Multisystemic Inflammation Influences Prognosis in Fulminant Lymphocytic Myocarditis.

BACKGROUND: Multisystem inflammatory syndrome (MIS) is a hyperinflammatory shock associated with cardiac dysfunction and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, there are no reports on using MIS criteria, such as multisystemic inflammation (MSI) in fulminant myocarditis, without SARS-CoV-2 infection. This study investigated the differences in clinical characteristics and course between patients with fulminant lymphocytic myocarditis (FLM) plus MSI and those without MSI.Methods and Results: This multicenter retrospective cohort study included 273 patients with FLM registered in the JROAD-DPC database between April 2014 and March 2017. We evaluated the presence of MSI using criteria modified from previously reported MIS criteria and compared the characteristics and risk of mortality or heart transplantation between FLM patients with MSI and without MSI. Of the 273 patients with FLM, 107 (39%) were diagnosed with MSI. The MSI group was younger (44 vs. 57 years; P<0.0001) and had more females (50% vs. 36%; P=0.0236), a higher incidence of pericardial effusion (58% vs. 40%; P=0.0073), and a lower 90-day mortality rate (19% vs. 33%; P=0.0185) than the non-MSI group. The risk of mortality at 90 days was lower in FLM patients aged <50 years with MSI aged <50 years than in those without MSI (P=0.0463). CONCLUSIONS: These results suggest that MSI may influence the prognosis of FLM, especially in patients aged <50 years.

Effect of rifampicin administration on CYP induction in a dermatomyositis patient with vasospastic angina attributable to nilmatrelvir/ritonavir-induced blood tacrolimus elevation: A case report.

Ritonavir (RTV), which is used in combination with nilmatrelvir (NMV) to treat coronavirus disease 2019 (COVID-19), inhibits cytochrome P450 (CYP) 3A, thereby increasing blood tacrolimus (TAC) levels through a drug-drug interaction (DDI). We experienced a case in which a DDI between the two drugs led to markedly increased blood TAC levels, resulting in vasospastic angina (VSA) and acute kidney injury (AKI). Rifampicin (RFP) was administered to induce CYP3A and promote TAC metabolism. A 60-year-old man with dermatomyositis who was taking 3 mg/day TAC contracted COVID-19. The patient started oral NMV/RTV therapy, and he was admitted to the hospital after 4 days because of chest pain and AKI. On day 5, his blood TAC level increased markedly to 119.8 ng/mL. RFP 600 mg was administered once daily for 3 days, and his blood TAC level decreased to the therapeutic range of 9.6 ng/mL on day 9, leading to AKI improvement. Transient complete atrioventricular block and nonsustained ventricular tachycardia were present during chest pain. In the coronary spasm provocation test, complete occlusion was observed in the right coronary artery, leading to a diagnosis of VSA. VSA and AKI are possible side effects of high blood TAC levels caused by DDI, and attention should be paid to cardiovascular side effects such as VSA and AKI associated with increased blood levels of TAC when it is used together with NMV/RTV. When blood levels of TAC increase, oral RFP can rapidly decrease TAC blood levels and potentially reduce its toxicity.

Clinical, electrocardiographic, and echocardiographic parameters associated with the development of pacing and implantable cardioverter-defibrillator indication in patients with transthyretin amyloid cardiomyopathy.

AIMS: This study aimed to identify factors for attention leading to future pacing device implantation (PDI) and reveal the necessity of prophylactic PDI or implantable cardioverter-defibrillator (ICD) implantation in transthyretin amyloid cardiomyopathy (ATTR-CM) patients. METHODS AND RESULTS: This retrospective single-center observational study included consecutive 114 wild-type ATTR-CM (ATTRwt-CM) and 50 hereditary ATTR-CM (ATTRv-CM) patients, neither implanted with a pacing device nor fulfilling indications for PDI at diagnosis. As a study outcome, patient backgrounds were compared with and without future PDI, and the incidence of PDI in each conduction disturbance was examined. Furthermore, appropriate ICD therapies were investigated in all 19 patients with ICD implantation. PR-interval ≥220 msec, interventricular septum (IVS) thickness ≥16.9 mm, and bifascicular block were significantly associated with future PDI in ATTRwt-CM patients, and brain natriuretic peptide ≥35.7 pg/mL, IVS thickness ≥11.3 mm, and bifascicular block in ATTRv-CM patients. The incidence of subsequent PDI in patients with bifascicular block at diagnosis was significantly higher than that of normal atrioventricular (AV) conduction in both ATTRwt-CM [hazard ratio (HR): 13.70, P = 0.019] and ATTRv-CM (HR: 12.94, P = 0.002), whereas that of patients with first-degree AV block was neither (ATTRwt-CM: HR: 2.14, P = 0.511, ATTRv-CM: HR: 1.57, P = 0.701). Regarding ICD, only 2 of 16 ATTRwt-CM and 1 of 3 ATTRv-CM patients received appropriate anti-tachycardia pacing or shock therapy, under the number of intervals to detect for ventricular tachycardia of 16-32. CONCLUSIONS: According to our retrospective single-center observational study, prophylactic PDI did not require first-degree AV block in both ATTRwt-CM and ATTRv-CM patients, and prophylactic ICD implantation was also controversial in both ATTR-CM. Larger prospective, multi-center studies are necessary to confirm these results.

Pathological features of biopsied myocardium in patients clinically diagnosed with peripartum cardiomyopathy.

The etiology of peripartum cardiomyopathy (PPCM) is unknown. Therefore, we evaluated the etiology of patients clinically diagnosed with PPCM using endomyocardial biopsy. We studied five patients diagnosed with PPCM following endomyocardial biopsy (age, 28-42 years; mean age, 35 years). Biopsied samples were evaluated using microscopy, including immunostaining and electron microscopy. The pathological findings were as follows: myocardial hypertrophy, myocardial fibrosis, and cell infiltration. Two patients were diagnosed with lymphocytic myocarditis, one with eosinophilic myocarditis, one with hypertensive heart disease, and one with a combination of hypertension and myocarditis. Endomyocardial biopsy suggested that the causes of PPCM were varied and related to myocarditis and myocardial overload due to hypertension.

Right Ventricular Dyssynchrony in Patients With Chronic Thromboembolic Pulmonary Hypertension and Pulmonary Arterial Hypertension.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary arterial hypertension (PAH) are characterized by elevated pulmonary arterial pressure resulting in right heart failure. Right ventricular (RV) dyssynchrony may be associated with early-stage RV dysfunction; however, the differences in RV dyssynchrony between CTEPH and PAH and the factors contributing to RV dyssynchrony remain unclear.Methods and Results: Forty-four patients (CTEPH, 26; PAH, 18) were enrolled in this study. RV dyssynchrony was assessed by determining the standard deviation of the intervals from the peak QRS to peak systolic strain for 6 segments of the RV free and septal wall by using 2-dimensional speckle-tracking echocardiography (RV-6SD). The RV-6SD, pulmonary hemodynamics, echocardiographic findings, and patient demographics in CTEPH and PAH patients were compared and their correlations with RV-6SD were investigated. CTEPH patients were older and had significantly higher pulse pressure of the pulmonary artery (PP), tricuspid valve regurgitation pressure gradient, and RV-6SD, and lower pulmonary arterial compliance (PAC), despite showing comparable pulmonary arterial pressures. Age-adjusted multiple logistic analysis showed that RV-6SD and PAC were predictors of CTEPH rather than PAH. RV-SD6 was positively correlated with PP and RV dimension and negatively correlated with PAC. CONCLUSIONS: CTEPH patients showed more evident RV dyssynchrony than PAH patients. Low PAC and a widened PP may delay RV free wall motion and cause RV dyssynchrony.

Iron-Utilization System in Vibrio vulnificus M2799.

Vibrio vulnificus is a Gram-negative pathogenic bacterium that causes serious infections in humans and requires iron for growth. A clinical isolate, V. vulnificus M2799, secretes a catecholate siderophore, vulnibactin, that captures ferric ions from the environment. In the ferric-utilization system in V. vulnificus M2799, an isochorismate synthase (ICS) and an outer membrane receptor, VuuA, are required under low-iron conditions, but alternative proteins FatB and VuuB can function as a periplasmic-binding protein and a ferric-chelate reductase, respectively. The vulnibactin-export system is assembled from TolCV1 and several RND proteins, including VV1_1681. In heme acquisition, HupA and HvtA serve as specific outer membrane receptors and HupB is a sole periplasmic-binding protein, unlike FatB in the ferric-vulnibactin utilization system. We propose that ferric-siderophore periplasmic-binding proteins and ferric-chelate reductases are potential targets for drug discovery in infectious diseases.

Pathological findings of myocardium in a patient with cardiac conduction defect associated with an SCN5A mutation.

A 16-year-old Japanese man was admitted to our hospital because of syncope during exercise. His father and his younger brother had permanent pacemaker implantation because of sick sinus syndrome. Several examinations revealed first-degree atrioventricular block, complete right bundle branch block, sick sinus syndrome, and ventricular tachycardia with normal cardiac function. As no abnormalities were evident on coronary angiography, right ventricular endomyocardial biopsy was performed. It showed myocardial disarrangement and lipofuscin accumulation in hypertrophic myocytes. Moreover, electron microscopy showed a few degenerative myocytes, Z-band streaming, disarrangement, increased small capillaries with Weibel-Palade bodies in endothelial cells, and endothelial proliferations. Genetic analysis of the proband, his father, and his younger brother revealed a missense mutation, D1275N, in SCN5A, a gene which encodes sodium ion channel protein, are related to cardiomyopathy and arrhythmia. The proband was diagnosed with a cardiac conduction defect (CCD) and underwent permanent pacemaker implantation. These pathological findings suggest various myocardial changes presented in CCD patients with a missense mutation, D1275N, in SCN5A.

Histopathological changes of myocytes in restrictive cardiomyopathy.

Restrictive cardiomyopathy (RCM) is a rare primary myocardial disease, and its pathological features are yet to be determined. Restrictive cardiomyopathy with MHY7 mutation was diagnosed in a 65-year-old Japanese woman. Electron microscopy of a myocardial biopsy revealed electron-dense materials resulting from focal myocyte degeneration and necrosis as well as tubular structures and pseudo-inclusion bodies in some nuclei. These features may be associated with the pathogenesis of RCM.

Relationship between resting full-cycle ratio and fractional flow reserve in assessments of coronary stenosis severity.

AIM: Comparisons between the resting full-cycle ratio (RFR), a new physiological resting index, and fractional flow reserve (FFR) in terms of prognostic value are limited. We aimed to identify the prognostic value of concordance between RFR and FFR and to determine the stability of measured RFR. METHODS AND RESULTS: We measured FFR and RFR in 161 coronary arteries of 119 patients and classified the data using known cutoffs for FFR (≤0.80) and RFR (≤0.89) into groups; high FFR and high RFR (high FFR/low RFR) group, high FFR and low RFR (high FFR/low RFR) group, low FFR and high RFR (low FFR/high RFR) group, and low FFR and low RFR (low FFR/low RFR) group. The concordance rates in these groups were 42.2% (68/161), 4.4% (7/161), 14.3% (23/161), and 39.1% (63/161), respectively. The concordance between FFR and RFR was 81.4%. The prevalence of females was significantly higher, values for hemoglobin values were significantly lower, and average E/E' (an index of left ventricular (LV) diastolic function by echocardiography) was significantly higher in high FFR/low RFR group than in low FFR/high RFR group (p = .008, .050, and .028, respectively). CONCLUSIONS: The RFR and FFR values consistently agreed. Female, anemia, and LV diastolic dysfunction may be related to the difference of discordance between high FFR/low RFR and low FFR/high RFR.

A case of chronic myocarditis.

Chronic myocarditis is sometimes difficult to diagnose using several clinical diagnostic modalities. A 43-year-old Japanese man was admitted to our hospital with heart failure due to a diffusely hypokinetic left ventricle. No abnormal accumulation was seen on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography. Coronary angiography showed no abnormalities. Endomyocardial biopsy was performed on suspicion of dilated cardiomyopathy, revealing diffuse cell infiltration (more T lymphocytes associated with macrophages than B cells on immunohistochemical staining), myocyte damage, and replacement fibrosis. The pathological diagnosis of biopsy specimen was difficult to differentiate between chronic myocarditis and inflammatory dilated cardiomyopathy without immunohistochemistry. Endomyocardial biopsy offers one of the most useful methods for diagnosing chronic myocarditis.

Collapse of VBX Balloon-Expandable Endoprosthesis in Bilateral Common Iliac Arteries in a Lean, Elderly Patient with Bent Back.

An 87-year-old woman who had previously received bare nitinol self-expandable stent implantation twice into the bilateral common iliac artery (CIA) due to repeated in-stent restenosis presented with acute onset of intermittent claudication. Computed tomography (CT) showed bilateral CIA obstruction with thrombus. Because thrombectomy and ballooning did not achieve recanalization, kissing VBX balloon-expandable endoprostheses were deployed in both CIAs, which resolved the patient's symptoms. However, the symptoms recurred 9 days later, and CT revealed collapsed VBX stent grafts surrounded by blood thrombus. X-rays showed spinal compression of the VBX stent while standing, which might have caused the collapse. We report a case of the collapse of a VBX balloon-expandable endoprosthesis in the bilateral CIAs of an elderly patient with a bent back. Physicians should consider that a bent back could be the cause of VBX collapse even in the CIA when elderly persons present with this deformity.

Usefulness of relative apical longitudinal strain index to predict positive 99m Tc-labeled pyrophosphate scintigraphy findings in advanced-age patients with suspected transthyretin amyloid cardiomyopathy.

BACKGROUND: We previously reported that a high score (2 or 3 points) according to the Kumamoto criteria, a combination of high-sensitivity cardiac troponin T (hs-cTnT) ≥0.308 ng/mL, the length of QRS ≥ 120 ms in electrocardiogram, and left ventricular (LV) posterior wall thickness ≥ 13.6 mm, increases the pretest probability of 99m Tc-labeled pyrophosphate (99m Tc-PYP) scintigraphy in patients with suspected transthyretin amyloid cardiomyopathy (ATTR-CM). However, some patients with a low score (0 or 1 point) show positive findings on 99m Tc-PYP scintigraphy. Therefore, we evaluated the usefulness of additional examinations, including echocardiographic assessment of myocardial strain, to raise the pretest probability of 99m Tc-PYP scintigraphy for these patients. METHODS AND RESULTS: We examined 109 consecutive patients aged ≥70 years with low scores according to the Kumamoto criteria who underwent 99m Tc-PYP scintigraphy. Nineteen patients (17%) had positive 99m Tc-PYP scintigraphy findings. The relative apical longitudinal strain (LS) index (apical LS/ basal LS + mid LS) (RapLSI) was significantly higher in patients with positive than negative 99m Tc-PYP scintigraphy findings (1.04 ± 0.37 vs 0.70 ± 0.28, P < .01). Multivariable logistic regression analysis revealed that a high RapLSI (≥1.04) was significantly associated with 99m Tc-PYP positivity (odds ratio, 14.14; 95% confidence interval, 3.36-59.47; P < .01). The sensitivity, specificity, and accuracy of the diagnostic model using the RapLSI for identification of 99m Tc-PYP positivity were 53%, 94%, and 87%, respectively. CONCLUSIONS: A high RapLSI can raise the pretest probability of 99m Tc-PYP scintigraphy in patients with a low score according to the Kumamoto criteria. The RapLSI can assist clinicians in determining strategies for these patients.

Randomized, Open-Label, Cross-Over Comparison of the Effects of Benzbromarone and Febuxostat on Endothelial Function in Patients with Hyperuricemia.

Uric acid is generated with reactive oxygen species via xanthine oxidase (XO), and hyperuricemia, which is identified as the excess of uric acid in the blood, has been associated with vascular endothelial dysfunction. However, the effects of urate-lowering medicines on endothelial function have not been fully elucidated. Thus this study determined and compared the effects of benzbromarone (urate transporter 1 inhibitor) and febuxostat (XO inhibitor) on endothelial function.This randomized, cross-over, open-label study initially recruited 30 patients with hyperuricemia. They were divided into two groups, treated initially with benzbromarone or febuxostat for three months and then were switched for the next three months. Endothelial function was defined as reactive hyperemia indexes (RHI) determined using Endo-PAT 2000 before and at three and six months after medication using the two agents. Blood levels of asymmetric dimethylarginine (ADMA) and high-molecular-weight (HMW) adiponectin were also compared. We finally analyzed data from 24 patients whose endothelial function was assessed as described above.Our findings show that levels of uric acid significantly decreased, whereas those of HMW adiponectin and the RHI have significantly increased after treatment with benzbromarone. Meanwhile, in patients administered with febuxostat, uric acid levels tended to decrease and RHI significantly decreased. Neither of the two agents altered ADMA levels. The changes in RHI (P = 0.026) and HMW adiponectin levels (P = 0.001) were found to be significantly greater in patients treated with benzbromarone than febuxostat. Changes in the levels of HMW adiponectin and of uric acid were significantly correlated (r = -0.424, P = 0.039).Benzbromarone has increased adiponectin besides reducing uric acid levels, and thus, this might confer more benefits on endothelial function than febuxostat.

How to Safely Prevent Venous Thromboembolism in Severe Trauma Patients.

Venous thromboembolism (VTE) is a life-threatening complication after trauma. Several studies have reported VTE prophylaxis using low-molecular-weight heparin; however, there is no consensus for prophylaxis after trauma. This study aimed to assess the efficacy and safety of our new anticoagulation therapy protocol using unfractionated heparin (UFH) plus intermittent pneumatic compression (IPC) to prevent post-traumatic VTE in high-risk trauma patients.This study enrolled 70 trauma patients who were admitted to the emergency medical center of Nagasaki University Hospital and had Risk Assessment Profile (RAP) scores ≥ 5. After stopping bleeding at the trauma site, all patients received intravenous UFH (10,000 U/day) plus IPC, which was continued for 14 days or until the patients could walk. On days 7 and 14, all patients underwent lower extremity sonography for deep-vein thrombosis screening. VTE incidences between patients with the above intervention and historical controls with IPC alone were compared.No significant differences in age, sex, and the RAP score were observed between the 105 controls and intervention patients. VTE occurrence was fewer in patients with the intervention (14.3%) than in the controls (28.6%; P = 0.029). No hemorrhagic complications occurred after UFH administration. Multivariable logistic analysis revealed a significant association between the intervention and low incidence of VTE (odds ratio: 0.390; 95% confidence interval: 0.163-0.913; P = 0.030).Routine UFH administration with IPC may prevent post-traumatic VTE without adverse events.

Endoscopic Hemostasis in Porcine Gastrointestinal Tract Using CO2 Low-Temperature Plasma Jet.

BACKGROUND: Recently, atmospheric low-temperature plasma (LTP) has attracted attention as a novel medical tool that might be useful for achieving hemostasis. However, conventional plasma sources are too big for use with endoscopes, and the efficacy of LTP for achieving hemostasis in cases of gastrointestinal bleeding is difficult to investigate. In this study, to solve the problem, we developed a 3D-printed LTP jet that has a diameter of 2.8 mm and metal body for endoscopic use. The characteristics, hemostasis efficacy, and safety were investigated. MATERIALS AND METHODS: On investigating the basic characteristics of the developed plasma jet, the electron densities, gas temperatures, and reactive species were measured by emission spectroscopy and thermocouple. To evaluate the efficacy of such hemostatic treatment, porcine gastrointestinal bleeding was treated with the device. In addition, to investigate the safety of such treatment, the CO2 LTP-treated tissue was compared with tissue that was treated with clipping-based or argon plasma coagulation-based hemostasis for 5 d, and hematoxylin and eosin staining was used to evaluate tissue damage in the treated regions. RESULTS: The measurement of emission spectroscopy, power, and electron density of various gas plasmas suggested that a high-density (1014 cm-3) LTP of CO2 was generated by the LTP jet, and the gas temperature was 41.5°C at 3 mm from the outlet of the LTP jet. The CO2 LTP achieved hemostasis of oozing blood by 70 ± 20 s. In addition, the CO2 LTP resulted in earlier recovery than clipping-based or argon plasma coagulation-based hemostases, and the treated regions had no damage by the CO2 LTP treatment. CONCLUSIONS: These results indicated that the developed LTP plasma jet has the potential to be used for endoscopic hemostasis.

Effectiveness and safety of oral direct factor Xa inhibitors for the treatment of venous thromboembolism in patients with cancer and/or older age.

Venous thromboembolism (VTE) is a multifactorial disease. Cancer and older age are risk factors for both recurrent VTE and bleeding under anticoagulant therapy. Oral direct factor Xa inhibitors (Xa inhibitors) have been widely used to treat VTE. However, their effectiveness and safety in cancer and elderly patients have not been fully elucidated. A total of 187 consecutive patients who started Xa inhibitors for VTE therapy between September 2014 and September 2016 were recruited. Patients' demographics, changes in VTE amount, VTE recurrence, clinically relevant bleeding, and death until February 2017 were compared between 92 cancer and 95 non-cancer patients, and 57 elderly (≥ 75 years) and 130 non-elderly patients. Compared with non-cancer patients, cancer patients had a significantly higher incidence of deep vein thrombosis (DVT) in the proximal legs, superior vena cava, and upper extremities (p = 0.034), although the patients' demographics and incidence of pulmonary thromboembolism (PE) were similar between the two groups. There were no significant differences in VTE recurrence (p = 0.328) and clinically relevant bleeding (p = 0.078) between the two groups. Death occurred in 29 cancer patients, 23 of whom died of cancer, while there were no deaths among the non-cancer patients. Elderly patients had a lower body weight and creatinine clearance than non-elderly patients. No significant differences between the two groups were found in relation to PE (p = 0.544), DVT site (p = 0.054), recurrent VTE (p = 0.194), clinically relevant bleeding (p = 0.130) and death (p = 0.241). In comparisons among the four groups (elderly and non-elderly patients with and without cancer), recurrent VTE and clinically relevant bleeding were comparable (p = 0.493 and 0.227, respectively), while death was more frequent in cancer patients regardless of age (p < 0.001). The efficacy and safety of Xa inhibitors as VTE treatment were comparable between cancer and non-cancer patients, and in elderly and non-elderly patients. This suggests that Xa inhibitors may be promising drugs for VTE treatment, irrespective of age and comorbid cancer.

Doppler ultrasound diagnosis of transient leg malperfusion caused by dynamic obstruction in a patient with chronic aortic dissection.

Leg malperfusion caused by dynamic obstruction is a serious complication of aortic dissection. A diagnosis of the malperfusion is difficult because it is made mainly on the basis of nonspecific symptoms such as intermittent claudication and numbness on walking. In the present study, we reported on a case of a 51-year-old man with leg malperfusion in chronic aortic dissection diagnosed by Doppler ultrasound. The combination of bisferious and dampened velocity waveform changes after walking may lead us to suspect a leg malperfusion caused by dynamic obstruction.

Effects of Nicorandil Versus Nitroglycerin on Arterial Oxygenation During Two-Lung Ventilation and One-Lung Ventilation in Patients With Risk Factors for Myocardial Ischemia: A Prospective, Randomized, Double-Blind Study.

OBJECTIVES: To compare the effects of nicorandil and nitroglycerin on arterial oxygenation during two-lung ventilation (TLV) and one-lung ventilation (OLV) in patients with risk factors for myocardial ischemia. DESIGN: A prospective, randomized, double-blind study. SETTING: A tertiary care hospital. PARTICIPANTS: Fifty-six patients scheduled for elective video-assisted thoracic surgery were assigned randomly to either the nicorandil group or the nitroglycerin group. INTERVENTIONS: Patients in the nicorandil group received a bolus dose of nicorandil, 0.08 mg/kg during induction of anesthesia, followed by a continuous infusion at a rate of 0.08 mg/kg/h. Patients in the nitroglycerin group received a continuous infusion of nitroglycerin at a rate of 1 µg/kg/min from the induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Arterial blood gas analysis was performed at the following points: before induction of anesthesia; during TLV; at 5, 10, 20, and 30 minutes after the initiation of OLV. PaO2 at TLV (479.7 ± 57.1 v 408.2 ± 70.9 mmHg, p < 0.001); and at 5 minutes (344.8 ± 85.1 v 282.6 ± 85.8 mmHg, p = 0.012), 20 minutes (215.7 ± 103.0 v 158.2 ± 74.5 mmHg, p = 0.027), and 30 minutes (198.8 ± 103.5 v 147.5 ± 64.1 mmHg, p = 0.039) after OLV was significantly higher in the nicorandil group than in the nitroglycerin group. CONCLUSION: This study demonstrated that oxygenation during TLV and OLV was significantly higher in patients receiving nicorandil than in those receiving nitroglycerin.

Identification of the heme acquisition system in Vibrio vulnificus M2799.

Vibrio vulnificus, the causative agent of serious, often fatal, infections in humans, requires iron for its pathogenesis. As such, it obtains iron via both vulnibactin and heme-mediated iron-uptake systems. In this study, we identified the heme acquisition system in V. vulnificus M2799. The nucleotide sequences of the genes encoding heme receptors HupA and HvtA and the ATP-binding cassette (ABC) transport system proteins HupB, HupC, and HupD were determined, and then used in the construction of deletion mutants developed from a Δics strain, which could not synthesize vulnibactin. Growth experiments using these mutants indicated that HupA and HvtA are major and minor heme receptors, respectively. The expressions of two proteins were analyzed by the quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). Furthermore, complementation analyses confirmed that the HupBCD proteins are the only ABC transport system shared by both the HupA and HvtA receptors. This is the first genetic evidence that the HupBCD proteins are essential for heme acquisition by V. vulnificus. Further investigation showed that hupA, hvtA, and hupBCD are regulated by Fur. The qRT-PCR analysis of the heme receptor genes revealed that HupR, a LysR-family positive transcriptional activator, upregulates the expression of hupA, but not hvtA. In addition, ptrB was co-transcribed with hvtA, and PtrB had no influence on growth in low-iron CM9 medium supplemented with hemin, hemoglobin, or cytochrome C.