Immune surveillance and neoplasia—II A two-stage mathematical model

In a previous paper (DeLisi and Rescigno, 1977) a model for the interaction of tumor cells and killer lymphocytes was presented. Although that model was highly simplified, the qualitative behavior was in accord with intuitive expectations and a wide range of data. It could not however account forde novo tumor development. In this paper a slightly more realistic model is presented by introducing a delay in the formation of killer lymphocytes. This is done by requiring two stages in the production of a killer. We show that introduction of this second stage allows tumor development from even a single cell, thus removing an important limitation of two variable systems.     

Comparative studies of glutathione reductase and lipoamide dehydrogenase

1. Glutathione reductase and lipoamide dehydrogenase are structurally and mechanistically related flavoenzymes catalyzing various one and two electron transfer reactions between NAD(P)H and substrates with different structures. 2. The two enzymes differ in their coenzyme and functional specificities. Lipoamide dehydrogenase shows higher coenzyme preference while glutathione reductase displays greater functional specificity. 3. Binding preference of the two flavoenzymes for nicotinamide coenzymes is demonstrated by 31P-NMR spectroscopy. 4. The presence of arginines in glutathione reductase which is inactivated by phenyl glyoxal, is likely to be responsible for the NADPH-activity of glutathione reductase. 5. The substrate binding sites of the two enzymes are similar, though their functional details differ. 6. The active-site histidine of glutathione reductase functions primarily as the proton donor during catalysis. While the active-site histidine of lipoamide dehydrogenase stabilizes the thiolate anion intermediate and relays a proton in the catalytic process.     

Platinum complexes with one radiosensitizing ligand [PtCl2(NH3) (sensitizer)]: radiosensitization and toxicity studies in vitro

Complexes of general formula [PtCl2(NH3)L] with one radiosensitizing ligand per platinum are compared with ligand L alone, complexes with two radiosensitizers per platinum [PtCl2L2], and their analogs with NH3 ligands, with respect to radiosensitizing properties and toxicity in CHO cells. Radiosensitizing ligands, L, were misonidazole, metronidazole, 4(5)-nitroimidazole, and 2-amino-5-nitrothiazole, and the ammine analogs were cis- and trans-DDP [diamminedichloroplatinum(II)] and the monoammine, K[PtCl3(NH3)]. Results are related to a previous study on plasmid DNA binding by these series. The toxicity of the mono series [PtCl2(NH3)L], attributable to DNA binding, is much higher than the corresponding bis complexes, [PtCl2L2]. For L = misonidazole, toxicity is similar to the monoammine, but higher in hypoxic than in aerobic cells. trans-[PtCl2(NH3)-(misonidazole)] is more toxic than the cis isomer. Except for L = 4(5)-nitroimidazole, the complexes [PtCl2(NH3)L] are more toxic than L in air and hypoxia. Hypoxic radiosensitization by the mono complexes is comparable to the monoammine and is not better than free sensitizers, again except for L = 4(5)-nitroimidazole. Significantly lower sensitization is observed in oxic cells. The bis complexes [PtCl2L2], which do not bind to DNA as well as the mono complexes, are less effective radiosensitizers and less toxic than the [PtCl2(NH3)L] series.     

The immunostimulatory effect of IL-1β in vivo is blocked by antisense peptides complementary to the loop sequence 163-171

Antisense (AS) peptides complementary to the β-bulge surface loop VQGEESNDK (Boraschi loop) of the cytokine interleukin-1β (IL-1β) have been shown to bind IL-1β at the Boraschi loop position, and to inhibit some of the IL-1β-mediated biological effects in vitro. Here we show that primary AS peptide FVITFFSLY inhibits IL-1β-mediated immunostimulation in vivo in a dose-dependent fashion, while inactive on IL-1β-induced inflammation, an effect that takes place independently of the Boraschi loop. To the best of our knowledge, this is the first time that an AS peptide has been used successfully in vivo.     

The circulatory small non-coding RNA landscape in community-acquired pneumonia on intensive care unit admission

Community-acquired pneumonia (CAP) is a major cause of sepsis. Despite several clinical trials targeting components of the inflammatory response, no specific treatment other than antimicrobial therapy has been approved. This argued for a deeper understanding of sepsis immunopathology, in particular factors that can modulate the host response. Small non-coding RNA, for example, micro (mi)RNA, have been established as important modifiers of cellular phenotypes. Notably, miRNAs are not exclusive to the intracellular milieu but have also been detected extracellular in the circulation with functional consequences. Here, we sought to determine shifts in circulatory small RNA levels of critically ill patients with CAP-associated sepsis and to determine the influence of clinical severity and causal pathogens on small RNA levels. Blood plasma was collected from 13 critically ill patients with sepsis caused by CAP on intensive care unit admission and from 5 non-infectious control participants. Plasma small RNA-sequencing identified significantly altered levels of primarily mature miRNAs in CAP relative to controls. Pathways analysis of high or low abundance miRNA identified various over-represented cellular biological pathways. Analysis of small RNA levels against common clinical severity and inflammatory parameters indices showed direct and indirect correlations. Additionally, variance of plasma small RNA levels in CAP patients may be explained, at least in part, by differences in causal pathogens. Small nuclear RNA levels were specifically altered in CAP due to Influenza infection in contrast to Streptococcus pneumoniae infection. Pathway analysis of plasma miRNA signatures unique to Influenza or Streptococcus pneumoniae infections showed enrichment for specific proteoglycan, cell cycle, and immunometabolic pathways.     

A multinuclear, high-resolution NMR study of bovine casein micelles and submicelles

High-resolution, natural abundance 13C[1H] (100.5 MHz), 31P[1H] (161.8 MHz) and 1H (400.0 MHz) NMR spectroscopy was used to identify the calcium-binding sites of bovine casein and to ascertain the dynamic state of amino acid residues within the casein submicelles (in 125 mM KCl, pD = 7.4) and micelles (in 15 mM CaCl2/80 mM KCl, pD = 7.2). The presence of numerous, well-resolved peaks in the tentatively assigned 13C-NMR spectra of submicelles (90 A radius) and micelles (500 A radius) suggests considerable segmental motion of both side chain and backbone carbons. The partly resolved 31P-NMR spectra concur with this. Upon Ca2+ addition, the phosphoserine beta CH2 resonance (65.8 ppm vs DSS) shifts upfield by 0.2 ppm and is broadened almost beyond detection; a general upfield shift (up to 0.3 ppm) is also observed for the 31P-NMR peaks. The T1 values of the alpha CH envelope for submicelles and micelles are essentially identical corresponding to a correlation time of 8 ns for isotropic rotation of the caseins. Significant changes in the 31P T1 values accompany micelle formation. Data are consistent with a loose and mobile casein structure, with phosphoserines being the predominant calcium-binding sites.     

Postexercise dose-response relationship between plasma glucose and insulin secretion

To investigate whether exertion changes beta-cell reactivity to glucose stimulation and to characterize the beta-cell response to glucose in humans, we performed four sequential 90-min hyperglycemic clamps (7, 11, 20, and 35 mM). Concentrations of hormones and metabolites involved in glucoregulation were measured. Metabolic rate and substrate utilization were studied by indirect calorimetry. Studies were performed without prior exercise, as well as 2 and 48 h after 60 min of bicycle exercise at 150 W. We found 1) a progressive increase in insulin concentrations reaching 1,092 +/- 135 microU/ml with increasing glucose levels, 2) linear relationships between glucose concentrations and concentrations of C-peptide (r = 0.931 +/- 0.008) and proinsulin (r = 0.952 +/- 0.009),3) increased glucose oxidation with increasing glucose uptake, 4) increased plasma norepinephrine, O2 uptake, and beta-hydroxybutyrate at greater than or equal to 20 mM glucose, and 5) no change in beta-cell response or glucose-induced thermogenesis after one bout of exercise despite no compensating changes in plasma concentrations of hormones or metabolites. We conclude that the beta-cell has a very large secretory potential. Secretion of the beta-cell increases linearly with prolonged, graded hyperglycemia. The processing of proinsulin is unchanged during prolonged beta-cell stimulation. In addition, hyperglycemia and sympathetic nervous activity induced by hyperinsulinemia enhance metabolic rate and ketone body production. Finally, a single bout of exercise does not influence either the beta-cell response to intravenous glucose or glucose-induced thermogenesis.     

Prochlorococcus extracellular vesicles: molecular composition and adsorption to diverse microbes

Extracellular vesicles are small (~50–200 nm diameter) membrane-bound structures released by cells from all domains of life. While vesicles are abundant in the oceans, their functions, both for cells themselves and the emergent ecosystem, remain a mystery. To better characterize these particles – a prerequisite for determining function – we analysed the lipid, protein, and metabolite content of vesicles produced by the marine cyanobacterium Prochlorococcus. We show that Prochlorococcus exports a diverse array of cellular compounds into the surrounding seawater enclosed within discrete vesicles. Vesicles produced by two different strains contain some materials in common, but also display numerous strain-specific differences, reflecting functional complexity within vesicle populations. The vesicles contain active enzymes, indicating that they can mediate extracellular biogeochemical reactions in the ocean. We further demonstrate that vesicles from Prochlorococcus and other bacteria associate with diverse microbes including the most abundant marine bacterium, Pelagibacter. Together, our data point toward hypotheses concerning the functional roles of vesicles in marine ecosystems including, but not limited to, possibly mediating energy and nutrient transfers, catalysing extracellular biochemical reactions, and mitigating toxicity of reactive oxygen species.