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Biomedical subjects

L Ma

Publications and source records attributed to L Ma.

At least 505 records · Page 28Linked to original sources
PubMed1994

Analysis of MRP gene expression and function in HL60 cells isolated for resistance to adriamycin.

In an effort to define clearly the basis of non-P-glycoprotein multidrug resistance in HL60/ADR cells, we have analyzed expression of MRP mRNA levels and the MRP-encoded protein in resistant cells and also in resistant cells that have undergone a reversion to drug sensitivity. The results demonstrate that an MRP cDNA containing 5'-end coding sequences reacts with a 6-kb RNA, which is overexpressed in the resistant isolate. As resistant cells revert to drug sensitivity there is essentially a complete loss of the 6-kb RNA. Southern blot analysis indicates that the MRP gene is amplified compared to the copy number found in sensitive cells. Revertant cells no longer contain amplified MRP sequences. Western blot analysis has been conducted using an antibody prepared against the carboxyl terminus (15 amino acids) of the deduced sequence of the MRP-encoded protein. The antibody is reactive with a 190-kDa protein (P190) and with two closely migrating proteins of 65 and 70 kDa (P70), which are overexpressed in plasma membranes and endoplasmic reticulum of resistant cells. Both proteins are greatly reduced in revertant cells. Growth of cells in the presence of tunicamycin demonstrates that both P190 and P70 are glycosylated, with the deglycosylated forms migrating in polyacrylamide gels as proteins of 165 kDa and 45 kDa, respectively. Additional antisera have also been prepared against sequence domains contained in the C-terminal region of P190. These antisera are reactive with both P190 and P70. Antisera directed against sequences of the amino terminal region of P190 do not react with P70.(ABSTRACT TRUNCATED AT 250 WORDS)

ATP-Binding Cassette Transporters↗
PubMed1994

[Effects of different cooling rate on the viability of cryopreservation of skin].

The three methods of stored skin by vitrification and slow cooling and vitrification+slow cooling were studied in order to improve the viability of stored skin. The results showed that the viability (oxygen consumptions and succinate dehydrogenase) of skin cryopreserved by vitrification was superior than by slow cooling and vitrification+slow cooling. The viability of homograft stored by vitrification was 61% compared with that for other two groups of 51.7% and 49.2% (P < 0.05). So the skin stored by this vitrification may be suitable for clinical use.

Cryopreservation↗
PubMed1994

[Effects of arsenic on the offspring development in mice].

Effects of arsenic exposure on offspring development were studied in pregnant mice. The results showed arsenic contents of the body and brain tissue increased and the structure of neural cells in cerebral cortex became abnormal after exposure. The offspring neurobehavioral development appeared retardant and the proportion of their peripheral lymphocytes with alpha-naphthalene acetate enzyme (ANAE) declined in a mice group with exposure to 0.75 mg/kg arsenic, and the offspring body weight gain slowed after weaning, blood cholinesterase activity and serum level of haemolysin declined significantly in a group with 4.50 mg/kg. It indicated arsenic could affect embryonic and offspring development in mice through pregnant exposure.

Animals↗
PubMed1994

Squamous cell carcinoma of the oesophagus with mucin-secreting component (muco-epidermoid carcinoma and adenosquamous carcinoma): a clinicopathologic study and a review of literature.

The clinicopathological features of 11 cases of primary oesophageal squamous cell carcinomas with mucin-secreting component (eight muco-epidermoid and three adenosquamous carcinomas) are presented. The incidence was 2.2% of all resected primary oesophageal tumors. The mean age was 64 years and the male to female ratio was 4.5:1. The mean diameter of these tumours was 4 cm. Twenty-seven per cent of these tumours were in the upper, 46% in the middle and 27% in the lower portion of the oesophagus. The age, sex and site distribution of these tumors were similar to those of squamous cell carcinomas. The medium survival of these patients was 15 months. The world literature concerning this rare entity was reviewed and compared with the findings of the present study. No major racial differences were noted. In addition, the classification of this group of tumours was also discussed.

Aged↗
PubMed1993

A mutation in the homeodomain of the human MSX2 gene in a family affected with autosomal dominant craniosynostosis.

Craniosynostosis, the premature fusion of calvarial sutures, is a common developmental anomaly that causes abnormal skull shape. The locus for one autosomal dominant form of craniosynostosis has been mapped to chromosome 5qter. The human MSX2 gene localizes to chromosome 5, and a polymorphic marker in the MSX2 intron segregates in a kindred with the disorder with no recombination. Moreover, a histidine substitutes for a highly conserved proline at position 7 of the MSX2 homeodomain exclusively in affected members. In the mouse, transcripts of the Msx2 gene are localized to calvarial sutures. These results provide compelling evidence that the mutation causes this craniosynostosis syndrome.

Acrocephalosyndactylia↗
PubMed1993

Disseminated mediastinal carcinoma with chromosomal translocation (15;19). A distinctive clinicopathologic syndrome.

BACKGROUND: A case of disseminated mediastinal carcinoma probably of thymic origin is reported in a 5-year-old boy with an anterior mediastinal mass associated with superior vena cava obstruction, tracheal deviation, right malignant pleural effusion, and evidence of bone metastasis. The diagnosis was based on findings of radiologic localization, light and electron microscopic study, and immunohistochemistry. The patient received combination chemotherapy but died of progressive disease. METHODS: Cytogenic study on the pleural fluid was attempted, and a literature search for similar chromosomal aberration was performed. RESULTS: Cytogenetic study of tumor cells from the pleural fluid revealed a clonal chromosomal abnormality of t(15;19)(q12;p13.1). Two patients with similar disease were reported in the English literature; their clinical courses, immunohistochemical findings, and t(15;19) were almost identical to those of the patient reported in this study. CONCLUSION: The authors suggest that this translocation may be specific to thymic carcinoma and may indicate a particularly aggressive form of the disease. Carcinomas are rare in children, so the chromosomal translocation may serve as a helpful marker for the diagnosis.

Adult↗
PubMed1993

Accelerated programmed cell death (apoptosis) in erythroid precursors of patients with severe beta-thalassemia (Cooley's anemia)

The profound and life-threatening anemia in patients with Cooley's anemia is ascribed primarily to intramedullary hemolysis (ineffective erythropoiesis), the cause of which is obscure. Based on prior morphologic data showing nuclear abnormalities, we hypothesized that accelerated apoptosis could occur in these erythroid precursors. The highly successful bone marrow (BM) transplantation program for patients with Cooley's anemia provided us with a unique opportunity to test this hypothesis. We obtained pretransplantation BM aspiration samples from patients undergoing BM transplantation in Pesaro, Italy and from their allogeneic donors. The erythroid precursors were isolated using ficoll sedimentation and then panning selecting fro CD45- cells. Cytospin and Giemsa staining showed that the separation provided greater than 90% erythroblasts. Five million of these erythroblasts were lysed and their DNA was isolated. There were obvious ladder patterns of DNA breakdown products in beta-thalassemia major samples, with less occurring in beta-thalassemia trait. Normal individuals showed only a slight smear of breakdown of DNA. These results indicate there is enhanced apoptosis in the erythroblasts in the BMs of Cooley's anemia patients. This finding might partially explain why most of these erythroblasts never survive to become mature erythrocytes.

Apoptosis↗
PubMed1993

Fine-needle aspiration of cutaneous malakoplakia.

A 99-yr-old Chinese woman with cutaneous malakoplakia and concomitant urinary tract infection was reported. The patient presented with an ulcerated right lower quadrant mass and computerized tomography showed that it was limited to the skin and subcutaneous tissue with no extension to the pelvic or abdominal structures. The patient also suffered from urinary tract infection and was treated with oral norfloxacin. The ulcerated subcutaneous mass disappeared on follow-up visit 6 months after presentation. The cytologic (fine-needle aspiration), histologic (trucut biopsy) and ultrastructural features of cutaneous malakoplakia were described. The possible usefulness of fine-needle aspiration in the diagnosis of this condition was discussed.

Abdomen↗
PubMed1993

Genomic structure, chromosomal location, and evolution of the mouse Hox 8 gene.

We isolated genomic clones containing the mouse Hox 8 gene, a member of the msh gene family. We show that Hox 8 comprises two exons of approximately 600 and 691 bp separated by a 3.5-kb intron, and that it cosegregates with previously mapped markers in the distal region of mouse chromosome 13. In midgestation embryos, the Hox 8 gene produces transcripts of 1.4 and 2.2 kb. Both transcripts are present in facial tissues of the newborn mouse, though the ratio of the 2.2-kb transcript to the 1.4-kb transcript is reduced relative to the ratio observed for midgestation embryos. An alignment of the homeobox sequences of previously characterized members of the msh family revealed three subclasses: Hox 7-like genes, Hox 8-like genes, and msh-like genes. Both the Hox 7-like genes and Hox 8-like genes are present throughout the vertebrates. Representatives of the third subclass, the msh-like genes, are found in a protostome (Drosophila) and a deuterostome (Ciona) and are thus likely to be phylogenetically widespread. To investigate the distribution of Hox 8-like genes outside the chordates, we used the polymerase chain reaction and degenerate Hox 8 primers to screen genomic DNA of the purple sea urchin (Strongylocentrotus purpuratus, Phylum Echinodermata). We isolated a gene with greater sequence similarity to mouse Hox 8 than to members of the Hox 7 or msh subfamilies, demonstrating that the Hox 8 subfamily has been in existence at least since the echinoderms diverged from the lineage that gave rise to the chordates.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Secretory monoclonal IgA antibody to human sperm produced by gastrointestinal immunization inhibits human sperm activity and mouse in vitro fertilization.

BALB/c mice were immunized intragastrically with human sperm. Cells from the Peyer's patches and spleens of the immunized mice were for the preparation of hybridomas secreting antisperm monoclonal IgA (mcIgA). The specific ratio of IgA-secreting cells in Peyer's patches was much higher than that in spleen. The binding site on human sperm of 9 of 19 mcIgA was in the post-acrosomal region using an immunofluorescent assay. Two of eight selected mcIgA caused strong human sperm agglutination and three of them produced significant inhibition of mouse in vitro fertilization. No mcIgA tested caused obvious human sperm immobilization or inhibited mouse in vivo fertilization. In vitro assembly of selected mcIgA in ascites with mouse secretory component (SC) caused no significant changes in effects on sperm function and in vitro fertilization. By use of Western blotting, dimer or higher polymers were demonstrated in all selected mcIgAs and corresponding protein antigens in 6 of 8 selected mcIgAs. These results suggest that human sperm function may be inhibited and fertilization rate reduced by specific secretory IgA to human sperm and that secretory immunity to protein antigens of human sperm could be induced by intragastrointestinal immunization.

Animals↗
PubMed1993

Combination therapy: photochemotherapy; electric current; and ionizing radiation. Different combinations studied in a WiDr human colon adenocarcinoma cell line.

The interactions of pairs of the modalities Photofrin II-sensitized photochemotherapy (PCT), ionizing radiation and an electric current were investigated by the colony formation assay in WiDr cells, a human colon adenocarcinoma cell line. When the cells were treated simultaneously with PCT and an electric current, a slightly synergistic effect was observed at low exposures (surviving fraction approximately 0.1) while a seemingly antagonist effect was found at higher exposures. The same was found to be true for the combinations of PCT plus ionizing radiation and ionizing radiation plus electric current.

Adenocarcinoma↗
PubMed1993

Acidosomes: recipients of multiple sources of membrane and cargo during development and maturation.

Acidosomes are organelles that in Paramecium are responsible for the acidification of phagosomes before phagosomes fuse with lysosomes. Using a combination of (a) the quick-freeze deep-etch (QF-DE) technique, (b) monoclonal antibodies (mAbs) that label specific membrane pools including those of the acidosomes, and (c) horseradish peroxidase (HRP)-uptake studies, we followed the development of acidosomes from the Golgi complex as well as the rapid transfer of HRP into the acidosomes. We also studied some of the characteristics of the involved membrane pools. Morphologically, acidosomes were first detected in the cytosol near the ER and Golgi stacks as clumps of tubules and vesicles, which apparently coalesced to form larger spherical or elongated preacidosomes. These clumped vesicles and preacidosomes had a QF-DE morphology resembling that of the mature acidosomes and were specifically labeled with mAbs that also labeled mature acidosomes. Within 10 s HRP cargo could be internalized by acidosomes while they were docked at the nascent vacuole membrane. This rapid uptake of HRP along with membrane occurs by vesicle fusion, a conclusion supported by QF-DE images. Thus the acidosome obtains its membrane from at least two sources, from the trans-Golgi network, and from the small HRP-containing vesicles. Cargo can also be acquired from two sources, the Golgi apparatus and the transport vesicles. Since it acquires non-particulate exogenous marker we conclude that the acidosome is linked to the endocytic pathway.

Animals↗
PubMed1993

Vacuolar H(+)-ATPase of Dictyostelium discoideum. A monoclonal antibody study.

A Dictyostelium membrane fraction rich in vacuolar proton pumps, previously described by Nolta et al. (J. Biol. Chem. 266, 18,318-18,323, 1991), was used as the immunogen for production of monoclonal antibodies. We obtained antibodies that recognized polypeptides of 100 kDa and 68 kDa, corresponding to the two largest subunits of the vacuolar proton pump. In indirect immunofluorescence experiments, these two subunits were located on an interconnected collection of tubules and vacuoles. On frozen thin sections they were found principally on membranes of vacuoles and collections of small vesicles typically located just internal to the plasma membrane. These vesicles and vacuoles had electron-translucent lumens. No other structures in axenically grown Dictyostelium cells were labeled to a significant extent by these two antibodies. Using an affinity-purified antibody to calmodulin and a monospecific antibody to the B subunit of the chromaffin granule vacuolar ATPase, markers known to label the membranes of the contractile vacuole complex in Dictyostelium (Zhu and Clarke, J. Cell Biol. 118, 347-358, 1992; Heuser et al., J. Cell Biol. 121, 1311-1327, 1993), we showed that the 100 kDa and 68 kDa subunits had the same distribution as these two markers. Co-localization was seen in both interphase and mitotic cells. Thus, our results support the conclusion that vacuolar proton pumps are located principally on the membranes of the contractile vacuole complex in Dictyostelium. In addition, in indirect immunofluorescence experiments, these monoclonal antibodies provided improved images of the organization of the contractile vacuole system.

Animals↗
PubMed1993

Fatal necrotizing fasciitis due to Vibrio damsela.

A patient who succumbed to fulminant necrotizing fasciitis due to Vibrio damsela after injury by a rabbitfish is described. Despite the absence of any known underlying illness, he did not respond to appropriate antibiotic therapy and radical surgical intervention. This represents the first documented case of necrotizing fasciitis due to this organism, and is also the first reported case in Southeast Asia inflicted by rabbitfish.

Animals↗
PubMed1993

Evidence for nitric oxide-generator cells in the brain.

Nitric oxide (NO) is a free radical that has been recently recognized as a neuronal messenger molecule. In order to understand the way in which NO functions in the central nervous system (CNS), it is important to identify the NO-generator and NO-target cells in the brain. I measured firstly the distribution of NO synthase in the brain, which catalyzes L-arginine to form NO, by the measurement of citrulline formation that is also synthesized from L-arginine together with NO in equal molar bass. In the brain of adult rat, the most potent activity of NOS was apparent in the cerebellum, next in the olfactory bulb and medium in the cerebrum. Further, in the presence of NADPH and Ca2+, NOS activity was detected in the neuron cultures derived from the cerebrum of fetal rat. Astrocytes, one type of glia, prepared also from the cerebrum of fetal rat, appeared to have a small but significant NOS activity. As astrocytes possess a high amount of cytosolic guanylate cyclase that is known to be activated by NO, the changes in the intracellular cGMP levels in the astrocytes were measured as another index of NO formation. The treatment of astrocytes with NOS inhibitor caused the suppression of the intracellular cGMP levels. These results indicate that NO is definitely produced by astrocytes. In addition, in the blood vessel system of the brain, although NOS has been thought to be localized in the endothelial cells of only larger vessels, NOS activity was also observed in the microvessel endothelial cells of the cerebrum of both adult and fetal pig. These data suggest that neuronal cells may be the major site of NO generation in the brain, and that the NOS is a constitutive type. The data also suggest that astrocytes can also express constitutive NOS, although the potency is not so large. Microvessel endothelial cells of the brain are also one of the sources of NO. The NO produced by these cells increases the cGMP levels in the astrocytes and may affect some physiological and/or pathophysiological events in the brain.

Amino Acid Oxidoreductases↗
PubMed1993

[Changes of immunologic function in patients with COPD induced chronic cor pulmonale].

We determined the counts of lymphocyte subpopulation CD3+, CD4+, CD8+ and CD16+ in PBL by using APAAP method and some humoral immunological parameters (HIP) in patients with COPD induced chronic cor pulmonale. The results showed: (1) In cases during exacerbation stage, the counts of CD3+, CD4+, CD16+ and the CD4+:CD8+ ratio decreased remarkably (P < 0.001). There was significant correlation between the counts of CD3+, CD4+, the CD4+:CD8+ ratio and PaO2 (P < 0.01). No marked change in serum IgG, IgA and IgM level was observed. Serum IgE and CIC level was significantly higher and C3 level lower than those in controls (P < 0.01). After treatment the counts of CD3+, CD4+, CD16+ and the CD4+:CD8= ratio went up notably (P < 0.01), but no significant change was found in the HIP. (2) In cases during remission stage only the CD4+ level was low (P < 0.05) and no remarkable difference was observed in the HIP. After treatment with thymopeptide the counts of CD4+ increased (P < 0.05), CD8+ decreased (P < 0.01) and the CD4+:CD8+ ratio increased (P < 0.01). The serum IgA and CIC level also went up significantly (P < 0.05). This indicated that thymopeptide played a role in regulating the immunologic function.

Aged↗
PubMed1993

Experimental studies of laser myocardial revascularization in rats.

Myocardial revascularization by Nd: YAG laser used in rats with myocardial infarction was studied. The left coronary artery was ligated and the laser channels with a diameter of 300 microns were made immediately by 2.5-4.2 W lasersonics YAG unit. After 24 hours, the rats were killed. Evaluation included hemodynamics, lactate dehydrogenase of myocardium and myocardial infarct size. The results showed that laser myocardial revascularization reduced myocardial infarct size and enzyme leakage, and improved left ventricular function. The study may provide theoretical basis for the clinical applications of this new technique in the treatment of ischemic heart disease.

Animals↗