Search PubMed⌕ Search

Biomedical subjects

T Murakami

Publications and source records attributed to T Murakami.

At least 739 records · Page 41Linked to original sources
PubMed1996

Bioactive saponins and glycosides. VII. On the hypoglycemic principles from the root cortex of Aralia elata Seem.: structure related hypoglycemic activity of oleanolic acid oligoglycoside.

The hypoglycemic component, elatoside E, was isolated from the root cortex of Aralia elata SEEM. (Araliaceae) together with elatoside F and eight known oleanolic acid glycosides, elatosides A and C, oleanolic acid 3-O-[alpha-L-arabinofuranosyl (1-->4)]-beta-D-glucopyranosiduronic acid, oleanolic acid 3-O-beta-D-glucopyranosiduronic acid, stipuleanosides R1 and R2, and chikusetsusaponins IV and IVa. The structures of elatosides E and F were determined on the basis of chemical and physicochemical evidence as oleanolic acid 3-O-[beta-D-xylopyranosyl (1-->2)][beta-D-glucopyranosyl (1-->3)]-alpha-L-arabinopyranoside and its 28-O-beta-D-glucopyranosyl ester, respectively. The hypoglycemic activity of oleanolic acid and nine oleanolic acid oligoglycosides from the root cortex of Aralia elata was determined by monitoring inhibition effect on the elevation of plasma glucose level by oral sucrose tolerance test in rats, and some structure-activity relationships of oleanolic acid glycoside were obtained.

Animals↗
PubMed1996

New hypoglycemic constituents in "gymnemic acid" from Gymnema sylvestre.

Investigation of hypoglycemic activity of major saponin constituents from "gymnemic acid", a crude saponin fraction of G. sylvestre, exposed not only two new saponins, gymnemosides a (1) and b (2), but also gymnemoside b and gymnemic acid V (7) as active principles. Furthermore, an acetyl group linked 16- or 22-hydroxy group in 1 and 2 was found to migrate easily to primary 28-hydroxyl group, while acyl migration from 28-hydroxy group in 3 was little observed.

Animals↗
PubMed1996

Medicinal foodstuffs. II. On the bioactive constituents of the tuber of Sagittaria trifolia L. (Kuwai, Alismataceae): absolute stereostructures of trifoliones A, B, C, and D, sagittariosides a and b, and arabinothalictoside.

From the medicinal foodstuff "kuwai", the tuber of Sagittaria trifolia L., four bioactive diterpene ketones, trifoliones A, B, C, and D, two diterpene glucosides, sagittariosides a and b, and a nitroethylphenol glycoside, arabinothalictoside, were isolated, together with six known diterpenes. Their absolute stereostructures were determined on the basis of chemical and physicochemical evidence which included the application of a modified Mosher's method and an exciton chirality method. Among the diterpene constituents, trifoliones A, B, C, and D exhibited inhibitory effects on the histamine release from rat mast cells induced by compound 48/80 and calcium ionophore A-23187.

Animals↗
PubMed1996

Molecular cloning and nucleotide sequences of cDNA and gene encoding endo-inulinase from Penicillium purpurogenum.

A cDNA and a gene encoding endo-inulinase from Penicillium purpurogenum were isolated, and were cloned for the first time. Two oligonucleotide probes, which were synthesized based on the partial amino acid sequences of the purified endo-inulinase, were used to screen a cDNA library. A 1.7-kb DNA fragment encoding endo-inulinase was isolated and analyzed. A single open reading frame, consisting of 1548-bp, was found to encode a polypeptide that comprised a 25-amino acid signal peptide and 490-amino acid mature protein. All the partial amino acid sequences of the purified enzyme were discovered in the deduced ones. The deduced amino acid sequences of endo-inulinase had similar sequences to those of fructan hydrolases. A 3.5-kb chromosomal DNA fragment encoding endo-inulinase was also isolated and analyzed. The same ORF with cDNA clone as identified. There were no introns in the endo-inulinase gene.

Amino Acid Sequence↗
PubMed1996

Long-term results of emergency coronary artery bypass grafting.

During a 20-year period, 364 patients underwent coronary artery bypass grafting (CABG) for the treatment of ischemic heart disease. Among these patients, 28 underwent emergency surgery. The reasons for performing emergency CABG were unstable angina in 15 patients, impending myocardial infarction in 12 patients and congestive heart failure in 1 patient. Eleven patients died postoperatively. Eight variables were examined by univariate analysis for their influence on the occurrence of a hospital death. Lack of a history of myocardial infarction, intraaortic balloon pumping (IABP) and acute coronary occlusion were all found to be predictors of hospital death. Seventeen patients were followed up for 12 years. There was no cardiac death and actuarial survival at 12 years was 63%. The 14 survivors are now in NYHA functional class I or II. Although the operative mortality rate is high after emergency CABG, a fair prognosis can be expected if the patients survive surgery.

Adult↗
PubMed1996

Effects of adenosine triphosphate on wide QRS tachycardia. Analysis in 18 patients.

A few studies have indicated that adenosine terminated triggered-activity idiopathic ventricular tachycardia, but all involved a small number of cases. The effects of adenosine triphosphate (ATP) on wide QRS tachycardia have thus not yet been completely clarified. This retrospective study was performed to evaluate the therapeutic and diagnostic utility of ATP in wide QRS tachycardia. A total of 18 patients with wide QRS tachycardia (QRS width > 120 msec, rate > or = 150 beats/min) were evaluated. ATP, 20-40 mg, was administered intravenously. An electrophysiological study and treadmill stress test were performed in all patients to elucidate the mechanism of the tachycardia. ATP terminated tachycardia or induced atrio-ventricular block in all 6 patients who had supraventricular tachycardia, but it had no effect on preexcited atrial fibrillation or pre-excited atrial flutter. Ventricular tachycardia was terminated by ATP in 5 of the 10 patients. In 4 of these 5 patients, the focus of the tachycardia was the right ventricular outflow tract. No entrainment phenomenon was demonstrated by electrophysiological study with induction of the tachycardia by stress test or isoproterenol infusion, suggesting the contribution of triggered activity to the tachycardia. In the remaining patient with complete right bundle branch block type tachycardia with right axis deviation, the mechanism of ventricular tachycardia could not be determined. In the 5 patients in whom ATP failed to terminate ventricular tachycardia, the reentry mechanism was suggested by the presence of entrainment phenomenon depicted on electrophysiological study. In summary, this study suggests that ATP terminates supraventricular wide QRS tachycardia and ventricular tachycardia due to triggered-activity, but that it has no effect on pre-excited atrial fibrillation or flutter or on ventricular tachycardia due to a reentry mechanism. These findings add to the mounting evidence regarding the therapeutic and diagnostic utility of ATP in wide QRS tachycardia.

Adenosine Triphosphate↗
PubMed1996

Extracellular matrix components in dilated cardiomyopathy. Immunohistochemical study of endomyocardial biopsy specimens.

Fibrotic change is one of the characteristic features of the heart with idiopathic dilated cardiomyopathy (DCM), but the extracellular matrix components have not been fully clarified. Fibronectin, laminin, and types IV, I and III collagen staining using the avidin-biotin-peroxidase complex method was conducted to study the localization of extracellular matrix components in biopsy specimens obtained from 7 patients with DCM. Fibronectin was observed in the endomysium and perimysium, co-existent with types I and III collagen; it was also distributed nonhomogeneously in the replacement fibrotic lesions. The staining intensity in a section varied substantially from location to location. Laminin surrounded the myocytes and was distributed in the endomysium localized together with type IV collagen, but it was not found in the perimysium. Weak but positive staining was observed in replacement fibrotic lesions in 2 patients. Similarly to laminin, type IV collagen staining was observed around the myocytes and in the endomysium. It was also observed in replacement fibrotic lesions in 4 patients either with or without laminin. Type I collagen, localized together with type III collagen, was distributed in both the endomysium and perimysium. It was also distributed nonhomogeneously in the replacement fibrotic lesions. Similar staining to type I collagen was seen for type III collagen. In summary, all examined components were observed in the fibrotic lesions with no primary deficit of any examined component being demonstrated. The variability of staining intensity and positive fibronectin staining suggests that the phases of fibrotic changes differed substantially from location to location.

Adolescent↗
PubMed1996

Is direct cell-to-cell contact needed to improve embryonic development in co-culture?

In vitro co-culture of embryos and somatic cells is used to obtain well-developed embryos of humans and other species. However, it is not known whether direct cell-to-cell contact is essential to embryonic development. To elucidate this mechanism, we cultured mouse embryos using rabbit oviductal cell as a somatic cell. To avoid the direct contact we used a microporous membrane cell-culture insert. This cell-culture insert permits only the liquid portion of the culture medium to pass through it and was interposed between mouse embryos and cultured rabbit oviductal cells. When mouse embryos were placed on the cultured oviductal cells directly, 52.2% of two-cell-stage embryos developed to the blastocyst stage. In contrast, when the cell-culture insert was interposed between the embryos and the cultured oviductal cells, 50.0% of two-cell-stage embryos developed to that stage. There was no difference between the rate of blastocyst development in co-culture system with and without cell culture insert. Results indicate that oviductal factor (s), rather than a direct contact with oviductal cells, is essential to the enhancement of embryonic development in vitro.

Animals↗
PubMed1996

Neurons with perineuronal sulfated proteoglycans in the mouse brain and spinal cord: their distribution and reactions to lectin Vicia villosa agglutinin and Golgi's silver nitrate.

This study demonstrates that many neurons in the somatosensory cortex, cingulate cortex, retrosplenial cortex and hippocampal subiculum of the mouse brain are covered by sulfated proteoglycans which are intensely negative-charged and stained with cationic iron colloid, while being digested with hyaluronidase. Neurons with similar perineuronal proteoglycans are also recognized in the extrapyramidal system (superior colliculus, red nucleus, reticular formation, vestibular nuclei and cerebellar nuclei), in the secondary auditory system (cochlear nuclei, nucleus of trapezoid body, inferior colliculus and nucleus of lateral lemniscus), in the vestibulo-ocular reflex system (vestibular nuclei and extraocular motor nuclei), and in the pupillary reflex system. The neurons with perineuronal sulfated proteoglycans in the cerebral cortices and hippocampal subiculum are usually labeled with the lectin Vicia villosa agglutinin, though those in the cerebellar, vestibular and cochlear nuclei may not be reactive to this lectin. Double staining of the retrosplenial cortex, hippocampal subiculum and cerebellar nuclei with Golgi's silver nitrate and cationic iron colloid indicates that the perineuronal sulfated proteoglycans are identical with the Golgi's reticular coating or glial nets.

Animals↗
PubMed1996

Perineuronal sulfated proteoglycans in the human brain are identical to Golgi's reticular coating.

Many neurons in the human somatosensory cortex (Area 7 of Brodmann) possess an intensely negative-charged surface coat consisting of perineuronal sulfated proteoglycans which were stained with cationic iron colloid. This surface coat was stained doubly with cationic iron colloid and Golgi's silver nitrate. The result indicates that the perineuronal sulfated proteoglycans are identical with Golgi's reticular coating, whose existence and nature have previously been controversial. The result also suggests that Golgi's silver nitrate stains the core proteins of proteoglycans.

Aged↗
PubMed1996

Dark neurons in the mouse brain: an investigation into the possible significance of their variable appearance within a day and their relation to negatively charged cell coats.

This study aims to investigate the occurrence and nature of dark neurons in the central nervous system under physiological conditions. Mouse brain tissues were perfusion-fixed with paraformaldehyde or glutaraldehyde at 4 h intervals during one day (3:00, 7:00, 11:00, 15:00, 19:00, 23:00). Paraffin sections were stained with the cationic colloidal iron method, and counterstained with nuclear fast red or carbolthionin. The dark neurons were readily distinguishable as their shrunken cell bodies stained densely with nuclear fast red or thionin. Some of the dark cells were coated with perineuronal sulfated proteoglycans; this coat, which formed a smoothly extended meshwork in light cells, presented spicule-like forms in the dark cells. The occurrence of dark cells in the retrosplenial cortex varied by the time of day: the incidence of the dark neurons was low (10-15%) at 11:00, 15:00 and 23:00, while it was significantly high (50-60%) at 3:00 and 19:00. Previous authors have ascribed the occurrence of dark neurons either to artifacts due to inappropriate fixation or to pathological damage. However, the present study strongly suggests that this type of neuron occurs under physiological conditions as reversible changes, and vary over a day, showing distinct peaks. These peaks occurred coincidentally while the mice were awake. Such morphological changes may be involved in the neuronal activation and exhaustion. Our view is consistent with the hypothesis (Tewari and Bourne, 1963) that the neurons take such dark profiles at certain stages of neurosecretion.

Animals↗
PubMed1996

Perineuronal sulfated proteoglycans, cell surface glycoproteins and dark neurons in the cingulate cortex of newborn and adult rats.

Many neurons in the adult rat cingulate cortex possess perineuronal sulfated proteoglycans detectable with cationic iron colloid and aldehyde fuchsin, or cell surface glycoproteins reactive to lectin Vicia villosa or soybean agglutinin. The perineuronal sulfated proteoglycans develop three to four weeks after birth. The cell surface glycoproteins develop at earlier stage or two to three weeks after birth. Dark or active neurons begin to appear three to four weeks after birth. These findings indicate that the brain matures after birth or during weaning period.

Animals↗
PubMed1996

Perineuronal sulfated proteoglycans in the adult rat brain: histochemical and electron microscopic studies.

Neurons of cerebellar nuclei in the rat brain had a marked surface coat which was stained with cationic iron colloid or aldehyde fuchsin. Neurons with a similar surface coat were also noted in the retrosplenial cortex. The surface coat was stained doubly with cationic iron colloid and aldehyde fuchsin. Digestion with hyaluronidase eliminated the stainability of the surface coat to both agents. Combined digestion with chondroitinase ABC, heparitinase and keratanase eliminated the cationic iron colloid staining but did not interfere with the aldehyde fuchsin staining. Electron microscopy of ultrathin sections revealed that the iron particles were deposited in the perineuronal tissue spaces. These findings indicate that the surface coat consists of sulfated proteoglycans which occupy, as the extracellular matrix, the perineuronal tissue spaces. Many neurons in the retrosplenial cortex were labeled with lectin Vicia villosa agglutinin. Double staining revealed that these lectin-labeled neurons are usually reactive to cationic iron colloid. Few neurons in the cerebellar nuclei were labeled with lectin V. villosa agglutinin.

Animals↗
PubMed1996

Rat parathyroid gland, with special reference to its blood vascular bed, pericapillary space and intercellular space.

The blood vascular bed, perivascular space and intercellular space of the rat parathyroid gland were studied using scanning electron microscopy of vascular casts, freeze-cracked tissue samples, and NaOH-digested tissue blocks. The findings were supplemented by transmission light and electron microscopy of iron colloid-treated or enzyme-digested tissue sections. The rat parathyroid gland contained a rich network of capillaries. These capillaries were surrounded by marked pericapillary spaces which were demarcated by basal lamina of both capillaries and parenchymal cells. The pericapillary spaces contained numerous collagen fibrils, and issued many crista-like projections which ran deep into the sheets of parenchymal cells. The intercellular spaces of parenchymal cells contained neither basal lamina nor collagen fibrils. The surfaces of the parenchymal cells showed strong negative charging, and maintained the intercellular spaces. The luminal surfaces of the capillary endothelium also showed strong negative charging, and maintained the capillary lumen.

Animals↗
PubMed1996

Melatonin accelerates reentrainment of circadian locomotor activity rhythms to new light-dark cycles in the rat.

We examined whether continuous melatonin administration through subcutaneously implanted silastic tubing accelerates reentrainment of circadian rhythms of locomotor activity to shifted illumination cycles. We found that rats required less time to reentrain to an advanced or delayed phase shift of a light-dark cycle while carrying a silastic implant filled with melatonin than while carrying an empty implant. These results suggest that continuous administration of melatonin accelerates the reentrainment of the circadian locomotor activity rhythm to a new light-dark cycle.

Activity Cycles↗
PubMed1996

Dynamic MR imaging and early-phase helical CT for detecting small intrahepatic metastases of hepatocellular carcinoma.

OBJECTIVE: We performed a study to evaluate the sensitivities of multislice dynamic MR imaging and early-phase helical CT as noninvasive methods for detecting small intrahepatic metastases of hepatocellular carcinomas. MATERIALS AND METHODS: Dynamic and spin-echo MR imaging and early- and delayed-phase helical CT of the liver were performed for patients with multiple hepatocellular carcinomas before transcatheter arterial chemoembolization. Forty-nine patients had 242 intrahepatic metastases less than 3 cm in diameter. Using iodized-oil CT after transcatheter arterial chemoembolization as a gold standard, the sensitivity of MR imaging for detecting intrahepatic metastases was compared with that of CT. RESULTS: Of the 242 nodules, 225 were diagnosed as hepatocellular carcinomas by iodized-oil CT. Of these, dynamic MR imaging and early-phase CT were significantly superior to those of spin-echo MR imaging (p < .0001) and delayed phase CT (p < .0001) for tumors less than 1 cm in diameter. CONCLUSION: Dynamic MR imaging and early-phase CT of the liver are the most sensitive noninvasive means of detecting small intrahepatic metastases of hepatocellular carcinoma before and after treatment.

Carcinoma, Hepatocellular↗
PubMed1996

CT and MR imaging of abdominal liposarcoma.

OBJECTIVE: CT and MR images were reviewed to correlate the histologic subtypes of abdominal liposarcoma with the radiologic findings. SUBJECTS AND METHODS: Ten patients with liposarcoma who underwent CT or MR imaging before surgery were included in this study. CT and MR imaging findings for these patients were compared retrospectively with histologic findings. RESULTS: Major histologic subtypes found in our group of patients were five well-differentiated, three myxoid, one pleomorphic, and one round-cell liposarcomas. The well-differentiated subtype consisted of lipoma-like and/or sclerosing components. The predominant attenuation and signal intensity characteristics of the lipoma-like components on CT and MR images resembled those of fat, whereas the predominant attenuation and signal intensity characteristics of the sclerosing components resembled those of muscle. The myxoid subtype showed, on unenhanced images, predominant attenuation and signal intensity characteristics that resembled those of water; on contrast-enhanced images, this subtype showed gradual reticular enhancement. The appearance of the round-cell and pleomorphic subtypes was that of heterogeneous, nonfatty tumors. Their characteristics were indistinguishable from those of other malignant soft-tissue masses. CONCLUSION: Each histologic subtype of abdominal liposarcoma showed different CT attenuation or MR imaging signal intensity characteristics. A clear understanding of these findings should prove helpful in the diagnosis of liposarcoma.

Abdominal Neoplasms↗