Biomedical subjects

M Cushman

Publications and source records attributed to M Cushman.

At least 91 records · Page 5Linked to original sources

PubMed1998

Plasma concentration of C-reactive protein and risk of developing peripheral vascular disease.

BACKGROUND: Among apparently healthy men, elevated levels of C-reactive protein (CRP), a marker for systemic inflammation, predict risk of myocardial infarction and thromboembolic stroke. Whether increased levels of CRP are also associated with the development of symptomatic peripheral arterial disease (PAD) is unknown. METHODS AND RESULTS: Using a prospective, nested, case-control design, we measured baseline levels of CRP in 144 apparently healthy men participating in the Physicians' Health Study who subsequently developed symptomatic PAD (intermittent claudication or need for revascularization) and in an equal number of control subjects matched on the basis of age and smoking habit who remained free of vascular disease during a follow-up period of 60 months. Median CRP levels at baseline were significantly higher among those who subsequently developed PAD (1.34 versus 0.99 mg/L; P=.04). Furthermore, the risks of developing PAD increased significantly with each increasing quartile of baseline CRP concentration such that relative risks of PAD from lowest (referent) to highest quartile of CRP were 1.0, 1.3, 2.0, and 2.1 (Ptrend=.02). Compared with those with no clinical evidence of disease, the subgroup of case patients who required revascularization had the highest baseline CRP levels (median= 1.75 mg/L; P= .04); relative risks from lowest to highest quartile of CRP for this end point were 1.0, 1.8, 3.8, and 4.1 (Ptrend=.02). Risk estimates were similar after additional control for body mass index, hypercholesterolemia, hypertension, diabetes, and a family history of premature atherosclerosis. CONCLUSIONS: These prospective data indicate that among apparently healthy men, baseline levels of CRP predict future risk of developing symptomatic PAD and thus provide further support for the hypothesis that chronic inflammation is important in the pathogenesis of atherothrombosis.

Adult↗

PubMed1998

Synthesis of a non-nucleoside reverse transcriptase inhibitor in the alkenyldiarylmethane (ADAM) series with optimized potency and therapeutic index.

A novel alkenyldiarylmethane (ADAM) analog has been synthesized with enhanced potency as an anti-HIV agent. The new compound (ADAM II) inhibits the cytopathic effect of HIV-1RF in CEM-SS cells with an EC50 of 13 nM, while it shows cytotoxicity with a CC50 of 31.6 microM, providing a therapeutic index of 2430. ADAM II is a non-nucleoside reverse transcriptase inhibitor, displaying an IC50 of 0.3 microM with poly(rC) oligo(dG) as the template/primer.

Anti-HIV Agents↗

PubMed1998

Synthesis of 2,6-dioxo-(1H,3H)-9-N-ribitylpurine and 2,6-dioxo-(1H,3H)-8-aza-9-N-ribitylpurine as inhibitors of lumazine synthase and riboflavin synthase.

2,6-Dioxo-(1H,3H)-9-N-ribitylpurine (6) and 2,6-dioxo-(1H,3H)-8-aza-9-N-ribitylpurine (7) have been synthesized and evaluated as inhibitors of lumazine synthase and riboflavin synthase. Reaction of 5-amino-6-ribitylaminouracil hydrochloride (8) with diethoxymethyl acetate (9) afforded the purine 6, while diazotization of 8 afforded the 8-aza purine 7. Compounds 6 and 7 were evaluated against lumazine synthase of Bacillus subtilis and riboflavin synthase of Escherichia coli. Both 6 and 7 were better inhibitors of lumazine synthase than riboflavin synthase. The 8-azapurine 7 had a lower KI (0.33 and 0.39 mM) than the purine 6 (0.47 and 0.54 mM) when evaluated with lumazine synthase and riboflavin synthase, respectively.

Bacillus subtilis↗

PubMed1998

Protein-linked DNA strand breaks induced by NSC 314622, a novel noncamptothecin topoisomerase I poison.

NSC 314622 was found to have a cytotoxicity profile comparable to the topoisomerase I (top1) inhibitors camptothecin (CPT) and saintopin in the National Cancer Institute In Vitro Anticancer Drug Discovery Screen using the COMPARE analysis. In vitro data showed that NSC 314622 induced DNA cleavage in the presence of top1 at micromolar concentrations. Cleavage specificity was different from CPT in that NSC 314622 did not cleave all sites induced by CPT whereas some sites were unique to the NSC 314622 treatment. Top1-induced DNA cleavage was also more stable than cleavage induced by CPT. NSC 314622 did not induce DNA cleavage in the presence of human topoisomerase II. High concentrations of NSC 314622 did not produce detectable DNA unwinding, which suggests that NSC 314622 is not a DNA intercalator. DNA damage analyzed in human breast carcinoma MCF7 cells by alkaline elution showed that NSC 314622 induced protein-linked DNA single-strand breaks that reversed more slowly than CPT-induced strand breaks. CEM/C2, a CPT-resistant cell line because of a top1 point mutation [Cancer Res 55:1339-1346 (1995)], was cross-resistant to NSC 314622. These results demonstrate that NSC 314622 is a novel top1-targeted drug with a unique chemical structure.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Differences in prevalence of and risk factors for subclinical vascular disease among black and white participants in the Cardiovascular Health Study.

A composite measure of subclinical vascular disease has been developed in the Cardiovascular Health Study (CHS). In previous reports, we measured the prevalence of subclinical disease among the original 5201 participants in the CHS, the relationship of risk factors to subclinical disease, and the association of subclinical disease to clinical coronary heart disease. In 1992 to 1993 (year 4 of the study), a larger cohort of 424 black women and 248 black men was added to the study. In this study, we have compared the prevalence of subclinical disease among blacks and whites in the CHS and the association with cardiovascular risk factors. The prevalence of subclinical disease for all participants (aged > or =65 years) was 41.3% for white women, 39.7% for black women, 41.9% for white men, and 43.7% for black men. The prevalence increased with age. The risk factor associations for subclinical disease were similar among blacks and whites. In multivariate analysis, age, systolic blood pressure, LDL cholesterol, smoking, and family history of myocardial infarction were independently associated with subclinical disease among both black and white women, while for white men, systolic blood pressure, use of antihypertensive medication, smoking, body mass index, and diastolic blood pressure (inverse) were related to subclinical disease. In black men, blood triglyceride level, use of antihypertensive medications, and family history of myocardial infarction (inverse) were associated with subclinical disease.

Black or African American↗

PubMed1998

Factor V Leiden is not a risk factor for arterial vascular disease in the elderly: results from the Cardiovascular Health Study.

Coagulation factor V Leiden is a risk marker for venous thrombosis. For arterial thrombosis no large study to date has included population-based elderly patients. The Cardiovascular Health Study is a longitudinal study of 5,201 men and women over age 65. With 3.4-year follow-up, we studied 373 incident cases of myocardial infarction (MI), angina, stroke. or transient ischemic attack (TIA), and 482 controls. The odds ratios for each event with heterozygous factor V Leiden were: MI, 0.46 (95% CI 0.17 to 1.25); angina, 1.0 (95% CI 0.45 to 2.23); stroke, 0.77 (95% CI 0.35 to 1.70): TIA, 1.33 (95% CI 0.5 to 3.55); any outcome, 0.83 (95% CI 0.48 to 1.44). Adjustment for cardiovascular risk factors did not change relationships. In older adults factor V Leiden is not a risk factor for future arterial thrombosis.

Adult↗

PubMed1998

Correlates of antithrombin, protein C, protein S, and TFPI in a healthy elderly cohort.

The majority of fatal acute myocardial infarctions occur in the elderly. Since these events are predominantly thrombotic, we studied the cross-sectional associations of the anticoagulant proteins Antithrombin, Protein C, Protein S. and Tissue Factor Pathway Inhibitor (TFPI) in a subgroup (n = 400) of the Cardiovascular Health Study (a study of healthy men and women > or = 65 years) free of clinical cardiovascular disease (CVD). We did not observe any strong age-associated trends, although Protein C was lower in older women (p < or = 0.001), and TFPI was higher in older men (p < or = 0.01). The inhibitors were highly intercorrelated, and were associated with increased levels of inflammation-sensitive proteins (e.g., fibrinogen. plasminogen), lipids (especially total and LDL-cholesterol), and coagulation factors, such as Factors VIIc, IXc, and Xc. None was associated with the procoagulant markers Prothrombin Fragment F1-2 or Fibrinopeptide A. Only TFPI was associated with subclinical atherosclerosis: ankle-arm index and internal carotid artery stenosis, p trend < or = 0.01; and carotid wall thickness, p trend < or = 0.05. In multivariate analysis the independent predictors of TFPI were levels of fibrinogen; the fibrinolytic marker plasmin-antiplasmin complex; LDL-cholesterol; and carotid wall thickness (R2 for the model = 0.35). In summary, the inhibitors did not appear to increase with age, and were predominantly associated with inflammation markers and lipids. Since markers of thrombin production do increase with age, we hypothesize that an age-related hemostatic imbalance may ensue, with associated increased thrombotic risk. Only TFPI was associated with subclinical CVD, suggesting that it may more closely reflect endothelial damage.

Aged↗

PubMed1997

Incidence of and risk factors for atrial fibrillation in older adults.

BACKGROUND: This study aimed to describe the incidence of atrial fibrillation (AF) among older adults during 3 years of follow-up. METHODS AND RESULTS: In this cohort study, 5201 adults > or = 65 years old were examined annually on four occasions between June 1989 and May 1993. At baseline, participants answered questionnaires and underwent a detailed examination that included carotid ultrasound, pulmonary function tests, ECG, and echocardiography. Subjects with a pacemaker or AF at baseline (n=357) were excluded. New cases of AF were identified from three sources: (1) annual self-reports, (2) annual ECGs, and (3) hospital discharge diagnoses. Cox proportional-hazards models were used to assess baseline risk factors as predictors of incident AF. Among 4844 participants, 304 developed a first episode of AF during an average follow-up of 3.28 years, for an incidence of 19.2 per 1000 person-years. The onset was strongly associated with age, male sex, and the presence of clinical cardiovascular disease. For men 65 to 74 and 75 to 84 years old, the incidences were 17.6 and 42.7, respectively, and for women, 10.1 and 21.6 events per 1000 person-years. In stepwise models, the use of diuretics, a history of valvular heart disease, coronary disease, advancing age, higher levels of systolic blood pressure, height, glucose, and left atrial size were all associated with an increased risk of AF. The use of beta-blockers and high levels of alcohol use, cholesterol, and forced expiratory volume in 1 second were associated with a reduced risk of AF. CONCLUSIONS: The incidence of AF in older adults may be higher than estimated by previous population studies. Left atrial size appears to be an important risk factor, and the control of blood pressure and glucose may be important in preventing the development of AF.

Adult↗

PubMed1997

Synthesis of analogs of 2-methoxyestradiol with enhanced inhibitory effects on tubulin polymerization and cancer cell growth.

A new series of estradiol analogs was synthesized in an attempt to improve on the anticancer activity of 2-methoxyestradiol, a naturally occurring mammalian tubulin polymerization inhibitor. The compounds were evaluated as inhibitors of tubulin polymerization and the binding of [3H]colchicine to tubulin, as well as for in vitro cytotoxicity in human cancer cell cultures. Overall, the most potent of the new compounds were 2-(2',2',2'-trifluoroethoxy)-6-oximinoestradiol, 2-ethoxy-6-oximinoestradiol, and 2-ethoxy-6-methoximinoestradiol. These agents lacked significant affinity for the estrogen receptor. The cytotoxicities of the compounds correlated in general with their abilities to inhibit tubulin polymerization, thus supporting inhibition of tubulin polymerization as the primary mechanism causing inhibition of cell growth.

2-Methoxyestradiol↗

PubMed1997

Inflammation, aspirin, and the risk of cardiovascular disease in apparently healthy men.

BACKGROUND: Inflammation may be important in the pathogenesis of atherothrombosis. We studied whether inflammation increases the risk of a first thrombotic event and whether treatment with aspirin decreases the risk. METHODS: We measured plasma C-reactive protein, a marker for systemic inflammation, in 543 apparently healthy men participating in the Physicians' Health Study in whom myocardial infarction, stroke, or venous thrombosis subsequently developed, and in 543 study participants who did not report vascular disease during a follow-up period exceeding eight years. Subjects were randomly assigned to receive aspirin or placebo at the beginning of the trial. RESULTS: Base-line plasma C-reactive protein concentrations were higher among men who went on to have myocardial infarction (1.51 vs. 1.13 mg per liter, P<0.001) or ischemic stroke (1.38 vs. 1.13 mg per liter, P=0.02), but not venous thrombosis (1.26 vs. 1.13 mg per liter, P=0.34), than among men without vascular events. The men in the quartile with the highest levels of C-reactive protein values had three times the risk of myocardial infarction (relative risk, 2.9; P<0.001) and two times the risk of ischemic stroke (relative risk, 1.9; P=0.02) of the men in the lowest quartile. Risks were stable over long periods, were not modified by smoking, and were independent of other lipid-related and non-lipid-related risk factors. The use of aspirin was associated with significant reductions in the risk of myocardial infarction (55.7 percent reduction, P=0.02) among men in the highest quartile but with only small, nonsignificant reductions among those in the lowest quartile (13.9 percent, P=0.77). CONCLUSIONS: The base-line plasma concentration of C-reactive protein predicts the risk of future myocardial infarction and stroke. Moreover, the reduction associated with the use of aspirin in the risk of a first myocardial infarction appears to be directly related to the level of C-reactive protein, raising the possibility that antiinflammatory agents may have clinical benefits in preventing cardiovascular disease.

Adult↗

PubMed1997

Lifetime smoking exposure affects the association of C-reactive protein with cardiovascular disease risk factors and subclinical disease in healthy elderly subjects.

Blood levels of C-reactive protein (CRP), a marker of inflammation, are related to cardiovascular disease risk. To determine cross-sectional correlates in the elderly, we measured CRP in 400 men and women older than 65 years and free of clinical cardiovascular disease at baseline as part of the Cardiovascular Health Study. Only 2% of the values were greater than 10 mg/L, the cut-point usually used to identify inflammation. CRP levels appeared tightly regulated, since there were strong bivariate correlations between CRP and the following: inflammation-sensitive proteins such as fibrinogen (r = .52); measures of fibrinolysis such as plasmin-antiplasmin complex (r = .23); pack-years of smoking (r = .30); and body mass index (r = .24; all P values < or = .001). The association with pack-years was independent of the length of time since cessation of smoking. CRP levels were also associated with coagulation factors VIIc, IXc, and Xc; HDL cholesterol (negative) and triglyceride; diabetes status; diuretic use; ECG abnormalities; and level of exercise. Because of effect modification, two multiple linear regression prediction models were developed for CRP, one each for never smokers and ever smokers. An a priori physiologic model was used to guide these analyses, which disallowed the use of other inflammation-sensitive variables such as fibrinogen. In never smokers, the independent predictors were body mass index (+), diabetes status (+), plasmin-antiplasmin complex (+), and the presence of ECG abnormalities (+); this model predicted 15% of the CRP population variance. In ever smokers, the predictors were body mass index (+), plasmin-antiplasmin complex (+), pack-years of smoking (+), HDL cholesterol (-), and ankle-arm blood pressure index (-); this model predicted 42% of the population variance. We conclude that levels of CRP in the healthy elderly are tightly regulated and reflect lifetime exposure to smoking as well as level of obesity, ongoing level of fibrinolysis, diabetes status, and level of subclinical atherothrombotic disease. Moreover, exposure to smoking affects the relation of CRP to these other factors.

Aged↗

PubMed1997

Relationship of C-reactive protein to risk of cardiovascular disease in the elderly. Results from the Cardiovascular Health Study and the Rural Health Promotion Project.

Markers of inflammation, such as C-reactive protein (CRP), are related to risk of cardiovascular disease (CVD) events in those with angina, but little is known about individuals without prevalent clinical CVD. We performed a prospective, nested case-control study in the Cardiovascular Health Study (CHS; 5201 healthy elderly men and women). Case subjects (n = 146 men and women with incident CVD events including angina, myocardial infarction, and death) and control subjects (n = 146) were matched on the basis of sex and the presence or absence of significant subclinical CVD at baseline (average follow-up, 2.4 years). In women but not men, the mean CRP level was higher for case subjects than for control subjects (P < or = .05). In general, CRP was higher in those with subclinical disease. Most of the association of CRP with female case subjects versus control subjects was in the subgroup with subclinical disease; 3.33 versus 1.90 mg/L, P < .05, adjusted for age and time of follow-up. Case-control differences were greatest when the time between baseline and the CVD event was shortest. The strongest associations were with myocardial infarction, and there was an overall odds ratio for incident myocardial infarction for men and women with subclinical disease (upper quartile versus lower three quartiles) of 2.67 (confidence interval [CI] = 1.04 to 6.81), with the relationship being stronger in women (4.50 [CI = 0.97 to 20.8]) than in men (1.75 [CI = 0.51 to 5.98]). We performed a similar study in the Rural Health Promotion Project, in which mean values of CRP were higher for female case subjects than for female control subjects, but no differences were apparent for men. Comparing the upper quintile with the lower four, the odds ratio for CVD case subjects was 2.7 (CI = 1.10 to 6.60). In conclusion, CRP was associated with incident events in the elderly, especially in those with subclinical disease at baseline.

Aged↗

PubMed1997

Dietary vitamin K1 and stability of oral anticoagulation: proposal of a diet with constant vitamin K1 content.

Case reports cited in Medline or Biological Abstracts (1966-1996) were reviewed to evaluate the impact of vitamin K1 dietary intake on the stability of anticoagulant control in patients using coumarin derivatives. Reported nutrient-drug interactions cannot always be explained by the vitamin K1 content of the food items. However, metabolic data indicate that a consistent dietary intake of vitamin K is important to attain a daily equilibrium in vitamin K status. We report a diet that provides a stable intake of vitamin K1 equivalent to the current U.S. Recommended Dietary Allowance, using food composition data derived from high-performance liquid chromatography. Inconsistencies in the published literature indicate that prospective clinical studies should be undertaken to clarify the putative dietary vitamin K1-coumarin interaction. The dietary guidelines reported here may be used in such studies.

Administration, Oral↗

PubMed1996

Design, synthesis, and biological evaluation of ellipticine-estradiol conjugates.

Three ellipticine-estradiol conjugates were synthesized in an effort to target the cytotoxicity of ellipticine to estrogen-receptor positive cells. The three conjugates were prepared with linker chains extending from the 17 alpha position of the estradiol to N-2 (compound 3), N-6 (compound 4), and C-9 (compound 5) positions of ellipticine. The ellipticine-estradiol conjugates were evaluated for their abilities to bind to estrogen receptors, to inhibit topoisomerase II, and for their cytotoxicities in human cancer cell lines. Conjugates 3 and 5 displayed weak binding affinities of 0.132 and 0.303 for the estrogen receptor (relative to estradiol = 100), while conjugate 4 did not show any detectable binding to the estrogen receptor. Compound 3 was a moderate inhibitor of topoisomerase II (IC50 24.1 microM), while 4 and 5 were inactive. Conjugate 3 was consistently more cytotoxic (GI50 values 1-10 microM) than compounds 4 and 5 (GI50 values 10-100 microM) in a variety of human cancer cell lines. None of the compounds displayed any selectivity for estrogen-receptor positive cell lines, which probably reflects their weak affinities for estrogen receptors.

Antineoplastic Agents↗

PubMed1996

Synthesis and biological evaluation of certain alkenyldiarylmethanes as anti-HIV-1 agents which act as non-nucleoside reverse transcriptase inhibitors.

Several novel alkenyldiarylmethane (ADAM) non-nucleoside HIV-1 reverse transcriptase inhibitors were synthesized. The most potent of these proved to be 3',3"-dibromo-4',4"-dimethoxy-5'5"-bis(methoxycarbonyl)-1,1-diphenyl-1-+ ++heptene (8) ADAM 8 inhibited the cytopathic effect of HIV-1 in CEM cell culture with an EC50 value of 7.1 microM and was active against an array of laboratory strains of HIV-1 in CEM-SS and MT-4 cells, but was inactive as an inhibitor of HIV-2. In common with the other known non-nucleoside reverse transcriptase inhibitors, ADAM 8 was an effective inhibitor of HIV-1 reverse transcriptase (IC50 1 microM) with poly(rC).oligo(dG), but not with poly(rA).oligo(dT), as the template/primer. ADAM 8 was inactive against HIV-1 reverse transcriptases containing non-nucleoside reverse transcriptase inhibitor resistance mutations at residues 101, 106, 108, 139, 181, 188, and 236, while it remained active against enzymes with mutations at residues 74, 98, 100, 103, and at 103/181. An AZT-resistant virus having four mutations in reverse transcriptase was more sensitive to inhibition by ADAM 8 than the wild-type HIV-1. In addition, ADAM 8 displayed synergistic activity with AZT, but lacked synergy with ddI. ADAM 8 or a structurally related analog may therefore be useful as an antiviral agent in combination with AZT or with other NNRTIs that are made ineffective by mutations at residues which do not confer resistance to ADAM 8.

Amino Acid Sequence↗

PubMed1996

NMR analysis of site-specific ligand binding in oligomeric proteins. Dynamic studies on the interaction of riboflavin synthase with trifluoromethyl-substituted intermediates.

The binding of small ligands to symmetrical oligomeric proteins may lead to a number of different partially ligated intermediates but should finally yield a symmetrical fully ligated enzyme/ligand complex. In the case of the trimeric protein, riboflavin synthase, some ligands form an unexpected protein/ligand complex, even in the presence of a large excess of ligand. Three different bound forms were observed by 19F NMR spectroscopy, and Scatchard-type analysis suggested binding sites of similar affinities. NOESY analysis of the kinetic network revealed that the three bound states exchange with free ligand, but not with each other, thus suggesting that the trimeric enzyme could be asymmetrical. This information permits appropriate precautions to be taken during X-ray structure analysis of riboflavin synthase, which is in progress. Quantitative analysis of the NOESY spectra yielded different rate constants for the different binding sites. For comparison, the monomeric lumazine protein was investigated as an example of a case with simple two-site exchange. For such systems, all kinetic parameters including kon and the dissociation constant can be determined from the NOESY spectrum. The data show that NMR spectroscopy can produce qualitative and quantitative information in cases of nonequivalent binding sites in oligomeric proteins if isolated NMR signals of the different forms can be observed. The technique is not limited to 19F as reporter nucleus.

Bacillus subtilis↗

PubMed1996

Association of fibrinogen and coagulation factors VII and VIII with cardiovascular risk factors in the elderly: the Cardiovascular Health Study. Cardiovascular Health Study Investigators.

The cross-sectional correlates of three hemostatic factors--fibrinogen, factor VII, and factor VIII--were examined in the Cardiovascular Health Study, a population-based cohort study of 5,201 subjects over age 65 years. Subjects were recruited in 1989-1990 in Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Pittsburgh, Pennsylvania. In multivariate linear regression models, cardiac risk factors significantly associated with fibrinogen were current smoking, race, lipids, and white blood count. In women, alcohol use, obesity, physical activity, and insulin level were also significant, while in men hypertension was correlated. The significant correlates of factor VII were lipids and white blood count in men and estrogen use, alcohol use, race, lipids, insulin level, white blood count, and obesity in women. The independent correlates of factor VIII were insulin, glucose, and race in both sexes; low density lipoprotein cholesterol, white blood count, and diuretic use in men; and alcohol use in women. In multivariate models, factors known to be modifiable risk factors for cardiovascular disease accounted for more of the population variance of these hemostatic factors in women than in men, especially for factor VII. The hemostatic factors may mediate some effects of risk factors on disease, and this should be considered in longitudinal studies.

Age Distribution↗

PubMed1996

Correlation of anti-HIV potency with lipophilicity in a series of cosalane analogs having normal alkenyl and phosphodiester chains as cholestane replacements.

In order to define the role of the cholestane moiety in the anti-HIV agent cosalane, a series of cosalane analogs was synthesized in which the cholestane ring system was replaced by normal alkenyl and phosphodiester substituents having varied chain lengths and lipophilicities. The compounds containing simple alkenyl substituents were found to be more potent as inhibitors of the cytopathic effect of HIV-1 in cell culture than the phosphodiesters. In addition, the potencies of the alkene congeners correlated positively with chain length and lipophilicity of the alkene. The results indicate that the cholestane moiety of cosalane functions as a lipophilic accessory appendage to escort the dichlorodisalicylmethane pharmacophore to a lipid environment.

Antiviral Agents↗