Endothelial dysfunction induced by triglycerides is not restored by exenatide in rat conduit arteries ex vivo

Exenatide (synthetic exendin-4) is a stable analogue of glucagon-like peptide 1 (GLP-1) and has recently been approved for clinical use against type 2 diabetes. Exenatide is believed to exert its effects via the GLP-1 receptor with almost the same potency as GLP-1 in terms of lowering blood glucose. Short term exenatide treatment normalizes the altered vascular tone in type 2 diabetic rats, probably due to the reduction in glycemia. The aim of this study was to investigate whether exenatide directly protects against triglyceride-induced endothelial dysfunction in rat femoral arterial rings ex vivo. Short term pre-incubation with Intralipid^® (0.5 and 2%) was found to dose-dependently induce endothelial dysfunction, in that it elicited a significant reduction in ACh-induced vasorelaxation by 29% and 35%, respectively. Paradoxically, this occurred with a concomitant increase in endothelial nitric oxide synthase (eNOS) activity. No such reduction in vasorelaxation by Intralipid^® was seen in response to the NO donor sodium nitroprusside (SNP), revealing an endothelium-dependent vascular dysfunction by Intralipid^®. However, exenatide did not protect against Intralipid^®-induced endothelial dysfunction. More surprisingly, the maximum vasorelaxation induced by exenatide (without Intralipid^®) was only 3 ± 2%, compared to the 23 ± 4%, 38 ± 4%, 79 ± 3% and 97 ± 4% relaxations induced by GLP-1, GLP-1 (9-36), ACh and SNP, respectively. This unexpected finding prompted us to ascertain that the exenatide preparation was biologically active, and both exenatide (10^− 11 mol/l) and GLP-1 (10^− 9 mol/l) significantly increased insulin secretion in pancreatic β-cells from ob/ob mice in vitro. In conclusion, exenatide could neither confer any acute protective effects against triglyceride-induced endothelial dysfunction nor exert any significant vasorelaxant actions in this model of rat conduit arteries ex vivo.     

Increased circulating IL-8 is associated with reduced IGF-1 and related to poor metabolic control in adolescents with type 1 diabetes mellitus

Background: A dysregulated growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis is well-recognized in children and adolescents with type 1 diabetes mellitus (T1DM). Decreased IGF-1 levels can also be found in chronic inflammatory diseases, while hyperglycemia promotes inflammatory cytokine production. Therefore, inflammatory cytokines may link poor metabolic control with GH/IGF-1 axis changes. This study examined the relationship between serum inflammatory cytokines and IGF-1 in adolescents (age 13–18) with TIDM in chronic poor (n = 17) or favorable (n = 19) glucose control. Poor control (PC) was defined as 3, consistent HbA1C > 9% during the previous 2 years, while favorable control (FC) was consistent levels of HbA1C < 9%. Results: HbA1C (FC: 7.5 ± 0.6%; PC: 10.5 ± 0.9%, p < 0.001) and interleukin (IL)-8 (FC: 3.7 ± 4.0 pg/ml; PC: 7.4 ± 4.3 pg/ml, p = 0.01) were increased and IGF-1 (FC: 536.5 ± 164.3 ng/ml; PC: 408.9 ± 157.1 ng/ml, p = 0.03) was decreased in patients with poor control compared to patients with favorable control. Moreover, IL-8 was inversely correlated with IGF-1 (r = −0.40, p = 0.03) and positively correlated with HbA1C (r = 0.36, p = 0.03). Conclusions: In adolescents with T1DM and chronic, poor glucose control, increased serum IL-8 is associated with reduced IGF-1 suggesting a pro-inflammatory milieu that may contribute to alterations in the GH/IGF-1 axis.     

A micro-potentiometric hemoglobin immunosensor based on electropolymerized polypyrrole–gold nanoparticles composite

We report a novel micro-potentiometric hemoglobin (Hb) immunosensor based on electrochemically synthesized polypyrrole (PPy)–gold nanoparticles (AuNPs) composite. PPy–AuNPs film with AuNPs uniformly distributed in it was deposited on gold electrode surface by a simple and direct procedure, without the addition of any nanoparticles or reducing agent. And this generic method makes it possible to deposite different polymers on miniaturized electrodes. With the existence of AuNPs, the antibody immobilization onto the electrode surface was facilitated. Morphology study by field emission scanning electron microscope (FE-SEM) confirms the presence of AuNPs in PPy. Based on an ion-sensitive field-effect transistors (ISFETs) integrated chip, a micro-potentiometric immunosensor for Hb and hemoglobin-A1c (HbA1c) has been constructed. The sensor response was linear over the concentration range 60–180 μg/ml Hb and 4–18 μg/ml HbA1c. The Hb concentration in whole blood samples has also been analysed, with a linear dose–response behavior between 125 and 197 μg/ml and a sensitivity of 0.20 mV μg⁻¹ ml. The measuring ranges of the developed Hb and HbA1c immunosensors meet the clinical demand for measuring the HbA1c/Hb ratio of 5–20%. This sensor results in simple and rapid differential measurement of Hb and HbA1c, and has great potential to become an inexpensive and portable device for monitoring of diabetes.     

Characterizing the freezing behavior of liposomes as a tool to understand the cryopreservation procedures

Freezing behaviors of egg yolk l-α-phosphatidylcholine (EPC) and 1,2-dipalmitoyl-rac-glycero-3-phosphocholine (DPPC) large unilamellar vesicles (LUV) were quantitatively characterized in relation to freezing temperatures, cooling rates, holding time, presence of sodium chloride and phospholipid phase transition temperature. Cooling of the EPC LUV showed an abrupt increase in leakage of the encapsulated carboxyfluorescein (CF) between −5 °C and −10 °C, which corresponded with the temperatures of the extraliposomal ice formation at around −7 °C. For the DPPC LUV, CF leakage started at −10 °C, close to the temperature of the extraliposomal ice formation; followed by a subsequent rapid increase in leakage between −10 °C and −25 °C. Scanning electron microscopy showed that both of these LUV were freeze-concentrated and aggregated at sub-freezing temperatures. We suggest that the formation of the extraliposomal ice and the decrease of the unfrozen fraction causes freeze-injury and leakage of the CF. The degree of leakage, however, differs between EPC LUV and DPPC LUV that inherently vary in their phospholipid phase transition temperatures. With increasing holding time, the EPC LUV were observed to have higher leakage when they were held at −15 °C compared to at −30 °C whilst leakage of the DPPC LUV was higher when holding at −40 °C than at −15 °C and −50 °C. At slow cooling rates, osmotic pressure across the bilayers may cause an additional stress to the EPC LUV. The present work elucidates freeze-injury mechanisms of the phospholipid bilayers through the liposomal model membranes.     

Renewal time and the impact of harmful algal blooms on the extensive mussel raft culture of the Iberian coastal upwelling system (SW Europe)

The extension and intensity of the upwelling season in the NW Iberian Peninsula (42°N–43°N) have decreased by 30 and 45% over the last 40 years, respectively. Accordingly, the renewal time (τ) of the Rías Baixas, four large coastal inlets where 15% of the World extraction of blue mussels occurs, has increased by 240%. We indirectly demonstrate here that the growing τ has caused the increasing occurrence of harmful microalgae in these embayments, dramatically affecting mussel raft cultivation. The equation D = 365(1 − exp(−τ/c₁)) explains 80% of the variability of the number of days per year that mussels cannot be extracted from the hanging ropes because of the occurrence of harmful microalgae (D). The coefficient c₁ = 37 ± 2 days indicates that an average τ over the upwelling season of >25 ± 1 or 50 ± 3 days reduce mussel extraction to only 50 or 25% of the year, respectively.     

A study of the distribution of chitosan onto and within a paper sheet using a fluorescent chitosan derivative

Acidic glutaraldehyde (Gh) crosslinked chitosan (ChGhH) when deprotonated the biopolymer (ChGh) presents high content of free amino groups. These modified biopolymers are comparable to epichlorohydrin (Ep) crosslinked (ChEp). C/N molar ratio of 6.1 for chitosan increases to 7.3, 7.5 and 7.1 for ChGhH, ChGh and ChEp. The effectiveness of the carbon-6 hydroxyl group in interconnecting chitosan units was supported by IR and ¹³CNMR, where Ep promotes increase in crystallinity. Copper uptake gave the order Ch > ChGh > ChGhH > ChEp, as: 1.35 ± 0.06, 1.30 ± 0.05, 1.05 ± 0.07 and 0.96 ± 0.22 mmol g⁻¹, reflecting the availability of nitrogen basic centers in adsorbing. The favorable thermodynamic data of adsorption through calorimetric titration gave exothermic enthalpic values: −28.98 ± 0.05, −6.68 ± 0.04, −6.13 ± 0.07 and −0.65 ± 0.23 kJ mol⁻¹ for Ch, ChGh, ChGhH and ChEp. Free Gibbs energy reflected spontaneity of interactions and, with the exception of chitosan, the entropic values are positive.     

Ethylenesulfide as a useful agent for incorporation into the biopolymer chitosan in a solvent-free reaction for use in cation removal

Chitosan (Ch) was chemically modified with ethylenesulfide (Es) under solvent-free conditions to give (ChEs), displaying a high content of thiol groups due to opening of the three member cyclic reagent. Elemental analysis showed a decrease in nitrogen content. This result indicated the incorporation of two ethylenesulfide molecules for each unit of the polymeric structure of the precursor biopolymer. Infrared spectroscopy, thermogravimetry, and ¹³C NMR in the solid state demonstrated the effectiveness of the reaction, with signals at 30 ppm for ChEs due to the change in the methylene group environment. Divalent metal uptake by chemically modified biopolymer gave the order Cu > Ni > Co > Zn, reflecting the corresponding acidity of these cations in bonding to the sulfur and the basic nitrogen atoms available on the pendant chains. The equilibrium data were fitted to Freundlich, Temkin, and Langmuir models. The maximum monolayer adsorption capacity for the cations was found to be 1.54 ± 0.02, 1.25 ± 0.03, 1.13 ± 0.01, and 0.83 ± 0.03 mmol g⁻¹, respectively. The Langmuir model best explained the cation–sulfur bond interactions at the solid–liquid interface. The thermodynamics for these interactions gave exothermic enthalpic values of −43.02 ± 0.03, −28.72 ± 0.02, −26.27 ± 0.04, and −17.32 ± 0.02 kJ mol⁻¹, respectively. The spontaneity of the systems is given by negative Gibbs free energies of −31.2 ± 0.1, −32.7 ± 0.1, −31.7 ± 0.1, and −32.2 ± 0.1 kJ mol⁻¹, respectively, in spite of the unfavorable negative entropic values of −39 ± 1, −13 ± 1, −18 ± 1, and −49 ± 1 J K⁻¹ mol⁻¹ due to solvent ordering in the course of complexation. This newly synthesized biopolymer is presented as a chemically useful material for cation removal from aqueous solution.     

Differences in cold and drought tolerance of high arctic and sub-arctic populations of Megaphorura arctica Tullberg 1876 (Onychiuridae: Collembola)

The springtail Megaphorura arctica (Onychiuridae: Collembola) inhabits the arctic and sub-arctic parts of the northern hemisphere where it on a seasonal basis will be exposed to severe cold and desiccating conditions. In the present study we compared how traits of stress resistance differed between two populations of M. arctica that were collected at a high arctic site (Spitsbergen) and a sub-arctic site (Akureyri, Iceland) with contrasting thermal environments. In addition we investigated how cold and desiccation affected the phospholipid fatty acid composition of M. arctica from Spitsbergen. The springtails from Spitsbergen were the most cold tolerant and this was linked to an almost three times higher level of trehalose accumulation during cryoprotective dehydration (15% and 5% of tissue dry weight in the Spitsbergen and Iceland populations, respectively). Although cryoprotective dehydration is intimately related to desiccation stress it was shown that M. arctica had a higher mortality when dehydrated over ice (−10 or −20 °C) than when dehydrated at temperatures above 1 °C. Thus, survival was lower after exposure to −10 °C than after exposure to a relative humidity of 91.2% RH at +1 °C although both treatments led to the same level of dehydration. Exposure to both cold (−10 and −20 °C) and desiccation at +1 °C caused significant changes in the phospholipid fatty acid composition with some similarities. These changes included a decrease in average chain length of the fatty acids due primarily to an increase in the phospholipid fatty acids 16:0 and a decrease in 18:3 and 20:4ω6.     

Physiological acclimation to light in Chara intermedia nodes

In this study we investigated the ability of Chara intermedia to acclimate to different irradiances (i.e. “low-light” (LL): 20–30 μmol photons m⁻² s⁻¹ and “high-light” (HL): 180–200 μmol photons m⁻² s⁻¹) and light qualities (white, yellow and green), using morphological, photosynthesis, chlorophyll fluorescence and pigment analysis.Relative growth rates increased with increasing irradiance from 0.016 ± 0.003 (LL) to 0.024 ± 0.005 (HL) g g⁻¹ d⁻¹ fresh weight and were independent of light quality. A growth-based branch orientation towards high-light functioning as a mechanism to protect the plant from excessive light was confirmed. It was shown that the receptor responsible for the morphological reaction is sensitive to blue-light.C. intermedia showed higher oxygen evolution (up to 10.5 (HL) vs. 4.5 (LL) nmol O₂ mg Chl⁻¹ s⁻¹), photochemical and energy-dependent Chl fluorescence quenching and a lower Fv/Fm after acclimation to HL. With respect to qP, the acclimation of the photosynthetic apparatus depended on light quality and needed the blue part of the spectrum for full development. In addition, pigment composition was influenced by light and the Chl a/Car and Antheraxanthin (A) + Zeaxanthin (Z)/Violaxanthin (V) + A + Z (DES) ratios revealed the expected acclimation behaviour in favour of carotenoid protection under HL (i.e. decrease of Chl a/Car from 3.41 ± 0.48 to 2.30 ± 0.35 and increase of DES from 0.39 ± 0.05 to 0.87 ± 0.03), while the Chl a/Chl b ratios were not significantly affected. Furthermore it was shown that morphological light acclimation mechanisms influence the extent of the physiological modifications.     

Formation of extracellular and intracellular ice during warming of vitrified mouse morulae and its effect on embryo survival

In vitrified solutions, ice can form during warming if the concentration of the cryoprotectant is insufficient. For the cryopreservation of cells, ice is innocuous when it remains outside the cell, but intracellular ice (ICI) is lethal. We tried to estimate the conditions in which ICI forms in vitrified mouse morulae during warming. The solutions for the experiments (EFS10–EFS50) contained 10–50% ethylene glycol plus Ficoll plus sucrose. When vitrified EFS20, EFS30, and EFS40 were kept at −80 °C, they remained transparent after 3 min, but turned opaque after 60 min (EFS20, EFS30) or 24 h (EFS40). Morulae were vitrified with EFS solutions after exposure for 30–120 s at 25 °C. They were warmed by various methods and survival was assessed in culture. After rapid warming (control), survival was high with EFS30 (79–93%) and EFS40 (96–99%). After slow warming, survival decreased with both EFS30 (48–62%) and EFS40 (44–64%). This must be from the formation of ICI. To examine the temperature at which ICI formed during slow warming, vitrified embryos were kept at various sub-zero temperatures during warming. Survival with EFS30 and EFS40 decreased on keeping samples for 3 min at −80 (25–75%), −60 (7–49%), −40 (0–41%), or −20 °C (26–60%). When samples were kept at −80 °C for 24 h, the survival decreased to 0–14%. These results suggest that ICI forms at a wide range of temperatures including −80 and −20 °C, more likely between −60 and −40 °C, and the ice forms not only quickly but also slowly.     

The Short-Term Cost-Effectiveness of Once-Daily Liraglutide Versus Once-Weekly Exenatide for the Treatment of Type 2 Diabetes Mellitus in the United States

Background

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with substantial morbidity, mortality, and economic impacts. Glucagon-like peptide-1 (GLP-1) receptor agonists, such as once-daily (QD) liraglutide and once-weekly (QW) exenatide, are FDA-approved treatment for T2DM. Head-to-head trials and meta-analyses comparing these agents have reported clinically meaningful improvements but small differences in glycemic control between both agents. In this study, we calculate and compare the cost-effectiveness implications of these alternative effectiveness outcomes.

Methods

We developed a decision model to evaluate the short-term cost-effectiveness of exenatide QW 2 mg versus liraglutide QD 1.8 mg in T2DM patients, with effectiveness measured as reduction in glycated hemoglobin (HbA1c). In the base case, the model tracks change in HbA1c and direct medical expenditure over a 6-month time horizon. We calculated and compared the cost per 1% reduction in HbA1c of models populated with clinical data from a head-to-head randomized, controlled trial (DURATION-6) and a network meta-analysis. Expenditure inputs were derived from wholesale acquisition costs and published sources.

Results

In the base case, 6-month expenditure for the liraglutide and exenatide strategies were $3,509 and $2,618, respectively. Using clinical data from DURATION-6 and the network meta-analysis, the liraglutide strategy had an incremental cost per 1% reduction in HbA1c of $4,773 and $27,179, respectively. The most influential model parameters were drug costs, magnitude of HbA1c reduction in patients on treatment for >1 month, and liraglutide gastrointestinal adverse event rate. In probabilistic sensitivity analyses (PSA) using DURATION-6 data, the exenatide strategy was optimal at willingness-to-pay levels below $4,800 per 1% reduction in HbA1c. In a PSA using meta-analysis data, the exenatide strategy was dominant.

Conclusions

Our modeled results demonstrate that the effectiveness and cost-effectiveness of liraglutide QD 1.8 mg relative to exenatide QW 2 mg depend largely on the chosen source of the clinical data.     

Exenatide Twice Daily Plus Glargine Versus Aspart 70/30 Twice Daily in Patients With Type 2 Diabetes With Inadequate Glycemic Control on Premixed Human Insulin and Metformin

ObjectiveMany patients with type 2 diabetes treated with premixed insulin gradually have inadequate glycemic control and switch to a basal-bolus regimen, which raises some concerns for weight gain and increased hypoglycemic risk. Switching to combination use of glp-1 agonist and basal insulin may be an alternative option.MethodsAfter a 12-week premixed human insulin 70/30 dosage optimization period, 200 patients with HbA1c of 7.0% to 10.0% were randomized into 24-week treatment groups with exenatide twice a day plus glargine or with aspart 70/30 twice a day.ResultsAfter 24 weeks, the patients receiving exenatide plus glargine (n = 90) had improved HbA1c control compared with those receiving aspart 70/30 (n = 90) (least squares mean change: ‒0.59 vs ‒0.13%; difference [95% CI]: ‒0.45 [‒0.74 to ‒0.17]) in the full analysis set population. Weight decreased 3.5 kg with exenatide and decreased 0.4 kg with aspart 70/30 (P < .001). The insulin dose was reduced 10.7 units/day (95% CI, ‒12.2 to ‒9.2 units; P < .001) with exenatide, and increased 9.7 units/day (95% CI, 8.2 to 11.2 units; P < .001) with aspart 70/30. The most common adverse events were gastrointestinal adverse effects in the exenatide group (nausea [21%], vomiting [16%], diarrhea [13%]). The incidence of hypoglycemia was similar in 2 groups (27% for exenatide and 38% for aspart 70/30; P = .1).ConclusionIn premixed human insulin‒treated patients with type 2 diabetes with inadequate glycemic control, switching to exenatide twice a day plus glargine was superior to aspart 70/30 twice a day for glycemic and weight control.     

Short-circuit current related to active transport of chloride in frog cornea: effects of furosemide and ethacrynic acid

Active transport of Cl⁻ accounts for 90% of the short-circuit current (s.c.c.) in the isolated frog cornea. 1·10⁻⁵ M furosemide produced a 50% reversible inhibition of this s.c.c. 1·10⁻⁴ M ethacrynic acid reduced the corneal s.c.c. to 32% of the control. In the isolated frog skin epithelium furosemide had no effect on the s.c. at a concentration of 1·10⁻⁴ M and a small stimulation at a concentration of 1·10⁻³ M. The furosemide inhibitory effects seems to be specific for Cl⁻, as it also inhibits Cl⁻ transport in the ascending limb of the loop of Henle (Burg, M.B. (1972) Proc. 5th Int. Congr. Nephrol., p. 50, Abstr.).     

Annual cycle of CO2 exchange over a reed (Phragmites australis) wetland in Northeast China

Net ecosystem exchange of CO₂ (NEE) was measured during 2005 using the eddy covariance (EC) technique over a reed (Phragmites australis (Cav.) Trin. ex Steud.) wetland in Northeast China (121°54′E, 41°08′N). Diurnal NEE patterns varied markedly among months. Outside the growing season, NEE lacked a diurnal pattern and it fluctuated above zero with an average value of 0.07 mg CO₂ m⁻² s⁻¹ resulting from soil microbial activity. During the growing season, NEE showed a distinct V-like diel course, and the mean daily NEE was −7.48 ± 2.74 g CO₂ m⁻² day⁻¹, ranging from −13.58 g CO₂ m⁻² day⁻¹ (July) to −0.10 g CO₂ m⁻² day⁻¹ (October). An annual cycle was also apparent, with CO₂ uptake increasing rapidly in May, peaking in July, and decreasing from August. Monthly cumulative NEE ranged from −115 ± 24 g C m⁻² month⁻¹ (the reed wetland was a CO₂ sink) in July to 75 ± 16 g C m⁻² month⁻¹ (CO₂ source) in November. The annual CO₂ balance suggests a net uptake of −65 ± 14 g C m⁻² year⁻¹, mainly due to the gains in June and July. Cumulative CO₂ emission during the non-growing season was 327 g C m⁻², much greater than the absolute value of the annual CO₂ balance, which proves the importance of the wintertime CO₂ efflux at the study site. The ratio of ecosystem respiration (R_eco) to gross primary productivity (GPP) for this reed ecosystem was 0.95, indicating that 95% of plant assimilation was consumed by the reed plant or supported the activities of heterotrophs in the soil. Daytime NEE values during the growing season were closely related to photosynthetically active radiation (PAR) (r² > 0.63, p < 0.01). Both maximum ecosystem photosynthesis rate (A_max) and apparent quantum yield (α) were season-dependent, and reached their peak values in July (1.28 ± 0.11 mg CO₂ m⁻² s⁻¹, 0.098 ± 0.027 μmol CO₂ μmol⁻¹ photon, respectively), corresponding to the observed maximum NEE in July. Ecosystem respiration (R_eco) relied on temperature and soil water content, and the mean value of Q₁₀ was about 2.4 with monthly variation ranging from 1.8 to 4.1 during 2005. Annual methane emission from this reed ecosystem was estimated to be about 3 g C m⁻² year⁻¹, and about 5% of the net carbon fixed by the reed wetland was released to the atmosphere as CH₄.     

The dominance of warming rate over cooling rate in the survival of mouse oocytes subjected to a vitrification procedure

The formation of more than trace amounts of ice in cells is lethal. The two contrasting routes to avoiding it are slow equilibrium freezing and vitrification. The cryopreservation of mammalian oocytes by either method continues to be difficult, but there seems a slowly emerging consensus that vitrification procedures are somewhat better for mouse and human oocytes. The approach in these latter procedures is to load cells with high concentrations of glass-inducing solutes and cool them at rates high enough to induce the glassy state. Several devices have been developed to achieve very high cooling rates. Our study has been concerned with the relative influences of warming rate and cooling rate on the survival of mouse oocytes subjected to a vitrification procedure. Oocytes suspended in an ethylene glycol–acetamide–Ficoll–sucrose solution were cooled to −196 °C at rates ranging from 37 to 1827 °C/min between 20 and −120 °C, and for each cooling rate, warmed at rates ranging from 139 to 2950 °C/min between −70 and −35 °C. The results are unambiguous. If the samples were warmed at the highest rate, survivals were >80% over cooling rates of 187–1827 °C/min. If the samples were warmed at the lowest rate, survivals were near 0% regardless of the cooling rate. We interpret the lethality of slow warming to be a consequence of it allowing time for the growth of small intracellular ice crystals by recrystallization.     

Biodegradation of Methyl red by Galactomyces geotrichum MTCC 1360

Galactomyces geotrichum MTCC 1360 can decolorize triphenylmethane, azo and reactive high exhaust textile dyes. At shaking condition this strain showed 100% decolorization of a toxic azo dye Methyl red (100 m gl⁻¹) within 1 h in deionized water at 30 °C. The degradation of Methyl red was possible through a broad pH (3–12) and temperature (5–50 °C) range. Glucose and mycelium concentration had increased the decolorization rate, but the addition of 1 gl⁻¹ molasses in deionized water made decolorization possible in only 10 min. Induction in the NADH–dichloro phenol indophenol (NADH–DCIP) reductase, Malachite green reductase, laccase and lignin peroxidase (Lip) activities were observed in the cells obtained after complete decolorization, showing that there is direct involvement in the degradation of Methyl red. The absence of N-N′-dimethyl-p-phenylenediamine (DMPD) in 5 °C, 2-aminobenzoic acid (ABA) in 50 °C and both the compounds in 30 °C sample have shown the differences in the metabolic fate of Methyl red at different temperatures. The untreated dye at 300 mg l⁻¹ concentration showed 88% germination inhibition in Sorghum bicolor, whereas it was 72% in Triticum aestivum. There was no germination inhibition for both the plants by Methyl red metabolites at 300 mg l⁻¹ concentration.

The scientific relevance of the paper

The azo dye Methyl red (100 mg l⁻¹) was decolorized by G. geotrichum MTCC 1360 within 1 h at shaking condition in deionized water. This organism could decolorize Methyl red at wide pH and temperature ranges. Decolorization time was reduced to 10 min by the addition of molasses to deionized water. There was induction in laccase and Lip, NADH–DCIP reductase and Malachite green reductase activities. The metabolic fate of Methyl red changes with temperature which can be evidenced by the formation of 2-ABA at 5 °C, N-N′-DMPD at 50 °C and both the compounds were absent at 30 °C. Phytotoxicity showed that metabolites of dye had induced shoot and root length of both the tested plants.     

Comparisons of the release of vasodilator substances from left and right cardiac chambers of the isolated perfused rabbit heart: Implications for intraventricular thrombus formation

Prostacyclin (PgI₂) and endothelium-derived nitric oxide (EDNO) are produced by the arterial and venous endothelium. In addition to their vasodilator action on vascular smooth muscle, both act together to inhibit platelet aggregation and promote platelet disaggregation. EDNO also inhibits platelet adhesion to the endothelium. EDNO and PgI₂ have been shown to be released from the cultured endocardial cells. In this study, we examined the release of vasoactive substances from the intact endocardium by using isolated rabbit hearts perfused with physiological salt solution (95% O₂/5% CO₂, T = 37 °C). The right and left cardiac chambers were perfused through separate constant-flow perfusion loops (physiological salt solution, 8 ml min⁻¹). Effluent from left and right cardiac, separately, was bioassayed on canine coronary artery smooth muscle, which had been contracted with prostaglandin F_{2α_}(2 × 10⁻⁶ M) and no change in tension was exhibit. However, addition of calcium ionophore A23187 (10⁻⁶ M) to the cardiac chambers’ perfusion line induced vasodilation of the bioassay coronary ring, 61.4 ± 7.4% versus 70.49 ± 6.1% of initial prostaglandin F_2α contraction for the left and right cardiac chambers perfusate, respectively (mean ± SEM, n = 10, p > 0.05). Production of vasodilator was blocked totally in the left heart but, only partially blocked in the right heart by adding indomethacin (10⁻⁵ M) to the perfusate, respectively, 95.2 ± 2.2% versus 41.5 ± 4.8% (mean ± SEM, n = 10, p < 0.05). 6-Keto prostaglandin F_1α, measured in the endocardial superfusion effluent was also higher for the left cardiac chambers than for the right at the time of stimulation with the A23187, respectively, 25385.88 ± 5495 pg/ml (n = 8) versus 13,132.45 ± 1839.82 pg/ml (n = 8), (p < 0.05). These results showed that cyclooxygenase pathway plays major role in generating vasoactive substances for the left cardiac chamber endocardium; while it is not the main pathway for the right ventricular endocardium at which EDNO and PgI₂ could act together and potentiate their antithrombogenic activities in isolated perfused rabbit heart. This may be an explanation for the intraventricular thrombus mostly seen in left ventricle rather than in right ventricle as a complication of myocardial infarction.     

Growth of dinoflagellates, Ceratium furca and Ceratium fusus in Sagami Bay, Japan: The role of temperature, light intensity and photoperiod

Seasonal changes of field populations and growth rates of two dinoflagellates, Ceratium furca and Ceratium fusus, were examined in the temperate coastal water of Sagami Bay, Japan. Weekly field sampling was conducted from August 2002 to August 2003, and laboratory experiments were also carried out to investigate effects of temperature, irradiance and photoperiod on the growth rates of these two Ceratium species. In the field, the abundances of both species increased significantly from April to August 2003, were gradually decreased from November 2002 and were not observed in January 2003. C. fusus was able to increase at lower temperatures in February 2003 compared to C. furca. In the laboratory, the two species did not grow at <10 °C or >32 °C. The highest specific growth rate of C. furca was 0.72 d⁻¹ at 24 °C and 600 μmol m⁻² s⁻¹. Optimum growth rates (>0.4 d⁻¹) of C. furca were observed at temperatures from 18 to 28 °C and at irradiances from 216 to 796 μmol m⁻² s⁻¹. The highest growth rate of C. fusus was 0.56 d⁻¹ at 26 °C and 216 μmol m⁻² s⁻¹. Optimum growth rates of C. fusus were observed at the same irradiance rage of C. furca, whereas optimum temperature range was narrower (26–28 °C). The growth curves of both species indicated saturation of the growth rates when light intensity was above 216 μmol m⁻² s⁻¹, and did not show photoinhibition at irradiances up to 796 μmol m⁻² s⁻¹. The specific growth rates of both Ceratium species were clearly decreased at L:D = 10:14 relative to those at L:D = 14:10 and L:D = 12:12. The present study indicates the two Ceratium species can adapt to a wide range of temperature and irradiance.     

Aquatic metabolism as an indicator of the ecological effects of hydrologic pulsing in flow-through wetlands

Water column metabolism is a major component in the functioning of wetland ecosystems and can be used as an indicator of ecosystem health. The effect of hydrologic pulsing on water column metabolism was studied with 2 year's field data and a validated model for two 1-ha created riparian wetlands in Columbus, OH, USA. Aquatic gross primary productivity (GPP) was measured during hydrologic pulses the first week of April, May and June of 2004 and compared to GPP during steady flow-conditions in April, May and June 2005. Pulses reduced diurnal variation of water temperature, pH and dissolved oxygen, and negatively affected GPP rates. Mean GPP measured during hydrologic flood pulses was 5.4 ± 2.6 kcal m⁻² day⁻¹, significantly lower than that measured for comparable months with steady-flow hydrology (10.8 ± 3.3 kcal m⁻² day⁻¹). Solar-normalized productivity values of 0.08 ± 0.01% of solar energy during pulses and 0.2 ± 0.02% for steady-flow conditions were also significantly different. Different hyperbolic curves of optimum productivity with water temperature were seen for pulsing and steady-flow conditions. A simulation model with hydrology, metabolism, and dissolved oxygen sub models was calibrated with 2005 steady-flow year data and validated with 2004 pulse year data. Results from both the field study and model simulations suggest that there was a threshold hydraulic inflow rate between 30 and 50 cm day⁻¹ where aquatic metabolism became negatively affected by flow.     

Pharmacokinetics of proline-rich tripeptides in the pig

Tripeptides may possess bioactive properties. For instance, blood pressure lowering is attributed to the proline-rich tripeptides Ile-Pro-Pro (IPP), Leu-Pro-Pro (LPP), and Val-Pro-Pro (VPP). However, little is known about their absorption, distribution, and elimination characteristics. The aim of this study was to characterize the pharmacokinetic behavior of IPP, LPP, and VPP in a conscious pig model. Synthetic IPP, LPP, and VPP were administered intravenously or intragastrically (4.0 mg kg⁻¹ BW in saline) to 10 piglets (approximately 25 kg body weight) in the postabsorptive state. After intravenous dosing, the elimination half-life for IPP was significantly higher (P < 0.001) than for LPP and VPP (2.5 ± 0.1, 1.9 ± 0.1, and 2.0 ± 0.1 min, respectively). After intragastric dosing, however, the elimination half-lives were not significantly different between the peptides (9 ± 1, 15 ± 4, and 12 ± 6 min, respectively). Maximum plasma concentrations were about 10 nmol l⁻¹ for the three tripeptides. The fraction dose absorbed was 0.077 ± 0.010, 0.059 ± 0.009, and 0.073 ± 0.015%, for IPP, LPP, and VPP, respectively. Proline-rich tripeptides reach the blood circulation intact, with an absolute bioavailability of about 0.1% when administered via a saline solution. Because half-lives of absorption and elimination were maximally about 5 and 15 min, respectively, this suggests that under these conditions a bioactive effect of these tripeptides would be rather acute.