[Antioxidants inhibit the oxidative modification of high density lipoproteins].

OBJECTIVE: To study the role and mechanism of antioxidants on inhibiting oxidative modification of high density lipoproteins (HDL). METHODS: Freshly prepared human plasma HDL was treated by incubation with copper ion, hyperchlorite or arterial wall cells. Compared to control, the test groups were treated with addition of different concentration of butylhydroxytoluene (BHT), vitamin C and vitamin E. Then, the relative electrophoretic mobility (REM), thiobarbituric acid-reactive substances (TBARS), ratio of lysolecithin to lecithin (LPC/PC), and lipoprotein moieties were investigated. RESULTS: BHT, vitamin C and vitamin E can significantly inhibit the increasing REM, TBARS, LPC/PC ratio and lipoprotein variation that induced by copper ion and hyperchlorite and arterial wall cells. But these antioxidants act on different manner. CONCLUSION: BHT, vitamin C and vitamin E can inhibit the oxidative modification of HDL and hence could be potential nutrients to prevent atherosclerosis.

[Study on the protective effect of HDL subclasses against lipopolysaccharide].

AIM: To elucidate the anti-LPS effect of high-density lipoprotein (HDL) subclasses. METHODS: The pNF-kappaB-luc plasmid was transfected into HepG2 cells and the luciferase expression was obtained by the optimization of cell density, incubation time of transfected cells and stimulating concentration of LPS. The luciferase expression was examined in the cells treated with various stimulus including LPS, mixtures of HDL subclasses and LPS. The expression of TNF-alpha mRNA was detected RT-PCR. RESULTS: After LPS stimulation, HDL subclasses did not show obvious influence on the effect of LPS to stimulate the luciferase production. However, pre-incubation of cells or pre-incubation of LPS with large-sized HDL(2) strongly inhibited the effect of LPS to stimulate the luciferase production. When LPS was incubated with increased concentration of HDL(2), the LPS effect was decreased to a greater extent. Pre-incubation of LPS with HDL(2) before addition to the cells resulted in a significant decrease in the mRNA level of TNF-alpha. CONCLUSION: The largest HDL(2) has strong LPS-binding capacity and can inhibit the LPS induced TNF-alpha release in HepG2 cells; HDL(3) shows weak anti-LPS effect; small-sized prebeta(1)-HDL does not show anti-LPS effect.

[Association between serum lipoprotein-cholesterol levels and HDL subpopulations].

OBJECTIVE: To investigate the influence of serum HDL-C or LDL-C levels on the components of serum HDL subpopulations. METHODS: Apolipoprotein (apo) A-I contents of serum HDL subpopulations in 292 subjects were determined by two-dimensional gel electrophoresis in conjunction with immunodection. RESULTS: With the decrease of serum HDL-C levels, the apoA-I contents of pre beta1-HDL and HDL3b increased and were significantly higher (P<0.01; P<0.05) in the low HDL-C group than in the high HDL-C group. But on the contrary, with the decrease of serum HDL-C levels, the apoA-I contents of HDL2b and HDL2a decreased and were significantly lower (P<0.01) in the middle and low HDL-C groups than in the high HDL-C group. With the increase of serum LDL-C levels, the apoA-I contents of pre beta1-HDL, HDL3C and HDL3b increased; the apoA-I contents of pre beta1-HDL and HDL3b were significantly higher in the high LDL-C group (P<0.05) and very high LDL-C group (P<0.01), and those of HDL3C were also significantly higher in the very high LDL-C group (P<0.01). But on the contrary, with the increase of LDL-C levels, the apoA-I contents of HDL2b decreased and were significantly lower in the high LDL-C group (P<0.05) and very high LDL-C group (P<0.01) when compared with the apoA-I contents of the desirable LDL-C group. CONCLUSION: With the decrease of serum HDL-C levels or increase of serum LDL-C levels, the small-sized HDL increased and the large-sized HDL decreased; furthermore, the HDL-C levels were more closely related to the components of the large-sized HDL (HDL2a, HDL2b).

[Study on apoE gene polymorphism and subclasses of serum high density lipoprotein in type IV hyperlipidemia].

OBJECTIVE: The aim of the study was to investigate apolipoprotein(apo) E polymorphism and its relationship with serum lipids and apolipoprotein, serum high density lipoprotein(HDL) subclasses in patients with type IV hyperlipidemia. METHODS: apoE genotype was assayed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The subclasses of serum HDL in 103 patients with type IV hyperlipidemia and 146 normolipidemic subjects were determined by two-dimensional gel electrophoresis in conjunction with immunodetection method. RESULTS: The apoE3/3 genotype frequency and allele epsilon 3 frequency were both the highest in the frequency distribution profiles of the type IV hyperlipidemia group and the control group. In type IV hyperlipidemia group, the genotype of apoE2 had higher serum HDL-C,apoE, HDL(2a) apoE/apoCIII ratio but lower TG/HDL-C,apoCIII, HDL(3c) levels when compared with the genotype of apoE(3) (P<0.05). In control group, the genotype of apoE(2) had higher serum TG, apoE levels and apoE/aopCIII ratio but lower HDL (3a) level when compared with the genotype of apoE(3) (P<0.05). CONCLUSION: An association of allele epsilon 2 of apoE gene with the maturation of HDL in type IV hyperlipidemia was noted in the study.

[Relationship of APOE gene polymorphism with subclasses of serum high density lipoprotein in hyperlipidemia].

OBJECTIVE: To investigate apolipoprotein E(apoE) polymorphism and its relationship with serum lipids and apolipoprotein, serum high density lipoprotein (HDL) subclasses in patients with hyperlipidemia(HL). METHODS: APOE genotype was assayed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The subclasses of serum HDL in 112 patients with hyperlipidemia and 73 healthy subjects were determined by two-dimensional gel electrophoresis in conjunction with immunodetection method. RESULTS: APOE3/3 genotypes and allele epsilon3 frequency in HL group and control group were both the highest. In HL group, the genotype of APOE2 had higher serum APOE/CIII ratio and lower HDL3b levels, compared with the genotype of APOE3 (P<0.05). In control group, the genotype of apoE2 had higher serum triglycerides, APOE levels and APOE/CIII ratio, compared with the genotype of APOE3 and APOE4 (P<0.05). CONCLUSION: Polymorphism of APOE gene may relate to the distribution of HDL particles.

[Relationship between the contents of serum HDL subclasses and the extent of coronary stenosis in coronary heart disease patients].

OBJECTIVE: To explore the relationship between the contents of serum HDL subclasses and the extent of coronary stenosis in coronary heart disease (CHD) patients. METHODS: The contents of serum HDL subclasses in CHD patients (n = 51) and healthy controls (n = 56) were determined by two dimensional gel electrophoresis associated with immunodetection method. CHD patients were divided into three groups by average coronary severity score (CSS). Data were analyzed using linear regression and correlation method and multiple stepwise regression method. RESULTS: It was found that as the extent of coronary stenosis increases, the levels of pre beta1-HDL, HDL3b increase, meanwhile the level of HDL2b decreases (P < 0.001). There were significant positive correlations between CSS and pre beta1-HDL (P < 0.01), HDL3a (P < 0.05), HDL3b (P < 0.01), and significant negative correlation was observed between CSS and HDL2b (P < 0.01). apoB100, HDL2b, TG, HDL-C, TC/HDL-C, apoAI are all independent risk factors of CHD. CONCLUSION: The extent of coronary stenosis is highly correlated with the subclasses of HDL.

[Purification and characterization of sanguicin--a bacteriocin produced by Streptococcus sanguis].

OBJECTIVE: Streptococcus sanguis plays an important Role in maintaining the periodontal microecological balance. Previous studies have demonstrated that sanguicin--a kind of bacteriocin produced by S. sanguis has a prominent function of inhibiting the growth of putative periodontopathic bacteria (PPB). The aim of this study was to purify sanguicin and investigate its characters. METHODS: The raw extract of sanguicin was obtained from cells of S. sanguis by ultrasonication, salting out and dialysis. Then the diethyl-aminoethyl-sepharose gradual washing was done in conjunction with glucosan gel filtration for in the purfication of sanguicin. The characters of purified sanguicin were determined and its inhibitiory effect on PPB was measured by agar diffusion test. RESULTS: The purifed sanguicin was obtained; it was heat labile and proteinaceous; and by SDS-PAGE, it showed a main band with the relative molecular mass of 65 x 10(3). The purifed sanguicin had a strong inhibitory effect on P. gingivalis, P. intermedia and F. nucleatum in vitro. CONCLUSION: Our methods are useful for the purification of sanguicin. Sanguicin has inhibitory effect on PPB obviously and will have a good prospect in periodontal ecological therapy.

[The interrelationships between serum triglyceride, total cholesterol and HDL subpopulations].

OBJECTIVE: To assess the influence of serum triglyceride (TG) level and total cholesterol (TC) level on the change of the contents of serum HDL subpopulations. METHODS: The apolipoprotein (apo) A-I contents of serum HDL subpopulations in 289 subjects were determined by two-dimensional gel electrophoresis associated with immunodetection method. RESULTS: Analysis of the data on the serum TG levels in subjects revealed that the apoA-I contents of pre beta 1-HDL, pre beta 2-HDL, HDL3b and HDL3a increased with the increase of TG level, whereas the apoA-I contents of HDL2a and HDL2b decreased. By comparison with the data of normal TG group, the apoA-I contents of pre beta 1-HDL and HDL3b in the high TG and very high TG groups were significantly higher, whereas those of HDL2b were significantly lower in the high TG and very high TG groups. Analysis of the data on the serum TC levels in subjects revealed that the apoA-I contents of pre beta 1-HDL, pre beta 2-HDL, HDL2c and HDL3b increased with the increase of TC level, while the apoA-I contents of HDL2b decreased. As compared with the data of TC desirable group, the apoA-I contents of pre beta 1-HDL, HDL3c and HDL3b were significantly higher in the high TC group. CONCLUSION: With the increase of serum TG or TC, there is a general shift toward small-sized HDL in subjects. Besides, the change of serum TG level is a more important factor influencing the components of HDL subpopulations, compared with the change of serum TC level.

[Impact of p16INK4A and p15INK4B on human hepatocellular carcinoma cell proliferation and apoptosis].

OBJECTIVE: Both tumor suppressor p16INK4A and p15INK4B are members of INK family of CDK inhibitor. Although the role of p16 has been well documented, the role of p15 and its signaling pathway remain less well studied. This study was aimed to assess the effect of p16 and p15 on hepatocarcinoma cell lines with different status of Rb gene. METHODS: After identification of the genetic status of p16, p15 as well as Rb of human hepatocellular carcinoma (HCC) cell lines BEL7402, SMMC7721 with the use of multiple PCR, the eukaryotic expression p16 and p15 recombinants pXJ-p16 and pXJ-p15 were constructed, respectively. The existence of exogenous p16, p15 genes, and the expression of p16 and p15 were assayed by means of PCR and RNA dot blotting. Finally, the proliferation and apoptosis were studied by using MTT, colony formation assay and flow cytometry. RESULTS: Neither deletion of p16 nor p15 was detected in the two cell lines. However, Rb exons 14-16 instead of exons 22-23 deletion existed in SMMC7721. The increased mRNA expression level of p16 was found in BEL7402-p16 and SMMC7721-p16, while increased mRNA expression level of p15 was found in BEL7402-p15. The endogenous p16 and p15 genes were transcripted at low level. The cell growth and colony formation were decreased in BEL7402-p15, compared with either mock cell BEL7402 or vector control cell BEL7402-pXJ. Also shown in this study were an altered G1 phase population from 37.7% to 43.6%, an S phase population from 22% to 13% (P<0.05), and a Sub G1 peak (apoptosis peak) in BEL7402-p15. Conversely, BEL7402-p16 with endogenous p16 gene showed neither difference in cell cycle population nor difference in colony formation rate, compared with control cell groups. Additionally, SMMC7721-p16 cell growth was not inhibited by exogenous p16 gene. CONCLUSION: p15 significantly arrested cell proliferation and induced apoptosis in BEL7402 in vitro, and the function was not influenced by endogenous p15 gene. The inhibition of cell growth by p16 on HCC cells could be dependent on intact RB pathway.

[Effect of purified pre-beta 1 HDL on efflux of 3H-cholesterol loaded in human smooth muscle cells].

OBJECTIVE: To compare the effects of different HDL subclasses on the efflux of 3H-cholesterol loaded human smooth muscle cells (SMCS). METHODS: 3H-cholesterol loaded human SMCS were incubated with purified pre-beta 1 HDL, alpha-HDL and apoE-deficient HDL3 respectively. The cholesterol effluxing capacity and incubating time of different HDL subclasses were detected, and were analysed by double-reciprocal mapping. RESULTS: It was found that the value of Emax of pre-beta 1 HDL is higher than that of alpha-HDL and apoE-deficient HDL3 (P < 0.01), and the value of Ke of pre-beta 1 HDL is lower than that of alpha-HDL and apoE-deficient HDL3 (P < 0.01). CONCLUSION: The results showed the effluxing capacity and efficiency of pre-beta 1 HDL were greater than those of alpha-HDL and apoE-deficient HDL3, thus suggesting that pre-beta 1 HDL is a more efficient acceptor of cell-derived 3H-cholesterol.

Sequencing of Lipoprotein Lipase Gene in 11 Cases of Chinese Patients with Severe Endogenous Hypertriglyceridemia.

Sequencing analysis of lipoprotein lipase (LPL) gene exons l-9 was made in 11 cases of Chinese patients with severe endogenous hypertriglyceridemia (serum TG > 7.68 mmol/L) by the dideoxy chain termination method using Sequenase PCR Product Sequencing Kit. Four of the patients were found to possess 3 variants at the LPL gene locus. One novel mutation was observed at exon 8 Thr(361)-Thr (C(1338)-A). This was a conservative mutation with an allele frequency of 1l.4% in the 74 of the Chinese controls. Two others Ala(261)-Thr (G(1037)-A) in exon 6 and Ser(447)-Ter (C(1595)-G) in exon 9, which were also found in Caucasians and have been reported to have disease associations with dyslipidaemia, showed at frequencies of 0% and 10.7% in the Chinese controls respectively. However, it is the first time that these three genetic variants have been reported in Chinese subjects. The results show that the gene variation of LPL may not be associated with endogenous hypertriglyceridemia in Chinese population.