Comparison of Atrial Leads: Importance of Polarity and Fixation Mechanism

To compare the influence of polarity and fixation mechanism on atrial leads, we evaluated acute implantation and 12-month follow-up results in 211 patients, 138 male and 73 female, aged 63 ± 14 years, implanted with DDD (210) and AAI (1) pacemakers. Eighty patients had bipolar (B) active fixation (AF) leads (CPI-4266), 71 had unipolar (U) AF (Medtronic-6957J), 36 had B passive fixation (PF) (Medtronic-4512), and 26 had U PF (Medtronic-4511) leads. Acutely, capture thresholds were higher in the AF than the PF group (BAF: 1.0 ± 0.5 V; UAF: 0.9 ± 0.4 V; BPF: 0.6 ± 0.2 V; UPF: 0.5 ± 0.1V - P < 0.001). The BPF lead acute sensing threshold was superior to the AF leads (P wave sensing for BPF: 3.2 ± 1.5 mV; BAF: 2.2 ± 1.2 mV; UAF: 2.2 ± 1.1 mV - P < 0.003). In both AF and PF groups, lead polarity did not affect pacing and sensing thresholds. The difference in acute capture thresholds between AF and PF leads was abolished prior to discharge, and at subsequent follow-up over 12 months, no difference in chronic thresholds was observed. During the follow-up period, the chronic sensing thresholds of BAF leads were superior to the others. There was no significant difference in the complication rates of the four leads. Thus, all four leads proved satisfactory in clinical practice. No major impact of polarity and fixation mechanism was detected.     

Comparative studies on biological activity of /+/R and /-/S enantiomers of cyclophosphamide and ifosfamide. I. Antitumour effect of cyclophosphamide and ifosfamide enantiomers

The differences in antitumour effect of /+/R and /-/S enantiomers of both cyclophosphamide and ifosfamide were detected. In the case of ifosfamide in all five tested tumour models (Leukemia L1210, P388, Lewis lung carcinoma, 16/C mammary adenocarcinoma and B16 melanoma) the /-/S form exerted not only higher antitumour effects than /+/R form, but revealed higher therapeutic indices as well. The same appeared to be true for /-/S enantiomer of cyclophosphamide in three models of solid tumours. In L1210 and P-388 ascitic leukemia models /+/R and /-/S cyclophosphamide exerted the same antitumour effect.     

Is homozygous α-thalassaemia a lethal condition in the 1990s?

Two cases of homozygous α-thalassaemia who received active treatment in accordance with parental wishes are reported. One infant survived and the other, although successfully weaned off mechanical respiratory support, unexpectedly developed portal vein thrombosis and died. Homozygous a-thalassaemia, a condition previously considered to be universally fatal, and an indication for therapeutic abortion, is now potentially curable with advances in diagnostic technology and treatment. However, active management of these cases raises serious ethical questions and has major financial implications on the health-care system. Invasive prenatal and intensive postnatal interventions should remain experimental and cannot be recommended as routine clinical practice until the questions of long-term neurodevelopmental outcome, and the morbidity and mortality associated with bone-marrow transplantation have been fully addressed. As a result of advances in information technology, more and more parents of affected foetuses are likely to request active treatment.     

雷公藤三萜酸C的分离与结构鉴定

雷公藤总甙系雷公藤(Tripterygium wilfordii Hook.f)去皮根心经提取后得到的有效组分,它具有很强的抗炎免疫抑制作用。作者从雷公藤总甙中分离出5个三萜类化合物T_1,T_2,T_3,T_6,T_(28)。本文报道T_(28)化合物的分子结构,其他待另文发表。T_(28)是一个新的乌     

Growth hormone stimulates insulin-like growth factor I actions on adult articular chondrocytes

We report effects of adding insulin-like growth factor I (IGF-I) and methionyl human growth hormone (GH), alone or in combination, to adult bovine articular chondrocytes plated at high density. Purified human and synthetic IGF-I stimulated chondrocyte DNA and proteoglycan synthesis. GH had no effect on either process. However, GH added in combination with IGF-I increased proteoglycan, cell-associated proteoglycan, and keratan sulfate synthesis over levels observed with IGF-I alone. IGF-I and GH did not alter the hydrodynamic size of proteoglycans or synthesis of collagen. Our results show that GH and IGF-I act together to stimulate adult chondrocyte extracellular matrix synthesis.