Combustion, performance, and emission characteristics of diesel engine using oxyhydrogen gas as a fuel additive.

A lot of research is being carried out to reduce the environmental pollution resulting from compression ignition engines. For this, various gaseous fuels are being explored as fuel additives in compression ignition engines. The purpose of this research work is to investigate rarely explored Brown's gas (oxyhydrogen gas) in CI engines to reduce environmental pollution. Brown's gas was produced by electrolysis of distilled water with potassium hydroxide as a catalyst. A common rail direct injection CI engine was used for the present investigation. Detail combustion, performance, and emission analyses were carried out, which is scarcely reported in oxyhydrogen gas fuel investigations in compression ignition engines. Oxyhydrogen was injected at varying flow rates of 200 ml/min, 400 ml/min, 600 ml/min, and 800 ml/min in the intake manifold of the CI engine equipped with an electronically controlled common rail direct injector. The peak pressure and maximum heat release rate increased with the increasing concentration of oxyhydrogen gas. The comparison was made between conventional diesel combustion and oxyhydrogen gas addition of 800 ml/min at 75% load. The reduction in CO and HC emissions was about 37.5% and 17.94% respectively. CO2 and NOx emissions increased by 9.37% and 7.41% respectively. Very low smoke emission of 0.01 to 0.02% was recorded at 800 ml/min oxyhydrogen gas flow rate. Thus, it can be concluded that oxyhydrogen gas provides promising benefits in terms of better combustion and low emissions. However, it is recommended to carry out further research to incorporate the use of this additive in actual automobile applications.

Cellular Phenotypic Plasticity of Cutaneous Melanoma: A Complex Puzzle.

Wenzina et al. (2020) explore the potential role of E-cadherin (CDH1) as a marker for invasive behavior in melanoma. The authors show that CDH1 expression is modulated by p38 signaling, and that manipulation of this pathway can impede endothelial disruption and lung dissemination in vivo and in vitro. The downstream markers PODXL and DEL of the invasive phenotype are associated with a poor prognosis.

CD34 defines melanocyte stem cell subpopulations with distinct regenerative properties.

Melanocyte stem cells (McSCs) are the undifferentiated melanocytic cells of the mammalian hair follicle (HF) responsible for recurrent generation of a large number of differentiated melanocytes during each HF cycle. HF McSCs reside in both the CD34+ bulge/lower permanent portion (LPP) and the CD34- secondary hair germ (SHG) regions of the HF during telogen. Using Dct-H2BGFP mice, we separate bulge/LPP and SHG McSCs using FACS with GFP and anti-CD34 to show that these two subsets of McSCs are functionally distinct. Genome-wide expression profiling results support the distinct nature of these populations, with CD34- McSCs exhibiting higher expression of melanocyte differentiation genes and with CD34+ McSCs demonstrating a profile more consistent with a neural crest stem cell. In culture and in vivo, CD34- McSCs regenerate pigmentation more efficiently whereas CD34+ McSCs selectively exhibit the ability to myelinate neurons. CD34+ McSCs, and their counterparts in human skin, may be useful for myelinating neurons in vivo, leading to new therapeutic opportunities for demyelinating diseases and traumatic nerve injury.

A direct link between MITF, innate immunity, and hair graying.

Melanocyte stem cells (McSCs) and mouse models of hair graying serve as useful systems to uncover mechanisms involved in stem cell self-renewal and the maintenance of regenerating tissues. Interested in assessing genetic variants that influence McSC maintenance, we found previously that heterozygosity for the melanogenesis associated transcription factor, Mitf, exacerbates McSC differentiation and hair graying in mice that are predisposed for this phenotype. Based on transcriptome and molecular analyses of Mitfmi-vga9/+ mice, we report a novel role for MITF in the regulation of systemic innate immune gene expression. We also demonstrate that the viral mimic poly(I:C) is sufficient to expose genetic susceptibility to hair graying. These observations point to a critical suppressor of innate immunity, the consequences of innate immune dysregulation on pigmentation, both of which may have implications in the autoimmune, depigmenting disease, vitiligo.

17-AAG inhibits vemurafenib-associated MAP kinase activation and is synergistic with cellular immunotherapy in a murine melanoma model.

Heat shock protein 90 (HSP90) is a molecular chaperone which stabilizes client proteins with important roles in tumor growth. 17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of HSP90 ATPase activity, occupies the ATP binding site of HSP90 causing a conformational change which destabilizes client proteins and directs them towards proteosomal degradation. Malignant melanomas have active RAF-MEK-ERK signaling which can occur either through an activating mutation in BRAF (BRAFV600E) or through activation of signal transduction upstream of BRAF. Prior work showed that 17-AAG inhibits cell growth in BRAFV600E and BRAF wildtype (BRAFWT) melanomas, although there were conflicting reports about the dependence of BRAFV600E and BRAFWT upon HSP90 activity for stability. Here, we demonstrate that BRAFWT and CRAF are bound by HSP90 in BRAFWT, NRAS mutant melanoma cells. HSP90 inhibition by 17-AAG inhibits ERK signaling and cell growth by destabilizing CRAF but not BRAFWT in the majority of NRAS mutant melanoma cells. The highly-selective BRAFV600E inhibitor, PLX4032 (vemurafenib), inhibits ERK signaling and cell growth in mutant BRAF melanoma cells, but paradoxically enhances signaling in cells with wild-type BRAF. In our study, we examined whether 17-AAG could inhibit PLX4032-enhanced ERK signaling in BRAFWT melanoma cells. As expected, PLX4032 alone enhanced ERK signaling in the BRAFWT melanoma cell lines Mel-Juso, SK-Mel-2, and SK-Mel-30, and inhibited signaling and cell growth in BRAFV600E A375 cells. However, HSP90 inhibition by 17-AAG inhibited PLX4032-enhanced ERK signaling and inhibited cell growth by destabilizing CRAF. Surprisingly, 17-AAG also stimulated melanin production in SK-Mel-30 cells and enhanced TYRP1 and DCT expression without stimulating TYR production in all three BRAFWT cell lines studied as well as in B16F10 mouse melanoma cells. In vivo, the combination of 17-AAG and cellular immunotherapy directed against Tyrp1 enhanced the inhibition of tumor growth compared to either therapy alone. Our studies support a role for 17-AAG and HSP90 inhibition in enhancing cellular immunotherapy for melanoma.

Characterization of a new, inducible transgenic mouse model with GFP expression in melanocytes and their precursors.

Melanocytes are neural crest-derived cells that are responsible for mammalian hair follicle (HF) pigmentation. The Dct-LacZ transgenic mouse is extensively used to study melanocyte biology but lacks conditionally-inducible labelling and fluorescent labelling, enabling specific, viable isolation of melanocytes using fluorescence-activated cell sorting (FACS). Here, we have generated a Tet-off bitransgenic mouse model, Dct-H2BGFP, containing Dct-tTA and TRE-H2BGFP transgenes. Characterization of Dct-H2BGFP mice confirmed a pattern of Dct-H2BGFP expression in melanoblasts, melanocyte stem cells (McSCs), and terminally differentiated melanocytes similar to the expression pattern of previously published mouse models Dct-LacZ and iDct-GFP. GFP expression is regulated by doxycycline. GFP is shown to co-localize with melanocyte label-retaining cells (LRCs) identified through BrdU retention. The GFP-expressing cells identified in vivo in the bulge and the secondary hair germ of telogen HFs of Dct-H2BGFP mice express the melanocyte and melanocyte stem cell markers Dct and Kit. Using Dct-H2BGFP mice, we separated GFP-expressing cells from the telogen HF based on FACS and showed that GFP-expressing cells express high levels of Kit and Dct, and lower levels of HF epithelial keratin genes. We also show that GFP-expressing cells express high levels of the melanocyte differentiation genes Tyr, Tyrp1, and Pmel17, further substantiating their identity within the melanocyte lineage. Thus, Dct-H2BGFP mice are not only useful for the in vivo identification of melanocytic cells, but also for isolating them viably and studying their molecular and biological properties.

An unusual case of disappearing bone disease in the mandible and literature review.

Disappearing bone disease is a rare disorder that causes spontaneous and progressive osteolysis and proliferation of lymphatic tissue and blood vessels. It is debilitating and there is evidence of mortality in reported cases including those affecting mandible. A 38-year-old man was diagnosed with disappearing bone disease of the mandible in 2013. This had progressed from being in the right ramus only, and now extends to the lower right first molar and affects the left coronoid process and ramus. Mandibular involvement has shown to be high-risk. In older patients, misdiagnosis can occur without thorough investigation, and education of clinicians needs to be paramount to provide the appropriate treatment for this rare condition. The disease can be debilitating and as such education and support of patients is essential.

Expression and function of hypoxia inducible factor-1 alpha in human melanoma under non-hypoxic conditions.

BACKGROUND: Hypoxia inducible factor-1 alpha (HIF-1alpha) protein is rapidly degraded under normoxic conditions. When oxygen tensions fall HIF-1alpha protein stabilizes and transactivates genes involved in adaptation to hypoxic conditions. We have examined the normoxic expression of HIF-1alpha RNA and protein in normal human melanocytes and a series of human melanoma cell lines isolated from radial growth phase (RGP), vertical growth phase (VGP) and metastatic (MET) melanomas. RESULTS: HIF-1alpha mRNA and protein was increased in RGP vs melanocytes, VGP vs RGP and MET vs VGP melanoma cell lines. We also detected expression of a HIF-1alpha mRNA splice variant that lacks part of the oxygen-dependent regulation domain in WM1366 and WM9 melanoma cells. Over-expression of HIF-1alpha and its splice variant in the RGP cell line SbCl2 resulted in a small increase in soft agar colony formation and a large increase in matrigel invasion relative to control transfected cells. Knockdown of HIF-1alpha expression by siRNA in the MET WM9 melanoma cell line resulted in a large decrease in both soft agar colony formation and matrigel invasion relative to cells treated with non-specific siRNA. There is a high level of ERK1/2 phosphorylation in WM9 cells, indicating an activated Ras-Raf-MEK-ERK1/2 MAPK pathway. Treatment of WM9 cells with 30 microM U0126 MEK inhibitor, decreased ERK1/2 phosphorylation and resulted in a decrease in HIF-1alpha expression. However, a 24 h treatment with 10 microM U0126 totally eliminated Erk1/2 phosphorylation, but did not change HIF-1alpha levels. Furthermore, siRNA knockdown of MEK siRNA did not change HIF-1alpha levels. CONCLUSION: We speculate that metabolic products of U0126 decrease HIF-1alpha expression through "off target" effects. Overall our data suggest that increased HIF-1alpha expression under normoxic conditions contributes to some of the malignant phenotypes exhibited by human melanoma cells. The expanded role of HIF-1alpha in melanoma biology increases its importance as a therapeutic target.

Determination of mitochondrial nitric oxide synthase activity.

The main biological targets of nitric oxide (NO) are hemoproteins, thiols, and superoxide anion (O2-). Mitochondria possess several hemoproteins, thiol-containing molecules, and they are one of the prime cellular producers of O2-. Thus, these organelles remain one of the main biological targets for NO. Reports on the existence of a Ca2+-sensitive mitochondrial NO synthase (mtNOS) have opened a new window in the field of NO and mitochondria research (Ghafourifar and Richter, 1997). mtNOS-derived NO reversibly decreases the activity of the mitochondrial hemoprotein, cytochrome c oxidase. This function of mtNOS regulates mitochondrial respiration and transmembrane potential (Deltapsi). The NO generated by mtNOS reacts with mitochondrial thiol-containing proteins including caspase-3. Because the S-nitrosated caspase-3 remains apoptotically silent as long as it is located within the mitochondria, this function of mtNOS portrays an anti-apoptotic property for mtNOS. mtNOS-derived NO also reacts with O2- to generate peroxynitrite. mtNOS-derived peroxynitrite induces oxidative stress and releases cytochrome c from the mitochondria, which represents a pro-apoptotic role for mtNOS. How mitochondria harmonize the reversible functions of mtNOS for mitochondrial respiration, its anti-apoptotic actions via S-nitrosation of caspase-3, versus the pro-apoptotic properties of peroxynitrite remains to be fully understood. However, intramitochondrial ionized Ca2+ concentration ([Ca2+]m) and the status of mitochondrial reducing defense barriers seem to play crucial roles in orchestrating the functions of mtNOS for mitochondria and cells (Ghafourifar and Cadenas, 2005).