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Biomedical subjects

Y Sakurai

Publications and source records attributed to Y Sakurai.

At least 325 records · Page 18Linked to original sources
PubMed1994

[A case report of emergency surgery for ruptured thoracic aortic aneurysm into the right thoracic cavity].

Rupture of aneurysm of descending thoracic aorta into the right thoracic cavity is an uncommon manifestation and, therefore, carries a high mortality rate. Sixty seven-year-old female was referred to our hospital due to ruptured aneurysm of descending thoracic aorta into the right thoracic cavity. Emergency operation was performed to replace the ruptured descending thoracic aorta through a left thoracotomy and to remove huge hematoma in the right thoracic cavity through a right thoracotomy. Post-operative chest radiograph showed well-expanded right lung which appears to prevent a serious respiratory complication. The patient recovered uneventfully after seven days of respiratory support.

Aged↗
PubMed1994

[A case of intracranial osteochondroma originating with psychomotor epilepsy].

A 28-year-old woman was admitted to our clinic due to psychomotor epilepsy. Craniogram, CT scan demonstrated a calcified lesion in the frontal, parasagittal region. MR proton images showed a mixed hyper-and hypodense lesion. The tumor originated from the frontal bone and was totally removed using airdrill safely. Histological findings revealed osteochondroma originating in the frontal bone is rare, and diagnostic procedures and surgical management of this tumor are discussed.

Adult↗
PubMed1994

Involvement of auditory cortical and hippocampal neurons in auditory working memory and reference memory in the rat.

The goal of the present study was to see whether one neuron is involved exclusively in one type of memory or in different types of memory. Single-unit activity was recorded from rat hippocampal CA1, CA3, dentate gyrus, and auditory cortex (AC) during performances of auditory working memory (WM) and reference memory (RM) tasks. Both the memory tasks employed identical apparatus and stimuli and differed only in the type of memory required for correct performance. Around 10% and 43% of the units from the four brain regions showed sensory correlates (differences in activity due to the type of sensory stimulus) only in the WM or RM task, respectively. Only the AC had units showing different kinds of sensory correlates between the WM and RM tasks. About 30% of the units from the four regions had sensory-retention correlates (sustained differential activity during the delay) only in the RM task, whereas the AC had units with sensory-retention correlates only in the WM task or in both the WM and RM tasks. Approximately 35% of the units from the hippocampal regions showed motor correlates (increments of activity immediately prior to responses) only in the WM task. Another 30% of the hippocampal units showed such correlates both in the WM and RM tasks. About 22% of the hippocampal CA1 and CA3 units showed comparison-motor correlates (increases of activity prior to correct responses) only in the WM task. These results indicate that some neurons are involved solely in WM or RM, whereas other neurons are involved in both WM and RM. The results also suggest that more neurons are involved in sensory and retention processing for RM than for WM, and that the AC alone has flexible neurons involved in the processes for both types of memory. More hippocampal neurons are involved in the motor and comparison processes for WM than for RM.

Acoustic Stimulation↗
PubMed1993

Boronate-containing polymer as novel mitogen for lymphocytes.

A novel water-soluble polymer (poly(AAm-co-PBA)) was synthesized by radical copolymerization of 3-acrylamidophenylboronic acid with acrylamide and evaluated as synthetic mitogen of lymphocytes. Boronic acid was introduced in the polymer as recognition site of sugar residues existing on the plasma membrane surface of lymphocyte, since it makes a covalent bonding with polyol compounds including sugars. Obvious increase in [3H]thymidine incorporation of lymphocytes was observed when murine spleen lymphocytes were cultured with poly(AAm-co-PBA), while little proliferative response of lymphocytes was observed in the presence of the homopolymer of acrylamide, the polymer without boronic acid moiety. This suggests that proliferation of lymphocytes was induced through the binding of phenylboronic acid moiety in poly(AAm-co-PBA) with glycoproteins existing on the plasma membrane surface of lymphocytes. Further, poly(AAm-co-PBA) was found to induce even the proliferation of B cell-depleted population of lymphocytes, suggesting T cell stimulation by this boronate-containing polymer.

Acrylic Resins↗
PubMed1993

Dependence of functional synaptic connections of hippocampal and neocortical neurons on types of memory.

Different types of memory are thought to be processed by different neuronal networks. The present study evaluated the functional synaptic connections among neurons by means of cross-correlation analysis when two types of memory, working and reference memory, were being processed in behaving rats. Some of the synaptic connections of neurons in the hippocampal CA1, CA3, dentate gyrus and auditory cortex functioned when the rat was performing only one of the memory tasks. Working memory needed more of these memory-type dependent synapses in the hippocampal regions than reference memory.

Animals↗
PubMed1993

Isolation and characterization of a novel serine proteinase complexed with alpha 2-macroglobulin from porcine gastric mucosa.

Porcine stomach mucosa was found to contain a 740-kDa protein having endopeptidase activity toward peptide 4-methylcoumaryl-7-amide substrates and low molecular mass peptides. This protein was purified to an apparent homogeneity by a series of chromatographic steps on DEAE-cellulose, Sepharose CL-4B, hydroxylapatite, and fast protein liquid chromatography Mono Q columns. The protein was shown to be a complex of the plasma proteinase inhibitor alpha 2-macroglobulin and a 25-kDa endopeptidase. The enzyme activity was completely inhibited by diisopropyl fluorophosphate, p-amidinophenylmethanesulfonyl fluoride, leupeptin, antipain, bovine pancreatic trypsin inhibitor, soybean trypsin inhibitor, and ovomucoid, indicating that the entrapped enzyme is a serine proteinase. The proteinase could be released from alpha 2-macroglobulin by mild acid treatment and the released enzyme showed activity toward protein substrates. Substrate specificity studies using synthetic and peptide substrates indicated that the enzyme preferentially hydrolyzes Arg-X bonds and, to a much lesser extent, Lys-X bonds, and is apparently distinct from thrombin, kallikrein, plasmin, and other trypsin-like proteinases so far reported including tryptase. Thus, the present enzyme is thought to be a novel type of serine proteinase. The proteinase associated with alpha 2-macroglobulin was also found in porcine intestinal mucosa, but not in plasma.

Amino Acid Sequence↗
PubMed1993

A novel recovery system for cultured cells using plasma-treated polystyrene dishes grafted with poly(N-isopropylacrylamide).

Poly(N-isopropyl acrylamide) (PIPAAm) demonstrated a fully expanded chain conformation below 32 degrees C and a collapsed, compact conformation at high temperatures. This unique temperature responsive polymer was grafted onto surfaces of commercial polystyrene dishes and used as temperature switches for creating hydrophilic surfaces below 32 degrees C and hydrophobic surfaces above 32 degrees C. Cell attachment and the growth of bovine endothelial cells and rat hepatocytes on PIPAAm-grafted surfaces at 37 degrees C demonstrated similar behavior to the commercialized culture dishes. Both cell types were observed to detach from the PIPAAm-grafted surface simply by reducing the temperature below the polymer transition temperature (collapse). Cells recovered by this method maintained substrate adhesivity, growth, and secretion activities nearly identical to those found in primary cultured cells in contrast to the compromised function found in cultured cells damaged by trypsinization. These results provide strong evidence that PIPAAm-grafted surfaces, as thermal switches are very effective for reversing cell attachment and detachment without cell damage. Properties of cell culture surfaces can be readily transformed by this technique reversibly into hydrophilic and hydrophobic coatings of PIPAAm-grafted polymers.

Acrylic Resins↗
PubMed1993

Prevention of changes in platelet cytoplasmic free calcium levels by interaction with 2-hydroxyethyl methacrylate/styrene block copolymer surfaces.

Changes in platelet cytoplasmic free calcium levels were investigated in contact with cast film surfaces of a block copolymer containing 2-hydroxyethyl methacrylate (HEMA) and styrene (St) (0.5 mole fraction HEMA). These copolymer surfaces demonstrate microdomain alternating lamellae structures composed of hydrophilic HEMA domains (5 nm width) and hydrophobic St domains (20 nm width). The results were compared with those obtained from platelets contacting a random copolymer of HEMA-St (0.5 mole fraction HEMA) and from homopolymers of polystyrene (PSt) and poly(2-hydroxyethyl methacrylate) (PHEMA). Cytoplasmic free calcium levels in platelets contacting the microdomain structured surfaces of the HEMA-St block copolymer remained relatively constant in contrast to the significant increases observed for the radically prepared HEMA-St copolymer, PSt, and PHEMA surfaces. Adhering platelets were stimulated by exogenously introduced thrombin and calcium ionophore A23187 20 min after platelet adherence to the polymer surfaces. Only platelets on the block copolymer surfaces showed active metabolic responses. These results suggest that adhering platelets on the microdomain structured surfaces maintain high sensitivities to external stimulation due to an intrinsic strong inhibition of platelet functional changes induced by surface contact.

Blood Platelets↗
PubMed1993

Western blot analysis of glycoproteins bearing Lewis(a) and sialyl-Lewis(a) antigens in human colorectal mucosa.

Glycoproteins (GPs) bearing Lewis(a) and sialyl-Lewis(a) antigens (Le(a), sialyl-Le(a)) derived from human colorectal carcinomas and their surrounding non-neoplastic mucosa (normal mucosa) were analyzed using Western blotting. GPs bearing Le(a) were detected mainly as segmental bands of M(r) 310, 220, 160, and 80 kDa in 80% of the normal mucosa, but these GPs were detected predominantly as broad bands ranging from high to low molecular weight (MW) in 71% of the carcinoma tissues. GPs bearing sialyl-Le(a) were detected only in 23% of the normal mucosa and limited on huge MW bands, i.e., more than 400 kDa, whereas these GPs were detected predominantly as broad bands in 49% of the carcinoma tissues. In the cases with lymph node metastasis, the MW of GPs bearing sialyl-Le(a) varied over a wide range and were detected as broad bands, compared with the cases without metastasis. In conclusion, the MW of GPs bearing Le(a) and sialyl-Le(a) in normal colorectal mucosa was different from that in colorectal carcinomas. That is, the MWs of GPs bearing Le(a) varied more in carcinoma tissues, and the GPs bearing sialyl-Le(a) from carcinoma tissues had lower MWs than those from normal mucosa. It was, furthermore, suggested that the increased expression of lower MW GPs bearing sialyl-Le(a) are associated with an increased metastatic potential of the tumor cells.

Blotting, Western↗
PubMed1993

Factor in urinary extracts from pregnant women that inhibit mouse oocyte maturation in vitro.

Mouse oocyte maturation inhibitory factors, on the basis of inhibitory activity of spontaneous germinal vesicle breakdown (GVBD) of denuded mouse oocytes in culture, were extracted and partially purified by reversed-phase resin adsorption and Sephadex G-100 and G-50 column chromatographies from the urine of pregnant women. Denuded oocytes obtained from ovaries of ICR mice underwent spontaneous GVBD by cultivation for 3 h in modified Krebs-Ringer's buffered solution, while this spontaneous GVBD was found to be inhibited by adding the final preparation (U-D-4) of urine. The inhibition was dose dependent, ranging from 0.6 to 10 micrograms protein/ml medium. Oocytes treated with U-D-4 and resuspended in control medium resumed GVBD. The molecular mass of U-D-4 was estimated to be less than 2,000 Da with gel filtration. Ether treatment failed to extract inhibitory factor(s) from U-D-4 and pepsin treatment inactivated U-D-4, indicating that inhibitory factor(s) in U-D-4 are peptide-like substances. The inhibitory effect of U-D-4 on spontaneous GVBD was partially reversed in the presence of naloxone, a potent opioid antagonist. U-D-4s obtained from urine samples of pregnant women, nonpregnant women, and men showed the inhibitory effect on spontaneous GVBD; however, the activity of U-D-4 obtained from pregnancy urine was significantly more potent than those of the other urine samples.

Animals↗
PubMed1993

Neonatal medulloblastoma.

A 9-day-old female presented with a large infra- and supratentorial medulloblastoma was treated by surgery, irradiation and chemotherapy. The infant suffered from vomit a few days after birth. She was hospitalized shortly thereafter, when head enlargement was noted. A CT scan taken on admission disclosed a large mass lesion in the cerebellum, extending to the pineal portion, and marked hydrocephalus. At the age of 14 days, the patient underwent ventriculoperitoneal shunting. When she was 67 days old, the tumor was radically resected. The histopathological diagnosis was medulloblastoma. Post operatively, she was irradiated with 30 Gy to the whole brain and 20 Gy to the tumor site. As chemotherapy, ACNU, 1-(4-amino-2-methyl-5-pyrimidinyl-3-(2-chloroethyl)-3-nitrosourea 1 mg/kg was administered twice per 6 weeks. On discharge at 7 months, her only neurological deficit was nystagmus. One week later, she could not move her legs and was readmitted. A CT scan showed no intracranial changes, but the spinal cord was swollen at Th12-L5 level. Myelography demonstrated a filling defect at the L3-5 level. Following irradiation of the spinal cord, the paraparesis gradually improved. However, her general status was deteriorating and a follow up CT scan revealed recurrence of the intracranial tumor. The patient died at the age of 9.3 months which is longer survival time than previous reported one. Neonatal brain tumors are rare, and there have been only 24 cases of neonatal medulloblastoma. The prognosis for these patients is extremely poor, regardless of treatment. Surgery, radiation and chemotherapy for neonatal medulloblastoma are discussed.

Brain Neoplasms↗
PubMed1993

Analysis of micelle formation of an adriamycin-conjugated poly(ethylene glycol)-poly(aspartic acid) block copolymer by gel permeation chromatography.

The micelle-forming behavior of a drug-block copolymer conjugate (adriamycin-conjugated poly(ethylene glycol)-poly(aspartic acid) block copolymer; PEG-P[Asp(ADR)]) was analyzed by gel permeation chromatography (GPC). Four compositions of the conjugates were observed to form micellar structures in aqueous media, and their micelle-forming behavior was found to be dependent on the composition and media. These micelles did not reach equilibrium within short time periods like low molecular weight surfactants. One composition formed stable micelles in the presence of serum.

Animals↗
PubMed1993

Biodistribution of micelle-forming polymer-drug conjugates.

Polymeric micelles have potential utility as drug carriers. To this end, polymeric micelles based on AB block copolymers of polyethylene oxide (PEO) and poly(aspartic acid) [p(Asp)] with covalently bound Adriamycin (ADR) were prepared. The micelle forming polymer-drug conjugates [PEO-p(Asp(ADR)] were radiolabeled and their biodistribution was investigated after intravenous injection in mice. Long circulation times in blood for some compositions of PEO-p[Asp(ADR)] conjugates were evident, which are usually atypical of colloidal drug carriers. This was attributed to the low interaction of the PEO corona region of the micelles with biocomponents (e.g., proteins, cells). Low uptake of the PEO-p(Asp(ADR)] conjugates in the liver and spleen was determined. The biodistribution of the PEO-p[Asp(ADR)] conjugates was apparently dependent on micelle stability; stable micelles could maintain circulation in blood, while unstable micelles readily formed free polymer chains which rapidly underwent renal excretion. Long circulation times in blood of PEO-p(Asp(ADR)] conjugates are thought to be prerequisite for enhanced uptake at target sites (e.g., tumors).

Animals↗
PubMed1993

Semantic process in kana word reading: activation studies with positron emission tomography.

Regional cerebral blood flow was measured by positron emission tomography to study changes during Japanese kana word or kana non-word reading tasks. The main cortical activation was observed bilaterally in the lateral and medial occipital gyri, and the left posterior inferior temporal area in both kana word and kana non-word tasks. In addition, the kana word task activated the right posterior inferior temporal area. Comparison of the mean regional cerebral blood flow increases revealed that the kana word task activated the left posterior inferior temporal area more than the kana non-word task, suggesting the role of the semantic process as well as the morphological one in this area.

Adolescent↗