赛赓啶对 KBV200细胞多药抗性的逆转作用

研究赛赓啶对KB_V200细胞多药抗性的逆转作用及逆转机制。在KB_V200细胞,采用MTT法,测出赛赓啶对长春新碱、阿霉素和鬼臼乙叉甙耐药的逆转系数分别为5.5,2.0和1.9,而对5-氟尿嘧啶、美法仑的细胞毒性作用无明显影响,表明赛赓啶为多药抗性逆转剂。荧光分光光度法测定表明,赛赓啶可使KB_V200细胞内阿霉素蓄积量增加。流式细胞荧光测定显示赛赓啶可增加罗丹明123的蓄积并减慢其外排。免疫细胞化学及狭缝杂交表明赛赓啶不影响KB_V200细胞的P-糖蛋白染色深度和 mdr1 RNA 表达水平。以上结果提示赛赓啶的多药抗性逆转机制是抑制P-糖蛋白泵的功能。     

P-glycoprotein expression in soft-tissue sarcomas

Multidrug resistance (MDR) is an important problem in chemotheraphy for neoplastic disease. In humans, MDR is mainly mediated by P-glycoprotein (P-gp), a product of theMDR1 gene, which acts as a transmembrane protein pump and eliminates chemotherapeutic agents from the cells. Expression of P-gp was immunohistochemically studied by using two monoclonal antibodies, JSB-1 and C-219, on paraffin-embedded sections from 55 patients with soft-tissue sarcoma. The histological diagnosis of tumors was malignant fibrous histiocytoma in 24 cases, liposarcoma in 9, synovial sarcoma in 7, malignant neurogenic tumors in 6, leiomyosarcoma in 5, others in 4. The histological grade was determined on the basis of criteria previously proposed by us. Out of 55 cases, 34 (62%) were positive for P-gp expression. There was a significant difference in P-gp expression between high-grade (90%) and intermediate and low-grade tumors (46%) (P<0.005). Tumors expressing P-gp had a less favorable prognosis than P-gp-negative tumors in the high- and intermediate-grade tumors. The current study demonstrated that the estimation of P-gp expression could be used to select appropriate therapeutic modalities.Abbreviations MDR multidrug resistance - P-gp P-glyco-protein     

血压在前阻力血管中下降最快的原因分析

目的：解释血压在毛细血管前阻力血管中下降最快的原因。方法：利用物理模型简化复杂的心血管系统。结果：全身所有的微、小动脉段“并联”，全身所有的毛细血管段“并联”。结论：微、小动脉段的总流阻最大、使俐血压在微、小动脉中下降最快。     

Two genes for chloramphenicol resistance common to Staphylococci and streptococci

Southern blot hybridization and pneumococcal transformation were used to study the epidemiology at a molecular level of the genes for chloramphenicol resistance (cat) in streptococci and staphylococci. The cat gene of staphylococcal plasmid pC194 showed homology to the cat genes of the chromosomal elements of 5 different strains of Streptococcus pneumoniae and of Streptococcus agalactiae B109. DNA sequence homology was also detected between the cat gene of staphylococcal plasmid pC221 and the cat gene of broad host range conjugative plasmid pIP501, originally isolated from S. agalactiae. Two different cat genes appear to be present in clinical isolates of both streptococci and staphylococci.     

Viridans group streptococci: a reservoir of resistant bacteria in oral cavities

The worldwide spread of erythromycin A-resistant streptococci, including Streptococcus pneumoniae , is of concern. Many studies have demonstrated that the viridans group streptococci can be a reservoir of erythromycin A resistance. Within oral streptoccoci, an important difference in the susceptibility pattern has been noted. The purpose of this short editorial is to highlight the importance of this group of bacteria as a reservoir of resistance to erythromycin A and the possible transfer of resistance to S. pneumoniae and S. pyogenes.     

Renal vascular resistance in normal children – a color Doppler study

To investigate the relationship between age and renal vascular resistance and to establish nomative data of the systolic/diastolic ratio (S/D ratio), pulsatility index (PI), and resistant index (RI) of the renal artery in the normal pediatric population, we studied 252 normal children aged newborn to 13 years (a total of 449 kidneys) with a color Doppler unit. After the normality of the kidney was established, color flow mapping was performed to localize the segmental portion of the renal artery. Flow velocity waveforms were then obtained by pulsed Doppler, and S/D ratio, PI, and RI were calculated. Multiple regression analysis confirmed the age dependence of the S/D ratio, PI, and RI of the renal artery in normal children. Renal vascular resistance continuously declines after birth and stabilizes at the age of 102 – 130 months. Normative data for S/D ratio, PI, and RI of the renal artery in normal children were established for each age group. Since renal vascular resistance decreases with age and stabilizes at 8 – 10 years, we suggest using different normal ranges for each age group when studying renal vascular resistance in pediatric patients. Received October 5, 1995; received in revised form and accepted April 24, 1996     

Hospital outbreak caused by a carbapenem-resistant strain of Acinetobacter baumannii: patient prognosis and risk-factors for colonisation and infection

Between October 2001 and August 2002, 30 hospital patients became infected or colonised by a multiresistant (including to carbapenems) epidemic strain of Acinetobacter baumannii (AbMR) in a hospital outbreak. This study analysed the risk-factors associated with acquisition of this epidemic strain and investigated the prognosis of patients infected by AbMR, with the aim of elucidating factors which lead to mortality. A case-control study of the acquisition of AbMR in patients infected or colonised in the hospital outbreak was performed. Independent risk-factors leading to death were studied by logistic regression analysis. Multivariate analysis of the risk-factors for colonisation/infection with AbMR revealed an independent association with the presence of an arterial catheter (OR, 1.13; 95% CI, 1.03-1.25) and administration of imipenem as monotherapy (OR, 11.12; 95% CI, 2.33-53.09). Multivariate analysis of the prognostic features leading to mortality revealed a significant association with hypotension or shock (OR, 24.63; 95% CI, 1.56-387.56) at the time of bacterial isolation.