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.     

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。     

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。     

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.     

Genetic predisposition to leprosy: A major gene reveals novel pathways of immunity to Mycobacterium leprae

The elucidation of the genetic control of susceptibility to common infectious diseases is expected to provide new and more effective tools for prevention and control of some of the most pressings health needs on a global scale. A major advantage of whole genome based genetic approaches is that no a priori assumptions about mechanisms of pathogenesis need to be made in these studies. Hence, genetic studies can identify previously unrecognized pathways of disease susceptibility and tag critical pathogenic events for further biochemical, immunological or physiological analysis. We have applied this strategy to leprosy, a disease that still claims 400,000 new cases each year. We identified genetic variants in the shared promoter region of the PARK2 and PACRG genes as major risk factors of leprosy susceptibility. Both encoded proteins are part of the cellular ubiquitination system. Specifically, PARK2, the cause of early onset Parkinson's disease, is an E3 ligase that likely is involved in controlled proteolysis, the cellular anti-oxidants response and the regulation of innate immune responsiveness. In addition, numerous E3 ligases have recently been shown to be critical regulators of immunity. While the specific role of PARK2/PACRG in leprosy pathogenesis remains unknown, a number of experimentally testable scenarios can be developed to further explore the role of these proteins in anti-Mycobacterium leprae host responsiveness.     

Differential susceptibility to inhaled pollutants: effects of demographics and diseases

Inhaled pollutants and respiratory disease deserve particular attention at a conference focused on susceptibility and environmental risk. Inhaled air contains diverse biological, physical and chemical stressors which may cause upper and lower respiratory inflammation and exacerbate complex polygenic disorders such as asthma and sinusitis. This paper focuses on intrinsic susceptibility factors of demographics and diseases as well as genetic background. The National Health Information Survey shows that acute and chronic respiratory conditions are common at all ages, but their incidence and prevalence vary between age groups. Susceptibility is therefore not a fixed characteristic, but the aggregate effect of changing intrinsic factors such as age and disease. While ethnicity is often cited as a risk factor for disease prevalence or severity, recent research shows that measurable factors such as nasal ellipticity determine exposure–dose relationships, while the imperfect surrogate of ethnicity does not. Studies also show that exposure–dose relationships can be modified by recent exposures, and additional information is clearly needed in this area. We propose that evidence for the genetic contribution to pollutant susceptibility be sought in inter-individual variation in responses of homogenous, well characterized individuals to short term controlled pollutant exposure. Future improvements in risk assessment models will be based on a precise identification of factors that determine exposure–dose relationships, and a mechanistic understanding of the reasons that a demographic factor or disease appears to confer altered susceptibility.     

Emerging technologies from the Human Genome Project for understanding susceptibility and risk

The new technologies from the Human Genome Program provide exceptional opportunities for surveying and measuring human exposure, as well as determining susceptibility on an individual-by-individual basis. These new technologies will soon enable rapid screening of populations at risk, as well as the broader public, for a variety of genes known to be associated with increased risk. These include specific oncogenes, tumor suppressor genes and DNA repair enzymes. Use of these technologies also presents a number of ethical issues, both in screening and in use of the information about individuals. Overall, the use of rapid genotyping technologies will introduce a specificity and possible group identifiers that will present new challenges to the determination of risk within the EPA mandate.     

GSTM1和GSTT1基因多态性与COPD易感性的研究

目的　探讨GSTM1、GSTT1基因多态性与COPD易感性的关系。方法　应用PCR技术对 91例COPD患者和 44例非COPD人群GSTM1、GSTT1不同基因型进行检测并根据性别、年龄及吸烟史对其易感性进行分析。结果　两组之间相比较男性及 >40岁的人群其GSTM10 / 0基因型频率有显著性差异 (P <0 0 5 ) ;在吸烟指数为≥ 3 1PY时 ,COPD组的GSTM10 / 0基因型频率显著高于对照组 (P <0 0 5 ) ;根据性别、年龄组及吸烟史分析 ,在两组人群中GSTT10 / 0基因型频率均未发现有显著性差异 (P值均 >0 0 5 ) ;两组人群综合基因型频率分析显示 ,在吸烟指数≥ 3 1PY的人群中GSTM10 / 0 -GSTT10 / 0基因型频率则显著高于对照组 (P<0 0 5 )。结论　GSTM1纯合缺失基因型可能增加了长期大量吸烟人群对COPD的易感性 ,若同时伴有GSTT1的纯合性缺失可进一步增加对COPD的易感性     

常见念珠菌属的临床分布及对抗真菌药物敏感性研究

目的研究念珠菌属的临床分布及其对6种抗真菌药物的敏感性。方法对264株念珠菌属的临床分布进行分析,同时研究264株念珠菌属对两性霉素B、制霉菌素、氟康唑、咪康唑、克霉唑、酮康唑的敏感性。结果264株念珠菌属中,以白色念珠菌最常见占62.5%,其次为热带念珠菌占20.8%、光滑念珠菌占12.5%、近平滑念珠菌占1.9%、其他念珠菌占2.3%;念珠菌属感染的主要部位为肺、泌尿道、消化道;药物敏感试验显示:念珠菌属对制霉菌素、两性霉素B、氟康唑敏感性最高,对唑类药物存在不同程度的耐药。结论应加强对念珠菌属的鉴定及药物敏感性的检测,以指导临床抗感染治疗合理选择药物。