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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 379 records · Page 21Linked to original sources
PubMed1993

Malignant exophthalmos associated with multiple myeloma.

We report a patient with malignant exophthalmos associated with multiple myeloma which showed no evidence of direct orbital involvement of plasma cells. This exophthalmos had similarities with Graves' ophthalmopathy, but the patient had no detectable autoimmune thyroid diseases. Plasmapheresis was effective not only for the treatment of heart and renal failure due to the myeloma kidney but also for the malignant exophthalmos. As the serum monoclonal IgG level was decreased by plasmapheresis, the improvement of proptosis, visual acuity, and hypertrophy of the extraocular muscle as measured by magnetic resonance imaging were observed. It is suggested that humoral factors removed by plasmapheresis might be involved in the pathogenesis of this nonendocrine exophthalmos.

Aged↗
PubMed1993

Measurement of transverse stiffness during contraction in frog skeletal muscle using scanning laser acoustic microscope.

The change in the transverse propagation velocity was measured by the scanning laser acoustic microscope (SLAM) during contraction in living frog skeletal muscles. The images of the interferogram were processed by image-analyzer and the propagation velocity was calculated from the shift of the interference lines at rest and during contraction. In all the measurements, the velocities during contraction were clearly slower than at rest and this fact indicates that the transverse stiffness decreased during contraction. After stimulation, the beginning of the decrease in the propagation velocity preceded that of the increase in force by 30-40 ms, suggesting that the decrease in the transverse stiffness reflects the molecular mechanism of force development in muscular contraction.

Acoustics↗
PubMed1993

Iron-binding properties of bovine lactoferrin in iron-rich solution.

The iron-binding properties of bovine lactoferrin in iron-rich solution were investigated. Ferrous iron was not stable in solution and was easily changed to the insoluble ferric state, but solubility of ferrous iron was stabilized by the presence of lactoferrin. However, casein hydrolysate or BSA was not effective in stabilizing iron in solution. As indicated by use of cibacron blue affinity gel, iron bound to lactoferrin, and the charge of supersaturated lactoferrin was higher than that of normal iron-saturated lactoferrin according to native PAGE electrophoresis. The evidence suggests that lactoferrin can bind iron at sites other than its chelate-binding sites, thereby stabilizing iron in solution.

Animals↗
PubMed1993

Pregnancy-associated changes in plasma metallothionein concentration and renal cadmium accumulation in rats.

Pregnancy-associated changes in metallothionein (MT) concentrations in blood plasma were examined using a competitive enzyme-linked immunosorbent assay with a rabbit polyclonal antibody to rat liver MT. Plasma MT of pregnant rats significantly increased after 8 days of gestation and remained high during pregnancy and for 7 days after delivery. Gel filtration showed that both Cu and Zn were associated with the plasma MT of pregnant rats. These results suggest that plasma MT may play a role in the transport of essential metals such as Cu and Zn to fetus during pregnancy, but the source of plasma MT is unknown. Injections of cadmium chloride and cadmium-metallothionein to pregnant rats further increased the plasma MT concentrations. After injection of CdCl2, both MT and Cd concentrations in the liver of the pregnant rats were significantly lower than those of the nonpregnant rats, whereas renal Cd and MT levels were higher in pregnant rats. This increased accumulation of Cd in the kidney of pregnant rats may be related to the increase of plasma MT during pregnancy. About 5% of 6 pg of in vitro added Cd (20 pg/ml) was bound to the MT in the plasma. Therefore, Cd may be transported by the circulating MT to the kidney, leading to an increase in renal accumulation of Cd in pregnant rats.

Animals↗
PubMed1993

Hormonal responses to head-out water immersion diminish after exposure to head-down tilt.

It has been postulated that gravitational change from 1 g to microgravity may cause cephalad fluid shift, resulting in suppression of antidiuretic hormone (ADH) secretion and diuresis (Gauer-Henry's reflex). However, results obtained in space flights did not confirm this. Since astronauts are confined at supine position for hours before launch, this posture may abolish the reflex in space flight. To investigate this possibility, effects of head-out water immersion (WI) after 2-hour head-down tilt (HDT) on hormonal and metabolic responses were examined and compared with those after 1-hour upright posture (UP). Hematocrit decreased by WI after UP, indicating hemodilution, but it did not change by WI after HDT. Plasma ADH, renin activity and aldosterone fell and atrial natriuretic peptide (ANP) rose by WI after UP, resulting in increased urine flow. On the other hand, appreciable hormonal changes were not elicited by WI after HDT, and urine flow stayed unchanged. These results indicate that fluid shift and hormonal and metabolic responses to WI are strongly attenuated by the prior exposure to HDT. Pre-launch posture of astronauts may at least partly explain why either suppression of ADH or diuresis was not observed on arrival at space.

Adult↗
PubMed1993

Ifenprodil prevents glutamate cytotoxicity via polyamine modulatory sites of N-methyl-D-aspartate receptors in cultured cortical neurons.

Neuroprotective effects of ifenprodil, a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, against glutamate cytotoxicity were examined in cultured rat cortical neurons. The viability of the cultures was markedly reduced by a 10-min exposure to glutamate followed by incubation with glutamate-free medium for 60 min. Ifenprodil and its derivative SL 82.0715 dose-dependently prevented cell death induced by glutamate. The NMDA antagonists MK-801 and 3-[(+/-)-2-carboxypiperazin-4-yl]propyl-1-phosphonic acid also prevented glutamate cytotoxicity with a potency similar to that of ifenprodil. Ifenprodil as well as MK-801 prevented NMDA-induced cytotoxicity, but did not affect kainate-induced cytotoxicity. Glutamate cytotoxicity was inhibited by removing extracellular Ca++ during and immediately after glutamate exposure. Ifenprodil and MK-801 reduced NMDA-induced Ca++ influx measured with rhod-2. Either spermidine, a polyamine modulatory site agonist, or glycine, a strychnine-insensitive glycine site agonist, potentiated NMDA- and glutamate-induced cytotoxicity. The protective effects of ifenprodil against NMDA- and glutamate-induced cytotoxicity were significantly reduced by spermidine, but not by glycine. These findings indicate that ifenprodil protects cortical neurons against glutamate cytotoxicity by selective antagonism of the polyamine modulatory site of the NMDA receptor complex.

Animals↗
PubMed1993

Mechanistic aspects of the interaction of antisense DNA.

To investigate the mechanism of antisense effects, diastereoisomerism of oligodeoxynucleotides with modified internucleotide phosphate linkages such as oligodeoxynucleoside phosphoramidates (OPA) and oligodeoxynucleoside phosphorothioates (OPT). Reversed-phase HPLC was used to separate the diastereoisomers of OPA (up to tetramer) and OPT (up to pentamer), and it was found that the complete purification of all diastereoisomers could be achieved by the two-step chromatographic approach. From the circular dichroism measurements, it was found that some diastereoisomers formed certain hybrids with their complementary oligonucleotides and some did not.

Chromatography, High Pressure Liquid↗
PubMed1993

Treatment of chronic dislocation or subluxation of the distal radioulnar joint.

Twenty-eight patients with chronic instability of the distal radioulnar (DRU) joint were treated with 4 procedures: Sauvé-Kapandji procedure (11 cases), Milch ulnar shortening osteotomy (9 cases), Bowers hemiresection interposition arthroplasty (4 cases), or ligamentous reconstruction (4 cases). The indication for operation in all cases was pain in the DRU joint and weakness of grip strength. Sixteen of 28 patients also complained of limitation of forearm rotation. At an average follow-up of 18 months, there were 72% satisfactory results in patients treated with the Sauvé-Kapandji procedure, 88.9% with the Milch procedure, 75% with the Bowers procedure, and no satisfactory results with ligamentous reconstruction. We believe that the Milch procedure is indicated for the wrist with mild instability with adequate articular surface of the DRU joint. The Bowers procedure and the Sauvé-Kapandji procedure are useful in treating patients with gross instability with or without articular damage to the DRU joint.

Adolescent↗
PubMed1993

[A case of dual origin of the left anterior descending coronary artery from the left and right coronary arteries with variant angina].

We present a case of a 68-year-old male inflicted with a rare anomaly of the coronary artery. He had been suspected to have worsening effort angina and underwent urgent cardiac catheterization. The coronary angiography revealed 75% stenosis in the first diagonal branch. The left anterior descending artery was terminated in the mid portion and did not reach the apex. Instead, an anomalous coronary artery from the portion just proximal to the right coronary artery reached the apex. After cardiac catheterization, nocturnal chest pain at rest started to occur frequently. We suspected that vasospasm may have occurred because ST segment elevations in leads II, III, aVF were recorded on the electrocardiogram. Administration of diltiazem (120 mg per day) suppressed angina. Exercise stress electrocardiogram and thallium-201 myocardial scintigram did not show apparent ischemia. This case suggests that we must consider the presence of coronary vasospasm even in patients with clinically-supposed effort angina, to be possibly due to vasospasm occurring in anomalous coronary arteries.

Aged↗
PubMed1993

[Antiatherogenic action of omega-3 polyunsaturated fatty acids].

Recently, atherosclerosis has become a matter of great concern because of a rapid increase of aged people. It has been widely known that omega-3 polyunsaturated fatty acids, rich in marine fish oil, have an antiatherogenic action. The mechanism is ascribed to its action on serum lipids, functions of the platelets, endothelial cells, smooth muscle cells and macrophages, prostaglandin and leukotriene metabolism, growth factor and cytokine production, EDRF production, blood pressure, etc. In this paper the basic and clinical evidences concerning the effects of fish oil on these multifactors, which are deeply involved in the development of atherosclerosis are reviewed.

Animals↗
PubMed1993

[Posterolateral rotatory instability of the elbow--a case report and anatomical study of the lateral collateral ligament].

A 20-year-old woman was referred to our clinic complaining of recurrent subluxation of her right elbow. A posterolateral rotatory instability test revealed that she had insufficiency of the lateral collateral ligament. She was surgically treated; the ligament was reconstructed by using the palmaris longus tendon. A year after operation, she had no pain in her elbow, and regained full range of elbow motion. The function of the lateral collateral ligament is often overlooked. We, therefore, dissected 24 elbow joints and studied anatomically in order to confirm the origin and insertion of the lateral collateral ligament. The ligament originates from the lateral epicondyle, and runs distally in fan shape. It further inserts partly to the annular ligament and partly to the supinator crest. After complete sectioning of the ligament, the forearm was fixed in supination, then flexed with valgus moment. This maneuver elicited subluxation of the radio-humeral joint, which was similar to what we observed in the clinical case. From these observations, we have concluded that the ligament is important for stability of elbow joint as well as the medial collateral ligament.

Adult↗
PubMed1993

[A case of T-cell type malignant lymphoma of the lung].

A case of T-cell type malignant lymphoma of the lung was reported. A 69-year-old woman was referred to our institute because of an abnormal shadow on the chest roentgenogram. She was symptom-free, and physical examination showed no abnormalities. Her laboratory tests were within normal limits. The chest roentgenogram showed a well-defined, nodular density in the left lower lung field without air bronchogram. She underwent a left lower lobectomy and a mediastinal lymphnodes dissection. This disclosed an elastic hard nodule, 2 cm in diameter, without pleural invasion. Pathologically the tumor was diagnosed as malignant lymphoma of T-cell type without regional lymphnode involvement. She is doing well without any sings of recurrence for one year after the operation.

Aged↗
PubMed1992

Mechanisms of cholecystokinin-induced protection of cultured cortical neurons against N-methyl-D-aspartate receptor-mediated glutamate cytotoxicity.

The protective effects of cholecystokinin (CCK) against glutamate-induced cytotoxicity were examined using cultured neurons obtained from the rat cerebral cortex. Cell viability was significantly reduced when the cultures were briefly exposed to glutamate or N-methyl-D-aspartate (NMDA) and then incubated with normal medium for 60 min. A 60-min exposure to kainate also reduced cell viability. CCK protected cortical neurons against glutamate-, NMDA- and kainate-induced cytotoxicity. Glutamate- and NMDA-induced cytotoxicity was also reduced by N omega-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor. However, CCK did not prevent the cytotoxic effects of sodium nitroprusside (SNP) which spontaneously releases NO. Moreover, CCK did not affect NMDA-induced Ca2+ influx measured with rhod-2, a fluorescent Ca2+ indicator. Therefore, release of a NO-like factor from the cerebral cortex was assayed using the thoracic artery in vitro. When the artery was incubated with minced cerebral tissues, glutamate elicited marked relaxation. SNP also elicited relaxation of the smooth muscle. CCK inhibited glutamate-induced relaxation but did not affect that induced by SNP. These results indicate that CCK prevents NMDA receptor-mediated cytotoxicity without reducing the Ca2+ influx. It is suggested that CCK inhibits NO-formation triggered by NMDA receptor activation.

Amino Acids↗
PubMed1992

The relative importance of glutathione and metallothionein on protection of hepatotoxicity of menadione in rats.

The effects of induction of metallothionein (MT) on the toxicity of menadione were investigated in rat liver slices. The protective role of hepatic glutathione (GSH) was also studied and compared to that of MT. A 3-h incubation of rat liver slices with menadione (100-300 microM) containing medium (37 degrees C, pH 7.4, 95%O2:5%CO2) resulted in cellular toxicity, as shown by changes in cytosolic K, Ca and GSH concentrations and lactate dehydrogenase (LDH) leakage. A dose-dependent decrease in cytosolic K and GSH was observed concomitant with an increase in cytosolic Ca and LDH leakage after incubation with menadione. Pretreatment of rats with zinc sulphate (ZnSO4) (30 mg/kg body wt.) increased MT levels in liver slices and suppressed the toxicity of menadione. Intracellular GSH concentrations in liver slices were either depleted or increased by injection of rats with buthionine sulfoximine (BSO), (4 mmol/kg body wt.) and N-acetyl-L-cysteine (NAC) (1.6 g/kg body wt.), respectively. Intracellular GSH was found to be crucial in protection against menadione toxicity. Menadione toxicity was increased when the rats were injected with sodium phenobarbital (PB) (4 x 80 mg/kg body wt.). Pretreatment with Zn provided partial protection against menadione toxicity in liver slices from both BSO- and PB-injected rats. These findings suggest that induction of MT synthesis does protect against quinone-induced toxicity, but the role may be secondary to that of GSH. The mechanisms by which MT protect against menadione toxicity are still unclear but may involve protection of both redox cycling and sulphydryl arylation.

Acetylcysteine↗
PubMed1992

Immediate effects of percutaneous transvenous mitral commissurotomy on pulmonary hemodynamics at rest and during exercise in mitral stenosis.

Hemodynamics were evaluated during exercise in 33 patients with mitral stenosis who underwent percutaneous transvenous mitral commissurotomy (PTMC). PTMC was performed using an Inoue balloon. Each patient underwent a supine ergometer exercise test before and on the day after PTMC. Ergometer work load was started at 20 W and increased in increments of 20 W at 3-minute intervals until terminated by the patient's fatigue or shortness of breath. Mitral valve area increased by 0.8 +/- 0.4 cm2 (1.1 +/- 0.3 to 1.9 +/- 0.4 cm2, p less than 0.001). Mean mitral pressure gradient decreased (12 +/- 5 to 6 +/- 2 mm Hg, p less than 0.001). Pulmonary arterial pressure significantly decreased and the cardiac index significantly increased both at rest and during exercise after PTMC. Before PTMC, the increases in pulmonary arterial pressure, total pulmonary resistance and pulmonary arteriolar resistance during exercise were greater in patients with a mitral valve area less than 1.0 cm2 than in patients with an area greater than or equal to 1.0 cm2. After PTMC, total pulmonary resistance still increased during exercise. However, pulmonary arteriolar resistance did not change during exercise in patients with a mitral valve area greater than or equal to 1.5 cm2, whereas it increased in patients with an area less than 1.5 cm2. An enlarged mitral valve area greater than or equal to 1.5 cm2, which may prevent pulmonary vasoconstriction and permits a greater increase in pulmonary blood flow during exercise, is considered a good result immediately after PTMC.

Cardiac Catheterization↗