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Biomedical subjects

B Liang

Publications and source records attributed to B Liang.

At least 73 records · Page 4Linked to original sources

Prevention of retrovirus-induced aberrant cytokine secretion, excessive lipid peroxidation, and tissue vitamin E deficiency by T cell receptor peptide treatments in C57BL/6 mice.

To test whether T cell receptor (TCR) peptide treatment can prevent immune dysfunction, excessive lipid peroxidation, and malnutrition caused by retrovirus infection, female C57BL/6 mice were infected with LP-BM5 retrovirus. Infection with retrovirus inhibited lymphocyte proliferation, cytokine release T helper 1 cells, stimulated cytokine secretion by T helper 2 cells, induced abnormal hepatic and cardiac lipid profiles, and produced excessive tissue lipid peroxidation with hepatic and cardiac vitamin E deficiency. Two weeks after infection, TCR peptides Vbeta5.2, Vbeta8.1, Vbeta8.1 + Vbeta5.2, Vbeta8.1(N), and Vbeta8.1 were injected to the mice at dose of 200 microg/mouse. Vbeta8.1 and Vbeta5.2 treatments largely maintained lymphocyte proliferation and IL-2 and IFN-gamma release, and prevented excessive IL-6, IL-10, and TNF-alpha secretion. Concomitantly, these treatments normalized hepatic and cardiac lipid profiles, reduced tissue lipid peroxidation, and thereby significantly maintained vitamin E in the liver and heart. Vbeta8.1 segments treatment did not prevent the immune dysfunction, abnormal lipid profile and lipid peroxidation, and vitamin E deficiency caused by the retrovirus infection. In conclusion, injection of intact TCR peptides during murine retrovirus infection largely prevented immune dysfunction by blocking the excessive stimulation of a T cell subset caused by retroviral superantigens. It also ameliorated malnutrition status by normalizing lipid profile, lipid peroxidation, and vitamin E deficiency. T cell immune dysfunction and its prevention by TCR peptide treatment is important in the therapy of vitamin E deficiency induced by retrovirus infection.

Amino Acid Sequence↗

[Analysis of frequency domain correlative cardiogram (FCG) in 151 healthy pilots].

Frequency domain correlative cardiogram (FCG) is a relatively new noninvasive method for diagnosis of coronary heart disease. However there has been little information about the application of FCG in pilots. To explore whether the FCG diagostic standards of normal people, can be applied to healthy pilots, 151 male pilots aged 22-47 (mean = 30 +/- 6 years) were examined with the HBD-II A instrument manufactured by Hong Kong WEX company. The results showed that the characteristics of FCG graph of the pilots were similar to that of the common healthy men. It indicates that the diagnostic standard of FCG for normal people can be used to pilots, so it might be useful in selection and real-time medical monitoring during ground training.

Adult↗

[Sphygmographic parameters in fighter and transport pilots].

To evaluate and discover hidden cardiovascular trouble in pilots, the cardiovascular function of 129 active male pilots was examined with a new sphygmographic method. 13 pilots (10.3%) were found to have abnormal cardiovascular function. The average arterial blood pressure and medium artery modulus of the fighter pilots aged from 30 to 34 years are inferior to those aged from 25 to 29 obviously, however, that is not the case in transport pilots. This indicates that frequent examination of cardiovascular function with convenient special method is necessary for the improvement of the quality of medical monitor on pilots.

Adult↗

[Dynamic analysis of 24 h blood pressure in pilots and hypertensive patients].

Blood pressure of 63 healthy male pilots and 20 primary hypertensive patients was measured with the "Smart LINK Ambulatory Monitoring System". The BP readings were taken every 30 min in daytime and 60 min at night for 24 h. The results showed that two peaks appeared at 7:00-9:00 A.M. and 16:00-19:00 P.M. and two valleys at 12:00-14:00 P.M. and 24:00-5:00 A.M. in healthy pilots, but the hypertensive subjects showed higher systolic or/and diastolic blood pressure continuously.

Aerospace Medicine↗

[Quantitative determination of the nickel, tin, copper, scandium, zirconium and hafnium in silicate sample by laser microspectrochemical analysis].

Quantitative determination of the nickel, tin, copper, scandium, zirconium and hafnium in silicate sample were carried out by laser microspectrochemical analysis, results show that the method has good precision and accuracy. The stability of the laser output and the selection of auxiliary spark excitation condition in experimental process were discussed.

English Abstract↗

Oxidative modification of low density lipoprotein in normal and hyperlipidemic patients: effect of lysophosphatidylcholine composition on vascular relaxation.

The elevated level of plasma low density lipoprotein (LDL) in hyperlipidemic patients is an important risk factor for the production of atherosclerosis. Plasma LDL must be modified before it can produce an impairment of endothelium-dependent relaxation in aortic rings or enhancement of uptake by macrophages. The dramatic increase in lysophosphatidylcholine (lysoPC) content in oxidatively modified LDL has been touted as an important biochemical factor for the impairment of endothelium-dependent relaxation. The present study was designed to examine the lysoPC composition of oxidized LDL samples from normal and hyperlipidemic subjects, and their effects on the impairment of endothelium-dependent relaxation. Oxidatively modified LDL from hyperlipidemic patients contained a slightly higher level (17%) of lysoPC, but produced a disproportionately greater impairment of endothelium-dependent relaxation than that from normal subjects. As lysoPC is composed of many molecular species, its composition in oxidized LDL samples was analyzed. In hyperlipidemic patients, lysoPC samples were found to contain a higher proportion of long-chain acyl groups. Subsequent studies revealed that only long-chain lysoPC (C > 16:0) were effective in impairing endothelium-dependent relaxation. Experimental loading of oxidized LDL from normal subjects with long chain lysoPC to mimic levels observed in oxidized LDL from hyperlipidemic patients resulted in further impairment of endothelium-dependent relaxation. We conclude that the greater proportion of long-chain lysoPC found in the oxidized LDL of hyperlipidemic subjects is responsible for the increased impairment of endothelium-dependent vascular relaxation. We propose that the high level of LDL found in the plasma of hyperlipidemic patients, coupled with its enhanced ability to generate long chain species of lysoPC during oxidative modification, are important factors for the development of atherosclerosis in these patients.

Adult↗

Beta2-microglobulin gene mutations in human melanoma cells: molecular characterization and implications for immune surveillance.

In recent years, the mechanisms underlying defects in the expression/function of human leukocyte antigen (HLA) class I antigens have been analyzed in an increasing number of melanoma cells, since these abnormalities are likely to have a negative impact on T-cell-based immunotherapy of melanoma. This article reviews the information about the molecular defects found in melanoma cell lines that do not express HLA class I antigens, following a concise description of the structure and assembly of HLA class I antigens. Distinct defects ranging from large deletions to point mutations in beta2-microglobulin genes have been found in melanoma cells. A mutation in an 8 base-pair CT repeat region of exon 1 has been found frequently in melanoma cell lines suggesting that this region of the beta2-microglobulin gene is a hot-spot for mutations. The effects of beta2-microglobulin mutations are mostly at the level of translation, emphasizing the importance of analyzing beta2-microglobulin expression at the protein level in melanoma lesions without detectable HLA class I antigen expression. Interestingly, many melanoma cell lines have additional defects that directly impact HLA class I antigen expression. Therefore, multiple mechanisms that affect the expression/function of HLA class I antigens appear to be available to melanoma cells to escape from immune recognition.

Exons↗

[Treatment of nerve root avulsion of brachial plexus by nerve transfer].

The results of nerve transposition for root avulsion of brachial plexas in 21 cases were reported. The methods of the nerve transposition were divided into four groups as followings: By transfer of phrenic nerve, accesory nerve, the motor branches of cervical plexus and intercostal nerves in cease; By transfer of phrenic nerve, accessory nerve and the motor branches of cervical plexus in 6 cases; By transfer of phrenic nerve and accessory nerve in 9 cases, and by transfer of phrenic nerve or the motor branches of cervical plexus or intercostal nerve in 5 cases. During operation, in 1 cases variation of the brachial plexus was found. Injury to the subclavian artery occurred in 4 cases and they were repaired, which is good for the blood circulation of the upper arm and nerve regeneration. Nineteen cases were followed up with good results. The overall excellent and good rate was 73.7%. It was considered that transposition of nerve should be a routine operation for the treatment of root avulsion of brachial plexus and the accompanied arterial injury should be repaired at the same time during operation, and the latter would be advantageous to enhance functional recovery of nerve.

Accessory Nerve↗

Effects of vaccination against different T cell receptors on maintenance of immune function during murine retrovirus infection.

Murine retrovirus infection causes an aberrant stimulation of several subsets of T helper 2 cells identified by their T cell receptors (TCR). C57BL/6 mice were treated with synthetic peptides based upon different human TCR V beta CDR1 sequences following experimental infection with the murine retrovirus. Previous studies established that retrovirally infected mice produced autoantibodies to certain of these peptides, and their administration after infection diminished many of the cytokine abnormalities induced by the virus. This study determined whether the complete 16-mer synthetic peptides modeling the V beta CDR1/FR3 were required, and whether admixture of autoantigenic peptides synergized immune preservation. Treatment with complete TCR pep beta 3 and pep V beta 5.2 peptide alone and combined largely prevented the retrovirus-induced reduction in B and T cell proliferation and Th1 cytokine secretion while suppressing excessive production of Th2 cytokines, which are stimulated by retrovirus infection. Treatment with overlapping short peptides corresponding to the N-terminal 11-mer and C-terminal 12-mer did not significantly prevent the immune dysfunction in retrovirus-infected mice. These data suggest that immune dysfunction and abnormal cytokine production, induced by murine retrovirus infection, were largely prevented by TCR V beta CDR1 peptides, and the complete CDR1 in association with the five residues from FR2 was required.

Amino Acid Sequence↗

Immunomodulation by pycnogenol in retrovirus-infected or ethanol-fed mice.

Pycnogenol is a commercial mixture of bioflavonoids that exhibits antioxidative activity. The effects of dietary pycnogenol on immune dysfunction in normal mice as well as those fed ethanol or infected with the LP-BM5 murine retrovirus were determined. The ethanol consumption and retrovirus infection caused abnormalities in the function and/or structure of a broad array of cells involved in humoral and cellular immunity. Pycnogenol enhanced in vitro IL-2 production by mitogen-stimulated splenocytes if its production was suppressed in ethanol-fed or retrovirus-infected mice. Mitogenesis of splenocytes did not show a significant change in mice treated with pycnogenol. It reduced the elevated levels of interleukin-6 produced in vitro by cells from retrovirus infected mice and IL-10 secreted by spleen cells from mice consuming ethanol. Natural killer cell cytotoxicity was increased with pycnogenol treatment.

Adjuvants, Immunologic↗

Vitamins and immunomodulation in AIDS.

Acquired immune deficiency syndrome (AIDS) is a clinical disorder caused by a retrovirus infection and represents the end point in a progressive sequence of immunosuppressive changes. Vitamins can enhance disease resistance in animals and humans. As such they are important co-factors in optimal functioning of the immune systems. In this article, the immunological and nutritional modifications caused by AIDS are summarized. The effects of murine and human retrovirus infection on vitamin status are analyzed as co-factors in the development of severe immune dysfunction, AIDS. The properties of immunoenhancing antioxidative vitamins, vitamin A, B6, B12, C, E, and beta-carotene, which are frequently low in AIDS patients, are evaluated relative to the development of immunodeficiency during retrovirus infection. Vitamin A, E, and B12 deficiency accelerated the development of AIDS with low T cells, whereas their normalization retarded the development of immune dysfunction. The interactions between these vitamins and the immune system in human AIDS patients and animal models of AIDS are reviewed. Our purpose is to provide data on how retrovirus infection can cause nutritional deficiencies that accentuate immune damage and to evaluate the potential therapeutic role of vitamins in the treatment of immune dysfunctions in AIDS patients.

Acquired Immunodeficiency Syndrome↗

T-cell-receptor dose and the time of treatment during murine retrovirus infection for maintenance of immune function.

C57BL/6 mice were injected with different doses of human T-cell receptor (TCR) V beta 8.1 CDR1 peptide at different times after murine retrovirus (LP-BM5) infection. Injection with TCR V beta 8.1 CDR1 peptide largely prevented the retrovirus-induced reduction in B- and T-cell proliferation, and T-helper 1 (Th1) cytokines [interleukin-2 (IL-2) and interferon-gamma (IFN-gamma)] secretion. It also suppressed T-helper 2 (Th2) cytokines (IL-6 and IL-10) production, which was stimulated by retrovirus infection. These effects were accomplished using at least 100 micrograms of peptide per mouse and the most effective dose of peptide had to be given within 4 weeks after retrovirus infection. Immunization with doses above 100 micrograms/mouse as long as 4 weeks postinfection maintained natural killer (NK) cell activity during retrovirus infection. Reducing the dose of peptide or delaying it until the disease progressed towards early murine acquired immune deficiency syndrome (AIDS) allowed development of immune dysfunction. These studies provide data suggesting that immune dysfunction, induced by murine retrovirus infection, was largely prevented by TCR V beta CDR1 peptide injection.

Adjuvants, Immunologic↗

Murine AIDS, a key to understanding retrovirus-induced immunodeficiency.

A murine AIDS model, induced by LP-BM5 murine leukemia virus (MuLV), has helped to investigate pathogenesis of acquired immunodeficiency syndrome (AIDS), cofactor involvement, and new treatment tests. LP-BM5 MuLV-infected mice characteristically develop hypergammaglobulinemia, splenomegaly, lymphadenopathy, T-cell functional deficiency, B-cell dysfunction, and, in the later stages, neurological signs including paralysis as well as susceptibility to opportunistic infections. The similarities between murine AIDS and human AIDS are striking, with similar changes in immune functions, T-cell differentiation, cytokine production, disease resistance, and oxidative stress. The well-characterized murine immunological system, availability of inbred strains, economy of using mice versus primate model, and similarities in immunodeficiency caused by human immunodeficiency virus (HIV) encouraged rapid development of the LP-BM5 murine AIDS model in the past decade.

Animals↗

Vitamin E deficiency and immune dysfunction in retrovirus-infected C57BL/6 mice are prevented by T-cell receptor peptide treatment.

Female C57BL/6 mice were infected with LP-BM5 retrovirus, causing murine acquired immunodeficiency syndrome (AIDS), which is functionally similar to human AIDS. Retrovirus infection inhibited release of T-helper 1 cytokines, stimulated secretion of T-helper 2 cytokines and induced hepatic and cardiac vitamin E deficiency with increased lipid peroxides. We hypothesized that the immune dysfunction caused increased oxidation and loss of vitamin E. Because T-cell receptor (TCR) peptide treatment blocked the excessive stimulation of a T-cell subset by retroviral superantigens, we tested whether maintenance of normal immune function during infection prevented excessive oxidative damage. The TCR peptide treatments with doses > 100 microgram/mouse and administered 2-4 wk postinfection significantly inhibited the retrovirus-induced immune dysfunction, concomitantly reduced tissue oxidative damage and thereby largely maintained vitamin E concentration in the liver and heart. Reducing the dose of peptide or delaying administration until early murine AIDS had developed resulted in severe immune dysfunction that caused elevated tissue lipid peroxidation and loss of vitamin E. The TCR peptide treatment partially maintained production of interleukin-2 (IL-2) and prevented retrovirus-induced elevated production of IL-6 by splenocytes in vitro. In conclusion, TCR peptide treatment during murine retrovirus infection ameliorated immune dysfunction and thus prevented increases in tissue lipid peroxidation and vitamin E loss. T-cell immune dysfunction and its prevention by TCR peptide treatment is important in the therapy of vitamin E deficiency induced by retrovirus infection.

Adjuvants, Immunologic↗

Characterization of a stimulatory adenosine A2a receptor in adult rat ventricular myocyte.

The expression and function of stimulatory adenosine A2 receptor on the cardiac myocyte is not well defined. The objective of the present study is to characterize the A2a receptor in adult rat cardiac ventricular myocytes. After selection of an optimal lot of collagenase for myocyte isolation and for consistent measurement of adenosine-mediated responses, the A1-receptor pathway was inactivated by pertussis toxin and by the A1-selective antagonist 1,3-dipropyl-8-cyclopentylxanthine. Effects of the adenosine agonist and antagonist or cardiac myocyte contractile amplitude and on adenosine 3',5'-cyclic monophosphate (cAMP) levels were determined. The A2a-receptor-selective agonist 2-[p-(2-carboxyethyl)phenylethylamino]-5'-N-ethylcarboxamidoade nos ine (CGS-21680) caused a pronounced stimulation of myocyte contractile amplitude and an increase in the cAMP level, as did the nonselective agonists 5'-(N-ethylcarboxamido) adenosine (NECA) and adenosine. The A2a-receptor-selective antagonist 8-(3-chlorostyryl)caffeine blocked the NECA- and adenosine-induced positive inotropic response. Probing of myocyte RNA with a rat A2a-receptor cDNA demonstrated a 2.6-kb mRNA, corresponding to that encoding the A2a receptor. Together, data from contractile, cAMP, and RNA studies indicate that A2a receptors are expressed and are functionally coupled to stimulation of cAMP accumulation and cardiac contractility in adult rat ventricular myocytes.

Adenosine↗

Technical and editorial administration of a World-Wide-Web site during a period of rapid growth: the OncoLink experience.

OncoLink is a cancer information resource on the World-Wide-Web (WWW) that provides a wide variety of information for cancer patients and healthcare providers. Since its introduction in March, 1994 it has enjoyed success as demonstrated by an over 31-fold increase in usage as of February, 1996. Current utilization exceeds 1.1 million accesses per month. The content of OncoLink has also expanded greatly, with new items being added daily. In addition, OncoLink has been the recipient of numerous awards from a variety of agencies and organizations. During this period of rapid growth, the complexity of managing and maintaining OncoLink has likewise increased. This work may be divided into three categories: content editing, technical (or production) editing, and web site maintenance. Consequently, we have developed numerous administrative procedures to handle this workload. After implementing these new administrative strategies, we were able to greatly reduce the need for face-to-face meetings of our Editorial and Production Staffs. This paper describes our experience with developing efficient strategies for managing the daily operation of OncoLink during a period of rapid growth.

Computer Communication Networks↗

Phase I study of lovastatin, an inhibitor of the mevalonate pathway, in patients with cancer.

Lovastatin, an inhibitor of the enzyme 3-hydroxy-3-methylglutaryl-coenzyme A reductase (the major regulatory enzyme of the mevalonate pathway of cholesterol synthesis), displays antitumor activity in experimental models. We therefore conducted a Phase I trial to characterize the tolerability of lovastatin administered at progressively higher doses to cancer patients. From January 1992 to July 1994, 88 patients with solid tumors (median age, 57 +/- 14 years) were treated p.o. with 7-day courses of lovastatin given monthly at doses ranging from 2 to 45 mg/kg/day. The inhibitory effects of lovastatin were monitored through serum concentrations of cholesterol and ubiquinone, two end products of the mevalonate pathway. Concentrations of lovastatin and its active metabolites were also determined, by bioassay, in the serum of selected patients. Cyclical treatment with lovastatin markedly inhibited the mevalonate pathway, evidenced by reductions in both cholesterol and ubiquinone concentrations, by up to 43 and 49% of pretreatment values, respectively. The effect was transient, however, and its magnitude appeared to be dose independent. Drug concentrations reached up to 3.9 micrometer and were in the range associated with antiproliferative activity in vitro. Myopathy was the dose-limiting toxicity. Other toxicities included nausea, diarrhea, and fatigue. Treatment with ubiquinone was associated with reversal of lovastatin-induced myopathy, and its prophylactic administration prevented the development of this toxicity in a cohort of 56 patients. One minor response was documented in a patient with recurrent high-grade glioma. Lovastatin given p.o. at a dose of 25 mg/kg daily for 7 consecutive days is well tolerated. The occurrence of myopathy, the dose-limiting toxicity, can be prevented by ubiquinone supplementation. To improve on the transient inhibitory activity of this dosing regimen on the mevalonate pathway, alternative schedules based on uninterrupted administration of lovastatin should also be studied.

Adult↗