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At least 19 recordsLinked to original sources
PubMed1975

[Neuronal organization of the large-cell segment of the cat's red nucleus].

When studying the neuronal organization of the large-cell part of the red nucleus in cats by the Golgi and Golgi-Kopsch methods three types of neurons have been revealed: large (50-90 mu), medium-sized (20-50 mu) and small cells (8-20 mu). long axon and short-axon neurons were found as well as long-dendrite cells with few thorns (the length of the dendrites form 600-900 mu) and short-dendrite cells (up to 400 mu). On basis ofanalysis of neuronal groups found in the large-cell part of the red nucleus of the cat a neuronal map of this part of the central nervous sytem is composed.

Animals↗
PubMed1992

[Surgical stress stimulates release of polymorphonuclear leukocyte elastase from a segmented neutrophil].

The studies were performed to find out whether increased serum levels of polymorphonuclear leukocyte elastase (PMNE) depend on increase of segmented neutrophils or increase of PMNE release from a segmented neutrophil on 17 patients for various elective surgeries. Serum levels of PMNE, leukocyte count and leukogram were determined before incision (preoperation), as well as on the 1st, 3rd and 5th day after operation. Serum levels of PMNE, segmented cell count, stab cell count, stab cell-segmented cell ratio increased most on the 1st postoperative day and decreased thereafter. Leukocyte count showed no significant changes. Serum levels of PMNE correlated well with PMNE released from a segmented neutrophil, but not with leukocyte count or segmented cell count. It was concluded that increased serum levels of PMNE by surgical stress depend on the increased PMNE release from a segmented neutrophil but not on the increased segmented cell count.

Adult↗
PubMed1990

Intrinsic segmental identity of segmental founder cells of the leech embryo.

Segmentation occurs in several animal phyla, and the cellular mechanisms generating this structural periodicity vary considerably. In the leech, an annelid worm, segmental founder cells arise through a fixed cell lineage (Fig. 1), and come together in a longitudinally repeating array through a stereotyped pattern of morphogenesis. In this paper we demonstrate that founder cells forced to differentiate in a foreign segmental environment give rise to their normal, segment-specific clones of neuronal descendants, even in segments in which those neuronal phenotypes would not normally be observed. These findings indicate that the individual founder cells possess segmental identity at or shortly after the time of their birth, and further suggest that such identities are established by a mechanism in which the parent stem cell 'counts' mitotic cycles.

Animals↗
PubMed1977

Bone marrow cell scene segmentation by computer-aided color cytophotometry.

Computer scene segmentation of touching cell images in bone marrow, on the basis of color information, is achieved using digitized scans at three different wavelengths of light. With trivariate histograms and Euler's coordinate transformation, it is possible cytophotometrically to isolate, on the basis of chromatic differences, individual heterogeneous cells located in cell groups. The ability of the described computer methods to isolate correctly the touching cell images is determined by visual comparison of the cells as seen in the microscope and the computer-generated displays of the scanned and segmented scenes.

Bone Marrow Cells↗
PubMed1992

Acetazolamide inhibition of basolateral Cl-/HCO3- exchange in rabbit renal proximal tubule S3 segment.

Cell pH (pH(i)) and cell membrane potential (Vb) were measured in isolated S3 segments of rabbit renal proximal tubule with double-barrelled microelectrodes to search for a possible effect of the carbonic anhydrase inhibitor, acetazolamide (ACZ), on Cl-/HCO3- exchange in the basolateral cell membrane. ACZ was found to retard and reduce the pH(i) response to bath Cl- removal reversibly with half-maximal inhibition at 0.42 mmol/l and a rather flat concentration dependence (Hill coefficient approximately 0.36). To determine whether the retardation resulted from inhibition of cytoplasmic carbonic anhydrase, which might have delayed the attainment of HCO3-/CO2 equilibrium, we have measured the response of pH(i) to step changes in PCO2 in the presence and absence of ACZ. ACZ greatly retarded the pH(i) response to CO2 steps; however, the concentration dependence differed (half-maximal inhibition at 18 mumol/l) and even at maximal ACZ concentrations the response to CO2 steps was more than twice as fast as the response to Cl- replacement. Since, in addition, the ACZ inhibition of Cl-/HCO3- exchange could not be overcome by increasing PCO2 we conclude that the ACZ effect on Cl-/HCO3- exchange in rabbit proximal tubule S3 segments does not result from inhibition of cytosolic or membrane-bound carbonic anhydrase, but from a direct interaction with the exchanger molecule.

Acetazolamide↗
PubMed1979

Membrane-dependent guanine nucleotide binding and GTPase activities of soluble protein from bovine rod cell outer segments.

Soluble proteins can be extracted by osmotic shock of purified rod (photoreceptor cell) outer segments that have intact plasma membranes. The soluble proteins include a component that contains tightly bound GDP-Exchange of this GDP with exogenous nucleotide is catalyzed by (and requires) the membranes from the outer segments. ATP does not participate in these reactions. Approximately one-half of the binding sites in the soluble component require GTP as the source of exogenous nucleotide; the remainder accept GTP or GDP with equal facility. When exogenous GTP is the source of bound nucleotide, it is found in the complex in the form of GDP. Exchange of bound nucleotide with GTP is stoichiometrically related to GTPase activity; this activity is highly dependent upon the presence of both membranes and soluble protein. The soluble nucleotide binding protein was purified by making use of the fact that it binds tightly to the membranes (under conditions of moderate ionic strength) in the absence of GTP and can be eluted by solutions containing low concentrations of GTP (but not GDP or ATP, nor can it be eluted by GTP-free solutions of low ionic strength). The purified protein contains two polypeptide chains of molecular weights 41,000 and 37,000; these are the major species that can be extracted from the outer segments by osmotic shock, and they constitute approximately 7% of the total protein of the isolated organelle.

Animals↗
PubMed1976

Physiological properties and receptive fields of mechanosensory neurones in the head ganglion of the leech: comparison with homologous cells in segmental ganglia.

A study of the head ganglion of the leech was made to compare the properties of specific sensory cells in this ganglion with those of homologous neurones in the segmental ganglia. 1. In the head ganglion, cells were identified that had electrical properties, sensory modalities and adaptation properties similar to those of touch (T), pressure (P) and nociceptive (N) cells in the segmental ganglia. The cell bodies of these neurones were situated in characteristics positions that could be correlated with those in the segmental ganglia. Several lines of evidence suggested that they were primary sensory neurones. Fewer T, P and N neurones were identified in the head ganglion than would be expected from its six constituent segmental ganglia. 2. The receptive fields of identified T, P and N cells were situated on the external surface of the head and the interior of the mouth with considerable overlap. They were generally smaller in size than those situated on the main part of the body. The receptive fields were also displaced anteriorly so that some of them were situated in segments anterior to those of the innervating cells. 3. The morphology of the sensory cells in the head ganglion was studied by intracellular injection of horseradish perioxidase. The general branching characteristics of the cells and the structural appearance of their processes resembled those of homologous cells in the segmental ganglia. However, the routes taken to the periphery by some of the cells were not constant from head ganglion to head ganglion. This variability was confirmed by electrophysiological evidence, and differed from the constancy seen in segmental sensory cells.

Action Potentials↗
PubMed1992

Analysis of HIV particle formation using transient expression of subviral constructs in mammalian cells.

Segments of the human immunodeficiency virus (HIV) type 1 gag and pol genes and mutants thereof were transiently expressed in mammalian cells. Expression was dependent on the presence of the rev responsive element in cis and the rev protein in trans and was readily detected by indirect immunofluorescence or Western blotting. Transfection of constructs encoding the entire gag and pol open reading frames yielded efficient release of particles banding at a density of 1.16 g of sucrose per milliliter and consisting mainly of processed gag proteins. In addition, these particles contained the p66/p51 heterodimer of reverse transcriptase (RT), had associated RT activity, and contained RNA. Electron micrographs revealed immature retrovirus-like particles budding primarily from the plasma membrane and extracellular particles with morphological characteristics of HIV. Particle production was independent of the pol open reading frame or an active HIV proteinase (PR) but without active PR, cell-associated and particle-associated proteins remained completely uncleaved and budding occurred primarily into intracellular vacuoles. A mutation preventing myristoylation of the viral polyproteins abolished particle release but did not interfere with polyprotein synthesis and did not prevent processing. Expression of gag and PR in the same reading frame yielded complete processing of polyproteins but no budding and led to increased cell toxicity. A mutation of the PR active site in this construct prevented cytotoxicity and restored particle release indicating that the observed phenotype was caused by the overexpression of PR. These particles were aberrant in size and morphology when analyzed on sucrose density gradients and by electron microscopy. Budding was arrested at an early stage and extracellular particles appeared to be released by a different mechanism. Only short C-terminal extensions were compatible with this release mechanism since expression of a similar mutant construct encoding the entire gag-pol open reading frame did not yield particles.

Animals↗
PubMed1979

A thresholding method for automatic cell image segmentation.

An algorithm for automatic segmentation of PAP-stained cell images and its digital implementation is described. First, the image is filtered in order to eliminate the granularily and small objects in the image which may upset the segmentation procedure. In a second step, information on gradient and compactness is extracted from the filtered image and stored in three histograms as functions of the extinction. From these histograms, two extinction thresholds are computed. These thresholds are suitable to separate the nucleus from the cytoplasm, and the cytoplasm from the background in the filtered image. Masks are determined in this way, and finally used to analyse the nucleus and the cytoplasm in the original image.

Cell Compartmentation↗
PubMed1978

Further scanning electron microscope studies of lizard auditory papillae.

The papillae basilares of 12 species of lizards from seven different families were studied by SEM. The iguanids, Sceloporus magister and S. occidentalis, have typical "iguanid type" papillae with central short-ciliated unidirectional hair cell segments and apical and basal long-ciliated bidirectional hair cell segments. These species of Sceloporus are unique among iquanids in that the bidirectional segments consist of but two rows of hair cells. The agamids, Agama agama and Calotes nigrolabius, have an "agamid-anguid type" papilla consisting of an apical short-ciliated unidirectional segment. Agama agama is unusual in having a few long-ciliated hair cells at the apical end of the apical short-ciliated segment. The agamid, Uromastix sp., has an "iguanid type" papilla with a central short-ciliated unidirectional segment and apical and basal bidirectional segments. The anguid, Ophisaurus ventralis, has an "iguanid" papillar pattern with the short-ciliated segment centrally located. All the short-ciliated hair cells of the above species are covered by a limbus-attached tectorial network or cap and the long-ciliated hair cells, only by loose tectorial strands. The lacertids, Lacerta viridis and L. galloti, have papillae divided into two separate segments. The shorter apical segment consists of opposingly oriented, widely separated short-ciliated cells covered by a heavy tectorial membrane. The apical portion of the longer basal segment consists of unidirectionally oriented hair cells, while the greater part of the segment has opposingly oriented hair cells. The xantusiids, Xantusia vigilis and X. henshawi, have papillae made up of separate small apical segments and elongated basal segments. The apical hair cells are largely, but not exclusively, unidirectional and are covered by a heavy tectorial cap. The basal strip is bidirectional and the hair cells are covered by sallets. The kinocilial heads are arrowhead-shaped. The papilla of the cordylid, Cordylus jonesii, is very similar to that of Xantusia except that the apical segment is not completely separated from the basal strip. The papilla of the Varanus bengalensis is divided into a shorter apical and a longer basal segment. The hair cells of the entire apical and the basal three quarters of the basal segment are opposingly oriented, not with reference to the midpapillary axis but randomly to either the neural or abneural direction. The apical quarter of the basal segment contains unidirectional, abneurally oriented hair cells. The entire papilla is covered by a dense tectorial membrane. The functional correlations of the above structural variables are discussed.

Animals↗
PubMed1979

Neutrophil marrow profiles in patients with rheumatoid arthritis and neutropenia.

Neutrophil marrow cellularity was determined in 14 neutropenic patients with rheumatoid arthritis (RA) from measurements of neutrophil-normoblast ratios in marrow biopsies and ferrokinetic estimates of marrow normoblasts. A marrow profile was developed for each patient comprising the numbers of promyelocytes and myelocytes, of metamyelocytes and bands, and of segmented neutrophils in whole marrow. In each case a maturation ratio was calculated by dividing the number of metamyelocytes and bands by the number of promyelocytes and myelocytes. The physiologic marrow response to loss of neutrophils from circulation was assumed to be an increase in promyelocytes and myelocytes due to proliferation and influx, a reduction in segmented cells due to early release, and a normal maturation ratio. The results were interpreted in the light of the 95% confidence limits for data previously obtained from 13 normal subjects: in patients with neutropenia reduced or basal numbers of promyelocytes and myelocytes were interpreted as absence of the anticipated proliferative response; increased numbers of marrow segmented cells were attributed to failure of release; a low maturation ratio was assessed to reflect intramedullary cell loss. The pattern in two patients with Felty's syndrome was consistent with a physiological response to neutrophil destruction. The other 12 patients had neutrophil marrow abnormalities. Seven patients with Felty's syndrome and four patients without splenomegaly had absolute or relative hypoplasia of neutrophil marrow or low maturation ratios. One patient with a normal spleen size had an increased number of marrow segmented cells yet failed to mobilize cells normally in response to dialysis coil-activation of C3. Abnormalities of neutrophil marrow may contribute to neutropenia in RA irrespective of the presence of splenomegaly. Recognition of neutrophil marrow abnormalities in these patients may be of value in prognosis and management.

Adult↗
PubMedDate not supplied

Fundamental study of automatic cyto-screening for uterine cancer. II. Segmentation of cells and computer simulation.

In images of Papanicolaou stained cells 64 gray levels have been differentiated by scanning densitomery. One of the two peaks in a differential histogram indicates the threshold of the cytoplasm, the other that of the nucleus. The two modes indicate where in the digitized image of good segmentation of the cell from its background and the nucleus from the cytoplasm can be accomplished.

Cell Nucleus↗
PubMed1977

High resolution analysis of cervical cells--a progress report.

This paper presents preliminary results of research toward the development of a high resolution analysis stage for a dual resolution image processing-based prescreening device for cervical cytology. Experiments using both manual and automatic methods for cell segmentation are described. In both cases, 1500 cervical cells were analyzed and classified as normal or abnormal (dysplastic or malignant) using a minimum Mahalanobis distance classifier with eight subclasses of normal cells, and five subclasses of abnormal cells. With manual segmentation, false positive and false negative error rates of 2.98 and 7.73% were obtained. Similar experiments using automatic cell segmentation methods yielded false positive and false negative error rates of 3.90 and 11.56%, respectively. In both cases, independent training and testing data were used.

Autoanalysis↗
PubMed1976

Hybridization of mRNA from adenovirus-transformed cells to segments of the adenovirus genome.

Cytoplasmic viral-specific RNA from the 8617 line of adenovirus type 2 (Ad2) transformed rat cells was hybridized to DNA fragments derived either by Eco-RI or Sma-I restriction endonucleases. Three discrete classes of viral RNA (26S, 20S, and 15S) were detected by hybridization of total cytoplasmic RNA with the fragment, and all of these RNA molecules also hybridized to the much smaller Sma-E fragment of Ad2 DNA. Poly (A)-containing RNA (exposed to 90% formamide) contained only the 20S and 15S mRNA species, suggesting that the 26S RNA might be an aggregated species. Viral RNA of the same size derived from the same regions of the genome has not been detected in lytically infected cells, suggesting some change in the pattern of transcription or RNA processing of the Ad2 DNA in the integrated state.

Adenoviridae↗