Salicylic acid mitigates salinity stress by improving antioxidant defence system and enhances vincristine and vinblastine alkaloids production in periwinkle [<Emphasis Type="Italic">Catharanthus roseus</Emphasis> (L.) G. Don]

A pot experiment was conducted to find out whether the foliar spray of salicylic acid (SA) could successfully ameliorate the adverse effects of salinity stress on periwinkle. Thirty-day-old plants were supplied with Control; 0 mM NaCl + 10⁻⁵ M SA (T₁); 50 mM NaCl + 0 SA (T₂); 100 mM NaCl + 0 SA (T₃); 150 mM NaCl + 0 SA (T₄); 50 mM NaCl + 10⁻⁵ M SA (T₅); 100 mM NaCl + 10⁻⁵ M SA (T₆); 150 mM NaCl + 10⁻⁵ M SA (T₇). The plants were sampled 90 days after sowing to assess the effect of SA on stressed and unstressed plants. Salt stress significantly reduced the growth attributes including plant height, leaf-area index, shoot and root fresh weights, shoot and root dry weights. Increasing NaCl concentrations led to a gradual decrease in photosynthetic parameters and activities of nitrate reductase and carbonic anhydrase. Ascorbic acid, total alkaloids and antioxidants enzymes superoxide dismutase, catalase and peroxidase also declined in NaCl-treated plants. The plants, undergoing NaCl stress, exhibited a significant increase in electrolyte leakage and proline content. Foliar application of SA (10⁻⁵ M) reduced the damaging effect of salinity on plant growth and accelerated the restoration of growth processes. It not only improved the growth parameters but also reversed the effects of salinity. Total alkaloid content was improved by SA application both in unstressed and stressed plants. The highest level of total alkaloid content recorded in leaves of SA-treated stressed plants was 11.1%. Foliar spray of SA overcame the adverse effect of salinity by improving the content of vincristine (14.0%) and vinblastine (14.6%) in plants treated with 100 M NaCl.     

Effects of glucose and phenol on soluble microbial products (SMP) in sequencing batch reactor systems

Soluble microbial products (SMP) are ubiquitously present in the effluents of biological wastewater treatment systems. In sequencing batch reactor (SBR) systems, effects of influent concentration and temperature on the amount and the molecular weight (MW) distribution of SMP were investigated for the two substrates, glucose and phenol. The values of effluent SMP/S₀ of phenol were higher than those of glucose at different influent concentrations and temperatures. It was found that the effluent SMP (S_e) was linearly correlated to the influent total organic carbon (TOC) (S₀) for both substrates. The slope and intercept of the equation were affected by the temperature. According to the analysis of the MW distribution, it was shown that there exists a bimodal pattern with the majority of SMP having a MW<1 kDa or >10 kDa. The low MW fraction (<1 kDa) amounts to 47.3–70.4% of the effluent SMP. The high MW fraction (>10 kDa) slightly fluctuates in the range of 21.2–32.8% of the effluent SMP.     

Exemestane Loaded Self-Microemulsifying Drug Delivery System (SMEDDS): Development and Optimization

The purpose of this research work was to formulate and characterize self-micro emulsifying drug delivery system containing exemestane. The solubility of exemestane was determined in various vehicles. Pseudo ternary phase diagram was used to evaluate the micro-emulsification existence area. SMEDDS formulations were tested for micro-emulsifying properties, and the resultant formulations loaded with exemestane (ME1, ME2, ME3, ME4 and ME5) were investigated for clarity, phase separation, globule size and shape, zeta potential, effect of various diluents and dilutions, thermodynamic and thermal stability. From the results it is concluded that increase in droplet size is proportional to the concentration of oil in SMEDDS formulation. Minor difference in the droplet size and zeta potential was observed by varying the diluents (deionized water and 0.1 N HCl) and dilutions (1:10, 1:50 and 1:100). Formulations, which were found to be thermodynamically stable (ME1, ME2, ME3 and ME4), were subjected to stability studies as per International Conference on Harmonization (ICH) guidelines. No significant variations were observed in the formulations over a period of 3 months at accelerated and long-term conditions. TEM photographs of microemulsions formulations further conformed the spherical shape of globules. Among the various SMEDDS formulations, ME4 offer the advantages of good clarity systems at high oil content and thus offer good solubilization of exemestane. Thus this study indicates that the SMEDDS can be used as a potential drug carrier for dissolution enhancement of exemestane and other lipophilic drug(s).     

Intranasal Microemulsion of Sildenafil Citrate: In Vitro Evaluation and In Vivo Pharmacokinetic Study in Rabbits

The purpose of the present study was to prepare intranasal delivery system of sildenafil citrate and estimate its relative bioavailability after nasal administration in rabbits to attain rapid onset of action with good efficacy at lower doses. Sildenafil citrate saturated solubility was determined in different solvents, cosolvents, and microemulsion systems. For nasal application, sildenafil citrate was formulated in two different systems: the first was a cosolvent system (S3) of benzyl alcohol/ethanol/water/Transcutol/taurodeoxy cholate/Tween 20 (0.5:16.8:47.7:15.9:1:18.1% w/w). The second was a microemulsion system (ME6) containing Oleic acid: Labrasol/Transcutol/water (8.33:33.3:16.66:41.66% w/w). The prepared systems were characterized in relation to their clarity, particle size, viscosity, pH, and nasal ciliotoxicity. In vivo pharmacokinetic performance of the selected system ME6 (with no nasal ciliotoxicity) was evaluated in a group of six rabbits in a randomized crossover study and compared to the marketed oral tablets. The targeted solubility (>20 mg/ml) of sildenafil citrate was achieved with cosolvent systems S1, S3, and S5 and with microemulsion systems ME3–ME6. The saturated solubility of sildenafil citrate in cosolvent system S3 and microemulsion system ME6 were 22.98 ± 1.26 and 23.79 ± 1.16 mg/ml, respectively. Microemulsion formulation ME6 showed shorter t _max (0.75 h) and higher AUC_(0-∞) (1,412.42 ng h/ml) compared to the oral tablets which showed t _max equals 1.25 h and AUC_(0-∞) of 1,251.14 ng h/ml after administration to rabbits at dose level of 5 mg/kg. The relative bioavailability was 112.89%. In conclusion, the nasal absorption of sildenafil citrate microemulsion was found to be fast, indicating the potential of nasal delivery instead of the conventional oral administration of such drug.     

闽江口互花米草淤积作用对其自身和短叶茳芏残体分解及硫养分释放的影响

2016—2017年,以闽江口鳝鱼滩西北部互花米草(SA)入侵初期与短叶茳芏(CM)形成的典型交错带植物残体为研究对象,基于野外原位分解试验,通过设定无淤积强度(S_0,0 cm/a)、当前淤积强度(S_5,5 cm/a)和未来淤积增强(S_(10),10 cm/a)3种处理,模拟互花米草入侵初期导致的淤积作用对其自身以及短叶茳芏残体分解及硫养分释放的影响。结果表明,随着互花米草入侵导致的淤积强度的增加,互花米草和短叶茳芏残体的分解速率均明显降低;与S_0相比,二者在S_5与S_(10)处理下的分解速率分别降低49.09%(SA)、35.14%(CM)和56.36%(SA)、44.59%(CM)。随着淤积强度的增加,互花米草和短叶茳芏残体分解过程中的TS含量整体均呈增加趋势,且其对短叶茳芏TS含量变化的影响较为明显;互花米草和短叶茳芏残体在分解过程中均表现为不同程度的硫释放,但随淤积强度的增加,二者硫释放量均呈降低趋势,且在相同淤积强度下,前者的硫释放量要高于后者。不同淤积强度下残体分解速率及硫养分释放强度的差异不仅与分解环境中的EC密切相关,且与残体残留率、初始基质质量(C/N和C/S)以及淤积导致养分条件改变而对分解过程中残体基质质量的影响有关。研究发现,随着淤积强度的增加,两种残体的分解速率及硫释放强度均降低;但在相同淤积强度下,短叶茳芏残体的分解速率和硫释放量均大于互花米草。     

Seasonal variations in colonization dynamics of periphytic protozoa in coastal waters of the Yellow Sea,northern China

The colonization features of periphytic protozoa have proved to be a useful tool for indicating water quality status in aquatic ecosystems. In order to reveal the seasonal variations in colonization dynamics of the protozoa, a 1-year baseline survey was carried out in coastal waters of the Yellow Sea, northern China. Using glass slides as artificial substrates, a total of 240 slides were collected at a depth of 1 m in four seasons after colonization periods of 3, 7, 10, 14, 21, and 28 days. A total of 122 ciliate species were identified with 21 dominant species. The colonization dynamics of the protozoa were well fitted to the MacArthur-Wilson and logistic models in all four seasons (P < 0.05). However, the equilibrium species numbers (S_eq), colonization rates (G), and the time to 90% S_eq (T_90%) represented a clear seasonal variability: (1) more or less similar levels in spring and autumn (S_eq = 29/23; G = 0.301/0.296; T_90%=7.650/7.779); (2) with a significant difference in summer and winter (S_eq = 32/121; G = 0.708/0.005; T_90% = 3.252/479.705). Multivariate approaches demonstrated that the exposure time for the species composition and community structure of the protozoa to an equilibrium period were 10–14 days in spring and autumn, but less and more time periods were needed in summer and winter, respectively. Based on the results, we suggest that the colonization dynamics of periphytic protozoa were different within four seasons, and an optimal sampling strategy for monitoring surveys should be modified during different seasons in marine ecosystems.     

Kinetics of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> var. <Emphasis Type="Italic">israelensis</Emphasis> growth on high glucose concentrations

The kinetic and general growth features of Bacillus thuringiensis var. israelensis were evaluated. Initial glucose concentration (S ₀) in fermentation media varied from 10 to 152 g/l. The results afforded to characterize four morphologically and physiologically well-defined culture phases, independent of S ₀ values: Phase I, vegetative growth; Phase II, transition to sporulation; Phase III, sporulation; and Phase IV, spores maturation and cell lysis. Important process parameters were also determined. The maximum specific growth rates (μ _X,m) were not affected with S ₀ up to 75 g/l (1.0–1.1 per hour), but higher glucose concentrations resulted in growth inhibition by substrate, revealed by a reduction in μ _X,m values. These higher S ₀ values led to longer Phases III and IV and delayed sporulation. Similar biomass concentrations (X _m = 15.2–15.9 g/l) were achieved with S ₀ over 30.8 g/l, with increasing residual substrate, suggesting a limitation in some other nutrients and the use of glucose to form other metabolites. In this case, with S ₀ from 30.8 to 152 g/l, cell yield (Y _X/S ) decreased from 0.58 to 0.41 g/g. On the other hand, with S ₀ = 10 g/l growth was limited by substrate, and Y _X/S has shown its maximum value (0.83 g/g).     

Studies on the Effect of Water-Soluble Polymers on Drug–Cyclodextrin Complex Solubility

The effect of complexation of irbesartan (IRB), a practically water-insoluble drug, with cyclodextrins in presence of different concentrations of water-soluble polymers (PEG 4000 and PVP K-90) on the dissolution rate of the drug has been investigated. Phase solubility studies were carried out to evaluate the solubilizing power of βCD in association with water-soluble polymers towards IRB and to determine the apparent stability constant (K _S) of the complexes. Improvement in K _S value for ternary complexes (IRB–βCD–polymers) clearly proved the benefit on the addition of water-soluble polymer to increase complexation efficiency. The dissolution rate of the drug from ternary systems containing PEG 4000 and PVP K-90 was higher as compared to the binary system. An optimum increase in the dissolution rate of the drug was observed at a polymer concentration of 5% w/w for PVP K-90 and 10% w/w for PEG 4000. DSC, FTIR, SEM, and XRD studies were carried out to characterize the complexes.     

Gas hold-up and oxygen mass transfer in three pneumatic bioreactors operating with sugarcane bagasse suspensions

Sugarcane bagasse is a low-cost and abundant by-product generated by the bioethanol industry, and is a potential substrate for cellulolytic enzyme production. The aim of this work was to evaluate the effects of air flow rate (Q _AIR), solids loading (%_S), sugarcane bagasse type, and particle size on the gas hold-up (ε _G) and volumetric oxygen transfer coefficient (k _L a) in three different pneumatic bioreactors, using response surface methodology. Concentric tube airlift (CTA), split-cylinder airlift (SCA), and bubble column (BC) bioreactor types were tested. Q _AIR and  %_S affected oxygen mass transfer positively and negatively, respectively, while sugarcane bagasse type and particle size (within the range studied) did not influence k _L a. Using large particles of untreated sugarcane bagasse, the loop-type bioreactors (CTA and SCA) exhibited higher mass transfer, compared to the BC reactor. At higher  %_S, SCA presented a higher k _L a value (0.0448 s^?1) than CTA, and the best operational conditions in terms of oxygen mass transfer were achieved for  %_S < 10.0 g L^?1 and Q _AIR > 27.0 L min^?1. These results demonstrated that pneumatic bioreactors can provide elevated oxygen transfer in the presence of vegetal biomass, making them an excellent option for use in three-phase systems for cellulolytic enzyme production by filamentous fungi.     

Local control rates in stereotactic body radiotherapy (SBRT) of lung metastases associated with the biologically effective dose

AimTo evaluate dose differences in lung metastases treated with stereotactic body radiotherapy (SBRT), and the correlation with local control, regarding the dose algorithm, target volume and tissue density.BackgroundSeveral studies showed excellent local control rates in SBRT for lung metastases, with different fractionation schemes depending on the tumour location or size. These results depend on the dose distributions received by the lesions in terms of the tissue heterogeneity corrections performed by the dose algorithms.Materials and methodsForty-seven lung metastases treated with SBRT, using intrafraction control and respiratory gating with internal fiducial markers as surrogates (ExacTrac, BrainLAB AG), were calculated using Pencil Beam (PB) and Monte Carlo (MC) (iPlan, BrainLAB AG).Dose differences between both algorithms were obtained for the dose received by 99% (D_99%) and 50% (D_50%) of the planning treatment volume (PTV). The biologically effective dose delivered to 99% (BED_99%) and 50% (BED_50%) of the PTV were estimated from the MC results. Local control was evaluated after 24 months of median follow-up (range: 3–52 months).ResultsThe greatest variations (40.0% in ΔD_99% and 38.4% in ΔD_50%) were found for the lower volume and density cases. The BED_99% and BED_50% were strongly correlated with observed local control rates: 100% and 61.5% for BED_99% > 85 Gy and <85 Gy (p < 0.0001), respectively, and 100% and 58.3% for BED_50% > 100 Gy and <100 Gy (p < 0.0001), respectively.ConclusionsLung metastases treated with SBRT, with delivered BED_99% > 85 Gy and BED_50% > 100 Gy, present better local control rates than those treated with lower BED values (p = 0.001).     

Effect of progesterone concentrations,follicle diameter,timing of artificial insemination,and ovulatory stimulus on pregnancy rate to synchronized artificial insemination in postpubertal Nellore heifers

Two experiments were designed to evaluate the effects of treatments with low versus high serum progesterone (P₄) concentrations on factors associated with pregnancy success in postpubertal Nellore heifers submitted to either conventional or fixed timed artificial insemination (FTAI). Heifers were synchronized with a new controlled internal drug release device (CIDR; 1.9 g of P₄ [CIDR1]) or a CIDR previously used for 18 days (CIDR3) plus 2 mg of estradiol (E₂) benzoate on Day 0 and 12.5 mg of prostaglandin F2α on Day 7. In experiment 1 (n = 723), CIDR were removed on Day 7 or 9 and heifers were inseminated after estrus detection. In experiment 2 (n = 1083), CIDR were all removed on Day 9 and FTAI was performed either 48 hours later in heifers that received E₂ cypionate (ECP) on Day 9 (0.5 mg; E48) or 54 or 72 hours later in conjunction with administration of GnRH (100 μg; G54 or G72). Synchronization with CIDR1 resulted in greater serum P₄ concentrations and smaller follicle diameters on Days 7 and 9 in both experiments. In experiment 1, treatment with CIDR for 9 days decreased the interval from CIDR removal to estrus (Day 7, 3.76 ± 0.08 days vs. Day 9, 2.90 ± 0.07; P < 0.01) and improved conception (Day 7, 57.1% vs. Day 9, 65.8%; P = 0.05) and pregnancy rates (Day 7, 37.6% vs. Day 9, 45.3%; P = 0.04). In experiment 2, treatment with ECP improved (P < 0.01) the proportion of heifers in estrus (E48, 40.9%^a; G54, 17.1%^c; and G72, 32.0%^b), but the pregnancy rate was not affected (P = 0.64) by treatments (E48, 38.8%; G54, 35.5%; G72, 37.5%). Synchronization with CIDR3 increased follicle diameter at FTAI (CIDR1, 11.07 ± 0.10 vs. CIDR3, 11.61 ± 0.10 mm; P < 0.01), ovulation rate (CIDR1, 82.8% vs. CIDR3, 88.0%; P < 0.01) and did not affect conception (CIDR1, 42.2 vs. CIDR3, 45.1%; P = 0.38) or pregnancy rates (CIDR1, 34.7 vs. CIDR3, 39.4%; P = 0.11). In conclusion, length of treatment with P₄ affected the fertility of heifers bred based on estrus detection. When the heifers were submitted to FTAI protocol, follicle diameter at FTAI (≤10.7 mm, 23.6%; 10.8–15.7 mm, 51.5%; ≥15.8 mm, 30.0%; P < 0.01) was the main factor that affected conception and pregnancy rates.     

Determination of acetylsalicylic acid and salicylic acid in skin and plasma by high-performance liquid chromatography

This study describes a HPLC method to determine the concentrations of acetylsalicylic acid (ASA) and salicylic acid (SA) in human stratum corneum and in plasma. The stratum corneum layers for ASA/SA analysis were removed from three patients with postherpetic hyperalgesia treated with topical and oral aspirin. Blood samples were also collected from the same patients. Tape strippings were placed in acetonitrile and sonicated for 15 min. After centrifuging, aliquots of the supernatant were injected into the chromatograph. ASA and SA from plasma samples were extracted on Isolute C₈ columns. Due to interfering peaks in the tape samples, HPLC conditions were slightly different for tape and plasma samples. ASA and SA were separated on a LiChrospher 100 RP-18 column at 1 ml/min using a water–phosphate buffer (pH 2.5)–acetonitrile mobile phase (35:40:25, v/v/v). A linear response to quantities of ASA from 0.1 to 100 μg/cm² and of SA from 0.1 to 5 μg/cm² in tape and to quantities of ASA 0.1 to 2 μg/ml and 1 to 50 μg/ml was obtained and the recovery from tape and plasma samples was over 98%. The method is sensitive (0.1 μg/cm²) and specific enough to allow the determination of the drugs in the skin not only after topical but also after oral administration. A good sensitivity was also obtained in plasma (0.1 μg/ml) allowing study of the kinetics of ASA and SA in plasma after oral administration. Concentrations of ASA after topical administration were 100–200 times higher than after oral administration. Plasma levels of ASA and SA after oral administration were similar to those previously found. No ASA or SA were detected in plasma after topical ASA administration.     

Development and fine mapping of three co-dominant SCAR markers linked to the <Emphasis Type="Italic">M/m</Emphasis> gene in the cucumber plant (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.)

Owing to its diverse sex types, the cucumber plant has been studied widely as a model for sex determination. In addition to environmental factors and plant hormones, three major genes—F/f, M/m, and A/a—regulate the sex types in the cucumber plant. By combining the bulked segregant analysis (BSA) and the sequence-related amplified polymorphism (SRAP) technology, we identified eight markers linking to the M/m locus. Among them, the two closely linked SRAP markers flanking the M/m locus were the co-dominant marker ME1EM26 and the dominant marker ME1EM23. Further, the co-dominant marker ME8SA7 co-segregated with the M/m locus. With the chromosome walking method using the cucumber genomic bacterial artificial chromosome (BAC) library, we successfully developed a co-dominant SCAR marker S_ME1EM23 from the ME1EM23 sequence. Along with the other two co-dominant SCAR markers S_ME1EM26 and S_ME8SA7 (developed from ME1EM26 and ME8SA7, respectively) in a larger segregating population (900 individuals), the M/m locus was mapped between S_ME1EM26 (5.4 cM) and S_ME1EM23 (0.7 cM), and S_ME8SA7 co-segregated with it. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Z. Li and J. Pan contribute equally to this article.     

Microemulsion for topical delivery of fenoprofen calcium: in vitro and in vivo evaluation

The aim of this study was to investigate microemulsion (ME) based topical delivery system for fenoprofen calcium (FPCa) to eliminate its oral gastrointestinal adverse effects. ME was prepared by the water titration method using oleic acid as oil phase, tween 80 as a surfactant and propylene glycol as a cosurfactant. Oleic acid was selected as oil phase due to its good solubilizing capacity. ME existence region was determined using pseudo-ternary phase diagrams for preparing different formulations. Six different formulations were selected with various values of oil (25–68%), water (2–3%), and the mixture of surfactant and cosurfactant (1:1) (24–67%). The selected ME formulae were characterized for optical birefringence, transmission electron microscopy (TEM), pH, % transmittance, electronic conductivity, drug content, droplet size, rheological properties and stability evaluation. In vitro release study of FPCa from ME s through the synthetic membrane and hairless rat skin were evaluated. The optimized formula ME5 consisting of 5% w/w FPCa, 60% w/w oleic acid as oil phase, 3% w/w aqueous phase, and 32% w/w of surfactant phase containing Tween 80 and propylene glycol (1:?1) showed the highest transdermal flux and highest skin permeation rate. Finally, the % inhibition of carrageenan-induced rat paw edema of the optimized formula ME5 was highly significant (p?0.001) as compared to plain gel of FPCa. In conclusion, ME is a promising technique for topical delivery of FPCa.     

Development and antifungal evaluation of a food-grade U-type microemulsion

Aims: Food-grade microemulsions have been of increasing interest to researchers as potential delivery systems for bioactive compounds. However, food-grade microemulsions are difficult to formulate and no microemulsion has been documented for antifungal purpose. The physicochemical characterization of a food-grade glycerol monolaurate (GML)/ethanol (EtOH)/Tween 80/potassium sorbate (PS)/water microemulsion system and the antifungal activities against Aspergillus niger and Penicillium italicum have been studied in this paper. Methods and Results: The influence of EtOH and PS on oil solubilization capability was clearly reflected in the phase behaviour of U-type microemulsion systems. One dilution-stable formulation ME (GML/EtOH/Tween 80/PS/water = 3 : 3 : 3·5 : 10·5 : 16) was selected. After 4 days of incubation, ME showed 80%A. niger growth inhibition at 0·2% and 72%P. italicum growth inhibition at 0·1%, respectively, and a delay of conidiation of 2 days compared with the control. In the antifungal activities of the microemulsion, GML and PS made major contributions with similar antifungal activities at a GML/PS weight ratio of 1: 3·5. Conclusions: Food-grade dilution-stable microemulsions prepared with GML as oil phase for antifungal purpose are feasible and solubilization of a hydrotrope contributes to the formation of microemulsions and enhanced antifungal activities. Significance and Impact of the Study: The present report represents the first to develop a food-grade microemulsion system for antifugal purpose.     

Measurement of stretch-induced loss of alveolar epithelial barrier integrity with a novel in vitro method

Mechanical ventilation with hightidal volumes has been shown to contribute to the formation orworsening of interstitial and alveolar edema. Previously we showed thatapplication of large biaxial deformations in vitro perturbs theconcentration and distribution of functional tight junction proteins inalveolar epithelial cells. Using a novel method, we determined thatapplied epithelial strain increases paracellular permeability in adose- and rate-dependent manner. Primary rat alveolar epithelial cellswere subjected to 12%, 25%, or 37% change in surface area (SA)cyclic equibiaxial stretch for 1 h. Cells were also stretchednoncyclically at 25% SA for 1 h. During the experimentalperiod, a fluorescently tagged ouabain derivative was added to theapical fluid. Evidence of binding indicated functional failure of theparacellular transport barrier. The percentage of field area stainedwas quantified from microscopic images. There was no significantevidence of basolateral fluorescent staining at 12% SA or at 25%SA applied cyclically or statically. However, cyclic stretch at 37%SA resulted in significantly more staining than in unstretched cells(P < 0.0001) or those stretched at either 12%(P < 0.0001) or 25% cyclic (P < 0.0005) or static (P < 0.05) SA. These resultssuggest that large cyclic tidal volumes may increase paracellularpermeability, potentially resulting in alveolar flooding.

     

Thermostability of haemoglobins from Antarctic fish

Summary Proteins from Antarctic fish are less stable at high temperatures than those from fish from lower latitudes. Investigations into the thermostability of haemoglobins from a range of Antarctic teleosts have been carried out for comparison with data from temperate species. Haemoglobin concentrations following periods of heating at 50°C were analysed spectrophotometrically and the time taken for 50% denaturation (t_50%) determined. The effects of pH and salt concentrations were also examined. With the exception of that of Rhigophila dearborni, the haemoglobins were found to be relatively unstable with t_50% values ranging from 7.7 to 29.9 min at pH 7. All haemoglobins became less stable on addition of KCl but the effect of pH was variable. Freezing had no effect on the stability of haemoglobin from Dissostichus mawsoni. The thermostability of haemoglobin from a temperate nototheniid, Notothenia angustata, was within the range displayed by its antarctic relatives and it would seem that in general the differences between genera are as great as those between Antarctic and temperate species as a whole.     

Stability of (1R,2S)-(-)-Ephedrine hydrochloride in Candida albicans-inoculated urine and blood samples

The stability of drugs in biological evidence during collection and storage is of particular concern in forensic investigations. Microbes in the samples and other elements are an essential component of these investigations. In the current study, the HPLC method was used to examine the stability of (1R, 2S)-(-)-Ephedrine hydrochloride in plasma and urine samples inoculated with C. albicans after storage at 37 °C for 48 h and −20 °C for six months. In the stability experiment, MIC_50% of (1R, 2S)-(-)-Ephedrine hydrochloride was applied according to MIC and MFC that were determined in this work. This drug had MIC and MFC of 50 and 100 ppm, respectively. In HPLC analysis, the standard (1R, 2S)-(-)-Ephedrine hydrochloride had a retention time of 1.63 and was used to identify this drug in samples that had or had not been exposed to C. albicans. The findings demonstrated that within 48 h at 37 °C, C. albicans had an impact on the drug concentration (10% and more than 15%, respectively, were lost in plasma and urine samples inoculated with C. albicans). In plasma samples, the drug content remained stable at −20 °C for three months, although it degraded in urine samples after one month. In plasma and urine samples, the concentration reduction had surpassed 70% and 50% by the sixth month, respectively. The results of this investigation show that C. albicans can change the stability of (1R, 2S)-(-)-Ephedrine hydrochloride in plasma and urine samples that contain MIC_50% of Ephedrine hydrochloride.     

Length–mass relationships for lake macroinvertebrates corrected for back-transformation and preservation effects

Coloured dissolved organic matter (CDOM) modifies the light penetration into water bodies due to stronger absorbance of UV and short wavelengths of light. Therefore, in natural waters with high CDOM concentration, the spectrum of sunlight is shifted towards brown, also referred to as brownification. Here, the relation between the spectrophotometrically measured water colour (CDOM) and landscape properties is examined. These properties explained at best > 40% of the CDOM variability among the study lakes larger than 10 km². The key “permanent” landscape variables were lake percentage (Lake_%) in the uppermost catchment area, and the peat land coverage (Peat_%) of the catchment, which indeed was strongly correlated with lake elevation above the sea level. High Lake % indicated low CDOM concentration, while high Peat_% indicated the opposite. Relative to the Peat_% of the catchment, the CDOM concentrations were, on average, slightly higher in medium-size lakes (area 10–100 km²) than in large lakes (area > 100 km²), while relative to Lake_% the concentrations declined more in medium-size lakes.     

Arterial hypoxemia and performance during intense exercise

In order to determine the level of hypoxemia which is sufficient to impair maximal performance, seven well-trained male cyclists [maximum oxygen consumption (VO_2max)51·min^–1 or 60 ml·kg^–1·min^–1] performed a 5-min performance cycle test to exhaustion at maximal intensity as controlled by the subject, under three experimental conditions: normoxemia [percentage of arterial oxyhemoglobin saturation (%S _a O₂)>94%], and artificially induced mild (%S _aO₂=90±1%) and moderate (%S _aO₂=87±1%) hypoxemia. Performance, evaluated as the total work output (Work_tot) performed in the 5-min cycle test, progressively decreased with decreasing %S _aO₂ [mean (SE) Work_tot=107.40 (4.5) kJ, 104.07 (5.6) kJ, and 102.52 (4.7) kJ, under normoxemia, mild, and moderate hypoxemia, respectively]. However, only performance in the moderate hypoxemia condition was significantly different than in normoxemia (P=0.02). Mean oxygen consumption and heart rate were similar in the three conditions (P=0.18 andP=0.95, respectively). End-tidal partial pressure of CO₂ was significantly lower (P=0.005) during moderate hypoxemia compared with normoxemia, and ventilatory equivalent of CO₂ was significantly higher (P=0.005) in both hypoxemic conditions when compared with normoxemia. It is concluded that maximal performance capacity is significantly impaired in highly trained cyclists working under an %S _aO₂ level of 87% but not under a milder desaturation level of 90%.