http://en.wikipedia.org/wiki/Messenger_RNA#Eukaryotic_mRNA_turnoverMicroRNA (miRNA) Main article: microRNA MicroRNAs (miRNA s) are small RNAs that typically are partially complementary to sequences in metazoan messenger RNAs. [16] Binding of a miRNA to a message can repress translation of that message and accelerate poly(A) tail removal, thereby hastening mRNA degradation. The mechanism of action of miRNAs is the subject of active research. [17] Hastening - Be quick to do something. GI MICROFLORA http://www.textbookofbacteriology.net/normalflora.html GASTRIC BYPASS http://www.post-gazette.com/pg/10062/1039722-114.stm Biosci Biotechnol Biochem.2001 Nov;65(11):2565-8. Changes of pyridine nucleotide levels during adipocyte differentiation ofmouse 3T3-L1 cells. Fukuwatari T, Doi M,Sugimoto E , Kawada T, Shibata K. Source Department of Life Style Studies, School of Human Cultures, The University of Shiga Prefecture, Hikone, Japan. [email protected]Abstract The levels of NAD and NADP were measured in 3T3-L1 cells during a differentiation from preadipocytes to adipocytes. The cells were grown in the ordinary medium and differentiated in the medium by adding dexamethasone, 1-methyl-3-isobutylxanthine, and insulin for 2 days, and then they were grown in the medium by adding only insulin for another 8 days to accumulate fat. The levels of cellular NAD and NADP increased abruptly with days after differentiation, and the levels of NAD and NADP reached maximum at day 7, and at day 10 the values were decreased compared with the maximum values. These results suggest that expression of the pyridine nucleotide biosynthesis genes is induced in the differentiation process. PMID:11791736 http://en.wikipedia.org/wiki/Selfish_Brain_Theory
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AbstractThe levels of NAD and NADP were measured in 3T3-L1 cells during a differentiation from preadipocytes
to adipocytes. The cells were grown in the ordinary medium and differentiated in the medium by adding
dexamethasone, 1-methyl-3-isobutylxanthine, and insulin for 2 days, and then they were grown in the
medium by adding only insulin for another 8 days to accumulate fat. The levels of cellular NAD and NADP
increased abruptly with days after differentiation, and the levels of NAD and NADP reached maximum at day
7, and at day 10 the values were decreased compared with the maximum values. These results suggest thatexpression of the pyridine nucleotide biosynthesis genes is induced in the differentiation process.
The “Selfish Brain” theory describes the characteristic of the human brain to cover its own,
comparably high energy requirements with the utmost of priorities when regulating energy fluxes
in the organism. The brain behaves selfishly in this respect. The "Selfish brain" theory amongst
other things provides a possible explanation for the origin of obesity, the severe and pathological
form of overweight.
Investigative approach of the Selfish Brain theory
The brain performs many functions for the human organism. Most are of a cognitive nature or
concern the regulation of the motor system. A previously lesser investigated aspect of brain
activity was the regulation of energy metabolism. The "Selfish Brain" theory shed new light on this
function. This theory states that the brain behaves selfishly by controlling energy fluxes in such a
way that it allocates energy to itself before the needs of the other organs are satisfied. The
internal energy consumption of the brain is very high. Although its mass constitutes only 2% of
the entire body weight, it consumes 50% of the carbohydrates ingested over a 24 hour period.
This corresponds to 100 g of glucose per day, or half the daily requirement for a human being. A
30 year-old office worker with a body weight of 75 kg and a height of 1.85 m consumes approx.
200 g glucose per day.
Before now the scientific community assumed that the energy needs of the brain, the muscles
and the organs were all met in parallel. The hypothalamus, an area of the upper brainstem, was
thought to play a central role in regulating two feedback loops within narrow limits.
The "lipostatic theory" established by Gordon C Kennedy in 1953 describes the fat
deposition feedback system.[1][ page needed ] The hypothalamus receives signals from circulating
metabolic products or hormones about how much adipose tissue there is in the body as well
as its prevailing metabolic status. Using these signals the hypothalamus can adapt the
absorption of nutrients so that the body’s fat depots remain constant, i.e. a "lipostasis" is
achieved.
The "glucostatic theory" developed in the same year by Jean Mayer describes the blood
glucose feedback system.[2][ page needed ]According to this theory the hypothalamus controls the
absorption of nutrients via receptors that measure the glucose level in the blood. In this way acertain glucose concentration is set by adjusting the intake of nutrients. Interestingly enough,
Mayer also included the brain in his calculations. Although he considered that food intake
served to safeguard the energy homoeostasis of the central nervous system, he did imply
that the energy flux from the body to the brain was a passive process.
On the basis of these theories a number of international research groups still position the origin of
obesity in a disorder in one of the two above described feedback systems.
http://www.jlr.org/content/48/4/826.full.pdf
Together, our results suggest that the reduction in intracellular lipid by constitutive
expression of UCP1 reflects a downregulation of fat synthesis rather than an upregulation
of fatty acid oxidation.—Si, Y., S. Palani, A. Jayaraman, and K. Lee. Effects of forced
uncoupling protein 1 expression in 3T3-L1 cells on mitochondrial function and lipid
metabolism. J. Lipid Res. 2007. 48: 826–836
http://en.wikipedia.org/wiki/Lactic_acidosis
When excess intracellular lactate is released into the blood, maintenance of electroneutrality
requires a cation (e.g. a proton) to be released as well. This can reduce blood pH. Glycolysis
coupled with lactate production is neutral in the sense that it does not produce excess protons.
However, pyruvate production does produce protons. Lactate production is buffered
intracellularly, e.g. the lactate-producing enzyme lactate dehydrogenase binds one proton per
pyruvate molecule converted. When such buffer systems become saturated, cells will transport
lactate into the blood stream. Hypoxia certainly causes both buildup of lactate and acidification,
and lactate is therefore a good "marker" of hypoxia, but lactate itself is not the cause of low pH.[4]
Lactic acidosis sometimes occurs without hypoxia, for example in rare congenital disorders where
mitochondria do not function at full capacity. In such cases, when the body needs more energythan usual, for example during exercise or disease, mitochondria cannot match the cells' demand
The name "glucocorticoid" derives from early observations that these hormones were involved
in glucose metabolism. In the fasted state, cortisol stimulates several processes that collectively
serve to increase and maintain normal concentrations of glucose in blood.
Metabolic effects:
Stimulation of gluconeogenesis, in particular, in the liver : This pathway results in the
synthesis of glucose from non-hexose substrates such as amino acids and glycerol from
triglyceride breakdown, and is particularly important in carnivores and certain herbivores.
Enhancing the expression of enzymes involved in gluconeogenesis is probably the best-
known metabolic function of glucocorticoids.
Mobilization of amino acids from extrahepatic tissues: These serve as substrates
for gluconeogenesis.
Inhibition of glucose uptake in muscle and adipose tissue: A mechanism to conserve
glucose.
Stimulation of fat breakdown in adipose tissue: The fatty acids released by lipolysis are
used for production of energy in tissues like muscle, and the released glycerol provide
another substrate for gluconeogenesis.
Glucocorticoids have been shown to exert a number of rapid actions that are independent of the
regulations of gene transcription. Binding of corticosteroids to the glucocorticoid receptor (GR)
stimulates phosphatidylinositol 3-kinase and protein kinase AKT, leading to endothelial nitric
oxide synthase (eNOS) activation and nitric oxide-dependent vasorelaxation
http://www.medscape.com/viewarticle/500858_2
Glucocorticoids and Ceramide Synthesis
The discovery that glucocorticoids have a large and specific effect on sphingolipids derived from
studies addressing the theory that the broad scope of corticosteroid action was due to the ability
of different hormones to directly modify membrane lipids.[39] Specifically, the well-recognizedimportance of corticosteroids in protection against stress was considered to possibly relate to
membrane fluidity, which is involved in the adaptation of bacteria, fish, and hibernating animals to
extremes of heat and cold.[40] To investigate this possibility, investigators quantified the fatty acid,
phospholipid, and sphingolipid composition of membranes in various cell types incubated with
dexamethasone. Notably, the glucocorticoid increased membrane sphingomyelin in rat
epididymal fat cells.[41] Dexamethasone was subsequently shown to increase sphingomyelin levels
in HeLa cells[42] and human polymorphonuclear leukocytes,[17] ceramide levels in a murine B
Plasma Ceramides Are Elevated in ObeseSubjects With Type 2 Diabetes andCorrelate With the Severity of InsulinResistance
Plasma ceramide levels are elevated in type 2 diabetic subjects and may contributeto insulin resistance through activation of inflammatory mediators, such as TNF-α.
http://www.ncbi.nlm.nih.gov/pubmed/21437908
J Cell Physiol. 2011 Mar 24. doi: 10.1002/jcp.22745. [Epub ahead of print]
Ceramide metabolism is affected by obesity and diabetes in humanadipose tissue.
ceramide (Cer), dihydroceramide (dhCer), sphingosine, sphinganine (SPA), sphingosine-1-phosphate(pmol/mg of protein), the expression (mRNA) and activity of key enzymes responsible for Cer metabolism:serine palmitoyltransferase (SPT), neutral and acidic sphingomyelinase (n-, aSMase) and neutral and acidicceramidase (n -, aCDase) were examined in human adipose tissue.
The expression of examined enzymes was elevated in both obese groups. The SPT and CDases activityincreased whereas aSMase activity deceased in both obese groups.
We have found correlation between adipose tissue ceramide content and plasma adiponectin concentration(r=0.69, p< 0.001) and negative correlation between total ceramide content and HOMA-IR index(homeostasis model of insulin resistance) (r = -0.67, p< 0.001).
The contents of SPA and Cer were significantly lower whereas the content of dhCer was higher in bothobese groups than the respective values in the lean subjects.
The Ceramide-centric Universe of Lipid-mediated Cell Regulation: StressEncounters of the Lipid Kind
The Journal of Biological Chemistry, 277,25847-25850
The Mitochondrion: a Novel Compartment for CeramideMetabolism and ActionA novel CDase has been localized to mitochondria, demonstrating unequivocally theexistence of a mitochondrial pathway of ceramide metabolism (22). Ceramide levelshave been detected in mitochondria (23), and TNF was shown to induce
accumulation of ceramide in the heavy membrane compartment (10,000 × gpellet)(24). The addition of exogenous ceramide to purified mitochondria results ininhibition of the respiratory chain, the generation of reactive oxygen species, and therelease of cytochrome c(24-27). The expression of bacterial SMase in mitochondria,but not other subcellular compartments, resulted in induction of apoptosis (28),suggesting a role for endogenous mitochondrial ceramide in regulating apoptosis.
Key Enzymes of Ceramide Metabolism as Switches in CellRegulationBecause of the intimate interconnections of lipid metabolism, many of the enzymes that regulate bioactive lipids also function as switches byregulating the levels of bioactive substrates and products. For
example, ceramidases can regulate the levels of ceramide (substrate)and/or sphingosine and S1P (products), with S1P often exerting anti-apoptotic effects that antagonize ceramide-mediated responses (seeminireview by Spiegel and Milstien (58)). TNF has been shown toactivate CDases, and this was correlated with lack of accumulation of ceramide and absence of an apoptotic response. Also, the action of IL-1 was shown to induce activation of CDase especially at lowconcentrations of the cytokine, thus leading to sphingosine-mediatedresponses. At higher concentrations of IL-1, ceramide accumulates andmediates effects of IL-1 on expression of α1-acid glycoprotein (2). SMsynthase (or inositol phosphoceramide synthase in yeast) regulates the
levels of ceramide and DAG in a reciprocal manner. Indeed, evidencehas been provided that active SM synthase can switch a signalingresponse from one mediated by ceramide (inhibition of NF-κB) to onemediated by DAG (activation of NF-κB) (49). Thus, many of theenzymes of sphingolipid metabolism are emerging as regulatedswitches controlling the relative levels of more than one bioactive lipid.
Figure 1Basic pathways of ceramide metabolism and interrelationship of regulatorypathways mediated by bioactive lipids. Ceramide can be formed de novo orfrom hydrolysis of SM or complex glycolipids (horizontal plane in diagram). In turn,ceramide may be converted to sphingosine (Sph) or serve as a substrate for SM
synthesis (generating DAG) or glycolipids. Each of the major bioactive lipids is thencapable of interacting with specific targets leading to specific responses (verticalplane). PalCoA, palmitoyl-CoA;DHS, dihydrosphingosine; DHCer , dihydroceramide;SK ,sphingosine kinase; PC, phosphatidylcholine;PA, phosphatidic acid; SMS, SMsynthase;DGK , DAG kinase; SL, sphingolipid.
Figure 2Compartmentalization of ceramide metabolism and function. Shown areseveral distinct compartments of ceramide metabolism and function (refer to text fordiscussion). Cer , ceramide; DHS, dihydrosphingosine; Cath D, cathepsin D; Sph,sphingosine; Sph-K , sphingosine kinase; Alk , alkaline;PalCoA, palmitoyl-CoA;SR,sarcoplasmic reticulum; dhCer , dihydroceramide;CerS, ceramide synthase; deSat ,desaturase; PC, phosphatidylcholine; SMS, SM synthase.
Similarly, little is known concerning SM synthase, one of the most recalcitrantenzymes that has resisted efforts at purification and cloning.
http://www.ncbi.nlm.nih.gov/pubmed/21669879
J Biol Chem. 2011 Jun 13. [Epub ahead of print]
Dynamic modification of sphingomyelin in lipid microdomains controlsdevelopment of obesity, fatty liver, and type 2 diabetes.
Lipid microdomains or caveolae, small invaginations of plasma membrane, have emerged as importantelement for lipid uptake and glucose homeostasis. Sphingomyelin (SM) is one of the major phospholipids of the lipid microdomains. In this study, we investigated the physiological function of sphingomyelinsynthase 2 (SMS2) using SMS2-knockout mice, and found that SMS2 deficiency prevents high fat diet-induced obesity and insulin resistance. Interestingly, in the liver of SMS2-knockout mice, large and maturedlipid droplets were scarcely observed. Treatment with siRNA for SMS2 also decreased the large lipiddroplets in HepG2 cells. Additionally, the siRNA of SMS2 decreased the accumulation of triglyceride in liver of leptin-deficient (ob/ob) mice, strongly suggesting that SMS2 is involved in lipid droplets formation.Furthermore, we found that SMS2 exists in lipid microdomains and partially associates with the fatty acidtransporter CD36/FAT and with caveolin 1, a scaffolding protein of caveolae. Since CD36/FAT and caveolin1 exist in lipid microdomains and are coordinately involved in lipid droplets formation, SMS2 is implicated inmodulation of the SM in lipid microdomains, resulting in the regulation of CD36/FAT and caveolae. Here, weestablished new cell lines, in which we can completely distinguish SMS2 activity from SMS1 activity, and wedemonstrated that SMS2 could convert ceramide produced in the outer leaflet of the plasma membrane intoSM. Our findings demonstrate the novel and dynamic regulation of lipid microdomains via conformationalchanges in lipids on the plasma membrane by SMS2, which is responsible for obesity and type 2 diabetes.
http://www.nutridesk.com.au/chili.phtml
http://www.jbc.org/content/283/31/21418.full.pdf
Capsaicin Stimulates Uncoupled ATP Hydrolysis by the
Sarcoplasmic Reticulum Calcium Pump
In muscle cells the sarcoplasmic reticulum (SR) Ca 2+-ATPase (SERCA) couples thefree energy of ATP hydrolysis to pump Ca 2+ ions from the cytoplasm to the SR lumen.
In addition, SERCA plays a key role in non-shivering thermogenesis through uncoupled
reactions, where ATP hydrolysis takes place without active Ca 2+ translocation.
Capsaicin (CPS) is a naturally occurring vanilloid, the consumption of which is linked
with increased metabolic rate and core body temperature.
To the best of our knowledge CPS is the first natural drug that augments uncoupled
SERCA, presumably resulting in thermogenesis. The role of CPS as a SERCA modulator
is discussed.
Phytother Res. 2011 Jun;25(6):935-9. doi: 10.1002/ptr.3339. Epub 2010 Nov 17.
CAPSICUM FRUITS, red peppers, are used throughout the world as spices that stimulate
gustation and make insipid foods more appetizing. The major pungent principle of red pepper is capsaicin (36), which has been reported to elevate body temperature
(11), stimulate the secretion of catecholamines (52), promote energy expenditure
(24), and suppress body-fat accumulation (23) in experimental animals.
Consequently, capsaicin is thought to constitute a potential dietetic therapy for
obesity and diabetes. However, capsaicin is strongly pungent and neurotoxic (22),
which largely prohibits its administration to humans.
http://en.wikipedia.org/wiki/Oleic_acid
Triglyceride esters of oleic acid compose the majority of olive oil, although there may be less than
2.0% as free acid in the virgin olive oil, with higher concentrations making the olive oil inedible. It
also makes up 59-75% of pecan oil,[3] 36-67% of peanut oil,[4] 15-20% of grape seed oil, sea
buckthorn oil, and sesame oil,[2] and 14% of poppyseed oil.[5] It is abundantly present in many
animal fats, constituting 37 to 56% of chicken and turkey fat,[6] and 44 to 47% of lard, etc.
Oleic acid is the most abundant fatty acid in human adipose tissue.
Fatty acids as natural uncouplers preventing generationof and H2O2 by mitochondria in the resting state
Both natural (laurate) and artificial (m-chlorocarbonylcyanide phenylhydrazone; CCCP) uncouplers strongly
inhibit and H2O2 formation by rat heart mitochondria oxidizing succinate. Carboxyatractylate, an
ATP/ADP antiporter inhibitor, abolishes the laurate inhibition, the CCCP inhibition being unaffected.Atractylate partially releases the inhibition by laurate and decelerates the releasing effect of carboxyatractylate. GDP is much less effective than carboxyatractylate in releasing the laurate inhibition of reactive oxygen species (ROS) formation. Micromolar laurate concentrations arresting the ROS formationcause strong inhibition of reverse electron transfer from succinate to NAD+, whereas State 4 respiration andthe transmembrane electric potential difference (ΔΨ) level are affected only slightly. It is suggested that (i)free fatty acids operate as natural ‘mild uncouplers' preventing the transmembrane electrochemical
H+potential difference ( ) from being above a threshold critical for ROS formation by complex I and,to a lesser degree, by complex III of the respiratory chain, and (ii) it is the ATP/ADP-antiporter, rather thanuncoupling protein 2, that is mainly involved in this antioxidant mechanism of heart muscle mitochondria.