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H Liu

Publications and source records attributed to H Liu.

At least 1,063 records · Page 59Linked to original sources

Extraction of lysozyme, alpha-chymotrypsin, and pepsin into reverse micelles formed using an anionic surfactant, isooctane, and water.

The extraction of lysozyme, alpha-chymotrypsin, and pepsin from buffered salt solutions into reverse micelles was examined at different pH values and surfactant concentrations. The reverse micelles was formed by mixing aqueous buffer supplemented with KCl and an organic phase of isooctane(2,2,4-trimethylpentane), containing the anionic surfactant, Aerosol O. T. (dioctyl ester of sodium sulfosuccinic acid). The technique of dynamic laser scattering was used to measure the size of reverse micelles which were in equilibrium with the aqueous phase. It was found that the size of the reverse micelles decreased with increasing ionic strength but increased with increasing AOT concentration. In the process of extraction, the reverse micelles might have rearranged themselves to host the protein. The sizes of protein-filled and -unfilled reverse micelles were different, and an open equilibrium could be reached between them. Under the extraction conditions, only a small number of micelles were found to contain protein.

Chymotrypsin↗

Equilibrium dialysis of metal-serum albumin. I. Successive stability constants of Zn(II)-serum albumin and the Zn(2+)-induced cross-linking self-association.

The binding of Zn(II) to human serum albumin (HSA) and bovine serum albumin (BSA) was intensively studied by equilibrium dialysis. The successive stability constants were obtained by least-squares fitting. For both the Zn(II)-HSA and Zn(II)-BSA systems, the successive stability constants are basically similar, though such constants for the latter generally slightly larger than those for the former; the order of magnitude of K1 and K2 was found to be approximately 10(5) M-1. The twelve binding sites found for Zn(II)-HSA and fourteen binding sites for Zn(II)-BSA can be divided into three and two different sets, respectively, but in both systems, there exist approximately three identical strongest binding sites. The binding equilibrium of Zn(II)-HSA markedly depends on the concentration of HSA. The type of Scatchard plots indicates the existence of the Zn(2+)-induced cross-linking self-association of HSA, which was found from Wyman plots to be the strongest at a concentration of Zn2+ in the range (4-6) x 10(-6) M. The maximum of the apparent self-association constants k2 so obtained was approximately 2.6 x 10(4) M-1. Such a self-association mechanism and the order of magnitude of K1 and K2 both to some extent support the inference that the zinc group ions are bound to the cysteinyl sulphur atoms.

Animals↗

Inhibition of estrogen-induced progesterone receptor in MCF-7 human breast cancer cells by aryl hydrocarbon (Ah) receptor agonists.

17 beta-Estradiol (E2) induces progesterone receptor (PR) binding, immunoreactive protein, nuclear PR formation and PR mRNA levels in MCF-7 human breast cancer cells. Gel mobility shift analysis of nuclear extracts from E2-treated cells also exhibited a higher intensity retarded band associated with formation of a PR complex with a consensus [32P]progesterone/glucocorticoid responsive element. In contrast, 1 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alone did not alter or decrease these same responses in MCF-7 cells; however, in cells co-treated with 1 nM TCDD plus 1 nM E2, TCDD significantly inhibited all the E2-induced responses. Scatchard analysis of PR binding demonstrated that TCDD decreased the number of E2-induced PR cellular binding sites but not the binding affinity of the PR for a radiolabeled promegestrone. In parallel studies, 3-methylcholanthrene, a prototypical polynuclear aromatic hydrocarbon, also inhibited E2-induced PR binding and immunoreactive protein. For a series of halogenated aromatics including 2,3,7,8- and 1,2,7,8-tetrachlorodibenzofuran, 1,3,7,8-TCDD and 6-methyl-1,3,8-trichlorodibenzofuran, their rank order potency for inhibiting E2-induced PR binding paralleled their rank order binding to the aryl hydrocarbon (Ah) receptor. These results support a role for the Ah receptor in mediating the antiestrogenic activity of polynuclear and halogenated aromatic hydrocarbons and illustrate cross-talk between the Ah and estrogen receptor signal transduction pathways.

Blotting, Northern↗

The influence of polytherapy on the relationships between serum carbamazepine and its metabolites in epileptic children.

The influence of polytherapy on the relationships between the age, weight, carbamazepine (CBZ) dose, total clearance, and intrinsic clearance, with concentrations, concentration ratios, and level/dose ratios of CBZ, carbamazepine-10,11-epoxide (CBZ-E) and trans-10,11-dihydroxy-10,11-dihydro-carbamazepine (CBZ-H) are investigated. Three groups of patients with CBZ monotherapy, or receiving CBZ polytherapy by taking CBZ and valproic acid (VPA) or CBZ plus other antiepileptic drugs (AEDs) were studied. The significant correlations between serum CBZ concentrations and CBZ dose in patients taking CBZ alone were no longer significant in patients with polytherapy, and the positive associations between serum CBZ-E concentrations and CBZ dose were lost in patients with CBZ + VPA. Only the concentrations of CBZ-H had significant correlations with CBZ dose in all three groups of patients. Results from this relationship study indicate a heteroinduction effect of other AEDs on CBZ metabolism, and a relatively weak influence on CBZ-E elimination. Data also suggest that there is a block in the biotransformation from CBZ-E to CBZ-H in patients taking CBZ + VPA, presumably caused by the inhibition effect of VPA on epoxide hydrolase. Therapeutic drug monitoring of CBZ will benefit from the knowledge obtained from the relationship study.

Aging↗

Expression and export in Escherichia coli of fusion proteins containing carboxy-terminally located honeybee prepromelittin.

The aim of this work was to express a eukaryotic pre-protein in Escherichia coli so that it could be obtained intact, without cleavage, by bacterial leader peptidase. To this end, cDNA coding for honeybee prepromelittin was ligated to the 3' end of genes coding for truncated forms of either Protein A or beta-galactosidase (beta-Gal) under the control of inducible promoters, with an oligonucleotide coding for the Factor Xa cleavage site at the junction between the two proteins. The Protein A fusion was expressed in good yield, and about 80% of it formed inclusion bodies. The prepromelittin section of the Protein A fusion caused some export of the intact fusion protein to the growth medium. The prepromelittin beta-Gal fusion was expressed in low yield and became associated with the E. coli cytoplasmic membrane. Its expression was toxic to E. coli. Thus, the synthesis of a full-length eukaryotic pre-protein in E. coli is best achieved when the fusion protein forms inclusion bodies.

Animals↗

Marrow granulocyte-macrophage progenitor cell response to burn injury as modified by endotoxin and indomethacin.

The production and release of granulocytes and macrophages are significantly impaired following burn injury and infection. In an attempt to determine the factors responsible for these adverse effects and their potential treatments, we performed a series of studies in mice analyzing the bone marrow response to burn wound infection. The proliferative response of the marrow granulocyte-macrophage progenitor cell (GM-CFC) in male BDF1 mice undergoing a dorsal scald burn or burn wound seeding with 1000 colony forming units of Pseudomonas aeruginosa was determined on day 3 postburn using a clonal culture of GM-CFC. Mice with infected burn wounds had a rate of GM-CFC proliferation that was 50% that of noninfected animals and levels of circulating colony stimulating activity (CSA) 30% those of controls (p = 0.006). Similar suppression of marrow proliferative status could be replicated with the administration of endotoxin to normal or burned animals as had been observed for burn-infected animals. The administration of indomethacin (5 mg/kg.day) substantially restored the GM-CFC proliferation in mice with infected burns as well as in animals given endotoxin. Indomethacin-treated animals had CSA values 244% those of untreated burn-infected animals (p = 0.016). We take these observations to suggest that suppression of myelopoiesis in burn-infected animals is related in part to endotoxin-stimulated production of prostaglandin mediators that altered myeloid proliferation and was responsive to cyclooxygenase blockade.

Animals↗

Macrophage suppression of granulocyte and macrophage growth following burn wound infection.

Burn injury results in alterations in granulocyte and macrophage production. Since macrophages may mediate these alterations we determined the effects of macrophages obtained from animals with burn injury with and without infection on the growth of marrow granulocyte macrophage progenitor cells (GM-CFCs). The in vitro GM-CFC growth response for maximally stimulated cultures was reduced by 25% to 30% (p < 0.01) for burned and infected (B + I) animal macrophages compared with burned (B) or sham (S) animals. Macrophages stimulated with endotoxin caused a further reduction for all groups in GM-CFC growth, most notably so for B + I macrophages. Burned + infected animal macrophages or all-endotoxin macrophages cocultured with indomethacin did not suppress GM-CFC growth. Following burn injury and infection, macrophages spontaneously elaborate negative regulators of myeloid growth that is further increased by endotoxin. It is likely that PGE2, a known negative regulator of granulocyte macrophage growth, is largely responsible for this suppressive effect.

Animals↗

Improved therapeutic monitoring of drug interactions in epileptic children using carbamazepine polytherapy.

Drug interactions in epileptic children with carbamazepine (CBZ) polytherapy were investigated by analysis of total and free CBZ and its metabolites simultaneously. Heteroinduction effects of CBZ metabolism by other antiepileptic drugs (AEDs), including phenytoin (PHT), phenobarbital (PB), or primidone (PRM), were clearly demonstrated. Serum CBZ level/dose ratios in patients taking CBZ plus other AEDs were decreased while CBZ-10,11-epoxide (CBZ-E) and trans-10,11-dihydroxy-10,11-dihydro-CBZ (CBZ-H) concentrations were significantly increased compared to patients with CBZ alone. Concentration ratios of CBZ-H/CBZ and CBZ-E/CBZ were also significantly higher in patients taking CBZ plus other AEDs. Interactions between CBZ and valproic acid (VPA) involved both protein binding displacement and metabolic inhibition. Patients taking CBZ plus VPA showed significantly increased free fractions of CBZ and CBZ-E and substantially increased serum CBZ-E concentrations and CBZ-E level/dose ratios, while CBZ-H/CBZ-E concentration ratios were decreased compared with patients on CBZ alone. Since this approach investigates the in vivo relationship between substrates and products of the enzymes involved in CBZ biotransformation (the ratios between CBZ and its metabolites), detailed information about the activities of the enzymes may be obtained. This approach appears to be a practical way to improve the monitoring of CBZ metabolism influenced by various physiological or pathological conditions and achieve a better understanding of the drug interactions under different drug regimens (coadministered inhibitor or inducer). This principle may also be adopted for other drugs with similar metabolic characteristics.

Adolescent↗

Influence of sex, age, weight, and carbamazepine dose on serum concentrations, concentration ratios, and level/dose ratios of carbamazepine and its metabolites.

We have conducted a comprehensive study in a group of epileptic children (25 boys and 30 girls) receiving carbamazepine (CBZ) monotherapy. The influence of sex, age, weight, and CBZ daily dose on serum CBZ, carbamazepine-10,11-epoxide (CBZ-E), and trans-10,11-dihydroxy-10,11-dihydro-carbamazepine (CBZ-H) concentrations, concentration ratios, and level/dose ratios were investigated. Compared with girls, boys required significantly larger CBZ dose and showed higher CBZ apparent clearances and lower level/dose ratios of CBZ and its metabolites. There were no significant differences between boys and girls in serum concentrations, concentration ratios, and free fractions of CBZ and its metabolites, although there were trends that boys had slightly higher concentration ratios. The relationship analysis suggested that there was a dose-dependent autoinduction of CBZ metabolism, and CBZ metabolism was decreased as patients mature, as measured by weight and age. Age showed a significant positive relationship with the free fractions of CBZ and its metabolites, indicating decreased protein binding of CBZ and its metabolites with the increase of age. Serum CBZ concentration is not a reliable index of CBZ dose, as there is only a weak correlation between them. Serum CBZ-H concentration showed strong positive correlations with CBZ dose and might be a valuable index in assessing patient compliance. The influence of sex, body weight, age, and CBZ dose on CBZ and its metabolites should be taken into consideration in further clinical studies.

Aging↗

Alterations of glucose transporter mRNA and protein levels in brain following thermal injury and sepsis in mice.

Since glucose transport and utilization are profoundly influenced by injury and infection, and the brain is an organ which primarily utilizes glucose as its energy source, we examined the status of the facilitative glucose transporters GLUT1 and GLUT3 in brain following thermal injury and infection. BDF1 mice underwent a 15% total body surface area burn with or without Pseudomonas aeruginosa infection. At 4 and 72 h post injury +/- infection, GLUT1 and GLUT3 mRNA abundance was measured by Northern blotting, and the correlative proteins determined using Western blotting. At 4 h, both brain GLUT1 mRNA and protein abundance were significantly increased in burned (mRNA 150 +/- 12%, protein 122 +/- 6%) and burn/infected (mRNA 165 +/- 11%, protein 119 +/- 5%) animals. At 72 h, GLUT1 mRNA and protein levels were also significantly increased in burn (mRNA: 139 +/- 11%, protein: 120 +/- 7%) and burn/infected (mRNA: 145 +/- 14%, protein: 138 +/- 8%) animals. Our studies suggest that alterations of GLUT1 mRNA and protein abundance were primary responses to the burn injury and were not further altered by burn wound infection.

Animals↗

Methods to calculate the lens efficiency in optically coupled CCD x-ray imaging systems.

In lens-coupled CCD x-ray imaging, the lens efficiency is of critical importance for attaining an x-ray quantum-noise-limited system. However, the equations and the associated parameters of this process have not always been used properly in some of the literature. This can result in the incorrect estimation of the signal-to-noise ratio (SNR). In practice, it is found more convenient to use lens-coupling efficiency equations which assume that the scintillating screen is an extended Lambertian source, since the number of light photons emerging from various scintillating screens has been measured and reported by several investigators. This communication examines several of the most common types of lens-coupling efficiency equations and explains how to use them correctly with other parameters to calculate the SNR of a lens-coupled CCD x-ray imaging system.

Biophysical Phenomena↗

Effects of vanadium treatment on the alterations of cardiac glycogen phosphorylase and phosphorylase kinase in streptozotocin-induced chronic diabetic rats.

Supersensitivity to isoproterenol (ISO) induced activation of cardiac phosphorylase in diabetic rat heart has been previously demonstrated and was also reproduced in this study. To explore further the nature of this supersensitivity, we examined the activity of phosphorylase kinase and the level of cyclic AMP (cAMP) in this tissue. We observed a significantly enhanced activation of phosphorylase kinase but no increase in cAMP levels in response to ISO stimulation in diabetic rat heart, suggesting that the supersensitivity of phosphorylase activation in diabetic heart may result from an enhanced activation of phosphorylase kinase that does not involve the cAMP pathway. On the other hand, perfusion of diabetic rat heart with verapamil (5 x 10(-8) M) prior to ISO stimulation abolished the enhanced cardiac phosphorylase activation, suggesting a role for calcium in the supersensitivity of phosphorylase activation. Furthermore, treatment of the diabetic rats with an insulin-like compound, vanadyl sulphate, completely abolished the enhanced cardiac phosphorylase activation and restored the increase in ISO-induced cAMP elevation in diabetic heart. The present study has provided further information on the changes of phosphorylase activation in the diabetic rat heart and demonstrated beneficial effects of vanadyl sulphate on the pathway leading to phosphorylase activation in diabetic rat heart.

Animals↗

Effects of gonadectomy on sexually dimorphic antidiuretic action of vasopressin in conscious rats.

The present study examined whether the antidiuretic response to vasopressin is affected by the estrous cycle and by gonadectomy in conscious, chronically instrumented hydrated rats. Infusion of vasopressin (10-100 pg.min-1.kg body wt-1) resulted in a dose-dependent antidiuresis. Urine volume and free water clearance decreased and urinary osmolality increased with no significant changes in mean arterial blood pressure, heart rate, osmolar clearance, and urinary sodium and potassium excretion. The antidiuretic response to vasopressin was significantly greater in intact male and estrous female rats than in intact female rats in the other phases of the estrous cycle. Thus the calculated doses of vasopressin to reduce urine flow and free water clearance, as well as to increase urinary osmolality 50% from their control values, were significantly higher in nonestrous females than in males and estrous females. Gonadectomy was without effect on the antidiuretic potency of vasopressin in males, but in gonadectomized females the antidiuretic response to vasopressin was enhanced to a level similar to that observed in intact males. These data indicate that the antidiuretic activity of vasopressin is affected not only by gender but also by phase of the estrous cycle and that the ovarian hormone(s) may modulate the antidiuretic action of vasopressin.

Animals↗

Increased plasma osmolality stimulates peripheral and central vasopressin release in male and female rats.

It has been demonstrated that the neurohypophysial hormones can be released intrahypothalamically by the paraventricular (PVN) and supraoptic nuclei. The present experiments were undertaken to determine whether a physiological stimulus for vasopressin release, increased plasma osmolality, will stimulate the release of vasopressin by the PVN into the surrounding interstitial fluid, and whether the responses are affected by gender. Intravenous infusion of 2.5 M NaCl for 60 min (0.1 ml.kg-1.min-1) in conscious rats resulted in an increased vasopressin concentration in the dialysate from a microdialysis probe adjacent to the PVN. This response was greater in nonestrous females than in males. On the other hand, the rise in the plasma vasopressin concentration was greater in males than in nonestrous females. Mean arterial blood pressure increased and heart rate decreased, but these responses were not affected by gender. The role of centrally released vasopressin in the control of the peripheral release of vasopressin is conjectural, but both responses may be modulated by the gonadal steroid hormones.

Animals↗

The UCLA population studies of chronic obstructive respiratory disease: XI. Impact of air pollution and smoking on annual change in forced expiratory volume in one second.

We assessed the relative impact of residential exposure to community air pollution and habitual cigarette smoking on lung function by comparing the annualized rate of change in forced expiratory volume in 1 s (FEV1) in current, former, and never-smokers 25 to 59 yr of age residing in three demographically similar areas of the Southern California air basin who had been chronically exposed to (1) moderate levels of photochemical oxidants and very low levels of other pollutants (Lancaster); (2) very high levels of photochemical oxidants, sulfates, and particulate matter (Glendora); and (3) high levels of sulfates, oxides of nitrogen, and probably hydrocarbons (Long Beach), together with moderate levels of sulfur dioxide. Of the 621 to 763 nonsmokers, 317 to 479 former smokers and 472 to 691 continuing smokers residing in the three areas who were studied initially, 53 to 64, 49 to 59, and 43 to 54%, respectively, were retested. For male residents, area of residence and smoking category each had highly significant effects on FEV1 decline (two-way ANCOVA; p < 0.001) without significant interaction (p > 0.4). After adjustment for baseline FEV1, age, height, and a history of allergy, the mean decline in FEV1 attributable to living in Long Beach compared with living in Lancaster was 23.6 ml/yr, which was 71% of the rate of decline in FEV1 (33.3 ml/yr), attributable to smoking > 1 pack of cigarettes per day. For female residents, a significant interaction was noted between area and smoking (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Significant prolongation of guinea pig heart contraction transplanted in rat after removal of anti-xeno-antibodies by whole body rinse-out (WBRO) with hemoglobin solution.

PURPOSE: In order to investigate effectiveness of removal of the anti-xeno- antibodies in xenotransplantation (xeno Tx), WBRO using pyridoxalated-human hemoglobin-polyethyleneglycol conjugate (PHP solution) was performed prior to transplantation (Tx) of a guinea pig heart in a rat. MATERIALS & METHOD: Experiment I. Removal of the immunoglobulins and the anti-guinea pig lymphocytotoxic antibody (ALA) by WBRO. Exchange transfusion with the PHP solution was done in the Tx-expected rats until a hematocrit lowered below 5% (n = 11). Experiment II. Xeno heart Txs. Guinea pig hearts were transplanted into rats without immunosuppressants 1) without (n = 8) or 2) with the WBRO (n = 8). RESULTS: Experiment I. Levels lowered to 14% in IgG, 17% in IgA and 6% in IgM, respectively, to initial values after the WBRO. An ALA titer lowered from 4 X (+) to 1 X (-) after the WBRO. Experiment II. An average heart contraction period was 10.4 +/- 1.8 minutes 1) without the WBRO in contrast to 472.5 +/- 4.8 minutes with the WBRO (p < 0.01). CONCLUSION: WBRO using PHP solution is effective in removal of the anti-xeno-antibodies and consequent prolongation of survival of the xenograft.

Animals↗

[The study of assessing methods for velopharyngeal function in patients with operated cleft palate]

This paper describes the study and quantitative analysis of velopharyngeal function in 103 patients with operated cleft palate using NPF,vedio-camera system and computer.The percentange of semi-circluar and circular closure patterns after surgery was distinct higher in VPI group than in VPC group,but coronary closure pattern was significant lower in VPI group than in VPC group(P<0.05).We compared the results of different operative age by VPI after surgery.The results showed that postoperative RVPI was in direct proportion to operated age.VPI in the group less than 3 years of age.VPI in the group less than 3 years of age was 28.57%,but in the group of over 7 years of age was 96.43%.Both showed significant difference(P<0.01).

Journal Article↗