Non-cerebellar visual afferents to the vestibular nuclei involving the prepositus hypoglossal complex: An autoradiographic study in the rat

Summary Radioactive amino-acids were injected into the nucleus reticularis tegmenti pontis (NRTP) and the pretectum (PT) in the rat. Beside the labeling of the several nuclei which are known to receive afferents of either the NRTP and/or the PT, monosynaptic projections from these two structures to the prepositus hypoglossal complex (PHN) were demonstrated. Pretectal visual inputs to the vestibular nuclei (VN) may thus be conveyed not only by the classical PT-inferior olive-cerebellar route, but also by two other non-cerebellar ones involving the strong efferent projections of the PHN onto the VN. These last two pathways are strong candidates to account for the residual visual sensitivity of VN neurons after cerebellectomy or inferior olive lesions.Supported by CNRS (A.T.P. 8115)     

Visual influence on postural control in the cat

Experimental Brain Research - The influence of horizontal optokinetic stimulation on posture and postural readjustments, induced by horizontal rotation of a turntable, were studied in the cat....     

Whole-blood pharmacokinetics and metabolic effects of the topical carbonic anhydrase inhibitor dorzolamide

Following a single-dose, open-label, pilot pharmacokinetic study in six subjects, the systemic pharmacokinetics and metabolic effects of dorzolamide after topical ocular administration were investigated in a double-blind, randomised, placebo-controlled study in 12 healthy volunteers. The subjects received a controlled diet on the 5 days before treatment initiation and throughout the study. For 14 days, a bilateral q.i.d. regimen of 3% dorzolamide, consisting of approximately 7.7 g per day (21.3 mol) dorzolamide hydrochloride, or placebo was given. Blood and urine electrolytes and acid-base profiles were measured 1 day prior to treatment and on days 1, 7 and 14 of treatment, and 24-h urine samples were collected daily.Topically applied dorzolamide was slowly taken up in erythrocytes and eliminated with a half life of approximately 120 days. Compared to the pre-study values, no significant treatment effect was observed in either the daily profiles or the 14-day cumulative sodium, potassium and citrate excretions. Two other volunteers given acetazolamide (125 mg q.i.d.) and assessed with the identical set of observations demonstrated marked metabolic changes.In spite of the prolonged and marked inhibition of carbonic anhydrase in red blood cells by dorzolamide, clinically significant metabolic and renal effects were not observed. The ocular tolerability profile was acceptable to all subjects.     

Postmortem coronary artery calcium score in cases of myocardial infarction

International Journal of Legal Medicine - Sudden cardiac death (SCD) related to atherosclerotic coronary artery disease (ACAD) resulting in myocardial infarction is the most prevalent cause of...     

Intra-operative unit recordings in the human dorsal horn with a simplified floating microelectrode

The authors report on the development, for studies in man, of a tungsten, glass-coated, light and simple microelectrode, that is implanted by hand in open operative conditions under the microscope and floats freely with the moving target tissue. This technique has provided limited but nevertheless satisfactory unit activity isolations. Intra-operative unit recordings were obtained from the dorsal horns of 2 spastic and 2 neurogenic pain patients. In the latter, dorsal horn deafferentation hyperactivities after a peripheral and a centro-peripheral lesion were recorded, characterized by a continuous, spontaneous and unalterable high frequency hyperactivity.     

Is it legitimate today to perform large rotations with forceps?

Many authors argue against the practice of large forceps rotations on the basis of a threefold increased neonatal risk compared to the use of forceps for anterior presentations. The experience of the Obstetric Clinic of H?pital Edouard-Herriot in Lyon, of 81 major forceps rotations from a series of more than 10 000 births, is very similar to that of Chiswick in Manchester, based on 86 cases. In nearly one quarter of the neonates, there are discreet, transient neurological signs which disappear within one week and, did not leave any permanent sequelae. It would appear that large rotations should not be totally forbidden, but that their indications have to be carefully considered, especially in cases of foetal distress. An experienced obstetrician can perform these rotations: in experienced hands, they are often straightforward, but in cases of unexpected difficulty (1 case in 10 or 20) it should be immediately abandoned and a caesarian should be performed.     

Studies on the interactions of tobacco leaf and tobacco smoke constituents and monoamine oxidase

Studies have demonstrated that smokers have lower levels of brain monoamine oxidase (MAO) A and B activity and lower MAO-B platelet activity than non-smokers. Recent speculations suggest that in addition to nicotine, tobacco components which are MAO inhibitors, may contribute to some tobacco related psychopharmacological effects. Furthermore, epidemiological evidence indicates a lower incidence of Parkinson’s disease in smokers than in non-smokers. This relationship also might be linked to MAO inhibition. There intriguing observations prompted studies on the effects of tobacco leaf and tobacco smoke constituents on MAO activity. Studies reported here demonstrate that crude hexane tobacco leaf and hexane and aqueous leaf extracts have MAO inhibitory properties. Rat brain mitochondrial MAO-A and MAO-B activity are not altered following continuous 28 day exposure (osmotic minipump) to two tobacco alkaloids, (S)-nicotine or (R,S)-N-methylanatabine. However, earlier studies in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treated parkinsonian C57BL/6 mouse model have provided indirect evidence that the tobacco derived 2,3,6-trimethyl-1,4-naphthoquinone (an MAO-A and B inhibitor) is effective in inhibiting MAO-B in vivo and is neuroprotective. Results reported here from more extensive tobacco leaf extractions provide evidence for three additional compounds with MAO-B inhibitory properties. One contains a chromone system, another a polyunsaturated macrocycle and the third we have identified as farnesylacetone. These findings provide support to the thesis that components of tobacco smoke may be responsible for the inhibition of brain MAO-A and brain and platelet MAO-B in human smokers.