Glutamatergic activities in neonatal rat spinal cord heterogeneously regulate single-fiber splanchnic nerve discharge

Kynurenic acid (KYN) is a metabolite of tryptophan and is involved in various neurological disorders. Using whole-bundle nerve recording techniques, we previously observed that applications of KYN to block endogenous ionotropic glutamate receptor activities in neonatal rat spinal cords in vitro cause a reversible fluctuation of splanchnic sympathetic nerve discharge (SND). We hypothesized that the SND fluctuation was due to a heterogeneous single-fiber response. To detail individual fiber activities, we used the so-called ‘oligofiber recordings’. Spontaneous single-fiber activities were recorded from the collagenase-dissociated splanchnic nerve fascicles. Applications of KYN increased, decreased or did not change firing rates. The heterogeneous responses in spontaneous spiking activities were confirmed by applications of APV or CNQX, suggesting an effect mediated by endogenous NMDA- or non-NMDA receptor activities. In addition to changes in firing rates, apparent drug-induced changes in firing patterns were also observed in some fiber activities. Using the oligofiber recording techniques, we confirmed a differential role of endogenous ionotropic glutamate receptor activities in regulating sympathetic outflows from the spinal cord of neonatal rats. Fine-tuning of ionotropic glutamate receptor activities in the spinal cord may serve as a simple way for heterogeneous regulation of various sympathetic-targeting tissues.     

Are newborn rat-derived neural stem cells more sensitive to lead neurotoxicity?

Lead ion (Pb(2+) ) has been proven to be a neurotoxin due to its neurotoxicity on mammalian nervous system, especially for the developing brains of juveniles. However, many reported studies involved the negative effects of Pb(2+) on adult neural cells of humans or other mammals, only few of which have examined the effects of Pb(2+) on neural stem cells. The purpose of this study was to reveal the biological effects of Pb(2+) from lead acetate [Pb (CH 3 COO) 2 ] on viability, proliferation and differentiation of neural stem cells derived from the hippocampus of newborn rats aged 7 days and adult rats aged 90 days, respectively. This study was carried out in three parts. In the first part, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT viability assay) was used to detect the effects of Pb(2+) on the cell viability of passage 2 hippocampal neural stem cells after 48-hour exposure to 0-200 μM Pb(2+) . In the second part, 10 μM bromodeoxyuridine was added into the culture medium of passage 2 hippocampal neural stem cells after 48-hour exposure to 0- 200 μM Pb(2+) , followed by immunocytochemical staining with anti-bromodeoxyuridine to demonstrate the effects of Pb(2+) on cell proliferation. In the last part, passage 2 hippocampal neural stem cells were allowed to grow in the differentiation medium with 0-200 μM Pb(2+) . Immunocytochemical staining with anti-microtubule-associated protein 2 (a neuron marker), anti-glial fibrillary acidic protein (an astrocyte marker), and anti-RIP (an oligodendrocyte marker) was performed to detect the differentiation commitment of affected neural stem cells after 6 days. The data showed that Pb(2+) inhibited not only the viability and proliferation of rat hippocampal neural stem cells, but also their neuronal and oligodendrocyte differentiation in vitro. Moreover, increased activity of astrocyte differentiation of hippocampal neural stem cells from both newborn and adult rats was observed after exposure to high concentration of lead ion in vitro. These findings suggest that hippocampal neural stem cells of newborn rats were more sensitive than those from adult rats to Pb(2+) cytotoxicity.     

A Long-Term Survival Case of a Primary Malignant Intracerebral Nerve Sheath Tumor

We report a long-term survival case of a primary malignant intracerebral nerve sheath tumor (MINST) occurring in the right frontal lobe of a 13-year old boy. After the gross total resection (GTR), we have performed radiation therapy but it recurred 50 months after the surgery, so the second GTR was performed. Later, second tumor recurrence was found 4 months after the second surgery. Subsequently the third GTR, radiotherapy, and chemotherapy were carried out. At present, the patient has been remaining alive for 77 months without evidence of tumor recurrence. According to the previous reports, the primary MINST is very rare : there are only 8 cases reported. It is also a fast-growing, invasive tumor with poor outcome. This is the first case that had no recurrence for 50 months after the surgery among the reported cases that had been followed up for more than 5 years. It is supposed that a period of recurrence free survival after GTR and low mitotic activity are associated with the patient''s prognosis. A GTR followed by adjuvant radiation therapy and chemotherapy will be recommended to patients of MINST.     

Galeal Tack-Up Sutures to Prevent Subgaleal Cerebrospinal Fluid Collection

Objective

Postoperative subgaleal cerebrospinal fluid (CSF) collection is considered as one of the common minor surgical complication which can lead to prolonged hospitalization. We introduce "galeal tack-up suture" to prevent postoperative subgaleal CSF collection.

Methods

Galeal tack-up suture consists of various surgical techniques which aim to fix galea to cranium in order to prevent CSF pooling in subgaleal space. A total of 87 patients who underwent craniotomy were divided into two groups while closing the wound : group A with galeal tack-up suture and group B with routine wound closure without galeal tack-up suture. The patients were observed for postoperative subgaleal CSF collection.

Results

Among 87 cranitomy cases, galeal tack-up suture was performed in 32 cases and routine wound closure was done in 55 cases. Postoperative subgaleal CSF collection occurred in 13 cases (15%) in which 12 cases occurred in group B patients and 1 case occurred in group A patients (p=0.026).

Conclusion

Galeal tack-up suture is an easy and effective technique in wound closure to prevent postoperative CSF collection.     

Surgical Outcomes and Complications after Occipito-Cervical Fusion Using the Screw-Rod System in Craniocervical Instability

Objective

Although there is no consensus on the ideal treatment of the craniocervical instability, biomechanical stabilization and bone fusion can be induced through occipito-cervical fusion (OCF). The authors conducted this study to evaluate efficacy of OCF, as well as to explore methods in reducing complications.

Methods

A total of 16 cases with craniocervical instability underwent OCF since the year 2002. The mean age of the patients was 51.5 years with a mean follow-up period of 34.9 months. The subjects were compared using lateral X-ray taken before the operation, after the operation, and during last follow-up. The Nurick score was used to assess neurological function pre and postoperatively.

Results

All patients showed improvements in myelopathic symptoms after the operation. The mean preoperative Nurick score was 3.1. At the end of follow-up after surgery, the mean Nurick score was 2.0. After surgery, most patients'' posterior occipito-cervical angle entered the normal range as the pre operation angle decresed from 121 to 114 degree. There were three cases with complications, such as, vertebral artery injury, occipital screw failure and wound infection. In two cases with cerebral palsy, occipital screw failures occurred. But, reoperation was performed in one case.

Conclusion

OCF is an effective method in treating craniocervical instability. However, the complication rate can be quite high when performing OCF in patients with cerebral palsy, rheumatoid arthritis. Much precaution should be taken when performing this procedure on high risk patients.     

Surgical suture assembled with polymeric drug-delivery sheet for sustained,local pain relief

Surgical suture is a strand of biocompatible material designed for wound closure, and therefore can be a medical device potentially suitable for local drug delivery to treat pain at the surgical site. However, the preparation methods previously introduced for drug-delivery sutures adversely influenced the mechanical strength of the suture itself – strength that is essential for successful wound closure. Thus, it is not easy to control drug delivery with sutures, and the drug-delivery surgical sutures available for clinical use are now limited to anti-infection roles. Here, we demonstrate a surgical suture enabled to provide controlled delivery of a pain-relief drug and, more importantly, we demonstrate how it can be fabricated to maintain the mechanical strength of the suture itself. For this purpose, we separately prepare a drug-delivery sheet composed of a biocompatible polymer and a pain-relief drug, which is then physically assembled with a type of surgical suture that is already in clinical use. In this way, the drug release profiles can be tailored for the period of therapeutic need by modifying only the drug-loaded polymer sheet without adversely influencing the mechanical strength of the suture. The drug-delivery sutures in this work can effectively relieve the pain at the surgical site in a sustained manner during the period of wound healing, while showing biocompatibility and mechanical properties comparable to those of the original surgical suture in clinical use.