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G Miller

Publications and source records attributed to G Miller.

At least 91 records · Page 5Linked to original sources
PubMed1999

Interleukin-1 receptor antagonist attenuates regional neuronal cell death and cognitive dysfunction after experimental brain injury.

The effect of systemic administration of human recombinant interleukin-1 receptor antagonist (rhIL-1ra) on behavioral outcome and histopathologic damage after lateral fluid-percussion brain injury of moderate severity was evaluated. In study 1, brain-injured Sprague Dawley rats received timed subcutaneous injections beginning 15 minutes after injury of either 100 mg/kg rhIL-1ra (high dose, total dose = 1900 mg/kg), 10 mg/kg rhIL-1ra (low dose, total dose = 190 mg/kg), or vehicle over 7 days. No effect of low-dose rhIL-1ra was observed in study 1. High-dose rhIL-1ra significantly attenuated posttraumatic neuronal loss in the injured hippocampal CA3 region (P < 0.05), dentate hilus (P < 0.05), and cortex (P < 0.05) but impaired recovery of motor function at 7 days after trauma (P < 0.05). In study 2, rats were pretrained to learn a visuospatial task in a Morris water maze, subjected to fluid-percussion brain injury or sham treatment, and randomly assigned to receive multiple subcutaneous injections at timed intervals of 100 mg/kg rhIL-1ra (total dose = 900 mg/kg) or vehicle over 42 hours, followed by continuous infusion of a lower concentration of rhIL-1ra (20 mg/kg/day, total dose = 100 mg/kg), or vehicle for 5 days using subcutaneously implanted osmotic minipumps. Postinjury administration of rhIL-1ra significantly attenuated cognitive deficits compared with vehicle-treated animals at 42 hours (P < 0.05) but did not affect motor function at 48 hours, 1 week, and 2 weeks. These results suggest that inhibitors of cytokine pathways may be therapeutically useful for the treatment of brain trauma.

Animals↗
PubMed1999

Role of the epstein-barr virus RTA protein in activation of distinct classes of viral lytic cycle genes.

Initiation of the Epstein-Barr virus (EBV) lytic cycle is controlled by two immediate-early genes, BZLF1 and BRLF1. In certain epithelial and B-cell lines, their protein products, ZEBRA and Rta, stimulate their own expression, reciprocally stimulate each other's expression, and activate downstream viral targets. It has been difficult to examine the individual roles of these two transactivators in EBV-infected lymphocytes, as they are expressed simultaneously upon induction of the lytic cycle. Here we show that the Burkitt lymphoma cell line Raji represents an experimental system that allows the study of Rta's role in the lytic cycle of EBV in the absence and presence of ZEBRA. When expressed in Raji cells, exogenous Rta does not activate endogenous BZLF1 expression, yet Rta remains competent to transactivate certain downstream viral targets. Some genes, such as BaRF1, BMLF1, and a late gene, BLRF2, are maximally activated by Rta itself in the absence of detectable ZEBRA. The use of the Z(S186A) mutant form of ZEBRA, whose transactivation function is manifest only by coexpression of Rta, allows identification of a second class of lytic cycle genes, such as BMRF1 and BHRF1, that are activated in synergy by Rta and ZEBRA. It has already been documented that of the two activators, only ZEBRA stimulates the BRLF1 gene in Raji cells. Thus, there is a third class of viral genes activated by ZEBRA but not Rta. Moreover, ZEBRA exhibits an inhibitory effect on Rta's capacity to stimulate the late gene, BLRF2. Consequently ZEBRA may function to repress Rta's potential to activate some late genes. Raji cells thus allow delineation of the combinatorial roles of Rta and ZEBRA in control of several distinct classes of lytic cycle genes.

DNA Replication↗
PubMed1999

Kaposi's sarcoma-associated herpesvirus encodes a bZIP protein with homology to BZLF1 of Epstein-Barr virus.

Kaposi's sarcoma-associated herpesvirus (KSHV) is a recently discovered human gamma herpesvirus strongly implicated in AIDS-related neoplasms. We report here the identification in the KSHV genome of a gene for a protein designated K-bZIP and belonging to the basic-leucine zipper (bZIP) family of transcription factors. K-bZIP shows significant homology to BZLF1, which plays a key role in the replication and reactivation of Epstein-Barr virus. K-bZIP is a homodimerizing protein of 237 amino acids with a prototypic bZIP domain at the C terminus. The N-terminal portion of K-bZIP is derived from the K8 open reading frame which, through in-frame splicing, adjoins the ZIP domain. This structure was revealed by rapid analysis of cDNA ends, followed by cloning of the entire cDNA. A 1.35-kb transcript encoding K-bZIP was detected in BCBL-1 cells treated with 12-O-tetradecanoylphorbol-13-acetate. The synthesis of this transcript was blocked by the protein synthesis inhibitor cycloheximide but not by the viral DNA synthesis inhibitor phosphonoacetate, a result which classifies it as an early lytic gene. RNase protection analysis further mapped the major transcription start site for the 1.35-kb K-bZIP mRNA and identified two other splice variants which encode proteins with the N-terminal portion of K-bZIP but lacking the C-terminal ZIP domain. Full-length K-bZIP forms dimers with itself, and the C terminus encompassing the ZIP domain is required for this process. Our studies set the stage for understanding the role of K-bZIP in the replication and reactivation of the KSHV genome.

Amino Acid Sequence↗
PubMed1999

Kinetics of Kaposi's sarcoma-associated herpesvirus gene expression.

Herpesvirus gene expression can be classified into four distinct kinetic stages: latent, immediate early, early, and late. Here we characterize the kinetic class of a group of 16 Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8 genes in a cultured primary effusion cell line and examine the expression of a subset of these genes in KS biopsies. Expression of two latent genes, LANA and vFLIP, was constitutive and was not induced by chemicals that induce the lytic cycle in primary effusion lymphoma (PEL) cell lines. An immediate-early gene, Rta (open reading frame 50 [ORF50]), was induced within 4 h of the addition of n-butyrate, and its 3.6-kb mRNA was resistant to inhibition by cycloheximide. Early genes, including K3 and K5 that are homologues of the "immediate-early" gene of bovine herpesvirus 4, K8 that is a positional homologue of Epstein-Barr virus BZLF1, vMIP II, vIL-6, and polyadenylated nuclear (PAN) RNA, appeared 8 to 13 h after chemical induction. A second group of early genes that were slightly delayed in their appearance included viral DHFR, thymidylate synthase, vMIP I, G protein-coupled receptor, K12, vBcl2, and a lytic transcript that overlapped LANA. The transcript of sVCA (ORF65), a late gene whose expression was abolished by Phosphonoacetic acid, an inhibitor of KSHV DNA replication, did not appear until 30 h after induction. Single-cell assays indicated that the induction of lytic cycle transcripts resulted from the recruitment of additional cells into the lytic cycle. In situ hybridization of KS biopsies showed that about 3% of spindle-shaped tumor cells expressed Rta, ORF K8, vIL-6, vMIP I, vBcl-2, PAN RNA, and sVCA. Our study shows that several KSHV-encoded homologues of cellular cytokines, chemokines, and antiapoptotic factors are expressed during the viral lytic cycle in PEL cell lines and in KS biopsies. The lytic cycle of KSHV, probably under the initial control of the KSHV/Rta gene, may directly contribute to tumor pathogenesis.

Chemokines↗
PubMed1999

Cellular tropism and viral interleukin-6 expression distinguish human herpesvirus 8 involvement in Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease.

Human herpesvirus 8 (HHV-8) infection has been implicated in the etiology of Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD), three diseases that frequently develop in immunocompromised, human immunodeficiency virus-positive individuals. One hypothesis that would account for different pathological manifestations of infection by the same virus is that viral genes are differentially expressed in heterogeneous cell types. To test this hypothesis, we analyzed the localization and levels of expression of two viral genes expressed in latent and lytic infections and the viral homologue of interleukin-6 (vIL-6). We show that PEL parallels KS in the pattern of latent and lytic cycle viral gene expression but that the predominant infected cell type is a B cell. We also show that MCD differs from KS not only in the infected cell type (B-cell and T-cell lineage) but also in the pattern of viral gene expression. Only a few cells in the lesion are infected and all of these cells express lytic-cycle genes. Of possibly greater significance is the fact that in a comparison of KS, PEL, and MCD, we found dramatic differences in the levels of expression of vIL-6. Interleukin-6 is a B-cell growth and differentiation factor whose altered expression has been linked to plasma cell abnormalities, as well as myeloid and lymphoid malignancies. Our findings support the hypothesis that HHV-8 plays an important role in the pathogenesis of PEL and MCD, in which vIL-6 acts as an autocrine or paracrine factor in the lymphoproliferative processes common to both.

Castleman Disease↗
PubMed1999

Amino acid substitutions reveal distinct functions of serine 186 of the ZEBRA protein in activation of early lytic cycle genes and synergy with the Epstein-Barr virus R transactivator.

The ZEBRA protein mediates the switch between the latent and lytic life cycles of Epstein-Barr virus. Z(S186A), a point mutant in ZEBRA's basic domain in which serine 186 is changed to alanine, is unable to induce expression of lytic cycle mRNAs or proteins from the latent EBV genome even though it retains the ability to activate transcription from reporters bearing known ZEBRA-responsive promoters (A. L. Francis et al., J. Virol. 71:3054-3061, 1997). We now describe three distinct phenotypes of ZEBRA mutants bearing different amino acid substitutions at S186. These phenotypes are based on the capacity of the mutants to activate expression of the BRLF1 and BMRF1 genes, which are targets of ZEBRA's action, and to synergize with the BRLF1 gene product Rta (R transactivator) in activating expression of downstream genes. One mutant class, represented by Z(S186T), was similar to the wild type, although reduced in the capacity to activate BRLF1 and BMRF1 early lytic cycle genes from the latent virus. A second class, represented by Z(S186C) and Z(S186G), was impaired in transcriptional activation, unable to activate early lytic cycle products from the latent virus, and not rescued by overexpression of Rta. A third class, Z(S186A), although unable by itself to activate BRLF1 or other lytic cycle genes, synergized with Rta. Rta rescued the capacity of Z(S186A) to activate the BMRF1 early lytic cycle gene from the latent virus. All mutant classes bound to DNA in vitro, although their capacity to bind to different ZEBRA response elements varied. Serine 186 of ZEBRA is a critical residue that is required for the distinct activities of induction of BRLF1 expression and for synergy with Rta. Since only Z(S186T) among the mutants behaved similarly to the wild type, activation of BRLF1 likely requires phosphorylation of S186. However, since Z(S186A) could synergize with Rta, synergy with Rta does not appear to be dependent on phosphorylation of S186. S186 likely mediates DNA recognition on the BRLF1 promoter in the context of the latent virus, protein-protein interactions, or both. The Z(S186) mutants define the amino acid side chains required for these functions.

Antigens, Viral↗
PubMed1999

Accuracy of glucose reflectance testing for detecting hypoglycemia in term newborns.

Glucose concentrations of 248 newborns at 1 and 3 hours of age were determined at the bedside by means of the Accu-Chek III Reflectance meter and in the laboratory by means of the Vitros 750 analyzer. Hypoglycemia being defined as a glucose concentration less than 40 mg/dL, the reflectance meter had a sensitivity of 0.757 and a specificity of 0.876 at 1 hour and 0.975 at 3 hours. The imprecision of the reflectance meter at 1 hour eliminated it as a routine testing method.

Gestational Age↗
PubMed1999

The impact of Medicaid managed care on community clinics in Sacramento County, California.

OBJECTIVES: The purpose of this study was to determine the impact of countywide Medicaid managed care on service use at community clinics. METHODS: Clinic use before and after introduction of Medicaid plans in one county was compared with that in a group of comparable counties without such plans. RESULTS: There were significant declines of 40% to 45% in the volumes of Medicaid clients, encounters, and revenues at clinics with the introduction of Medicaid plans. Declines of 23% in uninsured clients and encounters did not differ significantly. CONCLUSIONS: The introduction of Medicaid managed care with multiple commercial plans can have significant negative effects on nonprofit community clinics.

Analysis of Variance↗
PubMed1999

A relationship between computerisation and quality in general practice.

AIM: To explore whether there is an association between use of computers and compliance with The Royal Australian College of General Practitioners (RACGP) Entry Standards for General Practice. METHOD: Participants in the RACGP Field Test of Standards were surveyed to determine their level of computerisation. These data were matched with the participants' compliance with selected standards. These standards were selected on the basis that compliance with them was relatively low and might be improved by appropriate use of information technology. Ordinal regression analyses were conducted of compliance with the selected standard and relevant levels of computerisation. RESULTS: There was a significant relationship between having a practice computer and providing patients with written information about the practice (p < 0.0005) and systematic preventive care (p = 0.037). DISCUSSION: There may be a relationship between quality general practice and computerisation.

Computers↗
PubMed1998

Bilateral orchiectomy with or without flutamide for metastatic prostate cancer.

BACKGROUND: Combined androgen blockade for the treatment of metastatic prostate cancer consists of an antiandrogen drug plus castration. In a previous trial, we found that adding the antiandrogen flutamide to leuprolide acetate (a synthetic gonadotropin-releasing hormone that results in medical ablation of testicular function) significantly improved survival as compared with that achieved with placebo plus leuprolide acetate. In the current trial, we compared flutamide plus bilateral orchiectomy with placebo plus orchiectomy. METHODS: We randomly assigned patients who had never received antiandrogen therapy and who had distant metastases from adenocarcinoma of the prostate to treatment with bilateral orchiectomy and either flutamide or placebo. Patients were stratified according to the extent of disease and according to performance status. RESULTS: Of the 1387 patients who were enrolled in the trial, 700 were randomly assigned to the flutamide group and 687 to the placebo group. Overall, the incidence of toxic effects was minimal; the only notable differences between the groups were the greater rates of diarrhea and anemia with flutamide. There was no significant difference between the two groups in overall survival (P=0.14). The estimated risk of death (hazard ratio) for flutamide as compared with placebo was 0.91 (90 percent confidence interval, 0.81 to 1.01). Flutamide was not associated with enhanced benefit in patients with minimal disease. CONCLUSIONS: The addition of flutamide to bilateral orchiectomy does not result in a clinically meaningful improvement in survival among patients with metastatic prostate cancer.

Adenocarcinoma↗
PubMed1998

Transgenic mice for interleukin 3 develop motor neuron degeneration associated with autoimmune reaction against spinal cord motor neurons.

Interleukin 3 (IL-3) stimulates the proliferation and differentiation of various haematopoietic progenitor cells. Recently, IL-3 and other cytokines were reported to exert a neurotrophic activity and to be associated with neurological disorders, suggesting their complex role in the central nervous system. We now show that overexpression of IL-3 in transgenic mice causes a motor neuron disease with several features of amyotrophic lateral sclerosis and progressive muscular atrophy. These animals exhibit hind limb paralysis at 7 months of age, associated with dendritic and axonal degeneration, loss of motor neurons in the spinal cord, and autoimmune reaction against these cells. We examined the effect of IL-3 on embryonic motor neurons survival in mixed spinal cord cultures. Our results suggest that motor neuronal degeneration is not directly triggered by the high level of expression of IL-3.

Amyotrophic Lateral Sclerosis↗
PubMed1998

Probability Density Estimation Using Entropy Maximization.

We propose a method for estimating probability density functions and conditional density functions by training on data produced by such distributions. The algorithm employs new stochastic variables that amount to coding of the input, using a principle of entropy maximization. It is shown to be closely related to the maximum likelihood approach. The encoding step of the algorithm provides an estimate of the probability distribution. The decoding step serves as a generative mode, producing an ensemble of data with the desired distribution. The algorithm is readily implemented by neural networks, using stochastic gradient ascent to achieve entropy maximization.

Journal Article↗
PubMed1998

Somatic mutation of TSSC5, a novel imprinted gene from human chromosome 11p15.5.

We previously reported the isolation of a 2.5 Mb tumor-suppressing subchromosomal transferable fragment (STF) from 11p15.5 and the identification of nine known genes and four novel genes within this STF. We now report the isolation of a fifth novel cDNA, tumor-suppressing STF cDNA 5, designated TSSC5, located within the STF. TSSC5 encodes a predicted protein of 424 amino acids. Sequence analysis suggests that TSSC5 is a membrane protein with 10 transmembrane segments, and it is located between two imprinted genes, p57KIP2 and TSSC3. Northern blot hybridization revealed a 1.6-kb transcript in multiple adult tissues and in fetal liver and kidney, consistent with a potential role in embryonal tumors. We also found that TSSC5 is imprinted with preferential expression from the maternal chromosome. Reverse transcription-PCR analysis of TSSC5 revealed frequent occurrence of aberrant RNA splicing, which deleted exons 4, 5, and 6 in Wilms' tumors. Mutational analysis of TSSC5 by direct DNA sequencing of exons revealed a base substitution of G1120A in a Wilms' tumor, matched normal kidney, and the patient's mother, changed Arg at codon 309 to Gln. The G1120A substitution thus represents either a rare polymorphism or a tumor-predisposing mutation, because the mutant allele was of maternal origin and preferentially expressed in the patient's tissue. A second base substitution, C892T, was found in a lung cancer, changing Ser at codon 233 to Phe. This substitution was absent from the matched normal tissue and thus represented a somatic mutation. We also found loss of heterozygosity in the lung cancer, suggesting that TSSC5 may be a conventional tumor suppressor gene in the adult human lung and an imprinted tumor suppressor gene in the fetal kidney.

Adult↗
PubMed1998

A viral gene that activates lytic cycle expression of Kaposi's sarcoma-associated herpesvirus.

Herpesviruses exist in two states, latency and a lytic productive cycle. Here we identify an immediate-early gene encoded by Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus eight (HHV8) that activates lytic cycle gene expression from the latent viral genome. The gene is a homologue of Rta, a transcriptional activator encoded by Epstein-Barr virus (EBV). KSHV/Rta activated KSHV early lytic genes, including virus-encoded interleukin 6 and polyadenylated nuclear RNA, and a late gene, small viral capsid antigen. In cells dually infected with Epstein-Barr virus and KSHV, each Rta activated only autologous lytic cycle genes. Expression of viral cytokines under control of the KSHV/Rta gene is likely to contribute to the pathogenesis of KSHV-associated diseases.

Amino Acid Sequence↗
PubMed1998

Serologic association of human herpesvirus eight with posttransplant Kaposi's sarcoma in Saudi Arabia.

BACKGROUND: This study investigates the association between human herpesvirus eight (HHV8) and Kaposi's sarcoma (KS), the most common cancer occurring in renal transplant recipients in Saudi Arabia. METHODS: A cross-sectional study of seroreactivity to HHV8 antigens in posttransplant KS patients from a tertiary care hospital in Riyadh, Saudi Arabia, and in control subjects without KS was conducted. Seroreactivity rates were determined using immunoblotting assays to detect antibodies to two lytic cycle HHV8 antigens: p40, an antigen found in infected cells, and sVCA, an HHV8-encoded small viral capsid antigen expressed in Escherichia coli. RESULTS: Antibodies to HHV8 p40 and sVCA were present in a significantly higher proportion of renal transplant patients with KS (13 of 14 patients) compared to renal transplant patients without KS (5 of 18; P<0.001) and compared to other control individuals (6 of 44; P<0.001). HHV8 seroreactivity was more common among patients with renal failure (28%) than among other control groups (7%). CONCLUSIONS: The serologic results provide evidence of a strong association between HHV8 and posttransplant KS in Saudi Arabia.

Antibodies, Viral↗
PubMed1998

Factors involved in regulating primary and secondary immunity to infection with Histoplasma capsulatum: TNF-alpha plays a critical role in maintaining secondary immunity in the absence of IFN-gamma.

Primary infection to Histoplasma capsulatum often results in a self-limited upper respiratory infection in humans; however, in immunocompromised hosts, disseminated infection can occur through reactivation of a previous infection. Since disseminated histoplasmosis has emerged as a difficult clinical entity to treat in individuals infected with HIV, it was of interest to study the mechanisms involved in maintaining an effective memory immune response. It has been previously shown in a murine model of disseminated histoplasmosis that IL-12, IFN-gamma, and TNF-alpha were important factors in mediating primary protection. To study whether these and other factors were involved in maintaining a protective immune response following secondary infection, normal C57BL/6 mice were first infected with a sublethal dose of H. capsulatum (1 x 10(5)) and then reinfected 3 wk later with a lethal dose of H. capsulatum (6 x 10(5)). Under these conditions, all mice developed an effective immune response with sterilizing immunity. Moreover, normal C57BL/6 mice treated with neutralizing Abs against either IL-12, TNF-alpha, or IFN-gamma, depleted of neutrophils or treated with aminoguanidine at the time of reinfection, maintained an effective immune response. The ability of animals to survive a secondary infection in the absence of IFN-gamma was verified by showing that IFN-gamma(-/-) mice previously immunized with H. capsulatum and treated with amphotericin B at the time of primary infection had prolonged survival following reinfection with a normally lethal dose. It was further shown that enhancement of TNF-alpha production in IFN-gamma(-/-) mice was the major mechanism by which these mice were effective in controlling secondary infection.

Animals↗