Effect of copper on the photosynthesis and growth of Eichhornia crassipes.

Although copper is essential for plant growth and development and plays an important role in many physiological processes, excess copper, resulting from industrial development and population expansion in the recent decades, leads to environmental pollution and has been a cause of wide concern for the adverse effects on photosynthesis, metabolism and growth of plants. The growth properties (e.g. fresh weight, root length, height), photosynthetic properties (e.g. gas exchange, chlorophyll a fluorescence, chlorophyll content) and the physiological index (e.g. activity of antioxidant enzymes and osmotic regulators) of Eichhornia crassipes were assessed under various Cu2+ concentrations in hydroponic experiments. The growth of E. crassipes was negatively affected by Cu2+ treatments, especially at higher Cu2+ concentrations; the Cu2+ treatments resulted in decreased photosynthesis because of a decrease in leaf chlorophyll content and damage to PSII functions, except the oxygen-evolving complex. The physiological tolerance of E. crassipes to Cu2+ relies on osmotic regulation, anti-lipid peroxidation and improved antioxidant properties. The results indicate that E. crassipes could be considered as a phytoremediation agent for Cu2+ pollution in aquatic environments. However, the benefit of E. crassipes for Cu2+ removal in a highly polluted aquatic environment will be limited, but it will be effective in remediating sites with low pollution (≤5 mg·l-1 ). The present results could provide not only a basis for understanding the effects of pollutants on photosynthesis in plants under heavy metal stress but also provide a basis for choosing plants for phytoremediation.

[Auxiliary pathological diagnosis algorithm based on color moments for frozen-section of thyroid cancer].

Objective: To develop a color-moment based model for frozen-section diagnosis of thyroid lesions, and to evaluate the model's value in the frozen-section diagnosis of thyroid cancer. Methods: In this study, 550 frozen thyroid pathological slides, including malignant and non-malignant cases, were collected from Taizhou Central Hospital (Taizhou University Hospital), China, between June 2018 and January 2020. The 550 digitalized frozen-section slides of thyroid were divided into training set (190 slides), validation set (48 slides), test set A (60 slides) and test set B (252 slides). The tumor regions on the slides of malignant cases in the training and validation sets were labeled by pathologists. The labeling information was then used to train the thyroid frozen-section diagnosis models based on the voting method and those based on the color moment. Finally, the performance of two pathological slide diagnosis models was evaluated using the test set A and test set B, respectively. Result: The classification accuracy of the thyroid frozen-section diagnosis model based on the voting method was 90.0% and 83.7%, using test sets A and B, respectively, while that based on color moments was 91.6% and 90.9%, respectively. For actual frozen-section diagnosis of thyroid cancer, the model developed in this study had higher accuracy and stability. Conclusion: This study proposes a color-moment based frozen-section diagnosis model, which is more accurate than other classification models for frozen-section diagnoses of thyroid cancer.

MiR-375 is epigenetically downregulated due to promoter methylation and modulates multi-drug resistance in breast cancer cells via targeting YBX1.

OBJECTIVE: In this study, we firstly verified how miR-375 is downregulated in breast cancer cells with multi-drug resistance (MDR) and further investigated the regulative effect of miR-375 on Ybx1 expression. MATERIALS AND METHODS: MiR-375 expression and promoter methylation status were studied by retrieving data in NCBI GEO Datasets, qRT-PCR and Methylation-Specific PCR (MSP) assay. Drug sensitivity of the cancer cells was assessed using MTT assay. The binding between miR-375 and YBX1 gene was predicted using Targetscan 7.1 and verified using western blot and dual luciferase assay. RESULTS: MiR-375 is significantly downregulated in both MCF-7/ADM and MCF-7/PTX cells than in MCF-7 cells. MCF-7/ADM and MCF-7/PTX cells had significantly higher level of promoter methylation than MCF-7 cells. 5-AZA-dC treatment significantly reduced the methylation in MCF-7/ADM and MCF-7/PTX cells and increased miR-375 expression. MiR-375 can directly target 3'UTR of YBX1 and thereby decrease its expression in MCF-7/ADM and MCF-7/PTX cells. Both miR-375 overexpression and YBX1 knockdown significantly decreased P-gp expression and increased chemosensitivity of the cancer cells. CONCLUSIONS: MiR-375 is downregulated in MCF-7/ADM and MCF-7/PTX cells, and its downregulation is a result of promoter methylation. MiR-375 can directly target 3'UTR of YBX1 and thereby decrease its expression, which might be an important mechanism of MDR in breast cancer cells.

The role of insulin-like growth factor binding protein-3 in the breast cancer cell response to DNA-damaging agents.

Following exposure to radiation and chemotherapeutic agents, the epidermal growth factor receptor (EGFR) can modulate the repair of DNA double-strand breaks (DSB) by forming protein complexes that include the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). This is one of the key mechanism by which tumors become resistant to DNA-damaging therapies. Our previous studies have shown that insulin-like growth factor binding protein-3 (IGFBP-3) is a substrate for DNA-PKcs, and can transactivate EGFR. We therefore questioned whether IGFBP-3 might interact with the EGFR-DNA-PK complex that regulates the DNA damage response. The aim of this study was to delineate the role of IGFBP-3 in the response of breast cancer cells to DSB-inducing chemotherapeutic agents. In the estrogen receptor-negative breast cancer cell lines MDA-MB-468 and Hs578T, which express IGFBP-3 highly, nuclear localization of EGFR and IGFBP-3 was enhanced by treatment with cytotoxic drugs etoposide or doxorubicin and reduced by the EGFR kinase inhibitor gefitinib. Enhanced association among IGFBP-3, EGFR and DNA-PKcs, following the exposure to DNA-damaging drugs was supported by both co-immunoprecipitation analysis and direct visualization by proximity ligation assay. The activation of DNA-PKcs at Ser2056, DNA repair as measured by a nonhomologous end-joining assay, and the increase in EGFR and DNA-PKcs interaction induced by DNA-damaging agents, were all decreased by IGFBP-3 silencing, suggesting that IGFBP-3 has an obligatory role in the DNA repair response to DNA-damaging therapy. In conclusion, IGFBP-3 co-translocation to the nucleus of breast cancer cells and its formation of a complex with DNA-PKcs and EGFR in response to DNA damage shows its potential involvement in the regulation of DNA repair. This suggests the possibility of a therapeutic approach for sensitizing breast cancer to chemo- or radiotherapy by targeting the DNA repair function of IGFBP-3.

Neurotrophins use the Erk5 pathway to mediate a retrograde survival response.

Growth factors synthesized and released by target tissues promote survival and differentiation of innervating neurons. This retrograde signal begins when growth factors bind receptors at nerve terminals. Activated receptors are then endocytosed and transported through the axon to the cell body. Here we show that the mitogen-activated protein kinase (MAPK) signaling pathways used by neurotrophins during retrograde signaling differ from those used following direct stimulation of the cell soma. During retrograde signaling, endocytosed neurotrophin receptors (Trks) activate the extracellular signal-related protein kinase 5 (Erk5) pathway, leading to nuclear translocation of Erk5, phosphorylation of CREB, and enhanced neuronal survival. In contrast, Erk1/2, which mediates nuclear responses following direct cell body stimulation, does not transmit a retrograde signal. Thus, the Erk5 pathway has a unique function in retrograde signaling. Differential activation of distinct MAPK pathways may enable an individual growth factor to relay information that specifies the location and the nature of stimulation.

EphA receptors regulate growth cone dynamics through the novel guanine nucleotide exchange factor ephexin.

Eph receptors transduce short-range repulsive signals for axon guidance by modulating actin dynamics within growth cones. We report the cloning and characterization of ephexin, a novel Eph receptor-interacting protein that is a member of the Dbl family of guanine nucleotide exchange factors (GEFs) for Rho GTPases. Ephrin-A stimulation of EphA receptors modulates the activity of ephexin leading to RhoA activation, Cdc42 and Rac1 inhibition, and cell morphology changes. In addition, expression of a mutant form of ephexin in primary neurons interferes with ephrin-A-induced growth cone collapse. The association of ephexin with Eph receptors constitutes a molecular link between Eph receptors and the actin cytoskeleton and provides a novel mechanism for achieving highly localized regulation of growth cone motility.

Neurogenin promotes neurogenesis and inhibits glial differentiation by independent mechanisms.

The mechanisms by which neural stem cells give rise to neurons, astrocytes, or oligodendrocytes are beginning to be elucidated. However, it is not known how the specification of one cell lineage results in the suppression of alternative fates. We find that in addition to inducing neurogenesis, the bHLH transcription factor neurogenin (Ngn1) inhibits the differentiation of neural stem cells into astrocytes. While Ngn1 promotes neurogenesis by functioning as a transcriptional activator, Ngn1 inhibits astrocyte differentiation by sequestering the CBP-Smad1 transcription complex away from astrocyte differentiation genes, and by inhibiting the activation of STAT transcription factors that are necessary for gliogenesis. Thus, two distinct mechanisms are involved in the activation and suppression of gene expression during cell-fate specification by neurogenin.

EphB receptors interact with NMDA receptors and regulate excitatory synapse formation.

EphB receptor tyrosine kinases are enriched at synapses, suggesting that these receptors play a role in synapse formation or function. We find that EphrinB binding to EphB induces a direct interaction of EphB with NMDA-type glutamate receptors. This interaction occurs at the cell surface and is mediated by the extracellular regions of the two receptors, but does not require the kinase activity of EphB. The kinase activity of EphB may be important for subsequent steps in synapse formation, as perturbation of EphB tyrosine kinase activity affects the number of synaptic specializations that form in cultured neurons. These findings indicate that EphrinB activation of EphB promotes an association of EphB with NMDA receptors that may be critical for synapse development or function.

[Role of paraventricular nucleus in natriuresis and diuresis induced by volume expansion in rabbits].

In sham-lesioned and paraventricular nucleus (PVN) lesioned rabbits, the peak increases of urine volume (UV) induced by volume expansion (VE) were 0.59+/-0.09 and 0.31+/-0.03 ml/min (P<0.01) respectively, whereas the peak increases of U(Na)V were respectively 66.76+/-6.74 and 36.05+/-3.44 micromol/min (P<0.01). No significant differences were found in the two increases induced by VE between rabbits with intact and those with sham-lesioned PVN. In rabbits with vagotomy there were no changes in the two increases after PVN lesion (P>0.05). In rabbits with renal denervation there was no significant change in natriuretic response after PVN lesion (P>0.05), but lesion of PVN significantly attenuated diuretic response (P<0.02). There were no significant differences in glomerular filtration rate (GFR) and renal plasma flow (RPF) before or after VE between the rabbits with intact and lesioned PVN (P>0.05). These results suggest that PVN is involved in the regulation of natriuresis and diuresis induced by VE, which are mediated by vagal afferent nerve, whereas the renal sympathetic efferent nerve may be involved in natriuretic response.

Rapid nuclear responses to target-derived neurotrophins require retrograde transport of ligand-receptor complex.

Target-derived neurotrophins initiate signals that begin at nerve terminals and cross long distances to reach the cell bodies and regulate gene expression. Neurotrophin receptors, Trks, themselves serve as retrograde signal carriers. However, it is not yet known whether the retrograde propagation of Trk activation reflects movement of Trk receptors from neurites to cell bodies or reflects serial activation of stationary Trk molecules. Here, we show that neurotrophins selectively applied to distal neurites of sensory neurons rapidly induce phosphorylation of the transcription factor cAMP response element-binding protein (CREB) and also cause a slower increase in Fos protein expression. Both nuclear responses require activation of neurotrophin receptors (Trks) at distal nerve endings and retrograde propagation of Trk activation to the nerve cell bodies. Using photobleach and recovery techniques to follow biologically active, green fluorescent protein (GFP)-tagged BDNF receptors (TrkB-GFP) in live cells during retrograde signaling, we show that TrkB-GFP moves rapidly from neurites to the cell bodies. This rapid movement requires ligand binding, Trk kinase activity, and intact axonal microtubules. When they reach the cell bodies, the activated TrkB receptors are in a complex with ligand. Thus, the retrograde propagation of activated TrkB from neurites to cell bodies, although rapid, reflects microtubule-dependent transport of phosphorylated Trk-ligand complexes. Moreover, the relocation of activated Trk receptors from nerve endings to cell bodies is required for nuclear signaling responses. Together, these data support a model of retrograde signaling whereby rapid vesicular transport of ligand-receptor complex from the neurites to the cell bodies mediates the nuclear responses.

Akt promotes cell survival by phosphorylating and inhibiting a Forkhead transcription factor.

Survival factors can suppress apoptosis in a transcription-independent manner by activating the serine/ threonine kinase Akt, which then phosphorylates and inactivates components of the apoptotic machinery, including BAD and Caspase 9. In this study, we demonstrate that Akt also regulates the activity of FKHRL1, a member of the Forkhead family of transcription factors. In the presence of survival factors, Akt phosphorylates FKHRL1, leading to FKHRL1's association with 14-3-3 proteins and FKHRL1's retention in the cytoplasm. Survival factor withdrawal leads to FKHRL1 dephosphorylation, nuclear translocation, and target gene activation. Within the nucleus, FKHRL1 triggers apoptosis most likely by inducing the expression of genes that are critical for cell death, such as the Fas ligand gene.

[Role of spinal alpha adrenoceptor in the inhibition of renal sympathetic nerve activity and natriuresis induced by blood volume expansion in rabbits].

The effect of spinal alpha adrenoceptor blockage on the inhibition of renal sympathetic nerve activity (RSNA) and natriuresis induced by blood volume expansion was investigated in anesthetized and bilateral sinoaortic denervated rabbits. In the groups of rabbits with intrathecal injection of alpha-adrenoceptor blocker phentolamine or artificial cerebrospinal fluid the inhibition of RSNA induced by blood volume expansion were (-25.4 +/- 5.4)% and (-42.5 +/- 5.2)% respectively (P < 0.05). In the groups of rabbits with intrathecal injection of alpha 1 adtenoceptor blocker prazosin or artificial cerebrospinal fluid the inhibition of RSNA induced by blood volume expansion were (-29.3 +/- 6.1)% and (-42.5 +/- 5.2)% respectively (P < 0.05). These results suggested that both spinal alpha and alpha 1 adrenceptor blockage with attenuated the inhibition of RSNA induced by blood volume expansion. The spinal alpha 1 adrenceptor blockage with intrathecal injection of prazosin also attenuated signiticantly the natriuresis and diuresis induced by blood volume expansion (P < 0.05).

[The effect of renal dopamtne receptor blockade on natriuresis induced by volume expansion and intracerebroventricular injection of hypertonic saline in rabbits].

The present study was carried out to study the effects of renal dopamine receptor blockade on natriuresis induced by volume expansion (VE) and intracerebroventricular injection of hypertonic saline (ICHNa) in connexion with the use of dopamine receptor blockers haloperidol (Hal) in anesthetized rabbits. In the VE experiments, Hal group decreases the peak increase of UNa V from control group of 65.0 +/- 15.0 to 19.0 +/- 5.5 mumol/min (P < 0.02). In the ICHNa experiments, the peak increase of UNa V in control and Hal groups were respectively 28.9 +/- 4.6 and 29.0 +/- 5.8 mumol/min (P > 0.50). In the experiments of rabbit with intact renal dopamine receptor, the natriuresis induced by VE+ICHNa was significantly greater than those due to either inducing factor acting alone. Renal dopamine receptor blockade also significantly attenuated the natriuresis induced by VE+ICHNa. These results indicate that renal dopamine receptor blockade significantly attenuated the natriuresis induced by VE or VE+ICHNa, but did not affect the response of ICHNa. In the rabbits with intact renal dopamine receptor, the natriuretic response induced by VE+ICHNa was significantly greater than those response by either inducing factor acting alone.

[The role of brain cholinergic system in renal sodium, potassium and water excretion in rats].

In anesthetized rats intracerebroventricular (i. c. v.) injection of cholinergic agonist carbachol induced significant natriuresis, kaliuresis and diuresis (P < 0.05). Among them, the degree of natriuresis was changed with carbachol in a dose-dependent manner (r = 0.9997, P < 0.05). These responses were completely blocked by cholinergic M receptor antagonist atropine or N receptor antagonist hexamethonium pretreatment. Such effects of carbachol were inhibited in part by pretreatment with adrenergic alpha receptor antagonist phentolamine. These results indicate that the natriuresis, kaliuresis and diuresis induced by i. c. v. injection of carbachol were primarily mediated by both muscarinic and nicotinic receptors in the brain, while the effect was in part mediated secondarily via adrenergic alpha receptor.

[Role of paraventriculo-spinal pathway in the inhibition of renal sympathetic nerve activity induced by blood volume expansion in rabbits].

In anesthetized and bilateral sinoaortic denervated rabbits with either intact or ascorbic acid injected paraventricular nucleus (PVN), the inhibition of renal sympathetic nerve activity (RSNA) induced by blood volume expansion (VE) all decreased by approximately 48%. However, 3-4 h and 3-4 d after kainic acid lesion of PVN, the inhibition of RSNA was attenuated respectively to -28.0 +/- 4.5% and -25.7 +/- 4.1% (P < 0.05) with considerably shortened time course (P < 0.01). Also such inhibition could be significantly attenuated (P < 0.05) by intrathecal injection of vasop ressinergic V1 receptor antagonist in spinal T10-T12 segments. There was no significant difference with the slight and brief increase of mean arterial pressure induced by VE in the control and the experimental group. Thus it can be concluded that the inhibition of RSNA induced by VE is partly mediated by a vagal afferent triggered PVN-spinal pathway.

Titanium nails used in A-V fistulation for hemodialysis in 428 patients.

The 4-year experience in the clinical usage of titanium nails in making internal fistula for hemodialysis in 428 cases (17,829 dialyses) is reported. The results were satisfactory and no obvious complications were found. Being simple in practice and having a high success rate and less complications, this method has been applied at 86 hospitals in China.

[Role of brain cholinergic system on diuresis and natriuresis induced by volume expansion in rats].

The role of brain cholinergic system on diuresis and natriuresis induced by volume expansion was studied in conscious rats. In a series of experiments, the diuretic, natriuretic and kaliuretic responses induced by volume expansion were compared in three groups of conscious rats pretreated respectively with intracerebroventricular (icv) injection of artificial cerebrospinal fluid (ACSF), atropine and hexamethonium. The natriuretic, kaliuretic and diuretic responses induced by volume expansion were much less in the animals with icv injection of atropine than in the control group with injection of ACSF (P less than 0.01). While the group pretreated with icv injection of hexamethonium showed no significant decrease in these responses of volume expansion than that of the control (P greater than 0.05). Volume expansion produced no change in insulin and PAH clearance in both the atropine and the ACSF group. Thus the atropine suppressed diuresis, natriuresis and kaliuresis are independent of changes in GFR and RPF. It is inferred from the results of the present investigation that volume expansion induced diuresis and natriuresis appear to be due to inhibition of water and sodium reabsorption in the renal tubules and regulated by certain brain cholinergic system.

[Effect of electroacupuncture on the urine flow, sodium excretion and potassium excretion in the conscious dog].

Unanesthetized dogs with chronic ureteral and gastric fistulae were infused with 0.8% NaCl solution into the stomach at a constant rate for maintaining a state of saline loading. In these animals, there was a steady renal excretion of water, sodium and potassium. However, after a 20-minute unilateral electroacupuncture of the points corresponding to "Sanyinjao" and "Zhaohai" in human leg as described in Traditional Chinese Medicine caused a marked increase in urine flow and urinary sodium excretion, but had no significant effect on urinary potassium excretion. In another group of normal unanesthetized dogs (without saline loading), the effect of electroacupuncture mentioned above no longer appeared. Owing to the facts that electroacupuncture merely increased the water and sodium excretion of kidneys in saline-loading unanesthetized dogs, and had no effect in normal unanesthetized dogs, it is concluded that the effects of electroacupuncture on the urine flow and sodium excretion in saline-loading unanesthetized dogs is an action of normalization by acupuncture.