scholarly journals Hepatic one-carbon metabolism in early folate deficiency in rats

1993 ◽  
Vol 291 (1) ◽  
pp. 145-149 ◽  
Author(s):  
M Balaghi ◽  
D W Horne ◽  
C Wagner
Keyword(s):  
Enzyme Activity ◽  
De Novo ◽  
Folate Deficiency ◽  
Male Rats ◽  
Control Group ◽  
Deficient Diet ◽  
Ad Libitum ◽  
Deficient Group

Glycine N-methyltransferase (GNMT) is inhibited by 5-methyltetrahydrofolate polyglutamate in vitro. It is believed to play a regulatory role in the synthesis de novo of methyl groups. We have used the amino-acid-defined diet of Walzem and Clifford [(1988) J. Nutr. 118, 1089-1096] to determine whether folate deficiency in vivo would affect GNMT activity, as predicted by the studies in vitro. Weanling male rats were fed on the folate-deficient diet or a folate-supplemented diet pair-fed to the deficient group. A third group was fed on the folate-supplemented diet ad libitum. Development of folate deficiency rapidly resulted in decreased levels of S-adenosylmethionine (SAM) and elevation of S-adenosylhomocysteine (SAH). The ratios of SAM to SAH were 1.8, 2.7 and 1.5 in the deficient group for weeks 2, 3 and 4 of the experiment, and the values were 9.7, 7.1 and 8.9 for the pair-fed control group and 10.3, 8.8 and 8.0 for the control group ad libitum fed. The activity of GNMT was significantly higher in the deficient group than in either of the two control groups at each time period. This was not due to increased amounts of GNMT protein, but reflected an increase in specific enzyme activity. Levels of folate in both the cytosol and mitochondria were severely lowered after only 2 weeks on the diet. The distribution of folate coenzymes was also affected by the deficiency, which resulted in a marked increase in the percentage of tetrahydrofolate polyglutamates in both cytosol and mitochondria and a very large decrease in cytosolic 5-methyltetrahydrofolate. The increased GNMT activity is therefore consistent with decreased folate levels and decreased inhibition of enzyme activity.

FOOD CONSUMPTION AND RECTAL TEMPERATURE IN RATS DURING THIAMINE DEFICIENCY AND REPLETION

1963 ◽  
Vol 41 (12) ◽  
pp. 2463-2471 ◽  
Author(s):  
M. J. Veen ◽  
G. Russell ◽  
G. H. Beaton
Keyword(s):  
Food Consumption ◽  
Rectal Temperature ◽  
Food Restriction ◽  
Control Diet ◽  
Significant Rise ◽  
Male Rats ◽  
Thiamine Hydrochloride ◽  
Deficient Diet ◽  
Ad Libitum ◽  
Deficient Group

Rectal temperature in male rats fell slowly and gradually from ad libitum and pair-led control levels throughout a thiamine depletion period. During this period, food consumption dropped suddenly and sharply to a minimal level. A single oral dose of 50 μg of thiamine hydrochloride produced, within 4 hours, a significant rise (to less than control levels) in rectal temperature and an increase in food consumption within 24 hours. The increase in temperature was independent of the ingestion of food since diet was withheld during the 4 hours following thiamine administration. Subsequent feeding of control diet (containing thiamine) had not further increased the "4-hour" temperature after 24 hours. With continued feeding of control diet, rectal temperature rose to control levels after 3 days. On subsequent withdrawal of dietary thiamine from the deficient group, temperature and food consumption fell as before. When the animals were again repleted with 50 μg thiamine and deficient diet was continued, temperatures rose to the same level reached after the first thiamine administration. A third deprivation and repletion produced identical results.Food restriction alone, in pair-fed control groups, induced an initial elevation of rectal temperature above ad libitum control levels as temperatures in the deficient group were falling, and an eventual decrease below ad libitum control levels only after prolonged food restriction. It is suggested that the initial fall in body temperature in thiamine-deficient rats is not simply a terminal result of food restriction per se, but may reflect alterations in metabolism due to the deficiency.

dSLIM Immunomodulators Induce Anti-Tumor Responses Both In Vitro and In Vivo.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1727-1727
Author(s):  
Manuel Schmidt ◽  
Javier de Cristobal ◽  
Astrid Sander ◽  
Bernadette Brzezicha ◽  
Sven A. König Merediz ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Tumor Cells ◽  
Neutralizing Antibodies ◽  
De Novo ◽  
Tumor Cell Line ◽  
Control Group ◽  
Γδt Cells ◽  
Ifn Γ

Abstract Cytosine-guanine (CpG) motifs containing oligonucleotides (ODN) are commonly used for immunomodulatory purpose in cancer therapy and for the treatment of allergic diseases since they resemble bacterial DNA and serve as “danger signals”. These CpG-ODNs promote predominately a TH1-response with secretion of IL-12 and IFN-γ, In addition their broad potential includes activation of B-cell proliferation, monocyte stimulation and secretion of IgM and IL-6, and stimulation of plasmacytoid DC to produce IFN-α/-β and thus γδT-cells and NK-cells to express CD69 and secrete IFN-γ. Usually phosphorothioate (PS) modifications are to enhance the stability, but these are leading to several side-effects, like severe organ enlargements, morphological changes and immunosuppression in mice. We designed immunomodulatory molecules based on short covalently-closed dumbbell-like structures (dSLIM) to stabilize the DNA without the otherwise necessary PS-modification. To evaluate the anti-tumor effect of the dSLIM molecules we developed an in vitro anti-tumor assay. This assay uses supernatant from dSLIM-activated human PBMCs for incubation with tumor cells in vitro. We observed increased apoptosis and necrosis of the HT-29 tumor cell line after incubation with supernatant from dSLIM-treated PBMC which was significantly higher than the effect of supernatant from non-treated PBMC. In addition, supernatant from dSLIM-treated PBMC increased the expression of HLA-ABC on the tumor cells, a pre-requisite for tumor cell recognition by the immune system. These effects were confirmed with human HEK293 and murine Renca cell lines. Analyzing the effect with neutralizing antibodies to various apoptosis-related cytokines, we observed a crucial role of IFN-γ but not IFN-α or TNFα. To investigate the anti-tumor effects of dSLIM in vivo, we employed a SKH1 murine model which is prone to spontaneous development of papillomas. Using chemicals for initiation and weekly promotion of de novo papilloma development we compared groups of weekly s.c. or i.p. dSLIM injections, respectively, with the PBS control group. The number of papilloma developing mice was significantly lower in the dSLIM groups and the total number of papillomas on all mice was reduced by approximately 50%. In conclusion, we showed that dSLIM immunomodulators exhibit potent anti-tumor effects in vitro and in vivo.

Hepatic AQP9 expression in male rats is reduced in response to PPARα agonist treatment

2015 ◽  
Vol 308 (3) ◽  
pp. G198-G205 ◽  
Author(s):  
Janne Lebeck ◽  
Muhammad Umar Cheema ◽  
Mariusz T. Skowronski ◽  
Søren Nielsen ◽  
Jeppe Praetorius
Keyword(s):  
De Novo ◽  
Transmembrane Protein ◽  
Male Rats ◽  
Glycerol Metabolism ◽  
Free Access ◽  
Peroxisome Proliferator ◽  
Food Treatment ◽  
Pparα Agonist

The peroxisome proliferator receptor α (PPARα) is a key regulator of the hepatic response to fasting with effects on both lipid and carbohydrate metabolism. A role in hepatic glycerol metabolism has also been found; however, the results are somewhat contradictive. Aquaporin 9 (AQP9) is a pore-forming transmembrane protein that facilitates hepatic uptake of glycerol. Its expression is inversely regulated by insulin in male rodents, with increased expression during fasting. Previous results indicate that PPARα plays a crucial role in the induction of AQP9 mRNA during fasting. In the present study, we use PPARα agonists to explore the effect of PPARα activation on hepatic AQP9 expression and on the abundance of enzymes involved in glycerol metabolism using both in vivo and in vitro systems. In male rats with free access to food, treatment with the PPARα agonist WY 14643 (3 mg·kg−1·day−1) caused a 50% reduction in hepatic AQP9 abundance with the effect being restricted to AQP9 expressed in periportal hepatocytes. The pharmacological activation of PPARα had no effect on the abundance of GlyK, whereas it caused an increased expression of hepatic GPD1, GPAT1, and L-FABP protein. In WIF-B9 and HepG2 hepatocytes, both WY 14643 and another PPARα agonist GW 7647 reduced the abundance of AQP9 protein. In conclusion, pharmacological PPARα activation results in a marked reduction in the abundance of AQP9 in periportal hepatocytes. Together with the effect on the enzymatic apparatus for glycerol metabolism, our results suggest that PPARα activation in the fed state directs glycerol into glycerolipid synthesis rather than into de novo synthesis of glucose.

Some effects of fasting on rats fed a choline-deficient diet

1960 ◽  
Vol 198 (2) ◽  
pp. 371-374 ◽  
Author(s):  
E. Douglas Rees ◽  
William W. Winternitz ◽  
William F. Lattanzi
Keyword(s):  
Blood Glucose ◽  
Ketone Bodies ◽  
Blood Glucose Concentration ◽  
Liver Glycogen ◽  
Control Group ◽  
Deficient Diet ◽  
Hepatic Fat ◽  
Blood Ketone Bodies ◽  
Deficient Group

The blood ketone body concentrations of fasted and nonfasted rats fed a diet deficient in choline were determined and found to be similar to the concentrations obtained from a control group fed the same diet supplemented with choline. However, the animals on the choline-deficient diet had an 18–20% greater mean liver mass, and this could account for the failure to demonstrate the depressed level of blood ketone bodies which was anticipated on the basis of previous in vitro studies. Other possible explanations of this discrepancy are discussed. Despite a high hepatic fat content, the choline-deficient group had a normal concentration of liver glycogen. The nonfasting blood glucose concentration of the choline-deficient group (91.5 ± 5 mg %) was lower than that of the control group (102 ± 3 mg %). After 24 hours of fasting, the values were 52 ± 3 mg % and 61 ± 5 mg % for the choline-deficient and control group, respectively. The 72-hour fasting values were 43 ± 2 mg %, and 49 ± 2 mg %, respectively. Data showing the effect of diet composition on ketonemia, liver glycogen and blood glucose are presented and are in accord with previous studies.

scholarly journals Vitamin D Deficiency Induces Elevated Oxidative and Biomechanical Damage in Coronary Arterioles in Male Rats

Antioxidants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 997
Author(s):  
Réka Eszter Sziva ◽  
Zoltán Fontányi ◽  
Éva Pál ◽  
Leila Hadjadj ◽  
Anna Monori-Kiss ◽  
...  
Keyword(s):  
Vitamin D ◽  
Wall Thickness ◽  
Smooth Muscle Actin ◽  
Male Rats ◽  
Control Group ◽  
Cross Sectional ◽  
Stress Markers ◽  
Deficient Group ◽  
Coronary Arterioles

Background: Several reports prove interconnection between vitamin D (VD) deficiency and increased cardiovascular risk. Our aim was to investigate the effects of VD status on biomechanical and oxidative–nitrative (O–N) stress parameters of coronary arterioles in rats. Methods: 4-week-old male Wistar rats were divided into a control group (11 animals) with optimal VD supply (300 IU/kgbw/day) and a VD-deficient group (11 animals, <5 IU/kg/day). After 8 weeks, coronary arteriole segments were prepared. Geometrical, elastic, and biomechanical characteristics were measured by in vitro arteriography. O–N stress markers were investigated by immunohistochemistry. Results: Inner radius decreased; wall thickness and wall-thickness/lumen diameter ratio increased; tangential wall stress and elastic modulus were reduced in VD-deficient group. No difference could be found in wall-cross-sectional area, intima-media area %. While the elastic elements of the vessel wall decreased, the α-smooth muscle actin (α-SMA) immunostaining intensity showed no changes. Significant elevation was found in the lipid peroxidation marker of 4-hidroxy-2-nonenal (HNE), while other O–N stress markers staining intensity (poly(ADP)ribose, 3-nitrotyrosine) did not change. Conclusions: Inward eutrophic remodeling has developed. The potential background of these impairments may involve the initial change in oxidative damage markers (HNE). These mechanisms can contribute to the increased incidence of the cardiovascular diseases in VD deficiency.

scholarly journals Restriction endonuclease activity induced by PBCV-1 virus infection of a Chlorella-like green alga.

1986 ◽  
Vol 6 (5) ◽  
pp. 1430-1439 ◽  
Author(s):  
Y N Xia ◽  
D E Burbank ◽  
L Uher ◽  
D Rabussay ◽  
J L Van Etten
Keyword(s):  
Enzyme Activity ◽  
Restriction Endonuclease ◽  
Green Alga ◽  
Nuclear Dna ◽  
De Novo ◽  
Dna Degradation ◽  
Endonuclease Activity ◽  
Modification System

An enzyme was isolated from a eucaryotic, Chlorella-like green alga infected with the virus PBCV-1 which exhibits type II restriction endonuclease activity. The enzyme recognized the sequence GATC and cleaved DNA 5' to the G. Methylation of deoxyadenosine in the GATC sequence inhibited enzyme activity. In vitro the enzyme cleaved host Chlorella nuclear DNA but not viral DNA because host DNA contains GATC and PBCV-1 DNA contains GmATC sequences. PBCV-1 DNA is probably methylated in vivo by the PBCV-1-induced methyltransferase described elsewhere (Y. Xia and J. L. Van Etten, Mol. Cell. Biol. 6:1440-1445). Restriction endonuclease activity was first detected 30 to 60 min after viral infection; the appearance of enzyme activity required de novo protein synthesis, and the enzyme is probably virus encoded. Appearance of enzyme activity coincided with the onset of host DNA degradation after PBCV-1 infection. We propose that the PBCV-1-induced restriction endonuclease participates in host DNA degradation and is part of a virus-induced restriction and modification system in PBCV-1-infected Chlorella cells.

scholarly journals The apparent absence of involvement of biotin in the vitamin K-dependent carboxylation of glutamic acid residues of proteins

1977 ◽  
Vol 163 (1) ◽  
pp. 39-43 ◽  
Author(s):  
P A Friedman ◽  
M A Shia
Keyword(s):  
Glutamic Acid ◽  
Vitamin K ◽  
Microsomal Fraction ◽  
Male Rats ◽  
Biotin Deficiency ◽  
Deficient Diet ◽  
Carboxylase Activity ◽  
Liver Microsomal Fraction

The mechanism of the vitamin K-dependent post-translational carboxylation of the gamma-carbon atom of glutamic acid residues in proteins remains obscure. Experiments were performed in vivo and in vitro in an attempt to establish a role for biotin in the transfer of the carboxyl group. Weanling male rats were fed on a biotin-deficient diet until severe biotin deficiency was induced. Their degree of biotin deficiency was documented by assaying for liver acetyl-CoA carboxylase activity, which was about 15% of normal. However, one-stage and two-stage prothrombin times measured on the plasmas were normal. In addition, the liver microsomal fraction did not contain any more prothrombin precursor than did that of normal rat liver. Experiments were done in vitro in which vitamin K-dependent fixing of 14CO2 was measured in the liver microsomal fraction from vitamin K-deficient male rats in the presence or absence of avidin. No evidence for an avidin-sensitive critical biotin-containing site was obtained. Thus neither series of experiments suggests a role for biotin; the data are compatible with carboxyl transfer occurring either through a carboxylated vitamin K intermediate; or via a yet to be identified intermediate, or perhaps via CO2 itself.

dSLIM Immunomodulators Induce Anti-Tumor Responses Both In Vitro and In Vivo.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 5527-5527
Author(s):  
Manuel Schmidt ◽  
Javier de Cristobal ◽  
Astrid Sander ◽  
Bernadette Brzezicha ◽  
Sven A. Koenig-Merediz ◽  
...  
Keyword(s):  
Tumor Cell ◽  
Tumor Cells ◽  
Neutralizing Antibodies ◽  
De Novo ◽  
Tumor Cell Line ◽  
Control Group ◽  
Γδt Cells ◽  
Ifn Γ

Abstract Cytosine-guanine (CpG) motifs containing oligonucleotides (ODN) are commonly used for immunomodulatory purpose in cancer therapy and for the treatment of allergic diseases since they resemble bacterial DNA and serve as “danger signals”. These CpG-ODNs promote predominately a TH1-response with secretion of IL-12 and IFN-γ, In addition their broad potential includes activation of B-cell proliferation, monocyte stimulation and secretion of IgM and IL-6, and stimulation of plasmacytoid DC to produce IFN-α/-β and thus γδT-cells and NK-cells to express CD69 and secrete IFN-γ. Usually phosphorothioate (PS) modifications are to enhance the stability, but these are leading to several side-effects, like severe organ enlargements, morphological changes and immunosuppression in mice. We designed immunomodulatory molecules based on short covalently-closed dumbbell-like structures (dSLIM) to stabilize the DNA without the otherwise necessary PS-modification. To evaluate the anti-tumor effect of the dSLIM molecules we developed an in vitro anti-tumor assay. This assay uses supernatant from dSLIM-activated human PBMCs for incubation with tumor cells in vitro. We observed increased apoptosis and necrosis by the HT-29 tumor cell line after incubation with supernatant from dSLIM-treated PBMC which was significantly higher than the effect of supernatant from non-treated PBMC. In addition, supernatant from dSLIM-treated PBMC increased the expression of HLA-ABC on the tumor cells, a pre-requisite for tumor cell recognition by the immune system. These effects were confirmed with human HEK293 and murine Renca cell lines. Analyzing the effect with neutralizing antibodies to various apoptosis-related cytokines, we observed a crucial role of IFN-γ but not IFN-α or TNFα. To investigate the anti-tumor effects of dSLIM in vivo, we employed a SKH1 murine model which is prone to spontaneous development of papillomas. Using chemicals for initiation and weekly promotion of de novo papilloma development we compared groups of weekly s.c. or i.p. dSLIM injections, respectively, with the PBS control group. The number of papilloma developing mice was significantly lower in the dSLIM groups and the total number of papillomas on all mice was reduced by approximately 50%. In conclusion, we showed that dSLIM immunomodulators exhibit potent anti-tumor effects in vitro and in vivo.

scholarly journals Red kidney bean lectin is a potent cholecystokinin releasing stimulus in the rat inducing pancreatic growth

Gut ◽  
1997 ◽  
Vol 41 (3) ◽  
pp. 333-338 ◽  
Author(s):  
K-H Herzig ◽  
S Bardocz ◽  
G Grant ◽  
R Nustede ◽  
U R Fölsch ◽  
...  
Keyword(s):  
Small Intestine ◽  
Specific Binding ◽  
Male Rats ◽  
Growth Effect ◽  
Control Group ◽  
Maximal Effect ◽  
Pancreatic Growth ◽  
Cck Release

Background—Lectins are proteins capable of specific binding to carbohydrates without altering their covalent structure. As an essential part of plants they are ingested in our daily diet. By binding to glycosyl side chains of receptors lectins can mimic or inhibit the action of the ligand. Oral administration of phytohaemagglutinin (PHA) in rats dose dependently induces growth of the small intestine and the pancreas by an unknown mechanism.Aims—To investigate the mechanism of PHA induced intestinal and pancreatic growth.Methods—Thirty day old male rats were pairfed for 10 days with lactalbumin as a control diet or lactalbumin plus PHA or purified soybean trypsin inhibitor (STI) as a positive control (42 mg/rat/day) with or without 20 μg of the cholecystokinin A (CCK-A) antagonist MK 329. To investigate further the effect of PHA on CCK release intestinal mucosal cells were isolated from rats which were continuously perfused in a perfusion apparatus. CCK release into the medium was assayed.Results—PHA and STI significantly stimulated growth of the pancreas and the small intestine. MK 329 blocked this growth effect in the pancreas but not in the small intestine. In vivo, PHA significantly increased CCK plasma levels from 0.75 to 6.67 (SEM 2.23) compared with 2.3 (0.35) pM in the control group. In addition, in vitro PHA dose dependently stimulated CCK release with a maximal effect at 100 ng/ml.Conclusion—In vivo and in vitro PHA is a potent stimulus for CCK release in the rat, thereby inducing pancreatic growth, whereas intestinal growth is stimulated by a CCK independent mechanism.

LH induces de novo cholesterol biosynthesis via SREBP activation in granulosa cells during ovulation in female mice

Endocrinology ◽  
2021 ◽  
Author(s):  
Tomoya Nakanishi ◽  
Risa Tanaka ◽  
Shingo Tonai ◽  
Joo Yeon Lee ◽  
Manami Yamaoka ◽  
...  
Keyword(s):  
Corpus Luteum ◽  
Granulosa Cells ◽  
De Novo ◽  
Cholesterol Biosynthesis ◽  
Active Form ◽  
Control Group ◽  
Element Binding Protein ◽  
Matured Oocyte

Abstract In the liver, the sterol response element binding protein (SREBP) and the SREBP cleavage-activated protein (SCAP) complex upregulates cholesterol biosynthesis by gene induction of de novo cholesterol synthetic enzymes (Hmgcr, Cyp51, and Dhcr7). Insulin induced gene 1 (INSIG1) negatively regulates cholesterol biosynthesis by the inhibition of de novo cholesterol biosynthetic gene expression. In the ovary, cholesterol is de novo synthesized; however, the roles of SREBP and its regulators (SCAP and INSIG1) are not well understood. In this study, when immature mice were treated with gonadotropins (eCG followed by hCG), eCG induced and hCG maintained the expression of SREBP-1a, -2, and SCAP granulosa cells, whereas INSIG1 expression was dramatically downregulated after hCG injection. Downregulation of INSIG1 led to generate the SREBPs active form and translocate the SREBPs active form to nuclei. Inhibition of generation of the SREBPs active form by fatostatin or Scap siRNA in both in vivo and in vitro significantly decreased the expressions of de novo cholesterol biosynthetic enzymes, cholesterol accumulation, and progesterone (P4) production compared to control group. Fatostatin treatment inhibited the ovulation and increased the formation of abnormal corpus luteum which trapped the matured oocyte in the corpus luteum, however, the phenomenon was abolished by P4 administration. The results showed that decreasing INSIG1 level after hCG stimulation activated SREBP-induced de novo cholesterol biosynthesis in granulosa cells of preovulatory follicles, which is essential for P4 production and the rupture of matured oocyte during ovulation process.

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