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Biomedical subjects

L L Wright

Publications and source records attributed to L L Wright.

102 records · Page 6Linked to original sources
PubMed1979

Age differences in the effects of perceptual noise.

Elderly (60 to 82 years) and young (18 to 25 years) subjects were tested on a visual task in which noise items were present but did not require processing to test the hypotheses that elderly persons have more difficulty ignoring irrelevent stimuli and suppressing response competition than do younger persons. Tachistoscopically presented displays contained a precued central target letter either alone or flanked by noise items that required (1) a response the same as, or (2) opposite to that required by the target letter, or (3) did not require a response in this task. No evidence was found to support differentially greater response slowing by the elderly due to the presence of irrelevant stimuli. Elderly persons showed significantly less effects of response competition, suggesting that the two groups processed the task information differently. The results suggest that age differences in effects of perceptual noise and response competition are not general phenomena, but depend upon the demand characteristics of the specific task.

Adolescent↗
PubMed1978

Staphylococcal protein A-sepharose columns and the characterization of measles virus-specific polypeptides in persistently infected cells.

Viral polypeptides in extracts prepared from [35S]methionine-labeled human epithelial carcinoma cells persistently infected with measles virus were reacted with virus-specific antisera. Microcolumns of staphylococcal protein A linked to Sepharose were used to isolate antigen-antibody complexes that contained few contaminating host polypeptides. Measles virus polypeptides in these complexes could be identified readily on sodium dodecyl sulfate-polyacrylamide gels even when antiserum with low reactivity toward the viral antigens was used.

Animals↗
PubMed1978

Measles virus nucleocapsids: large-scale purification and use in radioimmunoassays.

Nucleocapsids in quantities approaching 1 mg were purified from 109 measles virus-infected cells. They contained one polypeptide species with a molecular weight of 59,000. Antiserum was raised in rabbits against purified nucleocapsids and used in a competitive radioimmunoassay. Because of their instability, purified nucleocapsids were not suitable for use in such an assay. Instead partially purified nucleocapsids from HEp-2 cells persistently infected with measles virus and labeled in vitro with [35S]methionine were used as the source of radioactive antigen. The radioimmunoassay thus developed measured less than 5 ng of nucleocapsids in infected cells.

Animals↗
PubMed1977

Interactive effects of parity and pup stress on the maternal behavior of Rattus norvegicus.

Litters of primiparous and multiparous rat mothers received 0,2, or 5 min of cold stress for the 1st 5 days postpartum. Primiparae showed increasing maternal responsiveness over the treatment period. Multiparae were initially maternally responsive to moderate stress cues from pups, but habituated to them over days. From Days 6 to 20, when pups were not stressed, lactation behavior of stressed groups declined in primiparous mothers but not in multiparous mothers.

Animals↗
PubMed1977

Age and sex differences in cerebral asymmetry as a function of competition for "time" and "space" in a successive auditory matching task.

Subjects in three age groups identified verbally encoded (VE) and nonverbally encoded (NVE) stimuli as "same" or "different". Matching times increased with age, but differentially for men and women and VE and NVE stimuli. Evidence for asymmetry effects occurred for middle age and older men, but only when a secondary memory task produced competion for "time" and "space" in the left hemisphere.

Adult↗
PubMedDate not supplied

The DAPI-3 amacrine cells of the rabbit retina.

In the rabbit retina, the nuclear dye, 4,6,diamidino-2-phenylindole (DAPI), selectively labels a third type of amacrine cell, in addition to the previously characterized type a and type b cholinergic amacrine cells. In this study, these "DAPI-3" amacrine cells have been characterized with respect to their somatic distribution, dendritic morphology, and neurotransmitter content by combining intracellular injection of biotinylated tracers with wholemount immunocytochemistry. There are about 100,000 DAPI-3 amacrine cells in total, accounting for 2% of all amacrine cells in the rabbit retina, and their cell density ranges from about 130 cells/mm2 in far-peripheral retina to 770 cells/mm2 in the visual streak. The thin varicose dendrites of the DAPI-3 amacrine cells form a convoluted dendritic tree that is symmetrically bistratified in S1/S2 and S4 of the inner plexiform layer. Tracer coupling shows that the DAPI-3 amacrine cells have a fivefold dendritic-field overlap in each sublamina, with the gaps in the arborization of each cell being occupied by dendrites from neighboring cells. The DAPI-3 amacrine cells consistently show the strongest glycine immunoreactivity in the rabbit retina and they also accumulate exogenous [3H]-glycine to a high level. By contrast, the AII amacrine cells, which are the best characterized glycinergic cells in the retina, are amongst the most weakly labelled of the glycine-immunopositive amacrine cells. The DAPI-3 amacrine cells costratify narrowly with the cholinergic amacrine cells and the On-Off direction-selective ganglion cells, suggesting that they may play an important role in movement detection.

Animals↗
PubMedDate not supplied

The fountain amacrine cells of the rabbit retina.

We have characterized a distinctive type of bistratified amacrine cell in the rabbit retina at both the single cell and population levels. These cells correspond to the "fountain" amacrine cells recently identified by MacNeil and Masland (1998). The fountain cells can be distinguished in superfused retinal wholemounts labeled with nuclear dyes, thus enabling them to be targeted for intracellular injection with Neurobiotin. This revealed that the primary dendrites ascend steeply to sublamina b of the inner plexiform layer, where they form an irregular arbor at the border of strata 4 and 5. These dendrites then give rise to multiple varicose processes that descend obliquely to sublamina a, where they form a more extensive arbor in stratum 1. The fountain amacrine cells show strong homologous tracer coupling when injected with Neurobiotin, and this has enabled us to map their density distribution across the retina and to examine the dendritic relationships between neighboring cells. The fountain amacrine cells range in density from 90 to 360 cells/mm2 and they account for 1.5% of the amacrine cells in the rabbit retina. The thick tapering dendrites in sublamina b form highly territorial arbors that tile the retina with minimal overlap, whereas the thin varicose processes intermingle in sublamina a. The fountain cells are immunopositive for y-aminobutyric acid and immunonegative for glycine. We further propose that these cells are homologous to the substance P-immunoreactive (SP-IR) amacrine cells in the cat retina and that they may account for a subset of the SP-IR amacrine cells in the rabbit retina.

3,3'-Diaminobenzidine↗
PubMedDate not supplied

The fountain amacrine cells of the rabbit retina.

We have characterized a distinctive type of bistratified amacrine cell in the rabbit retina at both the single cell and population levels. These cells correspond to the "fountain" amacrine cells recently identified by MacNeil and Masland (1998). The fountain cells can be distinguished in superfused retinal wholemounts labeled with nuclear dyes, thus enabling them to be targeted for intracellular injection with Neurobiotin. This revealed that the primary dendrites ascend steeply to sublamina b of the inner plexiform layer, where they form an irregular arbor at the border of strata 4 and 5. These dendrites then give rise to multiple varicose processes that descend obliquely to sublamina a, where they form a more extensive arbor in stratum 1. The fountain amacrine cells show strong homologous tracer coupling when injected with Neurobiotin, and this has enabled us to map their density distribution across the retina and to examine the dendritic relationships between neighboring cells. The fountain amacrine cells range in density from 90 to 360 cells/mm2 and they account for 1.5% of the amacrine cells in the rabbit retina. The thick tapering dendrites in sublamina b form highly territorial arbors that tile the retina with minimal overlap, whereas the thin varicose processes intermingle in sublamina a. The fountain cells are immunopositive for gamma-aminobutyric acid and immunonegative for glycine. We further propose that these cells are homologous to the substance P-immunoreactive (SP-IR) amacrine cells in the cat retina and that they may account for a subset of the SP-IR amacrine cells in the rabbit retina.

3,3'-Diaminobenzidine↗
PubMedDate not supplied

A quick strep test.

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Humans↗