Biomedical subjects

S Yuasa

Publications and source records attributed to S Yuasa.

At least 91 records · Page 5Linked to original sources

PubMed1996

[Effect of histamine H2-receptor antagonists on the phosphorus-binding ability of phosphate binders in hemodialysis patients].

We examined the effects of histamine H2-receptor antagonists on the phosphorus binding ability of phosphate binders. Serum calcium, phosphorus, ALP, PTH and arterial blood pH and bicarbonate were measured during treatment with histamine H2-receptor antagonists accompanied by calcium carbonate in sixteen patients undergoing maintenance hemodialysis. Seven patients receiving histamine H2-receptor antagonists without calcium carbonate were selected as controls. In the sixteen patients receiving calcium carbonate, serum calcium, ALP, PTH and arterial blood pH and bicarbonate were not significantly altered during treatment with histamine H2-receptor antagonists, but serum phosphorus levels increased significantly after four (5.6 +/- 1.1 mg/dl) and eight weeks (5.9 +/- 0.8 mg/dl) of treatment as compared with that before treatment (4.8 +/- 1.2 mg/dl). Furthermore, serum phosphorus levels decreased significantly eight weeks after the discontinuation of treatment with histamine H2-receptor antagonists. In the seven control patients there were no statistical differences in serum calcium and phosphorus levels measured before and after treatment with histamine H2-receptor antagonists. In seven other patients receiving histamine H2-receptor antagonists with calcium carbonate, calcium carbonate was replaced with calcium lactate as the phosphate binder after four weeks of treatment with histamine H2-receptor antagonists. With the 4-week administration of histamine H2-receptor antagonists accompanied by calcium carbonate, the serum phosphorus level increased, similarly to that of the first study (from 6.3 +/- 0.9 to 7.1 +/- 0.5 mg/dl). However, with the substitution of calcium lactate, the serum phosphorus level decreased significantly (6.3 +/- 0.2 and 6.0 +/- 0.9 mg/dl after four and eight weeks, respectively, despite continued administration of histamine H2-receptor antagonists). These results suggest that histamine H2-receptor antagonists significantly affect the phosphorus binding ability of calcium carbonate, but not of calcium lactate. Although the exact mechanism remains obscure, one possible explanation may be related to the rise in pH of the gastric juice. Careful observation of changes in the serum phosphorus level is required in hemodialysis patients receiving calcium carbonate and histamine H2-receptor antagonists. Calcium lactate may be useful as a phosphate binder in such hemodialysis patients.

Adult↗

PubMed1995

Clinical symptoms and regional cerebral blood flow in schizophrenia.

This study examined the relationship between clinical symptoms and regional cerebral blood flow (rCBF) in schizophrenic patients using single photon emission computed tomography (SPECT). The subjects were 26 medicated schizophrenic patients diagnosed according to DSM-III-R criteria. Clinical symptoms were assessed using the Scale for the Assessment of Negative Symptoms (SANS), selected items for the Positive and Negative Syndrome Scale (PANSS), and the scale for Schneider's first rank symptoms. Resting rCBF was measured using N-isopropyl-p-[I-123] iodoamphetamine (I-123 IMP) SPECT, and relative rCBF distribution was evaluated in nine regions of interest in each hemisphere. Factor analysis of symptom ratings indicated four separate syndromes: psychomotor poverty, alienation (hallucination and disturbance of the self), delusion, and disorganization. Stepwise multiple regression analysis showed the psychomotor poverty syndrome to be correlated with decreased rCBF in bilateral superior frontal areas and increased rCBF in the left thalamus and right basal ganglia. The disorganization syndrome was correlated with increased rCBF in bilateral anterior cingulates and decreased rCBF in bilateral middle frontal areas. The alienation syndrome was shown related to increased rCBF in the right inferior frontal area and parietal area. Dysfunction in distinctive neural networks involving various prefrontal areas would thus appear to underlie these syndromes in schizophrenia.

Adult↗

PubMed1995

Asymmetry of the ventricle and age at the onset of schizophrenia.

The relationship between lateral ventricular size or its asymmetry and age at the onset of schizophrenia was investigated in 20 schizophrenic patients diagnosed according to DSM-III-R criteria. The ventricle-brain ratio (VBR) was determined using three transaxial slices of magnetic resonance image (MRI) and asymmetry of the lateral ventricle was evaluated from the laterality index of the lateral ventricular area: (left-right/left+right) x 100. Each age at the onset of the prodromal and active phase according to DSM-III-R criteria was determined for each patient. The results showed that asymmetry of the ventricle, but not VBR, was significantly correlated inversely with age at the onset of both the prodromal phase and active phase. Neither asymmetry nor VBR correlated with the duration of illness, age at MRI scanning, or severity of clinical symptoms. It would thus appear that greater asymmetry of the ventricle is associated with earlier onset of schizophrenia.

Adolescent↗

PubMed1995

Hepatocyte growth factor stimulates liver regeneration and elevates blood protein level in normal and partially hepatectomized rats.

The effects of recombinant human hepatocyte growth factor (HGF) on liver growth and function of normal and partially hepatectomized rats have been examined. HGF was continuously administered into the jugular vein because it was rapidly eliminated from the plasma (t1/2 alpha; approximately 4.5 min) and degraded. In normal rats, the labeling index of hepatocytes was increased about 6 times by the administration of HGF. HGF also decreased the prothrombin time and increased the hepaplastin and serum albumin content. In 70%-hepatectomized rats, HGF stimulated liver regeneration and increased the level of blood proteins such as hepaplastin in a dose-dependent manner. The stimulation of serum protein level seemed to result from not only the increase of hepatic cell number but also the direct effect of HGF on the protein production in hepatocytes, because HGF rapidly enhanced the protein synthesis prior to the increase of cell number and increased the mRNA content of albumin in the liver in vivo. In addition, a combination of heparin with HGF further accelerated the effects of HGF described above, possibly due to the decrease of HGF clearance. These findings suggest that HGF accelerates both the hepatic regeneration and function in vivo, and that rhHGF is clinically expected to be a potent therapeutic agent in hepatectomy and liver injury.

Albumins↗

PubMed1995

Role for Doppler ultrasound in the assessment of renal circulation: effects of dopamine and dobutamine on renal hemodynamics in humans.

To examine the utility of Doppler ultrasound in assessing renal hemodynamics, we investigated the effects of dopamine and dobutamine on renal blood flow using Doppler ultrasound technique and conventional clearance tests in 7 healthy volunteers. After visualization of arterial blood flow in the right renal hilus by two-dimensional color flow mapping, the phasic blood flow velocity in the vessel was obtained by a pulsed Doppler method. Intravenous infusion of dopamine at a low dose increased the velocity and decreased the waveform pulsatility of renal artery blood flow without causing any significant changes in blood pressure, heart rate, or cardiac index. In contrast, dobutamine infusion increased the peak systolic velocity in a dose-dependent manner, but did not increase the mean velocity or decrease the waveform pulsatility. Percent changes of renal blood flow during infusions of both agents correlated well with those of the mean velocity. Furthermore, the degrees of changes of the waveform pulsatility were consistent with those of renal vascular resistance obtained from clearance tests and blood pressure. Our results suggest that mean velocity reflects renal blood flow and the pulsatility of blood flow waveform represents renal vascular resistance. We conclude that the effects of vasoactive agents on renal blood flow and renal vascular resistance can be estimated noninvasively, directly, and repeatedly using Doppler ultrasound.

Adult↗

PubMed1995

[Developmental mechanisms of neural network in the cerebellar system].

Various cell adhesion molecules and neurotrophic factors are involved in cell migration, axonal elongation and synaptogenesis during the development of neural networks. The developmental mechanisms of neural networks were investigated in the mouse cerebellar system in relation to the neuron-glia interactions and the expression of cell adhesion molecules. Radial migration of Purkinje cells in the cerebellar primordium is guided by contact with radial glial processes, and expression of the neuron-glia cell adhesion molecule tenascin is involved in this process. Purkinje cell migration is obstructed in the reeler mutant mouse, and the disorganized arrangement of radial glial processes is considered to be responsible for this defect. Pontine nuclei and inferior olivary nuclei constitute the cerebellar afferent system, and these neurons are generated from the rhombic lip which is originated from the alar plate of the metencephalon in common with the cerebellar primordium. Pontine nuclei migrate tangentially from the rhombic lip under the pia mater, and the binding sites for peanut lectin are specifically expressed on the migratory route. Thy-1 molecule, a member of the immunoglobulin superfamily is expressed transiently in the synaptogenesis between the cerebellar afferent fibers and their target neurons in the developing cerebellar cortex. The homophilic binding activity of this molecule is considered to be involved in the recognition between presynaptic terminals and postsynaptic structures.

Animals↗

PubMed1995

Adjunctive technique for control of hemorrhage during repair of cardiac rupture.

A 66-year-old man was treated for left ventricular free wall rupture after acute myocardial infarction. The cardiac rupture was repaired with a wide patch without infarctectomy. However, bleeding from the suture line was difficult to control. Using a new technique we made a fistula between the peripatch space and the right atrium. This was very effective in stopping the bleeding. Therefore, this technique can be an option in the management of myocardial bleeding.

Aged↗

PubMed1995

[Migration, differentiation and integration of an immortalized neural cell line transplanted into the neonatal and adult mouse brain].

An immortalized neural cell line V1 was transplanted stereotaxically into the cerebellum and hippocampus of developing and adult mice, and the mode of migration, differentiation and arrangement of the grafted cells were examined by labeling the grafted cells with DiI (1, 1'-dioctadecyl-3, 3, 3', 3'-tetramethylindocarbocyanine perchlorate) and immunohistochemical staining. This cell line was established by transduction of the temperature-sensitive allele tsA58 of SV40 large T antigen oncogene into mouse hypothalamic cells. Grafted cells did not show any tumorigenicity for a long time. Some of the cells grafted into the neonatal cerebellum and hippocampus were arranged along the host cortical layer and showed neuronal or glial differentiation according to the grafted site. The cells grafted into adult cerebellum also showed migration and arrangement along the host cortical layer as well as morphological differentiation into glial cells in a manner similar to that of transplantation to the neonate. On the other hand, the cells grafted into the adult hippocampus made only clusters without forming an organized arrangement. These findings suggest that the grafted cells are integrated into the developmental processes of the host brain, and the mode of differentiation and arrangement of the grafted cells depends on the microenvironment of the different developmental stages of the host brain. The involvement of host blood vessels and astroglial framework in the migration and arrangement of the grafted cells was also suggested. Furthermore, these findings suggest the plasticity of the host brain in response to the grafted cells and the possibility of reconstructing the host brain with this multipotential neural cell line.

Animals↗

PubMed1994

Interactions between growing thalamocortical afferent axons and the neocortical primordium in normal and reeler mutant mice.

The interactions between growing thalamocortical afferent axons and the neocortical primordium were examined during neocortical development of the mouse cerebrum, by labeling the afferents with the carbocyanine fluorescent dye, DiI, which was introduced into the dorsal thalamus of the fixed brains of control and reeler mutant mice. In the neocortical primordium of the control mouse, the labeled afferents running tangentially in the intermediate zone formed a dense plexus in the subplate, the layer below the cortical plate, as early as the 16th gestational day (E16). Small numbers of the afferents invaded the lower cortical plate at E16 and increasing numbers of labeled growing axons extended into the cortical plate at E17. At the 4th postnatal day (P4), labeled afferents grew radially up to the upper cortical plate and terminal arborizations of the afferents were evident in the forming layer IV. In contrast, in the E16 cerebrum of the reeler mutant mouse, in which the cortical layers are inverted, the labeled afferents traversed the neocortical primordium directly towards the superplate, the superficial layer above the cortical plate and the equivalent of the subplate in the control mouse. Thick bundles of labeled axons reached the superplate and made contact with the superplate neurons. At P4 in the reeler neocortex, the afferent axons that had reached the superplate began to change their direction of growth and turned towards the deeper layer. Electron-microscopic observations at E16 revealed that immature synapses were formed on the somata of the subplate neurons in the control mouse, and similar immature synapses were also formed on the superplate neurons of the reeler mutant. At E16 in the control, NGF receptor immunoreactivity was expressed in the intermediate zone, subplate and lower cortical plate, and the mode of expression corresponded to the distribution of thalamocortical afferents. At the same stage of the reeler mutant, expression of NGF receptor immunoreactivity was confined to the afferent axons that had grown through the neocortical primordium towards the superplate. In the control at E17, highly polysialylated NCAM (NCAM-H), a homophilic cell adhesion molecule, was expressed in the subplate, marginal zone and afferent axons. In the reeler mutant at the same stage, this adhesion molecule was expressed in both the superplate and the bundles of the afferent axons. These findings suggest that the subplate and the superplate, which are composed of neurons generated at the earliest stage, attract growing thalamocortical afferent axons specifically by a chemotropic mechanism through the expression of NGF receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1994

Preclinical evaluation of MKC-442, a highly potent and specific inhibitor of human immunodeficiency virus type 1 in vitro.

MKC-442 (6-benzyl-1-ethoxymethyl-5-isopropyluracil or I-EBU) has recently been identified as a highly potent and specific inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. Since the compound has favorable pharmacokinetic and toxicity profiles in vivo, we have evaluated MKC-442 for its inhibitory effect on the replication of HIV-1 in various cell cultures, including human peripheral blood lymphocytes and monocyte-macrophages. The 50 and 90% effective concentrations for HIV-1 (HTLV-IIIB strain) replication in MT-4 cells were 15 and 98 nM, respectively. MKC-442 was also inhibitory to HIV-1 replication in peripheral blood lymphocytes and monocyte-macrophages as determined by the production of p24 antigens in the culture supernatant. Fluorescence-activated cell sorter analysis revealed that MKC-442 was equally active against zidovudine-resistant mutants and zidovudine-susceptible strains. Furthermore, combinations of MKC-442 with either 3'-azido-3'-deoxythymidine, 2',3'-dideoxycytidine, or 2',3'-dideoxyinosine synergistically inhibited the replication of HIV-1. Thus, MKC-442 has been considered as a candidate for clinical efficacy studies.

Antiviral Agents↗

PubMed1994

[Determinants of homologous blood utilization in addition to autologous blood transfusion--a multivariate study].

Since April 1989, we have been using autologous blood donation in order to avoid homologous blood transfusion as much as possible. To determine the factors which influence the necessity for homologous blood transfusion as well as autologous blood donation. Of them 77.6% (group 1) required autologous blood only, but others needed homologous blood transfusion as well as autologous blood. Using an invert analysis, preoperative factors that showed significant differences were age, body weight, number of autologous blood donations, amount of donated autologous blood, preoperative Hb and Ht. Among operative factors, aortic cross clamping time, cardiopulmonary bypass time, amount of concentrated blood from CPB circuit, amount of transfused autologous blood and amount of drainage demonstrated significant differences between groups. Univariately significant factors were studied by multivariate discriminant analysis. Total amount of drainage proved to be the best contributor of non-homologous blood transfusion surgery, followed by preoperative Hb, body weight, amount of concentrated blood from CPB circuit and amount of donated autologous blood in order of contribution Understanding these factors, homologous blood transfusion requirement may be greatly reduced. This is thought to be the largest series of autologous blood donation in Japan.

Analysis of Variance↗

PubMed1994

[A case of ACTH-releasing lung carcinoid tumor presenting Cushing's syndrome].

The patient was a 47-year-old female who had undergone hypophysectomy due to Cushing's syndrome when 46 years old. In April 1992, about 1 month after the operation, chest CT-scan revealed a lesion of 8 x 8 mm in size in the right upper lobe. A high value of serum ACTH was obtained from the A3b wedge blood by cardiac catheterization. She was operated on suspicion of ACTH releasing lung tumor. During the operation, it was histologically diagnosed as lung carcinoid by a frozen section of the lesion. In addition, ACTH of the blood obtained from the right superior pulmonary vein was as high as 37,300 pg/ml, but that in the right main pulmonary artery or the radial artery was 850-970 pg/ml. Right upper lobectomy with dissection of mediastinal lymph nodes was so performed. Post-operative value of serum ACTH was significantly decreased. She was in good course, and is still asymptomatic 8 months after the operation.

Adrenocorticotropic Hormone↗

PubMed1994

[Right ventricular function after aorto-coronary bypass surgery: with relation to the site of right coronary artery occlusion].

Postoperative right ventricular function was evaluated serially by thermodilution techniques (REF-1, Edwards Laboratories) in patients who underwent aorto-coronary bypass surgery with uneventful postoperative recovery. The patients were divided into three groups depending on the location of critical stenosis of the right coronary artery. The stenosis was proximal to the right ventricular branch in group I (n = 13), distal to the right ventricular branch but proximal to the acute marginal branch in group II (n = 13) and distal to the acute marginal branch in group III (n = 11). Control (n = 20) consisted of the patients with no significant stenosis of the right coronary artery. Cardiac index, intracardiac pressures and amount of cathecolamin used during postoperative course showed no significant differences among the groups including control. With the use of cathecolamine after surgery, right ventricular ejection fraction (RVEF) rose and right ventricular volumes (RVEDV and RVESV) decreased in all the groups except for group I. These values in group I were unchanged. Thus, there were significant differences in RVEF, RVEDV and RVESV between group I and control. These results mean that right ventricular dysfunction may remain even long after occlusion of the proximal right coronary artery.

Aged↗

PubMed1994

[Effect of low calcium diet on blood pressure and pressure natriuresis response in rats: role of the renin-angiotensin system].

Dietary Ca is an important modulator of arterial blood pressure in humans and rats. Since the kidney plays a key role in the pathogenesis of hypertension, the effect of a low Ca diet (0.01%Ca) on blood pressure and pressure natriuresis response was studied in Sprague-Dawley rats. In addition, a possible role of the renin-angiotensin system in the development of hypertension and an altered pressure natriuresis response resulting from low dietary Ca intake was investigated. In the low Ca diet group, systolic blood pressure determined by the tail-cuff method was significantly higher than in the normal Ca diet group (1.1%Ca) 1 week after the diet (113.0 +/- 7.1 vs. 105.0 +/- 9.5 mmHg, p < 0.05). Furthermore, low dietary Ca treatment significantly inhibited the water and sodium excretory responses to acute elevation of renal perfusion pressure. Treatment with an inhibitor of angiotensin converting enzyme, captopril (30 mg/kg/day), attenuated both the development of hypertension and the reduced pressure natriuresis response observed in Ca-deficient rats. Although plasma renin activity was not different between the low and normal Ca diet groups after the 2-week dietary regimen, the pressor response to angiotensin II injection was significantly greater in the low Ca diet group. These results indicate a possible involvement of the renin-angiotensin system in the development of hypertension and the inhibitory effects of the pressure natriuresis response caused by low dietary Ca intake, via enhanced sensitivity to angiotensin II.

Animals↗

PubMed1994

[Coronary artery bypass grafting in the patients with previous cerebral infarction: the risk of perioperative cerebral complications].

From Oct. 1987 to Apr. 1992, coronary artery bypass grafting (CABG) was performed in 33 patients who had a history of previous cerebral infarction. Two patients associated with severe carotid disease underwent combined carotid endarterectomy and CABG. There have been no perioperative cerebral complications. On the other hand, in 199 patients without a history of previous cerebral infarction, three patients (1.5%) suffered perioperative cerebral infarction. In two of these patients, the etiology was felt to be calcific and atherosclerotic debris from the ascending aorta and in the remaining patient, to be arterial hypotension during cardiopulmonary bypass. In conclusion, no direct relationship has been found between previous cerebral infarction and incidence of perioperative cerebral complications.

Aged↗

PubMed1994

[Role of endothelium-derived nitric oxide in mediating the natriuretic response to acute extracellular volume expansion].

To determine the role of endothelium-derived nitric oxide (EDNO) in mediating the natriuretic response to acute extracellular volume expansion (ECVE) with isotonic saline (3% of body weight per hour), the diuretic and natriuretic responses to ECVE were studied in anesthetized Sprague-Dawley rats during the intravenous infusion of an EDNO synthesis inhibitor, NW-nitro-L-arginine methyl ester (L-NAME). Intravenous infusion of L-NAME at the dose of 5 micrograms/kg/min significantly inhibited the diuresis and natriuresis in response to ECVE by 58% and 67%, without altering arterial pressure, effective renal plasma flow, glomerular filtration rate and basal excretory function. This inhibitory effect of L-NAME on the diuretic and natriuretic responses to ECVE was attenuated by the infusion of the EDNO synthesis precursor, L-arginine (1mg/kg/min), but not by D-arginine. In addition, pretreatment with 0.3 mg/kg of the angiotensin II receptor antagonist, L-158,809, normalized the diuretic and natriuretic responses to ECVE in L-NAME-treated rats, suggesting an angiotensin-II-dependency of the reduced renal excretory response to ECVE during EDNO synthesis inhibition. Neither L-arginine nor L-158,809 alone significantly altered the renal excretory response to ECVE compared with vehicle-treated control rats. These results suggest that EDNO might play an important role in the regulation of sodium and water excretion during ECVE, and indicate a possible interaction between EDNO and angiotensin II on the renal excretory function.

Angiotensin II↗

PubMed1994

[Assessment of the distribution of renal cortical blood flow by contrast ultrasonography].

The importance of the distribution of intrarenal blood flow in the regulation of various renal functions, such as urine concentration and sodium excretion, has been well recognized. However, there have been no reliable methods to measure local flow in the kidney in vivo. The present study demonstrated the usefulness of contrast ultrasonography combined with injection of sonicated 5% albumin for assessment of the distribution of renal cortical blood flow in eleven mongrel dogs. The left kidney was displayed by tomographic echography, and microbubbles of sonicated albumin were injected into the abdominal aorta above the left renal artery. Video density time curves were generated and fitted to a time-intensity curve. Intrarenal infusion of acetylcholine (4.0 micrograms/kg/min) increased renal blood flow (RBF) from 2.5 +/- 0.3 to 4.6 +/- 1.0 ml/min/g kwt (p < 0.01), and norepinephrine (0.5 microgram/kg/min) decreased RBF from 2.5 +/- 0.3 to 1.2 +/- 0.5 ml/min/g kwt (p < 0.01). There were significant positive correlations between percent change in RBF and peak intensity and area under the curve, which were calculated with a time-intensity curve. Furthermore, the inner/outer renal cortex ratio of peak intensity significantly increased during acetylcholine infusion (0.72 +/- 0.11 vs 0.86 +/- 0.09; p < 0.01), whereas no significant change was observed during norepinephrine infusion. These results suggest that renal contrast ultrasonography may be useful for real-time assessment of the distribution of renal cortical blood flow in vivo.

Acetylcholine↗

PubMed1993

Expression of three nonallelic genes coding calmodulin exhibits similar localization on the central nervous system of adult rats.

By Northern blot analysis with the digoxigenin-labeled antisense RNA probes of the noncoding regions, the transcripts of three calmodulin (CaM) genes, CaMI, CaMII, and CaMIII, were separately detected in 12 different tissues of adult Wistar albino rats, without any cross-hybridization. The mRNAs of all three CaM genes were abundant in the central nervous system (CNS) as well as in the testis, although ubiquitous expression was detected at low levels in the other tissues. There were subtle but significant differences in the tissue-specific distribution of the three CaM gene RNAs. By in situ hybridization, strong hybridization of the three CaM gene probes was observed in common in large projection neurons of the CNS: the hippocampal pyramidal cells, the cerebellar Purkinje cells, and the large neurons of the cerebral neocortex, the pyriform cortex, the mesencephalon, the pons, and the spinal cord. The expression of the three CaM genes was at lower levels in small interneurons of the CNS. These profiles of expression were almost the same among the three CaM genes. Thus, all three CaM genes were coordinately expressed in neurons of the adult rat CNS. Certain regulatory mechanisms of the three CaM genes seemed to mediate similar tissue- and cell type-specific expression in the CNS.

Animals↗