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Biomedical subjects

S M Liu

Publications and source records attributed to S M Liu.

At least 91 records · Page 5Linked to original sources
PubMed1992

Activity of the epidermal-growth-factor receptor and phospholipase C-gamma 1 in heat-stressed fibroblasts and A-431 cells.

A variety of changes in the functions of specific plasma-membrane components have been reported in cells exposed to a heat shock. In this study, we examined the consequences of heat stress on epidermal-growth-factor (EGF)-induced receptor autophosphorylation and receptor-mediated tyrosine phosphorylation of phospholipase C-gamma 1 (PLC-gamma 1), a cellular substrate. Although the tyrosine kinase activity of the EGF receptor is rapidly inactivated at 45 degrees C in vitro [Carpenter, King & Cohen (1979) J. Biol. Chem. 254, 4884-4891], EGF stimulates autophosphorylation of its receptor in both A-431 cells and human fibroblasts after a prolonged heat shock. Phosphoamino acid analysis of the receptor reveals an EGF-induced increase in phosphotyrosine and phosphoserine at 46 degrees C. EGF also stimulates the phosphorylation of phospholipase C-gamma 1 and induces the formation of inositol phosphates under heat-shock conditions. 125I-EGF binding and internalization in A-431 cells is not decreased during incubations at 46 degrees C for up to 90 min. EGF-induced dimerization of EGF receptors on the cell surface is preserved during heat shock. Though EGF-receptor-mediated endocytosis is not inhibited by elevated temperature, the degradation of internalized 125I-EGF is dramatically decreased. These results indicate that, aside from ligand degradation, the EGF-mediated pathway of signal transduction through phospholipase C-gamma 1 remains remarkably intact during conditions of extreme cellular stress.

Animals↗
PubMed1992

Na+ alters the affinity for glucose and phosphate in rat renal brush-border membranes: a study of NMR relaxation rates.

Transport of D-glucose (Glc) and Pi across renal microvilli brush-border membrane vesicles (BBMV) is coupled to Na+.Na+ may alter substrate binding and dissociation or the mobility of the translocator and its complexes. To evaluate substrate binding in NaCl or KCl solutions containing BBMV, we measured nuclear magnetic resonance transverse relaxation rates (1/T2) of [1-13C]Glc and 31P(i), as well as their temperature, magnetic field, and pH dependencies. The data indicate the following: 1) the alpha-anomer, but not the beta-anomer, of Glc binds to BBMV, more in the presence of Na+ than of K+; 2) interactions of P(i) with BBMV that increase its 1/T2 are significant in the presence of K+ but not of Na+; 3) temperature and magnetic field dependencies of the 1/T2 of P(i) bound to BBMV are consistent with more rapid exchange with free P(i) in the presence of Na+ than of K+; and 4) in the presence of Na+, [H+] promoted interactions of P(i) with BBMV that increase its 1/T2, probably by interfering with formation of rapidly dissociating Na(+)-P(i)-carrier complexes. In conclusion, Na+ promotes association of alpha-Glc to BBMV but promotes rapid exchange and dissociation of P(i) from BBMV. In both cases, Na+ effects coupling by altering the affinity of the cotransporters for the substrate.

Animals↗
PubMed1992

Imported kala-azar: a case report.

A 77-year-old man returned from Honan Province, mainland China, and developed intermittent fever and loss of body weight. On physical examination there was evidence of chest infection but no lymphadenopathy or hepatosplenomegaly. Laboratory data suggested anemia, thrombocytopenia and polyclonal gammopathy. The diagnosis of Leishmaniasis was finally established by bone marrow aspiration which disclosed Leishman-Donovan bodies. Unfortunately, the patient expired soon after the diagnosis was made and a partial autopsy was performed. Kala-azar is a rare disease in Taiwan. However, it should be suspected in those patients who have visited the endemic areas, even though the clinical manifestations are atypical.

Aged↗
PubMed1991

Orientation of the photosynthetic flagellate, Peridinium gatunense, in hypergravity.

The photosynthetic freshwater flagellate, Peridinium gatunense, uses both positive phototaxis and negative gravitaxis to move upwards in the water column. At higher fluence rates approaching those at the surface of their habitat, the cells tend to become unoriented and thus stop their upward movement. Orientation and motility of Peridinium gatunense has been studied in the slow rotating centrifuge microscope (NIZEMI), which allows observation of swimming behavior during centrifugation acceleration between 1 g and 5g. The movement vectors were analyzed by real time image analysis capable of tracking many cells simultaneously. At 1 g the orientation was not very precise, but the degree of orientation increased significantly at higher acceleration forces up to about 3 g. Most cells were capable of swimming even against an acceleration vector of 3.8 g; at higher acceleration forces the cells were not able to cope with the centrifugal force. The linear velocity of cells swimming against 1 g was about 20% lower than that of cells moving in other directions. The velocity decreased even more in cells swimming against higher acceleration forces.

Animals↗
PubMed1991

Renal protein synthesis in diabetes mellitus: effects of insulin and insulin-like growth factor I.

Is increased synthesis of proteins responsible for the hypertrophy of kidney cells in diabetes mellitus? Does the lack of insulin, and/or the effect of insulin-like growth factor I (IGFI) on renal tubule protein synthesis play a role in diabetic renal hypertrophy? To answer these questions, we determined the rates of 3H-valine incorporation into tubule proteins and the valine-tRNA specific activity, in the presence or absence of insulin and/or IGFI, in proximal tubule suspension isolated from kidneys of streptozotocin diabetic and control rats. The rate of protein synthesis increased, while the stimulatory effects of insulin and IGFI on tubule protein synthesis were reduced, early (96 hours) after induction of experimental diabetes. Thus, hypertrophy of the kidneys in experimental diabetes mellitus is associated with increases in protein synthesis, rather than with decreases in protein degradation. Factor(s) other than the lack of insulin, or the effects of IGFI, must be responsible for the high rate of protein synthesis present in the hypertrophying tubules of diabetic rats.

Animals↗
PubMed1991

[CA125 in non-Hodgkin's lymphoma].

CA125 is an antigenic determinant recognized by monoclonal antibody CA125 raised against a serous ovarian cancer cell line. Elevation of this antigen has been reported in over 80% of women with epithelial ovarian cancer and many other diseases including both malignant and non-malignant ones. However, in non-Hodgkin's lymphoma (NHL) only a few reports have focused on this topic thus interesting us. In order to exploit its possible role in this field, a total of 61 eligible patients with a diagnosis of NHL were studied. Serum CA125 was measured by radioimmunoassay (RIA) prior to any operative procedures or chemotherapy. Serum CA125 above 35 U/ml was seen in 47.7% of nodal NHL (n = 44) and 70.6% of extranodal NHL (n = 17) with an overall positive rate at 54.1%. The elevation of serum CA125 correlates well with the presence of peritoneal involvement and therefore, with disease extent to some degree. No correlation between it and the histological type or with the B symptom was the rule. Avidin-biotin peroxidase stain by anti-CA125 MoAb was applied to identify the tissue content of this antigen in 15 cases of whom 11 had CA125 well above 35 U/ml. None of the 15 cases examined showed positive result. In conclusion, serum CA125 is probably no more than an indicator of peritoneal stimulation released by tumor invasion rather than a tumor product. The possible role in disease follow-up remains to be elucidated.

Adult↗
PubMed1991

Myelodysplastic syndrome: a study of prognostic factors.

Forty-three patients with myelodysplastic syndrome (MDS) were retrospectively analyzed for its prognostic factors. We evaluated the relationship of the clinical, biochemical, and hematological data, as well as colony-forming unit myeloid (CFU-C) culture, Bournemouth score, modified Bournemouth score, and modified Dutcher score to the prognosis. The median age was 65 years. Eighteen patients had refractory anemia (RA), 4 had refractory anemia with ringed sideroblasts (RARS), 15 had refractory anemia with excess blasts (RAEB), 2 had refractory anemia with excess blasts in transformation (RAEB-t), and 4 had chronic myelomonocytic leukemia (CMMoL). The median survival of all patients was 482 days. The median survival for each subtype was as follows: RA, 628 days; CMMoL, 350 days; RAEB, 240 days; RAEB-t, 90 days. For RARS, no data have yet been obtained, because only one out of 4 patients with RARS has died. We subdivided all patients into two groups: one group included patients with RA or RARS and the other group included patients with RAEB, RAEB-t or CMMoL. The former group had a median survival of 677 days and the latter group 240 days, p = 0.0035. In the former group, 3 out of 22 patients (13.6%) developed acute myeloid leukemia (AML), as compared to 8 out of 21 patients (38.1%) in the latter group, p = 0.0661. Twenty-five of the 43 patients died: 10 from AML and 15 from infection and/or bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

BCR rearrangements in Ph positive chronic myelocytic leukemia.

Nine patients with chronic myelocytic leukemia (CML) and 1 patient with erythroleukemia were studied with 3'bcr and 5'bcr probes using Southern blot hybridization technique. Bcr rearrangements were detected in 8 patients with CML in the chronic phase, and bcr rearrangement was deduced to have existed in a CML patient in blastic crisis. However, no abnormal fragment was found in the patient with erythroleukemia. 3'bcr and 5'bcr probes combined with proper restriction enzymes were believed to be of great value in determining bcr rearrangements in Ph positive CML.

Adolescent↗
PubMed1991

An embryonic origin for medulloblastoma.

Medulloblastoma is a common brain tumor of children. Three differentiated cell types are found in medulloblastomas: neurons, glia, and muscle cells. Because of the presence of multiple differentiated cell types these tumors were named after a postulated cerebellar stem cell, the medulloblast, that would give rise to the differentiated cells found in the tumors. We describe a cell line with the properties expected of the postulated medulloblast. The rat cerebellar cell line ST15A expresses an intermediate filament, nestin, that is characteristic of neuroepithelial stem cells. ST15A cells can differentiate, gaining either neuronal or glial properties. In this paper we show that the same clonal cell can also differentiate into muscle cells. This result suggests that a single neuroectodermal cell can give rise to the different cell types found in medulloblastoma. We also show expression of nestin in human medulloblastoma tissue and in a medulloblastoma-derived cell line. Both the properties of the ST15A cell line and the expression of nestin in medulloblastoma support a neuroectodermal stem cell origin for this childhood tumor.

Animals↗
PubMed1990

Motility and gravitactic orientation of the flagellate, Euglena gracilis, impaired by artificial and solar UV-B radiation.

The effects of ultraviolet radiation on the gravitactic orientation of the freshwater flagellate, Euglena gracilis, were determined by a real time image analysis system. Both artificial UV radiation and solar radiation in a temperature-controlled growth chamber were employed. Histograms of gravitaxis showed that the degree of orientation decreased with increasing exposure time; this can be quantified using the Rayleigh test and upper quadrant summation. The effects of artificial UV radiation on the orientation are considerably stronger than those of solar radiation, probably because the radiation source emits higher fluence rates below 300 nm than found in solar radiation. The effects of monochromatic ultraviolet radiation on motility have been determined, and an action spectrum has been calculated.

Animals↗
PubMed1990

Effects of solar radiation on photoorientation, motility and pigmentation in a freshwater Peridinium.

Solar radiation has a pronounced effect on photoorientation, motility and pigmentation in the freshwater dinoflagellate, Peridinium gatunense. Photoorientation (positive phototaxis) is impaired even after short exposure times and is totally inhibited after about 2.5 h. The percentage of motile cells decreases after short exposure times and after 4 h most cells are immotile. Likewise, the mean velocity decreases after an initial light-induced increase (photokinesis) under solar radiation. Solar UV-B (280-320 nm) radiation seems to be the major cause for the effects, since cutting off shorter wavelength by an ozone cuvette or WG filters prolongs the tolerated exposure times. Possible UV-B targets are the photoreceptor pigments since solar radiation causes a massive bleaching of the cells within a few hours.

Animals↗
PubMed1990

Identification of megakaryocytic cells by Ulex Europaeus Agglutinin I (UEA 1) in B5 fixed, decalcified, paraffin-embedded specimens.

To determine the utility of Ulex Europaeous Agglutinin I (UEA 1) as a marker for megakaryocytes, bone marrow from one hundred cases with various diseases studied using an immunoperoxidase method on the B5 fixed, decalcified and paraffin-embedded specimen. Our results indicated that large typical megakaryocytes and small megakaryocytes (micromegakaryocytes) were intensively stained by UEA 1 in diffuse, marginal, focal and hypo-granular patterns. Compared with factor VIII-related antigen, UEA 1 was more sensitive as a marker in identification of megakaryocytes. It provided an effective tool to observe the morphologic appearance of megakaryocytic lineage on B5 fixed, decalcified, paraffin-embedded specimen. The facility to identify the small atypical megakaryocytes as well as the different staining patterns would be helpful in the diagnosis of megakaryocytic disorders.

Bone Marrow↗
PubMed1990

Photoorientation, motility and pigmentation in a freshwater peridinium affected by ultraviolet radiation.

The effects of ultraviolet radiation on orientation, motility and pigmentation were measured in the freshwater dinoflagellate, Peridinium gatunense. Histograms of the positive phototactically oriented cells showed a decrease in the degree of orientation even after short exposure times. Quantification of the orientation revealed a significant inhibition after 2 h exposure. Similarly, the percentages of motile cells and the mean linear velocity of the cells was strongly affected. UV radiation also caused a massive bleaching of the cellular pigments as shown by absorption spectra determined after increasing exposure times. The ecological consequences of these effects are discussed.

Animals↗
PubMed1989

Polymorphic reticulosis: a malignant lymphoma of B-cell lineage.

Whether the pathogenesis of polymorphic reticulosis is from T cells, B cells, or histiocytes has been controversial. In this study, the Southern blot hybridization technique was used to analyze immunoglobulin and T-cell receptor beta-chain genes and to perform the conventional surface marker analysis in two patients with polymorphic reticulosis. The immunophenotype demonstrated the presence of predominantly mature, activated T-lymphocytes, minimal B-cells, and no natural killer cells or monocytes/granulocytes. The mature T-cell phenotype could be due to either inflammatory infiltrates or neoplastic cells of peripheral T-cell type, because the two coexist in polymorphic reticulosis tumors. The value of surface marker examination is limited in the analysis of PMR tumors. However, genetic analysis revealed that only Ig genes were rearranged, with no rearrangement of the TCR beta gene. Rearrangement of immunoglobulin genes occurs in B-lineage lymphoid neoplasms and is thought to be a criterion for diagnosis of lymphoid neoplasms. Based on genetic analysis and clinicopathologic information, this study concluded that polymorphic reticulosis is a malignant lymphoma of B-cell lineage.

Adult↗
PubMed1989

Combined cold- and warm-antibody autoimmune hemolytic anemia--review of the literature and a case report.

This report described the second case in the literature of Waldenstrom's macroglobulinemia with combined cold- and warm- antibody autoimmune hemolytic anemia (CCW-AIHA). Both IgG and IgM red cell auto-antibodies (auto-Abs) were present in the patient's serum. The IgM auto-Abs had a high thermal amplitude and anti-I blood group specificity. The IgG auto-Abs did not reveal blood group specificity. This patient depended on steroids to control hemolysis, but responded well to chemotherapy and plasmapheresis. CCW-AIHA has rarely been reported. In this study, the literature is reviewed and the characteristic serological and clinical features of this rare category of autoimmune hemolytic anemia (AIHA) are discussed.

Adolescent↗