Adenosine deaminase prefers a distinct sugar ring conformation for binding and catalysis: kinetic and structural studies

Several recent X-ray crystal structures of adenosine deaminase (ADA) in complex with various adenosine surrogates have illustrated the preferred mode of substrate binding for this enzyme. To define more specific structural details of substrate preferences for binding and catalysis, we have studied the ADA binding efficiencies and deamination kinetics of several synthetic adenosine analogues in which the furanosyl ring is biased toward a particular conformation. NMR solution studies and pseudorotational analyses were used to ascertain the preferred furanose ring puckers (P, nu(MAX)) and rotamer distributions (chi and gamma) of the nucleoside analogues. It was shown that derivatives which are biased toward a "Northern" (3'-endo, N) sugar ring pucker were deaminated up to 65-fold faster and bound more tightly to the enzyme than those that preferred a "Southern" (2'-endo, S) conformation. This behavior, however, could be modulated by other structural factors. Similarly, purine riboside inhibitors of ADA that prefer the N hemisphere were more potent inhibitors than S analogues. These binding propensities were corroborated by detailed molecular modeling studies. Docking of both N- and S-type analogues into the ADA crystal structure coordinates showed that N-type substrates formed a stable complex with ADA, whereas for S-type substrates, it was necessary for the sugar pucker to adjust to a 3'-endo (N-type) conformation to remain in the ADA substrate binding site. These data outline the intricate structural details for optimum binding in the catalytic cleft of ADA.

Disease-specific alterations in frontal cortex brain proteins in schizophrenia, bipolar disorder, and major depressive disorder. The Stanley Neuropathology Consortium

Severe psychiatric disorders such as schizophrenia, bipolar disorder and major depressive disorder are brain diseases of unknown origin. No biological marker has been documented at the pathological, cellular, or molecular level, suggesting that a number of complex but subtle changes underlie these illnesses. We have used proteomic technology to survey postmortem tissue to identify changes linked to the various diseases. Proteomics uses two-dimensional gel electrophoresis and mass spectrometric sequencing of proteins to allow the comparison of subsets of expressed proteins among a large number of samples. This form of analysis was combined with a multivariate statistical model to study changes in protein levels in 89 frontal cortices obtained postmortem from individuals with schizophrenia, bipolar disorder, major depressive disorder, and non-psychiatric controls. We identified eight protein species that display disease-specific alterations in level in the frontal cortex. Six show decreases compared with the non-psychiatric controls for one or more diseases. Four of these are forms of glial fibrillary acidic protein (GFAP), one is dihydropyrimidinase-related protein 2, and the sixth is ubiquinone cytochrome c reductase core protein 1. Two spots, carbonic anhydrase 1 and fructose biphosphate aldolase C, show increase in one or more diseases compared to controls. Proteomic analysis may identify novel pathogenic mechanisms of human neuropsychiatric diseases.

Time trends analysis of hearing loss: an alternative approach to evaluating hearing loss prevention programs

Two general approaches for evaluating the performance of hearing loss prevention programs (HLPPs) are described in the literature: (1) a comparison of the rate of hearing loss in an HLPP with a reference population and (2) a comparison of audiometric variability or annual incidence of hearing loss with an established set of criteria that rank HLPP performance on a graded scale. This article discusses a third method, time trends analysis, which assesses patterns in hearing loss over time. Patterns may reflect program improvement (decreased hearing loss incidence over time), deterioration (a pattern of increased incidence), or stasis (unchanged incidence). To demonstrate this method, a time trends analysis was conducted on a population of 44,547 industrial workers. Subjects were divided into 11 subgroups based on year of enrollment in the HLPP (1980-1990) and followed retrospectively for 3 years to determine the incidence of hearing loss. Hazard ratios (HRs) were estimated for each subgroup by gender using the Cox Proportional Hazards model and adjusting for age, race, and hearing threshold at enrollment in the HLPP. For women, plots of adjusted HRs against enrollment years produced a statistically significant (p < 0.05) quadratic trend of an initial increase in hearing loss, followed by decreasing incidence over time. For men, there was a statistically significant linear trend of decreasing hearing loss over time. The downward trend, particularly during the late 1980s, indicates improved HLPP performance during the latter portion of the decade. Time trends analysis can be a valuable tool for assessing HLPP performance for those with access to follow-up data and ability to work with statistical models.

Purification of a jojoba embryo fatty acyl-coenzyme A reductase and expression of its cDNA in high erucic acid rapeseed

The jojoba (Simmondsia chinensis) plant produces esters of long-chain alcohols and fatty acids (waxes) as a seed lipid energy reserve. This is in contrast to the triglycerides found in seeds of other plants. We purified an alcohol-forming fatty acyl-coenzyme A reductase (FAR) from developing embryos and cloned the cDNA encoding the enzyme. Expression of a cDNA in Escherichia coli confers FAR activity upon those cells and results in the accumulation of fatty alcohols. The FAR sequence shows significant homology to an Arabidopsis protein of unknown function that is essential for pollen development. When the jojoba FAR cDNA is expressed in embryos of Brassica napus, long-chain alcohols can be detected in transmethylated seed oils. Resynthesis of the gene to reduce its A plus T content resulted in increased levels of alcohol production. In addition to free alcohols, novel wax esters were detected in the transgenic seed oils. In vitro assays revealed that B. napus embryos have an endogenous fatty acyl-coenzyme A: fatty alcohol acyl-transferase activity that could account for this wax synthesis. Thus, introduction of a single cDNA into B. napus results in a redirection of a portion of seed oil synthesis from triglycerides to waxes.

Efficacy of abciximab readministration in coronary intervention

Abciximab, an Fab monoclonal antibody fragment that blocks the platelet glycoprotein IIb/IIIa receptor, is increasingly used as an adjunct to coronary intervention. Little is known, however, about the efficacy and safety of readministration of abciximab. This study examined and characterized outcomes of patients receiving abciximab for a second time. From April 1995 to June 1997, 164 consecutive patients were readministered abciximab at our 3 institutions. We retrospectively examined and analyzed in-hospital outcomes in this cohort. The median time to readministration was 95 days. The angiographic success rate of percutaneous intervention was 99.5%. Rates and 95% confidence intervals of in-hospital events were death 2% (0.7% to 6.1%), myocardial infarction 3% (1% to 7%), coronary bypass surgery 0% (0% to 2.2%), and intracranial hemorrhage 2% (0.4% to 5.3%). Severe thrombocytopenia was observed in 4% of patients (1.4% to 7.8%) after readministration. Allergic or anaphylactic reactions were not observed. Major bleeding was associated with excessive concomitant antithrombotic therapy. Patients undergoing readministration of abciximab within 2 weeks of first administration experienced a higher incidence of severe thrombocytopenia (12% vs. 2%, p = 0.046). Thus, abciximab remains clinically efficacious when readministered as an adjunct to percutaneous coronary intervention. However, concomitant heparin administration must be carefully monitored and warfarin therapy should be avoided. Vigilant surveillance for thrombocytopenia should be employed. Reduced dosing may be necessary when abciximab is readministered within days of the initial administration.

Health effects of depleted uranium on exposed Gulf War veterans

A small group of Gulf War veterans possess retained fragments of depleted uranium (DU) shrapnel, the long-term health consequences of which are undetermined. We evaluated the clinical health effects of DU exposure in Gulf War veterans compared with nonexposed Gulf War veterans. History and follow-up medical examination were performed on 29 exposed veterans and 38 nonexposed veterans. Outcome measures employed were urinary uranium determinations, clinical laboratory values, and psychiatric and neurocognitive assessment. DU-exposed Gulf War veterans with retained metal shrapnel fragments are excreting elevated levels of urinary uranium 7 years after first exposure (range 0.01-30.7 microg/g creatinine vs 0.01- 0.05 microg/g creatinine in the nonexposed). The persistence of the elevated urine uranium suggests on-going mobilization from a storage depot which results in a chronic systemic exposure. Adverse effects in the kidney, a presumed target organ, are not present at this time, though other effects are observed. Neurocognitive examinations demonstrated a statistical relationship between urine uranium levels and lowered performance on computerized tests assessing performance efficiency. Elevated urinary uranium was statistically related to a high prolactin level (>1.6 ng/ml; P=0.04). More than 7 years after first exposure, DU-exposed Gulf War veterans with retained metal fragments continue to excrete elevated concentrations of urinary uranium. Effects related to this are subtle perturbations in the reproductive and central nervous systems.

Use of comparison populations for evaluating the effectiveness of hearing loss prevention programs

One approach for evaluating the effectiveness of Hearing loss prevention programs (HLPPs) is to compare the rate of hearing loss in a study population with that in a reference population. This approach was used to evaluate the HLPP of a population of 14,900 employees of an industrial company with branches across the United States. Three reference populations were selected from a database of 22 industrial companies compiled under the sponsorship of the National Institute for Occupational Safety and Health. The risk of hearing loss in the study population was estimated relative to each of the three reference populations using the Cox proportional hazards model after adjustment for race, age at baseline, and hearing threshold at time of enrollment in the HLPP. In comparison with the three reference populations, hearing loss was 2.1 to 3.9 times more likely to occur in study population males and 1.8 to 5.1 times more likely in study population females. The 95% confidence interval around each risk estimate precluded unity, indicating that each risk estimate was statistically significant. These results indicate that the performance of the subject HLPP needs improvement. This study demonstrated the use of comparison populations for evaluating the effectiveness of HLPPs.

Data collection instrument and procedure for systematic reviews in the Guide to Community Preventive Services. Task Force on Community Preventive Services

INTRODUCTION

A standardized abstraction form and procedure was developed to provide consistency, reduce bias, and improve validity and reliability in the Guide to Community Preventive Services: Systematic Reviews and Evidence-Based Recommendations (the Guide).

DATA COLLECTION INSTRUMENT

The content of the abstraction form was based on methodologies used in other systematic reviews; reporting standards established by major health and social science journals; the evaluation, statistical and meta-analytic literature; expert opinion and review; and pilot-testing. The form is used to classify and describe key characteristics of the intervention and evaluation (26 questions) and assess the quality of the study's execution (23 questions). Study procedures and results are collected and specific threats to the validity of the study are assessed across six categories (intervention and study descriptions, sampling, measurement, analysis, interpretation of results and other execution issues).

DATA COLLECTION PROCEDURES

Each study is abstracted by two independent reviewers and reconciled by the chapter development team. Reviewers are trained and provided with feedback.

DISCUSSION

What to abstract and how to summarize the data are discretionary choices that influence conclusions drawn on the quality of execution of the study and its effectiveness. The form balances flexibility for the evaluation of papers with different study designs and intervention types with the need to ask specific questions to maximize validity and reliability. It provides a structured format that researchers and others can use to review the content and quality of papers, conduct systematic reviews, or develop manuscripts. A systematic approach to developing and evaluating manuscripts will help to promote overall improvement of the scientific literature.

Genetic discoveries: challenges for nurses who care for children and their families

Genetic discoveries emerging from the HGP are revolutionizing health care. With the potential to promote health and minimize disease through these discoveries, pediatric nurses will need to incorporate the health, ethical, and social aspects of this knowledge into their care of children and families. Genetic advancements are creating new challenges not only for nursing practice, but also for educational curricula. While genetic information and technology bring great potential for new ways to detect and manage a wide range of pediatric health problems, nurses must ensure that this information is managed in ways that will maximize benefit and minimize potential harm to children and their families. Educational preparation is critical to the application of genetic information and testing in health care of all clients. Pediatric nurses with adequate educational preparation in genetics now have an exciting opportunity to develop new skills and roles and make a significant contribution to genetic services and the advancement of nursing knowledge of children.

Developing an evidence-based Guide to Community Preventive Services--methods. The Task Force on Community Preventive Services

Systematic reviews and evidence-based recommendations are increasingly important for decision making in health and medicine. Over the past 20 years, information on the science of synthesizing research results has exploded. However, some approaches to systematic reviews of the effectiveness of clinical preventive services and medical care may be less appropriate for evaluating population-based interventions. Furthermore, methods for linking evidence to recommendations are less well developed than methods for synthesizing evidence. The Guide to Community Preventive Services: Systematic Reviews and Evidence-Based Recommendations (the Guide) will evaluate and make recommendations on population-based and public health interventions. This paper provides an overview of the Guide's process to systematically review evidence and translate that evidence into recommendations. The Guide reviews evidence on effectiveness, the applicability of effectiveness data, (i.e., the extent to which available effectiveness data is thought to apply to additional populations and settings), the intervention's other effects (i.e., important side effects), economic impact, and barriers to implementation of interventions. The steps for obtaining and evaluating evidence into recommendations involve: (1) forming multidisciplinary chapter development teams, (2) developing a conceptual approach to organizing, grouping, selecting and evaluating the interventions in each chapter; (3) selecting interventions to be evaluated; (4) searching for and retrieving evidence; (5) assessing the quality of and summarizing the body of evidence of effectiveness; (6) translating the body of evidence of effectiveness into recommendations; (7) considering information on evidence other than effectiveness; and (8) identifying and summarizing research gaps. Systematic reviews of and evidence-based recommendations for population-health interventions are challenging and methods will continue to evolve. However, using an evidence-based approach to identify and recommend effective interventions directed at specific public health goals may reduce errors in how information is collected and interpreted, identify important gaps in current knowledge thus guiding further research, and enhance the Guide users' ability to assess whether recommendations are valid and prudent from their own perspectives. Over time, all of these advantages could help to increase agreement regarding appropriate community health strategies and help to increase their implementation.

A comparison of the effect of rocuronium and vecuronium on heart rate during gynaecological laparoscopy

The effect on intra-operative heart rate of two nondepolarising muscle relaxants, rocuronium and vecuronium, was compared in 116 fit out-patients undergoing gynaecological laparoscopic procedures. Both groups received an anaesthetic technique which differed only in the choice of muscle relaxant. Intra-operatively it was noted that patients given rocuronium (20 mg) had significantly fewer episodes of bradycardia (heart rate < 50 beat.min-1) than patients given vecuronium 4 mg (p < 0.05). Profound bradycardias (heart rate < 30 beat.min-1) did not occur in any of the patients in the rocuronium study group, whereas 5% of patients receiving vecuronium had a period of transient asystole. We conclude that, at the doses stated, rocuronium results in significantly fewer episodes of bradycardia than vecuronium when used as a muscle relaxant for laparoscopic gynaecological procedures.

Thioguanine administered as a continuous intravenous infusion to pediatric patients is metabolized to the novel metabolite 8-hydroxy-thioguanine

Thiopurine antimetabolites have been in clinical use for more than 40 years, yet the metabolism of thiopurines remains only partially understood. Data from our previous pediatric phase 1 trial of continuous i.v. infusion of thioguanine (CIVI-TG) suggested that TG was eliminated by saturable mechanism, with conversion of the drug to an unknown metabolite. In this study we have identified this metabolite as 8-hydroxy-thioguanine (8-OH-TG). The metabolite coeluted with the 8-OH-TG standard on HPLC and had an identical UV spectrum, with a lambda(max) of 350 nm. On mass spectroscopy, the positive ion, single quad scan of 8-OH-TG yielded a protonated molecular ion at 184 Da and contained diagnostic ions at m/z 167, 156, 142, and 125 Da. Incubation of TG in vitro with partially purified aldehyde oxidase resulted in 8-OH-TG formation. 8-OH-TG is the predominant circulating metabolite found in patients receiving CIVI-TG and is likely generated by the action of aldehyde oxidase.

Regional hospital improves efficiency with co-generation retrofit

Feasibility analysis of the co-generation retrofit of the Red Deer Regional Hospital pointed to a reasonable payback of capital cost and increased efficiency in operation of the facility. Budget restrictions nearly stopped the project from proceeding. Innovative construction procedures proposed by the Facility Management Group, in particular, Mr Keith Metcalfe, Director of Maintenance, allowed a worthwhile project to reach successful completion. We feel that this model can perhaps be used by similar facilities in the future to achieve their energy efficiency goals.

Painful medicine: managed care and the fate of America's major teaching hospitals

Healthcare spending in the United States has risen steadily throughout the post-World War II period as the American healthcare system has been transformed from cottage industry to big business. The increasing rate of social investment in healthcare also transformed America's major teaching hospitals. As a case in point, the University of Iowa Hospitals and Clinics saw annual operating revenues rise from $1 million in 1945 to more than $350 million in 1995, which was accompanied by an extraordinary expansion in its physical facilities and in its multifaceted operations. In the 1970s and even more so in the 1980s, however, the unceasing climb in healthcare spending fueled concern among policy experts, politicians, employers, and insurers alike. In turn, the search for effective cost controls led to the current managed care revolution. While the end of that revolution is not yet in sight, managed care has, it appears, effected significant cost savings, but at no small cost to America's major teaching hospitals and their social missions of teaching, research, and patient care. Whether those missions can survive--and, if so, in what form--in a healthcare system dominated by the managed care ethos is an increasingly important concern.

What do internal medicine residents need to enhance their diabetes care?

OBJECTIVE

To identify areas that should be targeted for improvement in care, we examined internal medicine resident practice patterns and beliefs regarding diabetes in a large urban hospital outpatient clinic.

RESEARCH DESIGN AND METHODS

Internal medicine residents were surveyed to assess the frequency at which they performed key diabetes quality of care indicators. Responses were compared with recorded performance derived from chart and laboratory database reviews. Resident attitudes about diabetes were determined using the Diabetes Attitude Survey for Practitioners. Finally, an eight-item scale was used to assess barriers to diabetes care.

RESULTS

Both self-described and recorded performance of recommended diabetes services short of national recommendations. For yearly eye examinations and lipid screening, recorded performance levels were similar to trainees' reports. However, documented inquiries about patient self-monitoring of blood glucose, performance of foot examinations, and urine protein screening were lower than trainees' reports. Some 49% of the residents selected a target HbA1c of 6.6-7.5% as an attainable goal, yet half of the patients using oral agents or insulin had HbA1c values > 8.0%. No differences in self-described or recorded performance were found by year of training. Most residents did not perceive themselves to need additional training related to diabetes care, and residents were generally neutral about patient autonomy. Patient nonadherence and time constraints within the clinic were most often cited as barriers to care.

CONCLUSIONS

The study identifies several areas that require improvement in resident care of diabetes in the ambulatory setting. Because experience during training contributes to future practice patterns, developing a program that teaches trainees how to implement diabetes practice guidelines and methods to achieve optimal glycemic control may be key to future improvements in the quality of diabetes care.

Lead: male-mediated effects on reproduction and development in the rat

The present study was designed to determine the effect of relatively low levels of lead acetate (25 and 250 ppm) exposure on fertility and offspring viability in male Sprague-Dawley rats. Protein synthesis in 2-cell embryos was monitored by [35S] methionine labeling and two-dimensional SDS gel electrophoresis. Fertility was reduced in males with blood lead levels in the range 27-60 microg/dL. Lead was found to affect initial genomic expression in embryos fathered by male rats with blood lead levels as low as 15-23 microg/dL. Dose-dependent increases were seen in an unidentified set of proteins with a relative molecular weight of approximately 70 kDa (Mr). These results indicate that male-mediated effects of lead may be observed in the 2-cell embryo. The alteration observed in embryonic gene expression with paternal lead exposure may be useful for studying the role of the paternal contribution to the activation of the embryonic genome and protein synthesis in the early embryo.

The effect of wrist angle on electrically evoked hand opening in patients with spastic hemiplegia

This paper studied the effect of wrist angle on the amount of hand opening achieved by electrical stimulation in people with spastic hemiplegia. With their forearm in pronation, subjects were asked to relax while their affected wrist was passively moved in steps of about 15 degrees from full flexion into extension. Trains of stimuli were applied to the long finger extensor muscles through surface electrodes on the forearm. At each wrist position stimulation was turned on for a few seconds until hand opening equilibrated. Wrist angle and fingertip positions were recorded using a three-dimensional (3-D) motion analysis system. Maximal displacements between thumbtip and each fingertip occurred when the wrist was fully flexed. As the wrist was extended, hand aperture achieved by electrical stimulation progressively declined, reaching zero at 40 degrees of wrist extension. We conclude that electrical stimulation can significantly increase the grasp aperture of the hemiplegic hand, but this is strongly dependent on wrist posture and accompanying voluntary effort.