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L Pei

Publications and source records attributed to L Pei.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Effect of ischemia/reperfusion on the phosphorylation of synaptosomal tyrosine of hippocampus of Mongolian gerbils].

The effects of ischemia/reperfusion on the levels of protein tyrosine phosphorylation in the synaptosome of gerbil hippocampus and the effects of three drugs, ketamine (KT), a noncompetitive antagonist of NMDA receptor, nifedipine (ND), a voltage gated calcium channel (VGCC) antagonist and 6,7-dinitroquinoxaline-2,3-dione (DNQX), a non-NMDA receptor antagonist, on the phosphorylation were studied. The results showed that (1) 15 min of transient forebrain ischemia caused a marked decrease in the level of tyrosine phosphorylation of many protein bands, but, if followed by 15 min to 48 h of reperfusion, many protein bands including the 180 kD protein appeared to be increased; (2) the degree of tyrosine phosphorylation of the protein bands was higher than that of the sham-operated control, e.g. that of 180 kD protein was 1.8 fold of control; (3) administration of KT and ND before ischemia attenuated the increase of 180 kD protein tyrosine phosphorylation, while DNQX had no effect; and (4) immunoprecipitation and Western blot confirmed that the NR2B subunits of the NMDA receptors were among the phosphorylated 180 kD protein and ischemia /reperfusion did not affect the level of protein expression of NR2B. The above results suggest that the increase of tyrosine phosphorylation of NR2B induced by ischemia/reperfusion may further activate NR channels and aggravate neuronal injury, and that NR channels and other protein can be regulated by tyrosine phosphorylation not only through NR channels themselves but also via L-type VGCCs. Consequently, antagonists of both NR channels and L-type VGCCs may play a certain role in prevention and cure of ischemic brain injury.

Animals↗
PubMed1999

Activation of regulatory cells suppresses experimental allergic encephalomyelitis via secretion of IL-10.

Suppression of CD4+ Th1 cell-mediated autoimmune disease via immune deviation is an attractive potential therapeutic approach. CD4+ Th2 T cells specific for myelin basic protein, induced by immunization of young adult male SJL mice, suppress or modify the progression of CNS autoimmune disease. This report demonstrates that activation of non-neuroantigen-specific Th2 cells is sufficient to suppress both clinical and histological experimental allergic encephalomyelitis (EAE). Th2 cells were obtained following immunization of male SJL mice with keyhole limpet hemocyanin. Transfer of these cells did not modify EAE, a model of human multiple sclerosis, in the absence of cognate Ag. Disease suppression was obtained following adoptive transfer and subcutaneous immunization. Suppression was not due to the deletion of myelin basic protein-specific T cells, but resulted from the presence of IL-10 as demonstrated by the inhibition of Th2-mediated EAE suppression via passive transfer with either anti-IL-10 or anti-IL-10R mAb. These data demonstrate that peripheral activation of a CD4+ Th2 population specific for an Ag not expressed in the CNS modifies CNS autoimmune disease via IL-10. These data suggest that either peripheral activation or direct administration of IL-10 may be of benefit in treating Th1-mediated autoimmune diseases.

Adoptive Transfer↗
PubMed1999

Antagonism of paraoxon intoxication by recombinant phosphotriesterase encapsulated within sterically stabilized liposomes.

This investigation effort is focused on increasing organophosphate (OP) degradation by phosphotriesterase to antagonize OP intoxication. For these studies, sterically stabilized liposomes encapsulating recombinant phosphotriesterase were employed. This enzyme was obtained from Flavobacterium sp. and was expressed in Escherichia coli. It has a broad substrate specificity, which includes parathion, paraoxon, soman, sarin, diisopropylfluorophosphate, and other organophosphorous compounds. Paraoxon is rapidly hydrolyzed by phosphotriesterase to the less toxic 4-nitrophenol and diethylphosphate. This enzyme was isolated and purified over 1600-fold and subsequently encapsulated within sterically stabilized liposomes (SL). The properties of this encapsulated phosphotriesterase were investigated. When these liposomes containing phosphotriesterase were incubated with paraoxon, it readily degraded the paraoxon. Hydrolysis of paraoxon did not occur when these sterically stabilized liposomes contained no phosphotriesterase. These sterically stabilized liposomes (SL) containing phosphotriesterases (SL)* were employed as a carrier model to antagonize the toxic effects of paraoxon by hydrolyzing it to the less toxic 4-nitrophenol and diethylphosphate. This enzyme-SL complex (SL)* was administered intravenously to mice either alone or in combination with pralidoxime (2-PAM) and/or atropine intraperitoneally. These results indicate that this carrier model system provides a striking enhanced protective effects against the lethal effects of paraoxon. Moreover when these carrier liposomes were administered with 2-PAM and/or atropine, a dramatic enhanced protection was observed.

Animals↗
PubMed1999

Pituitary tumor-transforming gene protein associates with ribosomal protein S10 and a novel human homologue of DnaJ in testicular cells.

Pituitary tumor-transforming gene (PTTG) is a recently characterized proto-oncogene that is expressed specifically in adult testis. In this study, we have used in situ hybridization and developmental Northern blot assays to demonstrate that PTTG mRNA is expressed stage-specifically in spermatocytes and spermatids during rat spermatogenic cycle. We have used the yeast two-hybrid system to identify proteins that interact with PTTG in testicular cells. Two positive clones were characterized. One of the clones is the ribosomal protein S10, the other encodes a novel human DnaJ homologue designated HSJ2. Northern blot analysis showed that testis contains higher levels of HSJ2 mRNA than other tissues examined, and the expression pattern of HSJ2 mRNA in postnatal rat testis is similar to PTTG. S10 mRNA levels do not vary remarkably among different tissues and remains unchanged during testicular germ cell differentiation. In vitro binding assays demonstrated that both S10 and HSJ2 bind to PTTG specifically and that PTTG can be co-immunoprecipitated with S10 and HSJ2 from transfected cells. Moreover, the binding sites for both proteins were located within the C-terminal 75 amino acids of the PTTG protein. These results suggest that PTTG may play a role in spermatogenesis.

Adult↗
PubMed1999

Functional studies of a fibrinogen binding protein from Staphylococcus epidermidis.

A gene encoding a fibrinogen binding protein from Staphylococcus epidermidis was previously cloned, and the nucleotide sequence was determined. A portion of the gene encompassing the fibrinogen binding domain has now been subcloned in an expression-fusion vector. The fusion protein can bind to fibrinogen in a capture enzyme-linked immunosorbent assay and can be purified by fibrinogen affinity chromatography. This protein can completely inhibit the adherence of S. epidermidis to immobilized fibrinogen, suggesting that the adherence of S. epidermidis to fibrinogen is mainly due to this protein. Antibodies against this fibrinogen binding protein were also found to efficiently block the adherence of S. epidermidis to immobilized fibrinogen. Despite homology with clumping factors A and B from S. aureus (cell surface-associated proteins binding to fibrinogen), binding involved the beta chain of fibrinogen rather than the gamma chain, as in clumping factor A.

Animals↗
PubMed1998

Molecular cloning of a novel transcriptional repressor protein of the rat type 1 vasoactive intestinal peptide receptor gene.

This study demonstrates that the transcriptional repressor sequence of the rat vasoactive intestinal peptide receptor (VIPR) gene constitutes a 42-base pair core element that is the binding site for a nuclear protein. We showed that this element was able to confer transcriptional repression to a heterologous promoter and that deletion or point mutations within this element resulted in loss of transcriptional repression. Southwestern blot analysis indicated that the VIPR repressor element interacts specifically with a nuclear protein of about 72 kDa. By screening a rat lung expression library coupled with rapid amplification of cDNA ends polymerase chain reactions, we isolated a cDNA clone (designated as VIPR-RP) that contains an open reading frame of 656 amino acids. VIPR-RP is 78% identical to a previously characterized protein, differentiation-specific element-binding protein, which is a member of a family of proteins including components of the DNA replication factor C complex. However, VIPR-RP cDNA encodes for a much smaller protein than differentiation-specific element-binding protein because of a frameshift. VIPR-RP mRNA is expressed in multiple tissues, including lung, liver, brain, heart, kidney, spleen, and testis. VIPR-RP protein specifically interacts with the VIPR repressor element as demonstrated by gel shift assays. Transfection of VIP-RP expression vector into Cos cells resulted in transcriptional repression of a reporter construct containing multiple copies of the VIPR repressor element. These results indicate that VIPR-RP is a novel transcriptional repressor protein that regulates VIPR expression.

Amino Acid Sequence↗
PubMed1998

Genomic organization and identification of an enhancer element containing binding sites for multiple proteins in rat pituitary tumor-transforming gene.

The rat pituitary tumor transforming gene (PTTG) genomic structure was characterized in this study. Northern blot analysis showed that PTTG mRNA is highly expressed in testicular cell lines. Transfection of testicular cell lines with fusion constructs containing various portions of PTTG 5'-flanking sequences linked to luciferase showed that at least 745 base-pair (bp(s)) 5'-flanking sequences are required for PTTG transcriptional activation. DNaseI footprinting assays indicated that nuclear protein(s) from testicular cell lines interacts with PTTG 5'-flanking sequence between -509 and -624 bp, including two consensus Sp1 binding sites. Western and Southwestern blot analysis showed that three nuclear proteins in addition to Sp1 protein specifically interact with this DNA sequence and that two of these proteins are testicular cell-specific. Deletion of this 115-bp sequence from PTTG promoter resulted in complete loss of promoter function. Site-directed mutagenesis within the Sp1 consensus sequences indicated that the Sp1 binding sites are not critical components of the enhancer sequence for PTTG trancriptional activation in testicular cell lines. Finally, the 115-bp enhancer sequence was shown to be able to activate transcription from a heterologous promoter. These results suggest that PTTG transcriptional activation in testicular cell lines involves interactions of multiple nuclear factors with the PTTG 5' enhancer sequence.

Animals↗
PubMed1998

A fibrinogen-binding protein of Staphylococcus epidermidis.

The present study reports on fibrinogen (Fg) binding of Staphylococcus epidermidis. Adhesion of different S. epidermidis strains to immobilized Fg was found to vary significantly between different strains, and the component responsible was found to be proteinaceous in nature. To further characterize the Fg-binding activity, a shotgun phage display library covering the S. epidermidis chromosome was constructed. By affinity selection (panning) against immobilized Fg, a phagemid clone, pSEFG1, was isolated, which harbors an insert with an open reading frame of approximately 1.7 kilobases. Results from binding and inhibition experiments demonstrated that the insert of pSEFG1 encodes a specific Fg-binding protein. Furthermore, affinity-purified protein encoded by pSEFG1 completely inhibited adhesion of S. epidermidis to immobilized Fg. By additional cloning and DNA sequence analyses, the complete gene, termed fbe, was found to consist of an open reading frame of 3,276 nucleotides encoding a protein, called Fbe, with a deduced molecular mass of approximately 119 kDa. With a second phage display library made from another clinical isolate of S. epidermidis, it was possible to localize the Fg-binding region to a 331-amino-acid-long fragment. PCR analysis showed that the fbe gene was found in 40 of 43 clinical isolates of S. epidermidis. The overall organization of Fbe resembles those of other extracellular surface proteins of staphylococci and streptococci. Sequence comparisons with earlier known proteins revealed that this protein is related to an Fg-binding protein of Staphylococcus aureus called clumping factor.

Amino Acid Sequence↗
PubMed1998

[Arterial plasma nitric oxide and lactate level in hemorrhagic shock patients].

OBJECTIVE: To investigate the relationship between arterial plasma nitric oxide(NO), lactate (LA) concentration and prognosis of hemorrhagic shock patients. METHODS: The blood levels of a NO and LA were measured with fluoropholometry and colorimetry in 48 hemorrhagic shock patients, and other 30 patients for selective surgery served as controls. RESULTS: NO level was significantly lower and LA level was significantly higher in the hemorrhagic shock group than that of the control group respectively. NO level had a negative correlation with LA level and trauma index. NO level in the patients complicated by sepsis was still lower than that of the control group. CONCLUSION: Decrease of NO level may be a main cause of disturbance of microcirculation and increase of LA. The lower the NO level, the higher the LA level, the worse the prognosis. So NO and LA level play an important role in forecasting progress of hemorrhagic shock patients.

Adolescent↗
PubMed1997

Genomic structure and embryonic expression of the rat type 1 vasoactive intestinal polypeptide receptor gene.

The genomic structure of the rat vasoactive intestinal polypeptide type 1 receptor (VIPR I) gene was characterized using polymerase chain reactions (PCR) and DNA sequencing. These studies show that the rat VIPR I gene spans more than 20 kb of DNA sequence and includes thirteen exons separated by twelve introns, ranging from 0.2 to 4.5 kb. VIP is known to play an important role early in embryonic development. To elucidate the receptor-mediated biological functions of VIP in development, the temporal and spatial expression of VIPR I during rat embryonic development was examined in this study. Using in situ hybridization histochemistry with 35S-labeled riboprobe, VIPR I mRNA was detected as early as embryonic day 11 (E11), in the neuroepithelium, foregut, heart and in cells lining the blood vessels. From E14 through E18, VIPR I mRNA was detected in multiple tissues derived from all three germ layers. These include neuronal cells in brain and spinal cord (ectoderm); smooth muscle cells of intestines, cells lining the wall of the heart and blood vessels, kidney, adrenal gland (mesoderm); epithelial cells of airway and of liver (endoderm). The early onset and wide tissue expression of VIPR I suggests that binding of VIP to this receptor may play an important role in rat embryonic development.

Animals↗
PubMed1997

Considerations for toxicology studies of respiratory drug products.

The standard approaches for the preclinical development of chronically administered drugs also apply to most respiratory drugs. Modifications from the standard preclinical development plan, however, may be necessary if the drug is administered intranasally or by inhalation. Administration by these routes may result in airway toxicity and the intended patient population is often particularly susceptible. Current and former representatives of the Division of Pulmonary Drug Products (CDER, U.S. FDA) present this article to describe general principles of preclinical development for respiratory drug indications. The article addresses drugs intended for administration by the intranasal or inhalation routes. The article describes the types of studies recommended, considers the initial human dose, and discusses dose-escalation strategies in clinical trials. Other areas of special concern with intranasal or inhalation administration include immunotoxicity, reproductive toxicity, types of dosing apparatus, excipients and extractables, and formulation changes. The approaches described in this article are intended as general information and should be adapted to the scientific considerations and circumstances of a particular drug under development.

Humans↗
PubMed1997

Isolation and characterization of a pituitary tumor-transforming gene (PTTG).

Pathogenesis of tumor formation in the anterior pituitary has been intensively studied, but the common mechanism involved in pituitary cell transformation and tumorigenesis remains elusive. In this study, we used mRNA differential display PCR to identify mRNAs that are differentially expressed in rat pituitary tumor cells compared with normal pituitary tissue. An mRNA exclusively expressed in pituitary tumor but not in normal pituitary was characterized. Using this pituitary tumor-specific PCR product as a probe to screen a cDNA library constructed from rat pituitary tumor GH4 cells, a cDNA of 974 bp was isolated. This cDNA encodes a novel protein of 199 amino acids, which contains no well characterized functional motifs. The mRNA of this cDNA is detected in normal adult testis and in embryonic liver, where the transcript is about 300 bp shorter and expressed at a much lower level than that detected from pituitary tumor cells. Overexpression of this protein in mouse 3T3 fibroblasts shows that it inhibits cell proliferation and induces cell transformation in vitro. Injection of transfected 3T3 cells into athymic nude mice resulted in tumor formation within 3 weeks in all animals. These results indicate that pituitary tumor cells express a unique and potent transforming gene (PTTG), which may play a role in pituitary tumorigenesis.

3T3 Cells↗
PubMed1997

[Studies on the mechanism of protection of cultured neurous by ketamine anoxia/reoxygenation-induced injury].

The effects of anoxia/reoxygenation (A/R) and glutamate on cultured cortical neurons from 16 to 18-day-old fetal rats and the protective effect of ketamine were studied. The 12-day cultures of 12 days were exposed to anoxia (5 h) followed by reoxygenation (0-24 h). Following progressive A/R, the release of lactate dehydrogenase (LDH) into the bathing medium obviously increased and exogenous glutamate (3 h) also markedly increased the release of LDH. When the cultures were pretreated with ketamine before A/R, the amounts of LDH efflux in culture medium were significantly less than those of controls. These results demonstrate that the cultured cortical neurons are seriously damaged by A/R and exogenous glutamate. Such damage could be attenuated by ketamine, suggesting that the neurotoxic effect of glutamate and NMDA (N-methyl-D-aspartate) receptors play an important role in the process of ischemia-induced damage in the brain.

Animals↗
PubMed1997

[Studies on mechanism of the inhibition of Ca2+/CaM PKII activity induced by hypoxia in rat hippocampal slices].

The effects of Ca2+ and ketamine on Ca2+/CaM PK II activity in rat hippocampal slices under in vitro hypoxic states have been studied and the effect of hypoxia on glutamate accumulation was also investigated. The results were as follows: (1) Ca2+/CaM PK II activity decreased gradually with increasing hypoxic time in culture medium with or without 1.3 Ca2- mmol/L, with the former case being much more pronounced. (2) Extracellular accumulation of GLU increased about two-fold after hypoxia for 30 min in vitro. (3) When slices were incubated for 30 min under conditions in excess of exogenous GLU the enzyme activity markedly decreased, a finding suggesting that the inhibition of enzyme activity induced by hypoxia may result from excitotoxicity. (4) The inhibition of the enzyme activity induced by either hypoxia or excess exogenous glutamate alone could be antagonized markedly by pretreatment with ketamine, suggesting that the hypoxia induced inhibition of the enzyme activity is mediated by NMDA receptor.

Animals↗
PubMed1997

[Treatment of nerve root avulsion of brachial plexus by nerve transfer].

The results of nerve transposition for root avulsion of brachial plexas in 21 cases were reported. The methods of the nerve transposition were divided into four groups as followings: By transfer of phrenic nerve, accesory nerve, the motor branches of cervical plexus and intercostal nerves in cease; By transfer of phrenic nerve, accessory nerve and the motor branches of cervical plexus in 6 cases; By transfer of phrenic nerve and accessory nerve in 9 cases, and by transfer of phrenic nerve or the motor branches of cervical plexus or intercostal nerve in 5 cases. During operation, in 1 cases variation of the brachial plexus was found. Injury to the subclavian artery occurred in 4 cases and they were repaired, which is good for the blood circulation of the upper arm and nerve regeneration. Nineteen cases were followed up with good results. The overall excellent and good rate was 73.7%. It was considered that transposition of nerve should be a routine operation for the treatment of root avulsion of brachial plexus and the accompanied arterial injury should be repaired at the same time during operation, and the latter would be advantageous to enhance functional recovery of nerve.

Accessory Nerve↗
PubMed1996

Identification of a negative glucocorticoid response element in the rat type 1 vasoactive intestinal polypeptide receptor gene.

Glucocorticoids play important roles in lung development and function by modulating the expression of a variety of genes. The type 1 vasoactive intestinal polypeptide (VIP) receptor gene is highly expressed in the lung where it mediates VIP physiological functions. In this study, the effect of glucocorticoid on VIP receptor gene expression was examined. Dexamethasone (100 n) suppresses endogenous VIP receptor mRNA expression in cultured lung cells. Transient transfection of lung cells with fusion constructs containing various portions of the VIP receptor 5'-flanking sequences linked to the luciferase reporter gene shows that 126 base pairs (bp) of the VIP receptor upstream sequences are sufficient to mediate transcriptional repression by glucocorticoid. DNase I footprinting demonstrates that purified glucocorticoid receptor (GR) binds to the VIP receptor promoter between -21 and -36 bp relative to the transcription start site. Point mutations within this binding site not only abolish GR binding and GR-mediated transcriptional repression of the VIP receptor gene, but basal transcription is also reduced to background levels. Co-transfection of GR expression vector and the VIP receptor GR binding site linked to the thymidine kinase promoter and luciferase shows that this sequence is sufficient to confer glucocorticoid-mediated transcriptional repression to a heterologous promoter. These results indicate that the VIP receptor gene contains a negative glucocorticoid response element between -21 and -36 bp that may act to regulate both basal and glucocorticoid-mediated expressions of the VIP receptor gene in lung cells.

Animals↗
PubMed1996

Remission of acromegaly caused by pituitary carcinoma after surgical excision of growth hormone-secreting metastasis detected by 111-indium pentetreotide scan.

GH-secreting carcinomas of the pituitary are extremely rare. We describe a 37-yr-old woman with refractory acromegaly 15 yr after transphenoidal surgery and radiotherapy, with no evidence of a recurrent pituitary mass. Scanning with 111-indium pentetreotide revealed an area of intense activity in the left neck. A 3.5 x 2.5-cm mass was excised from the neck after demonstrating an arterio-venous GH gradient of 7:1. GH levels (50 ng/mL) dropped to 0.8 ng/mL 3 h after surgery and remained normal. GH gene expression was demonstrated in the metastasis by Northern and Western blot analyses and by positive immunocytochemistry and immunoelectron microscopy. In vitro cultured cells responded to GHRH and TRH by increasing GH levels (P < 0.01). Medium GH was identical to authentic pituitary GH, as demonstrated by high pressure liquid chromatography. RT-PCR of hypothalamic hormone receptor messenger RNA in the mass revealed somatostatin receptor subtypes 2, 3, and 5 and GHRH, TRH, and dopamine receptor expression. No GH gene amplification, rearrangement, or gsp mutation was found. RB gene deletion and H-ras mutations, previously reported in PRL- and ACTH-secreting carcinomas, were not detected. In conclusion, clinical and molecular features of a GH-secreting pituitary carcinoma are presented. This metastatic lesion synthesized GH and expressed functional hypothalamic hormone receptors.

Acromegaly↗