Processing of proSAAS in neuroendocrine cell lines

ProSAAS, a recently discovered granin-like protein, potently inhibits prohormone convertase (PC)1, and might also perform additional functions. In the present study, the processing of proSAAS was compared in two neuroendocrine cell lines overexpressing this protein: the AtT-20 mouse pituitary corticotrophic line and the PC12 rat adrenal phaeochromocytoma line. The processing of proSAAS was examined by pulse–chase analysis using [3H]leucine, by MS, and by chromatography and radioimmunoassay. Various smaller forms of proSAAS were detected, including peptides designated as little SAAS, PEN and big LEN. Because the PC-12 cells used in the present study do not express either PC1 or PC2, the finding that these cells efficiently cleave proSAAS indicates that these cleavages do not require either enzyme. Two of the peptides identified in AtT-20 media represent novel C-terminally truncated forms of PEN. In both cell lines, the secretion of the small proSAAS-derived peptides is stimulated by secretagogues. However, long-term treatment of wild-type AtT-20 cells with two different secretagogues (8-bromo-cAMP and a phorbol ester) does not affect levels of proSAAS mRNA; this treatment significantly increases PC1 mRNA by approx. 60–80%. The lack of co-regulation of proSAAS and PC1 mRNA implies that enzyme activity can be induced without an accompanying increase in the inhibitor. In addition, the finding that the peptides are secreted via the regulated pathway is consistent with the proposal that they may function as neuropeptides.

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Pharmacogenetic association between NAT2 gene polymorphisms and isoniazid induced hepatotoxicity: trial sequence meta-analysis as evidence

Bioscience Reports ◽

10.1042/bsr20180845 ◽

2019 ◽

Vol 39 (1) ◽

Cited By ~ 7

Author(s):

Saif Khan ◽

Raju K. Mandal ◽

Abdulbaset Mohamed Elasbali ◽

Sajad A. Dar ◽

Arshad Jawed ◽

...

Keyword(s):

Gene Polymorphisms ◽

Meta Analysis ◽

Term Treatment ◽

Wild Type ◽

Severe Problem ◽

Trial Sequence ◽

Increased Risk ◽

Long Term Treatment ◽

Nat2 Gene

Abstract Hepatotoxicity is a severe problem generally faced by tuberculosis (TB) patients. It is a well-known adverse reaction due to anti-TB drugs in TB patients undergoing long-term treatment. The studies published previously have explored the connection of N-acetyltransferase 2 (NAT2) gene polymorphisms with isoniazid-induced hepatotoxicity, but the results obtained were inconsistent and inconclusive. A comprehensive trial sequence meta-analysis was conducted employing 12 studies comprising 3613 controls and 933 confirmed TB cases using the databases namely, EMBASE, PubMed (Medline) and Google Scholar till December 2017. A significant association was observed with individuals carrying variant allele at position 481C>T (T vs. C: P = 0.001; OR = 1.278, 95% CI = 1.1100–1.484), at position 590G>A (A vs. G: P = 0.002; OR = 1.421, 95% CI = 1.137–1.776) and at position 857G>A (A vs. G: P = 0.0022; OR = 1.411, 95% CI = 1.052–1.894) to higher risk of hepatotoxicity vis-à-vis wild-type allele. Likewise, the other genetic models of NAT2 gene polymorphisms have also shown increased risk of hepatotoxicity. No evidence of publication bias was observed. These results suggest that genetic variants of NAT2 gene have significant role in isoniazid induced hepatotoxicity. Thus, NAT2 genotyping has the potential to improve the understanding of the drug–enzyme metabolic capacity and help in early predisposition of isoniazid-induced hepatotoxicity.

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Opposite Effects of Captopril on Angiotensin I-Converting Enzyme ‘Activity’ and ‘Concentration’; Relation between Enzyme Inhibition and Long-Term Blood Pressure Response

Clinical Science ◽

10.1042/cs0600491 ◽

1981 ◽

Vol 60 (5) ◽

pp. 491-498 ◽

Cited By ~ 71

Author(s):

F. Boomsma ◽

J. H. B. de Bruyn ◽

F. H. M. Derkx ◽

M. A. D. H. Schalekamp

Keyword(s):

Blood Pressure ◽

Enzyme Activity ◽

Inhibitory Effect ◽

Enzyme Concentration ◽

Term Treatment ◽

Converting Enzyme ◽

Control Value ◽

Long Term Treatment

1. The relationship between the antihypertensive action of captopril and its inhibitory effect on angiotensin I(ANG I)-converting enzyme has been investigated. Converting enzyme was measured in plasma by its ability to generate hippuric acid from the synthetic substrate hippuryl-l-histidyl-l-leucine. Inhibition by captopril appeared transient on storage of the plasma samples at −20°C, so that measurements in such samples were not a valid index of the effect in vivo. 2. Rapid reversal of captopril's inhibitory effect on ANG I-converting enzyme in plasma was achieved by the addition of N-ethylmaleimide (0.1 mmol/l). In this way an estimate of converting enzyme ‘concentration’ was obtained both in stored and in freshly prepared plasma samples. Measurements of converting enzyme ‘activity’ in freshly prepared samples, in the absence of N-ethylmaleimide, were used as an index of inhibition in vivo. 3. In eight hypertensive subjects ANG I-converting enzyme ‘concentration’ did not change after a single oral 100 mg dose of captopril. Long-term treatment of 10 hypertensive subjects with captopril was associated with a gradual increase in converting enzyme ‘concentration’ from 29 ± 2 to 47 ± 3 m-units/ml (mean ± sem) over a period of several weeks. In contrast, captopril caused a rapid fall of converting enzyme ‘activity’. 4. Abrupt withdrawal of captopril after long-term treatment caused a gradual decrease in ANG I-converting enzyme ‘concentration’ to the control value. In contrast, converting enzyme ‘activity’ rose rapidly and became equal to enzyme ‘concentration’ 2 days after the drug had been stopped. 5. The concentration of enzymatically active renin in plasma rose from 13 ± 3 to 81 ± 34 μ-units/ml during long-term captopril treatment (mean ± sem). Blood pressure fell from 168 ±4/108 ± 3 to 140 ± 3/90 ± 3 mmHg and had not returned to the control value in the first week after the drug had been stopped, despite the fact that circulating active renin and ANG I-converting enzyme ‘activity’ were elevated. 6. It is concluded that long-term inhibition of ANG I-converting enzyme by captopril is associated with an increased plasma concentration of this enzyme. The results also suggest that the level of converting enzyme ‘activity’ in plasma is not the only factor that determines the long-term effect of captopril on blood pressure.

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Long-term treatment of isolated rat soleus muscle with phorbol ester leads to loss of contraction-induced glucose transport

Biochemical Journal ◽

10.1042/bj2670659 ◽

1990 ◽

Vol 267 (3) ◽

pp. 659-663 ◽

Cited By ~ 15

Author(s):

P J F Cleland ◽

K C Abel ◽

S Rattigan ◽

M G Clark

Keyword(s):

Glucose Transport ◽

Phorbol Ester ◽

Adenine Nucleotide ◽

Term Treatment ◽

Protein Kinase C Activity ◽

Long Term Treatment ◽

Rat Soleus Muscle ◽

Contractile Performance ◽

Isolated Rat

Muscle contraction involves mobilization of intracellular Ca2+ and is associated with several metabolic adjustments, including increased glucose transport. In the present study isolated rat soleus muscles were exposed to 12-O-tetradecanoylphorbol 13-acetate, and responses to both insulin and contraction in terms of glucose transport were assessed. Muscles treated with this phorbol ester for 12 h showed an increased basal rate of 3-O-methylglucose uptake, and responded partially to insulin but did not respond to contraction. Phorbol-ester-treated and non-treated (vehicle-only) muscles were indistinguishable in terms of pre-contraction content of adenine nucleotide, phosphocreatine, lactate and glycogen, as well as contractile performance and contraction-induced glycogenolysis. Phorbol ester treatment of isolated solei for 12 h resulted in the loss of 90% of protein kinase C activity as determined with histone IIIs as substrate, and 70% as determined by using phorbol ester binding. It is concluded that treatment of solei with phorbol ester gives rise to a marked loss of contraction-induced glucose transport.

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Panitumumab – an effective long-term treatment for patients with metastatic colorectal cancer and wild-type KRAS status

Cancer Treatment Reviews ◽

10.1016/s0305-7372(10)70003-7 ◽

2010 ◽

Vol 36 ◽

pp. S15-S16 ◽

Cited By ~ 4

Author(s):

Elena Elez ◽

Maria Alsina ◽

Josep Tabernero

Keyword(s):

Colorectal Cancer ◽

Metastatic Colorectal Cancer ◽

Term Treatment ◽

Wild Type ◽

Kras Status ◽

Long Term Treatment

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Negative Regulation of PTEN by MicroRNA-221 and Its Association with Drug Resistance and Cellular Senescence in Lung Cancer Cells

BioMed Research International ◽

10.1155/2018/7908950 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 5

Author(s):

Ning Wang ◽

Chen Zhu ◽

Ye Xu ◽

Wenliang Qian ◽

Min Zheng

Keyword(s):

Lung Cancer ◽

Drug Resistance ◽

Cancer Cells ◽

Cell Lines ◽

Term Treatment ◽

Lung Cancer Cells ◽

Akt Pathway ◽

Long Term Treatment ◽

Important Regulator

Objective.Chemotherapy is the routine method for treating many cancers, but long-term treatment may result in developing resistance to the drugs. The aim of this study was to identify whether noncoding RNAs play a role in drug resistance and how they affect drug resistance.Materials and Methods.The expression levels of miR-221 in different lung cancer cell lines H226, H1299, and A549 were measured. H1299 and A549 cell lines were transfected to overexpress and downexpress miR-221, and cell viability and cell senescence were determined. The PTEN/Akt pathway was then examined by real-time polymerase chain reaction and Western blot analysis.Results. MiR-221 together with proteins MDR1 and ABCG2 was upregulated in Cisplatin-resistant A549 lung cancer cells. Anti-miR-221 inhibits proliferation and induces senescence in lung cancer cells. PTEN/Akt pathway axis was identified as a target of drug resistance induced by miR-221.Conclusion. Our results revealed that miR-221 is an important regulator for chemotherapy sensitivity and showed miR-221 as a potential target for drug sensitization.

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Tween® Preserves Enzyme Activity and Stability in PLGA Nanoparticles

Nanomaterials ◽

10.3390/nano11112946 ◽

2021 ◽

Vol 11 (11) ◽

pp. 2946

Author(s):

Jason Thomas Duskey ◽

Ilaria Ottonelli ◽

Arianna Rinaldi ◽

Irene Parmeggiani ◽

Barbara Zambelli ◽

...

Keyword(s):

Enzyme Activity ◽

Glycolic Acid ◽

Treatment Options ◽

Plga Nanoparticles ◽

Term Treatment ◽

Titration Calorimetry ◽

Burst Release ◽

Long Term Treatment ◽

Pharmaceutical Molecules

Enzymes, as natural and potentially long-term treatment options, have become one of the most sought-after pharmaceutical molecules to be delivered with nanoparticles (NPs); however, their instability during formulation often leads to underwhelming results. Various molecules, including the Tween® polysorbate series, have demonstrated enzyme activity protection but are often used uncontrolled without optimization. Here, poly(lactic-co-glycolic) acid (PLGA) NPs loaded with β-glucosidase (β-Glu) solutions containing Tween® 20, 60, or 80 were compared. Mixing the enzyme with Tween® pre-formulation had no effect on particle size or physical characteristics, but increased the amount of enzyme loaded. More importantly, NPs made with Tween® 20:enzyme solutions maintained significantly higher enzyme activity. Therefore, Tween® 20:enzyme solutions ranging from 60:1 to 2419:1 mol:mol were further analyzed. Isothermal titration calorimetry analysis demonstrated low affinity and unquantifiable binding between Tween® 20 and β-Glu. Incorporating these solutions in NPs showed no effect on size, zeta potential, or morphology. The amount of enzyme and Tween® 20 in the NPs was constant for all samples, but a trend towards higher activity with higher molar rapports of Tween® 20:β-Glu was observed. Finally, a burst release from NPs in the first hour with Tween®:β-Glu solutions was the same as free enzyme, but the enzyme remained active longer in solution. These results highlight the importance of stabilizers during NP formulation and how optimizing their use to stabilize an enzyme can help researchers design more efficient and effective enzyme loaded NPs.

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