Synthesis of the nucleoside moiety of liposidomycins: elucidation of the pharmacophore of this family of MraY inhibitors

Tunicamycins (TCMs) and liposidomycins (LPMs) are naturally occurring inhibitors of the bacterial translocase (MraY). Based on structure-activity relationship (SAR) studies, a molecular model has been proposed for their inhibitory mechanism. This study points out the importance of the nucleoside moiety of liposidomycins in the inhibition of MraY. A simplified molecule (I) based on the liposidomycin core structure has been synthesised and tested on MraY. The compound displayed a moderate inhibitory activity (IC50 = 50 microM). The validation of the molecular model was then performed by synthesising higher homologues of I, containing an additional stereocentre in the 5' position (XIV and XV). In agreement with the prediction, only the (S) isomer XV showed significant activity against MraY (IC50 = 5 microM).

Antibacterial activity of RU44790, a new N-tetrazolyl monocyclic beta-lactam

RU44790 belongs to a new class of synthetic monocyclic beta-lactam antibiotics which feature a bioisosteric tetrazole moiety instead of the more classical acidic functions at the N-1 position of the beta-lactam ring. Its antibacterial activity was evaluated against some 900 strains and was compared with those of other recent beta-lactam derivatives, especially aztreonam. RU44790 is endowed with potent activity against gram-negative bacteria. At less than or equal to 0.6 micrograms/ml, RU44790 inhibited 90% of all strains of the family Enterobacteriaceae with the exception of Citrobacter spp. (MIC for 90% of strains tested, 1.2 micrograms/ml). The activity was similar to that of aztreonam against strains that are normally susceptible to expanded-spectrum cephalosporins. On the other hand, the new compound was 10 to 100 times more potent than aztreonam and most of the other antibiotics tested against enterobacteria that produce chromosome-encoded or plasmid-mediated extended-spectrum beta-lactamases. Pseudomonas aeruginosa isolates were equally susceptible to both monobactams. RU44790 was inactive against staphylococci and had only marginal activity against streptococci (MIC for 50% of strains tested, 2.5 micrograms/ml). RU44790 was highly resistant to hydrolysis by various beta-lactamases, particularly cephalosporinases such as P99. The latter enzyme was also inhibited by the compound. RU44790 showed a high affinity for penicillin-binding protein 3 of Escherichia coli. The results suggest that RU44790 has good potential in the treatment of infections caused by gram-negative microorganisms.

Sex differential in the relationship of electrocardiographic ST-T abnormalities to risk of coronary death: 11.5 year follow-up findings of the Chicago Heart Association Detection Project in Industry

The independent contributions of ST segment depression and/or T wave abnormality (ST-T abnormalities) on the baseline resting electrocardiogram to risk of 11.5 year coronary heart disease (CHD) mortality were explored among 9203 white men and 7818 white women who were 40 to 64 years old and without definite CHD at entry in the Chicago Heart Association Detection Project in Industry. At baseline, prevalence rates of ST-T abnormalities were age related for both sexes, and at every age the rate was higher in women than men (age-adjusted prevalence rates 12.3% and 8.1%, respectively). Univariate analysis showed that ST-T abnormalities were associated with significantly increased risk of death from CHD for both men and women. However, men with ST-T abnormalities had much greater age-adjusted and multiple risk factor-adjusted absolute excess risk and relative risk than women with such electrocardiographic abnormalities. When baseline age, diastolic pressure, serum cholesterol, cigarettes/day, history of diabetes, and baseline use of antihypertensive medication were included in the multivariate analysis, ST-T abnormalities remained significantly related to death from CHD in men but not women. The interaction term between sex and ST-T abnormalities was at a borderline level of statistical significance by Cox regression analysis. In conclusion, ST-T abnormalities indicate an increased risk of subsequent death from CHD independent of major coronary risk factors for middle-aged U.S. men, but this is not clearly so for women.

Relationship of clinical diabetes and asymptomatic hyperglycemia to risk of coronary heart disease mortality in men and women

This epidemiologic study explored the sex differential in risk of death from coronary heart disease in persons with or without clinically diagnosed diabetes or asymptomatic hyperglycemia. Use was made of 9-year follow-up data from the Chicago Heart Association Detection Project in Industry for 11,220 white men and 8,030 white women aged 35-64 years at entry to the Project (November 1967-January 1973). Both clinically diagnosed diabetes and asymptomatic hyperglycemia were associated with an increased risk of death from coronary heart disease. The extent of this association was greater in women than in men in regard to relative risk. However, absolute excess risk for both diabetics and those with asymptomatic hyperglycemia was larger for men than for women. Clinical diabetes appeared to be an independent risk factor for coronary heart disease in both men and women based on multivariate Cox regression analyses. On the other hand, for men, no significant independent effect of asymptomatic hyperglycemia was apparent. Women with asymptomatic hyperglycemia had significantly higher coronary heart disease death rates than normoglycemic women, with adjustment for major coronary heart disease risk factors; in multivariate analyses, the relationship of asymptomatic hyperglycemia to risk of coronary heart disease was of borderline significance (p = 0.054). This study indicates the independent associations of diabetes and possibly asymptomatic hyperglycemia with coronary heart disease mortality, with greater relative significance in women than in men.

Prevalence of diabetes/hyperglycemia and associated cardiovascular risk factors in blacks and whites: Chicago Heart Association Detection Project in Industry

Prevalence rates of diabetes, asymptomatic hyperglycemia, and cardiovascular risk factors were examined in an employed population of 28,895 whites and 2607 blacks, ages 25 to 64 years. Diabetes had been previously diagnosed in this population among approximately 3% of the males of both races and 2% of the females. Plasma glucose 1 hour after a 50 gm oral load was highest among white males (141 mg/dl), similar and at intermediary levels among black males (134 mg/dl) and white females (135 mg/dl), and lowest among black females (126 mg/dl). A divergent pattern of obesity was observed, however, with black females being by far the most overweight. Preliminary mortality data for males suggest that both blacks and whites with diabetes have sizably higher death rates than those without diabetes; a black-white differential is not apparent.

Pulse pressure-III. Prognostic significance in four Chicago epidemiologic studies

This report, the third in a series on pulse pressure and pure systolic hypertension, examines the associations between blood pressure and the cardiovascular diseases and coronary heart disease, both cross-sectionally and prospectively, utilizing data from four Chicago epidemiologic studies, in an effort to determine whether or not a widened pulse pressure, or pure systolic hypertension, is an independent risk factor. In these analyses, blood pressure is divided into two components, one related to level and the other to pulse pressure, with pulse pressure redefined so that the association between pulse pressure and the prevalence of ECG abnormalities or mortality, indicates whether the endpoint is more strongly related to systolic or diastolic blood pressure. In these studies, blood pressure level is significantly related to both ECG abnormalities and mortality. In the cross-sectional analyses, pulse pressure is generally positively related to the prevalence of ECG abnormalities, indicating a stronger association for systolic blood pressure, and thus a possible association with pure systolic hypertension. However, in the prospective analyses, pulse pressure is generally not related to mortality, indicating an equal association with mortality for systolic and diastolic blood pressure in these studies. Thus, although the cross-sectional analyses generally support the hypothesis that a widened pulse pressure, or pure systolic hypertension, is an independent risk factor for the cardiovascular diseases and coronary heart disease, the prospective analyses do not.

Asymptomatic hyperglycemia and cardiovascular diseases in three Chicago epidemiologic studies

Three epidemiologic studies in Chicago populations yielded inconsistent findings on the relationship of diabetes to cardiovascular disease