Biomedical subjects

H Nordemar

Publications and source records attributed to H Nordemar.

13 recordsLinked to original sources

PubMed1987

Long-term results after septal surgery--submucous resection versus septoplasty.

Postoperative controls, 5-9 years after surgery, were made in two groups of patients who had undergone submucous septal resection and septoplasty, respectively. The rate of subjective improvement after septoplasty was higher (77%) than after septal resection (66%). In the septoplasty group, however, the experienced surgeons had an improvement rate of 90%, whereas the untrained surgeons had no better results than after submucous septal resection. Postoperative complications, including septal perforation and deformation of the external nose, were significantly fewer after septoplasty. There were no clear-cut correlations between rhinoscopy findings and subjective results at postoperative examinations. The septoplasty technique is advocated, but in the hands of a trained surgeon.

Adolescent↗

PubMed1983

Principles in embryonic development and differentiation of vestibular hair cells.

The early development and maturation of vestibular hair cells in the CBA/CBA mouse were analyzed at the ultrastructural level with conventional transmission electron microscopy and freeze fracturing. Cells differentiating into future hair cells pass their terminal mitosis close to the otocyst lumen. The earliest morphologic sign of differentiation into future hair cells was the arrangement of microvilli in a regular fashion. Hair cell cytodifferentiation occurred with a gradient from the hair cell surface to the base. In parallel with the maturation of sensory hairs a structural intracellular rebuilding occurred: the number of polyribosomes and amount of rough endoplasmic reticulum decreased, the nucleus moved basally, and mitochondria accumulated in the supranuclear region. Both tight junctions and gap junctions occurred initially on developing hair cells. From the sixteenth gestational day on, gap junctions disappeared, indicating an uncoupling phenomenon. Afferent nerve terminals developed before efferent nerve endings. Maturation of innervation occurred, for the most part, postnatally, and after that hair cells reached mature morphology.

Animals↗

PubMed1981

Biochemical studies on the embryonic development of the mammalian inner ear in organ culture.

Adenylate cyclase activity and phospholipid labeling were compared during embryonic development of the mouse inner ear in vivo and in vitro. Inner ears were explanted on the 16th gestational day and cultured in vitro for 3-12 days. The gestation time in vivo is 21 days. During the 1st week in vitro there is very little growth of the inner ear with regard to total protein content. In contrast, the labyrinth increases its protein content threefold during the corresponding period of time in vivo. The activity of adenylate cyclase develops parallel in vivo and in vitro until the 19th gestational day whereafter the specific activity of the enzyme in vitro surpasses that of the enzyme in vivo three- to fivefold suggesting a lack of control mechanisms in organ culture. Phospholipids are labeled by 32P in an essentially similar quantitative relationship in vivo and vitro, while some quantitative differences exist. According to the present study the usefulness of the organ culture for the investigation of inner ear development appears limited to a culture period corresponding to an age prior to birth.

Adenylyl Cyclases↗

PubMed1981

Ototoxicity or teratogenicity. An analysis of drug-induced effects on the early development of the mammalian otocyst.

The 13th gestational day inner ear (otocyst stage) is particularly vulnerable to toxic influence from the environment during its further development. Ethacrynic acid in a concentration of 1 and 10 micrograms/ml caused complete arrest in development, and this was not overcome when withdrawing the drug after in vitro exposure to ethacrynic acid during 3 days. Gentamicin exposure at 1 and 10 micrograms/ml caused dysmorphogenesis but did not inhibit cytodifferentiation which, however, often was poor. Higher concentrations of gentamicin (100 micrograms/ml) had a more generalized toxic effect not only on epithelial but also on mesenchymal tissue.

Abnormalities, Drug-Induced↗

PubMed1980

Embryogenesis of the inner ear. IV. Post-natal maturation of the secretory epithelia of the inner ear in correlation with the elemental composition in the endolymphatic space.

The rise of the potassium concentration in the endolymphatic space occurred between the 4th and 8th day after birth (DAB). During this time morphological maturation of the stria vascularis was ended. The increasing concentration of potassium in the developing endolymph parallelled in the vestibular and cochlear parts of the labyrinth. The dark cell epithelium surrounding vestibular organs was, however, ultrastructurally mature at birth except for an increase of the number of intercellular digitations toward the basal membrane maturing during the first days postpartum. The maturation of endolymph thus took place prior to the development of the endocochlear potential.

Animals↗

PubMed1979

Genesis and maturation of vestibular hair cells.

The embryologic development in vivo and in vitro of mammalian hair cells in the crista ampullaris was continuously followed with regard to structural differentiation and maturation from the terminal mitosis to the morphological condition at partus or equivalent age in vitro. Otocysts were explanted both early and late during embryologic development: 13th and 16 gestation day, respectively. Both in fetal life and during in vitro conditions, the surface structures of the developing hair cell with regular arrangement of kinocilium/stereocilia were first differentiated, followed by a cytologic transformation intracellularly and subsequent development of nerve endings. Hair cells were able to develop without any morphologic contact with the nervous system. The afferent nerve system developed before the efferent nerve system (CBA/CBA mouse).

Animals↗

PubMed1979

Embryogenesis of the inner ear. I. Development and differentiation of the mammalian crista ampullaris in vivo and in vitro.

The embryonic development of the crista ampullaris in the CBA/CBA mouse was followed comparatively in vivo and in vitro after explanation of the 13th gestational day otocyst. Special attention was paid to hair cell differentiation. In general the in vivo and the in vitro groups of inner ears showed a similar morphological maturation of hair cells on the ultrastructural level. The first sign of hair cell differentiation occurred on the 14th day in vivo and after 1 day in culture showing a thickening of microvilli presumably indicating the development of future sensory hairs. On the 16th day or after 3 days of in vitro culture the sensory hairs were regularely arranged with the kinocilium located at the cell periphery. Afferent nerve endings were identified on the 17th gestational day and some nerve terminals were suspected to be of efferent character appearing on the 18th day. On the day of birth there did not occur complete nerve chalices but a differentiation of hair cells into type I and II was indicated on the 19th gestational day by a slight difference in hair cell configuration and extension of innervation.

Animals↗

PubMedDate not supplied

Formation of the cupula cristae ampullaris: development in vivo and in vitro.

The development of the cupula cristae ampullaris in the mouse starts on the 14th gestational day and occurs mainly during the 15th and 16th gestational days. Subsequently the secretory activity of the epithelial cells diminishes. The cupula is formed from the underlying epithelium when there are only a small number of differentiated hair cells present. Secretion of cytoplasmic material occurs mainly from supporting cells. The surface of the epithelium at a location corresponding to the planum semilunatum in the adult organ has a thick layer of microvilli and demonstrates a particularly high secretory activity on the 15th gestational day. After the 16th gestational day there are few morphologic signs of secretion. The cupula also develops in inner ear anlages that have been explanted at the otocyst stage on the 12th or 13th gestational day and cultured for eight days in vitro.

Animals↗

PubMedDate not supplied

Organ culture of the 16th gestation day mouse labyrinth. A model suggestion for pre- and post-partum development.

The 16th day mouse embryo inner ear was explanted and cultured "in vitro" for 6 days, which corresponds to 1 day post-partum development "in vivo". A normal development occurred both when the inner ear anlage was divided into a vestibular and a cochlear portion and when it was cultured as a whole. The present model system may provide a helpful tool in the study of both normal development and inner ear pathology.

Animals↗

PubMedDate not supplied

Postnatal development of the vestibular sensory epithelium in the mouse.

The vestibular epithelium of the CBA/CBA mouse was analyzed from birth until the adult stage. Hair cells type I and type II develop in parallel. Initially, the innervation progresses rapidly post partum. A few mature type I hair cells with fully developed nerve calyces occur 4 days post partum. An early temporary innervation of both type I and type II hair cells occurs and is later rebuilt forming mature nerve endings and nerve calyces. Synaptic bodies develop within the cytoplasm of hair cells without the contact of nerve endings. Efferent nerve endings develop late on both type I and type II hair cells and moreover are few in the adult animal. The vestibular epithelium is not completely mature until 3-4 weeks post partum.

Animals↗

PubMedDate not supplied

Organ culture of the late embryonic inner ear as a model for ototoxicity studies.

The 16th gestational day inner ear of the CBA/CBA mouse was used in an organ culture system as a model for ototoxicity studies. The specimens in culture were exposed to 1, 10, 100 and 1 000 micrograms/ml of gentamicin base during 1-5 days in culture. Minor changes were found after only one day of exposure. Pathological changes of vestibular hair cells characteristic for aminoglycoside antibiotics occurred after exposure to 1 and 10 micrograms/ml. Concentrations of 100 and 1 000 micrograms/ml caused a general toxicity with destruction of the whole morphology of the crista ampullaris. Hair cells were, however, more affected than were supporting cells. Initially, variation of hair cell damage occurred within each crista and between different cristae but this became less apparent after 5 days in culture. The 16th gestational day organ culture system can serve as a useful model system with many controlled experimental parameters in the testing of ototoxic drugs.

Animals↗

PubMedDate not supplied

Embryogenesis of the inner ear. II. The late differentiation of the mammalian crista ampullaris in vivo and in vitro.

The embryonic development of the crista ampullaris of the CBA/CBA mouse was followed both in organ culture of explanted inner ears of the 16th gestational day and in vivo from the 16th gestational day until the 21st day, an age corresponding to birth. Cytodifferentiation of the sensory epithelium of the crista ampullaris occurs during this period. At partus, there is a rather mature crista with well developed hair cells and 1-2 layers of supporting cells. Innervation and differentiation into type I and type II hair cells have started prior to partus but occur mainly post partum. The in vitro development followed that of the in vivo but with a slight delay, especially concerning the later stages of the in vitro development. At the time corresponding to partus, differentiation of hair cells is almost identical in the two groups but innervation is delayed in the in vitro group of inner ears. Because of the very high reproducibility/stability in vitro and morphologic maturation of both hair cells and gross structure of the crista ampullaris, organ culture of the 16th gestational day inner ear explant is a suitable model in the study of the late embryonic development under normal and pathological conditions.

Animals↗

PubMedDate not supplied

Alcohol and ultrastructural changes in the developing inner ear. An in vitro study.

Inner ear explants from the CBA/CBA mouse were used in an organ culture system. The explants were cultured from the 16th gestational day until one day post partum. They were exposed to 1.5% or 3% ethanol in organ culture medium in order to determine any possible toxic effects upon the differentiating sensory structures of the sensory epithelium of the inner ear, that could be correlated to fetal alcohol syndrome. The higher concentration of ethanol caused a general and possibly unspecific destruction of the sensory epithelium, while the lower concentration caused characteristic changes including intracellular edema or vacuolization, especially confined to hair cells. Pathologic changes seemed dose-related but not time-related.

Animals↗