器官培养在研究人食管上皮癌变中的应用

将组织块置于明胶海绵上,摇摆器官培养,4～6周后成人食管粘膜仍保持良好的结构形态,具有活跃生长的上皮细胞和良好的腺体结构;将组织块贴壁,静置外植块—细胞培养,成人食管粘膜和胎儿食管组织块可存活2～3个月,提供大量生长旺盛的上皮细胞。成人食管癌旁粘膜培养利于观察细胞癌前改变,可能较易于诱发癌变;胎儿食管具有正常背景,利于研究细胞癌变的全过程.二者配合可组成研究人食管上皮癌变的完整体外实验系统。     

The distribution of (-)-propranolol in the isolated rabbit iris

It has been postulated that propranolol lowers the intraocular pressure by adrenergic neurone block. However, in the isolated iris of albino rabbits, there was only a small degree of cocaine-sensitive (i.e., neuronal) accumulation of ³H-(-)-propranolol, and none at all after pretreatment of the animals with reserpine. Moreover, after preloading of the iris with ³H-(-)-propranolol, veratridine failed to release any labelled material. Hence, any adrenergic neurone blocking action of propranolol is highly unlikely.Albino and pigmented irides were first exposed to ³H-(-)-propranolol and then washed out. The results and their compartmental analysis indicated an extensive binding of ³H-(-)-propranolol in or at pigment cells; the binding is characterized by a low dissociation constant. It is very likely that the initial binding and the subsequent slow dissociation from pigment cells explains the long duration of action of beta-adrenoceptor antagonists in human therapy.     

Effects of sodium and GTP on the binding kinetics of [3H]diprenorphine in NG 108-15 cell membranes

Summary Equilibrium binding isotherms of [³H]diprenorphine in membranes from NG 108-15 cells are consistent with a homogenous population of binding sites. Upon addition of Na⁺, Mg²⁺ and GTP, only a 2-fold reduction in affinity with a minor decrease in the number of sites is observed. Dissociation curves of [³H]diprenorphine, however, are clearly biphasic: in the absence of Na⁺, Mg²⁺ and GTP, 80% of the bound ligand dissociates slowly with at _1/2 of 100 min, and only 20% rapidly (t _1/2 4.5 min). In the presence of Mg²⁺, nearly all the binding is found in the slowly dissociating form. Upon the addition of either Na⁺ or GTP, 20–30% of the binding dissociates more rapidly. The rate constant of the rapidly dissociating form generated by Na⁺, however, is 2.5 times greater than that induced by the presence of GTP. Thus, the addition of both, Na⁺ and GTP, converts about 80% of the receptor into a very fast dissociating form (t _1/2 1.7 min).Exposure of intact cells to pertussis toxin (10 ng/ml) or treatment of membranes with N-ethyl maleimide (500 M), strongly reduces the proportion of the slowly dissociating component. Following these treatments, the effect of GTP is reduced or abolished, but that of Na⁺ remains unaffected.We conclude from these data that the effects of Na⁺ and GTP are not only distinct in site but also in mechanism of action and that there are three forms of opioid receptors that can be differentiated by their kinetic properties. The slowly dissociating receptor form requires a functional N unit.     

Quantitation of differential sensitivity of normal marrow myeloid progenitor cells to anthracene derivatives

The effect of 3 anthracene derivatives, mitoxantrone, ametantrone, bisantrene, on 4 normal human bone marrows, was studied using the myeloid stem cell assay developed by Pike and Robinson, in order to define to what extent this test could be used to predict the relative clinical hematologic toxicity of new anticancer agents. For the 3 drugs, an exponential relationship between colony survival and drug concentration was found, but was much steeper for mitoxantrone (slope = -195.2 ± 8.8/g/ml) than for ametantrone (slope = 5.1 ± 1.0/g/ml, p0.001) and bisantrene (slope = 7.1 ± 0.3/g/ml, p0.001). The difference of slope between ametantrone and bisantrene was of borderline significance (p0.05). The ratios of concentrations inducing a 50% growth inhibition for mitoxantrone versus bisantrene and for ametantrone versus bisantrene were close to the corresponding ratios of concentrations inducing a 90% growth inhibition. The relative in vitro toxicities reproduce very well the relative myelosuppression observed in clinical trials with mitoxantrone versus bisantrene but the results were less satisfactory for the comparison of these 2 agents with ametantrone. In addition, our data suggest that, for these 3 compounds, intrinsic myeloid progenitor sensitivity is a major determinant of leukopenia.     

Short-termin vivo stability of endothelial-lined polyester elastomer and polytetrafluoroethylene grafts

A fibronectin substrate will significantly enhance the strength of endothelial cell attachment on grafts constructed of polyester elastomer (PE) and polytetrafluoroethylene (e-PTFE). This experiment was undertaken to determine the short-termin vivo stability of endothellum on these fibronectin coated surfaces. Eight mongrel dogs underwent bilateral carotid artery replacement with both graft materlals. All grafts were inoculated with 2,000 cells/mm² using cultured autogenous venous endothelium labelled with Indium-111-oxine. The Indium-111 label in the grafts was measured immediately prior to implantation, after 1 hour ofin vivo perfusion, and at explantation after 24 hours. The percentage of inoculated cells attached to the grafts before perfusion was simillar for both materials, 93.3±3.0% versus 92.2±7.2%, for PE and e-PTFE respectively. All grafts were patent at one hour after implantation. PE grafts were found to have 93.8±3.9 % of the attached cells present at one hour while e-PTFE grafts had only 54.5 ± 10.8 % remaining, p<.001. After 24 hours, 5/8 (62.5%) e-PTFE grafts and 2/8 (25.0 %) PE grafts remained patent, p=.13. Of the patent grafts however, endothelial cell retention was still superior on the PE grafts with 78.0±0.6% of the attached cells remaining compared to only 24.5±6.1% on e-PTFE, p<.001. Occluded PE grafts had fewer cells remaining at 24 hours than patent ones, 78.0±0.6% versus 31.1±32.8%, respectively, p=.13. Histologically, patent PE grafts demonstrated nearly confluent endothelial monolayers while e-PTFE had patches of endothelial cells surrounded by, a platelet-fibrin carpet. We conclude that short-term patency appears to be determined by the extent of endothelial retention on PE but not e-PTFE.     

Guanine nucleotide and cation regulation of radioligand binding to R i adenosine receptors of rat fat cells

Summary The modulation of radioligand binding at R _i adenosine receptors of rat fat cells by guanine nucleotides and cations was investigated. Guanine nucleotides (in the order of potency: GTP=GDP>Gpp(NH)p>5-GMP) decreased the binding of the R _i receptor agonist (–)N⁶-phenylisopropyl[³H]adenosine ([³H]PIA), but did not affect binding of the antagonist 1,3-diethyl-8[³H]phenylxanthine ([³H]DPX). Saturation of [³H]PIA binding revealed that GTP (100 mol/l) converts the high affinity form of the R _i receptor into a low affinity form. This effect was confirmed in kinetic experiments. GTP decreased the potency of agonists in competing for [³H]DPX binding, as shown by a 50-fold shift of the K _i-value for (–)PIA, whereas antagonist-induced inhibition of binding remained unchanged. The divalent cations Mg²⁺ and Ca²⁺ produced a slight increase in [³H]PIA binding but did not affect [³H]DPX binding. Mn²⁺ markedly decreased both agonist and antagonist binding at R _i adenosine receptors. Divalent cations reversed the guanine nucleotide-induced decrease of affinity of the R _i receptor. Na⁺ did not significantly affect agonist or antagonist binding but abolished the stimulatory effect of Mg²⁺ on agonist binding in the presence of GTP. Our data indicate that guanine nucleotides convert the R _i adenosine receptor of rat fat cells from a high to a low agonist affinity state and that the modulation of radioligand binding by mono-and divalent cations differs from that of R _i receptors of other tissues.     

Effects of several 5′-carboxamide derivatives of adenosine on adenosine receptors of human platelets and rat fat cells

Summary The effects of several 5-carboxamide derivatives of adenosine on stimulatory (R _a) adenosine receptors of human platelets and inhibitory (R _i) adenosine receptors of rat fat cells have been compared. 5-N-Cyclopropylcarboxamidoadenosine (CPCA) and 5-N-ethylcarboxamidoadenosine (NECA) most potently inhibited ADP-induced aggregation of human platelets as shown by IC₅₀-values of 0.24 and 0.34 mol/l. 5-N-Methylcarboxamidoadenosine (MECA; IC₅₀ 0.81 mol/l) and 5-N-carboxamidoadenosine (NCA; IC₅₀ 2.1 mol/l) were less potent, whereas adenosine, 2-chloroadenosine and (-)N⁶-phenylisopropyladenosine [(-)PIA] exhibit IC₅₀-values of about 1.5 mol/l. Nearly the same rank order of potency was obtained for stimulation of adenylate cyclase activity of platelet membranes and for inhibition of [³H]NECA binding to human platelets. In order to examine the effects of the carboxamide analogues on R _i adenosine receptors of rat fat cells inhibition of lipolysis and adenylate cyclase were studied. (-)PIA was the most potent inhibitor of lipolysis as shown by an IC₅₀ of 0.5 nmol/l, followed by CPCA (IC₅₀ 1.1 nmol/l) and NECA (IC₅₀ 1.3 nmol/l), whereas MECA (IC₅₀ 17.9 nmol/l) and NCA (IC₅₀ 20.1 nmol/l) were much less potent than NECA in inhibiting lipolysis. Similar results were obtained for inhibition of adenylate cyclase activity of fat cell membranes and for competition with [³H]PIA binding to fat cell membranes. The relative potencies of the adenosine analogues at both receptor subclasses were calculated from the ratio of the IC₅₀-values for inhibition of platelet aggregation and of lipolysis. (-)PIA showed the highest selectivity for R _i receptors as indicated by a 2,900-fold lower IC₅₀ for the antilipolytic than for the antiaggregatory effect. The R _a/R _i activity ratio for NECA was about 260, for CPCA 220, for NCA 105 and for MECA 45. These results indicate that all 5-carboxamide adenosine derivatives are more potent agonists at R _i receptors than at R _a receptors. Since MECA has a higher selectivity for R _a receptors than NECA, it may be useful for the characterization of stimulatory adenosine receptors in different tissues.     

Macromolecular DNA-damage in murine and human leukemic and lymphoid cells after in vitro exposure to ASTA Z 7557 (INN mafosfamide)

Summary Cyclophosphamide (CPA) is widely used against leukemic and lymphoproliferative diseases, but in vitro studies on response to this agent so far have been limited to instable derivatives with poor galenic properties. ASTA Z 7557 is a newly synthesized activated cyclophosphamide that circumvents the need for hepatic activation and has good stability. The critical cytotoxic lesions after exposure to bifunctional alkylating agents presumably are DNA interstrand crosslinks (ISC). We have, therefore, examined the formation and apparent removal of ISC after in vitro treatment with ASTA Z 7557 by use of the highly sensitive alkaline elution technique. Survival of murine L1210 cells was determined after 1 hour in vitro exposure with a D 37 value of 5.7 g/ml (from the initial shoulder part of the survival curve) and a Do value of 1.5 g/ml (from the exponential part of the curve). Previous labelling of L1210 cells by ¹²⁵IUdR simplified the alkaline elution procedure but there was some cytotoxicity of the radiochemical itself with a reduction of cloning efficiency from 77% to 61 %. The maximum of ISC was observed at 6 h after initiation of treatment with much of the damage apparently removed at 24 h. The simultaneous presence of DNA single strand breaks (SSB), however, confounds the analysis of DNA damage at 24 h and early cytolysis and unaided death of human lymphocytes often preclude the analysis of macromolecular damage at this time. Human peripheral blood cells isolated from patients with leukemic or lymphoproliferative diseases showed a remarkable heterogeneity with regard to the formation of ISC at 3 h. Thus, analysis of macromolecular damage may become an additional prognostic factor for response to CPA beyond the morphologic classification of these diseases.     

Immunohistochemistry of folliculo-stellate cells in normal human adenohypophyses and in pituitary adenomas

Summary Presence and distribution of S-100 protein (S-100), neuron-specific enolase (NSE), cytokeratin polypeptides, glial fibrillary acidic protein (GFAP), vimentin, actin, lysozyme and pituitary hormones (prolactin, hGH, ACTH, -FSH, -LH, -TSH, alpha subunit) in folliculo-stellate cells (FSC) were studied in seven normal human pituitary glands and 28 pituitary adenomas using peroxidase-antiperoxidase and the avidin-biotin immunohistochemical techniques. Approximately 5% of the cells of the adenohypophysis were agranular, non-hormon-producing FSC most of which showed a conspicuous and strong reaction with S-100 antibodies but some were, in addition, GFAP- and vimentin-positive. In contrast to endocrine cells (EC), FSC were not decorated by antibodies to NSE or cytokeratins. In addition to supportive functions, these cells, due to their close special relationship to EC, seem to have transport and other metabolic functions yet to be elucidated. By their S-100 reactivity and their distribution FSC are comparable to glial cells of the central and schwann and satellite cells of the peripheral nervous system (PNS) as well as to supportive cells in neuroendocrine organs and related tumors (e.g., pheochromocytomas, paragangliomas, carcinoids). With one exception, S-100 reactive FSC were not found in pituitary adenomas. The immunohistochemical demonstration of S-100 protein in pituitary tissue is, therefore, a reliable aid in the discrimination between adenomas and normal pituitary tissue, particularly in small and poorly preserved specimens. In one adenoma FSC were found in addition to ACTH-producing tumor cells. This seems to be an extremely rare event suggesting a combination tumor.Supported in part by Fonds zur Förderung der wissenschaftlichen Forschung (no. 4708) to H. Denk