Incidence of seropositive and seronegative rheumatoid arthritis in Denmark: a nationwide population-based study.

OBJECTIVE: To investigate and compare trends in incidence rates (IRs) of seropositive and seronegative rheumatoid arthritis (RA) in Denmark using various data sources for serostatus definition. METHOD: This nationwide population-based cohort study was based on data from Danish healthcare and clinical quality registries between 2000 and 2018. Information on anti-cyclic citrullinated peptide and immunoglobulin M rheumatoid factor was obtained, and definitions of seropositivity according to the number of applied data sources were prespecified. Annual age- and sex-standardized IRs were calculated as the number of incident seropositive and seronegative cases, divided by the number of person-years (PY) in the general population in that given year. RESULTS: An increasing temporal trend in IR of seropositive RA and a decreasing trend in seronegative RA were observed. The IRs were higher for seropositive RA than for seronegative RA from 2009 onwards, with a widening of the IR gap between 2009 and 2016 regardless of the definition of seropositivity. When combining laboratory- and physician-reported autoantibody information and ICD-10 codes, the IR of seropositive RA in 2018 was approximately twice that of seronegative RA, at 19.0 and 9.0 per 100 000 PY, respectively. The level of antibody testing increased significantly during the study period. CONCLUSIONS: The IR of seropositive RA increased over time, whereas the IR of seronegative RA decreased. Temporal IR changes may be caused by a real change in the RA serology subtypes, an increase in autoantibody testing and availability, changes in registration practice over time, or a combination of these factors.

Incidence and prevalence of rheumatoid arthritis in Denmark from 1998 to 2018: a nationwide register-based study.

OBJECTIVE: To investigate the incidence and prevalence of rheumatoid arthritis (RA) in the adult Danish population. METHOD: In this nationwide register-based cohort study, patients with incident RA between 1998 and the end of 2018 were identified using Danish administrative registries. The age- and sex-standardized incidence rate (IR), incidence proportion (IP), lifetime risk (LR), and point prevalence (PP) of RA were calculated. RA was defined as a first-time RA diagnosis registered in the Danish National Patient Registry combined with a redeemed prescription of a conventional synthetic disease-modifying anti-rheumatic drug in the following year. In addition, three different case definitions of RA were explored. RESULTS: The overall age- and sex-standardized IR of RA from 1998 to 2018 was 35.5 [95% confidence interval (CI) 35.1-35.9] per 100 000 person-years while the IP was 35.2 (95% CI 34.8-35.5) per 100 000 individuals. The IR was two-fold higher for women than for men. The LR of RA ranged from 2.3% to 3.4% for women and from 1.1% to 1.5% for men, depending on the RA case definition used. The overall PP of RA was 0.6% (95% CI 0.5-0.6%) in 2018: 0.8% (95% CI 0.7-0.8%) for women and 0.3% (95% CI 0.3-0.4%) for men. The prevalence increased about 1.5-fold from 2000 to 2018. CONCLUSION: The IR and PP were approximately two-fold higher for women than for men. The prevalence of RA in Denmark increased significantly from 2000 to 2018. The RA case definition had more impact on the results than the choice of denominator.

In vivo MR imaging of magnetically labeled human embryonic stem cells.

INTRODUCTION: Human embryonic stem cells (hES) have emerged as a potentially new therapeutic approach for treatment of heart and other diseases applying the concept of regenerative medicine. A method for in vivo visualization and tracking of transplanted hES would increase our understanding of in vivo hES behavior in both experimental and clinical settings. The aim of this study was to evaluate the feasibility of magnetic labeling and visualization of hES with magnetic resonance imaging (MRI). METHODS: hES were established and expanded according to standard procedures. After expansion, the cells were cultured under feeder free conditions and magnetically labeled by addition of dextran-coated Ferrum-oxide particles (Endorem) to the medium. Accumulation of small particles of iron-oxide (SPIO) in hES was assessed by Prussian blue staining and electron microscopy. For in vitro MRI, the labeled and unlabeled hES were examined in cell solution and after transplantation into explanted mouse heart ( approximately 100,000 cells) on a Bruker Avance DMX 500 vertical magnet at 11.75 T. A multi-slice, multi spin-echo T(2)-weighted images were obtained. For in vivo imaging, the experiments were performed on male Sprague-Dawley using Bruker Biospec 2.35 T magnet. The hES were directly injected ( approximately 500,000 cells) after surgical procedure (thoracotomy) into anterior left ventricular (LV) wall. Multi-slice T(2)-weighted gradient echo images were obtained using cardiac gating. RESULTS: hES appeared to be unaffected by magnetic labeling and maintained their ability to proliferate and differentiate. No additive agent for membrane permeabilisation was needed for facilitation of intracellular SPIO accumulation. Prussian blue and electron microscopy have revealed numerous iron particles in the cytoplasm of hES. On T(2)-weighted images, the labeled cells have shown well-defined hyopintense areas at the site of injection in anterior LV wall both in vitro and in vivo. CONCLUSIONS: It is feasible to magnetically label and visualize hES both in vitro and in vivo. MR visualization of magnetically labeled hES may be a valuable tool for in vivo tracking of hES.

Ischemic preconditioning can overcome the effect of moderate to severe cold ischemia on concordant mouse xeno-heart transplants.

PURPOSE: Concordant mouse xeno-heart transplants are relatively sensitive to ischemia-reperfusion injury. We investigated the effect of an ischemic preconditioning (IPC) protocol on the functional and biochemical outcome of mouse xenohearts transplanted to the Lewis rat. MATERIAL AND METHODS: NMRI mice (30 to 40 g) were anesthetized, intubated, and mechanically ventilated. They were subjected either to a IPC protocol leading to an SaO(2) of 70% for 5 minutes followed by normoxia (defined as SaO(2) >90%) for 10 minutes (n = 9) or normoxia only (n = 11). The hearts were then heterotopically transplanted to Lewis rats (220 g). The frequencies of immediate onset and early dysfunction and late dysfunction were registered. The hearts surviving for 6 hours were explanted and the absolute concentrations of phosphocreatine and adenosine triphosphate (ATP) were determined in micromole per gram of heart tissue with high-pressure liquid chromatography. The phosphorylation ratio, PCr/ATP, a known correlate to biochemical and functional outcome, was calculated. RESULTS: Four of 11 (36.4%) of control hearts experienced immediate onset and early dysfunction versus 0% (0/9) in M hearts subjected to IPC (P = .01). Furthermore, the IPC protocol increased the PCr concentration, 15.08 +/- 1.00 versus 9.04 +/- 2.04 micromol/g in controls (P = .01), and the PCr/ATP ratio, 1.80 +/- 0.17 versus 1.27 +/- 0.21 (NS; P = .06). CONCLUSIONS: IPC provides a protective PCr overshoot overcoming the short-term effects of moderate to severe ischemic injury on mouse xeno-heart transplants.

Singlet oxygen energy illumination during moderate cold ischemia prolongs the survival of concordant hamster xeno-heart transplants.

INTRODUCTION: Singlet oxygen energy (SOE) is a potent inhibitor of reactive oxygen species (ROS) in vitro and in vivo in certain dose ranges and can improve the levels of high-energy phosphates (HEP) in concordant hamster xeno-heart transplants. Some data indicate that a certain degree of cold ischemia (CI) might be beneficial to xenotransplants. We investigated if SOE illumination of hamster xeno-hearts during moderate cold ischemia (CI) improved graft survival. MATERIALS AND METHODS: Eighteen hearts from Golden Syrian hamsters (70 to 80 g) were subjected to 8 hours of CI in cold (+4 degrees C) saline solution (NaCL, 0.9%) before heterotopic cervical transplantation to Lewis rats (220 g). Among the treatment group (n = 8), SOE was produced by illuminating the hearts for 10 minutes every 30 minutes with photons at lambda 634 nm with the Oxylight equipment. Graft function was evaluated every 6 hours after transplantation with digital exam until cessation of heart beats. RESULTS: The graft survival of SOE-illuminated ischemic hamster xenografts was 2.34 +/- 0.56 versus 1.15 +/- 0.37 days in the control group (P < .05). All hearts displayed immediate graft function versus 70% in the controls (NS). CONCLUSIONS: SOE illumination at lambda 634 nm during moderate cold ischemia (+4 degrees C) can improve the survival of concordant hamster xeno-heart transplants. The exact mechanism(s) are currently unknown, but the effect might in part be exerted by a combination of reduced production of ROS and increased oxidative phosphorylation.

Selective cerebral overexpression of growth hormone alters cardiac function, morphology, energy metabolism and catecholamines in transgenic mice.

BACKGROUND: Growth hormone (GH) has important regulatory effects on cardiac morphology and function both during normal development as well as in pathophysiological settings such as myocardial infarction (MI) and congestive heart failure (CHF). In order to investigate in more detail the interaction between GH and sympathetic nervous system (SNS) system we studied the effects of selective cerebral GH overexpression on myocardial content of catecholamines, myocardial and brain energy metabolism as well as on cardiac function during resting and stress conditions in a transgenic mouse model. METHODS: Transgenic mice with selective bovine GH overexpression under control of glial fibrillary acidic protein promoter in the brain (GFAP-bGH, n=15) were created and compared to genetically matched non-transgenic mates (Control, n=15). Cardiac morphology and function were evaluated in vivo using transthoracic echocardiography during resting and stress conditions induced pharmacologically by dopamine (D) and isoprotenolol (ISO). Myocardial and brain energy metabolism were evaluated non-invasively using in vivo volume-selective phosphorus magnetic resonance spectroscopy ((31)P MRS). Myocardial content of catecholamines was analyzed by means of HPLC. RESULTS: Compared to the C animals, the GFAP-bGH mice have showed several differences in the cardiac phenotype. Systolic (fractional shortening) and diastolic function (E/A wave ratio of mitral flow) was disturbed in the GFAP-bGH mice (both p<0.05). During the dopamine stress, there was chronotropic insufficiency in the GFAP-bGH group (p<0.01) while no difference was observed in response to isoprotenolol. Left ventricular dimensions were increased in GFAP-bGH mice (p<0.05). There was a tendency for higher body weight in GFAP-bGH compared to the control group (p=0.06) while no difference was observed in heart weight and brain weight when normalized for body weight. Myocardial content of noradrenaline was lower in the GFAP-bGH group (p<0.05). PCr/ATP ratio was higher (p<0.05) in the brain and lower in the heart (p<0.05) in the GFAP-bGH mice. CONCLUSIONS: Selective cerebral overexpression of GH results in alterations of cardiac function, morphology and metabolism in transgenic mice. Decreased myocardial content of catecholamines in the GFAP-bGH mice suggests central interaction between GH and sympathetic nervous system.

Selective beta1-blockade attenuates post-infarct remodelling without improvement in myocardial energy metabolism and function in rats with heart failure.

OBJECTIVE: To investigate in vivo effects of long-term selective beta1-blockade on cardiac energy metabolism, remodelling, function and plasma cytokines in a rat model of post-infarct congestive heart failure (CHF). METHODS: Myocardial infarction (MI) was induced in male rats by ligation of the left coronary artery. Three different groups of rats were studied, MI rats treated with metoprolol (n=17), MI rats treated with saline (n=14) and sham-operated rats (n=12). The treatment with metoprolol 1 mg/kg/h was initiated in the third week post-infarct for a period of 6 weeks. All rats were investigated non-invasively with volume-selective 31P magnetic resonance spectroscopy and echocardiography for evaluation of left ventricular (LV) energy metabolism, morphology and function. Plasma concentration of IL-1beta and IL-6 and density of beta-adrenergic receptors were analyzed. RESULTS: Metoprolol attenuated the increase in LV dimensions and volumes. Treatment with metoprolol had no effect on PCr/ATP and LV function. Plasma level of IL-1beta was higher and IL-6 was lower in the metoprolol group. Density of beta-adrenergic receptors was similar in all three groups. CONCLUSION: Selective beta1-blockade in rats with chronic CHF attenuates post-infarct structural remodelling, without concomitant improvement in myocardial energy metabolism and function. Improvements in myocardial energy metabolism and function do not precede and are not a prerequisite for an anti-remodelling effect of beta1-blockade in the setting of chronic CHF.

A novel evaluation of subcutaneous formulations by in vivo magnetic resonance imaging (MRI).

The applicability of magnetic resonance imaging (MRI) for non-invasive in vitro studies of parenteral vehicles without use of marker substances was investigated. A wide range of extended release (ER) formulations such as oils, a lipid emulsion, and water solutions of a cyclodextrin and block co-polymers were visualized in vitro and in vivo by a (1)H-MRI technique. The study included measurements in vitro in a beaker and by injections in pig flesh. In vivo studies were carried out in rats. The contrast of the vehicles vs the background material could be visualized and quantifications of vehicle dispersion and disappearance were performed on obtained in vivo data. A wide range of different vehicles suitable for s.c. ER delivery were tested, such as different oils, a lipid emulsion, and water solutions of a cyclodextrin and block co-polymers. The vehicle volume expansion in vivo was possible to follow. However, this was not generally applicable for all kinds of vehicle component. The tested co-polymers, Poloxamers, were one type of vehicle component that provides an excellent MRI signal. The in vitro tests predicted the suitability of this vehicle for in vivo MRI studies. In the in vivo study of the block co-polymer formulations the apparent vehicle volume increased to a peak value from an initial value close to the injected volume. Thereafter the volume diminished and no vehicle could be detected after 29 h after injection. MRI could be applied for measurements of the dispersion and disappearance of some vehicles at the site of injection after s.c. administration without use of contrast agents.

Disturbance of purine nucleotide metabolism: a possible early key event in development of intestinal damage induced by chemotherapy.

Protective strategies to minimize the hematological toxicity in connection with bone marrow transplantation (BMT) have been successful, but toxicity to the gastrointestinal tract prevents further dose escalation and therefore limits the application of the treatment. As it is known that chemotherapy leads to disruption of the intestinal barrier and morphological changes of mitochondria in enterocytes, this study was conducted in order to investigate intestinal energy metabolism and permeability after intensive cytotoxic therapy in rats. Intestinal damage was produced by intraperitoneal administration of the cytostatic etoposide. Intestinal permeability was assessed by a [51Cr]EDTA absorption test and intestinal purine nucleotide content by a high-performance liquid chromatography (HPLC) technique. Four hours after the administration of etoposide, and the next 48 hr, there was a significant increase in the intestinal permeability (P < 0.05) and a significant reduction of the purine nucleotide content in the intestinal epithelial cells (P < 0.01) as compared to control animals. This early disturbance in enterocyte energy metabolism may be a key event in the development of the intestinal damage, induced by chemotherapy, and an explanation for the early disruption of the intestinal barrier demonstrable before morphological changes are evident.

Selective beta(1)-blockade improves cardiac bioenergetics and function and decreases neuroendocrine activation in rats during early postinfarct remodeling.

In spite of the solid evidence that beta-blockade reduces mortality and morbidity in congestive heart failure (CHF) this therapy continues to be underused in clinical praxis. The reason for this may lie in scarcity of knowledge about the mechanisms of beta-blockade action. The major aim of this study was to investigate in vivo whether selective beta(1)-blockade may improve cardiac energy metabolism in rats with myocardial infarction in early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague-Dawley rats by ligation of the left coronary artery. Two different groups of rats were studied, rats with MI treated with metoprolol (5 mg/kg/h; n = 9) and rats with MI saline treated (n = 9). The treatment with metoprolol was given by subcutaneously implanted minipumps and was initiated at 3 days postinfarct and during the period of 4 weeks. All rats were investigated with noninvasive methods (31)P magnetic resonance spectroscopy (MRS) and transthoracic echocardiography 3 days after induction of MI and 4 weeks later. Phosphocreatine/ATP ratio was normalized after the treatment with metoprolol while it was 50% lower in the saline group (p < 0.001). In the metoprolol group stroke volume and ejection fraction increased while deceleration time of mitral early filling was longer (all p < 0.05). Left ventricular weight as well as volumes and dimensions were similar between the groups. Plasma levels of noradrenaline (p = 0.058), adrenaline (p < 0.01) and brain natriuretic peptide (p = 0.09) were lower in the metoprolol group. Selective beta(1)-blockade with high dose of metoprolol initiated in the early postinfarct phase improves myocardial energy metabolism and function and prevents overactivation of sympathetic system. The beneficial effect on myocardial bioenergetics may be an important mode of action of beta-blockers which contributes to the clinical benefits of the therapy in CHF.

Decreasing ratios of phosphocreatine to beta-ATP correlates to progressive acute rejection in a concordant mouse heart to rat xenotransplantation model.

Biopsies are difficult to perform in rodent heart transplant models without compromising the graft function and therefore other means to evaluate the grafts repeatedly and noninvasively are warranted. The goal of the present study was to measure changes in ratios of high energy phosphorus containing metabolites detected with in vivo 31Phosphorous Magnetic Resonance Spectroscopy ((31)P MRS) in a xenotransplantation model and to investigate if these ratios correlated to histological signs of acute xenograft rejection. Thirty-five heart transplantations were performed (NMRI-mice to Lewis (RT1(1)) rats). Thirteen heart transplants underwent repeated daily in vivo (31)P MRS measurements and 22 grafts were measured on any of 4 postoperative days and thereafter sacrificed for histology. A modified scoring system based on Billingham's criteria was used to stage the rejection process. The median graft survival was 3.0 +/- 0.44 (median +/- SD) days (n = 17). Significant differences, both overall and interday, could be calculated for the phosphocreatine (PCr)/beta-adenosine triphosphate (beta-ATP) ratios and for the rejection score. The decreases in PCr/beta-ATP ratios correlated significantly to the progressive acute rejection process in the sacrificed grafts (P = 0.01). Further studies are indicated to establish the potential of (31)P MRS in immunosuppressed recipients of vascularized xenotransplants with prolonged graft survival.

Effect of hypothermia on the ischemic and reperfused rat skeletal muscle, monitored by in vivo (31)P-magnetic resonance spectroscopy.

The aim of this study was to compare the ischemic and postischemic energetic changes of rat skeletal muscle in response to hypothermia or room temperature, monitored noninvasively and continuously by in vivo (31)P-magnetic resonance spectroscopy ((31)P-MRS). A model of pedicled rat rectus femoris muscle was developed and analyzed by in vivo (31)P-MRS at a magnetic field strength of 2.35 T. Measurements were performed at three time points: before ischemia, after 4 hours of ischemia, and after 1 hour of reperfusion. Three groups were studied: (1) sham-operated rats (n = 6); (2) rats subjected to room temperature (24-26 degrees C, n = 6); and (3) rats subjected to hypothermia (9-12 degrees C, n = 6). Blood perfusion was measured by laser Doppler flowmetry (LDF). In the hypothermic group, phosphocreatine (PCr) recovered to 75% and adenosine triphosphate (ATP) to 86%; in the room temperature group, the recovery was 53% and 51%, respectively (P < 0.05). Skeletal muscle subjected to hypothermia (9-12 degrees C) was found to recover to a higher postischemic energetic level compared with skeletal muscle subjected to room temperature. Hypothermia appears to be a simple and effective method with which to reduce the damage related to ischemia and reperfusion.

Growth hormone improves bioenergetics and decreases catecholamines in postinfarct rat hearts.

The aims of this study were to examine, in vivo, the effects of GH treatment on myocardial energy metabolism, function, morphology, and neurohormonal status in rats during the early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague Dawley rats. Three different groups were studied: MI rats treated with saline (n = 7), MI rats treated with GH (MI + GH; n = 11; 3 mg/kg x day), and sham-operated rats (sham; n = 8). All rats were investigated with 31P magnetic resonance spectroscopy and echocardiography at 3 days after MI and 3 weeks later. After 3 weeks treatment with GH, the phosphocreatine/ATP ratio increased significantly, compared with the control group (MI = 1.69 +/- 0.09 vs. MI + GH = 2.42 +/- 0.05, P < 0.001; sham = 2.34 +/- 0.08). Treatment with GH significantly attenuated an increase in left ventricular end systolic volume and end diastolic volume. A decrease in ejection fraction was prevented in GH-treated rats (P < 0.05 vs. MI). Myocardial and plasma noradrenaline levels were significantly lower in MI rats treated with GH. These effects were accompanied by normalization of plasma brain natriuretic peptide levels (sham = 124.1 +/- 8.4; MI = 203.9 +/- 34.7; MI + GH = 118.3 +/- 8.4 ng/ml; P < 0.05 vs. MI). In conclusion, GH improves myocardial energy reserve, preserves left ventricular function, and attenuates pathologic postinfarct remodeling in the absence of induction of left ventricular hypertrophy in postinfarct rats. The marked decrease in myocardial content of noradrenaline, after GH treatment, may protect myocardium from adverse effects of catecholamines during postinfarct remodeling.

Impairment of cardiac function and bioenergetics in adult transgenic mice overexpressing the bovine growth hormone gene.

Cardiovascular abnormalities represent the major cause of death in patients with acromegaly. We evaluated cardiac structure, function, and energy status in adult transgenic mice overexpressing bovine GH (bGH) gene. Female transgenic mice expressing bGH gene (n = 11) 8 months old and aged matched controls (n = 11) were used. They were studied with two-dimensional guided M-mode and Doppler echocardiography. The animals (n = 6) for each group were examined with 31P magnetic resonance spectroscopy to determine the cardiac energy status. Transgenic mice had a significantly higher body weight (BW), 53.2+/-2.4 vs. 34.6+/-3.7 g (P < 0.0001) and hypertrophy of left ventricle (LV) compared with normal controls: LV mass/BW 5.6+/-1.6 vs. 2.7+/-0.2 mg/g, P < 0.01. Several indexes of systolic function were depressed in transgenic animals compared with controls mice such as shortening fraction 25+/-3.0% vs. 39.9+/-3.1%; ejection fraction, 57+/-9 vs. 77+/-5; mean velocity of circumferential shortening, 4.5+/-0.8 vs. 7.0+/-1.1 circ/sec, p < 0.01. Creatine phosphate-to-ATP ratio was significantly lower in bGH overexpressing mice (1.3+/-0.08 vs. 2.1+/-0.23 in controls, P < 0.05). Ultrastructural examination of the hearts from transgenic mice revealed substantial changes of mitochondria. This study provides new insight into possible mechanisms behind the deteriorating effects of long exposure to high level of GH on heart function.

In vivo metabolic imaging of cardiac bioenergetics in transgenic mice.

Recent advances in transgenic technology have made the mouse a particularly interesting small animal in cardiovascular research. Increasingly sophisticated experimental methods and tools are needed for detailed characterization of cardiovascular physiology and biochemistry in the mice. The objective of this study was to develop a method for noninvasive evaluation of cardiac energy metabolism in the mouse. Cardiac gated (31)P magnetic resonance spectroscopy using Image Selected in Vivo Spectroscopy (ISIS) method was applied in old mice overexpressing bovine growth hormone (bGH) (n = 5) and control mice (n = 5). The localized volumes of interest were 128 and 112 microL, respectively. Phosphocreatine-to-ATP ratio was 1.5 +/- 0.13 in the bGH mice and 2.1 +/- 0.04 in the control group (P < 0.01). The study demonstrates the feasibility of application of volume-selective (31)P MRS for evaluation of cardiac energy metabolism in the mouse under maintained physiological conditions.

Liquid chromatography "on-flow" 1H nuclear magnetic resonance on native glycosphingolipid mixtures together with gas chromatography/mass spectrometry on the released oligosaccharides for screening and characterisation of carbohydrate-based antigens from pig lungs.

Glycosphingolipids were prepared from pig lung and pooled into two fractions with (i) < or = 3 sugar residues, and (ii) > or = 3 sugar residues. Oligosaccharides were prepared and used for gas chromatography, gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry. The glycolipid fractions i and ii were further characterised and purified using a novel method based on high performance liquid chromatography "on-flow" proton nuclear magnetic resonance. The LC "on-flow" NMR technique showed good chromatographic separation and gave NMR spectral information which could be used as guidance for pooling of the separated mixture glycolipids. Conventional 1H NMR, thin layer immunostaining, gas chromatography, gas chromatography/mass spectrometry and matrix-assisted laser desorption/ionization mass spectrometry were used to characterise the glycolipids and to validate LC-NMR spectral data.

Bioenergetic, functional and morphological consequences of postinfarct cardiac remodeling in the rat.

Despite recent advances in the treatment, severe chronic heart failure (CHF) remains a syndrome associated with high mortality. Therefore, the search for new agents to improve both patient symptoms and survival, as well as the pursuit for detailed knowledge about pathophysiology of the failing heart, will continue to depend on relevant animal models. Large acute myocardial infarction (MI) initiates complex changes in the geometrical, structural, and biochemical architecture of both infarcted and non-infarcted regions of ventricular myocardium, which can profoundly affect left ventricular function and prognosis. In this paper we present a new model for non-invasive cardiac (31)P MRS in the rat. Volume-selective (31)P magnetic resonance spectroscopy and echocardiography were used for evaluation of myocardial energy metabolism, cardiac morphology and function in rats 3 days and 3 weeks after induction of large MI. The phosphocreatine:adenosine triphosphate (PCr:ATP) ratio was decreased in rats with MI comparing with controls both at 3 days (1.6+/-0.06 vs 2.7+/-0.04; mean+/-s.e.m. P<0.0001) and 3 weeks (1.6+/-0.07 v 2.7+/-0.02 P<0.0001) postinfarct. The results from the study demonstrate that postinfarct cardiac remodeling is a rapid process of changes not only in cardiac geometry, structure and function but also in myocardial energy metabolism after large transmural MI in the rat.

Mouse extensor digitorum longus muscle preparation as a tool in nutrition research: a quantitative comparison to in vivo and cell culture experiments.

Incubated restrained and unrestrained extensor digitorum longus (EDL) muscles from adult non-growing mice were evaluated as a tool in non-steady state nutrition experiments. Energy state was determined by nucleotide determinations in muscles. Protein synthesis was estimated by the amount of L-[U-14C]phenylalanine incorporated into proteins, and protein balance was measured by tyrosine release from muscle proteins. Confluent cultured L6 rat muscle cells served as a reference system in steady state without hypoxia being sensitive to growth factors and regulatory peptides at physiologic concentrations. Irrespective of medium composition, incubated EDL muscles remained in negative protein balance, being unrelated to the resting tension of the incubated muscles. Energy-rich phosphates were not restored to normal levels during incubation, but protein synthesis was not attenuated by the decline in energy state. Fractional protein synthesis (0.05-0.15%/h) remained constant for up to 6 h of EDL incubation, and was comparable to protein synthesis in cultured confluent non-proliferating myocytes (0.20-0.30%/h) and to mixed leg muscles measured in vivo (0.10-0.20%/h). Protein synthesis in incubated EDL muscles reflected alterations in muscle peptide formation in vivo following either oral provision of food or parenteral injection of insulin. EDL muscles were sensitive to in vitro exposure to both insulin (60-125 microU/mL) and insulin-like growth factor 1 (IGF-1) (1000 ng/mL). The sensitivity to insulin seemed to be modified by the nutritional state (starved/fed) of the animals before sacrifice. Protein synthesis in EDL muscles was less responsive to serum-containing growth factors (IGF-1, epidermal growth factor [EGF], platelet-derived growth factor [PDGF]) compared to confluent L6 muscle cells, which probably reflected different receptor expression. Our results demonstrate that protein metabolism in incubated unrestrained mouse EDL muscles reflects in vivo protein metabolism.

Harmful singlet oxygen can be helpful.

Highly reactive harmful singlet oxygen O2(1delta(g)) can be helpful while relaxing to its triplet ground state O2(3sigma(g)-). The energy emitted during this relaxation from the excited energy state is discernable at 634 nm. We report here on the effect of this energy as photon illumination and as energy transfer in air on the production of reactive oxygen species (ROS) by human monocytes, measured as isoluminol-enhanced chemiluminescence. We demonstrate up to 60% decrease in the secretion of ROS after 2-min illumination of the monocytes stimulated with phorbol myristate acetate (PMA). The results provide in vitro documentation of the utility of singlet oxygen energy in modifying cellular behaviour.