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Biomedical subjects

L Ma

Publications and source records attributed to L Ma.

At least 541 records · Page 30Linked to original sources
PubMed1991

Fibrinolytic enzyme from Agkistrodon halys brevicaudus (Korean mamushi) snake venom.

By means of DEAE-Sepharose CL-6B ion exchange chromatography and TSK-GEL G2000 SW high-performance gel filtration, a purified protein with fibrinolytic activity was obtained from the venom of Agkistrodon halys brevicaudus (Korean mamushi). The protein was homogeneous as judged by isoelectric focusing electrophoresis and high-performance gel filtration. Its mol. wt is 39,200 and its isoelectric point 4.12. The specific fibrinolytic activity of the protein was 3.2 times higher than that of the crude venom. The fibrinolytic activity of the purified principle was 33 units/mg protein (units of standard urokinase activity).

Amino Acids↗
PubMed1991

Characterization of the mouse homolog of the XPBC/ERCC-3 gene implicated in xeroderma pigmentosum and Cockayne's syndrome.

The human XPBC/ERCC-3 DNA repair gene specifically corrects the repair defect of xeroderma pigmentosum (XP) complementation group B and rodent repair mutant cell lines of group 3. The gene encodes a presumed DNA- and chromatin-binding helicase involved in early steps of the excision repair pathway. To study the evolution of this gene, its expression in different tissues and stages of development and to permit the generation of a mouse model of XP by targeted gene replacement in mouse embryonal stem cells, we have isolated the mouse XPBC/ERCC-3 homolog. Sequence comparison of the predicted protein revealed a 96% amino acid identity with the human gene product. Notably, all postulated functional domains were strictly conserved. The mouse XPBC/ERCC-3 promoter is--like its human counterpart--devoid of classical promoter elements such as TATA and CAAT boxes and contains several conserved segments with unknown function. One of these conserved regions, consisting in part of a polypyrimidine track, is also present in the ERCC-1 promoter. The mouse XPBC/ERCC-3 gene is expressed constitutively at low levels in all tissues examined except for testis, where its expression is significantly enhanced.

Amino Acid Sequence↗
PubMed1991

Kahn's wire passer used in medial canthal tendon fixation.

The history of fixation of the medial canthal structures is one of gradual improvement in instrumentation and technique. Today, open reduction and internal fixation remain the mainstay of treatment for the medial canthal structures. With regard to the internal fixation method, we have developed a wire passer that can facilitate wire fixation of the delicate medial canthal tendon. We present two cases that manifest abnormalities of the medial canthal tendon. Both were corrected successfully with this wire passer.

Adult↗
PubMed1991

[Experimental study on the relationship between burn shock and infection].

It is well known that burned patients with difficulty in passing through the shock stage are commonly complicated by early septicemia. But explanations about the mechanism vary and no one can account for all the cases. In the present study, Specific Pathogen-free mice (950), Germfree mice (50) and Wistar rats (720) were used in studying 25%-30% burn injury; limited time of hypotension; endotoxemia and simple intestinal obstruction to determine if the bacteria could translocate across the viable intestinal wall to cause systemic infection. The data showed that microflora from gut can cause systemic infection following early burn injury; and shock, endotoxemia and ileus which always complicate severe burns can function together in promoting bacteria translocation. These results suggest that gut origin infection may play an important role in irreversible burn shock and/or early fulminating septicemia following burn injury.

Animals↗
PubMed1991

[The establishment and characterization of the anti-idiotypic monoclonal antibody-NP30 of Schistosoma japonicum].

A hybridoma cell line secreting an IgM monoclonal antibody designated NP30 was obtained from a fusion of SP2/o and spleen cells of a BALB/c mouse chronically infected with schistosoma japonicum for one and a half year and identified by screening with immunized rabbit sera against gut-associated antigen (GAA) and soluble egg antigen (SEA) of S. japonicum, indicating that the NP30 was an anti-anti-antigen or anti-antibody. NP30 was further determined to be an anti-idiotypic antibody (anti-id) which was serologically and functionally identical to GAA, so that it could be portrayed as the internal image of GAA, which might have the potential to be used as an antigenic reagent in immunodiagnostic assays of schistosomiasis japonica.

Animals↗
PubMed1991

[The humoral immune response of different strains of mice after intragastrointestinal immunization with human sperm antigens].

The inbred Balb/c and C57 mice, and the outbred Swiss Webster mice were intragastrointestinally immunized with human sperm antigens. The lymphocytes from the spleen, mesenteric lymph node (MLN), Peyer's patch (PP) and uterus or epididymis were isolated and cultured. The lymphocyte-secreting antisperm IgG and IgA and the antisperm antibodies in the gut wash and serum were determined with enzyme-linked immunosorbent assay (ELISA). In the Balb/c and Swiss Webster mice, the immune responses to sperm have shown to be stronger than that in C57, stronger in female than in male. The antigenicity of sperm membrane extracts seems to be higher than that of whole sperm. Antisperm antibodies secreted by lymphocytes from the epididymis and uterus have demonstrated to be detectable. For stimulation of the local immune response, the intra-PP and intralumina immunizations are more effective than others.

Animals↗
PubMed1991

[Experimental study on the immunomodulatory effects of rhubarb].

The immunomodulatory effects of Rhubarb on the murine functions are reported. Varying dosages of Rhubarb administrated orally were able to increase the delayed hypersensitivity response induced by bovine serum albumin and proliferation response of murine spleen cell to Con A and lipopolysaccharide. The above description indicate that Rhubarb could promote immune response.

Animals↗
PubMed1990

Identification and characterization of large, complex forms of chloroplast translational initiation factor 2 from Euglena gracilis.

Chromatography of partially purified preparations of Euglena gracilis chloroplast initiation factor 2 (IF-2chl) on gel filtration resins indicates that this factor is present in high molecular mass forms ranging from 200 to 700 kDa. The higher molecular weight complexes can be separated from the 200,000 Mr form of this factor by chromatography on DEAE-cellulose. Further purification indicates that the majority of the IF-2chl is present as dimeric, tetrameric, and probably hexameric complexes of polypeptides of 97,000-110,000 in molecular weight. In addition, one form consisting of subunits of about 200,000 Mr has been detected. All of these species are active in promoting fMet-tRNA binding to chloroplast 30 S subunits in a message-dependent reaction. Initiation complex formation promoted by IF-2chl requires the presence of GTP. Similar levels of binding are obtained when GTP is replaced by a nonhydrolyzable analog suggesting that IF-2chl is acting stoichiometrically rather than catalytically under the conditions used. The activity of this factor is stimulated by the presence of either Escherichia coli or chloroplast IF-3. None of the forms of IF-2chl detected is active on E. coli ribosomes.

Animals↗
PubMed1990

Obstructed intestine as a reservoir for systemic infection.

Intestinal motility, absorption, and secretion are altered after intestinal obstruction, but at what point the normal bacterial barrier function of the viable gut fails after intestinal obstruction is unclear. Thus, we tested whether after simple intestinal obstruction bacteria would translocate across the viable intestinal wall to cause systemic infection. Within 6 hours of intestinal ligation 1 cm proximal or distal to the ileocecal valve, bacteria had translocated to the mesenteric lymph nodes, and by 24 hours after intestinal obstruction, bacteria had spread to the liver, spleen, and blood stream. Bacterial translocation rarely occurred in the animals undergoing laparotomy and sham intestinal ligation, indicating that bacterial translocation was not due to surgical stress. Based on the results of these studies, bacterial translocation induced by intestinal obstruction appears to be due to disruption of the ecology of the normal gut microflora, leading to intestinal overgrowth with certain enteric bacilli and mucosal damage. Although the exact mechanism(s) by which simple mechanical obstruction injures the intestine is not known, the fact that mucosal injury did not occur in germ-free mice suggests that bacteria may play a role in the pathogenesis of obstruction-induced intestinal injury.

Animals↗
PubMed1990

Protein malnutrition predisposes to inflammatory-induced gut-origin septic states.

The development of an uncontrolled inflammatory response has been implicated in the pathogenesis of adult respiratory distress syndrome and multiple-organ failure. Because zymosan activates complement and induces a systemic inflammatory response, the effect of zymosan on intestinal structure and barrier function was measured in normally nourished (NN) and protein malnourished (PM) mice. Normally nourished and protein malnourished (up to 21 days) mice challenged intraperitoneally with zymosan (0.1 mg/g body weight) were killed 24 hours after zymosan challenge and their organs cultured for translocating bacteria. Zymosan-induced bacterial translocation was limited to the mesenteric lymph nodes of the NN mice, whereas translocating bacteria spread from the gut to the liver, spleen, and blood stream (p less than 0.05) in the PM mice. Zymosan-induced bacterial translocation appeared to be related primarily to the combination of mucosal injury and a disruption of the gut flora ecology in the PM mice and to mucosal injury in the NN mice. The extent of mucosal injury was greater the longer the mice were protein malnourished before zymosan challenge. The effect of zymosan on survival was measured in separate groups of mice. At a dose of 0.1 mg/g body weight, no deaths occurred in NN mice or in 7-day PM mice. However 20% of the 14-day PM mice and 80% of the 21-day PM mice receiving zymosan died. Thus PM predisposes to mucosal damage and the development of potentially lethal gut origin septic state during periods of systemic inflammation.

Animals↗
PubMed1990

Human papillomavirus in oesophageal squamous cell carcinoma.

Thirty seven cases of oesophageal squamous cell carcinoma were studied by applying DNA slot blot analysis and in situ hybridisation using type specific probes for HPV 6, 11, 16 and 18. Cases of condyloma accuminata, cervical carcinoma, and laryngeal papilloma were used as controls. Blocks including areas of invasive carcinoma, intraepithelial neoplasia, and normal epithelium were studied in each case. No HPV genome was detectable in any of the oesophageal cases. It is concluded that these types of HPV do not have an association with oesophageal squamous cell carcinoma.

Carcinoma, Squamous Cell↗
PubMed1990

Localisation of CD10 to biliary canaliculi by immunoelectron microscopical examination.

Common acute lymphoblastic leukaemia antigen (CALLA) was first characterised in lymphoid leukaemic cells. The antigen is present in different stages of lymphoid cell differentiation as well as in subsets of myeloid cells, and further studies have also shown its presence in non-lymphoid tissues. The recent cloning and sequencing of the gene permitted deduction of its amino acid sequence which is identical with the human membrane-associated enzyme, neutral endopeptidase. Strong immunostaining for CALLA was detected in the human liver with a canalicular pattern. Immunoelectron microscopy also confirmed that the antigen was localised only in the area of the bile canaliculi. Although the function of neutral endopeptidase in the canaliculi is unknown, this antigen may prove useful in the study of biliary function and diseases.

Antigens, CD↗
PubMed1990

Myelodysplastic syndrome presenting with generalized cutaneous granulocytic sarcomas.

A patient with myelodysplastic syndrome (refractory anemia with excess of blasts in transformation, RAEB-T) presented with generalized granulocytic sarcomas involving the skin. The diagnosis was confirmed by skin and bone marrow biopsies. Partial myeloperoxidase deficiency was noted in the circulating polymorphonuclear leukocytes and the more differentiated tumor cells in the granulocytic sarcoma. This observation suggests that such leukocytes may be derived from the abnormal 'leukemic' clone.

Aged↗
PubMed1990

[Effects of the polysaccharides isolated from mycelium and fermentation fluid of Schizophyllum commune on immune function in mice].

SPG1 and SPG2 are polysaccharides extracted respectively from fermented cultural mycelium and fermentation fluid of Schizophyllum commune. This paper reports the effect of SPG1 and SPG2 on concanavalin A (Con A) induced proliferation of lymphocyte from C57BL/6J mice in vitro. SPG1 (10, 25, 50 and 100 micrograms/ml) and SPG2 (10, 50 and 100 micrograms/ml) was found to significantly increase lymphocyte proliferation. In addition, SPG1 (10, 25, 50 and 75 micrograms/ml) antagonized the suppressive effect of hydrocortisone on proliferation of mouse spleen cells, while SPG2 did not. In vivo, at the dose of 2.5 and 5.0 mg/kg ip for 9 days, SPG1 and SPG2 remarkably enhanced the delayed-type hypersensitivity to 2, 4-dinitrochlorobenzene (DNCB) in mice. SPG1 (1.25, 2.5 and 5.0 mg/kg, ip for 1 day) and SPG2 (2.5 and 5.0 mg/kg, ip for 1 day) promoted the plaque forming cell (PFC) response to sheep red blood cells (SRBC) in mice. The effects of SPG1 and SPG2 on immune function were studied in aged immunodeficient mice. SPG1 (10 and 25 micrograms/ml) and SPG2 (25 micrograms/ml) was found to enhance the Con A induced lymphocyte proliferation in 14 months aged mice. At the dose of 2.5 mg/kg, SPG1 and SPG2 produced respectively 162.1 and 136.0% increase in PFC response in 14 months aged mice.

Animals↗
PubMed1990

[Experimental study on pathogenesis of endotoxin-induced gut origin infection].

It has been documented that endotoxin could induce gut origin infection. Consequently, experiments were performed to correlate endotoxin-induced gut origin infection with changes in intestinal mucosal structure and xanthine dehydrogenase and oxidase activity. Bacteria infection from the intestines to extraintestinal organs in 70% of the mice receiving endotoxin. Endotoxin injured primarily the ileal and cecal mucosa and increased ileal and hepatic xanthine dehydrogenase and cecal oxidase activities (P less than 0.05). These results suggest that xanthine oxidase-induced mucosal damage plays a role in endotoxin-induced gut origin infection.

Animals↗