鹿茸多肽对胎大鼠脑神经干细胞体外诱导分化的实验研究

目的　探讨鹿茸多肽对胎大鼠脑神经干细胞体外分化的影响。　方法　从E12～ 14d的Wistar大鼠脑中分离扩增获得大量神经干细胞后 ,加入不同浓度的鹿茸多肽 ,观察其对胚胎神经干细胞分化的影响 ,并通过免疫组织化学染色检测神经干细胞分化为神经元和星形胶质细胞的状况。　结果　 5 0 μg L组分化细胞总数与对照组相比有显著性差异 (P <0 0 1) ;5 0 μg L、10 0 μg L、2 0 0 μg L组神经元特异烯醇化酶 (NSE)阳性率与对照组相比有显著性差异 (P <0 0 1) ,并呈一定的剂量依赖性。　结论　鹿茸多肽在体外可明显促进神经干细胞向神经元分化 ,为鹿茸多肽应用于神经系统损伤性疾病的治疗提供了实验依据。     

Nucleotide sequence of RNA segment 3 of the avian influenza A/FPV/Rostock/34 and its comparison with the corresponding segment of human strains A/PR/8/34 and A/NT/60/68

The nucleotide sequence of RNA segment 3 of A/FPV/Rostock/34 (H7N1), an avian strain of influenza A virus, has been determined from a cloned DNA copy. Segment 3 codes for the PA polypeptide and the sequence specifies an acidic polypeptide of 716 amino acid residues. Comparison of the sequence with the corresponding segment of two human strains A/PR/8/34 and A/NT/60/68 indicates significant divergence of the avian sequence from the human sequences at the nucleotide level. At the amino acid level there is considerably greater homology between the avian and human strains. This presumably reflects a constraint on divergence of the PA polypeptide imposed by a common functional requirement of PA in all influenza virus strains.     

Chemically modified tetracycline (CMT)-3 inhibits histamine release and cytokine production in mast cells: possible involvement of protein kinase C

Objective: To find novel inhibitors of mast cell function we have studied the effect of a potent, non-antimicrobial, chemically modified tetracycline, CMT-3 or COL-3, on key functions of mast cells.Methods and Results: In the presence of 25 μM CMT-3, the 48/80-induced histamine release from rat serosal mast cells was inhibited significantly, to 43.0 ± 7.3% of control. Similarily, the activation-induced secretion of TNF-α and IL-8 by HMC-1 cells were decreased in the presence of 25 μM CMT-3 to 13.5 ± 4.1% and 9.7 ± 1.1% of control, respectively. CMT-3 did not cause intracellular accumulation of TNF-α but instead it reduced the expression of TNF-α mRNA in HMC-1 cells. Moreover, CMT-3 was found to significantly inhibit the protein kinase C (PKC) activity with IC₅₀ value of 31 μM. CMT-3 inhibited effectively both human recombinant PKCalpha and PKCdelta isoforms. In comparison to doxycycline, CMT-3 was more effective as an inhibitor of both cytokine production and PKC activity.Conclusions: Considering the central role of PKC in mast cell activation, PKC inhibition could, at least partially, explain the observed inhibitory effects of CMT-3. The inhibition of the key proinflammatory functions of mast cells by CMT-3 suggests its potential clinical usefulness in the treatment of allergic and inflammatory disorders.Received 18 February 2005; returned for revision 7 March 2005; accepted by A. Falus 21 April 2005     

A new method for assaying adhesion of cancer cells to the greater omentum and its application for evaluating anti-adhesion activities of chemically synthesized oligosaccharides

A new ex vivo method for assaying adhesion of cancer cells to the greater omentum has been developed using mouse greater omentum and [³H]labelled human gastric and mouse colorectal cancer cells. Since the adhesion rates were found to increase up to 18 h and labelled cells seemed to be stable during the period, the present method could be useful for investigating adhesion of cancer cells to the greater omentum, which must occur at the first step of the peritoneal dissemination. The adhesion of cancer cells to the greater omentum was inhibited by a series of chemically synthesized oligosaccharides and Galβ1,3[3OMeGalβ1,4GlcNAcβ1,6]αBn was found to be the best inhibitor. The anti-tumor effect of this novel tetrasaccharide in vivo was shown in preliminary experiments using Balb/c mice and colon26 cells.     

Reactivity of a monoclonal antibody produced to the histidine-rich protein of Plasmodium lophurae with Plasmodium falciparum

Monoclonal antibodies were produced against the histidine-rich protein of Plasmodium lophurae and tested for reactivity with Plasmodium falciparum antigens. One anti-histidine-rich protein monoclonal antibody showed immunological cross-reactivity with polypeptides of P. falciparum synthesized in vivo and in vitro.     

Types of nerves in the enteric nervous system

The enteric nervous system is one of the three divisions of the autonomic nervous system, the others being the sympathetic and parasympathetic. In contrast to the other divisions, it can perform many functions independently of the central nervous system. It consists of ganglionated plexuses, their connections with each other, and nerve fibres which arise from the plexuses and supply the muscle, blood vessels and mucosa of the gastrointestinal tract. The enteric nervous system contains a large number of neurons, approximately 10⁷ to 10⁸. About ten or more distinct types of enteric neurons have been distinguished on electrical, pharmacological, histochemical, biochemical and ultrastructural grounds as well as on the basis of their modes of action. Both excitatory and inhibitory nerves supply the muscle and there are inhibitory and excitatory interneurons within the enteric plexuses. There are also enteric nerves which supply intestinal glands and blood vessels, but these receive less emphasis in this commentary.Correlations between groups of neurons defined on different criteria are poor and in many cases the physiological roles of the nerves are not known. The functions of noradrenergic nerves which are of extrinsic origin are reasonably well understood, but cholinergic nerves in the intestine are the only intrinsic nerves for which both the transmitter and to some extent the functions are known. In the case of non-cholinergic, non-noradrenergic enteric inhibitory nerves, the functions are understood but the transmitter is yet to be determined, both adenosine 5′-triphosphate and vasoactive intestinal polypeptide having been proposed. Other nerves have been defined pharmacologically (non-cholinergic excitatory nerves to neurons and muscle, intrinsic inhibitory inputs to neurons, and enteric, non-cholinergic vasodilator nerves) and histochemically (intrinsic amine-handling neurons and separate neurons containing peptides: substance P, somatostatin, enkephalins, vasoactive intestinal polypeptide, gastrin cholecystokinin tetrapeptide, bombesin, neurotensin and probably other peptides). Little is known of the functions of these nerves, although a number of proposals which have been made are discussed.     

Regionally defective colonization of the terminal bowel by the precursors of enteric neurons in lethal spotted mutant mice

In order to gain insight into the process of colonization of the bowel by the neural crest-derived precursors of enteric neurons, the development of the enteric nervous system was examined in lethal spotted mutant mice, a strain in which a segment of bowel is congenitally aganglionic. In addition, nerve fibers within the ganglionic and aganglionic zones of the gut of adult mutant mice were investigated with respect to their content of acetylcholinesterase, immunoreactive substance P, vasoactive intestinal polypeptide and serotonin, and their ability to take up [³Hserotonin. In both the fetal gut of developing mutant mice and in the mature bowel of adult animals abnormalities were limited to the terminal 2 mm of colon. The enteric nervous system in the proximal alimentary tract was indistinguishable from that of control animals for all of the parameters examined. In the terminal bowel, the normal plexiform pattern of the innervation and ganglion cell bodies were replaced by a coarse reticulum of nerve fibers that stained for acetylcholineserase and were continuous with extrinsic nerves running between the colon and the pelvic plexus. These coarse nerve bundles contained greatly reduced numbers of fibers that displayed substance P- and vasoactive intestinal polypeptide-like immunoreactivity, but a serotonergic innervation was totally missing from the aganglionic bowel. During development, acetylcholineserase and uptake of [³Hserotonin appeared in neural elements in the foregut of mutant mice on the 12th day of embryonic life (E12), about the same time these markers appeared in the forgut in normal mice. By day E14, neurons expressing one or the other marker were recognizable as far distally as about 2 mm from the anus. The appearance of neurons in segments of gut grown for 2 weeks as expiants in culture was used as an assay for the presence of neuronal progenitor cells in the segments of fetal bowel at the time of explantation. Both acetyl- cholinesterase activity and uptake of [³Hserotonin developed in neuronsin vitro in expiants of proximal bowel between days E10 and E17. At all times, however, the terminal 2mm of mutant but not normal fetal gut gave rise to aneuronal cultures. In some mutant mice rare, small, ectopically-situated pelvic ganglia were found just outside aganglionic segments of fetal colon. Uptake of [³Hserotonin, normally a marker for intrinsic enteric neurites, was found in these ganglia.The experiments suppport the hypothesis that the terminal 2 mm of the gut in lethal spotted mutant mice is intrinsically abnormal and thus cannot be colonized by the precursors of enteric neurons. The defect seems to be specific in that both cells and processes of intrinsic enteric neurons, including all serotonergic and most peptidergic neurites, seem to be excluded from the abnormal region while extrinsic nerve fibers, including sympathetic and sensory axons, are able to enter the aganglionic zones. Since examination of neural progenitor cells has failed to reveal a significant proximo-distal displacement of these cells through the enteric tube during development of the murine bowel, a defect in the migration of precursor cells down the alimentary tract to the terminal gut seems unlikely to be substantially involved in the pathogenesis of aganglionosis. This conclusion is supported by the normal enteric nervous system in proximal regions of the mutant gut and the presence of enteric type neurons outside of, but at the same level as the aganglionic region.     

Localization of vasoactive intestinal polypeptide in penile erectile tissue and in the major pelvic ganglion of the rat

Vasoactive intestinal polypeptide was localized by immunocytochemical techniques in the major pelvic ganglion and penile erectile tissue of the rat. Vasoactive intestinal polypeptide fibers were concentrated in penile crura with the density of innervation decreasing distally. The helicine arteries were very densely innervated while fewer fibers surrounded the deep artery of the penis. Intrinsic smooth muscle of the cavernous bodies received a moderate supply of vasoactive intestinal polypeptide immunoreactive fibers. Dorsal vascular structures, including the deep dorsal vein were innervated by vasoactive intestinal polypeptide fibers. Vasoactive intestinal polypeptide immunoreactive cell bodies were found in the major pelvic ganglion, concentrated on one end of the ganglion. Rectrograde studies with a dye injected into the penile crura indicated that neurons in major pelvic ganglion projected to the penis. Combined dye and immunofluorescent studies showed that all the dye-labeled neurons were immunoreactive for vasoactive intestinal polypeptide.

It is concluded that all vascular beds in the penis of the rat are innervated by vasoactive intestinal polypeptide fibers and that the extent of the innervation is related to the occurrence of smooth muscle. Neurons in the major pelvic ganglion probably are the main source of vasoactive intestinal polypeptide fibers to the penis.     

Localization of [Met5]- and [Leu5]-enkephalin-like immunoreactivity in nerve terminals in human paravertebral sympathetic ganglia

Both [Leu⁵]- and [Met⁵]-enkephalin have been localized immunohistochemically in nerve fibres and in small, intensely fluorescent cells of adult human sympathetic ganglia. The nerve fibres showing enkephalin-like immunoreactivity formed a network varying in density around the sympathetic neurons, some being closely related to the perikarya. No labelled neuronal cell bodies were found. No structures within the ganglion were labelled after reaction with antibodies to vasoactive intestinal polypeptide, adrenocorticotrophin or substance P. No differences between the distributions of [Leu⁵]-and [Met⁵]-enkephalin-like immunoreactivities were found.The physiological roles of enkephalins are still unknown, but it is possible that they might act as neurotransmitters or neuromodulators in the human sympathetic nervous system.     

Pancreatic endocrine cells in Bufo bufo: immunocytochemistry and ultrastructure

The endocrine pancreas of the toad consists of rounded islets of various sizes embedded in the exocrine tissue. Isolated cells are also present. At least 4 types of endocrine cell are distinguishable by shape, size and electrondensity of the secretory granules as well as by their immunoreactivity with different antisera: insulin, somatostatin, pancreatic polypeptide, and glucagon cells. Insulin cells can be divided into 2 types according to their cytoplasmic electrondensity. Colocalisation of different hormones in the same cell is rarely observed. The close contact between endocrine and exocrine cells and the scarcity of nerve supply is indicative of a paracrine control of hormone secretion.