Stretched inverse opal colloid crystal substrates-induced orientation of fibroblast.

Recently, there has been increasing interest in studying the interaction between mammalian cells and nanometer-sized structures. However, the effect of nanostructures on cell behavior, such as cell morphology and alignment, is still largely unknown. Inverse opal colloid crystal substrates, which can be stretched to produce nano-scale pore structures of different degrees of orientation, serve as a convenient model system to study the effect of nanotopography on cell morphology and cell alignment. In this work, we fabricated inverse opal colloidal crystal films that were either unstretched or stretched to three, four or six times their original length, producing pore structures of increasing degree of orientation. Human dermal fibroblast-fetal (HDF-f) cells were seeded and cultured on these four types of substrates. The results from fluorescence microscopy and scanning electron microscopy indicated that cells showed the highest degree of alignment when cultured on inverse opal colloid crystal films that were stretched the most (six times original length). The results also demonstrated that the orientation of nanostructures could affect both the morphology and growth direction of fibroblasts. The ability to control the direction of cell growth through the engineering of nanostructures could have important applications in tissue engineering, especially for tissues with anisotropic structures, such as cardiac muscle, blood vessel, tendon and ligament.

Reversible valence tautomerism induced by a single-shot laser pulse in a cobalt-iron Prussian blue analog.

Reversible valence tautomeric conversion induced by a single-shot laser pulse (8 ns duration) with a photon excitation energy of 2.38 eV has been observed in Na0.36Co1.32Fe(CN)(6).5.6H(2)O. A photoswitching process with accompanying magnetization and color changes was successfully achieved within the pulse duration at high temperature (above 200 K) in a thermal hysteresis loop. This unusual photoeffect originates from an optical charge transfer between Fe and Co atoms and evolves due to a cooperative interaction among the local photoexcited sites.

Gene expression and apoptosis in the spinal cord neurons after sciatic nerve injury.

To demonstrate a dependence of spinal cord motoneurons on the communication with their targets, the expression of immediate early gene c-fos and neurotrophin genes in the lumbar (L3-L6) spinal cord neurons was examined in Sprague-Dawley rats (male > or = 9-weeks-old) with unilateral sciatic nerve transection. Using in situ hybridization, we detected the expression of c-fos mRNA in the motoneurons of the spinal cord segments within 45 min to 3 h of peripheral nerve transection (n = 4 in each time point). The expression of c-fos mRNA was also correlated positively with the expression of Fos antigen using immunohistochemistry, while no change in calbindin and parvalbumin antigens were noted. The expression of BDNF mRNA increased at 90 min after sciatic nerve transection. However, no detectable enhancement in the expression of NGF mRNA was observed. DNA fragmentation in neurons was observed using the incorporation of digoxigenin-dUTP by terminal transferase into 3'-OH terminals of DNA fragments in the ipsilateral section of the spinal cords 48h after nerve injury. Nuclei that exhibited DNA fragmentation were not observed in the spinal cord of the control animals. Lastly, we observed that the majority of astrocytes did not have DNA fragmentation. Because the detection of DNA fragmentation using this assay is one of early detections of apoptosis or programmed cell death, the result suggested we could detect early cell death in spinal cord, and indicated a target dependence of the neurons in the spinal cord after transection of sciatic nerve.

[1354 freshmen's dental investigation]

1354 freshmen have been investigated to discover the relationship between dental diseases and environments,living habits and personal sanitary conditions,because urban young men like sweet foods and snacks,the incidence of caries is greater in the cities than in the country,more people with tetracycline discolored tooth live in urban areas than in the rustic ones,which is due to dense living conditions, vulnerable to respiratory organs disease,medical conditions and convenience of taking tetracycline when ill;on the other hand,gingivitis is more common within the country students than within the city students,for those students from the country are used to brush their tooth after adolescence and usually have more dental calculus which is harmful to the gingiva.More than half of the investigated freshmen are ignorant of correct method of brushing and oral health and that is important factors of high rate of dental disease,according to the above reasons,the effective measures should educated to prevent dental disease.

[Participate of nitric oxide participate in hypoxic regulation of cerebrovascular tension].

Making use of nitric oxide synthesase (NOS) inhibitor Nw-nitric-oxide-L-arginine (L-NNA), the effect of NO and the pressence of endothelial cell on hypoxia-induced vascular dilatation was studied with new-born calve basilar artery. The experimental results show that L-NNA can attenuate the hypoxia-induced vascular dilatation, but the magnitude of attenuation is smaller than that of constriction caused by L-NNA on normoxic calve basilar artery. Under hypoxia, the vascular dilatation of endothelial cell denuded artery is smaller than that of endothelial cell intact artery; the difference between them is approximate by the same as the change caused by L-NNA on endothelial call intact artery. After destroying the endothelial cell, L-NNA has no obvious effect on the vascular tension. These results suggest that NO and endothelial cell are involved in hypoxia-induced vascular dilaxation.

[Regulation of nitric oxide on cerebral blood flow].

It has discovered recently that nitric oxide (NO) is an important activating factor to blood vessels. Nitric oxide activates the soluble guanylate cyclase in the vascular smooth muscle. It is clear that nitric oxide does not act only on systemic blood vessels under physiological conditions. However, in hypoxia and hypercapnia, there are many controversies about the regulation of nitric oxide on cerebral blood vessels. In this paper, we have reviewed the latest advances in this field.

[Regulative role of hypocapnia on cerebral blood flow under hypoxia in rats].

The experiments were performed on urethane anesthetized and artificially ventilated SD rats using a gascous mixture of 11.9% O2 and 88.1% N2. The PaCO2 was regulated by changing the volume of ventilation. The items to be studies are: (1) The correlation between hypocapnia and CBF under hypoxia; (2) the value of PaCO2 that can keep CBF at the level of hypoxic adapters; (3) the CBF change during a 5 h hypoxia-hypocapnia and (4) the reactivity of isolated basilar artery strips on hypoxia-hypocapnia. The results showed: (1) There was a significant correlation between the degree of hypocapnia and CBF under hypoxia. The correlation curve was steeper than that of normoxia. (2) When the ventilation was controlled at 25.5% above normoxic control value and the PaCO2 was about 2/3 of normoxic level under hypoxia, the CBF is near to the level of normoxic control. (3) When the PaCO2 was controlled at 2/3 of normoxic level, the CBF could still keep at the level of normoxic control for 5 h. (4) The tension of artery strip was decrease under hypoxia-normocapnia but increased under hypoxia-hypocapnia. Artery stripes with or without endotheliocyte make no difference in their tension changes due to changes of O2-CO2 tension.

[Measurement of rCBF by hydrogen gas clearance with lower H2 concentration in rats].

H2 clearance method in measuring regional cerebral blood flow (rCBF) on animals has been widely used in experimental research. It was found that 3% H2 which is lower than the lower concentration limit guarded against occurrence of explosion could be mixed with any concentration ratio of N2 to O2 without causing transient hypoxia as often found by inhaling 100% H2 and thus made clearance measurement more accurate and safe. Comparison studies between inhaling 100% H2 and 3% H2 as well as inhaling 3% H2 for 1-1.5 min and 3% H2 for 5 min were undertaken. Repeated measurements of 3% H2 clearance for 1.5 min further showed that clearance test using low H2 concentration for short term periods reflected better the rCBF of experimental animals.

[Effects of hyperoxia and hypoxia on cerebral circulation and intracranial pressure].

Oxygen is an active stimulus of cerebral blood vessels. Hyperoxia can induce decrease in cerebral blood flow and intracranial pressure, but hypoxia increases cerebral blood flow and intracranial pressure. Both hyperoxia and hypoxia play an opposite role in cerebral circulation and intracranial pressure. Recent studies of cerebral circulation and intracranial pressure under hyperoxia and hypoxia were reviewed in the present paper with special reference to the correlation between cerebral circulation and intracranial pressure.

Experimental study of intracranial hypertension.

The present investigation was made in rabbits and cats with perfusing mock cerebrospinal fluid into fourth ventriculus to produce experimental diffusion intracranial hypertension. Under normoxia and acute hypoxia conditions, the changes in cerebral blood flow, spontaneous electrocortical activity, direct cortical response, electrocardiogram, blood pressure and cerebral perfusion pressure were measured as intracranial hypertension caused by step elevation and abrupt elevation; at the same time, the relationship mentioned above was also investigated. The experimental results are very important to clinic treatment and to the patients suffering from anoxia with intracranial hypertension.

The influence of acute and chronic hypoxia on the electroencephalogram of human body.

This report deals with the study of electroencephalograms of 36 subjects who inhaled hypoxic mixture at the sea level (PO2 is as that at 7000 m above sea level) or in a hypobaric chamber with rapid decompression (as that at 5000-7500 m above sea level) and of 46 subjects who reached high altitude area (5000-8600 m) under chronic hypoxia. The characters of the EEGs at rest during photic stimulation, hyperventilation and convalescence after hypoxia were compared in two experiments. The result of experiments shows that in the same individual, the severer the hypoxia, the more obvious the changes on the EEGs. At the same altitude, acute hypoxia causes more obvious changes on the EEGs than chronic one does, but its speed of recovery is faster than that of chronic hypoxia. Under chronic hypoxia, the changes on the EEGs caused by hyperventilation are slighter than those under acute hypoxia. When photic stimulation is given, there is temporary appearance of alpha waves on the EEGs featuring slow waves under acute and chronic hypoxia. The possible mechanism of changes on the EEGs under acute and chronic hypoxia is also analyzed in this report.