Shiori Kawasaki

Dissemination in Japanese hospitals of strains of Staphylococcus aureus heterogeneously resistant to vancomycin

BACKGROUND Since the discovery of the vancomycin-resistant Staphylococcus aureus (VRSA) strain Mu50 (minimum inhibitory concentration [MIC] 8 mg/L), there has been concern about the potential spread of such strains throughout Japanese hospitals. Two important questions need to be answered: (1) what is the prevalence of VRSA, and (2) by what mechanism does vancomycin resistance occur. METHODS The vancomycin susceptibilities of three methicillin-resistant S aureus (MRSA) strains (Mu50, Mu3, and H1) and the methicillin-susceptible S aureus type strain FDA209P were compared by MIC determinations and population analysis. Mu3 (MIC 3 mg/L) was isolated from the sputum of a patient with pneumonia after surgery who had failed vancomycin therapy. H1 (MIC 2 mg/L), which is a representative vancomycin-susceptible MRSA strain, was isolated from a patient with pneumonia who responded favourably to vancomycin therapy. Subclones of Mu3 with increased resistance against vancomycin were selected with serial concentrations of vancomycin and their MICs were determined. The prevalence of VRSA and Mu3-like strains in Japanese hospitals was estimated by population analysis from 1149 clinical MRSA isolates obtained from 203 hospitals throughout Japan. The genetic traits of the Mu3 and Mu50 strains were compared with clonotypes of MRSA from around the world. FINDINGS Mu3 and Mu50 had an identical pulsed-field gel electrophoresis banding pattern. When grown in a drug-free medium, Mu3 produced subpopulation of cells with varying degrees of vancomycin resistance, thus demonstrating natural heterogeneity, or variability, in susceptibility to vancomycin. In the presence of vancomycin, Mu3 produced subclones with resistance roughly proportional to the concentrations of vancomycin used. Selection of Mu3 with 8 mg/L or more of vancomycin gave rise to subclones with vancomycin resistance equal to that of Mu50 (MIC 8 mg/L) at a frequency of 1/1,000,000. During screening of Japanese MRSA strains, no strain of VRSA additional to Mu50 was found. The prevalence of MRSA isolates heterogeneously resistant to vancomycin was 20% in Juntendo University Hospital, 9.3% in the other seven university hospitals, and 1.3% in non-university hospitals or clinics. INTERPRETATION Heterogeneously resistant VRSA is a preliminary stage that allows development into VRSA upon exposure to vancomycin. Heterogeneously resistant VRSA was found in hospitals throughout Japan. This finding could explain, at least partly, the frequent therapeutic failure of MRSA infection with vancomycin in Japan.

Dilatation Mechanism of Balloon Angioplasty in Children: Assessment by Angiography and Intravascular Ultrasound

AbstractPurpose: Little information is available about the dilatation mechanism in children. This prospective study aimed to (1) evaluate the dilatation mechanism of balloon angioplasty in children with arterial stenosis, and (2) compare the morphological changes seen by intravascular ultrasound (IVUS) and angiography. Methods: Twenty consecutive patients, who had undergone a total of 23 procedures, were examined before and immediately after balloon angioplasty with a 4.3 Fr, 30 MHz rotational tip IVUS system. The lesions for IVUS study had resulted from coarctation of the aorta in six patients, pulmonary arterial stenosis in five, Blalock-Taussig shunt stenosis in three, subclavian artery stenosis in two, renal artery stenosis in two, coronary artery stenosis in one and ductus arteriosus in one. Results: Four distinctive morphological types were identified: type I with arterial stretching, type IIa with superficial tearing, type IIb with deep intimal-medial tearing, type III with flap formation, and type IV with dissection. The diameter of the narrowest site before and after balloon angioplasty increased significantly from 2.1 ± 1.4 mm to 4.6 ± 3.4 mm (p < 0.001). Eighteen of the 23 angioplasty procedures (78%) were considered to be successful, with a dilatation ratio of more than 50%. In most patients with successful dilatation, non-stretch mechanisms such as tearing, flap formation, or dissection were found. The positive percent (70%) of non-stretch mechanisms seen by IVUS was significantly higher than the positive findings (39%) by angiography (Χ2= 6.47, p < 0.02). Conclusions: Non-stretch morphology of the arterial wall may be a common mechanism of dilatation after balloon angioplasty in children with arterial stenosis. IVUS is a useful modality for evaluating the effectiveness of balloon angioplasty and the mechanism of dilatation in individual cases.

Effect of Hemoperfusion using Polymyxin B-Immobilized Fibers on Non-Shock Rat Sepsis Model

BACKGROUND Direct hemoperfusion with a polymyxin B-immobilized column (PMX-DHP) is recognized to be effective for the treatment of septic shock and is widely applied in Japan. However, it is still unknown whether the efficacy is limited to cardiovascular dysfunction. Therefore, the purpose of this study was to examine the effects of PMX-DHP on a non-hypotensive sepsis model. METHODS Wistar rats were assigned to either a PMX-DHP group, control group, or sham group (n=7 in each group). A sepsis model was made by intravenous infusion of live E. coli. (LD50). The change in systemic blood pressure was less than 20% of the initial level in this model. In the PMX-DHP group, an arteriovenous extracorporeal circuit with a PMX column was applied until 3 h after E. coli injection. The same procedure with a dummy column was applied in the control group. Plasma levels of ALT, LDH, BUN, tumor necrosis factor alpha (TNFα), interleukin (IL)-1β, IL-6, and IL-10 were measured. The mesenteric microcirculation was observed at 1 and 3 h after E. coli injection. In another series, survival was calculated up to 18 h (n=14 in each group). RESULTS Organ damage markers were lower in the PMX-DHP group. The levels of pro-inflammatory cytokines were significantly lower in the PMX-DHP group than in the control group. Microcirculation was better maintained in the PMX-DHP group. Survival was significantly better in the PMX-DHP group (93%) compared with that in the control group (57%, P=0.03). CONCLUSIONS PMX-DHP was effective in a non-hypotensive sepsis model.

Non-invasive assessment of liver fibrosis in patients after the Fontan operation

Background:  This study analyzed the change in liver fibrosis markers after the Fontan operation and investigated their clinical usefulness as an index of congestive liver fibrosis.

Left aortic arch with right descending aorta and right ligamentum arteriosum associated with d-TGA and large VSD: Surgical treatment of a rare form of vascular ring

A 1-month-old boy with respiratory distress underwent pulmonary artery banding after diagnosis of d-loop transposition of the great arteries and ventricular septal defect. Respiratory distress recurred after surgery. Angiography, esophagography, and magnetic resonance imaging showed left aortic arch, retroesophageal aorta, and right descending aorta. Surgery at 9 months of age showed a right-sided ligamentum arteriosum. Division of the ligamentum relieved the constriction of the esophagus and trachea caused by this rare form of vascular ring.

Aortic and mitral valve replacement in a patient with acute febrile neutrophilic dermatosis (Sweet's syndrome): report of a case.

Abstract A 29-year-old woman was admitted to our hospital with severe orthopnea, fever, and acute dermatosis. She had a 5-year history of episodic acute neutrophilic dermatosis and peripheral leukocytosis following a high fever, which were symptoms consistent with a diagnosis of Sweets syndrome. Echocardiography revealed remarkable dysfunction of the left ventricle due to severe aortic regurgitation, which had not been present at a previous admission when mild mitral regurgitation was detected. The aortic and mitral valves were replaced with prosthetic valves on an emergency basis. The leaflets of the aortic valve were very thin and appeared fragile. The anterior leaflet of the mitral valve showed severe prolapse due to the torn chordae and hypoplasia of the posterior strut chordae. Her postoperative course was uneventful. Microscopic examination revealed fibrosal degeneration and the infiltration of lymphocytes and macrophages into both heart valves. This may be the first case report of valvulitis and Sweets syndrome occurring simultaneously.

Formation of the venous thrombus after venous occlusion in the experimental mouse model of metabolic syndrome

INTRODUCTION The metabolic syndrome is considered to be a risk factor for the venous thromboembolism (VTE) as well as arterial thrombosis. Although obesity, hyperglycemia and dyslipidemia are considered to be important triggering factors, it is difficult to evaluate the relationship between VTE and the metabolic syndrome in a clinical study. Furthermore the mechanism of venous thrombosis initiation still remains elusive. MATERIALS AND METHODS 20 min clamp of superior mesenteric vein was applied to 7 w, 16 w-old KK-A(y) mouse and 16 w-old B6J mouse (n = 6 in each group), after de-clamp, the view of the mesenteric vein and intestinal submucosal venule were observed by the intravital microscopy. RESULTS Massive thrombi formed in the mesenteric vein in 16 w-old KK-A(y) mice, moderate thrombi formation was observed in 7 w-old KK-A(y) mice, while very few thrombi were observed in B6 J mice. The first event in submucosal venule after de-clamp was the adhesion of leukocytes to the endothelium. Subsequently, leukocytes assembled and platelets covered the leukocyte cluster. These leukocyte-platelet aggregates move from the venule to the vein and finally formed a venous thrombus. CONCLUSION Metabolic syndrome is a risk factor for venous thrombosis. Intravital microscopic examination revealed leukocyte and platelet recruitment to the venule in the early stages of venous thrombosis formation.

Coronary artery bypass grafting. Late result of actual 10-years follow-up in 376 patients.

OBJECTIVES The aim of this study was to analyze the long-term results of coronary artery bypass grafting in Japanese patients who were followed more than 10 years after surgery, and, without resorting to actuarial methods, to determine the factors that influence long-term survival. SUBJECTS AND METHODS From January 1984 through December 1986, 376 patients received coronary artery bypass grafting at the Department of Cardiothoracic Surgery of Juntendo University; it is these patients who comprise the subject of this study. Of the 376 patients, 328 were males (87.2%) and the mean patient age was 58.5 years (range: 32 to 78 years). Single vessel disease was present in 36 patients (10.8%), double vessel disease in 89 patients (26.7%), triple vessel disease in 150 patients (45.0%) and 58 patients (17.4%) with 50% of more stenosis of the left main coronary artery. The mean number of grafts used was 2.3 grafts per patient, while internal thoracic artery conduits were used in 66 patients (17.6%). RESULTS The 10-year survival rate for the entire series of patients was 81.4%. Patients receiving internal thoracic artery grafts had a 10-year survival rate of 94.0%, superior to the 78.0% rate found in patients who received only saphenous vein grafts. Other risk factors associated with reduced survival rates, besides non-use of internal thoracic artery, were: advanced age, diabetes mellitus, hypertension, presence of left main coronary artery disease, and severely impaired left ventricular function. The 10-year cardiac event free rate in the total group was 80.4%. Of 70 patients who died during the follow-up period, 19 deaths were due to cardiac causes (27.1%), 19 due to malignant neoplasm (27.1%) and 13 due to the cerebral vascular accident (18.6%). CONCLUSIONS Univariate analysis revealed that: the use of only saphenous vein grafts (P = 0.0055), advanced age (P < 0.0001), diabetes mellitus (P < 0.0001), hypertension (P = 0.0282), presence of left main coronary artery disease (P = 0.0140), and severely impaired left ventricular function (P = 0.0075) are associated with reduced survival in patients undergoing coronary artery bypass grafting in this cohort of patients.

A new technique for venous unifocalization of the bilateral superior vena cava with the Glenn procedure

The bidirectional Glenn procedure has been used as an intermediate stage for Fontan completion. In this staged operation, a bilateral, bidirectional Glenn procedure is performed in patients with a bilateral superior vena cava (SVC). With the bilateral SVC anatomy, the small aperture of the bilateral SVC reduces blood flow volume, and unbalanced flow can cause the stasis of blood, unbalanced pulmonary blood flow, and thrombosis formation. To resolve these issues, a new surgical technique, which we named the ‘‘unifocalization of bilateral SVC,’’ was tried as a part of the Glenn procedure. We hypothesized that single-vessel blood flow from the dual SVCs would distribute to both lungs in a manner similar to that of the unilateral Glenn procedure. In this study, we describe this new surgical procedure along with results and surgical limitations of this method.

Outcomes of One-Lung Fontan Operation: A Retrospective Multicenter Study in Japan

BACKGROUND The Fontan operation for patients with one available lung is an extremely challenging situation. However, few reports are available on this procedure. The purpose of this study was to describe outcomes of one-lung Fontan operation. METHODS A retrospective multicenter study was performed. Twelve of 1,142 patients whose data were recorded here underwent one-lung Fontan operation between September 1989 and October 2009. Preoperative, operative, and postoperative data were reviewed. RESULTS Median age at operation was 3.5 years (range, 1.0 to 22.8), the preoperative mean pulmonary pressure was 11.5±3.3 mm Hg (range, 7.0 to 18.0), the ventricular ejection fraction was 58%±13% (range, 39 to 76), and end-diastolic ventricular pressure was 7.5±3.5 mm Hg (range, 1.0 to 12.0). The available lung was right in 9 patients and left in 3 patients. Eleven patients underwent a two-staged Fontan completion. Extracardiac conduit total cavopulmonary connection, intraatrial extracardiac conduit total cavopulmonary connection, and atriopulmonary connection were performed in 10 patients, 1 patient, and 1 patient, respectively. The estimated actuarial survival was 83% at 1 year, 73% at 5 years, and 73% at 10 years. Impaired ventricular function was found to be a significant risk factor for mortality by univariate analysis (43.0%±9.5% versus 64.0%±9.5%, p<0.01), but not by multivariate analysis. CONCLUSIONS One-lung Fontan operation can be performed with an acceptable midterm to long-term mortality rate in patients without impaired ventricular function. Thus, absence of one lung itself is not a contraindication to the Fontan operation.