Biomedical subjects

R Tanaka

Publications and source records attributed to R Tanaka.

At least 469 records · Page 26Linked to original sources

PubMed1992

[Studies on the effect of combination of amphotericin B and flucytosine on Candida albicans by flow cytometry].

The antifungal effects of amphotericin B (AMPH) and flucytosine (5-FC) on three strains of Candida albicans were studied by flow cytometry (FCM). When the IFM4954 and IFM4949 were treated with AMPH or 5-FC alone, cytograms of cell distribution changed at the concentration of 1/2 MIC, respectively. Next, the effect of combination of AMPH and 5-FC were examined. Cytogram of cell distribution of IFM4954 and IFM4949 changed under the combination of 1/4 MIC of AMPH and 1/4 MIC of 5-FC, namely a synergic effect was observed. In conclusion, FCM is a useful apparatus for analysis of the effect of antifungal agents.

Amphotericin B↗

PubMed1992

Species-specific oligonucleotide probes for five Bifidobacterium species detected in human intestinal microflora.

Portions of the 16S rRNA from closely related species of the genus Bifidobacterium that are found in the human intestinal microflora were sequenced in order to design species-specific oligonucleotide probes. Five oligonucleotide probes ranging from 16 to 19 bases in length and complementary to 16S rRNA sequences from Bifidobacterium adolescentis, B. bifidum, B. breve, B. infantis, and B. longum were synthesized. With crude high-molecular-weight RNA preparations as targets, these probes showed the desired species specificity, even down to a 1-nucleotide difference. For the practical evaluation of these probes, their specificity and sensitivity were tested against seven strains of the same species and 54 strains of heterologous bacteria with fixed whole cells as targets. The probes for B. adolescentis, B. breve, and B. longum showed efficient and specific hybridization. Although the probes for B. bifidum and B. infantis cross-reacted with a few bacterial strains not isolated from humans, these probes showed species specificity for human intestinal bacteria. These 16S rRNA probes should prove valuable for the identification and detection of human intestinal Bifidobacterium species.

Base Sequence↗

PubMed1992

Left ventricular hypertrophy due to volume overload versus pressure overload.

Left ventricular hemodynamic overload produces an increase in stroke work (SW), which is compensated by the development of left ventricular hypertrophy. However, recent reports question the adequacy of this compensation in mitral regurgitation (MR). Accordingly, we examined the adequacy of compensatory hypertrophy in chronic experimental MR. Six dogs with chronic severe MR were matched according to SW with six dogs that had severe chronic aortic stenosis (ASSW). SW in the two groups was increased identically (40%) compared with normals. However, the hypertrophic response was much greater in the AS group [left ventricular wt (g) to body wt (kg) ratio (LVBW) 4.0 +/- 0.2 normals, 5.0 +/- 0.2 MR, and 7.5 +/- 0.2 ASSW; P < 0.05 MR vs. ASSW]. This differing hypertrophic response increased normalized SW, the area within the stress-volume loop, in MR (90 +/- 5 g) vs. 63 +/- 5 g in ASSW (P < 0.05). Thus in MR, each unit of myocardium had to perform more work than in AS. In a separate comparison, four different dogs with AS (ASHy), which had a similar amount of hypertrophy to the MR dogs (LVBW) (5.0 +/- 0.2 MR, 5.2 +/- 0.2 ASHy) were studied. SW was greater in the MR group, suggesting more SW overload was required to produce similar amounts of hypertrophy in MR vs. AS. Contractile function was depressed in the MR group but not in the AS. These findings indicate that the hypertrophic response to a similar SW demand is less in MR than AS, a response associated with contractile dysfunction in the MR group.

Animals↗

PubMed1992

Ontogeny of integumental calcium in relation to surface area and skin water content in the perinatal rat.

Calcium is an important regulator of epidermal differentiation and skin biomechanics in many vertebrate species. In this study, we measured total epidermal calcium in the perinatal Sprague-Dawley rat. Values ranged from 12 to 15 mg per 100 g of tissue. These levels were elevated compared with dermis and other soft (nonbone) organs, including brain, kidney, heart, and liver. Administration of radioactive calcium to the pregnant rat resulted in high rates of 45Ca2+ localization in the fetal epidermis 24 h later. From gestational day 20 to postnatal day 3, the epidermis showed progressive dehydration with water content decreasing from 79 to 73%. Dermal hydration over the same period decreased from 91 to 81%. In the neonatal rat (age 0-3 days), linear regression analysis of surface area vs. body weight on a log-log plot yielded a slope of 1.04. This finding contrasts with an expected slope of 0.67 based on simple surface area-to-volume relationships and differs from the empirical 0.75-power law observed in adult bioenergetics. In summary, these results show the perinatal rat is encapsulated by a continuous differentially hydrated calcium-rich epidermal envelope that increases in surface area over the early postnatal period directly as the first power of body mass.

Animals↗

PubMed1992

Infusion of peripheral blood mononuclear cell products from nephrotic children increases albuminuria in rats.

Supernatants of peripheral blood mononuclear cell culture from children with minimal change nephrotic syndrome (MCNS) and focal segmental glomerulosclerosis (FSGS) were tested for their ability to increase glomerular basement membrane (GBM) permeability and for effects on anionic sites in the GBM. Supernatants from cultures of concanavalin A-stimulated peripheral blood mononuclear cells from patients with MCNS, those with FSGS and normal controls were infused into the renal arteries of normal rats. Infusion of the supernatants from patients with MCNS and FSGS caused a significant reduction of anionic sites in the GBM (p less than 0.001) and a significant increase in urinary albumin excretion (p less than 0.05), whereas infusion of supernatants in control cases did not reduce anionic sites nor increase urinary albumin excretion. These findings show that stimulation of peripheral blood mononuclear cells from MCNS and FSGS with concanavalin A results in liberation of soluble substances which reduce polyanions in the GBM and increases GBM permeability.

Albuminuria↗

PubMed1992

Changes in myocardial blood flow during development of and recovery from tachycardia-induced cardiomyopathy.

BACKGROUND: Chronic supraventricular tachycardia (SVT) causes a dilated cardiomyopathy and myocyte injury. Termination of SVT improves left ventricular (LV) function but is associated with LV hypertrophy. Changes in myocardial blood flow (MBF) that may accompany the development of and recovery from SVT cardiomyopathy might have a significant effect on LV function and myocyte structure. The goal of this study was to relate changes in LV function, myocyte composition, and coronary vascular structure to changes in MBF with the development and recovery of SVT cardiomyopathy. METHODS AND RESULTS: LV function and MBF were measured in three groups of conscious pigs: sham control (control; n = 8), after 3 weeks of atrial pacing (SVT, 240 beats per minute; n = 8), and after a 4-week recovery from SVT (post-SVT; n = 8) by echocardiography catheterization and microspheres. Measurements were made under three states: 1) at rest with a basal heart rate, 2) rapid atrial pacing (240 beats per minute), and 3) during adenosine infusion (1.5 mumol/l.kg-1.min-1) without pacing. LV myocyte, capillary, and arteriole morphometric studies were performed in five additional pigs from each group using histochemistry and electron microscopy. LV fractional shortening was lower and left atrial pressure was significantly higher in the SVT group compared with control at rest, during pacing, and with adenosine (p less than 0.05). In the post-SVT group, fractional shortening returned to control values at rest and with adenosine, but fell from control values with pacing (p less than 0.05). Left atrial pressure fell in the post-SVT but remained significantly higher than control (p less than 0.05). LV/body weight ratio was significantly increased in the post-SVT group (p less than 0.05). In all states, SVT LVMBF was significantly reduced from control values (rest, 0.8 +/- 0.3 versus 1.6 +/- 0.3 ml-min-1.g-1; pacing, 1.2 +/- 0.2 versus 3.1 +/- 0.3 ml.min-1.g-1; adenosine, 1.4 +/- 0.3 versus 4.4 +/- 0.4 ml.min-1.g-1, respectively, p less than 0.05). In the post-SVT group, LVMBF was similar to control at rest (1.3 +/- 0.2 ml.min-1.g-1) but was significantly lower than control with pacing and adenosine (2.0 +/- 0.4 and 2.5 +/- 0.5 ml.min-1.g-1, respectively, p less than 0.05). Myofibrillar content fell significantly with SVT compared with control (42 +/- 5 versus 61 +/- 3%, p less than 0.05) and returned to control values in the post-SVT group (64 +/- 3%). Capillary density remained unchanged in the SVT and post-SVT groups, but capillary luminal diameter decreased and arteriole diameter increased in the SVT group (p less than 0.05). CONCLUSIONS: The LV dysfunction and myocyte injury with SVT cardiomyopathy were associated with reduced MBF. Early recovery from SVT cardiomyopathy resulted in hypertrophy with normal MBF at rest, but significantly reduced coronary reserve.

Adenosine↗

PubMed1992

Relation between ventricular and myocyte function with tachycardia-induced cardiomyopathy.

Chronic supraventricular tachycardia (SVT) causes left ventricular (LV) dilatation and dysfunction. Changes in myocyte function and structure may be important factors in the development of SVT cardiomyopathy. Accordingly, LV function and isolated myocyte structure and function were examined in six pigs with pacing-induced SVT cardiomyopathy (3 weeks at 240 beats per minute) and six control pigs. LV function was examined by simultaneous echocardiography and catheterization, and isolated myocyte function was studied using computer-assisted video microscopy. Indexes of isolated myocyte contractile performance were examined in the unloaded, unattached state (31 control and 24 SVT cells) and after attachment to a basement membrane substrate (65 control and 45 SVT cells). LV fractional shortening and peak +dP/dt significantly decreased in SVT cells compared with control cells (12 +/- 2% versus 28 +/- 2%, and 842 +/- 61 versus 1,216 +/- 119 mm Hg/sec, respectively; p less than 0.05). Isolated myocyte percent shortening and normalized peak velocity of shortening of SVT myocytes adherent to a basement membrane were significantly lower than attached control myocytes (1.2 +/- 0.2% versus 4.3 +/- 0.3%, and 15 +/- 2 versus 37 +/- 5% resting cell length/sec, respectively; p less than 0.05). Similarly, in the unattached state, the extent and velocity of shortening of SVT myocytes were reduced by over 50% from control values. Contractile properties of attached and unattached cardiocytes were also examined in the presence of 2-8 mM extracellular Ca2+. For both attached and unattached SVT myocytes, responsiveness to increases in extracellular Ca2+ were significantly blunted from control values. Ultrastructural examination of SVT myocytes revealed that the percent volume of myofibrils within isolated myocytes was reduced from control values (46 +/- 7% versus 65 +/- 2%, p less than 0.05). In summary, SVT cardiomyopathy is probably due to a primary defect in isolated myocyte contractile performance. The reduced contractile function of SVT cardiomyopathic myocytes was associated with abnormalities in cytoarchitecture and Ca2+ responsiveness.

Animals↗

PubMed1992

Pyridoxine-dependent seizures: report of a case with atypical clinical features and abnormal MRI scans.

A Japanese girl with atypical pyridoxine-dependent seizures is reported. Until 9 months of age the seizures had been controlled by conventional anticonvulsants. The initial administration of pyridoxine was followed by a collapse; the suppression-burst pattern changed to an almost flat pattern in the EEG. T1- and T2-weighted magnetic resonance imaging (MRI) scans showed poor differentiation between white and gray matter, and T2-weighted MRI scans showed periventricular hyperintensity areas adjacent to the posterior horns of lateral ventricles. The findings in this patient indicate that pyridoxine should be given to infants with intractable epilepsy, regardless of the response to anticonvulsants, and that resuscitation facilities should be available during such a trial.

Brain↗

PubMed1992

Cerebral arteriovenous malformations associated with a straight sinus anomaly.

Nine cerebral arteriovenous malformations (AVM) associated with straight sinus anomaly were demonstrated on angiograms. All 10 AVM (1 patient had two AVM) occupied deep cerebral structures: Seven were totally or partially located in the basal ganglia or the corpus callosum, and 3 were in the medial occipital or temporal lobe. In 6 patients, almost no filling of the straight sinus was observed, although the AVM were located deeply and the main drainage was via the vein of Galen. All 6 patients showed retrograde flow in the deep cerebral veins or venous drainage through a persistent facial sinus. The other 3 patients had duplication or septal formation of the straight sinus. Straight sinus anomaly is extremely rare in the normal population but seems not uncommon in patients with deep-seated AVM.

Adolescent↗

PubMed1992

Bilateral homonymous hemianopsia due to tentorial herniation, with sparing of central vision: case report.

Cases of complete bilateral homonymous hemianopsia with sparing of central vision that are caused by bilateral tentorial herniation are extremely rare. We describe one such case resulting from severe head trauma, the first to be reported in which magnetic resonance images showed clear evidence of the responsible lesion. The causes of bilateral homonymous hemianopsia with sparing of central vision and the possible mechanisms whereby macular sparing may arise are discussed.

Adolescent↗

PubMed1992

Characterization of thyroidal membrane-bound Mg-adenosinetriphosphatase activated by trypsin or poly-L-lysine.

The Mg-adenosinetriphosphatase (ATPase) in the thyroidal NaI-treated microsome fraction was activated by treatment with basic polyamino acids or trypsin, but not with acidic polyamino acids and basic proteins such as lysozyme and ribonuclease. The enzyme kinetics showed that the activation of trypsin or poly-L-lysine was due to an increase in the maximal velocity of the hydrolyzing reaction without a change in the affinity of the enzyme for its substrate. A break at about 25 degrees C was observed in the Arrhenius plots of Mg-ATPase in the trypsin- or poly-L-lysine treated preparations, but there was no break in the control preparation. These results suggest that the activating effect of trypsin or poly-L-lysine on Mg-ATPase activity in the thyroidal NaI-treated microsome fraction is related to the lipid environment surrounding the enzyme molecule in the thyroid cell membrane.

Animals↗

PubMed1992

The effects of valvular regurgitation on thermodilution ejection fraction measurements.

Through the use of thermodilution principles and rapid response thermistors, it is now possible to measure right ventricular ejection fractions serially in patients. However, to our knowledge, the extent to which tricuspid regurgitation affects the accuracy of thermodilution ejection fraction measurements has not been quantified. The purpose of this study was to compare actual and thermodilution ejection fraction measurements in an in vitro model of tricuspid regurgitation over a wide range of ejection fractions. Stepwise perforation of the inlet valve resulted in regurgitant fractions ranging from 4 to 40 percent. At each increment of inlet valve regurgitation, triplicate sets of thermodilution (EFthermo) ejection fraction measurements were obtained and compared with actual ejection fractions (EFactual). The mean difference between EFactual and EFthermo significantly increased with 8 percent regurgitation and significantly increased with greater increments of inlet valve regurgitation. EFthermo consistently underestimated EFactual over the entire range of regurgitant values. Linear regression analysis revealed a significant correlation between EFactual and EFthermo for all degrees of regurgitation; however, the correlation coefficient significantly declined from control valves with 13 percent regurgitation and declined further with 33 percent regurgitation. Qualitative classification of the inlet valve regurgitation into mild, moderate, and severe regurgitation was performed using pulsed Doppler echocardiography. Mild inlet valve regurgitation resulted in a significantly increased difference between EFactual and EFthermo from control values. A significant increase in the difference between EFactual and EFthermo was observed with both moderate and severe regurgitation. In summary, thermodilution underestimated actual ejection fraction in a direct linear relationship to the degree of inlet valve regurgitation. Thus, in the presence of tricuspid regurgitation, this method may still be useful in serially measuring changes in right ventricular ejection fraction.

Cardiac Output↗

PubMed1992

Adult T-cell leukemia with a solitary lung mass.

A 49-year-old woman was admitted to the hospital with supraclavicular lymph node swelling. On a chest x-ray film, a 4 x 4-cm nodular shadow was observed in the right middle lung field. The white blood cell count was 10,100/cu mm, showing 44 percent abnormal lymphocytes with lobulated nuclei. Since HTLV-I antibodies were markedly positive, she was diagnosed as having ATL. Transbronchial tumor biopsy revealed accumulation of ATL cells. Our patient is the first case with only a large nodular accumulation of ATL cells without diffuse infiltration of the cells in the lung.

Female↗

PubMed1992

PTA of supra-aortic arteries with temporary balloon occlusion to avoid distal embolism.

Percutaneous transluminal angioplasty (PTA) was carried out in eight patients with cervical arterial stenosis; six in the subclavian and brachiocephalic arteries (5 with subclavian steal syndrome), one in the common carotid artery, and one in both the brachiocephalic and common carotid arteries (with subclavian steal syndrome). The PTA balloon catheters were introduced via the femoral artery in seven and brachial artery in one. To prevent distal embolization through the vertebral and internal carotid arteries, the blood flow in these vessels was temporarily occluded with a balloon catheter. The dilation of the stenotic areas was generally satisfactory. Antegrade blood flow was promptly obtained in the vertebral artery even in patients with subclavian steal syndrome. In all patients, the clinical symptoms improved. Two patients underwent repeat PTA because of restenosis.

Adult↗

PubMed1992

Choroid plexus arteriovenous malformations.

Among 24 arteriovenous malformations (AVMs) involving the choroid plexus, 11 were plexal type AVMs predominantly located in the choroid plexus of the lateral ventricle, and 13 were parenchymal type AVMs mainly situated in the paraventricular cerebral parenchyma. 83% of all AVMs involved both the choroid plexus and the paraventricular cerebral parenchyma. Most cases presented with intracranial hemorrhage, particularly intraventricular hemorrhage. The most serious surgical problem was a small residual nidus unrecognized at the initial operation causing postoperative hemorrhage. Five parenchymal type AVMs presented residual niduses in the choroid plexus, causing death in two cases. Two plexal type AVMs resulted in residual AVMs supplied by the cisternal segment of the anterior choroidal artery, situated in the medial temporal lobe. To prevent postoperative hemorrhage from a small residual nidus, immediate postoperative angiography while the patient is still under general anesthesia should be performed to identify any residual nidus.

Adolescent↗

PubMed1992

Acute subdural hematoma in young patient with moyamoya disease--case report.

A 17-year-old boy with known moyamoya disease developed an acute subdural hematoma after a mild head trauma. He had been confined to a wheelchair with contracture in the upper and lower extremities due to juvenile rheumatoid arthritis since age 1 year. He had undergone encephalo-duro-arterio-synangiosis (EDAS) on the right and encephalo-myo-synangiosis (EMS) on the left at 13 years of age. He was admitted with headache, nausea, and vomiting after a fall from his wheelchair at age 17. Computed tomography on admission showed a large acute subdural hematoma in the right fronto-temporal region but no bleeding at the EDAS or EMS sites. Cerebral angiography 12 weeks after the head trauma revealed a remarkable reduction in the spontaneous transdural external-internal carotid anastomoses in the right frontal region. The acute subdural hematoma was probably caused by rupture of the spontaneous transdural anastomoses.

Acute Disease↗

PubMed1992

Prognosis of primary malignant lymphoma of the central nervous system--a retrospective study of 32 cases.

A retrospective analysis of 32 patients with primary malignant lymphoma of the central nervous system (CNS) diagnosed between 1976 and 1989 investigated treatment results and recurrence patterns. All patients showed either complete or partial regression of the tumor after initial treatment, mainly radiation therapy with adjuvant chemotherapy. The mean dose of whole-brain irradiation was 40.9 Gy and that of booster was 14.4 Gy. Most patients had tumor recurrence. The median time to recurrence from completion of the treatment was 5 months. The 1- and 5-year survival rates were 50.0 and 17.7%, respectively, and the overall median survival time was 11 months. Most tumors had multiple recurrences at the primary site and other regions of the CNS, and tended to recur in the periventricular region and the cerebrospinal fluid space. Spinal metastasis occurred in five cases. The importance of good control of the primary lesion and active maintenance therapy for the whole CNS is emphasized.

Adult↗

PubMed1992

Temporal lobe tumor demonstrating ganglioglioma and pleomorphic xanthoastrocytoma components. Case report.

The case is reported of a 16-year-old boy with a left temporal lobe tumor composed of a ganglioglioma and a pleomorphic xanthoastrocytoma. Histologically, the tumor had two different components. One component involved the cortex of the left posterior temporal lobe and showed an aggregation of neuronal cells with an astroglial stroma. Ultrastructurally, numerous dense-cored vesicles, diagnosed as ganglioglioma, were found in the neuronal cells. The other component involved the adjacent cortex and white matter of the left anterior temporal lobe and the surrounding subarachnoid space. This was composed of pleomorphic cells with many multinucleated giant cells and occasional foamy cells. Most of the tumor cells were positive for glial fibrillary acidic protein. These features correspond well to earlier descriptions of pleomorphic xanthoastrocytoma. At 24 months following total tumor extirpation, the patient is alive and has had no evidence of tumor recurrence.

Adolescent↗