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51.
Tree structural diversity is assessed by modelling stand diameter at breast height (DBH) distribution. The aim of this study
was to verify the suitability of a mixture of two- and three-component Weibull and gamma models for describing irregular and
multimodal DBH distributions. Investigations were carried out in natural Abies alba Mill. and Fagus sylvatica L. stands, representing the growing-up stage, in the Świętokrzyski National Park (Central Poland) and in the Pieniny National
Park (Southern Poland). Sample plots (0.25–0.5 ha in area) were selected from a database used for forest dynamics analysis.
The parameters of the mixture model were estimated using maximum likelihood estimation (MLE) and a combination of an expectation–maximisation
(EM) algorithm with a Newton-type (NT) method. The multistart method (MM) of choosing initial values was used. The DBH distributions
in mixed Abies–Fagus forests of complex structure were accurately approximated by two- and three-component mixture models. The root mean square
error (RMSE) values varied from 3.4515 to 7.6682 for the Weibull mixture and from 3.6457 to 7.1419 for the gamma mixture.
The results indicated that the mixture Weibull and gamma models were, in general, equally suitable for modelling irregular
and multimodal DBH distributions. Finite mixture models may be used to characterise tree structural diversity, especially
in uneven-aged stands of complex structure. 相似文献
52.
David Gunnarsson Gunnar Selstam Yvonne Ridderstr?le Lena Holm Elisabeth Ekstedt Andrzej Madej 《Acta veterinaria Scandinavica》2009,51(1):51
Background
Exposure to xenoestrogens in humans and animals has gained increasing attention due to the effects of these compounds on reproduction. The present study was undertaken to investigate the influence of low-dose dietary phytoestrogen exposure, i.e. a mixture of genistein, daidzein, biochanin A and formononetin, on the establishment of testosterone production during puberty in male goat kids.Methods
Goat kids at the age of 3 months received either a standard diet or a diet supplemented with phytoestrogens (3 - 4 mg/kg/day) for ~3 months. Plasma testosterone and total and free triiodothyronine (T3) concentrations were determined weekly. Testicular levels of testosterone and cAMP were measured at the end of the experiment. Repeated measurement analysis of variance using the MIXED procedure on the generated averages, according to the Statistical Analysis System program package (Release 6.12, 1996, SAS Institute Inc., Cary, NC, USA) was carried out.Results
No significant difference in plasma testosterone concentration between the groups was detected during the first 7 weeks. However, at the age of 5 months (i.e. October 1, week 8) phytoestrogen-treated animals showed significantly higher testosterone concentrations than control animals (37.5 nmol/l vs 19.1 nmol/l). This elevation was preceded by a rise in plasma total T3 that occurred on September 17 (week 6). A slightly higher concentration of free T3 was detected in the phytoestrogen group at the same time point, but it was not until October 8 and 15 (week 9 and 10) that a significant difference was found between the groups. At the termination of the experiment, testicular cAMP levels were significantly lower in goats fed a phytoestrogen-supplemented diet. Phytoestrogen-fed animals also had lower plasma and testicular testosterone concentrations, but these differences were not statistically significant.Conclusion
Our findings suggest that phytoestrogens can stimulate testosterone synthesis during puberty in male goats by increasing the secretion of T3; a hormone known to stimulate Leydig cell steroidogenesis. It is possible that feedback signalling underlies the tendency towards decreased steroid production at the end of the experiment. 相似文献53.
54.
Witold Wielkopolski Robert
mieszek Stanislaw Witek Andrzej Dabrowski Piotr Wieczorek Barbara Lejczak Pawel Kafarski 《Pest management science》1994,40(2):107-112
Isoxazole-substituted 1-aminoethyl- and 1-hydroxyethyiphosphonates were synthesized by a multi-step procedure and were screened for herbicidal activity against Lepidium sativum L. and Cucumis sativus L. All the synthesized compounds exhibited notable herbicidal activity. 相似文献
55.
Effect of coniferyl alcohol addition on removal of chlorophenols from water effluent by fungal laccase 总被引:2,自引:0,他引:2
Nam-Seok Cho Jerzy Rogalski Magdalena Jaszek Jolanta Luterek Maria Wojtas-Wasilewska Elzbieta Malarczyk Monika Fink-Boots Andrzej Leonowicz 《Journal of Wood Science》1999,45(2):174-178
The effect of coniferyl alcohol on removal of chlorinated phenols from a water environment byRhizoctonia praticola andCerrena unicolor laccases was studied. At optimal conditions in which 7 mM coniferyl alcohol and laccase were added to chlorinated phenols over 20h, about 34% of the radioactivity of 4-chlorophenol, 57% of 2,4-dichlorophenol, 66% of 2,4,5-trichlorophenol, and 85% of pentachlorophenol were removed from the supernatants, compared to the level without laccase activity. After 12-h incubation periods at the optimal concentrations of coniferyl alcohol and laccase (added simultaneously), the fast first phase of chlorophenol removal was complete in 1 h, and eventually coniferyl alcohol enhanced the removal of 4-chlorophenol by 40%, 2,4-dichlorophenol by 54%, 2,4,5-trichlorophenol by 60%, and pentachlorophenol by 76%. 相似文献
56.
Andrzej K Siwicki Zdzisaw Zak Elbieta Terech-Majewska Agata Kowalska & Joanna Maaczewska 《Aquaculture Research》2009,40(4):405-411
This study examined the influence of β‐1.3/1.6‐glucan (MacroGard) on the innate immune system in healthy pikeperch (Sander lucioperca) juveniles. MacroGard was fed in a pelleted ration of 1 or 2 g kg?1 feed for 6 weeks. The control group of fish was fed feed with no supplement. Blood, pronephros and spleen samples for the study of nonspecific cellular and humoral defense mechanisms were collected from 10 fish from each group. No changes were observed in either the behaviour or the health of the fish throughout the rearing period. Fish mortality was not noted in any of the groups. Additionally, the supplementation of feed with MacroGard did not have a significant impact on the fish growth rate as expressed in both absolute and relative values (P>0.05). The condition of the fish from the experimental group did not differ from that of the control group specimens, and the feed conversion ratios were also very similar (P>0.05). The results showed that MacroGard administered in two doses significantly (P<0.05) activated the metabolic activity and potential killing activity of spleen phagocytes, compared with the control‐fed pikeperch. The highest phagocyte activity was observed with a dose of 2 g kg?1. The proliferative response of pronephros lymphocytes indicated a similar pattern. MacroGard significantly increased proliferative response of lymphocytes stimulated by mitogens (P<0.05). MacroGard also significantly increased the lysozyme activity and total immunoglobulin levels in the serum. In this study neither significantly different ceruloplasmine activity or total protein level in serum were observed. The result showed that MacroGard at the optimal dose of 1 g kg?1 feed and a twofold higher dose does not have a negative influence on the hepatocytes or increased nonspecific cell‐ and humoral‐mediated immunity in healthy pikeperch. 相似文献
57.
Irene Sartini Beata ebkowska‐Wieruszewska Andrzej Lisowski Amnart Poapolathep Barbara Cuniberti Mario Giorgi 《Journal of veterinary pharmacology and therapeutics》2021,44(1):28-35
Acetaminophen (paracetamol) is used in dogs to manage fever and mild pain. The aim of this study was to assess the pharmacokinetics of acetaminophen in both fed and fasted Labrador Retrievers after a single intravenous and oral administration (20 mg/kg). Six healthy dogs underwent three treatments in a randomized block study (a, n = 2; b, n = 2; c, n = 2). In phase one, group a received acetaminophen intravenously, group b and c orally after being fasted and fed, respectively. In phase two and three, groups were swapped, and the experiment was repeated. At the end of the trial, each dog received the same treatment. Acetaminophen plasma concentrations were detected using a validated HPLC‐UV method. The pharmacokinetic analysis was performed using a noncompartmental model. Clearance, volume at steady state and half‐life of acetaminophen in Labrador Retrievers were 0.42 L/kg hr, 0.87 L/kg and 1.35 hr, respectively. No significant statistical differences were found between fasted and fed dogs regarding maximum plasma concentration, time at maximum concentration and bioavailability as measured by the AUC. Feeding does not significantly affect the acetaminophen oral pharmacokinetics. 相似文献
58.
The carbonyl-amine reaction between pyruvic acid and alpha-amino alcohols was monitored by Fourier transform infrared spectroscopy at a temperature range between 20 and 100 degrees C and under acidic and basic conditions. To avoid interference, the reactions were conducted in the absence of solvent using liquid reactants such as methyl pyruvate, pyruvic acid, ethanolamine, and 1-amino-2,3-propanediol. Analysis of the time- and temperature-dependent spectra indicated that under basic conditions and at room temperature, the initial imine formation and its subsequent isomerization through a 1,3-prototropic shift occur very rapidly and the reaction goes to completion within 12 min. Interestingly, the isomerization product of the initial imine is the so-called Schiff base intermediate formed when the corresponding amino acid and the reducing sugar react during a typical Maillard reaction. Furthermore, the detailed studies also indicated that during the first 30 s, the rate of formation of the initial imine was faster than the rate of its isomerization; however, after 60 s, its rate of isomerization becomes faster than the rate of its formation. The data also indicated that under acidic conditions, this isomerization was prevented from occurring and the reaction was terminated at the initial imine formation stage. In addition, temperature-dependent spectra indicated that the isomerization of the Schiff's base into eneaminol can be achieved at or above 60 degrees C and its subsequent rearrangement into Amadori product can be attained at temperatures above 80 degrees C even under basic conditions, thus providing a novel route to Maillard reaction products starting from a keto acid and an amino alcohol. This observation was also confirmed through identification of the common Amadori product in both keto acid/amino alcohol and sugar/amino acid mixtures, by the application of tandem mass spectrometry and chemical ionization techniques. 相似文献
59.
New self-incompatibility alleles in apricot (Prunus armeniaca L.) revealed by stylar ribonuclease assay and S-PCR analysis 总被引:1,自引:0,他引:1
Júlia Halász Attila Hegedüs Rita Hermán Éva Stefanovits-Bányai Andrzej Pedryc 《Euphytica》2005,145(1-2):57-66
Apricot (Prunus armeniaca L.) shows gametophytic self-incompatibility controlled by a single locus with several allelic variants. An allele for self-compatibility
(SC) and seven alleles for self-incompatibility (S1–S7) were described previously. Our experiments were carried out to ascertain whether the number of allelic variants of apricot
S-locus was indeed so small. Twenty-seven apricot accessions were analysed for stylar ribonucleases by non-equilibrium pH gradient
electrofocusing (NEpHGE) to determine their S-genotype. To validate the results of electrofocusing, the applicability of the S-gene-specific consensus PCR primers designed from sweet cherry sequences was tested. NEpHGE revealed 12 bands associated
with distinct S-alleles in newly genotyped cultivars. Cherry consensus primers amplified 11 alleles out from 16 ones, which indicated that
these primers could also recognize most of the S-RNase sequences in apricot, and provided an efficient tool to confirm or reject NEpHGE results. By combining the protein
and DNA-based methods, complete or partial S-genotyping was achieved for 23 apricot accessions and nine putatively new alleles (provisionally labelled S8–S16) were found. Their identity needs to be confirmed by pollination tests or S-allele sequencing. This study provides evidence that similarly to other Prunus species, the S-locus of apricot is more variable than previously believed. 相似文献
60.
Andrzej K Siwicki Zdzisaw Zak John C Fuller Jr Steven Nissen Sylwia Trapkowska Edward Gbski Krzysztof Kazu Agata Kowalska & Elbieta Terech-Majewska 《Aquaculture Research》2005,36(1):16-21
The present study examined the influence of leucine metabolite β‐hydroxy‐β‐methylbutyrate (HMB), a natural product HMB, on nonspecific cell‐mediated defence mechanisms and protection against enteric redmouth disease (ERM) in pikeperch (Sander lucioperca). β‐hydroxy‐β‐methylbutyrate was fed in a pelletted ration at 50 mg kg?1 of the feed for 8 weeks. The phagocytic ability and potential killing activity of blood and pronephric phagocytes were examined in HMB‐ and control‐fed fish before and after 8 weeks of feeding HMB. Simultaneously, the proliferative response of blood and pronephric lymphocytes stimulated by mitogens concanavaline A and lipopolisaccharide were examined in experimental and control groups. Following 8 weeks of HMB feeding, a challenge test was performed by injecting the fish with live pathogenic bacteria Yersinia ruckeri. β‐hydroxy‐β‐methylbutyrate applied in the diet for 8 weeks prompted a statistically significant (P<0.05) increase in phagocytic ability and potential killing activity of the blood and pronephric phagocytes and the proliferative response of blood and pronephric lymphocytes. The changes in these mechanisms correlated with protection against Y. ruckeri, the ERM pathogen. The results showed that feeding HMB increased the nonspecific cell‐mediated defence mechanisms and protection against ERM by reducing cumulative mortality (30%) following the challenge with pathogenic bacteria. Future studies will include determination of optimal doses and protocols of oral application of HMB to maximize the immunomodulatory effects and protection against viral diseases in intensive pikeperch culture. 相似文献