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J Ribas

Publications and source records attributed to J Ribas.

68 records · Page 4Linked to original sources
PubMed1985

The zona-free hamster egg penetration assay as a prognostic indicator in a human in vitro fertilization program.

The present study was designed to test the validity of the hamster egg penetration assay as a prognostic indicator of male fertility in 54 patients undergoing in vitro fertilization. Human oocyte fertilization, cleavage, and pregnancy were compared with the results of this bioassay. Good correlation was found between hamster egg penetration and oocyte fertilization. Conversely, a definite lower limit of hamster egg penetration to define absolute male infertility could not be established because human oocyte fertilization, cleavage, and even pregnancy occurred in spite of low hamster egg penetration.

Animals↗
PubMed1984

A diagnostic "patch test" for onchocerciasis using topical diethylcarbamazine.

There is great need for a simple, inexpensive, and sensitive diagnostic test for onchocerciasis, especially in endemic areas where trained personnel and laboratory facilities are limited. Diethylcarbamazine (DEC) was applied as a "patch test" to the skin of 45 patients with onchocerciasis in the Southern Sudan. 75 tests were done on these 45 patients, and 69 (92%) were positive. A positive reaction was a papular eruption beneath the patch. Histopathological studies of the skin beneath the patch revealed the microscopic features of a severe Mazzotti reaction, including degenerating microfilariae in the upper dermis and within epidermal eosinophilic abscesses.

Administration, Topical↗
PubMed1983

[Projections of the nucleus praepositus hypoglossi to the cerebellum in the cat].

The axonal projections from the nucleus praepositus hypoglossi (PH) to the cerebellum have been studied in cat. Cerebellar projections were evidenced by means of the retrograde axonal transport of horseradish peroxidase. According to the results the PH nucleus projects to the entire vermis, especially to the posterior lobes, as to the flocculus and paraflocculus. No projections to other areas of the cerebellar cortex were found. PH projections go to the cerebellum through the inferior peduncle.

Animals↗
PubMed1982

[Effects of distal axotomy on field potentials of the external oculomotor nucleus in the waking cat].

The electrophysiology of abducens nucleus antidromic field potentials from onset of peripheral axotomy up to reinnervation has been studied in the alert cat. Nerve section induced a reduction of 80% in the amplitude of the antidromic field potential. This reduction began from 2 to 5 days after axotomy and returned to control values from 20 to 30 days later, in parallel with recovery of oculomotor function. During the critical chromatolytic period, the latency of the antidromic potentials increased, while the amplitude of the antidromic field potential could be easily modified by adequate visual and/or vestibular stimulation. In contrast to control motoneurons, axotomized cells showed a noticeable variability in their activation latency, as well as a higher threshold for the antidromic invasion of the IS-SD compartments.

Abducens Nerve↗
PubMed1982

[Activity of axotomized motor neurons of the external oculomotor nucleus in the waking cat].

The spontaneous and the visual and vestibular induced activity of axotomized abducens motoneurons (ABD Mns) has been recorded in alert cats. Axotomy was carried out peripherally in the ocular orbit. ABD Mns were identified by their antidromic activation from the VIth nerve. Control Mns showed a clear relationship with eye position and velocity in the horizontal plane, whereas axotomized Mns showed a remarkable variability in their antidromic activation, a rapid fatigability during eye fixations and a decreased sensibility to eye velocity. Occasionally, axotomized Mns fired a short burst of activity before saccades in the off-direction. Functional involvements of described findings are discussed.

Abducens Nerve↗
PubMed1982

[Field potentials induced in the ambiguous nucleus by stimulation of the recurrent and superior laryngeal nerves].

Field potentials in the ambiguous nucleus induced by stimulation of the recurrent, superior laryngeal and vagus nerves have been recorded in the anesthetized cat. Stimulation of the ipsilateral recurrent nerve induced a positive-negative-positive antidromic field potential in the ambiguous nucleus indicating a close-field organization of laryngeal motoneurons, which showed a preferential projection of their dendritic trees in dorso-medial and ventro-lateral directions. Superior laryngeal nerve stimulation induced the sequential synaptic activation of laryngeal motoneurons. Besides laryngeal motoneurons activation, stimulation of the vagus nerve also induced the antidromic invasion of a distinct population of efferent neurons with a latency longer than those of laryngeal motoneurons.

Animals↗
PubMed1981

Identification of prepositus neurons projecting to the oculomotor nucleus in the alert cat.

A population of prepositus hypoglossi nucleus neurons with discharges correlated to gaze parameters and antidromically activated by stimulation of the ipsilateral oculomotor nucleus has been recorded in the alert cat. The latency for antidromic invasion was of 0.6-0.8 msec. Neuronal firing rate encoded eye position and eye velocity in the horizontal plane, showing in all cases ipsilateral 'on' direction.

Animals↗
PubMed1981

[Neurophysiological study of the neurons of the nucleus prepositus hypoglossi which projects to the oculomotor complex in the cat].

The spontaneous and vestibularly induced activity of 19 prepositus hypoglossi neurons antidromically activated by the electrical stimulation of the ipsilateral oculomotor complex has been recorded in awake cats. Spontaneous activity of these neurons was linearly related to horizontal eye position, increasing their firing frequency with positions further to the recording side. Sinusoidal rotation of the animal showed that these neurons were type II. Sensitivity of the neurons to eye velocity was very low. According to present results, it is concluded that prepositus hypoglossi neurons that project to the oculomotor complex are "position-velocity" units possible final destinations of prepositus terminals in the oculomotor nucleus are also discussed.

Animals↗
PubMed1981

A morphological and electrophysiological study of nigrotectal pathway in the rat.

After horseradish peroxidase injections in the superior colliculus of the rat, labelled cells were found in the pars reticulata of the substantia nigra. Nigrotectal cells are organized in a band beginning in the ventromedial area of the rostral part of pars reticulata, while at caudal levels they occupy a more lateral position, closely packed near the cerebral peduncle. In another series of experiments, the effects of substantia nigra electrical stimulation on collicular unitary activity was studied in anaesthetized rats. Electrical stimulation of the substantia nigra decreased the spontaneous and pharmacologically induced activity of superior colliculus neurons. Inhibition took place with short latencies (1-4 msec). Inhibited cells were localized in deep layers of the superior colliculus. In addition, long latency activation and inhibition were also obtained. It is concluded that nigrotectal pathway is mainly inhibitory in character.

Animals↗
PubMed1978

A study of indomethacin combined with ritodrine in threatened preterm labor.

A prospective and double-blind study was undertaken to compare the effectiveness of two different treatments on two randomized groups of patients with threatened preterm labor. The first treatment consisted of the administration of ritodrine and a placebo; in the second, ritodrine was combined with indomethacin. 22 patients were evaluated in each group. The results obtained for gain in days, number of patients delivered at term, weight of newborns and number of recurrences in each group suggest that treatment with ritodrine and indomethacin is slightly but significantly more effective than treatment with ritodrine and placebo in prolonging pregnancy. No evidence has been found of possible unfavorable vascular effects of indomethacin in the fetus or the newborn.

Adult↗
PubMed1977

Phenylethanolamine: a new putative neurotransmitter in Aplysia.

Phenylethanolamine is present in the Aplysia nervous system in concentrations similar to that of octopamine. These are receptors that are very specific for phenylethanolamine, which on different neurons mediate sodium, chlorine, or potassium conductance increase responses. These observations indicate that phenylethanolamine may act as a neurotransmitter in Aplysia.

Animals↗
PubMed1975

The primate median eminence. I. Correlative scanning-transmission electron microscopy.

A combined scanning/transmission electron microscopic (SEM/TEM) technique was used to analyze the third cerebral ventricle and underlying tissue of the median eminence of 6 mature rhesus monkeys. The same sample of the ventricular wall was subjected to both SEM and TEM. This technique demonstrates two basic subpopulations of supraependymal cells on the surface of the supraoptic, infundibular and mammillary recesses. Type 1 cells are definitely neuron-like in their surface configuration and internal fine structural organization. Type 2 cells are more similar to histiocytes and are not as numerous as type 1 cells. The functional capacity of type 1 cells is discussed in the context of their potential role as a neuronal network that may serve as a short loop autoregulatory mechanism controlling the synthesis of releasing hormones or biogenic amines.

Animals↗