Is a higher sampling rate desirable in the computer processing of the pediatric electrocardiogram?

A considerably large number of ECGs of pediatric patients had small notches and slurs on QRS complexes. By sampling these ECGs at higher rates, namely 4 KHz, it was shown that the higher rate data accurately reconstructed the notches and slurs on the QRS complex which were occasionally missed or distorted when the sampling rate was 250 Hz. When using the sampling rate of 250 Hz, it was observed that the reduction of the peak-to-peak amplitude of a QRS complex exceeded 0.1 mV in nearly 30 percent of tested cases, even if the ECG did not contain unwanted noise signals. Moreover, if there is relatively more noise in children's ECGs, one should reduce noise in such data in order to prevent measurement errors in the succeeding steps of the computer program. In such circumstances, the higher sampling rate would be preferable since filtering techniques which are used to reduce noise may considerably affect the estimation of the onset, offset and amplitude of the intrinsic ECG signals if the sampling rate is low. The reduction of the price of computers and their peripheral devices may facilitate the adoption of the higher sampling rate. From these considerations it was concluded that the use of the higher sampling rate might be both practical and an effective measure to enhance the diagnostic performance of the computer ECG systems.     

Complex HeartWare left ventricular assist device infection treated with pump exchange: clinical alert for the driveline location

Journal of Artificial Organs - Infection is a major complication in patients with a left ventricular assist device (LVAD). Once a driveline exit-site infection (DLI) reaches the LVAD component,...     

64层CT与血管内超声对冠状动脉粥样斑块的定性和定量评估的对照研究

目的 对照血管内超声（intravascular ultrasound,IVUS）评价64层CT对冠状动脉粥样斑块的定性检测和定量分析。方法 2005年7月至10月连续纳入12例拟行PCI的稳定性心绞痛患者进行研究。所有患者术前接受64层CT的冠状动脉成像,术中行三支冠状动脉（左前降支、回旋支和右冠状动脉）的IVUS检查。结果 共对31支血管（左前降支12支,回旋支10支,右冠状动脉9支）,88个节段进行了64层CT和IVUS的对比检查,其中64层CT可评价节段为68个。在IVUS检测到的51个有斑块节段中,64层CT检测出47个（敏感性92％）,在17个IVUS判断为无斑块的节段中,64层CT判断16个为无斑块（特异性94％）。64层CT测量的斑块面积和IVUS测量的斑块面积相关（r=0．53,P〈0．01）,但是高估了斑块面积[（9．09±3．89）mm。比（6．80±2．81）mm^2,P〈0．01]。64层CT在43个IVUS测定的低回声成分中检出30个为低密度成分,平均CT值67．39HU。结论 冠状动脉无严重钙化时,64层CT可准确检测冠状动脉近中段粥样斑块。64层CT测量的斑块面积虽然和IVUS测量结果相关,但准确测量受限。     

Rapid induction of more malignant tumors by various genotoxic carcinogens in transgenic mice harboring a human prototype c-Ha-ras gene than in control non-transgenic mice

In this study, we investigated the carcinogenic response oftransgenic mice carrying the human prototype c-Ha-ras gene,namely Tg rasH2/CB6F1 mice, to various genotoxic carcinogensand compared it with that of control non-transgenic CB6F1 mice(non-Tg mice). The present studies were conducted as the firststep in the evaluation of the Tg rasH2/CB6F1 mouse as a modelfor the rapid carcinogenicity testing system. Short-term (     

Reverse effect of guanine on the inhibitory action of mycophenolic acid during nucleic acid synthesis

Mycophenolic acid (MPA) was demonstrated to inhibit DNA and RNA synthesis in L1210 cells strongly; however these effects were remarkably reduced by guanine. The presence of MPA in the medium decreased the guanine nucleotide contents (GMP, GDP, GTP) of the cells, but the addition of guanine reversed this effect. We have reported previously that MPA had no inhibitory effect on hypoxanthine guanine phosphoribosyltransferase (HGPRTase) activity. Together these findings suggest that the decrease of guanine nucleotides induced by MPA is restored by GMP, which is formed from guanine by HGPRTase in the cells. It is speculated that a suppressor of HGPRTase activity, such as 6-mercaptopurine, may protect the antitumor activity of MPA by preventing the conversion of guanine to GMP.     

Augmentation of TNF-induced osteoclast differentiation by inhibition of ERK and activation of p38: Similar intracellular signaling between RANKL- and TNF-induced osteoclast differentiation

Research in osteoclast differentiation has been greatly advanced since the identification of receptor activator of nuclear factor-κB ligand (RANKL) as osteoclast differentiation factor. The mechanisms of RANKL-induced osteoclast differentiation have been extensively investigated. Mitogen-activated protein kinases (MAPKs) were shown to play crucial roles in RANKL-induced osteoclast differentiation. RANKL-induced osteoclast differentiation was enhanced by inhibition of extracellular signal-regulated kinase (ERK), whereas it was suppressed by inhibition of p38 MAPK. It was reported that tumor necrosis factor (TNF), a major proinflammatory cytokine, induced osteoclast differentiation independently of RANKL. A report showed that inhibition of p38 suppressed TNF-induced osteoclast differentiation, whereas inhibition of ERK did not augment TNF-induced osteoclast differentiation. In this study we reevaluated the roles for MAPKs in TNF-induced osteoclast differentiation. In contrast with the previous report, pretreatment of mouse monocytic RAW264 cells with MAPK/ERK kinase (MEK) inhibitors including PD98059 and U-0126 augmented TNF-induced osteoclast differentiation. Furthermore, we found that U-0126 was more effective in augmentation of osteoclast differentiation than PD98059. Western blot analysis showed that U-0126 inhibited ERK phosphorylation and enhanced p38 phosphorylation, whereas PD98059 inhibited both ERK and p38 phosphorylation. SB203580, a p38 inhibitor, suppressed TNF-induced osteoclast differentiation, and inhibited p38 phosphorylation whereas it augmented ERK phosphorylation. These results demonstrate that ERK inhibition and p38 activation play crucial roles in both RANKL- and TNF-induced osteoclast differentiation.     

Clinical effect and pharmacokinetics of intermediate dose Ara-C therapy in a patient with acute non-lymphocytic leukemia with two CNS recurrences

A case of two repeated CNS recurrences of acute non-lymphocytic leukemia (M2) was treated with intermediate dose Ara-C therapy and achieved 2 complete remissions. The clinical effect and pharmacokinetics of intermediate dose Ara-C therapy in this patient were discussed. A 55-year-old male with acute non-lymphocytic leukemia (M2) achieved complete remission by combination chemotherapy of Behenoyl-ara-C, Daunorubicin, 6-Mercaptopurine and Prednisolone in July, 1985. He subsequently received consolidation and intensification therapy with periodical intrathecal injection of Methotrexate (MTX), but 13 months later he developed his first CNS recurrence which was resistant to the intrathecal administration of Ara-C and MTX. As he also relapsed systemically, Ara-C was administered in intermediate dose (1 g/m2 every 12 hrs for 5 days) and he achieved complete remission both in the CNS and systemic manifestations. Six months later he was diagnosed as having a second CNS recurrence and another systemic relapse. Intermediate dose Ara-C was administered again, and he achieved complete remission in the CNS and partial remission in systemic manifestations. Pharmacokinetic study revealed high peaks of Ara-C concentration in plasma (6.2 microM immediately after the end of the infusion) and high degree of its penetration into the CNS (5.6 microM at 3 hr after the end of the infusion) suggesting the effective and perhaps a uniform level of Ara-C is achieved throughout the CNS by this therapy. In 3 other patients without CNS involvement 0.88 +/- 0.44 microM of Ara-C, which is enough concentrations for its cytostatic effect, was detected at 3 hr after the end of infusion, suggesting the efficacy of the therapy for CNS prophylaxis. In this case the relapse occurred after repeated administration of antileukemic drugs, including Behenoyl-ara-C, an analog of Ara-C, and was resistant to the intrathecal administration of Ara-C. These findings suggest that intermediate dose Ara-C therapy was effective to overcome a resistance to antileukemic drugs, including Ara-C, and also, in some cases, more effective than intrathecal injection of antileukemic drugs for the treatment of CNS leukemia.     

Lipopolysaccharide responsiveness of malignant lymphoid cells in a patient with hairy cell leukemia.

The malignant cells in a patient with hairy cell leukemia responded most evidently to lipopolysaccharide (LPS) in in vitro culture for 3 1/2 days when the conventional tritiated thymidine uptake method was used. Since the malignant cells from patients with several other forms of leukemia and the peripheral blood mononuclear cells from healthy individuals did not show a comparable degree of responsiveness to LPS, we could exclude the possibility that this response was due to effects on contaminating normal mononuclear cells or to the nonspecific conditioning effect through LPS-affected contaminating normal monocytes. Morphological changes were observed with photo- and electronmicroscopy. It is likely that the hairy cells from the patient did respond to LPS, and whether or not this phenomenon may be confined to this type of lymphoid leukemia is not being investigated.