The Effects of Dietary Restriction and Aging on in Vivo and in Vitro Binding of Aflatoxin B_1 to Cellular DNA

Laboratory animals maintained on a reduced calorie but nutritionally adequate diet have extended life spans and lowered incidences of spontaneous and chemically induced cancers compared to ad libitum- fed counterparts. Many of the effects of dietary restriction on laboratory animals have been suggested to be related to a deceleration of the aging process. The inhibition of age-related changes in xenobiotic metabolizing enzyme activities by dietary restriction has previously been reported. Alterations of these enzyme activities may cause changes in metabolic activation of carcinogens and, therefore, carcinogen-DNA binding. DNA-repair capability has also been reported to be enhanced in diet-restricted rats. Using AFB1 as a model carcinogen, we have studied in vivo and in vitro hepatic AFB1 -DNA binding, demonstrating that dietary restriction (60% of ad libitum consumption) may decrease the metabolic activation of AFB1, and subsequently reduce AFB 1-DNA binding. Our preliminary results obtained from the AFB 1-DNA binding experiments in isolated hepatocytes suggest that the observed age-dependent reduction in AFB 1-DNA binding which may be attributed to a loss of metabolic activating capability was delayed in the diet-restricted rats.

Arsenic Induced Inhibition of δ-aminolevulinate DehydrataseActivity in Rat Blood and its Response To Meso2,3-dimercaptosuccinic Acid andMonoisoamyl DMSA

Objective The objective of this study was to investigate arsenic induced changes in blood 8-aminolevulinic acid dehydratase (ALAD) after in vitro and in vivo exposure to this element and its response to co-administration of meso 2,3-dimercaptosuccinic acid (DMSA) and monoisoamyl DMSA (MiADMSA) either individually or in combination. Methods Rat whole blood was exposed to varying concentrations (0.1, 0.2 and 0.5 mmol/L) of arsenic (III) or arsenic (V), to assess their effects on blood ALAD activity. Varying concentrations of MiADMSA and DMSA (0.1,0.5 and 1.0 mmol/L) were also tried in combination to determine its ability to mask the effect of arsenic induced (0.5 mmol/L) inhibition of blood ALAD in vitro. In vitro and in vivo experiments were also conducted to determine the effects of DMSA and MiADMSA either individually or in combination with arsenic, on blood ALAD activity and blood arsenic concentration. Results In vitro experiments showed significant inhibition of the enzyme activity when 0.1-0.5 mmol/L of arsenic (III and V) was used. Treatment with MiADMSA increased ALAD activity when blood was incubated at the concentration of 0.1 mmol/L arsenic (III) and 0.1 mmol/L MiADMSA. No effect of 0.1 mmol/L MiADMSA on ALAD activity was noticed when the arsenic concentration was increased to 0.2 and 0.5 mmol/L. Similarly, MiADMSA at a lower concentration (0.1 mmol/L) was partially effective in the turnover of ALAD activity against 0.5 mmol/L arsenic (III), but at two higher concentrations (0.5 and 1.0 mmol/L) a complete restoration of ALAD activity was observed. DMSA at all the three concentrations (0.1,0.5 and 1.0 mmol/L) was effective in restoring ALAD activity to the normal value. Conclusions The results thus suggest that arsenic has a distinct effect on ALAD activity. Another important toxicological finding of the present study, based on in vivo experiments further suggests that combined administration of DMSA and MiADMSA could be more beneficial for reducing blood ALAD inhibition and blood arsenic concentration than the individual treatment.

Antitumor and off-target effects of cholesterol-conjugated let-7a mimics in an orthotopic hepatocellular carcinoma xenograft nude mouse model

Objective: To explore the antitumor and potential off-target effects of systemically delivered cholesterol-conjugatedlet-7a mimics(Chol-let-7a) and control mimics(Chol-miRCtrl) on hepatocellular carcinomain vivo.Methods: The antitumor effects of two intravenous dosing regimens ofChol-let-7a on heptocellular carcinoma growth were compared using an orthotopic xenograft mouse model. Off-targets were analyzed with histopathological and ultrapathological features of heparenal tissue and cells in theChol-let-7a-, Chol-miRCtrl-, and saline-treated (blank) xenograft mice and normal control mice. Then,let-7a abundance in orthotopic tumors, corresponding paracancerous hepatic tissue, and normal liver tissue from healthy nude mice was examined by reverse transcription-polymerase chain reaction. The distribution ofChol-let-7a andChol-miRCtrl in vivo was examined by whole-animal imaging and frozen-sections observation. The experiments were approved by the Institutional Research Board of Peking Union Medical College Hospital.Results: Continuous treatment withChol-let-7a resulted in tumors that were 35.86% and 40.02% the size of those in theChol-miRCtrl and blank xenograft group (P < 0.01 andP < 0.01, respectively), while intermittent dosing withChol-let-7a resulted in tumors that were 65.42% and 56.66% the size of those in theChol-miRCtrl and the blank control group, respectively (P < 0.05 andP < 0.05). In addition, some histopathological and ultrapathological features were only observed after treatment with the two cholesterol-conjugated molecules, however mild with intermittent dosingChol-let-7a treatment, such as diffuse sinusoidal dilation and edema, primarily around the centrolobular vein in heptic tissues;mild hypercellularity with dilated capillary lumens in the renal tissue;and some organelle abnormalities found in heptic and renal cells. Furthermore, whole-animal imaging showed thatChol-let-7a andChol-miRCtrl were predominantly distributed in the liver, kidney, and bladder regions after injection, and that the concentration ofChol-let-7a andChol-miRCtrl in the kidney and the bladder decreased much slowly in the xenograft animals, especially in theChol-miRCtrl group. Finally, RT-PCR analysis showed thatlet-7a levels were significantly increased in Chol-let-7a-treated xenografts compared withChol-miRCtrl group (P=0.003) and blank xenograft group (P=0.001);however, the level was only equivalent to 50.6% and 40.7% of that in paracancerous hepatic tissue and hepatic tissue in normal mice, respectively.Conclusions: Chol-let-7a, administered either continuously or intermittently, showed effective antitumor efficacy.Chol-let-7a had some off-target effects, such as mild acute hepatitis-like inflammation and non-specific drug-induced kidney injury. The intermittent dosing regimen resulted in less damage than the continuous regimen, while maintaining relatively satisfactory antitumor efficacy, which could be useful for the investigation and possible clinical use of miRNA treatment regimens in the future.

Effect of temperature on noninvasive blood glucose monitoring in vivo using optical coherence tomography-corrigendum

The authors would like to apologize for some mistakes in the letter on Chinese Optics Letters vol. 12, no. 11, page 111701 and wish to make the corrections described below：

Epigenetic and Transcriptional Modulator Potential of Epigallocatechin-3-gallate and Genistein on Fetal Hemoglobin Reactivators Genes

Background:𝛽-hemoglobinopathies are one of the most common recessive genetic diseases worldwide,with limited treatments available,particularly in developed countries where the prevalence is higher.Pharmacological reactivation of Fetal Hemoglobin(HbF)is a promising therapeutic strategy.However,approximately 25%of the patients do not respond to Hydroxyurea(HU),the first and most commonly used HbF inducing agent approved by the FDA.Objective:Here,we performed an in vitro assessment of transcriptional effects induced by natural bioactive compounds,namely Epigallocatechin-3-gallate(EGCG)and genistein(GN)in globin genes(HBA1,HBB,HBG1 and HBG2)in HbF regulators/silencer genes(KLF1,BCL11A,MYB and BGLT3)and in epigenetic regulator genes(DNMT1,DNMT3A,DNMT3B,HDAC1,HDAC2,HDAC3 and HDAC8).Moreover,we evaluated EGCG’s in vivo effects in hematological parameters of healthy volunteers.Methods:K562 cells were exposed for 72 and 96 h to GN and EGCG at 100,250 and 500 ng/mL.Cell proliferation and viability were measured,and transcriptional levels were evaluated by qRT-PCR.For in vivo assay,complete blood count was determined by flow cytometry and HbF level was determined through HPLC in 30 healthy individuals before and after 225 mg EGCG ingestion per day during a 90-day period.Results:Both compounds impact cellular metabolism and proliferation with no cytotoxic effects.Divergent GN and EGCG effects in globin and BGLT3 expression levels suggest the involvement of divergent signaling pathways.As for the epigenetic potential,EGCG particularly affects HDAC2 and HDAC8 transcription,whereas GN signifi-cantly affects expression patterns of methylation and acetylation modulators.HU appears to have time divergent effects,with greater impact in methylation at 72 h(overregulates DNTM3A)while affecting acetylation mostly at 96 h(downregulates HDAC1 and HDAC8).Additionally,in vivo,EGCG demonstrated a modulator effect in hematopoiesis and HbF induction.Conclusion:Our results advocate EGCG and GN with HbF pharmacological reactivation potential and sustain further research as new alternative approaches for𝛽-hemoglobinopathies therapies.