Mechanism of kisspeptin neuron synchronization for pulsatile hormone secretion in male mice.

The mechanism by which arcuate nucleus kisspeptin (ARN) neurons co-expressing glutamate, neurokinin B, and dynorphin intermittently synchronize their activity to generate pulsatile hormone secretion remains unknown. An acute brain slice preparation maintaining synchronized ARN neuron burst firing was used alongside in vivo GCaMP GRIN lens microendoscope and fiber photometry imaging coupled with intra-ARN microinfusion. Studies in intact and gonadectomized male mice revealed that ARN neuron synchronizations result from near-random emergent network activity within the population and that this was critically dependent on local glutamate-AMPA signaling.

Definition of the estrogen negative feedback pathway controlling the GnRH pulse generator in female mice.

The mechanisms underlying the homeostatic estrogen negative feedback pathway central to mammalian fertility have remained unresolved. Direct measurement of gonadotropin-releasing hormone (GnRH) pulse generator activity in freely behaving mice with GCaMP photometry demonstrated striking estradiol-dependent plasticity in the frequency, duration, amplitude, and profile of pulse generator synchronization events. Mice with Cre-dependent deletion of ESR1 from all kisspeptin neurons exhibited pulse generator activity identical to that of ovariectomized wild-type mice.

ATR FTIR Study of the Interaction of TiO Nanoparticle Films with β-Lactoglobulin and Bile Salts.

The technique of in situ particle film attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) has been used to probe the adsorption and coadsorption (sequential) of a common food protein (β-lactoglobulin, BLG) and two representative bile salts (taurocholic acid and glycocholic acid, abbreviated as TCA and GCA) onto the surface of titanium dioxide (TiO) nanoparticles. Evaluating of binding interactions between commonly used (historically now, in some countries) food additives and food components, as well as the body's own digestion chemicals, is a critical step in understanding the role of colloidal phenomena in digestion and bioavailability. TCA is found to adsorb onto TiO but without any significant ability to be retained when it is not present in the aqueous phase.

Highly redundant neuropeptide volume co-transmission underlying episodic activation of the GnRH neuron dendron.

The necessity and functional significance of neurotransmitter co-transmission remains unclear. The glutamatergic 'KNDy' neurons co-express kisspeptin, neurokinin B (NKB), and dynorphin and exhibit a highly stereotyped synchronized behavior that reads out to the gonadotropin-releasing hormone (GnRH) neuron dendrons to drive episodic hormone secretion. Using expansion microscopy, we show that KNDy neurons make abundant close, non-synaptic appositions with the GnRH neuron dendron.

Adsorption of Carboxymethyl Cellulose onto Titania Particle Films Studied with in Situ IR Spectroscopic Analysis.

Adsorption of carboxymethyl cellulose (CMC) in aqueous solution onto a titania nanoparticle film has been studied using in situ attenuated total reflectance infrared spectroscopy (ATR-IR). CMC was adsorbed onto the positively charged titania surface in neutral, partially charged, and fully charged state. The response of the adsorbed polyelectrolyte layer was monitored upon changing the electrolyte pH and ionic strength.

GnRH Pulse Generator Activity Across the Estrous Cycle of Female Mice.

A subpopulation of kisspeptin neurons located in the arcuate nucleus (ARN) operate as the GnRH pulse generator. The activity of this population of neurons can be monitored in real-time for long periods using kisspeptin neuron-selective GCaMP6 fiber photometry. Using this approach, we find that ARN kisspeptin neurons exhibit brief (∼50 seconds) periods of synchronized activity that precede pulses of LH in intact female mice.

Adsorption of a Polyethoxylated Surfactant from Aqueous Solution to Silica Nanoparticle Films Studied with In Situ Attenuated Total Reflection Infrared Spectroscopy and Colloid Probe Atomic Force Microscopy.

Polyethoxylated (PEO) surfactant adsorption to silica under aqueous conditions is an important physical process in a multitude of industries. Consequently, a considerable number of spectroscopic and other studies have been carried out to ascertain the molecular/structural details of the adsorbed surfactant and the kinetics of PEO surfactant adsorption. However, the use of infrared spectroscopy to probe surfactant adsorption at the silica/aqueous solution interface has been limited because of the instability of silica particle films under aqueous conditions and the opacity of silicon prisms below 1300 cm typically employed for these studies.

Microscopic and infrared spectroscopic comparison of the underwater adhesives produced by germlings of the brown seaweed species Durvillaea antarctica and Hormosira banksii.

Adhesives from marine organisms are often the source of inspiration for the development of glues able to create durable bonds in wet environments. In this work, we investigated the adhesive secretions produced by germlings of two large seaweed species from the South Pacific, Durvillaea antarctica, also named 'the strongest kelp in the word', and its close relative Hormosira banksii The comparative analysis was based on optical and scanning electron microscopy imaging as well as Fourier transform infrared (FTIR) spectroscopy and principal component analysis (PCA). For both species, the egg surface presents peripheral vesicles which are released soon after fertilization to discharge a primary adhesive.

Histomorphometric and histologic evaluation of titanium-zirconium (aTiZr) implants with anodized surfaces.

The choice of implant surface has a significant influence on osseointegration. Modification of TiZr surface by anodization is reported to have the potential to modulate the osteoblast cell behaviour favouring more rapid bone formation. The aim of this study is to investigate the effect of anodizing the surface of TiZr discs with respect to osseointegration after four weeks implantation in sheep femurs.

Mechanisms of murine cerebral malaria: Multimodal imaging of altered cerebral metabolism and protein oxidation at hemorrhage sites.

Using a multimodal biospectroscopic approach, we settle several long-standing controversies over the molecular mechanisms that lead to brain damage in cerebral malaria, which is a major health concern in developing countries because of high levels of mortality and permanent brain damage. Our results provide the first conclusive evidence that important components of the pathology of cerebral malaria include peroxidative stress and protein oxidation within cerebellar gray matter, which are colocalized with elevated nonheme iron at the site of microhemorrhage. Such information could not be obtained previously from routine imaging methods, such as electron microscopy, fluorescence, and optical microscopy in combination with immunocytochemistry, or from bulk assays, where the level of spatial information is restricted to the minimum size of tissue that can be dissected.

Surficial Siloxane-to-Silanol Interconversion during Room-Temperature Hydration/Dehydration of Amorphous Silica Films Observed by ATR-IR and TIR-Raman Spectroscopy.

Silica has been frequently studied using infrared and Raman spectroscopy due to its importance in many practical contexts where its surface chemistry plays a vital role. The majority of these studies have utilized chemical-vapor-deposited films in vacuo after high-temperature calcination. However, room-temperature hydration and dehydration of thin silica particle films has not been well characterized in spite of the importance of such films as substrates for polymer and surfactant adsorption.

Spark anodization of titanium-zirconium alloy: surface characterization and bioactivity assessment.

Titanium (Ti) and its alloys have been popularly used as implant biomaterial for decades. Recently, titanium-zirconium (TiZr) alloy has been developed as an alternative implant material with improved strength in load bearing areas. Surface modification is one of the key factors to alter the surface properties to hasten osseointegration.

IRGM3 contributes to immunopathology and is required for differentiation of antigen-specific effector CD8+ T cells in experimental cerebral malaria.

Gamma interferon (IFN-γ) drives antiparasite responses and immunopathology during infection with Plasmodium species. Immunity-related GTPases (IRGs) are a class of IFN-γ-dependent proteins that are essential for cell autonomous immunity to numerous intracellular pathogens. However, it is currently unknown whether IRGs modulate responses during malaria.

Juvenile hormone enhances aversive learning performance in 2-day old worker honey bees while reducing their attraction to queen mandibular pheromone.

Previous studies have shown that exposing young worker bees (Apis mellifera) to queen mandibular pheromone (QMP) reduces their aversive learning performance, while enhancing their attraction to QMP. As QMP has been found to reduce the rate of juvenile hormone (JH) synthesis in worker bees, we examined whether aversive learning in 2-day old workers exposed to QMP from the time of adult emergence could be improved by injecting JH (10 µg in a 2 µl volume) into the haemolymph. We examined in addition, the effects of JH treatment on worker attraction to QMP, and on the levels of expression of amine receptor genes in the antennae, as well as in the mushroom bodies of the brain.

Oxidative IR spectroelectrochemistry of copper in methanol containing carbon monoxide.

IR spectroelectrochemistry was used to examine the electro-oxidation behavior of carbon monoxide in methanol at a polycrystalline copper electrode. Under such neutral conditions copper electrodes are coated with ill-defined copper oxides and hydroxides and at the oxidative potentials can be expected to generate soluble copper species. The electrochemistry displayed complex behavior suggesting that methanol oxidation was one prominent reaction.

The kynurenine pathway contributes to long-term neuropsychological changes in experimental pneumococcal meningitis.

Pneumococcal meningitis is a lethal form of bacterial infection in the central nervous system that often causes lifelong neurological sequelae, despite therapeutic advances. The contemporary view is that the inflammatory response to infection contributes to the functional disabilities among survivors of this disease. We previously have established a mouse model of neurobehavioural deficits, using an automated IntelliCage™ system that revealed long-term behavioural and cognitive deficits in C57BL/6J female mice cured of meningitis by ceftriaxone treatment.

Steroid hormone (20-hydroxyecdysone) modulates the acquisition of aversive olfactory memories in pollen forager honeybees.

Here, we examine effects of the steroid hormone, 20-hydroxyecdysone (20-E), on associative olfactory learning in the honeybee, Apis mellifera. 20-E impaired the bees' ability to associate odors with punishment during aversive conditioning, but did not interfere with their ability to associate odors with a food reward (appetitive learning). The steroid had a significant impact also on the expression of amine-receptor genes in centers of the brain involved in the formation and recall of associative olfactory memories (mushroom bodies).

FTIR imaging of brain tissue reveals crystalline creatine deposits are an ex vivo marker of localized ischemia during murine cerebral malaria: general implications for disease neurochemistry.

Phosphocreatine is a major cellular source of high energy phosphates, which is crucial to maintain cell viability under conditions of impaired metabolic states, such as decreased oxygen and energy availability (i.e., ischemia).

Inflammasome-dependent IFN-γ drives pathogenesis in Streptococcus pneumoniae meningitis.

The pathology associated with Streptococcus pneumoniae meningitis results largely from activation of immune-associated pathways. We systematically investigated the production of IFN subtypes, as well as their influence on pathology, in a mouse model of S. pneumoniae meningitis.

Mushroom bodies of the honeybee brain show cell population-specific plasticity in expression of amine-receptor genes.

Dopamine and octopamine released in the mushroom bodies of the insect brain play a critical role in the formation of aversive and appetitive memories, respectively. As recent evidence suggests a complex relationship between the effects of these two amines on the output of mushroom body circuits, we compared the expression of dopamine- and octopamine-receptor genes in three major subpopulations of mushroom body intrinsic neurons (Kenyon cells). Using the brain of the honeybee, Apis mellifera, we found that expression of amine-receptor genes differs markedly across Kenyon cell subpopulations.

In situ ATR FTIR study of dextrin adsorption on anatase TiO2.

The adsorption of two dextrin-based polymers, a regular wheat dextrin (TY) and a carboxymethyl-substituted (CM) dextrin, onto an anatase TiO(2) particle film has been studied using in situ attenuated total reflection (ATR) FTIR spectroscopy. Infrared spectra of the polymer solutions and the polymer adsorbed at the anatase surface were acquired for two solution conditions: pH 3 and pH 9; below and above the isoelectric point (IEP) of anatase, respectively. Comparison of the polymer solution spectra and the adsorbed layer spectra highlighted a number of spectral differences that were attributed to involvement of the carboxyl group of CM Dextrin interacting with the anatase surface directly and the adsorption of oxidized dextrin chains in the case of regular dextrin (TY) at high pH.

Redox transformations at nanodiamond surfaces revealed by in situ infrared spectroscopy.

Attenuated total reflectance infrared spectroscopy is used to monitor nanodiamond surface group transformations in the presence of aqueous IrCl(6)(2-). Electron transfer between the nanoparticle surface and the solution redox species results in oxidation of ∼8.5% of surface alcohol groups, with concomitant formation of unsaturated ketone or quinone-like moieties.

Alginate ion adsorption on a TiO2 particle film and interactions of adsorbed alginate with calcium ions investigated by attenuated total reflection infrared (ATR-IR) spectroscopy.

The adsorption of alginic acid on a TiO(2) particle film from aqueous solution was investigated by attenuated total reflection infrared (ATR-IR) spectroscopy. ATR-IR spectra recorded at different pHs confirmed that alginate adsorption to TiO(2) is favored at pH 3.0 and no significant adsorption occurs above pH 5.