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Biomedical subjects

C Ma

Publications and source records attributed to C Ma.

At least 127 records · Page 7Linked to original sources
PubMed1997

[Study on serum soluble interleukin-6 receptor levels in patients with malignant hematological diseases].

OBJECTIVE: To explore the clinical implication of soluble interleukin-6 receptor(sIL-6R) in patients with malignant hematological diseases. METHODS: Serum levels of sIL-6R in 26 multiple myeloma (MM), 34 acute leukemia (AL) and 17 non-Hodgkin's lymphoma (NHL) patients before and after chemotherapy and 20 normal controls were measured by immunoenzymetic assay. RESULTS: Serum levels of sIL-6R in MM and B-ALL patients at diagnosis were significantly higher than that in normal controls (P < 0.001, and P < 0.01, respectively), while the levels in ANLL, T-ALL and NHL patients were normal. Serum beta2 microglobulin and creatinine levels in MM patients with elevated serum sIL-6R were higher than that in patients with normal sIL-6R levels(P < 0.001, and P < 0.05, respectively). Serum sIL-6R levels did not relate to clinical stages. Serum lactic-dehydrogenase (LDH) levels in B-ALL patients with elevated sIL-6R were higher than that in patients with normal sIL-6R levels (P < 0.05). Serial measurement of serum sIL-6R in MM patients showed a good correlation with serum M-protein and plasma cell percentage in bone marrow. CONCLUSION: Serum sIL-6R levels were significantly increased in MM and B-ALL patients, and it is a predictive factor for responsiveness to chemotherapy and an indicator of disease activity.

Adult↗
PubMed1997

Antigen-presenting cells and the selection of immunodominant epitopes.

Cellular immune responses are directed against a narrow set of immunodominant peptides derived from complex antigens. By contrast, epitopes that are hidden or infrequent targets of immune responses have been termed cryptic or subdominant. Although the identification of immunodominant epitopes is important for vaccine development, understanding immunological reactivity to cryptic or subdominant epitopes may hold clues to autoimmunity. We have examined the role of antigen-presenting (APC) cells in the selection of class Ii-restricted epitopes for display to T lymphocytes. The formation and MHC-restricted presentation of distinct antigenic epitopes is directly dependent upon processing and ligand binding reactions within APC. A novel MHC heterodimer, HLA-DM, facilitates the binding and presentation of peptides by class II DR, DP, and DQ molecules. We have demonstrated that some epitopes derived from endogenous antigens bind class II proteins independent of DM, whereas the presentation of other endogenous peptides is greatly influenced by DM expression. Targeting of exogenous antigens into specialized processing compartments within APC appears to overcome the requirement for DM in antigen presentation. These studies suggest HLA-DM may play a role in epitope selection and immunodominance.

Animals↗
PubMed1997

[The application of transposition of pectoralis major muscle or myocutaneous flap in the repair of long-standing wound over the mandibulo-cervico-thoracic area].

The pectoralis major muscle or myocutaneous flap is characterized by its easy dissection and free rotation, as well as abundance of blood supply and tissue mass of the flap, so that it was often used in repairing the wound over the mandibulo-cervico-thoracic area. From 1989 to 1996, 11 cases with long-standing wound of this area were difficult to repair with the traditional method, but were treated with transposition of this type of myocutaneous flap. The myocutaneous flap was applied in 8 case and muscle flap in 3 case. The flap area ranged from 12 cm x 8 cm to 26 cm x 18 cm. All the flaps survived, and excellent results were achieved. The technique and design of the operation were reported in details. It was concluded that the process was easy to perform, and the flap had abundant blood supply and high resistance to infection.

Adolescent↗
PubMed1996

Plasmodium falciparum erythrocyte membrane protein 1 is a parasitized erythrocyte receptor for adherence to CD36, thrombospondin, and intercellular adhesion molecule 1.

Adherence of mature Plasmodium falciparum parasitized erythrocytes (PRBCs) to microvascular endothelium contributes directly to acute malaria pathology. We affinity purified molecules from detergent extracts of surface-radioiodinated PRBCs using several endothelial cell receptors known to support PRBC adherence, including CD36, thrombospondin (TSP), and intercellular adhesion molecule 1 (ICAM-1). All three host receptors affinity purified P. falciparum erythrocyte membrane protein 1 (PfEMP1), a very large malarial protein expressed on the surface of adherent PRBCs. Binding of PfEMP1 to particular host cell receptors correlated with the binding phenotype of the PRBCs from which PfEMP1 was extracted. Preadsorption of PRBC extracts with anti-PfEMP1 antibodies, CD36, or TSP markedly reduced PfEMP1 binding to CD36 or TSP. Mild trypsinization of intact PRBCs of P. falciparum strains shown to express antigenically different PfEMP1 released different (125)I-labeled tryptic fragments of PfEMP1 that bound specifically to CD36 and TSP. In clone C5 and strain MC, these activities resided on different tryptic fragments, but a single tryptic fragment from clone ItG-ICAM bound to both CD36 and TSP. Hence, the CD36- and TSP-binding domains are distinct entities located on a single PfEMP1 molecule. PfEMP1, the malarial variant antigen on infected erythrocytes, is therefore a receptor for CD36, TSP, and ICAM-1. A therapeutic approach to block or reverse adherence of PRBCs to host cell receptors can now be pursued with the identification of PfEMP1 as a malarial receptor for PRBC adherence to host proteins.

Animals↗
PubMed1996

LAF-4 encodes a lymphoid nuclear protein with transactivation potential that is homologous to AF-4, the gene fused to MLL in t(4;11) leukemias.

A novel human gene, LAF-4, was isolated from a subtracted cDNA library that showed strong sequence similarity to AF-4, a gene that is translocated in t(4;11)(q21;q23) acute lymphoblastic leukemias (ALLs). In t(4;11) ALL, the AF-4 gene at 4q21 is translocated into the MLL locus at 11q23, resulting in the expression of an MLL/AF-4 fusion protein that is the presumptive oncoprotein. AF-4 and LAF-4 are homologous throughout their coding regions, yet neither protein is related to previously cloned genes. Human LAF-4 readily hybridized with genes in mouse and chicken, thus showing that this gene family has been highly conserved during vertebrate evolution. In mouse tissues, LAF-4 mRNA was found to be present at highest levels in lymphoid tissues, present at lower levels in brain and lung, and absent from other tissues. In human and mouse lymphoid cell lines, LAF-4 expression was highest in pre-B cells, intermediate in mature B cells, and absent in plasma cells, thus pointing to a potential regulatory role for LAF-4 in lymphoid development. Antibodies to LAF-4 showed it to be a nuclear protein that showed an uneven, granular immunofluorescence pattern. In vitro-translated LAF-4 was able to bind strongly to double-stranded DNA cellulose. Furthermore, both LAF-4 and AF-4 had domains that activated transcription strongly when fused to the GAL4 DNA-binding domain. Interestingly, the AF-4 transactivation domain is retained in the MLL/AF-4 fusion protein; thus, it may contribute to the transforming potential of the oncoprotein. Therefore, the cloning of LAF-4 has defined a new family of potential regulatory proteins that may function in lymphoid development and oncogenesis.

Amino Acid Sequence↗
PubMed1996

Identification and functional characterization of conserved promoter elements from glass: a retinal development gene of Drosophila.

The Drosophila melanogaster glass transcription factor acts in photoreceptor cell development, glass transcription in the developing eye begins in the morphogenetic furrow. We report a deletion analysis which shows that a 5147 bp fragment can confer near wild-type expression in the developing eye. We completed the sequence of a similar Drosophila virilis fragment and comparison of these two genomic sequences reveals seven perfectly conserved sequence elements of 15 bp (or longer). We placed oligomers of each element 5' to an hsp70 promoter-lacZ fusion construct, and examined the patterns of beta-galactosidase expression produced in transgenic files. Three of these elements drive beta-galactosidase expression in the developing eye, and one is inhibitory.

Animals↗
PubMed1996

Electron paramagnetic resonance characterization of tyrosine radical, M+, in site-directed mutants of photosystem II(t).

Photosystem II contains two well-characterized tyrosine radicals, D(.) and Z(.). Z is an electron carrier between the primary chlorophyll donor and the manganese catalytic site and is essential for enzymatic function. On the other hand, D forms a stable radical with no known role in oxygen evolution. D(.) and Z(.) give rise to similar, but not identical, room temperature electron paramagnetic resonance (EPR) signals, which can be distinguished by their decay kinetics. A third room temperature EPR signal has also been observed in site-directed mutants in which a nonredox active amino acid is substituted at the D or Z site. This four-line EPR signal has been shown to have a tyrosine origin by isotopic labeling (Boerner and Barry, 1994, J. Biol. Chem. 269:134-137), but such an EPR signal has never before been observed from a tyrosyl radical. The radical giving rise to this third unique signal has been named M+. Here we provide kinetic evidence that this signal arises from a third redox active tyrosine, distinct from tyrosine D and Z, in the photosystem II reaction center. Isotopic labeling and EPR spectroscopy provide evidence that M is a covalently modified tyrosine.

Cell Membrane↗
PubMed1996

Identification and characterization of autosomal genes that interact with glass in the developing Drosophila eye.

The glass gene encodes a zinc finger, DNA-binding protein that is required for photoreceptor cell development in Drosophila melanogaster. In the developing compound eye, glass function is regulated at two points: (1) the protein is expressed in all cells' nuclei posterior to the morphogenetic furrow and (2) the ability of the Glass protein to regulate downstream genes is largely limited to the developing photoreceptor cells. We conducted a series of genetic screens for autosomal dominant second-site modifiers of the weal allele glass3, to discover genes with products that may regulate glass function at either of these levels. Seventy-six dominant enhancer mutations were recovered (and no dominant suppressors). Most of these dominant mutations are in essential genes and are associated with recessive lethality. We have assigned these mutations to 23 complementation groups that include multiple alleles of Star and hedgehog as well as single alleles of Delta, roughened eye, glass and hairy. Mutations in 18 of the complementation groups are embryonic lethals, and of these, 13 show abnormal adult retinal phenotypes in homozygous clones, usually with altered numbers of photoreceptor cells in some of the ommatidia.

Animals↗
PubMed1996

Overcoming a defect in generalized recombination in the marine fish pathogen Vibrio anguillarum 775: construction of a recA mutant by marker exchange.

A defect in generalized recombination has prevented the use of marker exchange for the construction of specific chromosomal mutations in the marine fish pathogen Vibrio anguillarum 775. Through the use of large segments of homologous DNA, we were successful in overcoming this defect and used marker exchange to construct a recA mutant of V. anguillarum H775-3. A recombinant cosmid carrying the recA gene of V. anguillarum 775 in the center of a 25-kb cloned DNA insert was isolated by complementation of methyl methanesulfonate (MMS) sensitivity in Escherichia coli HB101. The recA gene was inactivated by inserting a kanamycin resistance gene into recA, and the mutant gene was subsequently introduced into V. anguillarum H775-3 by conjugal mobilization. Isolation of recombinants between cosmid-borne recA::kan sequences and chromosomal DNA was facilitated by the introduction of an incompatible plasmid, and Southern hybridization was used to verify the presence of recA::kan in the chromosomal DNA of the recA mutant. V. anguillarum carrying recA::kan was considerably more sensitive to UV radiation and to MMS than was its parent, and near wild-type levels of resistance to MMS and UV light were restored by introduction of cloned recA genes from both E. coli and V. anguillarum. These results indicate that recA is required for DNA repair in V. anguillarum and demonstrate the utility of this modified marker exchange technique for the construction of mutations in this economically important fish pathogen.

Animals↗
PubMed1996

The effect of recombinant human insulin-like growth factor-I on chronic puromycin aminonucleoside nephropathy in rats.

We recently demonstrated that recombinant hGH exacerbates renal functional and structural injury in chronic puromycin aminonucleoside (PAN) nephropathy, an experimental model of glomerular disease. Therefore, we examined whether recombinant human (rh) IGF-I is a safer alternative for the treatment of growth failure in rats with chronic PAN nephropathy. The glomerulopathy was induced by seven serial injections of PAN over 12 wk. Experimental animals (n = 6) received rhIGF-I, 400 micrograms/d, whereas control rats (n = 6) received the vehicle. rhIGF-I improved weight gain by 14% (p < 0.05), without altering hematocrit or blood pressure in rats with renal disease. Urinary protein excretion was unaltered by rhIGF-I treatment in rats with chronic PAN nephropathy. After 12 wk, the inulin clearance was higher in rhIGF-I-treated rats, 0.48 +/- 0.08 versus 0.24 +/- 0.06 mL/min/100 g of body weight in untreated PAN nephropathy animals, p < 0.05. The improvement in GFR was not associated with enhanced glomerular hypertrophy or increased segmental glomerulosclerosis, tubulointerstitial injury, or renal cortical malondialdehyde content. In rats with PAN nephropathy, administration of rhIGF-I increased IGF-I and GH receptor gene expression, without altering the steady state level of IGF-I receptor mRNA. In normal rats with intact kidneys, rhIGF-I administration (n = 4) did not alter weight gain, blood pressure, proteinuria, GFR, glomerular planar area, renal cortical malondialdehyde content, or glomerular or tubulointerstitial damage, compared with untreated animals (n = 4). rhIGF-I treatment reduced the steady state renal IGF-I mRNA level but did not modify gene expression of the IGF-I or GH receptors. We conclude that: 1) administration of rhIGF-I improves growth and GFR in rats with chronic PAN nephropathy and 2) unlike rhGH, long-term use of rhIGF-I does not worsen renal functional and structural injury in this disease model.

Animals↗
PubMed1996

Vitamin E ameliorates renal injury in an experimental model of immunoglobulin A nephropathy.

IgA nephropathy is one of the most common forms of glomerular disease. Nearly 25% of affected patients progress to end-stage renal disease over a 20-25-y follow-up period. IgA-containing immune complexes stimulate oxygen-free radical production by mesangial cells in vitro. The excessive oxidant stress may mediate glomerular injury in this disorder. Therefore, we studied whether dietary supplementation with the antioxidant agent, vitamin E, attenuates renal disease in an experimental model of incipient IgA nephropathy with mild kidney inflammation. IgA nephropathy was induced in male Lewis rats by oral immunization with 0.1% bovine gamma-globulin (BGG)-containing drinking water for 8 wk. At the completion of this period, animals received BGG, 1 mg/dose i.v., on three successive days. Experimental rats (n = 10) received a specially formulated diet containing 100 IU of vitamin E/kg of chow, whereas control animals (n = 10) were fed chow containing 30 IU of vitamin/kg of chow. The BGG immunization regimen induced mesangial IgA deposition in all rats. Vitamin E supplementation resulted in a nearly 5-fold increase in the serum vitamin E concentration. Vitamin E-treated rats gained more weight and had a lower incidence of hematuria, 20% versus 80% (p < 0.03). Moreover, proteinuria was decreased by 50%, and reduced renal plasma flow was restored to normal, compared with untreated rats with IgA nephropathy. Glomerular hypertrophy occurred in animals with IgA nephropathy, but less so in those receiving vitamin E supplementation. Renal cortical malondialdehyde content was reduced from 1.55 +/- 0.10 to 1.22 +/- 0.09 nmol/mg of protein (p < 0.01) in rats fed the vitamin E-enriched diet. Finally, renal transforming growth factor-beta 1 gene expression was reduced by 34% in rats with IgA nephropathy receiving vitamin E treatment (p < 0.05). We conclude that experimental IgA nephropathy is associated with increased renal oxidant injury. Dietary treatment with the antioxidant agent, vitamin E, attenuated renal functional and structural changes in this experimental glomerulopathy. These studies support the importance of clinical trials for the evaluation of the efficacy of antioxidant therapy in patients with IgA nephropathy.

Animals↗
PubMed1996

Extracellular regulators and pattern formation in the developing Drosophila retina.

The compound eye of Drosophila melanogaster is composed of about 800 similar facets (or ommatidia) each of which contains 20 cells (8 photoreceptor neurons and 12 accessory cells). The fly's vision depends on the precise geometry of these components, and the developmental systems that produce pattern and cell fate have become models for nervous system development in general. The development of this pattern is progressive and appears to involve several levels of induction and inhibition, mediated by diffusible signals. The analysis of genes identified by mutation has revealed that several diffusible factors act in the early patterning steps of the eye. Genes that encode these factors include hedgehog, decapentaplegic, wingless, spitz and scabrous.

Animals↗
PubMed1996

[The preventing and treating effects of electro-acupuncture on cholelithiasis in golden hamster].

In this study, the 38 golden hamsters, male and female each half, were divided into four groups: the control and control treating groups to feed normal foods; cholelithiasis model and model treating groups to feed special diet, which made high fat, high cholesterol and high carbohydrates to cause the cholelithiasis model of hamsters. After 30 day, the natural formation rate of gallstone rose to 50% (contral group), while model group, the formation rate was 100%. On the 30th day, the treatment was carried out. The control treating group and model treating group were acupunctured at Yanglingquan(G 34) and Qimen(Liv 14) through Riyue(G 24) on the right side of body respectively by electrotherapy. The period of treatment was total 7 days, once everyday and 10 min every once. The results showed: (1) In control treating group, the natural formation rate of gallstone of normal hamsters was dropped from 50% to 10%, the number of gall-tones was reduced markedly(P < 0.05) and number of huge gallstones was dropped to zero(P < 0.01). (2) In the cholelithiasis model treating group, the treatment of electrotherapy could significantly reduced the formation rate of cholelithiasis, the number of gallstones and the huge gall-stones(P < 0.05 or P < 0.01). Also, content of the cholesterol in plasma and bile were reduced, but the contents of the cholic acid secreted from the liver were obviously increased in the model hamsters. It was significant difference to compared with model group(P all < 0.05). (3) The electrotherapy increased the rhythmic actions and frequency of Oddi's sphincter electromyogram markedly(P < 0.05, P < 0.01) as well as secretion of hepatic bile(P < 0.05, P < 0.01). The effects of electrotherapy could continued 30 to 40 minutes. The results suggest that some points to acupuncture with electrotherapy can reduce the contents of cholesterol in plasma and bile, and increase the volumes of secretion of cholic acid, thus inhibit the crystallization of cholesterol from bile. At the sometime, the electrotherapy causes the rhythmic contractions of Oddi's sphincter and increase the secretion of bile, so the gallstones are discharged on its own initiative. Therefore the cholelithiasis is cured by acupuncture.

Animals↗
PubMed1995

Promoters of the phr gene in Escherichia coli K-12.

We have identified two promoters of the Escherichia coli phr gene by DNA deletion mapping, S1 mapping of transcripts and sequence homology. The weaker promoter, P2, located approximately 530 bp upstream from the start codon, extends beyond the previously known nucleotide sequence. The stronger, P1, lies 90 bp from the gene and is distinct from three previously described promoter-like sequences nearby. beta-Galactosidase production from a plasmid-borne gene, promoted by a synthetic copy of P1, increases after DNA damage, but the increase does not depend on the SOS-box-like sequences normally present in the vicinity of P1. Induction still requires intact recA and lexA genes, and also intact sulA.

Base Sequence↗