Iron(II) supramolecular helicates interfere with the HIV-1 Tat–TAR RNA interaction critical for viral replication

The interaction between the HIV-1 transactivator protein Tat and TAR (transactivation responsive region) RNA, plays a critical role in HIV-1 transcription. Iron(II) supramolecular helicates were evaluated for their in vitro activity to inhibit Tat–TAR RNA interaction using UV melting studies, electrophoretic mobility shift assay, and RNase A footprinting. The results demonstrate that iron(II) supramolecular helicates inhibit Tat-TAR interaction at nanomolar concentrations by binding to TAR RNA. These studies provide a new insight into the biological potential of metallosupramolecular helicates

Contamination by rough microsomes of rat liver mitochondria during poisoning by carbon tetrachloride

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23686/1/0000656.pd

Ultrastructural and biochemical studies on subcellular fractions of chloroquine induced autophagic vacoules

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23658/1/0000626.pd

The effect of 2-methoxyethanol and methoxyacetic acid on sertoli cell lactate production and protein synthesis in vitro

Exposure to 2-methoxyethanol (ME) or its major metabolite, methoxyacetic acid (MA), results in spermatocyte depletion and testicular atrophy in experimental animals. The site of spermatogenesis is within the seminiferous tubule. Sertoli cells support spermatogenesis, synthesizing and secreting proteins, and metabolic substrates for utilization by differentiating germ cells in the seminiferous tubule lumen. One of these substrates, lactate, is preferentially metabolized by spermatocytes. Therefore, because germ cells are dependent upon the metabolic products of Sertoli cells, the effect of ME and MA on production of lactate and protein synthesis was measured in cultured rat Sertoli cells. Cell cultures were incubated with ME or MA at 0, 3, or 10 m for up to 12 hr. No significant difference was seen in total protein synthesis as measured by [3H]leucine incorporation. ME and MA had no apparent effect on cell viability. However, lactate concentrations and rates of lactate accumulation were significantly decreased by MA, but not ME, at both 3 and 10 m following incubation for 6, 9, and 12 hr. The results suggest that inhibition of Sertoli cell lactate production resulting from ME or MA exposure could account for the inhibitory action of these compounds on spermatogenesis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24672/1/0000091.pd

Characterization of chloroquine-induced autophagic vacuoles isolated from rat liver

Studies have been undertaken to investigate the role of cellular autophagy in the accommodation of stress in a biological system. Chloroquine (Aralen hydrochloride), an antimalarial and anti-inflammatory drug, was used to induce autophagy in rat liver. A method is presented which uses differential and discontinuous sucrose gradient centrifugation for the preparation of autophagic vacuole-enriched fractions from rat liver. Ultrastructural studies of the autophagic vacuole fractions showed that the integrity of the autophagic vacuoles was maintained throughout the isolation procedure and that they were morphologically similar to those seen in situ. Assay of glucose-6-phosphatase, NADPH-DCIP reductase, and acid phosphatase confirm the presence of membranes derived from the endoplasmic reticulum, as well as lysosomes, in the autophagic vacuole fractions. The distribution of [14C]-chloroquine suggested a preferential binding of the drug to the autophagic vacuoles may have occurred. These results suggest that cellular autophagy may play an important role in the accommodation of chemically induced alterations in hepatocytes by preferentially sequestering chloroquine, as well as restoring cellular ultrastructure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24464/1/0000739.pd

Binding of carbon tetrachloride metabolites to rat hepatic mitochondrial DNA

Radioactivity from [14C]CCl4 was bound to highly purified mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) prepared from livers of rats after a single dose of [14C]CCl4. At a low, non-necrotizing dose as well as at an acutely toxic dose, mtDNA bound 20-50-fold more radioactivity per mg than did nDNA. Extensive enzymatic digestion and purification of mtDNA did not remove radioactivity. Binding of radioactivity to mtDNA could also be demonstrated after anaerobic incubation of isolated mitochondria with [14C]CCl4, NADPH, ADP, and succinate. Our results suggest that CCl4 can be activated by rat hepatic mitochondrial enzymes to metabolites which bind covalenty to mtDNA.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24743/1/0000165.pd

In vitro effects of 10,10'-oxybisphenoxarsine on isolated rat liver mitochondria

10,10'-Oxybisphenoxarsine (OBPA), a trivalent, heterocyclic organoarsenical, is a potent, broad spectrum antimicrobial agent often incorporated into plasticized polyvinyl chlorides. Although highly toxic, the mechanism of OBPA toxicity is unknown. Since it is hepatotoxic, we investigated the in vitro effects of OBPA on rat liver mitochondria. Isolated mitochondria were incubated with 1 to 8 [mu] OBPA and oxygen consumption was monitored polarographically. State 3 respiration of [alpha]-ketoglutarate, pyruvate, isocitrate, and succinate was rapidly inhibited. OBPA also uncoupled oxidative phosphorylation, although this was masked, at higher concentrations, by progressive respiratory inhibition. The electron transport chain appeared unaffected by OBPA, as measured by NADH oxidation, but several tricarboxcylic acid cycle dehydrogenases were inhibited. This inhibition was prevented and, in some cases, reversed by glutathione. It is likely that OBPA, like other trivalent organoarsenicals, exerts its toxic effects by reacting with vital mitochondrial sulfhydryl groups.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24072/1/0000324.pd

Protein synthesis by hepatic mitochondria isolated from carbon tetrachloride-exposed rats

Hepatic mitochondria isolated from rats 40 h after dosage with 1.1 ml/kg CCl4 are uncoupled and display structural damage. Mitochondrial function returns during hepatic recovery. Because the products of mitochondrial protein synthesis are essential to mitochondrial structure and function, the effects of CCl4 on the rate of mitochondrial protein synthesis, and on the products, was studied using mitochondria from CCl4-exposed rats during the early, maximum development and resolution stages of CCl4-induced mitochondrial damage. Rates of mitochondrial protein synthesis (incorporation of [35S]methionine) were elevated 300% over that of mitochondria from non-exposed rats 17 h after exposure; depressed by 50% at 40 h and above control at 113 h. When the radiolabeled products of incorporation were separated and examined by autoradiography, a novel, low-molecular-weight band, of approx. 9700, was apparent 40 h after CCl4 exposure. A band of similar molecular weight appeared when control mitochondria were incubated without an exogenous supply of ATP. Mitochondria from exposed rats which displayed rates of protein synthesis greater than control consistently had a relative increase in a band that corresponded in size to that of cytochrome oxidase subunit I. It was concluded that the loss of mitochondrial function induced by CCl4 could not be attributed to inhibition of mitochondrial protein synthesis, and that the mitochondria may not always synthesize protein in constant proportions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25736/1/0000293.pd

Carbon tetrachloride depresses hepatic phospholipid synthesis in rats

40 h after an acute dose of CCl4 (11.3 mmol/kg), the incorporation of [1-3H]ethanolamine into rat hepatic microsomal phospholipids was inhibited to 70% of control. Incorporation into phospholipids of the inner and outer mitochondrial membranes was 30-35% of control. Rates of incorporation were equal to or above normal rates in all membranes 65 h after dosage. The activity of methyltransferase in microsomal fractions isolated from rats 10 to 66 h after dosage was depressed. These data suggest that the alteration of mitochondrial phospholipids that parallels mitochondrial dysfunction after acute CCl4 dosage could be attributed to a CCl4-induced inhibition of the microsomal phospholipid biosynthetic pathways.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25820/1/0000383.pd

Guidelines for Material Design in Semitransparent Organic Solar Cells

Organic solar cells (OSCs) are uniquely suited for semitransparent applications due to their adjustable absorption spectrum. However, most high-performance semitransparent cells reported to date are based on materials that have shown high power conversion efficiency for opaque devices. We therefore present a model to assess the optimum efficiency and transparency for a specific donor and acceptor band gap. The absorption characteristics of both donor and acceptor are modeled with spectral data of typical absorber materials from the literature which are adjusted to achieve the desired band gap value. The results show three distinct regions of high light utilization efficiency if the photopic curve is employed as a weighting function (corresponding to window applications), and a broad maximum for the plant action spectrum as a weighting function (corresponding to greenhouse applications). When comparing these findings to reported experimental values, it is evident that the band gaps of the materials used for the experimental studies do not correspond to the maxima identified by our simulation model. The analysis of the energy levels of molecules recorded in the literature confirms that all band gaps and therefore all LUE maxima are chemically feasible so that the performance of semitransparent OSCs can be further improved by designing materials with optimized absorption spectra.Comment: 20 pages and 10 figure in the main manuscript, aditionally 6 pages and 4 figures in the supporting informatio