Design of a multichannel solid-state recorder and its application to temperature measurement

The development of a multichannel unconstrained memory system for monitoring physiological information is described. The system comprises a portable recorder, worn by the subject, to detect and store data in memory and a readout unit for transferring the data to a microcomputer. Using the microcomputer, the physiological data are displayed, retrieved and analysed. The portable recorder consists of a memory control unit, an instrumentation unit, an LCD timer and batteries. In the memory-control unit the data are transferred to EPROM (erasable programmable read-only memory), which is a nonvolatile memory. This memory, removed from the protable recorder, can be delivered to the laboratory and its contents analysed without interrupting the field experiment. In connection with the instrumentation unit, an 8-channel skin thermometer was designed and tested. It was accurate to within ±0.08°C compared with a standard thermometer.     

Transformationsvorgänge in der Frühphase der Entstehung des arteriellen Thrombus

Zusammenfassung In unserer ultrastrukturell durchgeführten Studie wurden Thromben in der Arteria carotis communis von Ratten nach einer zuerst von Meng und Seuter (1977) beschriebenen Methode experimentell erzeugt. Induktion der Thrombusbildung erfolgte in vivo durch Unterkühlung eines kleinen Gefäßabschnittes unter konstantem Druck und kurzfristiger Stase. Eine Änderung des Blutflusses wurde durch einen Silberclip erzeugt. Die geschädigten Gefäßsegmente einschließlich der Thromben bzw. deren Vorstufen wurden nach 5, 10, 30 min und 1, 4 und 24 h nach der Thrombosestimulation entnommen und fixiert. Semidünnschnitte und Ultradünnschnitte wurden im Licht- und Elektronenmikroskop morphologisch untersucht.Den Transformationsvorgängen im Thrombus konnten exakte Zeitmarken zugeordnet werden. Als wichtigstes histopathologisches Merkmal für die Altersbestimmung arterieller Thromben in der Frühphase der Thrombogenese werteten wir die Querstreifung der Fibrinfasern. Diese trat bereits nach 5 min auf, erreichte nach 30 min ein Maximum und verschwand als Folge der zunehmenden Verdichtung der Fasern nach einer Stunde. Nach 4 h sahen wir eine weitgehende Retraktion der Fibrinfasern, die nach 24 h zur Bildung des Fibrinfasergerüstes mit Einmauerung korpuskulärer Elemente führte. Überdies beobachteten wir zwei Thrombocytenaggregate von differenter Struktur. Wir unterschieden ein fibrinarmes Aggregat, in dem die Thrombocyten dichtgepackt und pseudopodienreich erschienen von einem thrombocytenarmen Aggregat mit reichlich interponierten Fibrinfasern. Die nach 5 min im Zentrum des Thrombus auftretende Agglutination der Plättchen im thrombocytenreichen Aggregat führte nach 30 min zur Thrombocytorrhexis und ergab daher einen weiteren Anhalt für die Altersbestimmung des Coagulum. Der entstandene celluläre Abraum stimulierte mononucleäre Zellen und Leukocyten zur Phagocytose. Daher sahen wir nach 4 h eine massive Leukocytose als Folge der frühen Thrombocytorrhexis. Nach 24 h war die viscöse Metamorphose im fibrinreichen und fibrinararmen Aggregat weitgehend abgeschlossen. Innerhalb des beobachteten Zeitraumes entstand eine Verballung und bizarre Deformierung der Erythrocyten, die bereits nach 5 min vom Zentrum des Thrombus ausging und nach 24 h die Peripherie erreichte. Eine Hämolyse der Erythrocyten war nach dieser Zeit noch nicht erkennbar.

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Evolution in the early changes in the establishment of arterial thrombi

Summary Ultrastructural studies of thrombi were carried out on the common carotid artery of the rat using a method first described by Meng and Seuter (1977). Induction of thrombus formation in vivo was achieved by chilling of a small vessel segment under constant pressure and short-termed stasis. Disturbance of the blood flow was produced by a silver clip. The damaged vessel segments with the thrombotic deposits were removed 5, 10, 30 min, and 1, 4 and 24 h after stimulation of thrombosis. They were fixed and samples were studied as semithin and ultrathin sections morphologically using light and electronmicroscopy.In the maturation of thrombi exact time intervals could be determined. The most important histopathological characteristics for age determination of arterial thrombi in the early period of thrombogenesis were the cross stripes of fibrin fibres. They appeared after 5 min, reaching a maximum after 10 min and disappeared as a result of increasing fibre density after 1 h. After 4 h nearly complete retraction of fibrin fibres was found which led after 24 h to the formation of a corresponding frame walling in the corpuscular elements. Apart from this aggregation of thrombocytes, which were of two different types were observed, one showing a fibrin-poor aggregate in which the thrombocytes appeared densely packed with numerous pseudopods, and one showing a thrombocyte poor aggregate with abundant interposed fibrin fibres. Agglutination of platelets which occurred in the thrombocyte-rich aggregate in the centre of the thrombus after 5 min led to thrombocytorrhexis after 30 min. The resulting cellular waste stimulated phagocytosis by mononuclear cells and leucocytes. Because of this a massive leucocytosis was found as a result of the early thrombocytorrhexis after 4 h. After 24 h the viscous metamorphosis in the fibrin-rich and in the fibrin-poor aggregate was largely completed. Clumping and deformation of erythrocytes was observed in the middle of the thrombus after 5 min and at the periphery of the thrombus after 24 h. Haemolysis did not occur within this time interval.

Frau Antoni, Herrn Ing. grad. Derks und Herrn Rieger sei für ausgezeichnete technische Assistenz herzlichst gedankt.     

Metabolism of phenylalanine in liver diseases

Summary 1. Amethod for the determination of phenylalaninehydroxylase-activity in needle biopsy material of human liver was developed and tested. The kinetic data of the enzyme were determined. TheK _m for the substrate phenylalanine is 1,32 mM, for the cofactor 0,08 mM.2. The activity of phenylalaninehydroxylase was determined in biopsies from normal liver, liver cirrhosis, alcoholic hepatitis and other liver diseases. In all liver diseases the enzyme activity related to wet weight or DNA is reduced. The capacity for the hydroxylation of phenylalanine (of a cirrhotic liver) amounts to about 20% of normal liver.3. After an oral load with L-phenylalanine (100 mg/kg) the phenylalanine- and tyrosine-concentration in blood plasma was followed for 5 hours. Patients with liver cirrhosis or acute hepatitis show significant higher concentrations of phenylalanine, and significant lower concentrations of tyrosine than normal persons.4. From the decline of phenylalanine-concentration after the maximum the phenylalanine-elimination rate and from the increase of tyrosine concentration the tyrosine-production rate were calculated. Between phenylalanine-elimination rate and tyrosine-production rate a strong correlation exists. In patients with cirrhosis or acute hepatitis significantly reduced phenylalanine-elimination rate and tyrosine production rate were found compared with persons without liver disease. Patients with alcoholi hepatitis show no significant difference compared with normal persons.5. There is no correlation between the activity of phenylalaninehydroxylase in liver tissue and phenylalanine-elimination rate and tyrosine-production rate, respectively, calculated from the concentration of this amino acids in serum after a phenylalanine load.6. We conclude from these findings that the increased serum concentration of phenylalanine in some liver diseases, especially liver cirrhosis, can partly be explained by the diminished metabolism of phenylalanine in the liver. Portocaval shunts probably contribute to the elevated level of phenylalanine in serum.Mit Unterstützung der Deutschen Forschungsgemeinschaft und der Sandoz-Stiftung für medizinische Forschung     

Kinaesthetic role of muscle afferents in man,studied by tendon vibration and microneurography

Summary The characteristics of vibration-induced illusory joint movements were studied in healthy human subjects. Unseen by the subject, constant frequency vibration trains applied to the distal tendon of the Triceps or Biceps induced an almost constant velocity illusory movement of the elbow whose direction corresponded to that of a joint rotation stretching the vibrated muscle. Vibration trains of the same duration and frequency applied alternatively to the Biceps and Triceps evoked alternating flexion-extension illusory movements.During successive application of vibration trains at frequencies from 10 to 120 Hz, the perceived velocity of the illusory movements increased progressively from 10 to 70–80 Hz, then decreased from 80 to 120 Hz. The maximal perceived velocity was three times higher during alternating vibration of the Biceps and Triceps than during single muscle stimulation.Unit activity from 15 muscle spindle primary endings and five secondary endings located in Tibialis anterior and Extensor digitorum longus muscles were recorded using microneurography in order to study their responses to tendon vibration and passive and active movements of the ankle.Primary endings were all activated by low amplitude tendon vibration (0.2–0.5 mm) previously used to induce illusory movements of the elbow. The discharge of some was phase-locked with the vibration cycle up to 120 Hz, while others responded one-to-one to the vibration cycle up to 30–50 Hz, then fired in a sub-harmonic manner at higher frequencies. Secondary endings were much less sensitive to low amplitude tendon vibration.Primary and secondary ending responses to ramp and sinusoïdal movements of the ankle joint were compared. During the movement, the primary ending discharge frequency was almost constant, while the secondary ending activity progressively increased. During ankle movements the primary ending discharge appeared mainly related to velocity, while some secondary activities seemed related to both movement velocity and joint angle position.Muscle spindle sensory ending responses to active and passive ankle movements stretching the receptor-bearing muscle (plantar flexion) were qualitatively and quantitatively similar. During passive reverse movements (dorsiflexion) most of the sensory endings stopped firing when their muscle shortened. Active muscle shortening (isotonic contraction) modulated differently the muscle spindle sensory ending discharge, which could stop completely, decrease or some times increase during active ankle dorsiflexion. During isometric contraction most of the muscle spindle sensory endings were activated.The characteristics of the vibration-induced illusory movements and the muscle spindle responses to tendon vibration and to active and passive joint movements strengthened the possibility of the contribution of primary endings to kinaesthesia, as suggested by several previous works. Moreover, the present results led us to attribute to proprioception in the muscle stretched during joint movement a predominant, but not exclusive, role in this kind of perception.     

Enhanced visual spatial attention ipsilateral to rTMS-induced 'virtual lesions' of human parietal cortex

The breakdown of attentional mechanisms after brain damage can have drastic behavioral consequences, as in patients suffering from spatial neglect. While much research has concentrated on impaired attention to targets contralateral to sites of brain damage, here we report the ipsilateral enhancement of visual attention after repetitive transcranial magnetic stimulation (rTMS) of parietal cortex at parameters known to reduce cortical excitability. Normal healthy subjects received rTMS (1 Hz, 10 mins) over right or left parietal cortex. Subsequently, detection of visual stimuli contralateral to the stimulated hemisphere was consistently impaired when stimuli were also present in the opposite hemifield, mirroring the extinction phenomenon commonly observed in neglect patients. Additionally, subjects' attention to ipsilateral targets improved significantly over normal levels. These results underline the potential of focal brain dysfunction to produce behavioral improvement and give experimental support to models of interhemispheric competition in the distributed brain network for spatial attention.     

Studies on cortical field potentials recorded during learning processes of visually initiated hand movements in monkeys

Summary A monkey was trained to lift a lever by wrist extension in response to a light stimulus. During the learning process of the task over several months, field potentials related not only to the task performance but also to substitution and stimulation experiments were recorded with chronically implanted electrodes on the surface and at a depth of 2.5–3.0 mm in the prefrontal, premotor, motor and prestriate cortices. In the substitution experiment, an examiner lifted a lever for the monkey so that it was watching the light and rewarded without the hand movement. In the stimulation experiment, the same light stimulus was simply delivered to the monkey. In a naive monkey which lifted the lever independently of the stimulus, stimulus-locked potentials were evoked by the task experiment in those cortices except the motor cortex, but none was elicited by the substitution or stimulation experiment. In a welltrained monkey, the substitution and stimulation experiments induced almost the same potentials as those prior to the task movement in respective cortices except the motor cortex, in which the component of cerebellar-induced premovement potential was not observed during the substitution and stimulation experiments. At an intermediate stage of learning, the situation was intermediate between the naive and well-trained stages and most premovement potentials except those in the motor cortex were elicited by the substitution experiment in reduced sizes, but nothing by the stimulation experiment.The present study suggests that the neuronal circuits for the operantly conditioned movement are functionally organized and gradually consolidated in the learning process, and that the consolidation is made earlier for the circuit involving association and premotor cortices than the circuit including the motor cortex in the process. The circuit to the motor cortex via the cerebro-cerebellar interconnection is recruited only on the execution of movement.     

Individual T cells hold unexpected clues to the nature of anergy and memory

The primary interest of our laboratory is understanding how the signals that a T cell receives influence its behavior during an immune response. Recently, we have focused our attention on the examination of T cell responses at an individual cell level. This article outlines our approach, presents our initial findings, and discusses the implications of these findings relative to our current models of T cell activation.     

Die Kultur von Tuberkelbacillen aus Larynxabstrichen

Ohne Zusammenfassung