Large ultrafast-modulated Voigt effect in noncollinear antiferromagnet Mn3Sn

The time-resolved magneto-optical (MO) Voigt effect can be utilized to study the Néel order dynamics in antiferromagnetic (AFM) materials, but it has been limited for collinear AFM spin configuration. Here, we have demonstrated that in Mn₃Sn with an inverse triangular spin structure, the quench of AFM order by ultrafast laser pulses can result in a large Voigt effect modulation. The modulated Voigt angle is significantly larger than the polarization rotation due to the crystal-structure related linear dichroism effect and the modulated MO Kerr angle arising from the ferroic ordering of cluster magnetic octupole. The AFM order quench time shows negligible change with increasing temperature approaching the Néel temperature (T_N), in markedly contrast with the pronounced slowing-down demagnetization typically observed in conventional magnetic materials. This atypical behavior can be explained by the influence of weakened Dzyaloshinskii–Moriya interaction rather than the smaller exchange splitting on the diminished AFM order near T_N. The temperature-insensitive ultrafast spin manipulation can pave the way for high-speed spintronic devices either working at a wide range of temperature or demanding spin switching near T_N.

Mn3Sn is an anti-ferromagnetic material which displays a large magneto-optical Kerr effect, despite lacking a ferromagnetic moment. Here, the authors show that likewise, Mn3Sn, also presents a particularly large magneto-optical Voigt signal, with a negligible change in the quench time over a wide temperature range.

[Characteristics of primary cutaneous rare nasal extranodal NK/T cell lymphoma: a clinicopathological study of 15 cases]

Objective: To investigate the clinicopathological features and differential diagnosis of primary cutaneous nasal extranodal NK/T cell lymphoma (pcENKTCL-NT). Methods: Fifteen cases of pcENKTCL-NT were collected at the First Affiliated Hospital of Zhengzhou University from January 2016 to December 2019. The clinical characteristics, morphological features, immunophenotypes, and results of in situ hybridization and gene detection were analyzed. Results: Among the 15 patients, 7 were male and 8 were female, with a male to female ratio of 1.0∶1.1. Their ages ranged from 29 to 86 years, and the median age was 59.3 years. All patients were hospitalized for skin lesions, including skin ulcers, scattered patchy red papules, and local blisters. The skin lesion might be a hard nodular mass, and part of it was a confluent patchy erythema; it could be manifested as multiple scattered nodules of different sizes, and some lesions were like round ulceration. There were 8 cases of lower limbs, 4 cases of chest (1 case with upper limb lesions), 2 cases of trunk and 1 case of neck. Most of the patients were sensitive to GGDP regimen (cisplatin, dexamethasone, gemcitabine and pemostatin). Histologically, most lesions showed tumor cells invading the epidermis and skin appendages, dermal infiltration, diffuse distribution, vascular and peritubular destruction, and some subcutaneous adipose tissue involvement. Morphologically, most of the tumor cells were mixed with small-to medium-size lymphocytes, and some were large cells, mixed cells or small cells. Immunohistochemistry showed that CD3, CD3 ε and TIA-1 were expressed in all cases, but not CD20 and CD8. CD56 and granzyme B were expressed in most of the cases, and CD5 was not expressed. Ki-67 positive index was about 50%-90%. EBV in situ hybridization was positive in all cases. The clonal rearrangement of T cell receptor gene was found in some CD56 negative cases. The 15 patients were followed up for 5-45 months, and one of them was lost to follow-up. Five patients died within 5-13 months after the diagnosis, accounting for 35.7% (5/14) of the 14 patients. The average survival time of the deceased patients was 8.6 months. Conclusions: The incidence rate of pcENKTCL-NT is relatively low, but its biological behavior is aggressive and its prognosis is overall poor. Its skin lesions and histopathological features are relatively diverse. The diagnosis should be determined with using clinical data, histological morphology, immunophenotype and EB virus in situ hybridization. At the same time, attention should be paid to differential diagnosis from other cutaneous lymphoma with cytotoxic phenotype to avoid missed diagnosis and misdiagnosis.

[Gastric adenocarcinoma with enteroblastic differentiation and elevated serum alpha fetoprotein]

Objective: To study the proportion and clinicopathological characteristics of gastric adenocarcinoma with enteroblastic differentiation (GAED) in gastric cancers showing an elevated serum alpha fetoprotein(AFP). Methods: A total of 724 resected gastric adenocarcinomas were collected from 2008 to 2018 at the 904 Hospital of Joint Service Support Force, and cases with pre-operative serum AFP>10 μg/L were screened. From the cases with elevated serum AFP, GAED cases were further evaluated based on morphology. Then the clincopathological features and immunohistochemical phenotypes of GAED were reviewed. In addition, the amplification of HER2 gene was detected with fluorescence in situ hybridization(FISH). When overall survival (OS) and progression-free survival (PFS) of GAED were analyzed, 289 cases ordinary gastric adenocarcinoma with normal serum AFP were employed as a control. Results: The percentage of GAED was 44% (11/25) in gastric cancers with elevated serum AFP. GAED was histologically tubular or papillary with clear cytoplasm, and some GAED cases showed cystadenoid structure similar to embryo sac (5 cases), homogeneous eosinophilic granules (4 cases) and intragland ulareosinophilic material (6 cases). All 11 GAED cases had lymph node metastasis. Liver metastasis and vascular thrombus were observed in 2 cases and 5 cases respectively. GAED was immunohistochemically positive for CDX2 (11/11), CD10 (8/11) and MUC2(3/11), which were intestinal epithelium differentiation markers. Meanwhile, primitive markers SALL4 (8/11), GPC3 (7/11) and AFP (5/11) were also expressed in GAED, and HER2 gene amplification was found in 3 cases (3/11) of GAED. Lastly, the PFS of GAED were significantly shorter than that of the control group (P=0.02), while OS was not statistically different between these two groups (P=0.99). Conclusions: Patients with GAED usually have a higher rate of elevated serum AFP in gastric adenocarcinoma, and the cancer exhibites features of both intestinal and primitive differentiation. As GAED is highly invasive, the prognosis of GAED may be poor. For GAED, the diagnosis of well-differentiated or moderately-differentiated adenocarcinoma should be avoided, because this diagnosis leads to underestimated malignant potential.

[Comparison of clinical outcomes of frozen-thawed blastocysts derived from non-pronucleus or two pronucleus zygotes]

Objective: To evaluate the application value of the blastocysts derived from non-pronucleus (0PN) zygotes by the good quality blastocyst formation rate and the clinical outcomes of frozen-thawed blastocyst transfers. Methods: The good quality blastocyst formation rate derived from 0PN zygotes was compared with that derived from2 pronucleus (2PN) zygotes in in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycles from January 2015 to December 2016. In addition, the clinical pregnancy, embryo implantation and live birth rates of frozen-thawed blastocyst transfers with blastocysts derived from 0PN and 2PN zygotes were analyzed on corresponding dates. Results: (1) In IVF cycles, the high quality blastocysts formation rate of 2PN embryos was significantly higher than that of 0PN (46.64% versus 42.42%, P<0.01) . In ICSI cycles, the high quality blastocysts formation rate of 2PN embryos was markedly higher than that of 0PN (41.96% versus 21.73%, P<0.01) . (2) In frozen-thawed embryo transfer cycles for IVF, the clinical pregnancy, implantation and live birth rates of D5 0PN blastocysts were significantly higher than those of D6 2PN (52.64% versus 46.78%, 49.91% versus 41.20%, 46.54% versus 39.56%, all P<0.05) , however, the abortion and newborn abnormal rates of D5 0PN blastocysts were lower than those of D6 2PN blastocysts (17.37% versus 23.36%, 1.31% versus 4.21%, both P<0.05) ; the clinical pregnancy, implantation and livebirth rates of D5 2PN blastocysts were significantly higher than those of D5 0PN (59.73% versus 52.64%, 55.95% versus 49.91%, 53.03% versus 46.54%, all P<0.05) , but newborn abnormal rate was a little higher than that of D5 0PN (3.90% versus 1.31%, P<0.05) ; the clinical pregnancy, implantation and live birth rates of D5 2PN blastocysts were significantly higher than those of D6 2PN (59.73% versus 46.78%, 55.95% versus 41.20%, 53.03% versus 39.56%, all P<0.05) , and the abortion rate of D5 2PN blastocysts was lower than that of D6 2PN blastocysts (18.23% versus 23.36%, P<0.05) . Conclusions: Although the blastocysts derived from 0PN could be transffered, the blastocysts derived from 2PN zygotes are preferred in all cycles. In IVF cycles, the good quality blastocysts derived from 2PN or 0PN zygotes will be transferred.

Comparison of the expression of human equilibrative nucleotide transporter 1 (hENT1) and ribonucleotide reductase subunit M1 (RRM1) genes in seven non-Hodgkin lymphoma cell lines

We investigated the variability in the expression of human equilibrative nucleoside transporter 1 (hENT1) and ribonucleotide reductase subunit M1 (RRM1) in non-Hodgkin lymphoma cell lines. hENT1 and RRM1 mRNA expression levels in natural killer (NK) cells and seven non-Hodgkin lymphoma cell lines (YTS, SNK-6, Jeko-1, ly-1, Raji, Karpas, and Jurket) were studied using reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR) and the results were compared using the Student t-test. mRNA expression of hENT1 was detectable in YTS, SNK-6, Jeko-1, ly-1, Raji, Karpas, Jurket, and NK cells, which revealed variability in gene expression. There were significant differences in the mRNA expression values of hENT1 (P = 0.021) and RRM1 (P = 0.002) compared to those in NK cells. mRNA expression of both hENT1 and RRM1 was closely associated with non-Hodgkin lymphoma cell proliferation. Differential expression analysis of hENT1 and RRM1 in non-Hodgkin lymphoma cell lines may provide novel drug leads for precision medicine.

Substitution of Wheat for Corn in Beef Cattle Diets: Digestibility, Digestive Enzyme Activities, Serum Metabolite Contents and Ruminal Fermentation

The objective of this study was to evaluate the effect of diets containing different amounts of wheat, as a partial or whole substitute for corn, on digestibility, digestive enzyme activities, serum metabolite contents and ruminal fermentation in beef cattle. Four Limousin×LuXi crossbred cattle with a body weight (400±10 kg), fitted with permanent ruminal, proximal duodenal and terminal ileal cannulas, were used in a 4×4 Latin square design with four treatments: Control (100% corn), 33% wheat (33% substitution for corn), 67% wheat (67% substitution for corn), and 100% wheat (100% substitution for corn) on a dry matter basis. The results showed that replacing corn with increasing amounts of wheat increased the apparent digestibility values of dry matter, organic matter, and crude protein (p<0.05). While the apparent digestibility of acid detergent fiber and neutral detergent fiber were lower with increasing amounts of wheat. Digestive enzyme activities of lipase, protease and amylase in the duodenum were higher with increasing wheat amounts (p<0.05), and showed similar results to those for the enzymes in the ileum except for amylase. Increased substitution of wheat for corn increased the serum alanine aminotransferase concentration (p<0.05). Ruminal pH was not different between those given only corn and those given 33% wheat. Increasing the substitution of wheat for corn increased the molar proportion of acetate and tended to increase the acetate-to-propionate ratio. Cattle fed 100% wheat tended to have the lowest ruminal NH₃-N concentration compared with control (p<0.05), whereas no differences were observed among the cattle fed 33% and 67% wheat. These findings indicate that wheat can be effectively used to replace corn in moderate amounts to meet the energy and fiber requirements of beef cattle.

Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

Optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation.

Light can provide ultrafast ways of spin manipulation in magnetic materials, but existing methods are limited by long thermal recovery or low temperature. Here, the authors demonstrate ultrafast spin precession via optical charge-transfer processes in exchange-coupled Fe/CoO at room temperature.

Relationship of EGFR DNA methylation with the severity of non-small cell lung cancer

The aim of this study was to study the relationship of EGFR DNA methylation with the severity of non-small-cell lung cancer (NSCLC). We enrolled 54 patients with NSCLC between March 2013 and June 2014 from Department of Cardiothoracic Surgery in our hospital. The methylation levels in the promoter region of the EGFR gene in cancerous and pericarcinomatous tissue were tested by pyrosequencing. EGFR mRNA expression levels were detected by real-time reverse-transcription polymerase chain reaction. The SPSS software was used for data analysis. We found that EGFR gene methylation levels showed no significant differences among patients of different gender, age, or smoking status. EGFR DNA methylation levels significantly increased (P < 0.05) following NSCLC malignancy upgrading, and showed negative correlation with mRNA expression (P = 0.041). DNA methylation levels of cancerous tissues were significantly higher compared to the corresponding pericarcinomatous tissues (P < 0.05) at stages I, II, and IIIA. The methylation levels at loci 3, 6, 9 among the detected CpG islands were higher in the cancer tissues at each stage (P < 0.05). In summary, our results suggest that the DNA methylation levels of EGFR can be used as an important indicator for the stage of cancer tissue malignancy.

Correlation of EGFR gene amplification with invasion and metastasis of non-small cell lung cancer

The aim of this study was to explore epidermal growth factor receptor (EGFR) gene amplification and its relationship with cancer invasion and metastasis in non-small cell lung cancer (NSCLC). EGFR amplification in 45 patients with NSCLC and 15 subjects with normal lung tissues was detected by fluorescence in situ hybridization. The relationship between EGFR amplification and the clinicopathologic features of NSCLC was analyzed. EGFR gene amplifications were identified in 2 of 15 normal lung tissues (13.33%) and in 29 of 45 NSCLCs (64.44%). Patients <60 years had a 66.67% EGFR amplification rate, while patients ≥60 years had a rate of 62.50%. The EGFR amplification rates in male and female patients were 64.0% (16/25) and 65.0% (13/20), respectively. Pathologically, the EGFR amplification rate of patients with squamous cell carcinoma was 56.52% (13/23), and with adenocarcinoma was 72.72% (16/22). The EGFR amplification rate in NSCLCs with well-moderate differentiation was lower than in those with poor differentiation; 48.0% (12/25) vs 85.0% (17/20), respectively. Patients with lymph node metastasis had nearly double the amplification rate than those without metastasis; 90.0% (18/20) vs 44.0% (11/25), respectively. The rate of EGFR amplification was significantly higher in NSCLC than in normal lung tissue (64.44 vs 13.33%, P < 0.05), and was not correlated with age or gender (P > 0.05), but increased with clinical stage in NSCLCs (P < 0.05). Overall, these studies found that the rate of EGFR gene amplification was increased significantly in NSCLC and was closely related to lymphatic metastasis and TNM stage.

Effects of Three Feeding Systems on Production Performance, Rumen Fermentation and Rumen Digesta Particle Structure of Beef Cattle

The effects of three different feeding systems on beef cattle production performance, rumen fermentation, and rumen digesta particle structure were investigated by using 18 Limousin (steers) with a similar body weight (575±10 kg) in a 80-d experiment. The animals were equally and randomly divided into three treatment groups, namely, total mixed ration group (cattle fed TMR), SI1 group (cattle fed concentrate firstly then roughage), and SI2 group (cattle fed roughage firstly then concentrate). The results showed that the average daily gain was significantly higher in cattle receiving TMR than in those receiving SI1 and SI2 (p<0.05). Consumption per kg weight gain of concentrate, silage, and combined net energy (NEmf) were significantly decreased when cattle received TMR, unlike when they received SI1 and SI2 (p<0.05), indicating that the feed efficiency of TMR was the highest. Blood urea nitrogen (BUN) was significantly decreased when cattle received TMR compared with that in cattle receiving SI1 (p<0.05), whereas there was no difference compared with that in cattle receiving SI2. Ammonia nitrogen concentration was significantly lower in cattle receiving TMR than in those receiving SI1 and SI2 (p<0.05). The rumen area of cattle that received TMR was significantly larger than that of cattle receiving SI1 (p<0.05), but there was no difference compared with that of cattle receiving SI2. Although there was no significant difference among the three feeding systems in rumen digesta particle distribution, the TMR group trended to have fewer large- and medium-sized particles and more small-sized particles than those in the SI1 and SI2 groups. In conclusion, cattle with dietary TMR showed increased weight gain and ruminal development and decreased BUN. This indicated that TMR feeding was more conducive toward improving the production performance and rumen fermentation of beef cattle.

Expression of plzfa in embryo and adult of medaka Oryzias latipes

In this study, a homologous gene named plzfa was identified and characterized in medaka Oryzias latipes. Oryzias latipes plzfa was detected in all the tissues including brain, gill, muscle, liver, intestine, kidney, spleen, testis and ovary using reverse transcriptase (RT)-PCR. plzfa was detected in the oocytes of the ovary and in the spermatogonia and somitic cells of the testis by in situ hybridization. plzfa had a maternal origin with continuous and dynamic expression during embryonic development. plzfa was observed in the brain, neural rod and sensor organs including the eyes, ears and nose during embryogenesis. plzfa was also detected in the neural crest, somite, pectoral fin, intestine and skin. These results indicate that plzfa is a pleiotropic gene that may play major roles in various tissues.

Perpendicular magnetic anisotropy and magnetization dynamics in oxidized CoFeAl films

Half-metallic Co-based full-Heusler alloys with perpendicular magnetic anisotropy (PMA), such as Co₂FeAl in contact with MgO, are receiving increased attention recently due to its full spin polarization for high density memory applications. However, the PMA induced by MgO interface can only be realized for very thin magnetic layers (usually below 1.3 nm), which would have strong adverse effects on the material properties of spin polarization, Gilbert damping parameter, and magnetic stability. In order to solve this issue, we fabricated oxidized Co₅₀Fe₂₅Al₂₅ (CFAO) films with proper thicknesses without employing the MgO layer. The samples show controllable PMA by tuning the oxygen pressure (P_O2) and CFAO thickness (t_CFAO), large perpendicular anisotropy field of ~8.0 kOe can be achieved at P_O2 = 12% for the sample of t_CFAO= 2.1 nm or at P_O2= 7% for t_CFAO= 2.8 nm. The loss of PMA at thick t_CFAO or high P_O2 results mainly from the formation of large amount of CoFe oxides, which are superparamagnetic at room temperature but become hard magnetic at low temperatures. The magnetic CFAO films, with strong PMA in a relatively wide thickness range and small intrinsic damping parameter below 0.028, would find great applications in developing advanced spintronic devices.

Kinetic modeling of inherent mineral catalyzed NO reduction by biomass char

The evolution of rice straw char reactivity during reaction with NO was examined in differential reactor at 900 and 1000 °C. Original and acid-washed rice straw chars were used. Surface area and mineral content of char samples with different conversion were analyzed. The reactivity of the acid-washed char increased until conversion Xchar = 20%, remained constant, and then decreased continuously to zero. The reactivity of the original char decreased continuously to zero throughout the reaction, with a faster decrease at 1000 °C. Mineral transformation during original char reaction was obvious. Concentration of acid-soluble K decreased about 56% and 90% at 900 and 1000 °C. Ca and Mg released little to gas phase, but reacted with SiO2 in a small amount. The evolution of the acid-washed char reactivity correlated well with the development of surface area and was well predicted by random pore model. The reactivity of the original char depended not only on the development of surface area, but also on transformation of inherent minerals, mainly K. A two-reaction model was built which well predicted inherent K transformation. A modified random pore model was developed, which successfully simulated inherent mineral catalyzed char-NO reaction.

Short communication: a mutation in the 3' untranslated region diminishes microRNA binding and alters expression of the OLR1 gene

The oxidized low-density lipoprotein (lectin-like) receptor 1 (OLR1) gene plays an important role in the degradation of the oxidized low-density lipoprotein, which causes damage to the arterial endothelium. Previous studies have shown that a single nucleotide polymorphism (SNP) in the 3' untranslated region (UTR) of OLR1 was associated with milk production and health traits in dairy cattle and with loin eye area and marbling depth in Qinchuan beef cattle. However, the mechanisms by which this SNP affects these traits are not well understood. MicroRNA (miRNA or mir) are small noncoding RNA that regulate gene expression by binding to target mRNA at their UTR to degrade or to repress translation of the target transcript. We hypothesized that miRNA bind to the 3' UTR of OLR1 to cause expression changes of the gene. To test this hypothesis, the Bos taurus autosome (bta)-mir-370miRNA was selected for this study based on bioinformatics prediction analysis. Two vectors that included A or C nucleotides of the 3' UTR SNP and 1 control vector were co-transfected with the vector of bta-miR-370 into human embryonic kidney 293 (HEK293) cells. Results of the dual-luciferase reporter assay showed that the activity of luciferase was significantly lower in cells transfected with the A nucleotide vector than that of the C nucleotide and control vectors. The assay also indicated that activity of miRNA bta-mir-370 was associated with a differential allelic regulation of OLR1 expression. These results imply that the 3' UTR SNP of the OLR1 gene is a strong candidate marker for selection in cattle breeding programs.

Exchange bias of the interface spin system at the Fe/MgO interface

The ferromagnet/oxide interface is key to developing emerging multiferroic and spintronic technologies with new functionality. Here we probe the Fe/MgO interface magnetization, and identify a new exchange bias phenomenon manifested only in the interface spin system, and not in the bulk. The interface magnetization exhibits a pronounced exchange bias, and the hysteresis loop is shifted entirely to one side of the zero field axis. However, the bulk magnetization does not, in marked contrast to typical systems where exchange bias is manifested in the net magnetization. This reveals the existence of an antiferromagnetic exchange pinning layer at the interface, identified here as FeO patches that exist even for a nominally 'clean' interface. These results demonstrate that atomic moments at the interface are non-collinear with the bulk magnetization, and therefore may affect the net anisotropy or serve as spin scattering sites. We control the exchange bias magnitude by varying the interface oxygen concentration and Fe-O bonding.

Quadratic scaling of intrinsic Gilbert damping with spin-orbital coupling in L10 FePdPt films: experiments and Ab initio calculations

The dependence of the intrinsic Gilbert damping parameter α(0) on the spin-orbital coupling strength ξ is investigated in L1(0) ordered FePd(1-x) Pt(x) films by time-resolved magneto-optical Kerr effect measurements and spin-dependent ab initio calculations. Continuous tuning of α(0) over more than one order of magnitude is realized by changing the Pt/Pd concentration ratio showing that α(0) is proportional to ξ(2) as changes of other leading parameters are found to be negligible. The perpendicular magnetic anisotropy is shown to have a similar variation trend with x. The present results may facilitate the design and fabrication of new magnetic alloys with large perpendicular magnetic anisotropy and tailored damping properties.

[Study on chemical constituents from petroleum ether-soluble parts of cones of Platycladus orientalis]

OBJECTIVE

To study chemical constituents from petroleum ether-soluble parts of cones of Platycladus orientalis.

METHODS

The compound were isolaeed by repeated column chromatography of silica gel and Sephadex LH-20. The structures were elucidated by physicochemical properties and spectrum analysis.

RESULTS

Seven constituents were isolated and identified as sandaracopimaric acid (1), 6alpha-hydroxy sandaracopimaric acid (2), ent-isopimara-8 (14), 15-dien-3beta, 19-diol (3), ent-isopimara-8 (9), 15-dien-3beta-ol (4), ent-isopimara-8 (14),15- dien-3beta-ol (5), isocupressic acid (6) and 15-acetylisocupressic acid (7).

CONCLUSION

Compounds 2 and 7 are isolated from this genus for the first time.

Coherent spin precession via photoinduced antiferromagnetic interactions in La0.67Ca0.33MnO3

Pronounced spin precessions are observed in a geometry with negligible canting of the magnetization in ferromagnetic La(0.67)Ca(0.33)MnO(3) thin films using the time-resolved magneto-optical Kerr effect. The precession amplitude monotonically decreases with increasing field, indicating that the coherent spin rotation may be triggered by a transient exchange field and not by demagnetization and/or anisotropy field modulation. We attribute the transient exchange field to emergent antiferromagnetic interactions due to charge transfer and modification of the kinetic energy of e(g) electrons under optical excitation.

ATP-mediated protein kinase B Akt/mammalian target of rapamycin mTOR/p70 ribosomal S6 protein p70S6 kinase signaling pathway activation promotes improvement of locomotor function after spinal cord injury in rats

The protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/p70 ribosomal S6 protein kinase (p70S6K) signaling pathway, as a central controller of cell growth, proliferation, survival, and differentiation in response to extracellular signals, growth factors, nutrient availability, energy status of the cell, and stress, has recently gained attention in neuroscience. The effects of this signaling pathway on repair of spinal cord injury (SCI), however, have not been well elucidated. ATP is increasingly recognized as an important regulator of signal transduction pathways, and plays important roles in functional recovery after nervous system injury. In the present study, we examined the ATP-induced changes of the Akt/mTOR/p70S6K signaling pathway in injured spinal cord of adult rats and potential therapeutic effects of this pathway on SCI-induced locomotor dysfunction. SCI was produced by extradural weight-drop using modified Allen's stall with damage energy of 50 g-cm force. The rats were divided into four groups: SCI plus ATP, SCI plus saline, SCI plus ATP and rapamycin, and sham-operated. Using immunostaining studies, Western blot analyses and real-time qualitative RT-PCR analyses, we demonstrated that the Akt/mTOR/p70S6K signaling pathway is present in the injured spinal cord and the expression of its components at the protein and mRNA levels is significantly elevated by exogenous administration of ATP following SCI. We observed the effectiveness of the activated Akt/mTOR/p70S6K signaling pathway in improving locomotor recovery, significantly increasing the expression of nestin, neuronal nuclei (NeuN), neuron specific enolase (NSE), and neurofilament 200 (NF200), and relatively inhibiting excessive reactive astrogliosis after SCI in a rapamycin-sensitive manner. We concluded that ATP injection produced a significant activation of the Akt/mTOR/p70S6K signaling pathway in the injured spinal cord and that enhancement of rapamycin-sensitive signaling produces beneficial effects on SCI-induced motor function defects and repair potential. We suggest that modulation of this protein kinase signaling pathway activity should be considered as a potential therapeutic strategy for SCI.

Identical sequences but different expression patterns of Hira gene in gynogenetic and gonochoristic crucian carps

Hir/Hira (histone regulation) genes were first identified in yeast as negative regulators of histone gene expression. It has been confirmed that HIRA is a conserved family of proteins present in various animals and plants. In this paper, the cDNAs of the Hira homolog named CagHira and CaHira were isolated from gynogenetic gibel carp (gyno-carp) and gonochoristic color crucian carp (gono-carp) respectively. The full-length CagHira is 3,860 bp in length with an open reading frame (ORF) of 3,033 bp that encodes 1,011 amino acids, while the full-length CaHira is 3,748 bp in length and also has an ORF of 3,033 bp. The deduced amino acid sequences of both Hira homologs contain seven WD domains and show high identity with other HIRA family members. RT-PCR analyses revealed strong expression of Hira in the ovaries, whereas no expression was detected in the testes of either of the fishes. Hira transcription was not detected in the liver of gyno-carp, but a high level of Hira mRNA was observed in gono-carp. The temporal expression pattern showed that the Hira mRNA is consistently expressed during all embryonic development stages in gyno-carp. However, the abundance of CaHira mRNA significantly decreased (P < 0.05) shortly after fertilization and then increased again and remained stable from gastrula till hatching. The varying spatiotemporal expression patterns of Hira genes in gyno-carp and gono-carp may be associated with the differing reproductive modes used by these two closely related fishes. Our results suggest that Hira may play a role not only in the decondensation of sperm nucleus and the formation of pronucleus during fertilization, but also in gastrulation and the subsequent development of embryos.

Viscous spin exchange torque on precessional magnetization in (LaMnO3)2n/(SrMnO3)n superlattices

Photoinduced magnetization dynamics is investigated in chemically ordered (LaMnO3)2n/(SrMnO3)n superlattices using the time-resolved magneto-optic Kerr effect. A monotonic frequency-field dependence is observed for the n=1 superlattice, indicating a single spin population consistent with a homogeneous hole distribution. In contrast, for n> or =2 superlattices, a large precession frequency is observed at low fields indicating the presence of an exchange torque in the dynamic regime. We attribute the emergence of exchange torque to the coupling between two spin populations-viscous and fast spins.

Interface magnetization reversal and anisotropy in Fe/AlGaAs(001)

The reversal process of the Fe interface layer magnetization in Fe/AlGaAs heterostructures is measured directly using magnetization-induced second-harmonic generation, and is compared with the reversal of the bulk magnetization as obtained from magneto-optic Kerr effect. The switching characteristics are distinctly different due to interface-derived anisotropy--single step switching occurs at the interface layer, while two-jump switching occurs in the bulk Fe for the magnetic field orientations employed. The angle between the interface and bulk magnetization may be as large as 40-85 degrees. Such interface switching will dominate the behavior of nanoscale structures.

Ultrafast photoinduced reflectivity transients in doped manganite

The temperature and magnetic field dependence of ultrafast photoinduced spin and quasiparticle relaxation dynamics is reported in La(0.67)Ca(0.33)MnO(3) and LaMnO(3) single crystals and thin films. Both manganites reveal an unusually slow ( approximately 10 micros) carrier relaxation process attributed to the spin-lattice relaxation in localized states. The quasiparticle dynamics is governed by the temperature- and magnetic field-dependent pseudogap in La(0.67)Ca(0.33)MnO(3), and by the temperature-independent Jahn-Teller gap in LaMnO(3). The loss of spectral weight near the Fermi level in La(0.67)Ca(0.33)MnO(3) strongy affects the quasiparticle relaxation dynamics as temperature increases from below T(C). Our results show that the coupled dynamics of charge, spin and lattice is strongly correlated with the distinct gap structures in these manganites.

Long-term natural culture of cochlear sensory epithelia of guinea pigs

To culture and maintain mammalian cochlear cells in vitro is still a big challenge. Only immortalized cochlear cell lines are available. With refinement of culture media and techniques, cochlear sensory epithelial cells of guinea pigs have been cultured without any genetic manipulation using a modified Keratinocyte medium for more than 6 months. The isolated cell clones by cloning cylinders showed a large, flat, epithelial morphotype and expressed cytokeratin and a tight junction associated protein ZO-1, but did not express vimentin. These cells were also labeled with Brn3.1 and calretinin, which are regarded as early hair cell markers. The immunostaining confirmed the culture cells derived from cochlear sensory epithelia. These non-immortalized natural cochlear cells provide valuable cell sources for molecular and genetic studies of the inner ear.

Chlorpromazine alters outer hair cell electromotility

OBJECTIVE

Outer hair cells (OHCs) of the inner ear rapidly convert electrical gradients into mechanical force, enhancing cochlear sensitivity and frequency selectivity. We investigated the effect of chlorpromazine, an antipsychotic medication that alters membrane biomechanics, on OHC electromotility.

STUDY DESIGN

Isolated guinea pig outer hair cells were perfused with chlorpromazine under whole-cell patch-pipette recording conditions. Electromotile responses were measured.

RESULTS

A dramatic, reversible, dose-dependent depolarization of voltage at peak capacitance (V(pkCm)) was seen with chlorpromazine treatment. The gain of the electromotile response was maximal near V(pkCm) both before and after chlorpromazine application. Unlike the 3 other agents that alter electromotility (salicylate, lanthanides, membrane tension), chlorpromazine did not change peak capacitance (Cm(pk)), which varies directly with maximal electromotile gain.

CONCLUSION

Chlorpromazine changes the membrane voltage at which OHCs exhibit maximal electromotile gain, without changing the magnitude of electromotile responses.

SIGNIFICANCE

Chlorpromazine may diminish hearing thresholds or otoacoustic emissions in large doses.

Directional rectification of gap junctional voltage gating between dieters cells in the inner ear of guinea pig

Deiters cells (DCs) are the cochlear supporting cells in inner ear and contain multiple gap junction connexin genes, which when mutated can induce hearing loss. In the present study, the gap junctions between DCs were investigated by a double voltage clamp technique. Besides asymmetric responses to the polarities of transjunctional voltage (V(j)) and transmembrane potential (V(m)), the channels were also sensitive to which cell side was stimulated in a cell pair, i.e. voltage gating had directional dependence. The direction-dependent voltage gating could result in asymmetric current flow between the cells and influenced K(+) passage. Multiple connexins may constitute non-homotypic channels with directional dependence of voltage gating to mediate functional gap junction pathways in the cochlea. This may explain how a single connexin mutation can produce hearing loss.

Voltage gating of gap junctions in cochlear supporting cells: evidence for nonhomotypic channels

The organ of Corti has been found to have multiple gap junction subunits, connexins, which are localized solely in nonsensory supporting cells. Connexin mutations can induce sensorineural deafness. However, the characteristics and functions of inner ear gap junctions are not well known. In the present study, the voltage-dependence of gap junctional conductance (G(j)) in cochlear supporting cells was examined by the double voltage clamp technique. Multiple types of asymmetric voltage dependencies were found for both nonjunctional membrane voltage (V(m)) and transjunctional (V(j)) voltage. Responses for each type of voltage dependence were categorized into four groups. The first two groups showed rectification that was polarity dependent. The third group exhibited rectification with either voltage polarity, i.e., these cells possessed a bell-shaped G(j)-V(j) or G(j)-V(m) function. The rectification due to V(j) had fast and slow components. On the other hand, V(m)-dependent gating was fast (<5 msec), but stable. Finally, a group was found that evidenced no voltage dependence, although the absence of V(j) dependence did not preclude V(m) dependence and vice versa. In fact, for all groups V(j) sensitivity could be independent of V(m) sensitivity. The data show that most gap junctional channels in the inner ear have asymmetric voltage gating, which is indicative of heterogeneous coupling and may result from heterotypic channels or possibly heteromeric configurations. This heterogeneous coupling implies that single connexin gene mutations may affect the normal physiological function of gap junctions that are not limited to homotypic configurations.

Auditory collusion and a coupled couple of outer hair cells

The discrepancies between measured frequency responses of the basilar membrane in the inner ear and the frequency tuning found in psychophysical experiments led to Bekesy's idea of lateral inhibition in the auditory nervous system. We now know that basilar membrane tuning can account for neural tuning, and that sharpening of the passive travelling wave depends on the mechanical activity of outer hair cells (OHCs)3, but the mechanism by which OHCs enhance tuning remains unclear. OHCs generate voltage-dependent length changes at acoustic rates, which deform the cochlear partition. Here we use an electrical correlate of OHC mechanical activity, the motility-related gating current, to investigate mechano-electrical interactions among adjacent OHCs. We show that the motility caused by voltage stimulation of one cell in a group evokes gating currents in adjacent OHCs. The resulting polarization in adjacent cells is opposite to that within the stimulated cell, which may be indicative of lateral inhibition. Also such interactions promote distortion and suppression in the electrical and, consequently, the mechanical activity of OHCs. Lateral interactions may provide a basis for enhanced frequency selectivity in the basilar membrane of mammals.

Responses of anteroventral cochlear nucleus neurons of the unanesthetized decerebrate cat to click pairs as simulated echoes

To elucidate the contribution of the anteroventral cochlear nucleus (AVCN) to 'echo' processing, this study documents the responses of AVCN neurons to simulated echoes and compares them to those of auditory nerve (AN) fibers. Single unit discharges were recorded from 121 units in the AVCN of 21 unanesthetized decerebrate cats in response to click pairs with inter-click intervals ranging from 1 to 32 ms between 45 and 105 dB SPL re 20 microPa. Units were classified according to the post-stimulus time histogram (PSTH) and excitatory-inhibitory response area (EI-area) schemes. Based on their spontaneous rates (SR), units were subdivided into low- ( < 20 spikes/s) and high- ( > 20 spikes/s) SR groups. A majority of the units exhibited second-click responses whose recovery time courses were similar to those of AN fibers. These units included primary-like, chopper and onset units in the PSTH scheme and Types I, I/III and III units in the EI-area scheme. A minority of the units exhibited responses that were distinct from those of AN fibers, in that they had second-click response recovery times that were either markedly reduced or prolonged. This group of units included those with primary-like, chopper and onset PSTHs and Type I/III and III EI-areas. No significant difference was found in the second-click response among various PSTH or EI-area types. High-SR AVCN units exhibited a decrease in the second-click response with increasing level. In contrast, low-SR AVCN units showed little level-dependent change in the second-click responses. This SR-based difference was similar to that previously found among AN fibers. The present results suggest that, although a majority of AVCN units exhibit similar time courses of second-click response recovery to those of AN fibers, there do exist mechanisms in the cochlear nucleus that can substantially alter this representation. Furthermore, the difference between the second-click response recovery functions of low- and high-SR AVCN units and the consistency of this finding between AVCN and AN suggest that SR represents an important dimension for signal representation in the AVCN neurons.

Effect of membrane tension on gap junctional conductance of supporting cells in Corti's organ

The effects of turgor pressure-induced membrane tension on junctional coupling of Hensen cell isolates from the inner ear were evaluated by input capacitance or transjunctional conductance measurement techniques. Turgor pressure was altered by changing either pipette pressure or the osmolarities of extracellular solutions. Both positive pipette pressure and extracellular applications of hypotonic solutions, which caused cell size to concomitantly increase, uncoupled the cells as indicated by reduced input capacitance and transjunctional conductance. These changes were, in many cases, reversible and repeatable. Intracellular application of 50 microM H-7, a broad-based protein kinase inhibitor, and 10 mM BAPTA did not block the uncoupling effect of positive turgor pressure on inner ear gap junctions. The transjunctional conductance at a holding potential of -80 mV was 53.6 +/- 5.8 nS (mean +/- SEM, n = 9) and decreased approximately 40% at a turgor pressure of 1.41 +/- 0.05 kPa. Considering the coincident kinetics of cell deformation and uncoupling, we speculate that mechanical forces work directly on gap junctions of the inner ear. These results suggest that pathologies that induce imbalances in cochlear osmotic pressure regulation may compromise normal cochlear homeostasis.

Temporal encoding and transmitting of amplitude and frequency modulations in dorsal cochlear nucleus

Amplitude- and frequency-modulated (AM and FM, respectively) tones have been considered as simplified models of natural sounds. The responses of auditory neurons can phase-lock to the modulation frequency (fm). The encoding and transmitting of such modulation phase-locking are interesting since there is no any fm physical peak in spectrum. In the present study, we approached these issues by recording the phase-locked responses of the dorsal cochlear nucleus (DCN) units in guinea pigs to different AM and FM tones. For AM noise tones without the spectral cues of fm, the unit's discharges still phase-locked to the envelope cycles, but it was generally weaker than to sinusoidal AM (SAM) tones. At 50% modulation depth (dm), the mean modulation gains of Pauser/ Buildup (P/B) units (n = 7) to AM noise tones was -0.61 dB whereas they had a 6.48 dB mean to SAM tones. Similar to the case of AM tones, phase-locking to sinusoidal FM (SFM) tones represented the time courses of frequency changes, and it could be separated and changeable corresponding to the frequency increasing and decreasing. There were differences between the phase-locking to SAM and SFM tones in an identical unit. Both ON and type I/III units tended to have stronger phase-locking to the SFM tones than to the SAM tones. The phase-locking to the possible demodulated fm components was further examined with different carrier frequencies (fc) and pure tones. The DCN units showed poor or no responses to modulation tones out of their response areas even in the low characteristic frequency (CF) units, but the low-CF units had clear phase-locking to pure tones at the similar fm ranges. The puretone phase-locking had a band-pass shape different from the low-pass shape of the auditory nerve fibers. These data suggest that the modulation phase-locking in the DCN units may be based on the temporal modulation cues and transmitted in the carrier place. The temporal integration of modulation information over the unit's response area as an across-frequency temporal processing model was discussed for modulation enhancement in the CN units.

Mortality among benzene-exposed workers in China

A large cohort of 74,828 benzene-exposed and 35,805 nonexposed workers employed between 1972 and 1987 in 12 cities in China was followed to determine mortality from all causes. Benzene-exposed study subjects were employed in a variety of occupations including coating applications, and rubber, chemical, and shoe production. Mortality was slightly increased among workers with greater cumulative exposure to benzene (ptrend < 0.05), but this excess was largely due to cancer deaths (ptrend < 0.01). Deaths due to lymphatic and hematopoietic malignancies (ptrend = 0.01) and lung cancer (ptrend = 0.01) increased with increasing cumulative exposure to benzene. Investigations continue to relate benzene exposure to specific lymphatic and hematopoietic malignancies and other causes of death.

Responses of auditory nerve fibers of the unanesthetized decerebrate cat to click pairs as simulated echoes

1. To elucidate the peripheral contribution to "echo" processing in the auditory system, we examined the characteristics of auditory nerve responses to click-pair stimuli in unanesthetized, decerebrate cats. We used equilevel click pairs at peak levels of 45, 65, and 85 dB SPL re 20 microPa. The interclick intervals ranged from 1 to 32 ms. This study reports results from 78 auditory nerve fibers in 7 cats. The fibers were divided into 2 groups: 33 low- and 45 high-spontaneous rate (SR), with SRs less than and > or = 20 spikes/s, respectively. A method was introduced to quantify the second-click response, and its recovery was examined as a function of the interclick interval. 2. In general, auditory nerve fibers showed a gradual recovery of the second-click response as interclick interval was increased. Noticeable differences in the second-click response recovery functions emerged among fiber populations that were related to the SR. Low-SR fibers showed little change in the recovery functions of the second-click response as the click level was increased from 45 to 85 dB SPL. In contrast, high-SR fibers showed slower recoveries with increasing click level from 45 to 85 dB SPL. At 45 and 65 dB SPL, the recovery functions of the two SR groups were similar. At 85 dB SPL, high-SR fibers exhibited slower recovery than low-SR fibers, regardless of fiber characteristic frequency. The interclick intervals at 50% second-click response ranged from 1 to 6 ms (mean, 1.4 ms) among low-SR fibers. The interclick intervals at 50% second-click response for high-SR fibers, whereas similar to those for the low-SR fibers at 45 and 65 dB SPL, ranged from 2 to 16 ms (mean, 3 ms) for high-SR fibers, at 85 dB SPL. 3. We also examined auditory nerve compound action potentials (CAPs) evoked by click-pair stimuli for various interclick intervals and click levels. With increasing interclick interval, the amplitude of the second-click CAP increased, and with increasing level, the second-click CAP showed slower recovery. At 45 dB SPL, the recovery functions of the second-click CAP were similar to those of the high- and low-SR fibers. At higher levels, the CAP exhibited lower second-click response values than both high- and low-SR fiber populations for interclick intervals < 4-8 ms. At 85 dB SPL, as interclick interval increased, between 8 and 16 ms, the CAP second-click response converged with that of the high-SR fibers, and by 32 ms, the second-click response values were similar for the CAP, high- and low-SR fibers. 4. The present results are consistent with those of forward masking studies at the level of the auditory nerve in that both demonstrate a short-term reduction of the neural responses. However, the two results differ in that we observed that high-SR fibers exhibited slower recovery than low-SR fibers in response to click-pair stimuli, opposite of the trend observed in the forward masking studies of responses to pure-tone bursts. 5. The present results on auditory nerve fiber responses to click-pair stimuli provide a reference for comparison with responses of central auditory neurons to similar stimuli. This information should serve to elucidate the peripheral contribution to the processing of echoes in the auditory system.

Processing of modulation frequency in the dorsal cochlear nucleus of the guinea pig: sinusoidal frequency-modulated tones

Frequency- and amplitude-modulated (FM and AM, respectively) tones are important information-bearing elements in voice sounds and can also be produced by the spatial movement of sound sources. Zhao and Liang (1995) recently reported the response features of dorsal cochlear nucleus (DCN) neurons to AM tones. In the present study, the responses of the guinea pig DCN neurons to sinusoidal FM (SFM) tones were examined. Discharges of the DCN units to the SFM tones phase-locked to the stimulus modulation frequencies (fm). The phase-locked discharge patterns existed over broad ranges of modulation parameters and at stimulus levels as high as 95 dB SPL or modulation depths (dm) as low as 2%. Robust phase-locking to the fm was observed in samples of all DCN unit types studied. The means of best fm (Bfm) and upper limit fm (ULfm) of all recorded units were 510 Hz and 940 Hz, respectively. Pauser/Buildup (P/B) units had mean maximum synchronization index (SImax) of 0.57. ON units had the highest Bfm with the mean of 646 Hz and subtype ON-S showed the highest mean of SImax at 0.63. Phase-locking to the fm was independent of discharge rates and existed even when the discharge rates were reduced to the background spontaneous rate (SR). A few units showed stronger synchronous responses to the square and triangular FM stimuli instead of the SFM tones. The relationship between the modulated responses and the unit's response area were further examined. The fm phase-locking occurred to modulation bands (or frequency ranges) within the response area, with the modulation bands as narrow as +/- 160 Hz in the central inhibitory areas of the type IV units. As the width of the modulation band changed within a unit's response area, the phases of the fm phase-locked responses of P/B units linearly changed while for Onset units, the change was lesser. The P/B and Onset units had a pi phase shift and a pi/2 phase change, respectively, as carrier frequencies (fc5) passed through characteristic frequencies (CF) and the excitatory/inhibitory response boundaries. The phase-locked responses to the fms were dependent on the SR but were independent of the CF. Low-SR (< or = 2 spikes/s) units had higher synchronization of responses to the fm than the high-SR (> 2 spikes/s) units (SImax = 0.64 and 0.42 respectively). These results suggest that the temporal characteristics of the fm is effectively represented in the responses of DCN units to the SFM tones. Such temporal encoding behavior can play an important role in the processing of the complex sounds in the auditory system. These results also have implications for a possible role for the DCN is in identifying the spatial movement of a sound source.

Small neurons in the vestibular nerve root project to the marginal shell of the anteroventral cochlear nucleus in the cat

We injected biotinylated dextran amine (BDA) into marginal shell regions of the anteroventral cochlear nucleus (AVCN) of the cat. These injections led to retrograde labeling of cells including small cells (median some area = 111 micron2, equivalent diameter = 11.9 microns) in the vestibular nerve root (VNR), just ventral to an anterior part of the AVCN. This is an unexpected new finding. The cells were scattered among BDA-labeled fibers and were oriented parallel to the course of the VNR fibers. We suggest that the small neurons of the VNR might serve as second-order vestibular neurons conveying information from vestibular end organs to the cochlear nucleus (CN) and/or act as interneurons between the olivocochlear fibers in the VNR and the CN.

Processing of modulation frequency in the dorsal cochlear nucleus of the guinea pig: amplitude modulated tones

The modulation frequency (Fm), particularly high Fm (> 200 Hz), in amplitude modulated (AM) tones can elicit the perception of the periodicity pitch (Langner, 1992). In this study, single unit responses to the Fms of the sinusoidal AM tones were investigated at 50 to 90 dB SPL. The recordings were made from the dorsal cochlear nucleus (DCN) of neuroleptic anesthetized guinea pigs with an intact cerebellum. The DCN units show a good capability of phase-locking to Fm at 400-1200 Hz. On-S-type II and Pauser/Buildup (P/B) units have a high modulation gain (7.2-8.3 dB). P/B units can preserve the high modulation gain (5-9 dB) up to 90 dB SPL. The modulation gain exponentially increases with decreasing modulation depth (Dm) and the phase-locking is detectable even at the Dm as low as 2-5%. The 'central skipping' of the phase-locking peak has been found at deep Dms in a few cases. The synchronization is independent of the discharge rate and can remain high even when the responses to AM tones are inhibited below the spontaneous activity. Such encoding behaviors over the unit's response area show that the Fm phase-locking is strong near or at its characteristic frequency (CF). The synchronization index (SI) versus carrier frequency (Fc) curve is similar to the inverse shape of tuning curve but more narrowly tuned than the iso-intensity function of pure tones at moderate to high intensity levels. The phase-locking is related to the unit's spontaneous rate (SR). The average modulation gain of the lower SR (< or = 2 spikes/s) units is 5 dB higher than that of the higher SR (> 2 spikes/s) units (8.16 and 2.92 dB, respectively) at 70 dB SPL. These results suggest that AM information is temporally encoded over broad ranges of modulation parameters in the DCN and is conveyed by the Fc channel. Such a timing mechanism can play an important role in processing of complex sounds under normal acoustic conditions.