to original sources
PubMed1979

New bronchodilators. Synthesis and bronchodilating activity of some 3-(alkoxymethyl)-alpha-(N-substituted aminomethyl)-4-hydroxybenzyl alcohols.

A series of 3-(alkoxymethyl)-alpha-(N-substituted aminomethyl)-4-hydroxybenzyl alcohols was synthesized as potential bronchodilators. The ability to prevent effects against histamine-induced bronchoconstriction in guinea pigs was studied to determine their bronchodilating activity. Introduction of a methoxymethyl group in place of the m-hydroxyl group of beta-adrenergic catecholamines afforded compounds especially effective in delaying histamine-induced bronchoconstriction in guinea pigs. Appropriate N-substitution also enhanced the potency of these catecholamine analogues. 4-Hydroxy-3-(methoxymethyl)-alpha-[N-[4-(methoxymethyl)-alpha-methylphenyl]aminoethyl]benzyl alcohol hemifumarate (3r) was the most potent compound in this series.

Airway Resistance↗
PubMed1979

The measurement of intracellular sodium activities in the bullfrog by means of double-barreled sodium liquid ion-exchanger microelectrodes.

A double-barreled Na+-selective microelectrode was constructed with monensin as a liquid ion exchanger. The HCl-treated monensin was dissolved in a solvent (Corning 477317) at 10% (weight/weight). Internal reference solution of its ionic barrel was mixture of 0.49 M NaCl and 0.01 M KCl, the pH being adjusted to 3 with 0.1 M citrate-HCl buffer, whereas that of the PD barrel was 0.5 M KCl. Average slope and selectivity ratio (Na+/K+) tested on 10 different microelectrodes were -57.5 +/- 1.87 mV/P(Na) (SEM) and 6.7 +/- 0.44, respectively. The electrical resistance was an order of 10(10) ohm and the response time was less than 10 sec. Using this microelectrode, a free flow micropuncture experiment was carried out in the bullfrog kidney and the intracellular Na+ activity as well as the membrane PD was determined on the proximal tubular cell. Average value (+/- SEM, n = 15) for the intracellular Na+ and K+ was 20.7 +/- 1.56 mEq/L and 61.2 +/- 1.16 mEq/L, respectively, and -68.7 +/- 0.88 mV for the peritubular membrane PD. There was a significant negative correlation between Na+ and K+ activities within the cell, i.e., the lower the ionic activity of cellular Na+ was, the higher the cellular K+, and vice versa, the sum of these two being kept nearly constant. The above finding may be somehow related to the isosmosis in the reabsorptive process across the proximal tubular epithelium.

Animals↗
PubMed1979

Reconstruction of the slow PIII from the rod potential.

Light-induced changes in K+ efflux across the photoreceptor membrane are compensated for by active uptake of K+ by a pump, which works with a time lag causing changes in [K+]o termed the KRG. From aspartate-treated bullfrog retinas we isolated the rod potential and the slow PIII, and by using them as indices of rod function and the KRG, respectively, studied relationships between the two. We conclude in support of our previous study that in rods the pump for K+ uptake works with a time lag of some 9 sec in time constant.

Animals↗
PubMed1978

Circadian rhythm in the ornithine decarboxylase activity of rat small intestine.

Intestinal ornithine decarboxylase [L-ornithine carboxy-lyase, EC 4.1.1.17] activity was found to show a marked circadian rhythm with a peak 4 h after the start of eating in rats on a diet containing protein. In rats with an intestinal blind loop, the enzyme was induced in the portion of the intestine that came in contact with the protein meal, but not in the blind loop. Injection of tetragastrin or CCK-PZ alone had no effect on enzyme induction, but when a protein suspension was introduced into a tied loop of intestine soon after the injection of tetragastrin or CCK-PZ, the enzyme was induced in the segment to almost the same extent as in the intestines of normal rats eating a protein meal. These results suggest that the circadian rhythm in activity of intestinal ornithine decarboxylase is initiated by release of gastrin, or CCK-PZ, or both, and contact of protein with the small intestine after the intake of food containing protein.

Animals↗
PubMed1978

Seasonal change of membrane potential across the proximal tubular epithelium in bullfrog kidneys.

In order to examine the seasonal changes in the relationship between the membrane potential and potassium activity of proximal tubular epithelium, a micropuncture study was performed with potassium selective microelectrodes on the kidney of the bullfrog (Rana catesbeiana) in two different seasons: winter (7 degrees C) and summer (20 degrees C). The potasssium activity in winter animals (7 degrees C) was 2.92 +/- 0.33 (mean +/- S.D., n = 20), 63.2 +/- 12.7 (n = 26), and 2.68 +/- 0.19 (n = 26) mM for the tubular fluid, cell, and plasma, whereas that in summer animals (20 degrees C) was 2.84 +/- 0.05 (n = 22), 61.8 +/- 11.2 (n = 24), 2.63 +/- 0.24 (n = 24) mM, respectively, indicating no seasonal difference. On the other hand, the mean values of the membrane PD in winter animals were 59.4 +/- 1.8 (n = 26) and 71.7 "/- 7.2 (n = 26) mV for the luminal and peritubular borders, whereas those in summer animals were 55.1 +/- 1.7 (n = 24) and 63.9 +/- 6.9 (n = 24) mV, respectivley, indicating that there was a significant seasonal difference (p less than 0.05 and p less than 0.001). Hence, compared to winter animals, the changes in the electrochemical profile for potassium in summer animals were: 1) the peritubular membrane PD is lower and 2) the transtubular electrochemical gradient is less steep. The sodium permeability calculated as the best fitting for a modified Goldman equation was 0.01 and 0.03 for winter and summer animals, respectively. In view of the fact the potassium in the cell and luminal fluid of the proximal tubule is kept at similar levels, potassium homeostasis is maintained in both groups of animals. The seasonal changes in electrical potentials are probably be due to an increase of cellular membrane permeability to ions other than potassium and to increased paracellular shunt conductance through the epithelium.

Animals↗
PubMed1978

[Repeated intracerebral hemorrhage in malignant astrocytoma--a case of apoplectic manifestation (author's transl)].

A case of 26-year-old female with malignant astrocytoma was described. Intracerebral hemorrhage appeared in apoplectic fashion on two occasions and surgery was done after each attack. At the first operation, a hematoma in the right putaminal region was totally evacuated and a specimen from the cavity wall showed tumor cells which could not be classified histologically at that time. The patient fully recovered postoperatively. Astrocytoma was confirmed 4 months later by the second operation for the repeated intratumoral hemorrhage. Only a half of the tumor was removed by the third operation. It was apparent that the tumor occupied the site of the right basal ganglia and infiltrated the internal copsule. We discussed the massive intratumoral hemorrhage and propose a craniotomy instead of simple trepanation for the treatment of intracerebral hematoma in order to make adequate biopsy of the hematoma wall and to remove the coexisting tumor, if present.

Adult↗
PubMed1978

[The diagnosis of lumbosacral lipomeningocele by computed tomography (author's transl)].

A case of 2-month-old girl with lumbosacral lipomeningocele was reported. She was admitted for evaluation of a large soft mass in the lumbosacral area, initially noted at birth. On examination, the tumor was 7 cm in diameter and 3 cm in height. The upper part of a mass was cystic. Plain X-ray films revealed bifid lower lumbar and sacal vertebra. Spinal CT scans revealed a mass and bifid spine. An area with EMI units, 2.4+/-4.2, at L4 level and another with EMI units, -52.9+/-5.5, at L5 level were seen extending from within the canal to the subcutaneous tissue. The former was identified as water and the latter as fat. The preoperative diagnosis of lipomeningocele was made. Operation was performed under the operating microscope. A meningocele sac contained no neural element and it's surface was adhesive to lipoma. Lipoma involved cauda equina and conus medullaris in the canal. We removed the extraspinal lipoma with meningeal sac and a part of the intraspinal lipoma to avoid neurological deficit. We consider, like many authors, that intraspinal lipoma should be operated as early as possible with the help of surgical microscope. Early diagnosis is necessary. Myelography is valuable but caution is needed at time of lumbar or cisternal puncture. But spinal computed tomography is noninvasive and allows for precise diagnosis without contrast myelography. CT scan is extremely useful in diagnosing congenital abnormality of the spine.

Cauda Equina↗
PubMed1977

Electrochemical profile of K and Cl ions across the proximal tubule of bullfrog kidneys: a study using double-barreled ion-sensitive microelectrodes.

Micropuncture study was performed in the proximal segment of bullfrog nephrons with double-barreled ion-sensitive microelectrodes to determine the electrochemical profile of K and Cl across the individual borders of tubular epithelium. The mean peritubular potential obtained was -68.4 mV, and the K activity in the plasma and the cell interior was 2.64 and 61.6 mEq/liter, respectively. The calculated equilibrium potential for K was 79.3 mV. Therefore, the cell K must be maintained by some K uptake mechanism against an electrochemical gradient of 11 mV. Further, the K activity of the tubular fluid was 2.92 mEq/liter and the actually measured PD across the brush border membrane was -55.7 mV. Since the calculated Nernst K potential is 76.8 mV, the K entry from lumen to cell must be done against an electrochemical gradient of 21.1 mV in the net. These facts might suggest a possibility of bilateral existence of K uptake mechanism in both the peritubular and brush border membranes of proximal tubular cells. In contrast, the Cl activity was measured to be 9.30, 78.0, and 72.5 mEq/liter for the cell, tubular fluid, and plasma, respectively. The Nernst Cl potentials calculated were 53.6 and 51.7 mV for the brush border and the peritubular membrane, the data being less than the actually determined values, 55.7 and 68.4 mV, respectively. Thus, the Cl ion seemed to distribute passively throughout its reabsorptive process in the bullfrog proximal tubule.

Animals↗