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Biomedical subjects

S Ma

Publications and source records attributed to S Ma.

At least 91 records · Page 5Linked to original sources
PubMed2000

[In vitro induction of autologous T cell killing by heat treated human chronic myelogenous leukemia cells].

OBJECTIVE: To investigate the potential of autologous T cell killing of heat treated chronic myelogenous leukemia (CML) cells (autologous tumor killing, ATK). METHODS: (51)Cr release assay was used to measure the ATK activity of autologous T cells against CML cells treated with 42 degrees C for 30 minutes (heat) or 37 degrees C for 30 minutes (non-heat). The phenotypes of T cells and heat shock protein 70 (HSP70) expression of CML cells were measured by flow cytometry (FCM). T cells from the CML patients were stimulated and expanded by autologous mixed lymphocyte/tumor cell cultures (MLTC). RESULTS: ATK activity of autologous T cells to the non-heated and heated CML cells were found in 4 (19.05%) and 10 (47.62%) of the 21 cases, respectively. The ATK activity of interleukin-2 (IL-2) stimulated autologous T cells against heated CML cells was markedly higher than that of unstimulated autologous T cells against non-heated CML cells (P < 0.001). FCM analysis showed that no HSP70 was expressed on the CML cell membranes whether heated or non-heated, but intracellular HSP70 expressions were (83.42 +/- 5.65)% and (78.34 +/- 6.32)% pre- and post-heated, respectively. The phenotypes of T cells stimulated and expanded in MLTC were TCRgammadelta - CD(3)(+), mostly CD(8)(+), with some activation markers (CD(25) and HLA-DR) expression. The ATK activities of these T cells against the heated and non-heated CML cells and K562 cells were (51.25 +/- 4.26)%, (36.52 +/- 3.83)% and (2.92 +/- 1.19)%, respectively. CONCLUSIONS: ATK activity of autologous T cells against CML cells could be induced or enhanced by heat treatment of the CML cells particularly of T cells stimulated with IL-2. This ATK activity was not associated with gammadelta T cells or HSP70 expression of CML cells.

Adolescent↗
PubMed2000

[Survival motor neuron gene and neuronal apoptosis inhibitory protein gene deletion in patients with spinal muscular atrophy].

OBJECTIVE: To investigate the frequencies of gene deletion survival motor neuron telomere (SMNTel) exon 7 and neuronal apoptosis inhibitory protein gene (NAIP) exon 5 in 55 Chinese spinal muscular atrophy (SMA) patients, and compare the relationship between these two candidate genes and the disease. METHODS: PCR-SSCP method was used to detect the deletion of SMNTel exon 7, direct visualization of PCR products by agarose electrophoresis was used to detect the deletion of NAIP exon 5 in 55 SMA patients with type I and type II. 40 normal individuals were involved in the study as controls. RESULTS: Homozygous deletion of the SMNTel exon 7 was identified in 92% (23/25) of SMA type I patients and 90% (27/30) of SMA type II patients. The same deletion was found in two mothers and one father of SMA patients. There was no homozygous deletion found in normal controls. None of the homozygous deletion of NAIP exon 5 was found in 55 SMA patients and normal controls. Only two patients were found to have the heterozygous deletion. CONCLUSIONS: The frequency of homozygous deletion of SMNTel exon 7 was 90.1%. Our data support that SMN gene is strongly associated with SMA.

Adult↗
PubMed1999

Dynein intermediate chain mediated dynein-dynactin interaction is required for interphase microtubule organization and centrosome replication and separation in Dictyostelium.

Cytoplasmic dynein intermediate chain (IC) mediates dynein-dynactin interaction in vitro (Karki, S., and E.L. Holzbaur. 1995. J. Biol. Chem. 270:28806-28811; Vaughan, K.T., and R.B. Vallee. 1995. J. Cell Biol. 131:1507-1516). To investigate the physiological role of IC and dynein-dynactin interaction, we expressed IC truncations in wild-type Dictyostelium cells. ICDeltaC associated with dynactin but not with dynein heavy chain, whereas ICDeltaN truncations bound to dynein but bound dynactin poorly. Both mutations resulted in abnormal localization to the Golgi complex, confirming dynein function was disrupted. Striking disorganization of interphase microtubule (MT) networks was observed when mutant expression was induced. In a majority of cells, the MT networks collapsed into large bundles. We also observed cells with multiple cytoplasmic asters and MTs lacking an organizing center. These cells accumulated abnormal DNA content, suggesting a defect in mitosis. Striking defects in centrosome morphology were also observed in IC mutants, mostly larger than normal centrosomes. Ultrastructural analysis of centrosomes in IC mutants showed interphase accumulation of large centrosomes typical of prophase as well as unusually paired centrosomes, suggesting defects in centrosome replication and separation. These results suggest that dynactin-mediated cytoplasmic dynein function is required for the proper organization of interphase MT network as well as centrosome replication and separation in Dictyostelium.

Animals↗
PubMed1999

Influence of fetal to neonatal transition on nitric oxide synthase expression in the nucleus tractus solitarius in sheep.

Transition from fetal to newborn life is accompanied by a marked rise in circulating norepinephrine (NE) concentrations though arterial blood pressure does not substantively change. Nitric oxide (NO) plays an important role in the central regulation of sympathetic tone in the nucleus tractus solitarius (NTS) and neuronal NO synthase (nNOS) expression is functionally regulated in the brain. The purpose of these studies was to determine the influence of transition at birth on nNOS expression in the brainstem nuclei, particularly in the NTS, associated with changes in arterial pressure and plasma NE concentration. Experiments were performed using time-dated gestational ewes with twin fetuses. Arterial blood pressure was recorded and arterial blood NE concentrations were measured in the term fetus (gestational 147-148 days) and newborn lambs (4 h of postnatal age). The fetal and newborn animals were then perfused with 4% paraformaldehyde. Sections of the medulla were examined by using both immunolabeling with a polyclonal antibody directed against nNOS and nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry, a marker for expression of nNOS. Micrographs were quantified using a microscope with reticule grid to measure the number of positive cells containing color staining in the brainstem nuclei. Plasma NE concentration in the newborn was more than two-fold greater compared to fetal values but mean arterial blood pressure was similar between fetus and newborn. The nNOS positive cells and NADPHd positive cells were significantly increased in the medial NTS (mNTS) of the newborn compared to fetus. nNOS immunoreactivity and NADPHd reactivity tended to increase in the rostral ventral medulla (RVM) in newborn, but were not altered in other brainstem nuclei during the transition from fetal to newborn life. The results suggest that nNOS expression in the mNTS is predominately enhanced at 4 h of neonatal age vs. the term fetus. We conclude that elevated circulating NE is associated with up-regulation of nNOS in the mNTS which may serve a protective role in central regulation of neonatal arterial blood pressure.

Animals↗
PubMed1999

Carbohydrate analysis of a chimeric recombinant monoclonal antibody by capillary electrophoresis with laser-induced fluorescence detection.

A general method for the analysis of asparaginyl-linked (N-linked) carbohydrate moieties of an IgG1 monoclonal antibody is described here. The antibody, rituximab, is a mouse/human chimeric antibody to human CD20 antigen. The glycans present on rituximab are neutral complex biantennary oligosaccharides with zero, one, and two terminal galactose residues (G0, G1, and G2, respectively). To monitor the variation of the glycosylation during manufacture, the glycans were first enzymatically released from the antibody via digestion with peptide-N-glycosidase F, then derivatized with a charged fluorophore, 8-aminopyrene-1,3,6-trisulfonic acid and further separated by capillary electrophoresis with laser-induced fluorescence detection. All observed glycans were fully resolved, including the positional isomers of G1. The exact nature of the isomers in terms of the location of the terminal galactose was further characterized via multiple enzymatic digestion steps including mannosidase with activity toward specific Man(alpha 1,3) linkage. The optimization and several key parameters, i.e., enzymatic digestion and derivatization, in the assay development will be discussed. Moreover, to ensure that the assay can be used in routine lot release testing, the assay was validated and found to be accurate and precise. The analytical approach described is suitable for characterization as well as routine testing of the N-linked glycan content in any IgG1 monoclonal antibody and glycoproteins in general.

Animals↗
PubMed1999

Charge-Transfer Complexation of C(60) with Diphenyltetrathiafulvalene (DPTTF) Capped Gold Clusters.

4,4'-Diphenyltetrathiafulvalene (DPTTF) capped gold nanoparticles of 3- to 5-nm diameter have been prepared and their thermal stability has been investigated by variable temperature FT-IR spectroscopy. The DPTTF molecules at the cluster surface undergo charge-transfer complexation with C(60) to form Au/DPTTF.C(60). Direct evidence of complexation is observed in the x-ray photoelectron and infrared spectra of the clusters. The orientational ordering transition of C(60) in Au/DPTTF.C(60) clusters occur at a higher temperature than pure C(60) indicating increased resistance to orientational disorder due to charge transfer. Variable-temperature infrared spectroscopic studies yield complementary information. Both FT-IR and mass spectra show that some of the sites on the gold surface are occupied by the phase-transfer reagent used in the cluster preparation. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

On topography and functionality in the B-D rings of cephalostatin cytotoxins.

Analogues 12'beta-hydroxycephalostatin 1 (9), 7'-deoxyritterazine G (10), and 14-epi-7'-deoxyritterazine B (11) were prepared via our protocol for unsymmetrical pyrazine synthesis. Cytotoxicity against human tumors was also determined for the first time for ritterazines, with femtomolar potency and a high correlation to cephalostatins observed. The SAR of these and related compounds provide insight into the importance of topography and certain chemical functionality in the B-D and B'-D' rings of cephalostatin type antineoplastics.

Antineoplastic Agents↗
PubMed1999

3D Monolayers of 1,4-Benzenedimethanethiol on Au and Ag Clusters: Distinct Difference in Adsorption Geometry with the Corresponding 2D Monolayers.

Au and Ag clusters of 3-nm mean diameter were prepared with 1,4-benzenedimethanethiol (BDMT) as the capping molecule. In both the monolayer-capped clusters, BDMT adsorbs in the dithiolate form in contrast to in the 2D monolayers, where the dithiolate form exists only in the case of Ag. As a result, the molecule lies flat on the cluster surface in both Au and Ag, whereas the molecular plane is perpendicular to the surface in the 2D monolayer of Au. This difference in adsorbate structure is attributed to the evolution in the cluster surface as adsorption occurs. Transmission electron microscopy and X-ray powder diffraction suggest that no superlattice of the clusters exists. Mass spectrometry suggests the presence of the phase transfer reagent at the surface. X-ray photoelectron spectroscopy confirms the chemical similarity of the two surfaces and suggests that the thiolate at the surface is susceptible to X-ray beam induced damage. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

[Study on mutation of exon 8 of Wilson's disease gene]

OBJECTIVE: To analyze the frequency of mutation in exon 8 of Wilson's disease (WD) gene in Chinese people. METHODS: Screening for ATP7B gene mutation was conducted in 45 WD patients£® Mobility shift of exon 8 was analyzed by SSCP. Nucleotide sequence of exon 8 was analyzed, and the PCR products were cut by enzyme Msp I. The authors found G2273T mutation at codon 778, and according to this mutation sequence, made an analysis of enzyme cut by Msp I in all patients. 2 WD families were analyzed. RESULTS: No abnormality was found in 20 controls. In 45 patients, 2 were homozygous (4.4%) and 11 heterozygous (12.2%). The positive rate of mutation was 16.67%. The Arg778Leu mutation was validated by this study. CONCLUSION: The mutation in exon 8 of WD gene may play an important role in pathogenesis of Wilson's disease in Chinese.

Journal Article↗
PubMed1999

Secretion of 92 kDa gelatinase (MMP-9) by bovine neutrophils.

To understand the process of neutrophil migration into mammary glands during mastitis, secretion of MMP-9 by bovine neutrophils was investigated. The methods of zymograms and RT-PCR were used to measure the secretory MMP-9 activity and its gene transcription, respectively. Both MMP-9 protein and mRNA were found to be expressed constitutively and greatly enhanced by PMA. However, the significant increase in the enzyme activity was found after 1 ng/ml PMA treatment for 1 h, while increasing MMP-9 mRNA transcription was only obvious after 1 ng/ml PMA treatment for 3 h. Moreover, secretion of MMP-9 protein was not inhibited by actinomycin D and cycloheximide. These results suggest that quick MMP-9 protein release from bovine neutrophils by the stimulation of PMA was due to the degranulation. As MMP-9 is an important proteinase in breakdown of the extracellular matrix and can be rapidly secreted by neutrophils through degranulation, it should play a critical role in the recruitment of neutrophils into mammary glands in bovine mastitis.

Animals↗
PubMed1999

Differential regulation of in vitro cytokine production by human blood cells in response to methylmethacrylate.

The effect of methylmethacrylate (MMA) on human whole blood cultures (WBC) obtained from healthy donors was investigated. Lymphocyte transformation and cytokine production, that is, interleukin 6 (IL-6), interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha), were used to evaluate the immunological activities of MMA. Primary cytotoxicity testing of MMA in Jurkat cells showed that this compound decreased the cell proliferation to 50% at a concentration of >60 mmol/L. Similarly, MMA significantly decreased lymphocyte transformation in either phytohemagglutinin (PHA) or Staphylococcus aureus protein A (SpA) activated WBC at 100 mmol/L. In contrast to activated WBC, MMA had no observed effect on resting blood cells. Cytokine expression in WBC seemed differentially modulated by MMA. There was a tendency for IL-6 production in both resting and PHA-stimulated WBC to be upregulated, while IL-6 induced in SpA stimulated cultures was downregulated. TNF-alpha was slightly increased by MMA in resting WBC at early incubation periods, and it was slightly downregulated in response to PHA or SpA activation. Suppression of IFN-gamma secretion was observed in WBC with or without PHA or SpA stimulation. The overall results demonstrated that MMA at physiological levels could influence the cytokine production in normal human blood cells in vitro. Alterations of cytokine production patterns by MMA indicate that this compound has multiple regulatory effects on immune reactions in normal human blood.

Adolescent↗
PubMed1999

The family of cold shock proteins of Bacillus subtilis. Stability and dynamics in vitro and in vivo.

Bacillus subtilis possesses three homologous small cold shock proteins (CSPs; CspB, CspC, CspD, sequence identity >72%). They share a similar beta-sheet structure, as shown by circular dichroism, and have a very low conformational stability, with CspC being the least stable. Similar to CspB, CspC and CspD unfold and refold extremely fast in a N <==> U two-state reaction with average lifetimes of only 100-150 ms for the native state and 1-6 ms for the unfolded states at 25 degreesC. As a consequence of their low stability and low kinetic protection against unfolding, all three cold shock proteins are rapidly degraded by proteases in vitro. Analysis of the CSP stabilities in vivo by pulse-chase experiments revealed that CspB and CspD are stable during logarithmic growth at 37 degreesC as well as after cold shock. The cellular half-life of CspC is shortened at 37 degreesC, but under cold shock conditions CspC becomes stable. The proteolytic susceptibility of the CSPs in vitro was strongly reduced in the presence of a nucleic acid ligand, suggesting that the observed stabilization of CSPs in vivo is mediated by binding to their substrate mRNA at 37 degreesC and, in particular, under cold shock conditions.

Amino Acid Sequence↗
PubMed1999

Supramolecular Isomerism in Caviplexes.

Stereoisomeric complexes of an open-ended cavitand and its guest molecules (shown schematically) were detected, and complexes within caviplexes were introduced. Some control can be exerted on the stereoisomerism through methylation of the guest. The symbols "0" and "1" represent different ends of the guest molecule.

Journal Article↗
PubMed1999

Autoantigens produced in plants for oral tolerance therapy of autoimmune diseases.

Oral administration of protein antigens can induce antigen-specific immune hyporesponsiveness and may be useful in treating autoimmune diseases or preventing transplant rejection. However, the therapeutic value of oral tolerance may be limited when candidate autoantigens cannot be produced by conventional system in quantities sufficient for clinical studies. Plants may be ideally suited for this purpose, as they can produce hugh quantities of functional mammalian proteins at extremely competitive cost. Furthermore, transgenic food plants could provide a simple and direct method of autoantigen delivery for oral tolerance. Here we show that the diabetes-associated autoantigen glutamic acid decarboxylase (GAD) is efficiently expressed in both tobacco and potato plants, and that mice, when fed with fresh transgenic potato tubers, are fully protected from diabetes.

Administration, Oral↗
PubMed1999

Phalloplasty in female-to-male transsexuals using free radial osteocutaneous flap: a series of 22 cases.

From July 1994 to December 1996, 22 cases of primary female transsexualism received phalloplasty using free radial forearm osteocutaneous flaps in The Veterans General Hospital, Taipei, Taiwan. Follow-up period ranged from 6 months to 35 months. No complete flap loss and one partial loss (10% reduction) were noted after operation. The urethrocutaneous fistula rate was 40.9%, needing fistula repair surgery. Urethral stricture was noted in three cases (13.7%). Significant donor forearm morbidity was noted in two cases (9.1%) including one who suffered from radius bone fracture. All preserved 'clitorises' had intact erotic sensation and all neophalli gained protective sensation within 9 months. No 'penile fracture' was noted. In nine cases that have regular sexual activities, the sexual performance was rated as satisfactory. We share our experience and recommend that the free radial forearm osteocutaneous tubing flap is a promising choice for phalloplasty in female-to-male transsexuals.

Bone Transplantation↗