Metabolic control level and glucose variability in adolescents with type 1 diabetes during low and high-intensity exercise

OBJECTIVE

The main purpose of this study was to characterize the determinants of metabolic changes in young type 1 diabetes (T1DM) and to determine glycemic variability during low and high-intensity exercise.

PATIENTS AND METHODS

20 young male T1DM patients were divided into two subgroups characterized by levels of glycated hemoglobin (HbA1c): HbA1c<7.3% (better HbA1c subgroup, n=10) and with levels HbA1c>7.3% (worse HbA1c subgroup, n=10). All participants performed a maximal oxygen uptake test and two efforts of various intensities (45 minutes of aerobic exercise and 30 minutes of mixed aerobic-anaerobic intensity exercise). Continuous glucose monitors (CGM) were used to control the glucose concentration.

RESULTS

Changes in biomarkers describing the metabolic response were similar in both groups. A comparison of applied efforts exhibited that maximal capacity effort resulted in the highest values of blood glucose (BG) at the end (150.9-160.6 mg/dl) and 1 hour after the exercise (140.2-161.3 mg/dl). BG concentration before, during, 1 hour, and 24 hours after each exercise was insignificantly higher in the worse Hb1Ac group.

CONCLUSIONS

HbA1c levels are insufficient to confirm whether the applied effort is performed in acceptable glycemic values. The CGM monitors allow for precise control of BG variations and accurate planning of physical activity by adjusting the insulin and carbohydrate consumption dose.

Reinvestigation of Na5GdSi4O12: A Potentially Better Solid Electrolyte than Sodium β Alumina for Solid-State Sodium Batteries

Developing high-performing solid electrolytes that could replace flammable organic liquid electrolytes is vital in designing safer solid-state batteries. Among the sodium-ion (Na+) conducting solid electrolytes, Na-β″-alumina (BASE) is highly regarded for its employment in solid-state battery applications due to its high ionic conductivity and electrochemical stability. BASE has long been employed in commercial Na-NiCl2 and Na-S batteries. However, the synthesis of highly conductive BASE is energy-intensive, involving elevated temperatures for sintering and the incorporation of stabilizing additives. Additionally, BASE is highly sensitive to humidity, which limits its applications. Hence, there is an intense search to identify suitable high-performing solid electrolytes that could replace BASE. In this context, we reinvestigated Na5GdSi4O12 (NGS) and demonstrated that phase pure NGS could be synthesized by a simple solid-state reaction. Beyond a high ionic conductivity of 1.9 × 10-3 S cm-1 at 30 °C (1.5 × 10-3 S cm-1 for BASE), NGS exhibited high chemical as well as electrochemical stability, lower interfacial resistance, lower deposition and stripping potential, and higher short-circuiting current, designating NGS as a better solid electrolyte than BASE.

Higher-Order Optimality Conditions in Set-Valued Optimization with Respect to General Preference Mappings

We present higher order necessary conditions for a model of welfare economics, where the preference mapping has a star-shape property. We assume that the preferences can be satiable and can be described by an arbitrary preference set, without the use of utility functions. These conditions are formulated in terms of higher-order directional derivatives of multivalued mappings, and the variable domination structure is not given by cones.

Model of the Vibration Signal of the Vibrating Sieving Screen Suspension for Condition Monitoring Purposes

Diagnostics of industrial machinery is a topic related to the need for damage detection, but it also allows to understand the process itself. Proper knowledge about the operational process of the machine, as well as identification of the underlying components, is critical for its diagnostics. In this paper, we present a model of the signal, which describes vibrations of the sieving screen. This particular type is used in the mining industry for the classification of ore pieces in the material stream by size. The model describes the real vibration signal measured on the spring set being the suspension of this machine. This way, it is expected to help in better understanding how the overall motion of the machine can impact the efforts of diagnostics. The analysis of real vibration signals measured on the screen allowed to identify and parameterize the key signal components, which carry valuable information for the following stages of diagnostic process of that machine. In the proposed model we take into consideration deterministic components related to shaft rotation, stochastic Gaussian component related to external noise, stochastic α-stable component as a model of excitations caused by falling rocks pieces, and identified machine response to unitary excitations.

Accuracy Evaluation of Selected Mobile Inspection Robot Localization Techniques in a GNSS-Denied Environment

Locating an inspection robot is an essential task for inspection missions and spatial data acquisition. Giving a spatial reference to measurements, especially those concerning environmental parameters, e.g., gas concentrations may make them more valuable by enabling more insightful analyses. Thus, an accurate estimation of sensor position and orientation is a significant topic in mobile measurement systems used in robotics, remote sensing, or autonomous vehicles. Those systems often work in urban or underground conditions, which are lowering or disabling the possibility of using Global Navigation Satellite Systems (GNSS) for this purpose. Alternative solutions vary significantly in sensor configuration requirements, positioning accuracy, and computational complexity. The selection of the optimal solution is difficult. The focus here is put on the assessment, using the criterion of the positioning accuracy of the mobile robot with no use of GNSS signals. Automated geodetic surveying equipment is utilized for acquiring precise ground truth data of the robot’s movement. The results obtained, with the use of several methods, compared: Wheel odometry, inertial measurement-based dead-reckoning, visual odometry, and trilateration of ultra-wideband signals. The suitability, pros, and cons of each method are discussed in the context of their application in autonomous robotic systems, operating in an underground mine environment.

Changes in lipid and apolipoprotein levels in response to 8-week cardiac rehabilitation in men with coronary artery disease

Concentrations of selected lipoproteins are currently useful cardiovascular risk assessment indicators, especially in monitoring lipid-lowering therapy.

AIM

The aim was to evaluate the influence of 8-week mid-term CR on apolipoproteins: A-I, B, E and VLDL in CAD patients in relation to conventional lipid profile and prior coronary intervention: PCI or CABG.

MATERIALS AND METHODS

93 male patients admitted to CR after PCI or CABG. At baseline and after CR, conventional lipid profile parameters and VLDL concentrations were evaluated. Apolipoproteins: A-I, B, E were also determined. Basic anthropometric indicators and measurements of hemodynamic and exercise tolerance at rest and peak workload in exercise testing (HR, sBP, dBP, DP, W) were measured.

RESULTS

After CR, depending on revasculazation intervention, no changes in HDL-C, LDL-C, TG and VLDL values were observed (p>0.05). Reduction in apoA-I was noted in PCI group (p=0.0254). No statistically significant changes in apoB and apoE were found in groups. Significant increase in apo B/apo A-I index was observed only in PCI group (p=0.0329). PCI and CABG patients did not differ in hemodynamic and exercise tolerance parameters, except sBP in rest and dBP at peak workload in exercise testing (p=0.014 and p=0.031). Regardless on type of intervention, there was observed statistically significant increase in Wpeak (p=0,0000 in both groups) and DPpeak (p=0.0000 in PCI-patients and p=0.0003 in CABGpatients) after CR.

CONCLUSIONS

CR has various effects on lipid concentrations. Indicators of conventional lipid profile and selected apolipoproteins are not optimal parameters allowing assessment of effectiveness of CR program in such a short time, this role is well fullfilled by the hemodynamic and physical exercise indices. Apo B/apo A-I ratio value suggests an increasing risk of IHD complications, especially in post- PCI group. CR program requires intensification of lipid-reducing therapy and education on lifestyle modification.

Gas-phase hydration of Mg2+ complexes with deprotonated uracil, thymine, uridine, and thymidine

The gas-phase hydration of Mg²⁺ complexes with deprotonated uracil (U), thymine (T), uridine (U_r , uracil riboside), and thymidine (T_dr , thymine deoxyriboside) was studied. The aim of the work was to analyze the hydration of product ions (eg, [2U-H+Mg]⁺ ) formed as a result of the collision induced dissociation of the respective parent ion (eg, [3U_r -H+Mg]⁺ ). The efficiency of gas-phase hydration of the ions [2U-H+Mg]⁺ and [2T-H+Mg]⁺ was similar. However, the efficiency of gas-phase hydration of the ion [U+U_r -H+Mg]⁺ was much higher than that of gas-phase hydration of the ion [T+T_dr -H+Mg]⁺ . On the basis of the mass spectra obtained and the performed molecular modelling, it was concluded that in the ion [T+T_dr -H+Mg]⁺ , we deal with a steric hindrance due to the presence of a sugar moiety, which affects water attachment. In the ion [U+U_r -H+Mg]⁺ , the position of the sugar moiety does not affect water attachment.

Gas-phase relative stabilities of Tl+-crown ether complexes and Rb+-crown ether complexes

The gas-phase stabilities of Tl⁺-crown ether complexes and Rb⁺-crown ether complexes were studied using the electrospray ionization-collision-induced dissociation-tandem mass spectrometry. Tl⁺ and Rb⁺ have identical ionic radii, thus a comparison of the properties of the crown ether complexes with these two cations seems to be justified. The selected crown ethers were 12C4 (it has a cavity smaller than the cation radius), 18C6 (it has a cavity of size similar to the cation radius), 24C8 (it has a cavity greater than the cation radius) and their conjugates. It has been found that the crown ether complexes of stoichiometry 1:1 with Tl⁺ are more or equally stable in the gas phase than the crown ether complexes with Rb⁺. However, 2:1 complexes with Tl⁺ are less stable than the complexes with Rb⁺.

Behavioral and Biochemical Impact of Chronic Unpredictable Mild Stress on the Acquisition of Nicotine Conditioned Place Preference in Rats

Addiction is a chronic psychiatric disease which represents a global problem, and stress can increase drug addiction and relapse. Taking into account frequent concomitance of nicotine dependence and stress, the purpose of the present study was to assess behavioral and biochemical effects of chronic unpredictable mild stress (CUMS) exposure on nicotine reward in rats measured in the conditioned place preference (CPP) paradigm. Rats were submitted to the CUMS for 3 weeks and conditioned with nicotine (0.175 mg/kg) for 2 or 3 days. Our results revealed that only CUMS-exposed animals exhibited the CPP after 2 days of conditioning indicating that stressed rats were more sensitive to the rewarding properties of nicotine and that chronic stress exacerbates nicotine preference. Administration of metyrapone (50 mg/kg), a glucocorticosteroid antagonist, and imipramine (15 mg/kg), an antidepressant, abolished nicotine CPP in stressed rats after 2 days of conditioning. The biochemical experiments showed increased markers of oxidative stress after nicotine conditioning for 2 and 3 days, while the CUMS further potentiated pro-oxidative effects of nicotine. Moreover, metyrapone reversed oxidative changes caused by stress and nicotine, while imipramine was not able to overwhelm nicotine- and stress-induced oxidative damages; however, it could exert antioxidant effect if administered repeatedly. The results suggest that recent exposure to a stressor may augment the rewarding effects of nicotine through anhedonia- and stress-related mechanisms. Our study contributes to the understanding of behavioral and biochemical stress-induced modification of the rewarding effects of nicotine on the basis of the development of nicotine dependence.

Behavioral and Biochemical Interaction Between Nicotine and Chronic Unpredictable Mild Stress in Mice

Nicotine, the main component of tobacco smoke, exerts influence on mood, and contributes to physical and psychological dependence. Taking into account frequent concomitance of nicotine abuse and stress, we aimed to research behavioral and biochemical effects associated with nicotine administration in combination with chronic unpredictable mild stress (CUMS). Mice were submitted to the procedure of CUMS for 4 weeks, 2 h per day. Our results revealed that CUMS-exposed animals exhibited behavioral alteration like anxiety disorders in the elevated plus maze (EPM) test, the disturbances in memory in the passive avoidance (PA) test and depressive effects in the forced swim test (FST). Moreover, nicotine (0.05–0.5 mg/kg), after an acute or subchronic administration decreased stress-induced depression- and anxiety-like effect as well as memory deficit. Administration of metyrapone (50 mg/kg), a glucocorticosteroid antagonist, alleviated the depressive effect induced by the CUMS. The biochemical experiments showed decreased values of the total antioxidant status (TAS), activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) with simultaneously increased in malondialdehyde (MDA) concentration in mice submitted to the CUMS. The same effects were observed after an acute and subchronic nicotine administration within all examined brain structures (i.e., hippocampus, cortex, and cerebellum) and in the whole brain in non-stressed and stressed mice confirming pro-oxidative effect of nicotine. Our study contributes to the understanding of behavioral and biochemical mechanisms involved in stress-induced disorders such as depression, anxiety and memory disturbances as well as dual nicotine-stress interactions on the basis of the development of nicotine dependence.

IN-VITRO ANTIMICROBIAL ACTIVITY OF BRONCHOSOL

Bronchosol is a traditional medicinal product in the form of syrup used in cough and impeded expectoration. The active ingredients that it contains include extracts from the herb of thyme, the root of primrose and thymol. It is recommended in disorders of the respiratory tract when expectoration is impeded and secretion of liquid mucus in bronchi is insufficient. Antimicrobial activity of the components of Bronchosol, especially thyme and thymol, has frequently been reported in the literature. To date, there have not been any studies to confirm such activity of Bronchosol, though. The results of our research are the first one to point to the great activity of Bronchosol against microorganisms causing infections of the respiratory tract. It has been demonstrated that this product displayed antimicrobial activity against reference strains as well as strains of anaerobic and aerobic bacteria and fungi isolated from patients. The confirmation of the antimicrobial activity of Bronchosol provides an explanation of its effectiveness in the therapy of the respiratory tract infections.

Antimicrobial activity of preparation Bioaron C

The antimicrobial activity of sirupus Bioaron C, a preparation, whose main ingredient is an extract from the leaves of Aloe arborescens, was tested against different microorganisms isolated from patients with upper respiratory tract infections. The experiments were performed on 40 strains: 20 strains of anaerobic bacteria, 13 strains of aerobic bacteria and 7 strains of yeast-like fungi from the genus Candida and on 18 reference strains (ATCC). The antimicrobial activity of Bioaron C (MBC and MFC) was determined at undiluted concentration. Bioaron C proved to be very effective against the microorganisms causing infections. At the concentration recommended by the producer, the preparation showed biocidal activity (MBC, MFC) against the strains of the pathogenic microorganisms, which cause respiratory infections most frequently, including, among others, Peptostreptococcus anaerobius, Parvimonas micra, Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Streptococcus anginosus, Haemophilus influenzae, Moraxella catarrhalis, Pseudomonas aeruginosa and Candida albicans, already after 15 min. The MIC of Bioaron C against most of the tested microorganisms was 5 to 100 times lower than the usually applied concentration. The great antimicrobial activity means that the preparation may be used in the prevention and treatment of infections of the upper respiratory tract. Bioaron C may be an alternative or complement to classical therapy, especially in children.

Ocular manifestations in a newborn from a pregnancy complicated by an antiphospholipid syndrome--a case report

The paper presents a case of ophthalmologic manifestations, episcleritis and retinal branch vein thrombosis, in a neonate born to a mother with antiphospholipid syndrome (APS) in the course of systemic lupus erythematosus. Female neonate (birth weight 1150 g, Apgar scores 6, 7 and 7) was born with respiratory distress syndrome, moderate anemia and grades I and II intraventricular hemorrhage. Ophthalmic examination revealed an enormous pre-retinal hemorrhage with accompanying thrombotic changes typical of retinal vein in the fundus of the left eye. Episcleritis was found in the anterior segment of the eye and later confirmed by ultrasound. Laboratory tests showed increased levels of maternal antibodies aCL IgG, antybeta2GP1 IgG and antybeta2GP1 IgM. No ANA, LA and SS-A/SS-B antibodies were detected. Increased concentrations of aCL IgG and a lengthening APTT were observed in newborn blood at first but the parameters normalized by 6 months of age. Our observations allowed us to conclude that early examination of neonates born to mothers with antiphospholipid syndrome is essential as it allows fast identification of pathological retinal changes by means of assessing the presence of aPL antibodies.

Acute respiratory distress syndrome (ARDS) complicating influenza A/H1N1v infection--a clinical approach

ARDS is defined as an acute inflammatory syndrome characterized with bilateral parenchymal lung infiltrates on chest radiograph and PaO2/FiO2 ratio<200 resulting from causes other than acute left ventricular dysfunction. Inflammatory lung lesions may be induced by different disorders, with sepsis being the leading cause of ARDS. Other causes include infectious pneumonia, aspiration of gastric contents, drugs, severe trauma, fat embolism, surface burn, massive blood transfusion. Influenza A/H1N1 infection seems to be responsible for the development of extremely severe type of ARDS with poor response to routine treatment. Despite great progress in the management of ARDS with novel agents and sophisticated techniques, including antimicrobial drugs, extracorporeal membrane oxygenation, prostaglandins, nitric oxide, prostacyclin, exogenous surfactant administration and activated protein C, supportive treatment based mostly on advanced mechanical ventilation in the intensive care units seems to be the most important for the prognosis.

Prolonged ventricular repolarization measured by corrected QT interval (QTc) in subclinical hyperthyroidism

Overt hyperthyroidism and hypothyroidism exert a major effect on cardiac function and on ECG. The influence of subclinical hyperthyroidism on the circulatory system is still under debate. Few studies examined the effect of thyroid hormones on ventricular repolarization measured by corrected QT interval (QTc). Longer QTc is associated with increased risk of arrhythmia and cardiac mortality. The aim of this study was to examine the influence of subclinical hyperthyroidism on ventricular repolarization measured by corrected QTc in a standard 12-lead electrocardiogram. The examined group consisted of thirty-two patients with subclinical hyperthyroidism; the controls were thirty-nine healthy individuals. In the group with subclinical hyperthyroidism, we observed a significant increase in heart rate (80.3 +/- 10.59 vs. 73.7 +/- 11.37 bpm, p < 0.05). The mean corrected QTc was 0.434 +/- 0.0207 seconds and 0.414 +/- 0.0208 in the examined groups and in controls, respectively (p < 0.001). QTc did not correlate with free thyroxin concentrations (p = 0.5084).

CONCLUSION

Corrected QT intervals were significantly longer in patients with subclinical hyperthyroidism.

Benign prostatic hyperplasia, prostate cancer and other prostate diseases diagnosed as a result of screening procedure among 1,004 men in the Lublin district

Urological problems especially connected with prostate diseases appear in older men: prostatitis, benign prostatic hyperplasia, prostate cancer and others. Prostate cancer is the most common cancer in men and the second leading cause of deaths in male population. Therefore, it seems important to early detect prostate cancer in general practice setting due to screening procedures such as digital rectal exam and prostate-specific-antigen test. The aim of the study was to examine the character of diagnoses of a prostate disease among 1,004 men of the Lublin district who reported to a doctor during screening procedure carried out in urology outpatient clinic at Clinical Hospital in Lublin in the year 2000. After physical examination urologists initially diagnosed a prostate disease and sent men suspected to have a prostate cancer to further investigations. There was studied age and place of living. Benign prostate hyperplasia was the most common diagnosis made in 77.1% of subjects. It occurred most often in men aged 51-70 years. Prostate cancer was suspected in 3.5% of subjects. Frequency of benign prostate hyperplasia and prostate cancer suspicion increased with age. On the basis of studies screening procedures seem beneficial in the early detection of prostate cancer in men over 50.

Increasing level of prostate-specific antigen and prostate cancer risk factors among 193 men examined in screening procedure

Prostate cancer is one of the most common cancers in men, therefore has become recently an essential problem of public health. The factors influencing cancer include: androgens metabolism disorders, diabetes mellitus, overweight and obesity, smoking, alcohol and black coffee intake, diet rich in saturated fats and poor in unsaturated, lack of physical activity, geographical zone, race, such carcinogenic substances as: cadmium, materials used in rubber, painting, printing, ship industry etc., contagious factors and also older age and a positive family history of the disease. To diagnose prostate cancer in its early stage such screening procedures as physical examination--digital rectal exam (DRE) and determination of prostate-specific antigen (PSA) level in blood serum are used. The aim of the study was to assess prostate cancer risk factors occurrence in the examined 193 men, aged 50-70 years, who reported to urology outpatient department at Clinical Hospital in Lublin, measure the PSA level in blood serum and examine the correlation between them. Respondents filled in a questionnaire about the presence of prostate cancer risk factors and urogenital symptoms. The questionnaire was completed with DRE and PSA measurement. The results led us to the following conclusions: 1/ in the studied population elevated PSA level is determined in 3.1% of 193 examined men, 2/ increased PSA occurs mainly in men from rural areas, with elementary education, divorced, older (>60 years), using fat-rich diet, smokers, black coffee drinkers, with overweight or obesity and non diabetic, 3/ a combination of PSA test with DRE seems to be useful and rather cheap for the detection of prostate cancer in the early stage of its development.

DFT studies on the copolymerization of alpha-olefins with polar monomers: ethylene-methyl acrylate copolymerization catalyzed by a Pd-based diimine catalyst

Gradient-corrected density functional theory has been used to study the elementary reactions for the copolymerization of ethylene with methyl acrylate catalyzed by Pd-based diimine catalysts, modeled by the generic complex N(wedge)N-Pd(n-C(3)H(7))(+), with N(wedge)N = -NHCHCHNH-. The steric effects in the real systems are discussed on the basis of the calculations for the catalyst with N(wedge)N = -NArCRCRNAr-, R = CH(3), and Ar = C(6)H(3)(i-Pr(2)) and the previous calculations on ethylene/propylene polymerization. Considerations have been given to the different possible acrylate complexes, as well as the transition states and the products (agostic complexes and the alternative chelates) for two acrylate insertion paths (1,2 and 2,1). The chelate-opening reactions have also been studied. The results revealed a strong electronic preference for the 2,1-insertion paths, with a barrier that is 4.5 kcal/mol lower than any other studied insertion pathway. In the real systems the 2,1-insertion of acrylate is preferred by 0.5 kcal/mol. The 2,1-insertion barrier calculated for the real system of 12.4 kcal/mol is in very good agreement with the experimental value of 12.1 kcal/mol. The six-member chelate is the most stable insertion product with an energy that is 21 kcal/mol lower than the kinetic insertion product. The reactions of the chelate opening by ethylene that start from the lowest energy complexes have the lowest barrier for the four-member ring (23 kcal/mol) and the highest for the six-member structure (30.4 kcal/mol). The high barrier for the opening of the six-member chelate suggests the possibility of a two-step chelate-opening mechanism. The internal barriers for the chelate-opening reactions starting from the higher energy complexes are lower then the one-step reaction that starts from the preferred complex and comparable to those of the ethylene insertion into the Pd-alkyl bond. While the chelate opening by a subsequent acrylate insertion seems to be facile for the generic catalyst, steric effects in the real catalyst are likely to decrease the acrylate pi-complexation energies and increase the insertion barriers to the extent where such a reaction becomes unfeasible.

Evidence for a serotonin transporter deficit in experimental acute liver failure

It has been suggested that alterations of serotonin transport may be implicated in the pathogenesis of the neuropsychiatric symptoms encountered in acute liver failure. In order to address this issue, microdialysate concentrations of serotonin, its precursor L-tryptophan and metabolite 5-hydroxyindoleacetic acid (5-HIAA) as well as brain regional distribution of serotonin transporter ([3H]-citalopram) sites were measured in rats with acute liver failure resulting from hepatic devascularization. A significant loss of [3H]-citalopram sites was observed in dorsal Raphe nucleus, in frontal and frontoparietal cortices as well as in substantia nigra of rats with severe encephalopathy resulting from acute liver failure. In frontal cortex, this loss of transporter binding sites was accompanied by significant increases of L-tryptophan, serotonin and 5-HIAA concentrations in extracellular fluid. Pharmacological manipulation of the brain serotonin system could afford a novel therapeutic approach to the prevention of the neuropsychiatric symptoms characteristic of acute liver failure in humans.

Loss of noradrenaline transporter sites in frontal cortex of rats with acute (ischemic) liver failure

There is increasing evidence that central noradrenaline (NA) transport mechanisms are implicated in the central nervous system complications of acute liver failure. In order to assess this possibility, binding sites for the high affinity NA transporter ligand [3H]-nisoxetine were measured by quantitative receptor autoradiography in the brains of rats with acute liver failure resulting from hepatic devascularization and in appropriate controls. In vivo microdialysis was used to measure extracellular brain concentrations of NA. Severe encephalopathy resulted in a significant loss of [3H]-nisoxetine sites in frontal cortex and a concomitant increase in extracellular brain concentrations of NA in rats with acute liver failure. A loss of transporter sites was also observed in thalamus of rats with acute liver failure. This loss of NA transporter sites could result from depletion of central NA stores due to a reserpine-like effect of ammonia which is known to accumulate to millimolar concentrations in brain in ischemic liver failure. Impaired NA transport and the consequent increase in synaptic concentrations and increased stimulation of neuronal and astrocytic noradrenergic receptors could be implicated in the pathogenesis of the encephalopathy and brain edema characteristic of acute liver failure.

Mild hypothermia delays the onset of coma and prevents brain edema and extracellular brain glutamate accumulation in rats with acute liver failure

Mild hypothermia is effective in the prevention of brain edema associated with cerebral ischemia and traumatic brain injury. Brain edema is also a serious complication of acute liver failure (ALF). To assess the effectiveness of hypothermia in ALF, groups of rats were subjected to hepatic devascularization (portacaval anastomosis, followed 48 hours later by hepatic artery ligation), and body temperatures were maintained at either 35 degrees C (hypothermic) or 37 degrees C (normothermic). Mild hypothermia resulted in a significant delay in the onset of severe encephalopathy and in reduction of brain water content compared with normothermic ALF rats (control [n = 8] 80.22%; ALF-37 degrees C [n = 8] 81.74%; ALF-35 degrees C [n = 8] 80.48% [P <.01 compared with ALF-37 degrees C]). This protective effect was accompanied by a significant reduction of cerebrospinal fluid (CSF) (but not plasma) ammonia concentrations (CSF ammonia: control: 0.05 mg/dL; ALF-37 degrees C: 1.01 mg/dL; ALF-35 degrees C: 0.07 mg/dL, P <.01 compared with ALF-37 degrees C). In vivo cerebral microdialysis studies revealed that mild hypothermia resulted in a significant reduction of extracellular glutamate concentrations in the brains of rats with ALF (control: 1. 06 micromol/L; ALF-37 degrees C: 2.74 micromol/L; ALF-35 degrees C: 1.49 micromol/L [P <.01 compared with ALF-37 degrees C]). These findings suggest that: 1) mild hypothermia is an effective approach to the prevention of the central nervous system consequences of experimental ALF; and that 2) the beneficial effect of hypothermia is mediated via mechanisms involving reduced blood-brain transfer of ammonia and/or reduction of extracellular brain glutamate concentrations. Mild hypothermia may be an effective approach to delay the onset of brain edema in patients with ALF awaiting liver transplantation.

Effect of portacaval anastomosis on glutamine synthetase protein and gene expression in brain, liver and skeletal muscle

The effects of chronic liver insufficiency resulting from end-to-side portacaval anastomosis (PCA) on glutamine synthetase (GS) activities, protein and gene expression were studied in brain, liver and skeletal muscle of male adult rats. Four weeks following PCA, activities of GS in cerebral cortex and cerebellum were reduced by 32% and 37% (p<0.05) respectively whereas GS activities in muscle were increased by 52% (p<0.05). GS activities in liver were decreased by up to 90% (p<0.01), a finding which undoubtedly reflects the loss of GS-rich perivenous hepatocytes following portal-systemic shunting. Immunoblotting techniques revealed no change in GS protein content of brain regions or muscle but a significant loss in liver of PCA rats. GS mRNA determined by semi-quantitative RT-PCR was also significantly decreased in the livers of PCA rats compared to sham-operated controls. These findings demonstrate that PCA results in a loss of GS gene expression in the liver and that brain does not show a compensatory induction of enzyme activity, rendering it particularly sensitive to increases in ammonia in chronic liver failure. The finding of a post-translational increase of GS in muscle following portacaval shunting suggests that, in chronic liver failure, muscle becomes the major organ responsible for the removal of excess blood-borne ammonia.

L-ornithine-L-aspartate lowers plasma and cerebrospinal fluid ammonia and prevents brain edema in rats with acute liver failure

Brain edema sufficient to cause intracranial hypertension and brain herniation remains a major cause of mortality in acute liver failure (ALF). Studies in experimental animal models of ALF suggest a role for ammonia in the pathogenesis of both encephalopathy and brain edema in this condition. As part of a series of studies to evaluate the therapeutic efficacy of ammonia-lowering agents, groups of rats with ALF caused by hepatic devascularization were treated with L-ornithine-L-aspartate (OA), an agent shown previously to be effective in reducing blood ammonia concentrations in both experimental and human chronic liver failure. Treatment of rats in ALF with infusions of OA (0.33 g/kg/h, intravenously) resulted in normalization of plasma ammonia concentrations and in a significant delay in onset of severe encephalopathy. More importantly, brain water content was significantly reduced in OA-treated rats with ALF. These protective effects of OA were accompanied by increased plasma concentrations of several amino acids including glutamate, gamma-aminobutyric acid (GABA), taurine, and alanine, as well as the branched-chain amino acids, leucine, isoleucine, and valine. Increased availability of glutamate following OA treatment provides the substrate for the major ammonia-removal mechanism (glutamine synthetase). Plasma (but not cerebrospinal fluid) glutamine concentrations were increased 2-fold (P <.02) in OA-treated rats, consistent with increased muscle glutamine synthesis. Direct measurement of glutamine synthetase activities revealed a 2-fold increase following OA treatment. These findings demonstrate a significant ammonia-lowering effect of OA together with a protective effect on the development of encephalopathy and brain edema in this model of ALF.

Manganese deposition in basal ganglia structures results from both portal-systemic shunting and liver dysfunction

BACKGROUND & AIMS

Manganese (Mn) deposition could be responsible for the T(1)-weighted magnetic resonance signal hyperintensities observed in cirrhotic patients. These experiments were designed to assess the regional specificity of the Mn increases as well as their relationship to portal-systemic shunting or hepatobiliary dysfunction.

METHODS

Mn concentrations were measured in (1) brain samples from basal ganglia structures (pallidum, putamen, caudate nucleus) and cerebral cortical structures (frontal, occipital cortex) obtained at autopsy from 12 cirrhotic patients who died in hepatic coma and from 12 matched controls; and from (2) brain samples (caudate/putamen, globus pallidus, frontal cortex) from groups (n = 8) of rats either with end-to-side portacaval anastomosis, with biliary cirrhosis, or with fulminant hepatic failure as well as from sham-operated and normal rats.

RESULTS

Mn content was significantly increased in frontal cortex (by 38%), occipital cortex (by 55%), pallidum (by 186%), putamen (by 66%), and caudate (by 54%) of cirrhotic patients compared with controls. Brain Mn content did not correlate with patient age, etiology of cirrhosis, or history of chronic hepatic encephalopathy. In cirrhotic and portacaval-shunted rats, Mn content was increased in pallidum (by 27% and 57%, respectively) and in caudate/putamen (by 57% and 67%, respectively) compared with control groups. Mn concentration in pallidum was significantly higher in portacaval-shunted rats than in cirrhotic rats. No significant changes in brain Mn concentrations were observed in rats with acute liver failure.

CONCLUSIONS

These findings suggest that brain Mn deposition results both from portal-systemic shunting and from liver dysfunction.

L-ornithine-L-aspartate in experimental portal-systemic encephalopathy: therapeutic efficacy and mechanism of action

Strategies aimed at the lowering of blood ammonia remain the treatment of choice in portal-systemic encephalopathy (PSE). L-ornithine-L-aspartate (OA) has recently been shown to be effective in the prevention of ammonia-precipitated coma in humans with PSE. These findings prompted the study of mechanisms of the protective effect of OA in portacaval-shunted rats in which reversible coma was precipitated by ammonium acetate administration (3.85 mmol/kg i.p.). OA infusions (300 mg/kg/h, i.v) offered complete protection in 12/12 animals compared to 0/12 saline-infused controls. This protective effect was accompanied by significant reductions of blood ammonia, concomitant increases of urea production and significant increases in blood and cerebrospinal fluid (CSF) glutamate and glutamine. Increased CSF concentrations of leucine and alanine also accompanied the protective effect of OA. These findings demonstrate the therapeutic efficacy of OA in the prevention of ammonia-precipitated coma in portacaval-shunted rats and suggest that this protective effect is both peripherally-mediated (increased urea and glutamine synthesis) and centrally-mediated (increased glutamine synthesis).

Evidence for altered central noradrenergic function in experimental acute liver failure in the rat

These is increasing evidence to suggest that central noradrenergic mechanisms may contribute to the central nervous system manifestations of acute liver failure. To further elucidate this possibility, extracellular brain concentrations of the monoamines, noradrenaline (NA), dopamine (DA), and serotonin, were measured by high-performance liquid chromatography with electrochemical detection in microdialysates from the extracellular compartment of frontal cortex in rats with acute (ischemic) liver failure at various times during the progression of encephalopathy and brain edema, as well as in obligate control groups of animals. In addition, binding sites for the noradrenergic receptor subtype ligands, [3H]-prazosin (alpha1 sites), [3H]-RX821002 (alpha2 sites), and [125]I-iodopindolol (beta sites), were assessed using quantitative receptor autoradiography in regions of the brains of rats at coma stage of acute liver failure and of control groups of animals. Coma stages of encephalopathy in acute liver failure were associated with selectively increased noradrenaline concentrations (P < .05) and a concomitant selective loss of alpha1 and beta1 sites in frontal cortex and thalamus. These findings add to a growing body of evidence that central noradrenergic function is modified in acute liver failure and suggest that alpha1/beta1 receptor-mediated noradrenergic mechanisms may play a role in the pathogenesis of brain edema and encephalopathy in this condition.

Selective increases of extracellular brain concentrations of aromatic and branched-chain amino acids in relation to deterioration of neurological status in acute (ischemic) liver failure

Previous reports based on studies in brain tissue from humans and experimental animals suggest that aromatic amino acids (AAAs) and branched-chain amino acids (BCAA's) accumulate in brain in acute liver failure. In order to assess these changes in relation to the severity of neurological impairment and to the degree of hyperammonemia, AAAs and BCAAs were measured in vivo by cerebral microdialysis in frontal cortex of rats at various stages during the development of hepatic encephalopathy due to acute liver failure resulting from portacaval anastomosis followed by hepatic artery ligation. Extracellular brain concentrations of AAAs and of valine and leucine were elevated 2 to 4-fold following hepatic devascularization and these increases were significantly correlated to arterial ammonia concentration (r= 0.71-0.84, p<0.05). Extracellular concentrations of tyrosine paralleled the deterioration of neurological status in acute liver failure rats. In view of their role as precursors of monoamine neurotransmitters, ammonia-induced alterations of intracellular/extracellular brain concentration ratios for AAAs could account for altered neuronal excitability and contribute to the encephalopathy characteristic of acute liver failure.

Ornithine transcarbamylase deficiency: pathogenesis of the cerebral disorder and new prospects for therapy

Ornithine Transcarbamylase (OTC) is a key urea cycle enzyme. Congenital OTC deficiencies in humans result in hyperammonemia and a spectrum of neurological symptoms including hypotonia, seizures and mental retardation. Neuropathologic evaluation reveals cerebral atrophy, ventricular enlargement and Alzheimer type II astrocytosis. Using an animal model of congenital OTC deficiency, the sparse fur (spf) mouse, recent studies have revealed significant alterations of cholinergic, serotoninergic and glutamatergic neurotransmitter systems. Possible pathophysiologic mechanisms responsible for neuronal cell loss in OTC deficiency include a deficit in cerebral energy metabolism, and glutamate excitotoxicity. Therapy continues to rely on alternative substrate administration including sodium benzoate and sodium phenylacetate. Experimental evidence suggests that acetyl-L-carnitine and glutamate (NMDA) receptor antagonists could be potentially useful therapeutic agents. Liver transplantation is effective in many patients and recent experimental studies using adenoviral vectors suggest that gene therapy may ultimately be useful in the treatment of congenital OTC deficiency.

Decreased glutamate transporter (GLT-1) expression in frontal cortex of rats with acute liver failure

It has been suggested that reduced astrocytic uptake of neuronally released glutamate contributes to the pathogenesis of hepatic encephalopathy in acute liver failure. In order to further address this issue, the recently cloned and sequenced astrocytic glutamate transporter GLT-1 was studied in brain preparations from rats with ischemic liver failure induced by portacaval anastomosis followed 24 h later by hepatic artery ligation and from appropriate sham-operated controls. GLT-1 expression was studied using reverse transcriptase-polymerase chain reaction (RT-PCR). Expression of GLT-1 transcript was significantly decreased in frontal cortex at coma stages of acute liver failure. Western blotting using a polyclonal antibody to GLT-1 revealed a concomitant decrease in expression of transporter protein in the brains of rats with acute liver failure. Reduced capacity of astrocytes to reuptake neuronally released glutamate, resulting from a GLT-1 transporter deficit and the consequently compromised neuron-astrocytic trafficking of glutamate could contribute to the pathogenesis of hepatic encephalopathy and brain edema, two major complications of acute liver failure.

Selective loss of binding sites for the glutamate receptor ligands [3H]kainate and (S)-[3H]5-fluorowillardiine in the brains of rats with acute liver failure

There is increasing evidence that alterations of glutamatergic function are implicated in the pathogenesis of central nervous system consequences of acute liver failure. The aim of the study was to assess the integrity of glutamate receptors in the brain in experimental ischemic liver failure using quantitative receptor autoradiography and the selective ligands [3H]MK801 (for N-methyl-D-aspartate [NMDA] sites), [3H]5-fluorowillardiine (for non-NMDA, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid [AMPA] subclass sites), and [3H]kainate (for non-NMDA, kainate subclass sites). At coma stages of encephalopathy, a selective loss of up to 60% of binding sites for the kainate- and AMPA-receptor ligands was observed in cerebral cortical and hippocampal structures as well as in the hypothalamus and cerebellum. The finding of a selective loss of AMPA sites at coma stages of encephalopathy in this model of acute liver failure is consistent with previous electrophysiological reports of inhibition of AMPA-mediated neuronal depolarization resulting from exposure of hippocampal neurons to millimolar concentrations of ammonia. On the other hand, the present study showed that binding sites for the NMDA-receptor ligand [3H]MK801 at coma stages of encephalopathy in acute liver failure were within normal limits in all brain structures examined. NMDA sites are uniquely neuronal, whereas kainate and AMPA sites are localized on both neurons and astrocytes. Therefore, the selective loss of non-NMDA sites in acute liver failure may also reflect astrocytic changes in this condition. Because astrocytic glutamate receptors are implicated in K+ and neurotransmitter reuptake, alterations in their density could result in altered neuronal excitability and thus be responsible for the neurological dysfunction characteristic of hepatic encephalopathy in acute liver failure.

Neuroactive amino acids and glutamate (NMDA) receptors in frontal cortex of rats with experimental acute liver failure

It has been proposed that alterations of excitatory and inhibitory amino acids play a role in the pathogenesis of hepatic encephalopathy in acute liver failure. To evaluate this possibility, in vivo cerebral microdialysis was used to sample extracellular concentrations of amino acids in the frontal cortex of unanesthetized rats at various times during the progression of encephalopathy resulting from acute liver failure. Liver failure was induced by portacaval anastomosis followed 24 hours later by hepatic artery ligation. Dialysate concentrations of amino acids were measured by high-performance liquid chromatography (HPLC) with fluorescence detection. Deterioration of neurological status was accompanied by two- to four-fold increases in extracellular glutamate, glutamine, and glycine; concentrations of gamma-aminobutyric acid (GABA) and taurine were unchanged. Densities of binding sites for the glutamate (N-methyl-D-aspartate [NMDA]) receptor ligand 3H-MK801, assessed using quantitative receptor autoradiography, however, were unchanged in the frontal cortex of rats at coma stages of ischemic liver failure. Increased extracellular glutamate concentrations were positively correlated with the severity of encephalopathy and with arterial ammonia concentrations. Such changes may result from an ammonia-induced reduction in the capacity for astrocytes to uptake glutamate. Increased extracellular glutamate in brain, together with increases in concentrations of glycine, a positive allosteric modulator of glutamate (NMDA) receptors, are consistent with increased NMDA-related glutamatergic neurotransmission in this model of acute liver failure. Increased extracellular glutamate, therefore, could contribute to the pathogenesis of hepatic encephalopathy and brain edema in acute liver failure.

Free and esterified coenzyme A in the liver and muscles of chronically hyperammonemic mice treated with sodium benzoate

Ammonia toxicity and relative sodium benzoate toxicity alters the energy metabolism, leading to a decrease of adenosine triphosphate and free coenzyme A levels. The object of the present study was to analyze the hepatic and muscular acyl-coenzyme A profiles in chronically hyperammonemic mice treated with varying doses of the sodium benzoate. An enzymatic method was used for the measurement of free coenzyme A, acetyl-coenzyme A, and medium and long chain acyl-coenzyme A. Untreated chronic hyperammonemia resulted in a decrease in acetyl-coenzyme A and an increase in the long chain acyl-coenzyme A in the liver, accompanied by an increase in total coenzyme A in the muscular tissues. Treatment with sodium benzoate at moderate doses, caused a decrease in the hepatic free and esterified coenzyme A while these were increased at higher doses. We conclude that chronic hyperammonemia is responsible for qualitative changes in the free and esterified coenzyme A profile in the liver, while causing qualitative and quantitative changes in the muscular tissue, probably due to an inhibition of mitochondrial oxidation. The sodium benzoate had a biphasic effect on the hepatic content of free and esterified coenzyme A, suggesting a degradation of coenzyme A at moderate doses. However, at a higher dose of benzoate, the possibility of glycine mobilization and/or a significant formation of acylcarnitines is proposed as an important factor in an increase of the hepatic total coenzyme A.

Tissue acylcarnitine and acyl-coenzyme A profiles in chronically hyperammonemic mice treated with sodium benzoate and supplementary L-carnitine

The aim of the present study, was to establish the hepatic profile of acyl-coenzyme A (acyl-CoA) in relation to the hepatic profile of acylcarnitines in chronically hyperammonemic spf mice (hereditary deficiency in ornithine transcarbamylase) treated with sodium benzoate alone or in combination with L-carnitine. The muscular profile of the acylcarnitines and the stability of sarcolemma were also assessed in the same mice. Following administration of sodium benzoate, we observed decreases in hepatic total and free coenzyme A and in acetyl-CoA, which was accompanied by an increase in hepatic acyl-CoA. This treatment also resulted in increased free carnitine, decreased total carnitine, and decreased short and medium chain acylcarnitines in the liver. Increases in plasma creatine kinase levels, muscular free, total, and in short and medium chain acylcarnitines were also observed in this treatment group. In mice receiving a combination of sodium benzoate and L-carnitine, increases in free and total coenzyme A, acetyl-CoA and in free, total and esterified hepatic carnitines were observed. In this treatment group, the plasma level of creatine kinase was found to be reduced, while the free muscular carnitine was increased. Our results indicate that sodium benzoate is implicated in the decrease of total hepatic coenzyme A, through either an inhibition of CoA synthesis or activation of its degradation. The distribution of hepatic coenzyme-A and of hepatic and muscular carnitine (free or esterified) is altered following administration of sodium benzoate which results in a further destabilization of the sarcolemma induced by hyperammonemia. Supplemental treatment with L-carnitine was shown to have a positive effect by increasing hepatic coenzyme A and carnitine levels and restoring the stability of the sarcolemma caused by the treatment of sodium benzoate alone.

A profile of cerebral and hepatic carnitine, ammonia, and energy metabolism in a model of organic aciduria: BALB/cByJ mouse with short-chain acyl-CoA dehydrogenase deficiency

Spontaneous animal models of inborn errors of metabolism are valuable tools for defining the pathogenesis of these disorders and also the mechanism of various therapeutic approaches. In the present study, we have employed BALB/cByJ mice with an autosomal recessive deficiency of short-chain acyl-CoA dehydrogenase (SCAD). These animals were characterized by a marked urinary excretion of ethylmalonic and methylsuccinic acids along with butyrylglycine. Using adult homozygous mice we have studied the basic cerebral and hepatic profile of carnitine, ammonia, and energy metabolism. The effects of fasting and a short-term supplement of L-carnitine have been evaluated in comparison with control BALB/cJ mice. The mutant mice had low levels of acetyl-CoA and high levels of lactate compared to control mice. Fasting aggravated this condition by further decreasing acetyl-CoA and increasing lactate levels in the mutant mice. Free carnitine levels were significantly decreased in liver with fasting. Long-chain acylcarnitines were significantly lower in the brain of mutant mice. A short-term supplementation of L-carnitine resulted in general increases of carnitine levels in liver and muscle, but they still remained lower in mutant BALB/cByJ mice as compared to control BALB/cJ mice. L-Carnitine treatment increased cerebral CoA-SH levels and both hepatic and cerebral acetyl-CoA levels in mutant mice. Hyperammonemia which has been described frequently in acyl-CoA dehydrogenase deficiencies was not observed in adult BALB/cByJ mice. This could be due to a rapid conjugation of butyryl-CoA with glycine by an increased activity of glycine N-acyltransferase.

[Carnitine levels in muscle in mice with hyperammonemia: effect of treatment with sodium benzoate]

The object of this study was to measure carnitine levels in skeletal muscles of experimental mice with acute, subacute, and chronic hyperammonemia, with or without sodium benzoate treatment. Normal Swiss-ICR mice in which acute hyperammonemia was created through intraperitoneal injection of ammonium acetate showed a significant decrease in free carnitine in the skeletal muscles. The same phenomenon was observed in spf mice with chronic congenital hyperammonemia caused by an X-linked deficiency of liver ornithine transcarbamylase. In spf mice with subacute hyperammonemia created through treatment with an arginine-deficient diet, free carnitine of muscles increased compared with basal levels seen in chronic hyperammonemia. The changes in carnitine metabolism during chronic and subacute hyperammonemia were accompanied by a significant increase of creatine kinase levels in the plasma, which are an index of damage to the sarcolemma. A decrease in free and esterified levels of carnitine in the muscles was observed among normal mice treated with sodium benzoate. A decrease in esterified carnitine was also noticed among spf mice given an acute treatment with sodium benzoate as well as among normal and spf mice given a prolonged treatment with sodium benzoate. Plasma creatine kinase levels were high in normal mice, after both acute and prolonged treatments. However, the levels in spf mice treated with sodium benzoate were not significantly different from those in untreated spf controls in which a significant increase in plasma creatine kinase was already caused by chronic hyperammonemia.(ABSTRACT TRUNCATED AT 250 WORDS)

[Hypocarnitinemia in patients affected by a primary defect of ammonia metabolism treated with sodium benzoate]

We have studied the plasma and urinary levels of free and esterified carnitine in 18 patients affected by a primary defect of ammonia metabolism, which had been managed with or without a therapy of sodium benzoate. None of these patients presented with any acute neurologic or digestive symptoms during the study. Our group of non-treated patients showed an increase in the levels of plasma esterified carnitine and an elevation of urinary concentration of free carnitine, while the levels of urinary esterified carnitine clearly approached the superior limits of normal values. The group treated with sodium benzoate showed a more profoundly disturbed plasma and urinary carnitine profile: a significantly lower plasma and urinary free carnitine, accompanied by a clearly increased esterified/free carnitine ratio. We did not find any evidence of a relationship between the plasma levels of free or esterified carnitine and the protein intake or the plasma ammonia concentration. We are proposing a hypothesis to explain the hypocarnitinemia seen in our patients being treated with benzoate, along with other modifications observed in the carnitine profile. We believe that a supplement of carnitine could be beneficial in the management of some of these patients.

Plasma and urinary levels of carnitine in different experimental models of hyperammonemia and the effect of sodium benzoate treatment

The effect of hyperammonemia on plasma and urinary levels of carnitine was studied in different groups of +/Y (normal) and spf/Y (chronically hyperammonemic) mice. Experimental models of acute and subacute hyperammonemia were prepared in +/Y and spf/Y mice by the use of ammonium acetate ip injections and arginine-free diets, respectively. In acute hyperammonemia, the plasma levels of both free and acylcarnitines increased significantly whereas acyl/free carnitine ratio was decreased, indicating a mobilization of carnitine from the storage sites. The subacute hyperammonemia model showed the same tendency in respect of plasma and urinary carnitines; however, the values in plasma were more significantly different. The effect of sodium benzoate on plasma carnitine levels, during both an acute and a prolonged treatment, consisted in a significant lowering of free carnitine and a significant increase in the acyl/free carnitine ratio, in both +/Y normal and spf/Y mouse models. The changes in the urinary profile, on benzoate treatments, were not significant. These results demonstrate the individual effects of hyperammonemia and benzoate therapy on carnitine metabolism, which may be helpful in understanding and ameliorating the therapeutic approach to hereditary hyperammonemias.