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Biomedical subjects

J Liao

Publications and source records attributed to J Liao.

At least 109 records · Page 6Linked to original sources
PubMed1997

[Determination of changes in membrane phospholipids of rat lung and liver tissues from acute heat stress by high performance liquid chromatography].

The changes in the contents of phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC) in lung and liver membrane tissues of rats suffered from acute heat stress were investigated with HPLC. The separation was performed on a mu-Porasil Si column, 300 mm x 3.9 mm i.d., by isocratic elution of acetonitrile : methanol : 85% phosphoric acid (100 : 3 : 1). The phospholipids were detected at 205 nm. The results showed that the contents (mean +/- SD) of PI, PS, PE and PC in normal rats liver were 270.0 +/- 18.2 microg/g, 133.7 +/- 8.6 microg/g, 1465 +/- 132 microg/g and 53.7 +/- 2.8 mg/g respectively, whereas those in heat-stressed rats whose rectal temperature was increased to 42 degrees C and maintained for 15 minutes were decreased by 14%-25% (P<0.01) except PS. When the heat-stressed rats recovered to room temperature for 4h, the contents of phospholipids returned to normal level. The changes of PS and PC in rat lung tissues were identical with those in liver tissues.

Animals↗
PubMed1997

[Reversed-phase high performance liquid chromatographic analysis of the unfolding procedure of bovine insulin].

A method for measurement of the dynamic unfolding procedure of bovine insulin by reversed-phase HPLC has been established. Insulin contains 51 amino acids and two intrachain disulfide bridges. The denaturation of bovine insulin was carried in dithiothreitol solution at 100 degrees C, and the equilibrium products were examined by HPLC at different reaction time. The results show that the conformation of insulin has changed before cleavage of the disulfide bonds to A and B chains. Bovine insulin, two intermediates and the reduction products A and B chains were well separated on a C18 column (4.6 mm x 150 mm) with a linear gradient elution of acetonitrile containing 0.1% trifluoroacetic acid. The conformation of the unfolding intermediates of insulin was indicated by chromatographic method, and the results were verified by matrix-assisted laser desorption ionization time of flight mass spectrometry. The method is helpful to reveal the conformation changes in the procedures of protein unfolding.

Animals↗
PubMed1996

Determination of benflumetol in human plasma by reversed-phase high-performance liquid chromatography with ultraviolet detection.

A reversed-phase high-performance liquid chromatographic method for the determination of benflumetol in human plasma is described. Benflumetol in plasma samples was extracted with a glacial acetic acid-ethyl acetate (1:100, v/v) mixture at pH 4.0. Chromatography was performed on a Spherisorb C18 column using a methanol-water-glacial acetic acid-diethyl amine (93:6:1:0.03, v/v) mixture as the mobile phase and UV-VIS detection at 335 nm. The identity and purity of the benflumetol peak were carefully examined, and the internal standard method was applied for its quantitation. The absolute recovery of benflumetol in spiked plasma samples was 92.91% over the concentration range 5-4000 ng/ml. The recovery of internal standard "8212" at a concentration of 300 ng/ml in spiked plasma was 84.85%. The detection limit of benflumetol was 11.8 ng/ml. Plasma concentration-time profiles in healthy volunteer adults were measured after a single-dose oral administration of 500 mg of benflumetol. The assay procedures were within the quality control limits.

Acetic Acid↗
PubMed1996

Implications of intermediate filament protein phosphorylation.

Intermediate filament (IF) proteins, a large family of tissue specific proteins, undergo several posttranslational modifications, with phosphorylation being the most studied modification. IF protein phosphorylation is highly dynamic and involves the head and/or tail domains of these proteins, which are the domains that impart most of the structural heterogeneity and hence presumed tissue specific functions. Although the function of IF proteins remains poorly understood, several regulatory roles for IF protein phosphorylation have been identified or are emerging. Those roles include filament disassembly and reorganization, solubility, localization within specific cellular domains, association with other cytoplasmic or membrane associated proteins, protection against physiologic stress and mediation of tissue-specific functions. Understanding the mechanistic and functional aspects of IF protein phosphorylation is providing insights not only regarding the function of this modification, but also regarding the function of IF proteins.

Animals↗
PubMed1996

14-3-3 proteins associate with phosphorylated simple epithelial keratins during cell cycle progression and act as a solubility cofactor.

14-3-3 is a ubiquitous protein family that interacts with several signal transduction kinases. We show that 14-3-3 proteins associate with keratin intermediate filament polypeptides 8 and 18 (K8/18) that are expressed in simple-type epithelia. The association is stoichiometrically significant (> or = one 14-3-3 molecule/keratin tetramer), occurs preferentially with K18, and is phosphorylation- and cell cycle-dependent in that it occurs during S/G2/M phases of the cell cycle when keratins become hyperphosphorylated. Binding of phospho-K8/18 to 14-3-3 can be reconstituted in vitro using recombinant 14-3-3 or using total cellular cytosol. Phosphatase treatment results in dissociation of 14-3-3, and dephosphorylation of phospho-K8/18 prevents reconstitution of the binding. Three cellular keratin subpopulations were analyzed that showed parallel gradients of keratin phosphorylation and 14-3-3 binding. Incubation of 14-3-3 with keratins during or after in vitro filament assembly results in sequestering of additional soluble keratin, only in cases when the keratins were hyperphosphorylated. Our results demonstrate a stoichiometrically significant cell cycle- and phosphorylation-regulated binding of 14-3-3 proteins to K18 and in vitro evidence of a simple epithelial keratin sequestering role for 14-3-3 proteins.

14-3-3 Proteins↗
PubMed1996

Enhancement of antiproliferative activity of gamma interferon by the specific inhibition of tyrosine dephosphorylation of Stat1.

Gamma interferon (IFN-gamma) signals to the nucleus through the activation, by tyrosine phosphorylation, of the latent cytoplasmic transcription factor Stat1 (signal transducer and activator of transcription). It has been demonstrated that the activity of Stat1 is dependent on tyrosine phosphorylation which is regulated by Jak tyrosine kinases as well as by the as-yet-unidentified protein tyrosine phosphatase. We report that the N-terminal domain of Stat1, which is highly conserved among all STAT family members, is required for its tyrosine dephosphorylation. A single amino acid substitution (Arg-31 to Ala) in the Stat1 N-terminal domain inhibited Stat1 tyrosine dephosphorylation. The deletion of the Stat1 N-terminal domain resulted in a mutant Stat1 protein which was constitutively phosphorylated on Tyr-701. Upon IFN-gamma stimulation, the tyrosine phosphorylation of this mutant protein was further enhanced but was not down-regulated by protein tyrosine phosphatase in vivo. When expressed in NIH 3T3 cells, this mutant protein greatly enhanced the antiproliferative activity of IFN-gamma. We suggest that the N-terminal domains of STATs are crucial for modulating STAT activities through regulating the tyrosine dephosphorylation of STATs.

3T3 Cells↗
PubMed1996

[Experimental study on zhuanggu shengbao in preventing hormone-induced osteoporosis of rats].

Twenty four male Sprague-Dawley rats at 3 months of age were divided randomly into 3 groups. Prednisone acetate was given to the group B twice per weeks, Zhuanggu Shengbao (ZGSB) was added to the group C besides prednisone, the group A was control. The histomorphometric parameters of bone slides of proximal tibia were measured and calculated with image pattern analyser after 3 months of medication. Results showed that in comparing with group A, in group B the area and number of trabecula decreased, the intertrabecular space increased due to the bone resorption exceeded the bone formation, and the symptoms of osteoporosis revealed obviously. However, in group C, the bone resorption rate was markedly inhibited, and the formation of new bone accelerated so that the bone mass increased significantly. These results indicated the ZGSB could prevent the osteoporosis induced by prednisone acetate.

Animals↗
PubMed1996

p-Hydroxybenzyl alcohol attenuates learning deficits in the inhibitory avoidance task: involvement of serotonergic and dopaminergic systems.

p-Hydroxybenzyl alcohol (HBA), an aglycone of gastrodin, is an active ingredient of Gastrodia elata BLUME. In this study, we investigated the action of HBA on acquisition of an inhibitory avoidance response in rats and used piracetam as a positive control. The results indicated that scopolamine, a cholinergic receptor antagonist, injected before training impaired retention. HBA did not attenuate the scopolamine-induced impairment, but piracetam did. p-Chloroamphetamine, a serotonin releaser, injected before training impaired retention. HBA at 5 mg/kg and piracetam at 100 mg/kg could counteract the p-chloroamphetamine-induced deficit. Apomorphine, a dopaminergic receptor agonist, also impaired retention. HBA at 5 mg/kg and piracetam at 300 mg/kg could ameliorate the apomorphine-induced amnesia. The above results indicated that HBA, different from piracetam, can attenuate impairments induced by p-chloroamphetamine and apomorphine, but had no effect on impairment induced by scopolamine in an inhibitory avoidance task in rats. Such findings suggest that HBA may act through suppressing dopaminergic and serotonergic activities and thus improves learning.

Animals↗
PubMed1996

[Treatment of the deformed ear and jaw].

Lengthening of the mandible by gradual distraction and ear reconstruction using tissue expanders were performed on nine young patients (6-11 years old) with unilateral hemifacial microsomia. The technique holds promise for reconstruction of ear and mandible at the same time. This is essentially a pilot clinical project. A late follow-up of these patients is necessary.

Abnormalities, Multiple↗
PubMed1996

[Applied anatomical study of the lingual nerve].

The lingual nerve and its adjacent structures were observed and measured on 32 adult cadavours. Its length was 69.7 mm and it was divided, bounded by the internal pterygoid muscle, into three segments and the length and diameter of them were respectively measured. According to its relationship with the lingual nerve, the submandibular ganglion can be classified into fusion type (being 46.9%) and free type (being 53.1%), and its superoinferior and transeversal diameters were separately measured to be 2.7 and 2.9 mm. The lingual nerve and its lingual branches were closely related to submandibular duct and there were two intersects. The relation and clinical significance of the third segment of lingual nerve and its neighbor structures were studied.

Adult↗
PubMed1996

[Effect of inhaled nitric oxide on endotoxin induced acute lung injury in rabbit].

OBJECTIVE: In order to observe the effects of inhaling nitric oxide (NO) on acute lung injury (ALI). METHODS: 24 rabbits divided into 4 groups. Six rabbits injured with intravenous E. Coli endotoxin, then followed by treatment of inhaling 80 ppm NO in inspired gas. Before and after the infusion of endotoxin, the mean pulmonary arterial pressure (mPAP), mean systemic arterial pressure (mPSA) and the PaO2 were examined. The venous methemoglobin (MHb) was measured by using spectrophometer colorimitry. The extravasculur lung water was evaluated with rate of dried to wet lung weight at the end of study. RESULTS: The rabbits injured with endotoxin inhaling 80 ppm NO could rapidly reduce the mPAP, increase the PaO2 and without inducing significant change of mPSA, MHb and extravasculur lung water. CONCLUSIONS: Inhalation of 80 ppm NO can selectively cause pulmonary artery dilatation, reduce mPAP, improve pulmonary gas exchange, without producing system vasodilation and toxic effects to the rabbits.

Administration, Inhalation↗
PubMed1996

[Transseptal re-operation for recurrent pituitary adenoma].

To summarize the suitable approach for recurrent pituitary adenoma, fifteen patients with recurrent pituitary adenoma were re-operated via the transseptal sphenoid approach for the second time. During the operation, some degree of adhesion was noted in septal mucous membrane. The sphenoid cavity was filled with fibrous tissue which has correlated to the methods of reconstructing sellar floor during the previous operation. Follow-up study showed satisfactory results. It showed that transseptal sphenoid re-operation is still the best approach for treating recurrent pituitary adenoma in spite of some degree of operative difficulties.

Adenoma↗
PubMed1995

Position-independent expression of whey acidic protein transgenes.

The expression of a 3-kilobase genomic rat whey acidic protein (WAP) clone (-949/+2020) in transgenic mice has been demonstrated previously to be copy number-dependent and independent of the site of integration (Dale, T., Krnacik, M. J., Schmidhauser, C., Yang, C. Q.-L., Bissell, M. J., and Rosen, J. M. (1992) Mol. Cell. Biol. 12, 905-914). The present study demonstrated that position-independent expression of the rat WAP -949/+2020 transgene was dependent on transgene spacing. Position-independent expression also was inhibited by an internal replacement of 49 base pair within the conserved GC-rich 3'-untranslated region (3'-UTR) with an identically sized nonspecific DNA sequence. Using electrophoretic mobility shift assays, nuclear factors isolated from mouse and human cells were shown to associate specifically with the rWAP 3'-UTR DNA, but not with the 3'-UTR containing the internal replacement or specific point mutations. Since a single copy of the 3'-UTR inserted 5' of the promoter could not rescue the 3'-UTR deletion, the 3'-UTR element does not appear to be functioning as either a classic enhancer or insulator element. However, the level of expression of rWAP transgenes was correlated with transgene association with the chromosomal scaffold in vivo.

Animals↗
PubMed1995

The 70-kDa heat shock proteins associate with glandular intermediate filaments in an ATP-dependent manner.

Keratin polypeptides 8 and 18 (K8/18) are intermediate filament proteins expressed preferentially in glandular epithelia. We describe the identification, by co-immunoprecipitation from normal human colonic tissues and cultured cell lines, of the 70-kDa heat shock protein (hsp) and its related heat shock cognate protein as K8/18-associated proteins (hsp/c). The association is significant but sub-stoichiometric and occurs preferentially with the soluble rather than the cytoskeletal K8/18 fractions. Heat stress increases the level of soluble K8/18 in association with an increase in hsp70 levels and an increase in the stoichiometry of K8/18-hsp70 association. Identity of the associated proteins was confirmed by microsequencing of a tryptic digest of the purified associated protein and by using anti-hsp/c70-specific antibodies. The K8/18-hsp/c70 complex can be dissociated in a Mg-ATP-dependent manner that requires ATP hydrolysis. Binding of hsp to K8/18 can be reconstituted using purified bovine hsp70 and human K8/18 immunoprecipitates that have been depleted of bound hsp/c70 and increases slightly in the presence of ATP. The reconstituted K8/18-hsp70 complex can be again released in the presence of Mg-ATP. In addition, hsp70 binds to K8/18 without having a significant effect on in vitro filament assembly when added during or after assembly. Using an overlay assay, hsp70 binds exclusively to K8 in the presence of ATP. Our results show direct association of the hsp/c70 proteins with K8/18. This interaction may serve, at least in part, to regulate the function of these two abundant protein groups.

Adenosine Triphosphate↗
PubMed1995

Empigen BB: a useful detergent for solubilization and biochemical analysis of keratins.

Intermediate filament (IF) proteins make up some of the most insoluble proteins known, and within the IF protein family, keratins are the least soluble. We compared the efficiency of nonionic, cationic, mixed nonionic and anionic, and zwitterionic detergents in solubilizing keratins from insect cells that express recombinant human keratins and from human colonic cell lines and normal keratinocytes. The cationic detergent cetyltrimethylammonium bromide was similar to the zwitterionic detergent Empigen BB in its ability to efficiently solubilize keratins, but the latter detergent was superior in that it maintained antibody reactivity and allowed for immunoprecipitation of the keratins. Although Nonidet-P40 partially solubilizes keratins, Empigen BB solubilizes a significant amount of keratins not solubilized by Nonidet-P40. In the case of vimentin, differences in solubilization efficiency among the detergents was not as dramatic as with keratins. Our results show that Empigen BB solubilizes a significant amount of epidermal and glandular keratins while preserving antigenicity. This detergent should prove useful for carrying out biochemical and molecular studies on these proteins and may be similarly beneficial for other IF proteins.

Blotting, Western↗