Multicenter, Observational Cohort Study Evaluating Third-Generation Cephalosporin Therapy for Bloodstream Infections Secondary to Enterobacter, Serratia, and Citrobacter Species

OBJECTIVES

There is debate on whether the use of third-generation cephalosporins (3GC) increases the risk of clinical failure in bloodstream infections (BSIs) caused by chromosomally-mediated AmpC-producing Enterobacterales (CAE). This study evaluates the impact of definitive 3GC therapy versus other antibiotics on clinical outcomes in BSIs due to Enterobacter, Serratia, or Citrobacter species.

METHODS

This multicenter, retrospective cohort study evaluated adult hospitalized patients with BSIs secondary to Enterobacter, Serratia, or Citrobacter species from 1 January 2006 to 1 September 2014. Definitive 3GC therapy was compared to definitive therapy with other non-3GC antibiotics. Multivariable Cox proportional hazards regression evaluated the impact of definitive 3GC on overall treatment failure (OTF) as a composite of in-hospital mortality, 30-day hospital readmission, or 90-day reinfection.

RESULTS

A total of 381 patients from 18 institutions in the southeastern United States were enrolled. Common sources of BSIs were the urinary tract and central venous catheters (78 (20.5%) patients each). Definitive 3GC therapy was utilized in 65 (17.1%) patients. OTF occurred in 22/65 patients (33.9%) in the definitive 3GC group vs. 94/316 (29.8%) in the non-3GC group (p = 0.51). Individual components of OTF were comparable between groups. Risk of OTF was comparable with definitive 3GC therapy vs. definitive non-3GC therapy (aHR 0.93, 95% CI 0.51-1.72) in multivariable Cox proportional hazards regression analysis.

CONCLUSIONS

These outcomes suggest definitive 3GC therapy does not significantly alter the risk of poor clinical outcomes in the treatment of BSIs secondary to Enterobacter, Serratia, or Citrobacter species compared to other antimicrobial agents.

Association between Use of Methadone, Other Central Nervous System Depressants, and QTc Interval-Prolonging Medications and Risk of Mortality in a Large Cohort of Women Living with or at Risk for Human Immunodeficiency Virus Infection

STUDY OBJECTIVE

To evaluate the association between use of methadone, other central nervous system (CNS) depressants, and QTc interval-prolonging medications and risk of mortality among human immunodeficiency virus (HIV)-infected and at-risk HIV-uninfected women.

DESIGN

Multicenter, prospective, observational cohort study (Women's Interagency HIV Study [WIHS]).

PARTICIPANTS

A total of 4150 women enrolled in the WIHS study between 1994 and 2014 who were infected (3119 women) or not infected (1031 women) with HIV.

MEASUREMENTS AND MAIN RESULTS

Data on medication utilization were collected from all study participants via interviewer-administered surveys at 6-month intervals (1994-2014). Mortality was confirmed by National Death Index data. With age defining the time scale for the analysis, Cox proportional hazards models were used to estimate hazard ratios (HRs) for all-cause mortality in HIV-infected and -uninfected women and non-acquired immunodeficiency syndrome (AIDS) deaths in HIV-infected women. A total of 1046 deaths were identified, of which 429 were considered non-AIDS deaths. Use of benzodiazepines, CNS depressants (excluding methadone), and number of medications with conditional QTc interval-prolonging effects were each associated with all-cause mortality in multivariate models of HIV-infected women: hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.01-1.60, p=0.037; HR 1.61, 95% CI 1.35-1.92, p<0.0001; and HR 1.15 per drug, 95% CI 1.00-1.33, p=0.047, respectively. Other explanatory variables for all-cause mortality in this model included HIV viral load, CD4+  cell count, renal function, hemoglobin and albumin levels, HIV treatment era, employment status, existence of depressive symptoms, ever use of injection drugs, and tobacco smoking. Of interest, use of CNS depressants (excluding methadone) was also associated with non-AIDS deaths (HR 1.49, 95% CI 1.49-2.2, p<0.0001). Although use of benzodiazepines and conditional QT interval-prolonging medications were associated with increased risk of non-AIDS mortality (HR 1.32 and 1.25, respectively), the effect was not statistically significant (p>0.05).

CONCLUSION

In this cohort of HIV-infected and at-risk HIV-uninfected women, use of benzodiazepines, CNS depressants, and conditional QTc interval-prolonging medications were associated with a higher risk of mortality independent of methadone and other well-recognized mortality risk factors. Care must be taken to assess risk when prescribing these medications in this underserved and at-risk patient population.

Impact of an infectious diseases advanced pharmacy practice experience on student knowledge

INTRODUCTION

The goal of this assessment was to determine knowledge acquisition by pharmacy students during an infectious diseases (ID) advanced pharmacy practice experience (APPE).

METHODS

A 50-question knowledge-based examination was given to every student on a five-week ID APPE between July 1, 2013 and May 5, 2017. The examination was also given to control students (those who did not have an ID APPE) immediately prior to graduation. The primary outcome was difference in examination performance after completion of the ID APPE. Secondary outcomes included correlations between examination performance and number of previous inpatient clinical rotations (ICR), average score in therapeutic coursework (TC), and rotation block (RB).

RESULTS

Forty students were included (control = 5, experimental = 35). Average pre-test scores were similar between experimental and control students [61.7 (10.9)% versus 62.0 (5.1)%, respectively], but experimental post-test scores [80.2 (7.9)%] were significantly better than pre-test scores for both experimental (p < .05) and control student (p < .05) examination scores. ICR [1.3 (1.0) rotations], TC [81.5 (3.9)%], and RB (median = 4) had a positive correlation with pre-examination performance (R = .5, .5, and .4, respectively).

DISCUSSION

Improved ID pharmacotherapy knowledge is needed. Baseline scores of students taking an ID elective were similar to control students who completed the entire year of APPEs, and knowledge scores were higher in ID students after APPE completion. There was a positive, but not strong, correlation between pre-examination performance and number of previous rotations, therapeutic coursework, and rotation block.

CONCLUSION

A five-week ID elective APPE improved student performance on a knowledge-based examination. Consideration should be given to more consistent integration of ID principles across all rotation types.

Rethinking urinary antibiotic breakpoints: analysis of urinary antibiotic concentrations to treat multidrug resistant organisms

OBJECTIVE

The present study analyzed whether renally eliminated antibiotics achieve sufficient urinary concentrations based on their pharmacokinetic/pharmacodynamic principles to effectively eradicate organisms deemed resistant by automated susceptibility testing.

RESULTS

Lower median minimum inhibitory concentrations against enterobacteriaceae were noted for ceftriaxone, cefepime, and doripenem when comparing Etest^® to Vitek^®. All Pseudomonas aeruginosa isolates were susceptible to cefepime, ciprofloxacin, and doripenem with both susceptibility methods, but higher median minimum inhibitory concentrations were observed with Etest^®. Urine concentrations/time profiles were calculated for standard doses of ceftriaxone, cefepime, doripenem, and ciprofloxacin. The data presented in the current study suggests high urine concentrations of antibiotics may effectively eradicate bacteria which were determined to be resistant per in vitro susceptibility testing.

Systematic review of professional liability when prescribing β-lactams for patients with a known penicillin allergy

OBJECTIVE

To describe medical negligence and malpractice cases in which a patient with a known penicillin allergy received a β-lactam and experienced an adverse reaction related to the β-lactam.

DATA SOURCES

Lexis-Nexus, Westlaw, and Google Scholar were searched.

STUDY SELECTIONS

Medical negligence and malpractice cases were eligible for inclusion if they met the following criteria: the plaintiff had a known penicillin allergy, received a β-lactam, and experienced an adverse event. All United States federal and state cases were eligible.

RESULTS

Twenty-seven unique cases met the inclusion criteria. Eighteen cases involved the receipt of a penicillin-based antibiotic; of these cases with a known legal outcome, the plaintiff (patient or representative) prevailed or settled in 3 cases and defendants (providers) prevailed in 7 cases. Seven cases involved the receipt of a cephalosporin; of these cases with a known legal outcome, the plaintiff settled with physicians before trial in 1 case and defendants prevailed in 3 cases. Two cases involved the receipt of a carbapenem. Defendants prevailed in one case and the legal outcome of the other case is unknown. In cases in which the defense successfully moved for summary judgment, judges cited a lack of scientific evidence demonstrating a cephalosporin or carbapenem was contraindicated for a patient with a penicillin allergy.

CONCLUSION

The cases with published legal outcomes found limited professional liability for clinicians who prescribed cephalosporins or carbapenems to a patient with a known penicillin allergy. These results may decrease the litigation fears of practitioners and risk managers within health care systems.

Impact of an antifungal stewardship intervention on optimization of candidemia management

Background

Candidemia represents a leading cause of healthcare-associated bloodstream infections with significant morbidity and mortality. Previous studies have demonstrated that comprehensive care bundles improve candidemia management but are time-consuming.

Objective

To determine the impact of a one-time targeted candidemia intervention on time to initiation of adequate therapy compared to standard of care.

Methods

This Institutional Review Board (IRB)-approved, quasi-experiment evaluated a targeted candidemia intervention involving a single phone call to the primary team providing recommendations for care. Daily follow-up was provided by the infectious diseases (ID) consult service. Two time periods were evaluated: pre-intervention (01 August 2012 to 31 July 2014) and post-intervention (01 October 2014 to 30 September 2016). The primary endpoint was time to adequate antifungal therapy (TTx) in the business hours (6 a.m. to 6 p.m. Monday through Friday) population (BHP). Secondary endpoints were TTx in the total population as well as infection-related length of stay (IF-LOS) and compliance with quality indicators (composite endpoint: ophthalmology (OPH) consult, repeat cultures, and ⩾14 days of adequate therapy).

Results

In all, 117 patients were included (pre-intervention = 50, post-intervention = 67, BHP = 51). TTx decreased from 2 h 57 m to 2 h 12 m (p = 0.094) in the BHP and 3 h 30 m to 2 h 9 m (p = 0.021) in the total population. There was no difference in IF-LOS (p = 0.797), compliance with quality indicators (p = 0.343), or in-hospital mortality (p = 0.761). Post-intervention, there were more ID and OPH consults (p < 0.001).

Conclusions

Our one-time candidemia intervention did not statistically decrease time to adequate therapy in the BHP, but did in the total population. No differences were found for other clinical outcomes, except increases in ID and OPH consults. Further studies are needed to examine whether a one-time intervention is non-inferior to a more comprehensive care bundle.

Time-Kill Analysis of Ceftolozane/Tazobactam Efficacy Against Mucoid Pseudomonas aeruginosa Strains from Cystic Fibrosis Patients

INTRODUCTION

Mucoid Pseudomonas aeruginosa (MP) strains in cystic fibrosis (CF) patients are thought to initiate the chronic infection stage of CF and are associated with pulmonary function decline.

OBJECTIVES

The purpose of this study was to assess the susceptibility of MP strains to ceftolozane/tazobactam and the efficacy of ceftolozane/tazobactam against MP strains compared with those for standard-of-care antipseudomonal antibiotics.

METHODS

Ten clinical isolates of MP from CF patients were tested for susceptibility with Etest and time-kill analysis with ceftolozane/tazobactam compared with ceftazidime, cefepime, ciprofloxacin, meropenem, tobramycin, and polymyxin B. The physiologic free peak concentrations were used in the time-kill experiments.

RESULTS

Ceftolozane/tazobactam minimum inhibitory concentrations ranged from 0.032 to 1.5 mg/L. In the time-kill analysis, the mean starting inoculum for the isolates was 6.29 ± 0.22 log₁₀ colony forming units (CFU) per milliliter. On average, ceftolozane/tazobactam, cefepime, ciprofloxacin, meropenem, tobramycin, and polymyxin B all demonstrated bactericidal activity. With all isolates taken into account, polymyxin B, tobramycin, meropenem, and ceftolozane/tazobactam 3 g were the most potent, with reductions in inoculum of 5.07 ± 0.45, 4.58 ± 2.2, 4.76 ± 0.71, and 4.17 ± 0.94 log₁₀ CFU/mL, respectively. Ceftolozane/tazobactam 1.5 g, cefepime, and ciprofloxacin reduced the starting inoculum by 3.74 ± 0.99, 3.42 ± 1.4, and 3.23 ± 2.0 log₁₀ CFU/mL, respectively. Despite 90% susceptibility, ceftazidime was bactericidal against seven of ten strains, with an average reduction in starting inoculum of 2.91 ± 2.2 log₁₀ CFU/mL.

CONCLUSION

Ceftolozane/tazobactam activity against MP strains derived from CF patients was comparable to that of standard-of-care agents at both the 1.5-g dose and the 3-g dose. Further in vitro modeling and clinical trials are warranted.

Systematic Review of Professional Liability when Prescribing Β-Lactams for Patients with a Known Penicillin Allergy

Background

Patients labeled as penicillin allergic are more likely to receive second line non-β-lactam antibiotics, experience higher rates of treatment failure, and incur higher antibiotic costs. Fear of litigation has been identified as a reason clinicians avoid using β-lactams in a patient with a penicillin allergy. The systematic review objective is to describe medical negligence and malpractice cases in which known penicillin allergy patients received a β-lactam and experienced an adverse reaction.

Methods

Lexis-Nexus and Google Scholar were used to identify relevant legal cases. Variables collected from each case included date of publication, legal jurisdiction, date of injury, plaintiff and defendant demographics, health care setting, plaintiff clinical outcome, and legal outcome.

Results

Twenty-seven unique cases met inclusion criteria. The earliest case was published in 1959 and the most recent in 2013. The highest number of cases filed&#x2028;(n = 7) occurred in the most recent 10 year segment, from 2005 to 2015. Eighteen cases involved the receipt of a penicillin-based antibiotic; of these cases with a known legal outcome, the plaintiff (patient) prevailed or settled in 3 cases and defendants (providers) prevailed in 7 cases. Seven cases involved the receipt of a cephalosporin; of these cases with a known legal outcome, the plaintiff settled with physicians prior to trial in 1 case and defendants prevailed in 3 cases. Two cases involved the receipt of a carbapenem. Defendants prevailed in 1 case and the legal outcome of the other case is unknown. In cases where the defense successfully moved for summary judgment, judges cited a lack of scientific evidence demonstrating that a cephalosporin or carbapenem were contraindicated for a patient with a penicillin allergy.

Conclusion

The cases with published legal outcomes found limited professional liability and identify clear precedence for clinicians who prescribed cephalosporins or carbapenems to a patient with a known penicillin allergy. These results should decrease litigation fears of providers and risk managers within healthcare systems.

Disclosures

All authors: No reported disclosures.

Shifts in antimicrobial consumption and infection rates before and during a piperacillin/tazobactam shortage

OBJECTIVES

Anti-infective shortages represent a growing threat to optimum management of infected patients and alter the institutional selective pressure against hospital-acquired infections (HAIs). The objective of this analysis was to assess the impact of a shortage of piperacillin/tazobactam (TZP) on overall antibacterial use and HAI rates at an academic institution.

METHODS

Antimicrobial use and infection data were extracted from TheraDoc Clinical Surveillance Software (Premier, Inc.) for adult patients and were stratified as pre-shortage (October-December 2014) and post-shortage (February-April 2015). Paediatric and emergency department use were excluded. Antimicrobial use was reported as percent change and defined daily doses (DDD)/1000 patient-days (PD). Pre- and post-shortage vancomycin-resistant enterococci (VRE) and Clostridium difficile-associated diarrhoea (CDAD) rates were normalised to 1000 PD/month.

RESULTS

Total use of target antimicrobials remained constant before and after TZP shortage (990.29 vs. 957.77). Total TZP use fell 95.2% (81.1 vs. 3.9). Total meropenem use rose 96.0% (42.3 vs. 82.9) after the shortage, driven by a 125.4% increase in use for non-ICU patients. Cefepime and ceftazidime use rose 97.9% (28.2 vs. 55.8) and 94.2% (1.6 vs 3.0), respectively. Cefepime use in non-ICU patients rose 223.2%. Fluoroquinolone consumption did not differ between periods. CDAD rates decreased (-21.8%), whilst VRE rates doubled during the shortage (0.6 vs. 1.3 infections/1000 PD/month).

CONCLUSIONS

Whilst overall antimicrobial use appeared steady, the TZP shortage resulted in increased use of multiple other antimicrobials. The doubling of VRE rates is concerning and illustrates the need for increased antimicrobial stewardship vigilance and education in response to shifting prescribing patterns during shortages.

Managing acute bacterial skin and skin structure infections: Focus on new lipoglycopeptides

Acute bacterial skin and skin structure infections (ABSSSI) are some of the most commonly encountered infections worldwide. Hospitalizations as a result of ABSSSI are associated with high mortality. This article discusses the role of oritavancin and dalbavancin, two new lipoglycopeptides, in the context of the other I.V. available standard therapy options.

Comparison of susceptibility patterns using commercially available susceptibility testing methods performed on prevalent Candida spp

The rising rates of invasive fungal infections caused by non-albicans Candida and the increasing emergence of antifungal resistance complicate the management of invasive candidiasis. Accurate and timely antifungal susceptibility testing is critical to targeting antifungal therapy. The purpose of this study was to compare commercially available susceptibility testing methods using prospectively collected Candida isolates. Susceptibility testing was performed on 74 Candida isolates collected from July 2014 to March 2015 using broth microdilution according to the Clinical and Laboratory Standards Institute method, Etest, Vitek 2 (YS-05) and Sensititre. Essential agreement and categorical agreement (CA) were assessed using the reference method. Of the 34 total blood isolates collected, Candida albicans comprised only 38 % (13) of the Candida spp. with Candidaglabrata being nearly as prevalent (29 %, 10). CA using Etest was 86 % for fluconazole, 72 % for caspofungin, 98 % for micafungin and 97 % for anidulafungin. Vitek 2 CA was 90 % for fluconazole and 98 % for caspofungin. Sensititre CA was 93 % for fluconazole, 98 % for caspofungin, 98 % for micafungin and 100 % for anidulafungin. Although our study tested a small population of Candida isolates, our results were variable by method. When implementing antifungal susceptibility testing, clinicians should be aware of the strengths and limitations of each testing method.

Daptomycin-induced rhabdomyolysis and acute liver injury

Daptomycin use is a known cause of rhabdomyolysis; its role in liver injury is less certain. We report a case of daptomycin-induced rhabdomyolysis with liver injury. This report indicates a role for liver function monitoring while receiving daptomycin, as well as the importance of promptly considering drug toxicities in acute and emergency care settings.

Cost-benefit and effectiveness analysis of rapid testing for MRSA carriage in a hospital setting

A cost-effectiveness analysis was conducted comparing the polymerase chain reaction assay and traditional microbiological culture as screening tools for the identification of methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to the pediatric and surgical intensive care units (PICU and SICU) at a 722 bed academic medical center. In addition, the cost benefits of identification of colonized MRSA patients were determined. The cost-effectiveness analysis employed actual hospital and laboratory costs, not patient costs. The actual cost of the PCR assay was higher than the microbiological culture identification of MRSA ($602.95 versus $364.30 per positive carrier identified). However, this did not include the decreased turn-around time of PCR assays compared to traditional culture techniques. Patient costs were determined indirectly in the cost-benefit analysis of clinical outcome. There was a reduction in MRSA hospital-acquired infection (3.5 MRSA HAI/month without screening versus 0.6/month with screening by PCR). A cost-benefit analysis based on differences in length of stay suggests an associated savings in hospitalization costs: MRSA HAI with 29.5 day median LOS at $63,810 versus MRSA identified on admission with 6 day median LOS at $14,561, a difference of $49,249 per hospitalization. Although this pilot study was small and it is not possible to directly relate the cost-effectiveness and cost-benefit analysis due to confounding factors such as patient underlying morbidity and mortality, a reduction of 2.9 MRSA HAI/month associated with PCR screening suggests potential savings in hospitalization costs of $142,822 per month.

Artemether-lumefantrine: an option for malaria

OBJECTIVE

To review the pharmacology, pharmacokinetics, safety, and efficacy of artemether-lumefantrine for the treatment of Plasmodium falciparum malaria.

DATA SOURCES

English-language articles indexed in PubMed (1947-November 2011) were identified, using the search terms artemether-lumefantrine, artemether-lumefantrine AND malaria, Coartem, and Coartem AND malaria.

STUDY SELECTION AND DATA EXTRACTION

Available English-language articles were reviewed. In addition, the malaria treatment regimens recommended by region as provided by the World Health Organization and the treatment guidelines from the Centers for Disease Control and Prevention were reviewed.

DATA SYNTHESIS

Artemether-lumefantrine is an artemisinin-derived combination antimalarial approved by the Food and Drug Administration in 2009 for the treatment of P. falciparum malaria. The dual mechanisms of action of artemether-lumefantrine provide rapid and sustained parasite clearance. In the reviewed studies, the polymerase chain reaction (PCR)-corrected 28-day cure rates of artemether-lumefantrine were noninferior to the most common comparators, including chloroquine, dapsone, and other artemisinin derivatives (86-100% vs 51-100%, respectively). PCR-corrected day-42 cure rates were 92-99.3% for artemether-lumefantrine versus 62-100% for the comparator groups. The major adverse effects (gastrointestinal and central nervous system) were mild to moderate in severity and did not require a change in therapy. Although adherence to artemether-lumefantrine has been described as a potential problem due to the complicated dosing schedule, studies have described clinical cure rates similar to those of other antimalarials.

CONCLUSIONS

Artemether-lumefantrine is a safe and effective treatment for children and adults with P. falciparum malaria.

Bone loss and fracture risk associated with thiazolidinedione therapy

The increasing use of thiazolidinediones for the treatment of type 2 diabetes mellitus, coupled with the potential for fractures in the aging population, poses a significant concern for health care providers. This concern is based on many reports of postapproval adverse musculoskeletal effects, particularly bone changes and fractures. To better understand the effects of thiazolidinediones on bone health, we conducted a PubMed search of articles published from January 1966-June 2009. We reviewed the hypothesized mechanisms for thiazolidinedione-induced adverse effects on bone, studies that evaluated thiazolidinedione use and fracture risk, potential treatment options for fracture minimization, and future directions for research. Thiazolidinedione-induced bone changes may stem from the ability of these drugs to reduce the activity of osteoblasts without an appreciable effect on osteoclasts, shifting the balance of bone homeostasis to favor bone loss. Clinical data suggest that treating patients who have type 2 diabetes with thiazolidinediones has detrimental effects on bone health, as measured by reduced bone mineral density and increased fracture rates, notably distal extremity fractures in female patients. Thiazolidinediones are selective peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists; thus, continued pursuit of PPAR system selectivity and investigation of other PPAR agonists are crucial to understanding and avoiding these detrimental effects. Clinicians, particularly pharmacists, must take an active role in educating colleagues on the importance of screening thiazolidinedione-treated patients for fracture risk, counseling patients on adequate calcium and vitamin D intake and fall prevention, and appropriately selecting therapy for secondary prevention of fracture.

Medication-induced adverse effects: important concepts for the hand therapist

NARRATIVE REVIEW: Myopathy, fracture, tendon rupture, and neuropathy are severe physical adverse effects associated with commonly prescribed medications. Recognition of and exercise adjustment for these medication-induced effects by the therapist is essential to providing adequate care. The normal structure and function of muscle, tendon, cartilage, or bone may be altered by medications, leading to significant disability. The number of patients presenting to therapists with medication-induced physical complaints is rising with increases in medication utilization. Therapists should be involved in adverse effect risk reduction by 1) identification and reporting of potential adverse medication reactions, 2) adjustment of exercise regimen when the patient is on a medication with potential damaging effects on tendon, muscle, or cartilage, and 3) vigilant screening for medication-induced myopathies, fractures, neuropathies, and tendinopathies. Although many medications induce physical adverse effects, understanding the most serious musculoskeletal effects of commonly prescribed medications is critical for therapists.

LEVEL OF EVIDENCE

5.

Insulin--carcinogen or mitogen? Preclinical and clinical evidence from prostate, breast, pancreatic, and colorectal cancer research

Diabetes mellitus is a chronic disease that affects > 23.6 million Americans, and occurs when the body is unable to produce or becomes resistant to endogenous insulin. This alteration of insulin's action reduces adequate utilization of glucose transporter type 4 (GLUT4) receptors, which are responsible for cellular glucose uptake. Thus, exogenous administration of human insulin and insulin analogs is an important modality used to reduce morbidity and mortality in both type 1 and type 2 diabetes. According to 2007 estimates, 27% of all patients with diabetes use some form of insulin therapy. The increasing utilization of insulin has become a cause for concern because findings from several observational trials have suggested an association with an increased risk of developing cancer. To help elucidate the potential interplay between insulin use and cancer, we searched PubMed and MEDLINE to identify articles that assessed the carcinogenic and/or mitogenic potential of diabetes treatments, focusing on insulin specifically. Data from our review suggest that insulin analogs, particularly insulin glargine, may play more of a mitogenic than a carcinogenic role in association with different types of cancer, suggesting an amplified rate of existing tumor growth in the presence of insulin analogs. Evidence for insulin-induced mitogenicity appears to be most prevalent in prostate, breast, pancreatic, and colorectal cancers. In conclusion, the positive effects of insulin therapy on reducing morbidity and mortality in diabetes greatly outweigh the risks at this time. However, clinicians must be diligent in both screening for new cancers in patients receiving insulin and in monitoring for tumor growth or maintenance of remission in patients with existing cancers.

Atomistic view of the autosurfactant effect during GaN epitaxy

The Ga-N site exchange critical to the autosurfactant effect during GaN epitaxy is studied. On the GaN(0001) pseudo (1x1), the first site exchange results in N incorporation at the subsurface T1 site, forming ghost islands. The second exchange that converts these islands to that of bilayer height can be triggered by continued scanning tunneling microscopy imaging, which involves electrons tunneling to or from localized states associated with the second layer Ga. The resulting electrostatic force sets off a chain reaction which frees these Ga atoms, allowing N to form covalent Ga-N-Ga bonds of a new GaN bilayer.

Role of defect sites and Ga polarization in the magnetism of Mn-doped GaN

We report a study of the Mn local structure, magnetism, and Ga moments in molecular beam epitaxy grown Mn-doped GaN films. Using x-ray absorption spectroscopy and magnetic circular dichroism, we find two distinct Mn sites and a Ga moment antiparallel to Mn. First-principles calculations reproduce this phenomenology and indicate that Mn preferentially populates Ga sites neighboring N split interstitial defects. These results show that defects may strongly affect the Mn ordering and magnetism, and that the GaN valence band is polarized, providing a long-range ferromagnetic ordering mechanism for Ga1-xMnxN.

Stability of interindividual differences in serotonin function and its relationship to severe aggression and competent social behavior in rhesus macaque females

Few studies have investigated longitudinally interindividual stability of cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) concentrations in adult nonhuman primates across time and between baseline and stressful conditions. Furthermore, whereas studies with male macaques consistently have reported a significant, negative correlation between CSF 5-HIAA and rates of spontaneous aggression, wounding, and severe aggression, very few studies have examined this relationship in adult female nonhuman primates. Even fewer studies have investigated correlations between CSF 5-HIAA and competent social behavior, such as social dominance, in female monkeys. In the present study, two social groups of adult rhesus monkeys (Macaca mulatta) were formed by placing 16 females (aged 42 to 180 months, mean age: 68 months) in one of two indoor-outdoor enclosures with one or two adult males. CSF norepinephrine (NE), monoamine metabolites, and behavioral data were collected systematically over a 24-week period. In week 5 of the study, one additional female, not familiar to any of the other subjects, was added to each social group. Thereafter the groups were left undisturbed, and data characterizing spontaneous aggressive wounding and severe wound injuries in the females were collected for an additional year. The results showed that both group introduction and the addition of a new subject into each group resulted in increased monoamine turnover in the animals within the social groups. Interindividual differences in CSF concentrations of each of the monoamine metabolites and NE were highly stable from the baseline period to the stress samplings, and between stress samplings. Females with low CSF 5-HIAA exhibited higher rates of spontaneous aggressive wounding, and they were more likely to be removed from their social groups for aggressive wounding and/or treatment of injuries. CSF NE concentrations also were negatively correlated with rates of spontaneous aggression. In contrast, competitive aggression, i.e. noninjurious aggression used to maintain social dominance ranking, was not correlated with CSF 5-HIAA or NE. Females with above average CSF 5-HIAA prior to and following group formation were more likely to attain and maintain a high social dominance ranking within their social group than females with below average CSF 5-HIAA. The present findings indicate that CNS monoamine functioning in adult female rhesus macaques is traitlike, showing a high degree of interindividual stability across time and setting. These findings also suggest a role for serotonin in controlling impulses that regulate aggression and that competent social behavior among nonhuman primates may require average or above average serotonin functioning.