基于方法学评估与检测基线预测广西玉林市从业人员沙门菌带菌水平

目的基于沙门菌筛检流程的方法评价和检测基线,预测广西壮族自治区(广西)玉林市从业人员沙门菌的带菌水平。方法以沙门菌选择性增菌液(SBG)和3种选择性平板(CAS、XLD、DHL)构建沙门菌筛选和检定流程,通过测试菌株和408份从业者粪便样品实测获得统计参数,据此评估不同组合流程(SBG-CAS/XLD/DHL)筛检沙门菌的敏感性、特异性和阳性预测值;基于SBG-DHL分离沙门菌的敏感性校准和预测2014-2017年玉林市从业人员的带菌水平。结果CAS、XLD、DHL对测试菌株的敏感性和特异性分别为100.00%和96.67%、100.00%和83.33%、83.33%和50.00%;应用组合流程筛检408份从业人员粪便,共分离沙门菌22株,带菌率为5.39%;敏感性和阳性预测值分别为95.45%和89.23%(CAS)、86.36%和27.72%(XLD)、68.18%和16.15%(DHL)、100.00%和29.27%(CAS+XLD);CAS+XLD组合发现1例兼有硫化氢阴性和阳性的罗森沙门菌的无症状带菌者;校准和预测2014-2017年玉林市从业人员的平均年度带菌率为3.35%,以实测人数评估地区从业人员的带菌水平约为3350/10万。结论沙门菌检测敏感性和阳性预测值可作为检测质量和方法学的评价指标,大数据证实华南地区从业人员中沙门菌的高比例持留,公共卫生机构应加强沙门菌带菌者的防控,降低食源性病原菌的隐性扩散风险。     

Partial volume effects in dynamic contrast magnetic resonance renal studies

This is the first study of partial volume effect in quantifying renal function on dynamic contrast enhanced magnetic resonance imaging. Dynamic image data were acquired for a cohort of 10 healthy volunteers. Following respiratory motion correction, each voxel location was assigned a mixing vector representing the ‘overspilling’ contributions of each tissue due to the convolution action of the imaging system's point spread function. This was used to recover the true intensities associated with each constituent tissue. Thus, non-renal contributions from liver, spleen and other surrounding tissues could be eliminated from the observed time-intensity curves derived from a typical renal cortical region of interest. This analysis produced a change in the early slope of the renal curve, which subsequently resulted in an enhanced glomerular filtration rate estimate. This effect was consistently observed in a Rutland-Patlak analysis of the time-intensity data: the volunteer cohort produced a partial volume effect corrected mean enhancement of 36% in relative glomerular filtration rate with a mean improvement of 7% in r² fitting of the Rutland-Patlak model compared to the same analysis undertaken without partial volume effect correction. This analysis strongly supports the notion that dynamic contrast enhanced magnetic resonance imaging of kidneys is substantially affected by the partial volume effect, and that this is a significant obfuscating factor in subsequent glomerular filtration rate estimation.     

Semiquantitative Assessment of Tumor Spread through Air Spaces (STAS) in Early-Stage Lung Adenocarcinomas

IntroductionTumor spread through air spaces (STAS) has recently been reported as a form of tumor invasion having an unfavorable prognosis, but the significance of a small amount of STAS is not known. The aim of this study was to perform a semiquantitative assessment of STAS.MethodsSmall (≤2 cm) stage I lung adenocarcinomas surgically resected at our institution between 2003 and 2009 were assessed semiquantitatively in the most prominent area as no STAS, low STAS (1–4 single cells or clusters of STAS), or high STAS (≥5 single cells or clusters of STAS) by using a 20× objective and a 10× ocular lens. A statistical analysis was performed to determine the impact of clinicopathologic parameters on STAS and to clarify the relationship between STAS and patient survival.ResultsSTAS was assessed as no STAS in 109 of 208 cases (52.4%), as low STAS in 38 cases (18.3%), and as high STAS in 61 cases (29.3%). There were statistically significant associations between higher STAS and solid predominant invasive adenocarcinoma (p < 0.001), pleural invasion (p < 0.001), lymphatic invasion (p < 0.001), vascular invasion (p < 0.001), and tumor size of 10 mm or more (p = 0.037). There was a significant association between increasing STAS and shorter recurrence-free survival (RFS) in univariate analysis (no STAS, 154.2 months; low STAS, 147.6 months; and high STAS, 115.6 months). In a multivariate Cox proportional hazards model, only STAS (p = 0.015) remained a significant predictor of RFS.ConclusionsWe found that one-third of resected small adenocarcinomas had high STAS. Higher STAS was predictive of worse RFS.     

Practical model description of peripheral neural excitation in cochlear implant recipients: 3. ECAP during bursts and loudness as function of burst duration

In this, the third paper of the series, the loudness of low-rate bursts of electrical pulses was measured as a function of the burst duration, in subjects implanted with the Nucleus^® 24 cochlear implant system (three with straight and two with Contour™ electrode arrays). In order to help distinguish between the contributions of peripheral and more central effects, the ECAP was recorded to the individual pulses comprising the bursts, using the Neural Response Telemetry™ (NRT™) system. At a pulse rate of 250 pulses/s, the ECAP amplitude did not decrease greatly during the bursts: the mean reduction factor was 0.89. The time-constant for summation of the loudness contributions from the pulses comprising a burst was found to be larger than that associated with normal hearing. In addition, the first pulse of a pulse train was found to contribute much more to the overall loudness than did the subsequent pulses, although a corresponding difference was not observed in the ECAP recordings. These results establish a necessary connection between the essentially single-pulse model, developed in the fourth and fifth papers of the series, and the psychophysical data for pulse bursts, but they also have broader implications.     

Modulation of intein activity by its neighboring extein substrates

Inteins comprise a large family of phylogenetically widespread self-splicing protein catalysts that colonize diverse host proteins. The evolutionary and functional relationship between the intein and the split-host protein, the exteins, is largely unknown. To probe an association, we developed an in vivo and in vitro intein assay based on FRET. The FRET assay reports cleavage of the intein from its N-terminal extein. Applying this assay to randomized extein libraries, we show that the nature of the extein substrate bordering the intein can profoundly influence intein activity. Residues proximal to the intein-splicing junction in both N- and C-terminal exteins can accelerate the N-terminal cleavage rate by >4-fold or attenuate cleavage by 1,000-fold, both resulting in compromised self-splicing efficiency. The existence and the magnitude of extein effects require consideration for maximizing the utility of inteins in biotechnological applications, and they predict biases in intein integration sites in nature.     

点扩散函数法在人眼成像质量分析中的特征

目的采用点扩散函数（point spread function，PSF）分析系统，获得在人眼的视网膜成像质量表达中的各种特征，研究其在人眼成像质量评价中的作用。方法应用点扩散函数分析系统（PSF-1000），测量22例近视无散光者的视网膜成像质量，在瞳孔3mm和6mm状态下，取22眼调制传递函数（modulation transfer function．MTF）曲线中的12个点，分别等同于对数视力表4．0～5．1的12个点,针对PSF分析系统中的MTF参数进行比较和统计学分析。结果①PSF反映的是光强度大小和位置的偏差。PSF分析系统可直接采用屈光系统MTF曲线表达人眼的成像特征，该曲线MTF值从低频至中频迅速下降，高频趋向缓和至零，定量并客观地表达了人眼成像质量从低频至高频的改变。②左、右眼的MTF表达具有镜像对称性。⑧个体之间MTF值差异大（如空间频率为3．00c／d时，3mm瞳孔直径的MTF值为0．68-0．98，6mm瞳孔直径的MTF值为0．51～0．85）。④3mm和6mm瞳孔直径时的MTF值差异有统计学意义（P〈0.01）。结论点扩散函数分析系统既能表达总眼球成像的各种光学特性，又体现了像差、衍射和散射的共同影响。     

Gastrointestinal metastasis in hepatocellular carcinoma: radiological and endoscopic studies of 11 cases

BACKGROUND: From October 1990 to January 1999, 11 of 2237 hepatoma patients at our hospital had gastrointestinal tract metastasis. We describe the radiological and endoscopic features, clinical course and prognoses of those patients. METHODS: All patients were male. Six patients were hepatitis B carriers, and cirrhosis was noted in eight patients on admission. We reviewed all available radiological, endoscopic and pathological features. RESULTS: The commonest clinical presentation was frank gastrointestinal bleeding. Histological proof of gastrointestinal involvement was seen in six patients. Endoscopic features included ulcerative tumours mimicking advanced gastric carcinoma (43%) and submucosal tumours (29%). The sites of organ involvement were stomach (five), duodenum (two), colon (three) and duodenum and colon (one). Direct invasion by a contiguous neoplasm was the major route of gastrointestinal tract metastasis. Portal vein thrombosis may be the key point of haematogenous spread to other sites. CONCLUSIONS: The prognosis in these patients was extremely poor. Almost all patients died within 5 months if no further aggressive management was performed. Surgical intervention may be the optimal choice for palliative treatment of HCC with gastrointestinal tract involvement.     

Prognostic significance of microscopic and macroscopic extracapsular spread from metastatic tumor in the cervical lymph nodes

It has been established that the presence or absence of cervical node metastases in patients with head and neck squamous cell carcinoma (HNSCC) is a powerful prognostic indicator. This report reviews the evolution of thinking over the past 70 years with regard to the import and detection of cervical nodal metastases which exhibit spread of tumor beyond the confines of the original encompassing nodal capsule. In the process, this discussion touches upon clinical examination, gross and microscopic pathologic examination, and radiographic imaging studies. In particular, the distinction between gross nodal extracapsular spread of tumor and microscopic nodal extracapsular spread of tumor has been drawn in recent reports; this raises the possibility that identification of microscopic breaching of the node capsule by tumor might provide clinically significant information which is not provided by the gross observation of an intact lymph node capsule. While it remains to be seen whether microscopic extracapsular spread alone will prove to be an important prognostic factor, it is recommended that selective neck dissection continue to be offered even in those patients with clinically negative necks; further studies should aid in defining the import of microscopic extracapsular tumor spread in patients with positive cervical nodes.     

Intrinsic optical imaging reveals regionally different manifestation of spreading depression in hippocampal and entorhinal structures in vitro

The spatiotemporal features of spreading depression (SD) were analyzed in vitro by using combined hippocampal-entorhinal cortex slices. SDs were induced by microinjection of 1 M KCl in the stratum radiatum of the CA1 region of the hippocampus. Measurements of extracellular field potentials, extracellular space (ECS) volume changes and intrinsic optical signal changes were combined to study SD features in different regions of the slice. Each SD was associated with a pronounced shrinkage of the extracellular space (ECS) volume and a decrease in light transmittance. The beginning of the optical signal change occurred simultaneously with the electrographic onset as measured with extracellular microelectrodes but outlasted the dc shift for tens of seconds. The amplitude of the intrinsic optical signal change displayed marked regional variations with greatest changes of 12% in cortical regions. The signal amplitudes were considerably lower in hippocampal regions. The analysis of spread patterns revealed two types of waves: fully propagated waves spreading from CA1 all the way to the temporal neocortex and abortive waves that ceased earlier. The spread velocities displayed pronounced regional differences with highest velocities of 5.4 +/- 0.3 mm/min in the area CA3 of the hippocampal formation and lowest velocities of 2.7 +/- 0.1 mm/min in cortical regions.     

Tumour implantation following laparoscopy using different insufflation gases

Background : Because of the possibility of intraperitoneal seeding and port‐site recurrences following laparoscopic surgery, the role of laparoscopy in cancer surgery remains controversial. Previous experimental studies have suggested that chemical, metabolic and immunological changes following carbon dioxide (CO₂) insufflation may be responsible for this phenomenon. Earlier experimental studies done by the University of Adelaide Department of Surgery have also shown that helium insufflation is associated with none of the adverse changes brought about by CO₂ insufflation. Helium insufflation is also associated with lower rates of intra‐abdominal tumour spread. The aim of this study was to determine whether these identified benefits apply to inert gases in general. Methods : Twenty‐four Dark Agouti rats were randomized to undergo laparoscopy with 40 min insufflation using one of the following four gases (six rats in each group); CO₂, helium, argon and nitrogen. A tumour cell suspension was injected into the abdominal cavity at the beginning of laparoscopy. The rats were killed 7 days after surgery, and the peritoneal cavity and port sites were examined for the presence of tumour. Results : Rats undergoing helium insufflation, had the least number of port‐site recurrences and the least amount of intraperitoneal tumour spread. Argon and nitrogen pneumoperitoneum were associated with a large number of port‐site recurrences and widespread tumour seeding. The effect of CO₂ insufflation was intermediate. Conclusion : The choice of insufflation gas influences the incidence of port‐site metastases and the degree of intraperitoneal tumour spread following laparoscopic cancer surgery. The reduced port‐site recurrences and intraperitoneal spread that followed helium pneumoperitoneum is likely to be a unique property of this gas rather than a property of inert gases in general.