Difference In Inhibition Rate Research Articles

Susceptibility and mechanism of sodium salicylate-induced tinnitus model in low estrogen rats

Objective: The susceptibility of tinnitus rats with low estrogen level induced by sodium salicylate and the changes of tumor necrosis factor α (TNF-α) in serum were observed to investigate the relationship between tinnitus occurrence and estrogen level. Methods: Forty-two healthy female Wistar rats were randomly divided into control group(n=6), normal group(n=6), sham operation group(n=6) and ovariectomized group(n=24). Control group was intraperitoneally injected with normal saline 200 mg/kg for 14 consecutive days. Normal group, sham operation group and ovariectomized group were intraperitoneally injected with sodium salicylate 200 mg/kg for 14 consecutive days. Before and after sodium salicylate induction, the tinnitus behavior of rats in each group was detected by prepulse inhibition (PPI) and gap pre-pulse inhibition of the acoustic startle (GPIAS) test. Before and after sodium salicylate induction, blood samples were collected from eyeballs of rats in each group, and serum levels of estradiol and TNF-α were detected by ELISA. SPSS 25.0 software was used to analyze the data. Results: (1) Following 14 days of sodium salicylate intervention, there was no significant difference in PPI inhibition rate between groups or within groups(all P>0.05). (2)There was no significant difference in the inhibition rate of GPIAS in the four groups before sodium salicylate injection(F=0.217, P>0.05). With sodium salicylate injected for 14 days, the inhibition rate of GPIAS in ovariectomized group (30.88%±15.40%) was significantly lower than that in the other three groups (44.11%±21.06%, 38.27%±10.92%, 51.59%±11.34%), and the difference was statistically significant(F=3.533, P<0.05). The inhibition rate of GPIAS in ovariectomized group with sodium salicylate injected for 14 days was significantly lower than that before injection, and the difference was statistically significant(t=2.977, P<0.05).There was no significant difference in GPIAS inhibition rate between the other three groups before and after sodium salicylate injection(P>0.05). (3)The level of TNF-α in ovariectomized rats was significantly higher than that in the other three groups, the difference was statistically significant(all P<0.05). With sodium salicylate injection for 14 days, TNF-α level in the ovariectomized group increased more significantly than that in the other three groups, the difference was statistically significant(F=8.045, P<0.05). TNF-α levels increased following salicylate injection in normal group, sham operation group and ovariectomized group, and the differences were statistically significant(t value was -4.843, -4.932 and -5.965 respectively, each P<0.05). There was no significant difference in TNF-α levels before and after normal saline injection in control group(all P>0.05). Conclusion: Low estrogen levels increase susceptibility to sodium salicylate-induced tinnitus. Decreased estrogen levels may increase susceptibility to tinnitus through the increased expression of pro-inflammatory factor TNF-α.

Overvalued allelopathy and overlooked effects of humic acid-like substances on Microcystis aeruginosa and Scenedesmus obliquus competition

To form Microcystis blooms, Microcystis must be competitively dominant to other phytoplankton species to produce enough biomass. The aim of this study was to determine the competition mechanisms between Microcystis aeruginosa and Scenedesmus obliquus. M. aeruginosa and S. obliquus were separately cultured in the filtrate of mono and mixed cultures of M. aeruginosa and S. obliquus with varying treatments concerning N, P and iron availability. The inhibition rate for M. aeruginosa was 20–31% when cultured in mono and mixed culture filtrates enriched with N and P, but this rate was reduced to −15 to 19% when cultured in filtrates enriched with N, P and iron. The inhibition rate for M. aeruginosa decreased from 80 to 100% to 11–39% in dialytic filtrates. However, there were no differences in inhibition rate for S. obliquus, regardless of filtrate or dialytic filtrate treatments. The potential allelochemical, 2-butyl-octanol (0.144 mg L−1), was found to have little inhibitory effect to M. aeruginosa or S. obliquus. Thus, previously reported allelopathy to Microcystis would be overestimated. We also report a new mechanism in phytoplankton competition in this study. The phytoplankton secreted humic acid-like substances that can reduce the bioavailability of iron, resulting in the inhibition of other phytoplankton.

Antisense oligodeoxynucleotide against human telomerase reverse transcriptase inhibits the proliferation of Eca-109 esophageal carcinoma cells.

Previous studies have demonstrated that the growth of tumor cells may be inhibited by antisense oligonucleotides (ASODNs) targeted against human telomerase (hTR) or human telomerase reverse transcriptase (hTERT), resulting in antitumor activity in a wide variety of tumors. However, few studies have investigated the effect of hTERT gene-targeted ASODNs on telomerase activity and cell proliferation in human esophageal cancer. In the present study, an MTT assay was used to determine the growth inhibition rate of Eca-109 cells treated with a hTERT-targeted phosphorothioate-ASODN (PS-ASODN). An inverted microscope was used to observe the morphologic changes of the cells following treatment with 5 μM PS-ASODN for 10 days. Telomerase activity was detected using the silver staining semi-quantitative telomeric repeat amplification protocol (TRAP) assay. Following treatment with the PS-ASODN (1–5 μmol/l), the proliferation of the Eca-109 cells was inhibited. The differences in inhibition rate between the PS-ASODN and blank control groups were statistically significant (P<0.05) when the concentration of the PS-ASODN was ≥2 μmol/l, whereas no statistically significant difference was identified between the non-specific-ASODN and blank control groups. The inhibition rate increased gradually as the concentration of the PS-ASODN increased and with time, suggesting that the PS-ASODN inhibited the growth of Eca-109 cells in a concentration-dependent, time-dependent and sequence-specific manner. The growth rate of the cells incubated with the PS-ASODN was reduced compared with that of the control cells. Cells treated with the PS-ASODN became round, suspended and reduced in size. The PS-ASODN was also found to inhibit telomerase activity. The ability of the PS-ASODN to inhibit the telomerase activity and cell proliferation of the Eca-109 cell line suggests that ASODNs have the potential to be novel therapeutic agents for the treatment of esophageal cancer.

Epidermal Growth Factor Receptor Mutations Are Associated with Docetaxel Sensitivity in Lung Cancer

A recent large randomized controlled trial revealed that patients with lung cancer with epidermal growth factor receptor (EGFR) mutations had better prognoses when treated with the EGFR-tyrosine kinase inhibitor, gefitinib, than with cytotoxic chemotherapeutic agents. Lung cancer with EGFR mutations is highly sensitive to EGFR-tyrosine kinase inhibitors. The previous trial implied that EGFR mutations might be predictive of the response to cytotoxic chemotherapy. Forty-six tumor tissue specimens (32 adenocarcinomas and 14 nonadenocarcinomas) were obtained from patients with lung cancer who underwent surgical resection. EGFR mutations were detected using polymerase chain reaction-invader assay. A histoculture drug response assay was used as an in vitro drug sensitivity test. The inhibition rates of cisplatin, docetaxel (DOC), vinorelbine, and gemcitabine were measured. Sensitizing EGFR mutations were detected in samples from 14 patients, all with adenocarcinomas. The inhibition rate of cisplatin in tumors with EGFR mutations (group M) was 34.8 ± 15.5%, which was significantly lower (p = 0.0153) than in wild-type tumors (group W; 46.6 ± 14.0%). The inhibition rate of DOC in group M (18.8 ± 13.4%) was also significantly lower (p = 0.0051) than in group W (35.4 ± 19.1%). There were no significant differences in inhibition rates of gemcitabine and vinorelbine between groups M and W. Inhibition rates of DOC were significantly lower in group M (p = 0.0256) than in group W (32.6 ± 18.4) in samples from patients with adenocarcinoma. The histoculture drug response assay indicated that lung cancers with EGFR mutations were less sensitive to DOC than EGFR wild-type tumors.

Role of bone morhogenetic proteins 4 in the human brain glioma cell line U251

Objective To to investigate the role of bone morhogenetic proteins 4 (BMP4) in the human brain glioma cell line U251. Methods Adriamycin or plasmid of BMP4 was given to U251 cells, and BMP4 siRNA was given to U251 cells which had been given adriamycin for 48 h. Methyl thiazolyl tet-razolium ( MTT) was used to measure the activity of U251 cell growth in control group and treatment group. By the formula (1-Atreatment group/Acontrol group) ×100% , U251 cells growth inhibition rate was calculated. By using reverse transcription-polymerase chain reaction ( RT-PCR) , fluorescence quantitative PCR (FQ-PCR) and Western blotting, the transfection efficiency and the expression of BMP4 were assayed. Results Transfection was proved to be successful by RT-PCR, quantitative fluorescent PCR and Western blotting. Growth inhibition rate of U251 cells which were given BMP4 plasmid was (23.4± 1.1)%, (54.8±1.3)%, (58.8 ±1.6)%,(57.2 ±1.4)%, (56.1±0.9)% at the 0.5, 1.0, 1.5, 2. 0, 2. 5μg/well. There was significant difference in inhibition rate between 0. 5μg/well group and 1.0, 1.5, 2.0, 2.5μg/well groups (P 0.05). After adriamycin was added to U251 cells, the inhibition rate was (45. 2 ± 1. 1) % (P <0. 05 ). After BMP4 siRNA was added to U251 cells which had been given adriamycin , the inhibition rate of cells was (23.1± 2.7) % (P<0.05). Conclusion BMP4 can inhibit the glioma cells U251. BMP4 may be a new target for glioma therapy. Key words: Bone morphogenetic protein 4; Target therapy; Glioma

Stereoselective inhibition of human, mouse, and horse cholinesterases by bambuterol enantiomers

Bambuterol is a chiral carbamate and a selective inhibitor of butyrylcholinesterase (BChE, EC 3.1.1.8). In order to relate bambuterol selectivity and stereoselectivity of BChE and acetylcholinesterase (AChE, EC 3.1.1.7) of different species, we studied the inhibition of human, mouse, and horse BChE, as well as AChE of human and mouse by ( R)- and ( S)-bambuterol. AChE and BChE of all studied species were progressively inhibited by both bambuterol enantiomers, with a preference for the ( R)-bambuterol whose inhibition rate constants were about five times higher than that of ( S)-bambuterol. We observed no significant difference between human and mouse in bambuterol enantiomer BChE inhibition. However, ( R)-bambuterol inhibited horse BChE about 14 times slower than human and mouse BChE, and the inhibition rate for ( S)-bambuterol was about 18 times slower. Although the primary structure of horse BChE differs from the other two species in 15 amino acids, we presumed that differences in inhibition rates could be attributed to threonine at position 69 located close to the peripheral site of BChE. Since BChE inhibition by bambuterol enantiomers was at least 8000 times faster than that of AChE, both bambuterol enantiomers proved to be selective BChE inhibitors, as was previously shown for racemate.

The influence of 2-propanol and acetone on oviposition rate and oviposition site preference for acetic acid and ethanol of Drosophila melanogaster.

Drosophila melanogaster strains, homozygous for the alcohol dehydrogenase alleles AdhF, AdhS, and Adhn4 respectively, were tested for oviposition site preference with a Multiple Choice Device consisting of 18 patches per choice disk. Equal numbers of patches with ethanol-, acetic acid-, and water-supplemented medium were offered simultaneously. Patches with acetic acid-supplemented medium were chosen predominantly as oviposition sites. Pretreatment of flies with increasing concentrations of 2-propanol to inhibit alcohol dehydrogenase (ADH) activity resulted not only in a decreasing choice of acetic acid patches, but also in the laying of a decreasing number of eggs. Adh-null mutant flies showed a similar change in behavior pattern after 2-propanol treatment. Therefore it was concluded that ADH activity is not involved primarily in oviposition site preference behavior. A complicating factor is acetone, the oxidation product of 2-propanol, which had an even larger impact on egg production. However, differences in ADH allozymes with respect to biochemical oxidation capacity of secondary alcohols will not necessarily lead to differences between the Adh genotypes in oviposition rates or apparent changes in preferences, due to additional biochemical differences in inhibition rates by acetone of the various allozymes and other enzyme systems.

The relative molecular mass dependence of the anti-factor Xa properties of heparin.

The effect of heparin fractions of various Mr, with high affinity for antithrombin III, on the kinetics of the reaction between factor Xa and antithrombin III have been studied using purified human proteins. Each of the heparin fractions, which varied between pentasaccharide and Mr 32,000, accelerated the inhibition of factor Xa although an increasing rate of inhibition was observed with increasing Mr. The chemically synthesized pentasaccharide preparation (Mr 1714) gave a maximum inhibition rate constant of 1.2 X 10(7) M-1 X min-1, compared with 6.3 X 10(4) M-1 X min-1 in the absence of heparin, and this rose progressively to 4.2 X 10(8) M-1 X min-1 with the two fractions of highest Mr (22,500 and 32,000). The 35-fold difference in inhibition rates observed with the high-affinity fractions was virtually abolished by the presence of 0.3 M-NaCl. The disparity in these rates of inhibition was shown to be due to a change in the Km for factor Xa when a two-substrate model of heparin catalysis was used. The Km for factor Xa rose from 28 nM for the fraction of Mr 32,000 to 770 nM for the pentasaccharide, whilst 0.3 M-NaCl also caused an increase in Km with the high-Mr fraction. These data suggest that the increased rates of inhibition observed with heparins of higher Mr may be due to an involvement of heparin binding to factor Xa as well as to antithrombin III.

Inhibition of acetylcholinesterase from different species by organophosphorus compounds, carbamates and methylsulphonylfluoride

1. 1. Frog brain acetylcholinesterase (AChE) was more resistant to inhibition by organophosphorus compounds than chicken and rat brain AChE. The differences in inhibition rates were 2 times for soman, 10 times for sarin, tabun and Tx-60, 100 times for DFP, dimethylphosphorylfluoride and paraoxon and 1000 times for diethylphosphorylfluoride. 2. 2. Physostigmine and neostigmine inhibited chicken and rat brain AChE about 100 times faster than frog brain AChE. 3. 3. Chicken and rat brain AChE were inhibited only slightly faster by methylsulphonylfluoride than the frog brain AChE. The inhibition was accelerated by tetraethylammonium ions and retarded by tensilon in all cases. 4. 4. Tetraethylammonium ions, however, slightly retarded the inhibition rate of chicken and rat brain AChE by dimethylphosphorylfluoride. No significant effect was observed for the frog brain AChE. 5. 5. The species differences in inhibition rates were probably not due to differences in phosphorylation rates or conformational changes, but rather to the steric arrangement in the active site of the enzyme molecules.

ESTERASE ISOZYMES OF &lt;i&gt;DROSOPHILA VIRILIS&lt;/i&gt;: PURIFICATION AND PROPERTIES OF α- AND β-ESTERASE ISOZYMES

Thirteen electrophoretic variants of esterases in Drosophila virilis, 9 of which controlled by Esterase-α locus and the others by Esterase-β locus respectively, have been partially purified and characterized biochemically. Enzymes purified by column chromatographic techniques from each stock were free from all other esterases on agar gel electrophoresis but contained a little amount of other proteins. α-esterase utilized both of α- and β-naphthyl acetates at the same extent, while β-esterase did not utilized the α-substrate. Both esterases were more strongly inhibited by DFP than by eserine. PCMB inhibited greatly the activity of α-esterase (80.1% by 10-4M) but not that of β-esterase (7.6% by 10-4M). EDTA did not have any effect on either of α- and β-esterases. The inhibition by PCMB of α-esterase was in part due to the action on -SH group involved in the active center. Generally speaking, the optimal pH of α-esterase was slightly lower than that of β esterase. β-esterase was more unstable than α-esterase by the heat treatment at 60°C. Molecular weight of α-esterase was estimated as 75, 000 and that of β-esterase was as 140, 000 by method of Sephadex gel filtration. Isoallelic variants of the esterases were very similar, there being no significant difference among them in substrate specificity and in molecular weight. However, there were differences in inhibition rates by DFP and PCMB, in optimal pH and in resistibility to treatment at 60°C.

Reactions between alkyl phosphates and acetylcholinesterase from different species

1. 1. There are considerable differences between acetylcholinesterase (AChE) from different species with regard to their reactions with organophosphorous anticholinesterases. AChE from chicken brain was inhibited 20 times as fast with 2-MPAM-ES as rat and mouse brain AChE. In contrast AChE from frog brain was inhibited 1000 times slower with 2-MPAM-ES, 100 times slower with DFP and 10 times slower with 2-MPA-ES than rat brain AChE. 2. 2. The differences in inhibition rates were similar for membrane-bound enzymes and enzymes solubilized by Triton X-100. 3. 3. Both chicken and frog brain AChE were inhibited to the same extent by quaternary ammonium salts. 4. 4. There were only small species differences with regard to reactivation of DFP-inhibited enzymes by 2-PAM. 5. 5. When AChE from the different species were inhibited by DFP, the enzyme from frog brain “aged” 10 times slower than in the other enzymes. 6. 6. Substrate specificity studies showed that chicken brain enzyme exhibited its highest activity towards propionylcholine whereas frog enzyme had the highest activity towards acetylcholine.