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Objective: The objective of this review is to synthesize the available evidence on the effectiveness of lifestyle-based interventions for reducing absolute cardiovascular disease (CVD)., Introduction: Cardiovascular disease prevention guidelines recommend tailoring the choice and intensity of preventive interventions based on absolute CVD risk score. Several studies employing lifestyle-based interventions to mitigate CVD risk have reported heterogeneous outcomes, necessitating a systematic review to provide an exhaustive summary of current evidence., Inclusion Criteria: Eligible studies will include individuals at high-risk of CVD who are at least 18 years of age, with no history of CVD at baseline, regardless of sex, ethnicity and socio-economic status. Studies that compare lifestyle-based intervention to no intervention or usual care will be included. The outcome of interest is change in absolute CVD risk from baseline to post-intervention. Experimental and quasi-experimental study designs will be included., Methods: Searches will be conducted in PubMed, EMBASE and CINAHL from the inception of each database. The search for gray literature will include ProQuest Dissertations and Theses Global, Grey Literature Report, Web of Science, BIOSIS Previews and the Proceedings database. Selected studies will be critically appraised by two independent reviewers at the study level for methodological quality. Extracted data will include details about the interventions, populations, study methods and outcomes of significance to the review question and objectives. Where possible, papers will be pooled in statistical meta-analysis. Effect sizes will be expressed as either odds ratios or standardized mean differences, and their 95% confidence intervals will be calculated for analysis., Systematic Review Registration Number: PROSPERO CRD42017073543.

Background: Sleep deprivation is common in shift work occupations, including safety-sensitive occupations. While extending sleep prior to scheduled shifts (i.e., "banking sleep") may be an intuitive strategy for fatigue mitigation, the evidence behind this strategy is unclear., Methods: We performed a systematic review of literature retrieved in searches of four databases. We examined agreement between two independent screeners, abstracted key findings, reviewed and synthesized findings, and evaluated the quality of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. The Cochrane Collaboration's risk of bias tool was used to evaluate bias of individual studies. We reported findings as prescribed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement., Results: Of the 3007 records screened, five met inclusion criteria. The inter-rater agreement for inclusion/exclusion was high (κ = 0.87). One study addressed patient safety outcomes. Four studies assessed the impact of banking sleep on performance, five assessed measures of acute fatigue, and three evaluated banking sleep on indicators of health. All five studies presented a very serious risk of bias and the quality of evidence was very low. Given these caveats, the findings, in aggregate, support banking sleep as a strategy to improve indicators of performance and acute fatigue., Conclusions: This systematic review identifies gaps in research of shift workers on the efficacy of banking sleep as a fatigue risk management strategy. The available evidence supports banking sleep prior to shiftwork as a strategy for improved patient safety, performance, and reducing acute fatigue., (Copyright © 2019 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.)

Disclosure of medical errors and adverse outcomes is expected by regulatory agencies and society as a whole. Disclosure should occur in a systematic way that ensures honesty and transparency regarding the care that has been provided. It is often appropriate to seek professional help from Clinical Risk Management to assist with disclosure of any serious safety event that resulted in harm. Disclosure of medical errors facilitates efforts to prevent recurrence of safety events., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Insomnia is frequently co-morbid with depression, with a bidirectional relationship between these disorders. There is evidence that insomnia-specific interventions, such as cognitive behavioral therapy for insomnia, may lead to improvements in depression. The purpose of this systematic review and meta-analysis is to determine whether treatment of insomnia leads to improved depression outcomes in individuals with both insomnia and depression., Methods: We conduct a systematic review and meta-analysis to explore the effect of treatment for insomnia disorder on depression in patients with both disorders., Results: Three thousand eight hundred and fifteen studies were reviewed, and 23 studies met inclusion criteria. Although all of the studies suggested a positive clinical effect of insomnia treatment on depression outcomes, most of the results were not statistically significant. Although the interventions and populations were highly variable, the meta-analysis indicates moderate to large effect size (ES) improvement in depression as measured with the Hamilton Depression Rating Scale (ES = -1.29, 95%CI [-2.11, -0.47]) and Beck Depression Inventory (ES = -0.68, 95%CI [-1.29, -0.06])., Conclusions: These results support that treating insomnia in patients with depression has a positive effect on mood. Future trials are needed to identify the subtypes of patients whose depression improves during treatment with insomnia-specific interventions, and to identify the mechanisms by which treating insomnia improves mood., (© 2018 Wiley Periodicals, Inc.)

Background: Fatigue training may be an effective way to mitigate fatigue-related risk. We aimed to critically review and synthesize existing literature on the impact of fatigue training on fatigue-related outcomes for Emergency Medical Services (EMS) personnel and similar shift worker groups., Methods: We performed a systematic literature review for studies that tested the impact of fatigue training of EMS personnel or similar shift workers. Outcomes of interest included personnel safety, patient safety, personnel performance, acute fatigue, indicators of sleep duration and quality, indicators of long-term health (e.g., cardiovascular disease), and burnout/stress. A meta-analysis was performed to determine the impact of fatigue training on sleep quality., Results: Of the 3,817 records initially identified for review, 18 studies were relevant and examined fatigue training in shift workers using an experimental or quasi-experimental design. Fatigue training improved patient safety, personal safety, and ratings of acute fatigue and reduced stress and burnout. A meta-analysis of five studies showed improvement in sleep quality (Fixed Effects SMD -0.87; 95% CI -1.05 to -0.69; p < 0.00001; Random Effects SMD -0.80; 95% CI -1.72, 0.12; p < 0.00001)., Conclusions: Reviewed literature indicated that fatigue training improved safety and health outcomes in shift workers. Further research is required to identify the optimal components of fatigue training programs to maximize the beneficial outcomes.

Background: Scheduled napping during work shifts may be an effective way to mitigate fatigue-related risk. This study aimed to critically review and synthesize existing literature on the impact of scheduled naps on fatigue-related outcomes for EMS personnel and similar shift worker groups., Methods: A systematic literature review was performed of the impact of a scheduled nap during shift work on EMS personnel or similar shift workers. The primary (critical) outcome of interest was EMS personnel safety. Secondary (important) outcomes were patient safety; personnel performance; acute states of fatigue, alertness, and sleepiness; indicators of sleep duration and/or quality; employee retention/turnover; indicators of long-term health; and cost to the system. Meta-analyses were performed to evaluate the impact of napping on a measure of personnel performance (the psychomotor vigilance test [PVT]) and measures of acute fatigue., Results: Of 4,660 unique records identified, 13 experimental studies were determined relevant and summarized. The effect of napping on reaction time measured at the end of shift was small and non-significant (SMD 0.12, 95% CI -0.13 to 0.36; p = 0.34). Napping during work did not change reaction time from the beginning to the end of the shift (SMD -0.01, 95% CI -25.0 to 0.24; p = 0.96). Naps had a moderate, significant effect on sleepiness measured at the end of shift (SMD 0.40, 95% CI 0.09 to 0.72; p = 0.01). The difference in sleepiness from the start to the end of shift was moderate and statistically significant (SMD 0.41, 95% CI 0.09 to 0.72; p = 0.01)., Conclusions: Reviewed literature indicated that scheduled naps at work improved performance and decreased fatigue in shift workers. Further research is required to identify the optimal timing and duration of scheduled naps to maximize the beneficial outcomes.

Background: This study comprehensively reviewed the literature on the impact of shorter versus longer shifts on critical and important outcomes for Emergency Medical Services (EMS) personnel and related shift worker groups., Methods: Six databases (e.g., PubMed/MEDLINE) were searched, including one website. This search was guided by a research question developed by an expert panel a priori and registered with the PROSPERO database of systematic reviews (2016:CRD42016040099). The critical outcomes of interest were patient safety and personnel safety. The important outcomes of interest were personnel performance, acute fatigue, sleep and sleep quality, retention/turnover, long-term health, burnout/stress, and cost to system. Screeners worked independently and full-text articles were assessed for relevance. Data abstracted from the retained literature were categorized as favorable, unfavorable, mixed/inconclusive, or no impact toward the shorter shift duration. This research characterized the evidence as very low, low, moderate, or high quality according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology., Results: The searched yielded n = 21,674 records. Of the 480 full-text articles reviewed, 100 reported comparisons of outcomes of interest by shift duration. We identified 24 different shift duration comparisons, most commonly 8 hours versus 12 hours. No one study reported findings for all 9 outcomes. Two studies reported findings linked to both critical outcomes of patient and personnel safety, 34 reported findings for one of two critical outcomes, and 64 did not report findings for critical outcomes. Fifteen studies were grouped to compare shifts <24 hours versus shifts ≥24 hours. None of the findings for the critical outcomes of patient and personnel safety were categorized as unfavorable toward shorter duration shifts (<24 hours). Nine studies were favorable toward shifts <24 hours for at least one of the 7 important outcomes, while findings from one study were categorized as unfavorable. Evidence quality was low or very low., Conclusions: The quality of existing evidence on the impact of shift duration on fatigue and fatigue-related risks is low or very low. Despite these limitations, this systematic review suggests that for outcomes considered critical or important to EMS personnel, shifts <24 hours in duration are more favorable than shifts ≥24 hours.

Background: Guidance for managing fatigue in the Emergency Medical Services (EMS) setting is limited. The Fatigue in EMS Project sought to complete multiple systematic reviews guided by seven explicit research questions, assemble the best available evidence, and rate the quality of that evidence for purposes of producing an Evidence Based Guideline (EBG) for fatigue risk management in EMS operations., Methods: We completed seven systematic reviews that involved searches of six databases for literature relevant to seven research questions. These questions were developed a priori by an expert panel and framed in the Population, Intervention, Comparison, and Outcome (PICO) format and pre-registered with PROSPERO. Our target population was defined as persons 18 years of age and older classified as EMS personnel or similar shift worker groups. A panel of experts selected outcomes for each PICO question as prescribed by the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. We pooled findings, stratified by study design (experimental vs. observational) and presented results of each systematic review in narrative and quantitative form. We used meta-analyses of select outcomes to generate pooled effects. We used the GRADE methodology and the GRADEpro software to designate a quality of evidence rating for each outcome., Results: We present the results for each systematic review in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). More than 38,000 records were screened across seven systematic reviews. The median, minimum, and maximum inter-rater agreements (Kappa) between screeners for our seven systematic reviews were 0.66, 0.49, and 0.88, respectively. The median, minimum, and maximum number of records retained for the seven systematic reviews was 13, 1, and 100, respectively. We present key findings in GRADE Evidence Profile Tables in separate publications for each systematic review., Conclusions: We describe a protocol for conducting multiple, simultaneous systematic reviews connected to fatigue with the goal of creating an EBG for fatigue risk management in the EMS setting. Our approach may be informative to others challenged with the creation of EBGs that address multiple, inter-related systematic reviews with overlapping outcomes.

Background: Work schedules like those of Emergency Medical Services (EMS) personnel have been associated with increased risk of fatigue-related impairment. Biomathematical modeling is a means of objectively estimating the potential impacts of fatigue on performance, which may be used in the mitigation of fatigue-related safety risks. In the context of EMS operations, our objective was to assess the evidence in the literature regarding the effectiveness of using biomathematical models to help mitigate fatigue and fatigue-related risks., Methods: A systematic review of the evidence evaluating the use of biomathematical models to manage fatigue in EMS personnel or similar shift workers was performed. Procedures proposed by the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology were used to summarize and rate the certainty in the evidence. Potential bias attached to retained studies was documented using the Cochrane Collaboration's Risk of Bias tool for experimental studies., Results: The literature search strategy, which focused on both EMS personnel and non-EMS shift workers, yielded n = 2,777 unique records. One paper, which investigated non-EMS shift workers, met inclusion criteria. As part of a larger effort, managers and dispatchers of a trucking operation were provided with monthly biomathematical model analyses of predicted fatigue in the driver workforce, and educated on how they could reduce predicted fatigue by means of schedule adjustments. The intervention showed a significant reduction in the number and cost of vehicular accidents during the period in which biomathematical modeling was used. The overall GRADE assessment of evidence quality was very low due to risk of bias, indirectness, imprecision, and publication bias., Conclusions: This systematic review identified no studies that investigated the impact of biomathematical models in EMS operations. Findings from one study of non-EMS shift workers were favorable toward use of biomathematical models as a fatigue mitigation scheduling aid, albeit with very low quality of evidence pertaining to EMS operations. We propose three focus areas of research priorities that, if addressed, could help better elucidate the utility and impact of biomathematical models as a fatigue-mitigation tool in the EMS environment.

Background: Emergency Medical Services (EMS) workers may experience fatigue as a consequence of shift work. We reviewed the literature to determine the impact of caffeine as a countermeasure to fatigue in EMS personnel and related shift workers., Methods: We employed the GRADE methodology to perform a systematic literature review and search multiple databases for research that examined the impact of caffeine on outcomes of interest, such as patient and EMS personnel safety. For selected outcomes, we performed a meta-analysis of pooled data and reported the pooled effect in the form of a Standardized Mean Difference (SMD) with corresponding 95% confidence intervals., Results: There are no studies that investigate caffeine use and its effects on EMS workers or on patient safety. Four of 8 studies in shift workers showed that caffeine improved psychomotor vigilance, which is important for performance. Caffeine decreased the number of lapses on a standardized test of performance [SMD = 0.75 (95% CI: 0.30 to 1.19), p = 0.001], and lessened the slowing of reaction time at the end of shifts [SMD = 0.52 (95% CI: 0.19 to 0.85); p = 0.002]. Finally, 2 studies reported that caffeine reduced sleep quality and sleep duration., Conclusions: Although the quality of evidence was judged to be low to moderate, when taken together, these studies demonstrate that caffeine can improve psychomotor performance and vigilance. However, caffeine negatively affects sleep quality and sleep duration. More systematic, randomized studies need to be conducted in EMS workers in order to address the critical outcomes of health and safety of EMS personnel and patients. The risk/benefit ratio of chronic caffeine use in shift workers is currently unknown.

Background: Modifying the task load of Emergency Medical Services (EMS) personnel may mitigate fatigue, sleep quality and fatigue related risks. A review of the literature addressing task load interventions may benefit EMS administrators as they craft policies related to mitigating fatigue. We conducted a systematic review of the peer-reviewed literature to address the following question: "In EMS personnel, do task load interventions mitigate fatigue, mitigate fatigue-related risks, and/or improve sleep?" (PROSPERO 2016:CRD42016040114)., Methods: We performed a systematic review of the literature that described use of randomized controlled trials, quasi-experimental studies, and observational study designs. We retained and reviewed research that involved EMS personnel or similar shift worker groups 18 years of age and older. Studies of 'healthy volunteers' and non-shift worker populations were excluded. Studies were included where the methodology of the study implied a theoretical framework of task load (or workload) affecting fatigue, and then fatigue related outcomes. Outcomes of interest included personnel safety, patient safety, personnel performance, acute fatigue, and cost to system. We used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology to summarize findings and assess quality of evidence from very low to high quality., Results: The search strategy yielded 3,394 unique records resulting in 58 records included as potentially eligible. An additional 69 studies were reviewed in full following searches of bibliographies. We detected wide variation in the description and measurement of task load in the retained and excluded research. Among 127 potentially relevant studies reviewed in full, five were judged eligible. None of the retained studies reported findings germane to personnel safety, patient safety, or cost to system. We judged most studies to have serious or very serious risk of bias., Conclusions: The effect of task load interventions on fatigue, fatigue-related risks, and/or sleep quality was not estimable and the overall quality of evidence was judged low or very low. There was considerable heterogeneity in how task load was defined and measured.

Background: This study sought to systematically search the literature to identify reliable and valid survey instruments for fatigue measurement in the Emergency Medical Services (EMS) occupational setting., Methods: A systematic review study design was used and searched six databases, including one website. The research question guiding the search was developed a priori and registered with the PROSPERO database of systematic reviews: "Are there reliable and valid instruments for measuring fatigue among EMS personnel?" (2016:CRD42016040097). The primary outcome of interest was criterion-related validity. Important outcomes of interest included reliability (e.g., internal consistency), and indicators of sensitivity and specificity. Members of the research team independently screened records from the databases. Full-text articles were evaluated by adapting the Bolster and Rourke system for categorizing findings of systematic reviews, and the rated data abstracted from the body of literature as favorable, unfavorable, mixed/inconclusive, or no impact. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology was used to evaluate the quality of evidence., Results: The search strategy yielded 1,257 unique records. Thirty-four unique experimental and non-experimental studies were determined relevant following full-text review. Nineteen studies reported on the reliability and/or validity of ten different fatigue survey instruments. Eighteen different studies evaluated the reliability and/or validity of four different sleepiness survey instruments. None of the retained studies reported sensitivity or specificity. Evidence quality was rated as very low across all outcomes., Conclusions: In this systematic review, limited evidence of the reliability and validity of 14 different survey instruments to assess the fatigue and/or sleepiness status of EMS personnel and related shift worker groups was identified.

OBJECTIVE Hemifacial spasm (HFS) is a movement disorder characterized by involuntary spasms of the facial muscles, and it can negatively impact quality of life (QOL). This retrospective study and systematic review with meta-analysis was conducted to investigate the QOL in patients with HFS following intervention with microvascular decompression (MVD) and botulinum toxin (BT). METHODS In the retrospective analysis, a QOL questionnaire was administered to all patients undergoing MVD performed by a single surgeon. The QOL questionnaire included unique questions developed based on the authors' experience with HFS patients in addition to the health-related QOL HFS-8 questionnaire. The authors also report on a systematic review of the English literature providing outcomes and complications in patients with HFS undergoing treatment with either MVD or BT. RESULTS Regarding the retrospective analysis, 242 of 331 patients completed the questionnaire. The mean score of the 10 QOL questions improved from 22.78 (SD 9.83) to 2.17 (SD 5.75) following MVD (p < 0.001). There was significant improvement across all subscales of the questionnaire between pre- and postoperative responses (p < 0.001). Regarding the systematic review, it is reported that approximately 90% of patients undergoing MVD for HFS experience a complete recovery from symptoms, whereas the mean peak improvement of symptoms following treatment with BT is 77%. Furthermore, patients undergoing MVD reported a greater improvement in the mean supplemental index of QOL as compared with patients receiving BT therapy. CONCLUSIONS Microvascular decompression offers a significant improvement in QOL in well-selected patients suffering from HFS, and may offer an increased benefit for QOL over BT injections.

Background: Greater than half of Emergency Medical Services (EMS) personnel report work-related fatigue, yet there are no guidelines for the management of fatigue in EMS. A novel process has been established for evidence-based guideline (EBG) development germane to clinical EMS questions. This process has not yet been applied to operational EMS questions like fatigue risk management. The objective of this study was to develop content valid research questions in the Population, Intervention, Comparison, and Outcome (PICO) framework, and select outcomes to guide systematic reviews and development of EBGs for EMS fatigue risk management., Methods: We adopted the National Prehospital EBG Model Process and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework for developing, implementing, and evaluating EBGs in the prehospital care setting. In accordance with steps one and two of the Model Process, we searched for existing EBGs, developed a multi-disciplinary expert panel and received external input. Panelists completed an iterative process to formulate research questions. We used the Content Validity Index (CVI) to score relevance and clarity of candidate PICO questions. The panel completed multiple rounds of question editing and used a CVI benchmark of ≥0.78 to indicate acceptable levels of clarity and relevance. Outcomes for each PICO question were rated from 1 = less important to 9 = critical., Results: Panelists formulated 13 candidate PICO questions, of which 6 were eliminated or merged with other questions. Panelists reached consensus on seven PICO questions (n = 1 diagnosis and n = 6 intervention). Final CVI scores of relevance ranged from 0.81 to 1.00. Final CVI scores of clarity ranged from 0.88 to 1.00. The mean number of outcomes rated as critical, important, and less important by PICO question was 0.7 (SD 0.7), 5.4 (SD 1.4), and 3.6 (SD 1.9), respectively. Patient and personnel safety were rated as critical for most PICO questions. PICO questions and outcomes were registered with PROSPERO, an international database of prospectively registered systematic reviews., Conclusions: We describe formulating and refining research questions and selection of outcomes to guide systematic reviews germane to EMS fatigue risk management. We outline a protocol for applying the Model Process and GRADE framework to create evidence-based guidelines.

Study Objectives: Obstructive sleep apnea (OSA) is an independent risk factor for hypertension (HTN). Increasing evidence from animal and human studies suggests that HTN exacerbates OSA. We performed a systematic review and meta-analysis of studies evaluating the effect of anti-hypertensive medications on the severity of OSA., Methods: A literature search of PubMed and Embase was done using search concepts of OSA, HTN, and drug classes used to treat HTN. Studies that reported changes in the severity of OSA objectively by using apnea-hypopnea index (AHI) or respiratory disturbance index (RDI) were included. Pooled mean difference estimates were calculated. Tests for heterogeneity, publication bias, and subgroup sensitivity analysis were conducted., Results: Of 27,376 studies screened, only 11 met inclusion criteria, including 5 randomized controlled trials and 6 single-arm prospective trials. The pooled mean difference estimate (95% confidence interval [CI]), based on a random-effects model, was -5.69 (95% CI -10.74 to -0.65), consistent with an overall decrease in AHI or RDI attributable to antihypertensive medications. The effect size was even more pronounced, -14.52 (95% CI -25.65 to -3.39), when only studies using diuretics were analyzed. There was no significant heterogeneity or publication bias among the studies. Meta-regression indicated neither age, baseline AHI, nor change in systolic/diastolic blood pressure influenced the results., Conclusions: Collectively, findings from these relatively small, short-term studies tend to support the contention that treatment with antihypertensive agents confers a statistically significant, albeit small, reduction in the severity of OSA, which may be more pronounced with the use of diuretics., (© 2016 American Academy of Sleep Medicine.)

Objective: Waterpipe tobacco smoking (WTS) is an emerging trend worldwide. To inform public health policy and educational programming, we systematically reviewed the biomedical literature to compute the inhaled smoke volume, nicotine, tar, and carbon monoxide (CO) associated with a single WTS session and a single cigarette., Methods: We searched seven biomedical bibliographic databases for controlled laboratory or natural environment studies designed to mimic human tobacco consumption. Included studies quantified the mainstream smoke of a single cigarette and/or single WTS session for smoke volume, nicotine, tar, and/or CO. We conducted meta-analyses to calculate summary estimates for the inhalation of each unique substance for each mode of tobacco consumption. We assessed between-study heterogeneity using chi-squared and I-squared statistics., Results: Sufficient data from 17 studies were available to derive pooled estimates for inhalation of each exposure via each smoking method. Two researchers working independently abstracted measurement of smoke volume in liters, and nicotine, tar, and CO in milligrams. All numbers included in meta-analyses matched precisely between the two researchers (100% agreement, Cohen's k=1.00). Whereas one WTS session was associated with 74.1 liters of smoke inhalation (95% confidence interval [CI] 38.2, 110.0), one cigarette was associated with 0.6 liters of smoke (95% CI 0.5, 0.7). One WTS session was also associated with higher levels of nicotine, tar, and CO., Conclusions: One WTS session consistently exposed users to larger smoke volumes and higher levels of tobacco toxicants compared with one cigarette. These computed estimates may be valuable to emphasize in prevention programming.

A common endeavor shared by physicians practicing in specialty fields of Radiology and Obstetrics and Gynecology is the comprehensive care and diagnosis of women with breast problems and breast disease. Because each specialty provides its respective clinical expertise in breast health, each also shares a concern, which is the high risk of litigation associated with a missed or delayed diagnosis of breast cancer. This shared concern is well documented for both specialties. Instead, it is argued that physicians are better prepared by engaging in the practice of evidence-based breast care in their respective specialties., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Introduction: Single-site laparoscopy is gaining acceptance in many surgical fields including gynecology. The purpose of this report is to demonstrate the technique and outcome for removing a large adnexal mass through a single site., Case Description: A 41-y-old female was referred to gynecology oncology for increased abdominal girth for 3 mo. An ultrasound confirmed a benign-appearing, 37-cm left adnexal mass. The mass was removed through a single-site laparoscopic incision with the aid of drainage and a morcellator. The operating time was 84 min. The patient was discharged 2 h and 35 min later with full return to normal activity in 5 d., Conclusion: Large, benign-appearing adnexal masses can be managed safely with superior cosmetic results using single-site laparoscopy.

Background: Klippel-Trenaunay syndrome is a rare disease characterized by capillary malformationsand soft tissue and bony hypertrophy and atypical varicosities. Management of this syndrome is focused primarily on treatment of the complications that arise from these malformations. Ascites and lymphedema are two of the more common complications in these patients., Case: A 15-year-old female with Klippel-Trenaunay syndrome presented with chylous ascites, vaginal drainage, and unilateral lower extremity lymphedema. Treatment included dilation, hysteroscopy and curettage, and laparoscopic evacuation of abdomino-pelvic ascites with resolution of symptoms for 32 months. Repeat laparoscopic drainage was successful and remains symptom free after 12 months., Conclusion: Vaginal drainage of chylous ascites is a rare complication from Klippel-Trenaunay syndrome and can be successfully managed by techniques to remove abdomino-pelvic ascites., (Copyright © 2012 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.)

The frequency of surgical procedures in the office setting is increasing, and patient safety in this setting now has an expanded focus. Methods and strategies, including Ambulatory Patient Safety Guidelines, results tracking, communication, and risk management principles, will be reviewed in this chapter.

Up to 14 percent of women experience irregular or excessively heavy menstrual bleeding. This abnormal uterine bleeding generally can be divided into anovulatory and ovulatory patterns. Chronic anovulation can lead to irregular bleeding, prolonged unopposed estrogen stimulation of the endometrium, and increased risk of endometrial cancer. Causes include polycystic ovary syndrome, uncontrolled diabetes mellitus, thyroid dysfunction, hyperprolactinemia, and use of antipsychotics or antiepileptics. Women 35 years or older with recurrent anovulation, women younger than 35 years with risk factors for endometrial cancer, and women with excessive bleeding unresponsive to medical therapy should undergo endometrial biopsy. Treatment with combination oral contraceptives or progestins may regulate menstrual cycles. Histologic findings of hyperplasia without atypia may be treated with cyclic or continuous progestin. Women who have hyperplasia with atypia or adenocarcinoma should be referred to a gynecologist or gynecologic oncologist, respectively. Ovulatory abnormal uterine bleeding, or menorrhagia, may be caused by thyroid dysfunction, coagulation defects (most commonly von Willebrand disease), endometrial polyps, and submucosal fibroids. Transvaginal ultrasonography or saline infusion sonohysterography may be used to evaluate menorrhagia. The levonorgestrel-releasing intrauterine system is an effective treatment for menorrhagia. Oral progesterone for 21 days per month and nonsteroidal anti-inflammatory drugs are also effective. Tranexamic acid is approved by the U.S. Food and Drug Administration for the treatment of ovulatory bleeding, but is expensive. When clear structural causes are identified or medical management is ineffective, polypectomy, fibroidectomy, uterine artery embolization, and endometrial ablation may be considered. Hysterectomy is the most definitive treatment.

Objective: Describe characteristics, compliance, efficacy, and side effect profile of adolescents and young women who use intrauterine contraception (IC)., Study Design: Retrospective chart review of adolescent and young women who had IC devices placed over a 3-year period. Comparative statistics between devices and population characteristics were performed using the Fisher exact and the t test., Results: Eighty-nine patients were included in the study. The mean age at insertion was 19.5 years (range 16-22 years). Copper was used in 13% of patients; levonorgestrel (LNG) was used in 87%. The mean duration of use was 331.3 days (copper vs LNG; P = .2254). Side effects included infection (9%, but no pelvic inflammatory disease), pain (28%), partner felt strings (9%), and bleeding (32%). Reasons for removal included side effects (25%), desired fertility (5%), expulsion (3%), and pregnancy (2%). There were no pregnancies associated with the LNG IC, and there were fewer removals because of side effects than with the copper IUD (P = .0180)., Conclusion: IC is a reliable method of contraception in teens and young adults. There were fewer removals because of side effects in the LNG group, although overall other variables are similar between methods., (Copyright © 2011 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.)

Trauma during pregnancy has presented very unique challenges over the centuries. From the first report of Ambrose Pare of a gunshot wound to the uterus in the 1600s to the present, there have existed controversies and inconsistencies in diagnosis, management, prognostics, and outcome. Anxiety is heightened by the addition of another, smaller patient. Trauma affects 7% of all pregnancies and requires admission in 4 of 1000 pregnancies. The incidence increases with advancing gestational age. Just over half of trauma during pregnancy occurs in the third trimester. Motor vehicle crashes comprise 50% of these traumas, and falls and assaults account for 22% each. These data were considered to be underestimates because many injured pregnant patients are not seen at trauma centers. Trauma during pregnancy is the leading cause of nonobstetric death and has an overall 6% to 7% maternal mortality. Fetal mortality has been quoted as high as 61% in major trauma and 80% if maternal shock is present. The anatomy and physiology of pregnancy make diagnosis and treatment difficult.

The challenges inherent in medical education are multiple, including recognition of different learning styles among students, incorporation of the Accreditation Council for Graduate Medical Education competencies and outcomes measurement into the curriculum, and compliance with mandated duty hours along with a heightened awareness of patient safety required by our regulatory institutions. With the requirement that safety become an explicit part of the residency curriculum across all specialties, educators are charged with innovative ways of achieving this goal. The following commentary addresses this need and suggests an innovative approach to the traditional daily rounds' SOAP (subjective, objective, assessment, and plan) note to incorporate a second S for safety. The use of a SOAPS note elevates each encounter by integrating quality and error avoidance as a component of care. This method teaches the next generation of physicians the importance of patient safety as an integral part of every doctor-patient interaction.

Background: Science has developed from a solitary pursuit into a team-based collaborative activity and, more recently, into a multidisciplinary research enterprise. The increasingly collaborative character of science, mandated by complex research questions and problems that require many competencies, requires that researchers lower the barriers to the creation of collaborative networks of experts, such as communities of practice (CoPs)., Objectives: The aim was to assess the information needs of prospective members of a CoP in an emerging field, dental informatics, and to evaluate their expectations of an e-community in order to design a suitable electronic infrastructure., Methods: A Web-based survey instrument was designed and administered to 2768 members of the target audience. Benefit expectations were analyzed for their relationship to (1) the respondents' willingness to participate in the CoP and (2) their involvement in funded research. Two raters coded the respondents' answers regarding expected benefits using a 14-category coding scheme (Kappa = 0.834)., Results: The 256 respondents (11.1% response rate) preferred electronic resources over traditional print material to satisfy their information needs. The most frequently expected benefits from participation in the CoP were general information (85% of respondents), peer networking (31.1%), and identification of potential collaborators and/or research opportunities (23.2%)., Conclusions: The competitive social-information environment in which CoPs are embedded presents both threats to sustainability and opportunities for greater integration and impact. CoP planners seeking to support the development of emerging biomedical science disciplines should blend information resources, social search and filtering, and visibility mechanisms to provide a portfolio of social and information benefits. Assessing benefit expectations and alternatives provides useful information for CoP planners seeking to prioritize community infrastructure development and encourage participation.

Medical errors became a common topic of conversation with the release of the Institute of Medicine's "To Err Is Human" in November of 1999. This release reported that as many as 98,000 people die each year from inpatient medical errors. Putting this into perspective, deaths from medical errors surpassed deaths from breast cancer, motor vehicle accidents, and AIDS. Furthermore, medication errors account for more deaths annually than workplace injuries. This article addresses communication of adverse outcomes to patients (disclosure) through transparency and apology.

Dental Informatics (DI) is the application of computer and information science to improve dental practice, research, education, and program administration. As an emerging field, dental informatics faces many challenges and barriers to establishing itself as a full-fledged discipline; these include the small number of geographically dispersed DI researchers as well as the lack of DI professional societies and DI-specific journals. E-communities have the potential to overcome these obstacles by bringing researchers together at a resources hub and giving them the ability to share information, discuss topics, and find collaborators. In this paper, we discuss our assessment of the information needs of individuals interested in DI and discuss their expectations for an e-community so that we can design an optimal electronic infrastructure for the Dental Informatics Online Community (DIOC). The 256 survey respondents indicated they prefer electronic resources over traditional print material to satisfy their information needs. The most frequently expected benefits from participation in the DIOC were general information (85% of respondents), peer networking (31.1%), and identification of potential collaborators and/or research opportunities (23.2%). We are currently building the DIOC electronic infrastructure: a searchable publication archive and the learning center have been created, and the people directory is underway. Readers are encouraged to access the DIOC Website at www.dentalinformatics.com and initiate a discussion with the authors of this paper.

Objective: To investigate the relationship between ERAS-based preinterview scores, residency program postinterview scores and candidate rank order for the match., Study Design: Two hundred sixty-three candidates' preinterview and postinterview scores and rank order were evaluated. The rank order was stratified as 1-4, 5-8, 9-12, > 13 and unranked. Spearman's p statistical analysis was used., Results: There was a moderate relationship, r2 = 0.543, between preinterview and postinterview scores for all applicants. There was a significant inverse correlation between preinterview score and rank order, r2 = -0.763, and for the postinterview and rank order, r2 = -0.768. However, there were no significant relationships between factors significant for the top 4 ranked candidates., Conclusion: Preinterview and postinterview scores significantly correlated with each other and with the rank order list except for top-ranked candidates. Other factors may influence the rank order list.

Objective: To compare the use of episiotomy by private practitioners vs. resident staff and to determine if number of years in practice influences episiotomy use., Study Design: A retrospective chart review of vaginal deliveries at 35 weeks or greater between January 2001 and June 2001. The number of years in practice by each private physician was documented. Independent sample t tests and chi2 tests were used to analyze data., Results: In 995 deliveries, episiotomies were performed in 6% of low-risk resident deliveries vs. 26% of low-risk private deliveries (p<0.001). Physicians in practice > or = 15 years performed episiotomies in 32% of low-risk births. Physicians in practice <15 years performed episiotomies in 22% of low-risk births (p = 0.027)., Conclusion: Deliveries performed by private practitioners are associated with a higher rate of episiotomy than those by resident staff. The number of episiotomies appears to increase by number of years in practice.

The implementation of evidence-based practice (EBP) requires acquisition and use of a complex set of skills, including the ability to locate and critically evaluate clinically relevant research literature. In this article, we discuss information resources and tools that may be of value to educators faced with the task of teaching students to search for and evaluate research-based evidence. In addition, we discuss how health sciences librarians, with the use of new models of information instruction and delivery, can work with nursing faculty in developing curricula for training students in EBP.

The purpose of this study was to determine how a medical student's self-assessment at the completion of the third-year Ob/gyn clerkship compares with the institution's final grades at Lehigh Valley Hospital. From November 2002 to November 2003 at completion of each six-week Ob/gyn clerkship rotation, 47 medical students assessed themselves on the following parameters: fund of knowledge, personal attitude, clinical problem-solving skills, written/verbal skills, and technical skills. Additionally, they were asked to predict their performance on the NBME Shelf Exam. Their assessments were then compared with their final clerkship grades in each of the above parameters. Chi-squared and Kendall-tau tests were used to analyse the data for degree of agreement and association, respectively. There was a statistically significant weak to moderate, positive correlation between students' self-assessment and final clerkship grade for written/verbal skills (p = 0.002, r = 0.390). A statistically significant agreement between raters was also revealed for written/verbal skills (p = 0.003). Weak, non-statistically significant, positive relationships were revealed for fund of knowledge, clinical problem-solving and technical skills. A weak, negative, non-significant relationship was revealed for personal attitudes, and there was no statistically significant relationship between students' prediction of NBME score and categorized true score (p = 0.717, r = 0.49). At the end of their Ob/gyn clerkship, third-year medical students are better at assessing their technical and written/verbal skills than their global fund of knowledge and personal attitudes. These results may suggest that students are not aware of their own personal attitudes and communication skills and how they can affect their effectiveness as a physician.

Major depressive disorder is associated with considerable morbidity, disability, and risk for suicide. Treatments for depression most commonly include antidepressants, psychotherapy, or the combination. Little is known about predictors of treatment response for depression. In this study, 681 patients with chronic forms of major depression were treated with an antidepressant (nefazodone), Cognitive Behavioral Analysis System of Psychotherapy (CBASP), or the combination. Overall, the effects of the antidepressant alone and psychotherapy alone were equal and significantly less effective than combination treatment. Among those with a history of early childhood trauma (loss of parents at an early age, physical or sexual abuse, or neglect), psychotherapy alone was superior to antidepressant monotherapy. Moreover, the combination of psychotherapy and pharmacotherapy was only marginally superior to psychotherapy alone among the childhood abuse cohort. Our results suggest that psychotherapy may be an essential element in the treatment of patients with chronic forms of major depression and a history of childhood trauma.

Research on environmentally related chemical contaminants in breast milk spans several decades and dozens of countries. The ability to use this research as an environmental indicator is limited because of a lack of consistent protocols. Data on xenobiotics in breast milk are influenced by choices in sample selection, sample pooling, analysis, and reporting. In addition, most studies have focused only on a small panel of persistent organic pollutants, despite indications that a wide range of additional chemical contaminants may also enter breast milk. Despite these limitations, however, it is possible to draw some generalizations. In this paper we review available data on levels of organochlorine pesticides, polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs), polybrominated diphenyl ethers (PBDEs), metals, and solvents in breast milk. Examples drawn from around the world illustrate the available data and the patterns that have appeared in various areas over time. Over the past few decades, levels of the organochlorine pesticides, PCBs, and dioxins have declined in breast milk in countries where these chemicals have been banned or otherwise regulated. In contrast, the levels of PBDEs are rising. Regional differences in levels of xenobiotics in breast milk are related to historical and current local use patterns. Diet is a major factor that influences breast milk levels of persistent organic pollutants, with patterns in fish consumption playing a particularly significant role. Improved global breast milk monitoring programs would allow for more consistent data on trends over time, detection of new xenobiotics in breast milk, and identification of disproportionately exposed populations.

Objective: To determine if preeclampsia is an immunologic disease process consistent with a host-vs.-graft reaction by examining differences in immunoglobulin deposition at the maternal fetal interface (Nitabuch's layer) in preeclamptic patients., Study Design: A prospective study of patients at Lehigh Valley Hospital was conducted between July 1993 and April 1994. Group 1 (study) consisted of 11 primigravid women meeting the criteria for the diagnosis of preeclampsia. Group 2 (control) consisted of 11 primigravid women who had an uncomplicated pregnancy. At delivery, basal plate placental specimens were obtained, fixed, and processed for study by a blinded observer utilizing IgG, IgA, IgM, IgE immunofluorescence techniques. The placenta was then sent to a gynecologic pathologist for blinded evaluation and measurement of Nitabuch's membrane by light microscopy., Results: Taking the average width of 3 measurements of Nitabuch's membrane by light microscopy revealed no significant difference (group 1, .1839 mm vs. group 2, .1555 mm). Immunofluorescence techniques revealed that the thickness of immunofluorescence of Nitabuch's membrane was significantly greater in the study group vs. the control group (157.48 pixels vs. 63.80 pixels, P = .006, respectively)., Conclusion: Evaluation of the maternal-fetal interface reveals the deposition of increased immunoglobulins, the physiology of which may be similar to nephropathies as seen in systemic disease processes. The deposition of immunoglobulins may be associated with a common antigen which may point to an immunologic etiology for preeclampsia in some women.

A retrospective study was performed comparing centralized monitoring to noncentralized monitoring in regard to perinatal outcome. The study was conducted at Lehigh Valley Hospital (Allentown, PA) between August 1994 and February 1995. All deliveries during a 28-week-period were studied retrospectively. The study was designed such that for 14 weeks all patients were centrally monitored (Group A). During the following 14 weeks, no patients were centrally monitored (Group B). Patients not requiring monitoring, such as elective cesarean sections, were excluded from the study. The variables that were studied were the 5-minute Apgar, cord blood pH, perinatal mortality, admissions to the neonatal intensive care unit (NICU), spontaneous vaginal deliveries, cesarean sections, and operative vaginal deliveries. A total of 1,622 deliveries occurred during the 28 weeks of antenatal care. Group A consisted of 805 centralized monitored patients and Group B had 817 noncentralized monitored patients. There was no statistical difference in the 5-minute Apgar, umbilical artery pH, perinatal mortality, or the NICU admissions between the two groups. However, there was a significant statistical difference in the percent of cesarean sections performed for nonreassuring fetal heart rate tracings (Group A, 17.89% vs. Group B, 12.16%; P = 0.02). The overall cesarean section rate was increased in the centrally monitored group (Group A, 23.6% vs. Group B, 18.1%; P = 0.01). There were also statistically significant differences in operative vaginal deliveries (forceps and vacuum) for fetal heart rate abnormalities between Group A, 0.52% vs. Group B, .39% (P = 0.05). Centralized monitoring may be associated with an increase in the overall cesarean section rate. In addition, the rate of operative vaginal and abdominal deliveries appears to be increased for the indication of nonreassuring fetal heart rate tracings with the use of centralized monitoring.

13C and 15N isotope effects have been measured for the aspartate transcarbamylase (ATCase) reaction in an effort to elucidate the chemical mechanism of this highly regulated enzyme. The observed 15(V/K(asp))H2O value for the ATCase holoenzyme at saturing carbamyl phosphate and 12 mM L-aspartate is 1.0045 at pH 7.5, and this value remains unchanged in the presence of 5 mM ATP (activator) or 5 mM CTP (inhibitor). The fact that the isotope effect is not changed by the allosteric modifiers supports the conclusion that the kinetic properties of the active form of ATCase are not influenced by ATP or CTP. The observed 15(V/K(asp)) values for the catalytic subunit of ATCase are also the same as those determined for the holoenzyme, suggesting that the chemical mechanisms of both enzyme species are the same. Quantitative analysis of 13C and 15N isotope effects in both H2O and D2O has led to the proposal of a chemical model for the ATCase reaction which involves a precatalytic conformational change to form an activated complex that facilitates deprotonation of L-aspartate by an enzyme functional group. Nucleophilic attack on the carbonyl carbon of carbamyl phosphate by the alpha-amino group of L-aspartate results in the formation of a tetrahedral intermediate. An intramolecular proton transfer leads to formation of products N-carbamyl-L-aspartate and inorganic phosphate.

The primary and secondary 18O isotope effects for the alkaline (KOH) and enzymatic (phosphotriesterase) hydrolysis of two phosphotriesters, O,O-diethyl p-nitrophenyl phosphate (I) and O,O-diethyl O-(4-carbamoylphenyl) phosphate (II), are consistent with an associative mechanism with significant changes in bond order to both the phosphoryl and phenolic leaving group oxygens in the transition state. The synthesis of [15N, phosphoryl-18O]-, [15N, phenolic-18O]-, and [15N]-O,O-diethyl p-nitrophenyl phosphate and O,O-diethyl O-(4-carbamoylphenyl)phosphate is described. The primary and secondary 18O isotope effects for the alkaline hydrolysis of compound I are 1.0060 and 1.0063 +/- 0.0001, whereas for compound II they are 1.027 +/- 0.002 and 1.025 +/- 0.002, respectively. These isotope effects are consistent with the rate-limiting addition of hydroxide and provide evidence for a SN2-like transition state with the absence of a stable phosphorane intermediate. For the enzymatic hydrolysis of compound I, the primary and secondary 18O isotope effects are very small, 1.0020 and 1.0021 +/- 0.0004, respectively, and indicate that the chemical step in the enzymatic mechanism is not rate-limiting. The 18O isotope effects for the enzymatic hydrolysis of compound II are 1.036 +/- 0.001 and 1.0181 +/- 0.0007, respectively, and are comparable in magnitude to the isotope effects for alkaline hydrolysis, suggesting that the chemical step is rate-limiting. The relative magnitude of the primary 18O isotope effects for the alkaline and enzymatic hydrolysis of compound II reflect a transition state that is more progressed for the enzymatic reaction.

Deuterium isotope effects and 13C isotope effects with deuterium- and protium-labeled malate have been obtained for both NAD- and NADP-malic enzymes by using a variety of alternative dinucleotide substrates. With nicotinamide-containing dinucleotides as the oxidizing substrate, the 13C effect decreases when deuterated malate is the substrate compared to the value obtained with protium-labeled malate. These data are consistent with a stepwise chemical mechanism in which hydride transfer precedes decarboxylation of the oxalacetate intermediate as previously proposed [Hermes, J. D., Roeske, C. A., O'Leary, M. H., & Cleland, W. W. (1982) Biochemistry 21, 5106]. When dinucleotide substrates such as thio-NAD, 3-acetylpyridine adenine dinucleotide, and 3-pyridinealdehyde adenine dinucleotide that contain modified nicotinamide rings are used, the 13C effect increases when deuterated malate is the substrate compared to the value obtained with protium-labeled malate. These data, at face value, are consistent with a change in mechanism from stepwise to concerted for the oxidative decarboxylation portion of the mechanism. However, the increase in the deuterium isotope effect from 1.5 to 3 with a concomitant decrease in the 13C isotope effect from 1.034 to 1.003 as the dinucleotide substrate is changed suggests that the reaction may still be stepwise with the non-nicotinamide dinucleotides. A more likely explanation is that a beta-secondary 13C isotope effect accompanies hydride transfer as a result of hyperconjugation of the beta-carboxyl of malate as the transition state for the hydride transfer step is approached.(ABSTRACT TRUNCATED AT 250 WORDS)

A thiol group at the malate-binding site of the NAD-malic enzyme from Ascaris suum has been modified to thiocyanate. The modified enzyme generally exhibits slight increases in KNAD and Ki metal and decreases in Vmax as the metal size increases from Mg2+ to Mn2+ to Cd2+, indicative of crowding in the site. The Kmalate value increases 10- to 30-fold, suggesting that malate does not bind optimally to the modified enzyme. Deuterium isotope effects on V and V/Kmalate increase with all three metal ions compared to the native enzyme concomitant with a decrease in the 13C isotope effect, suggesting a switch in the rate limitation of the hydride transfer and decarboxylation steps with hydride transfer becoming more rate limiting. The 13C effect decreases only slightly when obtained with deuterated malate, suggestive of the presence of a secondary 13C effect in the hydride transfer step, similar to data obtained with non-nicotinamide-containing dinucleotide substrates for the native enzyme (see the preceding paper in this issue). The native enzyme is inactivated in a time-dependent manner by Cd2+. This inactivation occurs whether the enzyme alone is present or whether the enzyme is turning over with Cd2+ as the divalent metal activator. Upon inactivation, only Cd2+ ions are bound at high stoichiometry to the enzyme, which eventually becomes denatured. Conversion of the active-site thiol to thiocyanate makes it more difficult to inactivate the enzyme by treatment with Cd2+.

Secondary 18O isotope effects in the gamma-position of ATP have been measured on phosphoryl transfer catalyzed by yeast hexokinase in an effort to deduce the structure of the transition state. The isotope effects were measured by the remote-label method with the exocyclic amino group of adenine as the remote label. With glucose as substrate, the secondary 18O isotope effect per 18O was 0.9987 at pH 8.2 and 0.9965 at pH 5.3, which is below the pK of 6.15 seen in the V/K profile for MgATP. With the slow substrate 1,5-anhydro-D-glucitol, the value was 0.9976 at pH 8.2. While part of the inverse nature of the isotope effect may result from an isotope effect on binding, the more inverse values when catalysis is made more rate limiting by decreasing the pH or switching to a slower substrate suggest a dissociative transition state for phosphoryl transfer, in agreement with predictions from model chemistry. The 18O equilibrium isotope effect for deprotonation of HATP3- is 1.0156, while Mg2+ coordination to ATP4- does not appear to be accompanied by an 18O isotope effect larger than 1.001.

Six of 10 hamsters fed a single metacercarial cyst of Echinostoma caproni (single-worm infections) and 13 of 19 hamsters fed either 2 or 5 cysts (multiple-worm infections) were infected with adult echinostomes at necropsy 22 days post-infection. Considerable histopathological changes to the small intestine occurred in hamsters carrying single-worm infections. There were no differences in either mean length, width or wet weight of echinostomes in single- versus multiple-worm infections. The mean number of eggs/worm from single-worm infections (525) was significantly greater than that from multiple-worm infections (288). The average percentage of fully developed miracidia/worm from single worms (94%) was similar to that from worms in multiple infections (92-95%). Single worms of E. caproni were capable of self-fertilization and production of viable eggs. Miracidia derived from single worms were as capable of infecting laboratory-reared Biomphalaria glabrata and producing patent rediae as were those from multiple infections.

The half-time for the initial burst seen when a slow-binding inhibitor is present in an enzyme assay decreases from 0.693/k4 to 0.693/(k3 + k4) as the concentration of the slow-binding inhibitor is increased from zero to infinity (k3 and k4 are forward and reverse rate constants for the isomerization causing the slow-binding behavior). If the inhibitor solution contains a classical reversible inhibitor in addition to the slow-binding one, the half-time decreases from the same limit at zero inhibitor to a level which is higher at infinite inhibitor concentration (k3 is divided by (1 + xKi/Kj), where x is the ratio of classical and slow-binding inhibitor concentrations, and Ki and Kj are their initial inhibition constants before the slow-binding phase). Thus if one is using a racemic inhibitor, both enantiomers of which inhibit initially but only one of which shows slow-binding behavior, one will not obtain the correct parameters for the pure slow-binding inhibitor. A similar situation would apply if one were using a mixture of inhibitors such as antibiotics, several of which inhibit initially, but only one of which is a slow-binding inhibitor. This theory is illustrated by determining the half-times for the slow-binding inhibition of yeast hexokinase by various levels of TmATP in the presence and absence of HoATP, which shows little slow-binding behavior.

We have determined 15N isotope effects and solvent deuterium isotope effects for adenosine deaminase using both adenosine and the slow alternate substrate 7,8-dihydro-8-oxoadenosine. With adenosine, 15N isotope effects were 1.0040 in H2O and 1.0023 in D2O, and the solvent deuterium isotope effect was 0.77. With 7,8-dihydro-8-oxoadenosine, 15N isotope effects were 1.015 in H2O and 1.0131 in D2O, and the solvent deuterium isotope effect was 0.45. The inverse solvent deuterium isotope effect shows that the fractionation factor of a proton, which is originally less than 0.6, increases to near unity during formation of the tetrahedral intermediate from which ammonia is released. Proton inventories for 1/V and 1/(V/K) vs percent D2O are linear, indicating that a single proton has its fractionation factor altered during the reaction. We conclude that a sulfhydryl group on the enzyme donates its proton to oxygen or nitrogen during this step. pH profiles with 7,8-dihydro-8-oxoadenosine suggest that the pK of this sulfhydryl group is 8.45. The inhibition of adenosine deaminase by cadmium also shows a pK of approximately 9 from the pKi profile. Quantitative analysis of the isotope effects suggests an intrinsic 15N isotope effect for the release of ammonia from the tetrahedral intermediate of approximately 1.03 for both substrates; however, the partition ratio of this intermediate for release of ammonia as opposed to back-reaction is 14 times greater for adenosine (1.4) than for 7,8-dihydro-8-oxoadenosine (0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Phenylalanine ammonia-lyase has been shown to catalyze the elimination of ammonia from the slow alternate substrate 3-(1,4-cyclohexadienyl)alanine by an E1 cb mechanism with a carbanion intermediate. This conclusion resulted from comparison of 15N isotope effects with deuterated (0.9921) and unlabeled substrates (1.0047), and a deuterium isotope effect of 2.0 from dideuteration at C-3, with the equations for concerted, carbanion, and carbonium ion mechanisms. The 15N equilibrium isotope effect on the addition of the substrate to the dehydroalanine prosthetic group on the enzyme is 0.979, while the kinetic 15N isotope effect on the reverse of this step is 1.03-1.04 and the intrinsic deuterium isotope effect on proton removal is in the range 4-6. Isotope effects with phenylalanine itself are small (15N ones of 1.0021 and 1.0010 when unlabeled or 3-dideuterated and a deuterium isotope effect of 1.15) but are consistent with the same mechanism with drastically increased commitments, including a sizable external one (i.e., phenylalanine is sticky). pH profiles show that the amino group of the substrate must be unprotonated to react but that a group on the enzyme with a pK of 9 must be protonated, possibly to catalyze addition of the substrate to dehydroalanine. Incorrectly protonated enzyme-substrate complexes do not form. Equilibrium 15N isotope effects are 1.016 for the deprotonation of phenylalanine or its cyclohexadienyl analogue, 1.0192 for deprotonation of NH4+, 1.0163 for the conversion of the monoanion of phenylalanine to NH3, and 1.0138 for the conversion of the monoanion of aspartate to NH4+.(ABSTRACT TRUNCATED AT 250 WORDS)

The true substrate for the pyruvate kinase catalyzed phosphorylation of hydroxylamine at high pH which is activated by bicarbonate is shown to be N-hydroxycarbamate, since a lag is seen when the reaction is started by the addition of bicarbonate or hydroxylamine but a burst appears when it is started with a mixture of the two. The lag can be diminished by addition of carbonic anhydrase but not eliminated, showing that CO2 is an intermediate in the formation of the carbamate and that both the formation of CO2 and the subsequent reaction of CO2 with hydroxylamine limit the rate of carbamate formation. The equilibrium constant for the reaction bicarbonate + hydroxylamine reversed N-hydroxycarbamate is 1.33 M-1. The product of the phosphorylation decomposes by loss of CO2 to O-phosphorylhydroxylamine, which is stable at 25 degrees C between pH 3 and 11 and has pK2 = 5.63 for the phosphate and pK3 = 10.26 for the amino group.