Later stages of regeneration in the Polychaete, Nephtys

The sequence of events in posterior regeneration of the polychaete, Nephtys, has been examined in histological preparations from the fifth day to the end of the third week after amputation, that is from the time when wound healing is complete until several new segments are differentiated. The pygidium forms and begins to differentiate prior to segmentation. The first indication of each new segment is the appearance of a large pair of segmental blood vessels which arise from the vascular complex in the gut wall. Associated with these are fibroblasts, the anlagen of the new septum. Epidermal derivatives develop subsequently, appearing first ventrolaterally, close to the regenerating nerve cord. The mitotic rate appears to be highest prior to the period of maximum segment formation. Visible cell differentation follows, and subsequent growth of segments is primarily by cell enlargement. It appears likely that the blood-vascular system associated with the gut and the regenerating nerve cord, both of which are disproportionately large in the regenerate, are important for the initiation of new segments.     

Photoreactions of human lens monomeric crystallins

Human lens beta s- and gamma A-crystallins exhibit very similar tryptophan fluorescence emission maxima (329 nm). gamma A isolated from infant human lenses is photo-oxidized by 300 nm irradiation and forms water-insoluble aggregates; beta s or gamma A from young human lenses form a small amount of water-soluble crosslinked species. At least part of the mechanism of photodamage by 300 nm irradiation is photogeneration of the oxidant H2O2 via the generation of O2- radical, this reaction occurs via photosensitization by the tryptophan photo-oxidation product N-formylkynurenine (N-FK) or related species. These results indicate that even though the tryptophan residues of beta s- and gamma A-crystallins are in hydrophobic (buried) microenvironments as compared to those of the alpha- and beta-crystallins, the photogeneration of N-FK is sufficient to produce O2- and H2O2.     

Epinephrine-mediated stimulation of glucose uptake and lactate release by the perfused rat heart. Evidence for alpha- and beta-adrenergic mechanisms

Epinephrine treatment of the perfused rat heart led to an increase in the rate of glucose uptake and lactate release as well as increases in the rate of beating and the activity ratio of phosphofructokinase. The dose of epinephrine required for half maximal increases in the rate of beating, and glucose uptake and the activity ratio of phosphofructokinase was approx.10^?7M. Glucose uptake, lactate release and the activity ratio of phosphofructokinase were increased by the α-agonists methoxamine and phenylephrine, and the β agonist, isoproterenol. Propranolol and phenoxybenzamine each partially blocked the stimulatory effects of epinephrine on glucose uptake and lactate production. Phenoxybenzamine blocked the stimulatory effects of methoxamine but had no effect on those produced by isoproterenol which were blocked by propranolol. It is concluded that dual α and β adrenergic control of glycolysis occurs in cardiac muscle. It is proposed that the previously reported α-adrenergic control of phosphofructokinase plays a key role in the control of heart muscle glycolysis.     

Studies of enzyme polymorphisms in the Kamuela population of Drosophila mercatorum. II. Evaluation of glycolytic intermediates

A simple and effective cryogenic procedure for the extraction of glycolytic intermediates from whole Drosophila has been developed. This procedure gives consistent results when a measure (µM/liter/OD₂₆₀) is adopted which corrects for differences in extraction efficiency. Using this measure and a homozygous strain of D. mercatorum, there are no significant differences among extracts for the levels of any of the 15 glycolytic intermediate or energy molecules considered. The profile of means is consistent across experimental designs and instrument types. Coefficients of variation are well below 50% for most variables. The methodology presented has the statistical power to detect a mean change of 10 to 50% using an experimental design which requires as few as 32 observations. The estimated energy charge for resting Drosophila from these studies is the expected value of 0.86.     

Oxidant membrane injury by the neutrophil myeloperoxidase system. II. Injury by stimulated neutrophils and protection by lipid-soluble antioxidants

The stimulated human neutrophil can damage a variety of target cells, and in some models, a mechanism involving secretion of myeloperoxidase and H2O2 has been demonstrated. We explored the characteristics of this cell-cell interaction by using neutrophils and our recently described liposome model target cell system. Exposure of 51Cr-labeled liposomes to phorbol myristate acetate-stimulated human neutrophils resulted in release of 25 to 30% of the radioactivity. 51Cr release was abrogated by omission of the neutrophils, the phorbol ester or halide (iodide), replacement of the phorbol by an inactive congener, or addition of azide, cyanide, or catalase. Neutrophils from patients with hereditary absence of myeloperoxidase (MPO) or a failure of H2O2 formation (chronic granulomatous disease) did not cause liposome lysis unless purified MPO or a source of H2O2, respectively, was added. These data indicate that 51Cr release from liposomes is a consequence of the secretion of MPO and H2O2, which combine with extracellular halides to form a membrane lytic system. The influence of liposome composition on injury was then examined, with a focus on physiologically relevant lipid soluble antioxidants. Liposomes containing either alpha-tocopherol (0.33 to 1.67% of molar fraction of lipid) or beta-carotene (1.67% of molar fraction of lipid) were markedly resistant to lysis by the cellfree MPO-H2O2-chloride system. When the major structural lipid phosphatidyl choline was replaced by dipalmitoyl phosphatidyl choline, a synthetic phospholipid with no oxidizable double bonds, the resultant liposomes were totally resistant to lysis by the MPO-H2O2-chloride system. The addition of iodide to this system (i.e., both chloride and iodide present) changed the pattern of protection dramatically in that alpha-tocopherol and beta-carotene were no longer protective and the resistance of dipalmitoyl phosphatidyl choline liposomes was partial rather than complete. In contrast to iodide, the addition of bromide or thiocyanate did not have a major effect on the protection by antioxidants. Finally, we demonstrated protection by alpha-tocopherol or dipalmitoyl phosphatidyl choline against liposome lysis by phorbol-activated neutrophils. These studies illustrate the use of model phospholipid membranes in the characterization of oxygen-dependent cell-mediated cytotoxicity. Activated neutrophils lyse liposome targets through a MPO-dependent mechanism. Target properties, especially the content of lipid-soluble antioxidants, have a marked influence on susceptibility to lysis.(ABSTRACT TRUNCATED AT 400 WORDS)