Periarticular proprioception: analyzing the three-dimensional structure of corpuscular mechanosensors in the dorsal part of the scapholunate ligament.

Introduction Sensory nerve endings transmit mechanical stimuli into afferent neural signals and form the basis of proprioception, giving rise to the self-perception of dynamic stability of joints. We aimed to analyze the three-dimensional structure of periarticular corpuscular sensory nerve endings in a carpal ligament to enhance our understanding of their microstructure. Methods Two dorsal parts of the scapholunate ligament were excised from two human cadaveric wrist specimens. Consecutive cryosections were stained with immunofluorescence markers protein S100B, neurotrophin receptor p75 (p75), protein gene product 9.5 (PGP 9.5) and 4' ,6-diamidino-2-phenylindole (DAPI). Three-dimensional images of sensory nerve endings were obtained using confocal laser scanning microscopy and subsequent analysis was performed using Imaris software. Results Ruffini endings were characterized by a PGP 9.5-positive central axon, with a median diameter of 4.63 µm and contained a median of 25 cells. The p75-positive capsule had a range in thickness of 0.94 µm and 15.5 µm, consisting of single to three layers of lamellar cells. Ruffini endings were significantly smaller in volume than Pacini corpuscles or Golgi-like endings. The latter contained a median of three intracorpuscular structures. Ruffini endings and Golgi-like endings presented a similar structural composition of their capsule and subscapular space. The central axon of Pacini corpuscles was surrounded by S100-positive cells forming the inner core which was significantly smaller than the outer core, which was immunoreactive for p75 and PGP 9.5. Conclusion This study reports new data regarding the intricate outer and intracorpuscular 3D morphology of periarticular sensory nerve endings, including the volume, number of cells and structural composition. These results may form a basis to differ between normal and pathological morphological changes in periarticular sensory nerve endings in future studies.

Expression of the cobalamin transporters cubam and MRP1 in the canine ileum-Upregulation in chronic inflammatory enteropathy.

Chronic inflammatory enteropathy (CIE) in dogs, a spontaneous model of human inflammatory bowel disease (IBD), is associated with a high rate of cobalamin deficiency. The etiology of hypocobalaminemia in human IBD and canine CIE remains unknown, and compromised intestinal uptake of cobalamin resulting from ileal cobalamin receptor deficiency has been proposed as a possible cause. Here, we evaluated the intestinal expression of the cobalamin receptor subunits, amnionless (AMN) and cubilin (CUBN), and the basolateral efflux transporter multi-drug resistance protein 1 (MRP1) in 22 dogs with CIE in comparison to healthy dogs. Epithelial CUBN and AMN levels were quantified by confocal laser scanning microscopy using immunohistochemistry in endoscopic ileal biopsies from dogs with (i) CIE and normocobalaminemia, (ii) CIE and suboptimal serum cobalamin status, (iii) CIE and severe hypocobalaminemia, and (iv) healthy controls. CUBN and MRP1 expression was quantified by RT-qPCR. Receptor expression was evaluated for correlation with clinical patient data. Ileal mucosal protein levels of AMN and CUBN as well as mRNA levels of CUBN and MRP1 were significantly increased in dogs with CIE compared to healthy controls. Ileal cobalamin receptor expression was positively correlated with age, clinical disease activity index (CCECAI) score, and lacteal dilation in the ileum, inversely correlated with serum folate concentrations, but was not associated with serum cobalamin concentrations. Cobalamin receptor downregulation does not appear to be the primary cause of hypocobalaminemia in canine CIE. In dogs of older age with severe clinical signs and/or microscopic intestinal lesions, intestinal cobalamin receptor upregulation is proposed as a mechanism to compensate for CIE-associated hypocobalaminemia. These results support oral supplementation strategies in hypocobalaminemic CIE patients.

Reduced neural progenitor cell count and cortical neurogenesis in guinea pigs congenitally infected with Toxoplasma gondii.

Toxoplasma (T.) gondii is an obligate intracellular parasite with a worldwide distribution. Congenital infection can lead to severe pathological alterations in the brain. To examine the effects of toxoplasmosis in the fetal brain, pregnant guinea pigs are infected with T. gondii oocysts on gestation day 23 and dissected 10, 17 and 25 days afterwards. We show the neocortex to represent a target region of T. gondii and the parasite to infect neural progenitor cells (NPCs), neurons and astrocytes in the fetal brain. Importantly, we observe a significant reduction in neuron number at end-neurogenesis and find a marked reduction in NPC count, indicating that impaired neurogenesis underlies the neuronal decrease in infected fetuses. Moreover, we observe focal microglioses to be associated with T. gondii in the fetal brain. Our findings expand the understanding of the pathophysiology of congenital toxoplasmosis, especially contributing to the development of cortical malformations.

The Bovine Hepatic Cell Line BFH12 as a Possible Model for Hepatosteatosis in Dairy Cows.

Hepatosteatosis is a common metabolic disorder of dairy cows, especially during early lactation. Currently, there are a few models of bovine hepatic steatosis available, including primary hepatocytes, liver slices, and animal models. Studies that elucidate the influence of single fatty acids on lipid classes, fatty acid pattern, gene expression, and phenotypic changes are still limited. Hence, we investigated the suitability of the fetal bovine hepatocyte-derived cell line BFH12 as a model for hepatosteatosis. To create a steatotic environment, we treated BFH12 with stearic acid, palmitic acid, or oleic acid in non-toxic doses. Thin-layer chromatography and gas chromatography were used to analyze lipid classes and fatty acid pattern, and qPCR was used to quantify gene expression of relevant target genes. Lipid droplets were visualized with confocal laser scanning microscopy and evaluated for number and size. Treatment with oleic acid increased triglycerides, as well as lipid droplet count per cell and upregulated carnitine palmitoyl transferase 1, which correlates with findings of in vivo models. Oleic acid was largely incorporated into triglycerides, phospholipids, and non-esterified fatty acids. Stearic acid was found mainly in non-esterified fatty acids and triglycerides, whereas palmitic acid was mainly desaturated to palmitoleic acid. All three fatty acids downregulated stearyl-CoA-desaturase 1. In conclusion, BFH12 can acquire a steatotic phenotype by incorporating and accumulating fatty acids. Oleic acid is particularly suitable to produce hepatosteatosis. Therefore, BFH12 may be a useful in vitro model to study bovine hepatosteatosis and its underlying molecular mechanisms.

Detection of subtilisin 3 and 6 in skin biopsies of cattle with clinically manifested bovine ringworm.

Trichophyton (T.) verrucosum is a highly pathogenic dermatophyte causing zoonotic bovine ringworm that is transmissible to humans. The virulence factors subtilisin (Sub)3 and Sub6 are discussed to contribute to disease manifestation but no protein expression study is available for T. verrucosum. We used customized antibodies (against Trichophyton-species, Sub3 and Sub6) to examine skin biopsies of infected cattle via immunofluorescence stainings. Both virulence factors Sub3 and 6 were solely expressed by conidia and not only found in epidermal but also in dermal and hair structures. The anti-T-antibody reliably detected the fungus and proved more sensitive compared to histological stains. LAY SUMMARY: We examined the zoonotic dermatophyte Trichophyton (T.) verrucosum in bovine skin and studied two important virulence factors called subtilisin (Sub)3 and Sub6 that T. verrucosum produces and secretes using immunolabeling.

Collection of immature Dermacentor reticulatus (Fabricius, 1794) ticks from vegetation and detection of Rickettsia raoultii in them.

It is commonly assumed that Dermacentor reticulatus immature life stages are nidicolous and therefore cannot be collected from vegetation. However, in June and July of 2018 and 2019, a total of 47 questing D. reticulatus larvae and two nymphs were collected by the flagging method in two different sites close to the city of Leipzig, Germany. To confirm their role in the transmission of tick-borne pathogens, 45 larvae (pooled by 2 in 21 pools and 1 pool with three individuals) and one nymph were tested either by conventional or real-time PCR for the presence of Bartonella spp., Neoehrlichia mikurensis, Rickettsia spp., and Babesia spp. All samples tested negative for Bartonella spp., N. mikurensis, and Babesia spp.; while the minimal infection rate of larvae for Rickettsia spp. was 42%, and the one tested nymph was also positive. Sequencing partial ompB genes revealed the presence of Rickettsia raoultii in larvae and nymph. Further research needs to be done to determine under which circumstances immature D. reticulatus ticks are found outside the burrows of their hosts and can be collected from vegetation.

Borderline resistance to oxacillin in Staphylococcus aureus after treatment with sub-lethal sodium hypochlorite concentrations.

Surface disinfectants are regularly used in prophylactic and infection control measures. Concern has been raised whether residues of sub-inhibitory disinfectant concentrations may constitute a selective pressure and could contribute to the development of strains which are tolerant and/or resistant to biocides including antibiotics. The current study investigated whether Staphylococcus (S.) aureus ATCC® 29213™ and ATCC® 6538™ would change their growth characteristics and antimicrobial susceptibility profiles after prolonged treatment with sub-inhibitory concentrations of sodium hypochlorite (NaOCl). NaOCl is a fast-acting disinfectant with a broad-spectrum activity, inexpensive and widely used in healthcare and the food production industry. Minimum inhibitory concentration (MIC) for NaOCl was determined by broth macrodilution according to the guidelines for disinfectant efficacy testing provided by the German Veterinary Medical Society. Serial passages after 24 h and 72 h, respectively, in defined sub-inhibitory concentrations of NaOCl resulted in a number of phenotypic variants. Two of these variants, derived from S. aureus ATCC® 29213™, showed elevated MICs of oxacillin and were considered as in vitro-generated borderline oxacillin-resistant S. aureus (BORSA). Transmission electron microscopy revealed a significantly thickened cell wall in these isolates, a phenomenon that has also been described for Listeria monocytogenes after low-level exposure to NaOCl. Whole genome sequencing revealed an early stop codon in the gene coding for the GdpP protein and thereby abolishing the function of this gene. GdpP represents a phosphodiesterase that regulates gene expression, and loss of function of the GdpP protein has been described in association with borderline oxacillin resistance. Our findings suggest that a mutation in the GdpP protein gene and morphological changes of the cell wall were induced by repeated exposure to sub-lethal NaOCl concentrations, and most likely accounted for a BORSA phenotype in two variants derived from S. aureus ATCC® 29213™.

Equine bronchial fibroblasts enhance proliferation and differentiation of primary equine bronchial epithelial cells co-cultured under air-liquid interface.

Interaction between epithelial cells and fibroblasts play a key role in wound repair and remodelling in the asthmatic airway epithelium. We present the establishment of a co-culture model using primary equine bronchial epithelial cells (EBECs) and equine bronchial fibroblasts (EBFs). EBFs at passage between 4 and 8 were seeded on the bottom of 24-well plates and treated with mitomycin C at 80% confluency. Then, freshly isolated (P0) or passaged (P1) EBECs were seeded on the upper surface of membrane inserts that had been placed inside the EBF-containing well plates and grown first under liquid-liquid interface (LLI) then under air-liquid interface (ALI) conditions to induce epithelial differentiation. Morphological, structural and functional markers were monitored in co-cultured P0 and P1 EBEC monolayers by phase-contrast microscopy, scanning and transmission electron microscopy, hematoxylin-eosin, immunocytochemistry as well as by measuring the transepithelial electrical resistance (TEER) and transepithelial transport of selected drugs. After about 15-20 days of co-culture at ALI, P0 and P1 EBEC monolayers showed pseudo-stratified architecture, presence of ciliated cells, typically honeycomb-like pattern of tight junction protein 1 (TJP1) expression, and intact selective barrier functions. Interestingly, some notable differences were observed in the behaviour of co-cultured EBECs (adhesion to culture support, growth rate, differentiation rate) as compared to our previously described EBEC mono-culture system, suggesting that cross-talk between epithelial cells and fibroblasts actually takes place in our current co-culture setup through paracrine signalling. The EBEC-EBF co-culture model described herein will offer the opportunity to investigate epithelial-mesenchymal cell interactions and underlying disease mechanisms in the equine airways, thereby leading to a better understanding of their relevance to pathophysiology and treatment of equine and human asthma.

In vitro drusen model - three-dimensional spheroid culture of retinal pigment epithelial cells.

Age-related macular degeneration (AMD) is a leading cause of blindness in people over 50 years of age in many developed countries. Drusen are yellowish extracellular deposits beneath retinal pigment epithelium (RPE) found in aging eyes and considered as a biomarker of AMD. However, the biogenesis of drusen has not been elucidated. We reported previously that multicellular spheroids of human RPE cells constructed a well-differentiated monolayer of RPE with a Bruch's membrane. We determined that RPE spheroids exhibited drusen formation between the RPE and Bruch's membrane with expression of many drusen-associated proteins, such as amyloid ß and complement components, the expression of which was altered by a challenge with oxidative stress. Artificial lipofuscin-loaded RPE spheroids yielded drusen more frequently. In the current study, we showed that drusen originates from the RPE. This culture system is an attractive tool for use as an in vitro drusen model, which might help elucidate the biogenesis of drusen and the pathogenesis of related diseases, such as AMD.

The primate fovea: Structure, function and development.

A fovea is a pitted invagination in the inner retinal tissue (fovea interna) that overlies an area of photoreceptors specialized for high acuity vision (fovea externa). Although the shape of the vertebrate fovea varies considerably among the species, there are two basic types. The retina of many predatory fish, reptilians, and birds possess one (or two) convexiclivate fovea(s), while the retina of higher primates contains a concaviclivate fovea. By refraction of the incoming light, the convexiclivate fovea may function as image enlarger, focus indicator, and movement detector. By centrifugal displacement of the inner retinal layers, which increases the transparency of the central foveal tissue (the foveola), the primate fovea interna improves the quality of the image received by the central photoreceptors. In this review, we summarize ‒ with the focus on Müller cells of the human and macaque fovea ‒ data regarding the structure of the primate fovea, discuss various aspects of the optical function of the fovea, and propose a model of foveal development. The "Müller cell cone" of the foveola comprises specialized Müller cells which do not support neuronal activity but may serve optical and structural functions. In addition to the "Müller cell cone", structural stabilization of the foveal morphology may be provided by the 'z-shaped' Müller cells of the fovea walls, via exerting tractional forces onto Henle fibers. The spatial distribution of glial fibrillary acidic protein may suggest that the foveola and the Henle fiber layer are subjects to mechanical stress. During development, the foveal pit is proposed to be formed by a vertical contraction of the centralmost Müller cells. After widening of the foveal pit likely mediated by retracting astrocytes, Henle fibers are formed by horizontal contraction of Müller cell processes in the outer plexiform layer and the centripetal displacement of photoreceptors. A better understanding of the molecular, cellular, and mechanical factors involved in the developmental morphogenesis and the structural stabilization of the fovea may help to explain the (patho-) genesis of foveal hypoplasia and macular holes.

Complete genome sequence of Pseudoalteromonas phage vB_PspS-H40/1 (formerly H40/1) that infects Pseudoalteromonas sp. strain H40 and is used as biological tracer in hydrological transport studies.

Pseudoalteromonas phage vB_PspS-H40/1 is a lytic phage that infects Pseudoalteromonas sp. strain H40. Both, the phage and its host were isolated in the 1970s from seawater samples collected from the North Sea near the island of Helgoland, Germany. The phage particle has an icosahedral capsid with a diameter of ~43 to 45 nm and a long non-contractile tail of ~68 nm in length, a typical morphology for members of the Siphoviridae family. The linear dsDNA genome of Pseudoalteromonas phage vB_PspS-H40/1 has a sequence length of 45,306 bp and a GC content of 40.6%. The genome has a modular structure and contains a high proportion of sequence information for hypothetical proteins, typically seen in phage genome sequences. This is the first report of the complete genome sequence of this lytic phage, which has been frequently used since the 1990s as biological tracer in hydrogeological transport studies.

Ethyl Pyruvate: An Anti-Microbial Agent that Selectively Targets Pathobionts and Biofilms.

The microbiota has a strong influence on health and disease in humans. A causative shift favoring pathobionts is strongly linked to diseases. Therefore, anti-microbial agents selectively targeting potential pathogens as well as their biofilms are urgently demanded. Here we demonstrate the impact of ethyl pyruvate, so far known as ROS scavenger and anti-inflammatory agent, on planktonic microbes and biofilms. Ethyl pyruvate combats preferably the growth of pathobionts belonging to bacteria and fungi independent of the genera and prevailing drug resistance. Surprisingly, this anti-microbial agent preserves symbionts like Lactobacillus species. Moreover, ethyl pyruvate prevents the formation of biofilms and promotes matured biofilms dissolution. This potentially new anti-microbial and anti-biofilm agent could have a tremendous positive impact on human, veterinary medicine and technical industry as well.

Decline of microtubule-associated protein tau after experimental stroke in differently aged wild-type and 3xTg mice with Alzheimer-like alterations.

Stroke therapies are still limited to a minority of patients. Considering time-dependent aspects of stroke, the penumbra concept describes the transition from functional to permanent tissue damage. Thereby, the role of cytoskeletal elements, as for instance microtubules with associated tau remains poorly understood and is therefore not yet considered for therapeutic approaches. This study explored the expression of microtubule-associated protein tau related to neuronal damage in stroke-affected brain regions. Wild-type and triple-transgenic mice of 3, 7 and 12months of age and with an Alzheimer-like background underwent experimental stroke. After 24h, brain sections were used for immunofluorescence labeling of tau and Neuronal Nuclei (NeuN). Potential functional consequences of cellular alterations were explored by statistical relationships to the general health condition, i.e. neurobehavioral deficits and loss of body weight. Immunoreactivity for whole tau decreased significantly in ischemic areas, while the decline at the border zone was more drastic for tau-immunoreactivity compared with the diminished NeuN labeling. Quantitative analyses confirmed pronounced sensitivity for tau-immunoreactivity in the ischemic border zone. Decline of tau- as well as NeuN-immunoreactivity correlated with body weight loss during the 24-h observation period. In conclusion, microtubule-associated protein tau was robustly identified as a highly sensitive cytoskeletal constitute under ischemic conditions, suggesting a pivotal role during the transition process toward long-lasting tissue damage. Consequently, cytoskeletal elements appear as promising targets for novel therapeutic approaches with the objective to impede ischemia-induced irreversible cellular degradation.

Freeze-thaw cycles enhance decellularization of large tendons.

The use of decellularized tendon tissue as a scaffold for tendon tissue engineering provides great opportunities for future clinical and current research applications. The aim of this study was to assess the effect of repetitive freeze-thaw cycles and two different detergents, t-octyl-phenoxypolyethoxyethanol (Triton X-100) and sodium dodecyl sulfate (SDS), on decellularization effectiveness and cytocompatibility in large tendons. Freshly collected equine superficial and deep digital flexor tendons were subjected to decellularization according to four different protocols (1 and 2: freeze-thaw cycles combined with either Triton X-100 or SDS; 3 and 4: Triton X-100 or SDS). Decellularization effectiveness was assessed based on the reduction of vital cell counts, histologically visible nuclei, and DNA content. Transmission electron microscopy was performed to evaluate cellular and extracellular matrix integrity. Further, cytocompatibility of scaffolds that had been decellularized according to the protocols including freeze-thaw cycles (protocols 1 and 2) was assessed by seeding the scaffolds with superparamagnetic iron oxide labeled mesenchymal stromal cells and monitoring the cells histologically and by magnetic resonance imaging for two weeks. Decellularization was significantly more effective when using the protocols including freeze-thaw cycles, leaving only roughly 1% residual nuclei and 20% residual DNA, whereas samples that had not undergone additional freeze-thaw cycles contained roughly 20% residual nuclei and 40% residual DNA. No morphological extracellular matrix alterations due to decellularization could be observed. Scaffolds prepared by both protocols including freeze-thaw cycles were cytocompatible, but the cell distribution into the scaffold tended to be better in scaffolds that had been decellularized using freeze-thaw cycles combined with Triton X-100 instead of SDS.

Keratinization of the esophageal epithelium of domesticated mammals.

We studied the esophageal epithelium for keratinization characteristics from samples of domesticated mammals of three nutrition groups (herbivores: horse, cattle, sheep; omnivores: pig, dog, rat; carnivores: cat) using histochemistry (keratins, disulfides), sulfur measurements, and cryo-SEM. Keratins were found in all esophageal layers of all species, except for the equine Stratum corneum. The positive reaction staining of Pan-keratin was remarkable, but decreased in intensity toward the outer layers, whereas in the pig and cat, staining was confined to the corneal layer. The herbivores revealed positive staining reactions in the upper Stratum spinosum, particularly in the sheep. Regarding single keratins, CK6 immunostating was found in most esophageal layers, but only weakly or negatively in the porcine and equine Stratum corneum. CK13 staining was restricted to the sheep and here was found in all layers. CK14 could be detected in the equine and feline Stratum basale, and upper vital layers of the dog and rat. CK17 appeared only in the Stratum spinosum and Stratum granulosum, but in all layers of the dog and cat. Disulfides reacted strongest in the Stratum corneum of the herbivores, as corroborated by the sulfur concentrations in the esophagus. Our study emphasized that keratins are very important for the mechanical stability of the epithelial cells and cell layers of the mammalian esophagus. The role of these keratins in the esophageal epithelia is of specific interest owing to the varying feed qualities and mechanical loads of different nutrition groups, which have to be countered.

Impact of 5-lipoxygenase inhibitors on the spatiotemporal distribution of inflammatory cells and neuronal COX-2 expression following experimental traumatic brain injury in rats.

The inflammatory response following traumatic brain injury (TBI) contributes to neuronal death with poor outcome. Although anti-inflammatory strategies were beneficial in the experimental TBI, clinical translations mostly failed, probably caused by the complexity of involved cells and mediators. We recently showed in a rat model of controlled cortical impact (CCI) that leukotriene inhibitors (LIs) attenuate contusion growth and improve neuronal survival. This study focuses on spatiotemporal characteristics of macrophages and granulocytes, typically involved in inflammatory processes, and neuronal COX-2 expression. Effects of treatment with LIs (Boscari/MK-886), started prior trauma, were evaluated by quantifying CD68(+), CD43(+) and COX-2(+) cells 24h and 72 h post-CCI in the parietal cortex (PC), CA3 region, dentate gyrus (DG) and visual/auditory cortex (v/aC). Correlations were applied to identify intercellular relationships. At 24h, untreated animals showed granulocyte invasion in all regions, decreasing towards 72 h. Macrophages increased from 24h to 72 h post-CCI in PC and v/aC. COX-2(+) neurones showed no temporal changes, except of an increase in the CA3 region at 72 h. Treatment reduced granulocytes at 24h in the pericontusional zone and hippocampus, and macrophages at 72 h in the PC and v/aC. COX-2 expression remained unaffected by LIs, except of time-specific changes in the DG (increase/decrease at 24/72 h). Interrelations confirmed concomitant cellular reactions beyond the initial trauma site. In conclusion, LIs attenuated the cellular inflammatory response following CCI. Future studies have to clarify region-specific effects and explore the potential of a clinically more relevant therapeutic approach applying LIs after CCI.

Three-dimensional spheroidal culture visualization of membranogenesis of Bruch's membrane and basolateral functions of the retinal pigment epithelium.

PURPOSE: Aging changes in the RPE involve lipid accumulation and membranous basal deposits onto the underlying Bruch's membrane, which may be related to AMD. Conventional in vitro cell culture is limited in its ability to observe the epithelial functions on the basal side. The purpose of this study was to develop a three-dimensional culture system to observe basolateral functions of the RPE. METHODS: Isolated human RPE cells were cultured in a viscous medium on a rounded-bottom culture dish, resulting in spheroid formation. The appearance and size of the spheroids were assessed by light microscopy. Spheroids were fixed in 4% paraformaldehyde for immunohistochemistry or sampled for Western blotting. For transmission electron microscopy (TEM) and scanning electron microscopy (SEM), spheroids were postfixed in 1% osmium tetroxide. RESULTS: The spheroids had a differentiated RPE monolayer with a thin elastic layer, a main layer of Bruch's membrane, on their surface and showed outward deposition of lipoproteins with apoB-100. TEM revealed widely spaced collagen, which was identified as condensation of collagen fibrils by SEM. SEM showed deposition of membranous debris and lipid particles, which have been observed in human Bruch's membrane. Western blotting showed expression of RPE differentiation markers and components of Bruch's membrane and RPE lipoproteins. CONCLUSIONS: This model provides direct views of epithelialization processes involving elastogenesis and functions at the basolateral side such as lipoprotein deposition and may elucidate not only unknown epithelial behaviors but also the pathogenesis of RPE-related diseases.

Photonic crystal light collectors in fish retina improve vision in turbid water.

Despite their diversity, vertebrate retinae are specialized to maximize either photon catch or visual acuity. Here, we describe a functional type that is optimized for neither purpose. In the retina of the elephantnose fish (Gnathonemus petersii), cone photoreceptors are grouped together within reflecting, photonic crystal-lined cups acting as macroreceptors, but rod photoreceptors are positioned behind these reflectors. This unusual arrangement matches rod and cone sensitivity for detecting color-mixed stimuli, whereas the photoreceptor grouping renders the fish insensitive to spatial noise; together, this enables more reliable flight reactions in the fish's dim and turbid habitat as compared with fish lacking this retinal specialization.

Autonomic reactions and peri-interventional alterations in body weight as potential supplementary outcome parameters for thromboembolic stroke in rats.

BACKGROUND: Since several neuroprotectives failed to reproduce promising preclinical results under clinical conditions, efforts emerged to implement clinically relevant endpoints in animal stroke studies. Thereby, insufficient attention was given on autonomic reactions due to experimental stroke, although clinical trials reported on high functional and prognostic impact. This study focused on autonomic consequences and body weight changes in a translational relevant stroke model and investigated interrelations to different outcome measurements. METHODS: Forty-eight rats underwent thromboembolic middle cerebral artery occlusion (MCAO) while recording heart rate (HR) and mean arterial pressure (MAP). After assessing early functional impairment (Menzies score), animals were assigned to control procedure or potentially neuroprotective treatment with normobaric (NBO) or hyperbaric oxygen (HBO). Four or 24 hours after ischemia onset, functional impairment was re-assessed and FITC-albumin administered intravenously obtaining leakage-related blood-brain barrier (BBB) impairment. Body weight was documented prior to MCAO and 4 or 24 hours after ischemia onset. RESULTS: During MCAO, HR was found to increase significantly while MAP decreased. The amount of changes in HR was positively correlated with early functional impairment (P = 0.001): Severely affected animals provided an increase of 15.2 compared to 0.8 beats/minute in rats with low impairment (P = 0.048). Regarding body weight, a decrease of 9.4% within 24 hours after MCAO occurred, but treatment-specific alterations showed no significant correlations with respective functional or BBB impairment. CONCLUSIONS: Future studies should routinely include autonomic parameters to allow inter-group comparisons and better understanding of autonomic reactions due to experimental stroke. Prospectively, autonomic consequences might represent a useful outcome parameter enhancing the methodological spectrum of preclinical stroke studies.

Cracking down on inhibition: selective removal of GABAergic interneurons from hippocampal networks.

Inhibitory (GABAergic) interneurons entrain assemblies of excitatory principal neurons to orchestrate information processing in the hippocampus. Disrupting the dynamic recruitment as well as the temporally precise activity of interneurons in hippocampal circuitries can manifest in epileptiform seizures, and impact specific behavioral traits. Despite the importance of GABAergic interneurons during information encoding in the brain, experimental tools to selectively manipulate GABAergic neurotransmission are limited. Here, we report the selective elimination of GABAergic interneurons by a ribosome inactivation approach through delivery of saporin-conjugated anti-vesicular GABA transporter antibodies (SAVAs) in vitro as well as in the mouse and rat hippocampus in vivo. We demonstrate the selective loss of GABAergic--but not glutamatergic--synapses, reduced GABA release, and a shift in excitation/inhibition balance in mixed cultures of hippocampal neurons exposed to SAVAs. We also show the focal and indiscriminate loss of calbindin(+), calretinin(+), parvalbumin/system A transporter 1(+), somatostatin(+), vesicular glutamate transporter 3 (VGLUT3)/cholecystokinin/CB(1) cannabinoid receptor(+) and neuropeptide Y(+) local-circuit interneurons upon SAVA microlesions to the CA1 subfield of the rodent hippocampus, with interneuron debris phagocytosed by infiltrating microglia. SAVA microlesions did not affect VGLUT1(+) excitatory afferents. Yet SAVA-induced rearrangement of the hippocampal circuitry triggered network hyperexcitability associated with the progressive loss of CA1 pyramidal cells and the dispersion of dentate granule cells. Overall, our data identify SAVAs as an effective tool to eliminate GABAergic neurons from neuronal circuits underpinning high-order behaviors and cognition, and whose manipulation can recapitulate pathogenic cascades of epilepsy and other neuropsychiatric illnesses.