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At least 1,225 records · Page 68Linked to original sources
PubMed2000

Possible involvement of altered RGD sequence in reduced adhesive and spreading activities of advanced glycation end product-modified fibronectin to vascular smooth muscle cells.

Although fibronectin (FN) modified by advanced glycation end products (AGEs) has been shown to contribute to the development of diabetic vascular complications through its reduced adhesive activity to vascular cells, little is known about changes in the cell binding domain of AGE-modified FN. Here we examined the mechanism of reduced adhesive and spreading activities of AGE-modified FN to vascular smooth muscle cells (SMCs), particularly the contribution of modification of Arg-Gly-Asp (RGD) sequence. Incubation with glucose caused not only the formation of N(epsilon) -carboxymethyllysine and pentosidine, but also polymerization of FN in a dose- and time-dependent manner. AGE-modified FN had significantly low adhesive and spreading activities to cultured SMCs. On the other hand, multimeric FN formed by disulfide bonds did not show any effect on either cell adhesion or spreading. The adhesive activity of type I collagen, one of the RGD sequence-containing proteins, to SMCs also decreased by AGE-modification. The inhibitory effect of AGE-modification on cell adhesion was significantly greater in type I collagen than in FN. Although the extent of AGE-modification of type I collagen was indistinguishable from that of FN, AGE-modification decreased the arginine content of type I collagen by 69.5% and of FN by 30.6%, compared with their non-glycated forms. The addition of RGD peptides caused a decrease in adhesion of SMCs to non-glycated FN, but not to AGE-modified FN. Modification of RGD sequence with glyoxal eliminated its inhibitory effect on cell adhesion. Our results suggest that a marked decrease in adhesive and spreading activities of AGE-modified FN to SMCs might largely be due to a modification of its RGD sequence by AGE, thus suggesting a potential link between AGE modification of FN and the pathogenesis of diabetic angiopathy.

Amino Acids↗
PubMed1987

Effect of mechanical stimulus spread across glabrous skin of raccoon and squirrel monkey hand on tactile primary afferent fiber discharge.

The role of spread of skin deformation in activating cutaneous mechanoreceptors at a distance from their threshold receptive fields (RFs) was examined in glabrous skin of the North American raccoon and the squirrel monkey. One feedback-controlled mechanical stimulus probe was used to indent the skin to a controlled depth at a constant velocity, at varying distances from a second probe, which was used to monitor vertical displacement depth and velocity at this distant site. In many instances, the monitor probe was positioned over the RF of a cutaneous mechanoreceptor, and single-unit action potentials were simultaneously recorded from individual fibers of the median or ulnar nerve. With distance from the site of stimulation, there was a systematic, monotonic decline in indentation depth and velocity; velocity fell off with distance more rapidly than depth. The degree of diminution with distance varied with the size, shape, and curvature of the digital or palm pad stimulated. Spread of indentation was more restricted on digital than on palm pads, and was more restricted across monkey skin than across raccoon skin. Spread was less with higher-velocity than with lower-velocity indentations, but was seemingly unaffected by indentation depth. As expected from the findings noted above, the number of spikes discharged by slowly adapting mechanoreceptive afferent fibers declined more rapidly with distance between stimulus site and RF for digital than for palmar RFs, in squirrel monkey than in raccoon skin, and with higher-velocity than with lower-velocity stimuli. Furthermore, the number of spikes occurring during either ramp or early static indentation phases of stimulation dropped to zero more rapidly with distance than did either vertical indentation depth or velocity. Decreases with distance in both indentation depth and velocity acted to restrict the size of suprathreshold RFs. For most units, horizontal components of mechanical stimulation subtracted from the effects of vertical components. It is suggested, on the basis of this and other studies, that many neural and perceptual phenomena usually attributed to central mechanisms of afferent inhibition may be attributable, at least in part, to mechanical properties of the skin. In addition, the present data suggest that regional variations in the two-point limen may be associated with variations in spread of mechanical deformation. The conclusion that glabrous skin and subjacent soft tissues act as a low-pass filter system provides a mechanical basis for the relative efficacy of high-frequency vibratory stimuli in tactile pattern perception.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1981

Inhibition of yeast phagocytosis and cell spreading by glucocorticoids in cultures of resident murine peritoneal macrophages.

This study was initiated to determine whether the inhibition of phagocytosis and cell spreading in cortisol-treated cultures of resident murine peritoneal macrophages are glucocorticoid-directed responses. Phagocytosis of heat-killed Saccharomyces cerevisiae and cell spreading were measured in control and steroid-treated macrophage cultures over 6 days. When the cultures were exposed to testosterone, progesterone, or epicortisol, phagocytosis and cell spreading were similar to controls. In contrast, both macrophage functions were inhibited significantly in cultures treated with cortisol, methylprednisolone, dexamethasone, and triamcinolone acetonide. In addition, the rate of phagocytosis was retarded and phagocytic indices (i.e., yeast particle number/cell) were reduced in glucocorticoid-treated cultures. Dose-response studies with dexamethasone demonstrated that the ED50 for the inhibitory effect on phagocytosis was 20 nM. These results indicate that the inhibition of yeast phagocytosis and cell spreading in the steroid-treated cultures are specific glucocorticoid-directed responses.

Animals↗
PubMed1988

The effect of bovine serum albumin and cytohelicase on surface-spread synaptonemal complexes of rye (Secale cereale).

Synaptonemal complexes of rye meiocytes were spread on plastic coated slides for electron microscopic observation. Two proteins generally used in synaptonemal complex spreading techniques, bovine serum albumin and cytohelicase, were applied separately or in combination in an isotonic protoplast medium at concentrations of 0.1-5%. At high concentrations these proteins proved to enhance notably the ultimate number of cells with synaptonemal complexes in the preparations. Also under this condition, centromere structures became stainable with silver nitrate in both the synaptonemal complexes of pollen mother cells and in interphase nuclei of other cell types. Since the true action of cytohelicase under appropriate spreading conditions was uncertain, the putative enzymatic digestion of cell walls was determined in a series of experiments using the fluorochrome calcofluor white as a stain of callose walls. Obvious breakdown of the cell walls was not observed before 8 min of treatment under standard conditions. This made it plausible that the prime effect of cytohelicase is that of a nonspecific protein interacting with the chromatin and improving the adhesion of synaptonemal complexes to the hydrophobic plastic film. The differential staining of the centromere structures in the presence of bovine serum albumin and cytohelicase probably reflects a reduced spreading of these structures due to preferential binding between these proteins and centromeric proteins.

Animals↗
PubMed2000

Products of hemolysis in the subarachnoid space inducing spreading ischemia in the cortex and focal necrosis in rats: a model for delayed ischemic neurological deficits after subarachnoid hemorrhage?

OBJECT: The pathogenesis of delayed ischemic neurological deficits after subarachnoid hemorrhage has been related to products of hemolysis. Topical brain superfusion of artificial cerebrospinal fluid (ACSF) containing the hemolysis products K+ and hemoglobin (Hb) was previously shown to induce ischemia in rats. Superimposed on a slow vasospastic reaction, the ischemic events represent spreading depolarizations of the neuronal-glial network that trigger acute vasoconstriction. The purpose of the present study was to investigate whether such spreading ischemias in the cortex lead to brain damage. METHODS: A cranial window was implanted in 31 rats. Cerebral blood flow (CBF) was measured using laser Doppler flowmetry, and direct current (DC) potentials were recorded. The ACSF was superfused topically over the brain. Rats were assigned to five groups representing different ACSF compositions. Analyses included classic histochemical and immunohistochemical studies (glial fibrillary acidic protein and ionized calcium binding adaptor molecule) as well as a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay. Superfusion of ACSF containing Hb combined with either a high concentration of K+ (35 mmol/L, 16 animals) or a low concentration of glucose (0.8 mmol/L, four animals) reduced CBF gradually. Spreading ischemia in the cortex appeared when CBF reached 40 to 70% compared with baseline (which was deemed 100%). This spreading ischemia was characterized by a sharp negative shift in DC, which preceded a steep CBF decrease that was followed by a slow recovery (average duration 60 minutes). In 12 of the surviving 14 animals widespread cortical infarction was observed at the site of the cranial window and neighboring areas in contrast to findings in the three control groups (11 animals). CONCLUSIONS: The authors conclude that subarachnoid Hb combined with either a high K+ or a low glucose concentration leads to widespread necrosis of the cortex.

Animals↗
PubMed1991

Texture and motion spreading, the aperture problem, and transparency.

When a cross of either static or moving texture is inserted in the intersection of an Ehrenstein figure, we find that the texture and its motion appear to spread outside of the cross. We suggest that these phenomena are analogous to neon color spreading, wherein an interpretation of a transparent surface makes the properties of that surface, which are physically visible only inside the cross, appear to spread over its apparent extent. In our experiments, the texture and the motion of the cross are attributed to the transparent surface. In addition, the spreading changes the apparent aperture within which the texture and its motion are seen, leading to a corresponding change in the apparent direction of motion.

Adult↗
PubMed2026

DNA-FISH Metaphase Spreads to Distinguish Extrachromosomal DNA from Homogeneously Staining Regions in Human Cancer Cell Lines.

Whole-genome sequencing identifies focal DNA amplifications with base-pair resolution but cannot determine whether amplified sequences reside on extrachromosomal DNA (ecDNA, also known as double minutes) or within chromosomally integrated homogeneously staining regions (HSRs). DNA fluorescence in situ hybridization (DNA-FISH) metaphase spreads remain the gold standard for distinguishing these amplification states at single-cell resolution. Here, we present a detailed protocol for DNA-FISH metaphase spreads using human cancer cell lines, encompassing cell culture, metaphase arrest, hypotonic treatment, fixation, chromosome spreading, fluorescent probe hybridization, and fluorescence imaging. The protocol incorporates intermediate quality-control steps to verify successful chromosome dispersion and optimize metaphase spread quality, making the workflow accessible to laboratories without specialized cytogenetics expertise. Results demonstrate clear visualization of ecDNA and HSR amplification states using locus-specific probes and illustrate common technical artifacts that can affect interpretation. This protocol provides a robust and reproducible approach for studying the structural organization of oncogene amplification in cancer cells.

Humans↗
PubMed2001

The frequency of high avidity T cells determines the hierarchy of determinant spreading.

Autoimmunity often spreads in a predefined pattern during the progression of T cell-mediated autoimmune diseases. This progression has been well described in animal models and in man, but the basis for this phenomenon is little understood. To gain insight into the factors that determine this spreading hierarchy, we characterized the binding affinity of a panel of beta cell-autoantigenic peptides to I-Ag7, as well as the precursor frequency, functional avidity, and phenotype of the T cells that recognize these peptides in type 1 diabetes-prone nonobese diabetic mice. We observed that autoimmunity gradually spreads from a beta cell determinant, which had the largest precursor pool of high avidity T cells, to beta cell determinants with progressively smaller and lower avidity T cell precursor pools. This correlation between the sequential development of spontaneous T cell autoimmunity and the frequency and avidity of autoantigen-reactive T cells suggests that the extent to which T cells were negatively selected by the self-determinants is the key factor determining the spreading hierarchy.

Amino Acid Sequence↗
PubMed2003

Guanine exchange-dependent and -independent effects of Vav1 on integrin-induced T cell spreading.

Vav1 is a 95-kDa member of the Dbl family of guanine exchange factors and a prominent hemopoietic cell-specific protein tyrosine kinase substrate, the involvement of which in cytoskeletal rearrangements has been linked to its ability to activate Rho family small GTPases. Beta1 integrin ligation by fibronectin induced Vav1 phosphorylation in peripheral blood lymphocytes and in two different T cell lines. Vav1 overexpression led to massive T cell spreading on beta1 integrin ligands, and, conversely, two dominant negative mutants blocked integrin-induced spreading. Vav1 and beta1 integrin ligation synergistically activated Pak, but not Rac, Cdc42, or c-Jun N-terminal kinase. In addition, Vav1 cooperated with constitutively active V12Rac mutant, but not with V12Cdc42, to induce T cell spreading after integrin occupancy. More importantly, a Vav1 mutant that lacked guanine exchange factor activity still cooperated with V12Rac. In contrast, a point mutation in the SH2 domain of Vav1 abolished this synergistic effect. Therefore, our results suggest a new regulatory effect of Vav1 in T cell spreading, which is independent of its guanine exchange factor activity.

Animals↗
PubMed2003

[Spread of inhibition of return in visual search].

For conducting efficient visual search, it is important to inhibit spatial attention from reorienting to previously examined distractors. Several studies have proposed that this inhibition can be associated with object-based inhibition of return (IOR). The present study examined whether the spread of IOR across an object's surface affects the performance of visual search or not. If the spread of IOR occurs in visual search, unexamined targets and distractors linked with the previously attended items would be inhibited. We found that the spread of object-based IOR results in the increases of error rates in the target present trials and the decreases of reaction times in the target absent trials. These results indicate that participants made "absent" responses before examining all items if object-based IOR spread over unconfirmed items. We discuss the function of object-based IOR in visual search and also deal with how visual search is terminated.

Adolescent↗
PubMed1998

Agroclimatical analysis of plum pox virus spread in Slovakia.

In this report, the plum pox virus (PPV) spread from the point of view of agroclimatical conditions on the territory of Slovakia is analysed. The worst condition for the PPV spread was found in a warm macroregion. The air temperature sum in this macroregion during vegetative period ranged from 2400 to 3100 degrees C. The worst condition for the PPV spread was found in dry subregions of the macroregion. These were defined by differences between potential evapotranspiration and rainfall sums which ranged from 50 to 150 mm during summer months (from June to August). The decrease in air temperature sums and the increase of moisture in the environment as well as the severity of winter period was found to support the occurrence and spread of PPV.

Agriculture↗
PubMed1998

Non-invasive registration of the aboral and oral spreading of the gastroduodenal peristaltic activity (experimental and clinical investigations).

The electrical activity of the stomach and the upper part of the small intestine of healthy volunteers and patients with nausea and vomiting was recorded non-invasively on an original electrogastrograph. Two kinds of waves were distinguished according to their amplitude: low-amplitude waves, corresponding to the period of quiescence of migrating myoelectrical complex (MMC) and about twice higher in amplitude waves, characterising the periods of activity of MMC (peristaltic activity). There was also some difference between the low- and high-amplitude waves from the small intestine. Sequence of high-amplitude waves recorded from the stomach was followed usually by sequence of high-amplitude waves from the small intestine, presenting the aboral spreading of an activity period of MMC from the stomach to the small intestine. In some patients however, high-amplitude waves were led off first from the duodenal record and after that high-amplitude waves appeared in the gastric record. This suggests an oral spreading of the peristaltic activity (antiperistalsis). Experimental model of antiperistalsis was performed on dogs with chronically implanted electrodes on the gastric and duodenal muscle wall. Carbachol 5 micrograms/kg i.m. evoked bursts of spike potentials first with duodenal slow waves and after that with the gastric slow potentials. The antiperistaltic spreading of the spike activity in dog corresponded to the appearance of high-amplitude waves first in the record of the human small intestine, followed by sequence of high-amplitude waves in the stomach. Thus, the non-invasive recording of the electrical activity of the stomach and small intestines gives reliable information about the direction of the spreading of the peristaltic activity.

Algorithms↗
PubMedDate not supplied

Patterns of disease spread in metastatic breast carcinoma: influence of estrogen and progesterone receptor status.

BACKGROUND AND PURPOSE: It is widely recognized that tumor hormone receptor status correlates with overall survival in metastatic breast carcinoma; however, the influence of hormone receptors on the pattern of disease spread is not well known. PURPOSE: We set out to determine the common distributions of metastatic disease spread in metastatic breast carcinoma, and to evaluate tumor hormone receptor status as predictor of disease spread. METHODS: Thirty-six patients being imaged for possible metastatic breast carcinoma between 1995 and 1998, in whom the presence or absence of tumor estrogen and progesterone receptors (ER+ or ER- / PR+ or PR-) was known, who underwent both contrast-enhanced MR of the brain and total body skeletal scintigraphy, were studied retrospectively. RESULTS: Of twelve patients with skeletal metastases but no brain metastases, 83% were ER+/PR+. Ten patients had brain metastases but no skeletal involvement, 80% of which were ER-/PR-. Seven patients had no brain or osseous metastases, but had metastatic disease in the chest or abdomen. Eighty-six percent of patients in this group were ER-/PR-. The tumor receptor status was statistically different between these three distribution groups (P = .01). A final group, consisting of seven patients, showed widespread disease, with diffuse metastases to the brain, viscera, and skeleton. In this group, no patients were ER+/PR+. CONCLUSION: There are two major patterns of disease spread in metastatic breast carcinoma, excluding patients with extensive diffuse metastases. Patients with ER+/PR+ tumors tend to develop osseous but not brain metastases. Patients with ER-/PR- tumors tend to develop brain but not osseous metastases. Appreciation of these distributions can aid the radiologist in detecting metastatic lesions, and will help the clinician to estimate the likelihood of metastases to various organ systems, as well as to potentially target therapy.

Bone Neoplasms↗
PubMed2001

Improvements in cytogenetic slide preparation: controlled chromosome spreading, chemical aging and gradual denaturing.

BACKGROUND: Metaphase spreading is an essential technique for clinical and molecular cytogenetics. Results of classical banding techniques as well as complex fluorescent in situ hybridization (FISH) applications, such as comparative genomic hybridization (CGH) or multiplex FISH (M-FISH), are greatly influenced by the quality of chromosome spreading and pretreatment of the slide prior to hybridization. Materials and Methods Using hot steam and a metal plate with a temperature gradient across its surface, a reproducible protocol for slide preparation, aging, and hybridization was developed. RESULTS: This protocol yields good chromosome spreads from even the most difficult cell suspensions and is unaffected by the environmental conditions. Chromosome spreads were suitable for both banding and FISH techniques common to the cytogenetic laboratory. Chemical aging is a rapid slide pretreatment procedure for FISH applications, which allows freshly prepared cytogenetic slides to be used for in situ hybridization within 30 min, thus increasing analytical throughput and reducing benchwork. Furthermore, the gradually denaturing process described allows the use of fresh biologic material with optimal FISH results while protecting chromosomal integrity during denaturing. CONCLUSION: The slide preparation and slide pretreatment protocols can be performed in any laboratory, do not require specialized equipment, and provide robust results.

Cell Line↗
PubMed2000

Spread of epidural blockade in the anaesthetised pig using technetium99 and sensory-evoked potentials.

Our objective was to determine the extension and duration of a stable segmental thoracic or lumbar epidural blockade by lidocaine in the 20 to 25-kg pig. Fourteen anaesthetised pigs were investigated. The radioactive isotope technetium99 (Tc99) was added to lidocaine to evaluate the spread in the epidural space. One ml of this solution was administered via an epidural catheter either at the Th(6-7) or L6-S1 level. Sensory-evoked potentials (SEPs) were measured following peripheral nerve stimulation, to determine duration and sensory extension of the epidural blockade. The thoracic anatomical mean spread was 14.2 vertebrae. The end points of the spread were C3-C7 and Th8-Th13 and the lumbar anatomical mean spread was 10.2 vertebrae. The end points were Th10-Th12 and L6-S1. It was possible to abolish the SEPs with 2 and 4% lidocaine. A smaller volume of lidocaine was needed if a second dose was administered within 20 min. With 4% lidocaine it was possible to abolish the SEPs for more than 180 min. The use of 1 ml of 4% lidocaine repeated after 20 and 60 min at the Th(6-7) or L6-S1 level achieved a stable thoracic or lumbar epidural blockade.

Anesthesia, Epidural↗
PubMedDate not supplied

Unusual spread of liposarcoma.

BACKGROUND: The aim of our study was to investigate the unusual pattern of metastatic spread of liposarcoma. MATERIALS AND METHODS: We retrospectively studied thirty-two patients with liposarcoma (in seventeen located in the retroperitoneum and in fifteen in the extremities) who were managed at our institution over a ten-year period. Six patients with extremity liposarcoma developed local recurrence and or distal metastases and in three the site of the distal spread was other than the lungs. In only one patient with retroperitoneal liposarcoma we observed extra-pulmonary spread. The histologic type of all four cases with unusual spread was myxoid, with small areas of round cell differentiation in two cases. RESULTS: The survival of the patients after the initial recurrence was relatively prolonged (6, 1.5, 8 and 3 years with the last patient alive and well). CONCLUSION: Physicians should maintain a low threshold for initiating evaluation of relatively minor symptoms in patients with liposarcoma, as these symptoms may reflect the first manifestation of an extrapulmonary metastasis. Such an approach should result in earlier detection and hopefully improve survival for patients with liposarcoma.

Abdominal Neoplasms↗
PubMed2001

Highly nutrient-dense spreads: a new approach to delivering multiple micronutrients to high-risk groups.

Using a highly fortified food is the most attractive option to bringing missing nutrients to vulnerable groups. The recent development of a highly nutrient-dense spread (HNDS) for the treatment of malnourished children may have some relevance for other high-risk groups. Traditionally, severely malnourished children are fed for 3-4 weeks during their recovery with adapted milk feeds prepared by mixing dried skimmed milk, oil and sugar with a vitamin and mineral complex. This approach, however, is difficult to implement, since these feeds are excellent growth media for bacteria, and they must be prepared and fed under close supervision. This constraint led to the development of a HNDS, which is obtained by replacing part of the dried skimmed milk with a mixture of groundnut butter and powdered lactoserum. This spread can be eaten without dilution with water and preliminary trials showed that children preferred this HNDS to traditional liquid diets. In HNDS all powdered ingredients are embedded in fat which protects vitamins against oxidation and increases the shelf life of this product. Spreads also have a very low humidity and bacteria do not grow in it. Attempts to use spreads to supplement other vulnerable groups such as moderately malnourished children and pregnant women are discussed.

Child↗
PubMed2001

Symmetrical ethmoidal metastases from ductal carcinoma of the breast, suggesting transcribrosal spread.

Symmetrical ethmoidal metastases from ductal carcinoma of the breast, suggesting transcribrosal spread. While half of breast cancers develop metastases, the appearance of metastatic disease in paranasal sinuses from this origin is very rare. Eighteen other cases were found in the literature, dating from 1939 till now. A case of metastatic breastcancer presenting as a subacute therapy-resistant pansinusitis is described. The perfect symmetry was misleading. Bilateral ethmoidal biopsies were compatible with metastases from a ductal adenocarcinoma. Further investigation revealed meningeal carcinomatosis in the supra-orbital region and locoregional recurrence in the mastectomy scar and axilla. Comparing these 19 cases in chronological order, it was noticed that symptoms at time of diagnosis shift from those of space occupying lesions to those suggestive for sinusitis. This shift could be explained by earlier diagnosis. High index of suspicion is the key to diagnosis. Earlier diagnosis does not result in longer survival since in most cases patients have already widespread disease and die within one year. Most authors mention the role of the vertebral venous plexus in hematogeneous spreading of tumor cells. Another pathway of hematogenous spread is via (occult) lung metastases. This case prompts the hypothesis of transcribrosal spread from meningeal involvement.

Aged↗