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Introduction: Protein Z is a vitamin K-dependent protein that serves as a cofactor for the inhibition of activated factor X by the serpin protein Z-dependent protease inhibitor (ZPI). Protein Z plasma levels have been shown to be reduced in patients with peripheral arterial disease (PAD), but ZPI levels have not yet been reported. The aim of this study was to more fully assess the protein Z–ZPI system in individuals with atherosclerosis selected by the presence of symptomatic PAD. Materials and methods: Protein Z and ZPI levels were determined in 95 PAD patients (73 males; 22 females) [median age: 73 years (range, 50–86 years)] and in 190 controls comparable for age and gender. Protein Z was measured using a commercial immunoassay, and ZPI was measured with a homemade immunoassay and a functional assay. Results: Protein Z antigen, ZPI antigen and ZPI function were found to be significantly lower in PAD patients with respect to controls [protein Z, median 72.5% (range: 3.4–123.7%) vs. 90.7% (range: 32.1–203.2%), P < 0.0001; ZPI antigen, 86.1% (range: 25.1–149.5%) vs. 93.2% (range: 48.9–171.3%), P = 0.004; ZPI function, 83.5% (range: 21.1–135.2%) vs. 97.2% (range: 50.5–175.5%), P < 0.0001]. The lowest tertiles of protein Z antigen [odds ratio (OR) 5.4, 95% confidence interval (CI) 2.2–13.5, P < 0.0001] and ZPI function (OR 2.4, 95% CI 1.1–5.5, P = 0.03) were associated with PAD on multivariate analysis after adjustment for age, gender, and traditional cardiovascular risk factors. A significant inverse relationship was also observed between protein Z and ZPI levels and the number of traditional cardiovascular risk factors and the clinical severity of disease (Fontaine stage). Conclusions: Low levels of protein Z antigen and protein Z activity are significantly associated with the occurrence and severity of atherosclerotic PAD.

We previously reported that low protein Z plasma levels are associated with acute coronary syndromes (ACS). Aim of the present study was to evaluate protein Z levels in different phases of activity of coronary atherosclerosis. Protein Z plasma levels were measured in 166 (131 male and 35 female) patients consecutively admitted to the University of Florence with a diagnosis of ACS (group A), 166 (131 male and 35 female) patients selected by age and gender in relation to group A from those with a clinical history of ACS who remained symptom- and/or event-free over the last year before the investigation (group B); and 332 (262 male and 70 female) controls comparable for age and gender with the other two groups. None had liver or renal dysfunction nor showed a positivity for antiphospholipid antibodies or for factor V Leiden mutation. Patients under warfarin therapy were excluded. Mean protein Z plasma levels were found to be significantly (P < 0.0001) lower in group A (1475 ± 684.1 ng mL−1) and group B (1327.6 ± 690.7 ng mL−1) as compared with control group (1650.1 ± 634.5 ng mL−1), while no significant differences existed between the two groups of patients (P = 0.06). A logistic regression analysis, performed after the division of the study population into quartiles of protein Z levels and adjusted for all possible confounders, showed a significant increased risk of ACS for the lowest (<1213 ng mL−1) as compared with the highest quartile of protein Z in both groups of patients [group A odds ratio (OR): 2.7, 95% CI 1.3–5.5, P = 0.007; group B OR: 3.2, 95% CI 1.1–8.9, P = 0.02). In conclusion, these results strengthen our previous data on low protein Z plasma levels in ACS and indicate a possible dose–response effect of decreasing protein Z plasma levels on the coronary atherosclerotic disease.

The utility of the peristaltic in vitro assembly is further demonstrated in a gastric acid neutralization study involving a liquid antacid formulation, a placebo and a group of hypersecretory subjects. By adding an acid delivery system to the assembly to simulate gastric acid secretion and using dilute hydrochloric acid as the reaction medium, hydrogen ion concentration-time plots were obtained which were comparable to their in vivo counterparts.

The chromatin structure of the Saccharomyces cerevisiae ADH2 gene is modified during the switch from repressing (high glucose) to derepressing (low glucose) conditions of growth. Loss of protection toward micrococcal nuclease cleavage for the nucleosomes covering the TATA box and the RNA initiation sites (-1 and +1, respectively) is the major modification taking place and is strictly dependent on the presence of the transcriptional activator ADR1. To identify separate functions involved in the transition from a repressed to a transcribing promoter, we have analyzed the ADH2 chromatin organization in various genetic backgrounds. Deletion of the CCR4 gene coding for a general transcription factor impaired ADH2 expression without affecting chromatin remodeling. Growing yeast at 37 degrees C also resulted in chromatin remodeling at the ADH2 locus even under glucose repressing conditions. However, although this temperature-induced remodeling was dependent on the ADR1 protein, no ADH2 mRNA was observed. In addition, inactivating RNA polymerase II (and therefore, elongation) was found to have no effect on the ability to reconfigure nucleosomes. Taken together, these data indicate that chromatin remodeling by itself is insufficient to induce transcription at the ADH2 promoter.

A study of the hinge bending mode in the enzyme liver alcohol dehydrogenase is made by use of empirical energy functions. The enzyme is a dimer, with each monomer composed of a coenzyme binding domain and a catalytic domain with a large cleft between the two. Superposition of the apoenzyme and holoenzyme crystal structures is used to determine a rigid rotation axis for closing of the cleft. It is shown that a rigid body transformation of the apoenzyme to the holoenzyme structure corresponds to a 10 degrees rotation of the catalytic domain about this axis. The rotation is not along the least-motion path for closing of the cleft but instead corresponds to the catalytic domain coming closer to the coenzyme binding domain by a sliding motion. Estimation of the energy associated with the interdomain motion of the apoenzyme over a range of 90 degrees (-40 to 50 degrees, where 0 degrees corresponds to the minimized crystal structure) demonstrates that local structural relaxation makes possible large-scale rotations with relatively small energy increments. A variety of structural rearrangements associated with the domain motion are characterized. They involve the hinge region residues that provide the covalent connections between the two domains and certain loop regions that are brought into contact by the rotation. Differences between the energy minimized and the holoenzyme structures point to the existence of alternative conformations for loops and to the importance of the ligands in the structural rearrangements.