Gestational Protein Restriction in Wistar Rats; Effect of Taurine Supplementation on Properties of Newborn Skeletal Muscle.

Taurine ameliorates changes occurring in newborn skeletal muscle as a result of gestational protein restriction in C57BL/6 mice, but taurine supplementation effects may be exaggerated in C57BL/6 mice due to their inherent excessive taurinuria.We examined if maternal taurine supplementation could ameliorate changes in gene expression levels, properties of mitochondria, myogenesis, and nutrient transport and sensing, in male newborn skeletal muscle caused by a maternal low protein (LP) diet in Wistar rats.LP diet resulted in an 11% non-significant decrease in birth weight, which was not rescued by taurine supplementation (LP-Tau). LP-Tau offspring had significantly lower birth weight compared to controls. Gene expression profiling revealed 895 significantly changed genes, mainly an LP-induced down-regulation of genes involved in protein translation. Taurine fully or partially rescued 32% of these changes, but with no distinct pattern as to which genes were rescued.Skeletal muscle taurine content in LP-Tau offspring was increased, but no changes in mRNA levels of the taurine synthesis pathway were observed. Taurine transporter mRNA levels, but not protein levels, were increased by LP diet.Nutrient sensing signaling pathways were largely unaffected in LP or LP-Tau groups, although taurine supplementation caused a decrease in total Akt and AMPK protein levels. PAT4 amino acid transporter mRNA was increased by LP, and normalized by taurine supplementation.In conclusion, gestational protein restriction in rats decreased genes involved in protein translation in newborn skeletal muscle and led to changes in nutrient transporters. Taurine partly rescued these changes, hence underscoring the importance of taurine in development.

Taurine, glutathione and bioenergetics.

Biochemistry textbook presentations of bioenergetics and mitochondrial function normally focus on the chemiosmotic theory with introduction of the tricarboxylic acid cycle and the electron transport chain, the proton and electrical gradients and subsequent oxidative phosphorylation and ATP-production by ATP synthase. The compound glutathione (GSH) is often mentioned in relation to mitochondrial function, primarily for a role as redox scavenger. Here we argue that its role as redox pair with oxidised glutathione (GSSG) is pivotal with regard to controlling the electrical or redox gradient across the mitochondrial inner-membrane. The very high concentration of taurine in oxidative tissue has recently led to discussions on the role of taurine in the mitochondria, e.g. with taurine acting as a pH buffer in the mitochondrial matrix. A very important consequence of the slightly alkaline pH is the fact that the NADH/NAD(+) redox pair can be brought in redox equilibrium with the GSH redox pair GSH/GSSG.An additional consequence of having GSH as redox buffer is the fact that from the pH dependence of its redox potential, it becomes possible to explain that the mitochondrial membrane potential has been observed to be independent of the matrix pH. Finally a simplified model for mitochondrial oxidation is presented with introduction of GSH as redox buffer to stabilise the electrical gradient, and taurine as pH buffer stabilising the pH gradient, but simultaneously establishing the equilibrium between the NADH/NAD(+) redox pair and the redox buffer pair GSH/GSSG.

The effect of long-term taurine supplementation and fructose feeding on glucose and lipid homeostasis in Wistar rats.

The nonprotein amino acid taurine has been shown to counteract the negative effects of a high-fructose diet in rats with regard to insulin resistance and dyslipidemia. Here we examined the long-term (26 weeks) effects of oral taurine supplementation (2% in the drinking water) in fructose-fed Wistar rats.The combination of fructose and taurine caused a significant increase in fasting glucose compared to the control diet without changing hepatic phosphoenol pyruvate carboxykinase mRNA levels. The combination of fructose and taurine also improved glucose tolerance compared to control. Neither a high-fructose diet nor taurine supplementation induced significant changes in body weight, body fat or total calorie intake, fasting insulin levels, HOMA-IR, or insulin-induced Akt phosphorylation in skeletal muscle.Fructose alone caused a decrease in liver triglyceride content, with taurine supplementation preventing this. There was no effect of long-term fructose diet and/or taurine supplementation on plasma triglycerides, plasma nonesterified fatty acids, as well as plasma HDL, LDL, and total cholesterol.In conclusion, the study suggests that long-term taurine supplementation improves glucose tolerance and normalize hepatic triglyceride content following long-term fructose feeding. However, as the combination of taurine and fructose also increased fasting glucose levels, the beneficial effect of taurine supplementation towards amelioration of glucose intolerance and insulin resistance may be questionable.

Progression of type 2 diabetes in GK rats affects muscle and liver mitochondria differently: pronounced reduction of complex II flux is observed in liver only.

Impaired mitochondrial function is implicated in the development of type 2 diabetes mellitus (T2DM). This was investigated in mitochondria from skeletal muscle and liver of the Goto-Kakizaki (GK) rat, which spontaneously develops T2DM with age. The early and the manifest stage of T2DM was studied in 6- and 16-wk-old GK rats, respectively. In GK16 compared with GK6 animals, a decrease in state 3 respiration with palmitoyl carnitine (PC) as substrate was observed in muscle. Yet an increase was seen in liver. To test the complex II contribution to the state 3 respiration, succinate was added together with PC. In liver mitochondria, this resulted in an ∼50% smaller respiratory increase in the GK6 group compared with control and no respiratory increase at all in the GK16 animals. Yet no difference between groups was seen in muscle mitochondria. RCR and P/O ratio was increased (P < 0.05) in liver but unchanged in muscle in both GK groups. We observed increased lipid peroxidation and decreased Akt phosphorylation in liver with the progression of T2DM but no change in muscle. We conclude that, during the progression of T2DM in GK rats, liver mitochondria are affected earlier and/or more severely than muscle mitochondria. Succinate dehydrogenase flux in the presence of fatty acids was reduced severely in liver but not in muscle mitochondria during manifest T2DM. The observations support the notion that T2DM pathogenesis is initiated in the liver and that only later are muscle mitochondria affected.

Report of the first nationally implemented clinical routine screening for fetal RHD in D- pregnant women to ascertain the requirement for antenatal RhD prophylaxis.

BACKGROUND: A combination of antenatal and postnatal RhD prophylaxis is more effective in reducing D immunization in pregnancy than postnatal RhD prophylaxis alone. Based on the result from antenatal screening for the fetal RHD gene, antenatal RhD prophylaxis in Denmark is given only to those D- women who carry a D+ fetus. We present an evaluation of the first national clinical application of antenatal RHD screening. STUDY DESIGN AND METHODS: In each of the five Danish health care regions, blood samples were drawn from D- women in Gestational Week 25. DNA was extracted from the maternal plasma and analyzed for the presence of the RHD gene by real-time polymerase chain reaction targeting two RHD exons. Prediction of the fetal RhD type was compared with serologic typing of the newborn in 2312 pregnancies, which represented the first 6 months of routine analysis. RESULTS: For the detection of fetal RHD, the sensitivity was 99.9%. The accuracy was 96.5%. The recommendation for unnecessary antenatal RhD prophylaxis for women carrying a D- fetus was correctly avoided in 862 cases (37.3%), while 39 women (1.7%) were recommended for antenatal RhD prophylaxis unnecessarily. Two RHD+ fetuses (0.087%) were not detected, and antenatal RhIG was not given. CONCLUSION: These data represent the first demonstration of the reliability of routine antenatal fetal RHD screening in D-, pregnant women to ascertain the requirement for antenatal RhD prophylaxis. Our findings should encourage the implementation of such screening programs worldwide, to reduce the unnecessary use of RhIG.

Transfusion of shed mediastinal blood reduces the use of allogenic blood transfusion without increasing complications.

BACKGROUND: Reduced use of allogenic blood components is a key issue in cardiac surgery. Several methods to conserve blood have been used; reinfusion of shed mediastinal blood (RSMB) has found widespread acceptance, but the efficacy and safety are still debated. The purpose of this study was to evaluate the effects of RSMB on the use of allogenic blood components and selected complications. MATERIAL AND METHODS: Six hundred and twenty-three consecutive cardiac surgery patients in three successive periods, of whom patients in the middle period did not receive RSMB due to manufacturer delivery problems, were evaluated. Patients and procedures were characterized by EuroSCORE. Prospective collected data were: units of transfused allogenic blood, fresh frozen plasma (FFP) and platelets, postoperative blood loss and postoperative complications such as dialysis, re-operation due to bleeding, sternal infection and stroke. Length of stay in ICU was used as a general indicator of perioperative complications. RESULTS: The number of patients receiving allogenic blood in periods with RSMB was significantly lower (36.5% versus 54.9%, p<0.005), while no difference was seen in FFP and platelets. The average number of transfused blood units was lower in patients receiving RSMB (2.07 versus 3.41, p=0.029), while FFP (1.34 versus 2.01, p=0.11) and platelets (0.58 versus 0.95, p=0.05) were not statistically significantly different. Postoperative bleeding was lower (759 versus 967 ml, p=0.032) in the periods with RSMB. CONCLUSION: Patients receiving RSMB were less transfused with allogenic blood and had less postoperative drainage, while the frequency of observed postoperative complications was not different from patients who did not receive RSMB.

A role for taurine in mitochondrial function.

The mitochondrial pH gradient across the inner-membrane is stabilised by buffering of the matrix. A low-molecular mass buffer compound has to be localised in the matrix to maintain its alkaline pH value. Taurine is found ubiquitously in animal cells with concentrations in the millimolar range and its pKa value is determined to 9.0 (25 degrees C) and 8.6 (37 degrees C), respectively. Localisation of such a low-molecular buffer in the mitochondrial matrix, transforms the matrix into a biochemical reaction chamber for the important matrix-localised enzyme systems. Three acyl-CoA dehydrogenase enzymes, which are pivotal for beta-oxidation of fatty acids, are demonstrated to have optimal activity in a taurine buffer. By application of the model presented, taurine depletion caused by hyperglycemia could provide a link between mitochondrial dysfunction and diabetes.

A maternal low protein diet has pronounced effects on mitochondrial gene expression in offspring liver and skeletal muscle; protective effect of taurine.

BACKGROUND: Low birth weight is associated with an increased risk of developing impaired glucose tolerance, and eventually type 2 diabetes in adult life. Gestational protein restriction in rodents gives rise to a low birth weight phenotype in the offspring. RESULTS: We examined gene expression changes in liver and skeletal muscle of mice subjected to gestational protein restriction (LP) or not (NP), with or without taurine supplementation in the drinking water. LP offspring had a 40% lower birth weight than NP offspring, with taurine preventing half the decrease. Microarray gene expression analysis of newborn mice revealed significant changes in 2012 genes in liver and 967 genes in skeletal muscle of LP offspring. Taurine prevented 30% and 46% of these expression changes, respectively. Mitochondrial genes, especially those involved with oxidative phosphorylation, were more abundantly changed than other genes. The mitochondrial genes were mainly upregulated in liver, but downregulated in skeletal muscle, despite no change in citrate synthase activity in either tissue. Taurine preferentially rescued genes concerned with fatty acid metabolism in liver and with oxidative phosphorylation and TCA cycle in skeletal muscle. A mitochondrial signature was seen in the liver of NP offspring with taurine supplementation, as gene sets for mitochondrial ribosome as well as lipid metabolism were over represented in 4-week-old offspring subjected to gestational taurine supplementation. Likewise, 11 mitochondrial genes were significantly upregulated by gestational taurine supplementation in 4-week-old NP offspring. CONCLUSIONS: Gestational protein restriction resulted in lower birth weight associated with significant gene expression changes, which was different in liver and muscle of offspring. However, a major part of the birth weight decrease and the expression changes were prevented by maternal taurine supplementation, implying taurine is a key factor in determining expression patterns during development and in that respect also an important component in metabolic fetal programming.

RHD positive among C/E+ and D- blood donors in Denmark.

BACKGROUND: Many different partial and weak D types have been reported, and most of these are easily detected by serology. However, 17 Del types have also been described, with a very low expression of the D antigen, only detectable by absorption-elution techniques, and these may elicit the development of an anti-D. A genomic test of C/E+ and D- blood donors was initiated, to be able to categorize them correctly as D+ or -. STUDY DESIGN AND METHODS: We analyzed all C/E+ and D- donors within our donor population of 22,000 donors with an initial test for RHD Exon 10. In case of a positive reaction, the genotype was further analyzed by sequence-specific polymerase chain reaction or nucleotide sequencing of the RHD gene. CONCLUSIONS: Of 233 donors analyzed, seven were found positive for RHD Exon 10, and four of these were Del, corresponding to 1.7%. We report here a new mutation in the RHD gene. A correct assignment of all blood donors as D+ or D- is not possible using serotyping alone; genotyping offers the only exact categorization of all cases.

Gestational protein restriction in mice has pronounced effects on gene expression in newborn offspring's liver and skeletal muscle; protective effect of taurine.

UNLABELLED: We examined gene expression changes in liver and skeletal muscle of newborn mice subjected to a maternal low protein (LP) or normal protein (NP) diet during pregnancy, with or without taurine supplementation in the drinking water. LP offspring had a 40% lower birthweight than NP offspring, whereas it was reduced by only 20% with taurine supplementation. Microarray gene expression analysis revealed significant changes in 2012 genes in liver and 967 genes in skeletal muscle of LP offspring. By unknown mechanisms, taurine partially or fully prevented 30 and 46% of these expression changes, respectively. Mitochondrial genes, in particular genes associated with oxidative phosphorylation, were more abundantly changed in LP offspring, with primarily up-regulation in liver but down-regulation in skeletal muscle. In both tissues, citrate synthase activity remained unchanged. Taurine preferentially rescued changes in genes concerned with fatty acid metabolism in liver and with oxidative phoshorylation and tri carboxylic acid (TCA) cycle in skeletal muscle. ABBREVIATIONS: Gestational protein restriction resulted in lower birthweight associated with significant gene expression changes, which was different in liver and muscle of offspring. However, a major part of the birthweight decrease and the expression changes were prevented by maternal taurine supplementation, implying taurine is a key component in metabolic fetal programming.

Changed mitochondrial function by pre- and/or postpartum diet alterations in sheep.

In a sheep model, we investigated diet effects on skeletal muscle mitochondria to look for fetal programming. During pregnancy, ewes were fed normally (N) or were 50% food restricted (L) during the last trimester, and lambs born to these ewes received a normal (N) or a high-fat diet (H) for the first 6 mo of life. We examined mitochondrial function in permeabilized muscle fibers from the lambs at 6 mo of age (adolescence) and after 24 mo of age (adulthood). The postpartum H diet for the lambs induced an approximately 30% increase (P < 0.05) of mitochondrial VO(2max) and an approximately 50% increase (P < 0.05) of the respiratory coupling ratio (RCR) combined with lower levels of UCP3 and PGC-1alpha mRNA levels (P < 0.05). These effects proved to be reversible by a normal diet from 6 to 24 mo of age. However, at 24 mo, a long-term effect of the maternal gestational diet restriction (fetal programming) became evident as a lower VO(2max) (approximately 40%, P < 0.05), a lower state 4 respiration (approximately 40%, P < 0.05), and lower RCR ( approximately 15%, P < 0.05). Both PGC-1alpha and UCP3 mRNA levels were increased (P < 0.05). Two analyzed muscles were affected differently, and muscle rich in type I fibers was more susceptible to fetal programming. We conclude that fetal programming, seen as a reduced VO(2max) in adulthood, results from gestational undernutrition. Postnatal high-fat diet results in a pronounced RCR and VO(2max) increase in adolescence. However, these effects are reversible by diet correction and are not maintained in adulthood.

Identification of a novel human glucagon receptor promoter: regulation by cAMP and PGC-1alpha.

Previously we have demonstrated that glucagon receptor mRNA expression in cultured rat hepatocytes and pancreatic islets can be regulated by various factors, including cAMP; however, the regulation of the human glucagon receptor gene has not been well-defined. Here we have characterized the promoter regions of the human glucagon receptor gene. Primer extension studies yielded multiple products in both liver and pancreas, corresponding to transcription start sites situated at -166 and -477 relative to the start of translation, indicating two putative promoters. Both transcription start sites were found to be active, when sequence immediately upstream of the start sites were cloned into luciferase reporter constructs. The transcriptional activity of the proximal promoter, but not the distal promoter, could be inhibited approximately 50% by cAMP, indicating that the previously observed inhibitory effects of cAMP on glucagon receptor mRNA expression is mediated at the level of gene transcription. The cAMP-mediated downregulation of the proximal promoter was examined by deletion analysis in the human hepatoma cell line HepG2 and the cAMP responsiveness was found to be located in a region between 1051 and 1016 base pairs upstream of the transcription start site, which contains several putative cAMP responsive elements. Expression of peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC-1alpha), known to be upregulated in the liver by fasting, was found to abolish the cAMP-dependent downregulation of glucagon receptor mRNA expression in vitro, whereas overexpression of PGC-1beta had no effect.

Your mitochondria are what you eat: a high-fat or a high-sucrose diet eliminates metabolic flexibility in isolated mitochondria from rat skeletal muscle.

Extreme diets consisting of either high fat (HF) or high sucrose (HS) may lead to insulin resistance in skeletal muscle, often associated with mitochondrial dysfunction. However, it is not known if these diets alter normal interactions of pyruvate and fatty acid oxidation at the level of the mitochondria. Here, we report that rat muscle mitochondria does show the normal Randle-type fat-carbohydrate interaction seen in vivo. The mechanism behind this metabolic flexibility at the level of the isolated mitochondria is a regulation of the flux-ratio: pyruvate dehydrogenase (PDH)/ß-oxidation to suit the actual substrate availability, with the PDH flux as the major point of regulation. We further report that this regulatory mechanism of carbohydrate-fat metabolic interaction surprisingly is lost in mitochondria obtained from animals exposed for 12 weeks to a HF- or a HS diet as compared to rats given a normal chow diet. The mechanism seems to be a loss of the PDH flux decrease seen in controls, when fatty acid is supplied as substrate in addition to pyruvate, and vice versa for the supply of pyruvate as substrate to mitochondria oxidizing fatty acid. Finally, we report that the calculated TCA flux in the isolated mitochondria under these circumstances shows a significant reduction (~50%) after the HF diet and an even larger reduction (~75%) after the HS diet, compared with the chow group. Thus, it appears that obesogenic diets as those applied here have major influence on key metabolic performance of skeletal muscle mitochondria.

One-year high fat diet affects muscle-but not brain mitochondria.

It is well known that few weeks of high fat (HF) diet may induce metabolic disturbances and mitochondrial dysfunction in skeletal muscle. However, little is known about the effects of long-term HF exposure and effects on brain mitochondria are unknown. Wistar rats were fed either chow (13E% fat) or HF diet (60E% fat) for 1 year. The HF animals developed obesity, dyslipidemia, insulin resistance, and dysfunction of isolated skeletal muscle mitochondria: state 3 and state 4 were 30% to 50% increased (P<0.058) with palmitoyl carnitine (PC), while there was no effect with pyruvate as substrate. Adding also succinate in state 3 resulted in a higher substrate control ratio (SCR) with PC, but a lower SCR with pyruvate (P<0.05). The P/O2 ratio was lower with PC (P<0.004). However, similar tests on isolated brain mitochondria from the same animal showed no changes with the substrates relevant for brain (pyruvate and 3-hydroxybutyrate). Thus, long-term HF diet was associated with obesity, dyslipidemia, insulin resistance, and significantly altered mitochondrial function in skeletal muscle. Yet, brain mitochondria were unaffected. We suggest that the relative isolation of the brain due to the blood-brain barrier may play a role in this strikingly different phenotype of mitochondria from the two tissues of the same animal.

Application of human leukocyte antigen matching in the allocation of kidneys from cadaveric organ donors in the Nordic countries.

The Nordic organ exchange organization Scandiatransplant was founded in 1969. It covers a population of 24.41 million inhabitants in five countries: Denmark (5.45 million), Finland (5.19 million), Iceland (0.29 million), Norway (4.54 million), and Sweden (8.94 million). Initially, the purpose of Scandiatransplant was to establish and maintain a common waiting list for all Nordic patients with end-stage renal failure waiting for a cadaveric kidney transplant. The basis of maintaining a common Nordic waiting list was the recognition of the wide polymorphism of the human leukocyte antigen system, which demands a substantial pool of waiting patients to provide optimal histocompatibility matching between organ donor and recipient. Thus, one of the major tasks of the organization was and still is to specify rules for the exchange of kidneys between the participating transplant centers. Scandiatransplant includes the cooperation of all 10 Nordic kidney transplant centers in addition to eight immunology laboratories. Denmark has four transplant centers located in Copenhagen, Herlev, Odense, and Aarhus. Finland has one center in Helsinki. Norway has one center located in Oslo. Sweden has four kidney transplantation centers located in each of the university hospitals in Göteborg, Malmö, Stockholm, and Uppsala. The fifth Nordic country, Iceland, is participating fully in organ donation but has no individual transplant center. Organ transplantation in Icelandic patients is performed in other Nordic countries.

[Transformation of sugar and other carbohydrates into fat in humans]. / Omdannelse af sukker og andre kulhydrater til fedt hos mennesker.

The basic biochemistry of de novo lipogenesis and the current understanding of fat formation from carbohydrates in humans are reviewed. The suggestion is made that ingestion of carbohydrates in excess of the caloric needs necessarily results in de novo lipogenesis since the glycogen stores are already full. Under these circumstances a formation per day of 15-20 g palmitate from carbohydrates has been reported in the liver and a similar amount in the peripheral tissues.