Determination of Diffusion Kinetics of Ketamine in Brain Tissue: Implications for in vitro Mechanistic Studies of Drug Actions

Ketamine has been in use for over 50 years as a general anesthetic, acting primarily through blockade of N-methyl-D-aspartate receptors in the brain. Recent studies have demonstrated that ketamine also acts as a potent and rapid-acting antidepressant when administered at sub-anesthetic doses. However, the precise mechanism behind this effect remains unclear. We examined the diffusion properties of ketamine in brain tissue to determine their effects in in vitro studies related to the antidepressant action of ketamine. Brain slices from adult mice were exposed to artificial cerebrospinal fluid (aCSF) containing ∼17 μM ketamine HCl for varying amounts of time. The amount of ketamine within each slice was then measured by tandem high-performance liquid chromatography – mass spectrometry to characterize the diffusion of ketamine into brain tissue over time. We successfully modeled the diffusion of ketamine into brain tissue using a mono-exponential function with a time constant of τ = 6.59 min. This curve was then compared to a one-dimensional model of diffusion yielding a diffusion coefficient of approximately 0.12 cm2⋅s–1 for ketamine diffusing into brain tissue. The brain:aCSF partition coefficient for ketamine was determined to be approximately 2.76. Our results suggest that the diffusion properties of ketamine have a significant effect on drug concentrations achieved within brain tissue during in vitro experiments. This information is vital to determine the ketamine concentration necessary for in vitro slice preparation to accurately reflect in vivo doses responsible for its antidepressant actions.

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Quantitative secretome analysis establishes the cell type-resolved mouse brain secretome

10.1101/2020.05.22.110023 ◽

2020 ◽

Author(s):

Johanna Tüshaus ◽

Stephan A. Müller ◽

Evans Sioma Kataka ◽

Jan Zaucha ◽

Laura Sebastian Monasor ◽

...

Keyword(s):

Mouse Brain ◽

High Performance ◽

Brain Slices ◽

Large Cell ◽

Cell Type ◽

Cellular Origin ◽

Secretome Analysis ◽

Csf Proteins

AbstractTo understand how cells communicate in the nervous system, it is essential to define their secretome, which is challenging for primary cells because of large cell numbers being required. Here, we miniaturized secretome analysis by developing the high-performance secretome-protein-enrichment-with-click-sugars method (hiSPECS). To demonstrate its broad utility, hiSPECS was used to identify the secretory response of brain slices upon LPS-induced neuroinflammation and to establish the cell type-resolved mouse brain secretome resource using primary astrocytes, microglia, neurons and oligodendrocytes. This resource allowed mapping the cellular origin of CSF proteins and revealed that an unexpectedly high number of secreted proteins in vitro and in vivo are proteolytically-cleaved membrane protein ectodomains. Two examples are neuronally secreted ADAM22 and CD200, which we identified as substrates of the Alzheimer-linked protease BACE1. hiSPECS and the brain secretome resource can be widely exploited to systematically study protein secretion, brain function and to identify cell type-specific biomarkers for CNS diseases.

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Efficacy of enrofloxacin or doxycycline for treatment of Bartonella henselae or Bartonella clarridgeiae infection in cats.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.11.2448 ◽

1997 ◽

Vol 41 (11) ◽

pp. 2448-2455 ◽

Cited By ~ 57

Author(s):

D L Kordick ◽

M G Papich ◽

E B Breitschwerdt

Keyword(s):

Blood Culture ◽

High Performance ◽

Antimicrobial Agents ◽

Bartonella Henselae ◽

Bacterial Load ◽

Treatment Success ◽

In Vitro Susceptibility ◽

Drug Concentrations

Enrofloxacin and doxycycline are antimicrobial agents used to treat bacterial diseases of cats. In vitro susceptibility data indicate that either drug should be effective against Bartonella species. In vivo efficacies of these drugs for eradication of chronic Bartonella henselae or Bartonella clarridgeiae infections were examined in 18 experimentally infected cats and 25 naturally exposed cats treated with enrofloxacin (22.7 mg given orally [PO] every 12 h [q12h] [14 days, n = 10; 28 days, n = 13]) or with doxycycline (25 mg PO q12h [14 days, n = 9; 28 days, n = 8]) or not treated (n = 3). Plasma drug concentrations were determined in experimental cats by high-performance liquid chromatography. Only 23 of 43 cats enrolled ultimately met inclusion criteria. Bacteremia was eliminated for 12 to 25 weeks posttreatment in four of seven cats receiving 14 days of enrofloxacin, five of seven cats receiving 28 days of enrofloxacin, one of six cats receiving 14 days of doxycycline, and one of two cats receiving 28 days of doxycycline. Defining a negative result by blood culture as treatment success may be erroneous; these results may reflect the insensitivity of blood culture or the relapsing nature of Bartonella bacteremia. Our results suggest that MICs obtained with axenic media do not predict antimicrobial activity against intracellular Bartonella, that a long treatment course is required to eliminate infection, and that duration of therapy correlates with pretreatment bacterial load. Given current concern about the development of antimicrobial resistance, we would reserve recommendation for treatment to cats owned by an immunocompromised individual or as an alternative to euthanasia of a pet.

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TMOD-12. THE ROLE OF INTEGRIN α V AND CD44 IN GBM MIGRATION USING HUMAN ORGANOTYPIC SLICES

Neuro-Oncology ◽

10.1093/neuonc/noz175.1111 ◽

2019 ◽

Vol 21 (Supplement_6) ◽

pp. vi265-vi265

Author(s):

Zev Binder ◽

Sarah Hyun Ji Kim ◽

Pei-Hsun Wu ◽

Anjil Giri ◽

Gary Gallia ◽

...

Keyword(s):

Human Brain ◽

Cell Motility ◽

Brain Tissue ◽

Brain Slices ◽

Model System ◽

Model Systems ◽

In Vivo Model ◽

Human Brain Tissue

Abstract Current model systems used for GBM research include traditional in vitro cell line-based assays and in vivo animal studies. In vitro model systems offer the advantages of being easy to use, relatively inexpensive, and fast growing. However, these models lack key elements of the pathology they are attempting to model, including the biochemical and biophysical microenvironment and three-dimensional structure inherent to human brain tissue. In vivo model systems address these limitations, but have restrictions of their own. Species differences may result in non-applicable results and animal experiments are often not designed like clinical trials. Evidence of the limitations of current GBM models is found in the disparity between basic research findings and successful new treatments for GBMs in the clinic. Here we present an alternative model system for the study of human GBM cell motility and invasion, which features advantages of both in vitro and in vivo model systems. Using human organotypic brain slices as scaffolding for tumor growth, we explored the dynamic process of GBM cell invasion within human brain tissue. To demonstrate the utility of the model system, we investigated the effects of depletion of integrin α V (ITGAV) and CD44 on GBM cell motility. These two cell-surface proteins have been identified to have key functions in GBM cell motility. However, knockdown of ITGAV had little effect on tumor cell motility in organotypics while CD44 knockdown significantly reduced cell movement. Finally, we compare motility results from cells in human brain slices to those from cells growing on standard Matrigel and in mouse brain organotypics. We found significant differences in motility depending on the substrate in which the cells were moving. Our findings highlight the physiologic characteristics of human brain organotypics and demonstrate the use of real-time imaging in the ex vivo system.

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Determination of the EC50Amnesic Concentration of Etomidate and Its Diffusion Profile in Brain Tissue

Anesthesiology ◽

10.1097/00000542-200701000-00020 ◽

2007 ◽

Vol 106 (1) ◽

pp. 114-123 ◽

Cited By ~ 42

Author(s):

Claudia Benkwitz ◽

Mark Liao ◽

Michael J. Laster ◽

James M. Sonner ◽

Edmond I. Eger ◽

...

Keyword(s):

Diffusion Coefficient ◽

Fear Conditioning ◽

Brain Tissue ◽

Concentration Profile ◽

Brain Slices ◽

Diffusion Profile ◽

Contextual Fear Conditioning ◽

General Anesthetic ◽

Contextual Fear

Background Etomidate is a widely used general anesthetic that has become a useful tool to investigate mechanisms of anesthetic action in vivo and in brain slices. However, the free aqueous concentration of etomidate that corresponds to amnesia in vivo and the diffusion profile of etomidate in brain slices are not known. Methods The authors assessed the effect of intraperitoneally injected etomidate on contextual fear conditioning in mice. Etomidate concentrations in brain tissue were obtained by high-performance liquid chromatography. Uptake studies in 400-microm-thick brain slices were used to calculate the diffusion and partition coefficients of etomidate. A diffusion model was used to calculate the expected concentration profile within a brain slice as a function of time and depth. The predicted rate of drug equilibration was compared with the onset of electrophysiologic effects on inhibitory circuit function in recordings from hippocampal brain slices. Results Etomidate impaired contextual fear conditioning with an ED50 dose of 11.0+/-0.1 mg after intraperitoneal injection, which corresponded to an EC50 brain concentration of 208+/-9 ng/g. The brain:artificial cerebrospinal fluid partition coefficient was 3.35, yielding an EC50,amnesia aqueous concentration of 0.25 microm. The diffusion coefficient was approximately 0.2x10 cm/s. The development of etomidate action in hippocampal brain slices was compatible with the concentration profile predicted by this diffusion coefficient. Conclusions The free aqueous concentration of etomidate corresponding to amnesia, as defined by impaired contextual fear conditioning in mice, is 0.25 microM. Diffusion of etomidate into brain slices requires approximately an hour to reach 80% equilibration at a typical recording depth of 100 microm. This information will be useful in designing and interpreting in vitro studies using etomidate.

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The Role of Combined Penetration Enhancers in Nasal Microspheres on In Vivo Drug Bioavailability

Pharmaceutics ◽

10.3390/pharmaceutics10040206 ◽

2018 ◽

Vol 10 (4) ◽

pp. 206 ◽

Cited By ~ 8

Author(s):

Giovanna Rassu ◽

Luca Ferraro ◽

Barbara Pavan ◽

Paolo Giunchedi ◽

Elisabetta Gavini ◽

...

Keyword(s):

High Performance ◽

Drug Distribution ◽

Weight Ratio ◽

Penetration Enhancers ◽

Drug Bioavailability ◽

Drug Permeation ◽

Drug Concentrations ◽

Optimal Drug

Microspheres based on both methyl-β-cyclodextrins and chitosan were prepared by spray-drying as nasal formulations of a model polar drug to analyze, firstly, how the composition of the carrier affects drug permeation across synthetic membranes and, secondly, how it induces systemic or brain delivery of the drug. Microparticles with different weight ratios of the two penetration enhancers (10–90, 50–50, 90–10) were characterized with respect to morphology, size, structural composition, water uptake, and the in vitro drug permeation profile. The leader formulation (weight ratio of 50–50) was then nasally administered to rats; systemic and cerebrospinal fluid (CSF) drug concentrations were analyzed by high performance liquid chromatography (HPLC) over time. Microspheres obtained with a single enhancer, methyl-β-cyclodextrins or chitosan, were administered in vivo as a comparison. The in vitro properties of combined microspheres appeared modified with regard to the polymeric matrix ratio. In vivo results suggest that the optimal drug distribution between CSF and bloodstream can be easily obtained by varying the amount of these two penetration enhancers studied in the matrix of nasal microspheres.

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The Action of Glutamic Acid in Hypoglycaemic Coma

Journal of Mental Science ◽

10.1192/bjp.95.401.930 ◽

1949 ◽

Vol 95 (401) ◽

pp. 930-944 ◽

Cited By ~ 16

Author(s):

H. Weil-Malherbe

Keyword(s):

Glutamic Acid ◽

Brain Tissue ◽

Brain Slices ◽

Direct Consequence ◽

Shock Therapy ◽

Blood Stream ◽

Nervous Function ◽

The Brain

The loss of consciousness in hypoglycaemia is generally regarded as a direct consequence of the fact that the brain cells are being increasingly deprived of glucose, their principal fuel. The prompt relief of symptoms by glucose administration led to a number of investigations on the effect of other substrates known to sustain the respiration of surviving brain slices in vitro. Amongst these are various mono- and disaccharides, and such acids as lactic, pyruvic, succinic or glutamic acid which may be formed from glucose in the course of its metabolism. It appeared, however, that, in contrast to their in vitro action, most of these substances, including glutamic acid, were unable to relieve the symptoms of hypoglycaemia in eviscerated or hepatectomized animals (Bollmann and Mann, 1931; Maddock, Hawkins and Holmes, 1939). Similarly, lactic and pyruvic acids were found to have no effect on the oxygen consumption of the brain or the comatose state of hypoglycaemic patients undergoing insulin shock therapy (Wortis and Goldfarb, 1940; Goldfarb and Wort is, 1941). It has been shown for several substrates, including glutamic acid, that their rate of diffusion from the blood stream into brain tissue was markedly slower than that of glucose, and that therefore the concentration necessary for the maintenance of nervous function was not reached (Klein, Hurwitz and Olsen, 1946; Klein and Olsen, 1947). In harmony with this are the observations of Fried berg and Greenberg (1947), and of Waelsch, Schwerin and Bessman (1949) that intravenously injected glutamic acid is not taken up by brain tissue. The differences between the in vitro and in vivo results seemed to be adequately explained by these experiments.

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Differential Uptake of Volatile Agents into Brain Tissue In Vitro

Anesthesiology ◽

10.1097/00000542-200307000-00021 ◽

2003 ◽

Vol 99 (1) ◽

pp. 122-130 ◽

Cited By ~ 15

Author(s):

Michael A. Chesney ◽

Misha Perouansky ◽

Robert A. Pearce

Keyword(s):

Computational Modeling ◽

Brain Tissue ◽

Tissue Concentration ◽

Hippocampal Slices ◽

Drug Application ◽

Brain Slices ◽

Excitatory Postsynaptic Potential ◽

Drug Actions ◽

Sites Of Action

Background The rate of onset of drug actions in experiments with brain slices in vitro can vary widely. One factor that influences the rate is access to tissue sites of action. To study the effects of the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, also termed 2N in the literature) on physiologic processes under defined tissue concentrations, the authors performed electrophysiologic measurements of the effects of F6 and halothane, measured the uptake of these agents into brain tissue, and performed computational modeling to determine concentration-depth profiles during drug application. Methods Hippocampal brain slices 500 microm thick were prepared from adult rats. Evoked population responses in the CA1 region were obtained using extracellular recordings and electrical stimulation of the Schaffer collateral pathway. F6 (24 microm) and halothane (270 microm) were applied via superfusion for 40 min. Uptake of drug into tissue slices was measured using gas chromatography. Computational modeling was used to obtain estimates of drug diffusion coefficients in brain tissue and to calculate tissue concentration as a function of time and depth during drug application. Results Halothane reduced the amplitude of the evoked population spike and reduced the population excitatory postsynaptic potential slope. F6 had no effect on either measure. Uptake experiments yielded a diffusion coefficient of 0.1 x 10-6 cm2/s for F6 and 0.8 x 10-6 cm2/s for halothane. After 40 min of drug application, the concentration reached at tissue depths from which physiologic signals were obtained, approximately the top 200 microm of the slice, was estimated to be 58% of the final equilibrium value for F6 and 93% for halothane. Conclusions Diffusion into tissue is substantially slower for F6 than for halothane, and its impact is great enough that this must be considered when designing or interpreting in vitro experiments. However, impaired access does not account for the lack of effect of F6 on electrophysiologic responses in rat hippocampal slices.

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Monocytes as Carriers of Magnetic Nanoparticles for Tracking Inflammation in the Epileptic Rat Brain

Current Drug Delivery ◽

10.2174/1567201816666190619122456 ◽

2019 ◽

Vol 16 (7) ◽

pp. 637-644 ◽

Cited By ~ 4

Author(s):

Hadas Han ◽

Sara Eyal ◽

Emma Portnoy ◽

Aniv Mann ◽

Miriam Shmuel ◽

...

Keyword(s):

Brain Tissue ◽

Ex Vivo ◽

In Vivo Studies ◽

Nanoparticle Distribution ◽

Spontaneous Seizures ◽

Systemic Distribution ◽

Hippocampal Ca1 ◽

Pilocarpine Model

Background: Inflammation is a hallmark of epileptogenic brain tissue. Previously, we have shown that inflammation in epilepsy can be delineated using systemically-injected fluorescent and magnetite- laden nanoparticles. Suggested mechanisms included distribution of free nanoparticles across a compromised blood-brain barrier or their transfer by monocytes that infiltrate the epileptic brain. Objective: In the current study, we evaluated monocytes as vehicles that deliver nanoparticles into the epileptic brain. We also assessed the effect of epilepsy on the systemic distribution of nanoparticleloaded monocytes. Methods: The in vitro uptake of 300-nm nanoparticles labeled with magnetite and BODIPY (for optical imaging) was evaluated using rat monocytes and fluorescence detection. For in vivo studies we used the rat lithium-pilocarpine model of temporal lobe epilepsy. In vivo nanoparticle distribution was evaluated using immunohistochemistry. Results: 89% of nanoparticle loading into rat monocytes was accomplished within 8 hours, enabling overnight nanoparticle loading ex vivo. The dose-normalized distribution of nanoparticle-loaded monocytes into the hippocampal CA1 and dentate gyrus of rats with spontaneous seizures was 176-fold and 380-fold higher compared to the free nanoparticles (p<0.05). Seizures were associated with greater nanoparticle accumulation within the liver and the spleen (p<0.05). Conclusion: Nanoparticle-loaded monocytes are attracted to epileptogenic brain tissue and may be used for labeling or targeting it, while significantly reducing the systemic dose of potentially toxic compounds. The effect of seizures on monocyte biodistribution should be further explored to better understand the systemic effects of epilepsy.

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Phytochemical, Analytical and Medicinal Studies of Holoptelea integrifolia Roxb. Planch - A Review

Current Traditional Medicine ◽

10.2174/2215083805666190521103308 ◽

2019 ◽

Vol 5 (4) ◽

pp. 270-277 ◽

Cited By ~ 2

Author(s):

Vijay Kumar ◽

Simranjeet Singh ◽

Ragini Bhadouria ◽

Ravindra Singh ◽

Om Prakash

Keyword(s):

Liquid Chromatography ◽

Thin Layer ◽

Thin Layer Chromatography ◽

High Performance ◽

Biologically Active ◽

Toxicological Studies ◽

Wide Range ◽

Layer Chromatography

Holoptelea integrifolia Roxb. Planch (HI) has been used to treat various ailments including obesity, osteoarthritis, arthritis, inflammation, anemia, diabetes etc. To review the major phytochemicals and medicinal properties of HI, exhaustive bibliographic research was designed by means of various scientific search engines and databases. Only 12 phytochemicals have been reported including biologically active compounds like betulin, betulinic acid, epifriedlin, octacosanol, Friedlin, Holoptelin-A and Holoptelin-B. Analytical methods including the Thin Layer Chromatography (TLC), High-Performance Thin Layer Chromatography (HPTLC), High-Performance Liquid Chromatography (HPLC) and Liquid Chromatography With Mass Spectral (LC-MS) analysis have been used to analyze the HI. From medicinal potency point of view, these phytochemicals have a wide range of pharmacological activities such as antioxidant, antibacterial, anti-inflammatory, and anti-tumor. In the current review, it has been noticed that the mechanism of action of HI with biomolecules has not been fully explored. Pharmacology and toxicological studies are very few. This seems a huge literature gap to be fulfilled through the detailed in-vivo and in-vitro studies.

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A novel PET tracer 18F-deoxy-thiamine: synthesis, metabolic kinetics, and evaluation on cerebral thiamine metabolism status

EJNMMI Research ◽

10.1186/s13550-020-00710-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Changpeng Wang ◽

Siwei Zhang ◽

Yuefei Zou ◽

Hongzhao Ma ◽

Donglang Jiang ◽

...

Keyword(s):

High Performance ◽

Specific Activity ◽

High Accumulation ◽

Metabolic Kinetics ◽

Thiamine Metabolism ◽

Pet Tracer ◽

The Status ◽

The Brain

Abstract Background Some neuropsychological diseases are associated with abnormal thiamine metabolism, including Korsakoff–Wernicke syndrome and Alzheimer’s disease. However, in vivo detection of the status of brain thiamine metabolism is still unavailable and needs to be developed. Methods A novel PET tracer of 18F-deoxy-thiamine was synthesized using an automated module via a two-step route. The main quality control parameters, such as specific activity and radiochemical purity, were evaluated by high-performance liquid chromatography (HPLC). Radiochemical concentration was determined by radioactivity calibrator. Metabolic kinetics and the level of 18F-deoxy-thiamine in brains of mice and marmosets were studied by micro-positron emission tomography/computed tomography (PET/CT). In vivo stability, renal excretion rate, and biodistribution of 18F-deoxy-thiamine in the mice were assayed using HPLC and γ-counter, respectively. Also, the correlation between the retention of cerebral 18F-deoxy-thiamine in 60 min after injection as represented by the area under the curve (AUC) and blood thiamine levels was investigated. Results The 18F-deoxy-thiamine was stable both in vitro and in vivo. The uptake and clearance of 18F-deoxy-thiamine were quick in the mice. It reached the max standard uptake value (SUVmax) of 4.61 ± 0.53 in the liver within 1 min, 18.67 ± 7.04 in the kidney within half a minute. The SUV dropped to 0.72 ± 0.05 and 0.77 ± 0.35 after 60 min of injection in the liver and kidney, respectively. After injection, kidney, liver, and pancreas exhibited high accumulation level of 18F-deoxy-thiamine, while brain, muscle, fat, and gonad showed low accumulation concentration, consistent with previous reports on thiamine distribution in mice. Within 90 min after injection, the level of 18F-deoxy-thiamine in the brain of C57BL/6 mice with thiamine deficiency (TD) was 1.9 times higher than that in control mice, and was 3.1 times higher in ICR mice with TD than that in control mice. The AUC of the tracer in the brain of marmosets within 60 min was 29.33 ± 5.15 and negatively correlated with blood thiamine diphosphate levels (r = − 0.985, p = 0.015). Conclusion The 18F-deoxy-thiamine meets the requirements for ideal PET tracer for in vivo detecting the status of cerebral thiamine metabolism.

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