Biomedical subjects

L B Nabors

Publications and source records attributed to L B Nabors.

3 recordsLinked to original sources

PubMed1991

A unique neuronal organization in the cat pretectum revealed by antibodies to the calcium-binding protein calbindin-D 28K.

The pretectum is an important center for visual reflexes. However, the location, boundaries, and connections of individual nuclei of the pretectum are incompletely understood. In cat, the traditionally defined nuclear boundaries have been placed in doubt by recent evidence showing that the retinal input to the pretectum forms four continuous projection zones that do not match the cytoarchitectural boundaries of individual pretectal nuclei defined by previous studies. We now show that antibodies to the calcium-binding protein calbindin-D 28K (CaBP) label clusters of neurons within the pretectum that match the zones of retinal termination. Four obvious cell clusters within the pretectum were labeled by CaBP antisera. Computer three-dimensional reconstruction of these cell clusters revealed that they form four distinct but continuous zones that run the rostrocaudal length of the pretectum in a medial-to-lateral direction. By combining anterograde HRP labeling of retinal terminals with CaBP immunocytochemistry, these CaBP-labeled cell clusters were found virtually to overlap the retinal projection zones. The CaBP-labeled neurons included both multipolar and fusiform morphologies, and most were medium- to large-sized cells. HRP retrograde transport studies showed that many CaBP-labeled neurons in the clusters projected to the LGN, while none projected to the inferior olive (IO). GABA-immunoreactive neurons were also found within the CaBP cell clusters, but these neurons were smaller than most CaBP-labeled neurons, and none were retrogradely labeled following HRP injections into the LGN or IO. Two-color antibody double-labeling experiments did not reveal any GABA neurons within the clusters that colocalized CaBP. In summary, calbindin is a precise marker of neuron clusters that overlap the retinal projection zones in the cat pretectum. Many of these CaBP neurons project to the LGN, and none contain GABA.

Animals↗

PubMed1988

Quantitative immunocytochemistry using an image analyzer. I. Hardware evaluation, image processing, and data analysis.

In this review we describe how video-based image analysis systems are used to measure immunocytochemically labeled tissue. The general principles underlying hardware and software procedures are emphasized. First, the characteristics of image analyzers are described, including the densitometric measure, spatial resolution, gray scale resolution, dynamic range, and acquisition and processing speed. The errors produced by these instruments are described and methods for correcting or reducing the errors are discussed. Methods for evaluating image analyzers are also presented, including spatial resolution, photometric transfer function, short- and long-term temporal variability, and measurement error. The procedures used to measure immunocytochemically labeled cells and fibers are then described. Immunoreactive profiles are imaged and enhanced using an edge sharpening operator and then extracted using segmentation, a procedure which captures all labeled profiles above a threshold gray level. Binary operators, including erosion and dilation, are applied to separate objects and to remove artifacts. The software then automatically measures the geometry and optical density of the extracted profiles. The procedures are rapid and efficient methods for measuring simultaneously the position, geometry, and labeling intensity of immunocytochemically labeled tissue, including cells, fibers, and whole fields. A companion paper describes non-biological standards we have developed to estimate antigen concentration from the optical density produced by antibody labeling (Nabors et al., 1988).

Animals↗

PubMed1988

Quantitative immunocytochemistry using an image analyzer. II. Concentration standards for transmitter immunocytochemistry.

Image analyzers can measure both the optical density and geometry of immunocytochemically labeled cells and fibers, as reviewed in a companion paper (Mize et al., 1988). In this paper, we report a procedure which allows us to estimate the concentration of a neurotransmitter based upon the optical density of antibody labeling produced by immunocytochemistry. To accomplish this, we developed a standard which binds conjugated neurotransmitters. Several artificial media for the standard were compared, including agar, gelatin, and agar-gelatin. A 3% agar matrix was found to be most suitable because it cut well and was nearly transparent. The agar sections were activated with cyanogen bromide/acetonitrile to promote coupling to the antigen. To test the standard, we used gamma-aminobutyric acid (GABA) conjugated to bovine serum albumin (BSA) as the antigen. The antibody was directed against this conjugate. Activated agar sections were incubated in serial dilutions of the tritium-labeled GABA/BSA conjugate. The radioactivity of some of these sections was measured to estimate the amount of coupled antigen. The remaining sections were incubated in the GABA antibody and processed for immunocytochemistry. The optical density of these sections was measured with an image analyzer. A linear relationship was found between GABA concentration and optical density over a range of at least 0.01 to 1 nmol/mg of agar. These results show that the concentration of bound GABA can be estimated from the optical density of sections labeled by antibody immunocytochemistry. The applicability of this technique to fixed brain tissue is discussed.

Image Processing, Computer-Assisted↗