Influence of Bone Cement Augmentation on Complications in Cephalomedullary Nail Fixation of Geriatric Intertrochanteric Hip Fractures.

Introduction: The purpose of this study was to determine if augmentation of the helical blade with polymethylmethacrylate bone cement decreases the rates of varus cut-out and medial perforation in geriatric intertrochanteric hip fracture fixation.

Methods: This was a retrospective comparative cohort study at two urban Level I trauma centers. Patients with an intertrochanteric hip fracture (classified as AO 31A1-3) who were treated with the TFN-Advanced Proximal Femoral Nailing System (TFNA) from 2018 to 2021 were eligible for the study.

Improving Medical Student Mentorship in Orthopaedic Surgery.

Introduction: Owing to limited clinical clerkships and travel restrictions related to COVID-19, recent medical student mentorship in orthopaedic surgery has been impacted negatively. The purpose of this quality improvement (QI) project was to determine if medical student awareness of orthopaedics as a possible career field may be improved through a mentoring program designed and delivered by orthopaedic residents.

Methods: A five-resident QI team developed four educational sessions aimed at a medical student audience.

Sex-Based Differences in Outcomes After Hip Arthroscopic Surgery for Femoroacetabular Impingement: A Systematic Review.

Background: While sex-based differences in outcomes after hip arthroscopic surgery for femoroacetabular impingement syndrome (FAIS) are often recorded, no studies have been dedicated to analyzing the literature as a whole.

Purpose: To investigate whether sex is a predictor of outcomes in studies evaluating hip arthroscopic surgery for FAIS.

Study Design: Systematic review; Level of evidence, 4.

Comparison between mouse and sea urchin orthologs of voltage-gated proton channel suggests role of S3 segment in activation gating.

The voltage-gated proton channel, Hv1, is expressed in blood cells, airway epithelium, sperm and microglia, playing important roles in diverse biological contexts including phagocytosis or sperm maturation through its regulation of membrane potential and pH. The gene encoding Hv1, HVCN1, is widely found across many species and is also conserved in unicellular organisms such as algae or dinoflagellates where Hv1 plays role in calcification or bioluminescence. Voltage-gated proton channels exhibit a large variation of activation rate among different species.

Rapid desensitization of the rat α7 nAChR is facilitated by the presence of a proline residue in the outer β-sheet.

The rat α7 nicotinic acetylcholine receptor (nAChR) has a proline residue near the middle of the β9 strand. The replacement of this proline residue at position 180 (P180) by either threonine (α7-P180T) or serine (α7-P180S) slowed the onset of desensitization dramatically, with half-times of ~930 and 700 ms, respectively, compared to 90 ms for the wild-type receptor. To investigate the importance of the hydroxyl group on the position 180 side-chains, the mutant receptors α7-P180Y and α7-P180F were studied and showed half-times of desensitization of 650 and 160 ms, respectively.

Evolution by leaps: gene duplication in bacteria.

Background: Sequence related families of genes and proteins are common in bacterial genomes. In Escherichia coli they constitute over half of the genome. The presence of families and superfamilies of proteins suggest a history of gene duplication and divergence during evolution.

Reversal of agonist selectivity by mutations of conserved amino acids in the binding site of nicotinic acetylcholine receptors.

Homomeric alpha7 and heteromeric alpha4beta2 nicotinic acetylcholine receptors (nAChR) can be distinguished by their pharmacological properties, including agonist specificity. We introduced point mutations of conserved amino acids within the C loop, a region of the receptor critical for agonist binding, and we examined the expression of the mutant receptors in Xenopus oocytes. Mutation of either a conserved C loop tyrosine (188) to phenylalanine or a nearby conserved aspartate (197) to alanine resulted in alpha7 receptors for which the alpha7-selective agonist 3-(4-hydroxy, 2-methoxybenzylidene) anabaseine (4OH-GTS-21) had roughly the same potency as for wild-type receptors, whereas the physiologic agonist acetylcholine (ACh) showed drastically reduced potency for these mutant receptors.

Rhesus monkey alpha7 nicotinic acetylcholine receptors: comparisons to human alpha7 receptors expressed in Xenopus oocytes.

An alpha7 nicotinic acetylcholine receptor sequence was cloned from Rhesus monkey (Macaca mulatta). This clone differs from the mature human alpha7 nicotinic acetylcholine receptor in only four amino acids, two of which are in the extracellular domain. The monkey alpha7 nicotinic receptor was characterized in regard to its functional responses to acetylcholine, choline, cytisine, and the experimental alpha7-selective agonists 4OH-GTS-21, TC-1698, and AR-R17779.

The structural basis for GTS-21 selectivity between human and rat nicotinic alpha7 receptors.

The alpha7 nAChR-selective partial agonist 3-(2,4-dimethoxybenzylidene)anabaseine (GTS-21) is more efficacious and potent for rat receptors than for human alpha7 receptors. Four single amino acid differences exist between human and rat alpha7 in the agonist binding site, two in the C loop, and one each in the E and F loops. Reciprocal mutations were made in these three domains and evaluated in Xenopus laevis oocytes.

Comparison of K+-channel genes within the genomes of Anopheles gambiae and Drosophila melanogaster.

Background: Potassium channels are the largest and most diverse type of ion channel found in nature. The completion of the sequencing of the genomes of Drosophila melanogaster and Anopheles gambiae, which belong to the same order, the Diptera, allows us to compare and contrast K+-channel genes and gene families present within the genomes of two dipterans.

Results: This study identifies at least eight voltage-gated K+-channel genes in Anopheles, as well as three Slo-family, three Eag-family and six inward rectifier K+-channel genes.