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Biomedical subjects

J E Strong

Publications and source records attributed to J E Strong.

At least 19 recordsLinked to original sources
PubMed2005

Laboratory diagnosis of Ebola and Marburg hemorrhagic fever.

The control of Filovirus outbreaks can be greatly enhanced by timely laboratory confirmation of infection or the identification of alternative disease processes. The status of current laboratory diagnostics for Ebola and Marburg virus infections is discussed in terms of the assays available and their interpretation. In addition, the role of field-based laboratory support and its limitations and capabilities in an outbreak response setting, especially in regards to real-time PCR and immunofiltration assays, is presented.

Animals↗
PubMed1998

Reovirus therapy of tumors with activated Ras pathway.

Human reovirus requires an activated Ras signaling pathway for infection of cultured cells. To investigate whether this property can be exploited for cancer therapy, severe combined immune deficient mice bearing tumors established from v-erbB-transformed murine NIH 3T3 cells or human U87 glioblastoma cells were treated with the virus. A single intratumoral injection of virus resulted in regression of tumors in 65 to 80 percent of the mice. Treatment of immune-competent C3H mice bearing tumors established from ras-transformed C3H-10T1/2 cells also resulted in tumor regression, although a series of injections were required. These results suggest that, with further work, reovirus may have applicability in the treatment of cancer.

3T3 Cells↗
PubMed1998

The molecular basis of viral oncolysis: usurpation of the Ras signaling pathway by reovirus.

NIH-3T3 cells, which are resistant to reovirus infection, became susceptible when transformed with activated Sos or Ras. Restriction of reovirus proliferation in untransformed NIH-3T3 cells was not at the level of viral gene transcription, but rather at the level of viral protein synthesis. An analysis of cell lysates revealed that a 65 kDa protein was phosphorylated in untransformed NIH-3T3 cells, but only after infection with reovirus. This protein was not phosphorylated in infected or uninfected transformed cells. The 65 kDa protein was determined to be the double-stranded RNA-activated protein kinase (PKR), whose phosphorylation leads to translation inhibition. Inhibition of PKR phosphorylation by 2-aminopurine, or deletion of the Pkr gene, led to drastic enhancement of reovirus protein synthesis in untransformed cells. The emerging picture is one in which early viral transcripts trigger PKR phosphorylation in untransformed cells, which in turn leads to inhibition of translation of viral genes; this phosphorylation event is blocked by an element(s) in the Ras pathway in the transformed cells, allowing viral protein synthesis to ensue. The usurpation of the Ras signaling pathway therefore constitutes the basis of reovirus oncolysis.

3T3 Cells↗
PubMed1998

Validity of the Perceived Criticism Measure in an undergraduate sample.

The concurrent and predictive validity of the Perceived Criticism Measure's Criticism and Upset subscales was assessed for undergraduates, 21 men and 98 women. Participants were asked to identify five people important to them at present (typically these were parents as well as peers) and, for each, to rate how critical that person was as well as how upsetting they found that criticism to be. Scores on Upset exhibited convergent validity with another self-report measure of general sensitivity to criticism, whereas those on Criticism did not. Neither measure predicted higher ratings of criticism in a specific interaction with a mildly critical peer. Divergent validity with scores on a measure of depression was supported for Upset but was less clear for Criticism. Strong evidence of predictive validity for Criticism and Upset was obtained. Ratings for both Peer scales predicted increased negative affect after mild criticism from a peer, although this interaction took place 4 to 10 weeks after administration of the Perceived Criticism Measure.

Adolescent↗
PubMed1996

The v-erbB oncogene confers enhanced cellular susceptibility to reovirus infection.

We have previously demonstrated that two mouse cell lines that are poorly infectible by reovirus become highly susceptible upon transfection with the gene encoding the epidermal growth factor receptor (EGFR) (J. E. Strong, D. Tang, and P. W. K. Lee, Virology 197:405-411, 1993). This enhancement of infection efficiency requires a functional EGFR, since such an enhancement is not observed in cells expressing a mutated (kinase-inactive) EGFR. The additional finding that reovirus is capable of directly binding to the N-terminal ectodomain of the EGFR (D. Tang, J. E. Strong, and P. W. K. Lee, Virology 197:412-414, 1993) has led us to question whether this interaction is required for the activation of a signalling cascade that somehow augments the ensuing infection process. In the present study, we address this question, using cells transfected with the v-erbB oncogene, which encodes a protein structurally related to the EGFR but lacking a large portion of the N-terminal ligand-binding domain. The v-erbB protein also possesses ligand-independent, constitutive tyrosine kinase activity. Control NIH 3T3 cells, which are poorly infectible by reovirus (serotype 3, strain Dearing), and NIH 3T3 cells transfected with the v-erbB oncogene (THC-11) were assayed for their susceptibilities to reovirus infection. Infectivity was determined by immunofluorescent detection of viral proteins, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of radiolabeled cells, and plaque titration. All three assays demonstrated a drastically higher degree of susceptibility to infection in the THC-11 cell line. This enhanced susceptibility was found to be abrogated by treatment of the cells with genistein, an inhibitor of tyrosine protein kinases, but only partially by treatment with daidzein, an inactive analog of genistein. We propose that the mechanism of enhancement of infection efficiency conferred by EGFR and v-erbB is through the opportunistic utilization by the virus of an already activated signal transduction pathway.

3T3 Cells↗
PubMed1993

Evidence that the epidermal growth factor receptor on host cells confers reovirus infection efficiency.

Reovirus binds to multiple sialoglycoproteins on the host cell surface. In an attempt to probe additional specific determinants that dictate host cell susceptibility to reovirus infection, we found that two mouse cell lines (NR6 and B82) previously shown to express no endogenous epidermal growth factor (EGF) receptors were relatively resistant to reovirus infection, whereas the same cell lines transfected with the gene encoding the EGF receptor manifested significantly higher susceptibility as determined by induction of cytopathic effects, viral protein synthesis, and plaque titration. This enhancement of infection efficiency requires a functional EGF receptor since it was not observed in cells expressing a mutated (kinase-inactive) EGF receptor. The observed difference in infection efficiency is not due to differences in virus binding or internalization. These studies suggest that the reovirus infection process is closely coupled to the EGF receptor-mediated cell signal transduction pathway.

3T3 Cells↗
PubMed1993

Recognition of the epidermal growth factor receptor by reovirus.

The demonstration that alpha-sialic acid is the minimal determinant recognized by human reovirus is compatible with the finding that this virus binds to multiple sialoglycoproteins on the host cell surface. However, the identities of these proteins have remained unknown. By applying detergent-solubilized plasma membranes from the human epidermoid carcinoma A431 cell line to immobilized reovirions, we have identified the 150- to 170-kDa epidermal growth factor (EGF) receptor as one of the cell surface proteins recognized by reovirus. Direct interaction between the N-terminal extracellular domain of the EGF receptor and reovirus was confirmed by the demonstration that of a number of proteins secreted by A431 cells, the 105-kDa N-terminal cell surface domain of the EGF receptor was the major protein recognized by the virus. However, as expected, reovirus and EGF did not compete for the same binding site on the EGF receptor of intact A431 cells.

Autoradiography↗
PubMed1991

Conformational and functional analysis of the C-terminal globular head of the reovirus cell attachment protein.

We have been investigating structure-function relationships in the reovirus cell attachment protein sigma 1 using various deletion mutants and protease analysis. In the present study, a series of deletion mutants were constructed which lacked 90, 44, 30, 12, or 4 amino acids from the C-terminus of the 455-amino acid-long reovirus type 3 (T3) sigma 1 protein. The full-length and truncated sigma 1 proteins were expressed in an in vitro transcription/translation system and assayed for L cell binding activity. It was found that the removal of as few as four amino acids from the C-terminus drastically affected the cell binding function of the sigma 1 protein. The C-terminal-truncated proteins were further characterized using trypsin, chymotrypsin, and monoclonal and polyclonal antibodies. Our results indicated that the C-terminal portions of the mutant proteins were misfolded, leading to a loss in cell binding function. The N-terminal fibrous tail of the proteins was unaffected by the deletions as was sigma 1 oligomerization, further illustrating the discrete structural and functional roles of the N- and C-terminal domains of sigma 1. In an attempt to identify smaller, functional peptides, full-length sigma 1 expressed in vitro was digested with trypsin and subsequently with chymotrypsin under various conditions. The results clearly demonstrated the highly stable nature of the C-terminal globular head of sigma 1, even when separated from the N-terminal fibrous tail. We concluded that: (1) the C-terminal globular head of sigma 1 exists as a compact, protease-resistant oligomeric structure; (2) an intact C-terminus is required for proper head folding and generation of the conformationally dependent cell binding domain.

Amino Acid Sequence↗
PubMed1991

Biochemical and biophysical characterization of the reovirus cell attachment protein sigma 1: evidence that it is a homotrimer.

The oligomerization state of the reovirus cell attachment protein sigma 1 (49K monomeric molecular weight) was determined by biochemical and biophysical means. Full-length (protein product designated A) and C-terminal truncated (protein product designated B) serotype 3 reovirus S1 mRNA transcripts synthesized in vitro were cotranslated in a rabbit reticulocyte lysate, and the products were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under conditions which allowed for the identification of oligomeric forms of sigma 1. A total of four oligomeric protein bands (corresponding to A3, A2B1, A1B2, and B3, respectively) was consistently observed, which suggests that the protein is made up of three monomeric subunits. Biophysical characterization of purified sigma 1 using column filtration and sucrose gradient sedimentation analysis confirmed the highly asymmetric shape of sigma 1 and allowed us to determine the molecular weight of the native protein to be approximately 132K (a trimer). Similar biophysical analysis on the two tryptic fragments of the sigma 1 [N-terminal fibrous tail (26K monomeric molecular weight) and the C-terminal globular head (23K monomeric molecular weight)] yielded molecular weights of 77K and 64K, respectively, both again corresponding to trimers. We therefore conclude that protein sigma 1 is a homotrimer and provide, with supportive experimental evidence, a rationale for the anomalous behavior of the oligomeric protein in SDS-polyacrylamide gels, which, coupled with chemical cross-linking studies, has in part led to the previous suggestion that sigma 1 might be a higher order oligomer.

Capsid Proteins↗
PubMed1982

Bleomycin clinical pharmacology by radioimmunoassay.

Bleomycin pharmacokinetics were studied by radioimmunoassay in 11 patients who received 7-30 U intravenously (IV) and eight patients who received 4-30 U subcutaneously (SC). For patients who received IV bleomycin plasma disappearance was biphasic, with a mean initial half-life of 0.26 h and a terminal half-life of 2.3 h. Mean plasma drug clearance was 67.8 ml/min/m2 and the volume of distribution was 13.2 l/m2. Urinary excretion accounted for 63.9% of the drug in 24 h. After SC administration peak plasma levels occurred in 1.1 h, with a mean elimination half-life of 4.3 h. Mean plasma drug clearance was 60.5 ml/min/m2 and the volume of distribution was 19.2 l/m2. Bleomycin plasma clearance correlated well with serum creatinine (r2 = 0.72). Bleomycin has a rapid plasma elimination and urinary excretion. Bleomycin bioavailability after SC administration appears comparable to that seen after IV administration as determined by the areas under the plasma disappearance curves. Prolonged plasma levels are seen after SC injection, suggesting this route of administration can produce plasma concentrations comparable to those attained with continuous IV infusions.

Adolescent↗
PubMed1981

Postoperative analgesia in major orthopaedic surgery. Epidural and intrathecal opiates.

Sixty-two patients were given morphine 2 mg and 69 patients were given diamorphine 0.5 mg by either the epidural or intrathecal route. All had undergone either total hip replacement or spinal disc surgery. Forty-nine out of 131 patients required no further analgesia. Diamorphine was superior to morphine and the intrathecal route more effective than the epidural. Headache, pruritus, urinary retention and nausea and vomiting were recorded, the incidence of the latter being unacceptably high, particularly when the drugs were administered by the intrathecal route: one patient required resuscitation. It is suggested that previously reported respiratory depression using these techniques is associated with the administration of other analgesics contemporaneously; that dosage should be limited to one-fifth of the estimation intramuscular dose; and that patients should be observed in a recovery ward for 24 hours.

Aged↗
PubMed1981

Preliminary studies of the pharmacokinetics of talisomycin in the rhesus monkey.

The single dose intravenous pharmacokinetics of talisomycin (3 mg/M2) and bleomycin (18 U/M2) were determined in the rhesus monkey at non-nephrotoxic doses. Serum concentrations were analyzed by radioimmunoassay procedures. The tissue distribution of talisomycin was significantly higher and the elimination slower than bleomycin. The volume of distribution (Vdss) was 2.3 and 22.6 L/M2 for bleomycin and talisomycin, respectively. The volume of the peripheral tissue compartment (V2) of talisomycin was 17 times greater than bleomycin. The slower elimination of talisomycin was reflected by a half-life (t1/2) of 10.6 hr versus 1.6 hr for bleomycin. The slower elimination from the peripheral tissue compartments was also evidenced by a five-fold difference in the tissue transfer ratio (k12/k21) for these compounds. Similar differences, of lesser magnitude, have also been reported in the dog. The potential for higher tissue distribution and slower elimination of talisomycin could be related to the differences in in vivo antitumor activity and toxicity, and should be considered in design of the dose schedule in clinical studies.

Animals↗
PubMed1979

Use of covalently closed circular deoxyribonucleic acid for prescreening for antitumor compounds.

The interactions of PM-2 deoxyribonucleic acid (DNA) with 20 known antineoplastic agents were studied using agarose gel electrophoresis and fluorescence assay systems. Actinomycin D and adriamycin (and all other anthracyclines studied) induced superhelical conformational changes in PM-2 DNA. Bleomycin A2, tallysomycin, neocarzinostatin, macromomycin, and hedamycin degraded PM-2 DNA under various conditions. The potential utility of PM-2 DNA as an antitumor antibiotic prescreening tool was further studied by examining the effects of 200 broths on PM-2 DNA employing both fluorescence and agarose gel electrophorectic assays. The assays were shown to be sensitive and rapid and to provide information not provided by other prescreens with which the PM-2 DNA assays were compared.

Antineoplastic Agents↗
PubMed1979

Use of PM-2 DNA degradation as a pharmacokinetic assay for bleomycin.

The PM-2 DNA fluorescence assay has been shown to be a rapid, sensitive, and reproducible assay for bleomycin biochemical activity. The assay can detect bleomycin in human serum in the nmol range. The method measures DNA degradative activity of bleomycin and could be used to determine activity of bleomycin analogs and metabolites. The usefulness of the assay to perform bleomycin pharmacokinetic studies in cancer patients has been demonstrated. Linear regression analyses of parallel bleomycin assays with the radioimmunoassay gave a coefficient of correlation of 0.98 to 0.78 with trichloroacetic acid-treated serum. These results indicate excellent agreement between the two assays.

Adult↗