Biomedical subjects

S Kasas

Publications and source records attributed to S Kasas.

5 recordsLinked to original sources

PubMed1995

A method for anchoring round shaped cells for atomic force microscope imaging.

More and more researchers are interested in imaging living (Henderson, 1994) or fixed cells in their natural environment using the atomic force microscope (AFM). However, the AFM tip interacts strongly with the sample, and its z range freedom is limited to a few micrometers. This means that the cells to be imaged have to be strongly attached to the substrate, and imaging is restricted to cells having a flattened shape. Here we propose a simple and inexpensive solution to overcome these limitations. The method we propose is trapping living round shaped cells in a Millipore filter with a pore size comparable to the dimensions of the cell. The highest part of some of the blocked cells protrude through the holes of the filter and can this way be easily observed using the AFM without detachment.

Micropore Filters↗

PubMed1994

Further ultrastructural evidence that spirochaetes may play a role in the aetiology of Alzheimer's disease.

Recently it was reported that, at autopsy, in neuropathologically confirmed cases of Alzheimer's disease spirochaetes were found in blood and cerebrospinal fluid using dark-field microscopy. Moreover, the spirochaetes were isolated and cultured from brain tissue. We now show, using scanning electron microscopy and atomic force microscopy that the helically shaped microorganisms isolated and cultured from the Alzheimer brains possess axial filaments. This indicates that these microorganisms taxonomically indeed belong to the order Spirochaetales. A morphometric analysis reinforces this notion.

Alzheimer Disease↗

PubMed1993

Observation of living cells using the atomic force microscope.

We used an atomic force microscope (AFM) to image samples immersed in a fluid in order to study the dynamic behavior of the membranes of living cells. AFM images of cultured cells immersed in a buffer were obtained without any preliminary preparation. We observed surface changes and displacements which suggest that the cells were still alive during the measurements. Some membrane details imaged with the AFM have also been observed using a scanning electron microscope and their dynamic behavior has been confirmed by microcinematography. We believe that the AFM will offer new insights into the exploration of dynamic changes affecting cell membranes.

Biophysical Phenomena↗

PubMed1993

[Quantification of the intra-penile smooth muscle with a fuzzy logic algorithm].

We have developed a new computer program for tissue segmentation designed for the quantification of smooth muscle in the corpus cavernosum. The program uses digitalized images of stained histological sections taken with a CCD camera. The recognition of the different tissues is based on the examination of absorption of monochromatic light. The section is successively illuminated with light of three different wavelengths and the three absorption values and texture parameters are used for the identification of the tissue using a fuzzy algorithm.

Absorption↗

PubMedDate not supplied

Discrete reduction patterns of parvalbumin and calbindin D-28k immunoreactivity in the dorsal lateral geniculate nucleus and the striate cortex of adult macaque monkeys after monocular enucleation.

We analyzed the immunohistochemical distribution of the two calcium-binding proteins, parvalbumin (PV) and calbindin D-28k (CB), in the primary visual cortex and lateral dorsal geniculate nucleus (dLGN) of monocularly enucleated macaque monkeys (Macaca fascicularis and Macaca nemestrina) in order to determine how the expression of PV and CB is affected by functional inactivity. The monkeys survived 1-17 weeks after monocular enucleation. The distribution pattern of each of the proteins was examined immunocytochemically using monoclonal antibodies and compared with that of the metabolic marker cytochrome oxidase (CO). We recorded manually the number of immunostained neurons and estimated the concentration of immunoreactive staining product using a computerized image-acquisition system. Our results indicate a decrease of approximately 30% in the labeling of PV-immunoreactive (ir) neuropil particularly in those layers of denervated ocular-dominance columns receiving the geniculocortical input. There was no change in the number of PV-ir neurons in any compartment irrespective of the enucleation interval. For CB-ir, we found a 20% decrease in the neuropil labeling in layer 2/3 of the denervated ocular-dominance columns. In addition, a subset of pyramidal CB-ir neurons in layers 2 and 4B, which are weakly stained in control animals, showed decreased labeling. In the dLGN of enucleated animals, PV-ir and CB-ir were decreased only in the neuropil of the denervated layers. From these results, we conclude that cortical interneurons and geniculate projection neurons still express PV and CB in their cell bodies after disruption of the direct functional input from one eye. The only distinct decrease of PV and CB expression is seen in axon terminals from retinal ganglion cells in the dLGN, and in the axons and terminals of both geniculocortical projection cells and cortical interneurons in the cerebral cortex.

Animals↗