Arginine transport in Streptococcus lactis is catalyzed by a cationic exchanger.

Streptococcus lactis metabolizes arginine via the arginine deiminase pathway to ornithine, CO2, NH3, and ATP. The translocation of arginine and ornithine has been studied using membrane vesicles of galactose/arginine-grown cells of S. lactis fused with cytochrome c oxidase proteoliposomes by the freeze/thaw--sonication procedure earlier described. In the presence of reduced cytochrome c the fused membranes rapidly accumulate ornithine. Addition of arginine releases accumulated ornithine. Rapid uncoupler-insensitive exchange between external arginine and internal ornithine is seen at rates that are at least 60-fold higher than the rate of protonmotive force-driven arginine translocation. This arginine:ornithine exchange activity was reconstituted in proteoliposomes after solubilization of S. lactis membranes with octyl beta-D-glucopyranoside. These proteoliposomes catalyze a one-to-one exchange between arginine and ornithine. The arginine:ornithine exchange system is the first exchange system for cationic metabolites found in bacteria. Translocation of arginine via this system does not require metabolic energy obtained by arginine metabolism.     

Influence of polyunsaturated fatty acid supplementation and membrane fluidity on ozone and nitrogen dioxide sensitivity of rat alveolar macrophages

The phospholipid polyunsaturated fatty acid (PUFA) content and the membrane fluidity of rat alveolar macrophages were modified dose-dependently and in different ways. This was done to study the importance of both membrane characteristics for the cellular sensitivity toward ozone and nitrogen dioxide. Cells preincubated with arachidonic acid (20:4) complexed to bovine serum albumin (BSA) demonstrated an increased in vitro sensitivity versus ozone and nitrogen dioxide. The phenomenon was only observed at the highest 20:4 concentrations tested, whereas the membrane fluidity of the 20:4-treated cells already showed a maximum increase at lower preincubation concentrations. Hence it could be concluded that the increased ozone and nitrogen dioxide sensitivity of PUFA-enriched cells is not caused by their increased membrane fluidity, resulting in an increased accessibility of sensitive cellular fatty acid moieties or amino acid residues. This conclusion receives further support from other observations. These results strongly support the involvement of lipid oxidation in the mechanism(s) of toxic action of both ozone and nitrogen dioxide in an intact cell system.     

Mechanisms of ozone toxicity in cultured cells. I. Reduced clonogenic ability of polyunsaturated fatty acid-supplemented fibroblasts. Effect of vitamin E

The direct action of ozone on viability and survival of normal and modified mouse lung fibroblasts has been studied. By cell manipulation of fibroblasts in culture, the content of polyunsaturated fatty acids (PUFA) in the phospholipids was increased from about 6% to about 40%. The cellular content of alpha-tocopherol (alpha-T) (vitamin E) could be drastically enhanced. Vitamin E supplementation to the cell did not influence the PUFA manipulation. Normal, PUFA, and PUFA(alpha-T) fibroblasts were exposed to ozone by bubbling 10 ppm through the cell suspensions for different periods of time (0-6 h). No significant effects of the ozone exposure could be established when normal fibroblasts were used. The PUFA fibroblasts, however, were very vulnerable to ozone toxicity, both in terms of dye uptake (Trypan blue) and cell death (clonogenic ability). When alpha-tocopherol was present in the cell (200 ng/10(6) cells), a clear protection against ozone toxicity was found. It is concluded that ozone toxicity might be higher under conditions of a relative high amount of polyunsaturated fatty acids in the membrane phospholipids of the cell and a low cellular antioxidant capacity. Cellular membranes are probably an important target for ozone-induced cell death.     

Long-term results of the Swanson prosthesis for the treatment of lunate osteomalacia

From 1972 to 1982 a silicone implant arthroplasty was performed in 18 patients with Kienb?ck's disease grade III. In May 1988 all patients had a clinical and radiological re-examination. In the course of time reoperations were performed in 4 patients because of (sub)luxation of the prosthesis. Because of this operation most of the patients had less pain and retained an acceptable function of the wrist. Influence on working circumstances had been considerable in 8 patients. One patient received a disability pension because of this disease. Radiological examination often revealed increased degenerative changes in carpo-radial and intercarpal joints as well as proximal migration of the capitate. There was no clear relationship between residual complaints and function at the follow-up examination and the radiological findings.     

Measurement of antitryptic activity of serum with a centrifugal analyzer.

The Selected Method [Clin. Chem. 20, 396 (1974)] for the enzymatic assay of alpha1-antitrypsin in serum has been adapted for use with the E.N.I.-GEMSAEC. With alpha-N-benzoyl-D,L-arginine-p-nitroanilide as substrate, the difference between the tryptic activity measured with and without addition of serum in the same run has been used to calculate the trypsin-inhibitory capacity. The rate of increase in absorbance at 400 nm of the p-nitroanilide formed, has been evaluated during a reaction time of 140 s. Results correlated well (r = 0.986) for 54 human sera analyzed as described here and by the Selected Method. The adaptation on GEMSAEC can be used in detecting alpha1-antitrypsin deficiency in the newborn.     

In vitro cytotoxicity of sesquiterpene lactones from Eupatorium cannabinum L. and semi-synthetic derivatives from eupatoriopicrin

In this study 13 semi-synthetic derivatives were prepared from the sesquiterpene lactone eupatoriopicrin, with the aim of obtaining compounds that are more active than eupatoriopicrin, and to give more insight into structure–activity relationships. The compounds were screened for cytotoxicity in vitro against the tumour cell lines EAT, P388, FIO 26, L5178Y(s) (murine) and HeLa (human). Cytotoxicity was compared with the germacranolides eupatoriopicrin, 5′-dehydroxy eupatoriopicrin (‘compound 1’), hiyodorilactone E, eupatolide and eucannabinolide from Eupatorium cannabinum L. and with the eudesmanolides alantolactone and isoalantolactone from Inula helenium L. Acetalization of both hydroxyl groups in the ester side chain of eupatoriopicrin with acetone enhanced cytotoxicity 2–7-fold. Introduction of bulky groups, such as alkyl groups with a longer carbon chain and (halogenated) acetophenone derivatives, via acetalization, reversed the enhancement. Oxidation at the germacrane ring structure of eupatoriopicrin acetonide, yielding an alcohol or an epoxy derivative, affected cytotoxicity adversely.     

Secondary radiation damage as the main cause for unexpected volume effects: a histopathologic study of the parotid gland

PURPOSE: To elucidate with a histopathological study the mechanism of region-dependent volume effects in the partly irradiated parotid gland of the rat. METHODS AND MATERIALS: Wistar rats were locally X-irradiated with collimators with conformal radiation portals for 100% volume and 50% cranial/caudal partial volumes. Single doses up to 40 Gy were applied. Parotid saliva samples were collected, and the three lobes of the parotid gland were examined individually on the macro- and micromorphologic level up to 1 year after irradiation. RESULTS: Dose-dependent loss of gland weight was observed 1 year after total or partial X-irradiation. Weight loss of the glands correlated very well with loss of secretory function. Irradiating the cranial 50% volume (implicating a shielded lateral lobe) resulted in substantially more damage in terms of weight loss and loss of secretory function than 50% caudal irradiation (shielding the ventral and dorsal lobe). Histologic examinations of the glands 1 year after irradiation revealed that the shielded lateral lobe was severely affected, in contrast to the shielded ventral and dorsal lobes. Time studies showed that irradiation of the cranial 50% volume caused late development of secondary damage in the shielded lateral lobe, becoming manifest between 240 and 360 days after irradiation. The possible clinical significance of this finding is discussed. CONCLUSION: It is concluded that the observed region-dependent volume effect for late function loss in the rat parotid gland after partial irradiation is mainly caused by secondary events in the shielded lateral lobe. The most probable first step (primary radiation event) in the development of this secondary damage is radiation exposure to the hilus region (located between the ventral and dorsal lobe). By injuring major excretory ducts and supply routes for blood and nerves in this area, the facility system necessary for proper functioning of the nonexposed lateral lobe is seriously affected. The unexpected volume effect in the rat might have consequences for treatment strategies in radiotherapy, implicating not only salivary glands but also other organs with a seemingly homogeneous distribution of radiosensitive elements, a situation wherein volume effects have not been anticipated up to now.