Search PubMed⌕ Search

Biomedical subjects

J L Li

Publications and source records attributed to J L Li.

At least 109 records · Page 6Linked to original sources
PubMed1995

Identification of phosphocholine-containing glycoglycerolipids purified from Mycoplasma fermentans-infected human helper T-cell culture as components of M. fermentans.

Previously, we have reported the occurrence of novel phosphocholine-containing glycoglycerolipids (GGPLs: GGPL-I and GGPL-III) in human helper T-cell (MT-4 cell line) (Mustuda et al, Glycoconjugate J. 10:340). However, the GGPLs disappeared from the MT-4 after treatment with an antimycoplasma agent. This disappearance suggested the involvement of microorganisms in the GGPL expression. In this paper, we show that the novel lipids are components of Mycoplasma fermentans itself. The supernatant fluid of the antimycoplasma agent-untreated Mt-4 cell culture produced mycoplasma-like colonies on PPLO agar plates, and PCR and immunological methods revealed the presence of M. fermentans. GGPLs were expressed again in the treated Mt-4 cells after infection with the isolated M. fermentans. The isolated M. fermentans had glycoglycerolipids corresponding to GGPL-I and GGPL-III. Thin-layer chromatography-mass spectrometry and immunological analyses showed that these glycoglycerolipid which were derived from the isolated M. fermentans were identical with GGPL-I and GGPL-III previously obtained. This is the first report that shows mycoplasma has phosphocholine-containing glycoglycerolipids.

Animals↗
PubMed1994

High prevalence of p53 protein overexpression in patients with esophageal cancer in Linxian, China and its relationship to progression and prognosis.

BACKGROUND: Linxian is the highest endemic area of esophageal squamous cell carcinoma (ESCC) in China and one of the highest incidence areas in the world. The relationship of p53 protein accumulation to geographic variation, pathologic findings, and prognosis has not been investigated extensively. METHODS: Formalin fixed, paraffin embedded ESCC tissues from 100 patients who underwent esophagectomy between 1973 and 1983 were immunostained by using monoclonal antibody pAB1801. RESULTS: p53 overexpression was observed in 41 (87.2%) of 47 tumors of patients in Linxian and in 16 (64%) of 25 additional patients outside Linxian. Its prevalence in the noncancerous epithelium (11/72, 15.3%) and carcinoma in situ (1/7, 14.3%) was lower than that in invasive lesions (64/93, 68.8%). Its immunostaining intensity increased with the depth of cancer invasion. Of 30 primary carcinomas with lymph node metastasis, 29 (96.7%) were positive. However, only 36 (51.4%) of 70 primary lesions without metastasis were positive, and a higher intensity was noticed in the metastases. There was a lower expression rate in tumors of patients surviving more than 10 years (25/52, 48.1%) than in those surviving less than 3 years (40/48, 83.3%). Overall and nonadvanced or metastasis-free cumulative survival rates were both significantly different in patients with and without p53 protein overexpression. CONCLUSIONS: There is a higher expression rate of p53 protein in ESCC in tumors of patients from Linxian than in those from the surrounding area. The accumulation of p53 protein is related to the invasiveness and capability for metastases of cancer cells and appears to be a useful prognostic factor for patients with ESCC.

Adult↗
PubMed1994

Bispecific anti-CD22/anti-CD3-ricin A chain immunotoxin is cytotoxic to Daudi lymphoma cells but not T cells in vitro and shows both A-chain-mediated and LAK-T-mediated killing.

We have generated a bispecific anti-CD22/anti-CD3 immunotoxin (IT) and determined whether it would exert both lymphokine-activated killer (LAK) T cell-mediated and ricin A chain (dgA)-mediated toxicity to Daudi tumor cells but not to T cells in vitro. One parental IT, Fab'-anti-CD22-dgA makes a potent immunotoxin for B cells, but not T cells, while the other, Fab'-anti-CD3-dgA, kills neither T nor B cells. Three mouse quadromas were generated and the bispecific Abs (BsAbs) were purified by double affinity chromatography. Two of the three purified BsAbs induced significant proliferation and IL-2 production in T cells. All three BsAbs induced LAK-T cell-mediated specific lysis of CD22+ Daudi cells. Two of the purified Ab were conjugated to dgA. Using a 51Cr release assay in the presence of LAK-T cells and Daudi target cells, the IC50s of the BsAbs were 3.5 x 10(-10) M and 9 x 10(-11) M, as compared to 2.1 x 10(-11) M and 3.2 x 10(-11) M, for their respective ITs. Hence, in the presence of LAK-T cells, the BsITs were 3- to 17-fold more cytotoxic than unconjugated BsAbs in 51Cr-release assays. Daudi cells were also treated in vitro with different mixtures of LAK-T cells, BsAbs, and BsITs and then adoptively transferred into SCID mice. As determined by the mean paralysis time of the recipients, in the presence of LAK-T cells the BsITs had impressive anti-tumor activity.

Antibodies, Bispecific↗
PubMed1994

[A transposition of iliopsoas in replacement of pelvic floor for incontinence of urination and/or defecation in children].

Fourteen patients, the age ranged from 2 to 12 years, with fecal and/or urinary incontinence were treated between 1991 and 1993 using a transposition of iliopsoas in replacement or strengthening of pelvic floor. The results were encouraging. The evaluation of the function of pelvic floor was described. Levator plays an important role in normal mechanism of defecation as well as urination. Several types of incontinence develop while the disfunction of pelvic floor occur and some function of continence could be restored by an operation of transposition of iliopsoas.

Child↗
PubMed1994

[Effects of plant polysaccharides on cell proliferation and cell membrane contents of sialic acid, phospholipid and cholesterol in S 180 and K 562 cells].

The four kinds of plant polysaccharides, i.e., pachyman polysaccharides (PPS), Acanthopanax senticosus polysaccharides (ASPS), polysaccharides of tremella fuciformis (TF) and lentinan, have obviously inhibitory action against the animal tumor growth and have been applied to the treatment of cancer. The mechanism was that they could enhance the body immune function, but whether the tumor cells were killed is not clear. In this paper, the effects of the four plant polysaccharides on cell proliferation in mice sarcoma (ascitic type) S180 and human chronic myelogenous leukemia K562 cells were studied with MTT chromometry. Tt was found That TF and lentinan had no effect on both cell line, but PPS and ASPS could obviously inhibit the proliferation of them, the IC50 of PPS was 1.5mg/ml in both cell line, that of ASPS was 0.38 mg/ml (S180 cells) and 0.28mg/ml (K562 cells) respectively. This result indicated that the PPS and ASPS were able to kill the tumor cell directly. To investigate the mechanism of antitumor action of PPS and ASPS, the sialic acid (SA), phospholipid (PI) and cholesterol (Ch) contents of S180 cell membrane were examined after the PPS or ASPS application for 24 hours. No significant changes were observed for the Ch and Ch/Pl ratio, the amount of SA increased and that of PI lowered respectively (P < 0.05). The results suggested that the antitumor action of PPS and ASPS not only related to the action of enhancing the body immune function but also related to the changes of cell membrane.

Animals↗
PubMed1993

Acyclovir diphosphate dimyristoylglycerol: a phospholipid prodrug with activity against acyclovir-resistant herpes simplex virus.

Infection with herpes simplex viruses (HSVs) resistant to treatment with acyclovir (9-[(2-hydroxyethoxy)-methyl]guanine, Zovirax) is a growing clinical problem in patients with AIDS and other immunosuppressed states. Most virus isolates resistant to acyclovir are deficient or defective in virally coded thymidine kinase (TK), which converts acyclovir to acyclovir monophosphate in virus-infected cells. To restore acyclovir efficacy, we synthesized acyclovir diphosphate dimyristoylglycerol, an analog of a naturally occurring phospholipid, CDP-diacylglycerol. Its biological activity was tested in WI38 human lung fibroblasts infected with the acyclovir-resistant DM21 strain of HSV, which is TK negative due to an 816-base-pair deletion in the TK coding region. Acyclovir diphosphate dimyristoylglycerol has substantial activity in DM21-infected cells (IC50 = 0.25 microM), whereas acyclovir and acyclovir monophosphate were ineffective (IC50 > 100 microM). Similar results were obtained in TK-altered and TK-deficient strains of HSV-1 and in acyclovir-resistant isolates of HSV-2 obtained from two AIDS patients. The phospholipid prodrug is active by means of TK-independent metabolic pathways that liberate acyclovir monophosphate inside the host cell. Acyclovir phosphates were 56 times greater in WI38 human lung fibroblasts incubated for 24 hr with [8-3H]acyclovir diphosphate dimyristoylglycerol relative to acyclovir. Acyclovir monophosphate added to the culture medium (outside the cell) did not circumvent the acyclovir resistance of the TK-negative DM21 mutant, presumably due to its conversion to acyclovir by phosphatases. Acyclovir diphosphate diacylglycerol prodrugs may be useful in treating TK-deficient mutant and wild-type strains of HSV.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Experimental studies on penetrating heterokeratoplasty with human corneal grafts in monkey eyes.

In nine rhesus monkeys, human corneal grafts were used for penetrating keratoplasty in one eye of each. The data were divided into three groups according to the size of grafts. Group 1 (n = 3) received 5.5-mm human corneal grafts in 5.0-mm recipient beds; group 2 (n = 3) received 6.2-mm human corneal grafts in 6.0-mm beds; and group 3 (n = 3) received 7.5-mm grafts in 7.0-mm beds. Five of nine eyes in groups 1 and 2 (55%) maintained graft clarity for more than 1 year, but only two of the three in group 1 maintained clear human corneal grafts for 32 and 36 months, respectively. However, the three grafts in the third group maintained transparency for only 4-7 months. Our findings suggest that xenogeneic corneal grafts may have a greater success rate in humans than previously believed.

Adolescent↗
PubMed1992

Characterization of a Salmonella typhimurium aro vaccine strain expressing the P.69 antigen of Bordetella pertussis.

The P.69 Bordetella pertussis protective antigen was expressed by use of the trc promoter from the chromosome of a Salmonella typhimurium aro vaccine strain, BRD509, by integrating the prn gene, encoding the 93-kDa precursor of this protein, into the aroC locus. P.69 was detected on the cell surface of the S. typhimurium strain (BRD640) by agglutination and immunoelectron microscopy. BALB/c mice immunized orally or intravenously with BRD640 showed a significant level of protection against an aerosol challenge with virulent B. pertussis, compared with control animals. No anti-P.69 antibodies in the serum or anti-P.69 antibody-secreting cells in the lungs were detected in BRD640-vaccinated animals, although cells isolated from spleens showed a P.69-dependent cell proliferative response. In contrast, low levels of anti-P.69 antibodies in the serum and anti-P.69 antibody-secreting cells in the lungs were detected in immunized mice following a B. pertussis challenge.

Adhesins, Bacterial↗
PubMed1992

[Changes of subtypes of alpha 1-adrenoceptor in blood vessels of spontaneously hypertensive rats].

The two subtypes of alpha 1-adrenoceptors in blood vessels were compared between stroke prone spontaneously hypertensive rats (SHRSP) and WKY rats in vitro and in vivo. Pretreatment with 50 mumol/L chlorethylclonidine (CEC) for 30 min decreased the maximal contractions induced by norepinephrine (NE) to 31.4 +/- 8.3% and 35.2 +/- 2.9% (aortae); 68.4 +/- 8.2% and 80.1 +/- 7.2% (renal arteries); 68.4 +/- 6.3% and 5.4 +/- 7.0% (mesenteric arteries) of the controls in the SHRSP and the WKY rats, respectively. All the differences between the SHRSP and WKY rats were not statistically significant. In contrast, the blocking effects of nifedipine were much stronger in the SHRSP rats than those in the WKY rats. In the presence of 10 mumol/L nifedipine the maximal contractions induced by NE were decreased to 3.1 +/- 1.5% and 56.5 +/- 4.8% (P < 0.01, aortae); 9.0 +/- 4.1% and 23.6 +/- 3.5% (P < 0.05, renal arteries); 5.9 +/- 2.5% and 28.0 +/- 0.8% (P < 0.01, mesenteric arteries) of the controls in the SHRSP and the WKY rats, respectively. The experiment in vivo also showed that the effects of nifedipine on decreasing basal blood pressure and on antagonizing phenylephrine were increased in the SHRSP rats, as compared to the WKY rats. Analyses of two components of the contractions induced by 10 mumol/L NE in aortae demonstrated that both phasic and tonic contractions were mainly caused by activations of the alpha 1B subtype. There were no significant differences of blocking effects of nifedipine on the phasic contractions between the SHRSP and WKY rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Immunization strategies for the production of rat monoclonal anti-idiotope antibodies.

Anti-idiotypic antibodies are powerful reagents for the study of immunoregulation, and have potential interest as vaccines against tumors and infectious diseases. Three immunization strategies for the production of rat monoclonal anti-idiotope antibodies have been compared in this paper. Male Wistar rats were immunized i.p. and at multiple subcutaneous sites with 750 micrograms of purified monoclonal antibody against Plasmodium falciparum for three times and subsequently boosted by (1) intraperitoneal injection with 750 micrograms of the immunogen, (2) intravenous inoculation with 400 micrograms of the IgG, and (3) intrasplenic immunization with 200 micrograms of the idiotype. With the intraperitoneal boost method, the frequency of hybrids with anti-idiotope activity was 0.3-0.9% with 62.8-85.2% of the seeded wells containing hybrids. In the intravenous boost group, the percentage of hybrids demonstrating anti-idiotope activity increased to 11.0-13.3% with 80.2-97.9% of the hybrid efficiency. When immunized by the intrasplenic boost route, the frequency of anti-idiotope hybrids generated rose to 12.9-16.4% with 82.3-96.6% of the hybrid efficiency. There was no obvious effect of the boost immunizing methods on the generation of rat monoclonal anti-mouse IgG antibodies. These results indicated that the multiple-site immunization followed by intravenous or intrasplenic boost injection was an appropriate immunizing method for the production of monoclonal anti-idiotope antibodies.

Animals↗
PubMed1991

Identification and characterization of a protective immunodominant B cell epitope of pertactin (P.69) from Bordetella pertussis.

Epitopes defined by monoclonal antibodies (mAb) specific for the Bordetella pertussis outer membrane protein P.69 (pertactin) were mapped using a series of amino- and carboxy-terminal deletion mutants expressed in Escherichia coli. mAb were found to bind predominantly to a region of pertactin spanning a (Pro-Gln-Pro)5 repeat motif and one mAb was found to bind to another region spanning a (Gly-Gly-Xaa-Xaa-Pro)5 repeat motif. To localize further the mAb-binding sites, a panel of synthetic peptides, a series of 94 overlapping hexameric peptides, and a P.69 30-amino acid fusion to a hepatitis B core protein (HBcAg-69), were synthesized. This combined approach has identified the binding site for the mAb BBO5: Pro-Gly-Pro-Gln-Pro-Pro; mAb BBO7, E4A8 and E4D7: Ala-Pro-Gln-Pro-Pro-Ala-Gly-Arg; and mAb BPE3: Thr-Leu-Trp-Tyr-Ala-Glu-Ser-Asn-Ala-Leu-Ser-Lys-Arg. We have used a non-lethal murine respiratory model of B. pertussis infection to investigate the ability of a peptide containing the epitope of the mAb BBO5 to elicit protective immunity. Immunization of mice with the HBcAg-69 protein prevented growth of B. pertussis in the lungs compared to mice receiving HBcAg alone, and protection correlated with high titers of anti-P.69 antibodies.

Amino Acid Sequence↗
PubMed1991

[Changes of alpha 1-adrenoceptor and its subtypes in blood vessels of old rats].

Differences in the vascular alpha 1-adrenoceptor reserve and alpha 1a to alpha 1b subtype ratio between old (18 months) and young (3 months) rats were investigated by both in vitro and in vivo experiments. For the in vitro experiments, ring preparations of blood vessels with endothelium removed were prepared and were perfused with Kreb's solution. Antagonists for alpha 2- and beta-adrenoceptors were put in perfusate in order that norepinephrine (NE) could only activate alpha 1-receptor. The results showed that, in comparison with young rats, the maximal contractions induced by NE in aorta, renal arteries and mesenteric arteries isolated from old rats were not changed but the concentration-response curves were shifted to the right. Functional dissociation constant KA for NE was not changed but the ratio of KA to EC50 was decreased. In the aortae and mesenteric arteries from old rats, the blocking effect of chlorethylclonidine (CEC, selective alpha 1b-subtype antagonist) on NE-induced contraction was decreased significantly, while the effect of nifedipine (selectively blocks the response of alpha 1a-subtype) was increased. The in vivo experiments showed that the effect of nifedipine in lowering blood pressure was stronger in the old rats than in the young rats, while following administration of nifedipine, the effect of phenylephrine in raising blood pressure was weaker. These results indicate that, in comparison with the young rats, the alpha 1-adrenoceptor reserve is decreased and the ratio of alpha 1a-subtype to alpha 1b subtype is increased in blood vessels of old rats.

Aging↗
PubMed1991

Cholesterol requirement for growth of IR983F and P3X63-Ag8-U1 myeloma cells in serum-free medium.

Cholesterol, a major lipid component of the plasma membrane, is thought to have profound effects on the structure and function of cells. Most animal tissues are capable of synthesizing cholesterol de novo from acetate; however, there are relatively few mammalian cells in vitro expressing an absolute requirement for an exogenous source of cholesterol. In this paper, it was shown that both IR983F (983) rat myeloma cells and P3X63-Ag8-U1 (P3U1) mouse myeloma cells which had been cultivated in serum-free medium containing cholesterol for more than 6 months still required cholesterol in vitro for growth in serum-free medium. Optimal growth of 983 and P3U1 occurred in cholesterol concentrations of 15 and 5 micrograms/ml, respectively. Moreover, it was demonstrated that the cholesterol could be replaced by human low density lipoprotein in a concentration of 10 micrograms/ml but not by mevalonic acid lactone. In contrast to the parental myeloma cells, hybridoma cells derived from the mouse myeloma cells which had been cultivated in serum-free medium containing cholesterol for more than 6 months did not require cholesterol.

Animals↗
PubMed1991

Detection of blood stage antigens of Plasmodium vivax by sandwich ELISA using pan-species monoclonal antibodies and polyclonal antibodies.

This paper reports an improved PcAb-McAb-ELISA test to detect blood stage Plasmodium vivax antigen in which the plates were coated with rabbit anti-P. cynomolgi polyclonal antibody to capture the antigens in test samples and two monoclonal antibodies, M26-32 and 3F9, were added together to react with the captured antigens. The coincidence rate with this test was 93% with microscopically confirmed P. vivax cases, 97% with normal samples, 95% with microscopically negative fever cases from nonendemic areas and 86% from endemic areas, respectively. The sensitivity was greater than 1 parasite/10(5) RBC.

Antibodies↗
PubMed1990

Preliminary studies of serum glycoconjugates in patients with cancer using the enzyme-linked lectin assay.

After primary analyses on the serum glycoconjugates of lung cancer and normal individual using the enzyme-linked lectin assay (ELLA) with 12 kinds of lectins, PHA and LCA were selected for further study in the sera of 8 kinds of cancers, 4 kinds of non-malignant diseases and a kind of postoperative cancer. It was found that the test values of 7 kinds of cancers with PHA or LCA were significantly higher than those of the normal (P less than 0.01); the values of 4 kinds of non-malignant diseases with PHA were not higher (P greater than 0.05); the values of the postoperative cancer with PHA were obviously lower than those of the preoperative (P less than 0.02). The results showed that the serum glycoconjugates which can bind to PHA seemed related to the cancerous existence in human bodies. The significance of the findings was discussed.

Coronary Disease↗
PubMed1989

Oxygen reduction and lipid peroxidation by iron chelates with special reference to ferric nitrilotriacetate.

A certain iron chelate, ferric nitrilotriacetate (Fe3+-NTA) is nephrotoxic and also carcinogenic to the kidney in mice and rats, a distinguishing feature not shared by other iron chelates tested so far. Iron-promoted lipid peroxidation is thought to be responsible for the initial events. We examined its ability to initiate lipid peroxidation in vitro in comparison with that of other ferric chelates. Chelation of Fe2+ by nitrilotriacetate (NTA) enhanced the autoxidation of Fe2+. In the presence of Fe2+-NTA, lipid peroxidation occurred as measured by the formation of conjugated diene in detergent-dispersed linoleate micelles, and by the formation of thiobarbituric acid-reactive substances in the liposomes of rat liver microsomal lipids. Addition of ascorbic acid to Fe3+-NTA solution promoted dose-dependent consumption of dissolved oxygen, which indicates temporary reduction of iron. On reduction, Fe3+-NTA initiated lipid peroxidation both in the linoleate micelles and in the liposomes. Fe3+-NTA also initiated NADPH-dependent lipid peroxidation in rat liver microsomes. Although other chelators used (deferoxamine, EDTA, diethylenetriaminepentaacetic acid, ADP) enhanced autoxidation, reduction by ascorbic acid, or in vitro lipid peroxidation of linoleate micelles or liposomal lipids, NTA was the sole chelator that enhanced all the reactions.

Adenosine Diphosphate↗
PubMed1989

The epitope specificity and tissue reactivity of four murine monoclonal anti-CD22 antibodies.

The CD22 antigen is expressed on the surface of normal human B cells and some neoplastic B cell lines and tumors. Previous cross-blocking studies using a panel of monoclonal anti-CD22 antibodies have defined four epitope groups, termed A-D. In the present studies, we have further dissected the epitopes recognized by four monoclonal anti-CD22 antibodies using immunoprecipitation and cross-blocking techniques, immunofluorescence analyses with a variety of cell lines, and immunoperoxidase analyses of 36 normal human tissues. Two of the antibodies, HD6 and RFB4, have been described previously, and two, UV22-1 and UV22-2, are described in this report. Our studies indicate that the four monoclonal antibodies show unexpected complexities in their reactivity with CD22+ and CD22- cells and their reactivity with solubilized CD22 molecules. The four antibodies, which recognize epitopes defined previously as CD22-A and CD22-B, further subdivide these epitope clusters into four determinants, A1, A2, B1, and B2. Furthermore, only two of the antibodies, RFB4 and UV22-2, are B cell-specific. In summary, our data indicate that RFB4 and UV22-2 would be the antibodies of choice for constructing immunotoxins to treat B cell tumors.

Animals↗