Image technique optimization in MR imaging of a titanium alloy joint prosthesis

The purpose of this study was to explore systematically the effect of the imaging parameters changeable by the user in spin-echo (SE) imaging sequences to minimize image distortion when imaging joint prostheses. A titanium alloy hip joint prosthesis was studied at 1.0 T. The SE imaging parameters were bandwidth/pixel (BW/p), TE, strength of encoding gradients (matrix size), echo train length (ETL), and direction of phase and frequency encoding. The effect of ETL in rapid acquisition relaxation enhanced (RARE) sequences was also evaluated with a turbo-SE sequence using a different ETL with the same TR and an effective TE. It is concluded that an optimized image quality can be achieved in SE imaging by using a high bandwidth/pixel value (at least 130 Hz/pixel), a high resolution matrix (256–512), sequences with multiple refocusing, and a frequency-encoding axis parallel to the long axis of the prosthesis. The degree of distortion is reduced with this optimized technique.     

济南市德国小蠊对常用化学杀虫剂的敏感性测定

目的 :了解济南市德国小蠊 (BlattellaGermanica)对常用化学杀虫剂的抗药性 ,指导科学、合理使用杀虫剂。方法 :药膜接触法。结果 :野外品系德国小蠊与敏感品系比较 ,对氯氰菊酯、溴氰菊酯、残杀威、DDVP的抗性系数分别为 10 .2 2、3 .2 1、1.18、1.19。结论 :济南市德国小蠊对 4种杀虫剂的敏感性不一 ,在害虫防制时须选择使用适当的杀虫剂     

登革病毒感染蚊虫后几个器官敏感性的比较

以浓度为4×10~8TCID_(50)/ml和4×10～5TCID_(50)/ml的病毒液经口感染,4×10~8TCID_(50)/ml和4×10~2TCID_(50)/ml病毒液经胸接种白纹伊蚊(Aedes albopictus)。结果表明1、脑和神经节感染率相同,2、神经系统对病毒敏感性较涎腺高。     

长沙、上海、郑州、武汉中华按蚊对慈利、沔阳间日疟原虫易感性的交叉对比

来自不同疟疾疫区——长沙、上海、郑州、武汉四地区的中华按蚊,分别以羊膜饲血法感染湖南慈利或湖北沔阳两地区的间日疟原虫,交叉对比其易感性。七次实验共解剖饲血蚊541只。实验结果显示:以腺感染率和阳性腺指数为主要指标,四地区中华按蚊对间日疟原虫的易感性基本相似:两地区间日疟原虫对中华按蚊的感染力也大致相同。并讨论了可能影响人工感染率的几个因素。     

鼻咽癌在不同高发区人群中的发病差异

目的：探索在广东省不同鼻咽癌高发区人群中发病差异，探讨相关病因发病因素。方法：１９８６～１９９５年对广东省四会市、广州市近６万人前瞻性研究，通过对两地人群鼻咽癌检出率，ＥＢＶＶＣＡ／ＩｇＡ阳性率，阳性人群癌前病变，癌变检出率，并以Ｌｏｇｉｓｔｉｃ多元回归分析其差异。结果：发现四会地区人群与广州地区人群相比：①高鼻咽癌检出率；②ＥＢＶＶＣＡ／ＩｇＡ阳性人群高合并鼻咽粘膜癌前病变；③ＥＢＶＶＣＡ／ＩｇＡ阳性人群高鼻咽癌检出率；④鼻咽粘膜癌前病变高癌变率。结论：ＥＢＶ感染与肿瘤遗传易感性在鼻咽癌发病上是否起着协同或加强作用值得进一步研究。     

革兰阴性病原菌耐药性变化的分析

目的：了解革兰阴性病原菌耐药水平的变化趋势。方法：对我院1998～2004年从各类临床标本分离出的革兰阴性病原菌的药敏试验结果进行统计分析。结果：病原菌对亚胺培南的总体敏感率始终保持在较高水平,以下依次为头孢他啶(69%)、阿米卡星(66%)和环丙沙星(66%),但是铜绿假单胞菌和不动杆菌对常用抗生素的敏感率呈下降趋势。大肠杆菌、肺炎克雷伯菌和阴沟肠杆菌对亚胺培南的敏感率始终维持很高水平,但对其它各类药物的敏感率大多呈现明显的下降趋势,或维持在较低水平。结论：革兰阴性病原菌耐药水平有增高的趋势。亚胺培南可作为重症患者经验用药的首选药物之一,慎重使用第3代头孢菌素,并尽量避免经验用药。     

2001～2003年上海地区淋病奈瑟菌对抗生素的敏感性测定及质粒分析

目的了解上海地区2001～2003年淋病奈瑟菌(NG)对抗生素的敏感性情况及变化趋势。方法采用琼脂稀释法测定青霉素、头孢曲松、大观霉素、环丙沙星、四环素对742株NG的最小抑菌浓度(MIC)。用纸片酸度法检测β内酰胺酶菌株。用碱裂解方法抽提质粒。结果742株NG检出产青霉素酶菌(PPNG)342株(46.09%);质粒介导高度耐四环素(TRNG)166株(22.37%);耐环丙沙星718株(96.77%);耐大观霉素1株;未发现对头孢曲松耐药菌株;超过20%的菌株同时对青霉素、四环素和环丙沙星耐药;对35株菌株作了质粒分型,含耐药质粒检出率97%,分别带有5.4和7.4kb耐药性质粒。结论淋球菌对青霉素、四环素和环丙沙星3种药物分别有较高比例的耐药率。上海地区治疗淋病应首选大观霉素和头孢曲松。     

MR susceptometry: an external-phantom method for measuring bulk susceptibility from field-echo phase reconstruction maps

A novel method for estimating the susceptibility of an object by using the magnetic resonance (MR) imaging field distortions in an external-reference water bath next to the object is described. The field measurement was obtained with a phase reconstruction from a gradient-echo acquisition. A field model of an arbitrary object in a static magnetic field was discretely calculated from geometry determined from the magnitude reconstruction. Least-squares estimation yields the susceptibility of the object. Required (and proven) assumptions include validity of superposition, object homogeneity, negligible higher-order field terms, field-model accuracy, geometric-model accuracy, and correlation of gradient-echo phase to field distortion. MR susceptometry estimation of phantoms yielded susceptibility estimates that correlated well with known values (r >.9975). This MR susceptometry method is a first step toward quantitation of iron levels through MR imaging phase information in patients with iron overload.     

Die Rolle coagulasenegativer Staphylokokken in Mischinfektionen: Assoziationstestungen als in-vitro-Modell

Zusammenfassung Die Zunahme von Infektionen durch hochresistente grampositive Kokken hat in den letzten Jahren vornehmlich auf Intensivstationen zu erheblichen therapeutischen Problemen geführt. Hierbei ist eine Gruppe von Erregern in den Vordergrund getreten, die früher als harmlose Saprophyten galten: coagulasenegative Staphylokokken (CNS). In der vorliegenden Arbeit werden zunächst Daten zur Incidenz in verschiedenen Versorgungsbereichen unserer Klinik und zur Coincidenz mit anderen Erregern auf unserer Intensivstation vorgestellt. Es konnte gezeigt werden, daßS. aureus zwar der zahlenmäßig häufigste grampositive Erreger war, aber CNS sowohl aus Wundabstrichen der Intensivstation als auch aus Blutkulturen deutlich häufiger isoliert werden konnte. Ein gleichzeitiger Nachweis von CNS mitS. aureus und den neun häufigsten Enterobacteriaceae konnte in durchschnittlich 6% erbracht werden. Durch mögliche Interaktionen zwischen unterschiedlichen Erregern kann eine Veränderung der in Einzeltestung beobachteten Resistenzen auftreten. Um dies nachzuweisen, wurden sechs Erregerpaare einzeln und in Assoziation gegen Amoxicillin und Amoxicillin/Clavulansäure getestet. Unter Assoziation wurde das gemeinsame Wachstum zweier Keime unter kontrollierten Bedingungen in Boullionverdünnungsreihen oder einem Laborautomaten zur Resistenztestung (Cobas Bact) verstanden. In allen Fällen zeigte sich, daß die-Lactamasen der CNS in Assoziation die MHK der anderen Erreger deutlich erhöhte, was durch den Zusatz von Clavulansäure verhindert werden konnte. Eine Einzeltestung gibt also bei Mischinfekten mit Beteiligung von-Lactamasebildnern nur einen eingeschränkten Eindruck von der tatsächlichen Resistenzsituation.

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Role of coagulase negative staphylococci in mixed infections: associative testing as in vitro model

Summary Infections due to coagulase negative staphylococci (CNS) are of growing concern mainly in patients hospitalized in intensive care units (ICU). The ability of CNS to adhere and to grow on plastic devices and resistance to many antibiotics, including oxacillin, contributes to their pathogenicity. Using the computer assisted system of the Medical Microbiology Department, the incidences of different pathogens and the coincidence of CNS with other bacteria were evaluated in a surgical department.Staphylococcus aureus revealed to be the predominant pathogen; however, CNS showed an increasing incidence in wound specimens and blood cultures of patients on the ICU. Coincidence of CNS withS. aureus and the nine most frequent species of gram negative bacteria could be shown in 6%. To investigate the influence of-lactamases produced by CNS in mixed infections, association experiments were performed. Association means a controlled growth of two or even more bacteria in a susceptibility testing system, either a broth dilution method or an automated broth disk elution method (Cobas Bact). The association experiments showed a significant increase of amoxicillin MIC's of the pathogen associated with CNS. Addition of clavulanic acid restored activity of amoxicillin. It could be shown that in mixed infections CNS may contribute to the failure of antibiotic regimens by production of-lactamases.

     

Protection from insulin-dependent diabetes mellitus is linked to a peptide transporter gene

HLA class II association with insulin-dependent diabetes mellitus (IDDM) is well established but is still difficult to map to a particular locus. Polymorphism of the genes coding for transporter associated with antigen processing (TAP1 and TAP2), and located in the HLA class II region, was studied in 167 IDDM patients (116 adult-onset and 51 childhood-onset patients) and 98 normal controls using oligotyping after genomic amplification. A dominant protective effect was observed for theTAP2*0201 allele [relative risk (RR)=0.3, corrected probability (pc) < 0.001]. Conversely, susceptibility to IDDM was associated with apparent homozygosity for the TAP2*0101 allele (RR=3.4, pc < 0.001). Protection was independent from but additive to the protection conferred by the DRB1*02 DQB1*0602 haplotype (RR=0.06, pc<0.05), and antagonistic to the DRB1*03 DQB1*0201 and DRB1*04 DQB 1*0302 haplotypes predisposing effect (RR=1.1, not significant), arguing in favor of an absence of linkage disequilibrium between TAP2 and HLA class II genes. This was assessed by x² analysis. TAP1 allelic distribution was not different among diabetics and controls. A significant association was observed between the presence of TAP2*0101 and that of islet cell antibodies (p < 0.05). These data suggest that the TAP2 gene, which encodes protein required for delivery of antigen peptides to class I molecules in the endoplasmic reticulum, could modulate the autoimmune response leading to β cell destruction. From a practical point of view, they make the combined screening of HLA class II and TAP2 loci a highly valuable tool in IDDM prediction.