The use of successive blood-pressure measurements to estimate blood-pressure variability

Multiple daily, self-determined blood-pressure measurements were obtained from 254 hypertensive patients for 1 month. In an effort to establish a practical and reliable technique for estimating blood-pressure variability, standard deviations from three (at one time of day) or nine (throughout the day) successive self-determinations were compared with a reference value, taken to be the standard deviation for the entire month (252 determinations per subject). Neither the standard deviation of three measures taken on one occasion nor that of nine measures taken throughout the day correlated well with the reference value (average R₃=.21 for SBP, .20 for DBP; average R₉=.39 for SBP, .38 for DBP). However, when a sample consisting of 12 measures (taken three at a time, at the same time of day, weekly for 4 weeks) was used, the average correlation rose to .60 for SBP and .54 for DBP. Thus, it appears that 12 samples taken in this way provide a reliable estimate of the standard deviation for an entire month, and it is suggested that this sampling technique also would enhance the reliability of conclusions drawn from assessments of the prognostic value of blood-pressure variability.     

Cerebellar involvement in the coordination control of the oculo-manual tracking system: effects of cerebellar dentate nucleus lesion

Summary When the hand of the observer is used as a visual target, oculomotor performance evaluated in terms of tracking accuracy, delay and maximal ocular velocity is higher than when the subject tracks a visual target presented on a screen. The coordination control exerted by the motor system of the arm on the oculomotor system has two sources: the transfer of kinaesthetic information originating in the arm which increases the mutual coupling between the arm and the eyes and information from the arm movement efferent copy which synchronizes the motor activities of both subsystems (Gauthier et al. 1988; Gauthier and Mussa-Ivaldi 1988). We investigated the involvement of the cerebellum in coordination control during a visuo-oculo-manual tracking task. Experiments were conducted on baboons trained to track visual targets with the eyes and/or the hand. The role of the cerebellum was determined by comparing tracking performance defined in terms of delay, accuracy (position or velocity tracking errors) and maximal velocity, before and after lesioning the cerebellar dentate nucleus. Results showed that in the intact animal, ocular tracking was more saccadic when the monkey followed an external target than when it moved the target with its hand. After lesioning, eye-alone tracking of a visual target as well as eye-and-hand-tracking with the hand contralateral to the lesion was little if at all affected. Conversely, ocular tracking of the hand ipsilateral to the lesion side became more saccadic and the correlation between eye and hand movement decreased considerably while the delay between target and eyes increased. In normal animals, the delay between the eyes and the hand was close to zero, and maximal smooth pursuit velocity was around 100 degrees per second with close to unity gain; in eye-alone tracking the delay and maximal smooth pursuit velocity were 200 ms and 50 deg per second, respectively. After lesioning, delay and maximum velocity were respecttively around 210 ms and 40 deg per second, that is close to the values measured in eye-alone tracking. Thus, after dentate lesioning, the oculomotor system was unable to use information from the motor system of the arm to enhance its performance. We conclude that the cerebellum is involved in the coordination control between the oculomotor and manual motor systems in visuo-oculo-manual tracking tasks.     

Reach to grasp: the natural response to perturbation of object size

This study assessed the reach to grasp movement and its adaptive response to a perturbation of object size. In blocked trials, subjects (n = 12) were instructed to reach 35 cm to grasp and lift a small- (0.7 cm) or large-diameter (8 cm) cylinder. Under an unconstrained condition (condition 1), no instructions as to the type of grasp to adopt were given. Subjects thus naturally used a precision grip (PG) for the small cylinder and whole hand prehension (WHP) for the large cylinder. Under condition 2, subjects were instructed to utilize a PG for grasps of both the large and small cylinders. For condition 3, the instruction was to use WHP irrespective of object size. Kinematic organization was determined with analysis of the recordings of active markers placed on the wrist, thumb, and three fingers. For condition 1 the results showed a temporal arrangement of both components (transport and manipulation) which differed from that of conditions 2 and 3. In perturbed trials, illumination shifted from the small to large cylinder or vice versa. With condition 1, subjects automatically switched from one grasp to another with no or little increase of movement duration. This was generally achieved by an earlier temporal setting of peak wrist deceleration. For conditions 2 and 3, where a change of aperture was required, movement duration was prolonged without adaptation of earlier transport component parameters. It is concluded that the adaptive responses to a change of distal patterning also affect the organization of the proximal component. Assessment of grasps constrained by instructions may lead to interpretations of central control of the reach to grasp movement which differ from those obtained by assessing more natural prehensile patterns.     

Brain stimulation-induced changes of phonation in the squirrel monkey

Summary In 11 squirrel monkeys (Saimiri sciureus), the brain stem was systematically explored with electrical brain stimulation for sites affecting the acoustic structure of ongoing vocalization. Vocalization was elicited by electrical stimulation of different brain structures. A severe deterioration of the acoustical structure of vocalization was obtained during stimulation of the caudoventral part of the periaqueductal grey, lateral parabrachial area, corticobulbar tract, nucl. ambiguus and surrounding reticular formation, facial nucleus, hypoglossal nucleus, solitary tract nucleus and along the fibres crossing the midline at the level of the hypoglossal nucleus. It is suggested that these structures are part of, or at least have direct access to, the motor coordination mechanism of phonation. Complete inhibition of phonation was obtained from the raphe and raphe-near reticular formation.Abbreviations Ab nucl ambiguus - APt area praetectalis - BC brachium conjunctivum - BP brachium pontis - Cb cerebellum - CC corpus callosum - Cd nucl. caudatus - Cf nucl. cuneiformis - Cel nucl. centralis lateralis - Cl claustrum - CM centrum medianum - Cn nucl. cuneatus - Co nucl. cochlearis - CoI colliculus inferior - CoS colliculus superior - CP commissura posterior - CPf cortex piriformis - CRf corpus restiforme - CSL nucl. centralis superior lateralis thalami - CT corpus trapezoideum - DBC decussatio brachii conjunctivi - DG nucl. dorsalis tegmenti (Gudden) - DLM decussatio lemnisci medialis - DPy decussatio pyramidum - DR nucl. dorsalis raphae - DV nucl. dorsalis n. vagi - DIV decussatio n. trochlearis - EP epiphysis - FC funiculus cuneatus - FL funiculus lateralis - FLM fasciculus longitudinalis medialis - FRM formatio reticularis myelencephali - FRP formatio reticularis pontis - FRPc formatio reticularis pontis caudalis - FRPo formatio reticularis pontis oralis - FRTM formatio reticularis mesencephali - FV funiculus ventralis - G nucl. gracilis - GC substantia grisea centralis (periaqueductal grey) - GL nucl. geniculatus lateralis - GM nucl. geniculatus medialis - GP globus pallidus - GPM griseum periventriculare mesencephali - GPo griseum pontis - Hip hippocampus - HL nucl. habenularis lateralis - H habenula - IP nucl. interpeduncularis - LC locus coeruleus - LD nucl. lateralis dorsalis thalami - Lim nucl. limitans - LLd nucl. lemnisci lateralis, pars dorsalis - LLv nucl. lemnisci lateralis, pars ventrali - LM lemniscus medialis - LP nucl. lateralis posterior thalami - MD nucl. medialis dorsalis thalami - MV nucl. motorius n. trigemini - NCS nucl. centralis superior - NCT nucl. trapezoidalis - NMV nucl. mesencephalicus n. trigemini - NR nucl. ruber - NSV nucl. spinalisn. trigemini - NTS nucl. tractus solitarii - NIII nucl. oculomotorius - NIV nucl. trochlearis - NVI nucl. abducens - NVII nucl. facialis - NXII nucl. hypoglossus - OI oliva inferior - OS oliva superior - P nucl. posterior thalami - PbL nucl. parabrachialis lateralis - PbM nucl. parabrachialis medialis - PC depedunculus cerebri - Pd nucl. peripeduncularis - Pg nucl. parabigeminalis - Pp nucl. praepositus - PuI nucl. pulvinaris inferior - PuL nucl. pulvinaris lateralis - PuM nucl. pulvinaris medialis - PuO nucl. pulvinaris oralis - Py tractus pyramidalis - Pv nucl. principalis n. trigemini - R Ab nucl. retroambiguus - RL nucl. reticularis lateralis - RTP nucl. reticularis tegmenti pontis - Sf nucl. subfascicularis - SGD substantia grisea dorsalis - SGV substantia grisea ventralis - SN substantia nigra - ST stria terminalis - St subthalamus - TRM tractus retroflexus (Meynert) - TSc tractus spinocerebellaris - Ves nucl. vestibularis - VL nucl. ventralis lateralis - VPI nucl. ventralis posterior inferior - VPL nucl. ventralis posterior lateralis - VPM nucl. ventralis posterior medialis - VR nucl. ventralis raphae - Zi zona incerta - II tractus opticus - VII n. facialis     

Effects of angiotensin-converting enzyme inhibition on arterial,venous and capillary functions in cat skeletal muscle in vivo

The aim of the present study was to analyse quantitatively, on a cat gastrocnemius muscle preparation in vivo, the effects of local angiotensin-converting enzyme (ACE) inhibition by enalaprilat on total regional vascular resistance (tone) and its distribution to the large-bore arterial resistance vessels (>25 μm), the small arterioles (<25 μm) and the veins. Associated effects on capillary pressure and fluid exchange were also studied. Close-arterial infusion of enalaprilat (0.05–0.20 mg kg muscle tissue min^-1) elicited a moderate dilator response in all three consecutive sections of the muscle vascular bed, an increase in capillary pressure and transcapillary fluid filtration. This dilation could be abolished by the selective bradykinin B₂-receptor antagonist Hoe 140 (2 mg kg^-1 min^-1, i.a.), indicating that the dilator mechanism of ACE inhibition was an increased local concentration of bradykinin, and hardly at all a decreased concentration of angiotensin (AT) II. The generalized dilator response to ACE inhibition along the vascular bed suggested a relatively uniform distribution of ACE from artery to vein and this was further supported by the finding that a close-arterial infusion of AT I (0.04–0.32 μg kg^-1 min^-1), which was vasoactive only after conversion to AT II by local ACE, elicited a generalized constrictor response in all three vascular sections. In contrast, infused AT II (0.01–0.16 μg kg^-1 min^-1) constricted almost selectively the large-bore arterial vessels. The specific angiotensin AT₁-receptor antagonist losartan (2 mg kg^-1 min^-1, i.a.) abolished the constrictor response to AT II but did not affect vascular tone under control conditions, indicating that AT II is not involved in the initiation of basal vascular tone in muscle. These results, taken together, indicate that under basal conditions vascular ACE contributes to the local control of vascular tone in skeletal muscle by degrading the endogenous dilator bradykinin, and not by converting AT I into vasoconstrictor AT II.     

Patient safety unit for a hot-film anemometer,used for blood-velocity determination in humans

An inexpensive patient safety unit for a constant temperature hot-film anemometer is described. Both the so-called ‘electrical hazard’ and the thermal risk, which is special for the anemometer, have been eliminated.     

Blood pressure and heart rate during rest-exercise and exercise-rest transitions

Summary The transients of mean arterial blood pressure ( ) and heart rate (f _c) during rest-exercise and exercise-rest transitions have been studied in six healthy sport students. After 5 min of rest in an upright position on a cycle ergometer they exercised for 15 min and remained seated for a further 5 min. The subjects exercised at four different constant intensities (40 W, 80 W, 120 W, 160 W) in random order separated by at least 24 h. The was determined by a noninvasive and continuous method. During the first minute of exercise, three phases of response could be distinguished, with the first two showing no clear relationship to intensity. Phase 1 consisted of simultaneous increases in bothf _c and BP during the first 6 s. In phase 2, decreased whilef _c continued to increase. During phase 3, andf _c approximated constant values or a linear increase. Both parameters showed no comparable intensity-independent reactions during the off-transients. In conclusion, during the first 15 s of rest-exercise transitions there seems to be a fast and uniform cardiovascular drive which overrode other influences onf _c.     

人造血管在治疗四肢大血管损伤中的初步应用

目的作者自1995-2002年采用人造血管移植修复四肢大血管损伤23例，进行回顾性研究人造血管在治疗四肢大血管损伤中的应用。方法23例中男19例，女4例。年龄：21～47岁，平均34．7岁。手术清创和探查后，针对不同的情况选择人造血管移植修复方法。结果采用人造血管移植23例，肢体全部保存，肢体功能恢复较佳。结论四肢大血管损伤救治应快速诊断、快速救治，采用人造血管移植修复四肢主要血管损伤是一种快捷有效的方法。     

Cardiovascular actions of cannabinoids and their generation during shock

Marijuana is a widely abused recreational drug well known for its psychoactive properties. Cannabinoids, the active ingredients of marijuana, elicit their neurobehavioral effects by interacting with the CB₁ cannabinoid receptor subtype, expressed primarily in the brain but also present in some peripheral tissues. A second receptor subtype, the CB₂ receptor, is expressed on cells of the immune system and is thought to be responsible for the immunosuppressant effects of cannabinoids. Recently, endogenous lipidlike substances have been identified, including arachidonyl ethanolamide (anandamide) and 2-arachidonyl glyceride, that bind to cannabinoid receptors and mimic many of the neurobehavioral effects of plant-derived cannabinoids. Both plant-derived cannabinoids and the endogenous ligands have been shown to elicit hypotension and bradycardia via activation of peripherally located CB₁ receptors. Possible underlying mechanisms include presynaptic CB₁ receptor mediated inhibition of norepinephrine release from peripheral sympathetic nerve terminals, and/or direct vasodilation via activation of vascular cannabinoid receptors. The latter may also be the target of endocannabinoids of vascular endothelial origin. Recent studies indicate that a peripheral endogenous cannabinoid system in circulating macrophages and platelets is activated in hemorrhagic and septic shock and may contribute to the hypotension associated with these conditions via activation of vascular cannabinoid receptors. The potential role of this mechanism in human shock conditions is under investigation. Received: 20 May 1998 / Accepted: 24 August 1998     

Inhibition des activités spinales à caractère locomoteur par une modalité particulière de stimulation somatique chez le lapin

Summary In decerebrate rabbit preparations, a gentle pressure exerted on the dorsal skin area can completely suppress the rhythmic, locomotor-like movements or the corresponding nerve discharges which easily develop in such preparations. This inhibition can also be obtained on spinal preparation (and thus does not depend upon supraspinal levels); its maximal effect (i.e. minimal pressure threshold) is located at the lumbar level. It involves tonic receptors belonging both to the skin and to muscle and/or joints. This phenomenon probably plays a role in the so-called hypnotic akinesia which, as is well known, can easily be elicited in rabbits put in dorsal decubitus.

Notes de Remerciements. Travail réalisé avec l'aide d'une subvention du C.N.R.S. (ERA 411), de l'I.N.S.E.R.M. (Contrat 71 11 64) et de la Fondation pour la Recherche médicale française.