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Biomedical subjects

J L Li

Publications and source records attributed to J L Li.

At least 19 recordsLinked to original sources
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↗
PubMed1989

[The power and sample size of F tests of variance proportions in multiple regression].

We would consider not only the significance level alpha, but also the power 1-beta, when making a significance test. This paper presents the method of finding the power of the significance test of a multiple regression equation, and the method of finding the necessary sample size, and has listed the power table and the sample size table for ready reference.

Humans↗
PubMed1989

[A preliminary study on detecting Plasmodium falciparum in blood by Plasmodium falciparum DNA probe].

A simple and rapid method for detecting Plasmodium falciparum in human blood was used in this study. The assay is based on DNA-DNA spot hybridization. For this purpose, the total genomic DNA of P. falciparum was isolated and purified from the parasite cultured in vitro. Then the total genomic DNA was used as a probe and labelled with [alpha-32P]-dATP by nick-translation. Twenty-five test samples, ten-microliter lysed infected blood each, were spotted onto dry nitrocellulose paper and hybridized with labelled genomic DNA. After hybridization, the paper was exposed to X-ray film for autoradiography, resulting in an image in places where hybridization occurred. The result shows that the assay appears to be sensitive enough to detect parasitaemia up to 0.0009%. No visible hybridization was detected in normal human blood or human leukocytes. Many samples can be processed simultaneously. This may be applicable to mass survey for detecting P. falciparum in epidemiological study (Fig. 2).

Animals↗
PubMed1989

Cirrhosis of the liver induced by cupric nitrilotriacetate in Wistar rats. An experimental model of copper toxicosis.

Rats intraperitoneally injected with a daily dose of cupric nitrilotriacetate (Cu-NTA), which contained 4 to 7 mg of copper/kg body weight, showed submassive liver necrosis, hemolytic anemia, and acute renal tubular necrosis at the beginning of the experiment and intermittently after 4 weeks of injections. All rats that survived over 8 weeks exhibited liver fibrosis with portal-portal, portal-central, and central-central bridging. In all rats that survived over 16 weeks, micronodular cirrhosis of the liver or extensive liver fibrosis was observed. The copper content of the cirrhotic/fibrotic liver was above 250 micrograms/g dry weight. Electron-microscopic x-ray analysis at day 93 revealed that copper stored in secondary lysosomes was always accompanied by a proportional amount of sulfur (correlation coefficient, 0.98; P less than 0.005). An experimental model of copper toxicosis in terms of copper-induced cirrhosis of the liver was established with exogenous copper chelated by nitrilotriacetate.

Acetates↗
PubMed1989

[Study on toxicological mechanism of moniliformin].

A mycotoxin was extracted and purified from a strain of Fusarium moniliforme var. subglutinans isolated from mouldy corn seeds harvested in a serious Keshan disease region in Shaanxi Province. The purification procedure involves water extraction, ion exchange chromatography, desalination and crystallization. Its UV spectrum, IR spectrum and NMR are identical with that of the moniliformin. The toxin is highly toxic to young Beijing ducklings. The electrocardiogram (ECG) of the duckling was changed immediately after feeding with moniliformin. The cardiac muscle cells of Beijing ducklings were injured by the toxin. Toxicity may be alleviated to certain extent by applying adequate dosage of Selenium (3.18 X 10(-10) mol/L of H2SeO4) prior to moniliformin treatment. The permeability of the cardic muscle cells of the rats and young ducklings was damaged posterior to the injection of the toxin as tested by extracellular marcromolecular tracer (HRP) method. The relationship between moniliformin and Keshan disease was discussed. We consider that the moniliformin may be the causal agent of the disease.

Animals↗
PubMed1988

Evaluation of four CD22 antibodies as ricin A chain-containing immunotoxins for the in vivo therapy of human B-cell leukemias and lymphomas.

Ricin A chain-containing immunotoxins (IT-As) specific for the human B-cell antigen, CD22, were prepared from 4 monoclonal antibodies (MAbs) or their Fab' fragments: RFB4, HD6, UV22-I and UV22-2. The ITs were tested for their ability to kill cells from the Burkitt lymphoma line, Daudi, the pre-B-cell leukemia line, NALM-6, and the myeloma cell line, ARH-77. Daudi expresses high levels of CD22, whereas NALM-6 and ARH-77 express low levels of CD22. The IgG-RFB4-A was highly toxic to all 3 cell lines; it killed 50% of the Daudi cells at a concentration of 1.2 x 10(-12) M and 50% of NALM-6 and ARH-77 cells at concentrations of 1.5 to 2.1 x 10(-11) M. IgG-RFB4-A was 10-30 times more toxic to Daudi cells than were the IgG-As constructed from the other 3 CD22 MAbs and 10 times more toxic than ricin itself. IT-As constructed from the Fab' fragments of the 4 CD22 antibodies were 2 to 5 times less toxic to Daudi cells than their IgG-A counterparts. Fab'-RFB4-A was twice as toxic to Daudi cells as ricin, whereas the other Fab'-As were about 7 times less toxic than ricin. Scatchard analyses of the binding of the radio-iodinated antibodies to Daudi cells showed that the intact RFB4 antibody bound 3-10 times more strongly than the other antibodies, whereas the Fab'-RFB4 bound 1.2 to 3.5 times more strongly than the Fab' fragments prepared from the other antibodies. Thus, the potent cytotoxic activity of the RFB4-As appears to derive, in part, from their superior binding affinity. Prior studies have shown that UV22-I and HD6 cross-react with certain normal human tissues lacking cells of B-cell lineage, whereas UV22-2 and RFB4 are B-cell-specific. This fact, together with its superior potency as an IT-A, suggests that RFB4 is the antibody of choice for preparing Fab'-As or IgG-As for in vivo therapy of human B-cell leukemias and lymphomas.

Animals↗
PubMed1988

Sex differences in ferric nitrilotriacetate-induced lipid peroxidation and nephrotoxicity in mice.

Since male A/J mice are much more susceptible to both acute and subacute nephrotoxicity and the carcinogenic effect of ferric nitrilotriacetate than female mice, sex differences in the lipid peroxidation level after ferric nitrilotriacetate use were examined. The effects of orchiectomy and testosterone were also investigated. Male and female A/J mice were given a single intraperitoneal injection of ferric nitrilotriacetate (3 mg of iron/kg of body weight) and then thiobarbituric acid reactivity was determined in the liver and the kidney. Only male mice showed high thiobarbituric acid reactivity after 30 min, with the kidney showing higher activity than the liver. Castrated male mice showed a reduction in thiobarbituric acid reactivity, whereas testosterone-pretreated castrated male or testosterone-pretreated female mice showed increased thiobarbituric acid reactivity. In addition, daily intraperitoneal injections of ferric nitrilotriacetate resulted in the death of all normal male mice within 6 days, whereas all female and castrated male mice survived 3 months of treatment. Thus, male and female mice showed differences in ferric nitrilotriacetate-induced toxicity as reflected in the degree of lipid peroxidation and mortality.

Animals↗