Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.1.1.6 (CAD)
4,420 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have measured the 'core' mammalian carbamoyl-phosphate synthetase II (CPSII) activity, using NH4Cl as the nitrogen-donating substrate and trapping carbamoyl phosphate as urea through its reaction with ammonium ions. When ATP and magnesium ion concentrations are close to those found in the cell, the substrate saturation curves for ammonia and bicarbonate are hyperbolic, giving Km (NH3) values of 166 microM at high ATP concentrations and 26 microM at low ATP concentrations, while the Km (bicarbonate) is 1.4 mM at both ATP concentrations used. These values for the Km (NH3) are lower than previously reported for CPS II, and closer to the values for the mitochondrial counterpart. The Km for ammonia and bicarbonate are not altered by phosphorylation of the multienzyme polypeptide CAD, which contains the first three enzyme activities of pyrimidine biosynthesis. The CPS II activity is lower with an excess of either ATP or magnesium ions, causing the apparently sigmoid dependence of activity upon ATP concentration to be enhanced at low concentrations of free magnesium ions. The feedback inhibitor, UTP, acts by stabilising a state with a low affinity for magnesium ions and for ATP. In the presence of the activator, 5-phosphoribosyl diphosphate (PRibPP), the enzyme has a higher affinity for magnesium ions and thus the ATP dependence of the activity is hyperbolic. Phosphorylation of CAD similarly activates the CPS II enzyme by increasing the affinity for magnesium ions and by pushing the equilibrium away from the low-affinity UTP-stabilised state. Using our improved assay procedure, we observe a very large activation by PRibPP of carbamoylphosphate synthesis at low concentrations of magnesium ions, and we find that unlike UTP, the activator PRibPP is able to act on the phosphorylated enzyme.
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PMID:Regulation of the mammalian carbamoyl-phosphate synthetase II by effectors and phosphorylation. Altered affinity for ATP and magnesium ions measured using the ammonia-dependent part reaction. 149 69

All cross-sectional areas of the upper airway can be measured by an acoustic signal using the acoustic reflection technique, or acoustic rhinometry. The plane of the cross-sectional areas measured was determined in nasal models. The isotemporal layers were found to be nearly parallel to the nasal valve. The acoustically measured cross-sectional areas correlated with the cross-sectional areas of cuts from nasal models. After digitizing these cuts, a CAD software calculates cross-sectional areas in all orientations and at all distances. The difference between the measured and calculated cross-sectional areas is up to 3% in the nasal cavity and up to 17% in the nasopharynx. The hypothesis that the cross-sectional areas measured lie nearly parallel to the nasal valve was confirmed. The normal rhinometric curve shows the minimal cross-sectional area (I-notch) to lie at the nasal isthmus. The second narrowest segment of the nasal cavity lies at the head of the inferior concha and septal concha (C-notch). Characteristic examples of patients with turbinate hypertrophy, choanal atresia, enlarged adenoids, and septal deviations are presented. Acoustic rhinometric curves can only be interpreted in combination with the rhinoscopic findings because different pathological conditions can produce similar curves. Recording of reliable and reproducible data by acoustic rhinometry demands that the connection between the rhinometer and the nose does not distort the valve area. When we used two different nose pieces (1.2 and 1.5 cm outer diameter) the cross-sectional areas in the anterior third of the nose of only 28% of the patients was measured correctly.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Acoustic rhinometry: the bat principle of the nose]. 150 Mar 1

Transient episodes of myocardial ischemia can be reliably detected by AEM in patients with known CAD. AEM appears to be particularly useful for patients in whom symptom control has been achieved with conventional antianginal drugs because many of these patients (up to 50%) continue to have residual silent ischemia that would otherwise remain undetected. Despite the lack of symptoms, numerous studies in patients with stable and unstable coronary syndromes have shown that the presence of silent ischemia during AEM is associated with an increased risk of subsequent coronary events and cardiac death. Although Holter monitoring is a practical and reliable tool for prolonged evaluation of myocardial ischemia, its routine use can not be advocated until its clinical role has been clearly defined in the ongoing large prospective studies.
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PMID:Ambulatory electrocardiography evaluation of asymptomatic, unstable, and stable coronary artery disease patients for myocardial ischemia. 150 73

The computer-supported development of valves for cardiac-assist devices or artificial hearts is shown in relation to plastic technology. A CAD-system is used for the design development, whereas the dimensioning of the critical and highly stressed membranes is examined by FEM-analyses. Economic manufacture is permitted by the combined thermoforming-dip moulding technique; the blood-side components are made from biocompatible polyurethane to minimize blood damage. The first long-term results in the test set-up are compared to the FEM results.
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PMID:CAD-design, stress analysis and in vitro evaluation of three leaflet blood-pump valves. 151 32

On the basis of homology, the mammalian CAD (glutamine-dependent carbamyl phosphate synthetase-aspartate transcarbamylase-dihydroorotase) gene appears to have arisen from the fusion of four separate ancestral genes. Evidence for two of these precursor genes is found in the carbamyl phosphate synthetase (CPSase) domain of CAD. In prokaryotes, such as Escherichia coli CPSase is encoded by two distinct cistrons of the carAB operon. Whereas carA and carB are separated by a short noncoding intercistronic region, the homologous sequences of the CAD gene encode an amino acid bridge. This bridge connects the subdomains of the CAD CPSase. We constructed a bacterial carAB fusion gene in which the intercistronic region codes for a hamster bridgelike sequence. The fused carAB gene directs the synthesis of a stable bifunctional polypeptide whose glutamine-dependent CPSase activity is comparable to the E. coli CPSase holoenzyme. The fusion in E. coli of the single gene counterparts of CAD demonstrates a potential model system to study the genetic events that lead to gene fusion and the creation of multienzymatic proteins.
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PMID:Evidence that mammalian glutamine-dependent carbamyl phosphate synthetase arose through gene fusion. 151 89

At least 1000 CAD/CAM (computer-aided design and computer-aided manufacturing) systems for producing restorations are in dental offices. At least nine different systems have been described; the Cerec system (Siemens, Bensheim, FRG) is the best known and most widely used. Clinical results to date suggest that the automated CAD/CAM systems can provide restorations which perform at least as well as cast restorations. There are some technique sensitivities that must be managed with the new technology. The importance of fit at the margins is a controversial issue that remains to be settled. Bond strength of composite-luted restorations is dependent on margin location and luting material properties, and on the combination of silanating, etching, and curing mechanism of the luting composite. Surface finishes equivalent to cast gold and glazed porcelain can be achieved for machinable CAD/CAM materials.
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PMID:A review of the developments in dental CAD/CAM systems. 152 Sep 34

Known risk factors for coronary artery disease are very common in the Hopkins Lupus Cohort, in spite of the fact that the average patients age is only 38.3 years. Three or more known risk factors were found in 53% of patients. Risk factors for CAD were common even in patients not on a regimen of prednisone therapy during their cohort follow-up. Hypercholesterolemia increased significantly with greater average prednisone dose. Despite the frequency of risk factors, patients' awareness of the risk of CAD was low, with only 16.9% of patients believing they were at high risk for developing CAD within 5 years. In general, awareness of individual risk factors was lower in black than in white patients with SLE. Preventive practices were most commonly addressed towards hypertension. Preventive practices directed against obesity, hypercholesterolemia, and smoking were underutilized. Whether these known risk factors are sufficient in and of themselves to explain the high frequency of CAD in the cohort (8%) or whether they are "enabling" factors acting upon endothelium damaged by immune-complex disease cannot be addressed by this study. However, both further investigation of these risk factors and attention to lifestyle and pharmacologic approaches to risk factor reduction are indicated by this study.
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PMID:Coronary artery disease risk factors in the Johns Hopkins Lupus Cohort: prevalence, recognition by patients, and preventive practices. 152 5

The frequency of angiographically defined asymptomatic CAD in patients with carotid disease is 40%. Although the prognosis of patients with asymptomatic 1-vessel or 2-vessel CAD is good (annual cardiac mortality rate less than 2%), the prognosis of asymptomatic 3-vessel disease or left main CAD is substantially less favorable (annual cardiac mortality 5-8%). Preliminary data from nonrandomized studies suggest that coronary artery bypass surgery significantly lowers cardiac mortality in patients with asymptomatic 3-vessel or left main CAD. Further studies are needed to determine 1) vascular risk factor profiles that are predictive of asymptomatic CAD in patients with cerebrovascular disease and 2) the prevalence of asymptomatic CAD, especially 3-vessel and left main CAD, in patients with a variety of subtypes of cerebrovascular disease (e.g., carotid disease, atherosclerotic vertebrobasilar disease, cardioembolism, penetrating artery disease, stroke of undetermined cause). If the prevalence of asymptomatic 3-vessel or left main CAD is high in a subset of patients with cerebrovascular disease, a randomized study comparing coronary artery bypass surgery with best medical therapy (anti-ischemic agents, lipid-lowering therapy, and aspirin) may be warranted.
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PMID:Asymptomatic coronary artery disease in patients with stroke. Prevalence, prognosis, diagnosis, and treatment. 154 10

CAD reflects an alteration in the dynamic nature of coronary conduits. This alteration in function can be precipitated by a constellation of pathologic processes and combination of risk behaviors. Nursing intervention based on knowledge of pathophysiology of CAD and its interaction with risk factors and behaviors can play an important role in prevention of sequelae and development of effective therapeutic strategies.
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PMID:Pathophysiology of coronary artery disease. 154 86

The evaluation of patients with suspected or known CAD involves a comprehensive diagnostic workup. Careful analysis of pain and the factors that influence it is a key factor in differentiating CAD from other cardiovascular and noncardiac diagnoses. The assessment of pain also serves as an important guide for the identification of appropriate diagnostic tests. An evaluation of lifestyle patterns is helpful in identifying behaviors associated with a high risk of CAD. FHP serves as a useful categorization for documentation and provides data that are complementary to the physician's traditional review of systems. The ECG is the most common initial diagnostic test; however, cardiac catheterization remains the most definitive source for the diagnosis of CAD. The sequence and use of diagnostic tests proceeds according to the patient's physiologic stability, with consideration to the risks and benefits to the individual patient. The nurse has an important role in the evaluation for CAD. The initial encounter provides an opportunity to promote the patient's full participation in treatment as well as to establish a commitment to ongoing evaluation. The nurse must be prepared to explain not only the process for the evaluation but also the sometimes unclear results to the patient. In this way, patients can be better prepared to meet the challenges of daily living with CAD.
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PMID:Evaluating the patient with coronary artery disease. 154 88


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