Oceanic protection of prebiotic organic compounds from UV radiation

It is frequently stated that UV light would cause massive destruction of prebiotic organic compounds because of the absence of an ozone layer. The elevated UV flux of the early sun compounds this problem. This applies to organic compounds of both terrestrial and extraterrestrial origin. Attempts to deal with this problem generally involve atmospheric absorbers. We show here that prebiotic organic polymers as well as several inorganic compounds are sufficient to protect oceanic organic molecules from UV degradation. This aqueous protection is in addition to any atmospheric UV absorbers and should be a ubiquitous planetary phenomenon serving to increase the size of planetary habitable zones.

Vaccination for protection of retinal ganglion cells against death from glutamate cytotoxicity and ocular hypertension: Implications for glaucoma

Our group recently demonstrated that autoimmune T cells directed against central nervous system-associated myelin antigens protect neurons from secondary degeneration. We further showed that the synthetic peptide copolymer 1 (Cop-1), known to suppress experimental autoimmune encephalomyelitis, can be safely substituted for the natural myelin antigen in both passive and active immunization for neuroprotection of the injured optic nerve. Here we attempted to determine whether similar immunizations are protective from retinal ganglion cell loss resulting from a direct biochemical insult caused, for example, by glutamate (a major mediator of degeneration in acute and chronic optic nerve insults) and in a rat model of ocular hypertension. Passive immunization with T cells reactive to myelin basic protein or active immunization with myelin oligodendrocyte glycoprotein-derived peptide, although neuroprotective after optic nerve injury, was ineffective against glutamate toxicity in mice and rats. In contrast, the number of surviving retinal ganglion cells per square millimeter in glutamate-injected retinas was significantly larger in mice immunized 10 days previously with Cop-1 emulsified in complete Freund's adjuvant than in mice injected with PBS in the same adjuvant (2,133 ± 270 and 1,329 ± 121, respectively, mean ± SEM; P < 0.02). A similar pattern was observed when mice were immunized on the day of glutamate injection (1,777 ± 101 compared with 1,414 ± 36; P < 0.05), but not when they were immunized 48 h later. These findings suggest that protection from glutamate toxicity requires reinforcement of the immune system by antigens that are different from those associated with myelin. The use of Cop-1 apparently circumvents this antigen specificity barrier. In the rat ocular hypertension model, which simulates glaucoma, immunization with Cop-1 significantly reduced the retinal ganglion cell loss from 27.8% ± 6.8% to 4.3% ± 1.6%, without affecting the intraocular pressure. This study may point the way to a therapy for glaucoma, a neurodegenerative disease of the optic nerve often associated with increased intraocular pressure, as well as for acute and chronic degenerative disorders in which glutamate is a prominent participant.

Protection of nonobese diabetic mice from autoimmune diabetes by reduction of islet mass before insulitis.

Nonobese diabetic mice spontaneously develop diabetes that is caused by autoimmune cell-mediated destruction of pancreatic beta cells. Here we report that surgical removal of 90% of pancreatic tissue before onset of insulitis induced a long-term diabetes-free condition in nonobese diabetic mice. Pancreatectomy after development of moderate insulitis had no effect on the course of diabetes. The effect of pancreatectomy was abrogated with subsequent development of diabetes by infusion of islet-cell-specific T lymphocytes and by transplantation of pancreatic islets. Lymphocytes from pancreatectomized diabetes-free mice exhibited low response to islet cells but responded normally to alloantigens. These results suggest that the islet cell mass plays a critical role in development of autoimmune diabetes.

Functional protection of dystrophic mouse (mdx) muscles after adenovirus-mediated transfer of a dystrophin minigene.

Fast skeletal muscles of mdx (X chromosome-linked muscular dystrophy) mice were injected after birth with a recombinant adenovirus containing a minidys- trophin gene, a 6.3-kbp cDNA coding for the N- and C-terminal ends of dystrophin. Adult muscles were challenged by forced lengthening during tetanic contractions. Stretch-induced mechanical and histological damages were much reduced in injected muscles, in direct proportion of the Miniber of fibers expressing minidystrophin. Damaged fibers were preferentially found among minidystrophin-negative regions. Minidystrostrophin confers an important functional and structural protection of limb muscles against high mechanical stress, even after a partial somatic gene transfer.

Protection of nonobese diabetic mice from diabetes by intranasal or subcutaneous administration of insulin peptide B-(9-23).

The observation that overt type I diabetes is often preceded by the appearance of insulin autoantibodies and the reports that prophylactic administration of insulin to biobreeding diabetes-prone (BB-DP) rats, nonobese diabetic (NOD) mice, and human subjects results in protection from diabetes suggest that an immune response to insulin is involved in the process of beta cell destruction. We have recently reported that islet-infiltrating cells isolated from NOD mice are enriched for insulin-specific T cells, that insulin-specific T cell clones are capable of adoptive transfer of diabetes, and that epitopes present on residues 9-23 of the B chain appear to be dominant in this spontaneous response. In the experiments described in this report, the epitope specificity of 312 independently isolated insulin-specific T cell clones was determined and B-(9-23) was found to be dominant, with 93% of the clones exhibiting specificity toward this peptide and the remainder to an epitope on residues 7-21 of the A chain. On the basis of these observations, the effect of either subcutaneous or intranasal administration of B-(9-23) on the incidence of diabetes in NOD mice was determined. The results presented here indicate that both subcutaneous and intranasal administration of B-(9-23) resulted in a marked delay in the onset and a decrease in the incidence of diabetes relative to mice given the control peptide, tetanus toxin-(830-843). This protective effect is associated with reduced T-cell proliferative response to B-(9-23) in B-(9-23)-treated mice.

Phosphinate analogs of D-, D-dipeptides: slow-binding inhibition and proteolysis protection of VanX, a D-, D-dipeptidase required for vancomycin resistance in Enterococcus faecium.

VanX is a D-Ala-D-Ala dipeptidase that is essential for vancomycin resistance in Enterococcus faecium. Contrary to most proteases and peptidases, it prefers to hydrolyze the amino substrate but not the related kinetically and thermodynamically more favorable ester substrate D-Ala-D-lactate. The enzymatic activity of VanX was previously found to be inhibited by the phosphinate analogs of the proposed tetrahedral intermediate for hydrolysis of D-Ala-D-Ala. Here we report that such phosphinates are slow-binding inhibitors. D-3-[(1-Aminoethyl)phosphinyl]-D-2-methylpropionic acid I showed a time-dependent onset of inhibition of VanX and a time-dependent return to uninhibited steady-state rates upon dilution of the enzyme/inhibitor mixture. The initial inhibition constant Ki after immediate addition of VanX to phosphinate I to form the E-I complex is 1.5 microM but is then lowered by a relatively slow isomerization step to a second complex, E-I*, with a final K*i of 0.47 microM. This slow-binding inhibition reflects a Km/K*i ratio of 2900:1. The rate constant for the slow dissociation of complex E-I* is 0.24 min-1. A phosphinate analog with an ethyl group replacing what would be the side chain of the second D-alanyl residue in the normal tetrahedral adduct gives a K*i value of 90 nM. Partial proteolysis of VanX reveals two protease-sensitive loop regions that are protected by the intermediate analog phosphinate, indicating that they may be part of the VanX active site.

Synthesis and targeted delivery of an azidothymidine homodinucleotide conferring protection to macrophages against retroviral infection.

The infectivity and replication of human (HIV-1), feline (FIV), and murine (LP-BM5) immunodeficiency viruses are all inhibited by several nucleoside analogues after intracellular conversion to their triphosphorylated derivatives. At the cellular level, the main problems in the use of these drugs concern their limited phosphorylation in some cells (e.g., macrophages) and the cytotoxic side effects of nucleoside analogue triphosphates. To overcome these limitations a new nucleoside analogue homodinucleotide, di(thymidine-3'-azido-2',3'-dideoxy-D-riboside)-5'-5'-p1-p2-pyrophosphat e (AZTp2AZT), was designed and synthesized. AZTp2AZT was a poor in vitro inhibitor of HIV reverse transcriptase, although it showed antiviral and cytotoxic activities comparable to those of the parent AZT when added to cultures of a HTLV-1 transformed cell line. AZTp2AZT encapsulated into erythrocytes was remarkably stable. Induction of erythrocyte-membrane protein clusterization and subsequent phagocytosis of AZTp2AZT-loaded cells allowed the targeted delivery of this impermeant drug to macrophages where its metabolic activation occurs. The addition of AZTp2AZT-loaded erythrocytes to human, feline, and murine macrophages afforded almost complete in vitro protection of these cells from infection by HIVBa-L, FIV, and LP-BM5, respectively. Therefore, AZTp2AZT, unlike the membrane-diffusing azidothymidine, acts as a very efficient antiretroviral prodrug following selective targeting to macrophages by means of loaded erythrocytes.

Pharmacological modulation of heat shock factor 1 by antiinflammatory drugs results in protection against stress-induced cellular damage.

The activation of heat shock genes by diverse forms of environmental and physiological stress has been implicated in a number of human diseases, including ischemic damage, reperfusion injury, infection, neurodegeneration, and inflammation. The enhanced levels of heat shock proteins and molecular chaperones have broad cytoprotective effects against acute lethal exposures to stress. Here, we show that the potent antiinflammatory drug indomethacin activates the DNA-binding activity of human heat shock transcription factor 1 (HSF1). Perhaps relevant to its pharmacological use, indomethacin pretreatment lowers the temperature threshold of HSF1 activation, such that a complete heat shock response can be attained at temperatures that are by themselves insufficient. The synergistic effect of indomethacin and elevated temperature is biologically relevant and results in the protection of cells against exposure to cytotoxic conditions.