摘要:

Cells of the ciliateTetrahymena thermophilaproduce compounds that act as autocrine (paracrine) survival and/or growth factors. 8‐Bromo cyclic GMP, sodium nitroprusside, hemin, protoporphyrin IX, human recombinant and bovine insulin were tested for their ability to substitute for the cell‐produced factors and stimulate cell survival and proliferation. The cells were inoculated into conical flasks in a nutritionally complete, chemically defined medium at known cell densities from 5 to 5000cells/ml. In unsupplemented medium cells at 5 to 500cells/ml (‘low initial cell density cultures’) died within 8h, whereas cells at 1000 and 5000cells/ml (‘high initial cell density cultures’) proliferated with lag phases lasting for up to 4h. In the presence of insulin compounds, hemin, protoporphyrin IX, or 8‐bromo cyclic GMP, cells also proliferated at all low initial cell densities. Sodium nitroprusside was effective over two separate concentration ranges: at the nanomolar levels as well at low pico‐ to femtomolar levels. At initial population densities of up to 50cells/ml the cells at both concentrations of sodium nitroprusside survived about 4‐fold longer than the controls. At 500 initial cells/ml, cells at thehigh concentrations of sodium nitroprusside survived about 4‐fold longer than those of the control cultures; they proliferated in the low concentrations of sodium nitroprusside. Concentrations of hemin, too low to have any effects on their own, had synergistic effects with sodium nitroprusside. NG‐methyl‐L‐arginine inhibited proliferation at high initial cell densities. This inhibitory action was reduced by high concentrations of L‐arginine, protoporphyrin IX, sodium nitroprusside, or 8‐bromo cGMP, but not by insulin. Methylene blue inhibited cell proliferation at high initial cell densities. This inhibition was circumvented by addition of 8‐bromo cGMP. The findings that insulin‐related material may be released fromTetrahymenaand that insulin and sodium nitroprusside increase intracellular cGMP in these cells are discussed in relation to the presented results. Together these observations suggest that cGMP is responsible for supporting cell survival inTetrahymenaand switching the cells into their proliferative mode, and that cell‐produced signal molecules and insulin stimulate an NO‐dependent

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0087

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Xenopusembryos contain a considerable amount of a polysialo‐ganglioside not yet fully characterized; in this paper, we will refer to it as ganglioside X1. Preliminary experiments indicate asialo‐GM1 as the core structure of the ganglioside X1 and palmitic and oleic acid as the fatty acids of the ceramide moiety. Further analyses by comparative 2D‐TLC with adult fish and chick embryo brains indicate the pentasialilated ganglioside GP1c as the possible structure of X1. In the adultXenopus, X1 characterizes the ganglioside pattern of the central nervous system while is absent in all the other tested tissues. At least two other more polar (presumably richer in sialic acid) bands are often visible under X1, both in embryos and in brain and spinal cord tissues of adultXenopus. The persistence of polysialo‐gangliosides in the brain and spinal cord of adult amphibians could serve to guarantee a proper functioning of the central nervous system at low body temp

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0088

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Mouse trisomy 16 (Ts16) appears to provide an animal model of Down's syndrome in that a portion of mouse chromosome 16 is syntenic with part of human chromosome 21. Trisomy 21 in human beings leads to the mental retardation of Down's syndrome and in middle age, to some presenile anatomic and clinical features of Alzheimer's disease. Neural tissue from aging Ts16 mice is unavailable, however, as Ts16 mouse embryos die latein utero. We studied these embryos looking at the ultrastructure of neurons from the hippocampus and dorsal root ganglion in normal control mice embryos (diploid) and in Ts16 late embryonic litter mates after day 15 of gestation. The organelles in the Ts16 neurons looked similar to those in control neurons, fixed and processed under similar conditions. No obvious neuropathological structures were observed. These results, when compared to reports on electrophysiological abnormalities of cultured fetal Ts16 neurons and on abnormalities in neurotransmitter markers in the Ts16 fetal brain, lead us to suggest that the mental retardation of Down's syndrome is likely to result from functional and chemical defects not directly related to abnormal neuronal ultrastructure. When related to fine structural studies of transplanted embryonic Ts16 hippocampus which have been maintained for long periods of time, these results indicate that the trisomic mouse brain would not be useful as a structural model for Down's syndrome and hence presenile Alzheimer's disease, as it is not associated with any detectable morphological abnormality.

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0089

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Embryonic chick notochords were studied during their metabolically active and involuting periods for the expression of collagen type I and II. The staining was carried out on notochordsin vivoat stage 20 and stage 35 and on mesenchyme‐contaminated and mesenchyme‐free notochords at stage 20, which were culturedin vitrofor 6 days. The results show that type II collagen is demonstrable in the notochords, at all the examined stages, bothin vivoandin vitro. However, the expression of type I collagen was stage‐dependentin vivoandin vitro. At stage 20, the perinotochordal sheath is positively immunostained for collagen type I, but the notochord itself is negative. At stage 35, the perinotochordal sheath as well as the notochord are positively immunostained for collagen type I. The mesenchyme‐contaminated and the mesenchyme‐free notochords and their sheaths are also positively immunostained for the type I collagen after6 daysin vitro. The current results, at late developmental stages, indicate that the involuting notochords express collagen type I, which seems not to be altered by changing the micro‐environ

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0090

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

It was recently demonstrated that the pineal neurohormone melatonin is a hydroxyl radical scavenger and antioxidant, and that it plays an important role in the immune system. In studies reported herein, we have investigated the relationship of the melatonin level and the NF‐κB DNA binding activity in the spleen of Sprague—Dawley rats. Thesein vivoresults indicate that NF‐κB DNA binding activity in the spleen is lower at night, when endogenous melatonin levels are elevated, than during the day, when endogenous melatonin levels are lower. Furthermore, exogenously administered melatonin (10mg/kg) was shown to cause a significant decrease in NF‐κB DNA binding activity in the spleen at 60min after intraperitoneal injection (as compared with vehicle‐treated rats). These new findings suggest that the normal night time rise which can be expected for melatonin may be associated with increased NF‐κB DNA binding activity in the spleen. The melatonin, therefore, could potentially act to modulate spleen function and/or the immune system by regulating the NF‐κB DNA binding acti

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0091

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0092

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY