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Biomedical subjects

M Tamura

Publications and source records attributed to M Tamura.

At least 487 records · Page 27Linked to original sources
PubMed1994

Immunohistochemical distribution of progesterone, androgen and oestrogen receptors in the human ovary during the menstrual cycle: relationship to expression of steroidogenic enzymes.

In order to characterize immunohistochemically the possible in-situ effects of gonadal steroid hormones in the human ovary during the menstrual cycle, we immunolocalized progesterone (PR), androgen (AR) and oestrogen (ER) receptors in 50 normal cycling human ovaries, and examined the relationship between these findings and the cellular localization of steroidogenic enzymes including cytochrome P-450 cholesterol side-chain cleavage (P-450scc) enzyme, 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), cytochrome P-450 17 alpha-hydroxylase (P-450c17) and cytochrome P-450 aromatase (P-450arom). A large number of stromal cells were positive for AR, regardless of the distance from a follicle. No steroidogenic enzymes were observed in the stromal cells. In the pre-antral follicle, AR was observed in the theca cells. P-450scc, 3 beta HSD and P-450c17 were sporadically expressed in the theca cells in relatively large-sized pre-antral follicles. ER was positive in the granulosa cells only in the P-450arom-positive antral or pre-ovulatory follicle, which is likely to be a selected follicle. In the corpus luteum, in the period from ovulation to the mid-secretory phase, PR immunoreactivity was observed in a large number of both the luteinized granulosa and the theca cells. All steroidogenic enzymes were observed in all corpora lutea, but ER was negative in any corpus luteum. In the atretic follicle, AR was present in the theca interna cells. P-450scc, 3 beta HSD and P-450c17 were observed in the theca interna cells in some atretic follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxysteroid Dehydrogenases↗
PubMed1994

Modulation by polymyxin B of the effects of interferon on human myelogenous leukemia cells.

Natural and recombinant human interferon-alpha (IFN-alpha) and -gamma (IFN-gamma) exert differentiation-inducing and cytocidal effects in vitro on cells of the human myeloblastic leukemia cell line ML-2. These activities of IFNs are modulated by polymyxin B (PMB), a cyclic polycationic peptide antibiotic effective on Gram-negative bacilli. The modulating effect of PMB varies according to the species of IFN, namely, PMB enhances the activities of either natural IFN-gamma or recombinant IFN-gamma, while it inhibits the effects of either natural IFN-alpha or recombinant IFN-alpha. The cause of this variety in PMB effect on IFNs remains to be clarified.

Cell Differentiation↗
PubMed1994

Eosinophilic leukaemia with a t(2;5) (p23;q35) translocation.

Although the diagnosis of rare eosinophilic leukaemia is possible based on cytogenetic abnormalities, the chromosomal aberrations reported are diverse. We found a t(2;5) (p23;q35) translocation on bone marrow cells of a patient with chronic eosinophilia who suffered from multiple pustular folliculitis but lacked the clinical symptoms commonly observed in hypereosinophilic syndrome. No morphological abnormalities in an eosinophilic series were apparent and other haemopoietic cells were well preserved. A therapeutic trial with interferon-alpha failed after a 2-month period, and the patient is currently undergoing a combination therapy with interferon and intermittent administrations of hydroxyurea.

Adult↗
PubMed1994

A new protocol for the perinatal management of patients with congenital diaphragmatic hernia with severe hypoplastic lungs and its clinical application.

It is prerequisite for the pre-operative management of patients with congenital diaphragmatic hernia (CDH) to avoid the factors that increase pulmonary vascular resistance, because such patients easily fall into the state of persistent fetal circulation (PFC). In this paper, a new protocol is proposed for the perinatal management of CDH patients to prevent the PFC which is facilitated by the enlargement of hernia and the deviation of mediastinum caused by spontaneous breathing just after birth. We also describe the usefulness of this protocol based on our experience in which we successfully treated a patient with CDH with severe hypoplastic lungs that were diagnosed antenatally by ultrasonographic examination. In treating the CDH patient with severe hypoplastic lungs, it is effective for the respiratory control and the prevention of PFC to administer morphine and pancuronium to the neonate through the umbilical vein before the resection of the umbilical cord. In the case of Cesarean section, in addition to the direct administration of morphine to the patient, administration of morphine to the patient's mother just before the delivery is more effective to prevent PFC, which can be easily induced by the initial resuscitation at birth.

Cesarean Section↗
PubMed1994

Congenital diaphragmatic hernia treated by perinatal stabilization.

The delay of surgery in conjunction with high-frequency oscillation ventilation combined with preoperative stabilization is a standard treatment for congenital diaphragmatic hernia neonates in the high-risk group. A new protocol of perinatal stabilization with this preoperative stabilization has been developed at the University of Tokyo Hospital. The most important components of this method of perinatal stabilization are cesarean section and the injection of morphine and pancuronium through the umbilical vein prior to ligation of the umbilical cord. In order to benefit from this treatment, congenital diaphragmatic hernia patients should be diagnosed antenatally by ultrasonography and be delivered by cesarean section. This protocol of perinatal stabilization appears effective in congenital diaphragmatic hernia patients.

Fatal Outcome↗
PubMed1994

Subtype cross-reactive, infection-enhancing antibody responses to influenza A viruses.

Antibody-dependent enhancement of the uptake of influenza A virus by Fc receptor-bearing cells was analyzed by using virus strains of the three human influenza A virus subtypes, A/PR/8/34 (H1N1), A/Japan/305/57 (H2N2), and A/Port Chalmers/1/73 (H3N2). Immune sera obtained from mice following primary infection with an H1N1, H2N2, or H3N2 subtype virus neutralized only virus of the same subtype; however, immune sera augmented the uptake of virus across subtypes. Immune sera from H1N1-infected mice augmented uptake of the homologous (H1N1) and H2N2 viruses. Antisera to the H2N2 virus augmented the uptake of virus of all subtypes (H1N1, H2N2, or H3N2). Antisera to the H3N2 virus augmented the uptake of the homologous (H3N2) and H2N2 viruses. These results show that subtype cross-reactive, nonneutralizing antibodies augment the uptake of influenza A virus strains of different subtypes. Antibodies to neuraminidase may contribute to the enhanced uptake of viruses of a different subtype, because N2-specific monoclonal antibodies augmented the uptake of both A/Japan/305/57 (H2N2) and A/Port Chalmers/1/73 (H3N2) viruses.

Animals↗
PubMed1994

Left ventricular preload reserve in preterm infants with patent ductus arteriosus.

The left ventricular Frank-Starling response was studied in 15 preterm infants, less than 1500 g birth weight, and in 16 fullterm infants with patent ductus arteriosus. Left ventricular end diastolic volume (LVEDV), stroke volume, and cardiac output were calculated from biplane echocardiographic images with a modified Simpson's rule, and the left ventricular function curve was obtained by standardising with birth weight and body length. In the relationship between LVEDV and stroke volume, the slope of the regression line was significantly milder in preterm than in fullterm infants; however, there was no significant difference in the relationship between LVEDV and cardiac output. The heart rate was significantly higher in preterm than in fullterm infants. Our data indicated that the premature infants had less left ventricular reserve capacity to respond to the increased preload through the left-to-right ductal shunting than the mature ones, and that the high pulse rate made it possible to generate adequate cardiac output in premature infants.

Cardiac Output↗
PubMed1994

Does plasma immunoreactive ouabain originate from the adrenal gland?

It was reported recently that the endogenous digitalis-like factor ouabain may mainly originate from the adrenal gland. To ascertain the pathophysiological significance of endogenous ouabain and to examine if it originates in the adrenal gland, we determined plasma immunoreactive ouabain levels in patients with various cardiovascular and endocrine diseases. Plasma immunoreactive ouabain levels were also determined in the adrenal venous blood by adrenal venous sampling. Plasma immunoreactive ouabain levels were significantly increased in patients with essential hypertension, primary aldosteronism, Cushing's syndrome, pheochromocytoma, acromegaly, and chronic renal failure. Plasma immunoreactive ouabain levels were decreased in patients with primary aldosteronism after unilateral adrenalectomy, acromegaly after pituitary adenomectomy, and chronic renal failure after hemodialysis. Plasma immunoreactive ouabain levels in patients after bilateral adrenalectomy were similar to those in healthy subjects. There was no significant step-up of immunoreactive ouabain levels in the adrenal vein from the peripheral vein in three patients, whereas one patient with hypertension and right adrenal tumor but without any known adrenal hormone excess showed higher plasma immunoreactive ouabain levels in the right adrenal vein than those in the peripheral vein. These results suggest an important pathophysiological significance of endogenous ouabain in various cardiovascular and endocrine diseases. It is unlikely that the adrenal gland is a major source of plasma ouabain, although a possible excess production of ouabain by the adrenal tumor remains to be elucidated.

Adrenal Gland Neoplasms↗
PubMed1994

Acute bilateral cerebellar infarction in the territory of the medial branches of posterior inferior cerebellar arteries.

BACKGROUND: We describe the first clinicoradiological report of acute bilateral cerebellar infarction confined to the territory of the medial branches of the posterior inferior cerebellar arteries. CASE DESCRIPTION: A 65-year-old man with atrial fibrillation and hypertension had sudden onset of vertigo, followed by brief loss of consciousness. Three days later a cranial computed tomographic scan showed acute hydrocephalus and low-density areas in the cerebellar vermis on both sides. On transfer the patient showed mild dysarthria, dysequilibrium with retropulsion, symmetrical bilateral horizontal gaze-evoked nystagmus on lateral gaze, and marked gait ataxia without brain stem signs, followed by marked vertigo that was induced by motion. Cranial magnetic resonance imaging revealed abnormalities consistent with fairly symmetrical bilateral cerebellar hemorrhagic infarction that was confined to the territory of the medial branches of the posterior inferior cerebellar arteries, in addition to minimal high-intensity areas in the pons on T2-weighted images. The patient improved with conservative therapy, including intravenous administration of glycerol. CONCLUSIONS: We speculate that our patient likely had initial transient occlusion of the right vertebral artery at the origin of the right posterior inferior cerebellar artery, which probably gave rise to the bilateral medial branches of posterior inferior cerebellar arteries. This caused infarction in the territory of the medial branches on both sides without remaining brain stem signs. Such an unusual pattern of cerebellar infarction accompanied by acute hydrocephalus posed a diagnostic challenge at the time of transfer to our care, and correct diagnosis was facilitated by cranial magnetic resonance imaging.

Aged↗
PubMed1994

Stimulation of fracture repair by recombinant human basic fibroblast growth factor in normal and streptozotocin-diabetic rats.

The effect of local application of recombinant human basic fibroblast growth factor (rhbFGF) on fracture repair was examined using normal rats and streptozotocin-diabetic rats with impaired repairing ability. Immediately after fracturing the fibula, rhbFGF was applied by a single injection to the fracture site. Application of rhbFGF increased the volume and mineral content of callus in a dose-dependent manner in both normal and diabetic rats, and callus formation of diabetic rats was stimulated to levels similar to those in nontreated normal rats. The marked effect of rhbFGF on fracture repair was associated with an improvement in the mechanical properties of the healing fibula in both normal and diabetic rats. Immunohistochemical staining showed that endogenous bFGF was widely distributed in normal rats 1 and 3 weeks after fracture, especially in the soft callus and periosteum, whereas much less bFGF was detected in diabetic rats. Insulin treatment of diabetic rats restored the immunostaining for bFGF. These results demonstrate that bFGF is expressed during the early stage of fracture repair, and that the impaired fracture-repairing ability in diabetic rats is associated with reduced expression of bFGF at the fracture site. A single application of bFGF immediately after fracture not only facilitates the repair process in normal rats, but also recovers the impaired repairing ability in diabetic rats. These results suggest that local application of bFGF may facilitate bone union in patients with impaired as well as normal repairing ability.

Animals↗
PubMed1994

Probucol-induced QT prolongation and syncope.

We report a patient who experienced a reversible prolongation of the QT interval and episodes of syncope while receiving probucol. A 64-year-old woman experienced syncopal attacks 8 and 11 weeks after beginning probucol treatment (500 mg twice daily). The pre-treatment ECG showed a slight prolongation of the corrected QT interval (QTc) (0.46 sec). Her QTc increased to 0.62 sec 12 weeks after beginning probucol treatment and decreased to about the baseline value (0.48 sec) 6 weeks after treatment was discontinued. Probucol is known to prolong the QT interval. A long QT interval has been linked to an increased risk of ventricular arrhythmias, syncope or sudden death. However, clinical reports which causally relate probucol treatment to syncope are very rare. Although an ECG during the episodes of syncope was not available, this patient's syncope might be due to ventricular tachyarrhythmia associated with probucol-induced QT prolongation. This case emphasizes the need for careful evaluation of the QT interval before and during probucol treatment.

Atrial Fibrillation↗
PubMed1994

Biochemical and histochemical studies of the effects of cerebral metabolism-improving drugs on NADPH diaphorase activity in mouse brain.

The effects of cerebral metabolism-improving drugs on NADPH diaphorase activity in the mouse brain were studied, and we found that diaphorase activity in the post-mitochondrial fraction of brain homogenate was enhanced by idebenone in a concentration-dependent manner. Histochemical studies also indicated that diaphorase staining was intensified by idebenone at the same concentration. These results suggest that idebenone may stimulate the production of nitric oxide, probably through its direct action on nitric oxide synthase, thus producing its protective action on neurological disorders due to cerebral hypoxia or ischemia as a consequence of dilating the cerebral blood vessels.

Amino Acid Oxidoreductases↗
PubMed1994

Effects of flavonoid compounds on the activity of NADPH diaphorase prepared from the mouse brain.

The effects of flavonoids on NADPH diaphorase activity were studied in vitro, and we found that the enzyme activity was markedly inhibited by quercetin. This inhibitory action was shown to be accompanied by an increase in the apparent Km value of the enzyme for the cofactor NADPH, with a decrease in the Vmax, and an increase in the apparent Km for the substrate nitro blue tetrazolium, without any significant change in the Vmax. These results indicate that quercetin may directly inhibit NADPH diaphorase, thus suggesting the possibility that this compound may be able to inhibit the production of nitric oxide in the brain.

Animals↗
PubMed1994

Left ventricular contractile state of early human neonates with patent ductus arteriosus.

Using echocardiographic technique, we studied the left ventricular (LV) contractile state in 32 full-term infants within 24 hr after birth. They were divided into 2 groups based on the timing of the examinations; the group 1 (n = 17), < 3 hr after birth; the group 2 (n = 15), > 3 and < 24 hr after birth, and the additional examinations were performed on day 5. The patency of the ductus arteriosus and its internal diameter were determined by pulsed Doppler and two-dimensional echocardiography. The left atrial to aortic root ratio was obtained from M-mode echocardiography, and the LV contractile state was estimated by the relationship between heart rate-corrected velocity of circumferential fiber shortening (mVcfc) and end-systolic meridional wall stress (ESS). The ductus arteriosus was open in all cases of group 1 and in 83% of the cases of group 2, but the ductal diameter and the left atrial to aortic root ratio significantly decreased in group 2. The relationship between mVcfc and ESS showed no significant differences between 2 groups and the control. Afterload, represented as ESS, was significantly lower in group 1 than the control. We suggest that the low afterload condition helps the adequate LV contraction even under the increased preload through the left-to-right ductus arteriosus shunting after birth.

Blood Flow Velocity↗
PubMed1994

Right ventricular diastolic filling in the first day of life.

To evaluate the effects of altered preload on the Doppler flow pattern of right ventricular inflow in the first day of life, serial Doppler echocardiography of the pulmonary artery (PA) and tricuspid valve was performed in 16 normal neonates at 2, 12, and 24 hr. A computer-interfaced digitizer pad was utilized to measure the followings: PA flow velocity-time integral, total transtricuspid flow velocity-time integral, flow velocity-time integral of early diastolic filling (E area), and flow velocity-time integral of atrial contraction (A area). The PA flow velocity-time integral, total transtricuspid flow velocity-time integral, E area, A area, peak E, and peak A were increased significantly by 24 hr compared with the values at 2 hr of age. However, the peak E/A, E/A area and peak E/total transtricuspid flow velocity-time integral did not show significant changes from 2 to 24 hr. The ductus arteriosus size was inversely correlated with the peak E (r = -0.46, p < 0.05), E area (r = -0.37, P < 0.05), and A area (r = -0.34, p < 0.05). Therefore, the increase in right ventricular preload at 24 hr is considered to be due to the cessation of the left-to-right shunt through the ductus arteriosus. These results suggest that the pattern of early and late diastolic filling of the right ventricle were dependent on the increase in preload. We can therefore conclude that the redistribution of transtricuspid flow induced by the preload condition should be taken into account to interpret the transtricuspid velocity pattern in terms of diastolic function.

Blood Flow Velocity↗
PubMed1994

Hypersensitivity pneumonitis induced by inhalation of mushroom (Pholiota nameko) spores.

We describe the hypersensitivity pneumonitis of a 49-year-old woman who had been cultivating the edible mushroom 'Pholiota nameko' for three years. Her clinical manifestations and laboratory findings including transbronchial lung biopsy (TBLB) and bronchoalveolar lavage fluid (BALF) were consistent with those of other forms of hypersensitivity pneumonitis. Counter-immunoelectrophoresis determined the causative antigen to be the spores of Pholiota nameko. The indoor cultivation method appeared to play a major role in the occurrence of the hypersensitivity pneumonitis.

Alveolitis, Extrinsic Allergic↗
PubMed1994

Extra-axial ependymoma--case report.

A 13-year-old boy presented with a very unusual ependymoma extending extra-axially. Computed tomography demonstrated a tumor with a cyst and calcification adjacent to the dura and extending over the right occipital and parietal lobes. The cyst wall and solid tumor were enhanced postcontrast. Magnetic resonance imaging revealed that the solid tumor was isointense on T1-weighted images and a mixed iso- and high-intensity on T2-weighted images. The solid tumor and tissue surrounding the cyst were enhanced markedly by gadolinium-diethylenetriaminepentaacetic acid. Sagittal and coronal images demonstrated a multilocular tumor shadow. Cerebral angiography demonstrated a tumor fed by a posterior branch of the right middle meningeal artery but no feeders from the internal carotid and vertebral arteries. The tumor was removed en bloc. The histological diagnosis was clear cell-type ependymoma.

Adolescent↗