Biomedical subjects
Publications and source records attributed to M R Celio.
Human fetal tissue fixed with Bouin and kept for 30 years in ethanol is still useful in immunohistochemistry. The localization of beta-endorphin immunoreactive cells in the pituitary is given as example.
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The ultrastructure of the synapses formed by the Mauthner axon collateral (MAC) was examined in the goldfish spinal cord. All such collaterals form axo-dendritic chemical synapses with dendrites of motor and interneurons. Besides these chemical synapses, contacts have been found between some MAC and axons of interneurons, which can be characterized as gap junctions with presumed electrical transmission. All cellular processes contacted by the MAC contain 'dense bands' of material in their cytoplasm. These 'dense bands' are absent from other parts of the fish C.N.S. These observations and the peculiar synaptic pattern are discussed and correlated with electrophysiological results.
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The myelin sheath of the Mauthner axons in the spinal cord of young and adult fish belonging to the family Cyprinidae was examined by phase and electron microscopy. The sheath thickened considerably with age, the number of lamellae increasing from 200-230 in young fish (length 2--4 cm) to 250-300 in adult animals (length 20-25 cm). During this growth, the myelin sheath remained fairly compact and of optimal thickness for impulse propagation, the axon/fiber thickness ratio being 0.67-0.72 in young and 0.76-0.78 in adult fish. As already observed by previous investigators, the Mauthner axons lacked nodes of Ranvier. However, Schmidt-Lantermann's clefts (SLC) were present at irregular intervals. Within the SLC, parallel arranged osmiophilic bands of variable length and with a thickness of approx. 42-44 nm were observed to form a transitional zone between the cytoplasmic areas of the oligodendrocyte and the typical myelin structure. Between such adjacent 'D-bands', which thinned out to build up the major dense lines, an electron translucent area measuring approx. 25--26 nm in width contained a thin 'I-band' (8--10 nm) which was continuous with the intraperiod line. It is speculated that, in the Mauthner axon, the SLCs may be sites where freshly synthesized myelin is added to the lamellae already present, thus permitting their longitudinal growth.
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.
Recently, it has been shown that natural and synthetic deoxynucleotide polymers can adopt a left-handed helical structure (termed Z-DNA) in appropriate conditions (see, for example, refs 1 and 2 and the references therein). In contrast to the more familiar right-handed B-DNA, Z-DNA is strongly immunogenic, and polyclonal and monoclonal antibodies against Z-DNA have been elicited. By using such antibodies, immunoreactivity for Z-DNA has been detected in the polytene chromosomes of two dipteran species, in the macronucleus of a ciliated protozoon, and in certain plant nuclei (cited in ref. 11). In view of the possible importance of Z-DNA as a genomic regulatory signal, it would be highly desirable to know whether Z-DNA also occurs in mammals. We have therefore initiated an immunohistochemical study of various rat tissues by using three antisera specific for Z-DNA, and the peroxidase-antiperoxidase technique for visualization of tissue-bound antibodies. Here we demonstrate that the nuclei of many, but not all, types of rat cells exhibit Z-DNA immunoreactivity, suggesting that Z-DNA may exist naturally in mammalian chromatin.
Calcium ions have a pivotal role in many neuronal activities, but little is known about their involvement in the cortical processing of visual information. Using immunohistochemical methods, we have now detected a calcium-binding protein, calbindin-D-28K, which may confer on certain compartments of cortical area 17 the ability to modulate Ca2+ metabolism. Thus, calbindin occurs in the primate striate cortex in a pattern almost complementary to that displaying strong cytochrome c-oxidase activity. From this and other observations, we deduce that the distribution of calbindin-immunoreactive sites corresponds mainly to extra-geniculocortical connections of the primary visual cortex. This implies that the geniculocortical and extra-geniculocortical compartments of area 17 differ in an intracellular system for Ca2+ homeostasis.
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It is astonishing how a single ion, Ca++, can give rise to so many intracellular effects. The current explanation is that various combinations and permutations of a repertoire of calcium channels, calcium binding proteins and calcium pumps make up the individual answer of each neuronal type to the calcium signal. This review describes the major calcium binding proteins of the brain, which represent intracellular tools to decipher and transform the quantitative Ca+(+)-signal in qualitatively different cellular responses.
The existence of angiotensin II (AII) immunoreactivity in juxtaglomerular (JG) cells of rat kidney, which has been demonstrated previously by immunohistochemical studies, can be explained either as the product of intracellular synthesis or by the internalization of receptor-bound AII originating in plasma. To resolve these two alternative mechanisms, attempts were made to identify AI in JG cells of rat kidney by immunohistochemical staining using specific antibodies to AI. Although AI-like immunoreactivity was not detected in normal rat kidney, rats treated with the angiotensin-converting enzyme inhibitors, MK-421 or captopril, showed AI-like immunoreactivity in JG cells. The presence of renin and AII-like immunoreactivity was demonstrated in the same cells by specific antibodies to respective antigens used on adjacent serial sections. These findings support an intracellular mechanism of the formation of AII and suggest an intracellular renin angiotensin system, presumably separate from the extracellular system.
We searched for the presence of calretinin (CR) in 12 colonic cancer cell lines using immunohistochemistry, Western blot analysis and the reverse transcriptase-polymerase chain reaction (RT-PCR). We were able to demonstrate that calretinin is expressed in the cell lines HT-29, WiDr, LoVo, LS180, CO112, CO115. SW480, SW620, COLO205 and SK-CO-1, while no detectable amounts were found in the cell lines SW1116 and Caco-2. In general, rapidly proliferating cell lines expressed calretinin, whereas the protein was absent from cell lines with a low multiplication rate. A possible role for calretinin in maintaining the proliferative cycle of tumor cells is discussed.
BACKGROUND: Calretinin-22k (CR-22k), an alternatively spliced form of calretinin (CR) belongs to the EF-hand family of calcium-binding proteins and is expressed in several colon adenocarcinoma cell lines (e.g. WiDr, HT-29). MATERIALS AND METHODS: Serum samples of cancer patients were screened with a sandwich ELISA technique using the CR-specific antiserum 7696. Highly positive samples were analyzed by Western blots and immunohistochemistry. RESULTS: CR-22k was detected in the serum of several patients and values were as high as 0.19 microgram/ml. Western blot analysis confirmed the identity of the bound protein as CR-22k. The highest concentrations were detected in patients with colon or breast cancer, but also in a patient with ischemic necrosis of the gut. CR immunoreactivity was localized to epithelial cells, nerve fibres, cells of the connective tissue and to mesothelial cells. CONCLUSIONS: Our results establish that CR-22k is detectable in the serum of cancer patients under specific pathological conditions.