C-MYC overexpression is required for continuous suppression of oncogene-induced senescence in melanoma cells

Malignant melanomas often harbor activating mutations in BRAF (V600E) or, less frequently, in NRAS (Q61R). Intriguingly, the same mutations have been detected at higher incidences in benign nevi, which are largely composed of senescent melanocytes. Overexpression of BRAF(V600E) or NRAS(Q61R) in human melanocytes in vitro has been shown to induce senescence, although via different mechanisms. How oncogene-induced senescence is overcome during melanoma progression remains unclear. Here, we report that in the majority of analysed BRAF(V600E)- or NRAS(Q61R)-expressing melanoma cells, C-MYC depletion induced different yet overlapping sets of senescence phenotypes that are characteristic of normal melanocytes undergoing senescence due to overexpression of BRAF(V600E) or NRAS(Q61R), respectively. These senescence phenotypes were p16(INK4A)- or p53-independent, however, several of them were suppressed by genetic or pharmacological inhibition of BRAF(V600E) or phosphoinositide 3-kinase pathways, including rapamycin-mediated inhibition of mTOR-raptor in NRAS(Q61R)-expressing melanoma cells. Reciprocally, overexpression of C-MYC in normal melanocytes suppressed BRAF(V600E)-induced senescence more efficiently than NRAS(Q61R)-induced senescence, which agrees with the generally higher rates of activating mutations in BRAF than NRAS gene in human cutaneous melanomas. Our data suggest that one of the major functions of C-MYC overexpression in melanoma progression is to continuous suppress BRAF(V600E)- or NRAS(Q61R)-dependent senescence programs.

c-Myc depletion inhibits proliferation of human tumor cells at various stages of the cell cycle

A major role for c-Myc in the proliferation of normal cells is attributed to its ability to promote progression through G(1) and into S phase of the cell cycle. The absolute requirement of c-Myc for cell cycle progression in human tumor cells has not been comprehensively addressed. In the present work, we used a lentiviral-based short hairpin RNA (shRNA) expression vector to stably reduce c-Myc expression in a large number of human tumor cell lines and in three different types of normal human cells. In all cases, cell proliferation was severely inhibited, with normal cells ultimately undergoing G(0)/G(1) growth arrest. In contrast, tumor cells demonstrated a much more variable cell cycle response with cells from several lines accumulating in S or G(2)/M phases. Moreover, in some tumor lines, the phase of cell cycle arrest caused by inhibition of c-Myc could be altered by depleting tumor suppressor protein p53 or its transcriptional target p21(CIP/WAF). Our data suggest that, as in the case of normal cells, c-Myc is essential for sustaining proliferation of human tumor cells. However its rate-limiting role in cell cycle control is variable and is reliant upon the status of other cell cycle regulators.

Event-related potential N270 is elicited by mental conflict processing in human brain

We recorded event-related potentials (ERPs) in 15 subjects in order to elicit a N270 of arithmetic conflict. Subjects calculated an arithmetic problem and matched their calculation result to an answer digit. They pressed a button when the presented digit is a true answer (condition 1) and pressed another button when the answer is false (condition 2). ERP components of P90, N130, P180, N200 and late positive component (LPC) were recorded in condition 1. In condition 2, N270 was elicited between N200 and LPC and it peaked at approximately 270 ms (268.6 +/- 29.0 ms at Cz). The peak latency of LPC in condition 2 (405.7 +/- 51.3 ms) is significantly delayed than condition 1 (307.5 +/- 22.7 ms). N270 reflects the endogenous conflict processing in human brain.

Variable patterns of distribution of PrP(CWD) in the obex and cranial lymphoid tissues of Rocky Mountain elk (Cervus elaphus nelsoni) with subclinical chronic wasting disease

Sections of medulla oblongata, taken at the level of the obex, palatine tonsil and medial retropharyngeal lymph node from 10,269 captive Rocky Mountain elk (Cervus elaphus nelsoni), were examined by immunohistochemical staining with monoclonal antibody for the prion protein associated with the transmissible spongiform encephalopathy of cervids, chronic wasting disease (PrP(CWD)). The protein was detected in 226 of them. On the basis of the anatomical location of the deposits in the brainstem of 183 elk, four distinct patterns of distribution of PrP(CWD) within the parasympathetic region of the dorsal motor nucleus of the vagus nerve and the adjacent nuclei were observed. Mild gross lesions of chronic wasting disease (serous atrophy of fat) were observed in only three elk, all with spongiform degeneration; the other elk were considered to be in the preclinical stage of the disease. In contrast with the relatively predictable distribution of prion protein (PrP) in the brain and cranial nodes of sheep and mule deer, the distribution of PrP(CWD) in the brain and nodes of the elk was more variable and unrelated to their PrP genotype. One hundred and fifty-five of the 226 positive elk had deposits of PrP(CWD) in the brainstem and lymphoid tissues, 43 had deposits only in the lymphoid tissue and 28 had deposits only in the brainstem.

The relationship between Cho/NAA and glioma metabolism: implementation for margin delineation of cerebral gliomas

Background

The marginal delineation of gliomas cannot be defined by conventional imaging due to their infiltrative growth pattern. Here we investigate the relationship between changes in glioma metabolism by proton magnetic resonance spectroscopic imaging (¹H-MRSI) and histopathological findings in order to determine an optimal threshold value of choline/N-acetyl-aspartate (Cho/NAA) that can be used to define the extent of glioma spread.

Method

Eighteen patients with different grades of glioma were examined using ¹H-MRSI. Needle biopsies were performed under the guidance of neuronavigation prior to craniotomy. Intraoperative magnetic resonance imaging (MRI) was performed to evaluate the accuracy of sampling. Haematoxylin and eosin, and immunohistochemical staining with IDH1, MIB-1, p53, CD34 and glial fibrillary acidic protein (GFAP) antibodies were performed on all samples. Logistic regression analysis was used to determine the relationship between Cho/NAA and MIB-1, p53, CD34, and the degree of tumour infiltration. The clinical threshold ratio distinguishing tumour tissue in high-grade (grades III and IV) glioma (HGG) and low-grade (grade II) glioma (LGG) was calculated.

Results

In HGG, higher Cho/NAA ratios were associated with a greater probability of higher MIB-1 counts, stronger CD34 expression, and tumour infiltration. Ratio threshold values of 0.5, 1.0, 1.5 and 2.0 appeared to predict the specimens containing the tumour with respective probabilities of 0.38, 0.60, 0.79, 0.90 in HGG and 0.16, 0.39, 0.67, 0.87 in LGG.

Conclusions

HGG and LGG exhibit different spectroscopic patterns. Using ¹H-MRSI to guide the extent of resection has the potential to improve the clinical outcome of glioma surgery.

Prp-c and Prp-Sc at the fetal-maternal interface

Scrapie is a naturally occurring prion (PrP) disease causing a fatal neurodegenerative disorder in sheep and goats. Previous studies suggest that scrapie is transmitted naturally through exposure to the scrapie agent in wasted placentas of infected ewes. This study determined the distribution and biochemical properties of PrP cellular (PrP-C) and the distribution of PrP scrapie (PrP-Sc) in reproductive, placental, and selected fetal tissues and fetal fluids in sheep. Glycosylated, N-terminally truncated, proteinase K-sensitive PrP-C with apparent molecular masses of 23-37 kDa was present in reproductive, placental, and fetal tissues and fetal fluids. PrP-C was low or undetectable in intercotyledonary chorioallantois, amnion, urachus, amniotic fluid, and fetal urine. In pregnant ewes, cotyledonary chorioallantois, allantoic fluid, and caruncular endometrium contained higher levels of PrP-C than did intercaruncular endometrium, myometrium, oviduct, ovary, fetal bladder, or fetal kidney. Caruncular endometrial PrP-C was up-regulated during pregnancy. Despite the wide distribution of PrP-C in reproductive, placental, and selected fetal tissues and fetal fluid, PrP-Sc was detected only in caruncular endometrium and cotyledonary chorioallantois of pregnant scrapie-infected ewes. The embryo/fetus may not be exposed to scrapie in utero because it is separated physically from PrP-positive allantois and chorioallantois by PrP-negative amnion.

Event-related brain potentials elicited by a number discrimination task

To study the number cognition process, we recorded event-related potentials (ERPs) in 14 subjects when they were indicating whether a number pair was the same or not. The two numbers given in sequence were either the same (condition 1) or different (condition 2). After 270 ms following the onset of the second stimulus in condition 2, a negative component N270 was recorded on the scalp with the most negative amplitude at the central and occipital areas. Hemispheric asymmetry was not observed in the potential. This negative component is considered to reflect the mismatching process for numbers in the brain.

Reorganization of cerebro-cerebellar circuit in patients with left hemispheric gliomas involving language network: A combined structural and resting-state functional MRI study

The role of cerebellum and cerebro-cerebellar system in neural plasticity induced by cerebral gliomas involving language network has long been ignored. Moreover, whether or not the process of reorganization is different in glioma patients with different growth kinetics remains largely unknown. To address this issue, we utilized preoperative structural and resting-state functional MRI data of 78 patients with left cerebral gliomas involving language network areas, including 46 patients with low-grade glioma (LGG, WHO grade II), 32 with high-grade glioma (HGG, WHO grade III/IV), and 44 healthy controls. Spontaneous brain activity, resting-state functional connectivity and gray matter volume alterations of the cerebellum were examined. We found that both LGG and HGG patients exhibited bidirectional alteration of brain activity in language-related cerebellar areas. Brain activity in areas with increased alteration was significantly correlated with the language and MMSE scores. Structurally, LGG patients exhibited greater gray matter volume in regions with increased brain activity, suggesting a structure-function coupled alteration in cerebellum. Furthermore, we observed that cerebellar regions with decreased brain activity exhibited increased functional connectivity with contralesional cerebro-cerebellar system in LGG patients. Together, our findings provide empirical evidence for a vital role of cerebellum and cerebro-cerebellar circuit in neural plasticity following lesional damage to cerebral language network. Moreover, we highlight the possible different reorganizational mechanisms of brain functional connectivity underlying different levels of behavioral impairments in LGG and HGG patients.

Wet Chemical Etching of AlN Single Crystals

Anisotropic chemical etching is an important means for characterizing the polarity and defect density of single crystals. In this letter, we present the results of our studies on the etching of bulk AlN crystals in aqueous potassium hydroxide solution. The nitrogen polarity (0001) basal plane initially etched rapidly, while the aluminum polarity basal plane, and prismatic (100) planes were not etched. The etch rate of the nitrogen polarity basal plane eventually decreased to zero, as the surface became completely covered with hexagonal hillocks which were bounded by {101} planes. The hillock density for the self-seeded AlN crystals studied was typically in the range of 5×107cm−2 to 109cm−2. From our analysis of etched AlN crystals, we infer that freely nucleated crystals predominately have the nitrogen to aluminum direction pointing out from the nucleation surface, that is the ends of the AlN crystals facing the source are aluminum polarity.

Direct evidence from intraoperative electrocortical stimulation indicates shared and distinct speech production center between Chinese and English languages

Chinese processing has been suggested involving distinct brain areas from English. However, current functional localization studies on Chinese speech processing use mostly "indirect" techniques such as functional magnetic resonance imaging and electroencephalography, lacking direct evidence by means of electrocortical recording. In this study, awake craniotomies in 66 Chinese-speaking glioma patients provide a unique opportunity to directly map eloquent language areas. Intraoperative electrocortical stimulation was conducted and the positive sites for speech arrest, anomia, and alexia were identified separately. With help of stereotaxic neuronavigation system and computational modeling, all positive sites elicited by stimulation were integrated and a series of two- and three-dimension Chinese language probability maps were built. We performed statistical comparisons between the Chinese maps and previously derived English maps. While most Chinese speech arrest areas located at typical language production sites (i.e., 50% positive sites in ventral precentral gyrus, 28% in pars opercularis and pars triangularis), which also serve English production, an additional brain area, the left middle frontal gyrus (Brodmann's areas 6/9), was found to be unique in Chinese production (P < 0.05). Moreover, Chinese speakers' inferior ventral precentral gyrus (Brodmann's area 6) was used more than that in English speakers. Our finding suggests that Chinese involves more perisylvian region (extending to left middle frontal gyrus) than English. This is the first time that direct evidence supports cross-cultural neurolinguistics differences in human beings. The Chinese language atlas will also helpful in brain surgery planning for Chinese-speakers.

Evidence-based expert consensus on the management of primary central nervous system lymphoma in China

Primary central nervous system lymphoma (PCNSL) is a type of central nervous system restricted non-Hodgkin lymphoma, whose histopathological diagnosis is majorly large B cell lymphoma. To provide specific, evidence-based recommendations for medical professionals and to promote more standardized, effective and safe treatment for patients with PCNSL, a panel of experts from the Chinese Neurosurgical Society of the Chinese Medical Association and the Society of Hematological Malignancies of the Chinese Anti-Cancer Association jointly developed an evidence-based consensus. After comprehensively searching literature and conducting systematic reviews, two rounds of Delphi were conducted to reach consensus on the recommendations as follows: The histopathological specimens of PCNSL patients should be obtained as safely and comprehensively as possible by multimodal tomography-guided biopsy or minimally invasive surgery. Corticosteroids should be withdrawn from, or not be administered to, patients with suspected PCNSL before biopsy if the patient's status permits. MRI (enhanced and DWI) should be performed for diagnosing and evaluating PCNSL patients where whole-body PET-CT be used at necessary time points. Mini-mental status examination can be used to assess cognitive function in the clinical management. Newly diagnosed PCNSL patients should be treated with combined high-dose methotrexate-based regimen and can be treated with a rituximab-inclusive regimen at induction therapy. Autologous stem cell transplantation can be used as a consolidation therapy. Refractory or relapsed PCNSL patients can be treated with ibrutinib with or without high-dose chemotherapy as re-induction therapy. Stereotactic radiosurgery can be used for PCNSL patients with a limited recurrent lesion who were refractory to chemotherapy and have previously received whole-brain radiotherapy. Patients with suspected primary vitreoretinal lymphoma (PVRL) should be diagnosed by vitreous biopsy. PVRL or PCNSL patients with concurrent VRL can be treated with combined systemic and local therapy.

TMZ-induced PrPc/par-4 interaction promotes the survival of human glioma cells

Malignant gliomas recur even after extensive surgery and chemo-radiotherapy. Although a relatively novel chemotherapeutic agent, temozolomide (TMZ), has demonstrated promising activity against gliomas, the effects last only a few months and drug resistance develops thereafter in many cases. It has been acknowledged that glioma cells respond to TMZ treatment by undergoing G2/M arrest, but not apoptosis. Here we demonstrate a phase-specific chemotherapy resistance due to cellular prion protein (PrPc) in human glioma cells upon TMZ treatment. TMZ-induced G2/M-arrested cultures show an upregulation of PrPc expression and are more resistant, whereas G1/S-phase cells that show decreased levels of PrPc are more sensitive to apoptosis. Furthermore, an investigation into the biological significance of PrPc association with par-4 provided the first evidence of a relationship between the endogenous levels of PrPc and the resistance of glioma cells to the apoptotic effects of TMZ. Upon TMZ treatment, PrPc exerts its antiapoptotic activity by inhibiting PKA-mediated par-4 phosphorylation that are important for par-4 activation, nuclear entry and initiation of apoptosis. In context with cell cycle-dependent responses to chemotherapy, the data from this study suggest the possibility of exploiting the PrPc-dependent pathway to improve the efficacy of TMZ-based regimen for patients with gliomas.

Proteomic analysis of prolactinoma cells by immuno-laser capture microdissection combined with online two-dimensional nano-scale liquid chromatography/mass spectrometry

Background

Pituitary adenomas, the third most common intracranial tumor, comprise nearly 16.7% of intracranial neoplasm and 25%-44% of pituitary adenomas are prolactinomas. Prolactinoma represents a complex heterogeneous mixture of cells including prolactin (PRL), endothelial cells, fibroblasts, and other stromal cells, making it difficult to dissect the molecular and cellular mechanisms of prolactin cells in pituitary tumorigenesis through high-throughout-omics analysis. Our newly developed immuno-laser capture microdissection (LCM) method would permit rapid and reliable procurement of prolactin cells from this heterogeneous tissue. Thus, prolactin cell specific molecular events involved in pituitary tumorigenesis and cell signaling can be approached by proteomic analysis.

Results

Proteins from immuno-LCM captured prolactin cells were digested; resulting peptides were separated by two dimensional-nanoscale liquid chromatography (2D-nanoLC/MS) and characterized by tandem mass spectrometry. All MS/MS spectrums were analyzed by SEQUEST against the human International Protein Index database and a specific prolactinoma proteome consisting of 2243 proteins was identified. This collection of identified proteins by far represents the largest and the most comprehensive database of proteome for prolactinoma. Category analysis of the proteome revealed a widely unbiased access to various proteins with diverse functional characteristics.

Conclusions

This manuscript described a more comprehensive proteomic profile of prolactinomas compared to other previous published reports. Thanks to the application of immuno-LCM combined with online two-dimensional nano-scale liquid chromatography here permitted identification of more proteins and, to our best knowledge, generated the largest prolactinoma proteome. This enlarged proteome would contribute significantly to further understanding of prolactinoma tumorigenesis which is crucial to the management of prolactinomas.

3D-ASL perfusion correlates with VEGF expression and overall survival in glioma patients: Comparison of quantitative perfusion and pathology on accurate spatial location-matched basis

BACKGROUND

There is a need for an imaging-based tool for measuring vascular endothelial growth factor (VEGF) expression and overall survival (OS) in patients with glioma.

PURPOSE

To assess the correlation between cerebral blood flow (CBF), measured by 3D pseudo-continuous arterial spin-labeling (3D-ASL), and VEGF expression in gliomas on the basis of coregistered localized biopsy, and investigate whether CBF correlated with survival month (SM) in glioma patients.

STUDY TYPE

Prospective cohort.

SUBJECTS

Thirty-seven patients with gliomas from whom 63 biopsy specimens were obtained.

SEQUENCE

3D-ASL acquired with a 3.0T MR unit.

ASSESSMENT

Biopsy specimens were grouped as high-grade (HGG) or low-grade glioma (LGG). CBF measurements were spatially matched with VEGF expression by coregistered localized biopsies, and the CBF value was correlated with quantitative VEGF expression for each specimen. Patients' survival information was derived and connected with CBF.

STATISTICAL TESTS

Patients' OS was analyzed by Kaplan-Meier and Cox-regression methods. VEGF expression and CBF were compared in both LGG and HGG. The Spearman rank correlation was calculated for CBF and VEGF expression, SM. Significance level, P < 0.05.

RESULTS

CBF-derived 3D-ASL positively correlated significantly with VEGF expression in both LGG (31 specimens) and HGG (32 specimens), r = 0.604 (P < 0.001) and r = 0.665 (P < 0.001), respectively. LGG and HGG together gave a correlation coefficient r = 0.728 (P < 0.001). Median survival for LGG and HGG patients was 34.19 and 17.17 months, respectively (P = 0.037); CBF value negatively correlated significantly with SM with r = -0.714 (P < 0.001) regardless of glioma grade. CBF was an independent risk factor for OS with HR = 1.027 (P = 0.044), 1.028 (P = 0.010) for univariate/multivariate regression analysis.

DATA CONCLUSION

CBF determined by 3D-ASL correlates with VEGF expression in glioma and is an independent risk factor for OS in these patients.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:209-220.

Characterization of O-linked oligosaccharide biosynthesis in cultured cells using paranitrophenyl alpha-D-GalNAc as an acceptor

Aryl-N-acetyl-alpha-galactosaminides (aryl-GalNAc) are acceptor substrates for UDP-Gal:alpha-GalNAc beta 1-3 galactosyltransferase and, in vivo, aryl-GalNAc have been shown to inhibit O-linked oligosaccharide biosynthesis (Kuan et al., J. Biol. Chem. 264, 19271, 1989). Since aryl-GalNAc, appears to enter viable cells and serve as an acceptor for O-glycosylation enzymes, the recovery and characterization of the aryl-oligosaccharides from cell culture medium may reflect cellular pattems of O-glycosylation. To pursue this possibility, the following paranitrophenyl-linked oligosaccharide standards were enzymatically synthesized and characterized by 1H-NMR: Gal beta 1-3(GlcNAc beta 1-6)Gal-NAc alpha-pNp; Gal beta 1-3(Gal beta 1-4GlcNAc beta 1-6)GalNAc alpha-pNp; SA alpha 2-3Gal beta 1-3(SA alpha 2-3Gal beta 1-4GlcNAc,beta 1-6)GalNAc alpha-pNp; SA alpha 2-3Gal beta 1-3GalNAc alpha-pNp. As a model system, MDAY-D2 lymphoid tumour cells were cultured for various periods in medium containing 2 mM GalNAc alpha-pNp. The secreted aryl-oligosaccharides were separated by Biogel P2 chromatography and DEAE HPLC, followed by further fractionation of the disialyl oligosaccharides on an Ultrahydrogel HPLC column. Absorbance of the paranitrophenyl aryl constituent at 303 nm allowed detection at the 10 pmol level and provided a relatively specific means of following the oligosaccharides. MDAY-D2 cells produced disialylated aryl-oligosaccharides at a rate of 20 pmol/h/10(6) cells with a half-time of transit to the cell surface of 13.6 min, a rate consistent with their movement from the Golgi to the cell surface by bulk flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Transcortical insular glioma resection: clinical outcome and predictors

OBJECTIVE

Insular lobe gliomas continue to challenge neurosurgeons due to their complex anatomical position. Transcortical and transsylvian corridors remain the primary approaches for reaching the insula, but the adoption of one technique over the other remains controversial. The authors analyzed the transcortical approach of resecting insular gliomas in the context of patient tumor location based on the Berger-Sinai classification, achievable extents of resection (EORs), overall survival (OS), and postsurgical neurological outcome.

METHODS

The authors studied 255 consecutive cases of insular gliomas that underwent transcortical tumor resection in their division. Tumor molecular pathology, location, EOR, postoperative neurological outcome for each insular zone, and the accompanying OS were incorporated into the analysis to determine the value of this surgical approach.

RESULTS

Lower-grade insular gliomas (LGGs) were more prevalent (63.14%). Regarding location, giant tumors (involving all insular zones) were most prevalent (58.82%) followed by zone I+IV (anterior) tumors (20.39%). In LGGs, tumor location was an independent predictor of survival (p = 0.003), with giant tumors demonstrating shortest patient survival (p = 0.003). Isocitrate dehydrogenase 1 (IDH1) mutation was more likely to be associated with giant tumors (p < 0.001) than focal tumors located in a regional zone. EOR correlated with survival in both LGG (p = 0.001) and higher-grade glioma (HGG) patients (p = 0.008). The highest EORs were achieved in anterior-zone LGGs (p = 0.024). In terms of developing postoperative neurological deficits, patients with giant tumors were more susceptible (p = 0.038). Postoperative transient neurological deficit was recorded in 12.79%, and permanent deficit in 15.70% of patients. Patients who developed either transient or permanent postsurgical neurological deficits exhibited poorer survival (p < 0.001).

CONCLUSIONS

The transcortical surgical approach can achieve maximal tumor resection in all insular zones. In addition, the incorporation of adjunct technologies such as multimodal brain imaging and mapping of cortical and subcortical eloquent brain regions into the transcortical approach favors postoperative neurological outcomes, and prolongs patient survival.

Different systems in human brain are involved in presemantic discrimination of pictures as revealed by event-related potentials

It is uncertain if the several brain areas in response to presemantic picture processing are functionally homogeneous. Subjects were asked to discriminate visual stimulus pairs and event-related potentials (ERPs) were recorded from the scalp. A line-drawing picture (S1) was followed by another stimulus (S2) 600 ms later. S2 was the same as S1 in condition 1, a reversed picture of S1 in condition 2, the corresponding Chinese word in condition 3 and the syllabic alphabet of S1 in condition 4. Amplitudes of ERPs over right posterior scalp with time window from 102-180 ms after the onset of S2 in condition 1 and 2 were significantly larger than condition 3 and 4. The N2 component on the right anterolateral scalp with time window from 182-240 ms was significantly larger in condition 1 than other conditions, whereas the N2 on the left anterolateral scalp with time window from 262-350 ms in condition 2, 3 and 4 was significantly larger than condition 1. It is suggested that pictures and words are processed in different systems at the presemantic stage: repetitive and physically deviant stimuli evoke different responses in different brain regions.

Brain potentials during mental arithmetic-effects of problem difficulty on event-related brain potentials

One addend '+' symbol and another addend were presented in sequence to subjects in a monitor, and event-related brain potentials (ERPs) were recorded at the same time to examine the effect of problem difficulty (with or without carrying in solution) on ERPs. After the presentation of the second addend, N1, P1, N2, late positive complex and slow waves were recorded. The P2 amplitude at F3 site for the difficult arithmetic problems between 168 and 184 ms is larger (more positive) than that for easy problems (P < 0.05). The mean latency of P2 at F7 and P3b at F3 and F4 is significantly longer for difficult problems than that for easy ones (P < 0.05). It is suggested that prefrontal activity may be involved in the arithmetic data retrieval process. ERPs is modified to different degrees by changing the difficulty of mental arithmetic.

Expression of arachidonate 12-lipoxygenase in rat tissues: a possible role in glucagon secretion

There are three isoforms of arachidonate 12-lipoxygenase in mammals: platelet, leukocyte, and epidermal types. We found in this study that the leukocyte-type enzyme was present in rat pineal gland, lung, spleen, aorta, adrenal gland, spinal cord, and pancreas, as assessed by RT-PCR. Immunohistochemical analysis showed that the enzyme was localized in macrophages in lung and spleen, alpha-cells of pancreatic islet, zona glomerulosa cells of adrenal cortex, and neuronal cells of spinal cord and superior cervical ganglion. The presence of the 12-lipoxygenase in pancreatic alpha-cells was confirmed by glucagon staining in a consecutive section. We overexpressed the leukocyte-type 12-lipoxygenase cDNA in a glucagon-secreting alphaTC clone 6 cell line that had been established from a transgenic mouse. Glucagon secretion was stimulated by approximately twofold in the 12-lipoxygenase-expressing cells compared to the mock-transfected and original cells. The results suggest that the 12-lipoxygenase of the leukocyte type augments glucagon secretion from pancreatic islets.

Early-latency somatosensory evoked potentials elicited by electrical acupuncture after needling acupoint LI-4

The stimulating methods of prior studies on somatosensory evoked potentials (SEPs) elicited by acupoint stimulus had involved surface electrodes, while the clinical practice of acupuncture is mostly performed by inserting the acupuncture needle inside the body. Clinical observations show that there are often some special sensations when LI-4 is needled. To observe if the SEPs produced by acupoint acupuncture had a distinguishing property, we studied the SEPs elicited by electrical acupuncture after the acupuncture needle was inserted into LI-4 and its control point, and then mapped them with the 128-channel Electric Brain Signal Image system. We also compared this to SEPs by median nerve stimuli. Results showed that the most interesting finding was the marked differences of N1-P1 and N2-P2 amplitude between SEPs at LI-4 (SEP-LI) and its control point (SEP-CP), which were in the opposite direction. Marked differences were also found between latencies and amplitudes of the SEPs elicited by acupuncture and by median nerve stimulus (SEP-M). The differences between SEP-LI and SEP-CP might be due to the additional effects of the activation of nerve endings and muscle spindles in LI-4 to the SEPs formed by the activation of superficial and deep radial nerves during electrical acupuncture. The differences between SEPs to acupoint and median nerve stimuli might be mainly due to the different distances from the stimulated regions to the cerebral cortex, the diversity and the number of activated fibers.

Increased body weight in C57BL/6 female mice after exposure to ionizing radiation or 60Hz magnetic fields

PURPOSE

The purpose of this investigation was to determine whether early treatment with ionizing radiation and/or chronic magnetic field (MF) exposure affected body weight in female mice.

MATERIALS AND METHODS

Weanling C57BL/6 female mice were irradiated with four equal weekly cobalt-60 exposures (total cumulative doses: 3.0, 4.0, 5.1Gy) and/or received chronic lifetime exposure to 1.4 mT 60 Hz circularly polarized MF or ambient MF. The body weights of 2280 mice were recorded at 35 age intervals, and analysis of variance was used to compare the mean differences from baseline weights between treatment groups and sham-exposed controls.

RESULTS

A highly statistically significant effect of ionizing radiation on body weight was observed at 28 age intervals (p < or = 0.001), and for MF exposure at 10 age intervals (p < or = 0.001). During the young adult growth phase, mice exposed only to MF exhibited < or =0.5 g greater weight gain relative to sham-exposed controls (p = 0.0001). The effect of ionizing radiation alone was inversely related to dose, with the largest weight increases observed in all of the irradiated groups after 9-12 months (p = 0.0001).

CONCLUSIONS

Treatment with split-dose ionizing radiation at an early age and chronic exposure to a residential power frequency MF were found to produce small but significant increases in body weight.

Nucleolin promotes TGF-β signaling initiation via TGF-β receptor I in glioblastoma

The transforming growth factor β (TGF-β) pathway plays a key role in oncogenesis of advanced cancers, involving the non-Smad and Smad pathways. Meanwhile, nucleolin on the cell surface has been also reported to affect activation of signaling pathways. However, the effect of cell surface nucleolin on TGF-β pathway in glioblastoma is not still understood. Here, using antibodies of nucleolin and TGF-β receptor I (TβR-I), we observed blocking of either nucleolin or TβR-I inhibited the phosphorylation of CrkL, Erk1/2, and Smad2. Using nucleolin siRNA, nucleolin knockdown was also identified to suppress the expression of p-CrkL, p-Erk1/2, and p-Smad2. Furthermore, immunoprecipitation revealed the interaction between cell surface nucleolin and TβR-I on the U87 cell membrane. In addition, U87 cell wound-healing, soft-agar and MTT assay also showed si-nucleolin could obviously impair wound closure (p < 0.001), colony formation (p < 0.001) and cell growth (p < 0.001). In conclusion, nucleolin promotes and regulates the TGF-β pathway by interacting with TβR-I and is required for initiation and activation of TGF-β signaling. Thus, nucleolin could be a key factor in glioblastoma pathogenesis and considered a therapeutic target, which may also mediate more signaling pathways.