[Study on the clinical significance and correlation of arginase-1 and inducible nitric oxide synthase expression in hepatocellular carcinoma].

Objective: To investigate the clinical significance and correlation of arginase 1 (Arg-1) and inducible nitric oxide synthase (iNOS) expression in hepatocellular carcinoma (HCC). Methods: The expression of Arg-1and iNOS in 146 cases of hepatocellular carcinoma tissues and corresponding adjacent tissues was detected by immunohistochemistry. The clinicopathological characteristics and the correlation between the expressions and prognosis were determined by chi square test, Spearman's rank correlation, Kaplan-Meier survival analysis and Cox regression analysis. Results: The positive rates of Arg-1 and iNOS were 18.7% (23/123) and 37.0% (54/146), respectively, which was significantly lower than the adjacent tissues [100%(146/146) and 93.8% (137/146)] and the difference was statistically significant (χ (2) = 212.521, P < 0.01, χ (2) = 104.276, P < 0.01). There was a positive correlation between the both expression (r = 0.331, P < 0.01). Arg-1 low expression was correlated with preoperative serum alpha-fetoprotein (AFP) level, tumor size, differentiation degree, histological types and Edmondson's grade. iNOS low expression was correlated with the differentiation degree and Edmondson's grade (P < 0.05). Kaplan Meier survival analysis showed that in patients with recurrence-free survival (RFs), Arg-1 (+) group > Arg-1 (-) group and Arg-1 (+) iNOS (+) group > Arg-1 (+) iNOS (-) group > Arg-1 (-) iNOS (-) group (P < 0.05). Cox multivariate analysis showed that age, tumor size, Edmondson's grade, vascular tumor emboli were significantly correlated with RFs (P < 0.05). Conclusion: There is a positive correlation between Arg-1 and iNOS expressions in HCC, and both may reflect the HCC malignant degree. The reduced/absent expression of both may participate in the occurrence and development of HCC. The combined detection of Arg-1 and iNOS on HCC may have certain significance for the judgment of differentiation degree and prognosis.

Efficacy of slightly acidic electrolyzed water on the microbial safety and shelf life of shelled eggs.

This study evaluated the efficacy of slightly acidic electrolyzed water (SAEW) for the inactivation of Salmonella Enteritidis and Escherichia coli on shelled eggs as well as studied the shelf life and internal quality attributes (i.e., weight loss, Haugh unit, yolk index, albumen pH, and yolk pH) of eggs during storage at 25°C. The decontamination test egg samples (freshly laid) were inoculated and immersed for 1, 2, 3, and 4 min in each treatment (i.e., SAEW, acidic electrolyzed water, NaClO solution, and sterile deionized water) at available chlorine concentrations (ACCs) of 10, 18 and 26 mg/L. The storage test eggs (freshly laid) were immersed for 3 min in 4 treatments (i.e., SAEW, acidic electrolyzed water, NaClO solution, and no treatment) and stored for 30 D at 25°C. The effects of the SAEW on microbiological qualities and freshness parameters were investigated. Decontamination of eggs with SAEW showed an equivalent or higher bactericidal effect compared to other treatments. A complete inactivation of S. Enteritidis and E. coli on the surface of shelled egg samples resulted from treatment with SAEW at an ACC of 26 mg/L for 3 and 4 min, respectively. Almost all of the egg quality parameters investigated in the present study were significantly (P < 0.05) affected by the storage time. As storage time increased, the yolk index and Haugh unit value decreased, and weight loss, albumen pH, and yolk pH increased. However, SAEW treatment minimized weight loss (5.52%) and preserved the albumen and yolk quality better than no treatment at 25°C. Relative to acidic electrolyzed water and NaClO solution, the advantages of SAEW are reduced corrosion of egg surfaces and potentially less water and CO2 escaping from eggshell pores. The results highlight the promising use of SAEW to enhance the microbial safety and to extend the shelf life of shelled eggs. Future combined methods with SAEW and other treatments are also needed.

[Study on the correlation between work-related musculoskeletal disorders and work ability among nurses at three level general hospital in Xinjiang].

Objective: To investigate the correlation between work-related musculoskeletal disorders (WMSDs) and work ability (WA) among nurses in Xinjiang. Methods: A total of 1 873 nursing staff in the Departments of Internal Medicine, Surgery, Emergency and ICU Department, Operating Room and Supply Room of 6 Grade 3 General Hospitals in Xinjiang Beijiang Region were randomly selected by means of random sampling, and revised Nordic National Musculoskeletal Disorders Standard Questionnaire and Work Ability Index Scale were used to evaluate the status of nursing WMSDs and WA. Results: (1) The symptom incidence of work-related musculoskeletal disorders among nursing staff in the past year was 77.42%; The highest symptom incidence in all parts of the body was waist, neck, shoulder and back, and the symptom incidence was 63.59%, 59.80%, 47.78% and 37.32%, respectively; (2) The total score of nursing staff's work ability was (35.91±5.143) ; The proportion of "poor" , "middle" , "good" and "excellent" were 5.23%, 47.41%, 41.43% and 5.93% respectively; (3) The total working capacity of the sick group was (35.11±5.044) , The working ability of the non-diseased group was (38.64±4.507) , The difference between the two groups was statistically significant (t=13.773, P<0.01) ; There was a significant difference in the level of work ability between the two groups (z=-12.335, P<0.01) ; The working ability of "poor" and medium in the injury group was significantly higher than that of the non injury group, while the working ability was "better" and "excellent" than that of the non injury group; (4) The working ability of nursing staff of different age in WMSDs injury group was lower than that in non injury group, the difference was statistically significant (P<0.01) ; There was a negative correlation between the working ability of the injury group and the length of service, that is, with the increase of the length of service, the working ability index decreased (P<0.01) ; There was a positive correlation between the working ability of the non injury group and the length of service, that is, with the increase of the length of service, the work ability index increased gradually, but the correlation was not statistically significant (r=0.063, P=0.195) ; (5) The working ability of nursing staff of different departments in WMSDs injury group was lower than that in non injury group, the difference was statistically significant (P<0.01) . (6) Multiple linear regression analysis showed that the factors influencing the working ability of nursing staff were: past medical history, WMSDs disease, length of service and night shift frequency; Conclusion: The symptom incidence of WMSDs was high among nurses; Work Ability at a moderate level; work-related musculoskeletal disorders is associated with reduced ability of nursing staff; work-related musculoskeletal disorders are associated with reduced working capacity of nursing staff.

[Evaluation of ergonomic load of clinical nursing procedures].

Objective: To evaluate the ergonomic load of clinical nursing procedures and to provide evidence for the prevention and management of work-related musculoskeletal disorders (WMSDs) in nurses. Methods: Based on the nursing unit characteristics and the common departments involving patient-turning procedures, 552 nurses were selected from 6 clinical departments from July to September, 2016. The ergonomic load of four types of patient-turning procedures, i.e., turning the patient's body, changing the bed linen of in-bed patients, moving patients, and chest physiotherapy, was evaluated by the on-site inspectors and self-evaluated by the operators using the Quick Exposure Check. The exposure value, exposure level, and exposure rate of WMSDs were assessed based on the procedure-related physical loads on the back, shoulders/arms, wrists/hands and neck, as well as the loads from work rhythm and work pressure. Results: All surveyed subjects were females who were aged mostly between 26-30 years (49.46%) , with a mean age of 29.66±5.28 years. These nurses were mainly from the Department of Infection (28.99%) and Spine Surgery (21.56%) . There were significant differences in the back, shoulders/arms, neck, work rhythm, and work pressure scores between different nursing procedures (F=16.613, 5.884, 3.431, 3.222, and 5.085, respectively; P<0.05) . Patient-turning nursing procedures resulted in high to intermediate physical load in nurses. Procedures with high to low level of WMSDs exposure were patient turning (72.69%) , bed linen changing (67.15%) , patient transfer (65.82%) , and chest physiotherapy (58.34%) . In particular, patient turning was considered as very high-risk procedure, whereas others were considered as high-risk procedures. Conclusion: Patient-turning nursing procedures result in high ergonomic load in the operators. Therefore, more focus should be placed on the ergonomics of the caretakers and nurses.

[Current status of work-related musculoskeletal disorders in nurses in Xinjiang, China].

Objective: To investigate the prevalence of work-related musculoskeletal disorders (WMSDs) in nurses in Xinjiang, China, to analyze the influencing factors for the development of WMSDs, and to provide a reference for the prevention and treatment of WMSDs in nurses. Methods: Stratified cluster sampling was used to randomly select 8 422 nurses in 8 tertiary hospitals and 4 secondary hospitals in Xinjiang from January to October, 2015. A questionnaire survey was performed to investigate the prevalence of WMSDs in nurses from departments of internal medicine, surgery, gynecology, pediatrics, emergency, and intensive care and operating rooms and analyze related influencing factors. Results: A total of 3 000 questionnaires were distributed, and 2 851 questionnaires were returned, resulting in a recovery rate of 95.00%. In the nurses who participated in the survey, the prevalence of WMSDs was 78.58%. As for different body parts, the prevalence of WMSDs was 63.36% in the waist, 61.79% in the neck, 52.52% in the shoulder, 41.83% in the back, 35.56% in the knees, 33.35% in the ankles, 26.02% in the wrists, 23.41% in the hip, and 17.62% in the elbows. There were significant differences in the prevalence of WMSDs across the nurses with different ages and working years (χ2=28.29 and 27.73, both P<0.01) , and the prevalence of WMSDs tended to increase with the increasing age and working years (χ2=22.94 and 17.56, both P<0.01) . The results of multivariate logistic regression analysis showed that sex, working years, intensive care/emergency, outpatient service, surgical anesthesia, weekly working hours, physical condition, and fatigue in work were risk factors for WMSDs in nurses. Conclusion: In the nurses in Xinjiang, the prevalence of WMSDs in the neck, shoulder, back, and waist is high, and nurses with different ages, working years, departments, sexes, physical conditions, and weekly working hours have varying degrees of risk of WMSDs.

[Identification and verification of the candidate proteins that interact and collaborate with ATF3 in inhibiting hepatocarcinogenesis].

OBJECTIVE: To identify and verify proteins that interact and collaborate with ATF3 in inhibiting hepatocarcinogenesis. METHODS: Immunoprecipitation (IP), co-IP and protein spectrum analysis were used to identify the protein which interacted with ATF3 in HepG2. Immunohistochemistry (IHC) and Western blot (WB) were used to detect the expression pattern of ATF3 and its candidate interacting proteins in liver tissue. RESULTS: The protein expression differences were detected by IP in two HepG2 groups. The experimental group was infected by lentiviral vector with ATF3 over-expression and the control group was infected by mock-vehicle. Several protein bands with expression diversity were analyzed by protein spectrum, which revealed several candidate proteins that may be related with ATF3. Peptide sequences were analyzed by Mascot software and NCBI database. Combined with the existing literature and our study results, Gelsolin (GSN) was identified as a protein closely interacting with ATF3 and confirmed by co-IP, IHC and WB. CONCLUSIONS: GSN is identified and verified as an interacting protein with ATF3. ATF3 may function as a suppressor of liver cancer via protein-protein interactions with Gelsolin.

A new trend of genotype distribution of hepatitis B virus infection in southeast China (Fujian), 2006-2013.

HBV genotypes have specific geographical distributions and can serve as epidemiological markers. Accumulated data have shown that the major HBV genotypes in China are B and C. Here, the HBV genotypes were examined from 6817 blood samples, which were collected from patients with chronic HBV infection in Fujian Province during 2006-2013; genotype B was identified in 3384 patients (49·6%), while genotype C was identified in 3430 patients (50·3%). The percentage of patients infected with genotype C gradually increased with age from 39·5% (patients aged 50 years), reaching a peak of 67·3% in the 45-50 years age group. These results clearly demonstrate that the genotype distribution of HBV in Fujian Province has significantly changed in recent years with almost equal numbers of genotype B and genotype C infections existing in the entire patient population, while higher incidence of genotype C infection exists in older patients, but genotype B is no longer dominant in the Fujian area as previously reported.

Risk factors for recurrent Clostridium difficile infection in hematopoietic stem cell transplant recipients.

BACKGROUND: Recurrent Clostridium difficile infection (CDI) represents a significant burden on the healthcare system and is associated with poor outcomes in hematopoietic stem cell transplant (HSCT) patients. Data are limited evaluating recurrence rates and risk factors for recurrence in HSCT patients. METHODS: HSCT patients who developed CDI between January 2010 and December 2012 were divided into 2 groups: non-recurrent CDI (nrCDI) and recurrent CDI (rCDI). Risk factors for rCDI were compared between groups. Rate of recurrence in HSCT patients was compared to that in other hospitalized patients. RESULTS: CDI was diagnosed in 95 of 711 HSCT patients (22 rCDI and 73 nrCDI). Recurrence rates were similar in HSCT patients compared with other hospitalized patients (23.2% vs. 22.9%, P > 0.99). Patients in the rCDI group developed the index case of CDI significantly earlier than the nrCDI group (3.5 days vs. 7.0 days after transplant, P = 0.05). On univariate analysis, patients with rCDI were more likely to have prior history of CDI and neutropenia at the time of the index CDI case. Neutropenia at the time of the index CDI case was the only independent predictor of rCDI (78.8 vs. 34.8%, P = 0.006) on multivariate analysis. CONCLUSIONS: The rate of rCDI was similar between HSCT and other hospitalized patients, and the majority of patients developed the index case of CDI within a week of transplantation. Neutropenia at the index CDI case may be associated with increased rates of rCDI.

A novel RING finger protein, Znf179, modulates cell cycle exit and neuronal differentiation of P19 embryonal carcinoma cells.

Znf179 is a member of the RING finger protein family. During embryogenesis, Znf179 is expressed in a restricted manner in the brain, suggesting a potential role in nervous system development. In this report, we show that the expression of Znf179 is upregulated during P19 cell neuronal differentiation. Inhibition of Znf179 expression by RNA interference significantly attenuated neuronal differentiation of P19 cells and a primary culture of cerebellar granule cells. Using a microarray approach and subsequent functional annotation analysis, we identified differentially expressed genes in Znf179-knockdown cells and found that several genes are involved in development, cellular growth, and cell cycle control. Flow cytometric analyses revealed that the population of G0/G1 cells decreased in Znf179-knockdown cells. In agreement with the flow cytometric data, the number of BrdU-incorporated cells significantly increased in Znf179-knockdown cells. Moreover, in Znf179-knockdown cells, p35, a neuronal-specific Cdk5 activator that is known to activate Cdk5 and may affect the cell cycle, and p27, a cell cycle inhibitor, also decreased. Collectively, these results show that induction of the Znf179 gene may be associated with p35 expression and p27 protein accumulation, which lead to cell cycle arrest in the G0/G1 phase, and is critical for neuronal differentiation of P19 cells.

Compulsive exercise acutely upregulates rat hippocampal brain-derived neurotrophic factor.

This study was to examine the effects of treadmill exercise on the expression of brain-derived neurotrophic factor (BDNF) in rat hippocampus. After 1-wk treadmill familiarization, animals in exercise groups received a 4-wk exercise training or an acute exercise. They were sacrificed 2 h or 2 d after exercise and their hippocampal BDNF mRNA and protein levels were determined. We demonstrated that 1) hippocampal BDNF mRNA and protein levels were both elevated in response to exercise training at 2 h after the last run but not after 2 d; 2) an acute moderate exercise (1 or 3 d) increased BDNF protein levels; 3) acute severe exercise increased BDNF protein and mRNA levels in animals under a familiarization regimen, while suppressed the BDNF mRNA level in rats without treadmill familiarization, paralleling the stress effect of immobilization/water exposure. We conclude that compulsive treadmill exercise with pre-familiarization acutely upregulates rat hippocampal BDNF gene expression.

Utilization of Drosophila eye to probe the functions of two mammalian serine/threonine kinases, Snk and HsHPK.

Here we report a quick functional analysis of two mammalian serine/threonine kinases, a serum inducible kinase (Snk) and Homo sapiens hepatoma protein kinase (HsHPK), using Drosophila eye as a model system. We generated transgenic fly lines carrying constructs of both kinases under control of the GAL upstream activating sequence (UAS). Each UAS line was then crossed to a line in which GAL4 expression was driven by one of the following promoters, eyeless (ey), glass or decapentaplegic. Thus, different kinase mutants can be ectopically expressed in a promoter-dependent manner. We observed that the ectopic expression of either the wild-type or active form of Snk driven by the glass promoter resulted in a rough-eye phenotype. Nevertheless, the ectopic expression of HsHPK under the control of the ey promoter resulted in a small-eye phenotype. The results of this study demonstrated that ectopic expression of these two mammalian genes could be achieved by the regulation of Drosophila promoters. In addition, the effects of these ectopically expressed genes on eye development could be an implication of their functions with respect to cell proliferation and differentiation. Thus, Drosophila eye, with the powerful genetic tools and vast information on eye development available, can be a useful system to probe the functions of mammalian genes in the postgenome era.

Identification and characterization of a SET/NAP protein encoded by a brain-specific gene, MB20.

A new member of the NAP/SET gene family, named MB20, was isolated from a mouse brain cDNA library by virtue of its CAG trinucleotide repetitive sequence and a brain-specific gene expression pattern. The complementary DNA sequence predicted an open reading frame of 545 amino acids, with four copies of an 11-amino-acid direct repeat. The consensus sequence for these repeats, PKE-P--K-EE, is present in the largest subunit of murine neurofilament (NF-H). The MB20 protein sequence is homologous to nucleosome assembly proteins of several species, and its C-terminus is homologous to SET proteins. Immunoblot analysis revealed that MB20 protein is expressed in the brain. Transient transfection and immunofluorescence microscopy demonstrated that MB20 is distributed in the cytoplasm as well as in the nucleus. Deletion of the N-terminal end imparts the complete localization of MB20 protein to the nucleus. The ability of MB20 to bind histone proteins was analyzed by sucrose gradient sedimentation and by retention of histone proteins by immobilized MB20 protein. On the basis of its expression pattern, predicted sequence, and protein properties, we propose that MB20 plays a unique role in modulating nucleosome structure and gene expression during brain development.

A misexpression screen identifies genes that can modulate RAS1 pathway signaling in Drosophila melanogaster.

Differentiation of the R7 photoreceptor cell is dependent on the Sevenless receptor tyrosine kinase, which activates the RAS1/mitogen-activated protein kinase signaling cascade. Kinase suppressor of Ras (KSR) functions genetically downstream of RAS1 in this signal transduction cascade. Expression of dominant-negative KSR (KDN) in the developing eye blocks RAS pathway signaling, prevents R7 cell differentiation, and causes a rough eye phenotype. To identify genes that modulate RAS signaling, we screened for genes that alter RAS1/KSR signaling efficiency when misexpressed. In this screen, we recovered three known genes, Lk6, misshapen, and Akap200. We also identified seven previously undescribed genes; one encodes a novel rel domain member of the NFAT family, and six encode novel proteins. These genes may represent new components of the RAS pathway or components of other signaling pathways that can modulate signaling by RAS. We discuss the utility of gain-of-function screens in identifying new components of signaling pathways in Drosophila.

Impaired memory retention and decreased long-term potentiation in integrin-associated protein-deficient mice.

Previously, we have demonstrated that integrin-associated protein (IAP) mRNA level is approximately fourfold higher in rats showing good retention performance (600 sec) than rats showing poor retention performance (< 80 sec) in an inhibitory avoidance learning paradigm. In the present study, we have used the gene-targeted IAP-deficient mice to further investigate the role of IAP involved in memory formation and hippocampal long-term potentiation (LTP) in vivo. Results revealed that there was a significant impairment in memory retention and a significant reduction in the magnitude of LTP in IAP-deficient mice when compared with the wild-type and heterozygote mice, whereas the wild-type and heterozygote animals did not show marked differences on these measures. Furthermore, the impairment in retention performance of IAP-deficient mice was not due to different sensitivities of these animals to the electric shock. When we examined locomotor activity and rotarod treadmill performance, no differences were observed among these three groups of animals either. Western blot analysis confirmed the lack of IAP protein in IAP-deficient mice, whereas IAP expression was similar in both the wild-type and heterozygote controls. These results together demonstrate that IAP plays an important role in the process of memory formation and synaptic plasticity in mice.

Hepatocyte growth factor stimulates the growth and activates mitogen-activated protein kinase in human hepatoma cells.

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes and various epithelial cells. Unexpectedly, it has been reported to inhibit the growth of hepatoma cells in vitro. To clarify this phenomenon, we examined the effects of recombinant baculovirus-expressed HGF on the growth of 6 human hepatoma cell lines. The growth of Hep3B and HepG2 cells was markedly stimulated to 1.8- and 1.7-fold, respectively, PLC/PRF/5 to 1.4-fold, and SK-Hep-1 to 1.2-fold in a dose-dependent manner under HGF concentrations below 20 ng/ml. Neither HuH-7 nor HCC36 were affected. None of these cells were inhibited. All these cells expressed c-Met, the membrane receptor for HGF, and their c-Met would be activated to be phosphorylated upon addition of HGF. They also contained the ERK2 subgroup of mitogen-activated protein kinases (MAPKs). When HGF was added, their ERK2 would also be phosphorylated. The extent of ERK2 phosphorylation was partially correlated to their growth response to HGF. In conclusion, HGF could stimulate the growth of certain human hepatoma cells, probably through activation of c-Met and MAPKs.

From mosquito to man: identification of a novel protein kinase, HsHPK, which is highly expressed in human hepatoma tissues.

Protein kinases play an important role in the signaling pathway of growth factors in most of the higher organisms. During the study of protein kinase profiles of mosquitoes using RT-PCR and degenerate primers for consensus catalytic domain motifs to amplify protein kinase genes, we have noticed that a novel mosquito kinase, AaPK-38, shares a stretch of amino acids identical to the corresponding domain in Tousled gene of Arabidopsis thaliana that is required for leaf and flower development. A 2.1-kb cDNA encoding human HsHPK gene, which is a homolog of AaPK-38, was isolated from human testis cDNA library. This cDNA contains an open reading frame of 563 amino acids, with a complete kinase domain in its carboxyl terminus. The expressed Flag-tagged HsHPK was shown to have kinase activity based on in vitro autophosphorylation. Northern blot analysis revealed that human HsHPK mRNA is most abundant in testes, much less in heart and skeletal muscle and almost undetectable in liver and lung. Finally, we found that the expression of HsHPK in 4 out of 6 human hepatoma tissues is much higher than that in the adjacent normal counterpart. This result suggests HsHPK may play a role in the development of human hepatoma.

Expression of integrin-associated protein gene associated with memory formation in rats.

The present study has adopted the PCR differential display method to identify cDNA clones associated with memory formation in rats. The one-way inhibitory avoidance learning task was used as the behavioral paradigm. Total RNA isolated from the hippocampus of poor-memory (<80 sec) and good-memory (600 sec) rats 3 hr after training was used for comparison. Three cDNA fragments corresponding to different spliced forms of integrin-associated protein (IAP) mRNA were found to be differentially expressed in the hippocampus of good-memory rats. Quantitative reverse transcription-PCR revealed approximately four fold higher of IAP mRNA level in good-memory rats. This result was confirmed further by in situ hybridization analysis, and the major difference was in the dentate gyrus. It has been demonstrated that this difference in IAP mRNA expression is not attributable to different sensitivities of individual rats to electric shock. Rapid amplification of cDNA ends obtained the full-length IAP cDNA, which is 1192 bp in length excluding the poly(A+) tail. The IAP mRNA expression was significantly upregulated by NMDA and amphetamine injections to the dentate gyrus of the hippocampus. On the other hand, injection of antisense oligonucleotide complementary to the IAP transcript markedly impaired memory retention in rats and decreased the amplitude and slope of EPSP in the in vivo long-term potentiation paradigm. These results together suggest that IAP gene expression plays an important role in memory formation and synaptic plasticity in rat hippocampus.

An anteroposterior Dorsal gradient in the Drosophila embryo.

Dorsoventral (DV) patterning of the Drosophila embryo is initiated by a broad Dorsal (Dl) nuclear gradient, which is regulated by a conserved signaling pathway that includes the Toll receptor and Pelle kinase. We investigate the consequences of expressing a constitutively activated form of the Toll receptor, Toll(10b), in anterior regions of the early embryo using the bicoid 3' UTR. Localized Toll(10b) products result in the formation of an ectopic, anteroposterior (AP) Dl nuclear gradient along the length of the embryo. The analysis of both authentic dorsal target genes and defined synthetic promoters suggests that the ectopic gradient is sufficient to generate the full repertory of DV patterning responses along the AP axis of the embryo. For example, mesoderm determinants are activated in the anterior third of the embryo, whereas neurogenic genes are expressed in central regions. These results raise the possibility that Toll signaling components diffuse in the plasma membrane or syncytial cytoplasm of the early embryo. This study also provides evidence that neurogenic repressors may be important for the establishment of the sharp mesoderm/neuroectoderm boundary in the early embryo.