Real-World Effectiveness of Intravenous and Oral Antibiotic Stepdown Strategies for Gram-Negative Complicated Urinary Tract Infection With Bacteremia

Background

Robust data are lacking regarding the optimal route, duration, and antibiotic choice for gram-negative bloodstream infection from a complicated urinary tract infection source (GN-BSI/cUTI).

Methods

In this multicenter observational cohort study, we simulated a 4-arm registry trial using a causal inference method to compare effectiveness of the following regimens for GN-BSI/cUTI: complete course of an intravenous β-lactam (IVBL) or oral stepdown therapy within 7 days using fluoroquinolones (FQs), trimethoprim-sulfamethoxazole (TMP-SMX), or high-bioavailability β-lactams (HBBLs). Adults treated between January 2016 and December 2022 for Escherichia coli or Klebsiella species GN-BSI/cUTI were included. Propensity weighting was used to balance characteristics between groups. The 60-day recurrence was compared using a multinomial Cox proportional hazards model with probability of treatment weighting.

Results

Of 2571 patients screened, 759 (30%) were included. Characteristics were similar between groups. Compared with IVBLs, we did not observe a difference in effectiveness for FQs (adjusted hazard ratio, 1.09 [95% confidence interval, .49-2.43]) or TMP-SMX (1.44 [.54-3.87]), and the effectiveness of TMP-SMX/FQ appeared to be optimal at durations of >10 days. HBBLs were associated with nearly 4-fold higher risk of recurrence (adjusted hazard ratio, 3.83 [95% confidence interval, 1.76-8.33]), which was not mitigated by longer treatment durations. Most HBBLs (67%) were not optimally dosed for bacteremia. Results were robust to multiple sensitivity analyses.

Conclusions

These real-world data suggest that oral stepdown therapy with FQs or TMP-SMX have similar effectiveness as IVBLs. HBBLs were associated with higher recurrence rates, but dosing was suboptimal. Further data are needed to define optimal dosing and duration to mitigate treatment failures.

ICU Utilization After Implementation of Minor Severe Pneumonia Criteria in Real-Time Electronic Clinical Decision Support

OBJECTIVES

To determine if the implementation of automated clinical decision support (CDS) with embedded minor severe community-acquired pneumonia (sCAP) criteria was associated with improved ICU utilization among emergency department (ED) patients with pneumonia who did not require vasopressors or positive pressure ventilation at admission.

DESIGN

Planned secondary analysis of a stepped-wedge, cluster-controlled CDS implementation trial.

SETTING

Sixteen hospitals in six geographic clusters from Intermountain Health; a large, integrated, nonprofit health system in Utah and Idaho.

PATIENTS

Adults admitted to the hospital from the ED with pneumonia identified by: 1) discharge International Classification of Diseases , 10th Revision codes for pneumonia or sepsis/respiratory failure and 2) ED chest imaging consistent with pneumonia, who did not require vasopressors or positive pressure ventilation at admission.

INTERVENTIONS

After implementation, patients were exposed to automated, open-loop, comprehensive CDS that aided disposition decision (ward vs. ICU), based on objective severity scores (sCAP).

MEASUREMENTS AND MAIN RESULTS

The analysis included 2747 patients, 1814 before and 933 after implementation. The median age was 71, median Elixhauser index was 17, 48% were female, and 95% were Caucasian. A mixed-effects regression model with cluster as the random effect estimated that implementation of CDS utilizing sCAP increased 30-day ICU-free days by 1.04 days (95% CI, 0.48-1.59; p < 0.001). Among secondary outcomes, the odds of being admitted to the ward, transferring to the ICU within 72 hours, and receiving a critical therapy decreased by 57% (odds ratio [OR], 0.43; 95% CI, 0.26-0.68; p < 0.001) post-implementation; mortality within 72 hours of admission was unchanged (OR, 1.08; 95% CI, 0.56-2.01; p = 0.82) while 30-day all-cause mortality was lower post-implementation (OR, 0.71; 95% CI, 0.52-0.96; p = 0.03).

CONCLUSIONS

Implementation of electronic CDS using minor sCAP criteria to guide disposition of patients with pneumonia from the ED was associated with safe reduction in ICU utilization.

Diagnosis and Treatment of Pneumonia in Urgent Care Clinics: Opportunities for Improving Care

Background

Community-acquired pneumonia is a well-studied condition; yet, in the urgent care setting, patient characteristics and adherence to guideline-recommended care are poorly described. Within Intermountain Health, a nonprofit integrated US health care system based in Utah, more patients present to urgent care clinics (UCCs) than emergency departments (EDs) for pneumonia care.

Methods

We performed a retrospective cohort study 1 January 2019 through 31 December 2020 in 28 UCCs within Utah. We extracted electronic health record data for patients aged ≥12 years with ICD-10 pneumonia diagnoses entered by the bedside clinician, excluding patients with preceding pneumonia within 30 days or missing vital signs. We compared UCC patients with radiographic pneumonia (n = 4689), without radiographic pneumonia (n = 1053), without chest imaging (n = 1472), and matched controls with acute cough/bronchitis (n = 15 972). Additional outcomes were 30-day mortality and the proportion of patients with ED visits or hospital admission within 7 days after the index encounter.

Results

UCC patients diagnosed with pneumonia and possible/likely radiographic pneumonia by radiologist report had a mean age of 40 years and 52% were female. Almost all patients with pneumonia (93%) were treated with antibiotics, including those without radiographic confirmation. Hospital admissions and ED visits within 7 days were more common in patients with radiographic pneumonia vs patients with "unlikely" radiographs (6% vs 2% and 10% vs 6%, respectively). Observed 30-day all-cause mortality was low (0.26%). Patients diagnosed without chest imaging presented similarly to matched patients with cough/acute bronchitis. Most patients admitted to the hospital the same day after the UCC visit (84%) had an interim ED encounter. Pneumonia severity scores (pneumonia severity index, electronic CURB-65, and shock index) overestimated patient need for hospitalization.

Conclusions

Most UCC patients with pneumonia were successfully treated as outpatients. Opportunities to improve care include clinical decision support for diagnosing pneumonia with radiographic confirmation and development of pneumonia severity scores tailored to the UCC.

Oral β-Lactams, Fluoroquinolones, or Trimethoprim-Sulfamethoxazole for Definitive Treatment of Uncomplicated Escherichia coli or Klebsiella Species Bacteremia From a Urinary Tract Source

Background

Fluoroquinolones (FQs) are effective for oral step-down therapy for gram-negative bloodstream infections but are associated with unfavorable toxic effects. Robust data are lacking for trimethoprim-sulfamethoxazole (TMP-SMX) and high-bioavailability β-lactams (HBBLs).

Methods

In this multicenter observational cohort study, we simulated a 3-arm registry trial using causal inference methods to compare the effectiveness of FQs, TMP-SMX, or HBBLs for gram-negative bloodstream infections oral step-down therapy. The study included adults treated between January 2016 and December 2022 for uncomplicated Escherichia coli or Klebsiella species bacteremia of urinary tract origin who were who were transitioned to an oral regimen after ≤4 days of effective intravenous antibiotics. Propensity weighting was used to balance characteristics between groups. 60-day recurrence was compared using a multinomial Cox proportional hazards model with probability of treatment weighting.

Results

Of 2571 patients screened, 648 (25%) were included. Their median age (interquartile range) was 67 (45-78) years, and only 103 (16%) were male. Characteristics were well balanced between groups. Compared with FQs, TMP-SMX had similar effectiveness (adjusted hazard ratio, 0.91 [95% confidence interval, .30-2.78]), and HBBLs had a higher risk of recurrence (2.19 [.95-5.01]), although this difference was not statistically significant. Most HBBLs (70%) were not optimally dosed for bacteremia. A total antibiotic duration ≤8 days was associated with a higher recurrence rate in select patients with risk factors for failure.

Conclusions

FQs and TMP-SMX had similar effectiveness in this real-world data set. HBBLs were associated with higher recurrence rates but suboptimal dosing may have contributed. Further studies are needed to define optimal BL dosing and duration to mitigate treatment failures.

Relationship Between Resuscitation Team Members' Self-Efficacy and Team Competence During In-Hospital Cardiac Arrest

OBJECTIVES

Inadequate self-efficacy of resuscitation team members may impair team performance, but high self-efficacy does not guarantee competence. We evaluated the relationship between individual self-efficacy and resuscitation team competence.

DESIGN

Secondary analysis of a randomized controlled trial.

SETTING

High-fidelity in situ in-hospital cardiac arrest simulations at seven hospitals in Utah.

SUBJECTS

Multidisciplinary cardiac arrest resuscitation team members.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Resuscitation team members completed surveys evaluating resuscitation self-efficacy (confidence in resuscitation role, difficulty thinking clearly, and concerns about committing errors) after each simulation. The primary outcome was event-level chest compression hands-on fraction greater than 75%. Secondary outcomes included other measures of resuscitation quality, advanced cardiac life support protocol adherence, and nontechnical team performance. Analyses employed the Datta-Satten rank-sum method to account for response clustering within simulation events. Of 923 participants in 76 analyzable simulations, 612 (66%) submitted complete surveys and 33 (43%) resuscitation teams achieved hands-on fraction greater than 75%. Event-level chest compression hands-on fraction greater than 75% versus less than or equal to 75% was not associated with the percentage of resuscitation team members reporting confidence in their team role (n = 213 [74%] vs. n = 251 [77%], respectively, p = 0.18), lack of difficulty thinking clearly (n = 186 [65%] vs. n = 214 [66%], p = 0.92), or lack of worry about making errors (n = 155 [54%] vs. n = 180 [55%], p = 0.41). Team members' confidence was also not associated with secondary outcomes, except that teams with confident members had better values for composite (3.55 [interquartile range, IQR 3.00-3.82] vs. 3.18 [IQR 2.57-3.64], p = 0.024) and global (8 [7-9] vs. 8 [6-8], p = 0.029) scales measuring nontechnical team performance.

CONCLUSIONS

Team members' self-efficacy was not associated with most team-level competence metrics during simulated cardiac arrest resuscitation. These data suggest that self-efficacy should have a limited role for evaluation of resuscitation training programs and for initial certification and monitoring of individual resuscitation team members' competence.

A Pragmatic, Stepped-Wedge, Cluster-controlled Clinical Trial of Real-Time Pneumonia Clinical Decision Support

Rationale: Care of emergency department (ED) patients with pneumonia can be challenging. Clinical decision support may decrease unnecessary variation and improve care. Objectives: To report patient outcomes and processes of care after deployment of electronic pneumonia clinical decision support (ePNa): a comprehensive, open loop, real-time clinical decision support embedded within the electronic health record. Methods: We conducted a pragmatic, stepped-wedge, cluster-controlled trial with deployment at 2-month intervals in 16 community hospitals. ePNa extracts real-time and historical data to guide diagnosis, risk stratification, microbiological studies, site of care, and antibiotic therapy. We included all adult ED patients with pneumonia over the course of 3 years identified by International Classification of Diseases, 10th Revision discharge coding confirmed by chest imaging. Measurements and Main Results: The median age of the 6,848 patients was 67 years (interquartile range, 50-79), and 48% were female; 64.8% were hospital admitted. Unadjusted mortality was 8.6% before and 4.8% after deployment. A mixed effects logistic regression model adjusting for severity of illness with hospital cluster as the random effect showed an adjusted odds ratio of 0.62 (0.49-0.79; P < 0.001) for 30-day all-cause mortality after deployment. Lower mortality was consistent across hospital clusters. ePNa-concordant antibiotic prescribing increased from 83.5% to 90.2% (P < 0.001). The mean time from ED admission to first antibiotic was 159.4 (156.9-161.9) minutes at baseline and 150.9 (144.1-157.8) minutes after deployment (P < 0.001). Outpatient disposition from the ED increased from 29.2% to 46.9%, whereas 7-day secondary hospital admission was unchanged (5.2% vs. 6.1%). ePNa was used by ED clinicians in 67% of eligible patients. Conclusions: ePNa deployment was associated with improved processes of care and lower mortality. Clinical trial registered with www.clinicaltrials.gov (NCT03358342).

Prevalence, Characteristics, and Outcomes of Emergency Department Discharge Among Patients With Sepsis

IMPORTANCE

Sepsis guidelines and research have focused on patients with sepsis who are admitted to the hospital, but the scope and implications of sepsis that is managed in an outpatient setting are largely unknown.

OBJECTIVE

To identify the prevalence, risk factors, practice variation, and outcomes for discharge to outpatient management of sepsis among patients presenting to the emergency department (ED).

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted at the EDs of 4 Utah hospitals, and data extraction and analysis were performed from 2017 to 2021. Participants were adult ED patients who presented to a participating ED from July 1, 2013, to December 31, 2016, and met sepsis criteria before departing the ED alive and not receiving hospice care.

EXPOSURES

Patient demographic and clinical characteristics, health system parameters, and ED attending physician.

MAIN OUTCOMES AND MEASURES

Information on ED disposition was obtained from electronic medical records, and 30-day mortality data were acquired from Utah state death records and the US Social Security Death Index. Factors associated with ED discharge rather than hospital admission were identified using penalized logistic regression. Variation in ED discharge rates between physicians was estimated after adjustment for potential confounders using generalized linear mixed models. Inverse probability of treatment weighting was used in the primary analysis to assess the noninferiority of outpatient management for 30-day mortality (noninferiority margin of 1.5%) while adjusting for multiple potential confounders.

RESULTS

Among 12 333 ED patients with sepsis (median [IQR] age, 62 [47-76] years; 7017 women [56.9%]) who were analyzed in the study, 1985 (16.1%) were discharged from the ED. After penalized regression, factors associated with ED discharge included age (adjusted odds ratio [aOR], 0.90 per 10-y increase; 95% CI, 0.87-0.93), arrival to ED by ambulance (aOR, 0.61; 95% CI, 0.52-0.71), organ failure severity (aOR, 0.58 per 1-point increase in the Sequential Organ Failure Assessment score; 95% CI, 0.54-0.60), and urinary tract (aOR, 4.56 [95% CI, 3.91-5.31] vs pneumonia), intra-abdominal (aOR, 0.51 [95% CI, 0.39-0.65] vs pneumonia), skin (aOR, 1.40 [95% CI, 1.14-1.72] vs pneumonia) or other source of infection (aOR, 1.67 [95% CI, 1.40-1.97] vs pneumonia). Among 89 ED attending physicians, adjusted ED discharge probability varied significantly (likelihood ratio test, P < .001), ranging from 8% to 40% for an average patient. The unadjusted 30-day mortality was lower in discharged patients than admitted patients (0.9% vs 8.3%; P < .001), and their adjusted 30-day mortality was noninferior (propensity-adjusted odds ratio, 0.21 [95% CI, 0.09-0.48]; adjusted risk difference, 5.8% [95% CI, 5.1%-6.5%]; P < .001). Alternative confounder adjustment strategies yielded odds ratios that ranged from 0.21 to 0.42.

CONCLUSIONS AND RELEVANCE

In this cohort study, discharge to outpatient treatment of patients who met sepsis criteria in the ED was more common than previously recognized and varied substantially between ED physicians, but it was not associated with higher mortality compared with hospital admission. Systematic, evidence-based strategies to optimize the triage of ED patients with sepsis are needed.

Electronic pulmonary embolism clinical decision support and effect on yield of computerized tomographic pulmonary angiography: ePE-A pragmatic prospective cohort study

OBJECTIVE

Multiple professional societies recommend pre-test probability (PTP) assessment prior to imaging in the evaluation of patients with suspected pulmonary embolism (PE), however, PTP testing remains uncommon, with imaging occurring frequently and rates of confirmed PE remaining low. The goal of this study was to assess the impact of a clinical decision support tool embedded into the electronic health record to improve the diagnostic yield of computerized tomography pulmonary angiography (CTPA) in suspected patients with PE in the emergency department (ED).

METHODS

Between July 24, 2014 and December 31, 2016, 4 hospitals from a healthcare system embedded an optional electronic clinical decision support system to assist in the diagnosis of pulmonary embolism (ePE). This system employs the Pulmonary Embolism Rule-out Criteria (PERC) and revised Geneva Score (RGS) in series prior to CT imaging. We compared the diagnostic yield of CTPA) among patients for whom the physician opted to use ePE versus the diagnostic yield of CTPA when ePE was not used.

RESULTS

During the 2.5-year study period, 37,288 adult patients were eligible and included for study evaluation. Of eligible patients, 1949 of 37,288 (5.2%) were enrolled by activation of the tool. A total of 16,526 CTPAs were performed system-wide. When ePE was not engaged, CTPA was positive for PE in 1556 of 15,546 scans for a positive yield of 10.0%. When ePE was used, CTPA identified PE in 211 of 980 scans (21.5% yield) (P < 0.001).

CONCLUSIONS

ePE significantly increased the diagnostic yield of CTPA without missing 30-day clinically overt PE.

Real-world Effectiveness and Tolerability of Monoclonal Antibody Therapy for Ambulatory Patients With Early COVID-19

BACKGROUND

Neutralizing monoclonal antibodies (MAbs) are a promising therapy for early coronavirus disease 2019 (COVID-19), but their effectiveness has not been confirmed in a real-world setting.

METHODS

In this quasi-experimental pre-/postimplementation study, we estimated the effectiveness of MAb treatment within 7 days of symptom onset in high-risk ambulatory adults with COVID-19. The primary outcome was a composite of emergency department visits or hospitalizations within 14 days of positive test. Secondary outcomes included adverse events and 14-day mortality. The average treatment effect in the treated for MAb therapy was estimated using inverse probability of treatment weighting and the impact of MAb implementation using propensity-weighted interrupted time series analysis.

RESULTS

Pre-implementation (July-November 2020), 7404 qualifying patients were identified. Postimplementation (December 2020-January 2021), 594 patients received MAb treatment and 5536 did not. The primary outcome occurred in 75 (12.6%) MAb recipients, 1018 (18.4%) contemporaneous controls, and 1525 (20.6%) historical controls. MAb treatment was associated with decreased likelihood of emergency care or hospitalization (odds ratio, 0.69; 95% CI, 0.60-0.79). After implementation, the weighted probability that a given patient would require an emergency department visit or hospitalization decreased significantly (0.7% per day; 95% CI, 0.03%-0.10%). Mortality was 0.2% (n = 1) in the MAb group compared with 1.0% (n = 71) and 1.0% (n = 57) in pre- and postimplementation controls, respectively. Adverse events occurred in 7 (1.2%); 2 (0.3%) were considered serious.

CONCLUSIONS

MAb treatment of high-risk ambulatory patients with early COVID-19 was well tolerated and likely effective at preventing the need for subsequent emergency department or hospital care.

Antimicrobial Stewardship in a Hematological Malignancy Unit: Carbapenem Reduction and Decreased Vancomycin-Resistant Enterococcus Infection

BACKGROUND

Antibiotic stewardship is challenging in hematological malignancy patients.

METHODS

We performed a quasiexperimental implementation study of 2 antimicrobial stewardship interventions in a hematological malignancy unit: monthly antibiotic cycling for febrile neutropenia that included cefepime (± metronidazole) and piperacillin-tazobactam and a clinical prediction rule to guide anti-vancomycin-resistant Enterococcus faecium (VRE) therapy. We used interrupted time-series analysis to compare antibiotic use and logistic regression in order to adjust observed unit-level changes in resistant infections by background community rates.

RESULTS

A total of 2434 admissions spanning 3 years pre- and 2 years postimplementation were included. Unadjusted carbapenem and daptomycin use decreased significantly. In interrupted time-series analysis, carbapenem use decreased by -230 days of therapy (DOT)/1000 patient-days (95% confidence interval [CI], -290 to -180; P < .001). Both VRE colonization (odds ratio [OR], 0.64; 95% CI, 0.51 to 0.81; P < .001) and infection (OR, 0.41; 95% CI, 0.2 to 0.9; P = .02) decreased after implementation. This shift may have had a greater effect on daptomycin prescribing (-160 DOT/1000 patient-days; 95% CI, -200 to -120; P < .001) than did the VRE clinical prediction score (-30 DOT/1000 patient-days; 95% CI, -50 to 0; P = .08). Also, 46.2% of Pseudomonas aeruginosa isolates were carbapenem-resistant preimplementation compared with 25.0% postimplementation (P = .32). Unit-level changes in methicillin-resistant Staphylococcus aureus and extended-spectrum beta lactamase (ESBL) incidence were explained by background community-level trends, while changes in AmpC ESBL and VRE appeared to be independent. The program was not associated with increased mortality.

CONCLUSIONS

An antibiotic cycling-based strategy for febrile neutropenia effectively reduced carbapenem use, which may have resulted in decreased VRE colonization and infection and perhaps, in turn, decreased daptomycin prescribing.

Hydroxychloroquine vs. Azithromycin for Hospitalized Patients with COVID-19 (HAHPS): Results of a Randomized, Active Comparator Trial

RATIONALE

The COVID-19 pandemic struck an immunologically naïve, globally interconnected population. In the face of a new infectious agent causing acute respiratory failure for which there were no known effective therapies, rapid, often pragmatic trials were necessary to evaluate potential treatments, frequently starting with medications that are already marketed for other indications. Early in the pandemic, hydroxychloroquine and azithromycin were two such candidates.

OBJECTIVE

Assess the relative efficacy of hydroxychloroquine and azithromycin among hospitalized patients with COVID-19.

METHODS

We performed a randomized clinical trial of hydroxychloroquine vs. azithromycin among hospitalized patients with COVID-19. Treatment was 5 days of study medication. The primary endpoint was the COVID Ordinal Outcomes scale at day 14. Secondary endpoints included hospital-, ICU-, and ventilator-free days at day 28. The trial was stopped early after enrollment of 85 patients when a separate clinical trial concluded that a clinically important effect of hydroxychloroquine over placebo was definitively excluded. Comparisons were made a priori using a proportional odds model from a Bayesian perspective.

RESULTS

We enrolled 85 patients at 13 hospitals over 11 weeks. Adherence to study medication was high. The estimated odds ratio for less favorable status on the ordinal scale for hydroxychloroquine vs. azithromycin from the primary analysis was 1.07, with a 95% credible interval from 0.63 to 1.83 with a posterior probability of 60% that hydroxychloroquine was worse than azithryomycin. Secondary outcomes displayed a similar, slight preference for azithromycin over hydroxychloroquine. QTc prolongation was rare and did not differ between groups. The twenty safety outcomes were similar between arms with the possible exception of post-randomization onset acute kidney injury, which was more common with hydroxychloroquine (15% vs. 0%). Patients in the hydroxychloroquine arm received remdesivir more often than in the azithromycin arm (19% vs. 2%). There was no apparent association between remdesivir use and acute kidney injury.

CONCLUSIONS

While early termination limits the precision of our results, we found no suggestion of substantial efficacy for hydroxychloroquine over azithromycin. Acute kidney injury may be more common with hydroxychloroquine than azithromycin, although this may be due to the play of chance. Differential use of remdesivir may have biased our results in favor of hydroxychloroquine. Our results are consistent with conclusions from other trials that hydroxychloroquine cannot be recommended for inpatients with COVID-19; azithromycin may merit additional investigation.

CLINICAL TRIAL REGISTRATION

This trial was prospectively registered (NCT04329832) before enrollment of the first patient.

Diagnostic yield of pulmonary embolism testing in patients presenting to the emergency department with syncope

BACKGROUND

Syncope occurs in 1 in 4 people during their lifetime and accounts for 1% to 1.5% of emergency department (ED) visits. Most causes of syncope are benign, but syncope may be caused by life-threatening conditions including pulmonary embolism (PE) in up to 2% of cases. A recent publication reported the prevalence of PE in patients with syncope to be over 17%.

AIMS

We sought to determine the frequency and diagnostic yield of testing for PE in patients presenting to the ED with syncope in our large, integrated health care system.

METHODS

We performed a retrospective, longitudinal cohort study of patients who presented with syncope to EDs within a 21-hospital integrated health care system from 2010 to 2015 to find the frequency and diagnostic yield of testing for PE in patients with syncope at index ED visit and within 180 days afterward.

RESULTS

We screened 2 749 371 ED encounters to find 32 440 (1.2%) with syncope. Median age was 52 (interquartile range, 31-71), 57.5% were female, and 90% were Caucasian. PE was diagnosed on the index ED visit in 259 (0.8%; 95% confidence interval [CI], 0.7%-0.9%) cases. Assessment for suspected PE with D-dimer occurred in 5089 (15.7%) patients, and 2338 (7.2%) underwent computed tomography pulmonary angiography (CTPA). The yield of CTPA was 7.9%. PE was detected in 2.2% in whom a D-dimer was performed. From index visit to 180 days, 467 (1.4%; 95% CI, 1.3%-1.6%) patients were diagnosed with a PE, and 1051 (3.2%, 95% CI, 3.0%-3.4%) patients died.

CONCLUSION

Diagnostic testing for PE is frequent in patients with syncope presenting to the EDs of a large, integrated health care system. The yield of diagnostic testing is low.

Patient utilization of prescription opioids after discharge from the emergency department

BACKGROUND

Emergency department (ED) visits associated with prescription opioids have increased in the last ten years. This study describes the opioid utilization of patients discharged from the ED with an opioid prescription for pain, 14 to 21 days post discharge.

METHODS

This is a prospective, single-centered, survey-based observational descriptive study conducted from December 2017 to February 2018 in the ED at a tertiary level 1 trauma center. The primary outcomes were the percentage of patients with unused opioids and the quantity of opioids remaining 14 to 21 days post ED discharge. A sample of ED patients who received an oral opioid prescription were approached for informed consent and received a telephone survey 14 to 21 days post discharge.

RESULTS

Of 178 patients approached for consent, 122 were enrolled. Among them, 98 were successfully surveyed (80.3%). The median number of pills prescribed was 8 (IQR:8-12). Nearly half (49%) of patients had unused opioids 14 to 21 days post ED discharge, not including 9.2% of patients who never filled their prescriptions. Of the total 980 pills prescribed, 327 pills remained unused (33.4%). Only 55.1% of patients reported receiving counseling on side effect of opioids and 21.4% of patients reported they received counseling on storage and disposal.

CONCLUSION

The majority of patients in this study had unused or unfilled opioids 14 to 21 days post ED discharge, and approximately one third of the opioids prescribed remained unused. Most patients did not recall receiving opioid related education including proper disposal of medication.

Prehospital Care and Emergency Department Door-to-Antibiotic Time in Sepsis

RATIONALE

Early antibiotics improve outcomes for patients with sepsis. Factors influencing antibiotic timing in emergency department (ED) sepsis remain unclear.

OBJECTIVES

Determine the relationship between prehospital level of care of patients with sepsis and ED door-to-antibiotic time.

METHODS

This retrospective cohort study comprised patients admitted from the community to an academic ED June 2009 to February 2015 with fluid-refractory sepsis or septic shock. Transfer patients and those whose antibiotics began before ED arrival or after ED discharge were excluded. We used multivariable regression to evaluate the association between the time from ED arrival to antibiotic initiation and prehospital level of care, defined as the highest level of emergency medical services received: none, basic life support (BLS) ambulance, or advanced life support (ALS) ambulance. We measured variation in this association when hypotension was or was not present by ED arrival.

RESULTS

Among 361 community-dwelling patients with sepsis, the level of prehospital care correlated with illness severity. ALS-treated patients received antibiotics faster than patients who did not receive prehospital care (median, 103 [interquartile range, 75 to 135] vs. 144 [98 to 251] minutes, respectively) or BLS-only patients (168 [100-250] minutes; P < 0.001 for each pairwise comparison with ALS). This pattern persisted after multivariable adjustment, where ALS care (-43 min; 95% confidence interval [CI], -84 to -2; P = 0.033) but not BLS-only care (-4 min; 95% CI, -41 to +34; P = 0.97) was associated with less antibiotic delay compared with no prehospital care. ALS-treated patients more frequently received antibiotics within 3 hours of ED arrival (91%) compared with walk-in patients (62%; adjusted odds ratio, 3.11; 95% CI, 1.20 to 8.03; P = 0.015) or BLS-treated patients (56%; adjusted odds ratio, 4.51; 95% CI, 1.89 to 11.35; P < 0.001). ALS-treated patients started antibiotics faster than walk-in patients in the absence of hypotension by ED arrival (-41 min; 95% CI, -110 to -13; P = 0.009) but not when hypotension was present (+25 min; 95% CI, -43 to +92; P = 0.66).

CONCLUSIONS

Prehospital ALS but not BLS-only care was associated with faster antibiotic initiation for patients with sepsis without hypotension. Process redesign for non-ALS patients may improve antibiotic timeliness for ED sepsis.

Newborn Thyroid Screening: Influence of Pre-Analytic Variables on Dried Blood Spot Thyrotropin Measurement

BACKGROUND

Measuring thyrotropin (TSH) eluted from a dried blood spot (DBS) is used to screen an estimated 30 million newborns annually for congenital hypothyroidism (CH). Newborn thyroid screening has eliminated cretinism from the industrialized world and decreased the adverse effects of unrecognized CH on neurocognitive development. Hematocrit, a pre-analytic variable that affects the measurement of TSH from a DBS, contributes to the imprecision of DBS TSH measurement and could account for false-negative and false-positive DBS newborn screening test results. To assess whether variations in hematocrit found in newborns have a clinical effect in DBS-based newborn thyroid screening, the effects of hematocrit variability on the measurement of DBS TSH were studied.

METHODS

U.S. Centers for Disease Control and Prevention procedures for manufacturing DBS performance testing standards were used to generate DBSs from blood samples, with hematocrits of 35%, 40%, 45%, 50%, 55%, 60%, and 65% and serum TSH concentrations of 6.3 ± 0.4 and 26.6 ± 8.0 mIU/L. TSH was measured in the eluates of four replicate DBS 3 mm punches at each hematocrit using the Thailand Ministry of Public Health Newborn Screening Operation Center enzyme-linked immunosorbent assay. Data were analyzed using a linear mixed-effects model.

RESULTS

Based on the mixed-effects model, hematocrit significantly affected DBS TSH measurement (p < 0.001). A 1% increase in hematocrit resulted in a 0.06 mIU/L decrease in eluate TSH when TSH was 6.3 + 0.4 mIU/L, and a 0.21 mIU/L decrease in eluate TSH when TSH was 26.6 + 8.0 mIU/L.

CONCLUSIONS

DBS TSH is significantly affected by the blood sample hematocrit. The pre-analytic variability due to hematocrit is independent of TSH assay sensitivity, specificity, precision, repeatability, and reference intervals. The effect of hematocrit on DBS TSH measurement is clinically relevant, could account for geographic and ethnic variation in the incidence of CH, and may result in both false-positive and false-negative CH screening results. Individual newborn and population-specific hematocrit correction factors may improve the precision of DBS TSH measurement.

A Retrospective Analysis of Precision Medicine Outcomes in Patients With Advanced Cancer Reveals Improved Progression-Free Survival Without Increased Health Care Costs

Purpose:

The advent of genomic diagnostic technologies such as next-generation sequencing has recently enabled the use of genomic information to guide targeted treatment in patients with cancer, an approach known as precision medicine. However, clinical outcomes, including survival and the cost of health care associated with precision cancer medicine, have been challenging to measure and remain largely unreported.

Patients and Methods:

We conducted a matched cohort study of 72 patients with metastatic cancer of diverse subtypes in the setting of a large, integrated health care delivery system. We analyzed the outcomes of 36 patients who received genomic testing and targeted therapy (precision cancer medicine) between July 1, 2013, and January 31, 2015, compared with 36 historical control patients who received standard chemotherapy (n = 29) or best supportive care (n = 7).

Results:

The average progression-free survival was 22.9 weeks for the precision medicine group and 12.0 weeks for the control group (P = .002) with a hazard ratio of 0.47 (95% CI, 0.29 to 0.75) when matching on age, sex, histologic diagnosis, and previous lines of treatment. In a subset analysis of patients who received all care within the Intermountain Healthcare system (n = 44), per patient charges per week were $4,665 in the precision treatment group and $5,000 in the control group (P = .126).

Conclusion:

These findings suggest that precision cancer medicine may improve survival for patients with refractory cancer without increasing health care costs. Although the results of this study warrant further validation, this precision medicine approach may be a viable option for patients with advanced cancer.

Prevalence of human papillomavirus among oesophageal squamous cell carcinoma cases: systematic review and meta-analysis

Background:

Oncogenic human papillomavirus (HPV) has been hypothesised as a risk factor for oesophageal squamous cell carcinoma (OSCC), but aetiological research has been limited by the varying methodology used for establishing HPV prevalence. The aims of this systematic review and meta-analysis were to estimate the prevalence of HPV DNA detected in OSCC tumours and the influence of study characteristics.

Methods:

Study-level estimates of overall and type-specific HPV prevalence were meta-analysed to obtain random-effects summary estimates.

Results:

This analysis included 124 studies with a total of 13 832 OSCC cases. The average HPV prevalence (95% confidence interval) among OSCC cases was 0.277 (0.234, 0.320) by polymerase chain reaction; 0.243 (0.159, 0.326) by in situ hybridisation; 0.304 (0.185, 0.423) by immunohistochemistry; 0.322 (0.154, 0.490) by L1 serology; and 0.176 (0.061, 0.292) by Southern/slot/dot blot. The highest HPV prevalence was found in Africa and Asia, notably among Chinese studies from provinces with high OSCC incidence rates.

Conclusions:

Future research should focus on quantifying HPV in OSCC cases using strict quality control measures, as well as determining the association between HPV and OSCC incidence by conducting large, population-based case–control studies. Such studies will provide a richer understanding of the role of HPV in OSCC aetiology.

Common genetic variation near the connexin-43 gene is associated with resting heart rate in African Americans: a genome-wide association study of 13,372 participants

BACKGROUND

Genome-wide association studies have identified several genetic loci associated with variation in resting heart rate in European and Asian populations. No study has evaluated genetic variants associated with heart rate in African Americans.

OBJECTIVE

To identify novel genetic variants associated with resting heart rate in African Americans.

METHODS

Ten cohort studies participating in the Candidate-gene Association Resource and Continental Origins and Genetic Epidemiology Network consortia performed genome-wide genotyping of single nucleotide polymorphisms (SNPs) and imputed 2,954,965 SNPs using HapMap YRI and CEU panels in 13,372 participants of African ancestry. Each study measured the RR interval (ms) from 10-second resting 12-lead electrocardiograms and estimated RR-SNP associations using covariate-adjusted linear regression. Random-effects meta-analysis was used to combine cohort-specific measures of association and identify genome-wide significant loci (P≤2.5×10(-8)).

RESULTS

Fourteen SNPs on chromosome 6q22 exceeded the genome-wide significance threshold. The most significant association was for rs9320841 (+13 ms per minor allele; P = 4.98×10(-15)). This SNP was approximately 350 kb downstream of GJA1, a locus previously identified as harboring SNPs associated with heart rate in Europeans. Adjustment for rs9320841 also attenuated the association between the remaining 13 SNPs in this region and heart rate. In addition, SNPs in MYH6, which have been identified in European genome-wide association study, were associated with similar changes in the resting heart rate as this population of African Americans.

CONCLUSIONS

An intergenic region downstream of GJA1 (the gene encoding connexin 43, the major protein of the human myocardial gap junction) and an intragenic region within MYH6 are associated with variation in resting heart rate in African Americans as well as in populations of European and Asian origin.

Well-differentiated hepatocellular carcinoma in a ring-tailed lemur (Lemur catta)

A 16-year-old male ring-tailed lemur (Lemur catta) was presented with severe cachexia and an abdominal mass. The encapsulated, multilobular mass replaced the right medial lobe of the liver and compressed the adjacent gall bladder. Multiple haemorrhages and necrotic foci were found within the mass. Microscopically, neoplastic cells formed cords of moderately pleomorphic, polygonal cells with mild to moderate anaplasia. Immunohistochemical markers used for diagnosis of hepatocellular carcinomas in man were used to characterize the neoplastic cells, which expressed hepatocyte-specific antigen, but not glypican-3 or polyclonal carcinoembryonic antigen. Gross, microscopical and immunohistochemical features of the tumour were most consistent with a well-differentiated hepatocellular carcinoma. Although this tumour is common among prosimians, to the authors' knowledge this is the first documented case in a ring-tailed lemur. Hepatocellular carcinomas have been associated with hepatitis virus infections and excessive hepatic iron in man; however, no association was established between this tumour and viral infection or hepatic iron storage disease in the present case.

Granulomatous typhlocolitis, lymphangitis, and lymphadenitis in a horse infected with Listeria monocytogenes, Salmonella Typhimurium, and cyathostomes

A 15-year-old American Quarter horse mare was euthanized because of poor response to therapy for severe diarrhea. Significant gross findings were limited to the large intestines. The walls of the cecum and colon were thickened with widely scattered nodules in the mucosa and submucosa that extended into the enlarged colic lymph nodes. Microscopically, there was severe granulomatous typhlocolitis, lymphangitis, and lymphadenitis, with many intralesional Gram-positive, non-acid-fast coccobacilli and few cyathostomes. Intralesional bacteria were immunohistochemically and polymerase chain reaction (PCR) assay positive for Listeria monocytogenes. Concurrent infection with Salmonella enterica serovar Typhimurium was detected by PCR and culture. Infection with L. monocytogenes in horses is rare, and coinfection with Salmonella and small strongyles probably contributed to the development of granulomatous typhlocolitis.

SALT AND WATER LOSSES IN DIURETIN DIURESIS AND THEIR RELATION TO SERUM NON-PROTEIN NITROGEN AND ELECTROLYTE CONCENTRATIONS

The losses of sodium, potassium, chloride, nitrogen, and water following the administration of diuretin to rabbits over 5 to 9 day periods together with the changes in serum concentrations of sodium, chloride, N. P. N., and total protein occurring simultaneously with these losses are described. The circumstances responsible for the presence of azotemia in the animals were investigated in particular and the dependence of nitrogen retention upon dehydration and the modification of this dependence by variation in urine volume were demonstrated. It was clearly shown that no direct relationship exists between the azotemia and the coincident hypochloremia. It was found that nitrogen retention can be removed by the administration of water without salt, and the extent to which serum electrolyte and protein concentrations can be lowered by this procedure was also observed. The withdrawal from the body of large amounts of potassium as well as of sodium and chloride following the administration of diuretin, and also the inefficacy of sodium chloride solution in preventing the potassium loss was demonstrated.

Comparative inhibition of inducible and constitutive CYPs in rat hepatic microsomes by parathion

1. In microsomal fractions, the phosphorothioate pesticide parathion inhibits cytochrome P450 (CYP) enzymes by reversible and irreversible mechanisms resulting in the long-term suppression of drug oxidation. The present study evaluated the relative susceptibilities of constitutive and inducible CYP2 and CYP3 steroid hydroxylases to inhibition by the pesticide. 2. Enzyme kinetic analysis indicated that constitutive and dexamethasone (DEX)-induced androst-4-ene-3,17-dione (AD) 6beta-hydroxylations were similarly susceptible to inhibition by parathion (Km/Ki ratios 1.5-1.6). However, preincubation of parathion with NADPH-fortified microsomes intensified the extent of inhibition of CYP3A-dependent 6beta-hydroxylation. Comparison of Km/Ki ratios indicated that 6beta-hydroxylation activity in fractions from DEX-pretreated rats was about twice as susceptible as the control activity to inactivation by parathion metabolites (Km/Ki ratio of 8.0 versus 4.0). 3. The time-dependent loss of AD 6beta-hydroxylation by parathion occurred more efficiently in fractions from DEX-induced liver than in control. Thus, half-times of 1.3 and 6.1 min, respectively, were determined for the inactivation of DEX-inducible and constitutive activities. Parathion concentrations required for half-maximal inactivation were 32 and 67 microM in microsomes from DEX-induced and control rats. 4. In phenobarbital (PB)-induced fractions CYP2B1-mediated AD 16beta-hydroxylation was inhibited potently in a reversible fashion by parathion (Ki = 0.37 microM; Km/Ki ratio about 73). Inhibition was not enhanced at parathion concentrations near the Ki by a preincubation step with NADPH. 5. In control microsomes parathion elicited a type I binding interaction with oxidized CYP (Ks=7.7 microM, deltaAmax=2.2 x 10(-2) a.u.nmol CYP-1; deltaAmax/Ks 2.86 x 10(3) a.u. nmol CYP(-1)/mM). Ligand binding was 13- and 1.6-fold more efficient in PB and DEX microsomes, respectively. 6. These findings indicate that pretreatment of rats with enzyme-inducing drugs like DEX and PB alters the profile of CYPs and their susceptibility to inhibition by parathion. Potent reversible inhibition of CYP2B1 occurred in PB-induced fractions and DEX-inducible CYPs 3A were more susceptible to mechanism-based inactivation than the corresponding constitutive CYPs from the same subfamily.

Differential regulation of endobiotic-oxidizing cytochromes P450 in vitamin A-deficient male rat liver

1. The hepatic CYP4A-dependent omega-hydroxylation of arachidonic acid and CYP2C11-dependent 2alpha-/16alpha-hydroxylations of testosterone were decreased to 74 and 60% of respective control in microsomal fractions from vitamin A-deficient rats. Decreases in the rates of arachidonic acid omega-1-hydroxylation and testosterone 6beta-, 7alpha- and 17alpha-hydroxylations were less pronounced. 2. Corresponding decreases in microsomal CYP4A and CYP2C11 immunoreactive protein expression to 64 and 68% of respective control were observed in vitamin A-deficient rat liver. Expression of CYP3A proteins was unchanged from vitamin A-adequate control. 3. Northern analysis revealed a selective decrease in CYP4A2 mRNA expression in vitamin A-deficient rat liver to approximately 5% of control; expression of the related CYP4A1/4A3 mRNAs was not decreased. CYP2C11 mRNA expression was also decreased in vitamin A-deficient male rat liver to 39% of control levels. 4. Intake of the deficient diet containing all-trans-retinoic acid (ATRA) during the final week of the experiment restored CYP4A2 mRNA and CYP4A protein. Administration of exogenous androgen or episodic growth hormone was ineffective. In contrast, CYP2C11 expression was restored by ATRA and androgen, but not by growth hormone. 5. From these studies it emerges that CYP4A2, a fatty acid omega-hydroxylase in rat liver, is highly dependent on vitamin A for optimal expression, whereas CYP2C11 is indirectly down regulated by androgen deficiency resulting from vitamin A-deficiency. Altered CYP expression in vitamin A-deficiency provides insights into the relationship between dietary constituents and the intracellular formation of vasoactive eicosanoids as well as the clearance of androgenic steroids.

Characterization of a novel heterodimeric cathepsin L-like protease and cDNA encoding the catalytic subunit of the protease in embryos of Artemia franciscana

Embryos and larvae of the brine shrimp, Artemia franciscana, contain a novel cathepsin L-like cysteine protease (ACP) composed of 28.5- and 31.5-kDa subunits. Both subunits of the ACP are glycosylated, and seven isoforms of the protease were identified by isoelectric focusing with pI values ranging from 4.6 to 6.2. Several clones containing sequences coding for the 28.5-kDa subunit of the ACP were isolated from an Artemia embryo cDNA library in lambda ZAP II. One clone of 1229 bp, with an open reading frame of 1014 bp, was sequenced and found to contain 50-65% amino acid sequence identity with several members of the cathepsin L subfamily of cysteine proteases. The mature protein predicted from this sequence consisted of 217 amino acids with a mass of 23.5 kDa prior to post-translational modifications. The mature protein showed 68.6% amino acid sequence identity with human cathepsin L and 73.9% identity with cathepsin L-like proteases from Sarcophaga. peregrina and Drosophila melanogaster. The full-length cDNA clone analyzed in this study (pCP-3b) was renamed AFCATL1 (A. franciscana Cathepsin L1) and the sequence has been deposited in the Genbank database, accession number AF147207. Northern blot analyses identified a single transcript of about 1.4 kb in both embryos and young larvae of Artemia. Southern blot analyses of Artemia genomic DNA treated with various restriction endonucleases indicated a single gene for the ACP. The catalytic subunit of the ACP was tightly associated with a 31.5-kDa protein, which may localize the protease to nonlysosomal sites in embryos and larvae.

Pretranslational up-regulation of the hepatic microsomal delta4-3-oxosteroid 5alpha-oxidoreductase in male rat liver by all-trans-retinoic acid

Administration of all-trans-retinoic acid (ATRA; 60 mg/kg daily for 3 days) to male rats increased the rate of 5alpha-dihydrotestosterone (5alpha-DHT) formation from testosterone in microsomal fractions in vitro. The formation of androstane-3alpha,17beta-diol from testosterone was also increased because of the higher concentration of 5alpha-DHT produced in microsomal incubations. Northern analysis confirmed that the increased rate of 5alpha-DHT formation was due to the pretranslational up-regulation in delta4-3-oxosteroid 5alpha-oxidoreductase (EC 1.3.99.5) mRNA expression in ATRA-treated male rat liver. Thus, ATRA elicited in male rat liver a partial feminization of the expression of this enzyme, which normally exhibits a female-selective distribution in the rat. Subsequent experiments evaluated whether the administration of human chorionic gonadotropin or thyroxine to ATRA-treated male rats decreases 5alpha-reductase activity to that observed in untreated male rat liver. Although these treatments did not decrease 5alpha-reductase to untreated male levels, it was found that administration of ATRA to gonadectomized male rats produced complete feminization of the enzyme. Again, up-regulation was confirmed at the mRNA level. The activity of the male-specific cytochrome P450 2C11 (as reflected by microsomal testosterone 16alpha-hydroxylation activity) was correspondingly decreased by treatments that increased steroid 5alpha-reductase activity. Thus, gonadectomy in combination with ATRA administration effected a more pronounced decrease in 16alpha-hydroxylation activity than either treatment alone. These findings suggest that ATRA is a novel positive regulator of the 5alpha-reductase that in combination with the removal of circulating androgen, which normally suppresses 5alpha-reductase levels, feminizes the expression of this enzyme in rat liver.

Comparative induction of CYP3A and CYP2B in rat liver by 3-benzoylpyridine and metyrapone

3-Benzoylpyridine (3BP) is a major metabolite of HGG-12, and oxime that has been synthesized as a potential antidote to the toxic effects of soman and other anticholinesterases. Structural similarities exist between 3BP, the cytochrome P450 (CYP)-inducer metyrapone (MET) and other 3-substituted pyridines that interact with CYPs. The present study evaluated the regulatory effects of 3BP on CYP expression in rat liver. Both 3BP and MET (100 mg/kg) increased total hepatic microsomal holo-CYP content significantly 24 h after administration to male rats. Pronounced increases in activities mediated by CYP2B (androstenedione 16 beta-hydroxylation and 7-pentylresorufin O-depentylation) were produced by 3BP and MET, which correlated with respective 9- and 14-fold increases in CYP2B immunoreactive protein. In addition, both agents slightly increased rates of microsomal CYP3A-dependent steroid 6 beta-hydroxylation, troleandomycin metabolite complex formation and total CYP3A immunoreactive protein. Induction of the dexamethasone-inducible CYP3A23 mRNA to 4.5- and 2.5-fold of control was detected in liver of MET- and 3BP-induced rats; CYP3A2 mRNA levels were unchanged. Analogous in vitro studies revealed that MET was a preferential inhibitor of CYP3A-mediated steroid 6 beta-hydroxylation activity, but 3BP was inactive against constitutive steroid hydroxylase CYPs. These findings indicate that the structurally related 3BP and MET elicit similar induction effects on CYPs 2B and 3A23 in rat liver after in vivo administration, but differential inhibitory effects of the chemicals on CYP activity in vitro. Recent reports have implicated a microsomal binding site in the induction of CYP3A1/3A23 in rat liver. In light of the present findings, substituted pyridines like 3BP may be useful tools in structure-activity studies to evaluate the physicochemical requirements for binding to this protein.

Induction of cytochromes P450 2B and 2E1 in rat liver by isomeric picoline N-oxides

Pyridine derivatives are widely used solvents and precursors for the synthesis of chemicals of industrial importance. Oxidized metabolites have been implicated in the observed toxicity of pyridines and are known to induce drug-metabolizing enzymes in rat liver. In this study the three isomeric picoline (methylpyridine) N-oxides, as major oxidized metabolites of 2-, 3- and 4-picoline, were evaluated as inducers of cytochrome P450 (CYP) enzymes in rat liver. After a single dose of 100 mg/kg 24 h before sacrifice the 3- and 4-isomers were effective inducers of microsomal substrate oxidations associated with the phenobarbital-inducible CYPs 2B; upregulation of CYP2B protein was confirmed by immunoblotting. In contrast, the 2-isomer did not increase CYP2B protein or activity in rat liver but CYP2E1 protein expression was upregulated by the isomers to 160-200% of control. The three chemicals increased aniline 4-hydroxylation activity in rat liver, which is consistent with induction of CYPs 2B or 2E1 and 4-nitrophenol 2-hydroxylation activity was increased in microsomal fractions from 3- and 4-picoline N-oxide-treated rats. The activities of several other CYPs were also determined and CYP1A-dependent 7-ethylresorufin O-deethylation was increased (to approximately 6- and 2-fold of control) by the 3- and 4-isomer, respectively, whereas the activity of CYP3A-mediated androstenedione 6beta-hydroxylation was decreased by the agents--most notably by the 2-isomer. During NADPH-supported oxidation of CCl4, lipid peroxidation was increased in microsomes from 3- and 4-picoline N-oxide-pretreated rats and was modulated in vitro by the CYP2B inhibitor orphenadrine, but not by the CYP2E1 inhibitor 4-methylpyrazole. These findings establish that particular isomers of picoline N-oxide rapidly upregulate CYP2B or, to a lesser extent, CYP2E1 and implicate CYP2B in the enhanced lipid peroxidation observed in microsomes from rats treated with 3- and 4-picoline N-oxides. Such induction process may contribute to the hepatotoxicity of pyridines by enhancing the capacity for microsomal lipid peroxidation.

Role of CYP3A4 in human hepatic diltiazem N-demethylation: inhibition of CYP3A4 activity by oxidized diltiazem metabolites

The antihypertensive agent diltiazem (DTZ) impairs hepatic drug metabolism by inhibition of cytochrome P450 (CYP). The accumulation of DTZ metabolites in serum occurs during prolonged therapy and leads to decreased DTZ elimination. Thus, DTZ metabolites may contribute to CYP inhibition. This study assessed the role of human CYPs in microsomal DTZ oxidation and the capacity of DTZ metabolites to inhibit specific CYP activities. DTZ N-demethylation varied 10-fold in microsomal fractions from 17 livers (0.33-3.31 nmol/mg of protein/min). DTZ oxidation was correlated with testosterone 6beta-hydroxylation (r = 0.82) and, to a lesser extent, tolbutamide hydroxylation (r = 0.59) but not with activities mediated by CYP1A2 or CYP2E1. CYP3A4 in lymphoblastoid cell microsomes catalyzed DTZ N-demethylation but CYP2C8 and CYP2C9 were also active (approximately 20% and 10% of the activity supported by CYP3A4); seven other CYPs produced little or no N-desmethyl DTZ from DTZ. The CYP3A4 inhibitors ketoconazole and troleandomycin decreased microsomal DTZ oxidation, but inhibitors or substrates of CYP2C, CYP2D and CYP2E1 produced no inhibition. Some inhibition was produced by alpha-naphthoflavone, a chemical that inhibits CYP1As and also interacts with CYP3A4. In further experiments, the capacities of DTZ and three metabolites to modulate human CYP 1A2, 2E1, 2C9 and 3A4 activities were evaluated in vitro. DTZ and its N-desmethyl and N,N-didesmethyl metabolites selectively inhibited CYP3A4 activity, whereas O-desmethyl DTZ was not inhibitory. The IC50 value of DTZ against CYP3A4-mediated testosterone 6beta-hydroxylation (substrate concentration, 50 microM) was 120 microM. The N-desmethyl (IC50 = 11 microM) and N,N-didesmethyl (IC50 = 0.6 microM) metabolites were 11 and 200 times, respectively, more potent. From kinetic studies, N-desmethyl DTZ and N,N-didesmethyl DTZ were potent competitive inhibitors of CYP3A4 (Ki = approximately 2 and 0.1 microM, respectively). CYP3A4 inhibition was enhanced when DTZ and N-desmethyl DTZ underwent biotransformation in NADPH-supplemented hepatic microsomes in vitro, supporting the contention that inhibitory metabolites may be generated in situ. These findings suggest that N-demethylated metabolites of DTZ may contribute to CYP3A4 inhibition in vivo, especially under conditions in which N-desmethyl DTZ accumulates, such as during prolonged DTZ therapy.

Biotransformation of parathion in human liver: participation of CYP3A4 and its inactivation during microsomal parathion oxidation

Studies in rat liver have shown that cytochrome P450 (CYP) enzymes mediate the oxidative biotransformation of the phosphorothioate pesticide parathion to paraoxon and 4-nitrophenol. Transfer of the phosphorothioate thionosulfur atom to the CYP apoprotein results in amino acid modification and enzyme inactivation. Our study investigated the role of human hepatic CYP in parathion oxidation and their relative susceptibilities to inhibition and inactivation. Rates of parathion oxidation varied about 10-fold in microsomes from 23 individual livers (1.72-18.33 nmol total metabolites/mg protein/min). Linear regression of rates of parathion oxidation with those of other microsomal CYP reactions implicated CYP3A4 in the reaction. Thus, parathion oxidation was correlated strongly with testosterone 6beta-hydroxylation (r2 = 0.95, n = 11), but not with activities mediated by CYP 1A2, 2C9 or 2E1. CYP 3A4 expressed in lymphoblastoid cell lines was an efficient catalyst of parathion oxidation, although CYP 1A2 and 2B6 also catalyzed the activity. The CYP3A4 inhibitors ketoconazole and triacetyloleandomycin decreased the observed rate of microsomal parathion oxidation, but chemicals known to interact preferentially with other human CYP were essentially noninhibitory. P450 was lost during parathion biotransformation in human hepatic microsomes. Thus, incubation (10 min) of parathion (25 microM) with NADPH-supplemented microsomes led to an apparent 19 +/- 4% decrease in holo-P450 content. Several CYP-specific oxidation reactions were inhibited and inactivated by parathion. Testosterone 6beta-hydroxylation (mediated by CYP3A4), 7-ethylresorufin O-deethylation (CYP1A2) and tolbutamide methyl hydroxylation (CYP2C9/10), but not aniline 4-hydroxylation (CYP2E1), were inhibited effectively by parathion. Preincubation of microsomes with parathion and NADPH intensified the extent of inhibition (i.e., elicited inactivation) of reactions mediated by 3A4 and 1A2 and, to a lesser extent, 2C9. In summary, these findings strongly implicate CYP 3A4 as the principal catalyst of parathion oxidation in human liver, although other CYP may play a lesser role. During parathion oxidation CYP3A4 undergoes significant inactivation. In view of the role of this enzyme in the oxidation of many therapeutic agents, exposure to phosphorothioate pesticides may adversely affect drug elimination in humans.

Enhanced inhibition of microsomal cytochrome P450 3A2 in rat liver during diltiazem biotransformation

Pharmacokinetic drug interactions involving the calcium channel blocker diltiazem (DTZ) have been attributed to inhibition of microsomal cytochrome P450 (P450)-mediated drug oxidation. Accumulation of certain DTZ metabolites during dosage with the drug, as well as dose-related differences in DTZ pharmacokinetics, suggests that DTZ metabolites may also participate in P450 inhibition. The present study evaluated a series of putative DTZ metabolites as inhibitors of major constitutive P450s in rat liver in vitro, in relation to DTZ biotransformation. The principal finding to emerge was that the N-demethylated metabolite of DTZ was a more potent competitive inhibitor than DTZ of CYP3A2-dependent testosterone 6 beta-hydroxylation. This P450 appeared to be the preferred target for inhibition, because the observed K/K(m) ratio for inhibition of CYP3A2-dependent steroid hydroxylation was approximately 4- and 100-fold lower than those for CYP2C11 and CYP2A1-dependent pathways, respectively. It was also established that N-desmethyl-DTZ was a major metabolite formed during microsomal DTZ biotransformation in rat liver in vitro. The other primary metabolites, desacetyl-DTZ and O-desmethyl-DTZ, were ineffective inhibitors of any pathways of steroid oxidation by P450s, but several other potential metabolites, which were not detected in microsomal incubations, also inhibited P450 activity. Consistent with previous reports, there was no evidence of P450 inactivation or complexation by DTZ, but the drug and its N-desmethyl metabolite generated binding interactions with ferric P450 in rat hepatic microsomes. Considered together, the findings of the present study establish that N-desmethyl-DTZ is a preferential inhibitor of CYP3A2 in rat hepatic microsomes, with greater potency than the parent drug. This is consistent with clinical reports in which this metabolite accumulates during multiple-dose therapy with DTZ. The competitive nature of the inhibitory interaction suggests that the eventual elimination of N-desmethyl-DTZ should restore normal hepatic oxidation capacity.

Restoration of cytochrome P450 2C11 in vitamin A-deficient rat liver by exogenous androgen

Down-regulation of microsomal androgen-dependent CYP2C11 is produced in male rat liver by dietary vitamin A deficiency. Decreased circulating androgen concentrations also occur in vitamin A-deficient male rats. Both effects are prevented by addition of all-trans-retinoic acid to the diet. The present study evaluated directly whether androgen deficiency may be responsible for the down-regulation of 2C11 in vitamin A-deficient male rats. The major finding was that subcutaneous administration of the androgen methyltrienolone (MT) during the final week of the study restored CYP2C11 protein and its associated steroid 16alpha-hydroxylation activities to control levels; CYP2C11 mRNA was also restored. Despite the efficient restoration of CYP2C11 at a pretranslational level, no alteration in vitamin A status was apparent and animals remained vitamin A deficient after MT treatment. The possibility was assessed that vitamin A can maintain the microsomal content of CYP2C11 in normal liver. However, in contrast to MT, administration of ATRA to gonadectomized male rats did not restore 2C11 in liver. These findings establish that the major effect of vitamin A deficiency on CYP2C11 in male rat liver is mediated indirectly by androgen deficiency.

Pretranslational down-regulation of cytochromes P450 2C11 and 3A2 in male rat liver by tumor necrosis factor alpha

BACKGROUND & AIMS

The cytokine tumor necrosis factor alpha (TNF-alpha) is a primary inflammatory mediator after liver injury. Several cytokines impair the regulation of cytochrome P450 (CYP) genes in liver, but the specificity of these effects remains unclear. This study investigated the effects of recombinant murine TNF-alpha on the expression of specific constitutive CYPs in male rat liver.

METHODS

Microsomal steroid hydroxylation was used to indicate the activities of specific CYPs after TNF-alpha treatment and immunoblotting to correlate CYP activities with protein contents. CYP messenger RNA levels were measured by solution hybridization.

RESULTS

Testosterone 2 alpha/16 alpha- and 6 beta-hydroxylations, mediated respectively by CYPs 2C11 and 3A2, were decreased after TNF-alpha treatment, whereas 7 alpha-hydroxylation (CYP 2A1) was unchanged. Similarly, progesterone 2 alpha/16 alpha- (CYP 2C11) and 6 beta-hydroxylations (CYP 3A2), but not 21-hydroxylation (CYP 2C6), were decreased after TNF-alpha treatment. 2C11 and 3A2 apoproteins and messenger RNAs, but not 2A1 apoprotein, were decreased after TNF-alpha treatment; changes in messenger RNAs were evident 4 hours after treatment.

CONCLUSIONS

TNF-alpha down-regulates CYPs 2C11 and 3A2 in male rat liver at a pretranslational level, whereas two other constitutive CYPs, 2A1 and 2C6, seem refractory to TNF-alpha. Thus, impaired CYP regulation by TNF-alpha resembles the combined effects of autologous interferons (on 3A2) and interleukins (on 2C11).

Pretranslational down regulation of cytochrome P450 2C11 in vitamin A-deficient male rat liver: prevention by dietary inclusion of retinoic acid

Manipulation of vitamin A intake has been associated with altered rates of cytochrome P450 (P450)-mediated microsomal drug oxidation. Dietary vitamin A deficiency reportedly results in decreased rates of P450-dependent substrate oxidation, but the mechanisms underlying these changes remain unclear. In this study, the effects of dietary vitamin A modulation, as well as dietary inclusion of all-trans-retinoic acid (ATRA), on major constitutive P450s were defined. Total microsomal P450 in deficient male rats was decreased to 72% of control (0.63 +/- 0.07 vs. 0.88 +/- 0.08 nmol/mg of protein; P < .05); this was prevented by inclusion of ATRA (12 micrograms/g) in the deficient diet. Dietary vitamin A deficiency decreased rates of P450 2C11-mediated testosterone 2 alpha- and 16 alpha-hydroxylation in rat liver to 44 and 47% of respective adequate control, whereas rates of 6 beta- and 7 alpha-hydroxylation of the steroid were unaltered; inclusion of ATRA into the deficient diet prevented the loss of 2C11 activities. Immunoblot and RNA analysis revealed decreases in P450 2C11 apoprotein and its corresponding mRNA in liver from deficient rats that was prevented by inclusion of ATRA in the deficient diet. Serum testosterone concentrations were reduced in deficient rats and this also was prevented by dietary ATRA. To discern whether this was a direct effect of vitamin A on P450 2C11 regulation, further experiments evaluated the effect of ATRA administration to male rats maintained on standard rat chow (vitamin A-adequate). Dose- and time-dependent decreases in P450 2C11 activity were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of a reversible component in the in vitro inhibition of rat hepatic cytochrome P450 2B1 by parathion

Cytochrome P450 (P450) enzymes are inactivated in suicidal fashion during microsomal parathion oxidation. In the present study, two distinct components of the inhibition of the phenobarbital (PB)-inducible P450 2B1 by parathion were characterized. Here we report for the first time that low concentrations of parathion potently and reversibly inhibited, but did not inactivate, 2B1. In contrast, the previously described inactivation process occurred only at considerably higher parathion concentrations, at which concentrations enzyme activity was already extensively inhibited. At low concentration, parathion was a competitive inhibitor of 2B1-mediated androstenedione 16 beta-hydroxylation (Ki = 0.44 +/- 0.07 microM) and of 7-pentylresorufin O-depentylation (Ki = 0.40 +/- 0.03 microM) in microsomes from PB-pretreated rats and was similarly effective against androstenedione 16 alpha- and 16 beta-hydroxylation catalyzed by purified 2B1. Although preincubation of higher concentrations of parathion (> 5 microM) with NADPH-supplemented microsomes from PB-pretreated rat liver decreased holo-P450, heme loss was not observed near the Ki values. Instead, half-maximal loss of P450 occurred at 6 microM and at 9 microM parathion in PB-pretreated microsomes and in the reconstituted system, respectively. Parathion metabolism was efficient in PB-microsomes (Km values for 4-nitrophenol and paraoxon formation were 13 microM and 10 microM, respectively) and in the reconstituted system (corresponding Km values were 19 microM and 14 microM). Thus the constants for P450 inactivation and for parathion metabolism were similar and were at least 15-fold greater than the Ki values for the reversible process.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic biotransformation of parathion: role of cytochrome P450 in NADPH- and NADH-mediated microsomal oxidation in vitro

In vitro studies have established that cytochrome P450 (P450) is deactivated by the electrophilic sulfur atom released during the enzymic oxidation of parathion to paraoxon. However, in vivo studies in rats have been unable to demonstrate significant P450 loss. This study evaluated the possibility that there may be alternate pathways of parathion biotransformation in liver, other than those mediated by P450 and supported by NADPH. Initial experiments confirmed that parathion administration did not decrease microsomal P450 or testosterone hydroxylation activities. Subsequent in vitro experiments identified an NADH-dependent pathway of parathion biotransformation, and MS was used to confirm that paraoxon and 4-nitrophenol were the products of both the NADH- and NADPH-dependent reactions. The Michaelis constants of the NADH-dependent formation of paraoxon and 4-nitrophenol (26 +/- 6 microM and 53 +/- 10 microM, respectively) were approximately 3-fold greater than those for the NADPH-supported reactions (9 +/- 1 microM and 18 +/- 3 microM, respectively). Induction of male rats with phenobarbital and dexamethasone, but not beta-naphthoflavone, produced similar increases in the rates of NADH- and NADPH-mediated parathion metabolism. Rates of NADH- and NADPH-dependent metabolism were highly correlated in linear relationships. An anti-NADPH-cytochrome P450 reductase (NADPH-P450 reductase) antibody partially inhibited microsomal parathion oxidation mediated by either cofactor, and the P450 inhibitor clotrimazole was similarly effective against the NADH- and NADPH-supported oxidation of parathion. Finally, a reconstituted system containing P450 2B1, NADPH-P450 reductase, and phospholipid supported parathion oxidation mediated by NADH.(ABSTRACT TRUNCATED AT 250 WORDS)

Competitive inhibition of human liver microsomal cytochrome P450 3A-dependent steroid 6 beta-hydroxylation activity by cyclophosphamide and ifosfamide in vitro

The prodrugs cyclophosphamide (CP) and ifosfamide (IF) are oxidized by hepatic cytochrome P450 (P450) to the active cytotoxic species, phosphoramide mustard. Acrolein (prop-2-enal) is also formed during CP and IF activation in rat liver and has been associated with P450 destruction. Analogous inactivation of human liver P450s by CP or IF could lead to pharmacokinetic interactions with coadministered drugs. The present study investigated the susceptibilities of human hepatic P450s to inhibition and inactivation by CP and IF in vitro. Unlike the situation in rat liver microsomes, total P450 was not decreased after incubation of CP or IF with NADPH and human fractions. However, CP and IF inhibited testosterone 6 beta-hydroxylation mediated by P450s 3A but not P450 1A2-dependent 7-ethylresorufin O-deethylation, P450 2C-dependent tolbutamide methyl hydroxylation or P450 2E1-mediated N-nitrosodimethylamine N-demethylation. Kinetic analysis indicated that the drugs were reversible (competitive) inhibitors of testosterone 6 beta-hydroxylation (Km, 94 +/- 8 microM) in human liver microsomes (KiS, 510 +/- 20 microM and 490 +/- 40 microM for CP and IF, respectively). Time-dependent intensification of the inhibition of the activity by CP or IF did not occur; this supports the observation that P450 was refractory to inactivation. The rates of acrolein formation from CP and IF in human hepatic microsomes (0.76 +/- 0.23 and 0.19 +/- 0.07 nmol min-1 mg-1 of protein, respectively) were only 18% and 10% of the rates estimated in fractions from untreated rat liver (4.20 +/- 0.04 and 1.96 +/- 0.12 nmol min-1 mg-1 of protein, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of microsomal 17 beta-hydroxysteroid oxidoreduction activities in rat liver by all-trans-, 9-cis- and 13-cis-retinoic acid

Retinoids and steroid hormones mediate their biological effects through nuclear receptors. However, retinoids may alter the intracellular availability of ligands for steroid receptor activation by modulating the activity of biotransformation enzymes. This study investigated the modulation of NAD(H)-linked steroid oxidoreductases in rat hepatic microsomes by retinoids. 13-cis-Retinoic acid inhibited testosterone 17 beta-dehydrogenation (Ki 2.4 +/- 0.5 microM; Km/Ki ratio 0.34 +/- 0.06) but androstenedione reduction was less susceptible to inhibition (Ki 27 +/- 13 microM; Km/Ki ratio 0.045 +/- 0.12). All-trans-retinoic acid was less potent than the 13-cis-isomer and 9-cis-retinoic acid was of intermediate potency. In vivo administration of all-trans-retinoic acid (60 mg/kg i.p. for 7 days) decreased hepatic microsomal oxidoreduction activity, but exposure over shorter periods and 13-cis-retinoic acid were without effect. Thus, all-trans-retinoic acid elicits direct inhibition and may also alter the normal regulation of the oxidoreductase under certain conditions. Three geometric isomers of retinal were potent inhibitors of testosterone dehydrogenation (IC50s approximately 6 microM), but were ineffective against androstenedione reduction. These findings suggest that certain anti-hormonal effects of retinoids may be attributable in part to modulation of endobiotic biotransformation prior to receptor binding and activation.

Characterization of parvalbumin cDNA clones and gene expression in normal and dystrophic mice of strain 129 ReJ

Parvalbumin is a calcium-binding protein found in fast-twitch skeletal muscles and selected cells in the brain. In several dystrophic mutants in the mouse, the parvalbumin content of skeletal muscles and brain is reduced and this deficiency appears to correlate with the inability of these mice to handle enhanced calcium uptake associated with the dystrophic process. In this study, two overlapping cDNA clones of 392 and 1268 base pairs were isolated from a mouse cDNA library in lambda gt11, characterized, and used as probes to study the involvement of the parvalbumin gene and its expression in various tissues of dystrophic mice of strain 129 ReJ. Southern blot analyses of restriction fragments of genomic DNA from normal and dystrophic mice indicate the same number and size of parvalbumin-specific gene fragments observed by other researchers, suggesting that the size of the Pva gene is the same in both normal and dystrophic mice of strain 129 ReJ. Northern blot analyses of total RNA from hind-limb muscles using cloned parvalbumin cDNA as probes revealed an abundant 800-nucleotide mRNA with lesser amounts of a 1000-nucleotide mRNA transcript in both normal and dystrophic mice of strain 129 ReJ. The amount of these mRNAs was reduced by 65-77% in dystrophic muscles preparations and was similar to the levels of beta-actin mRNA in these animals. These results suggest that parvalbumin gene expression is not down regulated in dystrophic mice of strain 129 ReJ.

Inhibition and inactivation of constitutive cytochromes P450 in rat liver by parathion

Phosphorothioate pesticides, such as parathion (O,O-diethyl-O-4-nitrophenyl phosphorothioate), undergo enzymic oxidation to the active insecticidal agents that are the analogous organophosphorus compounds. In hepatic microsomal fractions, the NADPH-mediated conversion of parathion to paraoxon occurs with concomitant loss of cytochrome P450 (P450) and associated activities. In this study, the capacity of parathion to inactivate specific P450 enzymes was studied in rat hepatic microsomes. Parathion was a potent inhibitor of P450 3A2- and 2C11-mediated androst-4-ene-3,17-dione (androstenedione) 6 beta- and 16 alpha-hydroxylation (Ki values of 13 +/- 2 and 2.3 +/- 0.1 microM, respectively, and Km/Ki ratios of 1.4 +/- 0.2 and 11 +/- 1, respectively). After a 10-min preincubation between parathion and NADPH-supplemented microsomes, to inactivate P450 before androstenedione hydroxylation was carried out, the corresponding Km/Ki ratios were increased to 3.5 +/- 0.4 and 35 +/- 6, reflecting 2.5- and 3.2-fold enhancement of inhibition of P450 3A2- and 2C11-dependent activities. In contrast to these findings, P450 2A1/2-mediated androstenedione 7 alpha-hydroxylation was refractory to inhibition and P450 2C6-mediated progesterone 21-hydroxylation was inhibited but not inactivated by the pesticide. Further studies established that androstenedione 6 beta- and 16 alpha-hydroxylation pathways were inactivated with maximal half-times of 2.59 min and 1.72 min, respectively. Although the incubation of parathion (50 microM) with rat liver microsomes for 10 min led to a 16% decrease in P450 estimated spectrophotometrically, immunoblot analysis revealed no change in the microsomal content of P450 2C11 apoprotein. Finally, NADPH-mediated metabolism of parathion to paraoxon (by desulfuration) and 4-nitrophenol (by oxidative cleavage of the phosphorothioate ester) occurred efficiently in microsomes (4.32 and 4.35 nmol/min/mg of protein, respectively). P450 loss was estimated under the same incubation conditions and, thus, 210 parathion molecules were oxidized for each molecule of holo-P450 lost. These findings establish that parathion is a potent inhibitor and inactivator of the principal constitutive P450s, 3A2 and 2C11, in rat liver, whereas the P450s 2A1 and 2A2 are refractory to either inhibition or inactivation. Another major constitutive enzyme, P450 2C6, is inhibited effectively by parathion but does not appear to be subject to inactivation.

Social drinking and cognitive functioning in college students: a replication and reversibility study

The purposes of this study were to replicate a previous study of the relationship between alcohol consumption and cognitive functioning in college students and to investigate the reversibility of negative effects of social drinking on cognitive functioning when randomly assigned subjects abstained from drinking for 2 weeks. The previous study was replicated by administering the same battery of neuropsychological tests to 170 subjects (103 women) during the first testing session. Like the original study, the present study demonstrated several significant predicted inverse relationships between drinking and cognitive performance, but specific relationships between various drinking and cognitive variables were not replicated. As in the original study, some significant nonpredicted relationships also occurred. At the end of the first testing session, subjects were randomly assigned either to abstain from drinking or to maintain their usual drinking patterns for 2 weeks. They were then administered a different neuropsychological battery designed to assess functions similar to the original battery. Consumption the previous 2 weeks was significantly lower in the abstain group than in the maintain group, but there were no significant differences in the predicted direction between groups on the cognitive variables. Several significant predicted inverse correlations between drinking variables and cognitive performance occurred, but some nonpredicted relationships occurred also. Problems and implications for research in social drinking are discussed.

Alcohol use and cognitive functioning in men and women college students

Two studies of the relationship between alcohol consumption and cognitive functioning in men and women college students are presented. Study 1 showed several predicted relationships of decreased cognitive performance on various tests with increased quantity of alcohol per occasion and total lifetime consumption in both women and men. Study 2a was designed to replicate study 1, but the pattern of relationship of cognitive and consumption variables was quite different, e.g., increased cognitive performance was associated with increased quantity per occasion for several tests in males. Study 2b was designed to demonstrate reversibility of the negative effects of consumption on cognition by randomly assigning half of the subjects to abstain for two weeks. Reversibility was not demonstrated. Difficulties in studying these effects in college students are discussed.

The influence of amines on various platelet responses

Four amines, galactosamine, mannosamine, histamine and arginine were studied for their effects on platelet aggregation, platelet morphological changes, platelet protein phosphorylation and platelet secretion. Galactosamine inhibited platelet aggregation in response to arachidonic acid and ionophore A23187 but did not inhibit changes in platelet morphology, or in platelet protein phosphorylation in response to these agents and only partially inhibited platelet secretion. The results suggest that galactosamine can be used as a selective inhibitor of platelet-platelet attachment without having a significant effect on intracellular processes. Mannosamine was similar to galactosamine except that it partially suppressed phosphorylation of myosin light chain. Histamine was similar to mannosamine except that some platelet damage was seen in platelets exposed to histamine and arachidonic acid or ionophore A23187. Arginine was non-selective: it suppressed platelet aggregation, secretion and phosphorylation of myosin light chain and a 40 kDa protein (40P) in response to arachidonic acid and ionophore A23187. Arginine was also potent in suppressing platelet morphological changes. When the same four amines were evaluated for their effects on thrombin-induced aggregation; secretion was inhibited concomitantly with inhibition of aggregation. Inhibition of myosin light chain and 40P phosphorylation was evident with galactosamine, suggesting that when thrombin is used as the agonist, galactosamine is not a specific inhibitor of platelet-platelet attachment. These amines therefore have various effects on platelet responses. Under some conditions and with arachidonic acid or ionophore A23187 as agonist, one of them, galactosamine, can be used as a selective inhibitor of platelet-platelet attachment.

Alcohol consumption and cognitive functioning in college students

Decreased cognitive performance was significantly correlated with increased quantity of alcohol per occasion and with total lifetime consumption in both women and men college students tested while sober. In men, however, increased performance on some tasks was also significantly correlated with increased frequency of drinking.