Ectopic nodal structures in a patient with atrial tachycardia originating from the mitral valve annulus.

We report a case, which we believe to be rare, of adenosine-sensitive atrial tachycardia (AT) originating from the mitral valve annulus. The patient, a 73-year-old woman, died of unrelated cause 4 years after radiofrequency (RF) ablation therapy. Histologically, fibrous replacement of atrial musculature by mature collagenous tissue produced by the RF current was observed at the left inferior atrioventricular junction. In serial sections that included the coronary sinus, two distinct nodal structures containing small, pale myocytes within the fibrous tissue matrix were identified around the region of the ablation lesion. Our case appears to be a unique representation of tissue that was associated with the occurrence and maintenance of AT.     

Usefulness of echocardiographic tissue synchronization imaging to predict acute response to cardiac resynchronization therapy

Echocardiographic tissue synchronization imaging (TSI) consists of color-coding time-to-peak tissue Doppler velocities. This study of 29 patients who underwent cardiac resynchronization therapy (CRT) demonstrated that differences in baseline time-to-speak velocities of opposing ventricular walls by TSI were greater in 15 patients, with an acute hemodynamic improvement. A >/=65 ms delay from the anterior septum to the posterior wall using the apical long-axis view had 87% sensitivity and 100% specificity for predicting an acute response. Although a subgroup without acute improvement had later decreases in end-systolic volume, suggesting that acute response underestimates long-term effects, TSI has potential to assist in guiding CRT.     

Asian variant of CD5+ intravascular large B-cell lymphoma with splenic infarction

A 57-year-old man was admitted with fever and epigastralgia, and presented with splenomegaly and pancytopenia. A CT scan revealed splenic infarctions. There were no lymphadenopathies, skin lesions, or neurological abnormalities. A splenectomy was performed. Bone marrow involvement with hemophagocytosis was noted. The diagnosis of Asian variant of intravascular diffuse large B-cell lymphoma was based on intravascular and sinusoidal distribution of large CD5+ B cells. The patient died of the disease 11 months after onset. To our knowledge, this is the first report of AIVL that presented with splenic infarction. This distinct lymphoma should be included in the differential diagnosis of splenic infarction.     

HIV-Related Risk Behaviors Among Japanese Tourists in the Khaosan Road Area, Bangkok, Thailand

This study investigated HIV-related drug use and sexual behaviors among Japanese tourists in the Khaosan Road area in Bangkok, Thailand. A stratified sample of 150 Japanese tourists anonymously self-administered a structured questionnaire. Approximately two thirds of participants had used illicit drugs. Among drug users, 33% and 49% had used marijuana during the past 6 months in Japan and in Thailand, respectively. Study participants tended to engage in riskier sex in Japan than in Thailand. In Thailand, 9% had not always used condoms with sex workers for vaginal sex. The majority of participants had engaged in sex with sex workers under the influence of alcohol in Japan (88%) and in Thailand (71%). Those who had engaged in high-risk sexual behaviors in Japan were more likely to engage in the same behaviors in Thailand, and vice-versa. Drug abuse and HIV/AIDS prevention programs targeting young Japanese tourists should be established in Thailand.     

Predictive value of microvolt T-wave alternans for sudden cardiac death in patients with preserved cardiac function after acute myocardial infarction: results of a collaborative cohort study.

OBJECTIVES: We conducted a collaborative cohort study to evaluate the predictive power of microvolt T-wave alternans (TWA) in patients with preserved left ventricular ejection fraction (LVEF) after myocardial infarction (MI). BACKGROUND: There is little information available about the prognostic value of risk stratification markers in this population. Although these patients have a relatively good prognosis, identifying high-risk patients is important in clinical practice. METHODS: This study enrolled 1,041 post-MI patients with an LVEF > or =40% (average 55 +/- 10%). Microvolt TWA testing was performed 48 +/- 66 days after acute MI, and 10 other risk variables were also evaluated. The end points were prospectively defined as sudden cardiac death or life-threatening arrhythmic events. RESULTS: During a follow-up of 32 +/- 14 months, 38 patients (3.7%) died of nonarrhythmic causes and were not considered for analysis. Of the 1,003 evaluable patients, 18 (1.8%) reached an end point. Microvolt TWA was positive in 169 patients (17%), negative in 747 (74%), and indeterminate in 87 (9%). A positive microvolt TWA test, nonsustained ventricular tachycardia, and ventricular late potentials were predictors of events, and percutaneous coronary intervention decreased the risk rate. On multivariate analysis, a positive microvolt TWA test was the most significant predictor, with a hazard ratio of 19.7 (p < 0.0001). This marker had the highest sensitivity and negative predictive value for events. CONCLUSIONS: In patients with preserved cardiac function, the incidence of indeterminate results of microvolt TWA is low, and a positive test result is associated with arrhythmic events. Microvolt TWA could be used for risk stratification in this low-risk population.     

Adrenomedullin regenerates alveoli and vasculature in elastase-induced pulmonary emphysema in mice

RATIONALE: Adrenomedullin, a potent vasodilator peptide, regulates cell growth and survival. However, whether adrenomedullin contributes to lung regeneration remains unknown. OBJECTIVES: To investigate whether adrenomedullin influences the kinetics of bone marrow cells, and whether adrenomedullin promotes regeneration of alveoli and vasculature and thereby improves lung structure and function in elastase-induced emphysema in mice. METHODS: Adrenomedullin or vehicle was randomly administered to C57BL/6 mice for 5 days. We counted the numbers of mononuclear cells and stem cell antigen-1-positive cells in circulating blood. After intratracheal injection of elastase or saline, mice were randomized to receive continuous infusion of adrenomedullin or vehicle for 14 days. Functional and histologic analyses were performed 28 days after treatment. RESULTS: Twenty-eight days after elastase injection, destruction of the alveolar walls was observed. However, adrenomedullin infusion significantly inhibited the increase in lung volume, static lung compliance, and mean linear intercept in mice given elastase. Adrenomedullin increased the numbers of mononuclear cells and stem cell antigen-1-positive cells in circulating blood. Adrenomedullin significantly increased the number of bone marrow-derived cells incorporated into the elastase-treated lung. Some of these cells were positive for cytokeratin or von Willebrand factor. Infusion of adrenomedullin after the establishment of emphysema also had beneficial effects on lung structure and function. In vitro, addition of adrenomedullin attenuates elastase-induced cell death in alveolar epithelial cells and endothelial cells. CONCLUSIONS: Adrenomedullin improved elastase-induced emphysema at least in part through mobilization of bone marrow cells and the direct protective effects on alveolar epithelial cells and endothelial cells.     

Myelodysplastic syndrome (MDS)-associated inhibitory activity on haemopoietic progenitor cells

We studied MDS-associated inhibitory activity, which inhibited colony formation in vitro of granulocyte-macrophage progenitors (CFU-GM). Macrophages obtained from MDS bone marrow mononuclear cells (BM-MNC) when pretreated with granulocyte-macrophage colony stimulating factor (GM-CSF) suppressed the growth of normal CFU-GM. These macrophages were designated as 'MDS-derived inhibitory macrophages'. Media conditioned by MDS-derived inhibitory macrophages (MDS-CM) also suppressed the growth of normal CFU-GM. In the MDS-CM, high levels of prostaglandin E2 (PGE2) and ferritin were found. However, MDS-CM did not contain detectable levels of tumour necrosis factor (TNF) or gamma-interferon (gamma-IFN). Antiserum against human placental ferritin and/or against PGE2 blocked the haemopoietic inhibitory activity to some extent. These results suggest that inhibitory macrophages may be responsible for the suppression of granulopoiesis in patients with MDS and that the suppression may be mediated by soluble factors including PGE2 and ferritin.     

A Wilms tumor cell line, HFWT, can greatly stimulate proliferation of CD56+ human natural killer cells and their novel precursors in blood mononuclear cells

OBJECTIVE: A Wilms tumor cell line, HFWT, selectively stimulates expansion of natural killer (NK) cells from human peripheral blood mononuclear cells (PBMC). In this study, we attempted to identify NK precursors in PBMC or in cord blood mononuclear cells (CBMC) that preferentially respond to feeder HFWT cells. MATERIALS AND METHODS: Human NK cells or candidate precursor cells were fractionated from PBMC or CBMC by magnetic antibody cell sorting or by flow cytometry and applied to limiting dilution analysis to determine the proportion of NK/NK precursor cells, which are able to proliferate on irradiated HFWT cells. NK and NK precursor cells were cultured in medium containing interleukin-2 (IL-2). Expansion of NK cells from both resting NK cells and NK precursor cells was examined using proliferation from single cells, expression of NK cell markers, and cytotoxic activity. RESULTS: In the limiting dilution analysis, NK cells expanded on irradiated HFWT cells not only from CD3-CD56bright and CD3-CD56dim NK cells, but also from CD16+/-CD122+ cells in the lineage-negative (Lin-, CD3-CD14-CD19-CD56-) cell fraction. The feeder HFWT cells stimulated Lin-CD122+ cell proliferation more strongly than feeder cells from the well-known human NK target cell line K562. CBMC contained significantly higher percentages of Lin-CD122+ cells than PBMC. CONCLUSION: CD3-CD14-CD19-CD56- cells expressing CD122+ (a subunit of the IL-2 receptor) preferentially respond to HFWT feeder cells and are novel precursors of CD3-CD56+ NK cells in human PBMC and CBMC.     

Chronic restraint-induced stress has little modifying effect on radiation hematopoietic toxicity in mice

Both radiation and stresses cause detrimental effects on humans. Besides possible health effects resulting directly from radiation exposure, the nuclear plant accident is a cause of social psychological stresses. A recent study showed that chronic restraint-induced stresses (CRIS) attenuated Trp53 functions and increased carcinogenesis susceptibility of Trp53-heterozygous mice to total-body X-irradiation (TBXI), having a big impact on the academic world and a sensational effect on the public, especially the residents living in radioactively contaminated areas. It is important to investigate the possible modification effects from CRIS on radiation-induced health consequences in Trp53 wild-type (Trp53wt) animals. Prior to a carcinogenesis study, effects of TBXI on the hematopoietic system under CRIS were investigated in terms of hematological abnormality in the peripheral blood and residual damage in the bone marrow erythrocytes using a mouse restraint model. Five-week-old male Trp53wt C57BL/6J mice were restrained 6 h per day for 28 consecutive days, and TBXI (4 Gy) was given on the 8th day. Results showed that CRIS alone induced a marked decrease in the red blood cell (RBC) and the white blood cell (WBC) count, while TBXI caused significantly lower counts of RBCs, WBCs and blood platelets, and a lower concentration of hemoglobin regardless of CRIS. CRIS alone did not show any significant effect on erythrocyte proliferation and on induction of micronucleated erythrocytes, whereas TBXI markedly inhibited erythrocyte proliferation and induced a significant increase in the incidences of micronucleated erythrocytes, regardless of CRIS. These findings suggest that CRIS does not have a significant impact on radiation-induced detrimental effects on the hematopoietic system in Trp53wt mice.