scholarly journals In vivo activity of glutaminase in the brain of hyperammonaemic rats measured by 15N nuclear magnetic resonance

1995 ◽  
Vol 305 (1) ◽  
pp. 329-336 ◽  
Author(s):  
K Kanamori ◽  
B D Ross
Keyword(s):  
Brain Homogenate ◽  
Inhibitory Effect ◽  
Intact Brain ◽  
Strong Inhibitory Effect ◽  
Glutamine Synthesis ◽  
Gaba Synthesis ◽  
The Brain

The in vivo activity of phosphate-activated glutaminase (PAG) was measured in the brain of hyperammonaemic rat by 15N n.m.r. Brain glutamine was 15N-enriched by intravenous infusion of 15NH4+ until the concentration of [5-15N]glutamine reached 6.1 mumol/g. Further glutamine synthesis was inhibited by intraperitoneal injection of methionine-DL-sulphoximine, an inhibitor of glutamine synthetase, and the infusate was changed to 14NH4+ during observation of decrease in brain [5-15N]glutamine due to PAG and other glutamine utilization pathways. Progressive decrease in brain [5-15N]glutamine, PAG-catalysed production of 15NH4+ and its subsequent assimilation into glutamate by glutamate dehydrogenase were monitored in vivo by 15N n.m.r. Brain [5-15N]glutamine (15N enrichment of 0.35-0.50) decreased at a rate of 1.2 mumol/h per g of brain. The in vivo PAG activity, determined from the observed rate and the quantity of 15NH4+ produced and subsequently assimilated into glutamate and aspartate, was 0.9-1.3 mumol/h per g. This activity is less than 1.1% of the reported activity in vitro measured in rat brain homogenate at a 10 mM concentration of the activator Pi. Inhibition by ammonia (brain level 1.4 mumol/g) alone does not account for the observed low activity in vivo. The result strongly suggests that, in intact brain, PAG activity is maintained at a low level by a suboptimal in situ concentration of Pi and the strong inhibitory effect of glutamate. The observed PAG activity in vivo is lower than the reported in vivo activity of glutamate decarboxylase which converts glutamate into gamma-aminobutyrate (GABA). The result suggests that PAG-catalysed hydrolysis of glutamine is not the sole provider of glutamate used for GABA synthesis.

Spectrophotometry of b-type cytochromes in rat brain in vivo and in vitro

1989 ◽  
Vol 256 (4) ◽  
pp. C840-C848 ◽  
Author(s):  
C. A. Piantadosi
Keyword(s):  
Low Temperature ◽  
Rat Brain ◽  
Spectral Characteristics ◽  
Brain Homogenate ◽  
Brain Mitochondria ◽  
Oxidation Reduction ◽  
Intact Brain

Terminal oxidase inhibitors such as cyanide (CN) and carbon monoxide (CO) produce different absorption changes in the intact brain, suggesting different mitochondrial responses to the inhibitors. In the present study, the nature of the cytochromes involved in CO and CN responses in vivo was investigated by low-temperature spectroscopy of rat brain, frozen in situ, and of preparations of brain homogenate and isolated mitochondria. Comparison of the spectra from different preparations at the high resolution afforded by low-temperature spectroscopy indicated that absorption responses to CO in vivo originated from mitochondrial b cytochromes. Further detailed spectral analysis of mitochondrial preparations revealed three CN-insensitive b cytochromes in nonsynaptic brain mitochondria; one cytochrome could be reduced by succinate in the presence of CN, the second could be reduced by succinate plus ATP, and the third could be reduced only by anaerobiosis. The spectral characteristics of the mitochondrial b cytochromes, when compared with spectra from CO-exposed brain tissue frozen in situ, strongly implicated the energy-dependent cytochrome b in the oxidation-reduction (redox) responses caused by CO in vivo.

scholarly journals A study on Dowager Cixi’s Yanling-Yishou-Dan of Qing Dynasty in a Japanese laboratory of biochemistry and molecular biology in 1990s: An attempt for TCM modernization

2021 ◽  
pp. 1-21
Author(s):  
Jiankang Liu
Keyword(s):  
Qing Dynasty ◽  
Brain Homogenate ◽  
Modern Technology ◽  
Toxicity Tests ◽  
Brain Functions ◽  
Great Progress ◽  
Theoretical Evidence ◽  
The Brain

Traditional Chinese Medicine (TCM) modernization has been proposed for many years, but the progress is still slow due to both ideological and technical obstacles. When I went to Japan in 1989, I found Japan has made a great progress on TCM by using modern technology. Therefore, I have studied a fine extract prepared from medicinal herbs (renamed Yi-Zhi-Yi-Shou, YZYS), a prescription of Dowager Cixi’s Yanling-Yishou-Dan of Qing Dynasty, with the current drug investigation strategies. I examined its antioxidant activity both in vitro and in vivo. The in-vitro studies found that YZYS possesses strong antioxidant capacity, such as scavenging various kinds of free radicals, and inhibits free radical-induced peroxidation of brain homogenate, microsomes, mitochondria, amino acids, deoxyribose and DNA. The in-vivo study with immobilization-induced emotional stress in rats, showed that YZYS effectively inhibits stress-induced stomach ulcers and oxidative damage in plasma and the brain. In addition, YZYS is shown to be non-toxic in both acute and chronic toxicity tests. These studies demonstrate that YZYS is a potent natural antioxidant and offer theoretical evidence for the beneficial effect of YZYS on health and brain functions, and that TCM prescriptions can be studied scientifically as modern medical drugs.

Kanamycin Inhibits Cochlear-Renal ODC in Neonatal Rats

1992 ◽  
Vol 107 (4) ◽  
pp. 501-510 ◽  
Author(s):  
Andrew T. Lyos ◽  
William E. Winter ◽  
Charles M. Henley
Keyword(s):  
Organ Of Corti ◽  
Lateral Wall ◽  
Inhibitory Effect ◽  
Polyamine Biosynthesis ◽  
Key Enzyme ◽  
Old Rats ◽  
In Vivo Effects ◽  
The Brain

Ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, is important in development and regeneration. We hypothesize that aminoglycoside inhibition of ODC mediates developmental hypersensitivity to aminoglycoside ototoxicity. Kanamycin effects on ODC activity (decarboxylation of ornithine) in vitro were determined in the postmitochondriai fraction of cochlear and renal homogenates from 11-day-old rats. Kanamycin inhibited cochlear and renal ODC by an uncompetitive mechanism. For the cochlear enzyme, the inhibitor constant (Ki) for kanamycin was 99 ± 25 (μmol/L; for the renal enzyme, the Ki = 1.5 ± 0.1 mmol/L. In vivo effects of kanamycin on cochlear, renal, brain ODC activity were determined in rats treated with kanamycin (400 mg/kg/day, intramuscularly) or saline during postnatal days 11 through 20, the hypersensitive period for ototoxicity. Rats were killed on postnatal days 12,14,16, and 20 and ODC was assayed. Kanamycin significantly inhibited ODC in the lateral wall-organ of Corti and kidney (ANOVA α = 0.05), but had no effect on cochlear nerve and no consistent inhibitory effect in the brain. These results suggest that ODC is a potential target of kanamycin in susceptible tissues and may be a contributing factor in developmental sensitivity to the drug by inhibiting repair and developmental processes mediated by ODC.

scholarly journals Isoflurane abolishes spontaneous firing of serotonin neurons and masks their pH/CO2 chemosensitivity

2015 ◽  
Vol 113 (7) ◽  
pp. 2879-2888 ◽  
Author(s):  
Cory A. Massey ◽  
Kimberly E. Iceman ◽  
Sara L. Johansen ◽  
Yuanming Wu ◽  
Michael B. Harris ◽  
...  
Keyword(s):  
Brain Slices ◽  
Inhibitory Effect ◽  
Firing Frequency ◽  
Spontaneous Firing ◽  
Subsequent Decrease ◽  
Serotonin Neurons ◽  
Underlying Mechanisms

Serotonin (5-hydroxytryptamine, 5-HT) neurons from the mouse and rat rostral medulla are stimulated by increased CO2 when studied in culture or brain slices. However, the response of 5-HT neurons has been variable when animals are exposed to hypercapnia in vivo. Here we examined whether halogenated inhalational anesthetics, which activate TWIK-related acid-sensitive K+ (TASK) channels, could mask an effect of CO2 on 5-HT neurons. During in vivo plethysmography in mice, isoflurane (1%) markedly reduced the hypercapnic ventilatory response (HCVR) by 78–96% depending upon mouse strain and ambient temperature. In a perfused rat brain stem preparation, isoflurane (1%) reduced or silenced spontaneous firing of medullary 5-HT neurons in situ and abolished their responses to elevated perfusate Pco2. In dissociated cell cultures, isoflurane (1%) hyperpolarized 5-HT neurons by 6.52 ± 3.94 mV and inhibited spontaneous firing. A subsequent decrease in pH from 7.4 to 7.2 depolarized neurons by 4.07 ± 2.10 mV, but that was insufficient to reach threshold for firing. Depolarizing current restored baseline firing and the firing frequency response to acidosis, indicating that isoflurane did not block the underlying mechanisms mediating chemosensitivity. These results demonstrate that isoflurane masks 5-HT neuron chemosensitivity in vitro and in situ and markedly decreases the HCVR in vivo. The use of this class of anesthetic has a particularly potent inhibitory effect on chemosensitivity of 5-HT neurons.

scholarly journals Inhibition of Plasmodium sporogonic stages by ivermectin and other avermectins

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Raquel Azevedo ◽  
António M. Mendes ◽  
Miguel Prudêncio
Keyword(s):  
Direct Action ◽  
Inhibitory Effect ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Insecticidal Effect ◽  
Strong Inhibitory Effect ◽  
The Impact ◽  
Shed Light

Abstract Background The transmissible forms of Plasmodium parasites result from a process of sporogony that takes place inside their obligatory mosquito vector and culminates in the formation of mammalian-infective parasite forms. Ivermectin is a member of the avermectin family of endectocides, which has been proposed to inhibit malaria transmission due its insecticidal effect. However, it remains unclear whether ivermectin also exerts a direct action on the parasite’s blood and transmission stages. Methods We employed a rodent model of infection to assess the impact of ivermectin treatment on P. berghei asexual and sexual blood forms in vivo. We then made use of a newly established luminescence-based methodology to evaluate the activity of ivermectin and other avermectins against the sporogonic stages of P. berghei parasites in vitro independent of their role on mosquito physiology. Results Our results show that whereas ivermectin does not affect the parasite’s parasitemia, gametocytemia or exflagellation in the mammalian host, several members of the avermectin family of compounds exert a strong inhibitory effect on the generation and development of P. berghei oocysts. Conclusions Our results shed light on the action of avermectins against Plasmodium transmission stages and highlight the potential of these compounds to help prevent the spread of malaria.

scholarly journals The effects in vitro of hypoglycaemia and recovery from anoxia on synaptosomal metabolism

1982 ◽  
Vol 206 (3) ◽  
pp. 433-439 ◽  
Author(s):  
S A K Harvey ◽  
R F G Booth ◽  
J B Clark
Keyword(s):  
Adenine Nucleotide ◽  
Brain Slices ◽  
Substrate Oxidation ◽  
Metabolic Rates ◽  
Acetylcholine Synthesis ◽  
Metabolic Indices ◽  
The Brain

Synaptosomes from several regions of the rat brain were found to exhibit half-maximal rates of 14CO2 output and [14C]acetylcholine synthesis from D-[U-14C]glucose at glucose concentrations approx. 50-fold lower than those required by the brain in situ. However, synaptosomal acetylcholine synthesis was found not to be directly proportional to substrate oxidation as measured by 14CO2 output. When synaptosomes had been exposed to anoxia in vitro, their metabolic indices (14CO2 and [14C]acetylcholine synthesis, and adenine nucleotide levels) were found not to be significantly different from control aerobic values, unless they had been subjected to veratridine depolarization. This is in accord with previous findings that neither the absolute metabolic rates nor the vulnerability to hypoxic damage exhibited by brain in situ is reflected by brain slices in vitro, unless these are stimulated by depolarization. The use of synaptosomes as a model for synaptic damage in vivo is discussed.

scholarly journals DEVELOPMENT OF RIVASTIGMINE LOADED SELF ASSEMBLED NANOSTRUCTURES OF NONIONIC SURFACTANTS FOR BRAIN DELIVERY

2021 ◽  
pp. 205-215
Author(s):  
SARASWATHI T. S. ◽  
MOTHILAL M.
Keyword(s):  
Entrapment Efficiency ◽  
Sem Analysis ◽  
Intranasal Route ◽  
Onset Of Action ◽  
Perfusion Studies ◽  
In Situ Nasal Gel ◽  
The Brain

Objective: Aim of the study is to develop rivastigmine-loaded niosomal in situ gel via the intranasal route to the brain by crossing the Blood-Brain Barrier. For the treatment of Alzheimer’s disease, it provides a speedy onset of action, a faster therapeutic effect, avoidance of the first-pass metabolism, and enhanced bioavailability. Methods: Rivastigmine niosomal in situ nasal gel was developed, refined and tested with the goal of delivering the medicine to the brain via the intranasal route Rivastigmine niosomes were formulated by thin-film hydration technique, optimized using (32) factorial design and characterized for its physicochemical parameters. Rivastigmine-loaded niosomes were further incorporated into Carbopal-934P and HPMC-K4M liquid gelling system to form in situ nasal gel. The resulting solution was evaluated for several parameters including, viscosity at pH 5 and pH 6, gelling capacity and gelling time. Results: Optimized best formulation containing span 60 (A) and cholesterol (B) with (1:0.5) ratio identified from the model developed from Design-Expert®12 software, exhibited Entrapment efficiency (76.5±0.23%), particle size (933.4±0.14 nm), in vitro drug release maximum (68.94±0.26%) at 8th hour and further studied for its characteristics by SEM and TEM showed stable vesicles. Polynomial equations of Y1, Y2, and Y3 were conducted and ANOVA results showed a significant impact (p<0.05) on three levels. In vivo perfusion studies using rat model showed, the niosomes developed has good perfusion compared to pure drug with 27.2% of drug absorption in the brain at the end of 3 h. In vitro permeation of Rivastigmine through the dialysis membrane showed that 60.74% w/w drug permeated after 8 h. The formation of stable vesicles was proved by Zeta potential measurements and SEM analysis. Conclusion: Optimized formulation had greater perfusion and was expected to have a good bioavailability compared to conventional other drug delivery systems.

scholarly journals Favipiravir treatment prolongs the survival in a lethal mouse model intracerebrally inoculated with Jamestown Canyon virus

2021 ◽  
Vol 15 (7) ◽  
pp. e0009553
Author(s):  
Hirofumi Kato ◽  
Mutsuyo Takayama-Ito ◽  
Masaaki Satoh ◽  
Madoka Kawahara ◽  
Satoshi Kitaura ◽  
...  
Keyword(s):  
Antiviral Treatment ◽  
Febrile Illness ◽  
Drug Efficacy ◽  
Vero Cells ◽  
Inhibitory Effect ◽  
N2a Cells ◽  
Jamestown Canyon Virus ◽  
The Brain

Background Jamestown Canyon virus (JCV) is a mosquito-borne orthobunyavirus that causes acute febrile illness, meningitis, and meningoencephalitis, primarily in North American adults. Currently, there are no available vaccines or specific treatments against JCV infections. Methodology/Principal findings The antiviral efficacy of favipiravir (FPV) against JCV infection was evaluated in vitro and in vivo in comparison with that of ribavirin (RBV) and 2’-fluoro-2’-deoxycytidine (2’-FdC). The in vitro inhibitory effect of these drugs on JCV replication was evaluated in Vero and Neuro-2a (N2A) cells. The efficacy of FPV in the treatment of JCV infection in vivo was evaluated in C57BL/6J mice inoculated intracerebrally with JCV, as per the survival, viral titers in the brain, and viral RNA load in the blood. The 90% inhibitory concentrations (IC90) of FPV, RBV, and 2’-FdC were 41.0, 61.8, and 13.6 μM in Vero cells and 20.7, 25.8, and 8.8 μM in N2A cells, respectively. All mice infected with 1.0×104 TCID50 died or were sacrificed within 10 days post-infection (dpi) without treatment. However, mice treated with FPV for 5 days [initiated either 2 days prior to infection (−2 dpi–2 dpi) or on the day of infection (0 dpi–4 dpi)] survived significantly longer than control mice, administered with PBS (p = 0.025 and 0.011, respectively). Moreover, at 1 and 3 dpi, the virus titers in the brain were significantly lower in FPV-treated mice (0 dpi–4 dpi) versus PBS-treated mice (p = 0.002 for both 1 and 3 dpi). Conclusions/Significance Although the intracerebral inoculation route is thought to be a challenging way to evaluate drug efficacy, FPV inhibits the in vitro replication of JCV and prolongs the survival of mice intracerebrally inoculated with JCV. These results will enable the development of a specific antiviral treatment against JCV infections and establishment of an effective animal model.

scholarly journals MyoD-positive myoblasts are present in mature fetal organs lacking skeletal muscle

2001 ◽  
Vol 155 (3) ◽  
pp. 381-392 ◽  
Author(s):  
Jacquelyn Gerhart ◽  
Brian Bast ◽  
Christine Neely ◽  
Stephanie Iem ◽  
Paula Amegbe ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Rt Pcr ◽  
Skeletal Myoblasts ◽  
In Situ Hybridizations ◽  
Fetal Organs ◽  
The Brain

The epiblast of the chick embryo gives rise to the ectoderm, mesoderm, and endoderm during gastrulation. Previous studies revealed that MyoD-positive cells were present throughout the epiblast, suggesting that skeletal muscle precursors would become incorporated into all three germ layers. The focus of the present study was to examine a variety of organs from the chicken fetus for the presence of myogenic cells. RT-PCR and in situ hybridizations demonstrated that MyoD-positive cells were present in the brain, lung, intestine, kidney, spleen, heart, and liver. When these organs were dissociated and placed in culture, a subpopulation of cells differentiated into skeletal muscle. The G8 antibody was used to label those cells that expressed MyoD in vivo and to follow their fate in vitro. Most, if not all, of the muscle that formed in culture arose from cells that expressed MyoD and G8 in vivo. Practically all of the G8-positive cells from the intestine differentiated after purification by FACS®. This population of ectopically located cells appears to be distinct from multipotential stem cells and myofibroblasts. They closely resemble quiescent, stably programmed skeletal myoblasts with the capacity to differentiate when placed in a permissive environment.

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