Casting shadows of perception: An exploration of visual hallucinations.

ABSTRACT: Hallucinations can be caused by biological, psychological, neurological, ophthalmological, and environmental factors. This article discusses a selection of the various conditions that can present with visual disturbances and hallucinations including schizophrenia, HIV, neurosyphilis, hyperammonemia, migraine, substance use, brain tumors, sleep disturbances, thyroid disorders, delirium, ophthalmologic conditions, and Lewy body dementia, providing an overview of the differential diagnosis of visual hallucinations. The mechanisms by which these conditions can lead to hallucinations are also discussed, and insight into the recommended medical workup for each is provided.

Relative value units in health care: Friend, foe, or necessary evil?

The purpose of this article is to describe this use of relative value units (RVUs) among nurse practitioners (NP), including the challenges NPs may experience. Relative value units were developed as a means to determine reimbursement for health care based on time spent with the patient and skills required to complete the interaction, while addressing any disparities of reimbursement based on geography or insurance. Increasingly, providers such as NPs are being evaluated based in large part on how many RVUs they generate, which seems to prioritize productivity and may overlook many nonbillable aspects of the NP role such as emotional support or patient education. Nurse practitioners working in settings that require more invasive procedures may seem to be more productive on paper, regardless of the number of patients seen. Relative value units may not adequately reflect the skill and time taken to care for patients with chronic illness. Gender differences have been noted, both in terms of the number of RVUs generated for care of male or female patients, and those generated by male or female providers. If NPs are evaluated primarily based on productivity as measured by RVUs, we must consider how this might minimize or even invalidate the therapeutic relationship and holistic approach to patient care. Relative value units may negatively affect the willingness of NPs to serve as preceptors. Finally, as NPs experience less face-to-face time with patients and more demands for productivity, there may be a loss of quality care and professional integrity, which raises the risk of burnout among NPs.

Implications and recommendations for addressing insomnia disorder.

Sleep disorders, such as insomnia, are a common complication of many physical and mental health problems. This article reviews insomnia disorder, including assessment, comorbidities, and management. It is imperative that primary care providers understand how to provide the safest pharmacologic and nonpharmacologic treatments to patients with insomnia.

A small-molecule screen reveals that HSP90ß promotes the conversion of induced pluripotent stem cell-derived endoderm to a hepatic fate and regulates HNF4A turnover.

We have previously shown that the transcription factor HNF4A is required for the formation of hepatic progenitor cells from endoderm that has been derived from human induced pluripotent stem cells (iPSCs). We reasoned that we could uncover regulatory pathways with new roles in hepatocyte differentiation by identifying cellular processes that regulate HNF4A. We therefore performed a screen of 1120 small molecules with well-characterized mechanisms of action to detect those that affect the abundance of HNF4A in iPSC-derived hepatic progenitor cells. This approach uncovered several small molecules that depleted HNF4A. Of those, we chose to focus on an inhibitor of heat shock protein 90 beta (HSP90ß). We show that mutation of the gene encoding HSP90ß represses hepatocyte differentiation during the formation of hepatocytes from iPSCs. We reveal that HSP90ß, although dispensable for expression of HNF4A mRNA, directly interacts with HNF4A protein to regulate its half-life. Our results demonstrate that HSP90ß has an unappreciated role in controlling hepatic progenitor cell formation and highlight the efficiency of using small-molecule screens during the differentiation of iPSCs to reveal new molecular mechanisms that control hepatocyte formation.

Phase matching in hyperbolic wire media for nonlinear frequency conversion.

Efficient nonlinear frequency conversion requires a phase matching condition to be satisfied. We analyze the dispersion of the modes of hyperbolic wire metamaterials and demonstrate that phase matching at infrared wavelengths can be achieved with a variety of constituent materials, such as GaAs, in which phase matching cannot easily be achieved by conventional means. Our finding promises access to many materials with attractive nonlinear properties.

Porcine vas deferens luminal pH is acutely increased by systemic xylazine administration.

Data are accumulating to demonstrate that pH regulation in the male reproductive tract has a vital role in modulating sperm cell fertilizing capacity, and therefore male fertility. Bicarbonate uptake by sperm cells is required for the achievement of motility levels required for fertilization. Vas deferens epithelial cells can carry out measurable bicarbonate secretion, but the available literature to date reports that the vas deferens luminal content is typically acidic. This study aimed to determine pH in the boar vas deferens lumen and whether modulatory mechanisms exist for regulation of pH in this compartment of the male reproductive tract. A fiberoptic pH probe was used to assess pH in the vas deferens of anesthetized adult boars. The mean pH, derived from multiple measurements at variable positions along the vas deferens lumen, was 7.39 +/- 0.09. Furthermore, administration of xylazine, an alpha-2 adrenergic receptor agonist rapidly (<10 min) alkalinized the vas deferens lumen in most cases. Because the duct was transected proximal to the site of measurements, the observations rule out the possibility that alkalinization resulted from secretion in more proximal portions of the duct. These results indicate that the boar vas deferens lumen can be alkaline, and they suggest that porcine vas deferens epithelia increase net bicarbonate secretion in vivo after systemic alpha-2 adrenergic stimulation. This secretory response greatly changes the luminal environment to which sperm cells are exposed, which will initiate or enhance motility, and is expected to modulate male fertility.

Testosterone upregulates anion secretion across porcine vas deferens epithelia in vitro.

Testosterone induces and maintains prostaglandin endoperoxide synthase 2 (PTGS2, also known as cyclooxygenase 2) expression in vas deferens epithelial cells, but it remains unknown whether this has a physiological role in the context of male reproductive biology. Prostaglandins induce concentration-dependent increases in anion secretion in porcine vas deferens epithelial cell (1 degrees PVD) monolayers, where bicarbonate contributes to cAMP-stimulated anion secretion. Moreover, bradykinin induces anion secretion across 1 degrees PVD monolayers that is indomethacin sensitive, and both PTGS2 and PTGS1 are expressed in this model system. Therefore, it was hypothesized that testosterone modulates anion secretion across vas deferens epithelia via PTGS-dependent pathways and prostaglandin synthesis. Porcine vas deferens epithelial cells were isolated and cultured as monolayers on permeable supports until assayed in modified Ussing chambers. RNA and protein were isolated concurrently for semiquantitative expression analysis. Testosterone upregulated basal and bradykinin-induced short-circuit current across 1 degrees PVD monolayers, indicative of anion secretion. Testosterone also induced greater transepithelial electrical resistance. Increases in anion secretion were associated with preferential upregulation of PTGS2 at the mRNA and protein levels. In addition, testosterone induced greater basal and bradykinin-induced anion secretion across vas deferens epithelial cells isolated from the distal segment of the duct. Taken together, these results suggest that testosterone upregulates epithelial responsiveness to acute modulations of anion secretion (likely bicarbonate secretion), which ultimately modifies the environment to which sperm are exposed.