Induction of DNA strand breaks by ethylene oxide in human diploid fibroblasts

In vitro exposure of normal human diploid fibro-blasts (strain VH-10) to ethylene oxide (EtO) induced DNA strand breaks in the dose range of 2.5–30 mMh of EtO. Alkaline DNA unwinding (ADU), neutral filter elution (NFE), pulsed field gel electrophoresis (PFGE), and the comet assay were used to measure DNA single (SSBs) and double strand breaks (DSBs). Different induction rates of SSBs and DSBs, depending on applied method and also on treatment conditions (cells in monolayer or in suspension were used), were found. A dose-dependent increase of DNA strand breaks was found by the ADU method in the dose range of 2.5–20 mMh of EtO when treatment was performed in monolayer and in suspension. DSBs were detected by NFE only when the cells were treated with EtO in suspension (doses 10–30 mMh). The highest induction rate of DSBs (about 4 DSBs per 100 Mbp per 1 mMh of EtO) was detected in suspension with PFGE applied. We have shown that heat-labile sites are formed by EtO. Presumably, the different DSB levels detected by PFGE and NFE result from the conversion of these sites to DSBs during cell lysis at elevated temperature in the PFGE method. The results of the comet assay confirmed that apoptotic processes are not involved in the formation of DSBs in our experimental conditions (less than 1% of apoptotic cells were observed at all doses studied). Possible mechanisms for the induction of DNA strand breaks by EtO-treatment are discussed. The capacity to repair DSBs in EtO-exposed (5–7.5 mMh) cells was studied, and it was found that a considerable part of the damage (about 50%) could be repaired during 18 hr of incubation. © 1994 Wiley-Liss, Inc.     

Auditory sensory processing in autism: a magnetoencephalographic study.

BACKGROUND: Patients with autism show clinical features suggestive of abnormal processing of auditory and other sensory information. We hypothesized that low-functioning autistic subjects present abnormalities in discriminating simple auditory stimuli at sensory system preconscious stages of cortical processing. METHODS: To verify our hypothesis, we used magnetoencephalographic measurements of mismatch field (MMF), which reflects the detection of a change in the physical characteristics of a repetitive sound. Fourteen patients (aged 8-32 years) who met DSM-IV diagnostic criteria for autistic disorder participated in an auditory oddball experiment. Ten healthy participants matched for age and gender acted as control subjects. RESULTS: Significant differences in cerebral responses between patients and control subjects were recorded. Whereas control subjects showed a clearly identifiable MMF, with distinct generators in the M100 brain wave with regard to latency, position, and strength, no identifiable MMF was present in the autistic group. CONCLUSIONS: Our findings suggest that low-functioning autistic subjects present a dysfunction at preconscious stages of cortical auditory discrimination, playing a role in the abnormal processing of auditory sensory afferences. The attention independence of the MMF allows for exclusion of an effect related to impaired attention or task-related responses.     

垂体肿瘤误诊为青光眼临床分析

本文对５例垂体肿瘤被误诊为“双眼青光眼”作了总结分析。作者认为：对于视力下降，视神经萎缩患者，应详细询问病史及详查视野，常规蝶鞍区Ｘ片检查，必要时ＣＴ检查，以便及时正确诊断及治疗。     

低场MR对肝脏正常结构的显示能力及评价

在低场ＭＲ横断Ｔ１加权像上，对６０例正常肝脏的解剖结构进行了观察，除胆道系统及门静脉段Ⅰ支外，余结构均能被显示。显示率以肝左后上缘静脉最低（６．６７％），而下腔静脉、肝中静脉、门静脉及门脉左支脐部最高（１００％）。显示率大于５０％的结构占６８％。     

Classical conditioning rapidly induces specific changes in frequency receptive fields of single neurons in secondary and ventral ectosylvian auditory cortical fields

To determine if learning-induced changes in the response of auditory cortical neurons to a conditioned stimulus (CS) reflect general changes in cellular excitability or alterations in signal processing that are specific to that stimulus, we determined frequency receptive fields (FRFs) of single neurons in secondary and ventral ectosylvian auditory fields of the cat during classical conditioning. Associative changes in FRFs of most cells were specific to the frequency of the CS, established rapidly and reversed by extinction. Thus, learning causes specific changes in cortical processing of sounds whose significance is acquired.     

Detection and discrimination of chromatic targets in hemianopic macaque monkeys and humans

We measured the ability of three macaque monkeys with unilateral removal of primary visual cortex to detect 9 degrees, 200-ms targets presented at random in the upper or lower quadrants of the normal and hemianopic visual fields. The white or variously coloured target could differ from the background in both colour and luminance, or in either of them. Blue and red targets were detectable at any luminance contrast, but green and white targets were barely or not at all detectable at and near isoluminance in the hemianopic field. Blue and red targets were better detected than white targets at the same luminance difference. However, when both the target and the background were dynamically luminance-masked, detection in the hemianopic field failed at isoluminance whatever the colour. In addition, the monkeys were unable to discriminate between simultaneously presented red and green or blue and green targets in the hemianopic field when both targets had similar luminance contrast with the background. Two hemianopic patients tested on a subset of the tasks performed similarly to the monkeys. Together, the results indicate that the residual colour-opponent system that survives damage to V1 is involved in the detection of chromatic changes but cannot sustain simultaneous discrimination between pairs of colours.     

乳腺病变的数字化摄影与屏片摄影之比较研究

目的:比较数字化乳腺摄影与屏片乳腺摄影对于乳腺病变的显示效果,明确数字化乳腺摄影的临床应用价值.材料和方法:本研究包括60例本院乳腺手术患者,同时进行前瞻性的屏片和数字化乳腺摄影,根据BI-RADS描述、诊断影像,并与病理结果对照分析,比较两者对乳腺病变的诊断价值.结果:数字化和屏片乳腺摄影对于乳腺病变的大多数影像学表现,其显示效果差异无统计学意义.数字化乳腺摄影显示钙化灶的效果优于屏片乳腺摄影,且有明显的统计学意义.结论:数字化乳腺摄影已达到与屏片乳腺摄影相同的诊断效果,且数字化乳腺摄影显示钙化灶具有相当的优势.     

Effects of adult-onset calorie restriction on anxiety-like behavior in rats

Calorie restriction (CR) has consistently been shown to increase lifespan and ameliorate disease outcomes. Its effects on behavior are less clear, although anxiolytic-like effects have been observed. Rats were subjected to 1 of 4 dietary regimens: control, CR25%, CR50% and, an acute episode of CR and tested in 3 tests of anxiety: the open field test, the elevated plus maze, and the modified open field test. In the open field test, the CR25% and CR50% groups made more central zone entries than the control and Acute groups, which was primarily due to differences in the initial 5 min of the test. Moreover, both CR groups engaged in greater exploration of the central zone than the control group in the initial 5 min of the test. The Acute group also exhibited significantly longer latencies to leave the central zone at test onset than the control and CR50% group. In the elevated plus maze, the Acute group also displayed longer latencies to open arm entry as compared to the control and CR50% group and showed a lower ratio of open to total arm entries compared to all other groups. There were no effects of CR on any variable of the modified open field test. Possible neurochemical mechanisms underlying the anxiolytic-like effect of CR are discussed.