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Biomedical subjects

J Petit

Publications and source records attributed to J Petit.

At least 307 records · Page 17Linked to original sources
PubMed1977

Fast-conducting skeletofusimotor axons supplying intrafusal chain fibers in the cat peroneus tertius muscle.

1. In six experiments on cat peroneus tertius muscle, from 12 to 23 motor axons with conduction velocities above 85 m/s were repetitively stimulated so as to produce glycogen depletion in the muscle fibers they innervated. 2. The whole muscle was then quick-frozen, serially cut, stained to demonstrate glycogen, and examined for intrafusal glycogen depletion. 3. Zones of glycogen depletion were found in 27 of the 99 examined spindles: they were almost invariably located on chain fibers and specifically on the longest of the chain fibers in affected spindles. 4. Since it was shown that there are no purely fusimotor fast axons in the motor supply to peroneus tertius, it is concluded that skeletofusimotor axons are present among the fastest motor axons to this muscle.

Animals↗
PubMed1976

[Quantitative separation of biological lipids by successive chromatographic runs on juxtaposed thin layers (author's transl)].

During a study on incorporation of 14C-labeled precursors in biological lipids, we had to elaborate a method of quantitative separation of lipid classes, based upon three successive chromatographic runs on juxtaposed thin layers. The first thin layer, on which the lipid extract is applied, consists of silica gel alkalised by means of sodium hydroxide solution. The second thin layer is constituted only by silica gel G. The three one-dimensional migrations are respectively carried out in the following solvent systems: diethyl ether-hexane-benzene (55:30:15), hexane-benzene (80:20) and diethyl ether-benzene-acetic acid (62:20:18). The lipid fractions are scraped out and counted by liquid scintillation. The reproducibility of the whole operation is discussed.

Alkalies↗
PubMed1976

Heterogeneity of motor units activating single Golgi tendon organs in cat leg muscles.

The aim of this study was to investigate whether an individual Golgi tendon organ can signal the contraction of motor units with different physiological properties. The axonal conduction velocity and tetanic tension of motor units were examined in four muscles of the cat leg (peroneus brevis, peroneus longus, tibialis anterior and soleus). The motor units which were found to activate a given tendon organ had contractile properties dispersed over the same range as those of the whole muscle population. The proportion of tendon organ-activating motor units found in the studied samples suggests that altogether, the Golgi tendon organs of a muscle monitor the contraction of every motor unit in this muscle.

Animals↗
PubMed1976

Frequency of tendon organ discharges elicited by the contraction of motor units in cat leg muscles.

1. The responses elicited in individual tendon organs by the contraction of single motor units were studied in peroneus longus, peroneus brevis, tibialis anterior and soleus muscles. 2. No simple relation was found between the discharge frequency of a tendon organ and the tension produced in the muscle tendon by the contraction of individual motor units. 3. The sensitivity of a given tendon organ to contractile tension was not the same for each of the motor units which elicited its discharge. There was no correlation between the sensitivity of the receptor and the strength of the motor units. 4. Upon repetitive stimulation of a tendon-organ-activating motor unit at increasing rates, the frequency of the receptor sustained discharge reached a maximal value for rates of stimulation eliciting submaximal tetanic tension. Higher rates only produced an increase in the dynamic component of the tendon organ response. 5. These observations show that the contractile tension sensed by a tendon organ is not a simple fraction of the tension which appears at the muscle tendon. They might be accounted for as consequences of the fine structure of tendon organs and of variations in the number of muscle fibres contributed by different motor units to the bundle inserted on each receptor. The location of most tendon organs at musculo-aponeurotic junctions rather than in the tendon proper, could also be responsible for some of the observed discrepancies.

Action Potentials↗
PubMed1976

[Influence of an hypolipemic agent on the incorporation of 14C-labelled precursors in hepatic and serous lipids of the rat].

The action of a new hypolipidemic agent, the calcium diacetone-(ceto 2)-gulonate (D.C.G.Ca), on cholesterol and other lipid compounds biosynthesis has been studied in rats. The incorporation of 14C labelled acetate and mevalonate in liver and serum lipids of control rats has been compared with that of rats previously treated with D.C.G.Ca. No action of this compound has been noted on cholesterol biosynthesis after the mevalonate stage, which is an important result in consideration of therapeutic risks. Otherwise, a significant decrease of 14C-acetate incorporation in triglycerides has been observed in treated rats.

Acetates↗
PubMed1976

[Phosphorus requirements of bacteria metabolizing hydrocarbons in the sea].

The artificial stimulation of biological purification of sea-pollutant hydrocarbons requires phosphorus supply. The concentrations, corresponding to the optimal bacterial growth, depend, in particular on ionic strength. They range between 2 and 8 X 10(-4) M for waters in which the salinity is close to the mean salinity of an oceanic environment and between 1.5 and 3 X 10(-3) M when these waters receive a significant supply of freshwater or when salinity is naturally weak. Inhibition of bacterial development has been observed either with a microflora, or with pure strains for concentrations higher than the upper limits of concentrations so defined.

Acetates↗
PubMed1975

Cytochemical and electron-microscopic study of the paraoesophageal bodies and related nerves in Schizophyllum sabulosum (L.), Diplopoda Julidae.

The ultrastructural study of the paraoesophageal bodies of Schizophyllum sabulosum reveals the occurrence of two axonal types (ax 1 and ax 2) near secretory cells. Two possibilities exist for the functional role of the nerves related to these paraoesophageal bodies. The results of treatment with proteases (pronase, pepsin, trypsin) and the identification of glycogen in both the paraoesophageal bodies and the nerves that link them to the brain and Gabe organs, suggest transport of at least part of the secretions from the paraoesophageal bodies to the Gabe organs.

Amino Acids↗
PubMed1975

[The paracommissural regions (brain neurohemal formations) of diplopods. Preliminary note].

The paracommissural plates of Diplopods are neurohemal "organs" anatomically not individualized in bodies separate from the brain. They lie near the transverse commissure (tritocerebral commissure s.l.). They are composed of at least two distinct types of axon terminals, glial cells, tracheae and a neural lamella facing a blood sinus. The axons of paracommissural plates of originate in neurosecretory cells lying in the ganglions of the transverse commissure. The release of granules partly occurs by exocytosis.

Animals↗
PubMed1975

Unsutured Dacron prosthesis in groin hernias.

We have repaired difficult groin hernias during the past six years by an original procedure consisting of fitting an unsutured Dacron patch between the peritoneum and the muscular layers using a median lower abdominal incision. Our standard technic is described along with its variations and applications.

Adult↗