Prenatal stress‐related alterations in synaptic transmission and 5‐HT7 receptor‐mediated effects in the rat dorsal raphe nucleus are ameliorated by the 5‐HT7 receptor antagonist SB 269970

Early life adversity exerts a detrimental influence on developing brain neuronal networks and its consequences may include mental health disorders. In rats, prenatal stress may lead to anxiety and depressive‐like behavior in the offspring. Several lines of evidence implicated an involvement of prenatal stress in alterations of the brain serotonergic system functions, but the effects of prenatal stress on its core, the dorsal raphe nucleus (DRN), still remain incompletely understood. The present study was aimed at finding whether prenatal stress induces modifications in the glutamatergic and GABAergic inputs to DRN projection cells and whether it affects DRN 5‐HT₇ receptors, which modulate activity of these synapses. Prenatal stress resulted in an increase in basal frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and in a decrease in basal frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) recorded from putative projection neurons in DRN slices ex vivo. While there were no changes in the excitability of DRN projection neurons, the 5‐HT₇ receptor‐mediated reduction in the sEPSC frequency and rise in the sIPSC frequency, seen in control rats, were largely absent in slices obtained from prenatally stressed rats. Repeated administration of SB 269970, a 5‐HT₇ receptor antagonist, resulted in a reversal of prenatal stress‐induced alterations in 5‐HT₇ receptor‐mediated effects on the sEPSC/sIPSC frequency. Moreover, the treatment reversed prenatal stress‐induced alterations in basal excitatory transmission and partially reversed the effect of stress on basal inhibitory transmission in the DRN.     

Molecular Basis of Intervertebral Disc Degeneration and Herniations: What Are the Important Translational Questions?

Background

Intervertebral disc degeneration is a common condition with few inexpensive and effective modes of treatment, but current investigations seek to clarify the underlying process and offer new treatment options. It will be important for physicians to understand the molecular basis for the pathology and how it translates to developing clinical treatments for disc degeneration. In this review, we sought to summarize for clinicians what is known about the molecular processes that causes disc degeneration.

Results

A healthy disc requires maintenance of a homeostatic environment, and when disrupted, a catabolic cascade of events occurs on a molecular level resulting in upregulation of proinflammatory cytokines, increased degradative enzymes, and a loss of matrix proteins. This promotes degenerative changes and occasional neurovascular ingrowth potentially contributing to the development of pain. Research demonstrates the molecular changes underlying the harmful effects of aging, smoking, and obesity seen clinically while demonstrating the variable influence of exercise. Finally, oral medications, supplements, biologic treatments, gene therapy, and stem cells hold great promise but require cautious application until their safety profiles are better outlined.

Conclusions

Intervertebral disc degeneration occurs where there is a loss of homeostatic balance with a predominantly catabolic metabolic profile. A basic understanding of the molecular changes occurring in the degenerating disc is important for practicing clinicians because it may help them to inform patients to alter lifestyle choices, identify beneficial or harmful supplements, or offer new biologic, genetic, or stem cell therapies.     

Oncocytoid artifact of the parotid gland: A newly reported artifact

Electrocautery can induce significant alterations in the connective tissues and epithelium of specimens removed for diagnostic or therapeutic purposes. When electrocautery is used during parotid surgery, it can cause an oncocytoid artifact. The alterations described in this article are enlarged, tightly packed serous acinar cells with coarse to granular eosinophilic cytoplasm, distinct cell borders, and round basal nuclei that on cursory microscopic examination resemble oncocytes with respect to morphology. These changes are seen in conjunction with other, more recognized changes secondary to electrocautery and are believed to occur as a consequence of the electrothermal discharge. On the basis of our findings, this artifact is common in parotid surgical specimens and was misdiagnosed as benign oncocytic lesions in 5 cases.     

Management of Periodontal Tissues for Restorative Dentistry

Proper management of periodontal tissues is required to achieve predictable long-term success with restorative dental procedures. Forced eruption as well as several surgical techniques may be used to achieve and maintain adequate biologic width during restorative and esthetic dental procedures. The technique that will yield optimal results depends on the relationship between the restoration's margins and the surrounding periodontium. A classification system that describes these interrelationships and provides treatment recommendations is included.     

Phylogenetic analysis of human G9P[8] rotavirus strains circulating in Jiangsu,China between 2010 and 2016

Rotavirus A (RVA) is the leading cause of acute viral gastroenteritis in children under 5 years of age worldwide. G9P[8] is a common RVA genotype that has been persistently prevalent in Jiangsu, China. To determine the genetic diversity of G9P[8] RVAs, 7 representative G9P[8] strains collected from Suzhou Children’s Hospital between 2010 and 2016 (named JS2010‐JS2016) were analyzed through whole‐genome sequencing. All evaluated strains showed the Wa‐like constellation G9‐P[8]‐I1‐R1‐C1‐M1‐A1‐N1‐T1‐E1‐H1. Furthermore, phylogenetic analysis revealed that the VP7 genes of all strains clustered into lineage G9‐III and G9‐VI. With the exception of strain JS2012 (P[8]‐4), the VP4 sequences of all strains belonged to the P[8]‐3 lineage. Sequencing further revealed that amino acid substitutions were present in the antigenic regions of the VP7 and VP4 genes of all strains. Moreover, there were multiple substitutions in antigenic sites I and II of the nonstructural protein 4 (NSP4) genes, whereas the other NSP genes were relatively conserved. In conclusion, our phylogenetic analysis of these 7 G9P[8] strains suggests that RVA varied across regions and time. Therefore, our findings suggest that continued surveillance is necessary to explore the molecular evolutionary characteristics of RVA for better prevention and treatment of acute viral gastroenteritis.     

Hybrid-fuel bacterial flagellar motors in Escherichia coli

The bacterial flagellar motor rotates driven by an electrochemical ion gradient across the cytoplasmic membrane, either H⁺ or Na⁺ ions. The motor consists of a rotor ∼50 nm in diameter surrounded by multiple torque-generating ion-conducting stator units. Stator units exchange spontaneously between the motor and a pool in the cytoplasmic membrane on a timescale of minutes, and their stability in the motor is dependent upon the ion gradient. We report a genetically engineered hybrid-fuel flagellar motor in Escherichia coli that contains both H⁺- and Na⁺-driven stator components and runs on both types of ion gradient. We controlled the number of each type of stator unit in the motor by protein expression levels and Na⁺ concentration ([Na⁺]), using speed changes of single motors driving 1-μm polystyrene beads to determine stator unit numbers. De-energized motors changed from locked to freely rotating on a timescale similar to that of spontaneous stator unit exchange. Hybrid motor speed is simply the sum of speeds attributable to individual stator units of each type. With Na⁺ and H⁺ stator components expressed at high and medium levels, respectively, Na⁺ stator units dominate at high [Na⁺] and are replaced by H⁺ units when Na⁺ is removed. Thus, competition between stator units for spaces in a motor and sensitivity of each type to its own ion gradient combine to allow hybrid motors to adapt to the prevailing ion gradient. We speculate that a similar process may occur in species that naturally express both H⁺ and Na⁺ stator components sharing a common rotor.Molecular motors are tiny machines that perform a wide range of functions in living cells. Typically each motor generates mechanical work using a specific chemical or electrochemical energy source. Linear motors such as kinesin on microtubules or myosin on actin filaments and rotary motors such as F₁-ATPase, the soluble part of ATP-synthase, run on ATP, whereas the rotary bacterial flagellar motor embedded in the bacterial cell envelope is driven by the flux of ions across the cytoplasmic membrane (1–4). Coupling ions are known to be either protons (H⁺) or sodium ions (Na⁺) (5, 6).The bacterial flagellar motor consists of a rotor ∼50 nm in diameter surrounded by multiple stator units (7–10). Each unit contains two types of membrane proteins forming ion channels: MotA and MotB in H⁺ motors in neutrophiles (e.g., Escherichia coli and Salmonella) and PomA and PomB in Na⁺ motors in alkalophiles and Vibrio species (e.g., Vibrio alginolyticus) (1, 11). Multiple units interact with the rotor to generate torque independently in a working motor (9, 10, 12, 13). The structure and function of H⁺ and Na⁺ motors are very similar, to the extent that several functional chimeric motors have been made containing different mixtures of H⁺- and Na⁺-motor components (11). One such motor that runs on Na⁺ in E. coli combines the rotor of the H⁺-driven E. coli motor with the chimeric stator unit PomA/PotB, containing PomA from V. alginolyticus and a fusion protein between MotB from E. coli and PomB from V. alginolyticus (14).In most flagellated bacteria, motors are driven by ion-specific rotor–stator combinations. However, some species (e.g., Bacillus subtilis and Shewanella oneidensis) combine a single set of rotor genes with multiple sets of stator genes encoding both H⁺ and Na⁺ stator proteins, and it has been speculated that these stator components may interact with the rotor simultaneously, allowing a single motor to use both H⁺ and Na⁺. An appealing hypothesis that the mixture of stator components is controlled dynamically depending on the environment has arisen from the observation that the localization of both stator components depends upon Na⁺ (15). However, despite some experimental effort there is as yet no direct evidence of both H⁺ and Na⁺ stator units interacting with the same rotor (16).The rotation of single flagellar motors can be monitored in real time by light microscopy of polystyrene beads (diameter ∼1 μm) attached to truncated flagellar filaments (17). Under these conditions, the E. coli motor torque and speed are proportional to the number of stator units in both H⁺-driven MotA/MotB and Na⁺-driven PomA/PotB (17–19) motors. The maximum number of units that can work simultaneously in a single motor has been shown to be at least 11 by “resurrection” experiments, in which newly produced functional units lead to restoration of motor rotation in discrete speed increments in an E. coli strain lacking functional stator proteins (19). Stator units are not fixed permanently in a motor: Each dissociates from the motor with a typical rate of ∼2 min⁻¹, exchanging between the motor and a pool of diffusing units in the cytoplasmic membrane (20). Removal of the relevant ion gradient inactivates both H⁺ and Na⁺ stator units, most likely leading to dissociation from the motor into the membrane pool (2, 21, 22).Here we demonstrate a hybrid-fuel motor containing both H⁺-driven MotA/MotB and Na⁺-driven PomA/PotB stator components, sharing a common rotor in E. coli. We control the expression level of each stator type by induced expression from plasmids, and the affinity of Na⁺-driven stator units for the motor by external [Na⁺]. Units of each type compete for spaces around the rotor, and the motor torque is simply the sum of the independent contributions, with no evidence of direct interaction between units. Thus, we demonstrate the possibility of modularity in the E. coli flagellar motor, with ion selectivity determined by the choice of stator modules interacting with a common rotor. Our artificial hybrid motor demonstrates that species with multiple types of stator gene and a single set of rotor genes could contain natural hybrid motors that work on a similar principle (15, 16, 23).