Biomedical subjects

Y Murakami

Publications and source records attributed to Y Murakami.

At least 613 records · Page 34Linked to original sources

PubMed1993

N-acetyl-D-galactosamine inhibits TNF-alpha gene expression induced in mouse peritoneal macrophages by fimbriae of Porphyromonas (Bacteroides) gingivalis, an oral anaerobe.

Adherence to host cells is an essential step in the initiation of most infectious diseases. It is well known that bacterial fimbriae may be involved in the adherence. Porphyromonas (Bacteroides) gingivalis is a pathogenic organism of adult periodontitis which is a chronic inflammatory disease. Using an experimental system for fimbria-induced TNF-alpha gene expression in mouse peritoneal macrophages, we examined the role of sugar moieties in the adhesion of P. gingivalis fimbriae to these cells. The fimbriae strongly induced TNF-alpha gene expression in the macrophages, and marked TNF activity toward fibroblasts was observed in culture supernatants of the fimbria-treated cells. The potent expression of TNF-alpha was inhibited by N-acetyl-D-galactosamine, but not inhibited by D-mannose, alpha-lactose, and alpha-L-rhamnose, D-galactose, and N-acetyl-D-glucosamine.

Acetylgalactosamine↗

PubMed1993

[Subtraction and dynamic MR images of breast cancer].

The purpose of this study was to evaluate the diagnostic effectiveness of subtraction and dynamic MR imaging in patients with breast masses. In 23 breast cancers and six fibroadenomas, spin echo T1 images were obtained at 0.2 Tesla before and every minute after the intravenous injection of Gd-DTPA (0.1 or 0.2 mmol/kg). Subtraction images were obtained sequentially on the CRT monitor. All breast masses were enhanced after gadolinium and stood out as bright lesions on subtraction images. The tumor margin and its extension were more precisely evaluated on subtraction MR images than on conventional postcontrast MR images. Breast cancer showed a characteristic time-intensity curve with an early peak, in contrast to fibroadenoma, which showed a gradual increase in signal intensity. Subtraction MR imaging is a simple method for the evaluation of breast masses, and further, the time-intensity curve obtained by dynamic study is helpful in the differential diagnosis of lesions.

Adenofibroma↗

PubMed1993

Interleukin-4 and -5 as modulators of nerve growth factor synthesis/secretion in astrocytes.

To examine the regulation of nerve growth factor (NGF) gene expression with respect to neural trauma, we examined the effects of T cell-derived lymphokines on NGF synthesis/secretion in cultured mouse astrocytes. Interleukin (IL)-4 and IL-5 significantly increased the amount of NGF secreted by astrocytes, whereas IL-2, IL-3, and IL-6 had no significant effect. IL-4 and IL-5 produced marked increases in NGF mRNA levels in astrocytes as demonstrated by the reverse transcription-polymerase chain reaction (RT-PCR) method. The effect of IL-4 and IL-5 was greater in quiescent astrocytes than in growing cells. Neither increase in thymidine incorporation nor any morphological change was observed during the treatment with IL-4 and IL-5. The stimulatory effect of IL-4 and IL-5 on NGF synthesis was completely inhibited by the addition of anti-IL-4 monoclonal antibody and anti-IL-5 monoclonal antibody, respectively. The results indicate that IL-4 and IL-5 specifically trigger a cascade of events to regulate NGF synthesis in astrocytes, independent of cell growth.

Animals↗

PubMed1993

Supramolecular effects and molecular discrimination by macrocyclic hosts embedded in synthetic bilayer membranes.

Hybrid assemblies were prepared in combinations of a synthetic lipid, involving an L-alanine residue interposed between an anionic head group and a hydrophobic double-chain segment, with cage-type cyclophanes having a three-dimensionally extended hydrophobic cavity. Incorporation behavior of the cage-type hosts into the multi- and single-walled vesicules was characterized by highly sensitive differential scanning calorimetry and dynamic light-scattering measurements as well as by gel-filtration chromatography and electronic absorption spectroscopy. Both hosts were found to be completely incorporated into a relatively polar domain close to the vesicular surface. Anionic guest molecules, such as naphthol yellow S, dimethylsulfonazo III, bromopyrogallol red, and orange G, were effectively incorporated into the hydrophobic cavities provided by the cage-type cyclophanes embedded in the single-walled bilayer membrane, as confirmed by circular dichroism spectroscopy; the formation constants for 1:1 host-guest complexes were in the order of 10(4)-10(5) mol.dm-3. This means that the binding affinities of the cage-type hosts are largely retained even when the hosts are incorporated into the vesicle. Moreover, the pyridinium moieties bound to the chiral L-valine residues in the bridging components of the hosts underwent conformational changes upon inclusion of the guest, as confirmed by circular dichroism spectroscopy and molecular mechanics and dynamics calculations.

Alanine↗

PubMed1993

Sugar-binding sites with specificity for glucosamine in the guinea pig middle ear mucosa.

Glucosamine-binding sites were detected in Lowicryl K4M-embedded guinea pig middle ear mucosa by electron microscopy, using glucosaminyl bovine serum albumin. Incubation of ultrathin tissue sections with gold-labeled glucosaminyl bovine serum albumin (GlcN/BSA/gold) resulted in binding mainly on cilia, microvilli, rough endoplasmic reticulum and nuclei. The sugar binding was not inhibited after ultrathin sections had been digested with trypsin or neuraminidase. Various carbohydrates and glycoconjugates were tested as competitive inhibitors of GlcN/BSA/gold labeling on the tissue sections. The sugar specificity range detected by the glucosamine-binding sites included glucosamine, N-acetylglucosamine, mannose and fucose, whereas N-acetylgalactosamine, galactose and glucose were not detectable. A series of endotoxic substances such as Salmonella minnesota Re595 lipid A complex with BSA and lipopolysaccharides (LPS) derived from Escherichia coli 055:B5 or S. minnesota Re595 also competed with GlcN/BSA/gold binding. This indicates that the lipid A backbone glucosamine or other carbohydrate portions of LPS is a part of the structure recognized by glucosamine-binding sites.

Animals↗

PubMed1993

A study on postoperative enteritis caused by methicillin-resistant Staphylococcus aureus.

We investigated the production of staphylococcal enterotoxin (SE) with respect to coagulase types by methicillin-resistant Staphylococcus aureus (MRSA). A total of 138 strains of MRSA, which were isolated from clinical materials in the surgical ward between 1983 and 1990, were studied. Coagulase type IV strains produced SE A only, whereas coagulase type II strains were classified into four groups by SE production: SE B producing strains (32.7%), SE C producing strains (29.8%), SE B and C coproducing strains (12.5%), and SE A and C coproducing strains (25.0%). Almost all of the organisms (nine of ten) which were isolated from the feces of patients with MRSA enteritis were SE A and C coproducing strains. The coincidence in time of the prevalence of MRSA enteritis and the isolation SE A and C coproducing strains also demonstrated that these strains caused MRSA enteritis. Although SE C producing strains and SE A and C coproducing strains were simultaneously prevalent in 1990, the former tended to be sensitive while the latter tended to be resistant to minocycline. Considering the variety of antibiotic sensitivity in coagulase type II strains, it is thus considered to be of critical importance for epidemiologic purposes to further characterize isolates by SE typing.

Aged↗

PubMed1993

Mucin-producing pancreatic tumors: a study of nuclear DNA content by flow cytometry.

Nuclear DNA content in eight surgically resected mucin-producing pancreatic tumors (MPPT) consisting of two mucinous intraductal adenocarcinomas (MIDAC), two mucinous intraductal adenomas (MIDA), one mucinous cyst-adenocarcinoma (MCAC), and three mucinous cystadenomas (MCA) were measured by flow cytometry using paraffin-embedded tissue samples. The technique of Shutte was used for the preparation of paraffin-embedded tissue into single dissociated nuclei, while the method of Vindelov was used for staining the isolated nuclei with propidium iodine. Clinicopathologically, the four patients with MIDAC or MIDA were all male and had cystic lesions with a dilated pancreatic duct at the head of the pancreas, while the four patients with MCAC or MCA were all females and had cystic tumors at either the body or tail of the pancreas. All eight patients with MPPT had no metastasis to the regional lymph nodes and were all still alive without recurrence. In an analysis of nuclear DNA content, seven of eight patients had DNA diploid tumors while one patient with a MIDAC perforating the duodenum and choledochus had a DNA aneuploid tumor. Thus, these findings suggest that DNA diploid patterns in MPPT might be associated with a favorable prognosis in MPPT although some patients whose MPPT invaded the surrounding organs might have DNA aneuploid tumors.

Adenocarcinoma, Mucinous↗

PubMed1993

Failure of treatment with alpha-difluoromethylornithine against secondary multilocular echinococcosis in mice.

In AKR/J mice inoculated intraperitoneally with protoscoleces of Echinococcus multilocularis, the oral administration of alpha-difluoromethylornithine (DFMO) in drinking water had no obvious effect on the development of hydatid cysts. The DFMO treatment also caused no apparent depletion of three major polyamines (putrescine, spermidine, and spermine) in the cysts, although a slight reduction in the putrescine level was detected. The failure of DFMO treatment to reduce the growth of cysts in mice may result from the absence of ornithine decarboxylase in the parasite.

Animals↗

PubMed1993

Frameless isocentric stereotactic laser beam guide for image-directed microsurgery.

We have developed a frameless stereotactic multi-articulated arm suitable for image-directed microsurgery and surgical navigation. The system comprises a frameless isocentric mechanism and a three-dimensional (3 D) digitizer for intra-operative monitoring. Five joints of our multi-articulated arm are equipped with electromagnetic clutches, and the arms are provided with counterbalancing weights to ensure safe, smooth movement. Stereotactic microsurgical procedures were carried out with a laser beam guide mounted at the tip of the isocentric arm. We have used this system in 22 cases to resect tumours or epileptic foci. There were 12 cases of glioma, 5 cases of deep seated benign tumours, 3 cases of multiple metastatic tumours, and 2 cases of temporal lobe epilepsy. Postoperative enhanced CT images indicated total or subtotal resection in all cases. We also have used this system to determine the approach for clipping of a posterior cerebral artery aneurysm in 2 cases. The error of mechanical accuracy of the system was less than 1 mm. We believe that this system will prove useful in image-directed microsurgical procedures.

Brain Mapping↗

PubMed1993

Cellular responses of guinea-pig macrophages to C4a; inhibition of C3a-induced O2- generation by C4a.

We have investigated the cellular responses of guinea-pig macrophages to human C4a. C4a induced a biphasic Ca2+ mobilization; a rapid temporary Ca2+ mobilization from intracellular Ca2+ pool followed by a weak Ca2+ influx of extracellular Ca2+. Although the C4a-treated macrophages did not respond again to C4a, that is, desensitization to C4a, the C4a-desensitized macrophages still responded to C3a to induce a Ca2+ mobilization. Furthermore, C4a failed to inhibit [125I]-C3a binding to macrophages, suggesting that C4a receptors are different from C3a receptors. In contrast to C3a, C4a-induced Ca2+ mobilization didn't link to O2- generation but inhibited the C3a-induced O2- generation. These results suggest that C4a binds to a specific C4a receptor on guinea-pig macrophages to down-regulate the C3a receptor-mediated O2- generation in macrophages.

Animals↗

PubMed1993

Comparison of K-ras oncogene activation in pancreatic duct carcinomas and cholangiocarcinomas induced in hamsters by N-nitrosobis(2-hydroxypropyl)amine.

The presence of K-ras point mutations in pancreatic duct carcinomas and cholangiocarcinomas induced by N-nitrosobis(2-hydroxypropyl)amine (BHP) in Syrian hamsters was investigated by single-strand conformation polymorphism analysis of polymerase chain reaction products from frozen fresh materials in order to clarify the K-ras mutation rates in those two carcinomas induced simultaneously by one carcinogen, BHP. In the examined pancreatic duct carcinomas, 10 out of 16 were positive for a mutation in codon 12 while 3 out of 12 cholangiocarcinomas demonstrated mutation of K-ras gene. G-to-A transition was detected in the second position of codon 12 in both pancreatic carcinomas and cholangiocarcinomas. These results suggest that the role of genetic alteration in carcinogenesis may differ with the target organ, even when initiation is with the same carcinogen.

Animals↗

PubMed1993

Mechanical stimulation by toothbrushing increases oxygen sufficiency in human gingivae.

We studied the immediate effect of mechanical stimulation with a toothbrush on oxygen sufficiency in human gingivae. Teeth were brushed with a modified Bass technique at various forces (100, 200, and 300 g) for various times (5, 10, and 30 s). Hemoglobin (Hb) oxygen saturation was measured before and intermittently for 60 min after brushing, by non-invasive tissue reflectance spectrophotometry. Hb oxygen saturation increased within a few min after brushing and then slowly returned to the initial level. Toothbrushing at 200 g for 10 s caused the longest-lived increase in Hb oxygen saturation; saturation remained about 6% above the baseline level for more than 25 min. Before brushing, Hb oxygen saturation was significantly lower in inflamed gingivae than in healthy gingivae (p < 0.05). After brushing of inflamed gingivae, the Hb oxygen saturation almost reached the level measured in healthy gingivae before brushing. These findings suggest that stimulation with a toothbrush increases oxygen sufficiency in both healthy and inflamed gingivae.

Adolescent↗

PubMed1993

[Effect of erythromycin on anti staphylococcal activity and dye production of Pseudomonas aeruginosa isolated from clinical materials].

Anti staphylococcal activity by Pseudomonas aeruginosa was investigated through the use of the reversed agar plate and the filter paper stamp methods. Investigation was also conducted on the dye production of different clinical isolates of Pseudomonas aeruginosa, the relationship between drug susceptibility and anti staphylococcal activity, and the influence of erythromycin on anti staphylococcal activity. Seventy four strains of Pseudomonas aeruginosa were prepared which included 20 strains from pus, 34 strains from sputum and 20 strains from urine. These were then inoculated with methicillin resistant Staphylococcus aureus (MRSA). They were then cultured for 48 hours by using the reversed agar plate and the filter paper stamp methods. Anti staphylococcal activity was observed in 16 strains from pus (80%), 19 strains from sputum (55.9%) and 8 strains from urine (40%). The Pseudomonas aeruginosa strains which have no pigment tended to show poor anti staphylococcal activity. Drug susceptibility was tested using PIPC, AMK, IPM, CFS and OFLX. The strains which showed resistance to OFLX tended to show poor anti staphylococcal activity. Erythromycin inhibited the dye production of Pseudomonas aeruginosa but exhibited no effect on anti staphylococcal activity. Consequently, these results suggest erythromycin has exhibited a previously unknown pharmacological effect, furthermore, anti staphylococcal activity was not caused by pigmentation only.

Erythromycin↗

PubMed1993

Atypical form of atrioventricular septal defect without left axis deviation: relation between morphology and unusual QRS axis.

OBJECTIVE: To clarify the morphological features relating to an intermediate axis or a right axis deviation in atrioventricular septal defect (AVSD). SUBJECTS: 135 patients with typical AVSD and with nine patients with atypical AVSD, characterised by a well formed atrial septum, a milder downward displacement of the atrioventricular valves, and a shorter length of the ostium primum defect. MAIN OUTCOME MEASURES: Relation between morphology and electrocardiographic and vectorcardiographic findings; prevalence of Down's syndrome and of other cardiac anomalies. RESULTS: All nine patients with atypical AVSD had an unusual mean frontal QRS axis compared with six of the 135 patients (4%) with typical AVSD (p < 0.01). All eight patients who underwent the vector analyses showed atypical movement of the QRS loop--that is, an initial left inferior movement in the frontal loop (eight patients) and counter-clockwise rotation in the sagittal loop (seven). The corresponding values for 119 patients with typical AVSD were 20 and 22 patients (p < 0.01). Seven patients with atypical AVSD (78%) and 55 (41%) with typical AVSD had Down's syndrome (p < 0.05). None of the twenty one patients with additional cardiac anomalies had atypical AVSD, an unusual QRS axis, or unusual movement in the QRS loop. CONCLUSIONS: The atypical morphology, supposedly related to the degree of posteroinferior displacement of the conduction system, was one of the causes of unusual movement of the QRS loop in AVSD.

Adolescent↗

PubMed1993

Multiple arterial stenoses of unknown aetiology in the coronary, cerebral, and brachial arteries.

A 13 year old girl with multiple arterial stenoses of unknown aetiology is described. At the age of seven months she was noted to have cardiomegaly and diminished left ventricular ejection fraction with no cardiac anomaly. Cardiac function gradually improved and her condition remained satisfactory until she was 11 years old when multiple lesions in the coronary, cerebral, and left brachial arteries were diagnosed. Histological examination of an endomyocardial biopsy specimen from the right ventricle showed hypertrophic muscles surrounded by abundant fibrous tissue. Percutaneous transluminal angioplasty of the right coronary stenoses led to complete occlusion.

Arterial Occlusive Diseases↗

PubMed1993

Effect of human galanin on growth hormone prolactin, and antidiuretic hormone secretion in normal men.

Galanin is a brain-gut peptide occurring widely in the central and peripheral nervous system. Effects of iv administration of synthetic human galanin on pituitary GH, PRL, and antidiuretic hormone secretion were studied. Intravenous infusion of the peptide resulted in a significant increase in plasma GH levels whereas PRL and antidiuretic hormone did not significantly change. These findings suggest that galanin might play a role in modulating GH secretion in humans.

Adult↗

PubMed1993

Characterization of factors that suppress linear DNA replication in SV40 in vitro replication system.

The in vitro simian virus 40 (SV40) replication system has been developed as a model system of cellular DNA replication, because the replication initiated from the replication origin of SV40 and replication fork proceeds bidirectionally. In this system, SV40 T-antigen (TAg) is the only factor provided by viral genes, while all other factors are supplied by the host cells. A suppression of replication has been observed in the linear template containing SV40 replication origin, compared with the closed circular template in the SV40 in vitro replication system using a crude extract of HeLa cells. However in the in vitro replication system reconstituted from partially purified factors, less preference was observed for the replication of the closed circular DNA over the linear DNA. In a mono-polymerase system supplemented by crude extracts, a suppression of replication in a linear template was also observed, when compared with a closed circular template. This suppression effect of crude extract was abolished by heat treatment, suggesting that the suppression was induced by some protein factors. A crude extract of HeLa cells was fractionated by stepwise elution with buffers containing 0.2 M, 0.4 M, 0.6 M and 1 M NaCl on a phosphocellulose column, and characterization of factors that suppress linear DNA replication has been done. Both fractions that were eluted at 0.4 M and 0.6 M from phosphocellulose were necessary to suppress linear DNA replication efficiently. The factors in the 0.6 M fraction that suppressed linear DNA replication synergistically with the 0.4 M fraction were partially purified by successive chromatography with heparin-sepharose and dsDNA-cellulose followed by glycerol gradient centrifugation. These results suggested that multiple factors are required to suppress DNA replication of the linear template.

Cell Fractionation↗

PubMed1993

Mapping of the 70 kDa, 34 kDa, and 11 kDa subunit genes of the human multimeric single-stranded DNA binding protein (hSSB/RPA) to chromosome bands 17p13, 1p35-p36.1, and 7p21-p22.

Human single-stranded DNA binding protein (hSSB/RPA) is a multimeric single-stranded DNA binding protein consisting of three subunits of 70 kDa, 34 kDa, and 11 kDa. Human SSB was isolated from HeLa cells as an essential factor for the in vitro replication of simian virus 40 DNA. We and others have isolated and sequenced cDNAs for each subunit of the SSB. The chromosome on which each gene is located was determined through the analysis of a panel of human/hamster somatic cell hybrids using the polymerase chain reaction with pairs of synthetic oligonucleotide primers from the 3'-untranslated sequences of the genes. Genomic clones for each gene were isolated from a genomic cosmid library prepared from human lymphoblastoid cells. Using those clones as probes, we have carried out fluorescence in situ hybridization to human metaphase chromosomes and have mapped the 70 kDa subunit gene to 17p13, the 34 kDa subunit gene to 1p35-p36.1, and the 11 kDa subunit gene to 7p21-p22. Since hSSB participates in replication, recombination and repair of DNA, the physical mapping of hSSB genes may aid in the identification of human hereditary diseases associated with aberrant DNA reactions caused by genetic alterations of the hSSB.

Animals↗