Hypoxia-inducible factor 1α regulates branching morphogenesis during kidney development

The kidneys are exposed to hypoxic conditions during development. Hypoxia-inducible factor (HIF), an important mediator of the response to hypoxia, is believed to have an important role in development. However, the relationship between HIF and branching morphogenesis has not been elucidated clearly.     

Synthesis and biological evaluation of glucose conjugated phthalocyanine as a second-generation photosensitizer

Photodynamic therapy (PDT) is a treatment method using light and photosensitizers (PSs), which is categorized as a non-invasive surgery treatment for cancers. When the tumor is exposed to a specific light, the PSs become active and generate reactive oxygen species (ROS), mainly singlet oxygen which kills nearby cancer cells. PDT is becoming more widely recognized as a valuable treatment option for localized cancers and pre-cancers of skin as it has no long-term effects on the patient. But, due to the limited penetration rate of light into the skin and other organs, PDT can’t be used to treat large cancer cells or cancer cells that have grown deeply into the skin or other organs. Hence, in this study, our focus centers on synthesizing glucose-conjugated phthalocyanine (Pc) compatible with near-infrared (NIR) irradiation as second-generation photosensitizer, so that PDT can be used in a wider range to treat cancers without obstacles.     

Nitrosothiol Formation and Protection against Fenton Chemistry by Nitric Oxide-induced Dinitrosyliron Complex Formation from Anoxia-initiated Cellular Chelatable Iron Increase

Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with ^•NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged ^•NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief ^•NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1–2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief ^•NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of ^•NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of ^•NO.     

Cryopreservation of heat-shocked canine adipose-derived mesenchymal stromal cells with 10% dimethyl sulfoxide and 40% serum results in better viability,proliferation, anti-oxidation,and in-vitro differentiation

Cryopreserved canine adipose-derived mesenchymal stromal cells (Ad-MSCs) can be used instantly in dogs for clinical uses. However, cryopreservation results in a reduction of the cellular viability, proliferation, and anti-oxidation of post-thawed Ad-MSCs. Therefore, there is a need for in-vitro procedure to improve post-thawed Ad-MSCs’ viability, proliferation, anti-oxidation, and differentiation capacity. In this study, fresh-Ad-MSCs were activated with heat shock, hypoxia (5% O₂), or hypoxia (5% O₂) + heat shock treatments. The results showed that compared to the other treatments, heat shock significantly improved the proliferation rate, anti-oxidation, heat shock proteins and growth factors expressions of canine-fresh-Ad-MSCs. Consequently, fresh-Ad-MSCs were heat-shocked and then cryopreserved with different combinations of dimethyl sulfoxide (Me₂SO) and fetal bovine serum (FBS) to determine the combination that could effectively preserve the cellular viability, proliferation, anti-oxidation and differentiation capacity of Ad-MSCs after cryopreservation. We found that C-HST-Ad-MSCs cryopreserved with 10% Me₂SO + 40% FBS presented significantly (p < 0.05) improved cellular viability, proliferation rate, anti-oxidant capacity, and differentiation potential as compared to C-HST-Ad-MSCs cryopreserved with 1% Me₂SO + 10% FBS or 1% Me₂SO alone or control. We concluded, heat shock treatment is much better to enhance the characteristics of fresh-Ad-MSCs than other treatments, moreover, C-HST-Ad-MSCs in 10% Me₂SO + 40% FBS showed better results compared to other cryopreserved groups. However, future work is required to optimize the expression of heat shock proteins, which would further improve the characteristics of fresh- and cryopreserved-HST-Ad-MSCs and reduce the dependency on Me₂SO and FBS.     

Nitroimidazole conjugates of bis(thiosemicarbazonato)Cu(II) - Potential combination agents for the PET imaging of hypoxia

Combination agents comprising two different pharmacophores with the same biological target have the potential to show additive or synergistic activity. Bis(thiosemicarbazonato)copper(II) complexes (e.g. ⁶⁴Cu-ATSM) and nitroimidazoles (e.g. ¹⁸F-MISO) are classes of tracer used for the delineation of tumor hypoxia by positron emission tomography (PET). Three nitroimidazole-bis(thiosemicarbazonato)copper(II) conjugates were produced in order to investigate their potential as combination hypoxia imaging agents. Two were derived from the known bifunctional bis(thiosemicarbazone) H₂ATSM/A and the third from the new precursor diacetyl-2-(4-N-methyl-3-thiosemicarbazone)-3-(4-N-ethylamino-3-thiosemicarbazone) - H₂ATSM/en. Oxygen-dependent uptake studies were performed using the ⁶⁴Cu radiolabelled complexes in EMT6 carcinoma cells. All the complexes displayed appreciable hypoxia selectivity, with the nitroimidazole conjugates displaying greater selectivity than a simple propyl derivative used as a control. Participation of the nitroimidazole group in the trapping mechanism is indicated by the increased hypoxic uptake of the 2- vs. the 4-substituted ⁶⁴Cu-ATSM/A derivatives. The 2-nitroimidazole derivative of ⁶⁴Cu-ATSM/en demonstrated superior hypoxia selectivity to ⁶⁴Cu-ATSM over the range of oxygen concentrations tested. Biodistribution of the radiolabelled 2-nitroimidazole conjugates was carried out in EMT6 tumor-bearing mice. The complexes showed significantly different uptake trends in comparison to each other and previously studied Cu-ATSM derivatives. Uptake of the Cu-ATSM/en conjugate in non-target organs was considerably lower than for derivatives based on Cu-ATSM/A.     

Effects of training on axial muscle of two cyprinid species: Chondrostoma nasus (L.) and Leuciscus cephalus (L.)

The effect of an endurance training program lasting 17 weeks was studied in two cyprinid species, Chondrostoma nasus (L.) and Leuciscus cephalus (L.). Red, intermediate and white axial muscle were investigated. Morphometrical analysis revealed that training induced, in both species, increased red and intermediate muscle mass, fibre diameter and capillarization. Differences between species in the response to training were observed for volume densities of mitochondria and lipid. In contrast to C. nasus, L. cephalus show higher values for these compartments in red and intermediate fibres. The results are considered adaptational changes which increase the aerobic capacity of red and intermediate muscle fibres to meet higher sustained swimming activities.     

The Tumor Suppressor pVHL Down-regulates Never-in-Mitosis A-related Kinase 8 via Hypoxia-inducible Factors to Maintain Cilia in Human Renal Cancer Cells

NEK8 (never in mitosis gene A (NIMA)-related kinase 8) is involved in cytoskeleton, cilia, and DNA damage response/repair. Abnormal expression and/or dysfunction of NEK8 are related to cancer development and progression. However, the mechanisms that regulate NEK8 are not well declared. We demonstrated here that pVHL may be involved in regulating NEK8. We found that CAK-I cells with wild-type vhl expressed a lower level of NEK8 than the cells loss of vhl, such as 786-O, 769-P, and A-498 cells. Moreover, pVHL overexpression down-regulated the NEK8 protein in 786-O cells, whereas pVHL knockdown up-regulated NEK8 in CAK-I cells. In addition, we found that the positive hypoxia response elements (HREs) are located in the promoter of the nek8 sequence and hypoxia could induce nek8 expression in different cell types. Consistent with this, down-regulation of hypoxia-inducible factors α (HIF-1α or HIF-2α) by isoform-specific siRNA reduced the ability of hypoxia inducing nek8 expression. In vivo, NEK8 and HIF-1α expression were increased in kidneys of rats subjected to an experimental hypoxia model of ischemia and reperfusion. Furthermore, NEK8 siRNA transfection significantly blocked pVHL-knockdown-induced cilia disassembling, through impairing the pVHL-knockdown-up-regulated NEK8 expression. These results support that nek8 may be a novel hypoxia-inducible gene. In conclusion, our findings show that nek8 may be a new HIF target gene and pVHL can down-regulate NEK8 via HIFs to maintain the primary cilia structure in human renal cancer cells.     

The effects of starvation and repeated disturbance on mass loss,pit construction,and spatial pattern in a trap‐building predator

1. Starvation tolerance is an important trait for animals, as most will encounter starvation within their lifetime. Sit‐and‐wait predators are better adapted to starvation owing to their naturally low encounter rate with prey. 2. Starvation tolerance was studied under three levels of disturbance of wormlion larvae, a strict sit‐and‐wait predator that constructs pits. 3. Frequently disturbed wormlions constructed pits less often, and larger individuals continued to construct pits more frequently than smaller ones. It was expected that a high disturbance level would lead to a high rate of mass loss, however, surprisingly, the rate of mass loss was not higher for the frequently disturbed group. This suggests that the energetic cost of pit construction and maintenance is not as high as previously suggested for other pit‐building predators. 4. Larger individuals tolerated starvation better, in losing a lower proportion of their initial body mass and having higher chances of survival throughout the experiment. 5. The effect of starvation on the distance to neighbours was also investigated, and starved individuals were expected to maximise this distance in order to avoid interference competition. However, wormlions were usually clumped, and starvation or feeding had no effect on the pits' spatial pattern, suggesting that interference competition plays a minor role in this species. 6. Generally, wormlion larvae demonstrated a high starvation tolerance and low mortality rates even after 9 weeks of starvation.     

Effect of intermittent chronic exposure to hypoxia on feeding behaviour of rats

Healthy albino male rats were exposed to a simulated high altitude (HA) equivalent to 25000 ft (7620 m) for 6 h daily, continuously for 21 days to study the feeding behaviour. The 24-h food and water intake and body weight once in 3 days were recorded. Blood samples were drawn once a week from the retro-orbital venous plexus for blood sugar analysis. All the parameters were recorded before, during and after exposure to simulated HA. The results show a decrease in 24-h food and water intake and decreased gain in body weight during hypoxic exposure, which showed a tendency to come back to control during the post-exposure period. The blood sugar reflected a state of mild hyperglycaemia during exposure to HA.