Data-reporting considerations.
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Costs and Cost Analysis↗
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Hyperactive Ras as a therapeutic target in neurofibromatosis type 1.
The NF1 gene encodes neurofibromin, a GTPase-activating protein (GAP) for members of the p21(ras) (Ras) family, which negatively regulates Ras output by accelerating the conversion of active Ras. GTP to inactive Ras.GDP. Analysis of tumors from patients with neurofibromatosis type 1 (NF1) has shown biochemical evidence of hyperactive Ras as well as frequent loss of the normal NF1 allele, consistent with its role as a tumor suppressor gene. Taken together, these data suggest that novel therapeutics directed against components of the Ras signaling cascade might provide effective treatments for certain pathological complications of NF1. Here we summarize data that support a role for hyperactive Ras in NF1 disease, including Ras processing, activation, and down-regulation. We review targets for rational drug design, provide preliminary results, and discuss implications for future studies. Am. J. Med. Genet. (Semin. Med. Genet.) 89:14-22, 1999.
Drug Design↗
Implementation of the DOTS strategy for tuberculosis in the Leningrad Region, Russian Federation (1998-1999).
SETTING: The DOTS pilot project for tuberculosis control in the Leningrad Region of the Russian Federation, supported by the Finnish Lung Health Association and the World Health Organization (WHO). OBJECTIVE: To assess the efficacy of WHO-recommended standard short-course chemotherapy in newly detected pulmonary tuberculosis cases positive by smear or with extensive lung lesions suggestive of culture positivity, under project conditions. METHODS: Analysis of data on case detection, sputum smear conversion and treatment outcome based on standardised (WHO) registers from districts and a central computerised database. RESULTS: Of 859 adult pulmonary tuberculosis cases (292 smear-positive) notified in the Leningrad Region in the study period, 312 new cases were included in the project. The sputum conversion rate at the end of the second month was 82.8% and 91.1% at the end of the third month. Of bacteriologically confirmed cases, 71.3% were successfully treated, 4.9% died, 11.7% defaulted and 8.1% failed. CONCLUSION: In the first year of the pilot project in the Leningrad Region, the DOTS strategy revealed feasibility and moderate efficacy among new pulmonary tuberculosis cases who were either smear-positive or showed extensive lung lesions on chest X-ray, and who were therefore of high epidemiological and medical priority.
Adolescent↗
[The management control system of the Roma/C Local Health Authority. Financial year 2004].
The aim of this study was to describe the budgeting process of the Roma/C Local Health Authority during the 2004 financial year. The planning-control process, which included preparing regular reports, allowed performing comparisons between actual with planned results so that the necessary corrective actions could be taken in a timely manner. It also led to a confrontation between the various managers involved, regarding: 1. the conversion of ordinary regime hospital beds into day hospital beds; 2. the development of a new model of emergency care aimed at integrating care between the hospital and the community; 3. the need to implement dataware housing.
Bed Conversion↗
Lysine 2,3-aminomutase. Support for a mechanism of hydrogen transfer involving S-adenosylmethionine.
The conversion of L-lysine to L-beta-lysine is catalyzed by lysine 2,3-aminomutase. The reaction involves the interchange of the 2-amino group of lysine with a hydrogen at carbon 3. As such the reaction is formally analogous to adenosylcobalamin-dependent rearrangements. However, the enzyme does not contain and is not activated by this coenzyme. Instead it contains iron and pyridoxal phosphate and is activated by S-adenosylmethionine. Earlier experiments implicated adenosyl-C-5' of S-adenosylmethionine in the hydrogen transfer mechanism, apparently in a role similar or analogous to that of adenosyl moiety of adenosylcobalamin in the B12-dependent rearrangements. The question of whether both hydrogens or only one hydrogen at adenosyl-C-5' participate in the hydrogen-transfer process has been addressed by carrying out the lysine 2,3-aminomutase reaction with S-[5'-3H] adenosylmethionine in the presence of 10 times its molar concentration of enzyme. Under these conditions all of the tritium appeared in lysine and beta-lysine, showing that C-5'-hydrogens participate. To determine whether hydrogen transfer is compulsorily intermolecular and intramolecular, various molar ratios of [3,3-2H2]lysine and unlabeled lysine were submitted to the action of lysine 2,3-aminomutase under conditions in which 10-15% conversion to beta-lysine occurred. Mass spectral analysis of the beta-lysine for monodeutero and dideutero species showed conclusively that hydrogen transfer is both intramolecular and intermolecular. The results quantitatively support our postulate that activation of the enzyme involves a transformation of S-adenosylmethionine into a form that promotes the generation of an adenosyl-5' free radical, which abstracts hydrogen from lysine to form 5'-deoxyadenosine as an intermediate.
Amino Acid Isomerases↗
Swing-bed hospital cost and reimbursement.
Small rural hospitals can provide long-term care in acute care beds as part of the National Swing-Bed Program enacted in 1980. Medicare reimbursement for swing-bed care is based on the incremental cost concept. This article estimates the incremental cost to hospitals of swing-bed care and assesses the adequacy of swing-bed reimbursement in light of those estimates. Other swing-bed reimbursement policy issues are discussed, including payment for ancillary services, potential bundling of routine and ancillary reimbursement, and the possible incorporation of case mix into swing-bed payment determination.
Ancillary Services, Hospital↗
Hospital swing-bed care in the United States.
As a result of federal legislation implemented in 1982, hospital beds that are used to provide both long-term care and acute care are now proliferating rapidly throughout the country. Termed swing beds, such beds are currently restricted to rural areas. However, due largely to the impacts of Medicare DRG reimbursement, pressure is mounting to expand the swing-bed approach to urban settings. Swing beds appear to fill a significant gap between the relatively intense medical needs of post-acute care patients (now discharged earlier) and the capacity of our current nursing home delivery system to meet such needs. The evolution of swing beds is marked by an unusual blend of experimentation, scientific investigation, and public policy response to community and personal health care needs. This article summarizes that evolution, highlighting research findings and key policy developments. It concludes with the current status of the national swing-bed program and issues pertinent to future directions.
Bed Conversion↗
Gluconeogenesis: methodological approaches in vivo.
The complexity of the process of gluconeogenesis makes it very difficult to study in vivo. Of the many approaches used to study this process, none have proven ideal. The arterial-hepatic venous catheterization technique can provide accurate determination of the net splanchnic uptake of the various gluconeogenic precursors but gives no information as to their fate once extracted. The infusion of a labeled precursor, such as [14C]alanine, will provide qualitative information about the fate of the labeled substrate but, without complicated kinetic analysis, will not provide quantitative information on the conversion of the precursor to glucose. Though each of these individual techniques has major limitations in the study of gluconeogenesis, various combinations of these methods can provide further insight into the regulation of this complicated process. By combining the arterial-hepatic venous catheterization technique with the infusion of a labeled precursor, the splanchnic extraction of the precursor can be measured as well as the amount of the extracted precursor that is converted to glucose. The concomitant infusion of two isotopes (a 14C-labeled gluconeogenic precursor to assess substrate conversion to glucose and 3H-labeled glucose to measure glucose turnover) can also provide an accurate determination of the amount of circulating precursor that is converted to glucose. The latter technique provides no information on the splanchnic extraction of the precursor but has the advantage of being less invasive and, therefore, more applicable to man. The last two techniques measure accurately the direct conversion of the circulating precursor to glucose and, therefore, provide reliable index of gluconeogenesis.
Alanine↗
Use of 31PNMR spectroscopy to follow the time course of phosphatidylcholine chemical synthesis.
31PNMR spectroscopy is shown to be useful for studying the chemical synthesis of phosphatidylcholine from phosphatidic acid and choline. Sharp, well-resolved resonances were obtained by chelating multivalent cations, thereby enabling quantitation of reactants, products, and intermediates. The syntheses of several types of phosphatidylcholines were monitored by 31PNMR spectroscopy, including perdeuterated and headgroup spin-labeled molecules. For perdeuterated phosphatidylcholines, this analysis led to reaction conditions giving much better conversion to product than conditions previously observed. In addition, a polyphosphate side-product was identified in reactions which do not produce phosphatidylcholine, implying either a polyphosphate intermediate in the reaction mechanism, or else a competing side reaction.
Dimyristoylphosphatidylcholine↗
The SMART system: evaluation of on-line data handling for the SMA 12.
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Analog-Digital Conversion↗
Reproducibility of central venous pressures in supine and lateral positions: a pilot evaluation of the phlebostatic axis in critically ill patients.
OBJECTIVE: To determine if the phlebostatic axis (PA) can be used to obtain reproducible central venous pressures (CVP) in laterally positioned critically ill patients. DESIGN: A quasi-experimental study design was used. The outcome variable was central venous pressure. The explanatory variables were position (supine, 30 degrees right lateral, 30 degrees left lateral) and transducer leveling procedure (supine PA, upper PA, dependent PA). Each subject was used as his or her own control. SETTING: General intensive care unit of a 929 bed metropolitan teaching hospital in New South Wales, Australia. SUBJECTS: A convenience sample of 25 critically ill patients (15 men and 10 women) with an average age of 59.6 years +/- 15.2. METHOD: Each subject's baseline CVP range was collected over a 25-minute period in a supine position. CVP measurements were then obtained in the left and right lateral positions (initial lateral position alternated for each subsequent subject). When the subject was lateral, three CVP readings corresponding to the three transducer leveling procedures were taken. DATA ANALYSIS: One-way repeated measures analysis of variance (one for each leveling procedure) were performed. Clinical significance was deemed evident when the lateral CVP measurement exceeded the baseline range. RESULTS: Statistically significant changes were associated with the upper PA (p < 0.001) and the dependent PA (p < 0.001). Only the supine PA yielded statistically nonsignificant changes in CVP (p = 0.073). However, power analysis indicated that the results were not conclusive (power = 0.520). Clinical significance was determined in 100% and 92% of subjects in the left lateral and right lateral positions, respectively, when using the upper PA whereas the dependent PA yielded clinical significance in all (100%) subjects. Clinical significance was seen in 46% and 42% of subjects for the left lateral and right lateral positions, respectively, when the supine PA was used. CONCLUSION: Of the three leveling procedures, the supine PA yielded the most reproducible CVP measures. However, further studies are required before the supine PA can be recommended as a valid and reliable transducer position for CVP measurement in laterally positioned patients.
Adult↗
[Heart rhythm after conversion of ventricular tachyarrhythmia by internal shock delivery].
The purpose of this retrospective study is the analysis of dysrhythmias following internal cardioversion/defibrillation of ventricular tachycardia (VT) or fibrillation (VF) and to discuss their relevance to the therapy with automatic implantable devices. Therefore, 304 internal conversions of VT/VF during and/or after implantation of automatic defibrillators were evaluated in 51 patients. Significant post-shock arrhythmias (bradycardia, atrial fibrillation, non-sustained VT of > or = 10 cycles) were absent after 89% of internal shocks. Pauses of > 2 s were observed in 2/9 patients without VVI-back-up pacing. The heart rate was > or = 50 bpm in 10/51 patients. Atrial fibrillation occurred in 7 patients. Non-sustained, mostly polymorphic VT consisting of > or = 10 cycles followed 18/304 (6%) internal shocks in 13 patients. The VT rate was > or = 200/min in 17/18 episodes and triggered an inadequate shock once. The incidence of non-sustained VT post-shock was unrelated to shock energy, type, and duration of the converted arrhythmia. In conclusion, automatic implantable devices should provide back-up pacing. Tachycardic rhythms can mislead automatic interpretation of the effect of internal shocks.
Adult↗
[Transformation of genetically engineered oxytocinoyllysine into oxytocin].
Various methods for obtaining oxytocin from its recombinant precursor oxytocinoyllysine were studied. For splitting off the C-terminal lysine residue in oxytocinoyllysine, the carboxypeptidase B and an analogous carboxypeptidase from king crab hepatopancreas were used. Ammonolysis of oxytocinic acid methyl ester proved to be the most efficient method for the last stage of the oxytocin preparation. Reversed-phase HPLC was used for the product analysis at each stage of the recombinant oxytocinoyllysine conversion into oxytocin.
Amino Acid Sequence↗
How useful are bone turnover markers in rheumatoid arthritis? Influence of disease activity and corticosteroid therapy.
UNLABELLED: Rheumatoid arthritis is associated with osteopenia possibly related to increased bone resorption. Until recently, the markers used to evaluate bone turnover lacked specificity, and as a result studies were difficult to interpret. OBJECTIVES: To study bone remodeling in patients with rheumatoid arthritis, with special attention to the effects of corticosteroid therapy. PATIENTS AND METHODS: Forty-eight patients (36 women and 12 men) with a mean age of 54.6 +/- 11.6 years and a mean disease duration of 11 +/- 9 years were studied. Thirty-nine patients (81%) had positive tests for rheumatoid factors, and 21 (43.7%) were under corticosteroid therapy, with a mean treatment duration of 4.5 +/- 2.9 years and a mean daily dosage of 9.4 +/- 2.5 mg prednisone. A group of age- and sex-matched controls was also studied. Serum levels of procollagen Type I C-terminal propeptide (PINP), procollagen Type I N-terminal propeptide (PINP), and procollagen type I C-terminal telopeptide (ICTP) were determined in all patients and controls. The first two markers reflect bone formation and the last bone resorption. Other tests performed in each patient were the erythrocyte sedimentation rate, serum C-reactive protein, serum total alkaline phosphatase, serum osteocalcin, 24-hour urinary hydroxyproline excretion, and calcium/creatinine ratio in a morning urine sample. Several clinical parameters were used to evaluate disease activity and severity in the rheumatoid arthritis patients. RESULTS: ICTP levels were significantly elevated in the patients as compared with the controls (6.6 +/- 3.9 ng/ml versus 3.1 +/- 1.2 ng/ml, P = 0.0001), whereas no significant differences were found for PICP or PINP. Similar results were found when the analysis was confined to nonsteroid-medicated patients. Conversely, PICP levels were higher in steroid-medicated patients than in controls (P = 0.0132) and were correlated with steroid therapy duration (r = 0.436). ICTP levels were correlated with age (r = 0.3), Lee's index (r = 0.585), the Health Assessment Questionnaire score (r = 0.391), and the erythrocyte sedimentation rate (r = 0.442). Urinary hydroxyproline excretion was elevated in 41.6% of the patients. CONCLUSION: Our data suggest that rheumatoid arthritis is associated with increased bone resorption, and that steroid therapy further accelerates bone remodeling in this disease.
Adrenal Cortex Hormones↗
Analysis of interchromosomal mitotic recombination.
A novel synthetic locus is described that provides a simple assay system for characterizing mitotic recombinants. The locus consists of the TRP1 and HIS3 genes inserted into chromosome III of S. cerevisiae between the CRY1 and MAT loci. Defined trp1 and his3 alleles have been generated that allow the selection of interchromosomal recombinants in this interval. Trp+ or His+ recombinants can be divided into several classes based on coupling of the other alleles in the interval. The tight linkage of the CRY1 and MAT loci, combined with the drug resistance and cell type phenotypes that they respectively control, facilitates the classification of the recombinants without resorting to tetrad dissection. We present the distribution of spontaneous recombinants among the classes defined by this analysis. The data suggest that the recombination intermediate can have regions of symmetric strand exchange and that co-conversion tracts can extend over 1-3 kb. Continuous conversion tracts are favored over discontinuous tracts. The distribution among the classes defined by this analysis is altered in recombinants induced by UV irradiation.
Alleles↗
Single particle analysis of manganese-induced prion protein aggregates.
Prion diseases are characterized by the conversion of the cellular prion protein (PrP(C)) to a disease-specific aggregated isoform (PrP(Sc)). We have shown that Mn(2+) ions amplify aggregation, whereas Cu(2+) has an inhibitory effect. To characterize Mn(2+)-induced aggregates, we used cross-correlation analysis as well as scanning for intensely fluorescent targets in an SDS-dependent aggregation assay with fluorescently labeled PrP. We found that the effect of Mn(2+) was mainly due to the association of preformed PrP oligomers to larger aggregates, rapidly reversible by EDTA, and independent of the histidine-dependent copper-binding sites of PrP, suggesting that Mn(2+) induces reversible intermolecular binding. In contrast, the inhibitory effect of Cu(2+) required binding to histidine-containing binding sites, indicating that binding of copper affects the structure of PrP(C) which in turn modifies the susceptibility to manganese and the ability to aggregate. These findings suggest that copper and manganese may also affect prion propagation in vivo.
Binding Sites↗
Kinetic analysis of successive reactions catalyzed by bovine cytochrome p450(17alpha,lyase).
Bovine P450(17alpha,lyase) containing an additional four histidine residues at the COOH terminus was expressed in Escherichia coli and purified by one-step column chromatography using Ni-chelate resin. The membrane enzyme was incorporated into liposome membranes having similar lipid composition to that of the endoplasmic reticulum. In the presence of excess substrate, the P450-proteoliposomes metabolize pregnenolone (Delta5-steroid) to 17alpha-hydroxypregnenolone and further to dehydroepiandrosterone. The enzyme catalyzed 17alpha-hydroxylation of progesterone (Delta4-steroid) but did not form androstenedione from progesterone, although the proteoliposomes could catalyze the conversion of 17alpha-hydroxyprogesterone to androstenedione. The kinetic analysis of rapid quenching experiments showed that about 20% of the pregnenolone consumed was converted successively to dehydroepiandrosterone via a fraction of 17alpha-hydroxypregnenolone that did not dissociate from the enzyme. The rapid quenching experiments for progesterone metabolism by the proteoliposomes revealed that the dissociation rate of 17alpha-hydroxyprogesterone was 10 times faster than that of 17alpha-hydroxypregnenolone. The release of the intermediate metabolite of Delta4-steroid is sufficiently faster than the lyase reaction to prevent further reaction by the P450. It is concluded that the dissociation rates of the first hydroxylation metabolites regulate the successive reactions of P450(17alpha,lyase).
Animals↗
Reactions of substituted (methylthio)benzylidene Meldrum's acids with secondary alicyclic amines in aqueous DMSO. Evidence for rate-limiting proton transfer.
The replacement of the methylthio group of substituted methylthiobenzylidene Meldrum's acids (2-SMe-Z) by secondary alicyclic amines occurs by a three-step mechanism. The first step is a nucleophilic attachment of the amine to 2-SMe-Z to form a zwitterionic intermediate T(+/-)(A); the second step involves deprotonation of T(+/-)(A) to form T(-)(A); while the third step represents general acid-catalyzed conversion of T(-)(A) to products. At high amine and/or high KOH concentration nucleophilic attachment is rate limiting. At low amine and low KOH concentration the reaction follows a rate law that is characteristic for general base catalysis which, in principle, is consistent with either rate-limiting deprotonation of T(+/-)(A) or rate-limiting conversion of T(-)(A) to products. A detailed structure-reactivity analysis indicates that for the reactions with piperazine, 1-(2-hydroxyethyl)piperazine, and morpholine it is deprotonation of T(+/-)(A) that is rate limiting, while for the reaction with piperidine, conversion of T(-)(A) to products is rate limiting.
Journal Article↗