[Clinicopathologic features of delayed radiation-induced brain injury after radiotherapy for brain tumor].

OBJECTIVE: To study the clinicopathologic features of delayed radiation-induced brain injury after radiotherapy for brain tumor. METHODS: The clinical, histopathologic and immunohistochemical features of 9 cases with delayed radiation-induced injury were evaluated. RESULTS: The disease occurred from 6 months to 12 years after radiotherapy and often presented with headache and muscle weakness. Magnetic resonance imaging showed peripheral enhancing lesions with slight mass effect and surrounding edema. Microscopically, the major changes included coagulative necrosis, fibrinoid necrosis of vessels, vascular hyalinization with luminal stenosis and peripheral reactive gliosis. Immunostaining for hypoxia-inducible factors 1α was positive in reactive astrocytes. CONCLUSIONS: Delayed radiation-induced brain injury is a relatively common complication of radiation therapy. The lesion was frequently misdiagnosed as brain tumor. Correct diagnosis relies on clinical, radiologic and pathologic correlation.

[Study on intermolecular interaction between 4-aminopyridine and methacrylic acid using two dimensional FTIR spectroscopy].

A two-dimensional infrared (2D IR) correlation spectroscopy technique has been introduced to study the intermolecular interaction between 4-aminopyridine and methacrylic acid. The type and relationship of the bond between 4-aminopyridine and methacrylic acid molecule could not be characterized directly using the one-dimensional FTIR spectroscopy. On the contrary, the interactions between 4-aminopyridine and methacrylic acid molecule were determined using 2D IR correlation spectroscopy. The synchronous cross peaks exist between stretching vibrations of hydroxyl group of methacrylic acid at 1298 and 1202 cm(-1) and C=N group of 4-aminopyridine at 1531 cm(-1), and between carbonyl group of methacrylic acid at 1705 cm(-1) and N-H group of 4-aminopyridine at 3382 and 3212 cm(-1), respectively. According to the two-dimensional correlation rules, the interactions of static electricity and hydrogen bonding exist between 4-aminopyridine and methacrylic acid molecule. Such successful applications demonstrate that two-dimensional infrared correlation spectroscopy may be a convenient and effective means in the study of the intermolecular and intramolecular interaction.

[Study on effect of heating rate on thermal decomposition of HMX energetic materials by in-situ diffuse reflection FTIR spectrum].

In-situ FTIR spectroscopy is a rising and dynamic technique. This technique combines the advantages of investigation in-situ and accurate structure analysis by FTIR spectroscopy, and can detect real time chemical change in materials at different temperatures and obtain the relationship between micromechanism of materials and temperature. In the present paper, thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) heated with a rate of 5, 10, 20 and 40 degrees C x min(-1), respectively, was investigated by in-situ diffuse reflection FTIR spectroscopy. The results demonstrate that intramolecular cyclization occurs in breakage of HMX with a heating rate of 5 degrees C x min(-1), while intermolecular cyclization appears with a heating rate of 10, 20 and 40 degrees C x min(-1). With increasing temperature, the rupture rate of C-N bond is faster than that of N-N bond, which verifies that the cleavage of C-N bond is the dominant rupture form. With increasing heating rate, the decomposition beginning temperature of C-N bond increases. Eight kinds of gaseous products such as CO2, N2O, CO, NO, HCHO, HONO, NO2 and HCN were determined. The decomposition mechanism of HMX was not affected with changing heating rate.

[Study on thermal decomposition of HMX energetic materials by in-situ FTIR spectroscopy].

In-situ FTIR spectroscopy is a rising and dynamic technique. This technique, which combines the advantages of investigation in-situ and accurate structure analysis by FTIR spectsoscopy, can detect the chemical change of materials in different temperature with real time and obtain the relationship between micromechanism of materials and temperature. In the present paper, thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) heated with 5 degrees C x min(-1) was investigated by in-situ FTIR spectroscopy. The results demonstrate that C-N bond cleavage and N-N bond cleavage of HMX occur at 205 degrees C. With increasing temperature, the rupture rate of C-N bond is faster than that of N-N bond, which verifies that the cleavage of C-N bond is the dominant rupture form. The augment in tension of HMX cyclic confirms that intramolecular cyclization occurs in breakage of HMX. Eight kinds of gaseous products such as CO2, N2O, CO, NO, HCHO, HONO, NO2 and HCN were determined. According to the structure change in condensed state and gaseous products, the decomposition mechanism was deduced that HCHO, N2O, HONO and HCN were released due to the cleavage of C-N bond, and NO2 was released due to the cleavage of N-N bond.

[Application of adjustable oblique position for microendoscopic discectomy].

OBJECTIVE: To compare the adjustable oblique position with prone position in microendoscopic discectomy (MED) and to evaluate its advantages. METHODS: One hundred and twenty-eight patients who underwent MED during August 2000 and August 2002 were studied. Forty-seven cases were positioned prone, 81 cases were positioned with adjustable oblique position. Operating time, blood loss and patient endurance were recorded and compared. The airway resistance of 29 lumbar disorder patients was measured when they were positioned supine, lateral and prone respectively after general anesthesia. RESULTS: There was statistically significant difference between 2 groups in operating time, blood loss and endurance. In prone position group, when operating time lasted for more than 50 min, 75% patients felt hurt on the skin of rib arch, and 38% patients presented dizzy and nausea. And all the patients had erythema on the rib arch. In the adjustable oblique position group, 3 cases had shoulder pain after operation, and 1 case had 4 days' common poroneal nerve paralysis. The airway resistance of patients with prone position was significantly higher than those with supine and lateral positioned patients. (P < 0.05). CONCLUSION: The adjustable oblique position in MED had the following advantages: (1) Do not limit the movement of chest and help reduce intra-abdominal pressure and epidural bleeding; (2) Give the lumbar spine the largest degree of flexion and the largest interlaminar space, which prevents injury of facet joint; (3) Increase posterior intervertebral space and make disectomy easier and exposure of nerve root and nerve root canal clearer; (4) The patients feel comfortable and can adjust the position of lumbar spine and lower extremity; (5) The monitor has the same direction with doctor, and it is easy for the doctor to operate; (6) Doctor can sit during operation.

Fabrication of temperature-sensitive imprinted polymer hydrogel.

Weakly cross-linked temperature sensitive gels that memorize 4-aminopyridine molecules were designed and synthesized. The polymer gels show special selectivity, good thermo-sensitivity and reusability, which would have an enormous potential of application in drug controlled release systems.

Design of temperature sensitive imprinted polymer hydrogels based on multiple-point hydrogen bonding.

Weakly cross-linked temperature sensitive imprinted polymer hydrogels that recognize L-pyroglutamic acid (Pga) molecules via multiple-point hydrogen bonding were designed and synthesized. The amount of adsorption for Pga in imprinted hydrogels is 3-4 times higher than that in non-imprinted hydrogels. The selectivity test of imprinted polymer gels was carried out by using a series of structurally related compounds Pga, pyrrolidine, 2-pyrrolidone, L-proline as substrates. The results show that imprinted polymer gels exhibit high selectivity for Pga as compared to all the other tested substrates. The imprinted polymer hydrogels show good temperature sensitivity, special selectivity and reusability, suggesting that the polymer hydrogels would have an enormous potential for application in controlled drug release and separation field.

[Changes of neural electrophysiology properties of cauda equina in experimental lumbar spinal canal stenosis under dynamic burden].

OBJECTIVE: To study the changes of neural electrophysiology properties of cauda equina under double level compression and dynamic burdens, and to clarify the mechanisms of intermittent neurogenic claudication. METHODS: Thirty SD rats were divided into 5 groups (6 in each group). The laminectomy of L5 was performed in control group. In the experimental groups, the silicon sheets were inserted into the spinal canal of L4 and L6 to cause double level compression of cauda equina by 30%. Two hours after onset of compression, no dynamic burden was introduced in experimental group 1. Only high frequency stimulation(HFS) was introduced for 6 minutes in experimental group 2. Both HFS and additional increased compression were introduced for 6 minutes in experimental group 3. While only additional increased compression was introduced for 6 minutes in experimental group 4. After 6 minutes of dynamic burdens, all were returned to the status of static compression for another 30 minutes and then electrical examination was made. RESULTS: After 2 hours of compression, motor and sensory nerve conduction velocity (NCV) of all the four experimental groups decreased significantly (P < 0.05), but there was no significant difference between them. There was no significant change in the control group. There was no significant change of NCV in experimental group 1 during the last 30 minutes of experiment. NCV in the other three experimental groups decreased after introduction of dynamic burdens, especially in the experimental group 3. CONCLUSION: The above results showed that NCV of cauda equina decreased significantly under dynamic burdens during static compression. Two kinds of dynamic burdens introduced at the same time can cause more profound change than a single one.