Benzylamine oxidase in normal and atherosclerotic human aortae

Assays of serum benzylamine oxidase (BzAO) have led some workers to postulate a relationship between elevated BzAO activity and diseases characterized by proliferating connective tissue. The present study was designed to determine whether BzAO activity of a cellular tissue is also affected. BzAO was assayed in homogenates of normal and atherosclerotic human aortae. Characterization done in normal aortae showed that BzAO is not a classical monoamine, diamine, polyamine, or lysyl oxidase, nor is it a ceruloplasmin. The enzyme is heat stable at 60 degrees C and is associated primarily with the microsomal fraction on density centrifugation. Compared with phenylethylamines and indoleamines, benzylamine is the best substrate. BzAO is sensitive to inhibition by hydrazines and chymotrypsin but not trypsin, and is insensitive to Triton X-100 and sulfhydryl-group blockade. BzAO activity of atherosclerotic plaque (expressed per gram wet weight or per milligram protein) was decreased markedly compared to that in adjacent, nonplaque regions and in normal aortae. However, on a per milligram DNA basis, the BzAO activity of plaque did not differ from that of nonplaque tissue. We conclude that there is a decreased cell population density in plaque, a contention supported by kinetic analysis. Plaque BzAO showed a decreased Vmax with no change in the Km of benzylamine compared with nonplaque tissue. Thus, if a relationship exists between BzAO activity and proliferating connective tissue, it is not apparent at the level of the cellular enzyme in atherosclerotic aortae of man.     

Changes in the blood supply of the gastrointestinal tract in rats with age

Summary Regional blood flow of the gastrointestinal (GI) tract and cardiac output have been determined in male Sprague-Dawley rats weighing from 30–726 g. The cardiac output (ml/min per kg) was highest in rats weighing 80–100 g. In heavier rats the cardiac output decreased proportionally with the body weight. The gradient of blood flow to the different parts of the GI tract develops step by step. In the weaning period the blood flow (ml/min per g tissue) through the stomach was less than that through the distal parts of the GI tract. However, the blood flow through the small intestine, cecum and large intestine was uniform at this age. In rats weighing 80–100 g the blood flow through both the cecum and large intestine was less than that through the small intestine. The gradient in blood flow through the various segments of small intestine developed last.     

Correlation between the Ki-67 antigen in the brainstem and physiological data on sleep apnea in SIDS victims

Background: The Ki-67 antigen appears in all human proliferating cells during late G1, S, M and G2 phases of the cell cycle, but is consistently absent in the G_o phase (noncycling) cells. The correlation between Ki-67 in the brainstem and sleep apnea in victims of the sudden infant death syndrome (SIDS) was investigated to elucidate cell kinetics in the brainstem of this condition, which is still the main cause of postneonatal infant death. Materials and methods: Twenty-six cases of SIDS occurred among 38 infants dying under 6 months of age in a cohort of 27,000 infants studied prospectively to characterize their sleep–wake behavior. All the infants had been recorded during one night in a pediatric sleep laboratory some 3–12 weeks before death. The frequency and duration of sleep apnea were analyzed. At autopsy, brainstem material was collected and immunohistochemistry for Ki-67 was carried out. The density of Ki-67-positive neurons was measured semiquantitatively. Correlation analyses were carried out between the density of Ki-67-positive neurons and the data on sleep apnea. Results: Except in two cases in SIDS victims and in one control, the detection of Ki-67 was negative. No correlation analysis between the Ki-67 and of sleep apnea was found. Conclusions: There were no abnormal cell kinetics detected by the demonstration of Ki-67 antigen in the brainstems of SIDS victims.     

GM and KM allotypes in eight tribal populations of madyha Pradesh and Orissa, India

Summary Serum samples from eight endogamous Indian tribal populations of Madhya Pradesh (Dhurwa, Halba, Bhatra, Muria, Maria) and Orissa (Deshia Khond, Binjhal, Kisan) with a total of n=731 unrelated individuals were typed for G1M (1,2,3,17), G3M (5,10,11,13,14,15,16,21,26), and KM (1). In seven of these populations five different GM haplotypes were found:GM*1,17;21,26; GM*1,17;10,11,13,15,16; GM*1,2,17;21,26; GM*1,3;5,10,11,13,14,26; andGM*3;5,10,11,13,14,26. In the Kisan sample the haplotypeGM*1,2,17; 21,26 is absent. The intergroup variability in the distribution of these haplotypes is considerable and statistically highly significant. The reasons for that can be attributed to the ethnohistory and to the genetic isolation of these eight endogamous tribal populations. The GM haplotype distribution pattern of all these groups is quite different from that of the non-tribal populations of India, whereas it is in good agreement with that of the so far tested other tribal populations from India. This can be explained by different origin and history of the Indian tribal and non-tribal populations. In the KM system, too, remarkable variability is seen in the distribution of phenotype and allele frequencies among the eight tribal populations under study.     

Astroglia—Neuron interactions that promote long-term neuronal survival

Besides intrinsic determinants of cell growth, epigenetic signals have been proposed to regulate development and maintenance of neurons. Here we provide evidence that cerebral astrocytes contribute significantly to the set of environmental influences that are required for long-term survival of neurons derived from the mammalian central nervous system. Cerebral astrocytes in serum-free culture express diffusible and non-diffusible neuron-supporting signals, including cell-adhesive neurite growth-promoting glycoproteins, diffusible neurotrophic factors as well as membrane-bound molecules that mediate cell contact interactions. The combination and synergistic interaction of these environmental signals markedly enhance the survival of brain neurons. While astroglia-derived cell-adhesive substrates that include a high molecular weight complex consisting of laminin β-chains and proteoglycan (Matthiessen et al., 1989) stimulate neurite outgrowth, they fail to enhance long-term neuronal survival when additional neurotrophic and cell-contact interactions are lacking. Astrocytes release a diffusible neurotrophic activity that, when permanently applied, maintains long-term survival of central neurons in culture. The soluble neurotrophic activity seems to interact synergistically with cell-bound signals which are also required for long-term survival and which are expressed by astrocytes and neurons, but not by fibroblasts. Among neurons from different brain areas, such as hippocampus, cerebral cortex and septum, regional differences in their responsiveness to the astroglial neurotrophic activity have been observed.     

枢椎齿突骨折的有限元分析

目的：建立枢椎的三维有限元(FE)模型，探讨在前、后方不同载荷下齿突的不同损伤机制和骨折类型。方法：对一例新鲜枢椎标本进行CT扫描，层厚1mm，扫描图像转换后输入微机，通过软件PRO／E重建枢椎的三维立体模型，再转入有限元软件MARK并赋予此模型物理材料属性，然后模拟齿突骨折的受力条件，在齿突中性矢状面对齿突施加不同角度的载荷，分析各种条件下枢椎模型的应力、应变分布，探讨相应条件下可能导致的枢椎齿突骨折类型。结果：(1)对于齿突前部斜向后下方载荷，应力集中区从齿突前上部斜贯穿至后下部；对于齿突前部斜向后上方载荷，应力集中区从齿突前下部斜贯穿至后上部；齿突腰部始终保持高应力；(2)在齿突后部载荷下，其应力集中情况与前部载荷相似，不过应力集中区位置有所偏下。结论：(1)在齿突中性矢状面，齿突前部载荷容易导致齿突腰部发生断裂，形成枢椎齿突Ⅱ型骨折，也可能导致基底部发生断裂，形成枢椎齿突Ⅲ型骨折；(2)齿突后部载荷更容易导致基底部发生断裂，形成枢椎齿突Ⅲ型骨折。     

Variability of thoracic impedance cardiograms in man

The variability of thoracic impedance cardiogram signals was studied in a normal population with the objective of determining the effect of different respiratory manoeuvres and the optimal criteria for acquisition of this type of physiological signal. The variability of the first derivative of the thoracic impedance signal (dZ/dt) was determined at each 5ms intervals along the signal as the ensemble confidence limits of 3% and 97% around the coherent average. The results obtained indicate that: (a) signal variability is minimum during respiratory apnea (p<0.05) as compared with apneusis or normal respiration, (b) signal patterns are different during apnea and apneusis, and (c) during normal respiration the cardiac component of the thoracic impedance signal can be extracted from the respiratory noise by coherent average yielding a signal with the same pattern obtained during apnea.     

A simple and inexpensive metabolic cage for mice

An inexpensive and easily constructed metabolic cage for mice is presented. This apparatus can reliably monitor food and fluid consumption, as well as urine and fecal output, in a relatively non-intrusive manner.     

Naloxone-provoked vaso-vagal response to head-up tilt in men

A double-blind paired protocol was used to evaluate, in eight male volunteers, the effects of the endogenous opiate antagonist naloxone (NAL; 0.05 mg· kg^–1) on cardiovascular responses to 50° head-up tilt-induced central hypovolaemia. Progressive central hypovolaemia was characterized by a phase of normotensive-tachycardia followed by an episode of hypotensive-bradycardia. The NAL shortened the former from 20 (8–40) to 5 (3–10) min (median and range; (P < 0.02). Control head-up tilt increased the means of thoracic electrical impedance [from 35.8 (SEM 2.1) to 40.0 (SEM 1.8) ; P < 0.01 of heart rate [HR; from 67 (SEM 5) to 96 (SEM 8) beats · min^–1, P < 0.02], of total peripheral resistance [TPR; from 25.5 (SEM 3.2) to 50.4 (SEM 10.5)mmHg min 1^–1,P < 0.05] and of mean arterial pressure [MAP; from 96 (SEM 2) to 101 (SEM 2)mmHg, P < 0.02]. Decreases were observed in stroke volume [from 65 (SEM 12) to 38 (SEM 9) ml, P < 0.01], in cardiac output [from 3.7 (SEM 0.7) to 2.5 (SEM 0.5) 1 · mint, P < 0.01], in pulse pressure [from 55 (SEM 4) to 37 (SEM 3)mmHg, P < 0.01] and in central venous oxygen saturation [from 73 (SEM 2) to 59 (SEM 4)%, P < 0.01]. During NAL, mean HR increased from 70 (SEM 3); n.s. compared to control) to only 86 (SEM 9) beats · min^–1 (P < 0.02 compared to control) and MAP remained stable. The episode of hypotensive-bradycardia appeared as mean control HR decreased to 77 (SEM 7)beats · min^–1, TPR to 31.4(SEM 7.7)mmHg · min · 1^–1 and MAP to 60 (SEM 5)mmHg (P < 0.01), and the volunteers were tilted supine. Cardiovascular effects of naloxone on central hypovolaemia included a reduced elevation of HR and blood pressures and provocation of the episode of hypotensive-bradycardia.     

基于粗配准和混合互信息的医学图像配准算法

利用边缘检测算子和数学形态学方法提取医学图像轮廓,采用主轴矩法配准两幅图像的轮廓,使其达到粗略配准的目的。通常的互信息测度是基于香农熵的,因为香农熵对于局部极值具有很强吸引域,而某些参数下的雷尼熵可以消除局部极值,将两种测度分别用于精配过程中不同的搜索阶段。首先利用全局搜索算法,寻找基于雷尼熵的归一化互信息测度的全局最优初值,再通过局部优化算法对当前的最优解寻找基于香农熵的更精确的全局最优解。实验表明,这种配准算法是有效的。