[Further understanding and paying attention to normoalbuminuric diabetic kidney disease]

Diabetes mellitus (DM) has grown up to be an important issue of global public health because of its high incidence rate. Diabetic kidney disease (DKD) is the main cause of end-stage kidney disease (ESKD). Therefore, early diagnosis and timely prevention and treatment of DKD are essential for the progress of DM. The clinical diagnosis and staging of DKD are mostly based on the urinary albumin excretion rate (UAER) and estimated glomerular filtration rate (eGFR). However, clinically, DKD patients show normoalbuminuric diabetic kidney disease (NADKD) instead of clinical proteinuria. The old NADKD concept is no longer suitable and should be updated accordingly with the redefinition of normal proteinuria by NKF/FDA (National Kidney Foundation/Food and Drug Administration). Based on the relevant guidelines of DM and chronic kidney disease (CKD) and combined with the current situation of clinical research, the review described NADKD from the aspects of epidemiology, pathological mechanism, disease diagnosis, clinical characteristics and biomarkers, to arouse the new understanding of NADKD in the medical profession and pay attention to it.

[Correlation between nUGT1A1 gene polymorphisms and adverse events of irinotecan plus S-1 for patients with recurrent or metastatic esophageal squamous cell carcinoma: a prospective, open-label, randomized controlled trial (ESWN 01)]

Objective: To investigate the correlation between UGT1A1 polymorphisms and the irinotecan plus S-1 regimen-induced toxicities in Chinese advanced esophageal squamous cell carcinoma (ESCC) patients. Methods: A total of 46 recurrent or metastatic ESCC patients selected from ESWN 01 trial were randomly assigned to irinotecan plus S-1 group [intravenous infusion of irinotecan (160 mg/m(2)) on day 1 and oral S-1 (80-120 mg) on days 1-10, repeated every 14 days]. Peripheral venous blood at baseline was collected and genomic DNA was extracted. The genetic polymorphisms of UGT1A1*6 and UGT1A1*28 were analyzed by polymerase chain reaction (PCR) amplification. Irinotecan plus S-1 regimen-induced toxicities of patients with different UGT1A1 polymorphisms were observed. The correlation between UGT1A1 polymorphisms and the adverse effects was analyzed. Results: Among the 46 patients, the numbers of UGT1A1*6 wild type genotype (GG), mutant heterozygote (GA) and mutant homozygote (AA) were 30, 15 and 1, while those with UGT1A1*28 wild type genotype (TA6/6), mutant heterozygote (TA6/7) and mutant homozygote (TA7/7) were 36, 8 and 2, respectively. Only one patient with UGT1A1*6 AA genotype occurred grade 3 diarrhea, while one of the 2 patients with UGT1A1*28 TA7/7 genotype occurred grade 4 diarrhea. No neutropenia was observed in the patient with UGT1A1*6 AA genotype, however, both of the two patients with UGT1A1*28 TA7/7 genotype occurred grade 3-4 neutropenia. Patients with UGT1A1*28 genetic polymorphism (TA 6/7 or TA7/7) had a higher response rate compared with wild-type TA6/6 carriers. (55.6% versus 26.5%). Conclusions: The homozygous genotype of UGT1A1*6 AA and UGT1A1*28 TA7/7 are rare (<5%) in Chinese ESCC population. Not all homozygous AA and TA7/7 carriers occur severe dose limited toxicities (DLT) when treated with irinotecan (160 mg/m(2)) plus S-1 regimen for 2 weeks. However, it's still necessary torigorously observe the occurrence of severe diarrhea and neutropenia in patients with UGT1A1*6 AA and UGT1A1*28 TA7/7 and adjust the dose timely.

[Cohort study of efficacy and safety of polatuzumab vedotin combined with immunochemotherapy in patients with relapse/refractory diffuse large B cell lymphoma]

Objective: To investigate the efficacy and tolerability of Polatuzumab vedotin+rituximab±bendamustine (Pola-(B)R) in relapse/refractory diffuse large B cell lymphoma (R/R DLBCL) patients. Methods: The clinical data of 21 patients enrolled in Chinese Pola compassionate use program (CUP) in 4 centers from November 2019 to August 2020 were collected. There were 15 males and 6 females, and the median age was 56 years (ranged 25-76 years). Of the patients, 10 cases received Pola-BR regimen and the other 11 received Pola-R. Their clinical features, regimens, efficacy, and adverse events (AEs) were retrospectively analyzed. Results: Twenty-one patients with at least one efficacy evaluation were included. At data analysis cut-off point (12 Aug. 2020), the best overall response (BOR) rate was 81.0% (17/21) and the complete response (CR) rate was 19.0% (4/21). Kaplan-Meier survival estimation was performed, at a median follow-up of 54 days, three patients (14.3%) had disease progressed, and 18 patients (85.7%) were censored; the median progression-free survival (mPFS) was estimated to be 148 days. The incidence of adverse effects (AEs) of any grade was higher in Pola-BR group than Pola-R group (80.0% vs 63.6%). However, the incidence of grade 3-4 AEs were close in the two groups (30.0% vs 29.3%). The most common hematological toxicities were thrombocytopenia (28.6%, 6/21), neutropenia (28.6%, 6/21) and anemia (14.3%, 3/21), respectively. One patient with pneumonia and 1 patient with hemophagocytic syndrome recovered after symptomatic treatment. No peripheral neuropathy of grade≥2 was observed. Conclusions: The preliminary data suggested that, for heavily treated Chinese R/R DLBCL, the Pola-(B)R regimen still achieves promising efficacy and tolerable safety.

[Phase Ⅲ randomized controlled, multicenter, prospective study of recombinant anti-HER2 humanized monoclonal antibody (Cipterbin) combined with vinorelbine in patients with HER2 positive metastatic breast cancer: the HOPES Study]

Objective: To evaluate the clinical efficacy and safety of recombinant anti-HER2 humanized monoclonal antibody (Cipterbin) combined with vinorelbine in patients with HER2 positive metastatic breast cancer. Methods: Patients were randomized 2∶1 to test group and control group. Patients in test group received Cipterbin (4 mg/kg loading dose and 2 mg/kg maintenance dose each week, IV) combined with vinorelbine (25 mg/m(2) on days 1,8 and 15 of each 28 days, IV). Patients in control group received vinorelbine (25 mg/m(2) on days 1,8 and 15 of each 28 days, IV).The primary end point was progression free survival (PFS). Results: A total of 315 patients were enrolled from Jan 2009 to Jan 2013 (212 in test group and 103 in control group). The median PFS of test group was significantly longer than that of control group, 39.1 weeks vs 14.0 weeks (HR=0.24; 95%CI, 0.16-0.36; P<0.000 1). The objective response rate (ORR) and disease control rate (DCR) in test group were significantly higher than those in control group, ORR was 46.7% vs 18.45% (P<0.000 1) and DCR was 79.72% vs 45.63% (P<0.000 1). The incidence of neutropenia, leucopenia and erythrocytopenia were higher in both groups, but there was no significant difference between two groups.The most common adverse events associated with Cipterbin were infusion reactions. Left ventricular ejection fraction reduced to less than 50% in 5 patients, which were recovered. No serious cardiotoxicity. Conclusion: The recombinant anti-HER2 humanized monoclonal antibody (Cipterbin) combined with vinorelbine has significant efficacy and good safety. It is the optimized therapy regime for patients with taxane-pretreated HER2 positive metastatic breast cancer, which provides more targeted therapy opportunities for HER2 positive breast cancer patients in China.

Safety, efficacy and tumor mutational burden as a biomarker of overall survival benefit in chemo-refractory gastric cancer treated with toripalimab, a PD-1 antibody in phase Ib/II clinical trial NCT02915432

BACKGROUND

High tumor mutational burden (TMB-H) is correlated with enhanced objective response rate (ORR) and progression-free survival (PFS) for certain cancers receiving immunotherapy. This study aimed to investigate the safety and efficacy of toripalimab, a humanized programmed death-1 (PD-1) antibody, in advanced gastric cancer (AGC), and the predictive survival benefit of TMB and PD-L1.

PATIENTS AND METHODS

We reported on the AGC cohort of phase Ib/II trial evaluating the safety and activity of toripalimab in patients with AGC, oesophageal squamous cell carcinoma, nasopharyngeal carcinoma and head and neck squamous cell carcinoma. In cohort 1, 58 chemo-refractory AGC patients received toripalimab (3 mg/kg d1, Q2W) as a monotherapy. In cohort 2, 18 chemotherapy-naive AGC patients received toripalimab (360 mg d1, Q3W) with oxaliplatin 130 mg/m2 qd, d1, capecitabine 1000 mg/m2 b.i.d., d1-d14, Q3W as first-line treatment. Primary end point was ORR. Biomarkers such as PD-L1 and TMB were evaluated for correlation with clinical efficacy.

RESULTS

In cohort 1, the ORR was 12.1% and the disease control rate (DCR) was 39.7%. Median PFS was 1.9 months and median OS was 4.8 months. The TMB-H group showed significant superior OS than the TMB-L group [14.6 versus 4.0 months, HR = 0.48 (96% CI 0.24-0.96), P = 0.038], while PD-L1 overexpression did not correlate with significant survival benefit. A 77.6% of patients experienced at least one treatment-related adverse event (TRAE), and 22.4% of patients experienced a grade 3 or higher TRAE. In cohort 2, the ORR was 66.7% and the DCR was 88.9%. A 94.4% of patients experienced at least one TRAE and 38.9% of patients experienced grade 3 or higher TRAEs.

CONCLUSIONS

Toripalimab has demonstrated a manageable safety profile and promising antitumor activity in AGC patients, especially in combination with XELOX. High TMB may be a predictive marker for OS of AGC patients receiving toripalimab as a single agent.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02915432.

Multi-functional spintronic devices based on boron- or aluminum-doped silicene nanoribbons

Zigzag silicene nanoribbons (ZSiNRs) in the ferromagnetic edge ordering have a metallic behavior, which limits their applications in spintronics. Here a robustly half-metallic property is achieved by the boron substitution doping at the edge of ZSiNRs. When the impurity atom is replaced by the aluminum atom, the doped ZSiNRs possess a spin semiconducting property. Its band gap is suppressed with the increase of ribbon's width, and a pure thermal spin current is achieved by modulating ribbon's width. Moreover, a negative differential thermoelectric resistance in the thermal charge current appears as the temperature gradient increases, which originates from the fact that the spin-up and spin-down thermal charge currents have diverse increasing rates at different temperature gradient regions. Our results put forward a promising route to design multi-functional spintronic devices which may be applied in future low-power-consumption technologies.

Magnon Valve Effect between Two Magnetic Insulators

The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by the spin Seebeck effect at one layer affects the magnon current in the other layer separated by Au. We interpret the magnon valve effect by the angular momentum conversion and propagation between magnons in two YIG layers and conduction electrons in the Au layer. The temperature dependence of the magnon valve ratio shows approximately a power law, supporting the above magnon-electron spin conversion mechanism. This work opens a new class of valve structures beyond the conventional spin valves.

First-line icotinib versus cisplatin/pemetrexed plus pemetrexed maintenance therapy for patients with advanced EGFR mutation-positive lung adenocarcinoma (CONVINCE): a phase 3, open-label, randomized study

BACKGROUND

Icotinib has been previously shown to be non-inferior to gefitinib in non-selected advanced non-small-cell lung cancer patients when given as second- or further-line treatment. In this open-label, randomized, phase 3 CONVINCE trial, we assessed the efficacy and safety of first-line icotinib versus cisplatin/pemetrexed plus pemetrexed maintenance in lung adenocarcinoma patients with epidermal growth factor receptor (EGFR) mutation.

PATIENTS AND METHODS

Eligible participants were adults with stage IIIB/IV lung adenocarcinoma and exon 19/21 EGFR mutations. Participants were randomly allocated (1 : 1) to receive oral icotinib or 3-week cycle of cisplatin plus pemetrexed for up to four cycles; non-progressive patients after four cycles were maintained with pemetrexed until disease progression or intolerable toxicity. The primary end point was progression-free survival (PFS) assessed by independent response evaluation committee. Other end points included overall survival (OS) and safety.

RESULTS

Between January 2013 and August 2014, 296 patients were randomized, and 285 patients were treated (148 to icotinib, 137 to chemotherapy). Independent response evaluation committee-assessed PFS was significantly longer in the icotinib group (11.2 versus 7.9 months; hazard ratio, 0.61, 95% confidence interval 0.43-0.87; P = 0.006). No significant difference for OS was observed between treatments in the overall population or in EGFR-mutated subgroups (exon 19 Del/21 L858R). The most common grade 3 or 4 adverse events (AEs) in the icotinib group were rash (14.8%) and diarrhea (7.4%), compared with nausea (45.9%), vomiting (29.2%), and neutropenia (10.9%) in the chemotherapy group. AEs (79.1% versus 94.2%; P < 0.001) and treatment-related AEs (54.1% versus 90.5%; P < 0.001) were significantly fewer in the icotinib group than in the chemotherapy group.

CONCLUSIONS

First-line icotinib significantly improves PFS of advanced lung adenocarcinoma patients with EGFR mutation with a tolerable and manageable safety profile. Icotinib should be considered as a first-line treatment for this patient population.

Tunneling anisotropic magnetoresistance driven by magnetic phase transition

The independent control of two magnetic electrodes and spin-coherent transport in magnetic tunnel junctions are strictly required for tunneling magnetoresistance, while junctions with only one ferromagnetic electrode exhibit tunneling anisotropic magnetoresistance dependent on the anisotropic density of states with no room temperature performance so far. Here, we report an alternative approach to obtaining tunneling anisotropic magnetoresistance in α′-FeRh-based junctions driven by the magnetic phase transition of α′-FeRh and resultantly large variation of the density of states in the vicinity of MgO tunneling barrier, referred to as phase transition tunneling anisotropic magnetoresistance. The junctions with only one α′-FeRh magnetic electrode show a magnetoresistance ratio up to 20% at room temperature. Both the polarity and magnitude of the phase transition tunneling anisotropic magnetoresistance can be modulated by interfacial engineering at the α′-FeRh/MgO interface. Besides the fundamental significance, our finding might add a different dimension to magnetic random access memory and antiferromagnet spintronics.

Tunneling anisotropic magnetoresistance is promising for next generation memory devices but limited by the low efficiency and functioning temperature. Here the authors achieved 20% tunneling anisotropic magnetoresistance at room temperature in magnetic tunnel junctions with one α′-FeRh magnetic electrode.

Zigzag C2N nanoribbons with edge modifications as multi-functional spin devices

Recently, a holey two-dimensional (2D) C₂N crystal with a wide band gap has been successfully synthesized. However, its non-magnetic property largely limits real applications in spintronics. Here we find that edge magnetism can be introduced by tailoring the holey 2D C₂N crystal into nanoribbons with zigzag edges. When edge N atoms are bare or passivated by H atoms, the device can be used to design high-performance thermospin devices and thermal rectifiers. This is ascribed to the emergence of a spin semiconducting property with a wide band gap. Moreover, if the edge N atoms are passivated by O atoms, the device shows a half-metallic property; meanwhile an obvious spin Seebeck effect can also be observed when a temperature difference is applied across the device.

Carbon-based molecular devices: Fano effects controlled by the molecule length and the gate voltage

Fano effect is an important quantum phenomenon in mesoscopic systems, which arises from an interference between the localized state and the extended state. Here we observe an obvious Fano effect near the Fermi level in an all-carbon molecular device consisting of an acene molecule sandwiched between two zigzag graphene nanoribbon (ZGNR) electrodes. By increasing the length of the molecule, an extended state gradually evolves into a localized state. With the aid of the nearby extended state, a Fano effect is achieved. Using a gate voltage, we can easily tune the Fano effect induced by the single-transmission channel. When the spin degree of freedom is involved, the all-carbon device can show a half-metallic property with positive or negative 100% spin polarization at the Fermi level under the gate voltage; meanwhile the spin thermoelectric effect can also be enhanced.

Giant spin thermoelectric effects in all-carbon nanojunctions

We investigate the thermospin properties of an all-carbon nanojunction constructed by a graphene nanoflake (GNF) and zigzag-edged graphene nanoribbons (ZGNRs), bridged by the carbon atomic chains.

Spin caloritronics of blue phosphorene nanoribbons

We report a first-principles study of the magnetic properties and spin caloritronics of zigzag-type blue phosphorene nanoribbons (zBPNRs).

Temperature-controlled giant thermal magnetoresistance behaviors in doped zigzag-edged silicene nanoribbons

Based on the nonequilibrium Green's function (NEGF) method combined with density functional theory (DFT), we investigate the spin-dependent thermoelectric transport properties of zigzag-edged silicene nanoribbons (ZSiNRs) doped by an Al–P bonded pair at different edge positions.

The increase of the functional entropy of the human brain with age

We use entropy to characterize intrinsic ageing properties of the human brain. Analysis of fMRI data from a large dataset of individuals, using resting state BOLD signals, demonstrated that a functional entropy associated with brain activity increases with age. During an average lifespan, the entropy, which was calculated from a population of individuals, increased by approximately 0.1 bits, due to correlations in BOLD activity becoming more widely distributed. We attribute this to the number of excitatory neurons and the excitatory conductance decreasing with age. Incorporating these properties into a computational model leads to quantitatively similar results to the fMRI data. Our dataset involved males and females and we found significant differences between them. The entropy of males at birth was lower than that of females. However, the entropies of the two sexes increase at different rates, and intersect at approximately 50 years; after this age, males have a larger entropy.

Induction of immune tolerance by pre-infusion of apoptotic lymphocytes derived from peripheral blood of donor rats before liver transplantation

AIM

Acute rejection after liver transplantation is usually treated with large doses of immunosuppressants with severe toxic and side-effects, so it is imperative to find an effective method for preventing acute rejection. The aim of this study was to investigate the effects of immune tolerance by pre-infusion of apoptotic lymphocytes derived from peripheral blood of donor rats before liver transplantation.

METHODS

By using male Wistar and Sprague-Dawley (SD) rats as liver donors and recipients, an orthotopic liver transplantation model was established. The rats were divided into Group A (control group) and Group B (apoptotic lymphocytes pre-infusion group). In group B, 1ml apoptotic lymphocytes suspension (concentration 5×107 cells/mL) which were irradiated by X-ray from electron linear accelerator at the absorbed dose of 2.0Gy was pre-infused via the deep dorsal vein of penis on the 7th day before operation. The serum alanine transaminase (ALT), total bilirubin (TBIL), the serum of interleukin (IL) including IL-2, IL-4 and IL-10, liver pathological changes, and survival time were analysed.

RESULTS

The survival in Group A were 7~13d, with the median survival time (MST) of 11d, and in Group B were 37~60 d, with the MST of 60 d. There were significant differences between the two groups in survival (P <0.001). There were significant differences between the two groups in ALT (P <0.01) and TBIL (P <0.01). Microscopic inspection revealed that severe acute rejection in the Group A, but no sign of acute rejection was observed in the Group B in the 7th day postoperation. The levels of IL-2 were increased after operation in two groups, but was obviously increased in the 7th (P <0.01) and 10th (P <0.001) day postoperation in Group A. The levels of IL-4 and IL-10 in Group A were declined but were increased in the 7th (P <0.01) and 10th (P <0.001) day postoperation in Group B.

CONCLUSION

Preinfusion of apoptotic lymphocytes derived from peripheral blood of donor rats can induce immune tolerance in liver transplantation. Increased expression of Th2 cytokines (IL-4 and IL-10) may plays an important role in inducing immune tolerance.

Clinicopathologic characteristics and surgical treatment of solid pseudopapillary tumor of the pancreas

BACKGROUND AND AIM

Solid pseudopapillary tumor (SPT) of the pancreas is a very rare neoplasm of low malignant potential that mostly affects young women. The aim of the present study is to report our experience in surgical treatment of SPT and review of the literature.

MATERIAL AND METHODS

A retrospective review of three cases of SPT who were treated at our department during the last two years was performed. The clinicopathologic characteristics, surgical treatment, and prognosis are described in detail.

RESULTS

Case 1 described an asymptomatic SPT in a pregnant woman. To the best of our knowledge, only one case of SPT in pregnancy has been reported in the literature. Case 2 described an SPT in the pancreatic tail causing splenic infarction, and a distal pancreatectomy combined with splenectomy was performed. Case 3 described an SPT in the pancreatic head, for which a pancreatoduodenectomy was successfully performed. All of the three patients were followed up for 10-22 months without recurrence or metastases after the initial surgery at the time of reporting.

CONCLUSIONS

At present, radical resection is the treatment of choice for SPT. Enucleation can be performed for tumors with complete amicula. Distal pancreatectomy combined with or without splenectomy can be performed for pancreatic body and/or tail tumor, and pancreatoduodenectomy for pancreatic head tumor. The prognosis of SPT is good.

Fano-Rashba effect in thermoelectricity of a double quantum dot molecular junction

We examine the relation between the phase-coherent processes and spin-dependent thermoelectric effects in an Aharonov-Bohm (AB) interferometer with a Rashba quantum dot (QD) in each of its arm by using the Green's function formalism and equation of motion (EOM) technique. Due to the interplay between quantum destructive interference and Rashba spin-orbit interaction (RSOI) in each QD, an asymmetrical transmission node splits into two spin-dependent asymmetrical transmission nodes in the transmission spectrum and, as a consequence, results in the enhancement of the spin-dependent thermoelectric effects near the spin-dependent asymmetrical transmission nodes. We also examine the evolution of spin-dependent thermoelectric effects from a symmetrical parallel geometry to a configuration in series. It is found that the spin-dependent thermoelectric effects can be enhanced by controlling the dot-electrode coupling strength. The simple analytical expressions are also derived to support our numerical results.PACS numbers: 73.63.Kv; 71.70.Ej; 72.20.Pa.

Soybean isoflavone alleviates β-amyloid 1-42 induced inflammatory response to improve learning and memory ability by down regulation of Toll-like receptor 4 expression and nuclear factor-κB activity in rats

β-amyloid 1-42 (Aβ1-42)-induced learning and memory impairment in rats is believed to be associated with inflammation. Cytokine production is a key pathologic event in the progression of inflammatory processes. In this rat study, soybean isoflavones (SIF) was used to investigate it's protective effects on inflammation caused by β-amyloid 1-42 (Aβ1-42), which is associated with learning and memory impairment in Alzheimer disease. We characterized the learning and memory ability. cytokine profiles of circulating interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) in the serum and the expression of Toll like receptor4 (TLR4) and nuclear factor-κB p65 (NF-κB p65) mRNA and protein in the brain tissue following intracerebroventricular administration of Aβ1-42 by miniosmotic pump for 14 days. The results showed that functional deficits of learning and memory in SIF treatment groups were significantly improved compared to the control group without SIF treatment in water maze test. The serum IL-1β and TNF-α level were significantly increased, and the expressions of TLR4 and NF-κB p65 mRNA and protein in the brain were up-regulated, indicating inflammation response was initiated following administration of Aβ1-42. After intragastric pre-treatment with SIF, inflammatory cytokines was significantly reduced and also SIF reversed the Aβ1-42 induced up-regulation of TLR4 and NF-κB p65 mRNA and protein expression in the brain and expression of NF-κB p65 in nuclei. These results suggested that SIF reduced the cytokine cascade and inflammatory response induced by Aβ1-42 which could result in the improvement of spatial learning and memory ability impairment in the rats.

The response of the tandem pore potassium channel TASK-3 (K(2P)9.1) to voltage: gating at the cytoplasmic mouth

Although the tandem pore potassium channel TASK-3 is thought to open and shut at its selectivity filter in response to changes of extracellular pH, it is currently unknown whether the channel also shows gating at its inner, cytoplasmic mouth through movements of membrane helices M2 and M4. We used two electrode voltage clamp and single channel recording to show that TASK-3 responds to voltage in a way that reveals such gating. In wild-type channels, P(open) was very low at negative voltages, but increased with depolarisation. The effect of voltage was relatively weak and the gating charge small, 0.17. Mutants A237T (in M4) and N133A (in M2) increased P(open) at a given voltage, increasing mean open time and the number of openings per burst. In addition, the relationship between P(open) and voltage was shifted to less positive voltages. Mutation of putative hinge glycines (G117A, G231A), residues that are conserved throughout the tandem pore channel family, reduced P(open) at a given voltage, shifting the relationship with voltage to a more positive potential range. None of these mutants substantially affected the response of the channel to extracellular acidification. We have used the results from single channel recording to develop a simple kinetic model to show how gating occurs through two classes of conformation change, with two routes out of the open state, as expected if gating occurs both at the selectivity filter and at its cytoplasmic mouth.

Multiple primary primitive neuroectodermal tumours within the spinal epidural space with non-concurrent onset

A case of multiple primary primitive neuroectodermal tumours (PNETs), which occurred at different levels of the spinal epidural space successively over a period of 8 months, is reported. A 24-year-old male, presenting with rapidly progressive paralysis, hyperthesia and a posterior epidural mass extending from T8 to T10 revealed by magnetic resonance imaging (MRI), exhibited a good recovery after initial emergency surgery. Lower back pain, chest pain and paralysis were subsequently reported. Spinal MRI in month 7 revealed a mass extending from T12 to L1 and another mass extending from T4 to T5 was detected epidurally in month 8. Additional operations were performed and radiotherapy was given. Pathological findings were consistent with PNETs and symptoms improved with treatment, particularly following each surgical excision.

Spike sorting based upon machine learning algorithms (SOMA)

We have developed a spike sorting method, using a combination of various machine learning algorithms, to analyse electrophysiological data and automatically determine the number of sampled neurons from an individual electrode, and discriminate their activities. We discuss extensions to a standard unsupervised learning algorithm (Kohonen), as using a simple application of this technique would only identify a known number of clusters. Our extra techniques automatically identify the number of clusters within the dataset, and their sizes, thereby reducing the chance of misclassification. We also discuss a new pre-processing technique, which transforms the data into a higher dimensional feature space revealing separable clusters. Using principal component analysis (PCA) alone may not achieve this. Our new approach appends the features acquired using PCA with features describing the geometric shapes that constitute a spike waveform. To validate our new spike sorting approach, we have applied it to multi-electrode array datasets acquired from the rat olfactory bulb, and from the sheep infero-temporal cortex, and using simulated data. The SOMA sofware is available at http://www.sussex.ac.uk/Users/pmh20/spikes.

Probing spin-flip scattering in ballistic nanosystems

Because spin-flip length is longer than the electron mean-free path in a metal, past studies of spin-flip scattering are limited to the diffusive regime. We propose to use a magnetic double barrier tunnel junction to study spin-flip scattering in the nanometer sized spacer layer near the ballistic limit. We extract the voltage and temperature dependence of the spin-flip conductance Gs in the spacer layer from magnetoresistance measurements. In addition to spin scattering information including the mean-free path (70 nm) and the spin-flip length (1.0-2.6 microm) at 4.2 K, this technique also yields information on the density of states and quantum well resonance in the spacer layer.

Applications of multi-variate analysis of variance (MANOVA) to multi-electrode array electrophysiology data

We have developed an adaptation of multi-variate analysis of variance (MANOVA) to analyze statistically both local and global patterns of multi-electrode array (MEA) electrophysiology data where the activities of many (typically >100) neurons have been recorded simultaneously. Whereas simple application of standard MANOVA techniques prohibits extraction of useful information in this kind of data, our new approach, MEANOVA (=MEA+MANOVA), allows a more useful and powerful approach to analyze such complex neurophysiological data. The MEANOVA test enables the detection of the "hot-spots" in the MEA data and has been validated using recordings from the rat olfactory bulb. To further validate the power of this approach, we have also applied the MEANOVA test to data obtained from a simple computational network model. This MEANOVA software and other useful statistical methods for MEA data can be downloaded from http://www.sussex.ac.uk/Users/pmh20

Development of quantitative structure activity relationships in toxicity prediction of complex mixtures

AIM

To predict the toxicity of mixtures of halogenated benzenes (narcotics).

METHODS

Acute toxicity test of single chemicals and mixtures was performed using Photobacterium phosphoreum. Partition coefficients of mixtures were calculated by a special equation. Quantitative structure-activity relationship (QSAR) studies were carried out based on results of toxicity tests, n-octanol/water partition coefficient (Kow), and partition coefficient of mixtures (Kmix).

RESULTS

1) There was a good relationship between toxicity and lgKow for single compounds. 2) QSAR analysis showed a perfect correlation between the calculated Kmix and the mixture toxicity for binary mixtures. 3) Using the QSAR model of binary mixtures, the toxicity of other related mixtures containing different composition and fraction was predicted very well.

CONCLUSION

The toxicity of halogenated benzene mixtures (narcotics) was predicted by QSAR. This kind of study is helpful for assessing the toxicity of narcotic mixtures.

Calreticulin down-regulates both GTP binding and transglutaminase activities of transglutaminase II

Enzyme regulation is an important mechanism for controlling cell proliferation and differentiation in response to extracellular signaling molecules. We have previously reported that a approximately 50 kDa protein (termed Gbetah) consistently copurified with Galphah (transglutaminase II, TGII) and that Gbetah down-regulates the GTPase function of TGII by associating with GDP-bound TGII [Baek et al. (1996) Biochemistry 35, 2651-2657]. In this study, we examined the identity of Gbetah by partial amino acid sequencing and immunological characterizations. The results strongly suggest that Gbetah is a protein known as calreticulin (CRT). When the regulatory role of CRT in the GTPase activity of TGII was examined, CRT inhibited GTP (GTPgammaS) binding and hydrolysis in a concentration-dependent manner. Moreover, CRT interacted only with GDP-bound TGII. These results demonstrate that CRT down-regulates the GTPase activity of TGII by associating with GDP-bound TGII. Studies on the modulation of the TGase activity of TGII revealed that CRT also inhibited TGase activity. The inhibition showed the two characteristics depend on guanine nucleotides occupying the GTPase active site. The inhibition of the "empty" form of the GTPase active site increased the Ca2+ requirement without changing the Vmax. On the other hand, the inhibition of the GDP-bound form decreased Vmax, but did not alter the Ca2+ requirement. Moreover, the GTPgammaS-bound TGII was virtually resistant to Ca2+-mediated stimulation of the TGase activity, indicating that the GTP-bound TGII does not function as a TGase. We concluded that CRT is the regulatory protein of TGII that down-regulates both GTPase and TGase activities, opposing the activators of TGII function.

Cardiac specific overexpression of transglutaminase II (G(h)) results in a unique hypertrophy phenotype independent of phospholipase C activation

Tissue type transglutaminase (TGII, also known as G(h)) has been considered a multifunctional protein, with both transglutaminase and GTPase activity. The role of the latter function, which is proposed as a coupling mechanism between alpha(1)-adrenergic receptors and phospholipase C (PLC), is not well defined. TGII was overexpressed in transgenic mice in a cardiac specific manner to delineated relevant signaling pathways and their consequences in the heart. Cardiac transglutaminase activity in the highest expressing line was approximately 37-fold greater than in nontransgenic lines. However, in vivo signaling to PLC, as assessed by inositol phosphate turnover in [(3)H]myoinositol organ bath atrial preparations, was not increased in the TGII mice at base line or in response to alpha(1)-adrenergic receptor stimulation; nor was protein kinase Calpha (PKCalpha) or PKCepsilon activity enhanced in the TGII transgenic mice. This is in contrast to mice moderately (approximately 5-fold) overexpressing G(alphaq), where inositol phosphate turnover and PKC activity were found to be clearly enhanced. TGII overexpression resulted in a remodeling of the heart with mild hypertrophy, elevated expression of beta-myosin heavy chain and alpha-skeletal actin genes, and diffuse interstitial fibrosis. Resting ventricular function was depressed, but responsiveness to beta-agonist was not impaired. This set of pathophysiologic findings is distinct from that evoked by overexpression of G(alphaq). We conclude that TGII acts in the heart primarily as a transglutaminase, and modulation of this function results in unique pathologic sequelae. Evidence for TGII acting as a G-protein-like transducer of receptor signaling to PLC in the heart is not supported by these studies.

Coefficient of variation of interspike intervals greater than 0.5. How and when?

Using Stein's model with and without reversal potentials, we investigated the mechanism of production of spike trains with a CV (ISI)(standard deviation/mean interspike interval) greater than 0.5, as observed in the visual cortex. When the attractor of the deterministic part of the dynamics is below the firing threshold, spike generation results primarily from random fluctuations. Using computer simulation for a range of membrane decay times and with other model parameters set to values appropriate for the visual cortex, we demonstrate that CV (ISI) is then usually greater than 0.5; if the attractor is above the threshold, spike generation is mainly due to deterministic forces, and CV (ISI) is then usually lower than 0.5. The critical value of the inhibitory postsynaptic potential (IPSP) rate at which CV (ISI) becomes greater than 0.5 is determined, resulting in specifications of how neurones might adjust their synaptic inputs to elicit irregular spike trains.

Alpha 1B-adrenoceptor interacts with multiple sites of transglutaminase II: characteristics of the interaction in binding and activation

We previously reported that a novel GTP binding protein (G alpha h) is tissue type transglutaminase (TGII) and transmits the alpha 1B-adrenoceptor (AR) signal to phospholipase C (PLC) through its GTPase function. We have also shown that PLC-delta 1 is the effector in TGII-mediated signaling. In this study, interaction sites on TGII for the alpha 1B-AR were identified using a peptide approach and site-directed mutagenesis, including in vivo reconstitution of TGIIs with the alpha 1B-AR and PLC-delta 1. To identify the interaction sites, 11 synthetic peptides covering approximately 132 amino acid residues of the C-terminal domain of TGII were tested. The studies with the peptides revealed that three peptides, L547-I561, R564-D581, and Q633-E646, disrupted formation of an alpha 1-agonist-alpha 1B-AR-TGII complex and blocked alpha 1B-AR-mediated TGase inhibition in a dose-dependent manner, indicating that these peptide regions are involved in recognition and activation of TGII by the alpha 1B-AR. These three regions were further evaluated with full-length TGIIs by constructing and coexpressing each site-directed mutant with the alpha 1B-AR and PLC-delta 1 in COS-1 cells. Supporting the findings with these peptides, these TGII mutants lost 56-82% the receptor binding ability and reduced by 29-68% the level of alpha 1B-AR-mediated IP3 production via PLC-delta 1 as compared to those with wild-type TGII. The results also revealed that the regions of R564-D581 and Q633-E646 were the high-affinity binding sites of TGII for the receptor and critical for the activation of TGII by the receptor. Taken together, the studies demonstrate that multiple regions of TGII interact with the alpha 1B-AR and that the alpha 1B-AR stimulates PLC-delta 1 via TGII.

Transglutaminase II: a new class of GTP-binding protein with new biological functions

Tissue type transglutaminase (TGase II) is historically a member of the transglutaminase family, which covalently cross-links cellular proteins and polyamines. A recent new finding in the TGase II field is that the enzyme functions as a signal mediator from receptors to an effector in transmembrane signaling. This review will discuss the recent development of TGase II. This new signal transducer was termed Gh when initially discovered and was recently found to be TGase II. To help the reader understand the role of Gh as a signal mediator, the role of heterotrimeric G-proteins in hormone-mediated transmembrane signaling is briefly discussed. We have highlighted how Gh transmits the alpha 1-adrenoceptor signal to the phospholipase C-delta 1 and how Gh is activated and deactivated compared to the prototype of heterotrimeric G-proteins. Recent developments regarding the structure-function of Gh and other biological functions of Gh are discussed to facilitate understanding the impact of Gh in cells.

Evidence that phospholipase delta1 is the effector in the Gh (transglutaminase II)-mediated signaling

A new class of GTP-binding protein transglutaminase II (Gh) couples to a 69-kDa phospholipase C (PLC). An 8-amino acid region (Leu665-Lys672) of the alpha-subunit of Gh (Galphah) is involved in interaction and activation of PLC, an observation that has now been used to characterize the 69-kDa PLC further. A 20-amino acid peptide corresponding to Leu654-Leu673 of Galphah was used to prepare an affinity resin. On incubation with a partially purified PLC preparation from rat liver membranes, the affinity resin-bound approximately69- and 85-kDa proteins were recognized by an antibody to the 69-kDa PLC. Both purified 69-kDa PLC and PLC-delta1 bound to the affinity resin; moreover, antibodies to PLC-delta1 recognized the 69-kDa PLC, and antibodies to the 69-kDa PLC recognized PLC-delta1. A synthetic peptide corresponding to Leu661-Lys672 of Galphah inhibited the binding of PLC-delta1 to the affinity resin and also stimulated PLC-delta1. Reconstitution of PLC-delta1 with GTPgammaS (guanosine 5'-3-O-(thio)triphosphate)-activated Gh resulted in activation of PLC-delta1. Antibodies to Galphah also coimmunoprecipitated PLC-delta1 upon activation of Gh. These findings indicate that PLC-delta1 is the effector of Gh-mediated signaling.

Transesophageal low-energy cardioversion in an animal model of life-threatening tachyarrhythmias

The purpose of this study was to determine the feasibility and efficacy of terminating life-threatening ventricular tachyarrhythmia by low-energy synchronous or asynchronous shocks delivered through a transesophageal catheter that had both an anode and a cathode. Forty-three episodes of ventricular fibrillation or flutter (Vf or VF) were provoked by transesophageal asynchronous random shocks occurring during the vulnerable period of the ventricular cycle in seven dogs and seven pigs that were healthy adults. The 43 episodes of Vf or VF were terminated by the transesophageal technique. The defibrillation energy thresholds were 23.11 +/- 6.28 J (range, 5-30 J). Seven episodes of ventricular tachycardia (VT) with a cycle length of 360 msec or less (330 +/- 27 msec) were provoked by ventricular pacing stimuli during acute myocardial ischemia resulting from delayed resuscitation in two dogs and three pigs. Five of the seven VTs had a duration of 31 seconds or more, and they were all terminated by transesophageal synchronous shocks, the cardioversion thresholds being 1.71 +/- 2.25 J (range, 0.25-5 J). Fourteen episodes of idioventricular tachycardia (IVT) with a cycle length of 400 msec or more (445 +/- 33.5 msec) spontaneously occurred after the use of adrenaline and after defibrillation in four dogs and five pigs. We also succeeded in terminating seven episodes of IVT with a duration of 34 seconds or more by the same means of treating VT, although IVT is not an indication for cardioversion in the clinical setting.(ABSTRACT TRUNCATED AT 250 WORDS)