The interplay of intracellular calcium and zinc ions in response to electric field stimulation in primary rat cortical neurons in vitro

Recent pharmacological studies demonstrate a role for zinc (Zn2+) in shaping intracellular calcium (Ca2+) dynamics and vice versa in excitable cells including neurons and cardiomyocytes. Herein, we sought to examine the dynamic of intracellular release of Ca2+ and Zn2+ upon modifying excitability of primary rat cortical neurons using electric field stimulation (EFS) in vitro. We show that exposure to EFS with an intensity of 7.69 V/cm induces transient membrane hyperpolarization together with transient elevations in the cytosolic levels of Ca2+ and Zn2+ ions. The EFS-induced hyperpolarization was inhibited by prior treatment of cells with the K+ channel opener diazoxide. Chemical hyperpolarization had no apparent effect on either Ca2+ or Zn2+. The source of EFS-induced rise in Ca2+ and Zn2+ seemed to be intracellular, and that the dynamic inferred of an interplay between Ca2+ and Zn2+ ions, whereby the removal of extracellular Ca2+ augmented the release of intracellular Ca2+ and Zn2+ and caused a stronger and more sustained hyperpolarization. We demonstrate that Zn2+ is released from intracellular vesicles located in the soma, with major co-localizations in the lysosomes and endoplasmic reticulum. These studies further support the use of EFS as a tool to interrogate the kinetics of intracellular ions in response to changing membrane potential in vitro

A Low-cost, Sterile System for Fat Collection Using a Syringe Tube as a Reservoir

Summary:. Fat grafting is a widely performed procedure in the field of plastic surgery. It involves fat extraction, processing, and injection into a recipient site. It is imperative that the fat is collected and processed in a sterile system. A wide variety of equipment is required to perform the procedure (eg, a liposuction device, a vacuum pump, and syringes). Limitations often arise in the operating room, especially in low-resource areas, where task-specific equipment might be unavailable. This can present an opportunity for the surgeon to improvise and create a temporary solution. In this report, we describe our solution in dealing with the unavailability of a sterile vacuum pump canister during a large volume fat grafting procedure. We constructed a sterile reservoir using two syringes, through which negative pressure was delivered without breaking sterility. The items used were a 60-cm3 syringe barrel, a 10-cm3 syringe barrel, a 60-cm3 syringe plunger seal, a tube connected to the nonsterile vacuum pump, and the liposuction cannula. This technique allowed us to extract the fat in a sterile environment under the assistance of a suction device. Our novel technique was used for harvesting fat in a sterile reservoir, while still utilizing the assisted suction from the nonsterile vacuum pump, without breaking sterility

Reliability of Agreement between Insulin, Clonidine, and Glucagon Stimulation Tests for the Diagnosis of Growth Hormone Deficiency in Children: A Retrospective Cohort Study

Growth hormone (GH) deficiency (GHD) is a rare disorder. The diagnosis of GHD requires a combination of two provocative GH tests. This study aimed to find agreement between commonly used medications to determine which combined tests have high reliability of agreement. This retrospective cohort included 201 children who underwent GH provocation testing from January 2012 to December 2022. The insulin tolerance test (ITT) with the clonidine stimulation test (CST) or glucagon stimulation test (GST) with the CST were performed. We calculated Cohen’s kappa to determine the agreement between the test medications by considering the post-stimulation peak GH level with a cut-off value of 10 ng/mL as the primary outcome. A total of 151 patients underwent the two provocative tests and were included in the analysis. Of these patients, 119 underwent the ITT and CST and 54 (45.3%) were diagnosed with GHD. However, 32 patients underwent the GST and CST and 18 (56.2%) were diagnosed with GHD. The kappa value for ITT and CST was 0.258 (25.8%), indicating fair agreement between clonidine and insulin (p = 0.005). However, the kappa value for CST and GST was 0.178 (17.8%), representing slight agreement. The correlation coefficient revealed a very strong relationship between ITT and CST. Clonidine has fair agreement and a very strong correlation coefficient with ITT when used to diagnose GHD in children. Among the commonly used pharmacological tests for GH provocation in our unit, the CST was considered the best pharmacological test in terms of safety and reduced parental anxiety