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Biomedical subjects

M Y Liu

Publications and source records attributed to M Y Liu.

At least 145 records · Page 8Linked to original sources
PubMed1990

Allogeneic bone marrow transplantation for the treatment of leukemia.

Eighteen patients with leukemia have received HLA-identical allogeneic bone marrow transplantation (BMT) at our hospital since 1981. Fifteen of these patients have been living without relapse. for prophylaxis of GVHD, MTX was used in 8 patients, and cyclosporine (CSP) together with MTX in 6 patients, 3 received multiple agents at much smaller dosage, including monoclonal antibody. All patients received intravenous placental gamma-globulin, and 16 received garlic extract. Three patients died. One, who neither received MTX, nor CSP died of hyperacute GVHD, one who did not receive garlic extract died of GMV pneumonia, and the third one died of tuberculosis 18 months after BMT.

Adolescent↗
PubMed1990

Duodenal ulcer hemorrhage with and without dyspepsia.

To clarify the clinical significance of dyspepsia in patients with bleeding duodenal ulcer, we studied 298 patients prospectively. Ages of patients ranged from 16 to 81 yr (mean 45.9). There were 244 (82%) dyspeptic and 54 (18%) nondyspeptic patients. In the dyspeptic group, significantly more patients were taking nonsteroidal anti-inflammatory drugs. In the nondyspeptic group, there was a higher percentage of patients with duodenal bulb deformity (p less than 0.005), which deformity was related to previous peptic ulcer disease. The age, sex, past history of dyspepsia or bleeding, consumption of alcohol and cigarettes, and the hospital course of the two groups of patients did not differ significantly. Our results show that the clinical course of duodenal ulcer hemorrhage is not significantly different in patients with or without dyspepsia, and indicate that bleeding and dyspepsia probably are two independent presentations in the natural course of the disease. The significance of the correlation between dyspepsia and duodenal bulb deformity is discussed.

Adolescent↗
PubMed1990

[Etiology of intestinal obstruction--4 years' experience].

In order to find out the etiological patterns of intestinal obstruction, we reviewed 1205 cases diagnosed as intestinal obstruction at our hospital. The operative findings, locations of obstruction and pathological results were analyzed among 707 cases who were operated on. The most common cause of colon obstruction was tumor (78.7%). The etiologies of small intestinal obstruction were: adhesions, 47.4%; hernia, 22.1%; tumor, 11.8%; intussusception, 8.8%; foreign bodies, 3.7%; and miscellaneous causes, 6.2%. In the patients older than 40 years, the most common causes of intestinal obstruction were adhesion and malignancy, in contrast to hernia and intussusception that were commonly found in children. The mean age of the patients with colon obstruction was older than those with small bowel obstruction, 55.7 +/- 21. vs 39.4 +/- 17.3 (P less than 0.001). Of the patients with previous abdominal surgery, adhesions caused the obstruction in up to 60.5%. Among the 102 cases who had been operated for abdominal malignancy, the cause of intestinal obstruction was due to recurrent tumor in 78 patients (76.4%). Of patients without previous abdominal surgery, the etiologies of intestinal obstruction were: incarcerated hernia, 36.7%; tumor, 21.1%; intussusception, 15.6%; and adhesion, 13.8%. The incidence of strangulation obstruction was 25.7%, of which the major causes were adhesions, 51.7%; and hernia. 43.0%. We concluded that the most common cause of colon obstruction was tumor. The two most common causes of small intestinal obstruction were adhesions and hernia. Age and past history of abdominal surgery can much help for the differential diagnosis.

Adolescent↗
PubMed1989

Antibody to Epstein-Barr virus-specific DNase as a marker for field survey of patients with nasopharyngeal carcinoma in Taiwan.

A serological survey using antibody to Epstein-Barr virus (EBV)-specific DNase activity as a marker for the identification of patients with nasopharyngeal carcinoma (NPC) has been carried out on healthy subjects who visited Government Employees' Clinic Center (GECC) for routine health examination and on individuals residing in NPC high-risk areas (HRA) in Taiwan. During a 3-year prospective study, 22,596 and 9,869 sera were collected from the GECC and HRA groups, respectively. Taking neutralization of 2 or more units of EBV DNase activity as a positive response, the positivity rates in the GECC and HRA groups were 5.4% and 11.92%, respectively. Among the antibody-positive individuals, three cases of NPC were found in the GECC group (detection rate 0.63%) and 11 in the HRA group (detection rate 1.32%). A further patient at stage III of the disease was found in the first year of following up of 1,005 antibody-positive individuals. Among the 12 NPC patients in the HRA, five were newly diagnosed as having stage II (three patients) and stage III (two patients) NPC. These results support the hypothesis that antibody against EBV-specific DNase activity may be a useful marker for detection of patients with NPC, and they imply that individuals having high levels of antibody to EBV DNase activity may have an increased risk of development of NPC.

Adult↗
PubMed1989

Antibody against Epstein-Barr virus DNA polymerase activity in sera of patients with nasopharyngeal carcinoma.

A salt-dependent DNA polymerase activity was demonstrated in the culture of an EBV-producing, lymphoblastoid cell line (NPC-204 cells) treated with 5-iodo-2'-deoxyuridine (IUdR). There was a high frequency of levels of antibody to this enzyme in sera of patients with nasopharyngeal carcinoma (NPC). In contrast, sera from healthy subjects had little or no neutralizing activity. The high antibody level appeared as early as stage 1 of the disease in many NPC patients. The levels of the antibody increased with the progression of the disease and declined in treated patients. The results strongly suggest that tests measuring serum antibody against EBV DNA polymerase activity can be used for early diagnosis and prognosis of NPC.

Antibodies, Viral↗
PubMed1989

Cytochrome c peroxidase activity of a protease-modified form of cytochrome c-552 from the denitrifying bacterium Pseudomonas perfectomarina.

Protease activity present in aerobically grown cells of Pseudomonas perfectomarina, protease apparently copurified with cytochrome c-552, and trypsin achieved a limited proteolysis of the diheme cytochrome c-552. That partial lysis conferred cytochrome c peroxidase activity upon cytochrome c-552. The removal of a 4000-Da peptide explains the structural changes in the cytochrome c-552 molecule that resulted in the appearance of both cytochrome c peroxidase activity (with optimum activity at pH 8.6) and a high-spin heme iron. The oxidized form of the modified cytochrome c-552 bound cyanide to the high-spin ferric heme with a rate constant of (2.1 +/- 0.1) X 10(3) M-1 s-1. The dissociation constant was 11.2 microM. Whereas the intact cytochrome c-552 molecule can be half-reduced by ascorbate, the cytochrome c peroxidase was not reducible by ascorbate, NADH, ferrocyanide, or reduced azurin. Dithionite reduced the intact protein completely but only half-reduced the modified form. The apparent second-order rate constant for dithionite reduction was (7.1 +/- 0.1) X 10(2) M-1 s-1 for the intact protein and (2.2 +/- 0.1) X 10(3) M-1 s-1 for the modified form. In contrast with other diheme cytochrome c peroxidases, reduction of the low-spin heme was not necessary to permit ligand binding by the high-spin heme iron.

Amino Acid Sequence↗
PubMed1989

[Study on leukemic-colony forming unit in 31 patients with acute non-lymphocytic leukemia].

Thirty-one patients with acute non-lymphocytic leukemia (ANLL) were studied with Dicke's soft agar marrow culture to identify leukemic colony forming units. Eighteen of them had leukemic colony formation, in those patients, the average survival period was shorter (65d), and none of them achieved remission after chemotherapy. The remaining thirteen patients had no colony formation and had a longer survival period of 119.8 d. In the latter group four out of six who had undergone more than two courses of chemotherapy went into complete remission. Our study showed that patients who had leukemic colony formation had a worse prognosis than those who had no leukemic colony formation.

Adolescent↗
PubMed1989

[Study on the biological nature of ginseng pearl knot].

Pearl knots of the root system of cultivated ginseng in different ages and different development stages were studied and compared with wild ginseng. It has been found that the biological nature of pearl knots is the foundation of seasonal absorbing root of ginseng. It is pointed out that to remove the cold-proof matter later and keep suitable soil water in spring are important to prevent cold injury and promote growth of root system of ginseng. Key words ginseng; pearl knot; seasonal absorbing root

Panax↗
PubMed1989

[Low-dose cytosine arabinoside in treatment of 17 patients with acute nonlymphocytic leukemia].

Low dose Ara-C (LDAra-C, Ara-C 10-15 mg/12 h, i.m. x 14-21 days) was used in the treatment of 17 patients with ANLL, and from 14 patients blast cells were isolated before chemotherapy and cultured in the presence of Ara-C (10(-8) and 10(-7) mol/L), no definite induction of differentiation of leukemic cells was found. Of the 17 cases, 5 obtained CR, only one of them with M4 entered CR without pancytopenia or bone marrow aplasia during the LDAra-C treatment. For the rest, 4 with M2 obtained PR, and 8 did not respond. Toxic effects, including pancytopenia and bone marrow aplasia, were observed in most of the patients. Laboratory results showed that differentiation was not induced by Ara-C in low concentration in in vitro culture. LDAra-C is thought to be effective in the treatment of ANLL, and the mechanism may involve both the cytotoxicity and the induction of differentiation of leukemic cells, but the former is far more important.

Adolescent↗
PubMed1988

Spectroscopic characterization of a high-potential monohaem cytochrome from Wolinella succinogenes, a nitrate-respiring organism. Redox and spin equilibria studies.

When purified, a high-potential c-type monohaem cytochrome from the nitrate-respiring organism, Wollinella succinogenes (VPI 10659), displayed a minimum molecular mass of 8.2 kDa and 0.9 mol iron and 0.95 mol haem groups/mol protein. Visible light spectroscopy suggested the presence of an equilibrium between two ligand arrangements around the haem, i.e. an absorption band at 695 nm characteristic of haem-methionine coordination (low-spin form) coexisting with a high-spin form revealed by a band at 619 nm and a shoulder at 498 nm. The mid-point redox potential measured by visible redox titration of the low-spin form was approximately +100 mV. Binding cyanide (Ka = 5 x 10(5) M-1) resulted in the displacement of the methionyl axial residue, and full conversion to a low-spin, cyanide-bound form. Structural features were studied by 300-MHz 1H-NMR spectroscopy. In the oxidized state, the pH dependence of the haem methyl resonances (pH range 5-10) and the magnetic susceptibility measurements (using an NMR method) were consistent with the visible light spectroscopic data for the presence of a high-spin/low-spin equilibrium with a transition pKa of 7.3. The spin equilibrium was fast on the NMR time scale. The haem methyl resonances presented large downfield chemical shifts. An unusually broad methyl resonance at around 35 ppm (pH = 7.5, 25 degrees C) was extremely temperature-dependent [delta(323 K) - delta(273 K) = 7.2 ppm] and was assigned to the S-CH3 group of the axial methionine. In the ferrous state only a low-spin form is present. The haem meso protons, the methyl group and the methylene protons from the axial methionine were identified in the reduced form. The resonances from the aromatic residues (three tyrosines and one phenylalanine) were also assigned. Detailed monitoring of the NMR-redox pattern of the monohaem cytochrome from the fully reduced up to the fully oxidized state revealed that the rate of the intermolecular electronic exchange process was approximately 6 x 10(6) M-1 s-1 at 303 K and pH = 6.31. A dihaem cytochrome also present in the crude cell extract and purified to a homogeneous state, exhibited a molecular mass of 11 kDa and contained 2.43 mol iron and 1.89 mol haem c moieties/mol cytochrome. The absorption spectrum in the visible region exhibited no band at 695 nm, suggesting that methione is not a ligand for either of the two haems. Recovery of only small amounts of this protein prevented more detailed structural analyzes.

Bacteroidaceae↗
PubMed1988

Resonance Raman spectra of the copper-sulfur chromophores in Achromobacter cycloclastes nitrite reductase.

Resonance Raman spectroscopy at ambient temperature and 77 K has been used to probe the structures of the copper sites in Achromobacter cycloclastes nitrite reductase. This enzyme contains three copper ions per protein molecule and has two principal electronic absorption bands with lambda max values of 458 and 585 nm. Comparisons between the resonance Raman spectra of nitrite reductase and blue copper proteins establish that both the 458 and 585 nm bands are associated with Cu(II)-S(Cys) chromophores. A histidine ligand probably is also present. Different sets of vibrational frequencies are observed with 457.9 nm (ambient) or 476.1 nm (77 K) excitation as compared with 590 nm (ambient) or 593 nm (77 K) excitation. Excitation profiles indicate that the 458 and 585 nm absorption bands are associated with separate [Cu(II)-S(Cys)N(His)] sites or with inequivalent and uncoupled cysteine ligands in the same site. The former possibility is considered to be more likely.

Alcaligenes↗
PubMed1988

Crystallization of nitrite reductase from Achromobacter cycloclastes.

Crystals of a green copper-containing nitrite reductase from Achromobacter cycloclastes, which diffract to high resolution, belong to the cubic space group P213, with a = b = c = 98.4 A. Crystals of a nitrite reductase from Alcaligenes faecalis S-6 have been made, and belong to space group P212121, with a = 77.3 A, b = 94.6 A and c = 141 A. Crystals of the blue copper protein from Ac. cycloclastes have also been obtained: these belong to space group P21212, with cell dimensions a = 34.9 A, b = 91.1 A and c = 36.7 A (1 A = 0.1 nm).

Alcaligenes↗
PubMed1988

Purification of Vibrio fischeri nitrite reductase and its characterization as a hexaheme c-type cytochrome.

Dissimilatory nitrite reductase was isolated from anaerobically nitrate-grown Vibrio fischeri cells and purified to electrophoretic homogeneity. The enzyme catalyzes the six-electron reduction of nitrite to ammonia. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, under either nonreducing or reducing conditions, the purified nitrite reductase migrated as a single protein band of Mr 57,000. Gel filtration chromatography revealed a native molecular weight of 58,000, indicating the enzyme as isolated to be present in the monomeric form. Purified nitrite reductase exhibited typical c-type cytochrome absorption spectra with the reduced alpha-band at 552.5 nm. Heme content analysis using the purified preparation indicated the enzyme to contain 5.5 heme c groups per molecule. Iron analysis showed the presence of 5.62 g iron atoms per mole of enzyme and no nonheme irons were detected. These results clearly indicate that, similar to the dissimilatory nitrite reductases from Desulfovibrio desulfuricans, Wolinella succinogenes, and Escherichia coli, the V. fischeri nitrite reductase is a hexaheme c-type cytochrome. Amino acid composition of V. fischeri also revealed close similarities to those of the other three hexaheme nitrite reductases previously studied. Based on this information, it is concluded that the four ammonia-forming, dissimilatory nitrite reductases isolated to date represent a homologous group of proteins with the distinct property of being hexaheme c-type cytochromes.

Amino Acids↗
PubMed1988

The antinociceptive role of a bulbospinal serotonergic pathway in the rat brain.

The antinociceptive role of spinal serotonin (5-HT) neurons descending from 5-HT cells near the ventrolateral surface of the medulla oblongata was investigated by stimulating these cells in normal rats, in rats with generalized or selective chemical ablation of 5-HT nerves, and in rats with postsynaptic blockade of 5-HT receptors. Electrical stimulation of the lateral medulla elicited analgesia in normal rats; the increase in pain threshold was proportional to the intensity and to the frequency of stimulation. In addition, microinjection of kainic acid or L-glutamate at the same sites also produced analgesia. However, generalized destruction of CNS 5-HT nerves produced by intraventricular injection of 5,7-dihydroxytryptamine (5,7-DHT) or selective destruction of spinal 5-HT nerves produced by intraspinal injection of 5,7-DHT reduced the magnitude of the antinociceptive responses to electrical stimulation. Postsynaptic blockade of CNS 5-HT receptors produced by intraventricular injection of cyproheptadine also reduced the stimulation-produced analgesia. The specificity of the lesions for 5-HT nerves is demonstrated by the lack of effect on the levels of noradrenaline in the same brain regions. The results indicate that the activity of 5-HT nerve cells adjacent to the ventrolateral surface of the medulla oblongata and projecting to the spinal cord serves to elevate pain threshold.

5,7-Dihydroxytryptamine↗
PubMed1988

Primary intraosseous malignant meningioma of the skull: case report.

Primary intraosseous meningioma of the skull is rare. This report describes a 61-year-old man who was treated by craniectomy 3 times for a repeatedly recurrent primary intraosseous malignant meningioma. Transmission electron microscopy revealed interdigitation of cytoplasmic processes, microfilaments, and distinct desmosomal structures. Immunocytochemical studies of cultured cells showed strong expression of vimentin and weakly positive staining for S-100 protein. Primary intraosseous malignant meningioma should be considered in the differential diagnosis of massive solitary osteolytic lesions of the skull.

Humans↗