Label-free observation of DNA-encoded liposome fusion by surface plasmon resonance

Assembly and fusion between different populations of lipid nanoparticles was mediated by membrane-anchored lipidated nucleic acid (LiNA) strands and observed using surface plasmon resonance (SPR) as a label-free real-time assay. Irreversible membrane fusion was distinguished from reversible assembly by enzymatical cleavage of dsDNA tethers in situ. The assay enables user-friendly monitoring and application of membrane fusion in the context of liposomal drug delivery or synthetic biology.

Impact of different oral treatments on the composition of the supragingival plaque microbiome

Background

Dental plaque consists of a diverse microbial community embedded in a complex structure of exopolysaccharides. Dental biofilms form a natural barrier against pathogens but lead to oral diseases in a dysbiotic state.

Objective

Using a metaproteome approach combined with a standard plaque-regrowth study, this pilot study examined the impact of different concentrations of lactoperoxidase (LPO) on early plaque formation, and active biological processes.

Design

Sixteen orally healthy subjects received four local treatments as a randomized single-blind study based on a cross-over design. Two lozenges containing components of the LPO-system in different concentrations were compared to a placebo and Listerine®. The newly formed dental plaque was analyzed by mass spectrometry (nLC-MS/MS). 

Results

On average 1,916 metaproteins per sample were identified, which could be assigned to 116 genera and 1,316 protein functions. Listerine® reduced the number of metaproteins and their relative abundance, confirming the plaque inhibiting effect. The LPO-lozenges triggered mainly higher metaprotein abundances of early and secondary colonizers as well as bacteria associated with dental health but also periodontitis. Functional information indicated plaque biofilm growth.

Conclusion

In conclusion, the mechanisms on plaque biofilm formation of Listerine® and the LPO-system containing lozenges are different. In contrast to Listerine®, the lozenges led to a higher bacterial diversity.

Lipid-Modified Peptide Nucleic Acids: Synthesis and Application to Programmable Liposome Fusion

Peptide nucleic acids (PNAs) can be modified with aliphatic lipid chains and designed to be water soluble and able to spontaneously insert into phospholipid bilayers. Liposomes with 1.5% negatively charged POPG can be driven to fuse and mix their inner content volumes via functionalization with such lipidated peptide nucleic acids (LiPNAs). During fusion, only low amounts of leakage occur (<5%). We describe here the synthesis and purification of such LiPNAs using an automated peptide synthesizer and the preparation of LiPNA functionalized liposomes. Further, we describe the measurement of LiPNA-induced fusion using a fluorescence-based assay for the content mixing between a liposome population with an encapsulated self-quenching fluorescent dye (SRB) and a buffer-filled liposome population.

Bottom-Up Community Proteome Analysis of Saliva Samples and Tongue Swabs by Data-Dependent Acquisition Nano LC-MS/MS Mass Spectrometry

Analysis using mass spectrometry enables the characterization of metaproteomes in their native environments and overcomes the limitation of proteomics of pure cultures. Metaproteomics is a promising approach to link functions of currently actively expressed genes to the phylogenetic composition of the microbiome in their habitat. In this chapter, we describe the preparation of saliva samples and tongue swabs for nLC-MS/MS measurements and their bioinformatic analysis based on the Trans-Proteomic Pipeline and Prophane to study the oral microbiome .

The prevalence and patient outcomes of adult primary hypercholesterolaemia and dyslipidaemia in the UK: a longitudinal retrospective study using a primary care dataset from 2008 to 2018

Background

Cardiovascular disease (CVD) remains the leading cause of death and morbidity in Europe and United Kingdom (UK). Increased low-density lipoprotein cholesterol (LDL-C), implicated in primary hypercholesterolaemia and mixed dyslipidaemia (PH/MD), is an extensively studied risk factor, with proven direct and linear causality of CVD. Lowering LDL-C remains a primary goal in the treatment and prevention of atherosclerotic CVD.

Objectives

This study aimed to quantify adult prevalence and incidence of PH/MD in the UK.

Methods

We used an anonymised dataset covering primary care practices across the UK, accessed through the Clinical Practice Research Datalink (CPRD GOLD). Ethics approval was sought and provided (Protocol 19_238R). Using a validated set of clinical codes as well as pre-treatment lipid profile levels for total cholesterol (TC) (&gt;8 mmol/L), LDL-C (&gt;4.9 mmol/L), we calculated prevalent and new adult cases starting from 2009 to 2018. Our denominator population was the CPRD GOLD GP-registered adult population each calendar year, adjusted for mortality.

Results

There were 1,514,916 adults in the CPRD GOLD GP register for the period from 2009 to 2018. During that period there were 354,444 patients diagnosed with PH/MD. Males comprised 46.5%, mean age on diagnosis was 58.2 years. Mean follow-up time was 104 months. The annual prevalence of PH/MD increased from 2009 to 2019 (see graph). The overall prevalence across the period was 22.7%. Mean annual incidence across the decade was 1.7%. Mean LDL-C levels were 4.7 mmol/L and mean TC level was 6.8 mmol/L. In this cohort, 15.9% experienced cardiovascular events (see table). Nearly all patients have used lipid lowering therapies. Only 2.2% achieved at least 40% reduction of LDL-C from baseline.

Conclusions

The prevalence of PH/MD has been increasing despite the availability of interventions. Considering guidelines, only a small proportion of patients have achieved LDL-C goals.

Est prevalence of PH/MD in the UK

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Daiichi Sankyo Europe, Health iQ Ltd

Light-triggered switching of liposome surface charge directs delivery of membrane impermeable payloads in vivo

Surface charge plays a fundamental role in determining the fate of a nanoparticle, and any encapsulated contents, in vivo. Herein, we describe, and visualise in real time, light-triggered switching of liposome surface charge, from neutral to cationic, in situ and in vivo (embryonic zebrafish). Prior to light activation, intravenously administered liposomes, composed of just two lipid reagents, freely circulate and successfully evade innate immune cells present in the fish. Upon in situ irradiation and surface charge switching, however, liposomes rapidly adsorb to, and are taken up by, endothelial cells and/or are phagocytosed by blood resident macrophages. Coupling complete external control of nanoparticle targeting together with the intracellular delivery of encapsulated (and membrane impermeable) cargos, these compositionally simple liposomes are proof that advanced nanoparticle function in vivo does not require increased design complexity but rather a thorough understanding of the fundamental nano-bio interactions involved.

Lipidated Polyaza Crown Ethers as Membrane Anchors for DNA-Controlled Content Mixing between Liposomes

The ability to manipulate and fuse nano-compartmentalized volumes addresses a demand for spatiotemporal control in the field of synthetic biology, for example in the bottom-up construction of (bio)chemical nanoreactors and for the interrogation of enzymatic reactions in confined space. Herein, we mix entrapped sub-attoliter volumes of liposomes (~135 nm diameter) via lipid bilayer fusion, facilitated by the hybridization of membrane-anchored lipidated oligonucleotides. We report on an improved synthesis of the membrane-anchor phosphoramidites that allows for a flexible choice of lipophilic moiety. Lipid-nucleic acid conjugates (LiNAs) with and without triethylene glycol spacers between anchor and the 17 nt binding sequence were synthesized and their fusogenic potential evaluated. A fluorescence-based content mixing assay was employed for kinetic monitoring of fusion of the bulk liposome populations at different temperatures. Data obtained at 50 °C indicated a quantitative conversion of the limiting liposome population into fused liposomes and an unprecedently high initial fusion rate was observed. For most conditions and designs only low leakage during fusion was observed. These results consolidate LiNA-mediated membrane fusion as a robust platform for programming compartmentalized chemical and enzymatic reactions.

Metaproteomics analysis of microbial diversity of human saliva and tongue dorsum in young healthy individuals

Background: The human oral microbiome influences initiation or progression of diseases like caries or periodontitis. Metaproteomics approaches enable the simultaneous investigation of microbial and host proteins and their interactions to improve understanding of oral diseases.

Objective: In this study, we provide a detailed metaproteomics perspective of the composition of salivary and tongue microbial communities of young healthy subjects.

Design: Stimulated saliva and tongue samples were collected from 24 healthy volunteers, subjected to shotgun nLC-MS/MS and analyzed by the Trans-Proteomic Pipeline and the Prophane tool.

Results: 3,969 bacterial and 1,857 human proteins could be identified from saliva and tongue, respectively. In total, 1,971 bacterial metaproteins and 1,154 human proteins were shared in both sample types. Twice the amount of bacterial metaproteins were uniquely identified for the tongue dorsum compared to saliva. Overall, 107 bacterial genera of seven phyla formed the microbiome. Comparative analysis identified significant functional differences between the microbial biofilm on the tongue and the microbiome of saliva.

Conclusion: Even if the microbial communities of saliva and tongue dorsum showed a strong similarity based on identified protein functions and deduced bacterial composition, certain specific characteristics were observed. Both microbiomes exhibit a great diversity with seven genera being most abundant.

Programmable fusion of liposomes mediated by lipidated PNA

We recently reported a DNA-programmed fusion cascade enabling the use of liposomes as nanoreactors for compartmentalized chemical reactions. This communication reports an alternative and robust strategy based on lipidated peptide nucleic acids (LiPs). LiPs enabled fusion of liposomes with remarkable 31% efficiency at 50 °C with low leakage (5%).

Comparative analysis of Salivette® and paraffin gum preparations for establishment of a metaproteomics analysis pipeline for stimulated human saliva

The value of saliva as a diagnostic tool can be increased by taxonomic and functional analyses of the microbiota as recently demonstrated. In this proof-of-principle study, we compare two collection methods (Salivette® (SV) and paraffin gum (PG)) for stimulated saliva from five healthy participants and present a workflow including PG preparation which is suitable for metaproteomics.

Efficient liposome fusion mediated by lipid–nucleic acid conjugates

Highly efficient fusion and content mixing of liposomes encoded by lipidated oligonucleotides (LiNAs). “Hot fusion of biomembranes” – a low leakage process at elevated temperature.

A peptide resource for the analysis of Staphylococcus aureus in host-pathogen interaction studies

Staphylococcus aureus is an opportunistic human pathogen, which can cause life-threatening disease. Proteome analyses of the bacterium can provide new insights into its pathophysiology and important facets of metabolic adaptation and, thus, aid the recognition of targets for intervention. However, the value of such proteome studies increases with their comprehensiveness. We present an MS-driven, proteome-wide characterization of the strain S. aureus HG001. Combining 144 high precision proteomic data sets, we identified 19 109 peptides from 2088 distinct S. aureus HG001 proteins, which account for 72% of the predicted ORFs. Peptides were further characterized concerning pI, GRAVY, and detectability scores in order to understand the low peptide coverage of 8.7% (19 109 out of 220 245 theoretical peptides). The high quality peptide-centric spectra have been organized into a comprehensive peptide fragmentation library (SpectraST) and used for identification of S. aureus-typic peptides in highly complex host-pathogen interaction experiments, which significantly improved the number of identified S. aureus proteins compared to a MASCOT search. This effort now allows the elucidation of crucial pathophysiological questions in S. aureus-specific host-pathogen interaction studies through comprehensive proteome analysis. The S. aureus-specific spectra resource developed here also represents an important spectral repository for SRM or for data-independent acquisition MS approaches. All MS data have been deposited in the ProteomeXchange with identifier PXD000702 (http://proteomecentral.proteomexchange.org/dataset/PXD000702).

Form of dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 1A nonphosphorylated at tyrosine 145 and 147 is enriched in the nuclei of astroglial cells, adult hippocampal progenitors, and some cholinergic axon terminals

Compelling lines of evidence indicate that overexpression of dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A) in subjects with trisomy 21 (Down syndrome[DS]) contributes to the abnormal structure and function of the DS brain. In the present study, we used a novel, phospho-dependent antibody recognizing DYRK1A only with nonphosphorylated tyrosine 145 and 147 (DYRK1A Tyr-145/147P(-)), to investigate the expression pattern of this DYRK1A species in trisomic and disomic human and mouse brains. Immunoblotting and dephosphorylation experiments demonstrated higher levels of DYRK1A Tyr-145/147P(-) in postnatal trisomic brains in comparison with controls (by ∼40%) than those of the DYRK1A visualized by three other N- and C-terminally directed antibodies to DYRK1A. By immunofluorescence, the immunoreactivity to DYRK1A Tyr-145/147P(-) was the strongest in the nuclei of astroglial cells, which contrasted with the predominantly neuronal localization of DYRK1A visualized by the three other antibodies to DYRK1A we used. In addition, DYRK1A Tyr-145/147P(-) was enriched in the nuclei of neuronal progenitors and newly born neurons in the adult hippocampal proliferative zone and also occurred in some cholinergic axonal terminals. Our data show a distinctive expression pattern of DYRK1A forms nonphosphorylated at Tyr-145 and Tyr-147 in the brain tissue and suggest that DS subjects may exhibit not only upregulation of total DYRK1A, but also more subtle differences in phosphorylation levels of this kinase in comparison with control individuals.

Pre-clinical and Clinical Study Results for the Coracto™ Rapamycin-eluting Stent – A New-generation Drug-eluting Stent

First- and second-generation drug-eluting stents (DES) have successfully decreased the rate of restenosis compared with bare-metal stents (BMS); however, the incidence of late stent thrombosis, which mostly occurs after the implantation of DES, and chronic restenosis are still important medical problems. A new generation of DES, the Coracto™ rapamycin-eluting stent (RES), has the potential to reduce late stent thrombosis and the risk of chronic restenosis due to the totally biodegradable polymer providing a controlled drug release. In brief, the results of the two pre-clinical studies proved the safety and efficacy of the Coracto RES. In addition, in a clinical study comparing the Coracto RES and the Constant BMS, patients receiving the Coracto RES with chronic total occlusion (CTO) had a 71% decrease in the relative risk of restenosis after six months and an 82% reduction in target vessel revascularisation (TVR) after 24 months. The late stent thrombosis of the Coracto RES was 0% at 24-month follow-up. This article provides an overview of the data obtained from pre-clinical animal experiments using a porcine and rabbit model of stenting and a recently conducted clinical study demonstrating the safety and efficacy of the Coracto RES.

Abnormal expression of synaptic proteins and neurotrophin-3 in the Down syndrome mouse model Ts65Dn

Down syndrome (DS) results from triplication of the whole or distal part of human chromosome 21. Persons with DS suffer from deficits in learning and memory and cognitive functions in general, and, starting from early development, their brains show dendritic and spine structural alterations and cell loss. These defects concern many cortical brain regions as well as the hippocampus, which is known to play a critical role in memory and cognition. Most of these abnormalities are reproduced in the mouse model Ts65Dn, which is partially trisomic for the mouse chromosome 16 that is homologous to a portion of human chromosome 21. Thus, Ts65Dn is widely utilized as an animal model of DS. To better understand the molecular defects underlying the cognitive and particularly the memory impairments of DS, we investigated whether the expression of several molecules known to play critical roles in long-term synaptic plasticity and long-term memory in a variety of species is dysregulated in either the neonatal brain or adult hippocampus of Ts65Dn mice. We found abnormal expression of the synaptic proteins synaptophysin, microtubule-associated protein 2 (MAP2) and cyclin-dependent kinase 5 (CDK5) and of the neurotrophin-3 (NT-3). Both the neonatal brain and adult hippocampus revealed significant abnormalities. These results suggest that a dysregulation in the expression of neurotrophins as well as proteins involved in synaptic development and plasticity may play a potential role in the neural pathology of DS in humans.

Immunogold study of effects of prenatal exposure to lipopolysaccharide and/or valproic acid on the rat blood-brain barrier vessels

The involvement of blood microvessels, representing the anatomic site of the blood-brain barrier (BBB), in brain damage induced by prenatal exposure to lipopolysaccharide (LPS) and/or valproic acid (VPA) was studied in four-week-old rats. The immunogold procedure was applied for localization at the ultrastructural level of endogenous albumin and glucose transporter (GLUT-1) in three brain regions: cerebral cortex, cerebellum and hippocampus. Four groups of rats were used: (1) untreated control, (2) prenatally VPA-treated, (3) prenatally LPS-treated, and (4) prenatally LPS- and VPA-treated. The functional state of the BBB was evaluated as follows: (a) by its tightness, i.e., permeability to blood-borne albumin, and (b) by the expression of GLUT-1 in the endothelial cells (ECs). Using morphometry, the labelling density for GLUT-1 was recorded over luminal and abluminal plasma membranes of the ECs, also providing information on their functional polarity. No extensive increase of vascular permeability and/or any considerable dysfunction of the BBB in experimental groups nos. 2 and 3 were observed, although in solitary vascular profiles, increased endocytosis or even transcytosis of albumin by ECs was noted. In experimental group no. 4, some vascular profiles showed scanty leakage (microleakage), manifested by the presence of immunosignals for albumin in the perivascular area. Although some fluctuations in the expression of GLUT-1 occurred in all experimental groups, especially in group no. 3, a most pronounced and significant diminution of the labelling density, in all three regions of the brain, was observed in group no. 4. This finding suggests the synergistic action of prenatally applied LPS and VPA that affects specific transport functions of glucose in the microvascular endothelium. The diminished or disturbed supply of glucose to selected brain regions can be one of the factors leading to previously observed behavioral disturbances in similarly treated rats.

Effectiveness and tolerability of a homoeopathic remedy compared with conventional therapy for mild viral infections

Treatments for mild viral infections are usually directed at providing symptomatic relief. The effectiveness of the homoeopathic remedy Gripp-Heel was compared with that of conventional treatments in a prospective, observational cohort study in 485 patients with mild viral infections and symptoms such as fever, headache, muscle pain, cough or sore throat. Practitioners specialised in homoeopathy or conventional treatment, or practised both to similar extents. As evaluated by the practitioners, the homoeopathic therapy was effective to similar or greater degree than the conventional therapies: 67.9% of patients were considered asymptomatic at the end of Gripp-Heel therapy vs. 47.9% of patients in the control group. Practitioners judged homoeopathic treatments as 'successful' in 78.1% of cases vs. 52.2% for conventional therapies. Tolerability and compliance were good in both treatment groups, with the verdict 'very good' given for 88.9% of patients in the homoeopathic group vs. 38.8% in the conventional treatment group.

Fmr1 knockout mouse has a distinctive strain-specific learning impairment

The Fmr1 gene knockout mouse is a model for the human Fragile X mental retardation syndrome. Fmr1 knockout mice with a C57BL/6-129/OlaHsd hybrid background have been reported to have only a very mild deficiency in learning the Morris water maze task. We compared the effect of this knockout mutation on learning in mice with either an FVB/N-129/OlaHsd hybrid background or a C57BL/6 background. When FVB-129 mice were tested in a cross-shaped water maze task, the knockout mice showed a pronounced deficiency in their ability to learn the position of a hidden escape platform in comparison to normal littermates. In contrast, knockout mice with a C57BL/6 background learned the maze just as well as their normal littermates. Fear conditioning did not reveal differences between knockout and normal mice in either background. These results show that silencing the Fmr1 gene clearly interfered with learning a specific visuospatial task in FVB/N-129 hybrid mice but not in C57BL/6 mice. The strain dependence may model the influence of genetic background in the human Fragile X syndrome.

Effect of a single embryonic exposure to alcohol on glucose transporter (GLUT-1) distribution in brain vessels of aged mouse

Distribution of glucose transporter (GLUT-1) in brain microvascular endothelium, representing the anatomic site of the blood-brain barrier (BBB), was studied with electron microscopy in 24-month-old mice, which had been exposed prenatally (on 9th day of gestation) to a single teratogenic dose of ethanol. Offspring of mice that had received an equivalent volume of isocaloric dextrose served as controls. Sections of brain samples embedded at low temperature in hydrophilic resin Lowicryl K4M were exposed to anti-GLUT-1 antiserum followed by gold-labelled secondary antibodies. By using morphometry, the labelling density was recorded over luminal and abluminal plasma membranes of the endothelial cells of blood microvessels supplying four brain regions: cortex, hippocampus, cerebellum and olfactory bulb. We found that the density of immunosignals for GLUT-1, represented by colloidal gold particles, was unchanged in the olfactory bulb and slightly lowered in the abluminal plasmalemma of the vascular endothelium in the cerebral cortex of the ethanol-treated mice. In contrast, statistical analysis using Mann-Whitney U-test revealed that in the hippocampus and cerebellum, the density of immunolabelling of both plasma membranes of microvascular endothelial cells was significantly lowered in the ethanol-treated mice. These findings suggest that prenatally applied ethanol had a different influence on the vasculature supplying different brain regions. In effect, the inefficient supply of glucose to selected brain regions can be one of the factors leading to the previously observed deficit in long-term memory in a similar alcohol-treated group of mice.

Micromolar concentrations of steroids and of aldosterone antagonists inhibit the outwardly rectifying chloride channel with different kinetics

We used the patch-clamp technique to analyse the open/close kinetics of single, outwardly rectifying, intermediate-conductance (ORIC) Cl- channels from cultured epithelial cells under control conditions and in presence of different inhibitors. As observed previously in excised inside/out patches under control conditions, the switching kinetics were characterized by one open-state time constant (tau0 is approximately 30 ms) and three closed-state time constants (tau(cl)is approximately = to 0.2 ms, tau(c2) is approximately = 2 ms and tau(c3) is approximately = 60 ms). Aldosterone, six further steroids and two aldosterone antagonists inhibited channel open probability (NPo) concentration dependently with the potency at 10 micromol/l increasing in the sequence: hydrocortisone, corticosterone, P-oestradiol, cortisone, aldosterone, testosterone, progesterone, canrenone, spironolactone. Although all substances decreased tau(o), neither the steroids nor the aldosterone antagonists affected tau(cl), tau(c2) or tau(c3) or induced additional transitions with additional time constants. Instead, the steroids increased the prevalence of tau(c2) in the dwell-time histograms and the aldosterone antagonists increased the prevalence of tau(c3), both in a concentration-dependent manner. These observations may be explained by a model in which one open state leads to one of three closed states with rate constants alpha, beta and gamma, and in which beta or gamma increase under the influence of steroids or aldosterone antagonists, respectively. Cytosol, which contains a Cl- channel inhibitor of unknown molecular structure, (Krick et al., Pflügers Arch 418:491, 1991) was also tested, but the results did not conform to the blocker mechanisms described above. This shows that there are even further modes of channel inhibition and argues against the cytosolic Cl- channel inhibitor being a steroid.

Effects of valproate derivatives II. Antiepileptic efficacy in relation to chemical structures of valproate sugar esters

The structure effect relationships of derivatives of the antiepileptically active ester of valproate (VPA) 3,4:5,6-Di-O-isopropylidene-1-O-(2-propylpentanoyl)-D-mannitol (1) have been studied using intracellular recording to record the membrane potential of single neurons (buccal ganglia, Helix pomatia). Epileptiform activity was induced by the epileptogenic drug pentylenetetrazol. The effects of several derivatives on epileptiform activity were compared with those of the relay compound 1. Most of the synthesized agents decreased the duration of paroxysmal depolarization shifts (PDS) and increased their repetition rate. It was considered that a decreased the duration of PDS is antiepileptic and an increased repetition rate is pro-epileptic. Compared with the effects of compound 1, the following relationships were found: (1) Derivatives containing glucitol or galactitol were of similar antiepileptic potency. (2) Introduction of pyranoses or furanoses rendered the substances inactive or even pro-epileptic. (3) VPA in position 1 and 6 at the sugar acted as an antiepileptic whereas in position 3 and 4 it proved to be ineffective. (4) Replacement of VPA by ethylhexanoyl reduced the antiepileptic potency slightly and pivaloyl strongly. (5) Replacement of isopropylidene bridges by penta-O-acetyl or cyclohexylidene residues led to largely inactive substances. (6) Compounds having isopropylidene bridges in position 2,4;3,5 proved to be antiepileptic whereas bridges especially in positions 2,3:4,5 slightly enhanced epileptic activities.

Infantile handling eliminates reversal learning deficit in rats prenatally exposed to alcohol

Prenatal exposure to ethanol results in learning deficits and alters physiological response to stress. Neonatal handling and stimulation. on the other hand, produce long-lasting physiological and behavioral changes in response to stress. To determine whether early handling, consisting of daily separation and tactile stimulation for the first 3 weeks, can modify fetal alcohol effects on learning ability of young adult rats, offspring of rats chronically exposed to ethanol throughout pregnancy and control animals were trained in a T-maze to learn a position response and then to reverse the learned response. The nonhandled, ethanol-treated rats were deficient on reversal, but the ethanol-treated rats that were handled during the first 3 weeks of postnatal development showed no deficit in learning to reverse their previously learned responses. Postnatal handling had no effect on acquisition in alcohol-treated rats. Neither reversal nor acquisition was affected by infantile handling in pair-fed or normal control animals. Early handling may have eliminated the reversal deficit in the ethanol-treated offspring by altering their physiological and behavioral reactivity to stress.

Protective effects of fetal neocortical transplants on cognitive function and neuron size in rats with congenital micrencephaly

The rat with micrencephaly, produced by prenatal exposure to methylazoxymethanol, provides a useful model to study neurobehavioral abnormalities associated with congenital brain defects. The micrencephalic animals have a life-long learning impairment. As they age, their already impaired learning competence deteriorates further. To determine whether the aging-associated functional deterioration could be ameliorated by a neural transplant, micrencephalic rats bearing solid transplants of normal fetal neocortical tissue since infancy were evaluated on a visual pattern discrimination learning at 15 months and a spatial navigation test at 24 months of age. The transplant-bearing rats learned both tasks significantly better than the micrencephalic rats without transplants. Morphometric analyses revealed that cortical pyramidal neurons were larger in the transplant-bearing rats than in micrencephalic rats without transplants. The life-long presence of a transplant appeared to have protected the micrencephalic brain against aging-associated deterioration. This is the first demonstration that a neural transplant, placed in a congenitally defective infant brain, can ameliorate aging-associated cognitive deficits.

Cl- channel inhibition by glibenclamide is not specific for the CFTR-type Cl- channel

As long as the question of which channels are responsible for cAMP-mediated epithelial Cl- secretion remains unsolved, it is still important to search for specific inhibitors that might help to relate macroscopic to microscopic events. Following the report by Sheppard and Welsh (J Gen Physiol 100: 573, 1992) that glibenclamide inhibits whole-cell Cl- currents in genetically manipulated fibroblasts expressing the cystic fibrosis transmembrane conductance regulator (CFTR), we have studied the effect of glibenclamide on different types of Cl- channels of HT29 and T84 cells at the single-channel level. Our results confirm that micromolar concentrations of glibenclamide inhibit the linear, low-conductance Cl-channel, which appears to represent CFTR and show that the inhibition results from a typical flicker block. However, the same concentrations of glibenclamide inhibit also the outwardly rectifying intermediate conductance Cl- channel which, potentially, may contribute to transepithelial Cl- secretion.

Augmented memory loss in aging mice after one embryonic exposure to alcohol

Prenatal exposure to alcohol can produce behavioral and cognitive deficits even in the absence of dysmorphic facial features. In a mouse model, we tested whether embryonic exposure to alcohol could exacerbate functional loss as animals age. Normal-appearing offspring were selected from litters produced by C57Bl/6J mice that had been gavaged with one teratogenic dose (5.8 g/kg) of ethyl alcohol during organogenesis on the 9th day of gestation. In adulthood, the offspring suffered a deficit in long-term retention, but not acquisition, of a place learning task. Although barely detectable in young adults, the retention deficit was severe in aging mice. These findings demonstrate that the functional deficits resulting from embryonic exposure to alcohol can interact with those of aging.

Alzheimer neuropathology in mentally retarded adults: statistical independence of regional amyloid plaque and neurofibrillary tangle densities

The densities of neurofibrillary tangles (NFT) and neuritic plaques (NP) were assessed quantitatively in the brains of 303 mentally retarded adults 23 to 90 years of age at the time of their deaths (mean = 59.5 years). Cases with Down's syndrome, hydrocephalus and metabolic disorders were excluded from the study. Examinations of frontal, temporal, parietal, and occipital cortex, as well as hippocampus and parahippocampal gyrus were made in every case. NPs and/or NFTs were observed within the brains of 163 cases (53.8%). Detailed analyses indicated that NP density within all brain regions examined was positively related to age, with the largest age associated increases in density seen in frontal and temporal regions. In contrast, NFT density increased with age only within hippocampus and parahippocampal gyrus, but not neocortex. In addition, NP lesions within neocortex were more diffusely distributed across regions for older compared to younger cases, while no similar age-associated change in the topography of NFTs was observed. Finally, factor analyses of the combined NP and NFT data indicated that, while strong correlations existed across the various brain regions for measures of NP and NFT densities, considered separately, there was virtually no indication of regional associations between these two types of lesions. While these data, from cases with mental retardation, cannot be generalized directly to the nonretarded population, they provide strong evidence that models of Alzheimer pathogenesis must take into account the fact that regional densities of NPs and NFTs, and, therefore, the underlying processes associated with formation of these lesions, can be largely independent.

Premature decline in Morris water maze performance of aging micrencephalic rats

The rat with methylazoxymethanol-induced micrencephaly is a useful animal model of congenital brain defects and associated cognitive impairment. Born with profound morphological and neurochemical alterations in the forebrain, it shows impaired ability to learn mazes. In order to determine how an animal with such a developmentally damaged brain would function in old age, Long-Evans rats 6, 15, and 24 months of age were tested for their ability to learn to locate a hidden platform in the Morris water maze. The performance of micrencephalic rats of all ages was impaired on acquisition, retention, and transfer trials. Moreover, the magnitude of their acquisition deficit increased with age. It remains to be determined whether the premature decline of the micrencephalic rat in learning the task simply reflects a greater impact on an already compromised brain by neuron loss characteristic of aging brains or whether the prenatal insult alters some basic processes resulting in premature aging.

Visual discrimination by rats with transplacentally induced micrencephaly

Long-Evans rats with micrencephaly induced by prenatal exposure to methylazoxymethanol acetate and normal controls were trained in a two-choice box to discriminate between stimuli of different brightness (black vs. white) or pattern (horizontal vs. vertical alternating black-and-white stripes). Mild footshock was used to motivate the rats to learn. The micrencephalic rats were impaired in learning the pattern, but not brightness discrimination. These results confirm and extend similar findings with micrencephalic Wistar rats by another laboratory. The visual discrimination performance of micrencephalic rats was similar to that reported for normal rats with lesions in the visual cortical areas.

Neocortical transplants in the micrencephalic rat brain: morphology and behavior

Normal fetal (E18) neocortical tissue transplanted into the hypoplastic posterior neocortex of infant (10 +/- 2-day-old) rats with transplacentally induced micrencephaly developed into very large, healthy, and permanent transplants. Although the cellular organization within the transplants rarely resembled that of normal rat neocortex, the transplants formed a broad area of interface with the host brain and established fiber connections with it. When tested at 2 months and 1-year-of-age, the presence of the transplant had no significant effect on the typically abnormal performance of micrencephalic rats on two tests of unspecific function, open field activity and maze learning. However, a small group of micrencephalic rats in whom the transplant tissue had failed to fill in the small brain lesions inescapably inflicted during surgery, showed greater behavioral deficits than the micrencephalic controls, suggesting that the transplant had corrected the lesion effect.

Behavior and neurobehavioral teratology using the ferret

A behavioral profile of the ferret is presented for those who would like to use this animal in behavioral teratology and toxicology, or other disciplines involving behavior. We have reviewed neurobehavioral teratology of lisencephalic ferrets and neuropsychology of ferrets sustaining frontal lesions, as well as most of the studies of "normal" ferret behavior that have appeared in the research literature. Emphasis is placed on discussion of the tests used and how ferrets behaved on them. The behaviors discussed include spatial (maze) learning, delayed response, visual discrimination learning, discrimination learning sets, schedule maintained behavior, shock avoidance learning and spontaneously occurring behaviors, such as ambulation in open field, spontaneous alternation and species specific behaviors. Although the use of the ferret in behavioral experiments is not yet extensive and large gaps exist in our knowledge about the basic functional capacities of this animal, the ferret is unquestionably well suited for behavioral studies.