scholarly journals The Alternative Route to Heme in the Methanogenic ArchaeonMethanosarcina barkeri

Archaea ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Melanie Kühner ◽  
Kristin Haufschildt ◽  
Alexander Neumann ◽  
Sonja Storbeck ◽  
Judith Streif ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Feedback Regulation ◽  
Methanosarcina Barkeri ◽  
Heme Biosynthesis ◽  
Alternative Route ◽  
Activity Assay ◽  
Enzyme Activity Assay ◽  
Living Organisms

In living organisms heme is formed from the common precursor uroporphyrinogen III by either one of two substantially different pathways. In contrast to eukaryotes and most bacteria which employ the so-called “classical” heme biosynthesis pathway, the archaea use an alternative route. In this pathway, heme is formed from uroporphyrinogen III via the intermediates precorrin-2, sirohydrochlorin, siroheme, 12,18-didecarboxysiroheme, and iron-coproporphyrin III. In this study the heme biosynthesis proteins AhbAB, AhbC, and AhbD fromMethanosarcina barkeriwere functionally characterized. Using anin vivoenzyme activity assay it was shown that AhbA and AhbB (Mbar_A1459 and Mbar_A1460) together catalyze the conversion of siroheme into 12,18-didecarboxysiroheme. The two proteins form a heterodimeric complex which might be subject to feedback regulation by the pathway end-product heme. Further, AhbC (Mbar_A1793) was shown to catalyze the formation of iron-coproporphyrin IIIin vivo. Finally, recombinant AhbD (Mbar_A1458) was produced inE. coliand purified indicating that this protein most likely contains two [4Fe-4S] clusters. Using anin vitroenzyme activity assay it was demonstrated that AhbD catalyzes the conversion of iron-coproporphyrin III into heme.

scholarly journals Celecoxib Blocks Vasculogenic Mimicry via an Off-Target Effect to Radiosensitize Lung Cancer Cells: An Experimental Study

2021 ◽  
Vol 11 ◽  
Author(s):  
Kai Niu ◽  
Xie-Wan Chen ◽  
Yu Qin ◽  
Lu-Ping Zhang ◽  
Rong-Xia Liao ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Enzyme Activity ◽  
Periodic Acid ◽  
Vasculogenic Mimicry ◽  
Lewis Lung Cancer ◽  
Enzyme Activity Assay ◽  
Cox 2 ◽  
Target Effect

The resistance to radiotherapy in lung cancer can be attributed to vasculogenic mimicry (VM) to some extent. Celecoxib (CXB), a selective inhibitor of cyclooxygenase-2 (COX-2), is reported as a radiosensitizer in non-small cell lung cancer (NSCLC). However, whether CXB can regulate VM formation via an off-target effect to radiosensitize NSCLC remains unclear. This study aimed to elucidate the mechanism underlying the radiosensitizing effect of CXB on NSCLC, i.e., whether CXB can inhibit VM formation via binding to newly identified targets other than COX-2. CXB radiosensitivity assay was performed in BALB/c mice bearing H460 xenografts and C57 mice bearing Lewis lung cancer (LLC) xenografts, which were divided into the control, CXB, irradiation (IR) treatment, and IR plus CXB groups. VM formation was observed using 3D Matrigel, periodic acid solution (PAS) staining, and immunofluorescence staining. The potential off-targets of CXB were screened using Protein Data Bank (PDB) database, MGLTools 1.5.6, and AutoDock Vina 1.1.2 and confirmed by Western blotting, enzyme activity assay, and RNA interference in vitro experiments and by immunohistochemistry in vivo experiments. CXB treatment almost eliminated the enhancement of VM formation by IR in vitro and in vivo, partially due to COX-2 inhibition. Four potential off-targets were predicted by molecular docking. Among them, aminopeptidase N (APN) and integrin alpha-V (ITAV) were remarkably inhibited in protein expression and enzyme activity in vitro or in vivo, consistent with the remarkable reduction of VM formation in H460 xenografts in BALB/c mice. In conclusion, CXB dramatically blocked VM through inhibiting newly identified off-targets APN and ITAV, other than COX-2, then radiosensitizing NSCLC.

Expression and Enzyme Activity Assay of pfu with Molecular Chaperone

2010 ◽  
Vol 31 (6) ◽  
pp. 499-503
Author(s):  
Hai-Jun ZHANG ◽  
Jun YANG ◽  
Xiao-Guang LIU ◽  
Xiang-Yang HU
Keyword(s):  
Enzyme Activity ◽  
Molecular Chaperone ◽  
Activity Assay ◽  
Enzyme Activity Assay

Current Challenges in the Development of Vaccines and Drugs Against Emerging Vector-borne Diseases

2019 ◽  
Vol 26 (16) ◽  
pp. 2974-2986 ◽  
Author(s):  
Kwang-sun Kim
Keyword(s):  
New Host ◽  
In Vivo Models ◽  
Vector Borne Diseases ◽  
Novel Drugs ◽  
Huge Impact ◽  
Tick Borne Disease ◽  
Vector Borne ◽  
Living Organisms

Vectors are living organisms that transmit infectious diseases from an infected animal to humans or another animal. Biological vectors such as mosquitoes, ticks, and sand flies carry pathogens that multiply within their bodies prior to delivery to a new host. The increased prevalence of Vector-Borne Diseases (VBDs) such as Aedes-borne dengue, Chikungunya (CHIKV), Zika (ZIKV), malaria, Tick-Borne Disease (TBD), and scrub typhus has a huge impact on the health of both humans and livestock worldwide. In particular, zoonotic diseases transmitted by mosquitoes and ticks place a considerable burden on public health. Vaccines, drugs, and vector control methods have been developed to prevent and treat VBDs and have prevented millions of deaths. However, development of such strategies is falling behind the rapid emergence of VBDs. Therefore, a comprehensive approach to fighting VBDs must be considered immediately. In this review, I focus on the challenges posed by emerging outbreaks of VBDs and discuss available drugs and vaccines designed to overcome this burden. Research into promising drugs needs to be upgraded and fast-tracked, and novel drugs or vaccines being tested in in vitro and in vivo models need to be moved into human clinical trials. Active preventive tactics, as well as new and upgraded diagnostics, surveillance, treatments, and vaccination strategies, need to be monitored constantly if we are to manage VBDs of medical importance.

scholarly journals Prolactin and Male Fertility: The Long and Short Feedback Regulation

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
M. K. Gill-Sharma
Keyword(s):  
Chromatin Condensation ◽  
Feedback Regulation ◽  
Pituitary Hormones ◽  
Feedback Mechanism ◽  
Reproductive Hormones ◽  
Male Rats ◽  
Normal Men

In the last 20 years, a pituitary-hypothalamus tissue culture system with intact neural and portal connections has been developed in our lab and used to understand the feedback mechanisms that regulate the secretions of adenohypophyseal hormones and fertility of male rats. In the last decade, several in vivo rat models have also been developed in our lab with a view to substantiate the in vitro findings, in order to delineate the role of pituitary hormones in the regulation of fertility of male rats. These studies have relied on both surgical and pharmacological interventions to modulate the secretions of gonadotropins and testosterone. The interrelationship between the circadian release of reproductive hormones has also been ascertained in normal men. Our studies suggest that testosterone regulates the secretion of prolactin through a long feedback mechanism, which appears to have been conserved from rats to humans. These studies have filled in a major lacuna pertaining to the role of prolactin in male reproductive physiology by demonstrating the interdependence between testosterone and prolactin. Systemic levels of prolactin play a deterministic role in the mechanism of chromatin condensation during spermiogenesis.

Metabolic importance of Na+/K+-ATPase activity during sea urchin development.

1997 ◽  
Vol 200 (22) ◽  
pp. 2881-2892 ◽  
Author(s):  
P Leong ◽  
D Manahan
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Sea Urchin ◽  
Sodium Pump ◽  
Sea Water ◽  
Strongylocentrotus Purpuratus ◽  
Lytechinus Pictus ◽  
Stimulation Of

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

scholarly journals A Review on the Enhancement of Calcium Phosphate Cement with Biological Materials in Bone Defect Healing

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3075
Author(s):  
Sok Kuan Wong ◽  
Yew Hoong Wong ◽  
Kok-Yong Chin ◽  
Soelaiman Ima-Nirwana
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphate Cement ◽  
Research Effort ◽  
Biological Materials ◽  
Biological Properties ◽  
Comprehensive Overview ◽  
Bone Defect Healing ◽  
Living Organisms

Calcium phosphate cement (CPC) is a promising material used in the treatment of bone defects due to its profitable features of self-setting capability, osteoconductivity, injectability, mouldability, and biocompatibility. However, the major limitations of CPC, such as the brittleness, lack of osteogenic property, and poor washout resistance, remain to be resolved. Thus, significant research effort has been committed to modify and reinforce CPC. The mixture of CPC with various biological materials, defined as the materials produced by living organisms, have been fabricated by researchers and their characteristics have been investigated in vitro and in vivo. This present review aimed to provide a comprehensive overview enabling the readers to compare the physical, mechanical, and biological properties of CPC upon the incorporation of different biological materials. By mixing the bone-related transcription factors, proteins, and/or polysaccharides with CPC, researchers have demonstrated that these combinations not only resolved the lack of mechanical strength and osteogenic effects of CPC but also further improve its own functional properties. However, exceptions were seen in CPC incorporated with certain proteins (such as elastin-like polypeptide and calcitonin gene-related peptide) as well as blood components. In conclusion, the addition of biological materials potentially improves CPC features, which vary depending on the types of materials embedded into it. The significant enhancement of CPC seen in vitro and in vivo requires further verification in human trials for its clinical application.

scholarly journals Antiparasitary Activity Of The Juglone Compound: A Narrative Review

2021 ◽  
pp. 13
Author(s):  
◽  
Keyword(s):  
Mortality Rate ◽  
Leishmania Donovani ◽  
Inhibitory Concentration ◽  
Narrative Review ◽  
Hymenolepis Nana ◽  
Compound A ◽  
Living Organisms ◽  
Nanomolar Range

Objective: To report, based on the literature, the action of the compound 5-hydroxy-1,4-naphthoquinone against parasites (protozoa and helminths) that affect humans. Methods: This is a narrative review that used Pubmed and Google Scholar as a data tool. This work included articles published until September 2020 that were directly related to the use of the compound juglone in antiparasitic trials. Results: The compound juglone demonstrated promising effects as a human and animal antiparasitic substance. In protozoa, the Apicomplexo Toxoplasma gondii parasite showed a high mortality rate in concentrations of juglone in the nanomolar range. The juglone showed an average inhibitory concentration (IC50) of 1.62 µM, >100 µM, and 2.02 µM µM for Trypanosoma cruzi, T. brucei rhodesiense, and Leishmania donovani, respectively. Also, the juglone showed antihelmintic activity on Hymenolepis nana in mice, and on adult worms of Schistosoma mansoni (LE strain) with IC50 34.16 µM, 32.14 µM, and 25 µM in the 24h, 48h, and 72 h, respectively. Conclusion: The results published so far show the in vitro antiparasitic potential of juglone, and the need for further studies on the specific mode of action that interacts with parasites. Besides, the literature is still limited to studies that evaluate in vivo the compound juglone, requiring better information on its interaction with living organisms.

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