Lung Diffusion Capacity in Patients With Bilateral COVID-19 Pneumonia: A Three-Month Follow-Up Study.

OBJECTIVES: The aim of this study was to determine the short-term consequences of coronavirus disease 2019 (COVID-19) infection on pulmonary diffusion in patients with severe (but not critical) and moderately severe COVID-19 pneumonia during three months after COVID-19 infection. METHODS: A prospective study included 81 patients with an RT-PCR-test confirmed diagnosis of COVID-19 infection treated in the COVID Department of Lung Diseases of University Clinical Hospital Mostar. Inclusion criteria were ≥18-year-old patients, COVID-19 infection confirmed using real-time RT-PCR, radiologically confirmed bilateral COVID-19 pneumonia, and diffusion capacity of the lungs for carbon monoxide (DLCO) one and three months after COVID-19 infection. The pulmonary function was tested using the MasterScreen Body Jaeger (Jaeger Corporation, Omaha, USA) and MasterScreen PFT Jaeger (Jaeger Corporation, Omaha, USA) according to American Thoracic Society guidelines one and three months after COVID-19 infection. RESULTS: Forced vital capacity significantly increased three months after COVID-19 infection compared to the first-month control (p<0.0005). Also, a statistically significant increase in the FEV1 value (p<0.0005), FEV1%FVC ratio (p<0.005), DLCO/SB (p<0.0005), DLCO/VA value (p<0.0005), and total lung capacity (TLC) (p<0.0005) was observed in all patients. CONCLUSION: Our study showed that recovery of DLCO/VA and spirometry parameters was complete after three months, while DLCO/SB was below normal values even after three months. Therefore, one month after the COVID-19 infection patients had partial recovery of lung function, while a significant recovery of lung function was observed three months after the COVID-19 infection.

Personality Traits and Health Related Quality of Life in Patients with Irritable Bowel Sindrome and Inflammatory Bowel Disease.

BACKGROUND: Personality traits as alexithymia and type D personality may impair health related quality of life (HRQoL) in patients with irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). Aim of this study was to evaluate personality traits in patients with IBS and IBD and their impact on HRQoL. MATERIALS AND METHODS: The subjects (40 patients with IBS, 40 with IBD and 40 health control subjects) completed SF-36 questionnaire, TAS-20 and DS14 scale. RESULTS: Patients with IBS and IBD had higher results on TAS-20 and DS14 scale when compared with healthy controls. Also IBS patients had higher scores than IBD patients. Higher scores on TAS-20 and DS14 scales in IBS and IBD patients correlate with lower HRQoL. HRQoL was poorer in IBS and IBD patients than in healthy control subjects. CONCLUSIONS: Alexithymia and type D personality in IBS and IBD patients are associated with lower HRQoL and psychological interventions should be considered.

Rare Complication of Necrotizing Pancreatitis: Extension of Retroperitoneal Abscess into Femoral Region.

Distant abscesses are uncommon during the episode of acute pancreatitis (AP). However, these are possible sequalae of necrotizing pancreatitis and should be treated appropriately to prevent serious septic complications. We demonstrate a case of a 56-year-old male patient who presented with severe necrotizing pancreatitis and distant retroperitoneal abscess that reached femoral region and was detected on diagnostic imaging scans. Combination of surgical and supportive therapy was employed, and the patient recovered well with no permanent consequences. Our article highlights the importance of quick and accurate diagnosis and timely intervention in this rare type of pancreatitis complication.

LPS-induced inflammation desensitizes hepatocytes to Fas-induced apoptosis through Stat3 activation-The effect can be reversed by ruxolitinib.

Recent studies have established a concept of tumour necrosis factor-α (TNF-α)/Fas signalling crosstalk, highlighting TNF-α as a critical cytokine in sensitizing hepatocytes to death induced by Fas activation. However, in the exact inflammatory response, besides TNF-α, many other mediators, that might modulate apoptotic response differentially, are released. To resolve the issue, we studied the effects of lipopolysaccharide (LPS), one of the crucial inductors of inflammation in the liver, on apoptotic outcome. We show that LPS-induced inflammation diminishes the sensitivity of hepatocytes to Fas stimulus in vivo at caspase-8 level. Analysis of molecular mechanisms revealed an increased expression of various pro-inflammatory cytokines in non-parenchymal liver cells and hepatocyte-specific increase in Bcl-xL, associated with signal transducer and activator of transcription 3 (Stat3) phosphorylation. Pre-treatment with ruxolitinib, a selective Janus kinase (JAK) 1/2 inhibitor, prevented the LPS-induced Stat3 phosphorylation and restored the sensitivity of hepatocytes to Fas-mediated apoptosis. Furthermore, ruxolitinib pre-treatment diminished the LPS-induced Bcl-xL up-regulation without an inhibitory effect on LPS-induced expression of pro-inflammatory cytokines. In summary, although the reports are showing that the effects of isolated pro-inflammatory mediators, such as TNF-α or neutrophils, are pro-apoptotic, the overall effect of inflammatory milieu on hepatocytes in vivo is Stat3-dependent desensitization to Fas-mediated apoptosis.

Type of Cell Separator, Fenwal Amicus vs Fresenius Com Tec, May Influence the Corpuscular Elements Value of the Donor`s Blood.

INTRODUCTION: During the plateletpheresis procedure the number of thrombocytes in the donor's blood significantly decreases, and the levels of the hematocrit (HCT), hemoglobin (Hgb), and leukocyte (WBC) diminish as well. Influence of the cell separator is one of the factors that affects the levels of HCT, Hgb and WBC. In this study, the goal was to determine the value difference of HCT, Hgb, WBC, and platelets after the platelet pheresis process between performance on Fenwal AMICUS and on Fresenius Com Tec. DONORS AND METHODS: The criteria for participation: male in the age range of 25-45. We have formed two groups: for both groups - 180 separations were performed on 60 participants were the values of hematocrits, concentration of hemoglobin and number of leukocytes were established before and after separation using the double-needle continuous flow cell separation (DN-CFCS) on two different devices, Fenwal AMICUS device and the Fresenius Com Tec. device. To confirm the statistical differences we have used Student t-test for independent or dependent samples, as well as Mann-Whitney U test as non-parametric alternative. To compare differences between the values of four parameters (P1-P2) from two groups (using two devices - Fenwal AMICUS and Fresenius Com Tec) The possibility of errors were accepted for α<0.05, and the difference between groups as statistical relevant were accepted for p<0.05. RESULTS: Statistically significant lower values were noted for all researched parameters after separation on both devices. The statistically significant average values for Hct, Hgb and WBC obtained between two devices, were less than 0.05 (p=0.05). For the platelets (Plt) there was no statistical significant difference (p>0.05 - α=0.05), between average level obtained using either Fenwal AMICUS or Frazenius Com Tec. CONCLUSION: The type of cell separator had the influence on the decrease value of the observed parameters.

Prognostic value of lactates in relation to gas analysis and acid-base status in patients with pulmonary embolism.

AIM: To assess the prognostic value of lactate level for mortality in patients with pulmonary embolism (PE) and Pulmonary Embolism Severity Index (PESI) I-III and its independence of gas-analysis parameters and acid-base status. METHODS: This prospective observational study was conducted at the University Clinical Hospital Mostar from 2013 to 2017. On the first day after PE diagnosis, 1.5 mL of arterial blood was collected from 103 patients with PE. Partial pressure of oxygen in arterial blood, partial pressure of carbon dioxide in arterial blood, blood pH value, concentration of bicarbonates in arterial blood (HCO3-), base deficit, and oxygen saturation were analyzed. Lactate levels were assessed using blood samples taken from the cubital vein. Logistic regression analysis was used to assess the predictive value of gas-analysis variables, lactate level, PESI score, age, and sex for in-hospital death due to PE. RESULTS: The mortality in the group of PE patients was 19.1% (18 of 103 patients). Lactate level was an independent predictor of mortality (P=0.002, odds ratio 0.06). HCO3- was also found to be a significant predictor (P=0.022, odds ratio 2.4). Lactates were independent of other variables. Other gas-analysis parameters were not significant predictors of mortality. CONCLUSION: In PE patients at low-intermediate risk of mortality (PESI I-III), lactate level was associated with a short-term mortality, independently of other gas-analytic parameters. Oxford Centre for Evidence-based Medicine level of evidence: 2.

The Significance of Thallium-201-Chloride SPECT Myocardial Perfusion Imaging in the Management of Patients With Stable Chronic Coronary Artery Disease.

BACKGROUND: Patients with stable coronary artery disease (CAD) can be evaluated for myocardial viability by examining reverse redistribution of Thallium-201 (201TI) through cardiac scintigraphy. There is limited knowledge about association of a reverse redistribution with favorable cardiac outcomes. In this study, we hypothesized that higher left ventricular ejection fraction (LVEF), lower myocardial necrosis, fewer ischemic events, and less angina will be associated with reverse redistribution of 201TI imaging. METHODS: Adult patients with stable CAD included in this study underwent exercise-redistribution Thallium single-photon emission computed tomography (SPECT) and were followed for one year. LVEF and regional wall motion abnormalities were evaluated with echocardiography, exercise duration by bicycle testing, and myocardial ischemia and viability by Thallium SPECT. RESULTS: We studied 159 patients (87 men, 72 women, median age 60 years, range: 38-84) with well-developed collaterals. Those with reverse redistribution on SPECT (n = 61, 38.3%) had significantly better exercise tolerance (⩾85%; P < .001). Subjects with reverse redistribution had better LVEF (P < .001), wall motion parameters (P < .001), a lower degree of myocardial necrosis (P < .05), less angina during follow-up (P = .02), and fewer ischemic events whether treated with OMT or PCI (P < .001). CONCLUSIONS: Reverse redistribution of 201Tl on scintigraphic images is a predictor of myocardial viability. Evidence from our study suggests that optimally treated chronic CAD patients with reverse redistribution may have lower likelihood of future adverse cardiovascular events and better prognosis.

Influence of the Type of Plateletpheresis on the Value of Corpuscular Elements in the Blood Donors.

INTRODUCTION: During the plateletpheresis procedure the number of trombocites in the donor's blood significantly decreases, and the levels of the other components of blood as hematocrit, hemoglobin, and leukocyte diminish as well. Influence of the type of procedure DN-CFCS and SN-ICFS it is one of the factors that affects the decrease of the levels of HCT, Hgb and WBC. In this study, our goal was to see the difference in the value of HCT, Hgb, WBC, and platelets after the plateletfphresis process between DN-CFCS and SN-IFCS on the same cell separator - Fenval AMICUS. DONORS AND METHODS: The criteria for participation: men between age of 25-45. Two groups were formed. Group I 112 separation done with the method SN-ICFS and Group II 180 separation done with the method DN-CFCS. STATISTICAL ANALYSIS: To confirm the statistical difference we used Student t-test for independent or dependent samples, as well as Mann-Whitney U test as non parametric alternative. The possibility of errors were accepted for α<0.05, and the difference between groups were accepted as statistical relevant for p<0.05. RESULTS: Statistically significant lower values were observed of all researched parameters after separation for the donors on the equipement Amicus DN, and for donors on Amicus SN. A significant higher value of HCT before procedure was found in the AM DN group, in the researches of the other variables there were no significant differences. The resultst for the comparison of variables after procedure procedure for DN and SN procedure. A significant higher value of HCT and a significant higher level of Hgb, as well as a significant lower level of WBV after procedure in the AM DN group, while for the levels of PLT there were no significant differences. CONCLUSION: On the decrease of the value of the observed parameters the type of procedure has an influence that means DN-CFCS or SN-IFCS, continuous or discontinuous flow.

Body Composition and Inflammation in Hemodialysis Patients.

The volume state of dialysis patients is important in guiding the dialysis process. Volume overload in these patients is associated with inflammation. The objectives of the present study were to assess the body composition of patients on hemodialysis; to determine the concentrations of B-type natriuretic peptide (BNP) in plasma and evaluate the association of BNP concentrations with volume overload; to determine the concentrations of C-reactive protein (CRP), albumin and superoxide dismutase (SOD) activities as indicators of inflammatory or antioxidant processes. The study included 79 maintenance hemodialysis patients. Assessment of body compartments was carried out using a body composition monitor (BCM). After BCM measurements, blood samples were taken from the patients for laboratory tests. There were 40 (50.6%) volume-overloaded patients (relative overhydration >15%). These patients had a higher prevalence of arterial hypertension (P < 0.05), significantly higher concentrations of BNP (P = 0.01), lower body mass index (P < 0.05) and lower fat tissue index (P < 0.05). There was a positive correlation between plasma BNP and CRP concentrations (ρ = 0.231; P < 0.05), and a negative correlation between (log) BNP and albumin (r = -0.021; P < 0.05), as well as (log) CRP and albumin concentrations (r = -3; P < 0.01). SOD activity was positively correlated with albumin concentrations (r = 0.254; P < 0.05). The concentrations of BNP in this study were associated with volume overload and inflammatory markers. Patients with a higher albumin concentration had higher SOD activity.

Prevalence of amebiasis in inflammatory bowel disease in University Clinical Hospital Mostar.

AIM: To explore the prevalence of amebiasis in inflammatory bowel disease (IBD), Crohn's disease and ulcerative colitis, in patients in Clinical hospital Mostar (Bosnia and Herzegovina, region of Herzegovina). METHODS: In this study, Entamoeba histolytica/dispar prevalence was investigated in fresh faeces by native microscopy and immunochromatographic rapid assay "RIDA(®)QUICK Entamoeba test", in 119 cases of new found IBD patients, 84 of ulcerative colitis and 35 of Crohn's disease and in control group who had also 119 patients who didn't have any gastrointestinal complaints. IBD diagnosis was established by standard diagnostic procedures (anamnesis, clinical manifestations, laboratory, endoscopy and biopsy). RESULTS: Entamoeba histolytica/dispar were found in 19 (16.0 %) of a total of 119 cases, 12 (14.3 %) of the 84 patients with ulcerative colitis and 7 (20.0 %) of the 35 patients with Crohn's disease. As for the 119 patients in the control group who had not any gastrointestinal complaints, 2 (1.7 %) patients were found to have E. histolytica/dispar in their faeces. Amoeba prevalence in the patient group was determined to be significantly higher in group with Crohn's disease, ulcerative colitis and IBD total than in the control group (p < 0.001). CONCLUSION: Ameba infections in patients with Crohn's disease and ulcerative colitis, have a greater prevalence compared to the normal population.

Correlation between biochemical and histopathological parameters in patients with chronic hepatitis C treated with pegylated interferon and ribavirin.

AIM: The main goal of this study was to compare the biochemical and histopathological findings in patients with sustained virological response (SVR) before and two years after the therapy with pegylated interferon α-2a and ribavirin in chronic hepatitis C. SUBJECTS AND METHODS: The study was conducted at the Department of Internal Medicine and the Clinic for Infectious Diseases of the Clinical Hospital Mostar. The study included 48 patients whose treatment for chronic hepatitis C with pegylated interferon α-2a and ribavirin was finished two years prior to the achieved SVR at the end of the treatment. The main criterion for inclusion was a negative result of HCV RNA, determined by the RealTime HCV assay. After taking a history, physical examination, laboratory tests: AST, ALT, GGT, a liver biopsy were performed with the help of the ultrasound. The assessment of necroinflamatory score was determined by histologic activity index (HAI) score, and the stage of fibrosis according to Knodell's numerical score. RESULTS: The values of AST and ALT levels were statistically significantly decreased after the successful treatment (p<0.001), as well as the value of HAI score (p=0.001) and the stage of fibrosis (p=0.010), in contrast to GGT (p=0.054). For the components of HAI score like focal necrosis (0.001) and portal inflammation (0.042) the result showed that they were significantly higher before the therapy, which was not true for the piecemeal (p=0.054) and confluated necrosis (p=0.078). The improvement of HAI score after therapy was found in 36 patients (75.0%), and 27 patients (56.2%) showed an improvement in the degree of fibrosis with the most common improvement of 1 degree (85.7%). One third of patients (31.3%) had the same result in the degree of fibrosis before and after the therapy. Before the treatment, a positive correlation was observed between ALT (p=0.039) and AST (p=0.04) with HAI, AST and the stage of fibrosis (p=0.04). In contrast, after the treatment the only correlation was observed between AST and the stage of fibrosis (p=0.042). CONCLUSION: Virological and biochemical responses in patients with SVR may not reflect the histopathological effects of the treatment and therefore these patients should be monitored for the possible development of the liver cirrhosis and hepatocellular carcinoma.

"Who" can be found in and beyond of an electrocardiographic strip.

Over the years, an electrocardiogram had become the basic tool to study the heart physiology and pathophysiology. Many authors gave a substantial contribution in understanding the electrophysiological basis for numerous electrocardiographic changes. Some of them were named after authors themselves, or others used the names of scientists who first discovered or explained the nature of a particular electrocardiographic finding. In this article, electrocardiographic phenomena and eponyms used in today's electrocardiography are described.

Multiple symmetric lipomatosis: a diagnostic dilemma.

Introduction. Multiple symmetric lipomatosis, or Madelung's disease, is a rare condition which is characterized with large symmetrical accumulation of noncapsulated fat tissue in upper arms, neck, and shoulder areas. The disease etiology is unknown, with the highest incidence in the Mediterranean region. Case Presentation. Here, we present the case of Madelung's disease with symmetric fat distribution throughout the neck and history of alcoholism. The patient was treated from several diseases associated with alcoholism and hospitalized several times, but the diagnosis of Madelung's disease was omitted. The thyroid gland disease was excluded, while enlargement of the neck adipose tissue was attributed to obesity. Conclusions. This study points out possible diagnostic mistakes when a physician is not aware of a differentiation diagnosis of symmetrically enlarged neck masses, especially in geographic regions with high incidence of this disease.

Aerobic interval training attenuates remodelling and mitochondrial dysfunction in the post-infarction failing rat heart.

AIMS: Following a large myocardial infarction (MI), remaining viable muscle often undergoes pathological remodelling and progresses towards chronic heart failure. Mitochondria may also be affected by this process and, due to their functional importance, likely contribute to the progression of the disease. Aerobic interval training (AIT) has been shown effective in diminishing pathological myocardial transformation, but the effects of AIT on mitochondrial function in hearts undergoing remodelling are not known. METHODS AND RESULTS: Adult female Sprague-Dawley rats were randomized to either 8 weeks of aerobic interval treadmill running (5 days/week), which started 4 weeks after left coronary artery ligation (MI-Trained), or a sedentary group (MI-Sedentary). Echocardiography was performed before and after the 8-week period, at which point the left ventricles (LVs) were also harvested. Twelve weeks after surgery, MI-Sedentary rats had significantly lower LV fractional shortening compared with MI-Trained rats. Complex I-dependent respiration assessed in isolated LV mitochondria was decreased by ∼37% in MI-Sedentary and 17% in MI-Trained animals (group differences P < 0.05), compared with sham-operated animals. This was paralleled with diminished ATP production and increased degree of protein oxidation in MI-Sedentary rats. The enzymatic activity of complex I was also decreased to a greater extent in MI-Sedentary than in MI-Trained animals, with no evidence of its reduced expression. When complex II substrate was used, no differences among the three groups were observed. CONCLUSION: Exercise reduces LV contractile deterioration in post-infarction heart failure and alleviates the extent of mitochondrial dysfunction, which is paralleled with preserved complex I activity.

Complex I and ATP synthase mediate membrane depolarization and matrix acidification by isoflurane in mitochondria.

Short application of the volatile anesthetic isoflurane at reperfusion after ischemia exerts strong protection of the heart against injury. Mild depolarization and acidification of the mitochondrial matrix are involved in the protective mechanisms of isoflurane, but the molecular basis for these changes is not clear. In this study, mitochondrial respiration, membrane potential, matrix pH, matrix swelling, ATP synthesis and -hydrolysis, and H(2)O(2) release were assessed in isolated mitochondria. We hypothesized that isoflurane induces mitochondrial depolarization and matrix acidification through direct action on both complex I and ATP synthase. With complex I-linked substrates, isoflurane (0.5mM) inhibited mitochondrial respiration by 28 ± 10%, and slightly, but significantly depolarized membrane potential and decreased matrix pH. With complex II- and complex IV-linked substrates, respiration was not changed, but isoflurane still decreased matrix pH and depolarized mitochondrial membrane potential. Depolarization and matrix acidification were attenuated by inhibition of ATP synthase with oligomycin, but not by inhibition of mitochondrial ATP- and Ca(2+)-sensitive K(+) channels or uncoupling proteins. Isoflurane did not induce matrix swelling and did not affect ATP synthesis and hydrolysis, but decreased H(2)O(2) release in the presence of succinate in an oligomycin- and matrix pH-sensitive manner. Isoflurane modulated H(+) flux through ATP synthase in an oligomycin-sensitive manner. Our results indicate that isoflurane-induced mitochondrial depolarization and acidification occur due to inhibition of the electron transport chain at the site of complex I and increased proton flux through ATP synthase. K(+) channels and uncoupling proteins appear not to be involved in the direct effects of isoflurane on mitochondria.

Effect of nitric oxide donors S-nitroso-N-acetyl-DL-penicillamine, spermine NONOate and propylamine propylamine NONOate on intracellular pH in cardiomyocytes.

1. Previous studies suggest that exogenous nitric oxide (NO) and NO-dependent signalling pathways modulate intracellular pH (pH(i)) in different cell types, but the role of NO in pH(i) regulation in the heart is poorly understood. Therefore, in the present study we investigated the effect of the NO donors S-nitroso-N-acetyl-DL-penicillamine, spermine NONOate and propylamine propylamine NONOate on pH(i) in rat isolated ventricular myocytes. 2. Cells were isolated from the hearts of adult Wistar rats and pH(i) was monitored using the pH-sensitive fluorescent indicator 5-(and-6)-carboxy seminaphtharhodafluor (SNARF)-1 (10 µmol/L) and a confocal microscope. To test the effect of NO donors on the Na⁺/H⁺ exchanger (NHE), basal pH(i) in Na⁺-free buffer and pH(i) recovery from intracellular acidosis after an ammonium chloride (10 mmol/L) prepulse were monitored. The role of carbonic anhydrase was tested using acetazolamide (50 µmol/L). 4,4-Diisothiocyanatostilbene-2,2'-disulphonic acid (0.5 mmol/L; DIDS) was used to inhibit the Cl⁻/OH⁻ and Cl⁻/HCO3-exchangers. Acetazolamide and DIDS were applied via the superfusion system 1 and 5 min before the NO donors. 3. All three NO donors acutely decreased pH(i) and this effect persisted until the NO donor was removed. In Na⁺-free buffer, the decrease in basal pH(i) was increased, whereas inhibition of carbonic anhydrase and Cl⁻/OH⁻ and Cl⁻/HCO3⁻ exchangers did not alter the effects of the NO donors on pH(i). After an ammonium preload, pH(i) recovery was accelerated in the presence of the NO donors. 4. In conclusion, exogenous NO decreases basal pH(i), leading to increased NHE activity. Carbonic anhydrase and chloride-dependent sarcolemmal HCO3⁻ and OH⁻ transporters are not involved in the NO-induced decrease in pH(i) in rat isolated ventricular myocytes.

Isoflurane differentially modulates mitochondrial reactive oxygen species production via forward versus reverse electron transport flow: implications for preconditioning.

BACKGROUND: Reactive oxygen species (ROS) mediate the effects of anesthetic precondition to protect against ischemia and reperfusion injury, but the mechanisms of ROS generation remain unclear. In this study, the authors investigated if mitochondria-targeted antioxidant (mitotempol) abolishes the cardioprotective effects of anesthetic preconditioning. Further, the authors investigated the mechanism by which isoflurane alters ROS generation in isolated mitochondria and submitochondrial particles. METHODS: Rats were pretreated with 0.9% saline, 3.0 mg/kg mitotempol in the absence or presence of 30 min exposure to isoflurane. Myocardial infarction was induced by left anterior descending artery occlusion for 30 min followed by reperfusion for 2 h and infarct size measurements. Mitochondrial ROS production was determined spectrofluorometrically. The effect of isoflurane on enzymatic activity of mitochondrial respiratory complexes was also determined. RESULTS: Isoflurane reduced myocardial infarct size (40 ± 9% = mean ± SD) compared with control experiments (60 ± 4%). Mitotempol abolished the cardioprotective effects of anesthetic preconditioning (60 ± 9%). Isoflurane enhanced ROS generation in submitochondrial particles with nicotinamide adenine dinucleotide (reduced form), but not with succinate, as substrate. In intact mitochondria, isoflurane enhanced ROS production in the presence of rotenone, antimycin A, or ubiquinone when pyruvate and malate were substrates, but isoflurane attenuated ROS production when succinate was substrate. Mitochondrial respiratory experiments and electron transport chain complex assays revealed that isoflurane inhibited only complex I activity. CONCLUSIONS: The results demonstrated that isoflurane produces ROS at complex I and III of the respiratory chain via the attenuation of complex I activity. The action on complex I decreases unfavorable reverse electron flow and ROS release in myocardium during reperfusion.

Cardiac-specific overexpression of GTP cyclohydrolase 1 restores ischaemic preconditioning during hyperglycaemia.

AIMS: Hyperglycaemia (HG) decreases intracellular tetrahydrobiopterin (BH(4)) concentrations, and this action may contribute to injury during myocardial ischaemia and reperfusion. We investigated whether increased BH(4) by cardiomyocyte-specific overexpression of the GTP cyclohydrolase (GTPCH) 1 gene rescues myocardial and mitochondrial protection by ischaemic preconditioning (IPC) during HG through a nitric oxide (NO)-dependent pathway. METHODS AND RESULTS: Mice underwent 30 min of myocardial ischaemia followed by 2 h of reperfusion with or without IPC elicited with four cycles of 5 min ischaemia/5 min of reperfusion in the presence or absence of HG produced by d-glucose. In C57BL/6 wild-type mice, IPC increased myocardial BH(4) and NO concentrations and decreased myocardial infarct size (30 ± 3% of risk area) compared with control (56 ± 5%) experiments. This protective effect was inhibited by HG (48 ± 3%) but not hyperosmolarity. GTPCH-1 overexpression increased myocardial BH(4) and NO concentrations and restored cardioprotection by IPC during HG (32 ± 4%). In contrast, a non-selective NO synthase inhibitor N(G)-nitro-l-arginine methyl ester attenuated the favourable effects of GTPCH-1 overexpression (52 ± 3%) during HG. Mitochondria isolated from myocardium subjected to IPC required significantly higher in vitro Ca(2+) concentrations (184 ± 14 µmol mg(-1) protein) to open the mitochondrial permeability transition pore when compared with mitochondria isolated from control experiments (142 ± 10 µmol mg(-1) protein). This beneficial effect of IPC was reversed by HG and rescued by GTPCH-1 overexpression. CONCLUSION: Increased BH(4) by cardiomyocyte-specific overexpression of GTPCH-1 preserves the ability of IPC to elicit myocardial and mitochondrial protection that is impaired by HG, and this action appears to be dependent on NO.

Biphasic effect of nitric oxide on the cardiac voltage-dependent anion channel.

Nitric oxide (NO·) effects on the cardiac mitochondrial voltage-dependent anion channel (VDAC) are unknown. The effects of exogenous NO· on VDAC purified from rat hearts were investigated in this study. When incorporated into lipid bilayers, VDAC was inhibited directly by an NO· donor, PAPA NONOate, in a concentration-dependent biphasic manner. This was prevented by an NO· scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The effect paralleled that of NO() in delaying the opening of the mitochondrial permeability transition (PT) pore. These biphasic effects on the cardiac VDAC and the mitochondrial PT pore reveal a tandem impact of NO() on the two mitochondrial entities.

The mitochondrial bioenergetic phenotype for protection from cardiac ischemia in SUR2 mutant mice.

The sulfonylurea receptor-2 (SUR2) is a subunit of ATP-sensitive potassium channels (K(ATP)) in heart. Mice with the SUR2 gene disrupted (SUR2m) are constitutively protected from ischemia-reperfusion (I/R) cardiac injury. This was surprising because K(ATP), either sarcolemmal or mitochondrial or both, are thought to be important for cardioprotection. We hypothesized that SUR2m mice have an altered mitochondrial phenotype that protects against I/R. Mitochondrial membrane potential (ΔΨ(m)), tolerance to Ca(2+) load, and reactive oxygen species (ROS) generation were studied by fluorescence-based assays, and volumetric changes in response to K(+) were measured by light scattering in isolated mitochondria. For resting SUR2m mitochondria compared with wild type, the ΔΨ(m) was less polarized (46.1 ± 0.4 vs. 51.9 ± 0.6%), tolerance to Ca(2+) loading was increased (163 ± 2 vs. 116 ± 2 µM), and ROS generation was enhanced with complex I [8.5 ± 1.2 vs. 4.9 ± 0.2 arbitrary fluorescence units (afu)/s] or complex II (351 ± 51.3 vs. 166 ± 36.2 afu/s) substrates. SUR2m mitochondria had greater swelling in K(+) medium (30.2 ± 3.1%) compared with wild type (14.5 ± 0.6%), indicating greater K(+) influx. Additionally, ΔΨ(m) decreased and swelling increased in the absence of ATP in SUR2m, but the sensitivity to ATP was less compared with wild type. When the mitochondria were subjected to hypoxia-reoxygenation, the decrease in respiration rates and respiratory control index was less in SUR2m. ΔΨ(m) maintenance in the SUR2m intact myocytes was also more tolerant to metabolic inhibition. In conclusion, the cardioprotection observed in the SUR2m mice is associated with a protected mitochondrial phenotype resulting from enhanced K(+) conductance that partially dissipated ΔΨ(m). These results have implications for possible SUR2 participation in mitochondrial K(ATP).