18F‐fluorodeoxyglucose positron emission tomography imaging in brain tumours: The Western Australia positron emission tomography/cyclotron service experience

¹⁸F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) scans in the first 49 patients referred with either possible brain tumour or brain tumour recurrence were reviewed. FDG‐PET imaging was reported with reference to anatomical imaging. Based on the report the FDG study was classified as either positive or negative for the presence of tumour. Thirty‐eight cases were included in the analysis, 21 having pathological data and 17 with diagnostic clinical follow up. Eleven were excluded, as they had inadequate follow‐up data. Of the 21 cases with pathology, 18 were shown to have tumour. In this group there were five false‐negative scans and two false‐positive PET scans. Seventeen cases were assessed by clinical follow up, nine were considered to have been tumour. There were two false negatives with one false positive. The overall sensitivity, specificity and positive and negative predictive values were 74, 73, 87 and 53% respectively. This is similar to figures previously quoted in published work. Despite relatively limited numbers, the utility of FDG PET imaging in our hands is similar to published reports. With a positive predictive value of 87%, a positive FDG study indicates a high likelihood that there is brain tumour present. A negative study does not exclude the presence of tumour.     

Cholelithiasis in infants, children, and adolescents

During the past two decades, cholelithiasis has been recognized in increasing numbers of pediatric patients. This diagnosis should be considered in the event of upper abdominal complaints, particularly when one or more risk factors are evident. The etiology may be unknown or may be related to risk factors, including hemolytic conditions. In recent years, it has become evident that approximately 80% of gallstones in children are not due to hemolytic disease and that the remaining 20% are related to recurring hemolysis. The diagnosis of gallstones is best confirmed with ultrasonography. Routine ultrasonographic evaluation should be performed at intervals for all children who received TPA for more than 4 weeks, particularly those who have had ileal resection or have had chronic enteritis (Crohn disease). Cholecystectomy is the procedure of choice for symptomatic children with cholelithiasis, regardless of age. Cholecystectomy is recommended for the asymptomatic child younger than 3 years of age when echogenic shadows have been present for at least 12 months following resumption of oral feedings or when the gallstones are radiopaque. Also, cholecystectomy is advised for asymptomatic children who are older than 3 years of age if ultrasonographic studies confirm that echogenic foci with shadowing are true stones and not echogenic sludge. Complications of common bile duct obstruction, pancreatitis, perforation with bile peritonitis, and life-threatening sepsis may thus be prevented. Morbidity and mortality following cholecystectomy are expected to be relatively low in the pediatric age group.     

An electrophysiological study of the effects of orthographic neighborhood size on printed word perception

In two experiments participants read words and pseudowords that belonged to either large or small lexical neighborhoods while event-related brain potentials (ERPs) were recorded from their scalps. In Experiment 1, participants made speeded lexical decisions to all items, while in Experiment 2 they engaged in a go/no-go semantic categorization task in which the critical items did not require an overt behavioral response. In both experiments, words and pseudowords produced a consistent pattern of ERP effects: items with many lexical neighbors (large neighborhoods) generated larger N400s than similar items with relatively fewer lexical neighbors (small neighborhoods). Reaction time (RT, Experiment 1), on the other hand, showed a different pattern consistent with previous behavioral studies. While words tended to produce a facilitation in RT for larger neighborhoods, pseudowords produced an inhibition effect. The findings are discussed in terms of recent theories of word recognition and the functional significance of the N400.     

Event-related potentials during discourse-level semantic integration of complex pictures

This study examined event-related potentials (ERPs) elicited in response to semantic processing of non-verbal stories. ERPs were recorded from 29 scalp electrodes on 16 participants while they viewed series of complex gray-scale pictures, each of which relayed a simple story. The final picture of each story was either congruous or incongruous with the preceding context. Participants made delayed meaningfulness judgments for each story. Averaged ERPs time-locked to the onset of the final picture were more negative for incongruous than congruous pictures. Two distinct components were sensitive to congruency. The first component peaked at approximately 325 ms (N300) and was distributed over central and frontal sites. The second component peaked at approximately 500 ms and also had a centro-frontal maximum but was more widespread than the earlier component (anterior N400). The distinct scalp topographies of these two negativities provide strong evidence that the N300 and N400 are separate and distinguishable components. Furthermore, the presence of the N300 in this exclusively pictorial task suggests that the N300 is specific to the semantic processing of non-verbal stimuli and is not due to linguistic mediation. This study also revealed that the N400 can be modulated by discourse-level coherence manipulations with pictures. Finally, the different patterns of ERP effects observed during the semantic processing of verbal and non-verbal information suggest that non-identical neuronal sources, and thus non-identical representational systems, are accessed by these different types of materials. These findings strongly support at least partial modularity of semantic representations and processing mechanisms in the human brain.     

难治性青光眼两种治疗方法的比较

临床资料 2003-02／2004—10，难治性青光眼36例36眼，(男19，女17)例；年龄37—81(平均59．6)岁；术前视力：无光感6例，光感15例，手动13例，眼前数指2例；术前眼压：在5．59—10．77(平均8．01)kPa；1例系玻切术后继发性青光眼，35例系新生血管性青光眼(其中：视网膜静脉阻塞15例，糖尿病视网膜病变18例，原因不明2例)．①眼内窥镜下睫状体光凝术18例：在角膜缘环形剪开结膜，充分止血；在     

Brain and ventricle instability during psychotic episodes of the schizophrenias

Recent reports from serial brain scans suggest that the rate of ventricular expansion and/or brain atrophy may be accelerated in at least some schizophrenics. The authors assessed the effect of state changes upon such findings.Within-subject 3D MRIs were assessed for ventricular and brain volumes during periods of [partial] remission and of exacerbation of psychosis. Additional scans at comparable within-subject SAPS were used to assess rates of change in volumes that were independent of SAPS changes.Correlations of changes of ventricle and brain volumes vs. change of SAPS cores between scans revealed that ventricle volumes decreased during a period of psychotic exacerbation and increased at a time of [partial] remission (r(p)=-0.666; P<0.0005); conversely, brain volumes increased during psychotic exacerbation and decreased at [partial] remission (r(p)=+0.448; P=0.032). Scans at comparable SAPS scores suggested that the majority of patients had rates of ventricular expansion comparable to controls (0.9+/-0.6 cc/year), though two patients appeared to have rates of ventricular increase of 4.5+/-2. 1 cc/year (Lilliefores P=0.036; K-means clustering F=17.75). Exacerbation of psychosis in schizophrenia is accompanied by evidence of brain swelling, especially of periventricular brain, with encroachment of brain substance upon ventricular volumes. Controlled for state changes, the majority of schizophrenics show rates of ventricular expansion or brain atrophy indistinguishable from controls.     

Innervation of supporting cells in the apical turns of the guinea pig cochlea is from type II afferent fibers

The outer supporting cells in the apical turns of the guinea pig cochlea receive a dense innervation. Our previous study (Fechner et al. [1998] J. Comp. Neurol. 400:299-300) suggested that this innervation of the Deiters' and Hensen's supporting cells was not derived from efferent fibers of the olivocochlear bundle, but its origin has not been further specified. To test the hypothesis that the innervation was afferent in origin, we traced apical afferent fibers that were retrogradely labeled by extracellular injections of horseradish peroxidase. Labeled afferent fibers were of two types: type I fibers contacted inner hair cells, whereas type II fibers crossed the tunnel and contacted outer hair cells. Significantly, most of the type II fibers also formed branches to the outer supporting cells. Although a few olivocochlear efferent fibers formed such branches, counts indicated that the overwhelming majority of the branches were produced by type II afferent fibers. These branches were not produced by basal type II fibers. Apical type II fibers also differed from basal fibers by having shorter lengths, spiraling both apically and basally, and contacting all three rows of outer hair cells. These innervation differences suggest differences in the ways that information from outer hair cells is processed in the apex versus the base of the cochlea.