The Effect of MDSC-Derived Exosomes Played in Esophageal Squamous Carcinoma Cells after Ionizing Radiation

PURPOSE/OBJECTIVE(S)

Radiotherapy is the main treatment for esophageal cancer. Previous studies have shown that radiotherapy not only kills tumor cells directly, but also reshapes the immune microenvironment of the tumor. It has been reported an increase in the recruitment of myeloid-derived suppressor cells (MDSC) can occur in tumor tissue after ionizing radiation. Exosomes are mediators of intercellular information exchange and are also involved in the regulation of the tumor microenvironment. In this study, we wanted to understand whether MDSC in esophageal cancer tissue are involved in the regulation of tumor cell response to ionizing radiation via exosomes.

MATERIALS/METHODS

KYSE-150 was used to construct a subcutaneous transplantation tumor model in nude mice. And then mice irradiated with 5 Gy×5fx and 0 Gy×5fx respectively. After irradiation, the spleens of the mice were used to isolate MDSC, and collect the cell supernatants to extract the exosomes. Based on the exosomes, we divided the experiment into three groups (control, exosomes, exosomes+radiation). Exosomes were injected into a nude mouse model of esophageal cancer via the tail vein or co-cultured with KYSE-150 cells. Mice were irradiated with a 5 Gy×5fx after completion of injection, and KYSE-150 cells were irradiated with a single dose 4 Gy. After radiation, KYSE-150 cells were used to detect cell cloning, apoptosis and cell cycle by flow cytometry, cell proliferation by CCK 8. XRCC4,XRCC5,XRCC6,γH2AX,ATM expression in cells and tumor tissue were measured by Western blot and RT-PCR.

RESULTS

The tumor volume was significantly reduced after 5 Gy x 5fx radiation. When exosomes co-cultured with KYSE-150 cells, decrease in apoptosis and increase in cell cloning and cell proliferation were found in the exosomes+radiation group and exosomes group after radiation when compared with the control group, with this change being more pronounced in the exosome+radiation group. The results of the cell cycle assay showed that after ionizing radiation, the proportion of cells in the G0/G1 phase was significantly lower, and the proportion of cells in the S and G2/M phases were significantly higher in the exosomes+radiation group and exosomes group when compared to the Control group. The protein and mRNA expression of XRCC4,XRCC5,XRCC6,γH2AX,ATM in cells were increased in exosomes+radiation group and exosomes group after radiation when compared with the control group, with this change being more obvious in the exosome+radiation group. After irradiation, tumor volumes were measured in nude mice and the results showed that exosomes+radiation group tumors were the largest in volume, while the control group regressed most significantly after irradiation.

CONCLUSION

MDSC-derived exosomes have a tumor growth-promoting effect in esophageal squamous carcinoma, which is enhanced by ionizing radiation, and this may be related to the accelerated repair of damage in tumor tissue after radiation.

Irisin alleviates renal injury caused by sepsis via the NF-κB signaling pathway

OBJECTIVE

Renal injury caused by sepsis is a difficult point in the field of critical care medicine today, which seriously endangers the health of patients. The aim of our paper was to study the role of irisin in the inflammation and apoptosis of renal injury caused by sepsis and its potential mechanism of action.

MATERIALS AND METHODS

Lipopolysaccharide (LPS) was utilized to establish an acute kidney injury model. HK-2 cells were divided into 3 groups: control group, LPS group, LPS+irisin group. The expression of TNF-α, IL-1β, Bcl-2, and Bax were detected using Western blot. Commercial enzyme-linked immunosorbent assay (ELISA) kits were used to detect the levels of TNF-α, IL-6, and IL-1β in the cell supernatant. The LDH content was detected to observe cell damage. TUNEL staining and flow cytometry were to investigate the apoptosis in three groups. The viability of HK-2 cells was detected using Cell Counting Kit-8 (CCK-8) assay.

RESULTS

After HK-2 cells were treated with LPS, the LDH content in the cell supernatant was greatly increased, and the expression of TNF-α, IL-6, and IL-1β was also significantly increased. However, after treatment with irisin, LDH content and expression of inflammatory factors were significantly suppressed. Similarly, LPS treatment greatly elevated the levels of TNF-α, IL-1β, Bax, p65 and IκKα, as well as inhibited the expression of Bcl-2 and IκB-α. However, irisin treatment reversed these situations. In addition, the number of TUNEL-positive cells and the apoptotic rate were also greatly decreased in LPS+irisin group compared with those in LPS group.

CONCLUSIONS

Irisin could inhibit inflammation and apoptosis of HK-2 cells treated with LPS via the NF-κB pathway.

Microsatellite markers reveal polymorphisms at the 3′ untranslated region of the SLC11A1 gene in Zhongdian Yellow cattle (Bos taurus)

Solute carrier family 11-member A1 (SLC11A1) gene encodes natural macrophage resistance-associated protein which regulates activity of macrophages against intracellular pathogens. The objective of this study was to study the polymorphism in the microsatellites present at 3′ untranslated region (UTR) of the SLC11A1 gene in 113 Zhongdian Yellow cattle (Bos taurus). Using DNA bi-directional sequencing, we detected seven alleles (GT10–16) for the first microsatellite (MS1), five alleles (GT12–16) for MS2, and four alleles (GT4–7) for MS3. MS3 is studied for the first time and revealed four novel variants (alleles GT4–7). Alleles GT12 (45.1%), GT13 (59.3%), and GT5 (85.4%) were the most frequent alleles at MS1, MS2, and MS3, respectively, Genotypes G12/12, G13/13, and G5/5 had the highest frequency 0.239, 0.540, and 0.743 at MS1, MS2, and MS3, respectively. Haplotypic data revealed that GT12/GT13 was the most frequent haplotype observed followed by GT12/14 haplotype. Three nucleotide variations were observed in MS1 and MS2. Comparative analysis of GT12/GT12 and GT13/GT13 genotype with other bovine genotypes showed significant difference (P > 0.05). Our results suggest that the homozygous genotypes GT12/GT12 and GT13/GT13 in Zhongdian Yellow cattle might be related to disease resistance. The findings reported in this study would be helpful in cattle breeding programs.

Titanium and implantology: a review in dentistry

Implant dentistry has become a popular restorative option in clinical practice. Titanium and titanium alloys (TTA) are the gold standard for endo-osseus dental implants production, thanks to their biocompatibility, resistance to corrosion and mechanical properties. The characteristics of the TTA implant surface seem to be particularly relevant in the early phase of osseointegration. Furthermore, the microstructure of implant surface can largely influence the bone remodelling at the level of the bone-implant surface. Recently, research has stated on the long-term of both survival and success rates of osseointegrated implants and mainly on biomechanical aspects, such as load distribution and biochemical and histological processes at the bone-implant interface. This short review reports recent knowledge on chemical and mechanical properties, biological aspects, innovations in preventing peri-implantitis, describing clinical applications and recent improvements of TTA dental implants. In addition, it highlights current knowledge about a new implant coating that has been demonstrated to reduce the number of initially adhering bacteria and peri-implantitis.

Design, evaluation and initial imaging results of a PET insert based on strip-line readout for simultaneous PET/MRI

We present the development of a PET insert system for potential simultaneous PET/MR imaging using a 9.4 T small animal MRI scanner to test our system. The detectors of the system adopt a strip-line based multiplexing readout method for SiPM signals. In this readout, multiple SiPM outputs in a row share a common strip-line. The position information about a hit SiPM is encoded in the propagation time difference of the signals arriving at the two ends of the strip-line. The use of strip-lines allows us to place the data acquisition electronics remotely from the detector module to greatly simplify the design of the detector module and minimize the mutual electromagnetic interference. The prototype is comprised of 14 detector modules, each of which consists of an 8x4 LYSO scintillator array (each LYSO crystal is 3x3x10 mm³) coupled to two units of Hamamatsu MPPC arrays (4x4, 3.2 mm pitch) that are mounted on a strip-line board. On the strip-line board, outputs of the 32 SiPMs are routed to 2 strip-lines so that 16 SiPM signals share a strip-line. The detector modules are installed inside a plastic cylindrical supporting structure with an inner and outer diameter of 60 mm and 115 mm, respectively, to fit inside a Bruker BioSpec 9.4 Tesla MR scanner. The axial field of view of the prototype is 25.4 mm. The strip-lines were extended by using 5-meter cables to a sampling data acquisition (DAQ) board placed outside the magnet. The detectors were not shielded in the interest of investigating how they may affect and be affected by the MRI. Experimental tests were conducted to evaluate detection performance, and phantom and animal imaging were carried out to assess the spatial resolution and the MR compatibility of the PET insert. Initial results are encouraging and demonstrate that the prototype insert PET can potentially be used for PET/MR imaging if appropriate shielding will be implemented for minimizing the mutual interference between the PET and MRI systems.

The important role of manual aspiration through the guiding catheter during repeated solitaire mechanical thrombectomy in acute ischemic stroke

OBJECTIVE

Acute ischemic stroke (AIS) is an important global health problem. Intravenous (IV) thrombolysis with recombinant tissue plasminogen activator (rt-PA) is the standard treatment. However, only a small number of patients benefit from it because of strict application restrictions. Increasing evidence has demonstrated that mechanical thrombectomy is an effective and safe therapy for AIS.

PATIENTS AND METHODS

We present 14 cases of successful recanalization with Solitaire devices for AIS patients after stroke onset. During stent retrieval, continuous manual aspiration was applied through the guiding catheter, and several large pieces of thrombus were aspirated into the catheter along with the clot, which was adhered to the stent. Clinical outcomes were assessed by the NIHSS at discharge and the mRS on follow-up at 90 days.

RESULTS

All 14 patients with AIS occlusions were treated with Solitaire stents during the study period. The successful recanalization rate was 100%. On discharge, all patients (100%) had improved (NIHSS of ≥ 10 points). At 90 days, 12 patients (86%) had a good functional outcome with mRS of ≤  2.

CONCLUSIONS

We recommend the use of manual aspiration through a guiding catheter as an alternative technique when a specialized aspiration device is not available, to facilitate a fast, complete, and safe thrombus retrieval by the Solitaire system.

Molecular characteristics of the MHC-DRA genes from yak (Bos grunniens) and Chinese yakow (Bos grunniens × Bos taurus)

Two full-length cDNAs (762 bp) of the DRA gene from yak and Chinese yakow were isolated and analysed to identify structural and functional variations. The sequences for DRA in yak (Bogr-DRA) and Chinese yakow (Bogr × BoLA-DRA) were essentially identical to those for cattle (99%) and buffalo (97%). Except for two substitutions in the amino acids comprising the domain for signal peptide (SP) in yak, the additional residues were highly conserved across the species investigated. Peptide-binding site (PBS) of Bogr-DRA and Bogr × BoLA-DRA was highly reserved in the α1 domain among all species investigated. The lack of mutation in Bogr-DRA is consistent with the conception that the gene is highly conserved among all mammalian species. The very high conservation of the DRA gene among ruminants, including yak, may be due to its recent evolutionary detachment.

Isolation, sequence identification and expression profile of three novel genes Rab2A, Rab3A and Rab7A from Black-boned sheep (Ovis aries)

Complete coding sequences of three Black-boned sheep (Ovis aries) genes Rab2A, Rab3A and Rab7A were amplified using reverse transcription polymerase chain reaction (RT-PCR) based on the conserved sequence information of cattle or other mammals known to be highly homologous to sheep ESTs. The Black-boned sheep Rab2A gene encodes a protein of 226 amino acids which contains the conserved putative RabL2 domain and is highly homologous to the Rab2A proteins of seven other species--cattle (96%), human (83%), Sumatran orangutan (82%), rat (81%), mouse (80%), African clawed frog (72%) and zebrafish (71%). The Black-boned sheep Rab3A gene encodes a protein of 220 amino acids that contains the conserved putative Rab3 domain and is very similar to the Rab3A proteins of four species--cattle (99%), African clawed frog (99%), Western clawed frog (98%) and zebrafish (95%). And the Black-boned sheep Rab7A gene encodes a protein of 207 amino acids that contains the conserved putative Rab7 domain and has high homology with the Rab7A proteins of six other species--human (99%), dog (99%), Sumatran orangutan (99%), zebrafish (97%), rabbit (97%) and African clawed frog (96%). Analysis of the phylogenetic tree has demonstrated that the Black-boned sheep Rab2A, Rab3A and Rab7A proteins share a common ancestor and the tissue expression analysis has shown that the corresponding genes are expressed in a range of tissues including leg muscle, kidney, skin, longissimus dorsi muscle, spleen, heart and liver. Our experiment is the first to provide the primary foundation for a further insight into these three sheep genes.

Pigmentation in Black-boned sheep (Ovis aries): association with polymorphism of the Tyrosinase gene

Measurements were made in Black-boned (n = 40) and normal (n = 23) sheep (Ovis aries) from a flock in Nanping County of Yunnan Province, China, as well as a group (n = 21) of Romney Marsh sheep (O. aries) with the view to explaining the basis of the dark pigmentation occurring in the Black-boned animals. Plasma colour was significantly darker (P < 0.01) in Black-boned sheep than in their normal flock mates, which in turn had significantly darker plasma (P < 0.01) than the Romney Marsh sheep. Similar significant (P < 0.01) differences were measured for plasma tyrosinase activity and both groups of sheep from Nanping County had similar plasma concentrations of glutathione which were significantly smaller (P < 0.01) than for the Romney Marsh sheep.A partial fragment of 750 bp of exon 1 of the gene encoding tyrosinase was constructed and found to contain two silent mutation sites (G192C and C462T) but there was no effect on amino acid sequences of tyrosinase. Using restriction fragment length polymorphism analyses two allelic variants of site G192C were identified giving rise to the genotypes GG, GC and CC; the frequencies of allele G being 0.914, 0.824 and 0.286 in the Black-boned sheep, their flock mates and the Romney Marsh sheep respectively. Plasma tyrosinase activity was similar for genotypes GG and GC and for both genotypes significantly higher (P < 0.05) than for genotype CC. The sheep from Nanping County displayed only the GG and GC genotypes and had predominantly black or black and white coat colour whereas the Romney Marsh sheep were of either genotype GC or CC and exhibited only white coat colouration. It is not appears that the dark pigmentation of the Black-boned sheep arises because of polymorphisms in the exon 1 of tyrosinase gene. However, this result could explain the differences between Black-boned and Romney Marsh sheep but not for differences between Black-boned and Nanping Normal sheep. Moreover, this result has provided evidence of genetic markers in the form of polymorphisms of the tyrosinase gene which may help to find the black traits causing mutations. There would be merit in further studies using histochemical and molecular techniques to elucidate the causes of the dark pigmentation in these Black-boned sheep.

Measurements of the cross section for e(+)e(-) --> hadrons at center-of-mass energies from 2 to 5 GeV

We report values of R = sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->mu(+)mu(-)) for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.

Measurement of the total cross section for hadronic production by e(+)e(-) annihilation at energies between 2.6-5 GeV

Using the upgraded Beijing Spectrometer, we have measured the total cross section for e(+)e(-) annihilation into hadronic final states at center-of-mass energies of 2.6, 3.2, 3.4, 3.55, 4.6, and 5.0 GeV. Values of R, sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->&mgr;(+)&mgr;(-)), are determined.

Quantitative analysis of oxytocin and vasopressin messenger ribonucleic acids in single magnocellular neurons isolated from supraoptic nucleus of rat hypothalamus

Oxytocin (OT) and vasopressin (VP) are peptide hormones that are derived from genes predominantly expressed in distinct magnocellular neurons in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. Recent evidence suggests that some magnocellular neurons coexpress both peptides. Our qualitative RT-PCR experiments on single cells show that the majority of magnocellular neurons coexpress both peptide messenger RNAs (mRNAs) in varying amounts. Using a competitive RT-PCR method combined with a standard calibration curve, we quantitatively determined OT and VP mRNA in single magnocellular neurons from the normal female rat SON, with a detection sensitivity of less than 30 mRNA molecules/cell. We defined the phenotypes of the single magnocellular neurons according to their ratios of these two peptide mRNAs. Using this approach, we identified three major phenotypes: oxytocin neurons, where the average OT to VP mRNA ratio is about 256; vasopressin neurons, where the average VP to OT mRNA ratio is about 182; and one oxytocin/vasopressin coexisting neuron, where the OT/VP mRNA ratio is 2. Thus, there is some OT and VP mRNA coexpression in virtually all of the magnocellular neurons in supraoptic nuclei of hypothalamus. However, clear phenotypes are identifiable by considering quantitative as opposed to qualitative differences.

Analysis of synaptotagmin I-IV messenger RNA expression and developmental regulation in the rat hypothalamus and pituitary

Synaptotagmins are a large family of synaptic vesicle membrane proteins, that appear to be involved in neurotransmitter secretion from small secretory vesicles. We have quantitatively analysed the messenger RNA levels of synaptotagmin I-IV isoforms in adult hypothalamic and pituitary tissues in order to determine which of these isoforms dominate in these tissues which mainly secrete peptides from large dense core vesicles. We also studied the expression of these isoforms during prenatal (E15, and E17) and postnatal (P1, P7, P14 and P21) rat hypothalamic development. In order to assay small individual samples (e.g., pituitary and embryonic tissues), we employed quantitative reverse transcription-polymerase chain reaction methods. Our results show that synaptotagmin I messenger RNA is the most abundant isoform in all tissues, and is about 5.4- or 38-fold higher in hypothalamus than in neurointermediate and anterior pituitary lobe, respectively. Synaptotagmin II, which is very abundant in cerebellum, is relatively low in hypothalamus (5% of cerebellum) and virtually absent from the pituitary. Synaptotagmin III is about 10 times greater in the neural tissues versus the pituitary, and synaptotagmin IV was the least abundant isoform in all the tissues. Developmental analyses of the synaptotagmin isoforms in rat hypothalamus shows that all isoforms are at low levels during embryonic stages and increase postnatally. Synaptotagmin I and II have similar patterns and rise to maximum (adult) levels around P14, whereas synaptotagmin III and IV reach their maximum levels considerably earlier, at P1. These data show that synaptotagmin I is the dominant isoform in both predominantly peptide secreting systems (e.g., in pituitary tissues) and in neurotransmitter secreting systems (e.g., in cerebellum). While the developmental expression patterns of synaptotagmin I and II parallels the temporal development of synaptogenesis in the nervous system, the early maximal expression of synaptotagmin III and IV suggests that these isoforms may have other functions during early postnatal development.

Domoic acid is a potent neurotoxin to neonatal rats

Domoic acid induces a time-dependent neuroexcitotoxic effect in neonatal rats characterized by hyperactivity, stereotypic scratching, convulsions, and death with observable behaviors occurring at exposures 40 times lower by body weight in neonates than reported in adults. Low doses of domoic acid (0.1 mg/kg) induced c-fos in the central nervous system which was inhibited in part by 2-amino-5-phosphonovaleric acid, an NMDA receptor antagonist. Domoic acid caused no evidence of structural alteration in the brain of neonates as assessed by Nissel staining and cupric silver histochemistry. Domoic acid induced reproducible behavioral effects at doses as low as 0.05 mg/kg and induced seizures doses as low as 0.2 mg/kg. Determination of serum domoic acid levels after 60 min exposure indicated that serum levels of domoic acid in the neonates corresponded closely to the serum levels that induce similar symptoms in adult rats and mice. We conclude that neonatal rats are highly sensitive to the neuroexcitatory and lethal effects of domoic acid and that the increased sensitivity results from higher than expected serum levels of domoic acid. These findings are consistent with other findings that reduced serum clearance of domoic acid is a predisposing factor to domoic acid toxicity.

Glutamate receptors and calcium entry mechanisms for domoic acid in hippocampal neurons

Domoic acid (50 nM) elevates cytosolic free calcium ([Ca2+]i) levels in 49% of the hippocampal pyramidal neurons isolated from postnatal day one (PND1) rats. This effect was prevented by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; an antagonist of non-N-methyl-D-asparate (NMDA) receptors, but not 2-amino-5-phosphonovaleric acid (AP-5; an antagonist of NMDA receptors). Domoic acid given at 5 microM also elevated [Ca2+]i levels in a second population (36%) of neurons in which the effect was only partially inhibited by 100 microM CNQX. Nimodipine given at 300 nM prevented the elevation in [Ca2+]i caused by 50 nM and 5 microM domoic acid, indicating that domoic acid induced Ca2+ entry through type L voltage dependent calcium channels. These results provide evidence for at least two domoic acid-sensitive non-NMDA receptor subtypes in primary cultures of neonatal hippocampal pyramidal cells and indicate that voltage-dependent calcium channels are a primary calcium entry mechanism for domoic acid action.

Maitotoxin-elevated cytosolic free calcium in GH4C1 rat pituitary cells nimodipine-sensitive and -insensitive mechanisms

Maitotoxin includes an extracellular Ca2+-dependent membrane depolarization predominantly via activation of L-type voltage-dependent Ca2+ channels (L-VDCC) in GH4C1 rat pituitary cells. In contract to studies employing intracellular dyes, electrophysiological studies have indicated that maitotoxin activates voltage-independent conductances. In the present study, we used fura-2 calcium digital analysis to investigate the actions of very low concentrations of maitotoxin on cytosolic free calcium ([Ca2+]i) in GH4C1 cells in an effort to distinguish different calcium entry mechanisms. Maitotoxin at concentrations as low as 0.01 ng/mL elevated [Ca2+]i 35 +/- 3% and induced membrane depolarization. The concentration dependency for maitotoxin-elevated [Ca2+]i was biphasic with the first phase maximal at 0.05 to 0.5 ng/mL and the minimum EC50 of the second phase about 2.0 ng/mL. Nimodipine (100 nM), a dihydropyridine antagonist of L-VDCC, prevented the [Ca+2]i increase and depolarization induced by up to 0.1 ng/mL maitotoxin, but not at higher concentration (0.5 ng/mL) of maitotoxin. This indicates that lower concentrations (0.1 ng/mL) of maitotoxin require L-VDCC, whereas higher concentrations (>-0.5 ng/mL) of maitotoxin may require additional ionic mechanisms. Maitotoxin (0.5 ng/mL) induced 45Ca2+ uptake and depolarization in Ltk-cells which lack VDCC. Reducing extracellular Cl- from 123 to 5.8 microM increased the magnitude of membrane depolarization by maitotoxin (0.5 ng/mL), which suggests that a Cl- conductance participated in depolarization induced by higher maitotoxin concentrations. Taken together, our results indicate that maitotoxin activates at least two ionic mechanisms. At lower concentrations of maitotoxin, the primary ionic mechanism requires the activation of L-VDCC; however, at higher maitotoxin concentrations, additional ionic mechanisms are involve in the entry of extracellular Ca2+. This latter mechanism may represent the voltage-independent pathway evident under voltage clamp conditions.

[A computer real time system for acquiring and monitoring phrenic nerve discharge signal]

This paper presents a real time system of computer (IBM PC/AT) to acquire and monitor phrenic nerve discharge signal according to the need of researching. The system was programmed with 80286 assembly language. It has the properties of fast speed, high efficiency, small size of object code and abundant interactive functions. It is easy to handle and can be used for acquiring and monitoring other electrophysiological signals.

Maitotoxin induces a calcium-dependent membrane depolarization in GH4C1 pituitary cells via activation of type L voltage-dependent calcium channels

Maitotoxin (MTX) is a water-soluble polyether, isolated from the marine dinoflagellate Gambierdiscus toxicus, that stimulates hormone release and Ca2+ influx. We have investigated the action by which MTX induces Ca2+ influx and stimulates prolactin (PRL) release from GH4C1 rat pituitary cells. PRL release elicited by MTX is abolished in a concentration-dependent manner by nimodipine, a dihydropyridine (DHP) antagonist of type L voltage-dependent calcium channels (L-VDCC), indicating that MTX-enhanced PRL release occurs via activation of type L-VDCC. As an initial approach to determine whether MTX interacts directly with VDCC, we examined whether MTX affects the binding of [3H]PN 200-110, a DHP class antagonist, in intact GH4C1 cells. MTX increased the Bmax of [3H]PN 200-110 binding to intact GH4C1 cells from 4.6 +/- 0.03 to 12.5 +/- 2.2 fmol/10(6) cells, without changing the Kd. This indicates that MTX does not bind to the DHP site, but rather suggests that MTX may have an allosteric interaction with the DHP binding site. The effect of MTX on DHP binding was largely (65%) calcium-dependent. We next examined whether MTX alters the membrane potential of GH4C1 cells using the potential sensitive fluorescent dye bisoxonol. Addition of 100 ng/ml MTX to GH4C1 cells caused a membrane depolarization within 2.5 min which reached a plateau at 5 min. The MTX-induced depolarization was not prevented by substitution of impermeant choline ions for Na+. It was similarly unaffected by K+ channel blockers or by depleting the K+ chemical concentration gradient with gramicidin, a monovalent cation pore-forming agent. By contrast, low extracellular Ca2+ totally abolished the depolarization response, and nimodipine at 100 nM substantially reduced the MTX-induced membrane depolarization. These results indicate that the predominant effect of MTX on depolarization is Ca2+ influx through L-VDCC. Taken together, our results indicate that MTX-enhanced PRL release occurs exclusively via activation of type L-VDCC in GH4C1 cells. We suggest that MTX induces an initial slow calcium conductance, possibly via an allosteric interaction with a component of the VDCC complex, which, in turn, initiates a positive feedback mechanism involving calcium-dependent membrane depolarization and voltage-dependent activation of calcium channels.

[A computer program for the power spectra analysis of biomedical signals]

This paper presents a useful program for the power spectra analysis of biomedical signals on a microcomputer. The frequency spectra to show the allocation of frequency were calculated from the acquired biomedical signal via a window algorithm and the real signal special handling. The frequency spectra became normalized power spectra through algorithm and could be displayed on a monitor or printer in the mode of histogram. We have got good results using this program to compute the power spectra of phrenic nerve discharges from the rabbit.

[A computerized analysis of phrenic nerve discharge signal]

The authors offered a method of computerized analysis to solve the problems met in the manual measurement of the signal of phrenic nerve discharge (PND). An envelope was gained via digital fullwave rectification and filter from the acquired PND signal. From it, some important parameters were measured automatically. The program ran well in animal experiments. The values of the PND parameters obtained by computer showed no significant difference as compared with the averaged values measured manually by researchers.

[Uniform design for the best conditions of processing heixi in shenrong heixi pills] off

Uniform design has been applied to select the optimum technological conditions for processing Heixi in Shenrong Heixi Pills, using the contents of the main constituent of Heixi SNS as the optimum target. The best technological conditions have thus been found.