Search PubMed⌕ Search

Biomedical subjects

R F Wang

Publications and source records attributed to R F Wang.

At least 73 records · Page 4Linked to original sources
PubMed1997

Magnocellular and parvocellular visual pathways are both affected in a macaque monkey model of glaucoma.

PURPOSE: Neurochemical changes in nerve cells were investigated in the lateral geniculate nucleus (LGN) and primary visual cortex of macaque monkeys with experimentally induced glaucoma. METHODS: Glaucomatous damage was induced in one eye of experimental animals by elevation of intraocular pressure following laser burns to the trabecular meshwork. Staining for the metabolic marker cytochrome oxidase, as well as immunolabelling for the neuronal markers synaptophysin and neurofilament proteins, was conducted on sections of the LGN and primary visual cortex. RESULTS: In the LGN, staining for cytochrome oxidase and immunolabelling for synaptophysin were reduced in the parvocellular and magnocellular layers that received input from the glaucomatous eye and neurofilament protein labelling was reduced in the parvocellular layers. Cytochrome oxidase staining demonstrated the presence of denervated ocular dominance columns in layer IVC of the primary visual cortex of experimental animals. CONCLUSIONS: Pre- and post-synaptic neurochemical alterations in the magnocellular and parvocellular visual pathways of the brain are associated with experimentally induced glaucoma in macaque monkeys.

Animals↗
PubMed1997

Examining patients' responses about the effectiveness of five denture adhesive pastes.

In this clinical trial, the authors evaluated the responses of 25 experienced denture wearers in regard to the effectiveness of five denture adhesive pastes. The patients responded to questions about the effect of the pastes on quality and duration of retention as well as on mastication. Subjects were also asked which product they considered to be best. Eighteen (72 percent) of the 25 subjects rated Secure (John O. Butler Co.) denture adhesive paste best overall.

Adhesives↗
PubMed1997

Tumor antigens discovery: perspectives for cancer therapy.

The adoptive transfer of cytotoxic T lymphocytes (CTLs) derived from tumor-infiltrating lymphocytes (TIL) along with interleukin 2 (IL-2) into autologous patients with cancer resulted in the objective regression of tumor, indicating that these CTLs recognized cancer rejection antigens on tumor cells. To understand the molecular basis of T cell-mediated antitumor immunity, several groups started to search for such tumor antigens in melanoma as well as in other types of cancers. This led to the subject I will review in this article. A number of tumor antigens were isolated by the use of cDNA expression systems and biochemical approaches. These tumor antigens could be classified into several categories: tissue-specific differentiation antigens, tumor-specific shared antigens, and tumor-specific unique antigens. However, the majority of tumor antigens identified to date are nonmutated, self proteins. This raises important questions regarding the mechanism of antitumor activity and autoimmune disease. The identification of human tumor rejection antigens provides new opportunities for the development of therapeutic strategies against cancer. This review will summarize the current status and progress toward identifying human tumor antigens and their potential applications to cancer treatment.

Amino Acid Sequence↗
PubMed1996

Identification of TRP-2 as a human tumor antigen recognized by cytotoxic T lymphocytes.

The infusion of TIL586 along with interleukin-2 into the autologous patient with metastatic melanoma resulted in the objective regression of tumor. A gene encoding a tumor antigen recognized by TIL586 was previously isolated and shown to encode gp75 or TRP-1. Here we report that TRP-2 was identified as a second tumor antigen recognized by a HLA-A31-restricted CTL clone derived from the TIL586 cell line. The peptide LLPGGRPYR epitope was subsequently identified from the coding region of TRP-2 based on studies of the recognition of truncated TRP-2 cDNAs and the HLA-A31 binding motif. This epitope peptide was capable of sensitizing target cells for lysis by a CTL clone at 1 nM peptide concentration. Although some modified peptides could be recognized by the CTL clone, none were found to be better recognized by T cells than the parental peptide. Like other melamona differentiation antigens, TRP-2 was only expressed in melanoma, melanocytes, and retina, but not in other human tissues tested.

Amino Acid Sequence↗
PubMed1996

Utilization of an alternative open reading frame of a normal gene in generating a novel human cancer antigen.

Tumor infiltrating lymphocytes (TILs) derived from tumor-bearing patients recognize tumor-associated antigens presented by major histocompatibility complex (MHC) class I molecules. The infusion of TIL586 along with interleukin (IL) 2 into an autologous patient with metastatic melanoma resulted in the objective regression of tumor. A gene encoding a tumor antigen recognized by TIL586 was recently isolated and shown to encode gp75. Here we report that an antigenic peptide, MSLQRQFLR, recognized by TIL586 was not derived from the normal gp75 protein. Instead, this nonamer peptide resulted from translation of an alternative open reading frame of the same gene. Thus, the gp75 gene encodes two completely different polypeptides, gp75 as an antigen recognized by immunoglobulin G antibodies in sera from a patient with cancer, and a 24-amino acid product as a tumor rejection antigen recognized by T cells. This represents the first demonstration that a human tumor rejection antigen can be generated from a normal cellular gene using an open reading frame other than that used to encode the normal protein. These findings revealed a novel mechanism for generating tumor antigens, which may be useful as vaccines to induce tumor-specific cell-mediated immunity against cancer.

Alternative Splicing↗
PubMed1996

Human tumor antigens recognized by T lymphocytes: implications for cancer therapy.

The adoptive transfer of cytotoxic T lymphocytes (CTLs) derived from tumor-infiltrating lymphocytes (TIL) along with interleukin-2 (IL-2) into autologous patients with cancer resulted in the objective regression of tumor, indicating that these CTLs recognized cancer rejection antigens on tumor cells. In the past year, a number of such tumor antigens were isolated by the use of cDNA expression systems and biochemical approaches. The majority of tumor antigens identified to date have been found to be nonmutated, self proteins. This raises important questions regarding the mechanism of antitumor activity and autoimmune disease. Several tumor-specific mutated tumor antigens have also been recently identified, which include cell cyclin-dependent kinase 4 (CDK4) and beta-catenin. For the first time, a novel human cancer antigen was recently found to be generated by the use of an alternative open reading frame of the previously identified tyrosinase-related protein-1 (TRP-1) gene. The identification of human tumor rejection antigens provides new opportunities for the development of therapeutic strategies against cancer. The potential clinical applications of these tumor antigens will be discussed.

Amino Acid Sequence↗
PubMed1996

Color stability: denture base resins processed with the microwave method.

Several quick heat-cured denture base resin systems and microwave processing resins have been introduced to provide easier and faster processing. The microwave processing method is the fastest of the heat-cured processing methods. Conventional acrylic resins processed with the microwave method seem to possess adequate physical properties, and one study indicated that a microwave acrylic resin was reasonably color stable under conditions of accelerated aging, although manufacturers do not recommend using them for microwave processing. The purpose of this study was to evaluate the color stability of seven conventional and one microwave heat-cured denture base materials processed with the microwave method. The samples were subjected to conditions of accelerated aging to test for color stability. The color stability was quantitatively measured and color measurements were made before weathering and at 300, 600, and 900 hours. The mean color change for each sample group was statistically analyzed with polynomial regression to determine the pattern of color change over time. The differences in color change for the acrylic resins were significant for all materials, but the color change for Lucitone Hy-pro was not noticeable on visual examination. The results of this study revealed that color changes occurred after accelerated aging in heat-cured denture base resins and Acron GC microwave acrylic resins processed with the microwave method. Hy-pro and TruTone materials exhibited the least color change; Hy-pro material was the most color stable material.

Acrylic Resins↗
PubMed1996

Phylogenetic analysis of Fusobacterium prausnitzii based upon the 16S rRNA gene sequence and PCR confirmation.

In order to develop a PCR method to detect Fusobacterium prausnitzii in human feces and to clarify the phylogenetic position of this species, its 16S rRNA gene sequence was determined. The sequence described in this paper is different from the 16S rRNA gene sequence is specific for F. prausnitzii, and the results of this assay confirmed that F. prausnitzii is the most common species in human feces. However, a PCR assay based on the original GenBank sequence was negative when it was performed with two strains of F. prausnitzii obtained from the American Type Culture Collection. A phylogenetic tree based on the new 16S rRNA gene sequence was constructed. On this tree F. prausnitzii was not a member of the Fusobacterium group but was closer to some Eubacterium spp. and located between Clostridium "clusters III and IV" (M.D. Collins, P.A. Lawson, A. Willems, J.J. Cordoba, J. Fernandez-Garayzabal, P. Garcia, J. Cai, H. Hippe, and J.A.E. Farrow, Int. J. Syst. Bacteriol. 44:812-826, 1994).

Base Sequence↗
PubMed1996

Reclassification of a polycyclic aromatic hydrocarbon-metabolizing bacterium, Beijerinckia sp. strain B1, as Sphingomonas yanoikuyae by fatty acid analysis, protein pattern analysis, DNA-DNA hybridization, and 16S ribosomal DNA sequencing.

A bacterium isolated from a polluted stream, capable of metabolizing biphenyl, naphthalene, phenanthrene, and higher-molecular-weight polycyclic aromatic hydrocarbons (D. Gibson, V. Mahadevan, D. Jerina, H. Yagi, and H. Yeh, Science 189:295-297, 1975), was previously identified as Beijerinckia sp. strain B1. In this investigation, 16S rRNA gene sequencing, biochemical tests, fatty acid methyl ester analysis, polyacrylamide gel electrophoresis of protein, and DNA-DNA hybridization were used to determine the taxonomic relationship of Beijerinckia sp. strain B1. The sequence of the 16S rRNA gene of B1 was identical to that of Sphingomonas yanoikuyae ATCC 51230T. The biochemical tests, fatty acid analysis, and sodium dodecyl sulfate-polacrylamide gel electrophoresis profile of soluble proteins of strain B1 showed results similar to those of S. yanoikuyae. DNA-DNA hybridization indicated that B1 and S. yanoikuyae ATCC 51230T are 75% homologous at the DNA level. We propose that Beijerinckia sp. strain B1 be reclassified as S. yanoikuyae.

Bacterial Proteins↗
PubMed1996

The Periotest method: implant-supported framework precision of fit evaluation.

PURPOSE: In this study, the Periotest instrument was used to measure the precision of fit between cast high noble-metal frameworks and the supporting implants in a patient-simulation model. Three framework conditions and three implant-location variables were used to evaluate the rigidity of the assembly as measured by the Periotest method. The framework variables were (1) one-piece castings (OPC); (2) sectioned-soldered inaccurate castings (SSIC); and (3) sectioned-soldered accurate castings (SSAC). The implant-location variables were right anterior (RA), center (C), and left anterior (LA). MATERIALS AND METHODS: The patient simulation model used consisted of three self-tapping Branemark implants in a reasonable arch curvature in bovine bone. Three working casts were fabricated from the patient-simulation model using polyvinyl siloxane and tapered impression copings. From the working casts, three sets of three frameworks were fabricated as OPCs, SSICs, and SSACs using type 3 high noble alloy. The SSICs were fabricated with a quantitative misfit of 101.6 microns at the facial surface, between the abutment-to-gold cylinder interface at the C implant location. Periotest value (PTV) measurements were made at the midfacial surface of the frameworks directly above each abutment-to-gold cylinder interface. Three measurements were made for each test condition. The data were analyzed to compare framework condition(s) and implant location(s) using ANOVA and Fisher's Protected Least Significant Difference Comparison Test. RESULTS: The ANOVA showed that significant differences exist between the mean PTV data for framework condition and for implant location (p < .01). Significant differences were shown between the mean PTV data for the SSAC assemblies and the OPC and SSIC assemblies. The SSICs displayed a more positive (+) mean PTV than the OPCs. The OPC assemblies had a more positive mean PTV than the SSAC assemblies. The mean PTV data for the SSAC assemblies had a significantly different PTV (p < .01) than the other two framework condition assemblies. The OPC and the SSIC assemblies had PTVs that were not significantly different. The C implant location was significantly different from the RA and the LA implant locations (p < .01). The RA and the LA implant locations were not significantly different from each other. The C implant location always demonstrated the most positive mean PTV regardless of the framework condition being tested. CONCLUSIONS: The Periotest instrument quantified differences in the precision of fit between three framework conditions. The SSAC assemblies were significantly more rigid than the OPC and SSIC assemblies. The OPC and SSIC assemblies' mean PTVs were not significantly different. The mean PTVs for the C implant location and the RA and LA implant locations were significantly different (p < .01). The mean PTVs of the RA and LA implant locations were not significantly different. The implant-location PTVs followed the same rank order for all three framework conditions. The procedures used to fabricate a more precise fit between the framework and the supporting implants is influenced by the skill of the clinician and technician.

Analysis of Variance↗
PubMed1996

PCR detection and quantitation of predominant anaerobic bacteria in human and animal fecal samples.

PCR procedures based on 16S rRNA gene sequences specific for 12 anaerobic bacteria that predominate in the human intestinal tract were developed and used for quantitative detection of these species in human (adult and baby) feces and animal (rat, mouse, cat, dog, monkey, and rabbit) feces. Fusobacterium prausnitzii, Peptostreptococcus productus, and Clostridium clostridiiforme had high PCR titers (the maximum dilutions for positive PCR results ranged from 10(-3) to 10(-8)) in all of the human and animal fecal samples tested. Bacteroides thetaiotaomicron, Bacteroides vulgatus, and Eubacterium limosum also showed higher PCR titers (10(-2) to 10(-6)) in adult human feces. The other bacteria tested, including Escherichia coli, Bifidobacterium adolescentis, Bifidobacterium longum, Lactobacillus acidophilus, Eubacterium biforme, and Bacteroides distasonis, were either at low PCR titers (less than 10(-2)) or not detected by PCR. The reported PCR procedure including the fecal sample preparation method is simplified and rapid and eliminates the DNA isolation steps.

Adult↗
PubMed1996

Purification of 2,3-dihydroxybiphenyl 1,2-dioxygenase from Pseudomonas putida OU83 and characterization of the gene (bphC).

The 2,3-dihydroxybiphenyl 1,2-dioxygenase (2,3-DBPD) of Pseudomonas putida OU83 was constitutively expressed and purified to apparent homogeneity. The apparent molecular mass of the native enzyme was 256 kDa, and the subunit molecular mass was 32 kDa. The data suggested that 2,3-DBPD was an octamer of identical subunits. The nucleotide sequence of a DNA fragment containing the bphC region was determined. The deduced protein sequence for 2,3-DBPD consisted of 292 amino acid residues, with a calculated molecular mass of 31.9 kDa, which was in agreement with data for the purified 2,3-DBPD. Nucleotide and amino acid sequence analyses of the bphC gene and its product, respectively, revealed that there was a high degree of homology between the OU83 bphC gene and the bphC genes of Pseudomonas cepacia LB400 and Pseudomonas pseudoalcaligenes KF707.

Amino Acid Sequence↗
PubMed1996

Detection of Pasteurella pneumotropica in laboratory mice and rats by polymerase chain reaction.

A 16S rDNA-based polymerase chain reaction (PCR) method specific for Pasteurella pneumotropica was developed. The PCR product, a 395-base pair DNA fragment, was amplified from P. pneumotropica and not from 42 other bacterial species tested, including four other Pasteurella species and Actinobacillus ureae. The PCR method was used to identify 13 previously isolated strains that had been identified as P. pneumotropica by conventional methods: 12 were confirmed by PCR; one that was PCR-negative was re-examined by biochemical methods and determined to be A. ureae. The PCR detection of P. pneumotropica in nasopharyngeal swab specimens from 121 surveillance animals (15 inbred mice and 5 inbred rats from 20 animal rooms) had a high carrier state in healthy laboratory animals; for example, rat swab specimens were 89.6% (43/48) positive by PCR, 8.3% were positive by the direct culture-biochemical method, and 16.7% were positive by the enrichment culture-biochemical method. The positive rate for mice (21.9% [16/73]) was lower than that for rats.

Animals↗
PubMed1995

Phylogenetic analysis of polycyclic aromatic hydrocarbon degrading mycobacteria by 16S rRNA sequencing.

Mycobacterium sp. PYR-1 was previously isolated in our laboratory and was shown to be able to mineralize high molecular mass polycyclic aromatic hydrocarbons (PAHs) [Heitkamp and Cerniglia, (1988) Appl. Environ. Microbiol. 54, 1612-1614]. In this research, the 16S rRNA gene (rDNA) of this strain was amplified by polymerase chain reaction (PCR) and directly sequenced by cycle sequencing method. We compared this sequence with all known mycobacterial 16S rDNA sequences available from GenBank and found that Mycobacterium sp. PYR-1 16S rDNA differs from the other mycobacteria, especially in the region of nucleotides 168-200 (in the Escherichia coli numbering system). Using the 16S rDNA sequences of the mycobacteria, a phylogenetic tree was constructed. The data from the phylogenetic tree and similarity values suggest that Mycobacterium sp. PYR-1 is closer to M. aurum and M. vaccae. Using the same approach, we also determined the 16S rDNA from an another PAH-degrading Mycobacterium sp. PAH135, isolated by Grosser and colleagues (1991) (Appl. Environ. Microbiol. 57, 3462-3469). Mycobacterium sp. PAH135 was found to be closer to M. aichiense, and different from our Mycobacterium sp. PYR-1.

Base Sequence↗
PubMed1995

Differential vulnerability of neurochemically identified subpopulations of retinal neurons in a monkey model of glaucoma.

The vulnerability of subpopulations of retinal neurons delineated by their content of cytoskeletal or calcium-binding proteins was evaluated in the retinas of cynomolgus monkeys in which glaucoma was produced with an argon laser. We quantitatively compared the number of neurons containing either neurofilament (NF) protein, parvalbumin, calbindin or calretinin immunoreactivity in central and peripheral portions of the nasal and temporal quadrants of the retina from glaucomatous and fellow non-glaucomatous eyes. There was no significant difference between the proportion of amacrine, horizontal and bipolar cells labeled with antibodies to the calcium-binding proteins comparing the two eyes. NF triplet immunoreactivity was present in a subpopulation of retinal ganglion cells, many of which, but not all, likely correspond to large ganglion cells that subserve the magnocellular visual pathway. Loss of NF protein-containing retinal ganglion cells was widespread throughout the central (59-77% loss) and peripheral (96-97%) nasal and temporal quadrants and was associated with the loss of NF-immunoreactive optic nerve fibers in the glaucomatous eyes. Comparison of counts of NF-immunoreactive neurons with total cell loss evaluated by Nissl staining indicated that NF protein-immunoreactive cells represent a large proportion of the cells that degenerate in the glaucomatous eyes, particularly in the peripheral regions of the retina. Such data may be useful in determining the cellular basis for sensitivity to this pathologic process and may also be helpful in the design of diagnostic tests that may be sensitive to the loss of the subset of NF-immunoreactive ganglion cells.

Animals↗
PubMed1995

Mammalian cell/vaccinia virus expression vectors with increased stability of retroviral sequences in Escherichia coli: production of feline immunodeficiency virus envelope protein.

Many eukaryotic DNA sequences, especially lenti-retrovirus proviral genomes and their env genes, are unstable when cloned in high-copy-number plasmids in Escherichia coli. Stability can be increased by the use of low-copy-number vectors, although plasmid yields are low. Vectors are described here that contain the intermediate-copy-number P15A ori for cloning, stable propagation and higher-yield production of plasmid DNA in E. coli, and the f1 ori for propagation as single-stranded phage. These vectors also have the capacity to direct high-yield production of protein in mammalian cells, and the option of incorporation into and expression via a T7 promoter in vaccinia virus. The SR alpha promoter, encephalomyocarditis (EMC) virus untranslated leader sequence, and poly(A) signal sequence serve as a high-yield mammalian cell expression cassette without the requirement for mRNA capping. A polyhistidine sequence is available at the 3' end of the cassette to facilitate chromatographic purification of protein. neo and gpt genes were included in some vectors to serve as selectable markers, and the dhfr gene was included in one to achieve gene amplification in mammalian cells. Dicistronic mRNAs can be generated by insertion of coding sequences up and downstream from the EMC leader. The utility of these vectors was shown through expression of feline immunodeficiency virus (FIV) Env protein, in conjunction with the tissue plasminogen activator (tPA) leader sequence.

Animals↗
PubMed1995

Identification of a gene encoding a melanoma tumor antigen recognized by HLA-A31-restricted tumor-infiltrating lymphocytes.

The availability of antitumor cytotoxic T lymphocytes which can be generated from either peripheral blood lymphocytes after stimulation in vitro or tumor infiltrating lymphocytes (TIL) has made it possible to identify a number of melanoma antigens presented by major histocompatibility complex class I molecules. The present and previous studies indicated that TIL586 recognized an antigen expressed on most melanoma and normal melanocytes in the context of the HLA-A31 molecule. We report here the cloning of a cDNA that directs the expression of the shared melanoma antigen recognized by this TIL. The DNA sequence analysis revealed that the cDNA was almost identical to the gene encoding tyrosinase-related protein 1 or glycoprotein gp75 which was originally identified by serum antibodies in a patient with melanoma. The gene was found to be expressed only in melanoma, normal melanocyte cell lines, and retina, but not in other normal tissues tested. The gp75 antigen presented by HLA-A31 may therefore constitute a useful immune target for specific treatment of patients with melanoma, since both antibody- and T cell-mediated immune responses can be generated against this antigen.

Antigens, Neoplasm↗