Estimation of Acute Toxicity of Ammonium Sulphate to the Fresh Water Catfish,Heteropneustes fossilis——Ⅰ.Analysis of LC_(50) Values Determined by Various Methods

The acute toxic effects of ammonium sulphate to fresh-water catfish, Heteropneustes fossilis (H.fossilis) have been studied by determining LC50 values with 95% confidence limits, by the graphic method, the logistic method, the Spearman and Karber method and the trimmed Spearman-Karber method. The trimmed Spearman-Karber method was found the most ideal for ammonium salt toxicity test. The flaws in the trimmed Spearman-Karber method are also discussed.

Interventional effect of laser acupoint radiation on the expression of Nissl body and brain-derived neurotrophic factor in newborn rat models with ischemic/hypoxic cerebral injury

BACKGROUND： Some researches report that He-Ne laser can activate function of erythrocytes and increase content of blood and oxygen via bio-stimulating effect; therefore, it suspects that laser radiation at Baihui and Dazhui can partially increase blood circulation for oxygen-supplying content of brain and improve functional status of neurons. OBJECTIVE： To verify the effects of laser radiation at Baihui and Dazhui on the expression of Nissl body of brain tissue neurons and brain-derived neurotrophic factor （BDNF） in newborn rats with ischemic/hypoxic cerebral injury. DESIGN： Randomized controlled animal study. SETTING： Department of Neurological Histochemistry, Xianning University. MATERIALS： Forty Wistar rats of 7 - 8 days old, weighing 15 - 20 g and of both genders, were selected from Wuhan Experimental Animal Center. All the rats were randomly divided into sham operation group （n =8）, model group （n =16） and radiation group （n = 16）. The experimental animals were disposed according to ethical criteria. BDNF kit was provided by Wuhan Boster Bioengineering Co., Ltd. METHODS： The experiment was carried out in the Department of Neurological Histochemistry, Xianning University from April 2005 to October 2006. Rats in the radiation group and model group were performed with ligation of left common carotid artery, recovered at room temperature for 1 - 6 days, maintained in self-made hypoxic cabin under normal pressure and injected mixture gas （0.05 volume fraction of 02 and 0.92 volume fraction of N2） for 2 hours. In addition, rats in the sham operation group were treated with separation of left common carotid artery but not ligation and hypoxia. Rats in the model group were not given any treatment; while, rats in the radiation group were exposed with He-Ne laser of 63.28 nm in the wave length at Baihui and Dazhui acupoints on the second day after ischemia-hypoxia. The radiation was given for 10 minutes per day and once a day. Ten days were regarded as a course and the rats were exposed for 2 courses in total. At 20 days after routine breeding, left hemisphere tissues of rats in the three groups were collected for staining of Nissl body and immunohistochemistry of BDNF. MAIN OUTCOME MEASURES： Nissl body staining in left hemisphere tissue and expression of immune positive cells of BDNF. RESULTS： All 40 rats were involved in the final analysis. （1） Nissl body staining： Neuronal cytoplasm of brain tissue was full of blue granule Nissl bodies in the sham operation group; while, Nissl body in neuronal cytoplasm in the model group was stained slightly and had a certain degree of degeneration; meanwhile, there were a lot of blank area in ischemic region. Nissl body in neuron cytoplasm was gradually recovered in the radiation group and relieved as compared with that in the model group. （2） Positive cells of BDNF： Number of immune positive cells of BDNF which were ligated in lateral cerebral hemisphere of rats in the model group was higher than that in the sham operation group （P 〈 0.05）; while, BDNF expression in the radiation group was increased as compared with that in the model group （P 〈 0.05）. CONCLUSION： After laser acupoint radiation, Nissl body is increased and BDNF expression is also increased. This suggests that laser acupoint radiation has neuroprotective effect on brain tissue after ischemia-hypoxia injury.

Estimation of Acute Toxicity of Ammonium Sulphate to the Fresh Water Catfish,Heteropneustes fossilis Ⅱ.A Histopathological Analysis of the Epidermis

The toxicity of 4000 ppm (96 h LC50 value) of the inorganic fertilizer ammonium sulphate on the epidermis of Heteropneustesfossilis (H.fossilis) at different intervals of time has been studied. The destruction induced by the ammonium salt is massive. Secretion of a copious amount of slime from the goblet mucous cells leading to their exhaustion and/or shedding and subsequent disappearance is perhaps the first reaction to the toxicity of the irritant. Later, the polygonal epithelial cells of the outermost layer show cyclic stages of necrosis and sloughing followed by their regeneration and repair. The contents of the club cells show enormous shrinkage and condensation with subsequent replacement of their areas with a hazy substance. In the earlier stages of exposure, regeneration takes place quickly, side by side with the degenerative changes at different stages of experimentation. Later after 8 to 10 d, the degenerative changes slow down and the epidermis appears identical to that of the normal skin. Goblet mucous cells also showed several cyclic increases followed by decreases in number and activity.

Acute Toxic Effects of Mercuric Chloride on the Mucocytes of the Epithelial Lining of the Accessory Respiratory Organ and Skin of the Air Breathing Catfish Heteropneustes fossilis（Bloch）^1

Acute toxicity of 0.3 ppm mercuric chloride on the mucocytes of the branchial diverticulum and skin of Heteropneustes fossilis results in cyclic increases followed by decreases in the density, area occupancy and volume at different intervals of exposure. The alterations in the two tissues do not follow the same path perhaps due to different modes of action of the mercury salt: The skin comes under direct contact effects, while the branchial diverticulum may be affected by hormonal imbalance caused by a stress effect.

Histopathological Changes in the Epidermis of the Air Breathing Catfish Heteropneustes fossilis Exposed to Sublethal Concentration of Mercuric Chloride

Histopathological alterations induced by the sublethal concentration of (0.03 ppm) mercuric chloride solution on the epidermis of the fresh-water catfish Heteropneuates fossilis have been studied. It induces slow but significant histopathological changes in the various cellular components of the epidermis. It induces vacuolization, necrosis and pycnosis of the nuclei of the epithelial cells which subsequently shed. Loosening of epithelial cells of the outermost and middle layers following degeneration of the intercellular material and widened intercellular spaces is another important alteration. Prolonged mercury treatment also causes a gradual decrease in staining intensity for sulphated glycosaminoglycans in the outer border of the most superficial layer epithelial cells. The glandular elements (club cells and mucocytes) also get affected, showing cyclic degeneration followed by regeneration.

In situ hybridization of neuropeptide Y gene expression in the endothelial cells of human umbilical blood vessels

In recent years, the endothelial cell has become the popular subject of many scientificresearch fields such as cardiovascular and cancer pathology. The results reported up to nowindicate that the endothelial cell has the complex funtion in synthesis and metabolism, andtherefore plays an important role in the regulation of vascular function. Burnstock’s labfirst observed that many kinds of vasoactive substances are localized in the endothelial