scholarly journals Inhibition of Plasmodium sporogonic stages by ivermectin and other avermectins

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Raquel Azevedo ◽  
António M. Mendes ◽  
Miguel Prudêncio
Keyword(s):  
Direct Action ◽  
Inhibitory Effect ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Insecticidal Effect ◽  
Strong Inhibitory Effect ◽  
The Impact ◽  
Shed Light

Abstract Background The transmissible forms of Plasmodium parasites result from a process of sporogony that takes place inside their obligatory mosquito vector and culminates in the formation of mammalian-infective parasite forms. Ivermectin is a member of the avermectin family of endectocides, which has been proposed to inhibit malaria transmission due its insecticidal effect. However, it remains unclear whether ivermectin also exerts a direct action on the parasite’s blood and transmission stages. Methods We employed a rodent model of infection to assess the impact of ivermectin treatment on P. berghei asexual and sexual blood forms in vivo. We then made use of a newly established luminescence-based methodology to evaluate the activity of ivermectin and other avermectins against the sporogonic stages of P. berghei parasites in vitro independent of their role on mosquito physiology. Results Our results show that whereas ivermectin does not affect the parasite’s parasitemia, gametocytemia or exflagellation in the mammalian host, several members of the avermectin family of compounds exert a strong inhibitory effect on the generation and development of P. berghei oocysts. Conclusions Our results shed light on the action of avermectins against Plasmodium transmission stages and highlight the potential of these compounds to help prevent the spread of malaria.

scholarly journals Group IVA Cytosolic Phospholipase A2Regulates the G2-to-M Transition by Modulating the Activity of Tumor Suppressor SIRT2

2015 ◽  
Vol 35 (21) ◽  
pp. 3768-3784 ◽  
Author(s):  
Said Movahedi Naini ◽  
Alice M. Sheridan ◽  
Thomas Force ◽  
Jagesh V. Shah ◽  
Joseph V. Bonventre
Keyword(s):  
Tumor Suppressor ◽  
Cyclin A ◽  
Inhibitory Effect ◽  
Mitotic Entry ◽  
Cytosolic Phospholipase ◽  
Age Related ◽  
Group Iva ◽  
The Impact

The G2-to-M transition (or prophase) checkpoint of the cell cycle is a critical regulator of mitotic entry. SIRT2, a tumor suppressor gene, contributes to the control of this checkpoint by blocking mitotic entry under cellular stress. However, the mechanism underlying both SIRT2 activation and regulation of the G2-to-M transition remains largely unknown. Here, we report the formation of a multiprotein complex at the G2-to-M transitionin vitroandin vivo. Group IVA cytosolic phospholipase A2(cPLA2α) acts as a bridge in this complex to promote binding of SIRT2 to cyclin A-Cdk2. Cyclin A-Cdk2 then phosphorylates SIRT2 at Ser331. This phosphorylation reduces SIRT2 catalytic activity and its binding affinity to centrosomes and mitotic spindles, promoting G2-to-M transition. We show that the inhibitory effect of cPLA2α on SIRT2 activity impacts various cellular processes, including cellular levels of histone H4 acetylated at K16 (Ac-H4K16) and Ac-α-tubulin. This regulatory effect of cPLA2α on SIRT2 defines a novel function of cPLA2α independent of its phospholipase activity and may have implications for the impact of SIRT2-related effects on tumorigenesis and age-related diseases.

scholarly journals Distribution and vulnerability of transcriptional outputs across the genome in Myc-amplified medulloblastoma cells

2021 ◽  
Author(s):  
Rui Yang ◽  
Wenzhe Wang ◽  
Meichen Dong ◽  
Kristen Roso ◽  
Paula Greer ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Tumor Cells ◽  
Target Genes ◽  
De Novo ◽  
Inhibitory Effect ◽  
Nucleotide Synthesis ◽  
High Level ◽  
The Impact

Myc plays a central role in tumorigenesis by orchestrating the expression of genes essential to numerous cellular processes1-4. While it is well established that Myc functions by binding to its target genes to regulate their transcription5, the distribution of the transcriptional output across the human genome in Myc-amplified cancer cells, and the susceptibility of such transcriptional outputs to therapeutic interferences remain to be fully elucidated. Here, we analyze the distribution of transcriptional outputs in Myc-amplified medulloblastoma (MB) cells by profiling nascent total RNAs within a temporal context. This profiling reveals that a major portion of transcriptional action in these cells was directed at the genes fundamental to cellular infrastructure, including rRNAs and particularly those in the mitochondrial genome (mtDNA). Notably, even when Myc protein was depleted by as much as 80%, the impact on transcriptional outputs across the genome was limited, with notable reduction mostly only in genes involved in ribosomal biosynthesis, genes residing in mtDNA or encoding mitochondria-localized proteins, and those encoding histones. In contrast to the limited direct impact of Myc depletion, we found that the global transcriptional outputs were highly dependent on the activity of Inosine Monophosphate Dehydrogenases (IMPDHs), rate limiting enzymes for de novo guanine nucleotide synthesis and whose expression in tumor cells was positively correlated with Myc expression. Blockage of IMPDHs attenuated the global transcriptional outputs with a particularly strong inhibitory effect on infrastructure genes, which was accompanied by the abrogation of MB cells proliferation in vitro and in vivo. Together, our findings reveal a real time action of Myc as a transcriptional factor in tumor cells, provide new insight into the pathogenic mechanism underlying Myc-driven tumorigenesis, and support IMPDHs as a therapeutic vulnerability in cancer cells empowered by a high level of Myc oncoprotein.

Effect of hyperthermia on the viability and proliferative activity of tumor cells

2016 ◽  
Vol 21 (5) ◽  
pp. 250-252
Author(s):  
N. Yu Anisimova ◽  
M. V Kiselevskiy ◽  
Amir G. Abdullaev ◽  
N. V Malakhova ◽  
S. M Sitdikova ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Physiological Activity ◽  
Inhibitory Effect ◽  
In Vivo Studies ◽  
Transformed Cells ◽  
Cell Mortality ◽  
Temperature Exposure ◽  
The Impact

Introduction. Results of the systemic chemotherapy in the peritoneum canceromatosis are unsatisfactory because of poor penetration of anticancer drugs in serous cavities due to the presence ofperitoneal-plasma barrier. One of the possible ways to enhance the action cytostatic agents is the use of chemotherapy and hyperthermia, which, according to some data, has an own cytotoxic effect. The purpose of the study. The study of the effect ofdifferent modes of hyperthermia on the physiological activity of transplantable lines of tumor and non-transformed cells. Results. Analysis of the impact of hyperthermia on the physiological activity of transplantable lines of tumor and the non-transformed cells in vitro and in vivo studies demonstrated that along with the gain in the level and time of the temperature exposure as the degree of damage as tumor cell mortality rate increases. In this study the most effective treatment was as follows: the temperature is above 45°C with the exposure of more than 2 hours, which is difficult to achieve in practice due to the limited tolerance of healthy tissues. Conclusion. With the use of hyperthermia in monoregimen it is not possible to achieve effective levels of the temperature impact, which could hardly have a significant inhibitory effect on tumor cells.

scholarly journals Inhibition of Plasmodium Liver Infection by Ivermectin

2016 ◽  
Vol 61 (2) ◽  
Author(s):  
António M. Mendes ◽  
Inês S. Albuquerque ◽  
Marta Machado ◽  
Joana Pissarra ◽  
Patrícia Meireles ◽  
...  
Keyword(s):  
Control Strategies ◽  
Parasite Development ◽  
Mammalian Host ◽  
Mosquito Vector ◽  
Content Type ◽  
Vector Borne Diseases ◽  
Host Infection ◽  
Liver Infection

ABSTRACT Avermectins are powerful endectocides with an established potential to reduce the incidence of vector-borne diseases. Here, we show that several avermectins inhibit the hepatic stage of Plasmodium infection in vitro. Notably, ivermectin potently inhibits liver infection in vivo by impairing parasite development inside hepatocytes. This impairment has a clear impact on the ensuing blood stage parasitemia, reducing disease severity and enhancing host survival. Ivermectin has been proposed as a tool to control malaria transmission because of its effects on the mosquito vector. Our study extends the effect of ivermectin to the early stages of mammalian host infection and supports the inclusion of this multipurpose drug in malaria control strategies.

MODE OF ACTION OF CLOMIPHENE

1969 ◽  
Vol 60 (4) ◽  
pp. 635-644 ◽  
Author(s):  
J. Hammerstein
Keyword(s):  
Mode Of Action ◽  
Specific Activity ◽  
Direct Action ◽  
Clomiphene Citrate ◽  
Inhibitory Effect ◽  
Isotopic Dilution ◽  
Corpora Lutea ◽  
Isolation And Purification

ABSTRACT The in vitro influence of clomiphene citrate on the incorporation of acetate-1-14C into progesterone by slices of human corpora lutea was studied in 10 experiments using the reverse isotopic dilution technique for the isolation and purification of radioactive progesterone, followed in most instances by crystallization to constant specific activity. As a clear-cut and reproducible result, the formation of progesterone from labelled acetate was considerably diminished in the presence of clomiphene citrate independent of whether the tissues originated from the menstrual cycle or from normal as well as ectopic pregnancies. This inhibitory effect on the biosynthesis of progesterone was intensified by increasing the concentration of clomiphene in the medium. It was demonstrable after 13.3 minutes of incubation as well as after 6 hours. No obvious interference of clomiphene with the stimulating action of HCG on steroidogenesis was found. These findings point to a direct action of clomiphene on the ovary which might also have some bearing on the mode of action of clomiphene in vivo.

Inhibition of gastric H+ secretion, K+-ATPase and K+-phosphatase by estradiol in vivo and in vitro

1982 ◽  
Vol 60 (5) ◽  
pp. 680-684 ◽  
Author(s):  
L. Limlomwongse ◽  
P. Piyachaturawat
Keyword(s):  
Gastric Mucosa ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Enzyme Activities ◽  
Direct Action ◽  
Inhibitory Effect ◽  
Secretory Rate ◽  
Dose Dependent

The effect of estrogen on the gastric acid secretion and H+-transporting enzymes, K+ -ATPase and K+-phosphatase, were investigated in the rat. The maximum H+ secretory rate in response to 1 mM histamine was significantly reduced (P < 0.05) in both the isolated gastric mucosa obtained from the rats treated with estradiol in vivo for 7 days and the mucosa directly incubated in vitro with estradiol. The inhibitory effect on the gastric enzyme activities in vitro showed a dose-dependent pattern of a noncompetitive type. The result suggested that estradiol may have a direct action on the gastric H+ secretion by inhibiting the H+ transport enzyme activities.

scholarly journals In vivo activity of glutaminase in the brain of hyperammonaemic rats measured by 15N nuclear magnetic resonance

1995 ◽  
Vol 305 (1) ◽  
pp. 329-336 ◽  
Author(s):  
K Kanamori ◽  
B D Ross
Keyword(s):  
Brain Homogenate ◽  
Inhibitory Effect ◽  
Intact Brain ◽  
Strong Inhibitory Effect ◽  
Glutamine Synthesis ◽  
Gaba Synthesis ◽  
The Brain

The in vivo activity of phosphate-activated glutaminase (PAG) was measured in the brain of hyperammonaemic rat by 15N n.m.r. Brain glutamine was 15N-enriched by intravenous infusion of 15NH4+ until the concentration of [5-15N]glutamine reached 6.1 mumol/g. Further glutamine synthesis was inhibited by intraperitoneal injection of methionine-DL-sulphoximine, an inhibitor of glutamine synthetase, and the infusate was changed to 14NH4+ during observation of decrease in brain [5-15N]glutamine due to PAG and other glutamine utilization pathways. Progressive decrease in brain [5-15N]glutamine, PAG-catalysed production of 15NH4+ and its subsequent assimilation into glutamate by glutamate dehydrogenase were monitored in vivo by 15N n.m.r. Brain [5-15N]glutamine (15N enrichment of 0.35-0.50) decreased at a rate of 1.2 mumol/h per g of brain. The in vivo PAG activity, determined from the observed rate and the quantity of 15NH4+ produced and subsequently assimilated into glutamate and aspartate, was 0.9-1.3 mumol/h per g. This activity is less than 1.1% of the reported activity in vitro measured in rat brain homogenate at a 10 mM concentration of the activator Pi. Inhibition by ammonia (brain level 1.4 mumol/g) alone does not account for the observed low activity in vivo. The result strongly suggests that, in intact brain, PAG activity is maintained at a low level by a suboptimal in situ concentration of Pi and the strong inhibitory effect of glutamate. The observed PAG activity in vivo is lower than the reported in vivo activity of glutamate decarboxylase which converts glutamate into gamma-aminobutyrate (GABA). The result suggests that PAG-catalysed hydrolysis of glutamine is not the sole provider of glutamate used for GABA synthesis.

scholarly journals Corynebacterium Species Inhibit Streptococcus pneumoniae Colonization and Infection of the Mouse Airway

2022 ◽  
Vol 12 ◽  
Author(s):  
Kadi J. Horn ◽  
Alexander C. Jaberi Vivar ◽  
Vera Arenas ◽  
Sameer Andani ◽  
Edward N. Janoff ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Respiratory Health ◽  
Upper Airway ◽  
Inhibitory Effect ◽  
Airway Microbiome ◽  
The Stability ◽  
Independent Effects ◽  
The Impact

The stability and composition of the airway microbiome is an important determinant of respiratory health. Some airway bacteria are considered to be beneficial due to their potential to impede the acquisition and persistence of opportunistic bacterial pathogens such as Streptococcus pneumoniae. Among such organisms, the presence of Corynebacterium species correlates with reduced S. pneumoniae in both adults and children, in whom Corynebacterium abundance is predictive of S. pneumoniae infection risk. Previously, Corynebacterium accolens was shown to express a lipase which cleaves host lipids, resulting in the production of fatty acids that inhibit growth of S. pneumoniae in vitro. However, it was unclear whether this mechanism contributes to Corynebacterium-S. pneumoniae interactions in vivo. To address this question, we developed a mouse model for Corynebacterium colonization in which colonization with either C. accolens or another species, Corynebacterium amycolatum, significantly reduced S. pneumoniae acquisition in the upper airway and infection in the lung. Moreover, the lungs of co-infected mice had reduced pro-inflammatory cytokines and inflammatory myeloid cells, indicating resolution of infection-associated inflammation. The inhibitory effect of C. accolens on S. pneumoniae in vivo was mediated by lipase-dependent and independent effects, indicating that both this and other bacterial factors contribute to Corynebacterium-mediated protection in the airway. We also identified a previously uncharacterized bacterial lipase in C. amycolatum that is required for inhibition of S. pneumoniae growth in vitro. Together, these findings demonstrate the protective potential of airway Corynebacterium species and establish a new model for investigating the impact of commensal microbiota, such as Corynebacterium, on maintaining respiratory health.

scholarly journals BIOL-10. DISTRIBUTION AND VULNERABILITY OF TRANSCRIPTIONAL OUTPUTS ACROSS THE GENOME IN MYC-AMPLIFIED MEDULLOBLASTOMA CELLS

2021 ◽  
Vol 23 (Supplement_1) ◽  
pp. i5-i5
Author(s):  
Rui Yang ◽  
Wenzhe Wang ◽  
Meichen Dong ◽  
Kristen Roso ◽  
Xuhui Bao ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Target Genes ◽  
De Novo ◽  
Inhibitory Effect ◽  
Nucleotide Synthesis ◽  
Expression Of Genes ◽  
High Level ◽  
The Impact

Abstract Myc plays a central role in tumorigenesis by orchestrating the expression of genes essential to numerous cellular processes. While it is well established that Myc functions by binding to its target genes to regulate their transcription, the distribution of the transcriptional output across human genome in Myc-amplified cancer cells, and the susceptibility of such transcriptional outputs to therapeutic interferences remain to be fully elucidated. Here, we analyze the distribution of transcriptional outputs in Myc-amplified medulloblastoma (MB) cells by profiling nascent total RNAs within a temporal context. This profiling reveals a major portion of transcriptional action in these cells was directed at the genes fundamental to cellular infrastructures, including rRNAs and particularly those in the mitochondrial genome (mtDNA). Notably, even when Myc protein was depleted by as much as 80%, the impact on transcriptional outputs across the genome was limited, with notable reduction mostly in genes of involved in ribosomal biosynthesis, genes residing in mtDNA or encoding mitochondria-localized proteins, and those encoding histones. In contrast to the limited direct impact of Myc depletion, we found that the global transcriptional outputs were highly dependent on the activity of Inosine Monophosphate Dehydrogenases (IMPDHs), rate limiting enzymes for de novo guanine nucleotide synthesis and whose expression in tumor cells was positively correlated with Myc’s expression. Blockage of IMPDHs attenuated the global transcriptional outputs with a particularly strong inhibitory effect on the aforementioned infrastructure genes, which was accompanied by the abrogation of MB cell’s proliferation in vitro and in vivo. Together, our findings reveal a real time action of Myc as a transcriptional factor in tumor cells, gain new insight into the pathogenic mechanism underlying Myc-driven tumorigenesis, and support IMPDHs as a therapeutic vulnerability in MB cells empowered by a high level of Myc oncoprotein.

Impact of mTOR Inhibition on FoxP3+ Regulatory T Cells as Compared to Conventional T Cells after Allogeneic Bone Marrow Transplantation.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 448-448 ◽  
Author(s):  
Robert Zeiser ◽  
Dennis B. Leveson-Gower ◽  
Elizabeth A. Zambricki ◽  
Jing-Zhou Hou ◽  
Robert Negrin
Keyword(s):  
Clinical Trials ◽  
T Cells ◽  
Regulatory T Cells ◽  
Allogeneic Bone Marrow Transplantation ◽  
Inhibitory Effect ◽  
Allogeneic Bone ◽  
Mtor Inhibition ◽  
The Impact

Abstract FoxP3+CD4+CD25+ regulatory T-cells (Treg) have been shown to effectively reduce the severity of experimental acute graft-versus-host disease (aGvHD) while sparing graft-versus-leukemia activity. These findings, in concert with the observation that human and murine Treg share functional characteristics, have fueled interest in clinical trials to control aGvHD. Recent data indicates that the immunosuppressant rapamycin (RAPA) in contrast to cyclosporine A does not interfere with in vivo function of Treg and could enhance Treg expansion in vitro by a yet unknown mechanism. To investigate the impact of mTOR inhibition on proliferating Treg and Tconv, both cell types were exposed to CD3/CD28 Mabs in the presence of different RAPA concentrations in vitro. Phosphorylation of mTOR downstream products p70S6K1 and 4E-BP1 were assessed by western blot and flow cytometry. Inhibition of the phosphorylation of p70S6K1 and 4E-BP1 was observed in both populations in the presence of RAPA. Interestingly, Treg were more resistant to mTOR inhibition as compared to Tconv and displayed significantly higher phosphorylated products in the presence of RAPA at 10 nM (MFI Treg vs Tconv, p&lt;0.001) and at 100nM (MFI Treg vs Tconv, p&lt;0.001). To investigate whether Treg and RAPA protect from aGvHD in a synergistic manner, BALB/c recipients were transplanted with H-2 disparate BM and 1.6x10e6 T-cells (FVB/N) after lethal irradiation (8 Gy). aGvHD lethality was only slightly reduced when suboptimal Tconv:Treg ratios were employed (4:1, 8:1), or when recipients were treated with a non-protective RAPA dose (0.5 mg/kg bodyweight). Combining a suboptimal Tconv:Treg ratio with a non-protective RAPA dose reduced expansion of luciferase expressing (luc+) Tconv and pro-inflamatory cytokines and improved survival indicative for an additive in vivo effect of RAPA and Treg. To evaluate the impact of RAPA on in vivo T cell expansion, either luc+ Tconv or luc+ Treg were adoptively transferred. In vivo bioluminescence imaging demonstrated that RAPA had a more potent inhibitory effect on proliferation of Tconv as compared to Treg (p&lt;0.05 vs. NS). We did not observe RAPA to increase FoxP3+ Treg numbers in vivo, or to enhance GITR or CTLA-4 expression. Thus, increased Treg numbers observed in RAPA containing expansion cultures are likely due to a lower susceptibility of this cell population to mTOR inhibition. This could explain the observed synergistic effect of RAPA and Treg in aGvHD protection which has relevance for clinical trials utilizing Treg to prevent aGvHD.

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