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Biomedical subjects

J Durand

Publications and source records attributed to J Durand.

At least 91 records · Page 5Linked to original sources
PubMed1989

Effects of diphenylamine-2-carboxylate on sodium and chloride transport across bovine tracheal epithelium: studies in monolayers and in the native tissue.

1. The short-circuit current (I0) across monolayers of bovine tracheal epithelial cells is the sum of Na+ absorption and Cl- secretion. 2. Diphenylamine-2-carboxylate (DPC), added to the mucosal side of the native tissue or monolayers induced a rapid, dose-dependent and fully reversible reduction in I0, which reached zero with 3 mM DPC. 3. The blocking effect of DPC was examined during incubation (1) in standard, (2) in Cl(-)-free and (3) in Na+-free solution. Dose response curves revealed that the IC50 was not altered following ion substitution: it was approximately 0.7 mM DPC. 4. Thus, in bovine tracheal epithelium, DPC was an effective blocking agent of both Na+ and Cl- transport.

Amiloride↗
PubMed1989

Diphenylamine-2-carboxylate stimulates sodium ion transport in frog skin epithelium.

1. Diphenylamine-2-carboxylate (DPC), added to the mucosal side of the frog skin, increased reversibly the short-circuit current (I0), even in SO2-(4) Ringer. Amiloride blocked this effect. 2. The maximal stimulation was 140% of the control value and the EC50 was 0.26 mM DPC. 3. The stimulatory effect of DPC was additive to that of oxytocin. 4. The dose-response curves for amiloride determined in the absence and in the presence of 1 mM DPC showed an IC50 of 1.0 microM and 0.8 microM amiloride, respectively. 5. Thus DPC, a blocker of Cl- channels in various Cl-transporting epithelia, exerts a stimulatory effect on the amiloride-sensitive Na+ transport in frog skin.

Amiloride↗
PubMed1989

Intracellular study of oculomotor neurons in the rat.

The electrical and morphological properties of oculomotor neurons were investigated in the rat with intracellular recordings and intracellular horseradish peroxidase staining. Motoneurons were identified by their antidromic response to electrical stimulation of the ipsilateral medial rectus muscle. The antidromic action potential was followed by a delayed depolarization and an afterhyperpolarization of 20-50 ms in duration. The whole neuron input resistance calculated from intensity/voltage curves, was found between 4 and 15 M omega. Passive membrane properties showed the existence of anomalous rectifications. Motoneurons were studied on the basis of their responses to long-lasting depolarizing current pulses. The intensity/frequency curves suggest the existence of two ranges of discharges. The average intensity frequency slope during the steady state was 33 imp/s/nA. Ten oculomotor neurons were intracellularly labelled with horseradish peroxidase and fully reconstructed. The soma (23-33 microns in diameter) gave off five-eight primary dendrites which could extend over 600-800 microns from the soma. The oculomotor neurons were principally oriented in the sagittal plane. The soma size of oculomotor neurons was not related to the size of proximal tree. According to our observations, the morphological features of motoneurons did not allow us to predict the whole neuron input resistance. The comparison between in vivo and in vitro studies of oculomotor neurons revealed one major difference in the input resistance of the whole neuron which was three times higher in slices.

Action Potentials↗
PubMed1989

Design and preliminary evaluation of a portable instrument for assisting physiotherapists and occupational therapists in the rehabilitation of the hand.

This paper describes a portable instrument designed to monitor progress accomplished by patients participating in a hand rehabilitation program. The instrument is driven by a microcontroller and features signal conditioning circuits to measure and record the strength and duration of hand contractions. An alphanumeric display provides the patient with performance indications to allow biofeedback reinforcement, and clear instructions on how to perform the prescribed exercises. Exercise data acquired by the portable instrument can be transferred to a host computer for analysis and archival storage. Results of a preliminary clinical evaluation in 14 patients are presented.

Biofeedback, Psychology↗
PubMed1988

Muscular venous blood metabolites during rhythmic forearm exercise while breathing air or normoxic helium and argon gas mixtures.

The effects of breathing normoxic helium or argon gas mixture on the local muscular metabolism during exercise were compared to those of room air in four healthy subjects. For this purpose, PO2, PCO2, pH, the concentrations of lactate (LA), glucose (Gl) haemoglobin (Hb) and K+ and osmolarity were repeatedly measured in efferent muscular venous blood during 12 min of rhythmic forearm exercise and 16 min of recovery. The time courses and magnitude of the changes in PCO2, pH, [Gl], [Hb], [K+] and osmolarity during exercise and recovery were similar for breathing both the helium and argon gas mixtures. The main finding was that during exercise, the [LA] curve reached a peak value significantly higher by 25% under normoxic helium than under room air or normoxic argon breathing. This rise in [LA] was accompanied by a slight reduction in muscular venous PO2, too small to signify muscular hypoxia. The possibility that this decline in PO2 might be due to a shift in muscular metabolism towards lipid oxidation was confirmed by the lower muscular respiratory quotient observed during helium breathing. However, such a shift did not explain why [LA] rose during this breathing. The probable explanation is that helium facilitates LA diffusion out of the myocytes.

Adult↗
PubMed1988

Coupling of active sodium transport to oxidative metabolism in the rabbit distal colon.

1. Active transepithelial Na+ transport (Ji) and O2 consumption (Jr) were measured simultaneously in rabbit distal colon, under standard (control) incubation conditions and after various manoeuvres, known to inhibit Na+ transport. 2. The determination of Jr was complicated by the presence of fluctuations of the PO2 in the incubation solution and by spontaneous variations of the tissue respiration, which usually declined slowly with time. 3. The control values of Ji and Jr after 2 h incubation were 55 +/- 4 nequiv min-1 cm-2 and 16 +/- 1 nmol O2 min-1 cm-2, respectively (n = 44). The electrical resistance was 386 +/- 23 omega cm2; it was stable over 6 h. 4. Ji was reduced to a very low level with either amiloride, ouabain or Na+ substitution with choline. In all instances, Jr decreased concomitantly by 15-30%. 5. A plot of the change in Jr versus the change in Ji gave a straight line for all situations, i.e. for the spontaneous decline of Na+ transport and respiration and for the effects of the inhibitors. 6. The linearity between Jr and Ji allows for the determination of a stoichiometric ratio. It is of similar magnitude, when calculated either with the data of spontaneous variations or with those obtained by the action of any inhibitor tested. It is 15-20 Na+ ions per O2 molecule, a value close to that reported previously for amphibian epithelia and also close to the maximum theoretical value of 18 Na+ ions per O2 molecule.

Amiloride↗
PubMed1988

[Physiology of the tracheal epithelium].

The mucosa that lines the airways is covered with a fluid film forming a hypophase between mucus and cell surface. To study the function of this epithelium aims at describing the mechanisms by which fluid is normally produced. Another goal to be pursued consists in looking for the origin of pathological situations, such as cystic fibrosis, in which the functioning of epithelial cell is altered. The elucidation of transport mechanisms present in the apical and in the basolateral membrane results in a conceptual model that illustrates the asymmetrical functioning of epithelial cells. Recent discoveries enlarge our understanding of membrane transport processes; in particular, a concerted, reciprocal regulation of the activity of both membranes was shown to be exerted via the intracellular composition. The tracheal epithelium absorbs Na+ and secretes Cl-. These two transports are active and electrogenic; their sum corresponds approximately to the short-circuit current measured in vitro. Na+ absorption is sensitive to amiloride from the luminal side and also to ouabain added to the serosal compartment. The process is a primary active transport, analogous to that found in amphibian epithelia or in mammalian colon. Cl- secretion is abolished by furosemide (or bumetanide), by ouabain or by Na+ suppression in the serosal incubation solution. The mechanism is a secondary active transport: Cl- influx across the basolateral membrane is coupled to Na+ (probably through Na+, K+, Cl- symport); energy is dissipated by the Na+-K+-ATPase localised in the basolateral membrane. Thus, Na+ is recirculated across that membrane by the pump activity, which maintains a favorable gradient for influx via the symport. Cl- efflux takes place by diffusion through the luminal membrane. This model applies to other epithelia in which Na+-coupled Cl- secretion was shown to take place. It is confirmed by isotopic fluxes measurements and by electrophysiologic properties of the apical and the basolateral membrane. Various agents are known to influence ion transports. In particular Cl- secretion is stimulated by substances that increase the intracellular concentration of cyclic AMP. At the membrane level, the number of active Cl- channels in the apical membrane is primarily controlled, then the basolateral membrane K+ permeability. Yet, species differences are worth to note: the trachea of the cow is barely sensitive to agents that exert a marked action on dog trachea. The tracheal epithelium is used as an experimental model for studying cystic fibrosis, a disease in which the apical membrane is almost devoid of functional Cl- channels, so that Cl- permeability is quite low.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗
PubMed1988

[Subtotal traumatic amputation of the limb in young children. Analysis of 2 successful repairs].

Two replantations of nearly completely amputated limbs are presented. In both cases there were young children. These two success explain the necessity of limb preservation if the nerve integrity is respected. In the young child, the vital risk is lower because of the vessels, the local immunologic defense. The bone union is normal. The vascular suture with venous grafts is made with simple interrupted sutures rather than with continuous over and over sutures. The fasciotomy avoid a compartment syndrome. The bone graft growth is unforeseeable. These two case reports are nearly experimental because of the young age of the patients.

Age Factors↗
PubMed1987

L-glutamate and N-methyl-D-asparatate actions on membrane potential and conductance of cat abducens motoneurones.

The actions of L-glutamate and N-methyl-D-aspartate (NMDA) were studied with intracellular recordings from cat abducens motoneurones. Amino acids were electrophoresed extracellularly from the same 7-barreled electrode types as those used in the spinal cord. Depolarization development, conductance changes and firing pattern induced by amino acids were very similar to those described for spinal motoneurones. The shape of NMDA depolarization suggests a uniform distribution of the involved receptors on the membrane of the motoneurone.

Abducens Nerve↗
PubMed1987

Changes in composition of endoneurial and perineurial fatty acids during glycerol-induced Wallerian degeneration and regeneration in the sciatic nerve of the adult rat.

Intraneural injection of pure glycerol induces Wallerian degeneration with subsequent regeneration. In agreement with other reports, we observed an increase in endoneurial polyunsaturated fatty acids 8 days after the glycerol injection. Levels then fell until day 30. After a period of 5 months, there was an increase in C18:2(n-6) in the intrafascicular tissue, concomitant with a marked fall in this fatty acid in the remaining extrafascicular perineurium. The rise in C18:2(n-6) in endoneurium correlated with infiltration of this tissue by perineurial cells. Interactions between perineurium and endoneurium during nerve regeneration are discussed.

Animals↗
PubMed1987

Persistence of retinal dopamine cells in the degenerated eye of the cave salamander, Proteus anguinus L.

The Proteus anguinus L. is a blind cave perennibranch amphibian whose visual system undergoes an important morphogenetic degeneration in adulthood. The eyeball becomes atrophied and disappears under the fat tissue of the head. However, a retina can still be identified and a photophobic behavior of the animal indicates a remaining photosensitivity. In the oldest animal observed, some photoreceptor cells are still present as well as other types of retinal neurons. Characteristic synapses are observed in both the inner and outer plexiform layers. Dopaminergic amacrine cells, with processes in the inner plexiform layer, can be identified by their tyrosine-hydroxylase immunoreactivity. Taken together, these results indicate a possible functional role of the remaining retina. Since dopamine is especially involved in light adaptation from darkness, the residual retina could act in triggering the turning behavior of Proteus in response to lightening.

Animals↗
PubMed1987

[C-terminal extremity of ovine thyroglobulin shows strong interspecies homologies].

We report on the 466 nucleotides long, extreme 3' end of the ovine thyroglobulin (Tg) mRNA. The nucleotide sequence and the deduced carboxyl terminal region of the protein have been compared with those reported in other species. Comparison with hog peptides known to contain all the triiodothyronine (T3) of the mature Tg suggests that the antepenultimate amino acid, a tyrosine residue could be involved in hormone formation. This also agree with the data reported for bovine and murine Tg.

Animals↗
PubMed1986

Quality criteria for chromatographic analytical systems of polyunsaturated fatty acids metabolites.

The most powerful technique for eicosanoids identification is gas chromatography prior to mass spectrometry. Results are highly dependent upon the choice of appropriate gas chromatographic systems; the critical point of the system being the quality of the column. Our work is intended to provide a general overview of open tubular capillary columns which can be used for separation, identification and quantification of eicosanoids.

Arachidonic Acid↗