Allopregnanolone produces hyperphagia by reducing neophobia without altering food palatability.

The neurosteroid allopregnanolone may increase feeding by altering food palatability; however, it may also increase feeding by reducing anxiety (neophobia). Moreover, it is unclear whether this induced hyperphagia is selective to safe, palatable foods only. Male rats were injected with allopregnanolone 20 min prior to behavioral testing. The taste reactivity test was used to examine possible shifts in the palatability of a 0.3 M sucrose solution. A lickometer was used to monitor intake and licking of either a sucrose or sucrose-quinine solution. Sucrose palatability was not enhanced; however, allopregnanolone significantly increased sucrose intake and licking on Test Day 1 when the solution was novel, but not on Test Day 2 when the solution was familiar. Sucrose-quinine intake was not enhanced. Allopregnanolone-induced hyperphagia is not a result of altered sucrose palatability, but rather reflects a reduction in the neophobia elicited by a novel solution; an effect that further seems to be selective to safe, palatable foods.     

Aktuelles zum Thema Latex-Allergie

Zusammenfassung Die Typ I-Allergien gegen Latex sind in den vergangenen Jahren zu einem zunehmenden berufsdermatologischen Problem geworden, zumal mindestens 10% der Angestellten im Gesundheitswesen betroffen sind. In der Dermatologischen Klinik der Universit?t Erlangen-Nürnberg stieg die Anzahl der j?hrlich diagnostizierten Patienten mit Latexallergien von 1989 bis 1995 auf das 12fache, wobei der Anteil der schweren, generalisierten Formen der Erkrankung von 10,7% (1989/1990) auf 44% (1994/1995) zunahm. Unter den m?glichen Ausl?sern der Latexallergie (wasserl?sliche Proteine mit Molekulargewichten von 2 bis 200 kD) sind mindestens 5 Hauptproteine mit bereits bekannter Prim?rstruktur zu berücksichtigen. Zus?tzlich gibt es Hinweise für Markerproteine, die in bestimmten Risikogruppen geh?uft zur Ausl?sung spezifischer IgE-Antik?rper führen (z.B. 46 kD-Protein in medizinischen Berufen, 14,6 kD- und 27 kD-Proteine bei Kindern mit Spina bifida). Das Vorkommen von Kreuzreaktionen zwischen Latex und unterschiedlichen Früchten (besonders Avocado, Kiwi, Banane, E?kastanie) bei 60 bis 70% der Latexallergiker ist bei der allergologischen Abkl?rung und Beratung dieser Patienten zu beachten. Wesentliche Aspekte der Prophylaxe umfassen die konsequente Umstellung medizinischer Einrichtungen auf ungepuderte Latexhandschuhe mit niedrigem Proteingehalt. Eine Zusammenstellung von OP- und Untersuchungshandschuhen, welche Angaben über die von uns ermittelten Proteinkonzentrationen (modifizierte Lowry-Methode und Hochdruck-Flüssigkeits-Chromatographie, HPLC) enth?lt, soll ein Leitfaden bei der Auswahl allergologisch geeigneter Handschuhe sein. Eingegangen am 10. August 1996 Angenommen am 21. August 1996     

Responses of Neurons of the Nucleus of the Optic Tract and the Dorsal Terminal Nucleus of the Accessory Optic Tract in the Awake Monkey

The nucleus of the optic tract (NOT) and the dorsal terminal nucleus of the accessory optic tract (DTN) are essential nuclei for the generation of slow-phase eye movements during horizontal optokinetic nystagmus. We recorded from 101 neurons (all directionally selective) in four NOT/DTN of three trained and behaving rhesus monkeys. Neuronal activity increased when stimuli moved ipsiversively with respect to the recording site and decreased below spontaneous activity when stimuli moved contraversively. While the monkey fixated a small spot, some NOT/DTN neurons did not respond at all to the retinal image slip of a whole-field random dot pattern; others showed a monotonic increase of activity to increasing velocities of that stimulus. The velocity range tested was up to 100°/s. During the execution of optokinetic nystagmus, 39 of 73 cells tested showed a velocity-tuned response with an average optimum at 21°/s retinal image slip. Following saccades during optokinetic nystagmus (quick phases), the NOT/DTN neuronal activity briefly attained the level of spontaneous activity, as predicted from the velocity selectivity during optokinetic nystagmus. Immediately upon cessation of optokinetic stimulation in the preferred direction, NOT/DTN activity returned to the spontaneous level and did not reflect the ongoing optokinetic afternystagmus in darkness. Most NOT/DTN neurons displayed direction selectivity also during smooth pursuit. Twenty-one of 50 cells tested (42%) always responded to the retinal slip of the target (target velocity cells), 16 cells (32%) responded to the retinal slip of the background (background velocity cells), and 13 cells (26%) did not respond at all during smooth pursuit. We conclude from our results that the NOT/DTN is an essential structure for the processing of the direction and speed of retinal image slip. This information is then used for the generation and maintenance of slow eye movements, preferentially during horizontal optokinetic nystagmus but also during pursuit eye movements.     

Noninvasive measurement of cell volume changes by negative staining

To maintain the intracellular concentration of ions and small molecules on osmotic challenges, nature has developed highly sophisticated transport systems for regulating water and ion content. An ideal measurement technique for volume changes of cells during osmotic challenges has to fulfil two requirements: it has to be osmotically inert, and it should allow online monitoring of cell volume changes. Here, a simple fluorescence microscopy-based approach is presented. Using fluorescein as a negative stain, it is possible to monitor cell volume changes without affecting the functionality of cell membranes and cell osmolarity. Measurement of Madine-Darby canine kidney (MDCK) cells after hypo- and hyperosmotic challenges reveals the main advantages of this approach: besides providing precise and reproducible quantitative data on reversible cell volume changes, the viability of the cells can be assessed directly by the appearance of stain in the cytoplasm. This becomes evident especially after hypo-osmotic challenge of glutaraldehyde-treated cells, which become leaky after fixation, followed by a massive volume change. This new approach represents a very sensitive measurement technique for cell volume changes resulting from water or ion flux, and thus seems to be an ideal tool for studying cell volume regulatory processes.     

Influence of visually guided tracking arm movements on single cell activity in area MT

The behavioral relevance of neuronal activity in primate area MT for motion perception and control of visually guided eye movements is well documented. The projections of area MT comprise connections to subcortical structures and to the parietal network, both of which play a role in visuospatial transformation for guiding eyes and hands. Here, we have investigated, whether area MT is involved in the network needed to control visually guided arm movements. Our results show that half of the neurons tested significantly modulated their activity during visually guided arm movements. We conclude that the main reason for the neuronal modulation is not the arm movement per se, but the use of information from MT for visual feedback in the tracking movement. Moreover, control experiments show that attentional effects cannot solely cause the neuronal modulation. Thus, our study provides strong evidence that area MT is involved in processing visual information for visually guided manual tracking movements.     

Relationship between body fat mass,carbohydrate tolerance and iri response during glucose infusion in subjects with early diabetes

Summary We have studied the interrelationship of total body fat mass, carbohydrate tolerance and IRI response in 17 non-obese and obese subjects, who were suspected of having early diabetes. We carried out an i.v. glucose infusion test consisting of a priming injection of 0.33 g/kg followed by constant glucose infusion of 12 mg/kg/min in all persons. Total body fat mass was estimated by the tritium dilution method. There was a positive correlation of body fat mass, fasting glucose concentration and blood glucose concentration at 150 min as well as a strong correlation between body fat mass and BG area 60–120 min as parameters of carbohydrate tolerance in all subjects, i.e. the degree of carbohydrate intolerance was directly related to the quantity of total body fat mass. A similar correlation was found when the non-obese and obese groups were analyzed separately. In neither group did total body fat mass correlate with parameters of IRI response. In obese subjects with pathological carbohydrate tolerance, however, a positive correlation of basal IRI concentration and total body fat mass was found. Furthermore, a close relation between basal IRI level and parameters of carbohydrate tolerance could be demonstrated in obese subjects. The present study failed to demonstrate any correlation of parameters of carbohydrate tolerance and glucose-induced IRI response in either group. Thus, the significant relationship between body fat mass and degree of carbohydrate intolerance indicates that total body fat mass plays an important role in the disturbance of blood glucose homeostasis in early diabetes with and without obesity. Investigation performed within the medical research project ‘Diabetes mellitus and disturbances of lipid metabolism’, Ministry of Health, GDR.     

Effect of digoxin on coronary blood flow and myocardial oxygen consumption in patients with chronic coronary artery disease

In 10 patients with chronic coronary artery disease and without clinical evidence of congestive heart failure, the effects of 1.0 mg of digoxin intravenously on systemic hemodynamics, coronary blood flow, myocardial oxygen consumption and myocardial lactate extraction were studied both at rest and during atrial pacing. Atrial stimulation at a rate just below the threshold for angina led to a significant decrease in left ventricular enddiastolic pressure, from 10.6 ± 1.6 to 7.1 ± 0.8 mm Hg, associated with a significant decrease in left ventricular stroke work index per beat, from 76.7 ± 5.11 to 40.3 ± 4.01 g-m/m². After digoxin, nearly identical results in stroke work index could be observed at rest and during stimulation (75.2 ± 6.74 and 44.1 ± 5.92, respectively). However, left ventricular enddiastolic pressure decreased significantly before and during atrial stimulation (8.1 ± 1.29 and 4.7 ± 1.09 mm Hg, respectively). Cardiac index decreased from 3.08 ± 0.20 to 2.73 ±0.17 liters/min per m² at rest but during pacing it no longer differed before and after digoxin (3.17 ± 0.22 and 3.10 ± 0.20 liters/min per m², respectively). Myocardial oxygen consumption and lactate extraction remained unchanged after digoxin both at rest and during atrial pacing.It is concluded that some deficiency in left ventricular function is present in patients with chronic coronary artery disease even without clinical evidence of congestive heart failure. Digoxin improves left ventricular performance at rest and during stress conditions. An expected increase in myocardial oxygen consumption due to enhanced contractility is completely counterbalanced, probably by a decrease in left ventricular volume after digoxin.