Risk factors for catheter related thrombosis during outpatient parenteral antimicrobial therapy.

BACKGROUND: Outpatient parenteral antimicrobial therapy (OPAT) delivery using peripherally inserted central catheters is associated with a risk of catheter related thrombosis (CRT). Individualised preventative interventions may reduce this occurrence, however patient selection is hampered by a lack of understanding of risk factors. We aimed to identify patient, infection or treatment related risk factors for CRT in the OPAT setting. METHODS: Retrospective case control study (1:3 matching) within OPAT services at two tertiary hospitals within Australia. RESULTS: Over a 2 year period, encompassing OPAT delivery to 1803 patients, there were 19 cases of CRT, giving a prevalence of 1.1% and incidence of 0.58/1000 catheter days. Amongst the cases of CRT, there were nine (47%) unplanned readmissions and two (11%) pulmonary emboli. Compared to controls, cases had a higher frequency of malposition of the catheter tip (4/19 (21%) vs 0/57 (0%), p = 0.003) and complicated catheter insertion (3/19 (16%) vs 1/57 (2%), p = 0.046). CONCLUSIONS: Although CRTs during OPAT are infrequent, they often have clinically significant sequelae. Identification of modifiable vascular access related predictors of CRT should assist with patient risk stratification and guide risk reduction strategies.

Defining the relative impact of muscle versus Schwann cell denervation on functional recovery after delayed nerve repair.

Functional recovery following peripheral nerve injury worsens with increasing durations of delay prior to repair. From the time of injury until re-innervation occurs, denervated muscle undergoes progressive atrophy that limits the extent to which motor function can be restored. Similarly, Schwann cells (SC) in the distal nerve lacking axonal interaction progressively lose their capacity to proliferate and support regenerating axons. The relative contributions of these processes to diminished functional recovery is unclear. We developed a novel rat model to isolate the effects of SC vs. muscle denervation on functional recovery. Four different groups underwent the following interventions for 12 weeks prior to nerve transfer: 1) muscle denervation; 2) SC denervation; 3) muscle + SC denervation (negative control); 4) no denervation (positive control). Functional recovery was measured weekly using the stimulated grip strength testing (SGST). Animals were sacrificed 13 weeks post nerve transfer. Retrograde labeling was used to assess the number of motor neurons that regenerated their axons. Immunofluorescence was performed to evaluate target muscle re-innervation and atrophy, and to assess the phenotype of the SC within the distal nerve segment. Functional recovery in the muscle denervation and SC denervation groups mirrored that of the negative and positive control groups, respectively. The SC denervation group achieved better functional recovery, with a greater number of reinnervated motor endplates and less muscle atrophy, than the muscle denervation group. Retrograde labeling suggested a higher number of neurons contributing to muscle reinnervation in the muscle denervation group as compared to SC denervation (p > 0.05). The distal nerve segment in the muscle denervation group had a greater proportion of SCs expressing the proliferation marker Ki67 as compared to the SC denervation group (p < 0.05). Conversely, the SC denervation group had a higher percentage of senescent SCs expressing p16 as compared to the muscle denervation group (p < 0.05). The deleterious effects of muscle denervation are more consequential than the effects of SC denervation on functional recovery. The effects of 12 weeks of SC denervation on functional outcome were negligible. Future studies are needed to determine whether longer periods of SC denervation negatively impact functional recovery.

Inappropriate Transfer of Burn Patients: A 5-Year Retrospective at a Single Center.

OBJECTIVE: Burn injuries have an annual incidence exceeding 40,000. The Burn Center Referral Criteria published by the American Burn Association (ABA) serve to guide health centers in determining appropriateness of patient transfer to a specialized center. With inappropriate transfer rates reaching up to 77%, reliance on the ABA criteria is critical as the decision to transfer a patient can impose significant costs to both the patient and healthcare system. The aim of this study is to evaluate the appropriateness of all burn patient transfers to a single burn center over a 5-year period and assess the potential role of telemedicine to optimize the assessment and care of this patient population. METHODS: A 5-year retrospective review was conducted to all burn patients transferred or consulted for transfer to our burn center between January 2013 and January 2017. After application of inclusion and exclusion criteria, 767 cases were analyzed, with 612 ultimately being transferred. Outcome measures included basic clinical and demographic information, as well as logistical burn and transfer data such as percent total body surface area and transfer distance. After data collection, 5-year descriptive trends were analyzed, and the ABA criteria were applied to each patient case to evaluate appropriateness of transfer. Patients transferred despite not meeting at least one of the ABA criteria were classified as inappropriately transferred. RESULTS: A total of 25 patients (3.2%) were found to be inappropriate transfers. Statistical analysis compared appropriately transferred patients (n = 587) with those inappropriately transferred. Overall, inappropriately transferred patients were more likely to have superficial partial thickness burns (76% vs 46%, P = 0.05), were less likely to need surgery (4% vs 22%, P < 0.05), and had a higher incidence of upper extremity burns (32% vs 4%, P < 0.01). CONCLUSIONS: Our study increases awareness of the most commonly seen presentation of inappropriately transferred burn patients over a 5-year period at our center. Given the advent of telemedicine, the ability of institutions to pinpoint a subset of patients most vulnerable to inappropriate transfer will allow for a streamlining of resources that will serve to benefit both patients and the health system.

Atypical Mycobacterial Infections After Plastic Surgery Procedures Abroad: A Multidisciplinary Algorithm for Diagnosis and Treatment.

BACKGROUND: The recent rise in medical tourism, especially for cosmetic procedures, has been mirrored by an increase in the incidence of infections with Mycobacterium abscessus, which is an atypical mycobacterium that is ubiquitous in aquatic environments. M. abscessus soft tissue infections arise from the use of improperly sterilized water and surgical equipment during surgical procedures, and these infections have devastating consequences if not promptly treated. M. abscessus infections are notoriously difficult to diagnose and properly treat, and therefore, we illustrate a typical case presentation and provide a comprehensive diagnostic and treatment algorithm. METHODS: Of the patients who have presented to our hospital for treatment of cutaneous M. abscessus infections, a representative patient's story was included to illustrate the typical presentation and treatment timeline. The current literature on M. abscessus infections was reviewed, and this literature and the clinical experience of our plastic surgery and infectious disease teams were used in the creation of a diagnostic and treatment algorithm for M. abscessus infections. RESULTS: M. abscessus infections can have an incubation period of months, and the classic presenting signs include purulent drainage, violaceous nodules, and subcutaneous abscesses at the site of a recent surgery. A key finding is persistence of the infection despite debridement and empiric antibiotic treatment. Cultures grown on mycobacterial-specific growth media are considered the diagnostic criterion standard, but high clinical suspicion is enough to warrant the initiation of treatment. Treatment itself consists of surgical drainage and debridement in combination with multidrug antibiotic regimens that typically include amikacin, a macrolide, and a carbapenem or cephalosporin antibiotic, with the option for macrolide and fluoroquinolone maintenance therapy. CONCLUSIONS: M. abscessus cutaneous infections present with unique history and physical examination findings and often require complex diagnostic workups and treatment plans. Increased provider awareness of the management and potential complications of M. abscessus is crucial to the improvement patient outcomes, as is a multidisciplinary approach that incorporates primary care providers, pathologists, plastic surgeons, and infectious disease specialists.

Surgical outcomes in adults with purpura fulminans: a systematic review and patient-level meta-synthesis.

BACKGROUND: Cutaneous manifestations of purpura fulminans (PF) present many challenges for clinicians and surgeons. In a state of septic shock complicated by limb ischemia, surgical interventions are necessary to control the pathological cascade and improve patient outcomes. The objective of this article was to report etiologies and surgical outcomes associated with cutaneous manifestations in adults. METHODS: This systematic review and meta-analysis compared 190 adult patients with etiologies, signs and symptoms, and surgical outcomes associated with cutaneous manifestations of PF. The PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus databases were systematically and independently searched. Patient and clinical characteristics, surgical interventions, outcomes, and complications were recorded. RESULTS: Seventy-nine studies were eligible for the systematic review, and 77 were eligible for meta-analysis using Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) and Cochrane guidelines. A total of 71/190 (38%) cases reported surgical debridement. Fasciotomies were reported in 12/190 (6%) cases and 20 procedures. Amputations were reported in 154/190 (81%) cases. Reconstruction was reported in 45 cases. Skin grafts were applied in 31 cases. Flaps were used for reconstruction in 28 cases. Median (IQR) surgical procedures per patient were 4 (4, 5) procedures. Infectious organisms causing PF were 32% Neisseria meningitidis (n = 55) and 32% Streptococcus pneumonia (n = 55). Coagulase-negative Staphylococcus (95% confidence interval (CI)(8.2-177.9), p = 0.032), Haemophilus influenza (95%CI (7.2-133), p = 0.029), Streptococcus pneumonia (95% CI (13.3-75.9), p = 0.006), and West Nile Virus (95%CI (8.2-177.9), p = 0.032) were associated with significantly more extensive amputations compared to other organisms. CONCLUSION: This systematic review and patient-level meta-analysis found the most common presentation of PF was septic shock from an infectious organism. Neisseria meningitidis and Streptococcus pneumonia were equally the most common organisms associated with PF. The majority of cases were not treated in a burn center. The most common surgeries were amputations, with below-the-knee-amputations being the most common procedure. Skin grafting was the most commonly performed reconstructive procedure. The most common complications were secondary infections. Organisms with significantly more extensive amputations were coagulase-negative Staphylococcus, Haemophilus influenza, Streptococcus pneumonia, and West Nile Virus. Interpretation of findings should be cautioned due to limited sample data.

A Skin Rejection Grading System for Vascularized Composite Allotransplantation in a Preclinical Large Animal Model.

BACKGROUND: The Banff Criteria have been accepted as a system for grading histological rejection in graft skin in human vascularized composite allotransplantation (VCA). Preclinical swine hindlimb transplantation models have an important role in translational studies in VCA. However, unified grading criteria for rejection in swine skin have not yet been established. METHODS: Two hundred fourteen swine skin biopsy specimens were reviewed, including 88 native skin biopsies and 126 specimens from the skin component of heterotopic swine hindlimb transplants. Thorough review was performed in a blinded fashion by an expert veterinary pathologist with attention paid to the applicability of the Banff criteria as well as specific histologic characteristics and trends. Clinical and histopathologic rejection scores were then directly compared. RESULTS: Two hundred fourteen specimens reviewed showed significant similarities between swine and human skin, as previously published. Notable swine-specific characteristics, including paucicellular infiltration with rare epidermal cell infiltration or necrosis, were accounted for in a proposed grading system that parallels the Banff Criteria. CONCLUSIONS: This comprehensive grading system, based on the Banff Classification for skin rejection in VCA, provides a standardized system for more accurate comparison of rejection in preclinical swine VCA models.

International Medical Graduates in the US Plastic Surgery Residency: Characteristics of Successful Applicants.

Objectives: Within the United States, plastic surgery is a difficult field to match into for both US and international medical graduates. While the number of available residency positions has grown in recent years, this has not been mirrored by an equal increase in the number of international medical graduates who match. Furthermore, there are few reliable resources to guide international medical graduates who are interested in matching into US-based programs, so the process is often even more difficult and unpredictable than for US applicants. Methods: An anonymous survey was distributed electronically to international medical graduates who successfully matched into independent and integrated US plastic surgery residency programs. The survey assessed qualities such as medical school performance, test scores, research experience, and other relevant applicant information, and χ2 analysis was done to compare the survey results for integrated and independent track international medical graduates. Results: International medical graduates who successfully match tend to rank high and score well in their medical school classes, score between 230 and 250 on USMLE step 1 and 2CK tests, and have a mean of 2 years of research experience before applying to the match. International medical graduates in the independent track tend to have higher step 1 scores, whereas international medical graduates in the integrated track tend to have more research experience and additional nonmedical degrees. Conclusions: This is a survey-based overview that describes the characteristics of successfully matched international medical graduates. Limitations of this study include the inability to identify and survey the unsuccessful applicants as well as poor response rate of the successful candidates in the independent pathway who successfully matched.

Precision genome editing using synthesis-dependent repair of Cas9-induced DNA breaks.

The RNA-guided DNA endonuclease Cas9 has emerged as a powerful tool for genome engineering. Cas9 creates targeted double-stranded breaks (DSBs) in the genome. Knockin of specific mutations (precision genome editing) requires homology-directed repair (HDR) of the DSB by synthetic donor DNAs containing the desired edits, but HDR has been reported to be variably efficient. Here, we report that linear DNAs (single and double stranded) engage in a high-efficiency HDR mechanism that requires only ∼35 nucleotides of homology with the targeted locus to introduce edits ranging from 1 to 1,000 nucleotides. We demonstrate the utility of linear donors by introducing fluorescent protein tags in human cells and mouse embryos using PCR fragments. We find that repair is local, polarity sensitive, and prone to template switching, characteristics that are consistent with gene conversion by synthesis-dependent strand annealing. Our findings enable rational design of synthetic donor DNAs for efficient genome editing.

Structure-Based Design of an Iminoheterocyclic ß-Site Amyloid Precursor Protein Cleaving Enzyme (BACE) Inhibitor that Lowers Central Aß in Nonhuman Primates.

We describe successful efforts to optimize the in vivo profile and address off-target liabilities of a series of BACE1 inhibitors represented by 6 that embodies the recently validated fused pyrrolidine iminopyrimidinone scaffold. Employing structure-based design, truncation of the cyanophenyl group of 6 that binds in the S3 pocket of BACE1 followed by modification of the thienyl group in S1 was pursued. Optimization of the pyrimidine substituent that binds in the S2'-S2″ pocket of BACE1 remediated time-dependent CYP3A4 inhibition of earlier analogues in this series and imparted high BACE1 affinity. These efforts resulted in the discovery of difluorophenyl analogue 9 (MBi-4), which robustly lowered CSF and cortex Aß40 in both rats and cynomolgus monkeys following a single oral dose. Compound 9 represents a unique molecular shape among BACE inhibitors reported to potently lower central Aß in nonrodent preclinical species.

Design and validation of bicyclic iminopyrimidinones as beta amyloid cleaving enzyme-1 (BACE1) inhibitors: conformational constraint to favor a bioactive conformation.

On the basis of our observation that the biaryl substituent of iminopyrimidinone 7 must be in a pseudoaxial conformation to occupy the contiguous S1-S3 subsites of BACE1, we have designed a novel fused bicyclic iminopyrimidinone scaffold intended to favor this bioactive conformation. Strategic incorporation of a nitrogen atom in the new constrained ring allowed us to develop SAR around the S2' binding pocket and ultimately resulted in analogues with low nanomolar potency for BACE1. In particular, optimization of the prime side substituent led to major improvements in potency by displacement of two conserved water molecules from a region near S2'. Further optimization of the pharmacokinetic properties of this fused pyrrolidine series, in conjunction with facile access to a rat pharmacodynamic model, led to identification of compound 43, which is an orally active, brain penetrant inhibitor that reduces Aß(40) in the plasma, CSF, and cortex of rats in a dose-dependent manner.

Preladenant, a selective A(2A) receptor antagonist, is active in primate models of movement disorders.

Parkinson's Disease (PD) and Extrapyramidal Syndrome (EPS) are movement disorders that result from degeneration of the dopaminergic input to the striatum and chronic inhibition of striatal dopamine D(2) receptors by antipsychotics, respectively. Adenosine A(2A) receptors are selectively localized in the basal ganglia, primarily in the striatopallidal ("indirect") pathway, where they appear to operate in concert with D(2) receptors and have been suggested to drive striatopallidal output balance. In cases of dopaminergic hypofunction, A(2A) receptor activation contributes to the overdrive of the indirect pathway. A(2A) receptor antagonists, therefore, have the potential to restore this inhibitor imbalance. Consequently, A(2A) receptor antagonists have therapeutic potential in diseases of dopaminergic hypofunction such as PD and EPS. Targeting the A(2A) receptor may also be a way to avoid the issues associated with direct dopamine agonists. Recently, preladenant was identified as a potent and highly selective A(2A) receptor antagonist, and has produced a significant improvement in motor function in rodent models of PD. Here we investigate the effects of preladenant in two primate movement disorder models. In MPTP-treated cynomolgus monkeys, preladenant (1 or 3 mg/kg; PO) improved motor ability and did not evoke any dopaminergic-mediated dyskinetic or motor complications. In Cebus apella monkeys with a history of chronic haloperidol treatment, preladenant (0.3-3.0 mg/kg; PO) delayed the onset of EPS symptoms evoked by an acute haloperidol challenge. Collectively, these data support the use of preladenant for the treatment of PD and antipsychotic-induced movement disorders.

The effects of adenosine A2A receptor antagonists on haloperidol-induced movement disorders in primates.

RATIONALE: Adenosine and dopamine interact within the striatum to control striatopallidal output and globus pallidus GABA release. Manipulating striatal adenosine transmission via blockade of the A2A receptor subtype can compensate for the reduced dopamine activity within the striatum that underlies movement disorders such as antipsychotic-induced extrapyramidal syndrome (EPS) and Parkinson's disease (PD). Preclinical studies in the rat have demonstrated that adenosine A2A receptor antagonists can attenuate behaviors reflecting reduced dopamine activity, such as haloperidol-induced catalepsy and hypoactivity. OBJECTIVES: In the present studies using nonhuman primates, adenosine antagonists were tested against haloperidol-induced EPS in Cebus apella and haloperidol-induced catalepsy in Saimiri sciureus (squirrel monkey). Specifically, the A2A receptor antagonists, SCH 412348 (0.3-30 mg/kg PO) and KW-6002 (3-100 mg/kg PO); the A1/A2A receptor antagonist, caffeine (1-30 mg/kg PO and IM); and the A1 receptor antagonist, DPCPX (3-30 mg/kg PO) were tested in at least one of these models. RESULTS: SCH 412348 (10-30 mg/kg), KW-6002 (57-100 mg/kg), and caffeine (30 mg/kg) significantly increased the time to EPS onset. Additionally, SCH 412348, KW-6002, and caffeine afforded protection from the onset of EPS for at least 6 h in some of the primates. SCH 412348 (10 mg/kg) and caffeine (10 mg/kg) significantly reduced haloperidol-induced catalepsy. DPCPX produced a very slight attenuation of EPS at 30 mg/kg, but had no effect on catalepsy. CONCLUSIONS: These findings suggest that adenosine A2A receptor antagonists may represent an effective treatment for the motor impairments associated with both antipsychotic-induced EPS and PD.

The effect of caffeine to increase reaction time in the rat during a test of attention is mediated through antagonism of adenosine A2A receptors.

Caffeine produces effects on cognitive function particularly relating to aspects of attention such as reaction time. Considering the plasma exposure levels following regular caffeine intake, and the affinity of caffeine for known protein targets, these effects are likely mediated by either the adenosine A(1) or A(2A) receptor. In the present studies, two rat strains [Long-Evans (LE) and CD] were trained to asymptote performance in a test of selective attention, the 5-choice serial reaction time task (5-CSRTT). Next, the effects of caffeine were compared to the selective A(2A) antagonists, SCH 412348 and KW-6002 (Istradefylline), and the A(1) antagonist, DPCPX. Further studies compared the psychostimulant effects of each drug. Finally, we tested the A(2A) agonist, CGS-21680, on 5-CSRTT performance and given the antipsychotic potential of this drug class, studied the interaction between CGS-21680 and amphetamine in this task. Caffeine (3-10mg/kg IP) increased reaction time in both LE and CD rats, with no effect on accuracy, an effect replicated by SCH 412348 (0.1-1mg/kg PO) and KW-6002 (1-3mg/kg PO), but not DPCPX (3-30 mg/kg PO). At least with SCH 412348, these effects were at doses that were not overtly psychostimulant. In contrast, CGS-21680 (0.03-0. 3mg/kg IP) slowed reaction speed and increased omissions. Interestingly, at a comparatively low dose of 0.03 mg/kg, CGS-21680 attenuated the increased premature responding produced by amphetamine (1mg/kg IP). The present results suggest that the attention-enhancing effects of caffeine are mediated through A(2A) receptor blockade, and selective A(2A) receptor antagonists may have potential as therapies for attention-related disorders. Furthermore, the improvement in response control in amphetamine-treated rats following CGS-21680 pretreatment supports the view that A(2A) agonists have potential as novel antipsychotics.

The antinociceptive and anxiolytic-like effects of the metabotropic glutamate receptor 5 (mGluR5) antagonists, MPEP and MTEP, and the mGluR1 antagonist, LY456236, in rodents: a comparison of efficacy and side-effect profiles.

RATIONALE: Modulation of metabotropic glutamate receptor (mGluR) subtypes represents a novel approach for the treatment of neurological and psychiatric disorders. OBJECTIVES: This study was conducted to investigate the role of the mGluR5 and mGluR1 subtypes in the modulation of pain and anxiety. METHODS: The mGluR5 antagonists, 2-methyl-6-(phenylethynyl)pyridine (MPEP) and 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine (MTEP), and the mGluR1 antagonist, (4-methoxy-phenyl)-(6-methoxy-quinazolin-4-yl)-amine HCl (LY456236), were tested in models of pain [mouse formalin test, rat spinal nerve ligation (SNL)] and anxiety [Vogel conflict, conditioned lick suppression (CLS)], and their efficacious effects were compared to any associated side effects. RESULTS: The systemic administration of MPEP, MTEP, and LY456236 reduced hyperalgesia induced by formalin and mechanical allodynia following SNL. However, only LY456236 completely reversed the allodynia. In the anxiety models, MPEP (3--30 mg/kg), MTEP (3--10 mg/kg), and LY456236 (10--30 mg/kg) produced anxiolytic-like effects similar to the benzodiazepine, chlordiazepoxide (CDP, 6 mg/kg). However, only MPEP and MTEP were able to produce a level of anxiolysis comparable to CDP. In a series of tests examining potential side effects, MPEP and MTEP reduced body temperature and locomotor activity and impaired operant responding for food and rotarod performance at doses of 3--30 and 1--30 mg/kg, respectively. LY456236 reduced operant responding at 30 mg/kg. CONCLUSION: Both mGluR5 and mGluR1 antagonists are effective in models of pain and anxiety. However, an mGluR1 antagonist was more efficacious than the two mGluR5 antagonists in the pain models, which, conversely, appeared more efficacious in the anxiety models. These findings support the potential utility of mGluR5 and mGluR1 antagonists for both the treatment of chronic pain and as novel anxiolytics.