Modulators of nicotine reward and reinforcement.

Nicotine has been well-characterized for its ability to alter neurophysiology to promote rewarding and reinforcing properties. However, several exogenous chemicals possess properties that modulate or enhance nicotine's ability to alter neurophysiology. This chapter focuses on nicotine's impact on behavior through changes in neurophysiology and several chemical entities that in-turn modulate nicotine's ability to act as a neuromodulator.

Neuronal Excitability in the Medial Habenula and Ventral Tegmental Area Is Differentially Modulated by Nicotine Dosage and Menthol in a Sex-Specific Manner.

The medial habenula (MHb) has been identified as the limiting factor for nicotine intake and facilitating nicotine withdrawal. However, few studies have assessed MHb neuronal excitability in response to nicotine, and, currently, a gap in knowledge is present for finding behavioral correlates to neuronal excitability in the region. Moreover, no study to date has evaluated sex or nicotine dosage as factors of excitability in the MHb. Here, we utilized an e-vape self-administration (EVSA) model to determine differences between sexes with different nicotine dosages ± menthol. Following this paradigm, we employed patch-clamp electrophysiology to assess key metrics of MHb neuronal excitability in relation to behavioral endpoints. We observed female mice self-administered significantly more than males, regardless of dosage. We also observed a direct correlation between self-administration behavior and MHb excitability with low-dose nicotine + menthol in males. Conversely, a high dose of nicotine ± menthol yields an inverse correlation between excitability and self-administration behavior in males only. In addition, intrinsic excitability in the ventral tegmental area (VTA) does not track with the amount of nicotine self-administered. Rather, they correlate to the active/inactive discrimination of mice. Using fast-scan cyclic voltammetry, we also observed that dopamine release dynamics are linked to reinforcement-related behavior in males and motivation-related behaviors in females. These results point to a sex-specific difference in the activity of the MHb and VTA leading to distinct differences in self-administration behavior. His could lend evidence to clinical observations of smoking and nicotine-use behavior differing between males and females.

A technique for introducing broad-spectrum topical antibiotics during open reduction and internal fixation of acetabular fractures.

Postoperative surgical site infections remain a significant and prevalent complication after open reduction and internal fixation of acetabular fractures. Local antibiotics have been shown to decrease risk of postoperative infection, although recent evidence is conflicting. We provide a consistent and replicable technique for delivering intraoperative broad-spectrum antibiotics in the form of a putty applied directly to surgical implants. With this technique, systemic levels of those antibiotics remain safe and stable.

The Impact of High or Low Doses of Nicotine in a Mouse Model of Vapor Self-Administration.

INTRODUCTION: A wide variety of nicotine concentrations and formulations are available to users of electronic nicotine delivery systems (ENDS). This is increasingly true when considering the many flavors available with ENDS products. To date, there have been few preclinical investigations into the impact of nicotine doses, with and without flavors, on vaping-related behaviors. This present study evaluated how nicotine concentrations relevant to tank-based and pod-based ENDS, with and without flavors, impact reinforcement-related behavior in a mouse model. AIMS AND METHODS: Adult male and female C57/BL6J mice were used in vapor-inhalation self-administration assays. Mice were assigned e-liquids containing 6 mg/mL or 60 mg/mL nicotine. Additional mice were assigned these nicotine doses with green apple or menthol flavorants. Mice were trained on fixed-ratio 1 for 10, 2-hour sessions, then five sessions at FR3, three progressive ratio sessions, and two FR3 sessions. RESULTS: We observed male mice exhibited higher reinforcement-related behavior to menthol-flavored 6 mg/mL nicotine when compared to female mice. Males were only observed to have a menthol-induced enhancement of self-administration at 6 mg/mL nicotine and not 60 mg/mL nicotine. However, female mice exhibited significant menthol-induced increases in reinforcement-related behaviors with 60 mg/mL nicotine. CONCLUSIONS: These data provide evidence that males and females exhibit different dose sensitivities to nicotine. These sex-dependent differences in nicotine sensitivity also indicate that flavor-induced enhancement in nicotine intake is dependent on the different doses for each sex. IMPLICATIONS: There has been much discussion recently regarding the impact of flavors on vaping-related behavior. Our current study may support prior investigations that suggest flavors enhance the palatability of nicotine-containing products. However, this current study provides evidence that males and females exhibit different sensitivities to nicotine.

Bicondylar Tibial Plateau Fractures: What Predicts Infection?

OBJECTIVES: The purpose of this study was to identify the patient, injury, and treatment factors associated with infection of bicondylar plateau fractures and to evaluate whether center variation exists. DESIGN: Retrospective review. SETTING: Eighteen academic trauma centers. PATIENTS/PARTICIPANTS: A total of 1,287 patients with 1,297 OTA type 41-C bicondylar tibia plateau fractures who underwent open reduction and internal fixation were included. Exclusion criteria were follow-up less than 120 days, insufficient documentation, and definitive treatment only with external fixation. INTERVENTION: Open reduction and internal fixation. MAIN OUTCOME MEASUREMENTS: Superficial and deep infection. RESULTS: One hundred one patients (7.8%) developed an infection. In multivariate regression analysis, diabetes (DM) (OR [odds ratio] 3.24; P ≤ 0.001), alcohol abuse (EtOH) (OR 1.8; P = 0.040), dual plating (OR 1.8; P ≤ 0.001), and temporary external fixation (OR 2.07; P = 0.013) were associated with infection. In a risk-adjusted model, we found center variation in infection rates (P = 0.030). DISCUSSION: In a large series of patients undergoing open reduction and internal fixation of bicondylar plateau fractures, the infection rate was 7.8%. Infection was associated with DM, EtOH, combined dual plating, and temporary external fixation. Center expertise may also play a role because one center had a statistically lower rate and two trended toward higher rates after adjusting for confounders. LEVEL OF EVIDENCE: Level IV-Therapeutic retrospective cohort study.

Open Reduction and Internal Fixation of a Partial Articular (OTA-43B) Pilon Fracture Through a Direct Anterior Approach.

SUMMARY: We present the management of an OTA-43B Pilon fracture with a depressed plafond fragment, medial comminution, and displacement of the Chaput fragment. The patient was initially managed with external fixation to gain initial reduction of the pilon fracture and to allow the soft tissues to heal. As demonstrated, the extensile anterior approach can be modified and used to see the anteromedial and anterolateral tibial plafond so an anatomic reduction could be obtained. Also detailed is the reduction and fixation strategy and soft tissue closure, all of which plays a critical role in the outcome.

The Effects of Rosiglitazone on Task Specific Anxiety-Like Behavior and Novelty Seeking in a Model of Chronic Adolescent Unpredictable Stress.

Adolescence is characterized as a period of increased social behavior, risk taking, and novelty seeking, partly due to ongoing maturation in critical brain areas and the hypothalamic-pituitary-adrenal (HPA) negative-feedback system. During this period there is heightened vulnerability to stress that can drive neuro-immune-endocrine remodeling, resulting in the emergence of maladaptive behaviors that increase susceptibility to alcohol and substance abuse. Here we used a rat model to investigate the impact of chronic adolescent unpredictable stress on a battery of behavioral measures to assess anxiety, novelty seeking, risk taking, depression, and voluntary ethanol consumption while determining whether the PPARγ agonist rosiglitazone can attenuate these effects. Adolescent female rats that experienced stress showed increased risk taking behavior and novelty seeking behavior with no change in ethanol consumption. The administration of rosiglitazone during stress induction attenuated stress-induced cortisol elevation, normalized risk taking behavior in a model anxiety, and attenuated novelty seeking in a task-specific manner. Depressive-like behavior was not impacted by adolescent unpredictable stress or the administration of rosiglitazone. The results from this study demonstrate that exposure to unpredictable stress during adolescence increases the prevalence of maladaptive behaviors that are known to increase susceptibility to alcohol and substance abuse, and that rosiglitazone may be an effective therapeutic to attenuate the emergence of select risk taking and novelty seeking behaviors in females.

Proximal tibia fracture dislocations: Management and outcomes of a severe and under-recognized injury.

INTRODUCTION: Proximal tibia fracture dislocations (PTFDs) are a subset of plateau fractures with little in the literature since description by Hohl (1967) and classification by Moore (1981). We sought to evaluate reliability in diagnosis of fracture-dislocations by traumatologists and to compare their outcomes with bicondylar tibial plateau fractures (BTPFs). METHODS: This was a retrospective cohort study at 14 level 1 trauma centers throughout North America. In all, 4771 proximal tibia fractures were reviewed by all sites and 278 possible PTFDs were identified using the Moore classification. These were reviewed by an adjudication board of three traumatologists to obtain consensus. Outcomes included inter-rater reliability of PTFD diagnosis, wound complications, malunion, range of motion (ROM), and knee pain limiting function. These were compared to BTPF data from a previous study. RESULTS: Of 278 submitted cases, 187 were deemed PTFDs representing 4% of all proximal tibia fractures reviewed and 67% of those submitted. Inter-rater agreement by the adjudication board was good (83%). Sixty-one PTFDs (33%) were unicondylar. Eleven (6%) had ligamentous repair and 72 (39%) had meniscal repair. Two required vascular repair. Infection was more common among PTFDs than BTPFs (14% vs 9%, p = 0.038). Malunion occurred in 25% of PTFDs. ROM was worse among PTFDs, although likely not clinically significant. Knee pain limited function at final follow-up in 24% of both cohorts. CONCLUSIONS: PTFDs represent 4% of proximal tibia fractures. They are often unicondylar and may go unrecognized. Malunion is common, and PTFD outcomes may be worse than bicondylar fractures.

The Modified Eden-Lange Tendon Transfer for Lateral Scapular Winging Secondary to Spinal Accessory Nerve Injury.

Trapezius paralysis following injury to the spinal accessory nerve can be a debilitating complication resulting from lymph node biopsy, radical neck dissection, or penetrating trauma in the region of the posterior cervical triangle. Disruption of the delicate muscular balance in the shoulder girdle may result in lateral scapular winging, ipsilateral upper extremity radiculopathy, and limited shoulder function and range of motion. Spontaneous recovery with nonoperative management is possible in some patients, and restoration of function after reparative neural procedures has been observed in patients undergoing timely repair. However, extended delays from the time of injury to surgery are common and may necessitate various muscle transfers to reestablish the complex biomechanics and balance of the shoulder girdle. We describe a modification to the classic Eden-Lange procedure with lateral transfer of the levator scapulae and rhomboid minor to the scapula spine and rhomboid major transfer with a small wafer of bone to the scapula body for chronic lateral winging of the scapula following injury to the spinal accessory nerve as the result of a cervical lymph node biopsy.

Management of Complex Anterior Shoulder Instability: a Case-Based Approach.

PURPOSE OF THE REVIEW: The goal of this review is to provide a guide on surgical decision-making options for complex anterior shoulder instability using a case-based approach. RECENT FINDINGS: Arthroscopic Bankart repair is well documented for having successful outcomes in patients with isolated labral tear involvement with minimal bone loss. Latarjet is a generally accepted procedure in patients with 20-30% glenoid bone loss. When bone loss exceeds that which cannot be managed through Latarjet, a range of options exist and are highly dependent upon the extent of osseous deficiency on both the glenoid and humeral sides, surgeon experience, and patient-specific factors. The use of reverse total shoulder arthroplasty for the management of chronic locked shoulder dislocations has been described as a successful management option. Treatment options for complex anterior shoulder instability range widely based on patients' presenting exam, surgical history, amount of glenoid bone loss, size of Hill-Sachs lesion, and surgeon preference. When selecting the appropriate surgical intervention, the treating surgeon must consider the patient history, physical exam, and preoperative imaging along with patient expectations.

Idiopathic Transverse Myelitis Mimicking an Intramedullary Spinal Cord Tumor.

The differential diagnoses for spinal cord lesions include spinal tumors and inflammatory processes. The distinction between these pathologies can be difficult if solely based on imaging. We report for the first time to our knowledge a case of idiopathic transverse myelitis (ITM) mimicking a discrete cervical spinal lesion in a 66-year-old man who presented with gait instability and neck pain. The patient's symptoms failed to resolve after an initial course of steroid therapy. Surgical biopsy confirmed the diagnosis of ITM. Subsequent treatment with dexamethasone resulted in complete resolution of the symptoms as well as the intramedullary enhancement. ITM is most common in the cervical and thoracic spine, spanning 3-4 spinal segments. It usually occupies more than 50% of the cross-sectional area of the spinal cord and tends to be central, uniform, and symmetric. It exhibits patchy and peripheral contrast enhancement. These criteria are useful guidelines that help distinguish ITM from neoplastic spinal lesions. A decision to perform biopsy must take into consideration the patient's clinical symptoms, the rate of progression of neurological deficits, and the imaging characteristics of the lesion. Surgical biopsy for questionable lesions should be reserved for patients with progressive neurological deficits refractory to empirical medical therapy.

Plant phloem sterol content: forms, putative functions, and implications for phloem-feeding insects.

All eukaryotes contain sterols, which serve as structural components in cell membranes, and as precursors for important hormones. Plant vegetative tissues are known to contain mixtures of sterols, but very little is known about the sterol composition of phloem. Plants are food for many animals, but plant-feeding arthropods (including phloem-feeding insets) are unique among animals in that they have lost the ability to synthesize sterols, and must therefore acquire these essential nutrients from their food, or via endosymbionts. Our paper starts by providing a very brief overview of variation in plant sterol content, and how different sterols can affect insect herbivores, including those specializing on phloem. We then describe an experiment, where we bulk collected phloem sap exudate from bean and tobacco, and analyzed its sterol content. This approach revealed two significant observations concerning phloem sterols. First, the phloem exudate from each plant was found to contain sterols in three different fractions - free sterols, sterols conjugated to lipids (acylated), and sterols conjugated to carbohydrates (glycosylated). Second, for both plants, cholesterol was identified as the dominant sterol in each phloem exudate fraction; the remaining sterols in each fraction were a mixture of common phytosterols. We discuss our phloem exudate sterol profiles in a plant physiology/biochemistry context, and how it relates to the nutritional physiology/ecology of phloem-feeding insects. We close by proposing important next steps that will advance our knowledge concerning plant phloem sterol biology, and how phloem-sterol content might affect phloem-feeding insects.