Early and late effects in the bone marrow of mice following 2 Gy (6 MeV) neutron irradiation

Summary Following 5 Gy gamma irradiation, residual damage in bone marrow persisted up to one year and was ascribed to genetic defects in hemopoietic stem cells (von Wangenheim et al. 1986). To see whether high LET radiation is more efficient in inducing late effects, mice were whole-body irradiated with a single dose of 2 Gy neutrons ( = 6 MeV) and femoral cellularity, CFU-S number, proliferation ability of bone marrow cells (PF) and the compartment ratio (CR), i.e. the splenic 125-iodo-deoxyuridine incorporation per transfused CFU-S were measured up to one year after the radiation insult. Within 12 weeks, femoral cellularity, PF and CR recovered to control or near-control level, whereas CFU-S numbers remained significantly below control. No further recovery was observed. On the contrary, PF and CR deteriorated again after 12 and 26 weeks, respectively. CFU-S per femur tended to decrease as well. Thus it is demonstrated that a single dose of 2 Gy 6 MeV neutrons causes significant injury in function (PF) and structure (CFU-S numbers, CR) of bone marrow which persisted up to one year. While this residual injury can be attributed to genetic defects in hemopoietic stem cells, its increasing expression is probably due to late evolving damage in microenvironmental cells. The RBE of 6 MeV neutrons for the introduction of late effects in the bone marrow is in the range of 3.     

Tachykinins protect against ethanol-induced gastric lesions in rats

Subcutaneous pretreatment of rats with neurokinin (NK) A or the fragment NKA(4-10) reduced the degree of gastric lesions induced by oral administration of 96% ethanol. The protective effect of NKA(4-10) was dose-dependent. Arg-NKB, the water soluble derivative of NKB, was less effective than NKA or NKA(4-10) while [Me-Phe7]NKB, substance P (SP) and SP-methyl-ester were inactive. The NKA(4-10) antilesion effect was reversed by pretreatment with N-ethyl-maleimide, suggesting a possible involvement of sulphydryls in its action. Among the nonmammalian tachykinins, kassinin significantly reduced ethanol-induced lesions while eledoisin and physalaemin at equivalent molar doses were inactive. These results provide, for the first time, evidence that tachykinins and their derivatives exert gastroprotective activity toward ethanol-induced haemorrhagic lesions. Assuming a receptor-mediated mechanism, NK-2 sites could be involved.     

High degree of homology between primary structure of human lysosomal acid phosphatase and human prostatic acid phosphatase

Alignment of the amino-acid sequences of the human lysosomal acid phosphatase (LAP) and human prostatic acid phosphatase (PAP) yielded an extensive homology between the two mature polypeptide chains. In the overlapping part, which extends over the entire PAP sequence and the N-terminal 90% of the LAP sequence, the identity is 49.1%. The LAP has an additional C-terminal sequence, which is encoded by the last exon of the LAP gene. This sequence contains the transmembrane domain of LAP, which is lacking in the secretory PAP. All six cysteine residues as well as 20 out of 27 (LAP) and 26 (PAP) proline residues present in the overlapping part of the proteins are conserved, suggesting that they are involved in stabilization of the tertiary structure of both proteins. Only two out of 8 N-glycosylation sites in LAP and 3 in PAP are conserved, suggesting that the dense N-glycosylation of LAP is related to its function in lysosomes.     

An immunohistochemical study on the postnatal development of rat nasal-associated lymphoid tissue (NALT)

Summary This study concerns the development of nasal-associated lymphoid tissue in the rat, using immuno- and enzyme-histochemical staining techniques on cryostat sections. Nasal-associated lymphoid tissue is present at birth as a small accumulation of mainly T lymphocytes and non-lymphoid cells; B cells are rare. Distinct areas of T and B cells appear at 10 days after birth; by that time high endothelial venules are also observed. Intra-epithelial lymphocytes are present, most of them being T-helper cells. ED1+ macrophages are seen throughout the tissue. The proportion of ED1+cells does not change during ontogeny. ED2+cells (tissue macrophages) are present predominantly at the border between the lymphoid tissue and the surrounding connective tissue, in all age-groups. ED3+mononuclear cells are scattered throughout the nasal-associated lymphoid tissue of young animals. Later on, the ED3+ cells migrate into the border-area between lymphoid and connective tissue. Ia+ non-lymphoid cells in the nasal lymphoid tissue increase in number during ontogeny. Only a few of them show acid phosphatase activity, indicating that the proportion of classical scavenger macrophages is low. Some of them may be antigen presenting (dendritic) cells. Ia+ dendritic cells also occur between the epithelial cells. Moreover, some epithelial cells express the Ia marker.     

The heat generated by yeast cultures with a mixed metabolism in the transition between respiration and fermentation

The heat generated by both batch and continuous cultures of the yeast K. fragilis was studied using a modified Bench Scale Calorimeter. Batch cultures were used to measure the heat dissipation rates and the heat yields during fully aerobic and completely anaerobic growth, whereas continuous cultures enabled, in addition, a quantitative study of heat dissipation rates during growth on mixed metabolism. In this case, the extent of fermentation versus respiration could be specified and controlled by varying the degree of oxygen limitation. The heat dissipated per unit biomass formed was highest for fully respirative catabolism and fell continuously to a much lower value typical of anaerobic cultures as the catabolism was shifted increasingly to the fermentative mode. The heat generated per mole of oxygen taken up stayed quite close to the fully aerobic value of 506 kJ mol(-1) even when a sizable fraction of the substrate available to catabolism was fermented. If the fraction of respiration in the metabolism is lowered beyond a certain threshold, the ratio of the heat generation to oxygen consumption starts to increase dramatically and finally tends to infinity for fully anaerobic growth. All experimental results were quantitatively analyzed and explained on the basis of a simple model which formally describes the cultures in terms of two parallel "chemical" reactions. In simple cases such as the one presented here, the model enables calculation of the whole stoichiometry of the culture from a single measured heat yield.     

Purification and partial characterization of 1-aminocyclopropane-1-carboxylate synthase from tomato pericarp

1-Aminocyclopropane-1-carboxylate synthase was purified 5000-fold from LiCl-induced tomato fruit slices by conventional and high-performance liquid chromatography. The final preparation was estimated to be between 25% and 50% pure. Two-dimensional gel electrophoresis indicates that 1-aminocyclopropane-1-carboxylate synthase activity is associated with a 45-kDa polypeptide, with a pI of 5.8 +/- 0.2. The enzyme is inactivated both by its substrate, S-adenosyl-L-methionine (AdoMet) and by one of its products, 1-aminocyclopropane-1-carboxylate. Due to the extremely low abundance of the protein it was necessary to scale up the extraction in order to obtain reasonable amounts for sequence analysis. Therefore, 200 kg tomatoes were extracted on semi-industrial scale and 1-aminocyclopropane-1-carboxylate synthase purified. This yielded approximately 150 micrograms enzyme.     

Cell attachment properties of collagen type VI and arg-gly-asp dependent binding to its α2(VI) and α3(VI) chains

Twelve of sixteen different cell types including fibroblasts and tumor cells were able to attach and spread on substrates of pepsin-solubilized or intact collagen VI, and on its triple helical domain. Attachment and spreading were independent of soluble mediator proteins (fibronectin, laminin) and collagen VI was distinct from collagens I, IV and V in the cells with which it interacted. Many of the same cells bound and spread on substrates prepared from unfolded α2(VI) and α3(VI) chains but not on the α1(VI) chain. The interactions with the chains were inhibited by low concentrations (10–100 μM) of synthetic RGDS and RGDT but not RGES peptides while the binding of cells to pepsin-solubilized collagen VI was more than 20-fold less sensitive to these peptides. The data incidate that cells have the ability to bind to collagen VI in a specific manner suggesting a similar function for collagen VI in situ.     

Purification and crystallization of ferric enterobactin receptor protein, FepA, from the outer membranes of Escherichia coli UT5600/pBB2

The ferric enterobactin receptor protein, FepA, was isolated and purified from the outer membranes of a genetically transformed strain of Escherichia coli (UT5600/pBB2) using anion-exchange chromatography, chromatofocusing and gel filtration. The purified protein was found to crystallize from 25 mM sodium phosphate buffer in the presence of 0.8% beta-D-octylglucoside under a range of conditions. The protein formed mostly small rods and needle-shaped crystals in the hanging drop method.     

CD3/T-cell receptor coupling to a pertussis and cholera toxin-insensitive G-protein

We have analyzed the effect of CD3/T-cell receptor stimulation on GTP hydrolysis and GTP binding. We show that stimulation of Jurkat, T-cell, membranes with OKT3 results in a 50% increase in GTP hydrolysis which is specifically inhibited by GDP. Pretreatment of the membranes with neither pertussis toxin nor cholera toxin inhibited the GTP hydrolysis. We also show that stimulation with OKT3 increases the binding of GTPγS to Jurkat membranes. These data strongly implicate the involvement of a G-protein in CD3/T-cell receptor signalling.