Ret, GFRalpha-1, GFRalpha-2 and GFRalpha-3 receptors in the human hippocampus and fascia dentata

The immunohistochemical occurrence and localization of the receptor components of the glial cell line-derived neurotrophic factor (GDNF) family ligands, the Ret receptor tyrosine kinase and GDNF family receptor (GFR) alpha-1 to -3, is described in the human post-mortem hippocampal formation at pre- and full-term newborn, and adult age. Two different antibodies for each of the four-receptor molecules were used. Western blot analysis indicates that the availability of GFRalpha receptor proteins may vary with age and post-mortem delay. The immunohistochemical detectability of GFRalpha-1, GFRalpha-2, GFRalpha-3 and Ret receptor molecules is shown in the rat up to 72 h post-mortem. In the human specimens, labelled neuronal perikarya were detectable for each receptor protein at all examined ages, with prevalent localization in the pyramidal layer of the Ammon's horn and hilus and granular layer of the fascia dentata. In the adult subjects, abundant punctate-like structures were also present. Labelled glial elements were identifiable. Comparison of the pattern of immunoreactive elements among young and adult subjects suggests that the intracellular distribution of the GDNF family ligands may vary between pre- and perinatal life and adult age. The results obtained suggest the involvement of the Ret and GFRalpha receptors signalling in processes subserving both the organization of this cortical region during development and the functional activity and maintenance of the mature hippocampal neurons.     

Palatal taste buds in man: Topographical arrangement in islands of keratinized epithelium

Summary In an attempt to find and reconstruct the exact anatomical correlate of taste sensitivity in the human soft palate, a novel approach was used to examine the mucosal surface in conjunction with serial tissue sectioning. Six human subjects, 15 to 29 years of age, 3 females and 3 males, served to take precision impressions of the hard and the anterior soft palate, using non-commercial trays and a self-curing resin. From these impressions, replicas were cast in Epon and subsequently sputtercoated with gold and examined in a scanning electron microscope. In addition, one biopsy was taken from one of the volunteers, in an area including taste bud-suspicious elements. It was found that the anterior soft palate mucosa included 10 to 30, oval to round, site-exotic islands, about 0.2–0.6 mm in diameter, which were covered by a thin, keratinizing stratified squamous epithelium. These islands occurred mainly in an area located in the central part of the soft palate, immediately posterior to the hard/soft palate boundary. The keratinizing epithelium of such islands carried four to seven taste buds which were lacking elsewhere. These islands were formed by a large, mushroom-like connective tissue papilla penetrating most of the site-specific mucosal epithelium, with its cover of keratinizing epithelium, forming sharp external and internal cell-to-cell borderlines with the surrounding, non-keratinizing stratified squamous epithelium. These findings are discussed in relation to induction phenomena necessary to form such islands, and to the variable taste sensitivity detected clinically in this region.     

Muskelspindeln und sensible Endkörper in Harnröhrenschließmuskel

Summary Neurohistological investigations of the external urethral sphincter in a 2-day-old female baby proved the up till now not verified existence of muscle spindles. These are rare in number, in the majority containing only one intrafusal fiber. Beside of the spindles encapsulated nerve endings, situated in the interstitial tissue and marginal parts of the muscle fascicles, were detected.

     

Habituation of vasodilatation in the calf elicited by repeated sensory stimulation in man

Summary In 28 subjects the cardiovascular response to repeated stimulation was monitored during six daily sessions. Calf blood flow was measured with mercury-in-silastic venous occlusion plethysmography, blood pressure with electronic sphygmomanometer. The stimuli used were: 1 kHz sound of 90 dB and 100 dB intensity and immersion of one foot for 60 s in water at 4° C. Initially sounds induced large vasodilatation in the calf, immersion of one foot in the water induced in the contralateral calf vasodilatation in one group and vasoconstriction in another group of subjects. The blood pressure changes were less prominent and less consistent. After the first session of repeated stimulation the vascular response during the second session was significantly diminished. The reduction of the vasodilatation was the most rapid. During the remaining 5 days the responses were suppressed. It has been established that in the patients in the initial stage of hypertension the ability to habituate vascular response is impaired (Zbroyna and Krebbel 1985). It is therefore suggested that the test of the ability for long-term vascular habituation could be used as a supplementary diagnostic test.     

EEG and blood level of the potential antidepressant paroxetine after a single oral dose to normal volunteers

The quantitative electroencephalogram (EEG) and plasma concentration of the antidepressant paroxetine were monitored in five normal volunteers after a single oral dose of 70 mg paroxetine and placebo. Peak plasma concentration occurred 4–6 h post-dose. Placebo had little effect on the EEG but the effects of paroxetine were statistically significant at 6 h post-dose. The EEG changes after treatment consisted of a decrease in delta and theta activity (< 8 Hz) and increase in beta activity (>12 Hz). These changes were still evident 72 h after treatment. The EEG profile obtained with 70 mg paroxetine is similar to that reported for other antidepressant 5-HT uptake inhibitors, but dissimilar to the classical, sedative antidepressants.     

Comparison of several methods for the determination of arsenic compounds in water and in urine

Summary Several arsenic species (inorganic tri- or pentavalent arsenic, mono-and dimethylated arsonic acids) can be determined in water samples by electrothermal atomic absorption spectrometry after appropriate acidification procedures (concentrated HCl or a mixture HCl/HClO₄/HBr) and extraction by toluene in the presence or absence of KI; the determination of aromatic derivatives and of arsenic thiol complexes needs a wet or dry ashing step. The procedures for water analysis are not directly applicable to urine samples; in the best conditions, total inorganic plus 85% on the average of the methylated arsenicals present in urine are measured after acidification with concentrated HCl and extraction by toluene in the presence of KI. Total arsenic content (including arsenic from marine origin) is measured only after a drastic mineralization step like MgO treatment at 600°C. The results obtained by the electrothermal atomic absorption technique and those obtained by neutron activation analysis are in excellent agreement.When the presence of arsenic of marine origin is suspected in urine, the analysis of inorganic arsenic and its metabolites is preferably performed by an arsine generation technique. The sum of inorganic arsenic and of its mono and dimethylated derivatives determined by such a technique is identical with the results obtained by electrothermal atomic absorption spectrometry after complete mineralization of the samples as long as no arsenic from marine origin is present.After oral ingestion of As₂O₃ by man, the urinary excretion of inorganic arsenic and its metabolites is important and rapid (approximately 60% are eliminated by the oral route with a half life of 30 h).While the excretion occurs in the form of inorganic species during the first hours following the ingestion, a methylating process is rapidly triggered and leads to a preponderant excretion of dimethylarsinic acid 1 day after ingestion. In the case of ingestion of seafood containing arsenic, the urinary excretion occurs at a higher rate (half life 18 h) apparently without transformation.The absence of interference of arsenic from marine origin and the capacity of measuring separately inorganic arsenic and its main urinary metabolites makes the arsine generation technique the best suited for the monitoring of workers exposed to inorganic arsenic. However, since the technique may sometimes be too elaborate and time-consuming for routine work, the biological monitoring of workers can be performed by determining total arsenic concentration in urine after mineralization with MgO. Samples with high arsenic content are then re-analyzed to distinguish between occupational exposure and ingestion of the organic arsenic present in marine organisms. This is carried out either by the arsine generation method or, if this technique is not available, by a direct extraction procedure in the presence of KI of a sample acidified with HCI. With the latter procedure, 85% of the methylated arsenic is measured on average without interference of arsenic from marine origin.     

Fast head tilt has only a minor effect on quick compensatory reactions during the regulation of stance and gait

Summary Sudden tilts of the head to the front or rear were induced during stance, balancing, gait and during perturbations of gait. The most prominent response in the leg muscle electromyogram (e.m.g.) to head tilt occurred in the tibialis anterior muscle (latency about 55 ms) following a backward tilt induced during balancing. During stance and gait, the e.m.g. activity related to head tilt was only a minor component of the leg muscle activity normally occurring during gait. When the head tilt was induced shortly after a perturbation of gait (treadmill acceleration impulse), the compensatory reaction in the leg muscles did not significantly differ from that seen after the gait perturbation alone. In addition, the rate of acceleration of the head was tested against the compensatory e.m.g. responses: No correlation of influence could be discerned. The results indicate that sudden head tilts and the resulting head acceleration have little influence on the e.m.g. patterns that occur during gait and perturbations of gait. It is assumed that these patterns are regulated by central programs, and that the compensation for leg perturbation is achieved mainly by spinal reflex mechanisms. It is discussed whether the lack of head tilt responses is the result of an antagonistic vestibularneck interaction, or whether it indicates a reduced effectiveness of vestibulo- and cervico-spinal reflexes during gait.     

Stable T wave effects during improvement of heart rate control with biofeedback.

Under audiovisual heart rate feedback the differences between attempts to accelerate and decelerate improved with practice. Simultaneously, T wave amplitude was reduced during acceleratory trials and remained constant during deceleratory trials. The T wave difference between acceleratory and deceleratory trials, unlike the heart rate differences, did not improve with trial repetition. It was concluded that the improvement in heart rate control was parasympathetically mediated.     

The significance of the inflammatory reactions for the development of clinical signs in multiple sclerosis and acute experimental autoimmune encephalomyelitis as assessed by means of the spontaneous chemiluminescence activity of peripheral blood monocytes

We found that the course of the chemiluminescence activity (CL-A) of peripheral blood monocytes of Lewis rats with acute experimental autoimmune encephalomyelitis (EAE) correlates well with the clinical course of this autoimmune disease and that only a reduction in T helper cells caused a reduction in CL-A. However, in multiple sclerosis (MS) patients the CL-A increased when clinical improvement started. The serum of these patients contained at least two stimulatory substances. More than 50% of the stimulatory effect could be blocked by antibodies to interferon-γ.     

A comparative study of visual,auditory and somatosensory EEG responses in man

Summary The EEG responses (evoked potentials) to light flashes, clicks and electric stimulation (shocks) of the median nerve, recorded in the midline occipital region in the same group of 20 normal subjects, were studied. The average responses of the whole group as well as the individual average responses of separate subjects to stimuli of all three modalities present the same waves. There are differences in latency and amplitude but no significant differences in the shape. The auditory and somatosensory responses are less prominent and nearly suppressed with higher stimulus frequencies. The origin and possible physiological significance of the described responses is discussed. Their non-specific character is suggested.