Echocardiographic parameters discriminating myocardial infarction with pulmonary congestion from myocardial infarction without congestion in the mouse.

Our aim was to establish parameters describing systolic and diastolic function in mice after myocardial infarction (MI) that distinguish MI with pulmonary congestion from MI without congestion. Echocardiography, left ventricular (LV) catheterization, and infarct size measurements were performed on days 3, 5, 7, and 14 after ligation of the left coronary artery in C57BL/6 mice. Sham-operated mice were used as controls (Sham). MI mice with lung weight normalized to tibial length >125% of the average in the corresponding Sham group were considered to have pulmonary congestion (MIchf). MI mice with a smaller increase were called MI nonfailing (MInf). An infarct >40% of total LV circumference measured in two-dimensional long axis distinguished MIchf from MInf on both an average and an individual basis. Mean maximum rate of rise of LV pressure, LV fractional shortening, and posterior wall shortening velocity were significantly lower in MIchf compared with Sham at all time points and to MInf at 7 days. The diastolic parameters mitral flow deceleration velocity, LV end-diastolic pressure, and maximum rate of decline in LV pressure (LVdP/dtmin) discriminated the MIchf groups from Sham at all time points. Mitral flow deceleration velocity and LVdP/dtmin separated MIchf from MInf at 7 days. In addition to distinguishing all the groups on an average basis, left atrial diameter distinguished all MIchf animals from Sham and MInf. In conclusion, significantly increased left atrial diameter and infarct size >40% of total LV circumference may serve as major criteria for heart failure with pulmonary congestion after MI in mice.     

Substructure of solitary cilia in mouse kidney

Summary Recent scanning electron microscopic studies confirm the presence of solitary cilia on most epithelial cells along the mammalian nephron and collecting ducts.By transmission electron microscopy we have found that the axonemata of such cilia consist of a maximal number of 9 doublet and no singlet filaments. 10% of the cross-sectioned cilia contain 9 doublets arranged in a peripheral ring (9+0 pattern). 30 % of the cross-sections contain 8 or 7 doublets in peripheral ring and 1 or 2 doublets in the central region (8+1 and 7+2 patterns). Serial sections and goniometer tilt reveal the central doublets to originate as dislodged peripheral doublets. 60% of the sectioned cilia contain filament numbers between 8 and 4. In patterns of 5 and 4 filaments single microtubules predominate.The functional significance of these atypical cilia is discussed.We are indebted to Prof. B. Afzelius and Prof. Th. Brun for valuable information and discussions during this work. The technical assistance of Miss K. Weltzin, Mr. E. Erichsen, Mr. R. Jensen and Mr. J. Røli is greatly appreciated     

Progressive atrophy of the thymus in mice carrying Lewis lung carcinoma grafts

Summary A rapid and progressive thymus atrophy in B₆D₂ mice following transplantation of Lewis lung carcinoma cells is reported. Spleen weight, however, increased in tumor-carrying animals. Tumor extracts failed to induce these alterations. The mechanism of these perturbations of the immune system in tumor-carrying animals is discussed.This work was supported by the Norwegian Cancer Society     

Revegetation following experimental disturbance in a boreal old-growth Picea abies forest

Abstract. We studied revegetation patterns after experimental fine-scale disturbance (e.g. uprooting) in an old-growth Picea abies forest in southeastern Norway. An experimental severity gradient was established by manipulation of the depth of soil disturbance; two types of disturbed areas were used. Species recovery was recorded in the disturbed patches in three successive years after disturbance. The cover of vascular plants and, even more so the cover of bryophytes and lichens, recovered slowly after disturbance. The least severe treatments (removal of vegetation and removal of vegetation and the litter layer) was followed by the fastest recovery. The mean number of vascular plant species was usually higher three years after disturbance than before disturbance, while the opposite was true for bryophytes. Several vascular plant species that were abundant in intact forest floor vegetation (Vaccinium myrtillus, V. vitis-idaea and Deschampsia flexuosa) recovered during a three-year period primarily by resprouting from intact rhizomes and clonal in-growth. Other important recovery mechanisms included germination from a soil-buried propagule bank (e.g. Luzula pilosa, Plagiothecium laetum agg., Pohlia nutans and Polytrichum spp.) and dispersal of propagules into the disturbed patches (e.g. Betula pubescens and Picea abies). Microsite limitation seemed to occur in several species that were abundant in the soil propagule bank (e.g. the ferns Athyrium filix-femina, Gymnocarpium dryopteris and Phegopteris connectilis) but which did not appear in disturbed patches. Disturbance severity influenced revegetation patterns, recorded both as trajectories of vegetation composition in a DCA ordination space and as change in floristic dissimilarity. The length of the successional path (compositional change measured in β-diversity units) increased with increasing disturbance severity, and was also influenced by the area of the disturbed patch and the distance to intact vegetation. The rate of succession depended on the method by which it was measured; decreasing year by year in floristic space, while first decreasing and then increasing in ordination space. The reason for this difference is explained.     

Long-term changes in crustacean zooplankton--the effects of a mass removal of Arctic chan, Salvelinus alpinus (L.), from an oligotrophic lake

The long-term effects of the removal of     

Why the free floating macrophyte Stratiotes aloides mainly grows in highly CO2-supersaturated waters

We examined how the freely floating macrophyte, Stratiotes aloides L., sampled from a CO₂-supersaturated pond, changes leaf morphology, photosynthesis and inorganic carbon acquisition during its different submerged and emerged life stages in order to evaluate whether S. aloides requires consistently supersaturated CO₂ conditions to grow and complete its life cycle. Submerged rosettes formed from over-wintering turions had typical traits of submerged plants with high specific leaf area and low chlorophyll a concentrations. Emergent leaf parts of mature, floating specimens had typical terrestrial traits with stomata, low specific leaf area and high chlorophyll a content, while offsets formed vegetatively and basal, submerged parts of mature plants showed traits in between. All submerged leaf types exhibited some ability to use HCO₃⁻ but only rosettes formed from turions had efficient HCO₃⁻ use. Rosettes also had the highest CO₂ affinity and maximum CO₂-saturated photosynthesis in water. Half-saturation constants for CO₂ (21–74 μM CO₂) were for all submerged leaf parts 5–140 times lower than the concentrations of free CO₂ in the pond (350–2800 μM CO₂). Emergent leaves were less efficient in water but had significantly higher photosynthesis than submerged, mature leaf parts in air, and rates of photosynthesis of emergent leaves in air were three to five times higher than rates of CO₂-saturated photosynthesis of the three submerged leaf types in water. Underwater photosynthetic rates estimated at CO₂ concentrations corresponding to air equilibrium were not sufficiently high to support any noticeable growth except for rosettes, in which bicarbonate utilization combined with high CO₂ affinity resulted in photosynthetic rates corresponding to almost 34% of maximum rates at high free CO₂. We conclude that S. aloides requires consistently high CO₂-supersaturation to support high growth and to complete its life cycle, and we infer that this requirement explains why S. aloides mainly grows in ponds, ditches and reed zones that are characterized by strong CO₂-supersaturation.