Biomedical subjects

W Briner

Publications and source records attributed to W Briner.

24 records · Page 2Linked to original sources

PubMedDate not supplied

Ultrastructural features of neurons in the C57BL/6J mouse anteroventral cochlear nucleus: young mice versus old mice with chronic presbycusis.

Transmission electron microscopy was used to examine "bushy" and "multipolar" neurons in the anteroventral cochlear nucleus (AVCN) of young (2-month-old) and old (2-year-old) C57BL/6J mice, a strain that develops profound peripheral sensorineural auditory impairment during the second year of life. Two features differed with age irrespective of cell type or location within the AVCN: there was an increase in the incidence of neurons with heterochromatic nuclei and an increase in the percent of the neuron occupied by lipofuscin. Two features differed with age in multipolar cells only: there was a decrease in the roundness of nuclei and an increase in the number of nuclear invaginations. Some features differed with age to a greater extent in the dorsal portion of the AVCN: there were decreases in the length of terminals on bushy cells, and in the percentage of soma surface apposed by terminals, and increases in the incidence of neurons contacted by myelinated axons, in mean synaptic vesicle density, and in the amount of lipofuscin in bushy cells. Some features did not differ with age: the mean area of mitochondria, percentage of cytoplasm occupied by mitochondria, size of dense synaptic junctions, and for bushy cells only, nuclear shape and invaginations and width of perinuclear cisternae. Aging per se, chronic presbycusis, and neuronal type play roles in determining age-related changes in AVCN neurons.

Age Factors↗

PubMedDate not supplied

Neurodevelopmental effects of lanthanum in mice.

Mice were exposed to lanthanum chloride in drinking water at 0, 125, 250, and 500 mg/liter concentration prior to conception, during gestation, and until 30 days postnatally. Developing mice were assessed for the development of swimming and walking behavior and ear and eye opening. At 30 days of age the mice were assessed with a standard neurologic scale. Differences were found in the emergence of swimming and walking behavior and ear and eye opening. Differences were also found for touch response and visual placing responses. The brains of lanthanum-exposed mice were also smaller than controls. These findings indicate that lanthanum is a potential behavioral teratogen. Possible mechanisms are discussed.

Animals↗

PubMedDate not supplied

Valproate enhances N-cadherin production in Xenopus embryos.

Xenopus embryos were exposed to valproate (0, 20, 40, 80 mg/l) either before or after neural tube closure. The embryos were then homogenized and fractionated by gel electrophoresis, and N-cadherin was detected and measured with quantitative immunoblotting. Findings indicated that valproate exposure increased N-cadherin production in a dose-dependent manner. Embryos exposed prior to neural tube closure tended to be more sensitive to the effects of valproate. These findings suggest that alterations in N-cadherin-mediated adhesion or morphogenesis may partially explain the teratogenic mechanism of valproate.

Animals↗

PubMedDate not supplied

Comparison of the behavior of the curly tail and CBA mouse on a neurologic scale.

ct/ct mice are a mutation of the CBA strain with a high incidence of spina bifida (SB). Because humans with SB can exhibit abnormal behavior, we compared ct/ct and CBA mice using a neurologic assessment tool. ct/ct mice are more active and engage in more climbing, and stereotypical and compulsive behavior. When stimulated during cage removal ct/ct mice react more vigorously. ct/ct mice react more vigorously to a novel stimulus, and will vigorously search for a stable surface during visual placement. In the open field ct/ct mice crossed more lines and reared more than CBA. ct/ct mice demonstrated deficient performance in a modified Morris water maze. No differences were noted for other behaviors tested. The results argue that the mutation that produces SB in ct/ct mice also alters brain structure or chemistry. This is consistent with the findings in humans where SB can produce a variety of behavioral anomalies, most notably hyperactivity, attentional disorders, learning disabilities, and developmental lags.

Animals↗

PubMedDate not supplied

Dyscalculia in patients with vertigo.

This paper reports a hitherto undescribed relationship between vertigo of central origin and dyscalculia. Subjects with vertigo skipped and displaced decades when counting backwards by two. The error is not recognized when presented visually. The subjects also display decrements in ability to do mental arithmetic and in central auditory processing. The results are discussed in light of the relationship between the central vestibular/auditory system and structures involved in higher cognitive function. The relationship between balance disorders and children with learning disabilities is also examined.

Brain Diseases↗

PubMedDate not supplied

Three-dimensional structure of the human vestibular nuclear complex.

We used computer techniques to reconstruct in three dimensions 12 vestibular nuclear complexes (VNC) from serially sectioned brains of 7 patients. Specimens were from 4 patients with vestibular disorders and 3 patients considered vestibular normal. Despite the variety of the patient's otologic histories all the nuclei demonstrated the same shape and structural characteristics.

Aged↗