Interaction of Sensory Neurons and Satellite Cells during Stimulation of Nerve Regeneration

Neuroscience and Behavioral Physiology -     

GDNF Expression in Terminal Schwann Cells Associated With the Periodontal Ruffini Endings of the Rat Incisors During Nerve Regeneration

The terminal Schwann cells (TSCs) which play crucial roles in regeneration of the periodontal Ruffini endings (RE) exhibit immunoreaction for glial cell line‐derived neurotrophic factor (GDNF). However, no information is available regarding the role of GDNF in the periodontal RE during nerve regeneration. This study was undertaken to examine the changes in GDNF expression in the rat periodontal RE following transection of the inferior alveolar nerve (IAN) using immunohistochemistry for GDNF and S‐100 protein, a marker for the TSCs. We additionally investigated the changes in expression of GDNF in the trigeminal ganglion (TG) at protein and mRNA levels. A transection to IAN induced a disappearance of the TSCs from the alveolus‐related part (ARP), followed by a migration of spindle‐shaped cells with S‐100 but without GDNF immunoreactions into the tooth‐related part (TRP) by postoperative (PO) week 2. At PO week 2, GDNF immunoreacted cellular elements increased in number in the ARP although the spindle‐shaped cells without GDNF reaction remained in the TRP. After PO week 4, many GDNF‐positive TSCs appeared in the ARP though the spindle‐shaped cells vanished from the TRP. A real time RT‐PCR analysis demonstrated the highest elevation of GDNF mRNA in the TG at PO week 2. These findings suggested the involvement of this molecule in the maturation and maintenance of the periodontal RE during regeneration. Taken together with our previous and current studies, it appears that the regeneration of the periodontal RE is controlled by multiple neurotrophins in a stage‐specific manner. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.     

Evaluation of Mechanical Properties of Human Mesenchymal Stem Cells During Differentiation to Smooth Muscle Cells

Human mesenchymal stem cells (hMSCs) are multipotent cells appropriate for a variety of tissue engineering and cell therapy applications. Mechanical properties of hMSCs during differentiation are associated with their particular metabolic activity and regulate cell function due to alternations in cytoskeleton and structural elements. The objective of this study is to evaluate elastic and viscoelastic properties of hMSCs during long term cultivation in control and transforming growth factor-β₁ treatment groups using micropipette aspiration technique. The mean Young’s modulus (E) of the control samples remained nearly unchanged during 6 days of cultivation, but that of the test samples showed an initial reduction compared to its relevant control sample after 2 days of treatment by biological growth factor, followed by a significant rise after 4 and 6 days. The viscoelastic creep tests showed that both instantaneous and equilibrium moduli significantly increased with the treatment time and reached to maximum values of 622.9 ± 114.2 and 144.3 ± 11.6 Pa at the sixth day, respectively, while increase in apparent viscosity was not statistically significant. Such change of mechanical properties of hMSCs during specific lineage commitment contributes to regenerative medicine as well as stem-cell-based therapy in which biophysical signals regulate stem cell fate.     

Stem Cells in Liver Regeneration and Their Potential Clinical Applications

Stem cells constitute a population of “primitive cells” with the ability to divide indefinitely and give rise to specialized cells under special conditions. Because of these two characteristics they have received particular attention in recent decades. These cells are the primarily responsible factors for the regeneration of tissues and organs and for the healing of lesions, a feature that makes them a central key in the development of cell-based medicine, called Regenerative Medicine. The idea of wound and organ repair and body regeneration is as old as the mankind, reflecting the human desire for inhibiting aging and immortality and it is first described in the ancient Greek myth of Prometheus. It is of interest that the myth refers to liver, an organ with remarkable regenerative ability after loss of mass and function caused by liver injury or surgical resection. Over the last decade there has been an important progress in understanding liver physiology and the mechanisms underlying hepatic development and regeneration. As liver transplantation, despite its difficulties, remains the only effective therapy for advanced liver disease so far, scientific interest has nowadays been orientated towards Regenerative Medicine and the use of stem cells to repair damaged liver. This review is focused on the available literature concerning the role of stem cells in liver regeneration. It summarizes the results of studies concerning endogenous liver regeneration and stem cell experimental protocols. Moreover, this review discusses the clinical studies that have been conducted in humans so far.     

Segmental Analysis of the Vestibular Nerve and the Efferents of the Vestibular Complex

Use of a segmental approach in the study of vestibular centers in the hindbrain improves morphological and functional understanding of this region controlled by Hox genes, among other molecular determinants. Here, we review accrued data about segmental organization of vestibular afferents and efferents. Inner ear-originated vestibular fibers enter the hindbrain, together with auditory ones, through the alar plate of rhombomere 4, then branch into descending and ascending branches to reach appropriate vestibular nuclei along the vestibular column. Classical vestibular nuclei (superior, lateral, medial, and inferior) originate in eight successive rhombomeric segments, which suggests internal subdivisions correlated with distinct connections and functions. The vestibular projection neurons identified for various targets aggregate in discrete groups, which correlate topographically either with rhombomeric units, or with internal subdivisions within them. Each vestibular projection system (e.g., vestibulo-spinal, vestibulo-ocular, vestibulocerebellar) has a characteristic ipsilateral/contralateral organization. Comparing them as a connective mosaic in different species shows that various aspects of this segmental connective organization are conserved throughout evolution in vertebrates. Furthermore, certain genes that control the development of the rhombomeric units in the hindbrain may determine, among other aspects, the specific properties of the different neuronal subpopulations related to their axonal navigation and synaptogenesis. Anat Rec, 302:472–484, 2019. © 2018 Wiley Periodicals, Inc.     

Epidemiologic and Clinical Features of Campylobacter Enteritis Before and During COVID-19 in Korea

BackgroundWith the increase in meals at home due to coronavirus disease 2019 (COVID-19), the pattern and incidence of enteritis seemed to change. Some types of enteritis, such as Campylobacter enteritis, appear to have increased. Our study aimed to evaluate the change in the trend of enteritis, especially Campylobacter enteritis, before COVID-19 (2016–2019) and at the present time during COVID-19 in South Korea.MethodsWe analyzed data from the Health Insurance Review and Assessment Service. From 2016 to 2020, the International Classification of Diseases codes related to enteritis were examined to distinguish bacterial and viral enteritis and the trends of each were analyzed. The aspects of enteritis, before and after the COVID-19 outbreak, were compared.ResultsBoth bacterial and viral enteritis declined in all age groups from 2016 to 2020 (P < 0.001). In 2020, the reduction rate of viral enteritis was higher than that of bacterial enteritis. However, unlike other causes of enteritis, even after COVID-19, Campylobacter enteritis increased in all age groups. An increase of Campylobacter enteritis in 2020 was particularly noticeable in children and adolescents. The prevalence of viral and bacterial enteritis was higher in urban areas than in rural areas (P < 0.001). Campylobacter enteritis was more common in the rural areas (P < 0.001).ConclusionAlthough the prevalence of bacterial and viral enteritis have decreased in COVID-19, Campylobacter enteritis has increased in all age groups and in rural areas compared to urban areas. Recognizing that the trend of Campylobacter enteritis before and during COVID-19 is helpful for future public health measures and interventions.