The effect of past changes in inter‐annual temperature variability on tree distribution limits

Aim The northern limits of temperate broadleaved species in Fennoscanndia are controlled by their requirements for summer warmth for successful regeneration and growth as well as by the detrimental effects of winter cold on plant tissue. However, occurrences of meteorological conditions with detrimental effects on individual species are rare events rather than a reflection of average conditions. We explore the effect of changes in inter‐annual temperature variability on the abundances of the tree species Tilia cordata, Quercus robur and Ulmus glabra near their distribution limits using a process‐based model of ecosystem dynamics. Location A site in central Sweden and a site in southern Finland were used as examples for the ecotone between boreal and temperate forests in Fennoscandia. The Finnish site was selected because of the availability of varve‐thickness data. Methods The dynamic vegetation model LPJ‐GUESS was run with four scenarios of inter‐annual temperature forcing for the last 10,000 years. In one scenario the variability in the thickness of summer and winter varves from the annually laminated lake in Finland was used as a proxy for past inter‐annual temperature variability. Two scenarios were devised to explore systematically the effect of stepwise changes in the variance and shape parameter of a probability distribution. All variability scenarios were run both with and without the long‐term trend in Holocene temperature change predicted by an atmospheric general circulation model. Results Directional changes in inter‐annual temperature variability have significant effects on simulated tree distribution limits through time. Variations in inter‐annual temperature variability alone are shown to alter vegetation composition by magnitudes similar to the magnitude of changes driven by variation in mean temperatures. Main conclusions The varve data indicate that inter‐annual climate variability has changed in the past. The model results show that past changes in species abundance can be explained by changes in the inter‐annual variability of climate parameters as well as by mean climate. Because inter‐annual climatic variability is predicted to change in the future, this component of climate change should be taken into account both when making projections of future plant distributions and when interpreting vegetation history.     

The effect of interstimulus interval on somatosensory point localization

Somatosensory point localization is a clinical test evaluating spatial accuracy of the somatosensory system. Possible effects of the interstimulus interval (ISI) on point localization threshold have not been previously examined. In the present set of experiments the effect of time delay on somatosensory point localization was studied using ISIs of 1, 3, 5, 7, and 9 s, and applying a newly developed computer-controlled application method of a Semmes-Weinstein monofilament. It was found that the point localization threshold was not significantly affected by the ISI length. However, the response time was shorter and response accuracy better at the shorter (1 and 3 s) than at the longer (5, 7, and 9 s) ISIs, suggesting a change in the mechanism underlying point localization decision criteria in ISIs longer than 3 s.     

Effects of electromagnetic field emitted by cellular phones on the EEG during an auditory memory task: a double blind replication study

The effects of electromagnetic fields (EMF) emitted by cellular phones on the event related desynchronization/synchronization (ERD/ERS) of the 4-6, 6-8, 8-10, and 10-12 Hz electroencephalogram (EEG) frequency bands were studied in 24 normal subjects performing an auditory memory task. This study was a systematic replication of our previous work. In the present double blind study, all subjects performed the memory task both with and without exposure to a digital 902 MHz field in a counterbalanced order. We were not able to replicate the findings from our earlier study. All eight of the significant changes in our earlier study were not significant in the present double blind replication. Also, the effect of EMF on the number of incorrect answers in the memory task was inconsistent. We previously reported no significant effect of EMF exposure on the number of incorrect answers in the memory task, but a significant increase in errors was observed in the present study. We conclude that EMF effects on the EEG and on the performance on memory tasks may be variable and not easily replicable for unknown reasons.     

Immune responses to Puumala virus infection and the pathogenesis of nephropathia epidemica

Puumala virus, causative agent of a mild form of hemorrhagic fever with renal syndrome, also known as nephropathia epidemica, induces long-lasting humoral and cellular immunity in patients. The virus itself is not cytopathic, and the immune responses to the virus may be involved in teh pathogenesis of the disease.     

Angeli's salt and spinal motor neuron injury

Nitroxyl anion or its conjugate acid (NO_-/HNO) and nitric oxide (NO) may both have pro-oxidative and cytotoxic properties. Superoxide dismutase (SOD) enzyme has been shown to convert reversibly HNO to NO. Mutations found in the SOD enzyme in some familial amyotrophic lateral sclerosis (ALS) patients affect redox properties of the SOD enzyme in a manner, which may affect the equilibrium between NO and HNO. Therefore, we studied the effects of HNO releasing compound, Angeli's salt (AS), on both motor and sensory functions after intrathecal administration in the lumbar spinal cord of a male rat. These functions were measured by rotarod, spontaneous activity, paw- and tail-flick tests. In addition, we compared the effect of AS to NO releasing papanonoate, old AS solution and sulphononoate in the motor performance test. The effect of intrathecal delivery of AS on the markers of the spinal cord injury and oxidative/nitrosative stress were further studied.

Results: Freshly prepared AS (5 or 10 μmol), but not papanonoate, caused a marked decrease in the rotarod performance 3-7 days after the intrathecal administration. The peak motor deficiency was noted 3 days after AS (5 μmol) delivery. Old, degraded, AS solution and nitrous oxide releasing sulphononoate did not decrease motor performance in the rotarod test. AS did not affect the sensory stimulus evoked responses as measured by the paw-flick and tail-flick tests. Immunohistological examination revealed that AS caused injury related changes in the expression of glial fibrillary acidic protein (GFAP), fibroblast growth factor (FGF-2) and laminins in the spinal cord. Moreover, AS increased nitrotyrosine immunoreactivity in the spinal motor neurons.

Therefore, we conclude that AS, but not NO releasing papanonoate, causes motor neuron injury but does not affect the function of sensory nerves in behavioural tests.     

Effects of training on the exercise-induced changes in serum amino acids and hormones

The purpose of this study was to examine power-type athletes to determine changes in amino acid and hormone concentrations in circulating blood following 2 different high-intensity exercise sessions before and after the 5-week training period. Eleven competitive male sprinters and jumpers performed 2 different running exercise sessions: a short run session (SRS) of 3 x 4 x 60 m (intensity of 91-95%) with recoveries of 120 and 360 seconds, and a long run session (LRS) with 20-second intervals (intensity of 56-100%) with recoveries of 100 seconds to exhaustion. The concentrations of serum amino acids, hormones, and lactate were determined from the blood samples drawn after an overnight fast and 10 minutes before and after both SRS and LRS. The average blood lactate concentrations were 12.7 +/- 1.6 mmol;pdL(-1) and 16.6 +/- 1.4 mmol;pdL(-1) (p < 0.01) following SRS and LRS, respectively. The average total running time was longer (p < 0.001) following LRS (164 +/- 20 seconds) than following SRS (91 +/- 8 seconds). The fasting levels of all amino acids decreased (p = 0.024; 19.4%) after the 5-week period, whereas an increase (p = 0.007; 24.5%) was observed in the fasting concentration of testosterone (TE). The exercise sessions induced no changes in the total sum of all amino acids, but significant increases or decreases were observed in single amino acids. When the range of the relative concentration changes before and after the training period was compared, significant decreases were found in valine (p = 0.048), asparagine (p = 0.029), and taurine (p = 0.030) following SRS. There were significant increases in the absolute hormonal concentration changes following LRS with TE (p = 0.002; 30.4%), cortisol (COR; p = 0.006; 12.0%), and in the TE/COR ratio (p = 0.047; 21.0%) but not in the concentration of growth hormone (GH). The results of the study indicate that the speed and strength training period strongly decreases the fasting concentrations of amino acids in the power-trained athletes in a good anabolic state with the daily protein intake of 1.26 g;pdkg(-1) body weight. At the same time the intensive lactic exercise session induces strong decreases, especially in valine, asparagine, and taurine.     

Expression of transmembrane carbonic anhydrase isoenzymes IX and XII in normal human pancreas and pancreatic tumours

Carbonic anhydrase (CA) IX and XII are transmembrane isoenzymes which are expressed in several epithelia and overexpressed in some carcinomas. They have recently been linked to von Hippel-Lindau gene-mediated carcinogenesis in that both isoenzymes are downregulated by the product of the wild-type von Hippel-Lindau tumour suppressor gene. This paper describes the localisation of CA IX and XII in the normal human pancreas and pancreatic tumours. Both isoenzymes showed positive reaction in the basolateral plasma membrane of the normal acinar and ductal epithelia. The hyperplastic ductal epithelium in tumour specimens generally showed an increased staining for CA IX. Of 29 malignant tumours of exocrine pancreas, 10 showed moderate or strong immunoreaction for CA IX. The signal for CA XII remained weak in most malignant lesions. The present results show that both CA IX and XII are unevenly expressed in the ductal and acinar compartments of the human pancreas. The expression of these isoenzymes in a relatively low number of malignant tumour specimens suggests that they have a limited value in diagnostic evaluation of pancreatic carcinoma. However, the increased expression of CA IX in hyperplastic ductal epithelium may contribute to the pancreatic tumourigenesis.     

FLUCTUATING ASYMMETRY IN CENTRAL AND MARGINAL POPULATIONS OF LYCHNIS VISCARIA IN RELATION TO GENETIC AND ENVIRONMENTAL FACTORS

Developmental instability in the form of increased fluctuating asymmetry can be caused by either genetic or environmental stress. Because extinctions can be attributed broadly to these factors, fluctuating asymmetry may provide a sensitive tool for detecting such stresses. We studied the level of fluctuating asymmetry of flowers of a perennial outcrossing plant species, Lychnis viscaria, both in natural and common-garden populations. The degree of flower asymmetry was higher in small, isolated, and marginal populations of the species range. These marginal populations also were the most homozygous. In the core area of the species' range, flowers were more symmetrical The level of asymmetry was correlated with both population size and heterozygosity. However, a partial correlation analysis revealed that when the impact of population size was controlled for, there was a negative relationship between fluctuating asymmetry and heterozygosity, whereas when controlling for heterozygosity, no relationship between population size and fluctuating asymmetry was found. This indicates that genetic consequences of small population size probably underlie the relationship between the level of asymmetry and population size. Results from a transplantation experiment showed that individuals subjected to a higher environmental stress had an increased level of asymmetry compared to control plants. In the common-garden conditions the level of fluctuating asymmetry did not differ between the central and marginal populations. This suggests that presumably both genetic and environmental factors affected to the higher level of asymmetry among marginal populations compared to central ones. In all we conclude that even though fluctuating asymmetry seems to be a sensitive tool for detecting stresses, results from studies focusing on only one factor should be interpreted with caution.     

Increased Visceral Adipose Tissue as a Potential Risk Factor in Patients with Embolic Stroke of Undetermined Source (ESUS)

Purpose

The etiology of an ischemic stroke remains undetermined in 20–35% of cases and many patients do not have any of the conventional risk factors. Increased visceral adipose tissue (VAT) is a suggested new risk factor for both carotid artery atherosclerosis (CAA) and atrial fibrillation (AF), but its role in the remaining stroke population is unknown. We assessed the amount of VAT in patients with embolic stroke of undetermined source (ESUS) after excluding major-risk cardioembolic sources, occlusive atherosclerosis, and lacunar stroke.

Methods

Altogether 58 patients (mean age 57.7±10.2 years, 44 men) with ischemic stroke of unknown etiology but without CAA, known AF or small vessel disease underwent computed tomography angiography and assessment of VAT. For comparison VAT values from three different reference populations were used. Conventional risk factors (smoking, hypertension, diabetes, increased total and LDL-cholesterol, decreased HDL-cholesterol) were also registered.

Results

Mean VAT area was significantly higher in stroke patients (205±103 cm² for men and 168±99 cm² for women) compared to all reference populations (P<0.01). 50% of male and 57% of female patients had an increased VAT area. In male patients, VAT was significantly higher despite similar body mass index (BMI). Increased VAT was more common than any of the conventional risk factors.

Conclusion

Increased VAT was found in over half of our patients with ESUS suggesting it may have a role in the pathogenesis of thromboembolism in this selected group of patients.