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Biomedical subjects

C E Ford

Publications and source records attributed to C E Ford.

At least 19 recordsLinked to original sources
PubMed2003

Statistical validation of a commonly used method for personnel dosimetry issuance determinations.

In 1992, the federal requirements for personnel monitoring of occupational radiation doses were modified, making monitoring compulsory only for individuals "likely" to exceed 10% of the applicable annual dose limits. This regulatory change served as a catalyst for many radiation protection programs to re-evaluate their personnel monitoring issuance criteria to determine if some monitoring services might be reduced or eliminated. But in the absence of any clear definition of the term "likely," radiation protection programs relied on adjustments largely based on reviews of previous monitoring results and professional judgment. Although such semi-quantitative assessments may have been appropriate, the approach was not without inherent programmatic risks, as radiation dosimetry programs have been shown to be a consistent source of regulatory non-compliance upon inspection and serve as essential elements in defense against litigation efforts purporting workplace-related radiation injury. The objective of this study was to subject this commonly used method for post-regulatory change dosimetry issuance determinations to statistical validation. Personnel monitoring data from The University of Texas Health Science Center at Houston Radiation Safety Program pre- and post-1992 regulatory changes were accessed and descriptively analyzed. The dynamic nature of the institutional environment made direct comparisons of individuals between years impractical, so 1990 mean dose levels for various independent variables were compared using the Kruskal-Wallis non-parametric ANOVA test at a significance level of alpha = 0.05. The data from 1998 were then analyzed to ascertain if the groupings identified as statistically different in 1990 were still being monitored. The analyses statistically validated the monitoring program reductions made by the University of Texas Health Science Center at Houston radiation protection program. In addition, statistical support for further monitoring program reductions were identified, if such reductions were deemed to be necessary in the future.

Government Agencies↗
PubMed2002

Pharmacogenetic approaches to hypertension therapy: design and rationale for the Genetics of Hypertension Associated Treatment (GenHAT) study.

The Genetics of Hypertension Associated Treatment (GenHAT) study will determine whether variants in hypertension susceptibility genes interact with antihypertensive medication to modify coronary heart disease (CHD) risk in hypertensives. GenHAT is an ancillary study of the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial, ALLHAT, a double-blind, randomized trial of 42 418 hypertensives, 55 years of age or older, with systolic or diastolic hypertension and one or more risk factors for cardiovascular disease. About 50% are non-white, and about half are female. ALLHAT completes follow-up in March 2002. GenHAT is typing variants in hypertension genes; completion of genotyping is scheduled for 2003. Analysis of gene-treatment interactions in relation to outcomes include CHD, stroke, heart failure, and blood pressure lowering. To our knowledge, GenHAT is the largest pharmacogenetic study ever conducted. An added strength is its ability to link gene-treatment interactions with important clinical outcomes across diverse ethnic and gender groups.

Humans↗
PubMed2001

Design and synthesis of irreversible depsipeptidyl human rhinovirus 3C protease inhibitors.

Novel tripeptidyl C-terminal Michael acceptors with an ester replacement of the P(2)-P(3) amide bond were investigated as irreversible inhibitors of the human rhinovirus (HRV) 3C protease (3CP). When screened against HRV serotype-14 the best compound was shown to have very good 3CP inhibition (k(obs)/[I]=270,000M(-1)s(-1)) and potent in vitro antiviral activity (EC(50)=7.0nM).

3C Viral Proteases↗
PubMed2001

Operational aspects of terminating the doxazosin arm of The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT).

The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) is a randomized, practice-based trial sponsored by the National Heart, Lung, and Blood Institute (NHLBI). The double-blind, active-controlled component of ALLHAT was designed to determine whether the rate of the primary outcome-a composite of fatal coronary heart disease and nonfatal myocardial infarction-differs between diuretic (chlorthalidone) treatment and each of three other classes of antihypertensive drugs: a calcium antagonist (amlodipine), an angiotensin-converting enzyme inhibitor (lisinopril), and an alpha-adrenergic blocker (doxazosin) in high-risk hypertensive persons ages 55 years and older. In addition, 10,377 ALLHAT participants with mild to moderate hypercholesterolemia were also enrolled in a randomized, open-label trial designed to determine whether lowering serum LDL cholesterol with an HMG CoA reductase inhibitor (pravastatin) will reduce all-cause mortality as compared to a control group receiving "usual care." In January 2000, an independent data review committee recommended discontinuing the doxazosin treatment arm. The NHLBI director promptly accepted the recommendation. This article discusses the steps involved in the orderly closeout of one arm of ALLHAT and the dissemination of trial results. These steps included provisional preparations; the actual decision process; establishing a timetable; forming a transition committee; preparing materials and instructions; informing 65 trial officers and coordinators, 628 active clinics and satellite locations, 313 institutional review boards, over 42,000 patients, and the general public; reporting detailed trial results; and monitoring the closeout process. Control Clin Trials 2001;22:29-41

Adverse Drug Reaction Reporting Systems↗
PubMed2000

Substituted benzamide inhibitors of human rhinovirus 3C protease: structure-based design, synthesis, and biological evaluation.

A series of nonpeptide benzamide-containing inhibitors of human rhinovirus (HRV) 3C protease was identified using structure-based design. The design, synthesis, and biological evaluation of these inhibitors are reported. A Michael acceptor was combined with a benzamide core mimicking the P1 recognition element of the natural 3CP substrate. alpha,beta-Unsaturated cinnamate esters irreversibly inhibited the 3CP and displayed antiviral activity (EC(50) 0.60 microM, HRV-16 infected H1-HeLa cells). On the basis of cocrystal structure information, a library of substituted benzamide derivatives was prepared using parallel synthesis on solid support. A 1.9 A cocrystal structure of a benzamide inhibitor in complex with the 3CP revealed a binding mode similar to that initially modeled wherein covalent attachment of the nucleophilic cysteine residue is observed. Unsaturated ketones displayed potent reversible inhibition but were inactive in the cellular antiviral assay and were found to react with nucleophilic thiols such as DTT.

3C Viral Proteases↗
PubMed2000

Area income as a predictor of preventable hospitalizations in the Harris County Hospital District, Houston.

This study assesses whether geographical area income based on census data is a good predictor of preventable (or ambulatory care-sensitive) hospitalizations in a large public hospital system in Texas, and how area income correlates with the socioeconomic status reported by patients. Documenting a correspondence between area and individual-level income, as well as meaningful variation in rates of avoidable hospitalizations across subgroups and areas with varying concentrations of low-income persons, points to the validity and utility of this approach for monitoring how well public hospital systems in Texas address the needs of those they most directly serve. Area income may not fully reflect the disproportionately lower socioeconomic status of patients seen in the public hospital system. Nonetheless, living in lower-income zip codes was associated with higher preventable hospitalization rates for the predominantly low-income population served by the public hospital system. A tenfold difference found in the adjusted rates of hospitalizations for preventable conditions compared with control (or marker) conditions among persons living in low-income areas signals the likelihood of substantial unmet needs in this population. Small-area analysis and related comparisons of rates of preventable hospitalizations in high- and low-income areas provide useful indicators for monitoring and assessing the performance of public hospital systems in Texas.

Ambulatory Care↗
PubMed1999

Structure-assisted design of mechanism-based irreversible inhibitors of human rhinovirus 3C protease with potent antiviral activity against multiple rhinovirus serotypes.

Human rhinoviruses, the most important etiologic agents of the common cold, are messenger-active single-stranded monocistronic RNA viruses that have evolved a highly complex cascade of proteolytic processing events to control viral gene expression and replication. Most maturation cleavages within the precursor polyprotein are mediated by rhinovirus 3C protease (or its immediate precursor, 3CD), a cysteine protease with a trypsin-like polypeptide fold. High-resolution crystal structures of the enzyme from three viral serotypes have been used for the design and elaboration of 3C protease inhibitors representing different structural and chemical classes. Inhibitors having alpha,beta-unsaturated carbonyl groups combined with peptidyl-binding elements specific for 3C protease undergo a Michael reaction mediated by nucleophilic addition of the enzyme's catalytic Cys-147, resulting in covalent-bond formation and irreversible inactivation of the viral protease. Direct inhibition of 3C proteolytic activity in virally infected cells treated with these compounds can be inferred from dose-dependent accumulations of viral precursor polyproteins as determined by SDS/PAGE analysis of radiolabeled proteins. Cocrystal-structure-assisted optimization of 3C-protease-directed Michael acceptors has yielded molecules having extremely rapid in vitro inactivation of the viral protease, potent antiviral activity against multiple rhinovirus serotypes and low cellular toxicity. Recently, one compound in this series, AG7088, has entered clinical trials.

3C Viral Proteases↗
PubMed1999

Structure-based design of irreversible, tripeptidyl human rhinovirus 3C protease inhibitors containing N-methyl amino acids.

Tripeptide-derived molecules incorporating N-methyl amino acid residues and C-terminal Michael acceptor moieties were evaluated as irreversible inhibitors of the cysteine-containing human rhinovirus 3C protease (3CP). Such compounds displayed good 3CP inhibition activity (k(obs)/[I] up to 610,000 M(-1) s(-1)) and potent in vitro antiviral properties (EC50 approaching 0.03 microM) when tested against HRV serotype-14.

3C Viral Proteases↗
PubMed1999

Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. 3. Structure-activity studies of ketomethylene-containing peptidomimetics.

The structure-based design, chemical synthesis, and biological evaluation of various ketomethylene-containing human rhinovirus (HRV) 3C protease (3CP) inhibitors are described. These compounds are comprised of a peptidomimetic binding determinant and an ethyl propenoate Michael acceptor moiety which forms an irreversible covalent adduct with the active site cysteine residue of the 3C enzyme. The ketomethylene-containing inhibitors typically display slightly reduced 3CP inhibition activity relative to the corresponding peptide-derived molecules, but they also exhibit significantly improved antiviral properties. Optimization of the ketomethylene-containing compounds is shown to provide several highly active 3C protease inhibitors which function as potent antirhinoviral agents (EC90 = <1 microM) against multiple virus serotypes in cell culture.

3C Viral Proteases↗
PubMed1999

Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. 4. Incorporation of P1 lactam moieties as L-glutamine replacements.

The structure-based design, chemical synthesis, and biological evaluation of various human rhinovirus (HRV) 3C protease (3CP) inhibitors which incorporate P1 lactam moieties in lieu of an L-glutamine residue are described. These compounds are comprised of a tripeptidyl or peptidomimetic binding determinant and an ethyl propenoate Michael acceptor moiety which forms an irreversible covalent adduct with the active site cysteine residue of the 3C enzyme. The P1-lactam-containing inhibitors display significantly increased 3CP inhibition activity along with improved antirhinoviral properties relative to corresponding L-glutamine-derived molecules. In addition, several lactam-containing compounds exhibit excellent selectivity for HRV 3CP over several other serine and cysteine proteases and are not appreciably degraded by a variety of biological agents. One of the most potent inhibitors (AG7088, mean antirhinoviral EC90 approximately 0.10 microM, n = 46 serotypes) is shown to warrant additional preclinical development to explore its potential for use as an antirhinoviral agent.

3C Viral Proteases↗
PubMed1999

Solid-phase synthesis of irreversible human rhinovirus 3C protease inhibitors. Part 1: Optimization of tripeptides incorporating N-terminal amides.

The optimization of a series of irreversible human rhinovirus (HRV) 3C protease (3CP) inhibitors is described. These inhibitors are comprised of an L-Leu-L-Phe-L-Gln tripeptide containing an N-terminal amide moiety and a C-terminal ethyl propenoate Michael acceptor. Examination of approximately 500 compounds with varying N-terminal amides utilizing solid-phase synthesis and high-throughput assay techniques is described along with the solution phase preparation of several highly active molecules. A tripeptide Michael acceptor containing an N-terminal amide derived from 5-methylisoxazole-3-carboxylic acid is shown to exhibit potent, irreversible anti-3CP activity (k(obs)/[I] = 260,000 M(-1) s(-1); type-14 3CP) and broad-spectrum antirhinoviral properties (average EC50 = 0.47 microM against four different HRV serotypes).

3C Viral Proteases↗
PubMed1999

In vitro antiviral activity of AG7088, a potent inhibitor of human rhinovirus 3C protease.

AG7088 is a potent, irreversible inhibitor of human rhinovirus (HRV) 3C protease (inactivation rate constant (k(obs)/[I]) = 1,470,000 +/- 440,000 M(-1) s(-1) for HRV 14) that was discovered by protein structure-based drug design methodologies. In H1-HeLa and MRC-5 cell protection assays, AG7088 inhibited the replication of all HRV serotypes (48 of 48) tested with a mean 50% effective concentration (EC(50)) of 0.023 microM (range, 0.003 to 0.081 microM) and a mean EC(90) of 0.082 microM (range, 0.018 to 0.261 microM) as well as that of related picornaviruses including coxsackieviruses A21 and B3, enterovirus 70, and echovirus 11. No significant reductions in the antiviral activity of AG7088 were observed when assays were performed in the presence of alpha(1)-acid glycoprotein or mucin, proteins present in nasal secretions. The 50% cytotoxic concentration of AG7088 was >1,000 microM, yielding a therapeutic index of >12,346 to >333,333. In a single-cycle, time-of-addition assay, AG7088 demonstrated antiviral activity when added up to 6 h after infection. In contrast, a compound targeting viral attachment and/or uncoating was effective only when added at the initiation of virus infection. Direct inhibition of 3C proteolytic activity in infected cells treated with AG7088 was demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of radiolabeled proteins, which showed a dose-dependent accumulation of viral precursor polyproteins and reduction of processed protein products. The broad spectrum of antiviral activity of AG7088, combined with its efficacy even when added late in the virus life cycle, highlights the advantages of 3C protease as a target and suggests that AG7088 will be a promising clinical candidate.

3C Viral Proteases↗
PubMed1999

HIV-related malignancies: community-based study using linkage of cancer registry and HIV registry data.

For people immunosuppressed by human immunodeficiency virus (HIV), we expect an increase in cancer incidence similar to that documented in transplant patients. We examined the cancer spectrum in an HIV-infected cohort, specifically malignancies not currently associated with acquired immunodeficiency syndrome (AIDS), in relation to the general population. Cancer incidence data for residents of Harris County, Texas, diagnosed between 1975 and 1994, were linked to HIV/AIDS registry data by Soundex code and date of birth to identify malignancies in an HIV-infected cohort of 14,986 persons. Incidence of cancer in this cohort was compared to the general population by standardized incidence ratio (SIR) analysis. From the HIV-infected cohort, 2289 persons (15%) were identified as having one or more malignancies, with 97% occurring in males. The linkage alone identified 29.5% of the malignancies, of which only 28.7% were diagnosed in males. Adjusting for age, HIV-infected men and women had incidences of cancer that were 16.7 [95% confidence interval (CI) 16.1-17.3] and 2.9 (95% CI 2.3-3.7) times that expected for the general population of Harris County, Texas. Besides Kaposi's sarcoma, non-Hodgkin's lymphoma, cervix cancer and brain lymphoma, non-AIDS related malignancies of Hodgkin's lymphoma, non-melanotic skin cancer in males and colon cancer in females, exhibited significant SIRs of 5.6 (95% CI 3.6-8.4), 6.9 (95% CI 4.8-9.5) and 4.0 (95% CI 1.1-10.2). Increased incidences of lung, prostate and breast malignancies were not seen in this HIV cohort. Persons infected with HIV appear to be at increased risk for the non-AIDS related malignancies, Hodgkin's lymphoma, non-melanotic skin cancer in males and colon cancer in females.

Adolescent↗
PubMed1998

Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. 1. Michael acceptor structure-activity studies.

The structure-based design, chemical synthesis, and biological evaluation of peptide-derived human rhinovirus (HRV) 3C protease (3CP) inhibitors are described. These compounds incorporate various Michael acceptor moieties and are shown to irreversibly bind to HRV serotype 14 3CP with inhibition activities (kobs/[I]) ranging from 100 to 600 000 M-1 s-1. These inhibitors are also shown to exhibit antiviral activity when tested against HRV-14-infected H1-HeLa cells with EC50's approaching 0.50 microM. Extensive structure-activity relationships developed by Michael acceptor alteration are reported along with the evaluation of several compounds against HRV serotypes other than 14. A 2.0 A crystal structure of a peptide-derived inhibitor complexed with HRV-2 3CP is also detailed.

3C Viral Proteases↗
PubMed1998

Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. 2. Peptide structure-activity studies.

The structure-based design, chemical synthesis, and biological evaluation of various peptide-derived human rhinovirus (HRV) 3C protease (3CP) inhibitors are described. These compounds are comprised of an ethyl propenoate Michael acceptor moiety and a tripeptidyl binding determinant. The systematic modification of each amino acid residue present in the binding determinant as well as the N-terminal functionality is described. Such modifications are shown to provide irreversible HRV-14 3CP inhibitors with anti-3CP activities (kobs/[I]) ranging from 60 to 280 000 M-1 s-1 and antiviral EC50's which approach 0.15 microM. An optimized inhibitor which incorporates several improvements identified by the structure-activity studies is also described. This molecule displays very rapid irreversible inhibition of HRV-14 3CP (kobs/[I] = 800 000 M-1 s-1) and potent antiviral activity against HRV-14 in cell culture (EC50 = 0.056 microM). A 1.9 A crystal structure of an S-alkylthiocarbamate-containing inhibitor complexed with HRV-2 3CP is also detailed.

3C Viral Proteases↗
PubMed1998

Tripeptide aldehyde inhibitors of human rhinovirus 3C protease: design, synthesis, biological evaluation, and cocrystal structure solution of P1 glutamine isosteric replacements.

The investigation of tripeptide aldehydes as reversible covalent inhibitors of human rhinovirus (HRV) 3C protease (3CP) is reported. Molecular models based on the apo crystal structure of HRV-14 3CP and other trypsin-like serine proteases were constructed to approximate the binding of peptide substrates, generate transition state models of P1-P1' amide cleavage, and propose novel tripeptide aldehydes. Glutaminal derivatives have limitations since they exist predominantly in the cyclic hemiaminal form. Therefore, several isosteric replacements for the P1 carboxamide side chain were designed and incorporated into the tripeptide aldehydes. These compounds were found to be potent inhibitors of purified HRV-14 3CP with Kis ranging from 0.005 to 0.64 microM. Several have low micromolar antiviral activity when tested against HRV-14-infected H1-HeLa cells. The N-acetyl derivative 3 was also shown to be active against HRV serotypes 2, 16, and 89. High-resolution cocrystal structures of HRV-2 3CP, covalently bound to compounds 3, 15, and 16, were solved. These cocrystal structures were analyzed and compared with our original HRV-14 3CP-substrate and inhibitor models.

3C Viral Proteases↗
PubMed1998

Molecular basis for interactions of G protein betagamma subunits with effectors.

Both the alpha and betagamma subunits of heterotrimeric guanine nucleotide-binding proteins (G proteins) communicate signals from receptors to effectors. Gbetagamma subunits can regulate a diverse array of effectors, including ion channels and enzymes. Galpha subunits bound to guanine diphosphate (Galpha-GDP) inhibit signal transduction through Gbetagamma subunits, suggesting a common interface on Gbetagamma subunits for Galpha binding and effector interaction. The molecular basis for interaction of Gbetagamma with effectors was characterized by mutational analysis of Gbeta residues that make contact with Galpha-GDP. Analysis of the ability of these mutants to regulate the activity of calcium and potassium channels, adenylyl cyclase 2, phospholipase C-beta2, and beta-adrenergic receptor kinase revealed the Gbeta residues required for activation of each effector and provides evidence for partially overlapping domains on Gbeta for regulation of these effectors. This organization of interaction regions on Gbeta for different effectors and Galpha explains why subunit dissociation is crucial for signal transmission through Gbetagamma subunits.

Adenosine Diphosphate Ribose↗