Leishmania major pseudoperoxidase (LmPP) is a recently discovered heme protein expressed by the human pathogen. Previous in vivo and in vitro studies suggest that LmPP is a crucial element of the pathogen's defense mechanism against the reactive nitrogen species peroxynitrite produced during the host immune response. To shed light on the potential mechanism of peroxynitrite detoxification, we have determined the 1.76-Å X-ray crystal structure of LmPP, revealing a striking degree of homology with heme peroxidases. The most outstanding structural feature is a Cys/His heme coordination, which corroborates previous spectroscopic and mutagenesis studies. We also used a combination of stopped-flow and electron paramagnetic spectroscopies that together suggest that peroxynitrite is not a substrate for LmPP catalysis, leaving the function of LmPP an open question.

Nitric oxide generated by bacterial nitric oxide synthase (NOS) increases the susceptibility of Gram-positive pathogens Staphylococcus aureus and Bacillus anthracis to oxidative stress, including antibiotic-induced oxidative stress. Not surprisingly, NOS inhibitors also improve the effectiveness of antimicrobials. Development of potent and selective bacterial NOS inhibitors is complicated by the high active site sequence and structural conservation shared with the mammalian NOS isoforms. To exploit bacterial NOS for the development of new therapeutics, recognition of alternative NOS surfaces and pharmacophores suitable for drug binding is required. Here, we report on a wide number of inhibitor-bound bacterial NOS crystal structures to identify several compounds that interact with surfaces unique to the bacterial NOS. Although binding studies indicate that these inhibitors weakly interact with the NOS active site, many of the inhibitors reported here provide a revised structural framework for the development of new antimicrobials that target bacterial NOS. In addition, mutagenesis studies reveal several key residues that unlock access to bacterial NOS surfaces that could provide the selectivity required to develop potent bacterial NOS inhibitors.

OBJECTIVE:Physician shadowing has become ubiquitous to the premedical experience. However, students without connections to a medical professional are oftentimes forced to reach out to physicians independently from a program. Subsequently, these inquiries may go unanswered as they oftentimes appear unsolicited. The primary goals in the design and development of our program were to increase access to a clinical observership experience at our academic institution utilizing resident physicians as primary supervisors. METHODS:In January 2017, the Educational Shadowing Program (ESP) was established at our institution wherein undergraduate students could shadow within the Pediatric Continuity Clinic (PCC) staffed by pediatric resident physicians. ESP undergraduates shadowed the residents as they performed their history taking and physical exams and as they presented their patients to the attending physicians. Between patient encounters, the students assisted the residents in their administrative work which was completed as needed. ESP students were surveyed at their first orientation meeting and during the final case conference. RESULTS:The pre-participation survey showed that none of the student participants strongly agreed to having a good understanding of what the job of a resident physician entails. By the end of their 30 weeks, the proportion of participants with a strongly perceived understanding increased significantly. The proportion of student respondents that strongly agreed with their understanding of the physician-patient interaction also improved significantly over the study period, from 33% to 78%. Seventy-two percent of the residents surveyed agreed or strongly agreed that they enjoyed having the undergraduates in the clinic, affirming the positive effects of the program on the resident physicians. Forty-five percent of residents agreed or strongly agreed that the undergraduates improved their workflow in the clinic. CONCLUSION:This study demonstrates that establishing an undergraduate shadowing program in a busy academic pediatric clinic that involves resident physicians can be an overall positive experience for all participants. Fostering premedical student interest in pediatric care and primary care can possibly lead to more physician commitment to these fields, potentially helping to alleviate impending physicians in these specialties.

OBJECTIVE: To evaluate the role of psychosocial well-being on perioperative pain and opioid use among patients with cleft lip and palate (CLP) undergoing alveolar bone grafting (ABG). DESIGN: Retrospective review. SETTING: Tertiary level craniofacial clinic. PARTICIPANTS: 34 patients with CLP (median age: 11.7 years), including 25 (73.5%) unilateral CLP and 9 (26.5%) bilateral CLP, who underwent ABG from 2015 to 2022. INTERVENTIONS: ABG using iliac crest bone graft. Patients were prospectively administered four patient-reported psychosocial instruments from the Patient-Reported Outcomes Measurement Information System. MAIN OUTCOME MEASURES: Perioperative opioid use in morphine equivalent dosage/kilogram, patient-reported pain scores, and length of hospital stay after ABG. RESULTS: Patient-reported anxiety (r = 0.41, p = 0.02) and depressive symptoms (r = 0.35, p = 0.04) correlated to higher perioperative opioid usage. Multivariable regression models including psychosocial scores, total acetaminophen usage, length of surgery, and other simultaneous surgeries were developed for total opioid usage, patient-reported pain, and length of hospital stay. Patient-reported anxiety was independently predictive of higher perioperative opioid use (β=0.36, p = 0.01) and higher pain scores (β=0.39, p = 0.02), but not length of hospital stay. CONCLUSIONS: We identified an association for patient-reported anxiety and perioperative opioid use and pain in a CLP cohort undergoing ABG. Future considerations in preoperative patient and family consultation may be indicated in patients self-reporting higher anxiety in an effort to minimize perioperative opioid usage.

Custom synthesis of extracellular matrix (ECM)-inspired materials for condition-specific reconstruction has emerged as a potentially translatable regenerative strategy. In skull defect reconstruction, nanoparticulate mineralized collagen glycosaminoglycan scaffolds (MC-GAG) have demonstrated osteogenic and anti-osteoclastogenic properties, culminating in the ability to partially heal in vivo skull defects without the addition of exogenous growth factors or progenitor cell loading. In an effort to reduce catabolism during early skull regeneration, we fabricated a composite material (MCGO) of MC-GAG and recombinant osteoprotegerin (OPG), an endogenous anti-osteoclastogenic decoy receptor. In the presence of differentiating osteoprogenitors, MCGO demonstrated an additive effect with endogenous OPG limited to the first 14 days of culture with total eluted and scaffold-bound OPG exceeding that of MC-GAG. Functionally, MCGO exhibited similar osteogenic properties as MC-GAG, however, MCGO significantly reduced maturation and resorptive activities of primary human osteoclasts. In a rabbit skull defect model, MCGO scaffold-reconstructed defects displayed higher mineralization as well as increased hardness and microfracture resistance compared to non-OPG functionalized MC-GAG scaffolds. The current work suggests that MCGO is a development in the goal of reaching a materials-based strategy for skull regeneration.

Bacterial infections associated with methicillin-resistant Staphylococcus aureus (MRSA) are a major economic burden to hospitals, and confer high rates of morbidity and mortality among those infected. Exploitation of novel therapeutic targets is thus necessary to combat this dangerous pathogen. Here, we report on the identification and characterization, including crystal structures, of two nitric oxide synthase (NOS) inhibitors that function as antimicrobials against MRSA. These data provide the first evidence that bacterial NOS (bNOS) inhibitors can work synergistically with oxidative stress to enhance MRSA killing. Crystal structures show that each inhibitor contacts an active site Ile residue in bNOS that is Val in the mammalian NOS isoforms. Mutagenesis studies show that the additional nonpolar contacts provided by the Ile in bNOS contribute to tighter binding toward the bacterial enzyme.

Bacterial infections associated with methicillin-resistant Staphylococcus aureus (MRSA) are a major economic burden to hospitals, and confer high rates of morbidity and mortality among those infected. Exploitation of novel therapeutic targets is thus necessary to combat this dangerous pathogen. Here, we report on the identification and characterization, including crystal structures, of two nitric oxide synthase (NOS) inhibitors that function as antimicrobials against MRSA. These data provide the first evidence that bacterial NOS (bNOS) inhibitors can work synergistically with oxidative stress to enhance MRSA killing. Crystal structures show that each inhibitor contacts an active site Ile residue in bNOS that is Val in the mammalian NOS isoforms. Mutagenesis studies show that the additional nonpolar contacts provided by the Ile in bNOS contribute to tighter binding toward the bacterial enzyme.