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Biomedical subjects

C Peng

Publications and source records attributed to C Peng.

At least 55 records · Page 3Linked to original sources
PubMed1998

Examination of the kinetics of herpes simplex virus glycoprotein D binding to the herpesvirus entry mediator, using surface plasmon resonance.

Previously, we showed that truncated soluble forms of herpes simplex virus (HSV) glycoprotein D (gDt) bound directly to a truncated soluble form of the herpesvirus entry mediator (HveAt, formerly HVEMt), a cellular receptor for HSV. The purpose of the present study was to determine the affinity of gDt for HveAt by surface plasmon resonance and to compare and contrast the kinetics of an expanded panel of gDt variants in binding to HveAt in an effort to better understand the mechanism of receptor binding and virus entry. Both HveAt and gDt are dimers in solution and interact with a 2:1 stoichiometry. With HveAt, gD1(306t) (from the KOS strain of HSV-1) had a dissociation constant (KD) of 3.2 x 10(-6) M and gD2(306t) had a KD of 1.5 x 10(-6) M. The interaction between gDt and HveAt fits a 1:1 Langmuir binding model, i.e., two dimers of HveAt may act as one binding unit to interact with one dimer of gDt as the second binding unit. A gD variant lacking all signals for N-linked oligosaccharides had an affinity for HveAt similar to that of gD1(306t). A variant lacking the bond from cysteine 1 to cysteine 5 had an affinity for HveAt that did not differ from that of the wild type. However, variants with double cysteine mutations that eliminated either of the other two disulfide bonds showed decreased affinity for HveAt. This result suggests that two of the three disulfide bonds of gD are important for receptor binding. Four nonfunctional gDt variants, each representing one functional domain of gD, were also studied. Mutations in functional regions I and II drastically decreased the affinity of gDt for HveAt. Surprisingly, a variant with an insertion in functional region III had a wild-type level of affinity for HveAt, suggesting that this domain may function in virus entry at a step other than receptor binding. A variant with a deletion in functional region IV [gD1(Delta290-299t)] exhibited a 100-fold enhancement in affinity for HveAt (KD = 3.3 x 10(-8) M) due mainly to a 40-fold increase in its kinetic on rate. This agrees with the results of other studies showing the enhanced ability of gD1(Delta290-299t) to block infection. Interestingly, all the variants with decreased affinities for HveAt exhibited decreased kinetic on rates but only minor changes in their kinetic off rates. The results suggest that once the complex between gDt and HveAt forms, its stability is unaffected by a variety of changes in gD.

Animals↗
PubMed1998

Functional region IV of glycoprotein D from herpes simplex virus modulates glycoprotein binding to the herpesvirus entry mediator.

Glycoprotein D (gD) of herpes simplex virus (HSV) is essential for virus entry and has four functional regions (I to IV) important for this process. We previously showed that a truncated form of a functional region IV variant, gD1(Delta290-299t), had an enhanced ability to block virus entry and to bind to the herpesvirus entry mediator (HveAt; formerly HVEMt), a cellular receptor for HSV. To explore this phenotype further, we examined other forms of gD, especially ones with mutations in region IV. Variant proteins with deletions of amino acids between 277 and 300 (region IV), as well as truncated forms lacking C-terminal residues up to amino acid 275 of gD, were able to block HSV entry into Vero cells 1 to 2 logs better than wild-type gD1(306t). In contrast, gD truncated at residue 234 did not block virus entry into Vero cells. Using optical biosensor technology, we recently showed that gD1(Delta290-299t) had a 100-fold-higher affinity for HveAt than gD1(306t) (3.3 x 10(-8) M versus 3.2 x 10(-6) M). Here we found that the affinities of other region IV variants for HveAt were similar to that of gD1(Delta290-299t). Thus, the affinity data follow the same hierarchy as the blocking data. In each case, the higher affinity was due primarily to a faster kon rather than to a slower koff. Therefore, once the gDt-HveAt complex formed, its stability was unaffected by mutations in or near region IV. gD truncated at residue 234 bound to HveAt with a lower affinity (2.0 x 10(-5) M) than did gD1(306t) due to a more rapid koff. These data suggest that residues between 234 and 275 are important for maintaining stability of the gDt-HveAt complex and that functional region IV is important for modulating the binding of gD to HveA. The binding properties of any gD1(234t)-receptor complex could account for the inability of this form of gDt to block HSV infection.

Animals↗
PubMed1998

[The development of medical infusion monitoring and controlling network system].

The paper provided a medical infusion monitoring and controlling network system, in which the mainframe and its extensions can realize communication with each other by means of asynchronous serial port. At the same time, every extension can test infusion speed and adjust it to the presetting infusion speed gradually. The extensions also can alarm and stop infusion automatically when infusion will be over or there is a infusion malfunction.

Computer Communication Networks↗
PubMed1998

[Determination of trace rare earth impurities in the high-purity lanthanum oxide by chemical spectrographic analysis].

The determination of trace rare earth impurities in the high-purity Lanthanum oxide by chemical spectrographic analysis is reported in this paped. The matrix, La2O3, was separated by the extraction-eluating resin P507. The remained rare earth impurities were absorpted by carbon powder. The rare earth impurities absorpted were determinated in carrier KBH4 by spectrographic analysis. The trace rare earth impurities in 99.9999% La2O3 can be determinated by this method.

English Abstract↗
PubMed1997

Antigenic structure of soluble herpes simplex virus (HSV) glycoprotein D correlates with inhibition of HSV infection.

Soluble forms of herpes simplex virus (HSV) glycoprotein D (gD) block viral penetration. Likewise, most HSV strains are sensitive to gD-mediated interference by cells expressing gD. The mechanism of both forms of gD-mediated inhibition is thought to be at the receptor level. We analyzed the ability of different forms of soluble, truncated gD (gDt) to inhibit infection by different strains of HSV-1 and HSV-2. Strains that were resistant to gD-mediated interference were also resistant to inhibition by gDt, thereby suggesting a link between these two phenomena. Virion gD was the major viral determinant for resistance to inhibition by gDt. An insertion-deletion mutant, gD-1(delta 290-299t), had an enhanced inhibitory activity against most strains tested. The structure and function of gDt proteins derived from the inhibition-resistant viruses rid1 and ANG were analyzed. gD-1(ridlt) and gD-1(ANGt) had a potent inhibitory effect on plaque formation by wild-type strains of HSV but, surprisingly, little or no effect on their parental strains. As measured by quantitative enzyme-linked immunosorbent assay with a diverse panel of monoclonal antibodies, the antigenic structures of gD-1(rid1t) and gD-1(ANGt) were divergent from that of the wild type yet were similar to each other and to that of gD-1 (delta 290-299t). Thus, three different forms of gD have common antigenic changes that correlate with enhanced inhibitory activity against HSV. We conclude that inhibition of HSV infectivity by soluble gD is influenced by the antigenic conformation of the blocking gDt as well as the form of gD in the target virus.

Animals↗
PubMed1997

Glycoprotein D of herpes simplex virus (HSV) binds directly to HVEM, a member of the tumor necrosis factor receptor superfamily and a mediator of HSV entry.

Glycoprotein D (gD) is a structural component of the herpes simplex virus (HSV) envelope which is essential for virus entry into host cells. Chinese hamster ovary (CHO-K1) cells are one of the few cell types which are nonpermissive for the entry of many HSV strains. However, when these cells are transformed with the gene for the herpesvirus entry mediator (HVEM), the resulting cells, CHO-HVEM12, are permissive for many HSV strains, such as HSV-1(KOS). By virtue of its four cysteine-rich pseudorepeats, HVEM is a member of the tumor necrosis factor receptor superfamily of proteins. Recombinant forms of gD and HVEM, gD-1(306t) and HVEM(200t), respectively, were used to demonstrate a specific physical interaction between these two proteins. This interaction was dependent on native gD conformation but independent of its N-linked oligosaccharides, as expected from previous structure-function studies. Recombinant forms of gD derived from HSV-1(KOS)rid1 and HSV-1(ANG) did not bind to HVEM(200t), explaining the inability of these viruses to infect CHO-HVEM12 cells. A variant gD protein, gD-1(delta290-299t), showed enhanced binding to HVEM(200t) relative to the binding of gD-1(306t). Competition studies showed that gD-1(delta290-299t) and gD-1(306t) bound to the same region of HVEM(200t), suggesting that the differences in binding to HVEM are due to differences in affinity. These differences were also reflected in the ability of gD-1(delta290-299t) but not gD-1(306t) to block HSV type 1 infection of CHO-HVEM12 cells. By gel filtration chromatography, the complex between gD-1(delta290-299t) and HVEM(200t) had a molecular mass of 113 kDa and a molar ratio of 1:2. We conclude that HVEM interacts directly with gD, suggesting that HVEM is a receptor for virion gD and that the interaction between these proteins is a step in HSV entry into HVEM-expressing cells.

Animals↗
PubMed1997

[An instrument for estimating human body composition using impedance measurement].

According to the impedance feature of biological tissue, the instrument was designed at 1, 5, 10, 50, 100kHz to measure human impedance, and then to calculate human FAT, FFM, FAT%, TBW, ECW, ICW and so on. A 8031 singlechip microprocessor contacuting used as a control center in the instrument. The part of electric circuit contacuting human body in the instrument was unreally earthing. The instrument was safty, effective, repeatable, and easily manpulative. Prelimintary clinical experiment showed the results measured with the instrument could effectively reflect practical, status of human composition.

Adolescent↗
PubMed1997

[Bioimpedance measurement theory and technology].

Bioimpedance is an electrical character of living tissue, organ, cell or living body. When direct or alternating current of effective value below the exitation threshold passes through the living tissue, bioimpedance can be measured indirectly by voltage. It has been studied both theoretically and experimentally by many researchers. In this paper, the bioimpedance measurement theory and technologies are reviewed.

Body Composition↗
PubMed1996

Characterization and regulation of a mRNA encoding the prostaglandin F2alpha receptor in the rat ovary.

The recent cloning of several cDNAs encoding prostaglandin (PG) receptors has paved the way for a more detailed investigation of the postulated regulatory role of prostaglandins in corpus luteum function. We have utilized the reverse transcription-polymerase chain reaction (RT-PCR) to isolate a mRNA encoding the ovarian PGF(2alpha) (FP) receptor, using oligonucleotides based on the recently cloned mouse cDNA as primers. The 5'-untranslated region of the rat ovarian mRNA was isolated following 5'-RACE (rapid amplification of cDNA ends). The isolated 1526 base-pair sequence, which spans the entire open reading frame, was found 100% identical in the protein coding region to a similar sequence isolated from a rat astrocyte cDNA library, but different in the first 32 nucleotides of the 5'-untranslated region, possibly due to tissue-specific splicing heterogeneity. Using ribonuclease protection assay, a quantitative analysis of FP receptor mRNA levels was performed in corpora lutea excised from adult pseudopregnant rats (Day 8) at different timepoints (0.5-48 h) following the in vivo s.c. regimen of a luteolytic dose of the FP receptor agonist cloprostenol (5 microg). Already 3 h after cloprostenol injection, FP receptor mRNA levels exhibited a pronounced increase to values 4.0-fold higher (P < 0.01) than before injection. At 7 h through 24 h, the amount of luteal FP receptor mRNA decreased, approaching preinjection levels, whereafter they were again 3.0-fold higher (P < 0.01) at 48 h than before injection. We conclude that following homologous stimulation of the FP receptor, abundance of this mRNA is tissue-specifically regulated in a dynamic pattern, suggestive of an important role for FP receptor-mediated action on gene expression during the demise of corpus luteum function.

Amino Acid Sequence↗
PubMed1996

Immortalization of neuroendocrine pinealocytes from transgenic mice by targeted tumorigenesis using the tryptophan hydroxylase promoter.

Tryptophan hydroxylase (TPH) is the first enzyme in both serotonin and melatonin biosynthesis in neuroendocrine cells of the pineal gland. The lack of immortalized neuroendocrine pineal cell lines has been a major obstacle to the study of the tissue-specific and circadian regulation of TPH gene expression in the pineal gland. Previously, we demonstrated that a 6.1 kb 5' upstream region of the mouse TPH gene directs the restricted expression of a lacZ reporter gene to the pineal gland and the raphe nuclei of transgenic mice. Therefore, to develop TPH-expressing pineal cell lines we first established transgenic mice carrying a construct consisting of 6.1 kb of 5' flanking region fused to the SV40 T-antigen. These animals developed highly invasive pineal tumors and died at 12-15 weeks of age. The pineal tumors obtained from the transgenic mice were utilized to establish the immortalized pinealocyte-derived cell lines. These cells express two marker enzymes, TPH and serotonin N-acetyltransferase (NAT). In pineal gland TPH and NAT expressions have been known to be regulated during circadian cycle. The two established cell lines therefore promise to be a valuable in vitro model system for the study of the rhythmic nature of the pineal function at molecular level in mammal.

Animals↗
PubMed1996

Latex allergy and anaphylaxis in a child undergoing craniofacial surgery.

This case report represents an example of latex anaphylaxis in a child with a history of multiple previous surgeries without any complications. Obviously, the patient had not shown evidence of being sensitized until this particular surgery, where she had multiple sources of latex exposure, e.g., Foley catheter, blood pressure cuff, rubber gloves, and clear adhesive tape. If a more careful history had been taken, the diagnosis of latex allergy might have been suspected, for upon further questioning after surgery, the mother reported multiple incidences of urticarial reactions to rubber gloves and clothes with elastic waist bands. In summary, this case report highlights the importance of a careful history and the need for a high index of suspicion of potential latex allergy in children who acquire sensitization to latex because they require multiple surgical procedures for anatomic correction of congenital abnormalities. One week after this episode, the patient returned to the operating room for completion of her surgery. All latex was avoided, and there were no complications.

Anaphylaxis↗
PubMed1996

Disulfide bond structure determination and biochemical analysis of glycoprotein C from herpes simplex virus.

A biochemical analysis of glycoprotein C (gC of herpes simplex virus was undertaken to further characterize the structure of the glycoprotein and to determine its disulfide bond arrangement. We used three recombinant forms of gC, gC1(457t), gC1(delta33-123t), and gC2(426t), each truncated prior to the transmembrane region. The proteins were expressed and secreted by using a baculovirus expression system and have been shown to bind to monoclonal antibodies which recognize discontinuous epitopes and to complement component C3b in a dose-dependent manner. We confirmed the N-terminal residues of each mature protein by Edman degradation and confirmed the internal deletion in gC1(delta33-123t). The molecular weight and extent of glycosylation of gC1 (457t), gC1(delta33-123t), and gC2(426t) were determined by treating each protein with endoglycosidases and then subjecting it to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometric analysis. The data indicate that eight to nine of the predicted N-linked oligosaccharide sites on gC1(457t) are occupied by glycans of approximately 1,000 Da. In addition, O-linked oligosaccharides are present on gC1(457t), primarily localized to the N-terminal region (amino acids [aa] 33 to 123) of the protein. gC2(426t) contains N-linked oligosaccharides, but no O-linked oligosaccharides were detected. To determine the disulfide bond arrangement of the eight cysteines of gC1(457t),the protein was cleaved with cyanogen bromide. SDS-PAGE analysis followed by Edman degradation identified three cysteine-containing fragments which are not connected by disulfide linkages. Chemical modification of cysteines combined with matrix-assisted laser desorption ionization mass spectrometry identified disulfide bonds between cysteine 1 (aa 127) and cysteine 2 (aa 144) and between cysteine 3 (aa 286) and cysteine 4 (aa 347). Further proteolysis of the cyanogen bromide-generated fragment containing cysteine 5 through cysteine 8, combined with mass spectrometry and Edman degradation, showed that disulfide bonds link cysteine 5 (aa 386) to cysteine 8 (aa 442) and cysteine 6 (aa 390) to cysteine 7 (aa 419). A similar disulfide bond arrangement is postulated to exist in gC homologs from other herpesviruses.

Amino Acid Sequence↗
PubMed1996

[Sternocleidomastoid muscle lengthening for the cure of muscular torticollis].

A Z-plasty was designed to lengthen the sternocleidomastoid muscle for the treatment of muscular torticollis. Since September 1990, forty-nine patients (36 males, 13 females) have been treated. Their age ranged from 2 to 22 years old. Follow-up of there months to three years showed 95.9% of them were good results. The paper not only described the operative procedure, indications, choice of anaesthesia. postoperative functional exercise and the application of neck splint, but also emphasized the aesthetic effect to the operation.

Adolescent↗
PubMed1995

Mouse model for Usher syndrome: linkage mapping suggests homology to Usher type I reported at human chromosome 11p15.

Usher syndrome is a group of diseases with autosomal recessive inheritance, congenital hearing loss, and the development of retinitis pigmentosa, a progressive retinal degeneration characterized by night blindness and visual field loss over several decades. The causes of Usher syndrome are unknown and no animal models have been available for study. Four human gene sites have been reported, suggesting at least four separate forms of Usher syndrome. We report a mouse model of type I Usher syndrome, rd5, whose linkage on mouse chromosome 7 to Hbb and tub has homology to human Usher I reported on human chromosome 11p15. The electroretinogram in homozygous rd5/rd5 mouse is never normal with reduced amplitudes that extinguish by 6 months. Auditory-evoked response testing demonstrates increased hearing thresholds more than control at 3 weeks of about 30 decibels (dB) that worsen to about 45 dB by 6 months.

Animals↗