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Biomedical subjects

S M Liu

Publications and source records attributed to S M Liu.

At least 73 records · Page 4Linked to original sources
PubMed1996

Immunohistochemical study of Ulex europaeus agglutinin 1 (UEA-1) binding of megakaryocytes in bone marrow biopsy specimens: demonstration of heterogeneity in staining pattern reflecting the stages of differentiation.

During differentiation, megakaryocytes undergo nuclear endoreplication, an increase in cell size, cytoplasmic granulation, and release of platelets. The changes in highly lobulated nuclei with varying degree of polyploidy and increasing cell size are easily recognized morphologically. However, the actual cytoplasmic changes are more difficult to perceive morphologically. With the peroxidase-antiperoxidase (PAP) method using UEA-1 as the binding protein to the alpha-L-fucose of glycoprotein synthesized by megakaryocytes, we observed significant variation in cytoplasmic staining of megakaryocytes in routinely processed bone marrow biopsy sections. A total of 3344 megakaryocytes in bone marrow sections from 10 patients with nonhematologic diseases and from 10 patients with idiopathic thrombocytopenic purpura (ITP) was studied. According to the intensity and pattern of cytoplasmic staining, we divided megakaryocytes into at least six groups: (1) low granular (LG), (2) diffuse granular (DG), (3) diffuse dense granular (DDG), (4) marginal granular (MG), (5) denuded (DMK), and (6) endomitotic (EndoM). Most of the megakaryocytes were DG (mean, 42.75% +/- 19.21%) and DDG (mean, 50.25% +/- 21.23%). In correlation with nuclear morphology and cell size, it appears that substances binding to UEA-1 are located in the paranuclear region in early megakaryocytes and produce a low granular focal staining pattern (LG cells). Next, the granules spread throughout the cytoplasm (DG cells) and increase in quantity (DDG). This is followed by migration of granules to the periphery of the cytoplasm (MG cells) and is associated with the liberation of platelets and eventual formation of DMK megakaryocytes. Endomitosis, regulated by unknown factors, occurred in the MG stage. In comparing the group with nonhematologic disease (mean DG, 35.4% +/- 18.48%; DDG, 58.4% +/- 21.8%) and the group with ITP (mean DG, 50.1% +/- 17.82%; DDG, 42.1% +/- 18.12%), we found an increasing proportion of DG megakaryocytes in ITP, which suggests a left-shifted maturation of megakaryocytes. By understanding the staining pattern seen in the different stages of megakaryocytic differentiation, UEA-1 staining may be a practical method for studying megakaryocytopoiesis in routinely processed paraffin sections of bone marrow biopsy samples.

Biopsy↗
PubMed1996

Non-small cell lung cancer with testicular metastasis: a case report.

A 51-year-old man was diagnosed to have non-small cell lung cancer, right middle lobe, with multiple bony metastasis. Systemic chemotherapy with the regimens of cisplatin plus etoposide was administered. A 2 x 2.5 cm firm nodule in the right testis was incidentally found two weeks after the first course of chemotherapy. Transinguinal right radical orchiectomy was performed. Pathologic examination revealed a picture similar to his lung cancer. Secondary carcinoma of the testis is extremely rare. The relevant literature about its incidence, clinical manifestations, sources of primary tumor and routes of metastasis are reviewed.

Carcinoma, Non-Small-Cell Lung↗
PubMed1995

Cloning and identification of amino acid residues of human phospholipase C delta 1 essential for catalysis.

In vitro single point mutagenesis, inositol phospholipid hydrolysis, and substrate protection experiments were used to identify catalytic residues of human phosphatidylinositide-specific phospholipase C delta 1 (PLC delta 1) isolated from a human aorta cDNA library. Invariant amino acid residues containing a functional side chain in the highly conserved X region were changed by in vitro mutagenesis. Most of the mutant enzymes were still able to hydrolyze inositol phospholipid with activity ranging from 10 to 100% of levels in the wild type enzyme. Exceptions were mutants with the conversion of Arg338 to Leu (R338L), Glu341 to Gly (E341G), or His356 to Leu (H356L), which made the enzyme severely defective in hydrolyzing inositol phospholipid. Phospholipid vesicle binding experiments showed that these three cleavage-defective mutant forms of PLC delta 1 could specifically bind to phosphatidylinositol 4,5-bisphosphate (PIP2) with an affinity similar to that of wild type enzyme. Western blotting analysis of trypsin-treated enzyme-PIP2 complexes revealed that a 67-kDa major protein fragment survived trypsin digestion if the wild type enzyme, E341G, or H356L mutant PLC delta 1 was preincubated with 7.5 microM PIP2, whereas if it was preincubated with 80 microM PIP2, the size of major protein surviving was comparable to that of intact enzyme. However, mutant enzyme R338L was not protected from trypsin degradation by PIP2 binding. These observations suggest that PLC delta 1 can recognize PIP2 through a high affinity and a low affinity binding site and that residues Glu341 and His356 are not involved in either high affinity or low affinity PIP2 binding but rather are essential for the Ca(2+)-dependent cleavage activity of PLC.

Amino Acid Sequence↗
PubMed1995

Determination of heavy metals distribution in the anoxic sediment slurries by chemical sequential fractionation.

An analytical procedure involving chemical sequential fractionation was used for quantification of partitioning of some metals (Cu, Cr, and Cd) in anoxic sediment slurries (10 or 20% w/v) into six fractions. These fractions include exchangeable, bound to carbonate, easily reducible, moderately reducible, bound to organic, and residue fractions. Low amounts of Cu (10-11%) and moderate amounts of Cr (38%) and Cd (38-39%) were retained as the easily reducible and moderately reducible fractions which represented the mobile forms of metals in the sediments. The amendment of different amounts (20 or 100 mg/liter) of metals into the anoxic sediment slurries (10% w/v) resulted in a different percentage distribution of metals into six fractions. The amount of Cd in the carbonate fraction increased significantly after Cd amendment. The percentage of Cu or Cr in the easily reducible and moderately reducible fractions increased, while those in the residual fraction decreased as the amount of Cu or Cr amended into the sediment slurries increased.

Cadmium↗
PubMed1995

Effects of hydrogen peroxide and phorbol myristate acetate on endothelial transport and F-actin distribution.

We have previously reported that both hydrogen peroxide (H2O2) and phorbol myristate acetate (PMA) can stimulate endocytosis in bovine aortic endothelial cells. Moreover, we have found that redistribution of filamentous actin (F-actin) in a low concentration of cytochalasin B also increases such endocytic activity. In the present study, the effects of H2O2 and PMA on endothelial transport and F-actin distribution were studied in bovine aortic endothelial monolayers. A low concentration of H2O2 (10(-5) M) had no effect on permeability, but did cause redistribution of F-actin, i.e., the diffuse arrangement of filaments changed to a clear stress-fiber pattern, but the dense peripheral filament bands were not affected. A 10-fold higher concentration of H2O2 (10(-4) M), which increases permeability as we reported previously, caused a disruption of F-actin dense peripheral bands. PMA had a concentration-dependent effect on endothelial permeability and F-actin distribution, i.e., 10(-7) M PMA had no observed effect on permeability and no effect on F-actin structure either, whereas 5 x 10(-7) M PMA caused decreased permeability during the first 1 to 1.5 h and thereafter increased permeability for up to 6 h. There was also a time-dependent reorganization of F-actin structure after the treatment with 5 x 10(-7) PMA: the number of dense peripheral bands increased after 1 h of exposure; these bands had a ruffled appearance after 2 h and were disrupted after 6 h. These results suggest that, in endothelial cells, F-actin plays a role in regulating the width of intercellular junctions and thereby controls the paracellular pathway of vascular permeability.

Actins↗
PubMed1995

Involvement of nitric oxide in permeability alteration and F-actin redistribution induced by phorbol myristate acetate in endothelial cells.

We have previously reported that phorbol myristate acetate (PMA) caused a decrease in endothelial permeability during the first 1 to 1.5 h of exposure and thereafter an increase for up to 6 h. This permeability alteration was correlated with a time-dependent redistribution of F-actin, i.e., an increase in dense peripheral bands was observed during the first hour of PMA incubation and a disruption of the bands after 6 h. In the present study, we found that this PMA-induced alteration of permeability is L-arginine dependent, since the low permeability prevailed for up to 6 h when extracellular L-arginine was available. Moreover, we noted that administration of N-nitro-L-arginine methylester (L-NAME) to PMA-treated cells caused a direct increase in permeability. The redistribution of F-actin induced by PMA was also L-arginine dependent, since the number of dense peripheral bands continued to increase for up to 6 h when extracellular L-arginine was available, and these bands were directly disrupted when L-NAME was added. These results suggest that the tight contact between PMA-treated endothelial cells is maintained by a redistribution of F-actin elicited by the endogenous production of nitric oxide.

Actins↗
PubMed1995

Effects of long-term protein excess or deficiency on whole-body protein turnover in sheep nourished by intragastric infusion of nutrients.

The effect of long-term dietary protein excess and deficit on whole-body protein-N turnover (WBPNT) was examined in lambs nourished by intragastric infusions of nutrients. Ten sheep were given 500 mg N/kg metabolic weight (W0.75) per d from casein for 2 weeks and then either 50 (L), 500 (M) or 1500 (H) mg N/kgW0.75 per d for 6 weeks. Volatile fatty acids were infused at 500 kJ/kgW0.75 per d. Daily WBPNT was measured by continuous intravenous infusion of [1-13C]leucine 3 d before, and on days 2, 21 and 42 after the alteration in protein intake. Whole-body protein-N synthesis (WBPNS) was calculated as the difference between WBPNT and the protein-N losses as urinary NH3 and urea. Whole-body protein-N degradation (WBPND) was then estimated from WBPNS minus protein gain determined from N balance. Fractional rates of WBPNS and WBPND were calculated against fleece-free body N content. WBPNS rates at the L, M and H intakes were respectively 35.1, 41.5 and 63.7 g/d (P < 0.001) on average over the 6 weeks and WBPND rates were 39.5, 41.1 and 56.8 g/d (P < 0.001). The fractional rates of WBPNS were 5.01, 6.37 and 7.73% per d (P < 0.001) while those of WBPND were 5.64, 6.29 and 6.81% per d (P < 0.005) respectively. On days 2, 21 and 42, WBPNS rates at intake H were 54.0, 61.8 and 75.4 g/d (P = 0.03) respectively, and WBPND rates were 43.2, 56.4 and 70.9 g/d (P = 0.03); at intake L the amounts were 38.2, 34.2 and 32.8 g/d for WBPNS (P = 0.003) and for WBPND were 43.4, 38.0 and 36.9 g/d (P = 0.016) respectively. There were no significant (P > 0.05) differences in fractional rates of WBPNS and WBPND with time at either the L or H intake. We concluded that absolute protein turnover was affected both by dietary protein intake and body condition while the fractional rate of turnover was predominantly influenced by intake.

Ammonia↗
PubMed1995

Induction of megakaryocytic differentiation in a newly established human leukemic cell line by 12-o-tetradecanoylphorbol-13-acetate.

BACKGROUND: Biological studies on megakaryopoiesis have been hampered by the scarcity of megakaryocytes in normal bone marrow and difficulty in long term culture. Alternatively, leukemic cell lines with megakaryocytic differentiation potential may provide good models to counter these problems. METHODS: Leukemic cells from a patient with acute megakaryocytic leukemia were put into long-term culture and established into a cell line which was designated as VGH-MK1. The VGH-MK1 cells were challenged with differentiation agents and/or cytokines, and the differentiation of these cells was examined using morphological, immunocytochemical and surface-marker studies. RESULTS: Morphologically, VGH-MK1 cells had prominent nucleoli and basophilic cytoplasm with some protrusions, but large cells were occasionally seen. Under regular culture condition, the cells had a doubling time of 36-48 hours. The cloned cell line exhibited markers characteristic of megakaryoblasts after differentiation induction. Specifically, when stimulated with 12-o-tetradecanoylphorbol-13-acetate (TPA), cells became larger and had large or multinuclei. They were induced to express platelet glycoproteins GPIb (CD42b), GPIIb/IIIa (CD41), and GPIIIa (CD61) antigens, but not erythroid nor lymphoid markers. Platelet peroxidase (PPO) activity was also induced. Retinoic acid did not exhibit similar differentiation-inducing effects. In contrast, it counteracted the effects induced by TPA. CONCLUSIONS: An unique human leukemic cell line, VGH-MK1, has been established here. It could be induced to exhibit some characteristics of megakaryocytic lineage, and may be an useful model for the biological studies of megakaryopoiesis.

Adult↗
PubMed1994

Preliminary research on the p53 gene rearrangements in the evolution of chronic myelogenous leukemia to blast crisis.

DNA from 36 patients with chronic myelogenous leukemia (CML) at various clinical stages and 6 cases of acute leukemia was investigated for alterations of the p53 gene by Southern blot analysis. Rearrangements of the p53 gene were seen in 3 of 12 (25.00%) cases of blast crisis and accelerated phase (AP) of CML and in only one of 18 chronic phrase (CP), just as has been reported previously. Meanwhile, by restriction fragment length polymorphism (RFLP) analysis the Bgl II site polymorphism in the p53 gene was also found. The frequency in Chinese people detected here was 0.392, which was strikingly higher than that in some other countries (P < 0.001). These results suggested that the alterations of the p53 gene, for example, p53 rearrangements, were probably responsible for the progression of BC in some CML patients, and that the frequency of Bgl II polymorphism in the p53 gene might be related to the population distribution.

Blast Crisis↗
PubMed1994

Inhibition of parathyroid hormone secretion by amino-terminal chromogranin peptides.

The parathyroid gland responds to decreases in levels of extracellular calcium by increasing the secretion of both PTH and chromogranin-A (CGA) in approximately equal molar ratios. Because CGA has been suggested to be a precursor for biologically active peptides, we used primary cultures of bovine parathyroid cells to examine the effects of various peptides from CGA as well as analogous peptides from chromogranin-B (CGB) on PTH secretion. In concentrations from 10(-8)-10(-7) M, amino-terminal peptide CGA-(1-76) effectively inhibited the release of PTH in response to low extracellular calcium. Truncated analogs of this peptide, CGA-(1-40), CGB-(1-41), and CGA-(17-38) were also found to be active in the following order: CGA-(1-76) = CGA-(1-40) = CGB-(1-41) > CGA-(17-38). The biological activity of CGA-(1-40) was markedly reduced after reduction and alkylation, which resulted in disruption of the single disulfide bond between Cys17 and Cys38. Moreover, peptides derived from other regions of CGA and CGB, which included CGA-(403-428), CGB-(1-16), CGB-(316-326), and CGB-(635-657) were inactive. Pulse-chase experiments, using primary cultures of bovine parathyroid cells, revealed the presence of a CGA peptide in the culture medium that had the same amino-terminal sequence and mobility on sodium dodecyl sulfate-polyacrylamide gels as synthetic CGA-(1-76). Furthermore, in binding and cross-linking studies using intact parathyroid cells, CGA-(1-40) formed a single, covalently linked protein complex with a mol wt of 78,000. Formation of the protein complex could be completely inhibited in the presence of an excess of either CGB-(1-41) or CGA-(17-38). These results show that a naturally occurring amino-terminal peptide from CGA as well as shorter analogs can act as potent inhibitors of PTH secretion, and that their biological activity may be mediated through binding to a specific cell surface protein.

Animals↗
PubMed1994

[Clinical and experimental studies of feiyaning in treating pulmonary arterial hypertension in cor pulmonale].

40 Patients with chronic cor pulmonale (CCP) were treated with Feiyaning (FYN), a Yiqi Huoxue compound prescription, and ligustrazine (LT) were reported. The results showed that FYN and LT could lower the pulmonary artery pressure (PAP) significantly; decrease the pulmonary vascular resistance (PVR) as well as the consumption of oxygen in cardiac muscle; increase cardiac output (CO); improve some indices in hemorrheology; while PaO2 and SaO2 didn't change apparently. Moreover, lowering of FYN on PAP and PVR were superior to that of LT. The experimental studies showed that LT and injection of FYN could completely inhibit the hypoxia caused increase of PAP and PVR in rats; reduce the hypoxia caused pulmonary artery hypertension (PAH) and improve PVR of rats, as well as increase CO. The effects of FYN were superior to LT's. Although LT and FYN could decrease systemic arterial pressure to certain extent, they didn't induce systemic artery hypotension. It suggest that LT could reduce PAH definitely.

Adult↗
PubMed1993

Microtubules are involved in transport of macromolecules by vesicles in cultured bovine aortic endothelial cells.

The macromolecular transport in bovine aortic endothelial monolayers, cultured in vitro, was studied by fluorescence microscopy, confocal laser scanning microscopy, and transmission electron microscopy. A fluid-phase endocytic tracer, fluorescein isothiocyanate dextran 70 kD (FITC-dextran 70), was found to be transported into and out of endothelial cells via vesicles arranged as chains stretching between the luminal surface and the cell interior and also from cell interior to the abluminal surface. The endocytic activity was reduced by colchicine, which disrupts microtubules, and increased during treatment with cytochalasin B, which blocks microfilament polymerization. These findings indicate that microtubules are required for fluid-phase endocytosis and that microfilaments hinder this process.

Actin Cytoskeleton↗
PubMed1993

Differential heat stress stability of epidermal growth factor receptor and erbB-2 receptor tyrosine kinase activities.

The epidermal growth factor (EGF) and erbB-2 receptors are structurally related membrane-bound tyrosine kinases. While these proteins exhibit close sequence homology, 50% overall and 80% in the tyrosine kinase domains, they respond very differently to heat stress. In NIH-3T3 or NR6 cells transfected with wild-type EGF-R and incubated at 37 degrees C or heat shocked at 46 degrees C, EGF binds to its receptor and stimulates receptor autophosphorylation to equivalent extents. At 46 degrees C, however, the basal tyrosine kinase activity of the wild-type erbB-2 receptor is rapidly lost. When cells containing chimeric receptors composed of the EGF-R extracellular domain and intracellular domain of erbB-2 were heat stressed, 125I-EGF bound to the receptors, but did not stimulate receptor autophosphorylation. The decline in EGF-stimulated chimeric erbB-2 receptor autophosphorylation is dependent on the length of heat shock, with nearly 100% of the kinase activity lost after 60 min at 46 degrees C. The loss of chimeric receptor erbB-2 kinase activity is not due to degradation of receptor protein, nor is it attributable to a specific transmembrane domain from either the EGF or erbB-2 receptors. Sensitivity of erbB-2 to heat stress is also not a result of denaturation of this receptor's carboxy-terminal domain. Insertion of the erbB-2 tyrosine kinase domain into the EGF-R confers heat stress sensitivity to the resultant chimeric receptor. Thus, although the EGF-R and erbB-2 kinase domains show a high degree of homology, the secondary/tertiary structures of these domains would seem to be stabilized in distinct manners.

3T3 Cells↗
PubMed1993

Role of intracellular phosphate in the regulation of renal phosphate transport during development.

Direct correlations have been observed between the renal intracellular concentration of phosphate ([Pi]i) and postnatal age (3-13 weeks in rats, 1-4 weeks in guinea pigs), as well as between the dietary supply of Pi and [Pi]i. In turn, [Pi]i was found to be inversely correlated with the renal tubular transport of phosphate (TRPi). However, age- and diet-related differences in [Pi]i alone do not explain the high capacity of Na(+)-Pi cotransport present in the kidney of the neonate. Therefore, we explored whether changes in TRPi induced by altering Pi demand (whole body growth or bone mineralization) are mediated by factors other than changes in [Pi]i. TRPi was measured in vivo and nuclear magnetic resonance-visible [Pi]i in perfused kidneys of 8-week-old genetically growth hormone (GH)-deficient and GH-treated dwarf rats and in 8-week-old thyroparathyroidectomized (TPTX) Sprague-Dawley (SD) rats treated or untreated with etidronate (EHDP), an inhibitor of bone mineralization. In dwarf rats, [Pi]i was 1.2 +/- 0.2 mM and TRPi 2.4 +/- 0.2 mumol/ml glomerular filtrate. In TPTX SD rats, [Pi]i was 1.6 +/- 0.2 mM and TRPi 4.2 +/- 0.3 mumol/ml glomerular filtrate. Administration of GH to dwarf rats resulted in increases in Pi transport of 38% +/- 8% (P < 0.05), while administration of EHDP to TPTX SD rats decreased TRPi by 52% +/- 7% (P < 0.05). Neither GH nor EHDP significantly affected [Pi]i. Thus, in the rat changes in TRPi due to alterations in Pi demand occur in the absence of significant changes in [Pi]i.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Hydrogen peroxide stimulates endocytosis in cultured bovine aortic endothelial cells.

Fluid-phase uptake of macromolecules by cultured bovine aortic endothelial cells was measured using FITC-dextran (70,000 Da). Low doses of hydrogen peroxide added extracellularly stimulated the uptake of macromolecules by the endothelial cells. There was no general increase in the passive permeation or the transport across the cell layer. Moreover, when endothelial cells were stimulated with phorbol myristate acetate (PMA), macromolecules uptake was also enhanced. The PMA effect was blocked with superoxide dismutase (SOD) and catalase, suggesting a pivotal role of oxygen metabolites in fluid phase uptake of macromolecules by endothelial cells.

Animals↗
PubMed1993

Early extramedullary relapse of acute myelogenous leukemia in bilateral breasts: a case report.

We report a case of a 19-year-old female with acute myelogenous leukemia successfully treated with daunorubicin and Ara-c. Eight months after complete remission, palpable breast masses developed bilaterally. Biopsy and fine needle aspiration of the right mass showed cluster of leukemic cells indicative of extramedullary leukemic relapse. One month after biopsy, the patient's bone marrow showed presence of 90% blast cells. Palpable breast mass may be an early sign of relapse of acute myelogenous leukemia.

Adult↗
PubMed1993

[Maturation of ganglioneuroblastoma to ganglioneuroma: a case report].

A 1 year and 7 months old girl had suffered from chronic diarrhea for 6 weeks. A huge abdominal mass was found. She received subtotal resection of the tumor and the histological picture showed ganglioneuroblastoma. Then, 12 courses of chemotherapy (including cyclophosphamide, doxorubicin cisplatin and etoposide) were given for 8 months, but the residual tumor mass over the previous surgical area was still noted by CT scan. A second excision of the tumor was performed and histology showed a picture of ganglioneuroma incidentally. Chemotherapy was discontinued. The patient is still alive and well for more than one year.

Abdominal Neoplasms↗