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C E Ford

Publications and source records attributed to C E Ford.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1996

Design, synthesis, and evaluation of nonpeptidic inhibitors of human rhinovirus 3C protease.

The design, synthesis, and biological evaluation of reversible, nonpeptidic inhibitors of human rhinovirus (HRV) 3C protease (3CP) are reported. A novel series of 2,3-dioxindoles (isatins) were designed that utilized a combination of protein structure-based drug design, molecular modeling, and structure-activity relationship (SAR). The C-2 carbonyl of isatin was envisioned to react in the active site of HRV 3CP with the cysteine responsible for catalytic proteolysis, thus forming a stabilized transition state mimic. Molecular-modeling experiments using the apo crystal structure of human rhinovirus-serotype 14 (HRV-14) 3CP and a peptide substrate model allowed us to design recognition features into the P1 and P2 subsites, respectively, from the 5- and 1-positions of isatin. Attempts to optimize recognition properties in the P1 subsite using SAR at the 5-position were performed. In addition, a series of ab initio calculations were carried out on several 5-substituted isatins to investigate the stability of sulfide adducts at C-3. The inhibitors were prepared by general synthetic methods, starting with commercially available 5-substituted isatins in nearly every case. All compounds were tested for inhibition of purified HRV-14 3CP. Compounds 8, 14, and 19 were found to have excellent selectivity for HRV-14 3CP compared to other proteolytic enzymes, including chymotrypsin and cathepsin B. Selected compounds were assayed for antiviral activity against HRV-14-infected HI-HeLa cells. A 2.8 A cocrystal structure of derivative 19 covalently bound to human rhinovirus-serotype 2 (HRV-2) 3CP was solved and revealed that the isatin was situated in essentially the same conformation as modeled.

3C Viral Proteases↗
PubMed1996

Blood pressure and end-stage renal disease in men.

BACKGROUND: End-stage renal disease in the United States creates a large burden for both individuals and society as a whole. Efforts to prevent the condition require an understanding of modifiable risk factors. METHODS: We assessed the development of end-stage renal disease through 1990 in 332,544 men, 35 to 57 years of age, who were screened between 1973 and 1975 for entry into the Multiple Risk Factor Intervention Trial (MRFIT). We used data from the national registry for treated end-stage renal disease of the Health Care Financing Administration and from records on death from renal disease from the National Death Index and the Social Security Administration. RESULTS: During an average of 16 years of follow-up, 814 subjects either died of end-stage renal disease or were treated for that condition (15.6 cases per 100,000 person-years of observation). A strong, graded relation between both systolic and diastolic blood pressure and end-stage renal disease was identified, independent of associations between the disease and age, race, income, use of medication for diabetes mellitus, history of myocardial infarction, serum cholesterol concentration, and cigarette smoking. As compared with men with an optimal level of blood pressure (systolic pressure < 120 mm Hg and diastolic pressure < 80 mm Hg), the relative risk of end-stage renal disease for those with stage 4 hypertension (systolic pressure > or = 210 mm Hg or diastolic pressure > or = 120 mm Hg) was 22.1 (P < 0.001). These relations were not due to end-stage renal disease that occurred soon after screening and, in the 12,866 screened men who entered the MRFIT study, were not changed by taking into account the base-line serum creatinine concentration and urinary protein excretion. The estimated risk of end-stage renal disease associated with elevations of systolic pressure was greater than that linked with elevations of diastolic pressure when both variables were considered together. CONCLUSIONS: Elevations of blood pressure are a strong independent risk factor for end-stage renal disease; interventions to prevent the disease need to emphasize the prevention and control of both high-normal and high blood pressure.

Adult↗
PubMed1996

Rationale and design for the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). ALLHAT Research Group.

Are newer types of antihypertensive agents, which are currently more costly to purchase on average, as good or better than diuretics in reducing coronary heart disease incidence and progression? Will lowering LDL cholesterol in moderately hypercholesterolemic older individuals reduce the incidence of cardiovascular disease and total mortality? These important medical practice and public health questions are to be addressed by the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), a randomized, double-blind trial in 40,000 high-risk hypertensive patients. ALLHAT is designed to determine whether the combined incidence of fatal coronary heart disease (CHD) and nonfatal myocardial infarction differs between persons randomized to diuretic (chlorthalidone) treatment and each of three alternative treatments--a calcium antagonist (amlodipine), an angiotensin converting enzyme inhibitor (lisinopril), and an alpha-adrenergic blocker (doxazosin). ALLHAT also contains a randomized, open-label, lipid-lowering trial designed to determine whether lowering LDL cholesterol in 20,000 moderately hypercholesterolemic patients (a subset of the 40,000) with a 3-hydroxymethylglutaryl coenzyme A (HMG CoA) reductase inhibitor, pravastatin, will reduce all-cause mortality compared to a control group receiving "usual care." ALLHAT's main eligibility criteria are: 1) age 55 or older; 2) systolic or diastolic hypertension; and 3) one or more additional risk factors for heart attack (eg, evidence of atherosclerotic disease or type II diabetes). For the lipid-lowering trial, participants must have an LDL cholesterol of 120 to 189 mg/dL (100 to 129 mg/dL for those with known CHD) and a triglyceride level below 350 mg/dL. The mean duration of treatment and follow-up is planned to be 6 years. Further features of the rationale, design, objectives, treatment program, and study organization of ALLHAT are described in this article.

Antihypertensive Agents↗
PubMed1994

Signaling-induced association of a tyrosine-phosphorylated 36-kDa protein with p50csk.

The protein-tyrosine kinase, p50csk, is thought to participate in the regulation of signal transduction pathways by catalyzing the phosphorylation of the Src-related protein-tyrosine kinases on a negative regulatory tyrosine residue located near the COOH terminus. To study possible mechanisms by which the activity of p50csk might be regulated, we searched for p50csk-interacting proteins in human erythroleukemia cells. We found that in response to the treatment of cells with pervanadate, a potent inhibitor of protein tyrosine phosphatases, or to the cross-linking of Fc gamma RIIA receptors, p50csk becomes tightly associated with a 36-kDa protein (p36). This association is dependent on the tyrosine phosphorylation of p36 and involves its interaction with the SH2 domain of p50csk.p36 can be phosphorylated in vitro by p50csk or by a full-length GST-Csk fusion protein expressed in Escherichia coli. Tyrosine-phosphorylated p36 is found exclusively in the particulate membrane fraction of the cell. Conditions that induce the formation of the p50csk.p36 complex promote the appearance of p50csk in the particulate fraction. These data suggest that the association between p50csk and p36 serves to translocate the normally cytosolic p50csk to the membrane, where it presumably interacts with its physiologically relevant substrates.

Animals↗
PubMed1992

Myocardial beta-adrenergic receptor expression and signal transduction after chronic volume-overload hypertrophy and circulatory congestion.

BACKGROUND: The volume-overload, high-output state induced by aortocaval fistula is unique because it is not generally associated with marked abnormalities of contractile function. Thus, changes in beta-adrenergic receptor (beta AR) expression should reflect more directly the influence of neurohumoral adrenergic tone, clarifying the manner in which peripheral (neurohumoral) versus primary myocardial factors are operative in decreased beta AR-dependent signal transduction. METHODS AND RESULTS: We examined the beta-adrenergic receptor-responsive adenylyl cyclase pathway in hearts from pigs subjected to volume-overload hypertrophy with circulatory congestion. Nine pigs underwent initial pharmacological and hemodynamic studies, and, 5 weeks after aortocaval fistula placement, when signs of circulatory congestion were evident, these measurements were repeated. Biochemical analyses of plasma and myocardium from these animals and seven normal animals were compared. Experimental animals showed signs of circulatory congestion (tachypnea, weight gain, pulmonary rales) within 3-4 weeks of fistula placement. Necropsy showed ascites and biventricular cardiac hypertrophy, but no fibrosis or inflammation was present on histological inspection. Heart rate responsiveness to beta AR stimulation was blunted, with ED50, for isoproterenol increased 133% (p less than 0.001) after development of circulatory congestion. Biochemical analyses of the beta AR-responsive adenylyl cyclase pathway showed uniform decreases in beta AR number in right atrium, right ventricle, and left ventricle (36-41% decreases, p less than 0.005). Downregulation was selective for beta 1-receptors, and remaining receptors in the right and left ventricles showed low-affinity agonist binding, suggesting an uncoupling from Gs. All measures of adenylyl cyclase activity were diminished significantly in membrane homogenates from the right atrium (mean reduction, 50 +/- 10%) and left ventricle (mean reduction, 44 +/- 8%) after volume overload. Finally, we found that amounts of cardiac Gs, as measured in reconstitution assays, were decreased in both the right atrium (p less than 0.02) and the left ventricle (p less than 0.01) of volume-overloaded animals but that levels of pertussis toxin substrate were unchanged. CONCLUSIONS: Biochemical findings occurred in the absence of myocardial inflammation or fibrosis and without pharmacological interventions, suggesting that circulatory congestion, with attendant elevation in plasma norepinephrine, may be a sufficient stimulus to induce such changes. The data are compatible with a catecholamine-driven beta AR pathway desensitization. Thus, a primary defect in intrinsic contractile function is not a necessary component for abnormalities of the myocardial beta AR-responsive adenylyl cyclase pathway.

Adenylyl Cyclases↗
PubMed1992

Myocardial adrenergic denervation supersensitivity depends on a postreceptor mechanism not linked with increased cAMP production.

BACKGROUND: Two major hypotheses have been proposed to explain catecholamine supersensitivity after myocardial denervation, but neither sufficiently explains certain features of the phenomenon. In addition, a nonsurgical method for long-term myocardial adrenergic denervation is desirable but has not been accomplished or described with respect to catecholamine supersensitivity. METHODS AND RESULTS: We have accomplished chronic myocardial adrenergic denervation by using 6-hydroxydopamine (6-OHDA). Sixteen weeks after 6-OHDA administration to newborn pigs, we found substantial myocardial adrenergic denervation associated with beta-adrenergic receptor (beta AR) downregulation. Despite decreased beta AR number, the dose of isoproterenol yielding 50% maximal heart rate change (ED50) was decreased, and heart rates during exercise showed increased responsiveness despite decreased circulating catecholamines. Thus, stimulation of fewer receptors yielded an increased response, implying improved signal transduction efficiency. Competitive binding studies with isoproterenol showed an increased proportion of beta AR with high-affinity binding in myocardial membranes from 6-OHDA pigs, suggesting that interaction between beta AR and cardiac G, may contribute to improved signal transduction efficiency. However, measures of adenylyl cyclase activity indicated marked reduction in beta AR-dependent and G2-dependent cAMP production in myocardial membranes from denervated animals despite a normal amount of cardiac Gs and decreased Gi. CONCLUSIONS: We have demonstrated that substantial, long-term myocardial adrenergic denervation is possible using 6-OHDA. Denervation supersensitivity in this model does not depend on enhanced cAMP stimulation but rather depends on postreceptor elements in the beta AR-responsive pathway that may be independent of Gs-activated adenylyl cyclase activity. In this model of adrenergic denervation supersensitivity, beta-receptors, through Gs, may be linked to an alternative effector that drives heart rate responsiveness.

Adenylyl Cyclases↗
PubMed1991

Why do lean hypertensives have higher mortality rates than other hypertensives? Findings of the Hypertension Detection and Follow-up Program.

Specific causes of death were analyzed for 10,908 participants in the Hypertension Detection and Follow-up Program, to explore possible explanations for the observed excess 8.3-year mortality from all causes in hypertensives with low body mass. Although the cardiovascular mortality rate among men in the lowest decile of body mass (body mass index 21.96 or less) was 50% higher than that of men in the median class (body mass index 26.4-28.8), death rate for noncardiovascular deaths was more than 2 1/2 times higher in men with lean versus median body mass. The pattern was similar among women. Among noncardiovascular causes, striking differences in mortality rates between lean hypertensives and those of average body mass were observed for cirrhotic death (relative risk of 12+ in men and 11+ in women), for nonmalignant respiratory disease in men (relative risk of 7+), for violent death (both sexes), and for malignant neoplasms in men. Prevalence of smoking was almost twice as high in the lowest compared with the median body mass group; among the lean, excess deaths, particularly noncardiovascular deaths, were concentrated among smokers. Thus, male smokers in the lowest decile of body mass constituted only 3% of the study population, but contributed 8% of all deaths, 11% of all noncardiovascular deaths, and 22% of all cirrhotic deaths. A larger proportion of deaths occurred early in follow-up in the lean versus other hypertensives, suggesting occult disease among the lean at baseline. There was no evidence that more severe or treatment-resistant hypertension was present in or could explain excess mortality among the hypertensives with low body mass. The inference from the findings is not that overweight is protective for hypertensives nor that excess risk is due to leanness per se. Rather, a reasonable hypothesis, particularly from findings on specific causes of death, is that excess mortality in lean hypertensives is due to deleterious lifestyles, particularly smoking and excess alcohol intake, contributing to both leanness and risk of death.

Adult↗
PubMed1989

Prognostic value of serum creatinine and effect of treatment of hypertension on renal function. Results from the hypertension detection and follow-up program. The Hypertension Detection and Follow-up Program Cooperative Group.

The Hypertension Detection and Follow-up Program followed up 10,940 persons for 5 years in a community-based, randomized, controlled trial of treatment for hypertension. Participants were randomized to one of two treatment groups, stepped care and referred care. The primary end point of the study was all-cause mortality, with morbid events involving the heart, brain, and kidney as secondary end points. Loss of renal function, ascertained by a change in serum creatinine, was among these secondary events. Baseline serum creatinine concentration had a significant prognostic value for 8-year mortality. For persons with a serum creatinine concentration greater than or equal to 1.7 mg/dl, 8-year mortality was more than three times that of all other participants. The estimated 5-year incidence of substantial decline in renal function was 21.7/1,000 in the stepped-care group and 24.6/1,000 in the referred-care group. Among persons with a baseline serum creatinine level between 1.5 and 1.7 mg/dl, the 5-year incidence of decline was 113.3/1,000 (stepped care) and 226.6/1,000 (referred care) (p less than 0.01). The incidence of decline in renal function was greater in men, blacks, and older adults, as well as in those with higher entry diastolic blood pressure. Among persons with a baseline serum creatinine level greater than or equal to 1.7 mg/dl, serum creatinine concentration declined by 25% or more in 28.6% of stepped-care and 25.2% of referred-care participants. Although the incidence of clinically significant hypercreatininemia in a hypertensive population is low, an elevated serum creatinine concentration is a very potent independent risk factor for mortality. The slightly lower rate of development of hypercreatininemia and the higher rate of improvement in stepped-care compared with referred-care participants is consistent with the belief that aggressive treatment of hypertension may reduce renal damage and the associated increased risk of death.

Adult↗
PubMed1987

Recruitment in the hypertension detection and follow-up program.

The Hypertension Detection and Follow-up Program (HDFP), through a two-stage population-based screen for high blood pressure involving over 159,000 persons in 14 U.S. communities, recruited and randomized 11,386 participants. The design initially called for the recruitment of 800-1000 hypertensive individuals per clinic over a 9-month period. The size of the population to be screened was based on an estimated 15% of the general population being age and blood pressure (BP) eligible. All adults 30-69 years of age in defined populations were to be screened, with efforts to enroll into the trial all who met the BP eligibility criteria. Recruitment was carried out by interviewers who enumerated households and screened age-eligible individuals for elevated BP; those meeting BP criteria were invited to a clinic screen for confirmation. Of those persons enumerated, 179,239 were age eligible, and 159,566 of these had home BP measurements. The home screening yielded 22,994 persons who had a diastolic BP at or above 95 mm Hg, and 17,499 attended the clinic screen. At the clinic screen, 11,386 had diastolic BP at or above 90 mm Hg and were randomized into one of two treatment groups. The enumeration goal, and the recruitment yield and cost varied by clinic, primarily due to different characteristics of the defined populations. Overall, the target population approximated U.S. demographic characteristics except that a larger proportion of blacks was included. Because of generally good response rates, the randomized study population was representative of similarly aged hypertensive persons in the target populations. The recruitment results suggest that a population-based screening program for a high prevalence condition such as hypertension is an effective mode of recruitment, particularly when a population-based sample is required.

Adult↗
PubMed1987

Presumptive mosaic origin of an XX/XY female with ambiguous genitalia.

A child with ambiguous genitalia had an XX/XY karyotype in all tissues examined. Analyses of 11 informative polymorphisms, both chromosomal and genetic (Rh and HLA), showed no difference between the two cell lines. It is unlikely that the child originated from fertilisation of the egg and the second polar body by two sperms; therefore, we hypothesise that the child originated from an XXY zygote after mitotic errors during cleavage. Recent findings of differences in the chromosome constitution between the extra-embryonic tissues and the fetus support this view.

Disorders of Sex Development↗
PubMed1986

Long-latency auditory event-related potentials in epilepsy.

Long latency auditory event-related potentials have been shown to change in patients with cerebral dysfunction. Some seizure patients with no evidence of brain damage or mental retardation show altered interictal cognitive and memory function. Long-latency auditory event-related potentials to tone stimulation were recorded in nineteen control subjects and seventeen patients with complex partial or partial and secondarily generalized seizures who had no evidence of brain damage, retardation, or drug intoxication, and whose seizures were controlled when studied. The latencies of N2 and P3 components were significantly longer in seizure patients than control subjects, and the P3 waveform was significantly greater in amplitude in epileptics. These findings suggest that cognitive event-related potentials are affected by partial epilepsy. The changes may be related to the recently reported involvement of the hippocampus in ERP generation, or to loss or alteration of modulatory functions, possibly cholinergic in nature, in the temporal lobe consequent upon epileptogenesis.

Adult↗
PubMed1985

Learned helplessness and judgments of control.

One of the central hypotheses of learned helplessness theory is that exposure to noncontingency produces a reduced ability to perceive response-outcome relations (the postulated "cognitive deficit"). To test this hypothesis, subjects were exposed to a typical helplessness induction task and then asked to make judgments of the amount of control their responses exerted over a designated outcome (the onset of a light). Support for the postulated cognitive deficit would be found if subjects who experienced the induction underestimated the relation between their responses and outcomes. The results, however, demonstrated that induction subjects (n = 30) made higher and more accurate judgments of control than subjects in a no-treatment control group (n = 30). This finding clearly fails to support the postulated cognitive deficit and highlights the need for other direct tests of the basic hypotheses of helplessness theory.

Cognition↗
PubMed1985

Ascertainment of vital status through the National Death Index and the Social Security Administration.

Ascertainment of the vital status of individuals is of central importance to epidemiologic studies which monitor mortality as an end point. Utilizing identifying information collected in 1973-1974, the Hypertension Detection and Follow-up Program, a prospective, multicenter study, followed 25,362 individuals to determine eight-year mortality. In the most recent follow-up, there were 617 individuals whose vital status was not known. Available identifying information on these and on all 1,322 participants known to have died in 1979-1981 was submitted to the National Death Index (NDI) for possible confirmation of vital status. A subset of individuals who had Social Security numbers (490 lost to follow-up and 1,154 known deaths) was also submitted to the Social Security Administration (SSA). The NDI correctly identified 87.0% of the known deaths. Of the 1,154 known deaths (those with known Social Security numbers) submitted to both agencies, the NDI identified 93.1% and the SSA 83.6%. Significant variations by race and sex were noted in the identification rates, in part because of Social Security number discrepancies. False matches through the NDI matching process occurred for 10.4% of the known deaths. In the more restrictive SSA search, only 0.5% false matches resulted. For those lost to follow-up, vital status was ascertained in 57.1%. This paper describes the relative efficacy and attributes of the use of these systems to ascertain vital status.

Aged↗