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Biomedical subjects

H Shi

Publications and source records attributed to H Shi.

At least 181 records · Page 10Linked to original sources
PubMed1996

Antioxidant property of Fructus Momordicae extract.

The antioxidant effect of Fructus Momordicae extract, FME (mogrosides 75 approximately 80%), was studied. FME reduced the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and scavenged superoxide radicals (O2-) generated by a hypoxanthine and xanthine oxidase system. It also scavenged hydroxyl radicals (.OH) generated by Fenton reaction. In addition, FME inhibited Fe(II) induced lipid peroxidation in rat cortex homogenates in a dose-dependent manner, as indicated by decreased thiobarbituric acid-reactive substances (TBARS) formation. Oral administration of FME inhibited TBARS and malonaldehyde (MDA) formation in the ipsilateral cortex 30 min after iron-salt injection into the left cortex of rat. FME showed inhibitory effect on 4-hydroxy-2(E)-nonenal (4-HNE) formation induced by Fe(III) injection into the rat cortex. These data suggest that Fructus Momordicae extract has an antioxidant activity against free radicals and lipid peroxidation.

Animals↗
PubMed1996

Effects of calcium on the migration and recruitment of macrophages and macrophage-derived foam cells.

Calcium is thought to play an important role in the genesis of atherosclerotic lesions, but the precise mechanisms involved are unclear. In the present investigation, we have used in vitro systems to investigate the effects of calcium on one key aspect of lesion development: the migration of macrophages and macrophage/foam cells. Using agarose plate migration assays, the migratory characteristics of macrophages exposed to 1) no lipoprotein, 2) low density lipoprotein (LDL), 3) acetylated low density lipoprotein (acLDL), and ) oxidized low density lipoprotein were examined. The most marked stimulatory effect on macrophage mobility was observed when freshly isolated cells were exposed to acLDL during the migration assay. High levels of exogenous calcium were found to suppress the stimulatory effect of acLDL on migration. As the responses of macrophages exposed to a uniform concentration of agents in the surrounding medium may differ from chemotactic responses to a concentration gradient, the migration of macrophages, with and without preexposure to acLDL or LDL, was studied using microchemotaxis Boyden chambers. Under these conditions, calcium acted as a highly potent chemoattractant, especially to cells that had been preincubated with acLDL. These results suggest how elevated external calcium concentration leads initially to macrophage recruitment, and subsequently to foam cell aggregation and lipid core formation, in association with calcification, in the developing atherosclerotic plaque.

Animals↗
PubMed1996

Children's memories in the wake of Challenger.

OBJECTIVE: The Challenger spacecraft explosion of Jan. 28, 1986, offered an opportunity to study the memories of normal latency and adolescent children of different emotional involvements following one sudden and distant disaster. How would children of various levels of concern express their memories? And if studied over time, how would these narratives change? Would there be developmental differences? And would there be false details of memory? METHOD: The authors set out to compare the memories of 153 children from Concord, N.H. (who watched the explosion on television), and Porterville, Calif. (who heard about it). The structured-interview responses of involved and less involved children; latency-age versus adolescent children; and those seen initially (5-7 weeks after the explosion) versus those same children seen later (at 14 months) were statistically compared. RESULTS: The vast majority of children's memories of Challenger were clear, consistent, and detailed, with highlighting of personal placement, who else was there, and personal occurrences linked to the event. Those children who were less emotionally involved demonstrated significantly less clarity, consistency, and correct ordering of sequences and were less likely to remember personal placement, other people who were there, and related personal incidents. About 30% of all children in this study misunderstood something about Challenger and incorporated these misunderstandings into their memories as false details. Latency-age children continued to harbor false details for 14 months, as opposed to the adolescents. CONCLUSIONS: Childhood memories of the Challenger space shuttle explosion appeared predictable, were related to patterns of memory that have been observed following single, unrepeated traumas, and reflected age and stage differences.

Adolescent↗
PubMed1996

Promoter-specific activation of mouse lactoferrin gene by epidermal growth factor involves two adjacent regulatory elements.

The mouse lactoferrin gene responded to forskolin, 12-O-tetradecanoyl phorbol-13-acetate, and epidermal growth factor (EGF) stimulation via two adjacent enhancer elements, the cAMP response element (CRE) and EGF response element (EGFRE), collectively referred to as the mitogen response unit. In this report, we examined the minimal promoter and enhancer elements of the mouse lactoferrin gene that are required for EGF-induced transcriptional activation. We found that the CRE and noncanonical TATA box (ATAAA) are the minimal promoter elements for basal activity of the chloramphenicol acetyltransferase (CAT) reporter construct whereas the EGFRE is needed for an additional activity induced by EGF in transiently transfected human endometrial carcinoma RL95-2 cells (RL95-2). The EGFRE, however, did not function in heterologous promoters [SV 40 and thymidine kinase (TK)]. Therefore, EGF-stimulated lactoferrin gene activity is promoter specific in RL95-2 cells. In transiently transfected cells, EGF and forskolin showed synergistic effects on the CAT reporter that contained both response elements. Mutation made at either element or insertion of extra nucleotides between the two elements severely affected EGF-stimulated activity. Nuclear protein prepared from RL95-2 cells formed three complexes (A, B, and C) with the oligonucleotides containing both EGFRE and CRE in electrophoretic mobility shift assay. A new complex (E) was detected with the nuclear protein of EGF-treated cells. By oligonucleotide competition experiments, we demonstrated that the complex E was generated by protein bound to CRE. EGF-induced binding activity could be abolished by calf intestinal alkaline phosphatase but not by the protein synthesis inhibitor, cycloheximide. Therefore, binding of a preexisting phosphoprotein to the CRE region could be one of the requirements for EGF-induced mouse lactoferrin gene promoter activity.

Animals↗
PubMed1996

A misfolded form of 5S rRNA is complexed with the Ro and La autoantigens.

In both vertebrate and invertebrate cells, the 60-kDa Ro autoantigen is bound to small cytoplasmic RNAs known as Y RNAs. In Xenopus oocytes, the 60-kDa Ro protein is also complexed with a class of 5S rRNA precursors that contain internal mutations. Because these 5S rRNA precursors are processed inefficiently and degraded eventually, the Ro protein may function in a quality control pathway for 5S rRNA biosynthesis. We have investigated the sequence and secondary structure determinants in the mutant 5S rRNAs that confer binding by the 60-kDa Ro protein. The mutant 5S rRNAs fold to form an alternative helix that is required for recognition by the 60-kDa Ro protein. Mutations that disrupt the alternative helix eliminate Ro protein binding, whereas compensatory changes that restore the helix are bound efficiently by the Ro protein. When the structure of the mutant RNA was probed using dimethylsulfate and oligonucleotide-directed RNase H cleavage, the results were consistent with the formation of the alternative structure. The La protein, which is also complexed with the mutant 5S rRNA precursors, protects similar sequences from nuclease digestion as does the 60-kDa Ro protein. Thus, the binding sites for these two proteins are either nearby on the RNA, or the two proteins may be complexed through protein-protein interactions. When the human Ro protein is expressed in the yeast Saccharomyces cerevisiae, the protein binds wild-type 5S rRNA precursors, suggesting that a population of wild-type precursors also folds into the alternative structure.

Animals↗
PubMed1996

Effect of interferon-gamma on antigen-induced eosinophil infiltration into the mouse airway.

OBJECTIVE: To investigate whether murine recombinant interferon-gamma (IFN-gamma) is capable of inhibiting antigen-induced eosinophil (EOS) infiltration into the mouse airway. MATERIALS AND METHODS: BALB/c mice were sensitized and challenged repeatedly with ovalbumin (OVA) to develop an allergic airway inflammation model. The experimental mice were given injection of different doses of IFN-gamma. The numbers of EOS in bronchoalveolar lavage fluid (BALF) from each group were counted, and concentrations of interleukin (IL)-5 in supernatants of cultured spleen cells were detected. RESULTS: In sensitized mice challenged with OVA 20 minutes once a day for 6 days, the number of BLAF EOS was 9.53 +/- 0.84 x 10(5)/ml. However, no EOS could be found in BALF from mice without OVA sensitization and challenge. In mice treated with IFN-gamma, doses of IFN-gamma (1.0 x 10(3), 1.0 x 10(4), 1.0 x 10(5)U/KG) produced 29.8% (P < 0.05), 55.7% (P < 0.01), and 69.0% (P < 0.01) inhibition of eosinophilia, respectively. The results also showed that IFN-gamma prevented antigen-induced EOS recruitment into airway accompanied be decrement of levels of IL-5 with a dose-related response. CONCLUSION: IFN-gamma is capable of inhibiting EOS infiltration into mouse airway by inhibiting the production of IL-5. Our results suggested that IFN-gamma may be of value in treating asthma in human beings.

Animals↗
PubMed1996

Analysis of Chinese isolates of Trichinella spiralis by molecular biotechnology.

OBJECTIVE: To investigate the relationships among Trichinella spiralis isolates obtained from different hosts and geographical regions in China. MATERIALS AND METHODS: Six isolates of Trichinella spiralis obtained from Changchun, Tianjin, Xi'an, Henan and Yunnan were detected. All the isolates were collected from pigs or dogs. Restriction fragment length polymorphism (RFLP), isoenzyme electrophoresis and soluble protein analysis were used. RESULTS: Distinctive banding patterns in restriction maps were seen between Changchun and other isolates studied. A cloned specific repetitive DNA sequence (1.12 kb) from Changchun isolate was then selected to prepare probe for Southern blotting of DNA fragments. The hybridizing banding patterns among the isolates were different and only the Changchun isolate showed the 1.12 kb band. The Changchun isolate was also distinguishable from the other isolates in isoenzyme patterns of GP1, G6PD, HK, 6PGDH and AK, as well as in isoelectric focusing electrophoresis where the Changchun isolate presented a specific band at 4.1 P1. CONCLUSIONS: There are at least two different biological types of Trichinella spiralis in China and the differences between them may be attributed to different geographical origins and/or different hosts.

Animals↗
PubMed1996

[Effect of interferon-gamma on antigen-induced eosinophil infiltration in mouse airway].

Repeated aerosolized ovalbumin (OVA) challenge of OVA-sensitized mice induces bronchoalveolar lavage fluid (BALF) eosinophilia. The influence of interferon-gamma (IFN-gamma) on antigen-induced eosinophil recruitment in the airway as well as the concentration of interleukin-5 (IL-5) in supernatants of cultured spleen cells were examined. In sensitized mice challenged with OVA 20 minutes once a day for 6 days, the number of BALF eosinophils was (9.53 +/- 0.84) x 10(8)/L. However, no eosinophil could be found in the BALF from mice without OVA sensitization and challenge. In mice treated with intraperitoneal injection of INF-gamma before each challenge, different doses of IFN-gamma (1.0 x 10(3) U/kg, 1.0 x 10(4) U/kg and 1.0 x 10(5) U/kg) produced different degrees of eosinophilia inhibition 29.8% (P < 0.05), 55.7% (P < 0.01) and 69.0% (P < 0.01). Our results showed that IFN-gamma prevented antigen-induced eosinophil infiltration in airway accompanied by a decrement of levels of IL-5 with a dose related response. It is concluded that IFN-gamma is capable of inhibiting eosinophil infiltration in mouse airway by inhibiting the production of IL-5. Our results suggested that IFN-gamma may be of value in eliminating asthmatic airway inflammation in humans.

Animals↗
PubMed1996

[Differentiation of cytology of BALF between BOOP and UIP].

OBJECTIVE: BOOP is a disease entity proposed by Epler in 1985, and UIP is considered an important disease to be differentiated from BOOP. The aim of this study was to identify characteristic features in BALF samples of patients with BOOP and UIP. METHODS: Differential cell count and T-cell subpopulation of the BALF obtained from 7 patients with BOOP and 7 patients with UIP, both histologically verified, were determined. RESULTS: In BOOP patients the ratio of lymphocytes and the CD8+ cell in BALF were significantly higher and CD4+/cd8+ ratio was significantly lower than those of the UIP patients (P < 0.01). In UIP patients the ratio of neutrophils in BALF was significantly higher than that of the BOOP patients (P < 0.05). CONCLUSIONS: Cytological examination of BALF is effective in differentiating BOOP from UIP and it can provide useful information about both different pathogenetic processes of the two entities.

Aged↗
PubMed1995

Quantitative determination of serum iron in human blood by high-performance capillary electrophoresis.

A capillary electrophoretic (HPCE) method that can be used to quantitatively determine trace amounts of iron has been developed and applied to determine the iron level in human serum. After precipitation of serum proteins, Fe(III) in the serum is reduced to Fe(II) with hydroxylamine hydrochloride, and a stable Fe(II)-1,10-phenanthroline complex is formed by adding 1,10-phenanthroline to the supernatant containing 2.5 mM ammonium acetate-acetic acid at pH 5.0. The Fe(II)-1,10-phenanthroline complex, [Fe(C12H8N2)3]2+, has a very strong absorbance at 270 nm (with a molar absorptivity of approximately 9.2.10(4)). By measuring the absorbance of [Fe(C12H8N2)3]2+ at 270 nm, the iron level in human serum can be precisely quantified. The interference from copper, a major interference in serum, can be totally eliminated due to the complete separation of [Fe(C12H8N2)3]2+ and the Cu(II)-1,10-phenanthroline complex. In addition, other problems that usually occurred with conventional spectrophotometric methods, such as co-precipitation and occlusion of iron during sample pretreatment, are significantly minimized due to the ability to wash the precipitate and the higher detection sensitivity. With this method, a single drop (10 microliters) of serum would be sufficient to determine the serum iron concentration. The method is reliable, sensitive, rapid and reproducible. Thus it is highly suitable for use in the clinical laboratory.

Electrophoresis, Capillary↗
PubMed1995

Determination of vitamin A in dried human blood spots by high-performance capillary electrophoresis with laser-excited fluorescence detection.

We have developed a high-performance capillary electrophoresis (HPCE) method to analyze the retinol (vitamin A) concentration as retinol-retinol binding protein (holo-RBP) from microvolumes of serum (5-10 microliters) or one to two drops (approximately 20 microliters) of blood collected and air-dried on blood collection filter paper. A 0.64-cm diameter disk was cut from the dried whole blood specimens and the samples were dissolved in a pretreatment buffer and filtered. Filtrate was injected onto the HPCE column for analysis. The separation was carried out in a 60 cm x 50 microns I.D. fused-silica capillary and the running voltage was 20 kV. A He-Cd laser with a wavelength of 325 nm was used for excitation, and the fluorescence of the holo-RBP complex was monitored at 465 nm by a photodiode. A virtual linear relationship was obtained for the retinol concentrations between HPCE and HPLC for 28 serum samples, 19 dried venous blood samples and 9 capillary dried blood spot samples, indicating that valid measures of serum retinol can be obtained from one to two drops of capillary blood collected on filter paper. The absolute detection limit for retinol by HPCE is below 3 micrograms/l. The method is very useful for vitamin A level screening, especially for children and premature new-born babies.

Chromatography, High Pressure Liquid↗
PubMed1995

Physical disability in older runners: prevalence, risk factors, and progression with age.

BACKGROUND: Concern exists that certain types of exercise, particularly vigorous activity, may increase physical disability among older individuals. We investigated the prevalence of, and risk factors for, physical disability in active older persons (runners), and examined factors influencing the progression of physical disability with age. METHODS: Physical disability, measured using the Health Assessment Questionnaire Disability Index, was assessed prospectively in 454 runners, age 50 or greater, over five to seven years by annual mailed questionnaires. Baseline sociodemographic, clinical, and life-style characteristics associated with the presence of any disability over the course of the study were determined and contrasted with those in 292 older non-runners who had been similarly followed. RESULTS: Two hundred twenty-two runners (49%) reported some physical disability during the study. The presence of arthritis symptoms at baseline was the most important risk factor for physical disability; older age, greater body mass index, strenuous work-related physical activity, and the use of more medications were also associated with a greater likelihood of physical disability. Among the non-runners, 224 (77%) reported some physical disability, and the presence of arthritis symptoms was also the most important risk factor for physical disability in this group. Age-related changes in physical disability differed between those with and without arthritis symptoms in both the runner and non-runner groups. CONCLUSIONS: The presence of arthritis symptoms was an important risk factor for physical disability among both older runners and non-runners, and also identified subgroups of individuals with different progressions of disability with age.

Age Factors↗
PubMed1995

Effects of input pressure on in vitro turtle heart during anoxia and acidosis: a 31P-NMR study.

In vitro working hearts of the turtle, Chrysemys picta bellii, paced at 30 beats/min, were studied over a range of input pressures in the following sequence of perfusion conditions: control normoxia, control anoxia, lactacidotic normoxia, and lactacidotic anoxia. Two such series of experiments were performed. In series 1 (n = 12), ventricular pressure (PV) and cardiac output were measured, and power output and dPV/dt were calculated. In series 2 (n = 5), intracellular phosphorus metabolites and intracellular pH (pHi) were also measured using 31P-nuclear magnetic resonance (31P-NMR) spectroscopy. In series 1 all mechanical variables increased with input pressure in generally similar fashion, except during anoxic acidosis, during which mechanical performance was depressed and was increased less or not at all by input pressure. Creatine phosphate (CP) and pHi fell significantly in anoxia and anoxic acidosis, but neither these variables, ATP, CP/ATP, nor, presumably, ADP changed as a function of input pressure with any perfusate despite often large increments in mechanical output. We conclude that anoxia and acidosis act synergistically to depress cardiac function in turtle hearts. Also, the insensitivity of NMR variables to changes in input pressure and cardiodynamics suggests that changes in these variables are unimportant for controlling energy turnover in this preparation.

Acidosis↗
PubMed1995

A role for increased lutropin/choriogonadotropin receptor (LHR) gene transcription in the follitropin-stimulated induction of the LHR in granulosa cells.

Follitropin (FSH) has been shown in previous studies to stimulate the induction of the LH/CG receptor (LHR) and LHR mRNA in the granulosa cells of diethylstilbesterol-primed immature rats. The present studies were undertaken to identify the mechanisms underlying the hormone-dependent induction of the LHR in rat granulosa cells. The effect of FSH on LHR mRNA stability was determined by measuring the decay of LHR mRNA after removal of FSH under conditions where transcription was inhibited. Under these conditions, readdition of FSH had little effect on mRNA stability. However, inhibitors of transcription themselves were found to have a marked effect on stabilizing the LHR mRNA, thus potentially masking an effect of FSH. These results suggest that there is a labile destabilizing factor that constitutively degrades LHR mRNA. At present, it cannot be ascertained whether FSH has any effect on this destabilizing factor. Transcriptional activity of the LHR gene was examined using nuclear run-on assays. It was found that 1) in the absence of FSH, LHR-binding activity and mRNA levels were negligible, but the LHR gene was transcriptionally active in granulosa cells of immature rats; 2) incubations of granulosa cells with FSH or 8-bromo-cAMP significantly increased endogenous LHR gene transcription (approximately 10-fold) under conditions where increases in LHR mRNA were observed; 3) the continuous presence of FSH or 8-bromo-cAMP was required to maintain elevated levels of LHR gene transcription and LHR mRNA; and 4) exogenous estradiol alone had no effect on transcription of the LHR gene although it was able to synergistically enhance FSH-induced LHR expression. These experiments suggest that while the effects of estradiol on LHR induction do not appear to be mediated by an increase in LHR gene transcription, the effects of FSH (or cAMP) on LHR induction are clearly mediated, at least in part, by significant increases in the rate of LHR gene transcription.

8-Bromo Cyclic Adenosine Monophosphate↗