下颌骨侧位摄影X线中心线倾斜角度与垫板倾斜角度关系之探讨

目的探讨下颌骨侧位摄影分别采用一倾斜角度为α的垫板及未采用时，X线中心线倾斜角度各为β、γ之间的关系，为更简捷地拍好下颌骨提供理论参数和实践依据。方法立足于教科书，运用X线摄影原则与数学几何原理进行推理演绎。结果二者之间存在着可替换的关系，即γ=α＋β，可以大胆地去除垫板进行直接拍摄。结论不用垫板，只需通过增大X线中心线倾斜角度的方法，同样也能拍摄出一张好照片，且可操作性强，简便易行，实际使用价值更大。     

Effect of electric and chemical stimulation of the raphe obscurus on phrenic nerve activity in the cat

The effect of electrical and chemical (l-glutamate) stimulation of the raphe obscurus on phrenic nerve activity was examined in the cat. Phrenic nerve activity was recorded from a C5 nerve root in anesthetized, paralyzed and artificially ventilated cats. Neural discharge was quantitated by integrating the phrenic nerve activity. The respiratory frequency was determined from the integrated nerve signal. Focal electrical stimulation (18–144 μA; 5–40 Hz; 100 μs pulse duration) resulted in significant (P < 0.05) increases in both integrated phrenic nerve (IPN) amplitude and respiratory frequency. These changes were dependent upon current intensity and frequency of stimulation. The largest increases in IPN amplitude and respiratory frequency were47 ± 17%and146 ± 8%, respectively. To insure that the changes in integrated phrenic nerve activity (IPNA) were the result of stimulation of cell bodies and not axons of passage,l-glutamate (100, 200 nmol) was microinjected (100 nl) into the raphe obscurus. Significant (P < 0.05) dose-related changes occurred in integrated phrenic nerve amplitude with an increase of44 ± 13% at 100 nmol and80 ± 13% at 200 nmoll-glutamate. No significant increase in respiratory frequency was observed withl-glutamate microinjection. The results suggest that the raphe obscurus may be involved in respiratory control.     

Studying Weak Central Coherence at Low Levels: Children with Autism do not Succumb to Visual Illusions. A Research Note

While anecdotal reports of abnormal perceptual experiences in autism abound, there have been to date no experimental studies showing fundamental perceptual peculiarities. The present paper reports results from a first study of low-level visual integration in autism. Twenty-five subjects with autism, 21 normal 7- and 8-year-olds, and 26 children with learning difficulties were asked to make simple judgements about six well-known visual illusions. Two conditions were used, in an attempt to explore group differences; standard two-dimensional black and white line drawings, and the same figures augmented with raised coloured lines. The subjects with autism were less likely to succumb to the two-dimensional illusions than were the other groups, and were less aided by the three-dimensional disembedded' condition. These striking results are discussed with reference to the 'central coherence' account of autism.     

Short and long term effects of exercise training on the tonic autonomic modulation of heart rate variability after myocardial infarction

We studied the effects of cardiac rehabilitation on the sympathovagalcontrol of heart rate variability in 30 patients after a first,uncomplicated myocardial infarction. Twenty-two patients completed8 weeks of endurance training (trained), while eight decidednot to engage in the rehabilitation programme for logisticalreasons, and were taken as untrained controls. Age, site ofinfarction, ejection fraction, ventricular diameter and stresstest duration were similar in the two groups at baseline. Heartrate variability was evaluated 4 weeks after infarction beforestarting rehabilitation, and repeated 8 weeks and one year laterin both trained and untrained patients. Measures of heart ratevariability, obtained from both time- and frequency- domainanalysis of a 15 min ECG recording in resting conditions, wereas follows: mean RR interval and its standard deviation (RRSD),the mean square successive differences (MSSD), the percent ofRR intervals differing >50 ms from the preceding RR (pNTN50),the low and high frequency components of the autoregressivepower spectrum of the RR intervals and their ratio (LF/HF).At baseline, heart rate variability was similar in trained anduntrained patients. In the short term (8 weeks after infarction),training increased RRSD by 25% (P<0·01), MSSD by 69%(P<0·01), pNN50 by 120% (P<0·01), and reducedLF/HF ratio by 30% (P<0·01). The effects persistedafter one year in trained patients. In untrained patients, theautonomic control of heart rate variability did not change 8weeks after myocardial infarction and was only slightly modifiedby time. Thus, exercise training, performed for 8 weeks aftera myocardial infarction, modifies the sympathovagal controlof heart rate variability toward a persistent increase in parasympathetictone, known to be associated with a better prognosis. This maypartly account for the favourable outcome of patients who undergorehabilitation.     

年龄因素对健康人心率变异性的影响

目的探讨年龄因素对健康人心率变异性（ＨＲＶ）的影响。材料与方法将２３６例健康人分为五个年龄组，使用美国先进医用设备公司５．０版本ＨＲＶ软件做短时时域及频域ＨＲＶ分析。结果年龄因素对健康人ＨＲＶ短时时域和频域分析的多项指标产生显著影响，随着年龄增大，时域指标中的ＨＲＳＤ、ＳＤＡＮＮ、ｒＭＳＳＤ及ＰＮＮ５０均逐渐降低；随着年龄增长，频域指标中各频段下的绝对面积，即：ＶＬＦ、ＬＦ、ＭＦ及ＨＦ均逐渐降低；而频域指标中各频段下的相对面积，即：ＶＬＦＰ、ＬＦＰ、ＭＦＰ、ＨＦＰ随着年龄增长呈不同的发展趋势。ＬＦ／ＨＦ随着年龄的增加而逐渐升高。结论ＨＲＶ随着年龄的增加而下降，尤以迷走神经活性下降为显著。频域指标中各频段的相对面积较绝对面积能更敏感地反映交感、迷走神经张力的消长。     

Interleukin-6 production by astrocytes: Induction by the neurotransmitter norepinephrine

Astrocytes contribute to the immunocompetence of the central nervous system (CNS) via their expression of class II major histocompatibility complex (MHC) antigens and the production of inflammatory cytokines such as interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6). Of these cytokines, IL-6 is of particular interest because one of its many immune and inflammatory actions is the promotion of immunoglobulin synthesis, and it is thought that IL-6 expression within the brain exacerbates autoimmune diseases of the CNS, which are marked by local immunoglobulin production. Several stimuli induce astrocyte IL-6 expression, including such inducible endogenous factors as IL-1β and TNF-α. We have investigated the possibility that a constitutively present endogenous factor, the neurotransmitter norepinephrine (NE), can induce astrocyte IL-6 production. We report that NE induces both IL-6 mRNA and protein in primary neonatal rat astrocytes, with optimal induction at 10 μM. IL-6 protein induction by NE is comparable to that seen with IL-1β or TNF-α, and NE synergizes with these cytokines for a ten-fold enhanced effect. In contrast to astrocytes, microglia are relatively unresponsive to NE, IL-1β and TNF-α for IL-6 production. Experiments with the β-adrenergic receptor agonist isoproterenol, and α and β-adrenergic receptor antagonists (propranolol, phentolamine, atenolol, and yohimbine) indicate that β₂ and α₁-adrenergic receptors are involved in NE induction of astrocyte IL-6 expression. These results help to further the understanding of neuron-glial interactions, and the role of astrocytes and adrenergic activity in immune responses within the CNS.     

γ-Enolase and glial fibrillary acidic protein in nervous system tumors

Summary A large series of central and peripheral nervous system tumors was studied for the presence of glial fibrillary acidic protein (GFAP) and -enolase (neuron-specific enolase, NSE), using specific monoclonal antibodies (mAbs). Occurrence in and specificity of GFAP to glial and mixed tumors was confirmed and depended on the malignancy grade and features such as meningeal invasion. Using a well-characterized mAb, -enolase was demonstrated in neuronal, as well as in a whole range of non-neuronal tumors. This lack of specificity of -enolase prohibits its use as an exclusive neuronal marker. Nevertheless quantization or comparison with other types of enolases could still prove to be useful in well-defined situations. The advantages inherent to mAbs and a highly sensitive detection system turn GFAP stainings into a specific and readily reproducible technique.Supported in part by FGWO (grant no. 3.0019.86) and by the Geconcerteerde Actie (grant no. 84/89-68, Brain specific proteins)     

Cardiovascular reflexes and low long-term exposure to mercury vapour

Summary Subjective symptoms related to autonomic dysfunction and quantitative non invasive tests measuring both sympathetic and parasympathetic functions of the autonomic nervous system were studied among a group of 41 chlorine-alkali workers with low long-term exposure to mercury (Hg') vapour and their matched referents. The test battery included measurements of pulse rate variation in normal and deep breathing, in the Valsalva manoeuvre and in vertical tilt as well as blood pressure responses during standing and isometric work. The exposure time had been 16 years on average, and the mean exposure to Hg vapour was estimated to have been about 30 g/m³ of air. Only a tendency for a subtle reduction of cardiovascular reflex responses and a slight increase of subjective symptoms were seen in the exposed group, but no significant autonomic dysfunction was associated with the low level of exposure.     

The unit impulse response procedure for the pharmacokinetic evaluation of drug entry into the central nervous system

The unit impulse response theory has been adapted to characterize the transport profile of drugs into the central nervous system (CNS). From the obtained input function, the cumulative plasma volume (V) cleared by transport into the CNS in time can be calculated. Simulation studies demonstrated that transport governed by passive diffusion resulted in a linear relationship between V and time, while the slope of the line, the blood- brain barrier (BBB) clearance, proved to be an adequate and model independent parameter to characterize drug transport into the CNS. The error in the result of the numerical procedure could be limited to less than 10% of the theoretically predicted value. Superposition of 5 or 10% random noise on simulated data did not result in significant differences between the calculated and theoretically predicted clearance values. Simulations of carrier-mediated transport resulted in nonlinear transport curves; the degree of nonlinearity, and thus the detectability, was dependent on the initial degree of saturation of the system, the rate of desaturation, as caused by drug elimination processes and the noise level on the data. In vivoexperiments in the rat were performed, using atenolol, acetaminophen, and antipyrine as model drugs. Linear transport relationships were obtained for all drugs, indicating that transport was dependent on passive diffusion or a low affinity carrier system. BBB- clearance values were 7±1 l/min for atenolol, 63±7 ul/min for acetaminiphen and 316±25 l/min for antipyrine. These experiments validate the applicability of the presented technique in in vivostudies.     

Influence of ascending noradrenergic fibers on the neurotensin-like immunoreactive perikarya and evidence of direct projection of ascending neurotensin-like immunoreactive fibers in the rat central nucleus of the amygdala

The influence of ascending noradrenergic neuronal input on the neurotensin (NT)-like immunoreactive neuronal perikarya located in the dorsal part of the central nucleus of the amygdala (CNA) was examined using fluorescence histochemistry and peroxidase-antiperoxidase (PAP) immunocytochemistry. Unilateral hemitransection of the ascending noradrenergic pathway by injection of 6-hydroxydopamine into the caudal mesencephalon just rostral to the locus coeruleus caused a marked depletion of immunoreactivity in NT-like immunoreactive neuronal perikarya in the CNA. Ascending noradrenergic neuronal input, therefore, is considered to facilitate production of NT-like immunoreactive substances in neuronal perikarya and to influence on the functional role of the amygdaloid complex. In addition, we obtained evidence of unilateral direct ascending projections of NT-like immunoreactive neurons into the CNA since the disappearance of NT-like immunoreactive processes occurred mainly in the ventral part of the CNA after surgical hemitransection of the ascending neuronal pathway that interrupts the ascending NT-like immunoreactive pathway arising from the neurons in the brain stem.