The Diagnostic Effect of Brainstem Evoked Potential for Pancreatic Encephalopathy in Rats with Severe Acute Pancreatitis / 昆明医科大学学报

Objective The aim of this study is to demonstrate the diagnostic effect of brainstem evoked potential for pancreatic encephalopathy in rats with severe acute pancreatitis. Methods Sixty male Sprague-Dawley (SD) rats were randomly divided into two equal groups: a sham-operated (SO) group and a severe acute pancreatitis (SAP) group. Each group was evaluated at 3, 6, and 12 h during the experiment. To detect the brain stem evoked potential change at different time points. The ultrastructure of brain tissue was observed by transmission electron microscope (TEM). The expressions of the apoptosis-related proteins Bcl-2, Bax and caspase-3 were observed using immunohistochemical and Western Blot technique. Results In SAP group, congestion, edema, inflammatory cell infiltration, mitochondrial swelling and cell apoptosis were apparent. Compared with SO group, the brain stem evoked potential in severe acute pancreatitis group was obviously reduced in SAP group. Compared with SAP group, the expressions of Bcl-2 have increased, whereas the expressions of Bax and caspase-3 have decreased in SO group significantly ( <0.05) . Conclusion Brain stem evoked potential is a sensitive method in detection of rat brain damage. The results showed that the consistency and the damage degree of rats may be important clinical diagnostic index of pancreatic encephalopathy.

Apoptotic Pattern of Cochlear Outer Hair Cells and Frequency-specific Hearing Threshold Shift in Noise-exposed BALB/c Mice

OBJECTIVES: Apoptosis of outer hair cell (OHC) can be identified through nuclear staining by specific nuclear changes. The change of filamentous actin (F-actin) is also involved in early cell death process. The study was designed to investigate OHC death along the whole length of the organ of Corti. METHODS: BALB/c hybrid mice were used in this study. The noise group was exposed to white noise of 120 dB SPL for 3 hr per day for 3 consecutive days. The tone burst auditory brainstem response (ABR) test was conducted and cochleas from each group were obtained for the immunostaining of FITC phalloidin for F-actin and propidium iodide (PI) for nuclei. RESULTS: ABR threshold of the noise group significantly increased after noise exposure (P<0.001). No threshold shift was found in the control group. Threshold shift of the noise group constantly increased from 4 to 16 kHz, but threshold shifts at 16 kHz and 32 kHz were similar. Patterns of OHC staining were subclassified as FITC+PI- cells, FITC+ PI+ cells, FITC-PI+ cells and missing cells. Proportion of normal live OHCs (FITC+PI-) rapidly decreased from the apex to the base. In the basal turn, FITC-PI+ cells and vacancy OHC (missing cells) were observed easily. Apoptotic and missing cells were most abundant at 60% of the whole length of the Corti organ. CONCLUSION: We could subclassify morphologic changes in OHC death after noise exposure. Quantitative changes in OHCs along the whole Corti organ showed a plateau pattern similar to that of a frequency-specific threshold shift.

Computer Generated Three-Dimensional Reconstruction of the Auditory Pathway Structures of Brainstem

OBJECTIVE: The purpose of the study is to draw the three-dimensional reconstructions of nuclei and tracts of the auditory pathway structures of drainstem. METHOD: The drawings of 1 mm sections of the brainstem were scanned with a computer scanner into AUTOCAD program. All lines of structures except for the auditory pathway structures and outlines were removed. Each layer was plotted to a x, y, and z coordinated plotting reference to the corresponding points on the mid-sagittal plane and reconstructed to a three-dimensional drawing. Center point of the auditory pathway structures of all cross section layers were connected with a line in succession and that was thought to be a imaginary pathway of auditory pathway through the brainstem. RESULTS: This auditory pathway has several turning points, at the cochlear nucleus, superior olivary nucleus, and inferior colliculus which correspond with known generation sources of the peak of brainstem evoked potentials. CONCLUSION: This study presents a method for the conversion of the two-dimensional transverse sections into a three-dimensional format, to allow the visualization of the auditory pathway structures from multiple directions.

Auditory Brainstem Evoked Potential Responses in Focal Brain Lesions

Brainstem auditory response abnormalities directly reflect disturbance of neural function rather than the underlying anatomic cause of that disturbance. The test has advantage in detecting lesions that alter electrophysiology but do not produce detectable alterations of radiodensity, displace surrounding structures or change vascular supply and permeability. A sequence of seven low-amplitude potentials that occur in the initial 10 msec following click signals can be recorded from scalp electrodes in 44 patient with focal brain lesions using computer averaging techniques. The potentials, termed auditory brainstem responses, are thought to be the far-field reflection of electrical events originating in the auditory pathway during its course through the brainstem. We have studied auditory brainstem evoked potential responses in a variety of focal brain lesions and found them to be of assistance in evaluating the localization of pontomedullary, pons, midbrain, thalamus, subcortical and functional recovery. 1) Distortion of early components (type I) was occured in the brainstem lesions. 2) Distortion of late components (type II) was developed in the diencephalon or subcortical lesions. 3) Distortion of all components (type III) was developed in the brainstem and diffuse brain contusions. 4) Serial recordings provided information about the evolution of brain stem lesions and good functional recovery marker.

Auditory Brainstem Evoked Potential Responses in Focal Brain Lesions

Brainstem auditory response abnormalities directly reflect disturbance of neural function rather than the underlying anatomic cause of that disturbance. The test has advantage in detecting lesions that alter electrophysiology but do not produce detectable alterations of radiodensity, displace surrounding structures or change vascular supply and permeability. A sequence of seven low-amplitude potentials that occur in the initial 10 msec following click signals can be recorded from scalp electrodes in 44 patient with focal brain lesions using computer averaging techniques. The potentials, termed auditory brainstem responses, are thought to be the far-field reflection of electrical events originating in the auditory pathway during its course through the brainstem. We have studied auditory brainstem evoked potential responses in a variety of focal brain lesions and found them to be of assistance in evaluating the localization of pontomedullary, pons, midbrain, thalamus, subcortical and functional recovery. 1) Distortion of early components (type I) was occured in the brainstem lesions. 2) Distortion of late components (type II) was developed in the diencephalon or subcortical lesions. 3) Distortion of all components (type III) was developed in the brainstem and diffuse brain contusions. 4) Serial recordings provided information about the evolution of brain stem lesions and good functional recovery marker.