ZMK1 Is Involved in K+ Uptake and Regulated by Protein Kinase ZmCIPK23 in Zea mays

Potassium (K+) is one of essential mineral elements for plant growth and development. K+ channels, especially AKT1-like channels, play crucial roles in K+ uptake in plant roots. Maize is one of important crops; however, the K+ uptake mechanism in maize is little known. Here, we report the physiological functions of K+ channel ZMK1 in K+ uptake and homeostasis in maize. ZMK1 is a homolog of Arabidopsis AKT1 channel in maize, and mainly expressed in maize root. Yeast complementation experiments and electrophysiological characterization in Xenopus oocytes indicated that ZMK1 could mediate K+ uptake. ZMK1 rescued the low-K+-sensitive phenotype of akt1 mutant and enhanced K+ uptake in Arabidopsis. Overexpression of ZMK1 also significantly increased K+ uptake activity in maize, but led to an oversensitive phenotype. Similar to AKT1 regulation, the protein kinase ZmCIPK23 interacted with ZMK1 and phosphorylated the cytosolic region of ZMK1, activating ZMK1-mediated K+ uptake. ZmCIPK23 could also complement the low-K+-sensitive phenotype of Arabidopsis cipk23/lks1 mutant. These findings demonstrate that ZMK1 together with ZmCIPK23 plays important roles in K+ uptake and homeostasis in maize.

[Research progress on factors influencing early liver dysfunction after liver transplantation]

Liver transplantation is the most effective treatment for end-stage liver disease, and early graft dysfunction often occurs after surgery. Early liver dysfunction after liver transplantation has become one of the complications after liver transplantation, which seriously affects the graft and patient survival. Therefore, reducing its occurrence can be an important means to improve the prognosis of recipients after liver transplantation. This paper discusses the research progress on the definition, influencing factors, and prognosis and prediction model in order to provide better prevention and effective reference for improving the success rate and prognosis of early liver dysfunction in recipients after liver transplantation.

The involvement of the mGluR5-mediated JNK signaling pathway in rats with diabetic retinopathy

OBJECTIVE

To understand the involvement of the mGluR5-mediated JNK signaling pathway in rats with diabetic retinopathy (DR).

METHODS

This study established rat models of diabetes mellitus (DM), which were divided into Normal, DM, DM + CHPG (mGluR5 agonist CHPG), and DM + MTEP (mGluR5 antagonist MTEP) groups. The blood glucose and weight of rats were recorded. EB staining was used for observation of blood-retinal barrier (BRB) damage. Neural retina function was measured by pattern electroretinogram (ERG). PAS and NG2 immunohistochemistry were conducted to evaluate the retinal vascular morphology. The TUNEL assay and active caspase-3 immunohistochemistry were performed to detect retinal cell apoptosis. Additionally, the expression levels of superoxide dismutase (SOD) and methylenedioxyamphetamine (MDA) were measured. Moreover, expression levels of mGluR5 and JNK pathway-related proteins were detected by western blot.

RESULTS

When compared with control rats, rats in the DM group showed decreased amplitude and latency of the peak times in the ERG test; further, DM group rats presented increases in blood glucose, BRB permeability, a retinal capillary area density, retinal cell apoptosis with an increased number of active caspase-3-positive cells, MDA level, mGluR5 levels, and the ratio of p-JNK/JNK, and they showed reductions in body weight and SOD activity, as well as in the number of pericytes and in the pericyte coverage (all P < 0.05). However, rats in DM + CHPG group had stronger negative effects than those in DM group (all P < 0.05). Rats from DM + MTEP group showed an opposite trend compared with the DM rats (all P < 0.05).

CONCLUSION

The level of mGluR5 in DR rats was upregulated, whereas inhibition of mGluR5 alleviated retinal pathological damage and decreased cell apoptosis to improve DR via suppression of the JNK signaling pathway, which provided a scientific theoretical basis for the clinical treatment of DR.

Ultrasensitive chemiluminescence detection of sub-fM level Co(II) in capillary electrophoresis

A method of on-line ultrasensitive chemiluminescence detection with capillary electrophoresis for Co(II) is reported. Using our newly developed capillary electrophoresis with chemiluminescence detection system and novel mixing mode of the reagents, the effects of field-amplified injection on detection limits of metal ions were studied in detail. The sub-fM level (1.3 x 10(-16) M, 1.6 x 10(-24) mol, 1 molecule) detection of cobalt ions in ultradilute solution was performed. The catalytic behavior of the chemiluminescence reaction of luminol and hydrogen peroxide by cobalt ions and the reaction conditions, such as the concentration of luminol, H2O2, and pH of chemiluminescence reagent were investigated. The separation of fM level Co(II) and trace amounts of Ni(II) was performed successfully.

[Separation of DNA fragments from halobacterium halobium by capillary electrophoresis with non-gel sieving media]

The optimum electrophoresis separation conditions of Lambda DNA/EcoR I + Hind III fragments were investigated using the capillary column DB-1 coated with polysiloxane. When hydroxyethylcellulose (HEC, 1.0%, mass percentage) was used as the only non-gel sieving medium solution, some Lambda DNA fragments could not be separated. After polyvinylpyrrolidone (PVP, 2%, mass percentage) being added into the medium solution, PVP and HEC formed a network colloidal solution in buffer, and changed the network hole size of sieving media. In addition, the results showed that PVP could restrain the adsorption of capillary to DNA, reduced electroosmotic flow, and improved the selectivity of separation. For the first time, all fragments of Lambda DNA marker was separated completely under the same condition of mixed sieving medium solution. The method was applied to separate two groups of DNA fragments of halobacterium halobium, and the base pair number was conjectured.

Intrathecal magnesium sulfate attenuates algogenic behavior and spinal amino acids release after kainic acid receptor activation in rats

Activation of N-methyl-D-asparate (NMDA) receptor and non-NMDA classes of glutamate receptors play a key role in spinal nociceptive processing. Using with a lumbar intrathecal (IT) catheter and a loop dialysis catheter in lightly anesthetized (1% isoflurane) rats, the effect of IT pre-treatment with magnesium sulfate (100, 300 or 500 microg) on IT kainic acid (KA: 1 microg; non-NMDA receptor agonist) evoked amino acids (AAs) release and corresponding behavior was examined. IT KA produced significant increases (mean+/-SD of % baseline concentration) in dialysate concentrations of aspartate (424+/-88%), glutamate (241+/-35%) and taurine (398+/-58%). IT pre-treatment with MgSO(4) resulted in a dose-dependent suppression of the evoked algogenic behavior and aspartate release. These data suggest that activation of spinal KA receptors provides a powerful stimulus for secondary spinal excitatory AAs release and corresponding appearance of pain behavior. The regulation of this release by magnesium suggests the possible role of this divalent cation in regulating this excitatory effect of non-NMDA receptor activation.

A method for the fabrication of low-noise carbon fiber nanoelectrodes

A new and facile method has been developed for the fabrication of low-noise carbon fiber microelectrodes (CFMEs) and carbon fiber nanoelectrodes (CFNEs). The carbon fiber was flame-fuse sealed in the tip of the glass capillary. The CFMEs were made by cutting the protruding carbon fiber to the desired length, and the CFNEs were achieved by etching the protruding carbon on the flame to form a nanometer-scale tip. The tip of CFNEs can be controlled within the range from 100 to 300 nm. Thus, no epoxy wax was involved in the CFMEs and CFNEs. The experimental results of inspecting CFMEs and CFNEs by scanning electron microscopy demonstrated that the surface of the electrodes and the glass/fiber interface are very smooth. Therefore, the noise caused by the glass/fiber of these electrodes is much lower than that of the electrodes fabricated conventionlly. The electrodes were characterized by ferricyanide, catecholamine (dopamine,DA), norepinephrine (NE), and epinephrine (E)) and 5-hydroxytryptamine (5-HT) neurotransmitters using CV, LSV, DPV, and FSCV. The results showed that the CFMEs and CFNEs have very excellent electrochemical behavior and high sensitivity. The CV and DPV detection limits of DA, NE, and E are 7.6 x 10(-8), 7.0 x 10(-8), and 5.0 x 10(-8) mol/L, and the DPV detection limits of DA, NE, and E are 4.0 x 10(-8), 1.0 x 10(-7), and 2.2 x 10(-7) mol/L, respectively. This experiment offers a new and facile method for the fabrication of CFMEs and CFNEs of very high sensitivity and low noise.

Separation of vanadium, niobium and tantalum as ternary mixed-ligand complexes by capillary electrophoresis using chelation with 4-(2-pyridylazo)resorcinol and tartaric acid

Vanadium(V), niobium(V) and tantalum(V) were separated as ternary mixed-ligand complexes by capillary electrophoresis using 4-(2-pyridylazo)resorcinol (PAR) as the color chelating reagent. Four carboxylic acids such as tartaric acid (Tart), oxalic acid, citric acid and acetic acid were investigated as the additional ligand. The first was chosen as the best. Other parameters such as the concentration ratio of Tart to PAR, buffer concentration, injection time and applied voltage were also optimized. Under the optimized conditions, a complete separation of the three metal complexes was accomplished within 10 min. A linear calibration curve in the range of two orders of magnitude was obtained.

Antiallodynic effect of intrathecal gabapentin and its interaction with clonidine in a rat model of postoperative pain

BACKGROUND

Systemic administration of gabapentin was shown previously to attenuate mechanical allodynia in a rat model of postoperative pain. Because intrathecal administration of gabapentin is effective in other hypersensitivity states, the authors tested its effect in the postoperative model, its interaction with another antiallodynic agent (clonidine), and a possible mechanism of gabapentin action (entry into sites of action via an L-amino acid transporter).

METHODS

Male Sprague-Dawley rats were anesthetized with halothane, and an incision of the plantaris muscle of right hind paw induced punctate mechanical allodynia. Withdrawal threshold to von Frey filament application near the incision site was determined before and 2 h after surgery. Then, an intrathecal injection was performed and thresholds were determined every 30 min for 3 h thereafter.

RESULTS

Paw incision induced a mechanical hypersensitivity (mechanical threshold > 25 g before incision and < 5 g after). Intrathecal gabapentin dose-dependently (10-100 microg) reduced mechanical allodynia. Intrathecal injection of an inhibitor of L-amino acid transporters or a competitor for this transporter, L-leucine, did not reverse the intrathecal effect of gabapentin. The ED50 of intrathecal gabapentin, clonidine, and their combination were 51, 31, and 9 microg, respectively, and isobolographic analysis showed synergy between gabapentin and clonidine.

CONCLUSIONS

Intrathecal gabapentin is effective against tactile allodynia that occurs after paw incision, and interacts synergistically with clonidine. Unlike results in vitro, gabapentin does not obligatorily need to enter cells via the L-amino acid transporter mechanism to achieve its effects in vivo.

Antinociceptive and hemodynamic effects of a novel alpha2-adrenergic agonist, MPV-2426, in sheep

BACKGROUND

alpha2-Adrenergic agonists produce analgesia primarily by a spinal action and hypotension and bradycardia by actions at several sites. Clonidine is approved for epidural use in the treatment of neuropathic pain, but its wider application is limited by hemodynamic side effects. This study determined the antinociceptive and hemodynamic effects of a novel alpha2-adrenergic agonist, MPV-2426, in sheep.

METHODS

Forty sheep of mixed Western breeds with indwelling catheters were studied. In separate studies, antinociception to a mechanical stimulus, hemodynamic effects, arterial blood gas tensions, cerebrospinal fluid pharmacokinetics, and spinal cord blood flow was determined after epidural, intrathecal, and intravenous injection of MPV-2426.

RESULTS

MPV-2426 produced antinociception with greater potency intrathecally (ED50 = 49 microg) than epidurally (ED50 = 202 microg), whereas intravenous administration had no effect. Intrathecal injection, in doses up to three times the ED95, failed to decrease systemic or central arterial blood pressures or heart rate, whereas larger doses, regardless of route, increased systemic arterial pressure. Bioavailability in cerebrospinal fluid was 7% after epidural administration and 0.17% after intravenous administration. Intrathecal MPV-2426, in an ED95 dose and three times this dose, produced a dose-independent reduction in thoracic and lumbar spinal cord blood flow.

CONCLUSIONS

MPV-2426 shares many characteristics of other alpha2-adrenergic agonists examined in sheep, but differs from clonidine and dexmedetomidine by lack of antinociception and minimal reduction in oxygen partial pressure after large intravenous and epidural injections. No hemodynamic depression was observed after intrathecal injection at antinociceptive doses. These results suggest this compound may be an effective spinal analgesic in humans with less hypotension than clonidine, although its relative potency to cause sedation was not tested in this study.

Epidural phenylephrine attenuates hypotension induced by alkalinized lidocaine epidural anesthesia

In this double-blinded, randomized study, we examined the hemodynamic effects of lumbar epidural injection of alkalinized lidocaine with phenylephrine in 81 patients undergoing inguinal herniorrhaphy. Patients assigned to four equal groups received 20 mL of alkalinized lidocaine (17 mL of 2% lidocaine + 3 mL of 7% sodium bicarbonate) with one of four doses of phenylephrine: 0 (Group 1), 50 (Group 2), 100 (Group 3), or 200 microg (Group 4) injected via a lumbar epidural catheter. Blood pressure, heart rate, and skin temperature on the foot were recorded every 5 min for 1 h after injection and were compared among groups. Hypotension was defined as mean arterial pressure < 80% of baseline. The incidence of hypotension was 45%, 55%, 35%, and 15% in Groups 1-4, respectively. Patients in Group 4 showed the smallest reduction in blood pressure compared with Groups 1 and 2 (one-sided Fisher's exact test, P < 0.05). We conclude that the 200-microg dose of epidural phenylephrine (1:100,000 concentration) reduced the incidence of hypotension after epidural anesthesia with alkalinized lidocaine.

IMPLICATIONS

Hypotension after epidural anesthesia is common in general clinical practice. Phenylephrine administered epidurally in combination with alkalinized lidocaine may reduce the incidence of hypotension.

Adenocarcinoma combined with malignant peripheral nerve sheath tumor of the gallbladder

Adenocarcinoma of the gallbladder combined with a malignant peripheral nerve sheath tumor (MPNST) in the gallbladder in an 81-year-old woman is reported. The resected gallbladder showed two distinct tumor components, the epithelioid type of MPNST and adenocarcinoma with areas of mucin production. Although the immediate postoperative course was uneventful, a pathologic fracture of her right upper femur developed 4 months after the cholecystectomy. The pathology was determined to be a feature of metastatic MPNST rather than of adenocarcinoma. A whole body bone scan revealed multiple metastases, including the left parietal skull, left ninth rib, seventh thoracic vertebra, and right upper third of the femur. Despite cholecystectomy and postoperative irradiation therapy, she died 6 months after diagnosis of the tumor. Without an autopsy the primary site of the MPNST was unknown. We found that the prognosis was very poor in patients with distal metastatic MPNST, especially in older patients.

Rapid identification of pathogenic species of Neisseria by carbohydrate degradation tests. Importance of glucose in media used for preparation of inocula

Pathogenic species of Neisseria were identified more readily by carbohydrate degradation tests when 0.5% glucose was used in media from which inocula for the test were obtained. This improved the performance of both non-growth and growth-dependent methods for these tests. One of the three techniques used a non-nutrient buffered salt solution and depended on the presence of preformed enzymes. This test was more accurate and rapid than the two growth-dependent techniques.

Susceptibility of whole cells and spheroplasts of Pseudomonas aeruginosa to actinomycin D

Cells of Pseudomonas aeruginosa suspended in 0.2 M Mg(2+), 20% sucrose, 0.01 M tris(hydroxymethyl)aminomethane, or water partially release lipopolysaccharide. The release of alkaline phosphatase from the periplasmic space and the ability to form spheroplasts on lysozyme treatment is directly related to the lipopolysaccharide released during treatment with 0.2 M Mg(2+), 20% sucrose, or other agents. The synthesis of ribonucleic acid (RNA) by intact cells, magnesium-lysozyme spheroplasts, or 20% sucrose-lysozyme spheroplasts is not sensitive to actinomycin D, whereas RNA synthesis by intact cells or spheroplasts in the presence of ethylene-diaminetetraacetic acid (EDTA) is sensitive to actinomycin D. EDTA alone has an inhibitory effect on RNA synthesis by whole cell, by magnesium-lysozyme spheroplasts, and by 20% sucrose-lysozyme spheroplasts. The experimental data indicate that, although the cell wall is damaged by 0.2 M Mg(2+) or 20% sucrose treatment in the presence of lysozyme, the treated cells or spheroplasts are still resistant to actinomycin D. These results suggest that the cytoplasmic membrane should be considered as the final and determinative barrier to this antibiotic in this organism.