Cholinergic Neurons of the Medial Septum Are Crucial for Sensorimotor Gating.

Hypofunction of NMDA receptors has been considered a possible cause for the pathophysiology of schizophrenia. More recently, indirect ways to regulate NMDA that would be less disruptive have been proposed and metabotropic glutamate receptor subtype 5 (mGluR5) represents one such candidate. To characterize the cell populations involved, we demonstrated here that knock-out (KO) of mGluR5 in cholinergic, but not glutamatergic or parvalbumin (PV)-positive GABAergic, neurons reduced prepulse inhibition of the startle response (PPI) and enhanced sensitivity to MK801-induced locomotor activity. Inhibition of cholinergic neurons in the medial septum by DREADD (designer receptors exclusively activated by designer drugs) resulted in reduced PPI further demonstrating the importance of these neurons in sensorimotor gating. Volume imaging and quantification were used to compare PV and cholinergic cell distribution, density, and total cell counts in the different cell-type-specific KO lines. Electrophysiological studies showed reduced NMDA receptor-mediated currents in cholinergic neurons of the medial septum in mGluR5 KO mice. These results obtained from male and female mice indicate that cholinergic neurons in the medial septum represent a key cell type involved in sensorimotor gating and are relevant to pathologies associated with disrupted sensorimotor gating such as schizophrenia.SIGNIFICANCE STATEMENT The mechanistic complexity underlying psychiatric disorders remains a major challenge that is hindering the drug discovery process. Here, we generated genetically modified mouse lines to better characterize the involvement of the receptor mGluR5 in the fine-tuning of NMDA receptors, specifically in the context of sensorimotor gating. We evaluated the importance of knocking-out mGluR5 in three different cell types in two brain regions and performed different sets of experiments including behavioral testing and electrophysiological recordings. We demonstrated that cholinergic neurons in the medial septum represent a key cell-type involved in sensorimotor gating. We are proposing that pathologies associated with disrupted sensorimotor gating, such as with schizophrenia, could benefit from further evaluating strategies to modulate specifically cholinergic neurons in the medial septum.

Disease-State Understanding and Experience of Patients Receiving Continuous Intravenous Inotropic Support as Palliative Therapy: A Multicenter Survey.

Background: The use of continuous intravenous inotropic support (CIIS) as palliative therapy in patients with advanced heart failure (HF) has increased over the past decade. CIIS improves New York Heart Association (NYHA) functional class but does not impact survival. Objective: The objective of this study was to examine patients' understanding of the therapeutic intent of CIIS, prognostic awareness, and quality of life with CIIS. Design: We conducted a prospective, cross-sectional, multicenter study of patients with advanced HF receiving CIIS as palliative therapy between 2020 and 2022. Settings/Subjects: An investigator-developed survey instrument was administered to outpatients on CIIS in the United States via telephone. Measurements: Survey data were analyzed using descriptive and inferential statistics. Results: Forty-eight patients, 63% male, 81% African American/Black, with a mean age of 68.9 (standard deviation 12.3) years, participated in this study. The majority of patients responded that they expected CIIS to make them feel better (79%) and increase longevity (75%), but few expected that CIIS would cure their HF (19%). Patients described their overall quality of life on CIIS as not better/worse (19%), somewhat better (46%), and significantly better (35%) and reported high treatment satisfaction (87% were at least somewhat satisfied). Conclusions: In this study, patients report improved quality of life with CIIS as palliative therapy. Patients on CIIS as palliative therapy expected increased survival on CIIS, which is incongruent with current evidence. Further studies on how we can improve care processes so that patients have accurate prognostic and disease-state awareness, and receive goal concordant care, are warranted.

A Pilot Study to Understand the Role of Medical Humanities in Medical Education.

Over the past 20 years, the number of colleges offering programs in medical humanities has increased, and through the Medical Humanities Initiative at Georgetown University, this pilot study sought to understand students perceived benefits of a medical humanities curriculum. Based on a qualitative thematic analysis of free-response survey reflections from students enrolled in three unique medical humanities courses, six themes emerged. The themes help capture the role that a medical humanities education can play in shaping future clinicians and demonstrate that these courses not only provided a distinct teaching methodology from the scientific classroom but also appeared to deepen the students' understanding of the humanistic aspects of medicine and its many facets.

Risk-reducing surgery in PALB2 mutations carriers with breast cancer: a case series and literature review.

Background: Inherited germline mutations in PALB2 are known to predispose patients to a higher risk of breast, ovarian and pancreatic cancer with an estimated risk of developing breast cancer in over half of all affected women by age 80 years. Current guidelines for screening patients with PALB2 mutations include annual mammograms beginning at age 30 years and consideration of breast magnetic resonance imaging (MRI) and tomosynthesis. Existing evidence regarding risk-reducing surgery with mastectomy is insufficient to make a definitive recommendation to patients. In this case series, we describe the presentation and management of 5 patients with unilateral breast cancer and PALB2 mutations. To our knowledge, this is the first reported case series discussing the role of contralateral risk-reducing mastectomy (CRRM) in breast cancer patients with PALB2 mutations. The aim of our study was to evaluate the challenges in managing breast cancer risk in patients with PALB2 pathogenic variants with illustration through real-world clinical cases and a review of the literature. Methods: In this retrospective observational study, we present 5 patients with PALB2 mutations between the ages of 29 and 61 years who were diagnosed with breast cancer and underwent surgical management of their breast cancer at our institution between November 2020 and March 2022. Through their clinical courses and a literature review, we discuss the role of CRRM in breast cancer patients with PALB2 gene mutations. Results: Out of the 5 patients, 3 patients underwent CRRM and 2 patients chose unilateral surgery for their breast cancer and active surveillance for the contralateral breast. Of the 3 patients who underwent CRRM, 1 patient experienced a surgical complication from reconstruction on the prophylactic side. None of the patients developed any recurrences with an average length of follow up of 15.4 months. Conclusions: Based on our experience and the currently available literature, CRRM in patients with a PALB2 mutation should be performed on a case-by-case basis through a shared decision-making process taking into consideration overall risk, family history, patient preference and quality of life.