Manipulation of this pathway is therefore a good target for the s
Manipulation of this pathway is therefore a good target for the stimulation of bone growth in humans [11] and [12]. It is of interest that in the absence of the one molecule necessary for both these processes during embryogenesis, Indian hedgehog,
neither part of the endochondral ossification Venetoclax nmr occurs [7]. This process represents bone formation in trans – one cell type induces the formation of another (cartilage inducing bone) – the cells that give rise to the inducing signals (and extra-cellular matrix) do not themselves produce the bone. Previously, purmorphamine (Pur) that selectively induces osteogenesis in multipotent mesenchymal progenitor cells was identified [13]. Purmorphamine has been shown to increase alkaline phosphatase (ALP) activity in both cell lines C3H10T1/2 and MC3T3-E1 and enhances osteoblastic differentiation of human bone marrow mesenchymal cells in culture
and also when grown on titanium [14] and [15]. Further, it also seems to inhibit adipocyte find more maturation [16] and [17]. Purmorphamine induces osteogenesis by activation of the hedgehog signaling pathway. The transmembranic protein smoothened (Smo) is normally suppressed by another transmembranic protein patched (Ptch); this suppression is inhibited by sonic hedgehog protein in the developmental stage. It has been shown that Smo can be artificially targeted by Pur and the suppression by Ptch on Smo is stopped, leading to an activation of PJ34 HCl Smo and thereby the hedgehog signaling pathway leading to stimulation of bone formation. In this way Pur can replace the function of sonic hedgehog (Fig. 1a) [18]. When the Smo inhibition is blocked by a hedgehog protein, Smo can activate members of the Gli-family. Genetic studies have shown that mutations in Gli2 and/or Gli3 result in severe defects
in skeletal development in mice and humans [19], [20], [21] and [22]. Ablating the hedgehog genes in postnatal chondrocytes leads to dwarfism, showing that the hedgehog is essential for maintaining the growth plate and articular surface and is required for sustaining trabecular bone and skeletal growth [23]. It has been shown that Gli2 is a powerful transactivator of the BMP-2 gene in vitro and in vivo and that overexpression of Gli2 in osteoblast precursor cells induces osteoblast differentiation [24]. This and the combined effect of BMP-2 [25], explain the osteogenic induction by the hedgehog pathway activation [26], [27] and [28]. The mode of delivery of Pur is as important as the biology of its effect as diffusion makes a simple injection ineffective. Delivering sonic hedgehog or purmorphamine by binding it to a calcium phosphate layer should stimulate differentiation and proliferation locally and spread in a controlled manner by the release of calcium phosphate. This delivery system avoids the immediate burst-release of the active molecule and allowing the osteogenesis of the surrounding precursor cells.
40 Based on the proven superiority of split-dose bowel regimens o
40 Based on the proven superiority of split-dose bowel regimens over single-dose regimens, professional guidelines41 and 42 Ribociclib now recommend use of split-dose
preparation. Morning consumption of laxative as part of a split-dose regimen creates 2 concerns. First, patients may be resistant to waking early to complete the laxative. Despite this pragmatic consideration, patients do generally accept and comply with split dosing. Unger and colleagues43 reported 78% compliance with a split dose in patients receiving early morning colonoscopy. Several studies44 and 45 have also shown that patients better tolerate split-dosing preparations. The second concern pertains to the safety of split-dosing administration. Specifically, ingestion of the second dose of a bowel laxative within 2 to 6 hours of colonoscopy might increase the risk for aspiration during sedation (moderate, deep, or general anesthesia). Updated guidelines from the American Society of Anesthesiologists46 state that patients need to abstain from clear liquids for only 2 hours before receiving sedation. Nonetheless, some anesthesiologists question the clinical and safety equivalency of PEG solutions to other clear
liquids. In addressing these concerns, despite widespread use of PEG solutions for almost 30 years in millions of patients, there are only rare (<12), isolated reports of fatal, aspiration-induced chemical pneumonitis after administration of a PEG solution (most commonly occurring with nasogastric administration in adults Smad inhibitor or children with altered mental status). Phosphoribosylglycinamide formyltransferase Furthermore, a 2010 study47 showed no difference in residual gastric volume in patients taking a split-dose bowel
preparation (19.7 mL) versus a single-dose evening preparation (20.2 mL). Therefore, based on their proven superiority, split-dose bowel regimens should be recommended for most patients with IBD undergoing surveillance whose disease is in remission or well controlled. Caution is advised in patients with partial bowel obstruction, gastroparesis, or known delayed intestinal motility, because these patients are at increased risk for gastric retention and aspiration. In these instances, a 6-hour window is recommended between completion of the laxative ingestion and initiation of sedation. Several laxative formulations are available for preparation before colonoscopy. Randomized controlled trials comparing these agents are limited, and none has proven superiority. However, for all available agents, a split-dose regimen generally is preferred to single-dose regimens. Laxative options may be subsumed under 2 broad categories: PEG solutions and low-volume, hyperosmolar solutions (see Table 2). Several PEG solutions are available, including full-volume (4 L) balanced, isosmotic formulations (standard or sulfate-free) and a reduced volume (3 L) formulation, which contains ascorbate.
Control group was not exposed to any procedure during the experim
Control group was not exposed to any procedure during the experiment (G1, n = 12). The test groups were submitted to inhalation saline solution (G2, n = 10), budesonide 30 μg (G3, n = 10), and budesonide 100 μg (G4, n = 10), during a 14-day period. Vemurafenib manufacturer All the solutions were administered to the rats once a day. In order to minimize stress generated by novelty effect, the animals were submitted to the forced
ventilation chamber without nebulization for 5 min during 4 days, before the beginning of the experimental period. Besides the inhalatory treatment, all animals were submitted to the model of induction of alveolar bone loss. Cotton ligatures (Ethicon, Johnson & Johnson, São Paulo, Brazil) were placed around the second maxillary molars on the right side under general anaesthesia with xylazine/ketamine (10 mg/kg—1:1). The contra-lateral teeth (that were not submitted to any manipulation)
were considered for control analysis.11, 12, 13 and 14 Akt inhibitor To administrate the inhalatory solutions to the animals, a ventilation chamber was built according to a previous study.15 It consisted in a 3 mm thickness acrylic transparent cage (22 cm × 22 cm × 22 cm), divided into four cells with the same space each one and covered by a removable lid of the same material. A hole was present in the centre of the lid. The cage was connected to a nebulizer through a 5 mm diameter hose. The researchers prepared the solutions. Based on 5 min nebulization capacity Urocanase of the nebulizer (1.1 ml), 2.7 ml of budesonide (Pulmicort®, 0.5 mg/ml, AstraZeneca, São Paulo, Brazil) was diluted in 97.3 ml of saline solution (NaCl 0.9%) for G3. For G4, 9.1 ml of budesonide was diluted in 90.9 ml of NaCl 0.9%. The rats were placed in the cage that was covered and sealed with adhesive tape, to minimize possible loss of medication during the
nebulization procedure. After that, the animals were maintained for 1 min extra to dissipate the solution in the cage. Following, the chamber was cleaned with water and soap to remove deposits of the medication on the walls. All the procedures were performed in the morning, once a day, at the same time, during 14 days. To ensure proper operation of the apparatus, nebulization was performed without the animals in the cage in order to verify the nebulization volume during the experimental period once a week. Additionally, the residual volume in the reservoir was measured to verify possible alterations in the apparatus. Body weight was measured (in grams) to evaluate animals general health at days 0, 7, and 14, during the experimental period. The animals were killed by decapitation. Such procedure was performed 24 h after the last administration of the medication/saline solution. The levels of TNF-α in supernatants were determined by ELISA using commercial anti-cytokine antibody pairs (Becton Dickson, Pharmingen, San Jose, CA, USA), according to the manufacturer's protocols.
Considerable artifact was seen in the diffusion sequence with the
Considerable artifact was seen in the diffusion sequence with the stainless steel stent but not in the nitinol containing stents (Figure 5). Mean maximum radial distortion on dMRI scans was 3.4 mm and 3.8 mm in the nitinol containing stents versus 11.8 mm in the stainless steel stent. Additionally, the nitinol containing stents produced minimal torque in T2 or diffusion weighted sequences. In the current study, we found an association between pretreatment tumor ADC values and subsequent tumor response to chemoradiation in patients with pancreatic cancer. There was a significant
correlation between pre-treatment mean tumor ADC values and the percent tumor cell destruction observed http://www.selleckchem.com/products/sch772984.html at the time of surgery. Additionally, analysis of pretreatment ADC histograms
for each tumor demonstrated a shift towards higher ADC values in tumors that later responded to treatment. These preliminary findings suggest dMRI may be useful as an imaging biomarker in pancreatic cancer. An early selleck chemicals llc imaging biomarker for patients with pancreatic cancer is greatly needed. Treatment with chemoradiation is associated with considerable toxicity and a poor outcome for many patients [1], [20] and [21]. By identifying either before treatment or part way into a treatment course if a patient is responding, we have the potential to adapt therapy. Patients with nonresponding tumors can have therapy intensified or modified. Additionally, dMRI could be useful to determine if patients are resectable after chemoradiation therapy. For patients who are borderline resectable, it is likely some become resectable after chemoradiation but Flavopiridol (Alvocidib) are never offered surgery because pancreatic tumors regress slowly on CT imaging [2], [3], [4], [5] and [6]. Although longitudinal dMRI was not accomplished in this study, additional information related to spatially varying ADC changes within the tumor mass could be obtained after initiation of treatment to provide information related to tumor response and identify patients who may be resectable despite
what is seen on CT [18]. A limited number of reports have looked at dMRI in pancreatic cancer. One retrospective study found tumors with low ADC values at baseline responded poorly to systemic therapy, consistent with our findings [22]. Another report found a correlation between preoperative ADC values and the amount of tumor fibrosis in patients who did not receive preoperative therapy. Tumors with a low ADC were found to be densely fibrotic [23]. The large amount of fibrotic tissue in pancreatic tumors may limit the delivery of radiosensitizing systemic therapy and lower the amount of oxygen available for radiation induced free radical formation thereby decreasing the effectiveness of chemoradiation therapy [24].
According to Loginov (2006), a decrease in pan evaporation has be
According to Loginov (2006), a decrease in pan evaporation has been recorded over the entire territory of Belarus during the May–October period in recent decades (i.e. since 1980). Such a decrease in pan evaporation, known as 'the evaporation ERK inhibitor molecular weight paradox' (IPCC 2007) can be partially explained by changes in the wind speed (the near-surface wind is one of the main forcing factors). It was found that in the wet areas of the western former USSR (where our study region lies) the near-surface wind speed decreased by a factor of
1.6 between 1961 and 1990 (Meshcherskaya et al. 2004). According to our updated analyses, a reduction in wind speed was observed up to the 2000s, but the rates of its changes were reduced compared to pre-1990 decades. Over Belarus, the mean wind speed prior to 2004 was almost 20% less
(Loginov 2006). Visible evaporation (the difference between pan evaporation and precipitation) is an important characteristic of the regional water cycle. Indirectly, it indicates the total energy losses due to evaporation over the region. A positive value of visible evaporation indicates a deficit in the regional water budget, and the water demand by the atmosphere exceeds precipitation (so-called 'dry' conditions are perceived). When precipitation exceeds pan evaporation, selleck visible evaporation is negative (which corresponds to 'humid' conditions). The more negative the visible evaporation, the wetter the region, and the excess water remains for runoff and for replenishing soil moisture. To analyse visible evaporation changes, temporal changes in precipitation were studied first (Figure 9). Over Epothilone B (EPO906, Patupilone) most of the study region, there was a sizeable precipitation increase during the warm period (May–September) with small areas of decreasing precipitation. The absolute values of these decreases were much smaller than those in the areas of precipitation increase, and the region-wide precipitation estimates show increases
of 8–14% during the 1966–2008 period for the regions in question (see also HELCOM 2007, BACC 2008). Over the entire Baltic Sea Drainage Basin, long-term mean values of visible evaporation are negative, i.e. this region is located in the zone of sufficient moistening. Like pan evaporation, the mean visible evaporation after the 1980s became smaller than that in the previous two decades (Figure 10). Over the largest study region (region 1), where both precipitation and pan evaporation increased, variations in visible evaporation during the 1961–2008 period did not have a systematic component, but its interannual variability did increase sharply after the mid-1980s. In the south of the taiga zone (region 2) and in the mixed forest zone (region 3), the features of the visible evaporation changes are similar: after the mid-1980s visible evaporation fluctuations occurred mainly in the negative range, i.e. the region's soil moisture content increased.
After the treatment periods, both for the genotoxicity and antige
After the treatment periods, both for the genotoxicity and antigenotoxicity evaluation,
the cells were collected and, after obtaining the cell suspension, were subjected to the cell viability test with Trypan Blue (Gibco), according to the methodology described by Salvadori et al. (2003). For this evaluation, 5 μL of the cell suspension was mixed with 5 μL of Trypan Blue, where it was counted 100 cells click here of each treatment. The cells stained in white were considered live and the ones stained in blue dead. After counting the cell viability, 20 μL of the cell suspension was mixed to 120 μL of low melting point agarose at 37 °C. Then, this cell suspension was placed on slides previously coated with normal agarose and covered with coverslips. After a brief period of solidification
at 4 °C (15 min), the coverslips were removed and the slides incubated in lysis solution (1 mL of Triton X-100, 10 mL of DMSO and 89 mL of lysis stock – NaCl 2.5M, EDTA 100 mM, Tris 10 mM and ∼8 g of NaOH, pH = 10), in the dark, at 4 °C, for, at least, 1 h. After lysis, the slides were transferred to an electrophoresis vat and covered with an alkaline buffer (NaOH 300 mM + EDTA 1 mM, pH > 13), where they remained for 20 min for stabilization. After this period, they were subjected to electrophoresis at 39 V, 300 mA (∼0.8 V/cm) for 20 min. After the electrophoresis period, the slides were removed and neutralized in Tris buffer (0.4 M Trizma Hydrochloride, pH 7.5),
Galunisertib fixed in absolute ethanol for 10 min and stored at 4 °C, until the time of analysis. Sclareol The slides were stained with 50 μL of GelRed® solution (15 μL of GelRed 10,000× in water, 5 mL of NaCl at 1M, and 45 mL of distilled water) and immediately analysed after staining. It was analysed, in Leica epifluorescence microscopy, magnification of 400×, filter B – 34 (excitation: i = 420 nm–490 nm, barrier: I = 520 nm), 100 nucleoids per slide, totalling 600 nucleoids per treatment. The nucleoids were visually classified and allocated in one of the four classes (0, 1, 2, 3) according to the migration of the fragments as follows: class 0, no tail; class 1, small tail with size smaller than the diameter of the head (nucleus); class 2, size of the tail equal to the diameter of the head or even twice the diameter of the head and class 3, tail larger than the diameter of the head ( Rigonato et al., 2005). The total score was obtained by multiplying the number of cells in each class by the class damage, according to the formula: Total score = (0 × n1) + (1 × n2) + (2 × n3) + (3 × n3), where n = number of cells in each class analysed. Thus, the total score could vary from 0 to 300.
Therefore, in this study we used axenic strains of P donghaiense
Therefore, in this study we used axenic strains of P. donghaiense and P. tricornutum to assess their allelopathic interactions under controlled laboratory conditions. We first investigated their mutual interactions in a laboratory-designed co-culture experiment with several combinations of initial cell densities. Then, we further tested the allelopathic effects of the cell-free filtrates of one species on the growth of the other one by growing the microalgal cells in the presence of enriched culture filtrates. Both the axenic strains of the dinoflagellate
Prorocentrum Cabozantinib ic50 donghaiense Lu and the marine diatom Phaeodactylum tricornutum (Bacillariophyta) were obtained from the Institute of Hydrobiology, Jinan University, Guangzhou, China, and were routinely cultivated under standardised conditions at constant irradiance (70 μmol m− 2 s− 1) and temperature (23°C) in a 12 h/12 h (light/dark) photoperiod cycle. The artificial seawater was passed
through a 0.45 μm filter prior to being used for culture medium preparation, and an f/2 click here nutrient solution was used in the experiments ( Guillard 1973). The salinity of the artificial seawater was 30 PSU and the initial pH of the culture was approximately 7.0. The microalgal cells were cultivated to the exponential growth phase for use. They were inoculated into 250-mL Erlenmeyer flasks containing fresh f/2 seawater medium; the total experimental volume was 100 mL. The initial cell densities were set at 1.0 × 104 and 1.0 × 105 cells mL− 1 for the two microalgae respectively. Hence, the resulting combinations of initial cell densities of P. donghaiense and P. tricornutum were respectively (1) 1.0 × 104 cells mL− 1 each; (2) 1.0 × 104 and 1.0 × 105 cells mL− 1; (3) 1.0 × 105 and 1.0 × 104 cells mL− 1; and (4) 1.0 × 105 cells mL− 1 Casein kinase 1 each. As controls, both microalgae species were cultured individually at initial cell densities of 1.0 × 104 and 1.0 × 105 cells mL− 1. During the maintenance of the experimental
stages, the glass flasks containing algal cells were shaken three times every day by hand at the set time, and they were randomly rearranged to minimise the effects of light or temperature gradients in the plant growth chamber. The growth conditions were the same as stated above, and all experiments were carried out in triplicate. Based on the cell growth characteristics of these microalgae, culture samples were collected in the beginning growth stage (BGS), lag growth stage (LGS), exponential growth stage (EGS) and stationary growth stage (SGS), basically on Day 1, Day 4, Day 7 and Day 10 respectively. Thereafter, an 0.5 mL volume of solution was sampled, and microalgal cell densities were counted using a haemocytometer under an optical microscope after the cells were preserved ( Cai et al. 2013). In order to verify the effects of allelopathic compounds of one microalga on the growth of the other, the culture filtrates of P. donghaiense and P.
05), but it presented a more intense nociceptive response in phas
05), but it presented a more intense nociceptive response in phase II when compared to all groups (one-way ANOVA/Bonferroni's test P < 0.05, Fig. 3A). At P60, we observed a pattern
of nociceptive behavior similar PF-02341066 nmr to the responses recorded at P30 for all groups in both phases (phase I: F = 6.4, phase II: F = 12.52, one-way ANOVA, Bonferroni's test, P > 0.05, Fig. 3B). However, the morphine-vehicle I group presented a more marked nociceptive response in phases I and II when compared to other groups (one-way ANOVA/Bonferroni's test, P < 0.05, Fig. 3B). The administration of ketamine 30 min before the formalin test prevented the higher nociceptive response observed in the morphine group compared to the control group, at P30 and P60. Our results show that at P30, the control-ketamine (C-ketamine) and morphine-ketamine (M-ketamine) groups presented decreased nociceptive responses in both phases of the test when compared to the control-vehicle II (C-vehicle II) and morphine-vehicle II (M-vehicle II) groups (phase I: F = 7.97, phase II: F = 79.28, one-way ANOVA, Bonferroni's test, P < 0.05 for both phases; Fig. 4A). However, the morphine-ketamine group exhibited a less marked nociceptive response when compared to the control-ketamine group
in both phases of the test (one-way ANOVA, Bonferroni's test, P < 0.05; Fig. 4A). The morphine-vehicle II group, in turn, GDC-0941 supplier presented a similar nociceptive response to that of the control-vehicle II group in phase I (one-way ANOVA, P > 0.05), but a higher nociceptive response in phase II when compared to all groups (one-way ANOVA/Bonferroni's test P < 0.05, Fig. 4A). At P60, we observed a pattern of nociceptive response similar to that mafosfamide seen at P30 for all groups in both phases (one-way ANOVA, Bonferroni's test, P < 0.05, Fig. 4B). However, the morphine-vehicle II group presented a more intense nociceptive response than all other groups in phase I and phase II (phase I: F = 5.63, phase II: F = 11.92, one-way ANOVA/Bonferroni's test, P < 0.05 for both phases, Fig. 4B). In this
study, we demonstrated that rats that received morphine during the second week of life showed an increase in nociceptive behavior in phase II of the formalin test at P30. This increased response was partially reversed by a non-steroidal anti-inflammatory drug (indomethacin) and completely reversed by an NMDA receptor antagonist (ketamine). Moreover, at P60, the morphine-treated animals showed an increase in the nociceptive response in both phases of the formalin test (representing the neurogenic and inflammatory pain responses), which was also partially reversed by indomethacin and completely reversed by ketamine. These results indicate that exposure to drugs in early life can have long-lasting implications for the development of the nervous system, such as permanent changes in pharmacological responses and cell signaling (for a review, see Stanwood and Levitt, 2004).
The characterization of partial purified compounds
was ca
was carried out by FTIR and HPLC analysis. Infrared spectra showed a primary imine function (3469–3451 cm−1), amine function (3040, 673 cm−1), alkane groups (2958–2853 cm−1, 1466–1461 cm−1) (C BI 2536 mw C) of aromatic ring (1639–1495 cm−1), p-di substituted benzene (831 and 801 cm−1) and secondary alcohol function (3469–3451, 1370−1, 408, 1192−1, 198, 1040–1111 cm−1). HPLC analysis showed confirmation through similar λmax of standard, constructed library of reference standards by Shimadzu Inc. with isolated antibiotic, similar characterization of compound was reported earlier by many investigators [25] and [35]. Currently, increased resistant among pathogens against the available antimicrobial compounds, search of novel natural source for production of antimicrobial compounds is important. Present investigation highlights importance of media and cultural conditions for production of antimicrobial compound with its structural
characterization. Authors are thankful to Dr. Navin R. Sheth for his valuable support and help in analysis Epigenetics inhibitor of samples. "
"Cellulose is a structural framework of plant cell wall comprising of 35–50% weight basis of plant material [1] and one of the major constituents of renewable biomass. The major contribution for structural component in the cell wall is a cellulose complex comprising of linear polymer of β (1→4) glucose units. In plant cell walls, the cellulose contributes a microcrystalline structure and its component cellulose 1α, one of the stable isoform, which aids to 70% crystalline thus makes them hard material for saccharification [2]. The microcrystalline structure of cellulose is more difficult to hydrolyze economically into reducing sugars when compared to starch [3]. Generally cellulose hydrolytic enzymes are produced naturally by a wide range of microbial communities, Uroporphyrinogen III synthase including bacterial and fungal species. They are known to biosynthesize different types of cellulase enzymes, which have distinct metabolic
actions on the breakdown of cellulose [4] and [5] and these enzymes play a key role in the large scale conversion of plant biomass into simple, reducing sugars and facilitate the possible opportunity in modern tools of biotechnological applications to meet the growing fuel demands [6]. Due to the high cost, ever growing demand and depletion of fossil fuel resources with global warming problems by the increased emission of greenhouse gases (GHG); the spread of cost-effective technologies for producing alternate renewable fuels such as ethanol from cellulosic biomass feedstocks have emerged both at research and industrial scale. The second-generation biofuel, cellulosic ethanol is produced from non food based, renewable, fibrous lignocellulosic plant biomass.
The ultimate goal is to utilise these design principles so as to
The ultimate goal is to utilise these design principles so as to generate functional artificial metalloproteins. Mutagenesis studies of native protein scaffolds, or re-engineering of metal ion sites into other protein scaffolds, are often hampered by the complexity of the natural scaffold and can be heavily biased by the 'evolutionary baggage' they contain. An attractive approach therefore involves the de novo (from scratch) design of both an artificial
miniature protein fold and at the same time a metal ion binding site. These would allow one to address, without bias, what features of the protein matrix are important in tuning the metal ion properties. Though various de novo protein folds have been prepared including β-sheets and mixed GSK2118436 chemical structure α/β-motifs, the
introduction of metal ion binding sites has generally focussed on α-helices and bundles thereof (see Figure 1). These scaffolds are easier to design, MS-275 order relying primarily on the heptad repeat approach abcdefg and the population of the a and d sites with hydrophobic residues which form a hydrophobic core, and as such represent an attractive starting point for metalloprotein engineers. This short review has focused on the de novo design of metalloproteins which have been reported in the last couple of years. Readers are directed to some excellent reviews covering earlier findings [ 1, 2 and 3]. The introduction of metallo-porphyrins into designed proteins has received significant attention as hemeproteins are capable of performing a large range of functions including oxygen transport, electron transfer/transport and catalysis. Recently the design of a mini helix–heme–helix architecture named mimochrome VI has been reported, capable of forming an asymmetric 5-coordinate iron-porphyrin with a cavity on the distal face for small molecule access. This was immobilised on a self-assembled monolayer coated gold electrode and found to electrocatalytically turn over dioxygen [4], and in solution reported to be capable of peroxidise-like catalytic activity [5]. An attractive advantage of mimochrome VI is that unlike native peroxidises, it is catalytically active in the presence
of an organic co-solvent, broadening the scope of where it could be applied. A similar asymmetric 5-coordinate iron-porphyrin was introduced into a larger four-helix bundle as mimochrome VI was too small to engineer see more an Arg residue on the distal face, which enhanced hydrogen peroxide activation and improved catalytic activity [6]. A rationally designed four-helix bundle containing two iron-porphyrins was the first to bind dioxygen stably at room temperature, by controlling and preventing water access to the iron-porphyrin, and remarkably with a 10-fold higher affinity than carbon monoxide [7••]. The iron-porphyrin affinity of the distal His, and thereby access to the 5-coordinate iron-porphyrin capable of coordinating dioxygen, can be controlled by mutagenesis.