Effects of famotidine and vitamin C on low dose radiation-induced micronuclei in mice bone marrow cells

     The radioprotective effects of vitamin C and famotidine were investigated using the micronucleus test for anticlastogenic and cell proliferation activity. Various doses of vitamin C and famotidine were administered intraperitoneally 2 h before 2Gy gamma irradiation to NMRI adult male mice. Frequency of micronuclei in 1000 PCEs (MnPCEs) were scored for each sample. Cell proliferation ratio (PCE/PCE+NCE) was also calculated. Data were statistically evaluated using one-way ANOVA and Tukey’s HSD test. The results indicated that gamma irradiation alone caused a significant increase in the MnPCEs and reduced the cell proliferation ratio. Administration of various doses of famotidine and vitamin C before gamma irradiation reduced MnPCEs and therefore clastogenic effects of radiation. Famotidine didn’t change cell proliferation compared to the irradiation group but vitamin C significantly improved and increased cell proliferation to the control group’s level. The dose reduction factor (DRF) calculated, shows a DRF=2 for famotidine and a DRF=1.7 for vitamin C which is indicative of a high radioprotective property of these compounds. The way in which these compounds reduced the clastogenic effects of radiation might be via antioxidant property and free radical scavenging mechanism

The probability of influence of the abscopal effect on reduction of similar far away 4T1 cell line tumors by irradiation of main tumor

The most important problem with radiotherapy is the limitation of whole body irradiation of a metastatic patient. There are evidence showing that similar effect will occur in non-irradiated tumors similar to the irradiated ones. This effect is called abscopal effect. In the present study, the abscopal effect on local induced mice breast cancers has been investigated. One million of 4T1 mice breast cancer cell line was injected to balb/c mice subcutaneously while being under anesthesia. After the growth of tumors till becoming palpable, one of two induced tumors were exposed to total 28 Gy, with gamma rays emitted from a cobalt -60 tele-therapy machine in 14 fractions with 2 Gy daily doses. Tumor volumes were measured, using the caliper. The data was analyzed by the use of non-parametrical and ANOVA tests. Similar growth in non-irradiated control tumors was seen. After 10 or 11 fractions of one- side irradiation and total dose of 20 to 22 Gy, however, non-irradiated tumors, similar to irradiated ones, showed similar effect, reduction of size and volume different from control groups (P<0.05).The reduction of non-irradiated tumors relative to irradiation of another tumor in the same mouse is the emblem of occurrence of the abscopal effect. The mechanism of the abscopal effect is unknown but it could be related to the release of cytokines from irradiated tumors with their receptors existing on the surface of non-irradiated tumors. By induction of this effect, the remission probability of small metastases after local irradiation could be possible

Homogenous charge compression ignition (HCCI) technique: a review for application in two-stroke gasoline engines

Since Homogeneous Charge Compression Ignition (HCCI) has significantly low temperature combustion, NOx will be dramatically reduced while the mixture will be largely homogenous, thus soot formation will naturally be reduced too. The system can be operated under an ultra lean fuel condition thus able to achieve high efficiency and low emission. In addition to, two-stroke engine's advantages i.e. light, simple construction, less components and cheap to manufacture, two-stroke engines have the potential to pack almost twice the power density than that of four-stroke engine with similar capacity. The problem of poor combustion efficiency and high white smoke emission, which is caused by burnt engine oil, can be addressed by the incorporation some features that will ultimately convert a typical two-stroke engine into an efficient HCCI engine demonstrating bulk combustion. This paper briefly described an attempt to modify two-stroke engine design to prove the claim. Such an engine with its conversion will be suitable for use as a prime mover for series Hybrid Electrical Vehicle (HEV) giving high power-to-weight ratio and improved efficiency of the overall vehicle powertrain system

Tumor cell culture on collagen–chitosan scaffolds as three-dimensional tumor model: A suitable model for tumor studies

Tumor cells naturally live in three-dimensional (3D) microenvironments, while common laboratory tests and evaluations are done in two-dimensional (2D) plates. This study examined the impact of cultured 4T1 cancer cells in a 3D collagen–chitosan scaffold compared with 2D plate cultures. Collagen–chitosan scaffolds were provided and passed confirmatory tests. 4T1 tumor cells were cultured on scaffolds and then tumor cells growth rate, resistance to X-ray radiation, and cyclophosphamide as a chemotherapy drug were analyzed. Furthermore, 4T1 cells were extracted from the scaffold model and were injected into the mice. Tumor growth rate, survival rate, and systemic immune responses were evaluated. Our results showed that 4T1 cells infiltrated the scaffolds pores and constructed a 3D microenvironment. Furthermore, 3D cultured tumor cells showed a slower proliferation rate, increased levels of survival to the X-ray irradiation, and enhanced resistance to chemotherapy drugs in comparison with 2D plate cultures. Transfer of extracted cells to the mice caused enhanced tumor volume and decreased life span. This study indicated that collagen–chitosan nanoscaffolds provide a suitable model of tumor that would be appropriate for tumor studies

Dependence of micronuclei assay on the depth of absorbed dose

AimThe purpose of the present study is to investigate the dependence of micronuclei response on the depth of absorbed dose.BackgroundOne of the most common cytogenetic methods used for radiation dosimetry is micronuclei (MN). Being less complex and faster than other methods are two remarkable advantages of the MN method which make it suitable for monitoring of population. In biological dosimetry based on the micronuclei method, the investigation into the dependence of response on the depth in which dose is absorbed is significant, though has received less attention so far.Materials and methodsBlood samples were poured in separate vials to be irradiated at different depths using a linear accelerator system.ResultsAccording to the results, MN, as a function of the absorbed dose, had the best fitness with the linear–quadratic model at all depths. Furthermore, the results showed the dependence of MN response on the depth of absorbed dose. For doses up to 2[[ce:hsp sp="0.25"/]]Gy, the maximum difference from the reference depth of 1.5[[ce:hsp sp="0.25"/]]cm was related to the depth of 10[[ce:hsp sp="0.25"/]]cm; however, by increasing the absorbed dose, the response associated with the depth of 20[[ce:hsp sp="0.25"/]]cm showed the maximum deviation from the reference depth.ConclusionsConsequently, it is necessary to apply a correction factor to the biological dosimetry. The correction factor is dependent on the depth and the absorbed dose

Controlled Auto-Ignition (CAI) combustion in a two-stroke cycle engine using hot burned gases

A new combustion concept, which is viewed increasingly as a probable solution to these issues is Controlled Auto-Ignition (CAI) Combustion. In such an engine, a homogeneous mixture of air, fuel and residual gases is compressed until auto-ignition occurs. Due to its significantly low temperature combustion, NOx will be dramatically reduced while the mixture will be under ultralean fuel-air condition, thus able to achieve high efficiency and low emission. In the case of twostroke engine, problem of poor combustion efficiency and excessive white smoke emission can be addressed by the incorporation some features that will ultimately convert a typical two-stroke engine into an efficient CAI engine demonstrating the best of both features. Due to its inherent high internal residual gas rate in partial load operation, the two-stroke engine has been the first application to benefit from the unconventional CAI combustion process. This paper will concisely discuss the utilization of hot burned gas for induction thus imposing a CAI combustion feature onto two-stroke cycle engine. Among the features incorporated are the increasing in the level of Exhaust gas Recirculation and cycle-by-cycle uniformity of the air-fuel ratio (AFR) supplied to cylinder, which will be crucial in creating a suitable temperature within the engine’s combustion chamber

Experimental investigation of the influence of internal and external EGR on the combustion characteristics of a controlled auto-ignition two-stroke cycle engine

A two-stroke cycle engine incorporated with a controlled auto-ignition combustion approach presents a high thermodynamic efficiency, ultra-low exhaust emissions and high power-to-weight ratio features for future demand of prime movers. The start of auto-ignition, control of the auto-ignition and its cyclic variability, are major concerns that should be addressed in the combustion timing control of controlled auto-ignition engines. Several studies have been performed to examine the effect of internal exhaust gas recirculation utilization on auto-ignited two-stroke cycle engines. However, far too little attention has been devoted to study on the influence of external exhaust gas recirculation on the cyclic variation and the combustion characteristics of controlled auto-ignition two-stroke cycle engines. The purpose of this study is to examine the influence of external exhaust gas recirculation in combination with internal exhaust gas recirculation on the combustion characteristics and the cyclic variability of a controlled auto-ignition two-stroke engine using fuel with different octane numbers. In a detailed experimental investigation, the combustion-related and pressure-related parameters of the engine are examined and statistically associated with the coefficient of variation and the standard deviation. The outcomes of the investigation indicates that the most influential controlled auto-ignition combustion phasing parameters can be managed appropriately via regulating the internal and external exhaust gas recirculation and fuel octane number. In general, start of auto-ignition and its cyclic variability are predominantly affected by external exhaust gas recirculation variation rather than internal exhaust gas recirculation. Furthermore, although the magnitude of low temperature heat release is substantially influenced by external exhaust gas recirculation variation, timing of low temperature heat release is more influenced by internal exhaust gas recirculation approach

A converted two-stroke cycle engine for compression ignition combustion

A new kind of alternative combustion concept that has attracted attention intensively in recent years is called controlled auto-ignition (CAI) combustion. CAI combustion has been proposed and partially implemented with the aim of both improving the thermal efficiency of internal combustion engines, achieving cleaner exhaust emissions and lower cyclic variation. An experimental study is conducted through a CAI two-stroke cycle engine in order to investigate the influence of internal exhaust gas recirculation (In-EGR) and external exhaust gas recirculation (Ex-EGR) variation in relation to combustion cyclic variability and exhaust emissions characteristics. Results implied that cyclic variation of both combustion-related and pressure-related parameter is substantially improved. Furthermore remarkable decreased exhaust emissions, unburned hydrocarbon (uHC), carbon monoxide (CO) and nitric dioxide (NOX), was observed

Influence of hot burned gas utilization on the exhaust emission characteristics of a controlled auto-ignition two-stroke cycle engine

A controlled auto-ignition (CAI) two-stroke cycle engine suggests an exceptional aspect and promising future for internal combustion engines (ICEs), such as a higher power-toweight ratio, higher combustion efficiency and lower exhaust gas emissions. Conventional two-stroke cycle engines emit higher exhaust gas emissions and offer lower fuel saving economy. Most of these drawbacks can be addressed if CAI combustion is associated with a two-stroke cycle engine. An experimental investigation is carried out based on a single-cylinder CAI two-stroke cycle engine using Internal and External Exhaust Gas Recirculation (In-EGR and Ex-EGR) and fuels with different octane numbers to investigate the exhaust emissions characteristics. The experimental results indicate a remarkable improvement in the engine's exhaust gas emissions. The concentration of uHC and CO emissions decreased with application of In/Ex-EGR. However, NOx emission increased with the use of In-EG