骨组织工程种子细胞的研究进展

随着骨组织工程研究的进展 ,选择什么细胞作为其种子细胞成为近年来研究的热点。目前 ,骨组织工程应用中种子细胞有五种来源 :骨、骨膜、骨髓、骨外组织和早期胚胎。本文介绍了五种来源种子细胞的研究状况 ,并对种子细胞各自存在的问题及应用前景进行了分析。     

Detection and delineation of an unusual 17p11.2 deletion by array-CGH and refinement of the Smith–Magenis syndrome minimum deletion to 650 kb

Smith–Magenis syndrome (SMS) is a multiple congenital anomaly/mental retardation syndrome and it is characterized by an interstitial deletion of chromosome 17p11.2. SMS patients have a distinct phenotype which is believed to be caused by haploinsufficiency of one or more genes in the associated deleted region. Five non-deletion patients with classical phenotypic features of SMS have been reported with mutations in the retinoic acid induced 1 (RAI1) gene, located within the SMS critical interval. Happloinsufficiency of the RAI1 gene is likely to be the responsible gene for the majority of the SMS features, but other deleted genes in the SMS region may modify the overall phenotype in the patients with 17p11.2 deletions. SMS is usually diagnosed in the clinical genetic setting by FISH analysis using commercially available probes. We detected a submicroscopic deletion in 17p11.2 using array-CGH with a resolution of approximately 1 Mb in a patient with the SMS phenotype, who was not deleted for the commercially available SMS microdeletion FISH probe. Delineation of the deletion was performed using a 32K tiling BAC-array, containing 32,500 BAC clones. The deletion in this patient was size mapped to 2.7 Mb and covered the RAI1 gene. This case enabled the refinement of the SMS minimum deletion to 650 kb containing eight putative genes and one predicted gene. In addition, it demonstrates the importance to investigate deletion of RAI1 in SMS patients.     

Induction of β-family chemokines mRNA in human embryonic astrocytes by inflammatory cytokines

The cellular infiltration found during CNS inflammation consists of monocytes and activated T cells, suggesting the presence of cell-specific chemotactic signals during inflammatory responses. Astrocyte chemokine expression might contribute to site-specific leukocyte infiltration within the CNS. To investigate the factors that regulate astrocyte chemokine expression, we examined the ability of human fetal astrocytes to induce -family chemokine mRNA. Astrocyte-derived monocyte chemoattractant protein-1 (MCP-1), RANTES, macrophage inflammatory protein-1 (MIP-1), and MIP-1 mRNA were easily induced by lipopolysaccharide and/or the proinflammatory cytokines (IFN and/or TNF-), respectively. Addition of both IFN and TNF- together did not lead to an additive effect but resulted in the inhibition of MCP-1 and MIP-1 mRNA expression, indicating that interaction between chemokines and cytokines may play a key role in regulating the local immune response of resident and infiltrating cells at the site of lesion. Interestingly, ultraviolet light-inactivated measles virus, but not cytomegalovirus, strongly induced expression of MCP-1, RANTES, MIP-1, and MIP-1 mRNA in human embryonic astrocytes, especially MCP-1 and MIP-1. An association occurs between the -family chemokine expression in astrocytes and inflammatory factors/virus, suggesting a possible role for -family chemokines in the pathogenesis of CNS inflammatory disease.     

Stimulation of acid formation by histamine, carbachol and pentagastrin in isolated pig parietal cells

Free cells were obtained by sequential incubations of pig gastric mucosa with pronase and collagenase. Approximately 10-15% of the cell population represented parietal cells. Accumulation of aminopyrine (AP) in the acid compartments of parietal cells was used as an index of their acid production. Histamine, carbachol and pentagastrin each independently stimulated aminopyrine accumulation. The initial rate of aminopyrine accumulation, observed after addition of 10(-4) M carbachol or 10(-6) M pentagastrin, were 32% and 10%, respectively, of that observed with 10(-4) M histamine. Steady-state aminopyrine accumulation in the presence of 10(-4) M histamine, 10(-4) M carbachol or 10(-6) M pentagastrin were 6.2 +/- 3.3, 2.6 +/- 0.6 and 3.0 +/- 1.5 pmol AP per 10(4) parietal cells, respectively (mean +/- SD, n = 5). The EC50 value for histamine was 3.4 +/- 1.4 X 10(-7) M, and for pentagastrin 5.9 +/- 4.2 X 10(-8) M (mean +/- SD, n = 5). The dose-response curve for carbachol was biphasic. A plateau was reached at 10(-5)-10(-4) M carbachol, and for this phase an apparent EC50 of 2.1 +/- 1.4 X 10(-6) M carbachol was calculated (mean +/- SD, n = 5). A further increase to 10(-3) M carbachol increased the aminopyrine accumulation. Atropine (10(-6) M) inhibited the response to concentrations up to 10(-4) M carbachol, but was without effect on the histamine- and pentagastrin-stimulation. The H2-receptor antagonist, cimetidine, right-shifted the dose--response curve for histamine. Also, the pentagastrin-stimulated aminopyrine accumulation was inhibited by cimetidine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Behavioural effects of human fetal dopamine neurons grafted in a rat model of Parkinson's disease

Summary The ventral mesencephalon, containing the developing dopaminergic neurons of the substantia nigra-ventral tegmental region, was obtained from aborted human fetuses of 9–19 weeks of gestation. The tissue was grafted into the striatum of rats previously subjected to a 6-hydroxydopamine lesion of the mesostriatal dopamine pathway. The graft recipients were immunosuppressed by daily injections of Cyclosporin A. Amphetamine-induced motor asymmetry was reduced, and finally totally reversed, only in rats receiving grafts from the 9-week old fetal donor. The fluorescence microscopic analysis revealed large numbers of surviving dopamine neurons, and extensive fiber outgrowth into the host striatum, in these rats. By contrast, rats receiving grafts from 11–19 week old donors had at most only few surviving dopamine neurons. These results indicate that human fetal mesencephalic tissue may be an efficient source of dopamine neurons for functional intracerebral grafting in patients with Parkinson's disease.A preliminary account of some of the results from this study was presented at the New York Academy of Sciences meeting on Cell and tissue transplantation into the adult brain, New York, April 4, 1986     

Drug-induced intrahepatic cholestasis: characterization of different pathomechanisms

The pathogenesis of intrahepatic cholestasis in rats was studied using isolated perfused livers as an experimental model. Three basic mechanisms were differentiated: 1. Permeabilization of the bilio-sinusoidal barrier associated with electron microscopic alterations of the tight junctional complexes was found in livers of rats treated with -naphthylisothiocyanate (ANIT, 250 mg/kg body weight). Consequences of these alterations were: reflux of bile constituents such as taurocholate and sulfobromophthalein and increased access to the biliary space of paracellular markers such as inulin and sucrose. The clear-cut mechanism of ANIT cholestasis was used to distinguish other mechanisms of intrahepatic cholestasis. 2. Inhibition of the basic process of fluid secretion was found to be the primary event in the development of cholestasis induced by estrogens. After 5 days of treating rats with ethinyl estradiol (5 mg/kg/day), bile flow was diminished in isolated livers while the permeability of the biliary tract to sucrose and inulin was not affected. Accordingly, the maximal concentration of taurocholate in bile was increased, indicating that its secretion was sustained. The same effect was observed after 1 week of treatment with the depot estrogen estradiol valerate (1 mg/kg/week). After 3 weeks of treatment, however, the taurocholate concentration in bile was lowered and the clearance of sucrose was increased. Bile flow remained at the same cholestatic level for 20 weeks. These results suggest that estrogens have the potency to increase tight junctional permeability only in a second step in the development of cholestasis, following the inhibition of bile flow. 3. An additional mode of secretory inhibition was induced by lowering the concentration of Ca²⁺ in the perfusate of isolated liver. Using ANIT-pretreated livers, i. e., livers with very low capacity to secrete foreign dyes, a high rate of efflux of sulfobromophthalein into the perfusate of preloaded livers suggests stimulation of the efflux of cholephilic solutes across the sinusoidal membrane of liver cells.The results demonstrate that the term intrahepatic cholestasis comprises a number of different sites of interference with the complex process of bile secretion.Dedicated to Professor Dr. med. Herbert Remmer on the occasion of his 65th birthday     

Interactions between hexobarbital and thiopental in male rats evaluated with an anaesthesia threshold

The anaesthetic interaction between hexobarbital and thiopental in different combinations were investigated in male rats by using the isobolografic method. Data on dose, serum or brain concentrations at an EEG-criterion induced with a threshold method were utilized. The criterion was defined by a burst suppression in the EEG of 1 sec. or more (the "silent second"). With rats more than 115 days of age a synergistic interaction (potentiation) was obtained when a low dose of hexobarbital and a high dose of thiopental were used. The relationship between serum and brain concentrations of hexobarbital and thiopental in the different tested combinations gave no evidence for a pharmacokinetic interaction. Thus the synergistic interaction was located in the brain and probably related to the mechanisms of action. The same tests performed on rats at an age of approximately 90 days gave not only a potentiation when a low dose of hexobarbital and a high dose of thiopental were used, but also a potentiation when a high dose of hexobarbital and a low dose of thiopental were used. These results indicate an age-related change in sensitivity in the CNS between 90 and 115 days of age. Further investigations of this age-related change showed that this change from a potentiation to an additive interaction occurred between the age of 85 and 96 days.     

双歧杆菌QJ 405和乳酸杆菌QJ 405的生物学特征及鉴定

目的：观察从健康核潜艇艇员正常粪便中分离出的双歧杆菌QJ405和乳酸杆菌QJ405的生物学特征,判定其是否符合益生菌要求。方法：分析细菌的形态学和生理生化特征。采用数值分类法（API20A）的化学分类法（气相色谱分析）进行种属鉴定。抗生素敏感试验采用ATB法。结果：两株菌分别鉴定为长双杆菌和唾液乳酸杆菌唾液亚种,两菌代谢发酵碳水化合物均可产生大量乙酸、乳酸,对多种抗生素表现敏感。结论：双歧杆菌QJ405和乳酸杆菌QJ405的来源和部分生物活性符合益生菌的要求。