Microscopic anatomy of the eye of the deep-diving Antarctic Weddell seal (Leptonychotes weddellii).

The microscopic anatomy of the eye of the Weddell seal was studied with various light and electron microscopic methods with a view to correlating morphological findings with the biology of this seal which is adapted to the extremes of the Antarctic environment and to extreme diving excursions into the lightless depths of the sea. In the retina an area centralis was found but no fovea centralis. The densely packed photoreceptors consist exclusively of highly differentiated rods, which in primates detect light at low intensity but have rather poor image discrimination. The ganglion cells are relatively scarce, suggesting a high degree of convergence of the light-sensitive cells on the ganglion cells. The pigment epithelium is almost devoid of pigment granules. The extensive tapetum lucidum is about 400-500 microm thick and is composed of about 30 layers of specialized cells. The cornea is 650 (center) to 800-900 (periphery) microm thick. Its structure and glycosaminoglycan histochemistry correspond to that of other mammals. The iridocorneal angle is unusually deep and pervaded by an elaborate trabecular meshwork, which together with a complex canal of Schlemm can be correlated with the ability to absorb large amounts of fluid. The ciliary muscle and its antagonist, the membrane of Bruch, are poorly developed, suggesting relatively poor abilities of accommodation. The combination of a well-developed tapetum lucidum, an unpigmented pigment epithelium, well-developed rods, and a high number of rods converging on only few ganglion cells is obviously an adaptation to an extreme light sensitivity, enabling the animals to make use of the little light available in the deep sea.

Histophysiological observations on the external auditory meatus, middle, and inner ear of the Weddell seal (Leptonychotes weddelli).

The external auditory meatus, middle, and inner ear of the deep-diving Weddell seal (Leptonychotes weddelli) were studied with light microscopic, histological, and histochemical techniques in order to contribute to the open discussion on the orientation of this seal in the darkness of the deep Antarctic seas. The external auditory meatus is characterized by a well-developed venous plexus, single apocrine ceruminous, and numerous holocrine sebaceous glands and an incomplete tube of elastic cartilage. The tympanic membrane is comprised of two layers of radially and concentrically arranged collagen fibers and by elastic fibers which are concentrated in the outer part of the ear drum. The tympanic cavity is lined by a pseudostratified prismatic ciliated epithelium with goblet cells; a plexus of wide venous vessels marks the subepithelial lamina propria. The cochlea is about 10 mm high and forms about two and a half turns. The richly pigmented stria vascularis is well vascularized, while the cell-rich prominentia spiralis contains only single small blood vessels. The organ of Corti contains one row of inner and three rows of outer hair cells. Cells of Hensen, Claudius, and Boettcher are present. The basilar membrane is of comparatively uniform simple structure and is composed of abundant glycoproteins, proteoglycans, collagenous fibers, and the loose tissue of the tympanal layer. The spiral ligament is built up by abundant proteoglycans and a complex system of radial and concentric collagen fibers; close to the osseous wall of the bony cochlea it contains fine elastic fibers. The inner zone of the osseous wall of the cochlea strikingly contains hyaline cartilage. The thin lamina spiralis ossea is covered by a limbus spiralis with interdental cells secreting the lamina tectoria, which has a fibrous texture and contains glycoproteins and negatively charged components.

[Administration of terfenadine in a single dose: comparison to standard treatment, as a double blind study, in patients presenting with allergic rhinitis]. / Administration de la terfénadine en prise unique: comparaison au traitement standard, en double aveugle, chez des patients présentant une rhinite allergique.

This double-blind, randomized multicentre study was designed to compare efficacy and tolerability of 120 mg terfenadine taken once daily (in the morning) with the established regimen of 60 mg terfenadine taken twice daily in the treatment of seasonal rhinitis. Two comparable groups, a total of 191 hay fever patients, were treated for 1 week. Symptom severity was assessed by the investigators before and at the end of the treatment (visual analogue scale), and daily by the patient (four-point rating scale). All symptoms improved to a similar degree in both groups. Differences between the two groups were not statistically significant, except for nasal symptoms in three cases as assessed by the visual analogue scale in one centre (better relief in the group given 120 mg terfenadine once daily). Tolerability was good and similar in both groups. The data presented show that in the treatment of hay fever 120 mg terfenadine given once daily is an effective, convenient and well tolerated alternative to the regimen of 60 mg terfenadine given twice daily.

Multi-centre double-blind comparison of terfenadine once daily versus twice daily in patients with hay fever.

This double-blind, randomized multi-centre study was designed to compare efficacy and tolerability of 120 mg terfenadine taken once daily (in the morning) with the established regimen of 60 mg terfenadine taken twice daily in the treatment of seasonal rhinitis. Two comparable groups, a total of 191 hay fever patients, were treated for 1 week. Symptom severity was assessed by the investigators before and at the end of the treatment (visual analogue scale), and daily by the patient (four-point rating scale). All symptoms improved to a similar degree in both groups. Differences between the two groups were not statistically significant, except for nasal symptoms in three cases as assessed by the visual analogue scale in one centre (better relief in the group given 120 mg terfenadine once daily). Tolerability was good and similar in both groups. The data presented show that in the treatment of hay fever 120 mg terfenadine given once daily is an effective, convenient and well tolerated alternative to the regimen of 60 mg terfenadine given twice daily.