The proteome microenvironment determines the protective effect of preconditioning in cisplatin-induced acute kidney injury

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The influence of protein solubilisation, conformation and size on the burst release from poly(lactide-co-glycolide) microspheres.

Encapsulation of proteins in poly(lactide-co-glycolide) microspheres via emulsion is known to cause insoluble protein aggregates. Following protein emulsification and encapsulation in PLGA microspheres, we used circular dichroism to show that the recoverable soluble protein fraction also suffers subtle conformational changes. For a panel of proteins selected on the basis of molecular size and structural class, conformational stability measured by chemical denaturation was not indicative of stability during emulsion-encapsulation. Partial loss of structure was observed for alpha-helical proteins released from freeze-dried microspheres in aqueous buffer, with dramatic loss of structure for a beta-sandwich protein. The addition of sucrose (a lyoprotectant) did not prevent the loss of protein conformation upon encapsulation. Therefore, the conformational changes seen for the released soluble protein fraction originates during emulsification rather than microsphere freeze-drying. Analysis of the burst release for all proteins in buffer containing denaturant or surfactant showed that the degree of protein solubilisation was the dominant factor in determining the initial rate and extent of release. Our data for protein release into increasing concentrations of denaturing buffer suggest that the emulsion-denatured protein fraction remains insoluble; this fraction may represent the protein loss encountered upon comparison of protein encapsulated versus protein released.     

Effect of dietary protein level on aflatoxin B1 actions in the liver of weanling rats.

The hepatocarcinogenic responses of rats to aflatoxin B1 (AFB1) are believed to depend on microsomal activation of the toxin, followed by macromolecular binding. Dietary protein insufficiency is reported to reduce the level of microsomal metabolism, and therefore would be expected to reduce the AFB1-induced carcinogenicity. Indeed, diminished hepatocarcinogenicity in low-protein diet fed weanling rats that had received AFB1 has been reported. In the present study, carcinogenicity and other toxic effects of AFB1 (0.5 p.p.m.) fed to weanling male Fischer F344 rats on a low-protein diet (5%) or normal-protein (20%) diet for up to 8 weeks were examined. In our study, in contrast with the previous report, all animals that had survived some initial toxicity were found to have developed hepatic tumors or hyperplastic gamma-glutamyltransferase-positive foci a year later. The low-protein diet also produced sub-acute toxicity after AFB1 exposure in the weanling rats, leading to severe histological changes, and the death of about half the animals after 3-4 weeks of exposure. Animals fed an AFB1-containing normal-protein diet also exhibited AFB1-induced hepatocarcinogenicity, but not the sub-acute toxicity. The levels of hepatic enzymes involved in AFB1 metabolism were examined in animals fed the low- or normal-protein diets in the absence of AFB1. The low-protein diet, fed to 3 week weanlings for the subsequent 5 weeks, decreased hepatic cytochrome P450 levels, as well as the in vitro capacity of microsomal fractions to form AFB1-8,9-dihydrodiol, an index of AFB1-8,9-epoxide formation. Rats on a normal-protein diet did not show these changes. This discrepancy between the observed increase in sub-acute toxicity and decrease in microsomal activities in the low-protein fed animals implies that the toxic effects observed in these rats were not directly related to metabolic activation of the toxin. In contrast to the diminished microsomal in vitro AFB1 activation, however, in vivo AFB1-DNA adduct formation ability in rats receiving the low-protein diet in the absence of AFB1 was found to become elevated more rapidly during the 5 week experimental feeding period, compared with animals receiving the normal-protein diet. This was accompanied by a more rapid fall in the levels of AFB1-glutathione S-transferase isozyme activity in the low-protein fed animals. The results of this study on weanling rats support the importance of AFB1-GSH in protecting against the carcinogenic responses to AFB1, and probably also the sub-acute toxicity of the latter.(ABSTRACT TRUNCATED AT 400 WORDS)     

Amphetamine sensitivity in open-field activity vs. the prepulse inhibition paradigm

Amphetamine-induced mesolimbic dopamine release has been reported to reduce prepulse inhibition of the acoustic startle response. In addition, it is well known that mesolimbic dopamine stimulation leads to hyperactivity. The present study was undertaken to explore the possibility that one or the other measure may be a more sensitive in vivo indicator of dopamine release in the nucleus accumbens by determining if the amphetamine dose-response curves for these two behavioral measures were different. The data indicate that the dose-response curves obtained for the different behavioral measures are identical. These data are consistent with the idea that the same dopamine terminal field supports both prepulse inhibition of the acoustic startle response and dopamine-stimulated hyperactivity.     

Ovarian cysts are common in premenarchal girls: a sonographic study of 101 children 2-12 years old.

Previous studies of sonograms in premenarchal girls have reported the typical ovary to be homogeneous in echogenicity, with cysts an uncommon finding, particularly in children less than 6 years old. These studies found no macrocysts (cysts greater than 9 mm in greatest length) in patients less than 11 years old. This information contradicts published pathology studies and our sonographic experience. The goal of this study was to determine the prevalence of cysts in the ovaries of premenarchal girls. The pelvic sonograms of 101 consecutive premenarchal girls between 2 and 12 years old, without known gynecologic or endocrinologic disease, were prospectively studied. One hundred fifty-five ovaries were adequately imaged in three dimensions. Ovaries were evaluated for the presence or absence of cysts (as defined by sonographic criteria), and the length of the cyst or of the largest cyst, if several were noted, was measured. Cysts were identified in 106 ovaries (68%). Cysts were seen in patients of all ages, particularly in the younger children (2-6 years old). Thirteen of the cysts, noted in 11 patients between 2 and 10 years old, were macrocysts. The typical sonographic appearance of the ovary in premenarchal girls is not homogeneous. Cysts are common in premenarchal girls between 2 and 12 years old and are the cause of the typical heterogeneous image. Macrocysts can be seen in healthy girls less than 11 years old.     

Primary active sodium transport, oxygen consumption, and ATP: coupling and regulation

Several metabolic aspects of primary active transport have been explored in this communication. One emphasized theme entailed the need to investigate the properties of the mitochondria and the active transport systems within the intact cell. Several methodological and conceptual approaches were described that permitted such an analysis. The answers provided were sometimes qualitative or quantitative. Qualitative information was provided regarding the cytosolic signal linking active transport with respiration, suggesting that the cytosolic ADP concentration was an important element in that link. The intact renal cell was found to work normally at 50 to 60% of its maximal respiratory capacity, indicating that sufficient reserve capacity was present for increased metabolic demands. Several examples were described in which a combination of qO2 measurements and/or optical techniques were used to differentiate between effects of agents which act primarily on transport or metabolic events. Finally, the control of transport by metabolism was discussed, primarily emphasizing the role of ATP and Pi. One of the overall conclusions from these studies is that, in general, the mitochondria and the transport systems seem to display similar properties in the intact cell as they do in isolated form. However, uncertainties concerning the cellular microenvironment surrounding the mitochondria and the plasma membrane transporters have produced some interesting surprises concerning their function in the intact cell. More quantitative information on the energy compartmentation of the renal cell would be helpful to clarify numerous aspects of metabolic function.     

Projection of asbestos related diseases in the United States, 1985-2009. I. Cancer.

Projections of asbestos associated cancer mortality in the United States during the 25 year period 1985-2009 were made based on previously published estimates. These estimates were reviewed for malignant mesothelioma, lung cancer, and gastrointestinal cancers. Particular attention was given to the assumptions used in the original derivation of the estimates. For malignant mesothelioma mortality, previous estimates ranged from 15,500 to 300,000. Using recently published data from the Surveillance, Epidemiology, and End Results project, coupled with the previously published estimates, projected asbestos related malignant mesothelioma mortality in the United States for the period 1985-2009 was estimated to be 21,500. For lung cancer, previous estimates were reviewed, particularly with regard to the ratio of deaths from lung cancer to deaths from malignant mesothelioma. Using these ratios, a range of projected deaths was established and a median of those estimates used as a project, which was 76,700 such deaths in the United States between 1985 and 2009. Gastrointestinal cancer mortality has been projected by only three investigators. A median of those estimates (33,000) was used. In conclusion it is estimated that 131,200 deaths from asbestos associated cancer will occur in the United States between 1985 and 2009.