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S Meier

Publications and source records attributed to S Meier.

At least 55 records · Page 3Linked to original sources
PubMed1992

Tumor-cell dissociation at the invasion front: a new prognostic parameter in gastric cancer patients.

Tumor-cell dissociation (TCD) is a well-known feature at the invasion front of malignant tumors, but little attention has so far been paid to its biological significance. Therefore, the aim of the present study was to score the degree of TCD at the invasion front (TCD 0-3) in a retrospective series of 445 gastric cancer patients and to compare its prognostic significance with the parameters T-stage, tumor size, grade of tumor differentiation, lymph-node involvement and vascular invasion. We could show that highly significant differences (p less than 0.0001, log-rank test) existed between the 5-year survival rates of patients with different degrees of TCD (TCD 0: 92.3%; TCD 1: 62.1%; TCD 2: 41.2%. TCD 3:38.5%) and that these differences were independent of T-stage 2, tumor size and grade of tumor differentiation. Univariate Cox regression analysis showed that in intestinal-type carcinomas, T-stage (Chi-square: 45.2) followed by blood vessel and lymphatic vessel invasion (Chi-square: 43.6 and 40.0) had the highest prognostic value, whereas TCD (Chi-square: 31.5) revealed a prognostic value quite similar to that of lymph-node involvement (Chi-square: 35.1). This prognostic relevance was still present in multivariate Cox regression analysis, showing that the determination of TCD provided an increase in prognostic information which significantly (P = 0.026) exceeded the information obtained by the combination of T-stage and lymph-node involvement. Our data suggest that TCD is a new prognostic parameter, especially in those gastric carcinomas in which lymph-node involvement or vascular invasion are not present.

Adult↗
PubMed1992

[New histomorphologic prognostic parameters in stomach cancer. A uni- and multivariate analysis of 445 patients].

In a retrospective series of 445 gastric cancer patients, the prognostic significance of classical histological parameters such as T-category, tumor size, lymphnode involvement and tumor grading was compared with the prognostic value of vascular invasion and the degree of tumor cell dissociation (TCD) at the invasion front. As shown in a Cox regression analysis, T-category had the highest prognostic value. Nevertheless, vascular invasion and TCD proved to be independent new parameters in a multivariate analysis, exceeding the prognostic information obtained by the combination of T-category and lymph-node involvement. In contrast, tumor grading provided no significant information. The determination of TCD at the invasion front as well as a careful search for vascular invasion may therefore provide additional useful information for identifying those patients who are at high risk and who may be candidates for adjuvant therapy in future clinical trials.

Adult↗
PubMed1992

Performance of the Kodak DT-60 physician's office analyzer as measured by CLIA-88 proposed evaluation criteria. Assessment of demographic and quality assurance factors influencing performance.

The 1988 Clinical Laboratories Improvement Act (CLIA-88) proposes to mandate universal proficiency testing and internal quality assurance practices for all laboratories, including those in physician offices. For 3 years, we have provided an independent voluntary proficiency testing program to more than 400 physician office laboratories using Kodak DT-60 analyzers (Eastman Kodak, Rochester, NY). This unique data set enables us to evaluate, using the CLIA-88 proposed grading criteria, the ability of these laboratories to meet the proposed regulatory standards. Using the equivalent of a year's participation under the CLIA proficiency testing format (20 challenges per analyte), at least 88% would "pass," ie, achieve acceptable performance. We investigated the relationship between proficiency testing performance and several internal quality assurance practices as well as other factors commonly associated with quality performance, including analyst's professional background, monthly test volume, number of physicians served, and source of training on the instrument. The best indicator of successful performance in proficiency testing was on-site training provided by the manufacturer, as opposed to training provided by distributor personnel. We conclude that with proper on-site training and retraining, physician office laboratories will be able to meet the mandatory CLIA-88 proficiency testing requirements.

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PubMed1991

Incidence and prognostic significance of vascular invasion in 529 gastric-cancer patients.

The prognostic significance of blood-vessel invasion (BVI) and lymphatic-vessel invasion (LVI) was evaluated in a retrospective series of 529 gastric-cancer patients who underwent potentially curative surgery. Evidence for BVI was found in 127 patients (24.0%), while LVI was demonstrated in 245 patients (46.3%). The incidence of both BVI and LVI run parallel to increasing tumor size and tumor stage as well as to decreasing grade of tumor differentiation. The incidence of BVI and LVI was higher in lymph-node-positive patients than in lymph-node-negative patients. The 5-year-survival rate was significantly lower (p less than 0.0001) in patients with BVI or LVI (14.9% and 22.2% respectively) than in patients without BVI or LVI (54.7% and 64.1% respectively). Both BVI and LVI were shown to be prognostic factors independent of tumor stage, grade of differentiation or lymph-node involvement. In a multivariate Cox regression analysis, the gain of prognostic information provided by the evidence of BVI and LVI was shown to exceed the information obtained by the combination of tumor stage, grade of differentiation and lymph-node involvement. A careful search for vascular invasion in gastric cancer may therefore provide additional useful information for identifying patients who are at high risk and who may be candidates for adjuvant therapy in future clinical trials.

Adult↗
PubMed1991

Effects of soil-applied lead on seedling growth and ectomycorrhizal colonization of loblolly pine.

Six-month-old loblolly pine (Pinus taeda) were grown for 15 weeks in two native soils amended with 0, 30, 60, 120, 240 or 480 mg kg(-1) Pb as PbCl2. Ectomycorrhizae were quantified, by morphotype, as the total number of tips per centimeter, and as the number of tips for each morphotype and for Cenococcum geophilum. Total numbers of non-ectomycorrhizal short roots and necrotic tips were recorded. Total height and biomass exhibited a non-linear response to soil-applied lead. Growth generally was greatest in the controls and higher treatments, and least in the intermediate treatments. In both soils, Pb concentrations in roots increased linearly with increasing levels of soil-applied Pb. Neither foliage nor stems exhibited significant increases in Pb concentrations with increasing levels of Pb. Significant linear decreases in total numbers of ectomycorrhizal tips and significant linear increases in non-ectomycorrhizal short roots and necrotic tips occurred with increasing levels of Pb in the soil. The majority of individual morphotypes decreased with increasing Pb. However, the number of ectomycorrhizal tips formed by C. geophilium increased with increasing soil Pb levels after 15 weeks of treatment. These results indicate that short-term loblolly pine seedling growth is not inhibited by increasing Pb levels. Ectomycorrhizal formation decreased, and alterations in species composition occurred as a result of increasing concentrations of soil-applied Pb. These effects on ectomycorrhizae may cause long-term changes in nutrient and water balances, which could reduce tree vigor.

Journal Article↗
PubMed1991

Quality versus quantity: optimizing evaluation of ectomycorrhizae for plants under stress.

Many single environmental conditions or stresses have been evaluated with respect to formation and survival of ectomycorrhizae (EM). Current interests in atmospheric change include plant responses to pollutants such as ozone, sulfur dioxide, and acidic deposition in the presence of additional stress such as water deficit or plant disease. Stresses that result in formation of fewer EM or death of fine roots are evaluated routinely by quantifying EM, and results are often correlated with parameters that describe host physiology and growth. However, effects of stresses may be subtle, or identification of early plant responses may be desired. In such cases, quantification of EM may not reveal changes in EM formation by individual species of fungi if roots are colonized by other species with no net change in total numbers. Differences among frequencies of morphotypes suggest changes in species diversity of EM-forming fungi. Although the relative benefits of individual species to the host are largely unknown, information provided by qualitative assessment of EM may offer insight to define plant responses to stress and suggest additional research related to benefits of individual EM-forming fungi.

Journal Article↗
PubMed1990

Growth, ectomycorrhizae and nonstructural carbohydrates of loblolly pine seedlings exposed to ozone and soil water deficit.

Loblolly pine (Pinus taeda) seedlings from three full-sib families were exposed to 0, 50, 100 or 150 ppb ozone (O(3)) (5 h/d, 5 d/week for 6 or 12 weeks). Soil water potential was maintained near pot capacity (-0.03 MPa) or soil was allowed to dry to approximately -1.0 MPa and resaturated. Chlorotic mottling and flecking of needles due to O(3) injury were observed for seedlings from all pine families. Soil water deficit lessened the intensity of O(3) symptoms, possibly due to stomatal closure. Exposure to O(3) and soil water deficit each resulted in less seedling volume growth and dry weight, and changed the nonstructural carbohydrate content of seedlings compared with controls. Increasing O(3) concentrations resulted in a linear reduction in foliar starch content but did and affect hexose or sucrose content. Soil water deficit resulted in less starch and soluble sugar contents in above- and below-ground plant parts compared with controls. Soil water deficit did not affect numbers or percentages of roots that formed ectomycorrhizal tips. A linear dose-response relationship between O(3) and ectomycorrhizae was observed. The number of ectomycorrhizal tips/cm long root and the percentage of feeder roots that formed ectomycorrhizae were lower as O(3) concentration increased. Overall, each stress alone caused less seedling growth and carbohydrate content compared with controls, but only O(3) was responsible for suppression of ectomycorrhizae.

Journal Article↗
PubMed1989

Effects of simulated rain acidity on ectomycorrhizae of red spruce seedlings potted in natural soil.

Formation of ectomycorrhizae of red spruce (Picea rubens) grown in natural soil was measured after seedlings were exposed to 25 or 50 applications of simulated rain of pH 5.5, 3.5 or 2.5. Ectomycorrhizae were quantified as the total number of ectomycorrhizal tips per centimeter, and as the number of ectomycorrhizal tips for each morphotype and for Cenococcum geophilum. Rain solutions were applied to the soil alone, to foliage and stem alone, or to entire potted seedlings. Final soil pH was linearly related to rain solution acidity. Lower base saturation, calcium and zinc content, and higher exchangeable acidity were observed after pH 2.5 treatments if the soil was exposed. Rain solutions and the subsequent changes in soil characteristics did not affect the total numbers of ectomycorrhizal tips. Four morphotypes of ectomycorrhizae observed for these seedlings were unaffected by simulated rain. However, the numbers of ectomycorrhizal tips formed by C. geophilum tended to increase with rain solution acidity after 50 applications. Method of rain deposition did not affect ectomycorrhizae, suggesting both plant and soil mediated responses may favor certain mycobionts. The results of this study indicate that short-term acidic deposition does not induce significant changes in the frequency of ectomycorrhizae, but higher numbers of C. geophilum tips suggest there may be changes in the relative occurrence of specific morphotypes of fungus species.

Journal Article↗
PubMed1987

Mesodermal metamerism in the teleost, Oryzias latipes (the medaka).

Previous studies of the metameric pattern in mesodermal tissues of chick, mouse, turtle, and amphibian embryos have indicated that segmental characteristics exist along the entire length of the embryo. This paper describes this phenomenon in a fish embryo, for some differences in the cranial segmental plan exist between the anamniote and the amniote embryos hitherto studied. Embryos of the cyprinodont, Oryzias latipes, were fixed at various times, the examined by means of stereo scanning electron microscopy. As in other vertebrate embryos, the first indication of mesodermal metamerism in this fish embryo is the occurrence of somitomeres, which are orderly, tandemly arranged units of uncondensed mesenchymal cells in the paraxial mesoderm. As many as ten somitomeres can be observed caudal to the last formed somite to the elongating tail region. In addition, 7 somitomeres are present rostral to the first definitive somite, which is segment number eight. As in other vertebrate embryos examined, somitomeres in Oryzias embryos are circular, bilaminar arrays of paraxial mesoderm that form before any indications of segmentation can be seen with the light microscope. In the trunk region these mesodermal units condense to give rise to definitive somites, but in the head they eventually disperse. Despite a fundamentally different mode of gastrulation and a relatively small number of cells in the newly formed somitomeres, cranial segmentation in Oryzias embryos was found to be more similar in number to the metameric pattern of the embryos of the bird, reptile, and mammal than to the situation found in the two amphibians studied thus far.

Animals↗
PubMed1987

The migration of myogenic cells from the somites at the wing level in avian embryos.

This study is concerned with establishing a morphological basis for the initiation of migration of putative myogenic cells from the somites into the presumptive wing bud in avian embryos. At the 22 somite stage (stage 14) vasculogenesis is a prevalent activity. By use of a quail specific monoclonal antibody to vascular endothelial cells, vascular cells are recognized in the lateral plate, on the intermediate mesoderm, and on somite surfaces. Cells that are found between the lateral plate mesoderm and somites are shown to be vascular endothelial cells. The lateral body folds progressively bring the lateral plate mesoderm close to the lateral margin of the somites and vascular elements disappear from surface view. It is not until the 24 somite stage (stage 15) that some cells in the ventral lateral margin of somites at the wing level can be seen in scanning electron micrographs to extend basal cell processes toward adjacent vascular tubes. These results provide a morphological basis for the early migratory behavior of myogenic cells and demonstrate their close proximity to the prepatterned vascular network.

Animals↗
PubMed1984

SEM localization of laminin on the basement membrane of the chick corneal epithelium with immunolatex microspheres.

Embryonic chick corneal explants were soaked in mild detergent and the anterior corneal epithelium was peeled from its basement membrane, leaving the lamina lucida surface exposed and supported on the subjacent primary stroma. Explants were treated with rabbit anti-laminin IgG, followed by sheep anti-rabbit IgG linked microspheres, and processed for SEM. The lucida surface was heavily decorated with microspheres, whereas controls treated with preimmune rabbit IgG were essentially beadless. Laminin distribution was not regular, appearing denser in some regions than others. However, the connective tissue surface of the basement membrane was never laminin-positive, even after treatment with hyaluronidase. These results suggest the basal lamina of the corneal epithelium is asymmetric, with preferential location of laminin to the lucida surface of the basement membrane.

Animals↗
PubMed1984

Morphogenesis of the head of a newt: mesodermal segments, neuromeres, and distribution of neural crest.

Segmentation of the mesoderm in the head of a newt embryo is revealed by scanning electron microscopy. By the end of gastrulation, the newt embryo is already segmented from one end to the other, with additional segments added later by the tail bud. This metameric segmentation appears long before the first "somite" can be seen in the late neurula by light microscopy. The six segments found in the newt head look much like the six most-cranial segments described decades ago in shark embryos. Mesodermal segments in the newt head are similar to somitomeres in amniote embryos, but in amniote embryos, the numbers and relationships of head segments are quite different from those of the newt. In both amniote and newt, the first segment abuts the prosencephalon, but for each more caudal head segment, where the newt embryo has one segment, the amniote has two. Although the pattern and distribution of cranial neural crest is quite similar in newt and amniote embryos, there are different relationships between migrating crest masses and mesodermal segments due to the doubling of most of the cranial segments in amniotes. It now appears that all vertebrate embryos, regardless of their mode of gastrulation, form similar mesodermal segments from one end of the embryo to the other, and this metameric pattern is established during gastrulation.

Animals↗
PubMed1984

Morphogenesis of the cranial segments and distribution of neural crest in the embryos of the snapping turtle, Chelydra serpentina.

Recent studies of the heads of vertebrates have shown a primitive pattern of segmentation in the mesoderm and neural plate not previously recognized. The role of this pattern in the subsequent distribution of cranial crest and the development of branchial arches and cranial nerves, may resolve century-old arguments about the evolution of vertebrate segmentation. In this study, we examine the early embryonic development of the cranium of a primitive amniote, the snapping turtle, with the SEM. We show that the paraxial mesoderm cranial to the first-formed somites is segmented and that this pattern is based on somitomeres, similar to those described in the embryos of chick and mouse. Seven contiguous pairs of somitomeres comprise the "head mesoderm"; the first pair of somites actually arise from the eighth pair of somitomeres added to the axis. Cranial somitomeres are associated with specific brain regions, in that the first pair lie adjacent to prosencephalon, the second and third pair are adjacent to the mesencephalon, and the fourth, fifth, sixth, and seventh pair of somitomeres lie adjacent to individual neuromeres of the rhombencephalon. Prior to the closure of the anterior neuropore, cranial neural crest cells first emerge from the mesencephalon and migrate onto the second and third somitomeres. Shortly thereafter, neural crest cells emerge at more caudal levels of the rhombencephalon, beginning at the juncture of the fifth and sixth somitomeres. Eventually, neural crest originating from the mesencephalon spreads caudally as far as the fourth somitomere, leaving a gap in crest emigration adjacent to the fifth somitomere. The otic placode develops from the surface ectoderm covering the sixth and seventh somitomeres, and the adjacent rhombencephalic neural crest moves around the cranial and caudal edge of the placode. At more caudal levels, rhombencephalic crest cells merge with cervical crest populations to form a continuous sheet over the somites. By the time the anterior neuropore closes, some of the mesencephalic crest cells return from the paraxial mesoderm to spread onto the rostral wall of the optic vesicle and future telencephalon. The segmentation of the mesoderm and patterned distribution of cranial neural crest seen in snapping turtle embryos, further strengthens the argument that the heads of amniotes are derived from a common metameric pattern established early during gastrulation.

Animals↗
PubMed1984

Morphological and experimental studies of the somitomeric organization of the segmental plate in snapping turtle embryos.

The segmental plate mesoderm of snapping turtle embryos (Chelydra serpentina) was examined with stereoscanning electron microscopy imaging. A metameric pattern was detected along the entire length of the segmental plates. This pattern consisted of a tandem sequence of mesodermal units, called somitomeres. Each somitomere was oval to cubic in shape and the processes of the constituent mesodermal cells tended to be arranged in concentric rings about the centre of the somitomere. Several experiments from a previous study (Packard, 1980b) of snapping turtle segmental plates were repeated, but, instead of culturing the explants and observing the numbers of somites that formed, the explants were fixed immediately for scanning electron microscopy and the number of somitomeres was counted. The segmental plates were found to contain an average of 6.5 +/- 0.7 somitomeres, which is almost identical to the average number of somites formed by such segmental plates when cultured (6.6 +/- 1.2). Furthermore, the number of somitomeres was identical in right and left explants removed from the same embryo, and the number of somitomeres was consistent regardless of the length of the segmental plate. Both of these observations are identical to those made previously for somite formation in culture. This association between numbers of somitomeres and somites strongly suggests that one gives rise to the other. Finally, it was demonstrated that for each somite formed by a segmental plate in culture, the segmental plate contained one less somitomere. This showed in a direct manner that turtle somitomeres become somites. It was concluded that the segmental plate mesoderm of snapping turtle embryos is already segmented, and that the 'segmentation' seen under a dissecting microscope is actually the final stage of somitomere differentiation into an epithelial somite.

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