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Biomedical subjects

B Liu

Publications and source records attributed to B Liu.

At least 577 records · Page 32Linked to original sources
PubMed1995

Processing of pro-PTHRP by the prohormone convertase, furin: effect on biological activity.

We have examined the conversion of parathyroid hormone-related peptide (PTHRP) from its NH2-terminally extended precursor pro-PTHRP. Within pro-PTHRP, an amino acid sequence exists that can serve as a substrate for the prohormone convertase, furin. To evaluate the potential role of furin in processing of this entity, we expressed pro-PTHRP in COS-7 cells, which normally produce this enzyme. Transiently transfected COS-7 cells secreted high levels of PTHRP into conditioned culture medium. Cotransfection of these cells with antisense furin cDNA resulted in marked inhibition of furin mRNA expression and secretion of an NH2-terminal fragment of pro-PTHRP, which comigrated with synthetic pro-PTHRP-(-12-->+36) on gel-permeation high-pressure liquid chromatography. In an adenylate cyclase bioassay, condition medium containing this fragment and synthetic pro-PTHRP-(-12-->+36) both exhibited lower potency than synthetic PTHRP-(1-36) and conditioned medium containing PTHRP produced by COS-7 cells in the absence of antisense furin. These results demonstrate the capacity of furin to convert pro-PTHRP to a more active product and suggest a role for this enzyme in the normal intracellular processing of this hormone.

Amino Acid Sequence↗
PubMed1995

Daily spontaneous running alters behavioral and neurochemical indexes of nigrostriatal function.

Behavioral and neurochemical indexes of nigrostriatal dopaminergic function were compared between sedentary control rats (n = 12) and daily spontaneous running (DSR) male rats (n = 10). Nine weeks of DSR did not significantly alter body, heart, pituitary, or testes weights. DSR and control animals did differ in performance on a sensorimotor beam walking task, with DSR rats showing significantly shorter times required to cross the beam (60 +/- 17 vs. 119 +/- 14s; P < 0.02) as well as fewer slips off the beam (3.0 +/- 0.8 vs 6.2 +/- 1.1; P < 0.05). DSR animals also engaged in significantly greater durations of social investigation than control rats (43 +/- 5 vs 25 +/- 3 s; P < 0.01) when tested in a social investigation memory-recognition test. Basal dopamine release rates from superfused corpus striatal tissue fragments of DSR rats were about one-half those obtained from control animals (18 +/- 5 vs. 34 +/- 6 pg.mg-1.min-1; P < 0.05), whereas responses of these striatal tissue fragments to a depolarizing concentration of potassium were virtually identical (45 +/- 10 vs. 47 +/- 8 pg.mg-1.min-1). These data indicate that a relatively limited intensity of DSR insufficient to alter cardiovascular function can exert substantial effects on behavioral and neurochemical indicators of nigrostriatal dopaminergic activity.

Animals↗
PubMed1995

Regulation in vivo of the growth of Leydig cell tumors by antisense ribonucleic acid for parathyroid hormone-related peptide.

PTH-related peptide (PTHrP) has been shown to be the major mediator of hypercalcemia of malignancy, but may also exert effects on cell growth and differentiation. The Leydig cell tumor H-500, when implanted in Fischer rats, produces abundant PTHrP and eventually causes the death of the host animal. In the present study we have used antisense RNA technology to block the effects of PTHrP in H-500 Leydig tumor cells in vivo. The full-length rat PTHrP complementary DNA encoding amino acid -36-->141 was subcloned as an EcoRI-BglII insert in the antisense orientation into the mammalian expression vector pRc/CMV to produce the plasmid pRc-PAS. This plasmid was then stably transfected into the H-500 Leydig tumor cells with a Lipofectin reagent. After selection with the neomycin derivative G-418, a stable cell line, H-500-PTHrP-AS, was obtained which showed 80% inhibition of endogenous PTHrP messenger RNA compared to wild-type or vector-only transfected H-500 cells. Conditioned culture medium from these experimental cells showed a marked decrease in PTHrP immunoreactivity and in the ability of the medium to stimulate adenylate cyclase in UMR-106 rat osteosarcoma cells. Furthermore, inhibition of PTHrP production resulted in a significant increase in the doubling time of the H-500 cells. Transfection of the experimental plasmid into Rat-2 fibroblasts, which do not produce PTHrP, had no effect on cell growth. Control and experimental cells were then implanted sc into male Fischer rats. Animals were killed at timed intervals, and their tumor volumes were determined. Experimental animals receiving cells transfected with antisense PTHrP plasmid showed near-normal levels of plasma calcium and decreased expression of tumoral PTHrP messenger RNA. These animals also showed a 30-70% lower tumor volume during the course of the experiment compared to control animals. These studies have demonstrated that PTHrP can play a role as a promoter of tumor growth in vitro and in vivo.

Animals↗
PubMed1995

Microscopic anatomy of the equine skin with special reference to the dermis.

We have observed and re-evaluated the histology of the skin of the horse, using samples from four Thoroughbreds. The skin was composed of the usual three components: epidermis, dermis and subcutis. In particular, the dermis was found to have three fibrous components: a papillary layer, a reticular layer and a cordovan-leather tissue layer. The cordovan-leather tissue layer was subdivided into a superficial main layer and a deeper accessory layer. The superficial main layer was thick, and present in all of the skin samples. The deeper accessory layer was found in the dorsal and dorso-lateral parts of the neck and trunk and in the extremities. Hair bulbs and sudoriferous glands did not extend into the cordovan-leather tissue layer and subcutis.

Animals↗
PubMed1995

Immunocytochemical evidence for the presence of prolactin in the plerocercoid of Ligula intestinalis (Cestoda: Pseudophyllidea).

Immunoreactivity to prolactin in the nervous system of the plerocercoid of Ligula intestinalis was demonstrated by immunocytochemical method. Numerous PRL immunoreactive perikarya with long varicose fibres were observed in the peripheral nervous system in the worm, mainly in the transversal muscle layer and medullary parenchyma of the midbody. A few fibres were found in the main nerve cords of the central nervous system. PRL positive neurons sent their processes to associate with the main nerve cords. The immunostaining terminals appeared in the subtegument region in the lateral border of the plerocercoid. The result indicates that PRL immunoreactivity is well-developed in the plerocercoid of the cestode. The significance of the localization of prolactin in the worm is discussed.

Animals↗
PubMed1995

[Titanium porous-surface screw implant].

Titanium porous-surfaced screw implant was made by plasma-spray with Ti powder. The pore size was 80-300 microns. Two groups of implants were implanted in the mandibles of 15 dogs. Group A: porous-surfaced screw implant: Group B: smooth surface screw implant. The bone healing was evaluated by L. M. SEM. and shear strength testing. The results show that the osteo integration of two groups were completed after 12 weeks. The bone grew into porous surface. The shear strength of group A was significantly higher than that of group B.

Animals↗
PubMed1995

[Correlation analysis of lipids and apolipoproteins in plasma HDL, LDL and VLDL of normal subjects and endogenous hypertriglyceridemics].

The linear correlation and multiple stepwise regression analysis of lipids and apolipoproteins in plasma, HDL, LDL and VLDL of 20 normal subjects and 20 patients with endogenous hypertriglyceridemia was made. The result of simple factor analysis showed that there was a positive correlation of TG and VLDL TG with apoC II, C III, E, LDL apoB100 and VLDL apoC II, C III, E, B100; and a negative correlation with HDL apoA I. HDL-C was related positively with apoA I, HDL apoA I, C III and negatively with apoC III, E, LDL apoB100 and VLDL apoB100, C II, C III, E. TC was correlated positively with apoB100 and LDL apoB100. The result of multiple factor analysis showed that apoC III, E, B100/A I, VLDL apoC III and HDL apo C II, E, C II/C III, among 20 factors, were main factors which were related with TG. Apo C III, VLDL apoC III and LDL apoB100 were main factors which affected VLDL TG. ApoB100, and C II were main apolipoproteins which were related with TC; while the main apolipoproteins which affected HDL-C were apoA I, HDL apoA I, C II, VLDL apoE, HDL apoA II, the significance of the results is discussed.

Apolipoproteins↗
PubMed1995

[Effect of native and oxidation-modified LDL, VLDL and HDL on the morphological appearance and phenotype of cultured human arterial smooth muscle cells].

The arterial smooth muscle cells (SMC) are the predominant type of cells in atherosclerotic lesions, and their proliferation plays an important role in the process of AS genesis. We established the primary culture and sub-culture method for human arterial SMC and observed the effects of LDL, VLDL, HDL, OX-LDL, OX-VLDL and OX-HDL on the morphological appearance and phenotype of cultured human arterial SMC. The results revealed that the cells cultured in the medium containing OX-LDL, OX-VLDL and OX-HDL (25 micrograms/ml) became more irregular with long finger-like projects and lacked a bipolar shape, and the characteristic "hills" and "valleys" disappeared. LDL and VLDL also had the influence but in smaller degrees. HDL did not have any effect. The SMC cultured in the presence of OX-LDL (25 micrograms/ml) had less myofilaments and more endoplasmic reticulua, Golgi and mitochondria in cytoplasm compared with the cells in control group under electronmicroscope. These results suggest that the atherogenic role of LDL, VLDL, OX-LDL, OX-HDL, and OX-VLDL are closely related to their stimulating effects on the modulation of phenotype of arterial SMCs from "contractile" towards "synthetic".

Aorta↗
PubMed1995

Combination effects of gamma-interferon with pinyanmycin or psoralen on tongue cancer HSC3 cell line in vitro and in vivo.

The inhibitory effects of gamma-interferon (gamma-IFN), pinyanmycin (PYM), and psoralen (PSO) on human tongue cancer HSC3 cells were tested with MTT assay (tetrazolium-based colorimetric assay). The IC50 (drug concentration which causes 50% inhibition of the cell line) values of gamma-IFN, PYM and PSO were 371,535 U/ml, 224 ng/ml and 25,119 ng/ml, respectively. The CI50 (combination index) values of the combinations of PYM with gamma-IFN at the concentrations of 10(2), 10(3), 10(4) and 10(5) U/ml were 0.12, 0.04, 0.05, and 0.29, respectively; and those of PSO with gamma-IFN at the concentrations of 10(2), 10(3), 10(4) and 10(5) U/ml were 1.00, 0.66, 0.30 and 0.28, respectively. The growth inhibition (%) of the HSC3 cells transplanted tumor in nude mice by gamma-IFN, PYM, gamma-IFN plus PYM, PSO, and gamma-IFN plus PSO were 67.6, 103.5, 110.0, 83.1 and 102.9, respectively; the body weight loss (%) of the treated mice were 1.2, 6.9, 0.8, 5.0 and 1.8 respectively, and that of the control was 12.5. The results indicated that the combination effects of gamma-IFN with PYM or gamma-IFN with PSO are synergic and beneficial to the general health of the victim mice.

Animals↗
PubMed1995

[Stereoptical study of the microvilli in intrauterine growth retardation placenta with different ponderal indexes].

Two groups of 6 intrauterine growth retardation (IUGR) placentae each from normal ponderal index (NPI) or low ponderal index (LPI) and 10 placentae from normal pregnancy as control were quantitatively analyzed with light and electron microscopic morphometry. The results showed that the placental weight, volume, surface area of the villi and villous fetal capillary in IUGR were significantly reduced compared with those in the control group. Not only were the placental weight, volume, surface area of villi, villous capillary, intermicrovillous surface density and absolute values surface area of the microvilli in NPI group significantly lower than that in the control group, but also lower than in LPI group. This suggests that there was a functional deficiency of placenta in IUGR placentae, nonetheless, the changes of functional structures in IUGR placentae with different ponderal indexes were not the same. The stereoptical study with light microscopy and with the electron microscopic level in confirming that NPI group has a more severe deficiency in placental function than in the LPI.

Anthropometry↗
PubMed1995

[Inhibition of mRNA expression of silicotic collagen gene by tetrandrine].

Effects of tetrandrine (TT) on types I and III collagen gene mRNA in lung tissues of silicotic rats were studied with RNA dot blot and in situ hybridization by cDNA coding human and mouse Pro alpha 1 (I) and Pro alpha 1 (III) collagen. Results revealed types I and III collagen gene mRNA content in lung tissues of rats exposed to silica dust for two to four months was obviously greater than that in normal lung tissues (P < 0.05), and decreased significantly after treatment with TT (P < 0.05) by dot blot technique. In situ hybridization revealed silver granules of types I and III collagen gene mRNA were scattered in fibroblasts of alveolar septa in normal lung tissues, and in cellular nodes and thickened interstitia of silicotic tissues. It suggested aggregation of collagen in silicotic tissues was caused by enhancement of collagen gene expression, and TT could inhibit directly or indirectly transcription of collagen gene, and thus reduce synthesis of collagen protein in silicotic tissues.

Alkaloids↗
PubMed1995

[Primary-explant method of culturing human arterial smooth muscle cells].

The primary culture of human arterial smooth cells (SMC) was performed successfully using the primary-explant method. The cells formed "hills and valleys" characteristic of SMC; the myofilament bundles were observed in the cytoplasm of the cells under an electron microscope and the cells were stained red with Ma's method. The growing character of 35th passage SMC kept unchanged. In addition, some problems concerning the culture of human arterial smooth muscle cells are discussed.

Aorta↗
PubMed1995

[Study on lipid and apolipoprotein composition of plasma VLDL, LDL and HDL in endogenous hypertriglyceridemia].

We analysed the lipid and apolipoprotein (apo) composition of plasma VLDL, LDL and HDL including TG, FC, CE, PL and apoA I, A II, B100, C II, C III and E in 20 endogenous HTG patients whose plasma TG levels were > 2.26 mmol/L, TC < 6.74 mmol/L and in 20 normal subjects whose plasma lipid levels were normal (TG < 1.70 mmol/L, TC < 5.96 mmol/L). The results showed that the fasting plasma TG, apoC II, C III and E levels were significantly higher and HDL-C and apo A I levels lower in the HTG group than those in the normal group (P < 0.05). Abnormality of lipid and apolipoprotein composition of plasma VLDL, LDL and HDL in HTG was found. TG, FC, CE, PL and apoB100, C II, C III and E contents in VLDL were significantly increased in HTG (P < 0.01), while CE, apoA I, C II, C III and E in HDL were significantly decreased (P < 0.05) and TG in HDL significantly increased (P < 0.05) in HTG. TG and apoB100 in LDL in the HTG group were higher than those in the normal group (P < 0.05).

Adult↗
PubMed1995

[Changes of HDL-receptor of hepatic cell membrane in rabbit model of calcium bilirubinate cholangiolithiasis].

HDL-receptor of the hepatic cell membrane and Fch level of the hepatic tissue in the rabbit model of calcium bilirubinate cholangiolithiasis were examined. The results showed: (1)the HDL-receptors' Bmax of the biliary obstruction and infection (BOI) and biliary obstruction (BO) groups decreased during the 1st week after operation (P < 0.01); they were only 69.09% and 49.09% of that in the control group respectively, and the lowered level continued until the 6th week; the Kd values of BOI and BO groups were not different from that of the control group during the 1st week, but they were significantly higher in the 6th week after operation (P < 0.01); (2)the Fch levels of the hepatic tissue were slightly decreased in all experimental groups (P < 0.05). We concluded that under the conditions of biliary obstruction and infection, there was a disorder of the HDL receptors of hepatic cell membrane. At the early stage of biliary obstruction and infection, the receptors decreased in number, and at the later stage, the affinity changed and less HDL entered into the hepatic cell. Then the precurser cholesterol pool for BA biosynthesis narrowed. Thus, BA secreted from the liver cells into genetic elements possibly promote the formation of the calcium bilirubinate gallstones.

Animals↗
PubMed1995

[The pathological investigations on termination of early pregnancy with mifepristone].

133 samples of induced early abortions using mifepristone (RU486) in combination with misoprostol (Miso) were examined. There were no significant difference in the outcome and pathological changes between the two groups with varied RU486-Miso dosages. Another 133 samples of abortus (gestational age < or = 49 days) from vacuum aspiration were used as control. The villi of RU486-Miso group showed more extensive and severer degeneration than the villi of the control group under light and electron microscopy. However, whether RU486 affects the trophoblasts directly or in directly is yet in dispute. Further investigation is needed.

Abortion, Induced↗
PubMed1995

[Effects of alveolar macrophage conditioned media from interstitial lung disease patients on the procollagen mRNA expression in human lung fibroblasts].

We investigated the effects of alveolar macrophage (Am) conditioned media from interstitial lung disease (ILD) patients on lung fibroblast proliferation and procollagen mRNA expression in cells. 13 patients with ILD and 8 patients with bronchial carcinoma (BC) received bronchoalveolar lavage (BAL). The BAL fluid was collected and centrifuged to obtain cells of two groups. The cells were washed and incubated at 37 degrees C and 5% CO2 for 2 hours in DMEM with 10% FCS. Then the adherent Am was added with DMEM with 0.1% FCS. (2ml/10(6) cells), and cultured at 37 degrees C and 5% CO2 for 24 hours. The supernatant was obtained by centrifugation and stored in -20 degrees C for experiment. Lung fibroblasts were planted in 96 well microtitle plate and cultured to confluence. Each well was added 100 microliters Am conditioned medium and incubated for 16 hours, then added 5 uci 3H-TdR for measuring the fibroblast proliferation and incubated till 24 hours. The cells were collected and counted. The DMEM with 0.1% FCS was used as control. When stimulated with Am conditioned media from ILD patients, fibroblast proliferation increased 71%, but for media from BC patients, it just increased 14% (P < 0.05). After stimulated with conditioned media for 24 hours, the cells were trypzied, collected, ashed and isolated total RNA with guanine method. Several samples' total RNA was subjected to electrophoresis in 1% agaroseformaldehyde gel to test specificity of procollagen al (I) and al (III) cDNA probes. 10 micrograms total RNA of each sample was bloted to nitrit membrane and baked at 80 degrees C for 2 hours.

Cell Division↗
PubMed1995

[Immunohistochemical observations on production and distribution of endothelin in atherosclerosis plaques].

An analysis of endothelin in atherosclerotic plaques using immunohistochemical methods showed that endothelin not only existed in endothelial cells, large amounts were also found in the proliferating intimal vascular smooth muscle cells (VSMC). In the de-endothelized thoracic aorta of rats, significant amounts of endothelin could be produced by proliferating intimal VSMC. Radio-immunological studies demonstrated that the extent of VSMC proliferation was in direct ratio to endothelin content, which suggests that production of endothelin is related to proliferation of VSMC in atherosclerotic plaques.

Adult↗