Biology subjects

Tan, H.

Publications and source records attributed to Tan, H..

96 records · Page 6Linked to original sources

bioRxiv2018

De novo aging-related meganeurites: alteration of NADPH diaphorase positivity in the sacral spinal cord of the aged dog

The aging-related changes of NADPH-diaphorase (NADPH-d) in the spinal cord were studied in aged dogs. At all levels of the spinal cord examined, NADPH-d activities were present in neurons and fibers in the superficial dorsal horn, dorsal commissure and in neurons around the central canal. In addition, the sympathetic autonomic nucleus in the thoracic and rostral lumbar segments exhibited prominent NADPH-d cellular staining whereas the sacral parasympathetic nucleus (SPN) in the sacral segments was not well stained. Interestingly, we found abundant NADPH-d positive enlarged-diameter fibers termed megaloneurite, which characteristically occurred in the aged sacral segments, distributed in the dorsal gray commissure (DGC), lateral collateral pathway (LCP) the lateral fasciculi and the central canal compared with the cervical, thoracic and lumbar segments. The dense, abnormal NADPH-d megaloneurites occurred in extending from dorsal entry zone through lamina I along with the lateral boundary of the dorsal horn to the region of the SPN. These fibers were prominent in the S1-S3 segments but not in adjacent segments L5-L7 and Cx1 or in thoracolumbar segments and cervical segments. Double staining with GFAP, NeuN, CGRP, MAP2 and Iba1, NADPH-d megaloneurite colocalized with vasoactive intestinal peptide. Presumably, the megaloneurites may represent, in part, visceral afferent projections to the SPN and/or DGC. The NADPH-d megaloneurites in the aged sacral spinal cord indicated some anomalous changes in the neurites, which might account for a disturbance in the aging pathway of the autonomic and sensory nerve in the pelvic visceral organs.

neuroscience↗

bioRxiv2018

Pan-cancer analysis on microRNA-mediated gene activation

While microRNAs (miRNAs) were widely considered to repress target genes at mRNA and/or protein levels, emerging evidence from in vitro experiments has shown that miRNAs can also activate gene expression in particular contexts. However, this counterintuitive observation has rarely been reported or interpreted in in vivo conditions. We systematically explored the positive correlation between miRNA and gene expressions and its potential implications in tumorigenesis, based on 8375 patient samples across 31 major human cancers from The Cancer Genome Atlas (TCGA). Results indicated that positive miRNA-gene correlations are surprisingly prevalent and consistent across cancer types, and show distinct patterns than negative correlations. The top-ranked positive correlations are significantly involved in the immune cell differentiation and cell membrane signaling related processes, and display strong power in stratifying patients in terms of survival rate, demonstrating their promising clinical relevance. Although intragenic miRNAs generally tend to co-express with their host genes, a substantial portion of miRNAs shows no obvious correlation with their host gene due to non-conservation. A miRNA can upregulate a gene by inhibiting its upstream suppressor, or shares transcription factors with that gene, both leading to positive correlation. The miRNA/gene sites associated with the top-ranked positive correlations are more likely to form super-enhancers compared to randomly chosen pairs, suggesting a potential epigenetics mechanism underlying the upregulation. Wet-lab experiments revealed that positive correlations partially remain in the in vitro condition. Our study provides the field with new perspectives on the critical role of miRNA in gene regulation and novel insights regarding the complex mechanisms underlying miRNA functions, and reveals the clinical significance of the potential positive regulation of gene expression by miRNA.

bioinformatics↗

bioRxiv2018

Decoding voluntary movements and postural tremor based on thalamic LFPs for closed-loop stimulation for essential tremor

High frequency deep brain stimulation (DBS) targeting motor thalamus is an effective therapy for essential tremor (ET). However, conventional continuous stimulation may deliver unnecessary current to the brain since tremor mainly affects voluntary movements and sustained postures in ET. We recorded LFPs from the motor thalamus, surface electromyographic (EMG) signals and/or behavioural measurements in seven ET patients during temporary lead externalization after the first surgery for DBS when they performed different voluntary upper limb movements and in nine more patients during the surgery, when they were asked to lift their arms to trigger postural tremor. We show that both voluntary movements and postural tremor can be decoded based on features extracted from thalamic LFPs using a machine learning based binary classifier. This information can be used to close the loop for DBS so that stimulation could be delivered on demand, without the need for peripheral sensors or additional invasive electrodes.

neuroscience↗

bioRxiv2018

Establishment of baseline sensitivity of Rhizoctonia solani to thifluzamide in corn and its field application

In recent years, banded leaf sheath blight in corn has become an important disease in corn that seriously affects quality and yield. This paper aims to evaluate the sensitivity of Rhizoctonia solani to thifluzamide in corn, to clarify the effect of seed coating using a thifluzamide suspension agent on safety and physiological indicators and to determine banded leaf sheath blight in corn control effectiveness in the field, thereby providing a basis for the application of thifluzamide suspension agent as a seed coating. In this study, the thifluzamide sensitivity of 102 strains of R. solani in corn in different regions of Shandong was determined using the mycelial growth rate method, and the average half-maximal effective concentration value (EC50) was 0.086{+/-}0.004 g/mL. The sensitivity was consistent with a continuous and skewed normal distribution, and the sensitivity distribution frequency exhibited a continuous, unimodal curve, indicating that thifluzamide had strong inhibitory activity on the mycelial growth of R. solani in corn. The impacts of using a thifluzamide suspension agent for seed coating on safety and physiological indicators as well as the control effect in corn were evaluated by combining seed coating, an indoor pot test, and a field trial. The root activities under 24 g a.i. 100 kg-1 seed and 12 g a.i. 100 kg-1 seed were found to increase by 78.01% and 77.40%, respectively, compared with that under the blank control; the chlorophyll content of corn increased most significantly at a dosage of 24 g a.i. 100 kg-1, which was a 32.32% increase compared to the blank control. Thifluzamide (FS) could significantly increase the hundred-grain weight of corn and the per-plot yield. Among the examined dosages, 24 g a.i. 100 kg-1 seed had the most significant treatment effect, with the hundred-grain weight increasing by 12.47% and the yield rate increasing by 15.72% compared to the control in 2016, Simultaneously, the hundred-grain weight increasing by 13.44% and the yield rate increasing by 14.11% compared to the control in 2017. Three dosages of 24% thifluzamide (FS) increased the emergence rate and seedling growth of corn to varying extents. The field control effectiveness against banded leaf sheath blight in corn was best at the dosage of 24 g a.i. 100 kg-1 seed for seed dressing with thifluzamide (FS); in 2016 and 2017, the control effects in the small bell stage, large bell stage, tasseling and pollen-shedding stage, silking stage, milk-ripening stage, and wax-ripening stage were 100%, 66.73%, 52.8%, 67.81%, 68.48%, and 62.68% (2016), respectively, and 74.97%, 63.17%, 50.90%, 53.60%, 61.42%, and 55.88% (2017). These results indicated that thifluzamide had enormous potential for controlling banded leaf sheath blight in corn.

pathology↗

bioRxiv2018

Drosophila R8 photoreceptor cell subtype specification requires Notch and hibris.

Cell differentiation and cell fate determination in sensory systems are essential for stimulus discrimination and coding of environmental stimuli. Color vision is based on the differential color sensitivity of retinal photoreceptors, however the developmental programs that control photoreceptor cell differentiation and specify color sensitivity are poorly understood. In Drosophila melanogaster, there is evidence that the color sensitivity of different photoreceptors in the compound eye is regulated by inductive signals between cells, but the exact nature of these signals and how they are propagated remains unknown. We conducted a genetic screen to identify additional regulators of this process and identified a novel mutation in the hibris gene. hibris encodes an irre cell recognition module protein (IRM). These immunoglobulin super family cell adhesion molecules include human neph and nephrin (NPHS1). hibris is expressed dynamically in the developing Drosophila melanogaster eye and loss-of-function mutations give rise to a diverse range of mutant phenotypes including disruption of the specification of R8 photoreceptors cell diversity. The specification of blue or green sensitivity in R8 cells is also dependent upon Notch signaling. We demonstrate that hibris is required within the retina, non-cell autonomously for these effects, suggesting an additional layer of complexity in the signaling process that produces paired expression of opsin genes in adjacent R7 and R8 photoreceptor cells.\n\nAuthor SummaryAs humans, our ability to distinguish different colors is dependent upon the presence of three different types of cone cell neurons in the retina of the eye. The cone cells express blue, green or red absorbing visual pigments that detect and discriminate between these colors. The principle of color discrimination by neurons \"tuned\" to different colors is an evolutionarily conserved specialization that occurs in many different animals. This specialization requires 1) visual pigments that detect different colors and 2) a developmental program that regulates the expression of these pigments in different types of cells. In this study we discovered that the fruit fly (Drosophila melanogaster) gene hibris is required for the developmental program that produces blue sensitive neurons in the fly retina. When we over-expressed hibris throughout the developing retina, extra blue sensitive cells were produced. These results demonstrate that if there is not enough hibris, too few blue sensitive cells form, but if there is too much hibris, too many blue sensitive cells form. Finally, we discovered that the hibris gene does not act in color sensitive neurons of the retina themselves. This surprising discovery suggests that hibris may influence development of the retina in a completely new and different way.

developmental biology↗

bioRxiv2018

Radiogenomics-based Risk Prediction of Glioblastoma Multiforme with Clinical Relevance

GBM is the most common and aggressive primary brain tumor. Although the TMZ-based radiochemotherapy improves overall GBM patients survival, it also increases the frequency of false positive post-treatment magnetic resonance imaging (MRI) assessments for tumor progression. Pseudoprogression is a treatment-related reaction with an increase in contrast-enhancing lesion size at the tumor site or resection margins which mimics tumor recurrence on MRI. Accurate and reliable prognostication of GBM progression is urgently needed in the clinical management of GBM patients. Clinical data analysis indicates that the patients with PsP had superior overall and progression-free survival rates. In this study, we aimed to develop a prognostic model to evaluate tumor progression potential of GBM patients following standard therapies. We applied a dictionary learning scheme to obtain imaging features of GBM patients with PsP or TTP from the Wake dataset. Based on these radiographic features, we then conducted radiogenomics analysis to identify the significantly associated genes. These significantly associated genes were then used as features to construct a 2YS logistic regression model. GBM patients were classified into low-and high-survival risk groups based on the individual 2YS scores derived from this model. We tested our model using an independent TCGA dataset and found that 2YS scores were significantly associated with the patients overall survival. We further used two cohorts of the TCGA data to train and test our model. Our results show that 2YS scores-based classification results from the training and testing TGCA datasets were significantly associated with the overall survival of patients. We also analyzed the survival prediction ability of other clinical factors (gender, age, KPS, normal cell ratio) and found that these factors were not related or weakly correlated with patients survival. Overall, our studies have demonstrated the effectiveness and robustness of the 2YS model in predicting clinical outcomes of GBM patients after standard therapies.

bioinformatics↗