Demonstration of Hypomethylation of Proteins in the Brain of Pigs (but Not in Rats) Associated with Chronic Vitamin B12 Inactivation

1995 ◽  
Vol 88 (4) ◽  
pp. 471-477 ◽  
Author(s):  
M. McKeever ◽  
A. Molloy ◽  
P. Young ◽  
S. Kennedy ◽  
D. G. Kennedy ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Methionine Synthase ◽  
Nerve Tissue ◽  
Subacute Combined Degeneration ◽  
Vitro Assay ◽  
Clinically Normal ◽  
Critical Components ◽  
The Brain ◽  
Methylation Ratio

1. Pigs treated with nitrous oxide for periods of 1, 2 and 4 months demonstrated markedly reduced levels of methionine synthase and concomitant reduction in the ratio of S-adenosylmethionine to S-adenosylhomocysteine, the methylation ratio, at all time intervals. 2. Both ‘O’ and ‘N’ methylations were significantly reduced in pigs after 4 months in nitrous oxide but not after shorter periods. 3. Hypomethylation correlated with the development of clinical ataxia, but was absent when the pigs were clinically normal. It also only occurred when the S-adenosylmethionine level fell. 4. Rats maintained in nitrous oxide for 4 months showed a marked reduction of methionine synthase but no reduction in the methylation ratio or in brain hypomethylation. None of the rats became clinically ataxic. 5. Using an exogenous protein as a methyl group acceptor, it was demonstrated in an in vitro assay that the methyltransferase enzymes responsible for brain ‘O’ and ‘N’ methylation were not affected per se by nitrous oxide treatment. 6. It is concluded that reduction of the methylation ratio in the brain of pigs as a consequence of methionine synthase inhibition leads to brain hypomethylation. This hypomethylation could affect critical components of nerve tissue, inducing the vacuolar myelopathic changes seen in the spinal cord of these animals, which mimic those of subacute combined degeneration in man.

An Abnormal Methylation Ratio Induces Hypomethylation In Vitro in the Brain of Pig and Man, But Not in Rat

1995 ◽  
Vol 88 (1) ◽  
pp. 73-79 ◽  
Author(s):  
M. McKeever ◽  
A. Molloy ◽  
D. G. Weir ◽  
P. B. Young ◽  
D. G. Kennedy ◽  
...  
Keyword(s):  
Vitamin B12 ◽  
In Vitro Assay ◽  
Methyltransferase Activity ◽  
Vitro Assay ◽  
Neural Tissues ◽  
Protein Methyltransferases ◽  
The Brain ◽  
Methylation Ratio

1. The ratio of the methyl donor, S-adenosylmethionine, to the co-product, S-adenosylhomocysteine (the methylation ratio) is known to control the activity of methyltransferases in tissues. Inactivation of the vitamin B12-dependent enzyme, methionine synthase, reduces the methylation ratio in rats and pigs in vivo. 2. We have determined the effect that such alterations have on neural protein ‘O’ and ‘N’ methyltransferases using an in vitro assay in rats, pigs and humans in the presence of the normal methylation ratio and the abnormal methylation ratios found experimentally in vivo in rats and pigs. 3. The methylation ratio found in the neural tissues of vitamin B12-inactivated pigs significantly inhibits the protein methyltransferases of pigs and humans. 4. By contrast, the altered methylation ratio found in vitamin B12-inactivated rats only marginally inhibits the equivalent rat methyltransferases. 5. This is consistent with the induction of a myelopathy by such treatment in pigs and humans, but not in the rat. 6. Dietary supplements of methionine given to vitamin B12-inactivated pigs have been shown to prevent the myelopathy in vivo by both elevating the neural S-adenosylmethionine level and resetting the methylation ratio. We find in our in vitro assay that these events reinstate the methyltransferase activity to near normal levels, thus explaining its protective effect in vivo.

scholarly journals In vitro inactivation of methionine synthase by nitrous oxide.

1986 ◽  
Vol 261 (34) ◽  
pp. 15823-15826
Author(s):  
V Frasca ◽  
B S Riazzi ◽  
R G Matthews
Keyword(s):  
Nitrous Oxide ◽  
Methionine Synthase

HORMONES MODULATE THE CONCENTRATION OF CYTOPLASMIC PROGESTIN RECEPTORS IN THE BRAIN OF MALE RING DOVES (STREPTOPELIA RISORIA)

1980 ◽  
Vol 86 (2) ◽  
pp. 251-261 ◽  
Author(s):  
J. BALTHAZART ◽  
J. D. BLAUSTEIN ◽  
M. F. CHENG ◽  
H. H. FEDER
Keyword(s):  
Testosterone Propionate ◽  
Brain Regions ◽  
Posterior Hypothalamus ◽  
Vitro Assay ◽  
Progestin Receptors ◽  
Streptopelia Risoria ◽  
Oestradiol Benzoate ◽  
Ring Doves ◽  
The Brain

A cytoplasmic progestin receptor has been characterized in the brain of castrated ring doves using an in-vitro assay that measures the binding of a synthetic progestin, [3H]17α,21-dimethyl-19-nor-pregna-4,9-diene-3,20-dione(promegestone; R5020). The affinity of the receptor was similar in both the hyperstriatum and the hypothalamus (Kd≃4 × 10−10 mol/l). Its concentration was higher in the anterior hypothalamus–preoptic area (63 ± 4 fmol/mg (s.e.m.) protein) than in other brain regions (posterior hypothalamus, 33 ± 5; hyperstriatum, 28 ± 3; midbrain, 17 ± 4 fmol/mg protein; n = 7). Progesterone and R5020 competed well for binding but oestradiol and 5β-dihydrotestosterone did not. Corticosterone and, to a lesser extent, testosterone and 5α-dihydrotestosterone competed for binding but much higher concentrations were required than for progestins. Injections of testosterone (200 pg testosterone propionate daily for 7 days) significantly increased the concentration of progestin receptors in the anterior and posterior hypothalamus without having any significant effect on other brain areas. Shorter treatment, lasting for 2 days, with testosterone propionate (200 μg daily), 5α-dihydrotestosterone (200 μg daily) or oestradiol benzoate (50 μg daily) did not always cause this increase but seven injections of oestradiol benzoate (50 pg daily for 7 days) were even more effective than seven injections of testosterone propionate (200 μg daily for 7 days). These data suggested that the sensitivity to progesterone of the brain of the bird changes as a consequence of increases in the level of testosterone in the circulation.

L-Ascorbic acid and lysosomal acid hydrolase activities of guinea pig liver and brain

1978 ◽  
Vol 56 (5) ◽  
pp. 352-356 ◽  
Author(s):  
Susan K. Hoehn ◽  
Julian N. Kanfer
Keyword(s):  
Ascorbic Acid ◽  
Acid Phosphatase ◽  
Guinea Pig ◽  
Lysosomal Hydrolases ◽  
Vitro Assay ◽  
Ascorbic Acid Deficiency ◽  
Acid Deficiency ◽  
Dietary Treatments ◽  
The Brain

The effects of L-ascorbic acid deficiency on guinea pig hepatic and brain lysosomal hydrolases were examined. In general, hepatic β-N-acetylhexosaminidase, β-D-glucoronidase, α-D-galactosidase, α-D-mannosidase, and acid phosphatase were elevated in scorbutic animals. This appears to be independent of the starved state. Brain β-D-glucoronidase and acid phosphatase followed a similar pattern to that observed with the liver enzymes, but brain β-N-acetylhexosaminidase was not affected by L-ascorbic acid deficiency. Supplementing the in vitro assay system with L-ascorbic acid decreased the activity of hepatic β-N-acetylhexosaminidase somewhat but had no effect on the brain enzyme. Serum total β-N-acetylhexosaminidase was unaffected by dietary treatments although the activity of β-N- acetylhexosaminidase A tended to increase in the scorbutic animals. Subcellular fractions were obtained from the three groups of animals and the recoveries of protein, β-N-acetylhexosaminidase, and glucose-6-phosphatase estimated.

scholarly journals Test for Detection of Disease-Associated Prion Aggregate in the Blood of Infected but Asymptomatic Animals

2006 ◽  
Vol 14 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Binggong Chang ◽  
Xin Cheng ◽  
Shaoman Yin ◽  
Tao Pan ◽  
Hongtao Zhang ◽  
...  
Keyword(s):  
Early Stage ◽  
Mule Deer ◽  
Enzyme Linked Immunosorbent Assay ◽  
Specific Enzyme ◽  
Wasting Disease ◽  
Vitro Assay ◽  
Naturally Occurring ◽  
The Brain ◽  
Intraperitoneal Inoculation

ABSTRACT We have developed a sensitive in vitro assay for detecting disease-associated prion aggregates by combining an aggregation-specific enzyme-linked immunosorbent assay (AS-ELISA) with the fluorescent amplification catalyzed by T7 RNA polymerase technique (FACTT). The new assay, named aggregation-specific FACTT (AS-FACTT), is much more sensitive than AS-ELISA and could detect prion aggregates in the brain of mice as early as 7 days after an intraperitoneal inoculation of PrPSc. However, AS-FACTT was still unable to detect prion aggregates in blood of infected mice. To further improve the detection limit of AS-FACTT, we added an additional prion amplification step (Am) and developed a third-generation assay, termed Am-A-FACTT. Am-A-FACTT has 100% sensitivity and specificity in detecting disease-associated prion aggregates in blood of infected mice at late but still asymptomatic stages of disease. At a very early stage, Am-A-FACTT had a sensitivity of 50% and a specificity of 100%. Most importantly, Am-A-FACTT also detects prion aggregates in blood of mule deer infected with the agent causing a naturally occurring prion disease, chronic wasting disease. Application of this assay to cattle, sheep, and humans could safeguard food supplies and prevent human contagion.

scholarly journals Neuroprotective properties of the C-Jun N-terminal kinase (JNK) inhibitor in hypoxic hypoxia

2019 ◽  
Vol 18 (2) ◽  
pp. 80-88
Author(s):  
G. N. Zyuz’kov ◽  
E. V. Udut ◽  
L. A. Miroshnichenko ◽  
T. Ju. Poljakova ◽  
E. V. Simanina ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Subventricular Zone ◽  
Nerve Tissue ◽  
Hypoxic Exposure ◽  
Experimental Animals ◽  
Neuronal Stem Cells ◽  
Orientation And Exploratory Behavior ◽  
The Brain

The aim of the study was to reveal the influence of the JNK inhibitor on the induction of disturbances in the psychoneurological status of experimental animals in the modeling of posthypoxic encephalopathy and to reveal the mechanisms of its action related to the functioning of the neural stem cells of the brain. Materials and methods. The experiments were performed on 64 male outbred mice. Posthypoxic encephalopathy was modeled in non-native mice with hypoxia of the hermetic volume. The JNK inhibitor was administered to mice subcutaneously at a dose of 15 mg/kg once before hypoxic exposure. We studied the neuropsychiatric status, the content of neuronal stem cells in the subventricular zone of the brain of experimental animals, and the direct effect of the JNK inhibitor on intact neural stem cells in vitro. Results. The expressed cerebroprotective action of the pharmacological agent was revealed, which consisted of normalizing the indices of orientation and exploratory behavior and conditioned activity in experimental animals. These effects developed against a background of a significant increase in the content of neural stem cells in the subventricular zone of the brain. In the experiments in vitro, a direct stimulating effect of the JNK inhibitor on neural stem cells was found. Conclusions. The obtained results showed a neuroprotective action of the JNK inhibitor. At the same time, the prevention and compensation of the development of disturbances in the activity of the central nervous system is based on the preservation of the ability of the nerve tissue to repair andassociated with the functioning of resident neural stem cells.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

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