Age‐related changes in histogram pattern of anterior horn cells in human cervical spinal cord

The purpose of the present study was to clarify age‐related changes in histograms of spinal anterior horn cells. The study examined Rexed lamina IX of the C7 spinal cord segment in 22 men who had died of non‐spinal disease (age range, 0–85 years). First, we confirmed that the size of nucleoli exhibited a linear relationship to the diameter of spinal anterior horn cells by preparing histograms of nucleoli. Second, this formula was used to create histograms of cervical anterior horn cells. Results were as follows: (i) diameter of nucleoli ranged from 2.0 µm to 6.0 µm; (ii) in each subject, no changes were seen in histogram patterns among ventral, intermediate, dorsal and overall sections; (iii) at ≤ 20 years of age, histograms displayed a single peak for the diameter of nucleoli at about 4.0–4.5 µm; (iv) at 21–60 years of age, histograms displayed two peaks, at about 3.5–4.0 µm and 5.0–5.5 µm; and (v) at 61–85 years of age, histograms displayed a single peak at about 5.0–5.5 µm.     

DVH评价食管癌适形放疗计划对肺的影响

[目的]了解不同食管癌适形放疗计划对肺的影响。[方法]选择7例胸段食管癌病例,用ACQPLAN系统进行CT模拟定位并设计不同适形放疗计划,用剂量体积组方图(DVH)指标进行对比。每一例均设计三野(一前、二后斜)、四野(二前斜、二后斜)和六野(四野加一前一后野),对比以上不同计划中全肺平均接受剂量(Dmean)和受量超过20Gy的肺体积(V20Gy)。[结果]三野和六野计划的肺Dmean较接近,均明显低于四野计划的Dmean(P<0.01);三野计划的V20Gy明显低于四野和六野计划的V20Gy(P<0.01)。三个计划中所有病人的脊髓受照射剂量均在45Gy以下。[结论]综合考虑对脊髓和肺的影响,三野计划为食管癌适形放疗的较优方案。     

Correction for variations in MRI scanner sensitivity in brain studies with histogram matching

Quantitative comparisons of abnormalities in MRI scans between patients or within patients serially are affected by variations in MR scanner performance. A histogram matching method is proposed to correct for variation in scanner sensitivity. It is demonstrated that this histogram matching method reduced the variation in white matter intensities across normal subjects from 7.5 to 2.5% and provided a method to remove the threshold dependency in lesion volume measurement with global thresholding in patients with multiple sclerosis (MS). The effectiveness of the method was compared with three other possible correction schemes. The histogram matching method was shown to be 2 to 5 times better.     

Sensitivity of the acoustic startle response and neurons in subnuclei of the mouse inferior colliculus to stimulus parameters

Stimulus frequency, intensity, interstimulus interval, and risetime were evaluated for their influence on the acoustic startle reflex, determined by behavioral and EMG techniques, and on the activity of multiple-unit clusters in subdivisions of the mouse inferior colliculus. Tones of 5, 10, and 20 kHz were capable of eliciting the startle response when presented at 80-dB SPL intensities, 5-ms rise time, and variable intervals. The most effective frequency was 10 kHz. Changing the parameters to either 70 dB SPL, 20-ms rise time, or fixed intervals each resulted in a reduced startle response. Discharge rates of most unit clusters in the ventrolateral division of the central nucleus were not reduced under these conditions. By contrast, many clusters in the pericentral and external nuclei showed reduced responsiveness to fixed interval schedules and 20-ms rise time. Some correspondence between the limited effectiveness of 20-kHz tones in eliciting the startle response and the relatively poor 20-kHz responses of neurons in the pericentral and external nuclei was noted. In general, increasing stimulus intensity from 70 to 80 dB produced an increase in the number of discharges evoked in all inferior colliculus subdivision. It is proposed that a pathway mediating the acoustic startle response is likely to include a projection from the ventrolateral division to the pericentral and/or external nuclei and ultimately to motor neurons.     

Local histogram information content of ultrasound B-mode echographic texture

In the diagnostic ultrasound community, the echographic B-scan texture is an important area of investigation since it can be analyzed to characterize the histologic state of internal tissues. In the present paper, a minicomputer based system was used to digitize B-mode images and to develop a method to measure their textural information. This method is based on the concept of local information content of spatial image proposed by Lowitz (1983, 1984). It first measures the local gray-level histogram in a small square window centered on each picture element (pixel) of a digitized B-mode image. The information derived from the local histograms is then used to characterize the tissues, to partition the B-mode image into homogeneous zones of texture, to estimate to what extent a tissue is different from another, to delimit the contours of a tissue and to measure its surface. The method is illustrated on the thyroid gland but it can be applied to the study of other organs.     

Activity-Controlled Circadian Base Rate

The current pacing rates are clustered around a fixed base rate since pacemaker patients are usually sedentary, resting, or sleeping most of the time. This fixed base rate is either too low for daytime hemodynamic support or too high for nighttime rest and recovery. Multiple Holter studies involving normal individuals have suggested that the resting base rate fluctuates during the course of the day. The circadian base rate (CBR) algorithm was designed to provide patients with a circadian change in paced resting rate and a normal rate distribution. The CBR algorithm, using a sophisticated accelerometer sensor, was developed and tested using the downloaded activity data from patients implanted with Trilogy DR+ pacemakers. Twenty-five patients (19 men, 6 women, age 72 ± 9 years) were studied. Trilogy DR+ is able to record the detailed sensor and system behavior data for a week. During outpatient visits, the pacemaker was interrogated and the data accumulated in the pacemaker memory were downloaded. The CBR algorithm was applied to the activity variance histogram to calculate the base rate and to construct its histogram. The base rates in the CBR histogram are generally below 100 ppm with a distribution that mimics the natural sinus rate distribution of normal subjects. The CBR algorithm provides the highest daytime rates for hemodynamic support and the lowest nighttime rates for cardiac recovery, with a smoothly changing base rate modeling the normal circadian variation in heart rate.     

Habituation of human limbic neuronal response to sensory stimulation

Hippocampal, parahippocampal gyrus, and amygdalar neuronal responses to visual and acoustic stimuli were analyzed during trains of several hundred stimulus repetitions as part of an investigation of sensory pathways to medial temporal lobe structures in complex-partial epilepsy patients who were being monitored with depth electrodes. Ten percent of more than 500 single and multiple units tested were responsive to simple sensory stimuli. The majority of the responsive units were recorded in the posterior parahippocampal gyrus (HG) during visual stimulation. Although neurons in pes hippocampi (PH; Ammons's horn) were also responsive to photic stimuli, no visually responsive units were found in amygdala. Very few units were responsive to acoustic stimuli, and these were found only in PH and amygdala, and not in HG. Significant trends of increase or decrease in response amplitude during trains of stimuli were found in all acoustically responsive units. Significant trends of visual response amplitude increase or decrease were found in 20% of PH units, and in 44% of HG units. Mean latencies of acoustically responsive units were longer than those of visually responsive units, and latencies of PH sensory units showing decremental response were longer than nondecremental PH units. Rate of response decrement was usually linear for acoustic responses and exponential for visual responses. The response dynamics of medial temporal lobe neurons are compared with those described in the animal limbic system and are related to habituation of human sensory evoked scalp potentials.     

Anesthetic-dependent excitability changes in the hypothalamic ventromedial nucleus of the rat

In acute experiments in rats anesthetized with urethane, the field potentials, population spike, and unit activity evoked in the hypothalamic ventromedial nucleus (HVM) by amygdaloid stimulation are significantly increased with respect to control when preceded by a conditioning volley at 20- to 100-ms intervals. Under pentobarbital anesthesia, in contrast, the evoked responses were inhibited by the conditioning stimulus for similar interstimulus intervals. In unanesthetized animals chronically implanted with stimulating and recording electrodes, a facilitation of responses by a conditioning stimulus was observed when they were awake or anesthetized with urethane. When the same animals were anesthetized with pentobarbital the HVM evoked response was inhibited by a conditioning pulse. Frequency facilitation and post-tetanic potentiation of HVM responses were markedly enhanced under urethane, whereas in pentobarbital-anesthetized animals inhibition predominated. Picrotoxin reversed the inhibition under pentobarbital to facilitation. These results suggest that the HVM neuron population is under both excitatory and inhibitory influences from the amygdala, the former being predominant in awake and urethane-anesthetized animals and the latter being expressed under pentobarbital anesthesia and is probably mediated by γ-aminobutyric acid.     

Improvements in clinical electronystagmogram analysis

The authors apply the technique of amplitude histogram analysis to the clinical electronystagmogram (ENG). After a brief survey of the underlying concepts, some typical normal and pathological ENG records are discussed.Comparison of advantages and disadvantages reveals that the quoted technique may be suitable to be profitably introduced in clinical practice.