A Guide to MethylationToActivity: A Deep Learning Framework That Reveals Promoter Activity Landscapes from DNA Methylomes in Individual Tumors

Genome-wide DNA methylomes have contributed greatly to tumor detection and subclassification. However, interpreting the biological impact of the DNA methylome at the individual gene level remains a challenge. MethylationToActivity (M2A) is a pipeline that uses convolutional neural networks to infer H3K4me3 and H3K27ac enrichment from DNA methylomes and thus infer promoter activity. It was shown to be highly accurate and robust in revealing promoter activity landscapes in various pediatric and adult cancers. The following will present a user-friendly guide through the model pipeline.

Abstract PO-046: MethylationToActivity: A deep-learning framework that reveals promoter activity landscapes from DNA methylomes in individual tumors

Although genome-wide DNA methylomes have demonstrated their clinical value as reliable biomarkers for tumor detection, subtyping, and classification, their direct biological impacts at the individual gene level remain elusive. Here we present MethylationToActivity (M2A), a machine learning framework that uses convolutional neural networks to infer promoter activities based on H3K4me3 and H3K27ac enrichment, from DNA methylation patterns for individual genes. Using publicly available datasets in real-world test scenarios, we demonstrate that M2A is highly accurate and robust in revealing promoter activity landscapes in various pediatric and adult cancers, including both solid and hematologic malignant neoplasms.

Citation Format: Justin Williams, Beisi Xu, Daniel Putnam, Andrew Thrasher, Chunliang Li, Jun Yang, Xiang Chen. MethylationToActivity: A deep-learning framework that reveals promoter activity landscapes from DNA methylomes in individual tumors [abstract]. In: Proceedings of the AACR Virtual Special Conference on Artificial Intelligence, Diagnosis, and Imaging; 2021 Jan 13-14. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(5_Suppl):Abstract nr PO-046.

MethylationToActivity: a deep-learning framework that reveals promoter activity landscapes from DNA methylomes in individual tumors

Although genome-wide DNA methylomes have demonstrated their clinical value as reliable biomarkers for tumor detection, subtyping, and classification, their direct biological impacts at the individual gene level remain elusive. Here we present MethylationToActivity (M2A), a machine learning framework that uses convolutional neural networks to infer promoter activities based on H3K4me3 and H3K27ac enrichment, from DNA methylation patterns for individual genes. Using publicly available datasets in real-world test scenarios, we demonstrate that M2A is highly accurate and robust in revealing promoter activity landscapes in various pediatric and adult cancers, including both solid and hematologic malignant neoplasms.

Abstract 6576: DNA methylation reveals alternative promoter usage in genes critical to pediatric tumors

Transcriptional regulation is fundamental for cell identity and function, and it's deregulation is a defining feature for common diseases, including cancers. Besides directly modifying the canonical promoter activities, tumors frequently utilize alternative promoters to increase the isoform diversity, activate oncogenes when the canonical promoters are repressed, and to evade host immune attacks by immune-editing. However, fresh-tissue availability and technical challenges represent major obstacles in genomewide promoter activity assessment in patient tumors by ChIP-seq experiments. Here, we presented MethylToActivity (M2A), a deep-learning framework that reveals promoter activities (H3K4me3 and H3K27ac) from DNA methylation (DNAm) patterns, a relatively stable epigenetic regulatory mechanism that can be robustly and accurately profiled in various tissues, including retrospective tumor samples archived using the formalin-fixed paraffin-embedded (FFPE) method. Trained from a cohort of neuroblastomas (N = 6), we demonstrate that M2A 1) approaches the accuracies of ChIP-seq experiments in revealing promoter activities, 2) is generalizable to various pediatric and adult cancers, 3) captures changes of promoter activity associated with differentially methylated regions, and 4) faithfully recapitulates differential promoter usages among tumor subtypes. Importantly, M2A uncovers oncogenic activation of alternative promoters in genes critical for tumor survival while the canonical promoter remains inactive. These results substantiate that M2A is capable of accurately measuring promoter activities, which will be of great use not only to functionally interpret differential DNAm patterns, but to unveil alternative promoter usages in patient tumors, which will facilitate precision medicine by tailoring treatments based on both epigenetic deregulations and genetic variants.

Citation Format: Justin Williams, Beisi Xu, Daniel Putnam, Xiang Chen. DNA methylation reveals alternative promoter usage in genes critical to pediatric tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6576.

Nucleome Dynamics during Retinal Development

More than 8,000 genes are turned on or off as progenitor cells produce the 7 classes of retinal cell types during development. Thousands of enhancers are also active in the developing retinae, many having features of cell- and developmental stage-specific activity. We studied dynamic changes in the 3D chromatin landscape important for precisely orchestrated changes in gene expression during retinal development by ultra-deep in situ Hi-C analysis on murine retinae. We identified developmental-stage-specific changes in chromatin compartments and enhancer-promoter interactions. We developed a machine learning-based algorithm to map euchromatin and heterochromatin domains genome-wide and overlaid it with chromatin compartments identified by Hi-C. Single-cell ATAC-seq and RNA-seq were integrated with our Hi-C and previous ChIP-seq data to identify cell- and developmental-stage-specific super-enhancers (SEs). We identified a bipolar neuron-specific core regulatory circuit SE upstream of Vsx2, whose deletion in mice led to the loss of bipolar neurons.

Protein accumulation and rumen stability of wheat γ-gliadin fusion proteins in tobacco and alfalfa

The nutritional value of various crops can be improved by engineering plants to produce high levels of proteins. For example, because methionine deficiency limits the protein quality of Medicago Sativa (alfalfa) forage, producing alfalfa plants that accumulate high levels of a methionine-rich protein could increase the nutritional value of that crop. We used three strategies in designing methionine-rich recombinant proteins that could accumulate to high levels in plants and thereby serve as candidates for improving the protein quality of alfalfa forage. In tobacco, two fusion proteins, γ-gliadin-δ-zein and γ-δ-zein, as well as δ-zein co-expressed with β-zein, all formed protein bodies. However, the γ-gliadin-δ-zein fusion protein accumulated to the highest level, representing up to 1.5% of total soluble protein (TSP) in one transformant. In alfalfa, γ-gliadin-δ-zein accumulated to 0.2% of TSP, and in an in vitro rumen digestion assay, γ-gliadin-δ-zein was more resistant to microbial degradation than Rubisco. Additionally, although it did not form protein bodies, a γ-gliadin-GFP fusion protein accumulated to much higher levels, 7% of TSP, than a recombinant protein comprised of an ER localization signal fused to GFP in tobacco. Based on our results, we conclude that γ-gliadin-δ-zein is a potential candidate protein to use for enhancing methionine levels in plants and for improving rumen stability of forage protein. γ-gliadin fusion proteins may provide a general platform for increasing the accumulation of recombinant proteins in transgenic plants.

Effects of Rumen-Protected Choline and Monensin on Milk Production and Metabolism of Periparturient Dairy Cows

Choline and monensin may be supplemented during the transition period with the objectives of aiding in fat metabolism and improving energy balance, respectively. The objectives of this study were to determine the effects of supplementing rumen-protected choline (RPC) and monensin in a controlled-release capsule (CRC) on metabolism, dry matter intake, milk production, and liver function in transition dairy cattle. Three weeks before expected calving, 182 Holsteins were randomly assigned to receive one of the following: a monensin CRC, 56 g/d of RPC until 28 d in milk, CRC + RPC, or neither supplement (control). Blood samples were collected at enrollment, 1 wk before calving, and in the first and second weeks after calving. Liver biopsies were obtained from multiparous cows randomly selected from each treatment group within 24 h and again 3 wk postpartum. Daily milk production was recorded through 60 d in milk. There were no interactions of the effects of RPC and CRC on any of the outcomes measured. Overall, cows that received RPC produced 1.2 kg/d more milk in the first 60 d of lactation, but this effect was attributable to an increase in milk production of 4.4 kg/d among cows with a body condition score > or =4 at 3 wk before calving; fat cows that received RPC ate 1.1 kg of DM/d more from wk 3 before calving through wk 4 after calving. Monensin supplementation significantly increased serum concentrations of glucose and urea, lowered concentrations of beta-hydroxybutyric acid and aspartate aminotransferase in the peripartum period, and increased liver glycogen content at 3 wk into lactation. The metabolic effects of CRC are consistent with previous studies, and the effects on liver are novel. The mechanism by which RPC increased milk production was not revealed in this study and merits further research.

RNA-Interference Effectors and Their Delivery

RNA-interference, the mechanism by which the expression of a specific protein can be reduced or eliminated, has emerged as a potential way to treat disease. RNA-interference effectors, such as small interfering RNA and small hairpin RNA, are double-stranded nucleic acid sequences expressly designed to have homology to sections of the target protein's mRNA, and when present in the cytosol trigger hydrolysis of the mRNA through the RNA-interference pathway. Because RNA-interference effectors are macromolecular and typically polyanionic, their efficacy is poor when not accompanied by a delivery vehicle. This review outlines the RNA-interference mechanism and discusses the delivery of RNA-interference effectors, with an emphasis on synthetic polymer-based delivery systems.

Monocharged inhibitors of mast cell tryptase derived from potent and selective dibasic inhibitors

Truncation of potent and selective dibasic inhibitors afforded monocharged inhibitors of human mast-cell tryptase. Using two classes of analogues as lead structures, several monocharged derivatives were identified with K(i) values ranging from 0.084 to 0.21 microM against the enzyme.

Poly(lactic acid)-poly(ethylene glycol) nanoparticles as new carriers for the delivery of plasmid DNA

The purpose of the present work was to produce and characterize poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) nanoparticles (size lower than 300 nm) containing a high loading of plasmid DNA in a free form or co-encapsulated with either poly(vinyl alcohol) (PVA) or poly(vinylpyrrolidone) (PVP). The plasmid alone or with PVA or PVP was encapsulated by two different techniques: an optimized w/o/w emulsion-solvent evaporation technique as well as by a new w/o emulsion-solvent diffusion technique. Particle size, zeta potential, plasmid DNA loading and in vitro release were determined for the three plasmid-loaded formulations. The influence of the initial plasmid loadings (5, 10, 20 microg plasmid DNA/mg PLA-PEG) on those parameters was also investigated. The plasmid loaded into the nanoparticles and released in vitro was quantified by fluorimetry and the different molecular forms were identified by gel electrophoresis. PLA-PEG nanoparticles containing plasmid DNA in a free form or co-encapsulated with PVA or PVP were obtained in the range size of 150-300 nm and with a negative zeta potential, both parameters being affected by the preparation technique. Encapsulation efficiencies were high irrespective of the presence of PVA or PVP (60-90%) and were slightly affected by the preparation technique and by the initial loading. The final plasmid DNA loading in the nanoparticles was up to 10-12 microg plasmid DNA/mg polymer. Plasmid DNA release kinetics varied depending on the plasmid incorporation technique: nanoparticles prepared by the w/o diffusion technique released their content rapidly whereas those obtained by the w/o/w showed an initial burst followed by a slow release for at least 28 days. No significant influence of the plasmid DNA loading and of the co-encapsulation of PVP or PVA on the in vitro release rate was observed. In all cases the conversion of the supercoiled form to the open circular and linear forms was detected. In conclusion, plasmid DNA can be very efficiently encapsulated, either in a free form or in combination with PVP and PVA, into PLA-PEG nanoparticles. Additionally, depending on the processing conditions, these nanoparticles release plasmid DNA either very rapidly or in a controlled manner.

Dibasic inhibitors of human mast cell tryptase. Part 3: identification of a series of potent and selective inhibitors containing the benzamidine functionality

A survey of charged groups and linkers for a series of symmetrical and unsymmetrical dibasic inhibitors is described, leading to several classes of potent and selective inhibitors. In particular, the benzamidine functionality was identified as the most potent charged group investigated.

Polymer-based gene delivery with low cytotoxicity by a unique balance of side-chain termini

Protein expression after delivery of plasmid DNA to the cell nucleus depends on the processes of transcription and translation. Cytotoxic gene-delivery systems may compromise these processes and limit protein expression. This situation is perhaps most prevalent in current nonviral polycationic gene-delivery systems in which the polycationic nature of the delivery system can lead to cytotoxicity. To approach the problem of creating nontoxic but effective gene-delivery systems, we hypothesized that by optimizing the balance between polymer cationic density with endosomal escape moieties, effective gene transfer with low cytotoxicity could be created. As a model system, we synthesized a series of polymers whose side-chain termini varied with respect to the balance of cationic centers and endosomal escape moieties. Specifically, by polymer-analogous amidation we conjugated imidazole groups to the epsilon-amines of polylysine in varying mole ratios (73.5 mol % imidazole, 82.5 mol % imidazole, and 86.5 mol % imidazole). The primary epsilon-amine terminus of polylysine served as a model for the cationic centers, whereas the imidazole groups served as a model for the endosomal escape moieties. These polymers condensed plasmid DNA into nanostructures <150 nm and possessed little cytotoxicity in vitro. Transfection efficiency, as measured by luciferase protein expression, increased with increasing imidazole content of the polymers in a nonlinear relationship. The polymer with the highest imidazole content (86.5 mol %) mediated the highest protein expression, with levels equal to those mediated by polyethylenimine, but with little to no cytotoxicity.

Dibasic inhibitors of human mast cell tryptase. Part 2: structure-activity relationships and requirements for potent activity

Detailed structure activity relationships (SARs) for a series of dibasic human tryptase inhibitors are presented. The structural requirements for potent inhibitory activity are remarkably broad with a range of core template modifications being well tolerated. Optimized inhibitors demonstrate potent anti-asthmatic activity in a sheep model of allergic asthma. APC-2059, a dibasic tryptase inhibitor with subnanomolar activity, has been advanced to phase II clinical trials for the treatment of both psoriasis and ulcerative colitis.

Dibasic inhibitors of human mast cell tryptase. Part 1: synthesis and optimization of a novel class of inhibitors

The synthesis and optimization of a novel class of reversible and active-site directed dibasic inhibitors of human mast cell tryptase are described. The compounds were shown to be both remarkably potent and selective for tryptase with Ki values for optimized inhibitors in the picomolar range.

Design of imidazole-containing endosomolytic biopolymers for gene delivery

The development of safe and effective gene delivery agents poses a great challenge in the quest to make human gene therapy a reality. Cationic polymers represent one important class of materials for gene delivery, but to date they have shown only moderate efficiency. Improving the efficiency will require the design of new polymers incorporating optimized gene delivery properties. For example, inefficient release of the DNA/polymer complex from endocytic vesicles into the cytoplasm is one of the primary causes of poor gene delivery. Here we report the synthesis of a biocompatible, imidazole-containing polymer designed to overcome this obstacle. DNA/polymer polyplexes incorporating this polymer were shown to have desirable physico-chemical properties for gene delivery and are essentially nontoxic. Using this system, mammalian cells in vitro were transfected in the absence of any exogenous endosomolytic agent such as chloroquine.

Neutrophil myeloperoxidase is a potent and selective inhibitor of mast cell tryptase

Myeloperoxidase (MPO) is an important component of the neutrophil response to microbial infection. In this paper we report an additional activity of MPO, the potent and selective inhibition of human mast cell tryptase. MPO inhibits human mast cell tryptase in a time-dependent manner with an IC50 of 16 nM at 1 h. In contrast, MPO does not inhibit trypsin, thrombin, plasmin, factor Xa, elastase, or cathepsin G. It is the native protein conformation of MPO and not its enzyme activity that is responsible for tryptase inhibition. Heparin, at high concentrations, can prevent the inhibition of tryptase by MPO. We have shown by size-exclusion chromatography that MPO promotes the dissociation of active tryptase tetramer to inactive monomer. These data suggest that MPO inhibits tryptase by interfering with the heparin stabilization of tryptase tetramer. We have previously shown that lactoferrin (another neutrophil-associated protein) also inhibits tryptase activity by a similar mechanism. The finding that MPO is a potent inhibitor of tryptase lends further support to the hypothesis that neutrophil proteins, such as MPO and lactoferrin, may play a regulatory role as endogenous suppressers of tryptase enzyme activity.

PLGA microspheres containing plasmid DNA: preservation of supercoiled DNA via cryopreparation and carbohydrate stabilization

Biodegradable microspheres containing plasmid DNA have potential uses as mediators of transfection in cells, particularly phagocytic cells such as macrophages. However, the hydrophilic nature and the structural instability of supercoiled DNA preclude its facile encapsulation in polymer matrixes such as poly(d, l-lactic-co-glycolic acid) (PLGA) by traditional methods. We initially studied the microencapsulation of plasmid DNA using the established water-in-oil-in-water double-emulsion solvent-evaporation method and found that (1) the encapsulation efficiency was low (about 20%), (2) the microencapsulation procedure nicked (degraded) the supercoiled DNA, and (3) lyophilization of the microsphere also nicked the DNA. We have therefore designed a new microsphere preparation method (called cryopreparation) to specifically address these concerns. Using the cryopreparation method, the aqueous phase of the primary emulsion containing the plasmid DNA is frozen and then subjected to homogenization. Because there is no shear stress inside a solid, we hypothesized that freezing the aqueous phase of the primary emulsion would help to preserve the supercoiled plasmid DNA during formation of the secondary emulsion. We also hypothesized that the formation of crystals from buffers within the primary emulsion was a causative factor for nicking during freezing or lyophilization, and that disruption of the crystal formation by the addition of saccharides into the primary emulsion would improve the supercoiled-DNA content of the spheres. Our results support the two hypotheses. Not only was the supercoiled-DNA content increased from 39% to over 85%, but the encapsulation efficiency was also elevated from 23% to over 85%.

Site-directed mutagenesis of the sodium pump: analysis of mutations to amino acids in the proposed nucleotide binding site by stable oxygen isotope exchange

A model for the active site of P type ATPases has been tested by site-directed mutagenesis of amino acids in two conserved sequences of Mg(2+)-dependent and Na(+)- and K(+)-stimulated ATPase. The mutants K501R, K501E, D586E, D586N, P587A, and P588A were expressed in yeast cells and compared with wild type. In addition to previously published assays of adenosine 5'-triphosphate binding and hydrolysis, measurements of 18O exchange between Pi and water have been used to identify steps in the E2 half of the reaction cycle affected by the mutations. The study supports the prediction that K501 in the KGAP sequence interacts with adenosine 5'-triphosphate. However, quantitative comparisons of the effect of mutation K501E on the activity with the effects of mutations to an enzyme of known structure that also catalyzes phosphoryl group transfer make a direct role for the positive charge on the side chain of K501 in catalysis by stabilizing the transition state unlikely. No evidence for the predicted interaction between D586 and the hydroxyl groups of ribose was found. However, the data do indicate that the spatial organization of the loop containing the DPPR sequence is critical for phosphorylation of the enzyme. A role for D586 in coordinating the Mg2+ that is required for activity is proposed.

Enantioselective release of 5-fluorouracil from N-(2-hydroxypropyl)methacrylamide-based copolymers via lysosomal enzymes

Water soluble copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA) containing oligopeptide side chains terminated in an alpha-substituted glycine derivative of the anticancer compound 5-fluorouracil (5-FU) were synthesized by a new facilitated synthetic route and studied for their ability to release free 5-FU in the presence of lysosomal enzyme preparations. In addition, the properties of the low molecular weight alpha-substituted glycine derivatives were studied in the presence of lysosomal enzyme preparations and leucine aminopeptidase. The results revealed that (1) the stereochemistry (L vs D) of the alpha-substituted glycine derivative, (2) the hydrophobicity (Ala vs Leu) of the penultimate amino acid residue relative to the alpha-substituted glycine derivative, and (3) the total length of the oligopeptide sequence spacer (tetrapeptide vs hexapeptide) terminated in the alpha-substituted glycine derivative and the polymer carrier all directly influence the enzymatically catalyzed release of free 5-FU.

DNA base excision repair of 5-hydroxymethyl-2'-deoxyuridine stimulates poly(ADP-ribose) synthesis in Chinese hamster cells

5-Hydroxymethyl-2'-deoxyuridine (hmdUrd) is incorporated into DNA as a thymidine analog resulting in extensive substitution of thymine residues with 5-hydroxymethyluracil (hmUra) residues. These hmUra residues are then subject to excision by action of hmUra-DNA glycosylase. 3-Aminobenzamide (3AB), an inhibitor of poly(ADP-ribose) synthesis, is toxic to cells that incorporate and repair hmdUrd. To demonstrate that incorporation and repair of hmdUrd stimulates synthesis of poly(ADP-ribose) from intracellular NAD, V79 hamster cells were treated with hmdUrd and intracellular NAD levels were measured. Following hmdUrd treatment, NAD levels fell markedly (80-90%) within 4 h and remained low for at least 10 h, before partially recovering by 24 h. The degree of NAD lowering was dose dependent and paralleled net hmdUrd incorporation. The NAD lowering was largely prevented by concurrent treatment with 4 mM 3AB. No effects on NAD levels were seen following treatment with deoxythymidine or bromodeoxyuridine, which are incorporated into DNA but, in contrast to hmdUrd, are not repaired. When the incorporation of hmdUrd into DNA was blocked with hydroxyurea or aphidicolin, no NAD lowering was seen. HmdUrd also did not produce lowering of NAD concentrations in mutant cell strains deficient in the ability either to incorporate hmdUrd into DNA or to repair hmdUrd from DNA. These results demonstrate that synthesis of poly(ADP-ribose) resulted directly from the incorporation into DNA of the nucleoside hmdUrd and its subsequent repair. These results unequivocally demonstrate that the initiation of normal DNA base excision repair by itself, and not DNA damage per se, is a sufficient stimulus for the induction of poly(ADP-ribose) synthesis.

Superficial temporal-artery aneurysm

We report finding at surgery a histopathologically-confirmed superficial temporal-artery aneurysm. To our knowledge, this is the first report of this type of aneurysm in the ophthalmic literature. The ophthalmologist must include this condition in the differential diagnosis of a pulsatile and tender temporal artery, especially when a history of trauma is present.

Survival and mortality patterns of an acquired immunodeficiency syndrome (AIDS) cohort in New York State

The survival experience and causes of death of acquired immunodeficiency syndrome (AIDS) patients were studied using a cohort of 3,699 AIDS patients in New York State, excluding New York City, whose illness was diagnosed before January 1990 at age 13 years or older. The median length of survival for all cases was 11.5 months, and survival increased over time from 5.3 months pre-1984 to 9.3 months in 1984-1986 and to 13.2 months in 1987-1989. In a Cox proportional hazards model, risk of dying was higher for persons aged 35 years or more at diagnosis and for persons with a diagnosis other than Pneumocystis carinii pneumonia or Kaposi's sarcoma whose illness was diagnosed before 1986. In this AIDS cohort, 2,834 (77 percent) persons died before 1991; 87 percent of the death certificates listed human immunodeficiency virus (HIV)/AIDS or an AIDS indicator disease as one of the multiple causes of death. The finding that 13 percent of the death certificates did not mention AIDS/HIV suggests that use of death certificates alone to count HIV-related deaths would result in an undercount. The recent expansion of the federal AIDS case definition is expected to add HIV-infected persons who die from conditions, such as recurrent pneumonia, that were not included in the earlier definition.

The effect of inpatient psychiatric hospitalization on weight gain in children and adolescents

Measures of weight were obtained both at admission and at discharge for children and adolescents receiving inpatient services at a private psychiatric hospital. The sample included 20 males and 20 females from each of three units: child psychiatric, adolescent psychiatric, and adolescent substance abuse. The difference between the actual weight change of the subjects and the weight change predicted from growth charts was obtained. Overall, subjects gained a significant amount of weight. The actual mean increase in weight was roughly 3.5 times greater than the predicted increase, and there were no significant differences in weight gain between males and females among patients from each of the three units. Potential explanations for this increase in weight are explored, and the implications are discussed.

Differential regulation of Na,K-ATPase alpha 1, alpha 2, and beta subunit mRNA and protein levels by thyroid hormone

The purpose of this study was to determine the effect of thyroid status on the Na,K-ATPase alpha isoforms and beta in rat heart, skeletal muscle, kidney, and brain at the levels of mRNA, protein abundance, and enzymatic activity. Northern and dot-blot analysis of RNA (euthyroid, hypothyroid, and triiodothyronine-injected hypothyroids = hyperthyroids) and immunoblot analysis of protein (euthyroid and hypothyroid) revealed isoform-specific regulation of Na,K-ATPase by thyroid status in kidney, heart, and skeletal muscle and no regulation of sodium pump subunit levels in the brain. In general, in the transition from euthyroid to hypothyroid alpha 1 mRNA and protein levels are unchanged in kidney and skeletal muscle and slightly decreased in heart, while alpha 2 mRNA and protein are decreased significantly in heart and skeletal muscle. In hypothyroid heart and skeletal muscle, the decrease in alpha 2 protein levels was much greater than the decrease in alpha 2 mRNA levels relative to euthyroid indicating translational or post-translational regulation of alpha 2 protein abundance by triiodothyronine status in these tissues. The regulation of beta subunit by thyroid status is tissue-dependent. In hypothyroid kidney beta mRNA levels do not change, but immunodetectable beta protein levels decrease relative to euthyroid, and the decrease parallels the decrease in Na,K-ATPase activity. In hypothyroid heart and skeletal muscle beta mRNA levels decrease; beta protein decreases in heart and was not detected in the skeletal muscle. These findings demonstrate that the euthyroid levels of expression of alpha 1 in heart, alpha 2 in heart and skeletal muscle, and beta in kidney, heart, and skeletal muscle are dependent on the presence of thyroid hormone.

Fluid resuscitation in circulatory shock: a comparison of the cardiorespiratory effects of albumin, hetastarch, and saline solutions in patients with hypovolemic and septic shock

Twenty-six consecutive patients in hypovolemic shock were randomized to fluid challenge with 5% albumin (A), 6% hetastarch (H), or 0.9% saline (S) solutions. Fluid challenge consisted of 250 ml of test fluid every 15 min until the pulmonary artery wedge pressure (WP) reached 15 mm Hg. Thereafter, WP was maintained at 15 mm Hg for an additional 24 h with infusions of the same test fluid. Vital signs, hemodynamic and respiratory variables, as well as arterial lactate and colloid osmotic pressure (COP) were monitored according to protocol. Chest x-rays were performed by standardized technique before fluid challenge and at 12 and 24 h of maintenance fluid therapy and were evaluated for evidence of pulmonary edema. Cardiac function and hemodynamic stability were restored by fluid challenge with A, H, and S. Two to 4 times the volume of S as A or H was required to achieve similar hemodynamic endpoints. COP was increased by fluid challenge with A or H but was markedly reduced by fluid challenge with S and throughout the 24-h maintenance period. Fluid challenge resulted in reductions in COP-WP gradient of 62% in the A, 43% in the H, and 125% in the S groups. Resuscitation with S resulted in a significantly higher incidence of pulmonary edema (87.5%) than did resuscitation with A (22%) or H (22%). Urine output was not different among the groups at any time during the study. We conclude that 6% H performs as well as 5% A as a resuscitative fluid and that resuscitation with either of these colloids is associated with a lower incidence of pulmonary edema than is resuscitation with 0.9% S.

Sequences related to immunoglobulin kappa chain messenger RNA in T cells

We investigated by molecular hybridization whether T cells contain RNA sequences homologous to RNA which codes for immunoglobulin kappa-chain (k-chain). A radioactive probe of complementary DNA (cDNA) was prepared by transcription of purified k-chain mRNA from mouse myeloma MOPC-41 with reverse transcriptase (RNA-dependent-DNA nucleotidyltransferase) from avian myeloblastosis virus. The cDNA probably corresponded only to the constant region and 3'-terminus of k-chain mRNA. Kappa-chain cDNA was found to hybridize efficiently with RNA from both thymus cells and an established culture of thymoma cells. The thymus and thymoma cells contained 99.8% and 100% theta-positive cells, respectively. Quantitatively the average thymus T cell (thymus derived lymphocyte) contained about one half as much k-chain mRNA as the average spleen B cell ("bursa" dependent lymphocyte), whereas the thymoma cells contained only 1/33 as much. Control hybridizations of k-chain cDNA with myeloma and liver RNA support the conclusion that T cells in the thymus and in the thymoma cell line synthesize k-chain mRNA-like molecules. The thermal stability of hybrids of k-chain cDNA with RNA from spleen, thymus, thymoma, and another k-chain producing myeloma tumor was lower than that with MOPC-41 RNA. This finding may be due to the existence of several slightly different ck genes in the mouse as suggested by various control experiments.