Ionic mechanisms underlying region-specific remodeling of rabbit atrial action potentials caused by intermittent burst stimulation.

BACKGROUND: Pulmonary veins (PVs) and the coronary sinus (CS) play pivotal roles in triggering some episodes of atrial fibrillation. In isolated rabbit right or left atrial preparations, a 3-hour intermittent burst pacing protocol shortens action potential duration (APD) in CS and PV, but not in sinus node (SN) and left Bachmann bundle (BB) regions. OBJECTIVE: The purpose of this study was to use patch clamp techniques to study the rapidly inactivating (I(to)) and sustained (I(sus)) K(+) currents as well as Ca(2+) currents (I(Ca)) in cells dispersed from intermittent burst pacing and sham PV, BB, CS, and SN regions to determine whether changes in these currents contributed to APD shortening. METHODS: Real-time polymerase chain reaction was performed for transient outward K(+) and Ca(2+) channel subunit mRNAs to determine if intermittent burst pacing affected expression levels. RESULTS: I(to) densities were unaffected by intermittent burst pacing in PV and Bachmann bundle cells. mRNA levels of K(V)4.3, K(V)4.2, K(V)1.4, and KChIP2 subunits of I(to) in both regions were stable. In CS cells, I(to) densities in intermittent burst pacing were greater than in sham (P <.05), but there were no parallel mRNA changes. I(Ca) density of PV cells was reduced from 14.27 +/- 2.08 pA/pF (at -5 mV) in sham to 7.52 +/- 1.65 pA/pF in intermittent burst pacing PV cells (P <.05) due to a significant shift in voltage dependence of activation. These results were seen in the absence of mRNA changes in alpha(1C) and alpha(1D) Ca(2+) channel subunits. In contrast, intermittent burst pacing had no effect on Ca(2+) current densities and kinetics of CS cells, but decreased alpha(1)C and alpha(1)D mRNA levels. CONCLUSION: There is region-specific remodeling of I(to) and I(Ca) by intermittent burst pacing protocols in rabbit atrium. Increased I(to) in CS cells could account for the APD shortening observed with intermittent burst pacing, whereas an intermittent burst pacing-induced shift in voltage dependence of activation may contribute to APD shortening in PV cells.     

A case of ANCA-associated vasculitis with diffuse alveolar hemorrhage successfully treated by plasmapheresis]

A 65-year-old man was admitted due to rapidly progressing dyspnea experienced over a 3-day period. Chest radiography and computed tomography conducted upon admission showed diffuse bilateral interstitial infiltrate. Bronchoalveolar lavage fluid contained blood and siderophores, which suggested pulmonary alveolar hemorrhage. Laboratory data showed that the serum MPO-ANCA level was elevated, and so ANCA-associated pulmonary hemorrhage was diagnosed. Although aggressive immunosuppressive agents were administered, including steroids and cyclophosphamides, the patient's condition worsened. Plasmapheresis using fresh frozen plasma was performed on day 5, after which his symptoms improved dramatically. Plasmapheresis was done 6 times, and the pulmonary lesions resolved. The patient was discharged 6 months later. This case report suggests that plasmapheresis may be an effective treatment for ANCA-associated vasculitis with diffuse alveolar hemorrhage that is resistant to aggressive immunosuppressive therapy.     

Molecular epidemiologic study of tuberculosis--a study on isolates of M. tuberculosis in southern half of Osaka Prefecture

Restriction fragment length polymorphism, RFLP or DNA fingerprinting technique provides a very useful tool for the study of epidemiology of tuberculosis transmission in human. We performed RFLP analysis with the IS6110 insertion sequence of the organisms isolated from culture-positive patients who visited our Hospital during the period from January to December 2001. Our Hospital covers patients living in southern half of Osaka Prefecture including a part of Osaka City, which is the highest TB prevalence area in Japan. The number of copies of IS6110 per isolate ranged from 1 to 21. Most isolates (67%) carried 10 to 15 copies. Of 410 available isolates during the year of 2001, 131 (32%) belonged to a cluster and 279 (68%) did not. The clusters comprised one matching isolate in minimum to 13 isolates in maximum and had a total of 49 distinct RFLP patterns. The average age of the clustered cases was 52.1 years and 64% cases belonged to patients with ages younger than 60 years. Above findings suggest that many cases of tuberculosis in southern part of Osaka Prefecture result from recent transmission. It remains to be elucidated, however, how and where these recent infections occurred in these clustered cases.     

Effect of nicorandil on abnormal coronary flow reserve assessed by exercise201Tl scintigraphy in patients with angina pectoris and nearly normal coronary arteriograms

Summary The purpose of the present study is to assess the effect of nicorandil, a coronary vasodilator with a mechanism of potassium channel opening, on the abnormal myocardial²⁰¹Tl perfusion evoked by exercise. Eleven patients who had a history of typical angina, positive exercise electrocardiograms, positive²⁰¹Tl scintigraphy, nearly normal coronary arteriograms, and negative coronary vasospasm underwent exercise²⁰¹Tl scintigraphies under no medication (baseline test) and administration of nicorandil (nicorandil test).²⁰¹Tl was injected at a matched workload in both tests. Nicorandil did not alter heart rate, blood pressure, or the rate-pressure product at the end of the exercise, but it significantly improved the extent score from 0.37±0.22 to 0.20±0.15 (p<0.05) and the severity score from 33.9±32.2 to 13.5±16.4 (p<0.05), and also significantly hastened the²⁰¹Tl mean washout rate from 30.5±14.8% to 37.4±13.1% (p<0.05). Anginal symptoms disappeared in 3 of 5 cases and ST depression improved in 5 of 7 cases after nicorandil. We conclude that nicorandil augments coronary flow reserve, possibly due to a reduction of vasotone in the small coronary arteries.     

A rare case of pulmonary bronchogenic cyst associated with bronchial atresia in the same lobe

A rare case of 49-year-old woman having pulmonary bronchogenic cyst associated with bronchial atresia in the same lobe was presented. The diagnosis was confirmed by aortography and operation specimen. Three-dimensional reconstructed images of computed tomography clearly demonstrated the defference between mucoid impaction of bronchial trees in the left S9 not communicating with hilar bronchus and the cyst in the left S10 oppressing surrounding vessels.     

A case of pulmonary arteriovenous malformation treated by transcatheter embolization using coils]

The patient was a 21-year-old woman who, at 16 years old, had had no subjective symptoms. She was referred to our hospital because of abnormal shadows in the middle of the left lung that were seen on a chest radiograph during a school medical screening. In her first examination at our hospital, CT revealed tumor-like shadows with diameters of 2.0 cm in Lt-S6 and 0.5 cm in Rt-S5, together with arteries and veins. Lung ventilation and blood flow scintigraphy was used to obtain images of both kidneys and the head, and as a result, a pulmonary arteriovenous malformation (PAVM) was diagnosed. Because of a low shunt fraction of 10.8%, the patient was only kept under observation. However, at 21 years of age, she complained of dyspnea with exercise and was admitted to the hospital for further examination. Chest CT showed an increase in the diameter of the arteriovenous malformation (AVM) to 2.7 cm, and 3-D image reconstruction clearly revealed the position of the tumor in relation to the pulmonary artery and vein. The shunt fraction had increased to 18.3%. Coil embolization was therefore performed to A6b, the artery feeding the AVM (using interlocking detachable coils of 6 mm-10 cm and 8 mm-20 cm, and Trufill coils of two 7 mm-6 cm and 5 mm-4 cm). The patient had no serious postoperative complications. A decreased AVM diameter of 1.7 cm and an improved shunt fraction of 11% were observed, and she was discharged from the hospital. Since then, she has been well, without dyspnea, and her chest films show only coils and no aggravation of other AVMs. AVMs generally have no symptoms, but they can cause severe complications such as hypoxia from a right-to-left shunt, hemoptysis, hemothorax, and brain abscesses. Coil embolization should be considered more often for the treatment of AVM because it is safer, more effective and less invasive than traditional operations.     

A case of intrapulmonary teratoma presenting with expectoration of white hair and cheese-like material]

A 41-year-old man presented with expectoration of white hair and cheese-like material. The chest radiograph showed a round shadow adjacent to the right hilum. Bronchofiberscopy revealed strands of white hair and an obstruction consisting of sebaceous material in the right B3b bronchus. Right upper lobectomy was performed. Histological examination confirmed the diagnosis of intrapulmonary mature teratoma. This characteristic clinical presentation and the bronchofiberscopic findings may have been specific for the diagnosis of teratoma in this case.     

Idiopathic thrombocytopenic purpura and mononeuropathy multiplex

Peripheral neuropathy is an uncommon complication of idiopathic thrombocytopenic purpura (ITP). We report a 61-year-old man with ITP who developed acute-onset mononeuropathy multiplex. An electrophysiologic study revealed active axonal degenerative alteration, and a sural nerve biopsy showed axonal degeneration. Intraneural hemorrhage was suggested to be the most likely cause.