Adhesion of Crithidia fasciculata promotes a rapid change in developmental fate driven by cAMP signaling.

Trypanosomatids are single-celled parasites responsible for human and animal disease. Typically, colonization of an insect host is required for transmission. Stable attachment of parasites to insect tissues via their single flagellum coincides with differentiation and morphological changes. Although attachment is a conserved stage in trypanosomatid life cycles, the molecular mechanisms are not well understood. To study this process, we elaborate upon an in vitro model in which the swimming form of the trypanosomatid Crithidia fasciculata rapidly differentiates following adhesion to artificial substrates. Live imaging of cells transitioning from swimming to attached shows parasites undergoing a defined sequence of events, including an initial adhesion near the base of the flagellum immediately followed by flagellar shortening, cell rounding, and the formation of a hemidesmosome-like attachment plaque between the tip of the shortened flagellum and the substrate. Quantitative proteomics of swimming versus attached parasites suggests differential regulation of cyclic adenosine monophosphate (cAMP)-based signaling proteins. We have localized two of these proteins to the flagellum of swimming C. fasciculata; however, both are absent from the shortened flagellum of attached cells. Pharmacological inhibition of cAMP phosphodiesterases increased cAMP levels in the cell and prevented attachment. Further, treatment with inhibitor did not affect the growth rate of either swimming or established attached cells, indicating that its effect is limited to a critical window during the early stages of adhesion. These data suggest that cAMP signaling is required for attachment of C. fasciculata and that flagellar signaling domains may be reorganized during differentiation and attachment.IMPORTANCETrypanosomatid parasites cause significant disease burden worldwide and require insect vectors for transmission. In the insect, parasites attach to tissues, sometimes dividing as attached cells or producing motile, infectious forms. The significance and cellular mechanisms of attachment are relatively unexplored. Here, we exploit a model trypanosomatid that attaches robustly to artificial surfaces to better understand this process. This attachment recapitulates that observed in vivo and can be used to define the stages and morphological features of attachment as well as conditions that impact attachment efficiency. We have identified proteins that are enriched in either swimming or attached parasites, supporting a role for the cyclic AMP signaling pathway in the transition from swimming to attached. As this pathway has already been implicated in environmental sensing and developmental transitions in trypanosomatids, our data provide new insights into activities required for parasite survival in their insect hosts.

Transcriptional control of the Cryptosporidium life cycle.

The parasite Cryptosporidium is a leading agent of diarrhoeal disease in young children, and a cause and consequence of chronic malnutrition1,2. There are no vaccines and only limited treatment options3. The parasite infects enterocytes, in which it engages in asexual and sexual replication4, both of which are essential to continued infection and transmission. However, their molecular mechanisms remain largely unclear5. Here we use single-cell RNA sequencing to reveal the gene expression programme of the entire Cryptosporidium parvum life cycle in culture and in infected animals. Diverging from the prevailing model6, we find support for only three intracellular stages: asexual type-I meronts, male gamonts and female gametes. We reveal a highly organized program for the assembly of components at each stage. Dissecting the underlying regulatory network, we identify the transcription factor Myb-M as the earliest determinant of male fate, in an organism that lacks genetic sex determination. Conditional expression of this factor overrides the developmental program and induces widespread maleness, while conditional deletion ablates male development. Both have a profound impact on the infection. A large set of stage-specific genes now provides the opportunity to understand, engineer and disrupt parasite sex and life cycle progression to advance the development of vaccines and treatments.

DO seniors and IMGs have lower match probabilities than MD seniors after adjusting for specialty choice and USMLE Step 1 score.

CONTEXT: It is unknown if US residency applicants of different educational backgrounds (US allopathic [MD], Doctor of Osteopathic Medicine [DO], and international medical graduates [IMG]) but comparable academic performance have similar match success. OBJECTIVES: Our objective was to compare match probabilities between applicant types after adjusting for specialty choice and United States Medical Licensing Examination (USMLE) Step 1 scores. METHODS: We performed a secondary analysis of published data in National Resident Matching Program (NRMP) reports from 2016, 2018, 2020, and 2022 for US MD seniors, DO seniors, and IMGs (US citizens and non-US citizens). We examined the 10 specialties with the most available spots in 2022. Average marginal effects from a multiple variable logistic regression model were utilized to estimate each non-MD senior applicant type's probability of matching into their preferred specialty compared to MD seniors adjusting for specialty choice, Step 1 score, and match year. RESULTS: Each non-MD applicant type had a lower adjusted percent difference in matching to their preferred specialty than MD seniors, -7.1 % (95 % confidence interval [CI], -11.3 to -2.9) for DO seniors, -45.6 % (-50.6 to -40.5) for US IMGs, and -56.6 % (-61.5 to -51.6) for non-US IMGs. Similarly, each non-MD applicant type had a lower adjusted percent difference in matching than MD seniors across almost all Step 1 score ranges, except for DO seniors with Step 1 scores <200 (-2.0 % [-9.5 to 5.5]). CONCLUSIONS: After adjusting for specialty choice, Step 1 score, and match year, non-US MD applicants had lower probabilities of matching into their preferred specialties than their US MD colleagues.

Blood Culture-Negative Endocarditis Secondary to Skin Popping.

Infectious endocarditis (IE) is a diagnosis in which thorough evaluation must be performed and certain diagnostic criteria must be met. Thorough history and detailed physical examination can affect and guide the management of a patient from the very beginning. One of the main causes of endocarditis that physicians deal with in the hospital is intravenous drug abuse. This case report is of a 29-year-old male presenting to a rural emergency department with a two-week history of altered mental status after being struck on the head with a metal pipe. The patient also endorsed using intravenous drugs along with subcutaneous injections (skin popping). The patient was initially treated as a traumatic intracranial hemorrhage, but it was later found to be secondary to septic emboli from blood culture-negative endocarditis. Throughout this case report, we will approach the difficulties of diagnosing IE in a patient who represented many of the less common findings including dermatologic manifestations of diseases such as Osler nodes and Janeway lesions.

Management of Massive Rivaroxaban Overdose With Acetaminophen and Isosorbide Mononitrate Overdose.

Direct oral anticoagulants (DOACs) have been used more frequently for the prevention and management of thromboembolic disease in comparison to their predecessors. DOACs provide greater ease of administration, shorter half-lives, less monitoring, and fewer drug-drug interactions. With the rise of DOACs such as rivaroxaban, the opportunity for abuse also increases. Therefore, standardization of care based on rivaroxaban misuse must also be explored, an area in which there is not ample information. We present a case where a patient consumed a stockpile of her home medications in hopes to commit suicide. A 64-year-old female presented to the emergency department due to the ingestion of rivaroxaban 5,000 mg along with ingestion of acetaminophen 30,000 mg and isosorbide mononitrate 1000 mg in the setting of intentional self-harm with multiple declarations of being classified as Do Not Resuscitate. There have been documented cases of rivaroxaban overdose, however, there are no documented cases with levels of ingestion reaching 5,000 mg along with signs of severe bleeding. Our case study reviews the previously documented management of rivaroxaban abuse and the treatment that was given to our patient in the setting of extreme anticoagulant ingestion.

Risk Factors and Characteristics of Intraoperative Seizures During Awake Craniotomy: A Retrospective Cohort Study of 562 Consecutive Patients With a Space-occupying Brain Lesion.

INTRODUCTION: Intraoperative seizures (IOSs) during awake craniotomy (AC) are associated with significant morbidity. The reported incidence of IOS is between 3% and 30%. The aim of this study was to identify risk factors for IOS during AC for elective resection or biopsy of a space-occupying brain lesion. METHODS: In this retrospective study, we reviewed the records of all awake craniotomies performed by a single neurosurgeon at a single university hospital between July 2006 and December 2018. IOS was defined as a clinically apparent seizure that occurred in the operating room and was documented in the medical records. Explanatory variables were chosen based on previously published literature on risk factors for IOS. RESULTS: Five hundred and sixty-two patients had a total of 607 AC procedures during the study period; 581 cases with complete anesthesia records were included in analysis. Twenty-nine (5.0%) IOS events were reported during 29 (5%) awake craniotomies. Most seizures (27/29; 93%) were focal in nature and did not limit planned intraoperative stimulation mapping. Variables associated with IOS at a univariate P -value <0.1 (frontal location of tumor, preoperative radiotherapy, preoperative use of antiepileptic drugs, intraoperative use of dexmedetomidine, and intraoperative stimulation mapping) were included in a multivariable logistic regression. Frontal location of tumor (adjusted odds ratio: 5.68, 95% confidence interval: 2.11-15.30) and intraoperative dexmedetomidine use (adjusted odds ratio: 2.724, 95% confidence interval: 1.24-6.00) were independently associated with IOS in the multivariable analysis. CONCLUSIONS: This study identified a low incidence (5%) of IOS during AC. The association between dexmedetomidine and IOS should be further studied in randomized trials as this is a modifiable risk factor.

Benzodiazepine Sedation and Postoperative Neurological Deficits after Awake Craniotomy for Brain Tumor - An Exploratory Retrospective Cohort Study.

An awake craniotomy is a common neurosurgical procedure for excising brain tumor(s) located near or in eloquent areas. The use of benzodiazepine (BZD) for sedation in some patients with neuropathological conditions (e.g., stroke, brain tumors) has been previously linked with re-appearance of neurological deficits including limb incoordination, ataxia, and motor weakness, resulting in complications for the patient along with procedural challenges. Whether or not these findings can be extrapolated to patients undergoing brain tumor resection is largely unknown. The current work primarily sought to compare neurological outcome(s) in the immediate postoperative period between BZD-free and BZD-based sedation techniques in patients undergoing awake craniotomy. Using a database composed of awake craniotomies conducted within a single center and by a single surgeon, patients were retrospectively classified based on midazolam administration into BZD-free sedation (n=125) and BZD-based sedation (n=416) groups. Patients from each group were matched based on age, sex, tumor location, tumor grade, preoperative neurological deficits, non-operative BZD use, and Karnofsky Performance Scale scores, resulting in 108 patients within each group. Postoperative neurological deficits were recorded. Logistic regression analyses were conducted comparing postoperative neurological deficits between the matched groups. Postoperative neurological deficits were more prevalent within the BZD-based sedation group compared to the BZD-free sedation group (adjusted odds ratio (aOR)=1.903, 95% CI=1.018-3.560, p=0.044). In addition, subgroup analysis of the matched cohort showed a relationship between preoperative neurological symptoms and postoperative neurological deficits in the BZD-based sedation group (aOR=3.756, 95% CI=1.390-10.147, p=0.009). Our findings support the notion that the increased incidence of postoperative neurological deficits with BZD sedation may in part be related to the unmasking of preoperative neurological deficits. Further studies are required to confirm this phenomenon.

Management of Acute Ischemic Stroke in the Interventional Neuroradiology Suite During the COVID-19 Pandemic: A Global Survey.

BACKGROUND: According to early reports, patients affected by coronavirus disease 2019 (COVID-19) are at an increased risk of developing cerebrovascular events, including acute ischemic stroke (AIS). The COVID-19 pandemic may also impose difficulties in managing AIS patients undergoing endovascular thrombectomy (EVT), as well as concerns for the safety of health care providers. This international global survey aims to gather and summarize information from tertiary care stroke centers on periprocedural pathways and endovascular management of AIS patients during the COVID-19 pandemic. METHODS: A cross-sectional survey-based research questionnaire was sent to 259 tertiary care stroke centers with neurointerventional facilities worldwide. RESULTS: We received 114 responses (response rate: 44%) from 25 different countries across all 5 continents. The number of AIS patients and EVT cases were reported to have decreased during the pandemic. Most participants reported conducting COVID-19 testing before (49%) or after the procedure (31%); 20% of centers did not test at all. Only 16% of participating centers reported using a negative pressure room for the thrombectomy procedure. Strikingly, 50% of participating centers reported no changes in the anesthetic management of AIS patients undergoing EVT during the pandemic. CONCLUSIONS: This global survey provides information on the challenges in managing AIS patients undergoing EVT during the COVID-19 pandemic. Its findings can be used to improve patient outcomes and the safety of the health care team worldwide.

Mosquito heat seeking is driven by an ancestral cooling receptor.

Mosquitoes transmit pathogens that kill >700,000 people annually. These insects use body heat to locate and feed on warm-blooded hosts, but the molecular basis of such behavior is unknown. Here, we identify ionotropic receptor IR21a, a receptor conserved throughout insects, as a key mediator of heat seeking in the malaria vector Anopheles gambiae Although Ir21a mediates heat avoidance in Drosophila, we find it drives heat seeking and heat-stimulated blood feeding in Anopheles At a cellular level, Ir21a is essential for the detection of cooling, suggesting that during evolution mosquito heat seeking relied on cooling-mediated repulsion. Our data indicate that the evolution of blood feeding in Anopheles involves repurposing an ancestral thermoreceptor from non-blood-feeding Diptera.