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- Hellquist, Henrik B., et al.
(författare)
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Salivary duct carcinoma : a highly aggressive salivary gland tumour with overexpression of c-erbB-2
- 1994
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Ingår i: Journal of Pathology. - West Sussex, United Kingdom : John Wiley & Sons. - 0022-3417 .- 1096-9896. ; 172:1, s. 35-44
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Tidskriftsartikel (refereegranskat)abstract
- The clinicopathological and immunocytochemical features of nine cases of salivary duct carcinoma are described. This relatively rare tumour, which only recently has been widely recognized as a separate entity, is highly malignant and caused the death in eight of the patients. The tumour cells are arranged in cribriform and solid growth patterns, where the solid tumour nests frequently have comedo necrosis, and a fibrous, often sclerotic, stroma is present. The infiltrating desmoplasmic component and the diffuse invasive growth into adjacent adipose parotid tissue have similarities to ductal breast carcinoma. Immunocytochemical investigation of salivary duct carcinoma showed constant overexpression of c-erbB-2 as detected by membrane accentuation, and high proliferative activity as detected by nuclear positivity for MIB 1 (Ki-67). Changes in the expression of p53 and retinoblastoma gene product do not constitute a constant event in salivary duct carcinoma. A few of the tumours showed scattered cells with distinct nuclear positivity for both progesterone and oestrogen receptors. We emphasize that this highly malignant salivary gland tumour has a characteristic morphology, may not be as rare as previously considered, and that prompt and aggressive therapy is needed.
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| 2. |
- Johansson, Mats E., 1959-
(författare)
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Population biology of the clonal plant Ranunculus lingua
- 1992
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The scope of this thesis was to identify, describe and quantify important life-history traits for the pseudoannual aquatic plant Ranunculus lingua in different ecological settings, by comparing populations from geographically marginal vs. central habitats.Results from a four-year field study showed that abiotic factors (water-level fluctuations and associated processes) tended to have a greater influence in marginal populations, whereas biotic factors (competition, insect grazing and fungal infections) dominated in central populations. This was reflected in different depth distribution of ramet numbers and ramet sizes between the areas, and In different dynamic patterns, with a higher flux of ramets in marginal populations.In a reciprocal transplant experiment, marginal ramets produced more but smaller rhizomes, whereas central ramets produced Individually larger but fewer rhizomes, irrespective of transplant site. A possible selection for genotypes producing large rhizomes in the central habitat was supported by the fact that initially smaller ramets were more likely to be diseased by the fungal pathogen Peronospora gigantea and damaged by insect grazing. In the marginal population, where density-independent mortality factors tend to dominate, a high reproductive output, expressed in production of high numbers of rhizomes, was suggested to be a favoured life-history trait.In a glasshouse experiment, ramets from marginal and central populations were grown in low and high densities and under three contrasting nutrient levels. The allocation to sexual structures was generally very low, and did not incur any costs in terms of reduced rhizome production. Rhizome production showed strong positive allometrical relationships to mother ramet size. Increasing mother ramet size resulted in a larger increase in rhizome numbers for the marginal than for the central population, whereas the increase in mean rhizome mass was more pronounced for the centred population. Both populations showed similar reductions in rhizome production in response to increased density and lowered nutrient levels, which could not be explained by size-dependent effects adone.The dispersal, dynamics and distribution of R. lingua were studied in a marginal river population in northern Sweden, where the only means of dispersal is by vegetative diaspores, i.e. floating rhizome fragments. Stranding occurred mainly in river curves and at obstacles, and the distribution of established stands was also highly correlated with these features. Relative changes in ramet numbers were correlated with water-level fluctuations during the present and previous growing seasons, with winter low-water, and with duration of spring-flood. The predictability of change was high within but low between stands. It was concluded that the patterns and mechanisms of dispersal are fundamental for local distribution patterns as well as variation in regional abundance in R. lingua
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| 3. |
- Nilsson, Christer, et al.
(författare)
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A Comparison of Species Richness and Traits of Riparian Plants between a Main River Channel and Its Tributaries
- 1994
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Ingår i: Journal of Ecology. - : JSTOR. - 0022-0477 .- 1365-2745. ; 82:2, s. 281-295
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Tidskriftsartikel (refereegranskat)abstract
- Summary1 We examined differences in species richness and frequencies of vascular plants in the riverbank vegetation between the main channel of the Vindel River system and seven of its tributaries which spanned the same biogeographic range.2 Species richness per site was higher in the main channel than in the tributaries, both as a whole and for many species groups. The proportions of woody plants (phanerophytes and chamaephytes), geophytes, and natural species were higher in the tributaries, while the proportions of hemicryptophytes, ruderals, and short-floating species (i.e. species unable to float > 1 day) were higher in the main channel. Both types of river had species that were more than twice as frequent there than in the other category.3 The main channel had a high species richness at intermediate altitudes whereas the tributaries had least species at intermediate altitudes. Except for the highest altitudes, the tributaries also had a generally lower mean species richness than the main channel.4 Stepwise multiple regression analyses using 15 predictor variables explained stat- istically up to 85% of the floristic variation in the river system. Mean annual discharge and number of substrates explained most of the variation in five equations each, while peat cover explained most of the variation in four equations, and altitude and silt cover in one equation each. Mean annual discharge, peat cover and silt cover differed between the main channel and the tributaries and could therefore be responsible for the observed difference.
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