Nanoparticles-free fluorescence anisotropy amplification assay for detection of RNA nucleotide-cleaving DNAzyme activity.

Fluorescence anisotropy is a homogeneous, sensitive, ratiometric, and real-time analytical technology. However, it is a great challenge to produce a large fluorescence anisotropy change upon the presence of target small molecules without nanoparticles-dependent amplification. This work reports a nanoparticle-free and multiple G-enhanced fluorescence anisotropy assay for detection of DNAzyme activity. A Pb(2+)-dependent GR-5 DNAzyme was used as a model. We hybridized the rA-cleavable substrate strand containing a TMR label at the 5'-end with the DNAzyme strand containing an extended three G bases at the 3'-end. By this design, we demonstrate that both fluorescence quenching and the enhanced DNAzyme activity contribute to a Pb(2+)-induced large fluorescence anisotropy change (|Δr| = 0.168). The limit of detection for Pb(2+) is estimated to be about 100 pM with a dynamic range from 200 pM to 100 nM. The interference from the other nine divalent metal ions of 1000-times excess amount is negligible. Moreover, we show an extended assay for evaluation of the interactions of Pb(2+) with cysteine and glutathione by the detection of GR5 DNAzyme activity. Collectively, we developed a novel fluorescence anisotropy amplification assay, enabling us to detect DNAzyme activity and associated cofactors and inhibitors and to characterize the Pb(2+)-chelation capability of free thiols.

Effects of different dosages of parathyroid hormone-related protein 1-34 on the bone metabolism of the ovariectomized rat model of osteoporosis.

Intermittent and low-dose parathyroid hormone (PTH) injection to stimulate bone formation has been used in the treatment of osteoporosis. The N-terminal fragment 1-34 of PTH is quite similar in structure and function to N-terminal PTH-related protein (PTHrP). PTH(1-34) and PTHrP also share a coreceptor, the PTH/PTHrP receptor. Therefore, some studies have suggested that PTHrP could effectively stimulate bone formation, similar to PTH. We used an ovariectomized (OVX) rat model of osteoporosis to study the effects of PTHrP(1-34) on bone metabolism by measuring bone mineral density (BMD), bone histomorphometrics, and biomechanical parameters. We found that subcutaneous injection of PTHrP(1-34) (40 or 80 µg/kg body weight every day) in OVX rats increased lumbar and femoral BMD, improved bone biomechanical properties, enhanced bone strength, and promoted bone formation. We selected 40 µg/kg as the preferred therapeutic dose of PTHrP(1-34) and investigated the effects of frequency of treatment (per 1, 2, 3, or 7 days) on bone metabolism in OVX rats. We found that injection of PTHrP(1-34) once per day or every other day significantly improved the BMD and strength of OVX rats. Serum calcium and phosphate levels in all treated rats did not vary significantly from control rats. Based on our results, intermittent low-dose PTHrP(1-34) injection promoted bone formation in OVX rats, suggesting a high potential for therapeutic use in osteoporosis patients.

Real-Time Hemodynamic Changes in the Prefrontal and Bilateral Temporal Cortices During Intradermal Acupuncture for Major Depressive Disorder: A Prospective, Single-Center, Controlled Trial Protocol.

Background: Major depressive disorder (MDD) is highly prevalent, affecting more than 300 million individuals worldwide, and its occurrence may be related to the abnormality of the prefrontal cortex and bilateral temporal cortex. Acupuncture, rooted in the theories of acupoints and meridians, has demonstrated its efficacy in regulating cortical blood flow (CBF) in the brains of MDD patients. As one form of acupuncture, intradermal acupuncture (IA) can alleviate clinical symptoms such as depressive mood and insomnia in MDD patients. However, it remains unknown whether IA will have a specific effect on the prefrontal cortex and bilateral temporal cortex in MDD patients. Methods: In total, 60 participants will be recruited: 20 healthy control participants and 40 MDD patients. All healthy control participants will be allocated to the control group, whereas the 40 MDD patients will be randomly divided into two groups: the gallbladder meridian acupoint (GBA) group and the non-acupoint (NA) group, at a 1:1 allocation ratio. All groups will undergo a one-time IA intervention while their cortical activity is monitored using functional near-infrared spectroscopy (fNIRS). Total hemoglobin, oxygenated hemoglobin, and deoxygenated hemoglobin of the prefrontal and bilateral temporal cortices will be measured by fNIRS during the test procedure. Discussion: This trial aims to use fNIRS to compare real-time hemodynamic changes in the prefrontal and bilateral temporal cortices of healthy individuals and MDD patients during IA. The primary objective is to investigate whether MDD patients exhibit specific real-time responses to IA stimulation in these brain regions. The findings from this study will provide clinical data and a possible theoretical basis for the assumption that stimulation of IA may treat MDD by modulating the relevant brain regions. Trial Registration: The study protocol has been registered in the clinicaltrials.gov with the code NCT05707299.

Cadmium depletes cellular iron availability through enhancing ferroportin translation via iron responsive element.

Cadmium (Cd) is a heavy metal that has detrimental effects on various organs. The widespread contamination of Cd in the environment, crops and food sources poses a severe threat to human health. Acute toxicities of Cd have been extensively investigated; however, the health impact of chronic low­dose exposure to Cd, particularly exposure under non­toxic concentrations, has yet to be elucidated. Furthermore, the toxic threshold of Cd is currently unknown. Ferroportin is the only known iron exporter in vertebrate cells, and it has an essential role in controlling iron egress from cells. To the best of our knowledge, the present study is the first to verify the regulation of ferroportin by Cd. Treatment with low­dose Cd (i.e. at sublethal concentrations, without undermining cell viability) increased the protein expression of ferroportin in macrophages, and this was associated with depleted cellular iron levels. Mechanistic investigations revealed that Cd modulated the ferroportin concentration at the translational level, via the iron responsive element located at the 5'­untranslated region of ferroportin. In conclusion, these data provide evidence for the molecular basis by which Cd alters cellular iron availability through elevating concentrations of ferroportin.

Influence of heat treatment of rayon-based activated carbon fibers on the adsorption of formaldehyde.

The influence of heat treatment of rayon-based activated carbon fibers on the adsorption behavior of formaldehyde was studied. Heat treatment in an inert atmosphere of nitrogen for rayon-based activated carbon fibers (ACFs) resulted in a significant increase in the adsorption capacities and prolongation of breakthrough time on removing of formaldehyde. The effect of different heat-treatment conditions on the adsorption characteristics was investigated. The porous structure parameters of the samples under study were investigated using nitrogen adsorption at the low temperature 77.4 K. The pore size distributions of the samples under study were calculated by density functional theory. With the aid of these analyses, the relationship between structure and adsorption properties of rayon-based ACFs for removing formaldehyde was revealed. Improvement of their performance in terms of adsorption selectivity and adsorption rate for formaldehyde were achieved by heat post-treatment in an inert atmosphere of nitrogen.

Hepcidin deficiency undermines bone load-bearing capacity through inducing iron overload.

Osteoporosis is one of the leading disorders among aged people. Bone loss results from a number of physiological alterations, such as estrogen decline and aging. Meanwhile, iron overload has been recognized as a risk factor for bone loss. Systemic iron homeostasis is fundamentally governed by the hepcidin-ferroportin regulatory axis, where hepcidin is the key regulator. Hepcidin deficiency could induce a few disorders, of which iron overload is the most representative phenotype. However, there was little investigation of the effects of hepcidin deficiency on bone metabolism. To this end, hepcidin-deficient (Hamp1(-/-)) mice were employed to address this issue. Our results revealed that significant iron overload was induced in Hamp1(-/-) mice. Importantly, significant decreases of maximal loading and maximal bending stress were found in Hamp1(-/-) mice relative to wildtype (WT) mice. Moreover, the levels of the C-telopeptide of type I collagen (CTX-1) increased in Hamp1(-/-) mice. Therefore, hepcidin deficiency resulted in a marked reduction of bone load-bearing capacity likely through enhancing bone resorption, suggesting a direct correlation between hepcidin deficiency and bone loss. Targeting hepcidin or the pathway it modulates may thus represent a therapeutic for osteopenia or osteoporosis.

Sublethal exposure of organophosphate pesticide chlorpyrifos alters cellular iron metabolism in hepatocytes and macrophages.

Chlorpyrifos (CPF) is commonly used for agricultural and domestic applications, and its contamination is widely detected in environmental media, and in a broad spectrum of field crops, fruits and vegetables. CPF exposure causes many adverse effects on human health including hepatoxicity, neurotoxicity and endocrine disruption. However, few studies have been conducted thus far to investigate the potential influence of CPF exposure on iron metabolism at concentrations that do not trigger significant cell death. Iron metabolism is concertedly governed by the hepcidin-ferroportin axis, where hepcidin is the central hormone involved in the regulation of iron absorption and release, while ferroportin is the only known iron exporter that functions by iron egress from cells. In the present study, we demonstrated that CPF treatment at a non-toxic concentration greatly enhanced ferroportin gene transcription in human macrophage THP-1 cells. CPF significantly inhibited hepcidin expression in human hepatocyte HepG2 cells. As a result, the intracellular labile iron pool (LIP) was largely reduced in THP-1 and HepG2 cells. The combined data of this study identified a novel finding of CPF that disrupts iron homeostasis by altering ferroportin and hepcidin expression. These findings would be useful in understanding the biological effects of CPF exposure, especially under relatively low and non-toxic doses.

Excess iron undermined bone load-bearing capacity through tumor necrosis factor-α-dependent osteoclastic activation in mice.

Iron overload has been associated with bone mass loss. To elucidate the effects of excess iron on bone metabolism, an iron-overloading mouse model was established by administering iron-dextran at 250 mg/kg to female BALB/c mice. After 4 weeks, the mice were sacrificed and the biomechanical properties of the femurs were examined. The results suggested a notable decrease of the maximal bending stress and the modulus of bending elasticity in the femurs obtained from the excess iron-treated mice compared to the control mice. The levels of the serum osteocalcin, C-telopeptide of type I collagen (CTX-1) and tumor necrosis factor-α (TNF-α) were measured in order to investigate the underlying mechanism responsible for the excess iron-induced bone strength reduction. Overall, the results suggested that iron overload resulted in a marked reduction of bone load-bearing capacity through a TNF-triggered osteoclast differentiation and resorption mechanism.

Estrogen regulates iron homeostasis through governing hepatic hepcidin expression via an estrogen response element.

Iron is essential for the human being, involving in oxygen transport, energy metabolism and DNA synthesis. Iron homeostasis is tightly governed by the hepcidin-ferroportin axis, of which hepcidin is the master regulator. Excess iron is associated with various diseases including osteopenia and osteoporosis, which are closely related to the alternation of the endogenous estrogen level. To verify the biological effect of estrogen on iron metabolism, we established a mouse model of estrogen deficiency by ovariectomy. We demonstrated that the hemoglobin content and serum iron level decreased, whereas the tissue iron level in liver and spleen increased in the ovariectomized mice. Moreover, the transcription of hepatic hepcidin was elevated in ovariectomized mice compared to the control mice. We further demonstrated that there was an estrogen response element (ERE) in the promoter region of the hepcidin gene. The assay using the luciferase reporter system confirmed the existence of a functional ERE in the hepcidin promoter, as the estradiol treatment reduced hepcidin expression in cells transfected with ERE-intact construct, with no response to estradiol in cells transfected with ERE-devoid construct. In conclusion, estrogen greatly contributes to iron homeostasis by regulating hepatic hepcidin expression directly through a functional ERE in the promoter region of hepcidin gene. These findings might help build a better understanding towards the etiology of postmenopausal osteoporosis accompanied by excess tissue iron (such as iron retention of osteoclasts in bone) under estrogen deficiency.

Bone biomechanical and histomorphometrical investment in type 2 diabetic Goto-Kakizaki rats.

This study was performed to characterize the bone metabolism in ten 6-month-old male Goto-Kakizaki (GK) rats, a spontaneous type 2 diabetic model, with ten age- and sex-matched non-diabetic Wistar rats as controls. The femora and the fifth lumbar vertebrae were analyzed by a dual energy X-ray absorptiometry for bone mineral density. Histomorphometrical analyses were performed on the sections from the tibia embedded in methylmethacrylate. Biomechanical characterizations were made by a three-point bending test and a compressive test on the femur and the fifth vertebral body respectively. Compared to the control rats, the bone mineral density was significantly deceased and the histomorphometrical studies showed significantly decreased trabecular bone volume, trabecular thickness and number, osteoid surface and thickness, mineralizing surface, mineral apposition rate and bone formation rate, and also a significant increase in mineralization lag time in the diabetic rats. Strength in both bones and elastic modulus of vertebral body significantly decreased in the diabetic rats as well. In addition, the serum osteocalcin levels were significantly decreased and the serum tartrate-resistant acid phosphatase activity was significantly increased. In conclusion, the 6-month-old GK diabetic rats developed osteopenia with an increased risk of fracture owing to the decreased bone formation, and might be a useful model for unraveling the effects of diabetes on bones independent of obesity frequently seen in the type 2 diabetic patients.