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At least 1,207 records · Page 67Linked to original sources
PubMed2003

Binding of gastrointestinal tumor cells to endothelial E- and P-selectin adhesion receptors leads to transient down-regulation of sLeX ligands in vitro.

BACKGROUND AND AIMS: The prognostic relevance of sialyl Lewis X (sLeX) expression in colorectal and gastric cancer and its relevance to the hematogenous phase of tumor invasion is controversial. This study was designed to evaluate sLeX expression during tumor cell-endothelial cell interaction in vitro. METHODS: Adhesion and transendothelial penetration of MKN45, PaCa-2, WiDr, or Dan-G cells was analyzed by combined phase contrast-reflection interference contrast microscopy. In parallel, kinetics of membranous sLeX expression were examined fluorimetrically. To identify factor(s) which may be responsible for sLeX expression during tumor invasion tumor cells were treated with soluble immunomodulators, isolated endothelial plasma membranes, or E-selectin or P-selectin IgG fusion proteins. sLeX was then analyzed by flow cytometry. RESULTS: Fluorometric quantification of sLeX demonstrated an inverse correlation between basal sLeX expression level and adhesion capacity of the tumor cells. Unexpectedly, sLeX was strongly down-regulated on tumor cell membranes in the course of heterophilic cell-cell contacts. The process occurred transiently, with a maximum effect 30-60 min after introducing tumor cells to the endothelial monolayer. Binding of tumor cells to immobilized E- and P-selectin IgG globulin chimeras was shown to be responsible for this phenomenon. CONCLUSION: A transient loss of sLeX is necessary for gastrointestinal tumor cells to invade endothelial cells. Due to the transient nature of the decrease in sLeX the controversy about the prognostic relevance of sLeX expression in colorectal and gastric cancer may be rooted in the stage of tumor invasion at the time of sLeX measurement.

Cell Adhesion↗
PubMed1998

Cell matrix adhesions and localization of the vitronectin receptor in MCF-7 human mammary carcinoma cells.

Interference reflection microscopy (IRM) was used to evaluate the status of cell matrix adhesions in the MCF-7 human mammary carcinoma cell line. Focal contacts were concentrated at the periphery of individual cells or small cell clusters. Close contact was detected as a band at cell peripheries and as localized patches throughout the ventral face of cells. The MCF-7 cells also exhibited a distinctive reflection pattern of an intensity midway between that of either focal or close contact. This novel reflection pattern was located primarily at the periphery of cells and often obscured visualization of focal contacts in live cells. A similar distinctive pattern was absent from the normal tissue-derived MCF-10A mammary epithelial cell line. Immunofluorescence staining using an antiserum that cross-reacts with both alpha(v)beta3 and alpha(v)beta5 integrins revealed a distribution of the vitronectin receptor similar to that of the novel adhesion pattern as well as to that of focal contacts. In addition, IRM demonstrated the presence of "tracks" associated with cells, which were also stained with the vitronectin receptor antiserum. The tracks are apparently residual material left behind as a result of cell migration. When MCF-7 cells were cultured in the absence of estradiol, the tracks were greatly diminished when visualized with either IRM or staining for the vitronectin receptor. In contrast, the addition of 17-beta-estradiol to the medium resulted in an increased presence of the tracks as well as the development of extensive close contacts throughout the ventral surface of cells and cell clusters. Cells treated with the estrogen antagonist ICI 182,720 in the presence of estradiol had few associated tracks, indicating that the process leading to the formation of these structures is dependent on an estrogen receptor-activated pathway. However, the antagonist did not prevent the estradiol-induced formation of extensive close contacts. The extensive close contact as well as the increase in trailing material suggests that estradiol may promote breast tumor cell motility. However, this migratory activity may be mediated by both estrogen receptor-dependent and -independent pathways.

Breast Neoplasms↗
PubMed1999

The exposure of healthy volunteers to 200 ppm 1,1,1-trichloroethane increases the concentration of proinflammatory cytokines in nasal secretions.

OBJECTIVES: Irritating effects of organic solvents have usually been measured by means of questionnaires. The aim of the present study was to evaluate the sensitivity of different methods of detecting subclinical irritating effects. METHODS: Twelve healthy, non-smoking students were exposed to 200 ppm and to 20 ppm 1,1,1-trichloroethane in an exposure chamber, using a crossover design. The amounts of interleukins (IL)-1beta, IL-6 and IL-8 and prostaglandin E(2) (PGE(2)) in nasal secretions were measured. Mucociliary transport time was determined with the saccharine test. Ciliary beat frequency of nasal epithelial cells was measured with video-interference contrast microscopy. Subjective symptoms were assessed by questionnaire. RESULTS: Concentrations of ILs were significantly elevated after exposure to 200 ppm 1,1,1-trichloroethane (IL-1beta 82.4 vs. 28.8 pg/ml (medians), P=0.003; IL-6 12.2 vs. 7.2 pg/ml, P=0. 01; IL-8 549 vs. 424 pg/ml, P=0.007), whereas the other parameters remained unchanged. CONCLUSION: The interleukins measured proved to be sensitive indicators of irritating effects of 1,1, 1-trichloroethane. The German threshold limit (MAK value) of 200 ppm 1,1,1-trichloroethane does not prevent the subclinical inflammation of nasal mucosa.

Adult↗
PubMed2005

Excretory/secretory products of sheep abomasal nematode parasites cause vacuolation and increased neutral red uptake by HeLa cells.

Excretory/secretory (ES) products of Ostertagia (Teladorsagia) circumcincta and Haemonchus contortus have been implicated in the inhibition of gastric acid secretion and vacuolation, and the loss of parietal cells associated with abomasal parasitism. Vacuolation of epithelial (HeLa) cells caused by adult O. circumcincta or L3 O. circumcincta or H. contortus ES products have been examined by differential interference contrast microscopy and by the neutral red uptake assay. ES products caused visible vacuolation of HeLa cells, and this effect was enhanced by 8 mM NH4Cl. Some parasite ES products caused a marked detachment of cells from the coverslip. At lower concentrations of ES products, neutral red uptake was usually increased above the control, but at higher concentrations of ES products, uptake was often decreased, probably because of cell detachment. Although generally consistent with direct observations of HeLa cell vacuolation by parasite chemicals, neutral red uptake was not a satisfactory quantitative assay.

Abomasum↗
PubMed2005

Transforming growth factor-beta1 downregulates beating frequency and remodeling of cultured rat adult cardiomyocytes.

We have observed increased levels of transforming growth factor-beta1 (TGF-beta1) in human hibernating myocardium (HM). Impaired ventricular function in HM is known to be restored to normal following revascularization implying that myocardial structure in HM is to a certain degree preserved. We have therefore tested whether TGF-beta1 can imitate features of HM by reducing the number and frequency of beating cells (chronotropism) and structural remodeling of cultured adult rat cardiomyocytes (ARC), thus saving substrate, energy, and oxygen. Parameters measured were cell size, protein synthesis, protein degradation, protein content, myofibrillogenesis, and chronotropism. ARC were stimulated for 6 days with sera from patients with coronary heart disease, as this period led to a maximum response of cells. An increase of 90% in cell surface area following such treatment was reduced to a 20% increase of the original size by TGF-beta1. Concomitantly, the rate of protein synthesis dropped from 3.6-fold to 2.4-fold, and myofibrillogenesis was reduced. TGF-beta1 downregulated both the number of contracting cells from 81% to 10% and the frequency from 52 to nine beats per minute. However, TGF-beta1 treatment did not reduce the augmentation of protein content (1.28-fold versus 1.25-fold) indicating that protein degradation was also inhibited. Similar results were obtained with serum from healthy volunteers. The effects of TGF-beta1 were reversible. We conclude that TGF-beta1 constrains protein turnover and beating activity in underperfused myocardium, thus mediating protection by adapting myocytes to shortages in blood supply.

Animals↗
PubMed2003

On the mechanism of callose synthesis induction by metal ions in onion epidermal cells.

Metal ions induce the synthesis of callose in Allium cepa epidermal cells. Callose is deposited as single knoblike local accumulations, aggregates of knobs, or furrowed clusters tightly attached to the cell wall. The most effective metal is copper, it induces callose formation at micromolar concentrations. Agents acting on inositolphosphate metabolism, phospholipase inhibitors, calcium channel inhibitors, modulators of cytoplasmic calcium, or receptor antagonists influence callose synthesis. It is concluded that metal ions, especially Cu(2+), initiate a signal transduction chain by activation of phospholipases and generation of inositol 1,4,5-trisphosphate, and that callose synthesis is a cellular defence reaction caused by the disturbance of intracellular calcium homeostasis.

Calcium↗
PubMed2006

[Systematic qualitative histology of enossal implants with anodically oxidised surfaces].

Histological analysis of dental implants is often quantified by calculating the bone-implant contact rate (bone volume/total volume), whereas qualitative aspects like osteoconduction are underrepresented. The aim of this study was to focus on the micro-architectural properties of the bone-implant contact under physiologic loading using a systematic analysis of these characteristics. In 16 Beagle dogs we inserted 6 different types of dental implants in the hard bone of the mandible and the soft bone of the maxilla. After a healing period of two months the implants were loaded for three months and then histologically analysed. For the metric evaluation of qualitative histological aspects 12 examiners answered pivotal questions: 1. Is the implant functional sufficient? 2. Do you see close contact to bone, were bone is present? 3. Is the amount of bone at the implant at least similar to the peripheral bone? 4. Is the bone to implant contact homogenous? 5. Does the bone show a functional architecture? 6. Do you find osseoconductive bone apposition at the crestal and apical border? A superiority of anodic oxidized surfaces can be seen in questions 1, 2 and 3 mainly for the comparison of identical macrodesigns (MkIII). The potential for osseoconductivity (questions 4 and 5) shows a tendency for significant differences for the ZL Ticer implant. Homogenous bone to implant contact is rarely found, in contrast to rather positive implant function ratings. This suggests the existence of an optimum in the bone to implant contact rate. Bone to implant contact rate as an isolated quantitative parameter should in future be completed by a systematic, standardised and blinded analysis of qualitative properties.

Animals↗
PubMed2004

Metastatic breast cancer cells suppress osteoblast adhesion and differentiation.

Bone is a primary target for colonization of metastatic breast cancer cells. Once present, the breast cancer cells activate osteoclasts, thereby stimulating bone loss. Bone degradation is accompanied by pain and increased susceptibility to fractures. However, targeted inhibition of osteoclasts does not completely prevent lesion progression, nor does it heal the lesions. This suggests that breast cancer cells may also affect osteoblasts, cells that build bone. The focus of this study was to determine the ability of breast cancer cells to alter osteoblast function. MC3T3-E1 osteoblasts were cultured with conditioned medium from MDA-MB-231 breast cancer cells and subsequently assayed for changes in differentiation. Osteoblast differentiation was monitored by expression of osteocalcin, bone sialoprotein and alkaline phosphatase, and by mineralization. Osteoblasts cultured with MDA-MB-231 conditioned medium did not express these mature bone proteins, nor did they mineralize a matrix. Inhibition of osteoblast differentiation was found to be due to transforming growth factor beta present in MDA-MB-231 conditioned medium. Interestingly, breast cancer conditioned medium also altered cell adhesion. When osteoblasts were assayed for adhesion properties using interference reflection microscopy and scanning acoustic microscopy, there was a reduction in focal adhesion plaques and sites of detachment were clearly visible. F-actin was disassembled and punctate in osteoblasts cultured with MDA-MB-231 conditioned medium rather than organized in long stress fibers. Taken together, these observations suggest that metastatic breast cancer cells alter osteoblast adhesion and prevent differentiation. These affects could account for the continued loss of bone after osteoclast inhibition in patients with bone-metastatic breast cancer.

Alkaline Phosphatase↗
PubMed2006

Cytological mechanism of pollen abortion resulting from allelic interaction of F1 pollen sterility locus in rice (Oryza sativa L.).

Pollen abortion is one of the major reasons causing the inter-subspecific F(1) hybrid sterility in rice and is due to allelic interaction of F(1) pollen sterility genes. The microsporogenesis and microgametogenesis of Taichung 65 and its three F(1) hybrids were comparatively studied by using techniques of differential interference contrast microscopy, semi-thin section light microscopy, epifluorescence microscopy and TEM. The results showed that there were differences among the cytological mechanisms of pollen abortion due to allelic interaction at the three F(1) pollen sterility loci. The allelic interaction at S-a locus resulted in microspores unable to extend the protoplasm membrane with the enlargement of the microspore at the middle microspore stage and finally producing empty abortive pollen. The allelic interaction at S-b locus caused asynchronous development of microspores at the middle microspore stage producing stainable abortive pollen. The allelic interaction at S-c locus mainly led to the non-dissolution of the generative cell wall and finally caused the hybrid F(1) mainly producing stainable abortive pollen. Genotypic identification indicated that the abortive pollen were those with S ( j ) allele.

Alleles↗
PubMed2005

Three new species of Enterocola van Beneden, 1860 (Crustacea: Copepoda: Cyclopoida) from ascidian hosts.

Three new species of Enterocola are described: E. dicaudatus n. sp., from the ascidian host Polysyncraton rostrum Monniot & Monniot collected in Tanzania, E. monnioti n. sp., from the ascidian host Polyclinum constellatum Savigny collected in Bahrain, and E. parapterophorus n. sp., from the ascidian host Didemnum granulatum Tokioka taken in Djibouti. In all three species, the mandibles are interpreted as being represented by a pair of setulose seta-like elements that are largely concealed beneath similar paired setulose structures, the labral palps, carried on the labrum. The paired elements interpreted as mandibles are transversely orientated and lie in a groove, the anterior margin of which forms a defined ridge ornamented with spinules.

Animals↗
PubMed2006

Diplectanids (Monogenea) parasitic on the gills of the coralgroupers Plectropomus laevis and P. leopardus (Perciformes, Serranidae) off New Caledonia, with the description of five new species and the erection of Echinoplectanum n. g.

Echinoplectanum n. g. is erected for diplectanids which have a male copulatory organ comprising a tubular sclerotised penis with a muscular reservoir at its proximal extremity and an protrusible cirrus, often with spiny ridges, at its distal extremity, and a female copulatory organ comprising a sclerotised vaginal sac, often with two thin tubes. All species have similar squamodiscs made of rows of rodlets, with the central rows forming closed circles, and haptoral parts with a similar shape but different measurements; they are distinguished on the basis of the size and morphology of the male copulatory organ and sclerotised vagina. Five new species are included in Echinoplectanum and are all parasites of coralgroupers, Plectropomus spp., off New Caledonia, South Pacific. Two are from P. laevis (Lacépède): E. laeve n. sp. (type-species) has a large elongate penis, 53[Formula: see text]m in length, a cirrus with spiny ridges and a spherical vagina with two long thin tubes; and E. chauvetorum n. sp. has a large elongate penis, 51[Formula: see text]m in length, a cirrus with thin spiny ridges, and a pear-shaped vagina with two short thin tubes. Three species are from P. leopardus (Lacépède): E. leopardi n. sp. has an elongate penis, 36[Formula: see text]m in length, an unspiny cirrus and a triangular vagina; E. pudicum n. sp. has a very small elongate penis 14[Formula: see text]m in length and no visible vagina; and E. rarum n. sp. has a short thick penis 18[Formula: see text]m in length and a ring-shaped vagina with two thin tubes. In addition, Diplectanum plectropomi Young, 1969, from P. maculatus off Western Australia, and D. echinophallus Euzet & Oliver, 1965 from Epinephelus marginatus in the Mediterranean Sea and Senegal, West Africa, both herein redescribed from the type-specimens, are transferred to Echinoplectanum, as E. plectropomi n. comb. and E. echinophallus n. comb., respectively. Six of the seven species of Echinoplectanum are parasitic in members of Plectropomus from the South West Pacific, but one (E. echinophallus) is a parasite of Epinephelus marginatus and has been recorded only from the Mediterranean and East Atlantic; it is suggested that Echinoplectanum is associated with Plectropomus, a basal genus among the epinephelines, and that host-switching to Epinephelus marginatus occurred, whose distribution extends from Europe to the Indian Ocean. Morphological characteristics of the copulatory organs suggest that a "chastity belt versus spiny penis" sperm competition pattern prevails in Echinoplectanum spp.

Animals↗
PubMed2006

Laticola dae n. sp. (Monogenea: Diplectanidae) from Epinephelus maculatus (Perciformes: Serranidae) off New Caledonia.

Laticola dae n. sp. is described from specimens collected from the gill-filaments of the highfin grouper Epinephelus maculatus, a coral reef fish caught off Nouméa, New Caledonia, South Pacific. The species is characterised by a spoon-shaped sclerotised male copulatory organ, with four thin walls and 73-[Formula: see text]m in outer length, and a sclerotised vagina in form of a disc, 16-[Formula: see text]m in diameter, with a smaller hemisphere on one side. Laticola Yang et al., 2006 was described to accommodate diplectanids from Lates calcarifer (Centropomidae); this is the first Laticola described from a serranid. Other diplectanids, including several species of Pseudorhabdosynochus Yamaguti, 1958, were also found on the same species of fish; specimens of L. dae represented about half of the diplectanids collected; all other species were rare.

Animals↗
PubMed2006

Monogeneans on native and introduced freshwater fishes from Cuba with the description of a new species of Salsuginus Beverley-Burton, 1984 from Limia vittata (Poeciliidae).

During a parasitological survey carried out between March and September 2003 in Cuba, the following monogeneans were found on the gills of freshwater fishes: Salsuginus cubensis n. sp. on the Cuban molly Limia vittata Guichenot (Poeciliidae); Cichlidogyrus sclerosus Paperna & Thurston, 1969 and C. tilapiae Paperna, 1960 on the African cichlid Tilapia rendalli Boulenger (Cichlidae); Haplocleidus dispar Mueller, 1936 and Pterocleidus acer Mueller, 1936 (all Dactylogyridae) on the sunfish Lepomis macrochirus Rafinesque (Centrarchidae) (new geographical records); and Gyrodactylus sp. (Gyrodactylidae) on the biajaca Nandopsis tetracanthus Valenciennes (Cichlidae) (new host and geographical record). Salsuginus cubensis differs from all other species of the genus in the size and morphology of the copulatory complex. The occurrence of C. sclerosus, C. tilapiae, H. dispar and P. acer in their respective hosts is due to the introduction of these hosts to Cuba. A review of the species composition of the Monogenea in native and introduced freshwater fish from Cuba is presented and the zoogeographical distribution of the species found is briefly discussed.

Animals↗
PubMed2006

The status of Acleotrema Johnston & Tiegs, 1922 and Heteroplectanum Rakotofiringa, Oliver & Lambert, 1987 (Monogenoidea: Diplectanidae), with the redescription of Acleotrema girellae Johnston & Tiegs, 1922.

Acleotrema Johnston & Tiegs, 1922 is resurrected and its diagnosis amended. A. girellae Johnston & Tiegs, 1922 is redescribed based on the lectotype from the Australian Museum (Sydney, Australia). A. kyphosi Yamaguti, 1968 is considered a junior synonym of A. girellae. Heteroplectanum Rakotofiringa, Oliver & Lambert, 1987 is considered a junior synonym of Acleotrema. The nine species of the latter genus are transferred to Acleotrema as: A. diplobulbus (Yamaguti, 1968) n. comb., A. nenue (Yamaguti, 1968) n. comb., A. spiculare (Yamaguti, 1968) n. comb., A. yamagutii (Oliver, 1983) n. comb., A. nenuoides (Rakotofiringa, Oliver & Lambert, 1987) n. comb., A. parastromatei (Rakotofiringa, Oliver & Lambert, 1987) n. comb., A. serrulopenis (Rakotofiringa, Oliver & Lambert, 1987) n. comb., A. tamatavense (Rakotofiringa, Oliver & Lambert, 1987) n. comb. and A. oliveri (León-Règagnon, Pérez-Ponce de León & Garcia- Prieto, 1997) n. comb. An historical account of the species of Acleotrema is presented.

Animals↗
PubMed2006

The occurrence of the Japanese species Dinosoma lophiomi Toman, 1973 (Digenea: Hemiuridae) in Lophius piscatorius (Teleostei) from the western Mediterranean.

Hemiurid worms from the stomach of the angler Lophius piscatorius off Corsica are described and considered to belong to a Japanese species, Dinosoma lophiomi Toman, 1973, which was originally described from an Indo-Pacific lophiid host. The apparent disjunctive distribution of this species and apparent differences in the terminal genitalia between the European and Japanese specimens are discussed. This is the first record of Dinosoma Manter, 1934 from the Mediterranean Sea. The validity of diagnostic features of Adinosoma Manter, 1947 is commented upon, and lists of records of species of Dinosoma and digeneans from L. piscatorius in the Western Mediterranean are included.

Animals↗
PubMed2006

A revision of Lomasoma Manter 1935 (Digenea: Fellodistomidae), with new data on the type-specimens of four species and the description of L. triglae n. sp. from Chelidonichthys lucernus (L.) (Pisces: Triglidae) in the Western Mediterranean.

Type-specimens of Lomasoma wardi (Manter, 1934), L. monolenei (Manter, 1934), L. gracile (Manter, 1934) (emend.) and L. stefanskii Dollfus, 1960 were studied with special reference to the structure of their body margins and terminal genitalia. Illustrations and a partial redescription is given for each of these species. The new data obtained enabled the recognition and description of L. triglae n. sp. from the tub gurnard Chelidonichthys lucernus (L.) in the Western Mediterranean. Differences between the species of the genus are tabulated. An interpretation of the function of the muscular lobes on the margins of the body of Lomasoma spp. is presented, and comments are made on the structural homogeneity or diversity of different morphological features.

Animals↗
PubMed2006

A new species of Prohatschekia Nunes-Ruivo, 1954 (Copepoda: Hatschekiidae) parasitic on Scorpaena elongata (Cadenat) off Algeria.

A new species of parasitic copepod, Prohatschekia mediterranea n. sp. (Siphonostomatoida: Hatschekiidae), is described from a scorpaenid fish, Scorpaena elongata, collected off Algeria. This is the seventh species of Prohatschekia Nunes-Ruivo, 1954 to be described and the first record of the genus from the Mediterranean Sea. The new species is most closely related to P. cremouxi Nunes-Ruivo, 1954, known from a congeneric host collected in Senegal. A key is provided to distinguish the new species from other members of the genus.

Algeria↗