Resistance of Scots pine wood to Brown-rot fungi after long-term forest fertilization

The susceptibility of Scots pine (Pinus sylvestris L.) sap- and heartwood against the wood decaying brown-rot fungus (Coniophora puteana) was investigated after long-term forest fertilization at three different sites in central Finland. Different wood properties: wood extractives, wood chemistry, and wood anatomy were used to explain sap- and heartwood decay. Scots pine sapwood was more susceptible to decay than its heartwood. In one site, sapwood seemed to be more resistant to wood decay after forest fertilization whereas the susceptibility of heartwood increased. Significant changes in the sapwood chemistry were found between treatment and sites, however, no relationship between wood chemistry and wood decay was observed in the factor analysis. The results of this study show that there was an inconsistent relationship between decay susceptibility and fertilization and the measured physical and chemical attributes of the wood were not consistently correlated with the decay rate.     

C-peptide improves adenosine-induced myocardial vasodilation in type 1 diabetes patients

Patients with type 1 (insulin-dependent) diabetes show reduced skeletal muscle blood flow and coronary vasodilatory function despite intensive insulin therapy and good metabolic control. Administration of proinsulin C-peptide increases skeletal muscle blood flow in these patients, but a possible influence of C-peptide on myocardial vasodilatory function in type 1 diabetes has not been investigated. Ten otherwise healthy young male type 1 diabetic patients (Hb A1c 6.6%, range 5.7-7.9%) were studied on two consecutive days during normoinsulinemia and euglycemia in a double-blind, randomized, crossover design, receiving intravenous infusion of C-peptide (5 pmol.kg-1.min-1) for 120 min on one day and saline infusion on the other day. Myocardial blood flow (MBF) was measured at rest and during adenosine administration (140 microg.kg-1.min-1) both before and during the C-peptide or saline infusions by use of positron emission tomography and [15O]H2O administration. Basal MBF was not significantly different in the patients compared with an age-matched control group, but adenosine-induced myocardial vasodilation was 30% lower (P < 0.05) in the patients. During C-peptide administration, adenosine-stimulated MBF increased on average 35% more than during saline infusion (P < 0.02) and reached values similar to those for the healthy controls. Moreover, as evaluated from transthoracal echocardiographic measurements, C-peptide infusion resulted in significant increases in both left ventricular ejection fraction (+5%, P < 0.05) and stroke volume (+7%, P < 0.05). It is concluded that short-term C-peptide infusion in physiological amounts increases the hyperemic MBF and left-ventricular function in type 1 diabetic patients.     

Fluorescent nanoparticles as labels for immunometric assay of C-reactive protein using two-photon excitation assay technology

We describe the use of fluorophore-doped nanoparticles as reporters in a recently developed ArcDia TPX bioaffinity assay technique. The ArcDia TPX technique is based on the use of polymer microspheres as solid-phase reaction carrier, fluorescent bioaffinity reagents, and detection of two-photon excited fluorescence. This new assay technique enables multiplexed, separation-free bioaffinity assays from microvolumes with high sensitivity. As a model analyte we chose C-reactive protein (CRP). The assay of CRP was optimized for assessment of CRP baseline levels using a nanoparticulate fluorescent reporter, 75 nm in diameter, and the assay performance was compared to that of CRP assay based on a molecular reporter of the same fluorophore core. The results show that using fluorescent nanoparticles as the reporter provides two orders of magnitude better sensitivity (87 fM) than using the molecular label, while no difference between precision profiles of the different assay types was found. The new assay method was applied for assessment of baseline levels of CRP in sera of apparently healthy individuals.     

Seasonal changes in thermal responses of urban residents to cold exposure

To determine whether urban circumpolar residents show seasonal acclimatisation to cold, thermoregulatory responses and thermal perception during cold exposure were examined in young men during January-March (n=7) and August-September (n=8). Subjects were exposed for 24 h to 22 and to 10 degrees C. Rectal (T(rect)) and skin temperatures were measured throughout the exposure. Oxygen consumption (VO(2)), finger skin blood flow (Q(f)), shivering and cold (CDT) and warm detection thresholds (WDT) were assessed four times during the exposure. Ratings of thermal sensations, comfort and tolerance were recorded using subjective judgement scales at 1-h intervals. During winter, subjects had a significantly higher mean skin temperature at both 22 and 10 degrees C compared with summer. However, skin temperatures decreased more at 10 degrees C in winter and remained higher only in the trunk. Finger skin temperature was higher at 22 degrees C, but lower at 10 degrees C in the winter suggesting an enhanced cold-induced vasoconstriction. Similarly, Q(f) decreased more in winter. The cold detection threshold of the hand was shifted to a lower level in the cold, and more substantially in the winter, which was related to lower skin temperatures in winter. Thermal sensations showed only slight seasonal variation. The observed seasonal differences in thermal responses suggest increased preservation of heat especially in the peripheral areas in winter. Blunted vasomotor and skin temperature responses, which are typical for habituation to cold, were not observed in winter. Instead, the responses in winter resemble aggravated reactions of non-cold acclimatised subjects.     

Induction of SOS response,cellular efflux and oxidative stress response genes by chlorambucil in DNA repair-deficient Escherichia coli cells (ada,ogt and mutS)

Chlorambucil (CLB) is a bifunctional alkylating drug widely used as an anticancer agent and as an immunosuppressant. It is known to be mutagenic, teratogenic and carcinogenic. The cellular actions of CLB have remained poorly investigated. It is very likely that DNA damage and its repair are the key elements determining the destiny of CLB-exposed cells. We investigated the role of two specific DNA repair pathways involved in CLB-induced mutagenicity and gene expression changes by using Escherichia coli strains lacking either (i) two DNA methyltransferase functions (O(6)-methylguanine-DNA methyltransferase I (ada) and II (ogt)), or (ii) mismatch repair (MutS (mutS)). Mutagenicity was determined as the development of ciproxin and rifampicin resistance and the gene expression changes were assessed using expression profiling of all E. coli 4290 open reading frames (ORFs) by cDNA array. Chlorambucil-induced mutants in mutS cells, implying the importance of mismatch repair in preventing CLB-induced mutations. It also induced mutants in the ada, ogt strain, but to a lesser extent than in the wild-type strain. The simultaneous upregulation of several genes of the SOS response, cellular efflux and oxidative stress response, was demonstrated in both of the DNA repair-deficient strains but not in the wild-type cells. These and our previous results show that single-gene knock-out cells use specific gene regulation strategies to avoid mutations and cell death induced by agents such as chlorambucil.     

Skeletal muscle blood flow and flow heterogeneity during dynamic and isometric exercise in humans

The effects of dynamic and intermittent isometric knee extension exercises on skeletal muscle blood flow and flow heterogeneity were studied in seven healthy endurance-trained men. Regional muscle blood flow was measured using positron emission tomography (PET) and an [(15)O]H(2)O tracer, and electromyographic (EMG) activity was recorded in the quadriceps femoris (QF) muscle during submaximal intermittent isometric and dynamic exercises. QF blood flow was 61% (P = 0.002) higher during dynamic exercise. Interestingly, flow heterogeneity was 13% (P = 0.024) lower during dynamic compared with intermittent isometric exercise. EMG activity was significantly higher (P < 0.001) during dynamic exercise, and the change in EMG activity from isometric to dynamic exercise was tightly related to the change in blood flow in the vastus lateralis muscle (r = 0.98, P < 0.001) but not in the rectus femoris muscle (r = -0.09, P = 0.942). In conclusion, dynamic exercise causes higher and less heterogeneous blood flow than intermittent isometric exercise at the same exercise intensity. These responses are, at least partly, related to the increased EMG activity.     

Metabolic stability of alpha-methylated polyamine derivatives and their use as substitutes for the natural polyamines

Metabolically stable polyamine derivatives may serve as useful surrogates for the natural polyamines in studies aimed to elucidate the functions of individual polyamines. Here we studied the metabolic stability of alpha-methylspermidine, alpha-methylspermine, and bis-alpha-methylspermine, which all have been reported to fulfill many of the putative physiological functions of the natural polyamines. In vivo studies were performed with the transgenic rats overexpressing spermidine/spermine N(1)-acetyltransferase. alpha-Methylspermidine effectively accumulated in the liver and did not appear to undergo any further metabolism. On the other hand, alpha-methylspermine was readily converted to alpha-methylspermidine and spermidine; similarly, bis-alpha-methylspermine was converted to alpha-methylspermidine to some extent, both conversions being inhibited by the polyamine oxidase inhibitor N(1), N(2)-bis(2,3-butadienyl)-1,4-butanediamine. Furthermore, we used recombinant polyamine oxidase, spermidine/spermine N(1)-acetyltransferase, and the recently discovered spermine oxidase in the kinetic studies. In vitro studies confirmed that methylation did not protect spermine analogs from degradation, whereas the spermidine analog was stable. Both alpha-methylspermidine and bis-alpha-methylspermine overcame the proliferative block of early liver regeneration in transgenic rats and reversed the cytostasis induced by an inhibition of ornithine decarboxylase in cultured fetal fibroblasts.     

Antitumor activity and metal complexes of the first transition series. Trans-bis(salicylaldoximato)copper(II) and related copper(II) complexes,a novel group of potential antitumor agents

The antitumor activity of forty nine different metal complexes of the first transition series against mouse leukemia L 1210 cells and of two of the complexes against Ehrlich ascites carcinoma have been tested in vitro by the method described in this paper. Eight complexes showed a 50% inhibition of tumor cell division at concentration level 5–6 μg/ml of the complex for the former and two most effective complexes also for the latter. The trans-bis-(salicylaldoximato)copper(II) and trans-bis(resorcylaldoximato)copper(II) complexes were found to possess the highest antitumor activity.     

Bovine αs1-casein gene sequences direct high level expression of human granulocyte-macrophage colony-stimulating factor in the milk of transgenic mice

The generation is reported of transgenic mice expressing human granulocyte-macrophage colony-stimulating factor (GM-CSF) or human erythropoietin (EPO) under the control of bovine s1- casein regulatory sequences. GM-CSF expression was specific to the mammary gland, and levels of human GM-CSF in transgenic mouse milk were in the range of mg ml–1. The specific activity of the milk GM-CSF was similar to that of the recombinant protein produced in Escherichia coli, and the glycosylation-derived size heterogeneity corresponded to that of the native human protein. In spite of the identical bovine regulatory sequences of the fusion genes, the levels of human EPO in transgenic mouse milk were 103--106 times lower than those of GM-CSF, ranging from 0.003 to 3 g ml–1. There appeared to be a positive correlation between the amount of EPO in the milk of lactating females and blood haematocrit values. In view of this, other type of constructs should be used to achieve more efficient EPO expression and to circumvent concomitantly-occurring adverse effects. In contrast, the high-level production of recombinant GM-CSF, its resemblance to the native mammalian protein, and mild adverse consequences of transgene expression imply that the current construct could be used for generation of larger GM-CSF transgenic anim als to produce this protein in quantities sufficient for therapeutic purposes