Acute Changes in Left Atrial and Left Ventricular Diameters After Physiological Pacing

The present study examined alterations in left atria! diameter (LAD) and diastolic left ventricular diameter (LVDd) in 37 patients (72.2 ± 9.8 years old) who received physiological pacemakers; 22 with atrioventricular (AV) block and 15 with sick sinus syndrome (SSS). After pacemaker implantation, LAD and LVDd were serially measured using echocardiography, and their diameters ware expressed per body surface area (LADI and LVDdl; mm/m). Pulmonary capillary wedge pressure (PCWP) and cardiac output (CO) were measured in ten patients with SSS and ten with AV block during both right ventricular and AV sequential pacing. After AV sequential pacing, CO increased in 19 of 20 patients (3.2 ± 0.9 L/min to 3.9 ± 1.0 L/min: P < 0.001). LADI decreased from 24.9 ± 4.2 mm/m² to 21.8 ± 4.4 mm/m² (P < 0.001) in 22 patients with AV block and from 24.1 ± 3.4 mm/m² to 20.4 ± 3.8 mm/m² (P < 0.001) in 15 SSS patients. However, LVDdl did not change significantly in either group of patients. The changes in LAD after the implantation of a physiological pacemaker occurred rapidly, i.e. LAD began to decrease within 1 minute after the procedure, and then reached a plateau. This plateau phase continued for at least 7 days during physiological pacing. There was a positive correlation between the changes in LADI after pacemaker implantation and those in PCWP observed during the AV sequential pacing performed prim- to the implantation (r = 0.86; P < 0.001). The reduction in LAD following pacemaker implantation was rapid and seemed to be accompanied by improvement of cardiac function. Thus, it is suggested that the serial measurement of LADI is useful to predict the efficacy of physiological pacemaker implantation.     

颈椎管矢状径及截面积的应用解剖研究

为观察颈椎不同位置时椎管内结构的变化，解剖颈椎标本８具。用灌石腊的方法测量颈椎矢状径及截面积的变化。结果：颈椎轻度屈曲时，椎间盘、黄韧带、椎板、硬膜、脊髓的形态与位置发生变化，但对椎管容积影响不大，中立位和自然屈颈位时椎管矢状径和截面积两者均无明显差异（Ｐ＞０．０５）。提示：颈椎后路椎板成形椎管扩大手术时，坐位值得推荐。     

Postnatal development of conduction velocity and fibre size in the rat tibial nerve

The maximum conduction velocity (CV) and fibre diameters (D) were determined in the tibial nerve of developing rats. In 1-day-old rats CV of the fastest motor and sensory fibres (assessed separately) was 1.4 m/sec on the average and increased to 35 m/sec by postnatal day 30. The maximum conduction rate in adult rats ranged from 60 to 84 m/sec. Diameters of at least 100 nerve fibres in each age group were measured in electronmicrographs. The calibre of myelinating fibres in 1-day-old rats was 0.5–1.5 μm. By day 90 after birth the range of myelinated fibre size extended to 1.5–12.5 μm. The factor relating conduction rate and total fibre diameter of the largest fibres (i.e. the value of ) was found to vary with age, increasing from 1.1 to 6.2 between postnatal days 1 and 90. These results indicate that functional and morphological properties of peripheral nerve fibres in the rat undergo considerable changes during postnatal ontogeny until they reach adult values.     

The fetal biparietal diameter

Ultrasonographic measurement of the fetal biparietal diameter (989 measurements in 669 women) was used to investigate the relationship between the pattern of these measurements and the duration of pregnancy. An exponential function was tested with a computer, and equations were calculated for both combined series and single measurements. The linearity of the initial portion of the curve (< 30 weeks) was confirmed. The proposed function [y = ? 1.943 + 0.43 × ? 0.62 exp(0.058 ×)] was compared with an asymptotic function. Although serial sonographic assessment of the biparietal diameter is very useful in this respect, its applicability for calculation of the expected date of delivery is subject to the degree of variability characterizing any biological measurement.     

Increment of the fetal biparietal diameter during normal pregnancy,as determined by ultrasound

The fetal biparietal diameter was measured by ultrasound during normal pregnancy. 1076 measurements were performed. For each week of pregnancy, from 23 until 43 weeks, the mean, percentiles and smoothed percentiles were determined. From statistical analysis no influence of fetal sex and maternal parity on the fetal biparietal diameter was found. From the 50th percentile the weekly increment of the fetal biparietal diameter was calculated.     

新疆塔城地区哈萨克族,汉族老年性白内障直径,厚度测量

本文对塔城地区哈萨克族(简称哈族)、汉族老年性白内障48例手术及白内障直径、厚度测量进行分析,发现哈萨克族老年性白内障年龄前移,汉族年龄平均值66.21岁。而哈萨克族为60.76岁.哈族老年性白内障直径偏大,平均值12.67mm汉族平均值9.48mm.白内障厚度,哈族3.77mm,汉族4.40mm.经统计学上比较后均有显著性差异,汉族值与国内文献报道相一致,这是否与哈族在种族,生活环境等方面有关将需进一步考证.从观察所得数据,将使我们在防盲工作中增加白内障手术在啥族人群中的成功率,使更多的白内障哈族患者重见光明.     

Distinct morphological characteristics of touch,temperature, and mechanical nociceptive neurons in the crotaline trigeminal ganglia

Intrasomal recording and horseradish peroxidase injection techniques were employed in vivo to determine the morphological characteristics of touch, temperature, and mechanical nociceptive neurons in the trigeminal ganglia of crotaline snakes. The touch neurons, with a peripheral axon conducting at the A–β range, could be subdivided into tactile and vibrotactile neurons according to their response properties, but there were no morphological differences between them. These neurons exhibited a large and oval soma and possessed a set of large stem, peripheral, and central axons which were all myelinated and equal in diameter with a constriction at the bifurcation. The temperature neurons, which conducted peripherally at the A-δ; range, were physiologically separated into thermosensitive and thermo-mechanosensitive neurons, which were also morphologically indistinguishable. The temperature neurons had a round soma of medium size and a set of medium axons with varied axonal bifurcation patterns. All axons of these neurons were myelinated, but the central axon was thinner than the stem and peripheral axons. The mechanical nociceptive neurons, which had a peripheral axon conducting at the A-δ range, were morphologically heterogeneous based on their conduction velocities. The neurons conducting at the fast A-δ range were morphologically similar to the temperature neurons in the ganglion excepting their thinner central axons, whereas those at the slow A-δ range had a thinner myelinated stem axon that gave rise to a thinner myelinated peripheral axon and an unmyelinated central axon with a bifurcation of either a triangular expansion at the bifurcating point or a central axon arising straightforwardly from the constant stem and peripheral axons. This study revealed that distinct morphological characteristics do exist for the touch and temperature neurons and the subtypes of mechanical nociceptive neurons in the trigeminal ganglion, but not for the subfunctional types of touch neurons or temperature neurons. © 1995 Wiley-Liss, Inc.     

Measurement of basilar artery diameter in dogs: CT evaluation correlated with arteriography

Summary In this study we have used a computed tomographic (CT) method using profile analysis to measure the diameter of the basilar artery. In a search for a noninvasive and repeatable method to substitute for the traditional arteriography in the evaluation of the degree of cerebral vasospasm, we employed both CT and arteriography to measure the diameter of the basilar artery in eight adult mongrel dogs weighing between 7 and 12 kg. In three of these animals, assessments were made before and after subarachnoid hemorrhage (SAH) induced by injecting autologous arterial blood into the cistern magna. It was found that the basilar artery diameter as evaluated by CT was 47% larger than that measured by arteriography. However, there was a very good correlation (n=63, r=0.75, p<0.001) between the two methods. This paper presents a new model for the measurement of the basilar artery diameter, one which may also provide a safer method for the evaluation of vasospasm in humans.     

Local measurements of thrombus induced vasoconstriction in vivo

No data is available describing the local effect of thrombus formation on the vessel's diameter in vivo. As platelet or thrombus induced vasoconstriction seems to be of clinical importance in various diseases, it is desirable to get insight into the interrelation of thrombus formation and local vasoactivity. With a contactless photochemical process, endothelial cells can be damaged and thrombogenesis may be initiated in vivo. After first platelets stick to endothelial cells, a strong vasoconstriction is observed in arterioles. In venules, no vascular reaction can be observed. Constriction is most pronounced at the site of thrombus formation and decreases at growing distance. The thrombus is squeezed by the vascular constriction and thus mechanically held in place and squeezed out. A slight relaxation follows 30–80 rain later, but the vessel remains constricted during the following three hours. Thrombus induced vasoconstrictions can be reduced by papaverine, EP 092 (a thromboxane A₂ antagonist) and phentolamine in dose dependent manner in vivo. Papaverine was most effective followed by EP 092, Phentolamine was less effective, showing the minor importance of -receptor stimulation in this model.     

Wavelengths for laser treatment of port wine stains and telangiectasia

Background and Objective: This report presents analytical modelling of the influence of wavelength on the amount of volumetric rate of heat produced in dermal blood vessels by millisecond laser radiation. Study design/Materials and Methods: A new anatomical model is proposed that represents port wine stains as well as telangiectatic lesions. It consists of a target blood vessel, representing the deepest dermal blood vessel that requires irreversible injury, and a layer of whole blood, representing all other dermal blood vessels above the target vessel. The laser light that interacts with the blood vessels is assumed to be diffuse. Selective photothermolysis is the basis for the analysis. We consider wavelengths between 577 nm and 600 nm, the argon laser wavelengths at 488/515 nm, and the frequency doubled Nd:YAG laser wavelength at 532 nm. Results: The rate of volumetric heat production of absorbed laser light in the target blood vessel is expressed analytically as a function of blood absorption, the concentration of additional dermal blood, and the depth of the target vessel. Conclusion: The model explains why 585 nm is a good compromise for treating port wine stains that vary widely in number of dermal blood vessels. It predicts that wavelengths between 577 nm and 582 nm are excellent for the treatment of port wine stains in young children, and it suggests a possible explanation as to why the argon laser is sometimes said to be capable of treating dark mature port wine stains. The copper vapour laser wavelenght at 578 nm, and the frequency doubled Nd:YAG laser wavelength at 532 nm, are predicted to be suitable for the treatment of port wine stains that contain, respectively, a small to moderate and a moderate number of dermal blood vessels. When laser beam spotsize becomes smaller, the best wavelength for producing maximal rate of heat in the target vessel is predicted to shift to 577 nm. © 1995 Wiley-Liss, Inc.