Search PubMed⌕ Search

Biomedical subjects

C G Miller

Publications and source records attributed to C G Miller.

At least 37 records · Page 2Linked to original sources
PubMed1997

The cowpox virus-encoded homolog of the vaccinia virus complement control protein is an inflammation modulatory protein.

Vaccinia virus complement control protein (VCP) is encoded by vaccinia virus, with its homolog encoded by other pathogenic poxviruses including variola virus. Since rodents are the primary reservoir hosts of cowpox virus (CPV) and since CPV encodes a highly conserved functional homolog of VCP, termed here the inflammation modulatory protein (IMP), the effects of injection of CPV into the footpads of mice was determined in order to study the precise in vivo effects of IMP. Macroscopic examination of the site of injection with a recombinant virus lacking IMP (CPV-IMP) showed greater tissue damage, with more hemorrhage and induration, than sites injected with the wild-type cowpox virus. In addition, the measurement of the specific swelling response carried out for several weeks revealed significantly greater swelling in mice injected with CPV-IMP. Thus, IMP modulates the complement-activated inflammatory response in vivo. Furthermore, the diminished destruction of host tissue observed in the presence of IMP indicates symbiosis in which the virus ensures the preservation of surrounding host tissue, possibly to support the growth of its progeny.

Amino Acid Sequence↗
PubMed1997

Regulation of the Salmonella typhimurium pepT gene by cyclic AMP receptor protein (CRP) and FNR acting at a hybrid CRP-FNR site.

The Salmonella typhimurium pepT gene is induced nearly 30-fold in response to anaerobiosis. Anaerobic expression is dependent on the transcriptional regulator encoded by fnr (previously oxrA). Primer extension analysis and site-directed mutagenesis experiments show that pepT is transcribed from two sigma 70 promoters. One promoter (P1) is FNR dependent and anaerobically induced, while the other (P2) appears to be constitutive. The potABCD operon is divergently transcribed from a promoter near pepT P2. Sequence analysis of pepT promoter mutations which either elevate anaerobic expression or confer constitutive expression revealed that these mutations affect the -10 region of the P1 or P2 promoter, respectively. The pepT200 mutation, which changes the -10 region of the FNR-dependent P1 promoter to the consensus, has the surprising effect of allowing five- to sevenfold anaerobic induction in the absence of FNR. We have shown that the anaerobic induction of pepT-lacZ in a pepT200 fnr strain is dependent on wild-type alleles of both crp and cya. In a pepT200 pepT-lacZ strain, beta-galactosidase activity was elevated aerobically in the presence of exogenous cyclic AMP (cAMP) and was elevated also in succinate minimal medium relative to its level in glucose minimal medium. Primer extension analysis confirmed that P1 is the cAMP receptor protein (CRP)-dependent promoter. Site-directed mutagenesis experiments indicated that a hybrid CRP-FNR binding site positioned at -41 of the P1 promoter is utilized by both FNR and CRP. CRP-cAMP also appeared to repress FNR-dependent transcription of pepT under anaerobic conditions in both the pepT+ and pepT200 backgrounds. Although both CRP and FNR are capable of binding the hybrid site and activating transcription of pepT, CRP requires the consensus -10 sequence for efficient activation.

Aminopeptidases↗
PubMed1996

Two chemotactic factors, C5a and MIP-1alpha, dramatically alter the mortality from zymosan-induced multiple organ dysfunction syndrome (MODS): C5a contributes to MODS while MIP-1alpha has a protective role.

Multiple organ dysfunction syndrome (MODS) is a major cause of morbidity and mortality in surgical intensive care units. It is characterized by progressive failure of two or more organs remote from the origin of injury. Since MODS results from a severe generalized inflammatory response, both chemokines and complement have had a proposed role in its pathophysiology. The availability of macrophage inflammatory protein 1 alpha (MIP-1alpha) knockout mice and congenic C5-deficient and C5-sufficient mice allowed us to investigate the individual contribution of these immune modulators in MODS. It has been demonstrated in this assay that MIP-1alpha has a protective role against MODS mortality, while C5a contributes to MODS mortality. Using a zymosan-induced MODS murine model, the absence of MIP-1alpha increased mortality four-fold, whereas the absence of C5 decreased mortality four-fold. Therefore, MIP-1alpha-dependent mediators are essential in the prevention of MODS related deaths, while C5-dependent mediators of inflammation can be considered to be contributing to the development of MODS related deaths.

Animals↗
PubMed1995

Virus and host-specific adaptations in the BL1 and BR1 genes of bipartite geminiviruses.

The host range of individual geminiviruses may be quite narrow, and closely related viruses can exhibit distinct host adaptations. Two such bipartite geminiviruses are bean golden mosaic virus (GBMV) and tomato golden mosaic virus (TGMV). In both, the BL1 and BR1 genes are required for the spread of virus infection in plants. We have investigated the contributions of BL1 and BR1 to host-specific phenotypes of BGMV and TGMV by constructing hybrid viruses in which these coding regions were exchanged. Hybrids were assayed on bean, a good host for BGMV, and Nicotiana benthamiana, a good host for TGMV. A BGMV hybrid having TGMV BL1 and BR1 efficiently infected beans, but elicited attenuated symptoms. In N. benthamiana, this hybrid had slightly increased virulence and DNA accumulation relative to wild-type BGMV. A TGMV hybrid having BGMV BL1 and BR1 was virulent in N. benthamiana, but elicited attenuated symptoms. However, this hybrid exhibited no gain of function in beans relative to wild-type TGMV. Hybrid viruses with TGMV BL1 and BGMV BR1 had severely defective phenotypes in either viral or host background. Although exchanging BL1 and BR1 between BGMV and TGMV did not change host range, some host adaptation of these genes is suggested. However, virus-specific compatibility between BL1 and BR1 is of more importance for viability. Thus, these gene products may act in concert to potentiate virus movement.

Adaptation, Physiological↗
PubMed1995

Complementable and noncomplementable host adaptation defects in bipartite geminiviruses.

Members of the geminvirus group of plant viruses collectively infect a broad spectrum of species. Individual viruses which are genetically very similar may nevertheless have distinct host ranges. Two such geminiviruses are tomato golden mosaic virus (TGMV) and been golden mosaic virus (BGMV), for which common hosts have not previously been reported. Each virus has two genome components, designated A and B. The A component is capable of autonomous replication and encapsidation, whereas the B component provides viral functions required for the spread of infection in plants. To investigate the basis for the distinctive host ranges of BGMV and TGMV, we have introduced plasmids containing cloned viral genome components into Nicotiana benthamiana, a good host for TGMV, and bean, Phaseolus vulgaris, a good host for BGMV. We found that TGMV has a low specific infectivity for bean and is virulent, whereas BGMV has a high specific infectivity for N. benthamiana, but infections are asymptomatic and viral DNA accumulation is low. To investigate which viral functions were defective in the poor host in each case, we attempted to complement them by co-inoculation with the well-adapted virus. After inoculation of beans with both viruses, only BGMV was detected. Thus, TGMV exhibits a noncomplementable host adaptation defect in beans. This suggests that the defect has a cis-acting or virus-specific trans-acting genetic basis. In contrast, the BGMV phenotype of low DNA accumulation in N. benthamiana was partially complemented by TGMV A alone and complemented further by the complete TGMV genome. This suggests that a virus nonspecific, trans-acting factor encoded by the BGMV A component is poorly adapted to N. benthamiana. The results of this study indicate that bipartite geminivirus host range may be limited by defective virus-host interactions of more than one kind.

DNA, Viral↗
PubMed1995

Vinorelbine tartrate and paclitaxel combinations: enhanced activity against in vivo P388 murine leukemia cells.

BACKGROUND: Many critical cellular functions such as mitosis, cell movement, and maintenance of cell structure are performed by microtubules. Antimicrotubule agents (which disrupt or block the formation of microtubules) are among the most widely used anticancer drugs and have contributed to the curative therapy of many neoplasms. Recently, two new antimicrotubule agents, vinorelbine tartrate (Navelbine) and paclitaxel (Taxol) have demonstrated clinical activity against ovarian, breast, and non-small-cell lung carcinomas. These agents target microtubules at different sites, and they both interfere with mitotic spindle function. Since vinorelbine tartrate and paclitaxel have shown a similar antitumor profile in clinical trials thus far, it is reasonable to expect that they may be used interchangeably in some combination therapies or perhaps with each other in the same treatment regimen. PURPOSE: On the basis of their similar activity profile in clinical trials, we decided to investigate the therapeutic outcome of a vinorelbine tartrate and paclitaxel binary drug combination, even though they appeared to have overlapping toxic effects. We wanted to ascertain the effect of this binary drug combination, in an in vivo setting, as it related to host toxicity and antitumor activity. METHODS: CDF-1 female mice that were implanted intraperitoneally with one million P388 murine leukemia cells were treated intraperitoneally with vinorelbine tartrate, paclitaxel, or a combination of the two drugs on a day-1, -5, and -9 dosing schedule. Experimental groups had between five and eight mice per group. Vinorelbine tartrate was administered at either 8, 12, 16, 20, or 24 mg/kg and paclitaxel at either 4.5, 18, or 36 mg/kg. RESULTS: As single agents, neither vinorelbine tartrate nor paclitaxel generated meaningful numbers of 60-day cures (i.e., tumor free at day 60). In contrast, optimal combination regimens produced 60-day cures in more than 80% of the mice. The LD10 (dose lethal to 10% of the mice) of vinorelbine tartrate increased approximately 2.5-fold in the presence of paclitaxel and allowed otherwise lethal vinorelbine tartrate doses to be administered safely, which may have contributed to the antitumor efficacy of the combinations. The effect of the time delay between vinorelbine tartrate and paclitaxel administration on toxicity and cures appeared to be contingent on the vinorelbine tartrate dose. CONCLUSIONS: Results suggest that the overlapping toxic effects of vinorelbine tartrate and paclitaxel might not be a deterrent to their use in combination drug therapy. When used appropriately, rather than having enhanced toxic effects, otherwise toxic doses were better tolerated and survival improved over single-agent therapy.

Animals↗
PubMed1995

Severe and prolonged inflammatory response to localized cowpox virus infection in footpads of C5-deficient mice: investigation of the role of host complement in poxvirus pathogenesis.

Poxviruses are a large, complex group of highly successful pathogens that cause disease in humans and other animals. They encode several proteins postulated to be involved in the evasion of host immunity and therefore serve as excellent models for understanding virus-host interaction during the early stages of viral infection. Vaccinia virus, the best characterized member of the poxviridae family, encodes a 35-kDa major secretory polypeptide termed vaccinia virus complement control protein (VCP), which is structurally related to the family of human and mouse complement control proteins. Members of the family of complement control proteins have been shown to inhibit complement-mediated opsonization of bacteria and induction of inflammatory and phagocytic responses in vitro. Insertional inactivation of the VCP gene results in attenuation of viral virulence in vivo. The role of host complement in the inflammatory response to poxvirus infection has not been systematically investigated. Prior to determining the role of VCP on inflammatory responses in vivo, we decided to investigate the role of host complement in the progression of viral infection. We have compared the effects of injection of cowpox virus, primarily a rodent virus, into footpads of congenic mice strains B10.D2/nSnJ (C5-sufficient) and B10.D2/oSnJ (C5-deficient). The effects of the injection were monitored macroscopically by measuring the specific swelling response immediately following primary injection and subsequently after reinfection and by histological examination of the stained sections of the footpads. Our results indicate that there is a significant variation in the primary response in the two different mouse strains to cowpox virus infection. The specific swelling response observed in measurements from the footpads of the B10.D2/oSnJ mice was significantly greater, persisted for a longer duration, and was accompanied by severe ulceration, edema, induration, and hemorrhaging. Reinjection of the footpads after a 3-month period, during which time the swelling had subsided and the footpad had fully recovered to its original size and appearance, showed no significant differences between the two strains. This strongly suggests that the host complement plays a significant role during the initial response to poxvirus infection.

Animals↗
PubMed1994

Mutations affecting a regulated, membrane-associated esterase in Salmonella typhimurium LT2.

Mutations at the apeA locus in Salmonella typhimurium lead to loss of a soluble enzyme ("protease I") that hydrolyzes the chromogenic endoprotease substrate N-acetyl phenylalanine beta-naphthyl ester. We have isolated pseudorevertants of S. typhimurium apeA mutations that have regained the ability to hydrolyze this compound. These pseudorevertants contain mutations (apeR) that lead to overproduction of a membrane-bound esterase different from protease I. The apeR locus is phage P1 cotransducible with ilvC (83 map units) and is unlinked to apeA. Mutations at still another locus, apeE, lead to loss of the membrane-associated esterase. The apeE locus is P1 cotransducible with purE (12 map units). In an apeE-lacZ operon fusion strain, an apeR mutation increases the level of beta-galactosidase approximately 60-fold. We propose that apeR encodes a repressor of apeE. The evidence available suggests that the ApeE protein is not a protease.

Esterases↗
PubMed1994

Cloning and nucleotide sequence of the cyclic AMP receptor protein-regulated Salmonella typhimurium pepE gene and crystallization of its product, an alpha-aspartyl dipeptidase.

The Salmonella typhimurium pepE gene, encoding an N-terminal-Asp-specific dipeptidase, has been cloned on pBR328 by complementation of the Asp-Pro growth defect conferred by a pepE mutation. Strains carrying the complementing plasmids greatly overproduce peptidase E. The enzyme has been purified from an extract of such a strain, its N-terminal amino acid sequence has been determined, and crystals suitable for X-ray diffraction have been grown. A new assay using L-aspartic acid p-nitroanilide as a substrate has been used to determine the pH optimum (approximately 7.5) and to test the effect of potential inhibitors. Insertions of transposon gamma delta (Tn1000) into one of the plasmids have been used to localize the gene and as sites for priming sequencing reactions. The nucleotide sequence of a 1,088-bp region of one of these plasmids has been determined. This sequence contains an open reading frame that predicts a 24.8-kDa protein with an N-terminal sequence that agrees with that determined for peptidase E. The predicted peptidase E amino acid sequence is not similar to that of any other known protein. The nucleotide sequence of the region upstream from pepE contains a promoter with a cyclic AMP receptor protein (CRP) site, and the effects of growth medium and of a crp mutation on expression of a pepE-lacZ fusion indicate that pepE is a member of the CRP regulon. The unique specificity of peptidase E and its lack of sequence similarity to any other peptidase suggest that this enzyme may be the prototype of a new class of peptidases. Its regulation by CPR and its specificity suggest that the enzyme may play a role in allowing the cell to use peptide aspartate to spare carbon otherwise required for the synthesis of the aspartate family of amino acids.

Amino Acid Sequence↗
PubMed1994

The ultrasonic assessment of osteopenia as defined by dual X-ray absorptiometry.

Dual X-ray absorptiometry (DXA) studies of bone mineral density (BMD) of the lumbar spine and femoral neck were compared with measurements of broadband ultrasonic attenuation (BUA) and velocity of ultrasound (VOS) in the calcaneus in 300 pre- and postmenopausal women (mean age 53 years). The women were referred for evaluation of possible osteopenia as defined by DXA. The ability of ultrasound measurements to predict osteopenia in women was compared with the ability of lumbar spine and femoral neck DXA scans to predict osteopenia in the hip and spine. A new ultrasound parameter obtained by combining BUA and VOS (combined attenuation and velocity (CAV)) was also evaluated. Linear regression analysis of the three ultrasound parameters and lumbar spine and femoral neck BMD gave weak but statistically significant correlations (r = 0.45-0.54). The correlation between spine and femoral neck BMD was statistically significantly better (r = 0.72). Receiver-operating characteristic (ROC) analysis was used to investigate the sensitivity and specificity of ultrasound measurements in predicting patients with osteopenia. The areas under the ROC curves ranged from 0.64 to 0.75 and ultrasound parameters were shown to be poor at predicting osteopenia as defined by DXA. The ability of lumbar spine and femoral neck DXA measurement to predict osteopenia in the hip and spine, respectively, was statistically significantly better than any of the ultrasound parameters. Ultrasound measurements in the calcaneus did not appear to identify accurately patients with osteopenia defined by DXA measurements of bone density in the axial and appendicular skeleton.

Absorptiometry, Photon↗
PubMed1994

Should broadband ultrasonic attenuation be normalized for the width of the calcaneus?

Broadband ultrasonic attenuation (BUA) is a measure of ultrasound transmission through the calcaneus that is dependent on bone thickness as well as the density of scattering centres. This report examines whether the normalization of BUA (units dB MHz-1) for calcaneal width (nBUA: units dB MHz-1mm-1) improves the discrimination of clinical studies. BUA and calcaneal width were measured in 200 women using a contact ultrasound (CUBA-Research) system and nBUA evaluated by dividing BUA by bone width. 150 subjects were early post-menopausal and the remaining 50 were osteoporotic women with confirmed vertebral crush fracture. The ability of BUA and nBUA to differentiate between the two groups of subjects was compared using receiver operating characteristic (ROC) analysis. The areas (and standard errors) under the ROC curves were 0.878 (0.033) for BUA and 0.910 (0.028) for nBUA. The difference (and standard error) between the areas under the ROC curves was 0.033 (0.026) and was not statistically significant.

Aged↗
PubMed1994

The far lateral/combined supra- and infratentorial approach. A human cadaveric prosection model for routes of access to the petroclival region and ventral brain stem.

A far lateral approach to the ventral brain stem, lower clivus, and anterior foramen magnum is described. Methods for further exposure of the superior petroclival region by incorporating a subtemporal craniotomy and posterior petrosectomy are also demonstrated. Eight sequentially illustrated steps depict this technique. The far lateral/combined supra- and infratentorial exposure is a comprehensive surgical approach that provides direct access to the entire anterior and lateral brain stem and craniovertebral junction. It minimizes brain-stem retraction and maximizes visualization of the neurovascular structures.

Adipose Tissue↗