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Biomedical subjects

W Bacon

Publications and source records attributed to W Bacon.

52 records · Page 3Linked to original sources

Possible roles for corticosterone and critical size in the fledging of nestling pied flycatchers.

Our study was designed to see whether corticosterone (B) rises abruptly in the blood of nestling pied flycatchers (Ficedula hypoleuca) at the time they fledge, as reported recently for kestrels, and if so, why. We measured the growth and blood levels of B and selected nutrients of nestlings in broods of five, seven, and nine chicks during 1998 and 1999. In half of the broods, we clipped selected wing and tail feathers of both parents with the intention of making it more difficult for them to provide their chicks with food. We collected blood samples when the chicks were six to 10 d old (period of rapid growth) and 15 d of age or older (0-5 d before fledging). B increased substantially several days before the chicks left the nest and then declined somewhat. We found no differences in rates of growth or blood levels of B, nutrients, and hematocrit as a function of either brood size or parental handicapping. Nestlings within a day of fledging appear to have been food deprived in 1998; their glucose was significantly reduced, and B, free fatty acids, and glycerol were significantly elevated compared to levels in chicks 1-4 d younger. Such changes did not occur in 1999. Blood levels of B were significantly correlated with brood size near the day of fledging, but not earlier, in both years of the study. It was possible to predict the day on which chicks would leave the nest, using their wing length when 12 d old. These results suggest that high blood levels of B associated with food restriction and sibling competition induce chicks to fledge, provided they have reached a critical size, and that the importance of fasting, sibling competition, and B may vary from year to year.

Animals↗

GAPO syndrome: a new case of this rare syndrome and a review of the relative importance of different phenotypic features in diagnosis.

The case of GAPO syndrome reported here is the 24th recorded case, 23 cases having been published previously. The 29-year-old male under discussion presents all the typical features of the syndrome, having short stature, dysmorphic craniofacial features, total alopecia and pseudoanodontia. Orally, the erupted primary dentition was extremely worn and on radiographic examination, the second mandibular molars were found to be unerupted, together with the entire permanent dentition. Cephalometry revealed the absence of facial pneumatisation, a deficient cranial base with diminished upper face height and maxillary and mandibular hypoplasia with a prognathic skeletal pattern. Histological examination of an extracted primary incisor and its surrounding root bone revealed extensive ankylosis. This paper describes in detail the clinical findings and reviews, and discusses previously published cases in relation to the present one. As with prior cases, parental consanguinity was present in the pedigree.

Abnormalities, Multiple↗

[Methods for the anthropologic and teleradiographic study of the pterygoid process].

The relationships of the external pterygoid plate with the other components of the craniofacial building has hardly been explored because of recording difficulties. A method to accurately identify in a reproducible way the main axis of the pterygoid process with the help of two small iron balls was contrasted with other methods seen in the literature. The iron balls technique was shown to be the method of choice with regard to biostatistical consistency.

Adult↗