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Biomedical subjects

S Shimada

Publications and source records attributed to S Shimada.

At least 271 records · Page 15Linked to original sources
PubMed1992

Clinical events in association with timing of intraventricular hemorrhage in preterm infants.

To ascertain whether any routine practices or clinical manipulations in a neonatal intensive care unit could induce intraventricular hemorrhage (IVH) in preterm infants, we performed ultrasonic monitoring of the germinal layer continuously for 48 hours in 33 extremely premature infants with respiratory distress. Intraventricular hemorrhage developed in 16 of these infants. In four infants the timing of the germinal layer hemorrhage was confirmed with ultrasonic monitoring. Three of the four cases were apparently associated with clinical events occurring at the moment of IVH: manual ventilation for improvement of hypercapnia associated with primary pulmonary hypertension of the newborn; correction of hyperkalemia, which was causing an arrhythmia, with administration of calcium gluconate and sodium bicarbonate; and administration of surfactant-TA to improve respiratory failure caused by pulmonary hemorrhage. In these three infants it appeared that one of the basic factors inducing IVH might be an increase in blood pressure with or without hypercapnia, causing cerebral reperfusion after ischemic damage of the germinal layer.

Blood Pressure↗
PubMed1992

Time course and inhibition of saponin-induced hemolysis.

Hemolytic activities of 3 steroid saponins reached plateaus within 5 min, whereas those of 4 triterpenoid saponins did not within 60 min. Erythrocytes pretreated with a low concentration of tigogenin were resistant to hemolysis of some of these saponins, but those pretreated with hecogenin or tomatidine were as sensitive as non-treated erythrocytes. Therefore, the ketone group of hecogenin or the amino group of tomatidine would weaken the interactions between the erythrocytes and these sapogenins. Furthermore, incubations of these saponins with a small amount of cholesterol diminished the hemolytic activities.

Animals↗
PubMed1992

Role of asparagine-linked carbohydrates in pulmonary metastasis of B16-F10 murine melanoma cells: implication through glycosylation inhibition by nojirimycin.

N-linked oligosaccharide moieties of cell surface glycoconjugates may be involved in the metastatic potential of tumour cells. Many studies have examined the anti-metastatic properties of inhibitors of carbohydrate synthesis or processing in vitro. However, there has so far been little evidence of such inhibitory factors on metastasis in vivo because of the general high toxicity of the inhibitors. In this study, we found nojirimycin (NM) to be a substantially non-toxic carbohydrate synthesis inhibitor that inhibited the experimental metastasis of B16-F10 melanoma cells not only in vitro but also in vivo. When NM was administered intraperitoneally to syngeneic C57BL/6 mice, the inhibition was dose-dependent, with 40-75% suppression of pulmonary colonization observed after 5 days exposure to NM (at 0.4 or 4 mg/day). An in vitro lectin sensitivity assay showed that NM-treated B16-F10 cells were less susceptible to the lectin concanavalin-A, suggesting alteration or decrease of high mannose-type carbohydrate moieties on the cell surface. Further in vitro analysis of adhesiveness between B16-F10 cells and endothelial cells demonstrated that NM treatment causes reduced binding of B16-F10 cells to endothelial cells. We have also studied the effect of NM on natural killer (NK) cells in mice. NM treatment elicited no substantial increase in the cytotoxic activity of splenic NK cells against YAC-1 target cells. These results indicate that NM acts on the process of adhesion and that specific structures of the cell surface carbohydrate moieties may be involved in the colonization phase of metastasis in vivo.

1-Deoxynojirimycin↗
PubMed1992

DNA from bacteria, but not from vertebrates, induces interferons, activates natural killer cells and inhibits tumor growth.

The nucleic acid fraction from cells of 6 species of bacterium and 2 kinds of vertebrate, calf and salmon, was extracted and purified by the same procedures as described previously. When the spleen cells from BALB/c mice were incubated with the nucleic acid fraction from either of the bacteria, natural killer (NK) activity of the cells was remarkably elevated and the cells produced factors to activate macrophages and to inhibit viral growth. It was shown that the factor to activate macrophages was interferon (IFN)-gamma and that to inhibit viral growth was IFN-alpha/beta. On the other hand, the nucleic acid fraction from either of the vertebrate cells did not show such activities. Pretreatment of the bacterial nucleic acid fraction with DNase, but not with RNase, abrogated completely the biological activities. The activities of the bacterial nucleic acid were not influenced by the presence of polymyxin B, an inhibitor of lipopolysaccharide (LPS), and the spleen cells from not only BALB/c mice but also LPS-insensitive C3H/HeJ mice were activated, indicating that the activities of the fraction were not ascribed to LPS contaminated possibly into the fraction, but to DNA itself. Intralesional injection with the bacterial DNA fraction caused regression of mouse IMC tumors, but the injection with the vertebrate DNA fraction did not. These findings prompted us to examine the biological activities of DNA samples from a variety of animals and plants, which were provided from other laboratories or purchased from manufacturers. All of the DNA samples from cells of 5 kinds of bacterium, 2 of virus and 4 of invertebrate augmented NK activity and induced IFN, more or less, in mouse spleen calls, while the DNA from 10 kinds of vertebrate, including 3 of fish and 5 of mammal, showed no such activities. The DNA from 2 species of plants, were also inactive. Possible mechanisms to explain the different biological activities of DNA from different cell sources were discussed based on our previous finding that the particular palindromic sequences with a G-C motif(s) are required for induction of IFNs and activation of NK cells with synthetic 30-mer oligonucleotides.

Adjuvants, Immunologic↗
PubMed1992

Surfactant replacement therapy in premature babies with respiratory distress syndrome: factors affecting the response to surfactant and comparison of outcome from 1982-86 and 1987-91.

The impact of surfactant therapy on chronic lung disease remains uncertain. During the past decade (1982-91), over 300 babies with respiratory distress syndrome (RDS) weighing 501-2,500 g at birth were consecutively treated with surfactant-TA at our neonatal intensive care unit. Data on 95 RDS babies treated in the first 5 year period (Period 1, 1982-86) were compared with those on 158 RDS babies treated in the second 5 year period (Period 2, 1987-91). Overall respiratory improvement was better in Period 2 than in Period 1. In Period 2, surfactant therapy converted 98% of the babies with moderate/severe RDS to those with 'near normal' lung by 72 hr post-treatment. In Period 2, 95% of the surfactant-treated babies weighing 501-1,750 g at birth survived, 97% of which required no supplemental oxygen at 40 weeks corrected gestational age. Increased survival rate in the surfactant-treated babies during the past decade has not been followed by a parallel increase in chronic lung disease. The severity of the initial pulmonary disease per se was not the significant risk factor for chronic lung disease. Several other variables affecting the response to surfactant therapy and outcome have been identified by stepwise logistic regression analysis and include factors related to perinatal events such as birth asphyxia and infection, and other complications of prematurity.

Chronic Disease↗
PubMed1992

Traumatic subdural hygroma: pathology and meningeal enhancement on magnetic resonance imaging.

Five patients with traumatic subdural hygroma are reported with reference to its pathology and meningeal enhancement on magnetic resonance imaging. Hygromas showed initially iso- and, later, high intensity on both T1- and T2-weighted images compared with the intensity of the cerebrospinal fluid. In all cases of the thick hygromas, magnetic resonance imaging with gadolinium diethylene-triamine-pentaacetic acid showed meningeal enhancement. Intravenously injected radioisotope immediately flowed into the hygromas, but computed tomographic cisternography and gross inspection during the surgery showed no evidence of an influx of cerebrospinal fluid into the hygromas. Microscopic examination of the enhanced meninges revealed vascularized neomembrane with numerous fenestrations and pinocytosis underneath the dura mater. It is suggested from these data that the subdural neomembrane is associated with the development of the traumatic subdural hygromas. Meningeal enhancement would be useful to clarify the growing mechanism of traumatic subdural hygromas.

Aged↗
PubMed1992

[A retrospective analysis of surgical operations on malignancies of the ear].

In the past 20 years from 1970 to 1990, 21 patients with malignancies of the ear were treated at Cancer Institute Hospital. The primary sites were the auricle and cartilaginous external auditory canal (group 1: n = 8), the bony external auditory canal (group 2: n = 6) and the middle ear (group 3:n = 7). In group 1, pathological types were squamous cell carcinoma in four patients and basal cell carcinoma in the other four patients. Seven patients were treated by surgery alone, and the remaining patient was treated by interstitial implant radiotherapy. No recurrence have been noted up to today in this group. In group 2, pathological types were squamous cell carcinoma in four patients and adenoid cystic carcinoma in the other two patients. All of the six patients underwent external canal resection or subtotal temporal resection. Two patients received postoperative radiotherapy. A five year survival rate of group 2 was 60%. In group 3, pathological types were squamous cell carcinoma in six patients and undifferentiated carcinoma in the remaining patient. Most of them underwent radical mastoidectomy followed by irradiation. However, all the patients died within two years after treatment. In group 2 and 3, cytodiagnosis was useful for early discovery. In group 2, temporomandibular joint seemed to be a key point in surgical treatment. In group 3, the combination of conservative surgery with radiotherapy was not a radical treatment. This suggested it necessary to perform subtotal temporal resection to treat malignancy of the middle ear.

Adult↗
PubMed1992

gamma-Aminobutyric acid A or C receptor? gamma-Aminobutyric acid rho 1 receptor RNA induces bicuculline-, barbiturate-, and benzodiazepine-insensitive gamma-aminobutyric acid responses in Xenopus oocytes.

Xenopus oocyte expression of the recently cloned gamma-aminobutyric acid (GABA) rho 1 receptor subunit cDNA yields a pharmacologic profile characteristic of the GABAc responses described by Johnston [Benzodiazepine/GABA Receptors and Chloride Channels. Receptor Biochemistry and Methodology (R. W. Olsen and J. C. Venter, eds), Vol. 5. Alan R. Liss, New York, 57-71 (1986)] and the responses to retinal mRNA recently reported in the Xenopus expression system [Proc. Natl. Acad. Sci. USA 88:4318-4322 (1991)]. A rationale for defining GABA rho 1 as forming a GABAc receptor is discussed.

Animals↗
PubMed1992

[A device for hepatic arterial catheterization using saphenous vein graft].

We performed regional arterial infusion chemotherapy for hepatocellular carcinoma by retaining a hepatic arterial reservoir. The catheters were placed via gastroduodenal artery and positioned at the junction with common hepatic artery during operation. But we encountered many complications and did not perform regional arterial infusion chemotherapy. This time we cannulated through the saphenous vein graft by which hepatic perfusion was maintained by the superior mesenteric artery; we did not cannulate through the common femoral artery using a subcutaneously implanted reservoir. Venous arterial anastomosis is performed with interrupted (7-0 Prolene) vascular suture. Postoperative angiography by the reservoir showed total hepatic perfusion. There have been no instances of hemorrhage, thrombosis, or catheter dislodgement with this technique. Duration of follow-up varied from 2 to 7 months.

Carcinoma, Hepatocellular↗
PubMed1992

[Fluorescein fundus angiography of optic nerve head in primary open angle glaucoma and low tension glaucoma].

Fluorescein fundus angiography was performed at angle of 20 degrees in the 58 low tension glaucoma (LTG) eyes (30 cases) and 77 primary open angle glaucoma (POAG) eyes (41 cases) and the relation of the optic nerve head fluorescein changes to visual field disturbances (stage classification of Kosaki) was compared between POAG and LTG groups. The filling defect of fluorescein in the deep area and the decrease in number of superficial capillaries were observed in the optic nerve head. The filling defect area of fluorescein in the optic nerve head corresponding to Bjerrum scotoma was recognized even in the mild visual field disturbance cases of both LTG and POAG. The following findings were noted in both LTG and POAG cases; expansion of the filling defect area and the decrease in number of superficial capillaries in the same area with progression of visual field disturbances. Filling defect area of fluorescein of the optic nerve head accorded with visual field disturbance area in 19 LTG eyes (32.8%) and 61 POAG eyes (79.2%). On the contrary, the filling defect area of the optic nerve head was wider than the visual disturbance area in 37 LTG eyes (63.8%) and 16 POAG eyes (20.8%). These findings suggest that blood circulatory disorders of the optic nerve head occurred earlier in LTG than in POAG and that the development of LTG might be closely associated with the blood circulatory disorders.

Aged↗
PubMed1991

Cloning and expression of a cocaine-sensitive dopamine transporter complementary DNA.

A rat dopamine (DA) transporter complementary DNA has been isolated with combined complementary DNA homology and expression approaches. The DA transporter is a 619-amino acid protein with 12 hydrophobic putative membrane-spanning domains and homology to the norepinephrine and gamma-aminobutyric acid transporters. The expressed complementary DNA confers transport of [3H]DA in Xenopus oocytes and in COS cells. Binding of the cocaine analog [3H]CFT ([3H]2 beta-carbomethoxy-3 beta-(4-fluorophenyl)tropane) to transfected COS cell membranes yields a pharmacological profile similar to that in striatal membranes.

Amino Acid Sequence↗
PubMed1991

Identification of a novel tumor-associated Mr 110,000 gene product in human gastric carcinoma cells that is immunologically related to carcinoembryonic antigen.

A novel gene product which is immunologically related to carcinoembryonic antigen (CEA) and constitutively expressed by six of eight human gastric carcinoma cell lines is described. The antigen was initially identified by the differential binding patterns of four monoclonal antibodies (MAbs) which recognize the putative Mr 180,000 CEA and/or the Mr 90,000 CEA-related gene product, NCA (normal cross-reacting antigen). Western blot analyses of partially purified membrane fractions prepared from Hs 746T gastric carcinoma cells identified an Mr 110,000 antigen. Northern blot analyses using CEA- and NCA-specific complementary DNA probes did not identify any specific CEA or NCA transcripts in polyadenylate-selected mRNA isolated from the Hs 746T cells. Likewise, a probe designed to hybridize with different CEA-related family members failed to identify a CEA-related message in the Hs 746T cells. Subsequent studies revealed that interferon-gamma (IFN-gamma) treatment substantially increased the level of expression of the Mr 110,000 antigen on the Hs 746T and five other gastric cell types that constitutively expressed the antigen. IFN-gamma treatment also de novo induced the expression of the Mr 110,000 antigen on the surface of GaCa gastric carcinoma cells. A high percentage of Hs 746T (i.e., greater than 85%) and GaCa (approximately 75%) gastric carcinoma cells expressed the Mr 110,000 antigen after IFN-gamma treatment; yet, neither cell type expressed CEA or NCA as measured by the binding of the anti-CEA MAb, COL-1, or B6.2, an anti-NCA MAb. In contrast to CEA and NCA, phosphatidylinositol phospholipase C treatment failed to release the Mr 110,000 antigen from the surface of the Hs 746T or IFN-gamma-treated GaCa cells, suggesting that membrane attachment of this novel antigen is not via a glycosyl-phosphatidylinositol anchor. Finally, primers that amplify the 420 base pairs of the immunoglobulin-like domain of CEA and NCA detected an appropriately sized product in untreated as well as IFN-gamma-treated GaCa cells using the polymerase chain reaction method. Thus, a potentially novel gene product coding for an Mr 110,000 antigen that is strongly upregulated by IFN-gamma has been identified in human gastric carcinoma cells. Immunologically, the antigen shares reactive epitopes with CEA and its related NCA gene product; however, Northern blot analyses, polymerase chain reaction, and phosphatidylinositol phospholipase C results suggest that the antigen may be, at best, a distant relative of the CEA gene family.

Amino Acid Sequence↗
PubMed1991

Cloning of the gamma-aminobutyric acid (GABA) rho 1 cDNA: a GABA receptor subunit highly expressed in the retina.

Type A gamma-aminobutyric acid (GABAA) receptors are a family of ligand-gated chloride channels that are the major inhibitory neurotransmitter receptors in the nervous system. Molecular cloning has revealed diversity in the subunits that compose this heterooligomeric receptor, but each previously elucidated subunit displays amino acid similarity in conserved structural elements. We have used these highly conserved regions to identify additional members of this family by using the polymerase chain reaction (PCR). One PCR product was used to isolate a full-length cDNA from a human retina cDNA library. The mature protein predicted from this cDNA sequence in 458 amino acids long and displays between 30 and 38% amino acid similarity to the previously identified GABAA subunits. This gene is expressed primarily in the retina but transcripts are also detected in the brain, lung, and thymus. Injection of Xenopus oocytes with RNA transcribed in vitro produces a GABA-responsive chloride conductance and expression of the cDNA in COS cells yields GABA-displaceable muscimol binding. These features are consistent with our identification of a GABA subunit, GABA rho 1, with prominent retinal expression that increases the diversity and tissue specificity of this ligand-gated ion-channel receptor family.

Amino Acid Sequence↗
PubMed1991

Endothelin receptor: a profoundly desensitizing receptor expressed in Xenopus oocytes.

Xenopus oocyte expression studies can help to define the physiological properties of a receptor and can aid in receptor cloning. Expression of an endothelin receptor in oocytes injected with brain mRNA is inferred from depolarizations induced by several endothelin-related peptides. The response is abolished by intracellular EGTA injection but not in the absence of extracellular Ca2+. It is not present in non-injected oocytes, and reverses at a potential indicating that it is mediated by an increased Cl-1 conductance. Responses display striking, long-lasting desensitization. The expressed endothelin receptor thus displays properties characteristic of several receptors coupled to changes in phosphoinositide turnover, several of which have been successfully cloned using this response as a reporter.

Animals↗
PubMed1991

Spiny and aspiny types of neuropeptide Y immunoreactive neurons in the monkey neostriatum.

The present study demonstrates the existence of two types of neurons with neuropeptide Y (NPY) immunoreactivity in the neostriatum of the monkey (Macacus fuscatus) by using the avidin-biotin-immunoperoxidase method. One type, accounted for about 80% of striatal NPY cells, corresponded to the medium-sized aspiny type neurons. The other type resembled the medium-sized, spiny type II neurons. These findings suggest that there are at least two functional subpopulations of NPY neurons in the monkey neostriatum.

Animals↗