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At least 415 records · Page 23Linked to original sources
PubMed1990

[Otorhinological evaluations of patients undergoing rapid disjunction of the median palatine suture].

Seven young patients, who had been diagnosed to be oral breathers by an orthodontist, have been submitted to an ETN specialist examination, before and after the rapid expansion of the mid-palatal suture. Five of these patients had an actual reduction of nasal breathing capacity. Four patients presented a significant enlargement of the adenoids. One patient showed a transmission auditive deficiency. The ETN examination, two months after the maxillary expansion, has permitted to find out that all the patients who had an impaired nasal breathing before the maxillary expansion, had normalized their respiratory capacity. Moreover, those subjects who had enlarged adenoids, showed a normal adenoids volume in the second ETN examination. Finally also the patient with an auditive deficiency presented a normalization of this function at the second ETN examination.

Adenoids↗
PubMed1989

Genetic and molecular analysis of a simple disjunctional system in Drosophila melanogaster.

The basic aspects of the achiasmate distributive segregation system in Drosophila are briefly reviewed. Specific attention is given to the role of homology in specifying the patterns of distributive segregation. The genetic and molecular analysis of mutations affecting the system is also discussed. Finally, a consideration of the available evidence allows the presentation of a revised model of meiosis in Drosophila.

Animals↗
PubMed1989

Nucleolar organizer region heteromorphism associated with trisomy-21: a risk factor for non-disjunction?

An unusual nucleolar organizer region (double NOR) on chromosome 13 was observed in a Down syndrome child [47, XY, +21, dNOR(13)]. The variant chromosome was inherited from the mother [46, XX, dNOR(13)]. The extra chromosome 21 in the proband was maternal origin. The frequency of NOR chromosome association showed relatively high frequency in the mother and proband as compared to the controls. The result suggest that chromosome variants involving extra copies of NOR may indeed be involved in the meiotic nondisjunction of chromosome-21.

Child, Preschool↗
PubMed1987

[Epididymo-testicular disjunction. Presentation of 23 cases and review of the literature].

Twenty three cases of alterations of the epididymis-testicular union found in 1,000 children with cryptorchism are discussed. Anatomical and pathological findings are described and world literature on the subject is reviewed, finding very scanty references to this problem in spite of the fact that expected incidence of epididymis testicular non-junction is between 1 and 2% of the patients with cryptorchism.

Child↗
PubMed1986

[Disjunction between the daily duration of light and the plasma level of prolactin under hyperlong days in rams].

Adult rams were submitted to an artificial light regime with increasing and decreasing daylengths between 6 and 20 hrs. over a period of 8 months. Blood samples occurred at different durations of daylengths for measuring plasma levels of prolactin. Levels were high for a daily duration of light of 14.20, 17 and 18.30 hrs. along the increasing light-phase and of 18.30 hrs. during the decreasing light-phase. On the other hand prolactin levels were low for short daylengths, but also for a daylength of 20 hrs. It clearly appears that hyperlong days (greater than 18 hrs.) do not stimulate (or do actively inhibit) the secretion of prolactin in ovines.

Animals↗
PubMed1986

[Chromosome segregation in mice heterozygous for Robertsonian translocations. I. The effect of mutation in chromosome 17 on the disjunction of homologs in females].

The effects of mutations on chromosome 17 upon the segregation of the metacentric and acrocentric homologues in the progeny of female mice heterozygous for Robertsonian translocations Rb(8.17) 1Iem and Rb(16.17) 7Bnr were studied. Genetic analysis indicated that the ratio of Rb to non-Rb (normal karyotype) progeny from mothers heterozygous for mutations tf, qk, t12 were not significantly different from 1:1 expected. Introduction of mutations T, Ki, Fu, t6 into the female genotype caused strong distortion of segregation and an increase in the proportion of progeny with normal karyotype (65-70%). From the data on embryonic mortality and cytogenetic observations, it is concluded that distortion of equal transmission arises before MII of meiosis. Consequently, preferential distribution of the metacentric chromosome into the polar body during the first meiotic division is relevant to the segregation distortion observed.

Animals↗
PubMed1986

[Chromosome segregation in mice heterozygous for Robertsonian translocations. II. Changes in the structure of homologs as a cause of abnormal disjunction in females].

It was demonstrated that mutations T, Fu, Ki, t6 of chromosome 17 cause preferential transmission of the acrocentric homologues to the progeny from female Rb heterozygotes. The results indicate that the effects of these mutations on segregation are restricted to the Robertsonian translocations involving chromosome 17. Substitution of the parts of chromosome 17 distal or proximal to the T-locus did not alter the effect, of this chromosome on the transmission rate of the homologue. The transmissions effects of these mutations, whether cis or trans with Rb, were the same. It was observed that mothers Rb7/T43H transmitted the chromosome with the reciprocal translocation T43H to 70.9% of their progeny. Data were obtained supporting the idea that structural changes of the chromosomes caused by mutations affect segregation of the homologues in Rb heterozygous females. The possible mechanism of this influence is discussed.

Animals↗
PubMed1985

Conjugate and disjunctive saccades in two avian species with contrasting oculomotor strategies.

We have recorded with the magnetic search coil method the spontaneous saccades of two species of predatory birds, which differ in the relative importance of panoramic and foveal vision. The little eagle (Haliaetus morphnoides) hunts from great heights and has no predators, whereas the tawny frogmouth (Podargus strigoides) hunts from perches near the ground, is preyed upon, and frequently adopts an immobile camouflage posture. We find that both birds spend most of the time with their eyes confined to a small region of gaze, the primary position of gaze; in this position, the visual axes are much more diverged in the frogmouth than in the eagle, thereby giving it a larger total field of view at the expense of its binocular field. Both species, however, can align their visual axes, thereby gaining a binocular view of targets in the frontal visual field. The eagle makes saccades 10 times as frequently as the frogmouth, and in most of its saccades the eyes move in the same direction, although the eye movements are generally not conjugate; in most frogmouth saccades, on the other hand, the eyes move in opposite directions. We discuss these phenomena in terms of their saccadic mechanisms and their possible adaptiveness. We also report two incidental observations: in certain circumstances, the frogmouth shows no sign of having a vestibulo-ocular reflex, and the eagle, although the quintessential foveate animal, shows extreme directional asymmetries of monocularly evoked optokinetic nystagmus.

Animals↗