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Biomedical subjects

J Lamarche

Publications and source records attributed to J Lamarche.

15 recordsLinked to original sources
PubMed1988

Experimental allergic encephalomyelitis: a neurourological study.

To assess the neurourological disturbances produced by the perivascular inflammatory process in the acute phase of experimental allergic encephalomyelitis, we carried out a controlled study. Forty-six New Zealand male rabbits were inoculated with an encephalitogenic preparation. Twenty-seven of them developed neurological deficits in an average of 9.3 days postinoculation. A sample of 19 subjects was used as a control. The subjects were studied within 2 days after the manifestation of the first sign of encephalomyelitis. An average of eight successive cystosphincterograms were recorded. Their entire central nervous system was removed intact and suspended in 10% neutral buffered Formalin solution for 2 weeks, then cut into segments, embedded in paraffin, and finally stained with hematoxylin-eosin and Luxol Fast Blue. The results demonstrated a significant reduction of mean vesical capacity, maximum urethral pressure, and mean urethral pressure in the group with encephalomyelitis. Furthermore, we found a significant negative correlation between the average number of cellular perivascular infiltrates in the spinal sacral segment and urethral pressures. The results showed a significant negative correlation between supreamesencephalic inflammation and mean vesical capacity.

Animals↗
PubMed1988

Colonic hamartomas in tuberous sclerosis.

Twelve patients, 5 from the same family, diagnosed consecutively to suffer from tuberous sclerosis were investigated for gastrointestinal polyps. Six patients had no clinical neurologic involvement. Nine had colonic polyps: in 5 patients, these were hamartomas, in 3 patients adenomatous polyps, and the ninth patient had hamartomas and adenomatous and villoglandular polyps. Hamartomatous polyps were identical to those found in the Peutz-Jeghers syndrome. However, in 1 patient they included neural structures and in another there were angiomatous and adipous structures in addition to colitis cystica profunda. Two patients with hamartomatous polyps had normal intelligence and no clinical neurologic symptoms. The evaluation of one kindred revealed the association of hamartomatous polyps of the colon with forme fruste of tuberous sclerosis in different members, but none had the typical disease. Tuberous sclerosis should thus be considered in the differential diagnosis of hamartomatous colonic polyps. Conversely, colonic endoscopy may be a useful adjunctive test in the diagnosis of tuberous sclerosis, particularly in the incomplete varieties of disease.

Adolescent↗
PubMed1987

Pattern electroretinogram and optic nerve section in pigeons.

We studied the effect of optic nerve section on the pattern electroretinogram (PERG) of 10 pigeons. Base line PERG and flash ERG were measured prior to surgery and then one optic nerve was cut. We measured PERG at various time intervals up to 24 weeks after the section. There was a sharp drop in PERG amplitude immediately following the section. It gradually returned to normal levels in the following 24 weeks. Significant decreases in time to peak were noted at 1 and 16 weeks for 0.5 cycle per degree checks and at 1, 2 and 9 weeks for 0.25 cycle per degree checks. The ERG generated by a TV stimulus did not change in amplitude but had a shorter time to peak at 24 weeks for a high intensity stimulus and at 16, 18, 24 weeks for a low intensity stimulus. Light and electron microscopic sections (at 24 weeks) revealed an almost complete loss of nerve fibers in the optic nerve. Retinal sections revealed only a few surviving ganglion cells and a few nerve fibers. This suggests that in pigeons, PERG is not generated by ganglion cells.

Animals↗
PubMed1987

Carcinomatous neuropathy. An ultrastructural study of ten cases.

Superficial peroneal nerve biopsies were studied from 10 patients with carcinomatous neuropathy. There were 6 patients with the sensorimotor form and 4 patients with the sensory form. In both forms of neuropathy, histometric studies showed a variable loss of myelinated fibers which was generally most severe in the sensory form. In most of the cases of the sensorimotor form, ultrastructural studies showed segmental demyelination with onion bulb formation and regeneration of myelinated fibers. In the sensory form, there was no segmental demyelination, the regeneration of myelinated fibers was minimal and all the cases showed a loss of unmyelinated fibers. In sensory neuropathy, the histometric and ultrastructural changes reflect the massive acute destruction of ganglion cells in the dorsal root ganglia. In sensorimotor neuropathy, the alterations indicate a slowly progressive degenerating process in which both axonal degeneration and segmental demyelination occurred.

Aged↗
PubMed1985

The ventilatory response to hypoxia in the newborn lamb after carotid body denervation.

Neonates of various species including lambs respond to hypoxia by a transient hyperventilation followed by a VE depression (diphasic response). To better delineate the role of the carotid chemoreceptors and that of the central depressive/inhibitive effect of hypoxia on minute ventilation, we have studied the VE response of 4-day-old carotid body-deprived lambs (CBD) during successive exposure to moderate and severe (0.12 and 0.07 FIO2) hypoxia. The carotid body denervation was done to abolish most of the chemoreceptor stimulating effect on VE during hypoxia and to allow for central depression/inhibition of VE during hypoxia. In the CBD lambs, baseline VE was 461 +/- 81 (SE) ml X (kg X min)-1. It increased to 532 +/- 79 ml X (kg X min)-1 and to 541 +/- 75 ml X (kg X min)-1, to 0.12 FIO2 and 0.07 FIO2. These VE increases did not reach level of significance (P greater than 0.05). After 2-5 min of both levels of hypoxia VE dropped respectively to 460 +/- 60 ml X (kg X min)-1 and to 459 +/- 38 ml X (kg X min)-1. No marked ventilatory depressions were noted but VE had only returned to baseline. It is concluded that, in the denervated newborn lamb, the centrally mediated depressive effect of hypoxia is small and not sufficient to explain the diphasic VE response of the intact lamb to steady state hypoxia. Analysis of the magnitude of the hyperventilation and the VE damping pre-hypoxic levels occurring with sustained hypoxia in newborns of various species suggests that the immaturity of the O2-sensitive chemoreceptor rather than the central effect of hypoxia is the determinant factor of the diphasic response of newborn mammals to hypoxic hypoxia.

Animals↗
PubMed1985

Postnatal maturation of respiration in intact and carotid body-chemodenervated lambs.

The contribution of the carotid body chemoreceptor to postnatal maturation of breathing was evaluated in lambs from 7 to 70 days of age. The study was conducted by comparing the eupneic ventilation and resting pneumograms in intact conscious lambs with those of lambs that were carotid body chemodenervated (CBD) at birth. In comparison to the 1-wk-old intact lambs, the CBD lambs had significant decreases in minute ventilation (VE, 313 vs. 517 ml/kg), tidal volume (VT, 7.2 vs. 10.5 ml/kg), respiratory rate (f, 44 vs. 51 breaths/min), and occlusion pressure (P0.1, 2.8 vs. 7.2 cmH2O). Arterial PO2's were 59 vs. 75 Torr (P less than 0.05) and arterial PCO2's 47 vs. 36 Torr (P less than 0.05), respectively, in CBD and intact lambs. In intact lambs from 7 to 70 days, resting VE decreased progressively from 517 to 274 ml/kg (P less than 0.01) due to a fall in VT, mean inspiratory flow (VT/TI), and f, whereas the ratio of inspiratory time to total breath duration remained constant. P0.1 decreased from 7.2 to 3.9 cmH2O from 7 to 42 days. In contrast the CBD lambs experienced only minimal changes in VE, VT, VT/TI, and f during the same period. VE only decreased from 313 to 218 and P0.1 from 2.8 to 2.4 cmH2O. In contrast to that of intact lambs the resting pneumogram of CBD lambs remained relatively fixed from 7 to 70 days. Three CBD lambs died unexpectedly, without apparent cause, in the 4th and 5th wk of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗