Biomedical subjects

P Yao

Publications and source records attributed to P Yao.

11 recordsLinked to original sources

PubMed1998

Anti-aging effects of Bao-Chun-Wan on rats: a morphological ultrastructure study.

Bao-Chun-Wan, a Chinese prescription, is formulated according to the principle of tonifying the kidney for treatment of aging. Morphological study on the ultrastructure of laboratory albino rats treated with this formula showed an increase in thymic lymphocytes, which play an important role in the production of T cells. As to the liver cells, the formula has a protective effect and may induce enzymes enhancing oxidation and excretion of toxic substances. An increase in the Leydig's cell, which promotes reproductive hormone secretion, was also observed, but there was no obvious change in germinal cells. The above findings reported in this article have not been cited in any previous studies and are suggesting that the kidney tonifying formula may act through the mechanism of promoting body immune function, metabolism and biotransformation, and, therefore, result in anti-aging.

Aging↗

PubMed1997

Importance of a conserved phenylalanine-35 of cytochrome b5 to the protein's stability and redox potential.

Phenylalanine-35, which is a residue of the hydrophobic patch on the surface of cytochrome b5, has been mutated into Tyr35, His35 and Leu35 to elucidate the functions of the Phe35 and give further insight into the roles of the hydrophobic patch and/or aromatic network. The effects of these mutations on the heme environment, denaturation towards heating and the denaturant urea, redox potential and stability of protein were studied. The relative stability of cytochrome b5 and its mutants towards heating has the order Phe35Tyr > wild type > Phe35Leu > Phe35His in the oxidized state and wild type > Phe35Tyr > Phe35Leu > Phe35His in the reduced state. All the mutants exhibit decreased reduction potentials: Phe35Tyr -66 mV, Phe35His -51 mV and Phe35Leu -28 mV, which are more negative than that of the wild type. The order of redox potential reflects the relative stability in the oxidized and reduced states. A method of producing multiple mutants at a single site of a gene is also described for the first time.

Amino Acid Sequence↗

PubMed1996

Methyltransferase-specific domains within VP-39, a bifunctional protein that participates in the modification of both mRNA ends.

VP39 is a bifunctional vaccinia virus protein that acts as both a cap- dependent 2'-O-Methyltransferase and a poly(A) polymerase processivity factor. An analysis of C-terminal truncation mutants of a GST-VP39 fusion protein indicated the presence of a protease-sensitive C-terminal "tail" 36-43 amino acids in length that is non-essential for VP39 function. Fourteen new VP39 pointmutants, containing either single or multiple-clustered amino acid substitutions, were expressed in Escherichia coli. Of the eight that retained either one or both of the activities of VP39, seven were specifically methyltransferase-defective. None was specifically defective in adenylyltransferase stimulation. The nature of the methyltransferase defects in 10 of the methyltransferase-specific defectives, identified both herein and in a previous study (Schnierle BS, Gershon PD, Moss B, 1994, J biol Chem 269:20700-20706), was investigated using two novel substrate-binding assays. Three of the mutants (and possible a fourth), whose lesions were juxtaposed and centrally located within VP39, exhibited anomalous S-adenosyl-(L)-methionine (AdoMet) binding behavior, identifying residues important for AdoMet binding and possible also for catalysis. A surface plasmon resonance-based assay measured the interaction of VP39 with uncapped and 5'-cap 0-terminated oligo(A). A cap 0- dependent association-rate enhancement was observed for wild-type VP39 and 4 of the 10 mutant proteins. Two others were identified as defective in cap binding, and a third as partially defective. The lesions within the latter three mutants were closely apposed, and located toward the N-terminus of VP39. We have thus identified regions of VP39 important for interaction with its two substrates for cap-dependent methyltransferase activity: AdoMet and cap 0.

Amino Acid Sequence↗

PubMed1992

Modulation of dihydropyridine-sensitive gastric mucosal calcium channels by GM1-ganglioside.

1. A dihydropyridine-sensitive calcium channel complex was solubilized from gastric mucosal cell membranes and purified by affinity chromatography on wheat germ agglutinin. 2. The calcium channel complex labeled with [3H]PN200-110, when reconstituted into phosphatidylcholine vesicles, exhibited active 45Ca2+ uptake into intravesicular space as evidenced by La3+ displacement and osmolarity studies. The channel complex responded in a dose-dependent manner to dihydropyridine calcium antagonist, PN200-110, which at 0.5 microM exerted maximal inhibitory effect of 66% in 45Ca2+ uptake. 3. The uptake of 45Ca2+ into vesicle-reconstituted gastric mucosal calcium channel complex was inhibited by GM1-ganglioside. Maximum inhibitory effect was achieved at 10-15 nM GM1, at which point a 74% decrease in 45Ca2+ uptake occurred. Furthermore, GM1 also inhibited dihydropyridine binding to gastric mucosal membranes, indicating the extracellular orientation of calcium channel domains for GM1. 4. The ability of GM1 to modulate the intracellular calcium levels may be an important feature in gastric mucosal protection by this ganglioside.

Animals↗

PubMed1992

GM1-ganglioside regulation of EGF-induced gastric mucosal calcium channel activation.

1. Calcium channels, isolated from gastric epithelial cell membranes when reconstituted into phosphatidylcholine vesicles exhibited active 45Ca2+ uptake as evidenced by a dose dependent response to calcium channel activator, BAY K8644, and antagonist, PN200-110. 2. The channels on epidermal growth factor (EGF) binding in the presence of ATP showed an increase in tyrosine phosphorylation of 55 and 170 kDa calcium channel proteins. Such phosphorylated channels following reconstitution into the vesicles displayed a 48% greater 45Ca2+ uptake than that of the controls. 3. The binding of EGF to calcium channel protein was inhibited by GM1-ganglioside reaching maximum inhibition of 65% at 40 nM GM1. In contrast, calcium channel antagonist, PN200-110, had no effect on EGF binding. 4. The EGF-stimulated calcium channel protein phosphorylation was inhibited by GM1. This inhibitory effect was mainly reflected in the decrease of tyrosine phosphorylation of 55 and 170 kDa proteins. 5. The results suggest the participation of GM1-ganglioside in the regulation of EGF-stimulated gastric mucosal calcium channel activation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1992

Effect of GM1-ganglioside on gastric mucosal epidermal growth factor and platelet-derived growth factor receptor expression.

The effect of intragastric administration of GM1-ganglioside on the expression of gastric mucosal epidermal growth factor (EGF) and platelet derived growth factor (PDGF) receptors was investigated. Gastric mucosal cell membranes were isolated from the stomach of groups of rats, one receiving twice daily for 3 consecutive days a dose of 0.25 mg/100g GM1-ganglioside, and the other only vehicle. Binding assays revealed the presence of both types of receptors, activation of which led to the elevation of tyrosine kinase activity as evidenced by a marked increase in membrane protein tyrosine phosphorylation patterns. The specific receptor binding in the control group was 2.47 fmol/mg protein for EGF and 1.46 fmol/mg protein for PDGF, whereas the respective binding values in the GM1-ganglioside treated group increased by 45% and 38%. The results suggest that GM1-ganglioside is capable of enhancement of gastric mucosal EGF and PDGF receptor activities.

Animals↗

PubMed1991

Prostaglandin E2 receptor of rat submandibular salivary glands.

The binding characteristics of the PGE2 receptor were investigated in membrane preparations from these glands. Specific [3H]PGE2 binding was linear as a function of the membrane protein concentration and reached steady state by 40 min of incubation at 37 degrees C under neutral pH. Scatchard analysis of the binding data produced a curvilinear plot with a Kd of 0.18 nM and Bmax of 1.02 fmol/mg protein for the high-affinity binding sites, and a Kd of 181 nM and Bmax of 5.72 pmol/mg protein for the low-affinity binding sites. A competitive displacement study indicated that the receptor was specific for prostaglandins of the E series. The study is the first to demonstrate the presence of the PGE2 receptor in rat submandibular gland and to provide its biochemical features.

Animals↗

PubMed1990

Characterization of the epidermal growth factor receptor in the gastric mucosa.

The effects of epidermal growth factor (EGF), a potent mitogen involved in mucosal protection, are mediated by specific cellular receptors. Here, we present the characteristics and binding properties of EGF receptors in the gastric mucosa. The studies were conducted using cell membranes isolated by subcellular fractionation of rat stomach mucosal scrapings. Specific binding of [125I]-EGF to the membrane preparations was assessed at room temperature for various periods of time and at different pHs. The results showed that the binding was proportional to the incubation time up to 1 h and was not affected by a pH change between 4.0 and 7.0. Scatchard analysis of the binding data infer the presence of 2 binding sites, one of high affinity (Kd = 1.34 nM, Bmax = 34 fmol/mg protein) and the other of low affinity (Kd = 484 nM, Bmax = 2.29 pmol/mg protein). Cross-linking experiments using disuccinimidyl suberate to link the [125I]-EGF to gastric membranes followed by polyacrylamide gel electrophoresis and autoradiography revealed that the major receptor for EGF was a protein of 170 kilodaltons. When the solubilized membranes were subjected to wheat germ agglutinin affinity chromatography, the purified material was found to act as substrate for EGF-stimulated phosphorylation. The major component which was labeled by the [gamma-32P]-ATP was also found to be a 170-kilodalton protein. The data are the first to provide evidence that the gastric mucosa possesses a functional EGF receptor and describe its binding characteristics.

Animals↗

PubMed1988

Effects of pyrethroid insecticides on subjects engaged in packaging pyrethroids.

A health survey was conducted on 199 workers engaged in dividing and packaging pyrethroids. The subjects were exposed to fenvalerate at 0.012-0.055 mg/m3 and deltamethrin at 0.005-0.012 mg/m3 in the air with simultaneous skin contact for 0.5-4.5 months. Burning sensations and tightness or numbness on the face appeared in two thirds of the subjects and one third had sniffs and sneezes. Abnormal facial sensations, dizziness, fatigue, and miliary red papules on the skin were more evident in summer than in winter. Neither abnormalities in other organs or systems nor symptoms or signs of acute pyrethroid poisoning were found by interviews, examinations, and laboratory tests. There was no significant difference in plasma levels of NA, cAMP, and cGMP between the examined subjects and the control group. The urine concentration of fenvalerate in the study group ranged from 1.02 to 18.6 micrograms/l; deltamethrin in the urine was present in trace amounts.

Adolescent↗

PubMed1985

Chemo-attractant for the garter snake: characterization of vomeronasally-mediated response-eliciting components of earthworm wash--III.

Heating a 0.1 N HCl solution of lyophilized garter snake, Thamnophis sirtalis, chemoattractant obtained from earthworm, Lumbricus terrestris, surface washings, in a boiling water bath, and separation by gel chromatography, gave two fractions, F2, of high molecular weight and containing all the chemoattractant activity, and F4, of low molecular weight. The activity is lost between 15 and 30 min of heating. A similarly treated 0.1 N NaOH solution of lyophilized washings gave no F2 fraction and an F4 fraction in increasing amount. All the chemoattractant activity is lost between 0 and 15 min. Separations were monitored by assays for protein and carbohydrate.

Animals↗

PubMedDate not supplied

Postmortem cryosectioning as an anatomic reference for human brain mapping.

This study examined the densitometric and topographic detail of high resolution 3D digital postmortem cryosectioned brain images. Anatomic image data and histology from cryosectioned human brain were compared to in vivo MRI for the ability to delineate neuroanatomic structure. 3D surface reconstructions in the Talairach and Tournoux atlas ("Co-planar stereotaxic atlas of the human brain", Thieme, New York, 1988) coordinate system enabled morphometric comparisons for a representative sample of neuroanatomic structures. Spatial resolution of cryosection images averaged 200 and 170 microns/pixel for whole head and brain, respectively, and 40 microns/pixel for isolated the brain regions. Anatomic detail was far superior to MRI, particularly in deep subcortical regions such as the basal ganglia and in mesencephalic nuclei and tracts. Digital repositioning in the Talairach coordinate system enabled efficient structure localization and morphometric comparison. Histology from collected tissue sections provided cytologic detail that could be mapped to its approximate 3D context. This approach permits comprehensive morphometric analyses necessary for an anatomic framework to a digital atlas of the human brain.

Aged↗